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linux/kernel/bpf/btf.c
Fedor Tokarev 58250ae350 bpf: btf: Fix vsnprintf return value check 
vsnprintf returns the number of characters which would have been written if
enough space had been available, excluding the terminating null byte. Thus,
the return value of 'len_left' means that the last character has been
dropped.

Signed-off-by: Fedor Tokarev <ftokarev@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20220711211317.GA1143610@laptop
2022-07-29 09:57:14 -07:00

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// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2018 Facebook */
#include <uapi/linux/btf.h>
#include <uapi/linux/bpf.h>
#include <uapi/linux/bpf_perf_event.h>
#include <uapi/linux/types.h>
#include <linux/seq_file.h>
#include <linux/compiler.h>
#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include <linux/file.h>
#include <linux/uaccess.h>
#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/sort.h>
#include <linux/bpf_verifier.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/skmsg.h>
#include <linux/perf_event.h>
#include <linux/bsearch.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <net/sock.h>
#include "../tools/lib/bpf/relo_core.h"
/* BTF (BPF Type Format) is the meta data format which describes
* the data types of BPF program/map. Hence, it basically focus
* on the C programming language which the modern BPF is primary
* using.
*
* ELF Section:
* ~~~~~~~~~~~
* The BTF data is stored under the ".BTF" ELF section
*
* struct btf_type:
* ~~~~~~~~~~~~~~~
* Each 'struct btf_type' object describes a C data type.
* Depending on the type it is describing, a 'struct btf_type'
* object may be followed by more data. F.e.
* To describe an array, 'struct btf_type' is followed by
* 'struct btf_array'.
*
* 'struct btf_type' and any extra data following it are
* 4 bytes aligned.
*
* Type section:
* ~~~~~~~~~~~~~
* The BTF type section contains a list of 'struct btf_type' objects.
* Each one describes a C type. Recall from the above section
* that a 'struct btf_type' object could be immediately followed by extra
* data in order to describe some particular C types.
*
* type_id:
* ~~~~~~~
* Each btf_type object is identified by a type_id. The type_id
* is implicitly implied by the location of the btf_type object in
* the BTF type section. The first one has type_id 1. The second
* one has type_id 2...etc. Hence, an earlier btf_type has
* a smaller type_id.
*
* A btf_type object may refer to another btf_type object by using
* type_id (i.e. the "type" in the "struct btf_type").
*
* NOTE that we cannot assume any reference-order.
* A btf_type object can refer to an earlier btf_type object
* but it can also refer to a later btf_type object.
*
* For example, to describe "const void *". A btf_type
* object describing "const" may refer to another btf_type
* object describing "void *". This type-reference is done
* by specifying type_id:
*
* [1] CONST (anon) type_id=2
* [2] PTR (anon) type_id=0
*
* The above is the btf_verifier debug log:
* - Each line started with "[?]" is a btf_type object
* - [?] is the type_id of the btf_type object.
* - CONST/PTR is the BTF_KIND_XXX
* - "(anon)" is the name of the type. It just
* happens that CONST and PTR has no name.
* - type_id=XXX is the 'u32 type' in btf_type
*
* NOTE: "void" has type_id 0
*
* String section:
* ~~~~~~~~~~~~~~
* The BTF string section contains the names used by the type section.
* Each string is referred by an "offset" from the beginning of the
* string section.
*
* Each string is '\0' terminated.
*
* The first character in the string section must be '\0'
* which is used to mean 'anonymous'. Some btf_type may not
* have a name.
*/
/* BTF verification:
*
* To verify BTF data, two passes are needed.
*
* Pass #1
* ~~~~~~~
* The first pass is to collect all btf_type objects to
* an array: "btf->types".
*
* Depending on the C type that a btf_type is describing,
* a btf_type may be followed by extra data. We don't know
* how many btf_type is there, and more importantly we don't
* know where each btf_type is located in the type section.
*
* Without knowing the location of each type_id, most verifications
* cannot be done. e.g. an earlier btf_type may refer to a later
* btf_type (recall the "const void *" above), so we cannot
* check this type-reference in the first pass.
*
* In the first pass, it still does some verifications (e.g.
* checking the name is a valid offset to the string section).
*
* Pass #2
* ~~~~~~~
* The main focus is to resolve a btf_type that is referring
* to another type.
*
* We have to ensure the referring type:
* 1) does exist in the BTF (i.e. in btf->types[])
* 2) does not cause a loop:
* struct A {
* struct B b;
* };
*
* struct B {
* struct A a;
* };
*
* btf_type_needs_resolve() decides if a btf_type needs
* to be resolved.
*
* The needs_resolve type implements the "resolve()" ops which
* essentially does a DFS and detects backedge.
*
* During resolve (or DFS), different C types have different
* "RESOLVED" conditions.
*
* When resolving a BTF_KIND_STRUCT, we need to resolve all its
* members because a member is always referring to another
* type. A struct's member can be treated as "RESOLVED" if
* it is referring to a BTF_KIND_PTR. Otherwise, the
* following valid C struct would be rejected:
*
* struct A {
* int m;
* struct A *a;
* };
*
* When resolving a BTF_KIND_PTR, it needs to keep resolving if
* it is referring to another BTF_KIND_PTR. Otherwise, we cannot
* detect a pointer loop, e.g.:
* BTF_KIND_CONST -> BTF_KIND_PTR -> BTF_KIND_CONST -> BTF_KIND_PTR +
* ^ |
* +-----------------------------------------+
*
*/
#define BITS_PER_U128 (sizeof(u64) * BITS_PER_BYTE * 2)
#define BITS_PER_BYTE_MASK (BITS_PER_BYTE - 1)
#define BITS_PER_BYTE_MASKED(bits) ((bits) & BITS_PER_BYTE_MASK)
#define BITS_ROUNDDOWN_BYTES(bits) ((bits) >> 3)
#define BITS_ROUNDUP_BYTES(bits) \
(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))
#define BTF_INFO_MASK 0x9f00ffff
#define BTF_INT_MASK 0x0fffffff
#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)
#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
/* 16MB for 64k structs and each has 16 members and
* a few MB spaces for the string section.
* The hard limit is S32_MAX.
*/
#define BTF_MAX_SIZE (16 * 1024 * 1024)
#define for_each_member_from(i, from, struct_type, member) \
for (i = from, member = btf_type_member(struct_type) + from; \
i < btf_type_vlen(struct_type); \
i++, member++)
#define for_each_vsi_from(i, from, struct_type, member) \
for (i = from, member = btf_type_var_secinfo(struct_type) + from; \
i < btf_type_vlen(struct_type); \
i++, member++)
DEFINE_IDR(btf_idr);
DEFINE_SPINLOCK(btf_idr_lock);
enum btf_kfunc_hook {
BTF_KFUNC_HOOK_XDP,
BTF_KFUNC_HOOK_TC,
BTF_KFUNC_HOOK_STRUCT_OPS,
BTF_KFUNC_HOOK_TRACING,
BTF_KFUNC_HOOK_SYSCALL,
BTF_KFUNC_HOOK_MAX,
};
enum {
BTF_KFUNC_SET_MAX_CNT = 32,
BTF_DTOR_KFUNC_MAX_CNT = 256,
};
struct btf_kfunc_set_tab {
struct btf_id_set8 *sets[BTF_KFUNC_HOOK_MAX];
};
struct btf_id_dtor_kfunc_tab {
u32 cnt;
struct btf_id_dtor_kfunc dtors[];
};
struct btf {
void *data;
struct btf_type **types;
u32 *resolved_ids;
u32 *resolved_sizes;
const char *strings;
void *nohdr_data;
struct btf_header hdr;
u32 nr_types; /* includes VOID for base BTF */
u32 types_size;
u32 data_size;
refcount_t refcnt;
u32 id;
struct rcu_head rcu;
struct btf_kfunc_set_tab *kfunc_set_tab;
struct btf_id_dtor_kfunc_tab *dtor_kfunc_tab;
/* split BTF support */
struct btf *base_btf;
u32 start_id; /* first type ID in this BTF (0 for base BTF) */
u32 start_str_off; /* first string offset (0 for base BTF) */
char name[MODULE_NAME_LEN];
bool kernel_btf;
};
enum verifier_phase {
CHECK_META,
CHECK_TYPE,
};
struct resolve_vertex {
const struct btf_type *t;
u32 type_id;
u16 next_member;
};
enum visit_state {
NOT_VISITED,
VISITED,
RESOLVED,
};
enum resolve_mode {
RESOLVE_TBD, /* To Be Determined */
RESOLVE_PTR, /* Resolving for Pointer */
RESOLVE_STRUCT_OR_ARRAY, /* Resolving for struct/union
* or array
*/
};
#define MAX_RESOLVE_DEPTH 32
struct btf_sec_info {
u32 off;
u32 len;
};
struct btf_verifier_env {
struct btf *btf;
u8 *visit_states;
struct resolve_vertex stack[MAX_RESOLVE_DEPTH];
struct bpf_verifier_log log;
u32 log_type_id;
u32 top_stack;
enum verifier_phase phase;
enum resolve_mode resolve_mode;
};
static const char * const btf_kind_str[NR_BTF_KINDS] = {
[BTF_KIND_UNKN] = "UNKNOWN",
[BTF_KIND_INT] = "INT",
[BTF_KIND_PTR] = "PTR",
[BTF_KIND_ARRAY] = "ARRAY",
[BTF_KIND_STRUCT] = "STRUCT",
[BTF_KIND_UNION] = "UNION",
[BTF_KIND_ENUM] = "ENUM",
[BTF_KIND_FWD] = "FWD",
[BTF_KIND_TYPEDEF] = "TYPEDEF",
[BTF_KIND_VOLATILE] = "VOLATILE",
[BTF_KIND_CONST] = "CONST",
[BTF_KIND_RESTRICT] = "RESTRICT",
[BTF_KIND_FUNC] = "FUNC",
[BTF_KIND_FUNC_PROTO] = "FUNC_PROTO",
[BTF_KIND_VAR] = "VAR",
[BTF_KIND_DATASEC] = "DATASEC",
[BTF_KIND_FLOAT] = "FLOAT",
[BTF_KIND_DECL_TAG] = "DECL_TAG",
[BTF_KIND_TYPE_TAG] = "TYPE_TAG",
[BTF_KIND_ENUM64] = "ENUM64",
};
const char *btf_type_str(const struct btf_type *t)
{
return btf_kind_str[BTF_INFO_KIND(t->info)];
}
/* Chunk size we use in safe copy of data to be shown. */
#define BTF_SHOW_OBJ_SAFE_SIZE 32
/*
* This is the maximum size of a base type value (equivalent to a
* 128-bit int); if we are at the end of our safe buffer and have
* less than 16 bytes space we can't be assured of being able
* to copy the next type safely, so in such cases we will initiate
* a new copy.
*/
#define BTF_SHOW_OBJ_BASE_TYPE_SIZE 16
/* Type name size */
#define BTF_SHOW_NAME_SIZE 80
/*
* Common data to all BTF show operations. Private show functions can add
* their own data to a structure containing a struct btf_show and consult it
* in the show callback. See btf_type_show() below.
*
* One challenge with showing nested data is we want to skip 0-valued
* data, but in order to figure out whether a nested object is all zeros
* we need to walk through it. As a result, we need to make two passes
* when handling structs, unions and arrays; the first path simply looks
* for nonzero data, while the second actually does the display. The first
* pass is signalled by show->state.depth_check being set, and if we
* encounter a non-zero value we set show->state.depth_to_show to
* the depth at which we encountered it. When we have completed the
* first pass, we will know if anything needs to be displayed if
* depth_to_show > depth. See btf_[struct,array]_show() for the
* implementation of this.
*
* Another problem is we want to ensure the data for display is safe to
* access. To support this, the anonymous "struct {} obj" tracks the data
* object and our safe copy of it. We copy portions of the data needed
* to the object "copy" buffer, but because its size is limited to
* BTF_SHOW_OBJ_COPY_LEN bytes, multiple copies may be required as we
* traverse larger objects for display.
*
* The various data type show functions all start with a call to
* btf_show_start_type() which returns a pointer to the safe copy
* of the data needed (or if BTF_SHOW_UNSAFE is specified, to the
* raw data itself). btf_show_obj_safe() is responsible for
* using copy_from_kernel_nofault() to update the safe data if necessary
* as we traverse the object's data. skbuff-like semantics are
* used:
*
* - obj.head points to the start of the toplevel object for display
* - obj.size is the size of the toplevel object
* - obj.data points to the current point in the original data at
* which our safe data starts. obj.data will advance as we copy
* portions of the data.
*
* In most cases a single copy will suffice, but larger data structures
* such as "struct task_struct" will require many copies. The logic in
* btf_show_obj_safe() handles the logic that determines if a new
* copy_from_kernel_nofault() is needed.
*/
struct btf_show {
u64 flags;
void *target; /* target of show operation (seq file, buffer) */
void (*showfn)(struct btf_show *show, const char *fmt, va_list args);
const struct btf *btf;
/* below are used during iteration */
struct {
u8 depth;
u8 depth_to_show;
u8 depth_check;
u8 array_member:1,
array_terminated:1;
u16 array_encoding;
u32 type_id;
int status; /* non-zero for error */
const struct btf_type *type;
const struct btf_member *member;
char name[BTF_SHOW_NAME_SIZE]; /* space for member name/type */
} state;
struct {
u32 size;
void *head;
void *data;
u8 safe[BTF_SHOW_OBJ_SAFE_SIZE];
} obj;
};
struct btf_kind_operations {
s32 (*check_meta)(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left);
int (*resolve)(struct btf_verifier_env *env,
const struct resolve_vertex *v);
int (*check_member)(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type);
int (*check_kflag_member)(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type);
void (*log_details)(struct btf_verifier_env *env,
const struct btf_type *t);
void (*show)(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offsets,
struct btf_show *show);
};
static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS];
static struct btf_type btf_void;
static int btf_resolve(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id);
static int btf_func_check(struct btf_verifier_env *env,
const struct btf_type *t);
static bool btf_type_is_modifier(const struct btf_type *t)
{
/* Some of them is not strictly a C modifier
* but they are grouped into the same bucket
* for BTF concern:
* A type (t) that refers to another
* type through t->type AND its size cannot
* be determined without following the t->type.
*
* ptr does not fall into this bucket
* because its size is always sizeof(void *).
*/
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
return true;
}
return false;
}
bool btf_type_is_void(const struct btf_type *t)
{
return t == &btf_void;
}
static bool btf_type_is_fwd(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_FWD;
}
static bool btf_type_nosize(const struct btf_type *t)
{
return btf_type_is_void(t) || btf_type_is_fwd(t) ||
btf_type_is_func(t) || btf_type_is_func_proto(t);
}
static bool btf_type_nosize_or_null(const struct btf_type *t)
{
return !t || btf_type_nosize(t);
}
static bool __btf_type_is_struct(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT;
}
static bool btf_type_is_array(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY;
}
static bool btf_type_is_datasec(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_DATASEC;
}
static bool btf_type_is_decl_tag(const struct btf_type *t)
{
return BTF_INFO_KIND(t->info) == BTF_KIND_DECL_TAG;
}
static bool btf_type_is_decl_tag_target(const struct btf_type *t)
{
return btf_type_is_func(t) || btf_type_is_struct(t) ||
btf_type_is_var(t) || btf_type_is_typedef(t);
}
u32 btf_nr_types(const struct btf *btf)
{
u32 total = 0;
while (btf) {
total += btf->nr_types;
btf = btf->base_btf;
}
return total;
}
s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind)
{
const struct btf_type *t;
const char *tname;
u32 i, total;
total = btf_nr_types(btf);
for (i = 1; i < total; i++) {
t = btf_type_by_id(btf, i);
if (BTF_INFO_KIND(t->info) != kind)
continue;
tname = btf_name_by_offset(btf, t->name_off);
if (!strcmp(tname, name))
return i;
}
return -ENOENT;
}
static s32 bpf_find_btf_id(const char *name, u32 kind, struct btf **btf_p)
{
struct btf *btf;
s32 ret;
int id;
btf = bpf_get_btf_vmlinux();
if (IS_ERR(btf))
return PTR_ERR(btf);
if (!btf)
return -EINVAL;
ret = btf_find_by_name_kind(btf, name, kind);
/* ret is never zero, since btf_find_by_name_kind returns
* positive btf_id or negative error.
*/
if (ret > 0) {
btf_get(btf);
*btf_p = btf;
return ret;
}
/* If name is not found in vmlinux's BTF then search in module's BTFs */
spin_lock_bh(&btf_idr_lock);
idr_for_each_entry(&btf_idr, btf, id) {
if (!btf_is_module(btf))
continue;
/* linear search could be slow hence unlock/lock
* the IDR to avoiding holding it for too long
*/
btf_get(btf);
spin_unlock_bh(&btf_idr_lock);
ret = btf_find_by_name_kind(btf, name, kind);
if (ret > 0) {
*btf_p = btf;
return ret;
}
spin_lock_bh(&btf_idr_lock);
btf_put(btf);
}
spin_unlock_bh(&btf_idr_lock);
return ret;
}
const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *t = btf_type_by_id(btf, id);
while (btf_type_is_modifier(t)) {
id = t->type;
t = btf_type_by_id(btf, t->type);
}
if (res_id)
*res_id = id;
return t;
}
const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *t;
t = btf_type_skip_modifiers(btf, id, NULL);
if (!btf_type_is_ptr(t))
return NULL;
return btf_type_skip_modifiers(btf, t->type, res_id);
}
const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
u32 id, u32 *res_id)
{
const struct btf_type *ptype;
ptype = btf_type_resolve_ptr(btf, id, res_id);
if (ptype && btf_type_is_func_proto(ptype))
return ptype;
return NULL;
}
/* Types that act only as a source, not sink or intermediate
* type when resolving.
*/
static bool btf_type_is_resolve_source_only(const struct btf_type *t)
{
return btf_type_is_var(t) ||
btf_type_is_decl_tag(t) ||
btf_type_is_datasec(t);
}
/* What types need to be resolved?
*
* btf_type_is_modifier() is an obvious one.
*
* btf_type_is_struct() because its member refers to
* another type (through member->type).
*
* btf_type_is_var() because the variable refers to
* another type. btf_type_is_datasec() holds multiple
* btf_type_is_var() types that need resolving.
*
* btf_type_is_array() because its element (array->type)
* refers to another type. Array can be thought of a
* special case of struct while array just has the same
* member-type repeated by array->nelems of times.
*/
static bool btf_type_needs_resolve(const struct btf_type *t)
{
return btf_type_is_modifier(t) ||
btf_type_is_ptr(t) ||
btf_type_is_struct(t) ||
btf_type_is_array(t) ||
btf_type_is_var(t) ||
btf_type_is_func(t) ||
btf_type_is_decl_tag(t) ||
btf_type_is_datasec(t);
}
/* t->size can be used */
static bool btf_type_has_size(const struct btf_type *t)
{
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_INT:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_DATASEC:
case BTF_KIND_FLOAT:
case BTF_KIND_ENUM64:
return true;
}
return false;
}
static const char *btf_int_encoding_str(u8 encoding)
{
if (encoding == 0)
return "(none)";
else if (encoding == BTF_INT_SIGNED)
return "SIGNED";
else if (encoding == BTF_INT_CHAR)
return "CHAR";
else if (encoding == BTF_INT_BOOL)
return "BOOL";
else
return "UNKN";
}
static u32 btf_type_int(const struct btf_type *t)
{
return *(u32 *)(t + 1);
}
static const struct btf_array *btf_type_array(const struct btf_type *t)
{
return (const struct btf_array *)(t + 1);
}
static const struct btf_enum *btf_type_enum(const struct btf_type *t)
{
return (const struct btf_enum *)(t + 1);
}
static const struct btf_var *btf_type_var(const struct btf_type *t)
{
return (const struct btf_var *)(t + 1);
}
static const struct btf_decl_tag *btf_type_decl_tag(const struct btf_type *t)
{
return (const struct btf_decl_tag *)(t + 1);
}
static const struct btf_enum64 *btf_type_enum64(const struct btf_type *t)
{
return (const struct btf_enum64 *)(t + 1);
}
static const struct btf_kind_operations *btf_type_ops(const struct btf_type *t)
{
return kind_ops[BTF_INFO_KIND(t->info)];
}
static bool btf_name_offset_valid(const struct btf *btf, u32 offset)
{
if (!BTF_STR_OFFSET_VALID(offset))
return false;
while (offset < btf->start_str_off)
btf = btf->base_btf;
offset -= btf->start_str_off;
return offset < btf->hdr.str_len;
}
static bool __btf_name_char_ok(char c, bool first, bool dot_ok)
{
if ((first ? !isalpha(c) :
!isalnum(c)) &&
c != '_' &&
((c == '.' && !dot_ok) ||
c != '.'))
return false;
return true;
}
static const char *btf_str_by_offset(const struct btf *btf, u32 offset)
{
while (offset < btf->start_str_off)
btf = btf->base_btf;
offset -= btf->start_str_off;
if (offset < btf->hdr.str_len)
return &btf->strings[offset];
return NULL;
}
static bool __btf_name_valid(const struct btf *btf, u32 offset, bool dot_ok)
{
/* offset must be valid */
const char *src = btf_str_by_offset(btf, offset);
const char *src_limit;
if (!__btf_name_char_ok(*src, true, dot_ok))
return false;
/* set a limit on identifier length */
src_limit = src + KSYM_NAME_LEN;
src++;
while (*src && src < src_limit) {
if (!__btf_name_char_ok(*src, false, dot_ok))
return false;
src++;
}
return !*src;
}
/* Only C-style identifier is permitted. This can be relaxed if
* necessary.
*/
static bool btf_name_valid_identifier(const struct btf *btf, u32 offset)
{
return __btf_name_valid(btf, offset, false);
}
static bool btf_name_valid_section(const struct btf *btf, u32 offset)
{
return __btf_name_valid(btf, offset, true);
}
static const char *__btf_name_by_offset(const struct btf *btf, u32 offset)
{
const char *name;
if (!offset)
return "(anon)";
name = btf_str_by_offset(btf, offset);
return name ?: "(invalid-name-offset)";
}
const char *btf_name_by_offset(const struct btf *btf, u32 offset)
{
return btf_str_by_offset(btf, offset);
}
const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
type_id -= btf->start_id;
if (type_id >= btf->nr_types)
return NULL;
return btf->types[type_id];
}
/*
* Regular int is not a bit field and it must be either
* u8/u16/u32/u64 or __int128.
*/
static bool btf_type_int_is_regular(const struct btf_type *t)
{
u8 nr_bits, nr_bytes;
u32 int_data;
int_data = btf_type_int(t);
nr_bits = BTF_INT_BITS(int_data);
nr_bytes = BITS_ROUNDUP_BYTES(nr_bits);
if (BITS_PER_BYTE_MASKED(nr_bits) ||
BTF_INT_OFFSET(int_data) ||
(nr_bytes != sizeof(u8) && nr_bytes != sizeof(u16) &&
nr_bytes != sizeof(u32) && nr_bytes != sizeof(u64) &&
nr_bytes != (2 * sizeof(u64)))) {
return false;
}
return true;
}
/*
* Check that given struct member is a regular int with expected
* offset and size.
*/
bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
const struct btf_member *m,
u32 expected_offset, u32 expected_size)
{
const struct btf_type *t;
u32 id, int_data;
u8 nr_bits;
id = m->type;
t = btf_type_id_size(btf, &id, NULL);
if (!t || !btf_type_is_int(t))
return false;
int_data = btf_type_int(t);
nr_bits = BTF_INT_BITS(int_data);
if (btf_type_kflag(s)) {
u32 bitfield_size = BTF_MEMBER_BITFIELD_SIZE(m->offset);
u32 bit_offset = BTF_MEMBER_BIT_OFFSET(m->offset);
/* if kflag set, int should be a regular int and
* bit offset should be at byte boundary.
*/
return !bitfield_size &&
BITS_ROUNDUP_BYTES(bit_offset) == expected_offset &&
BITS_ROUNDUP_BYTES(nr_bits) == expected_size;
}
if (BTF_INT_OFFSET(int_data) ||
BITS_PER_BYTE_MASKED(m->offset) ||
BITS_ROUNDUP_BYTES(m->offset) != expected_offset ||
BITS_PER_BYTE_MASKED(nr_bits) ||
BITS_ROUNDUP_BYTES(nr_bits) != expected_size)
return false;
return true;
}
/* Similar to btf_type_skip_modifiers() but does not skip typedefs. */
static const struct btf_type *btf_type_skip_qualifiers(const struct btf *btf,
u32 id)
{
const struct btf_type *t = btf_type_by_id(btf, id);
while (btf_type_is_modifier(t) &&
BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) {
t = btf_type_by_id(btf, t->type);
}
return t;
}
#define BTF_SHOW_MAX_ITER 10
#define BTF_KIND_BIT(kind) (1ULL << kind)
/*
* Populate show->state.name with type name information.
* Format of type name is
*
* [.member_name = ] (type_name)
*/
static const char *btf_show_name(struct btf_show *show)
{
/* BTF_MAX_ITER array suffixes "[]" */
const char *array_suffixes = "[][][][][][][][][][]";
const char *array_suffix = &array_suffixes[strlen(array_suffixes)];
/* BTF_MAX_ITER pointer suffixes "*" */
const char *ptr_suffixes = "**********";
const char *ptr_suffix = &ptr_suffixes[strlen(ptr_suffixes)];
const char *name = NULL, *prefix = "", *parens = "";
const struct btf_member *m = show->state.member;
const struct btf_type *t;
const struct btf_array *array;
u32 id = show->state.type_id;
const char *member = NULL;
bool show_member = false;
u64 kinds = 0;
int i;
show->state.name[0] = '\0';
/*
* Don't show type name if we're showing an array member;
* in that case we show the array type so don't need to repeat
* ourselves for each member.
*/
if (show->state.array_member)
return "";
/* Retrieve member name, if any. */
if (m) {
member = btf_name_by_offset(show->btf, m->name_off);
show_member = strlen(member) > 0;
id = m->type;
}
/*
* Start with type_id, as we have resolved the struct btf_type *
* via btf_modifier_show() past the parent typedef to the child
* struct, int etc it is defined as. In such cases, the type_id
* still represents the starting type while the struct btf_type *
* in our show->state points at the resolved type of the typedef.
*/
t = btf_type_by_id(show->btf, id);
if (!t)
return "";
/*
* The goal here is to build up the right number of pointer and
* array suffixes while ensuring the type name for a typedef
* is represented. Along the way we accumulate a list of
* BTF kinds we have encountered, since these will inform later
* display; for example, pointer types will not require an
* opening "{" for struct, we will just display the pointer value.
*
* We also want to accumulate the right number of pointer or array
* indices in the format string while iterating until we get to
* the typedef/pointee/array member target type.
*
* We start by pointing at the end of pointer and array suffix
* strings; as we accumulate pointers and arrays we move the pointer
* or array string backwards so it will show the expected number of
* '*' or '[]' for the type. BTF_SHOW_MAX_ITER of nesting of pointers
* and/or arrays and typedefs are supported as a precaution.
*
* We also want to get typedef name while proceeding to resolve
* type it points to so that we can add parentheses if it is a
* "typedef struct" etc.
*/
for (i = 0; i < BTF_SHOW_MAX_ITER; i++) {
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_TYPEDEF:
if (!name)
name = btf_name_by_offset(show->btf,
t->name_off);
kinds |= BTF_KIND_BIT(BTF_KIND_TYPEDEF);
id = t->type;
break;
case BTF_KIND_ARRAY:
kinds |= BTF_KIND_BIT(BTF_KIND_ARRAY);
parens = "[";
if (!t)
return "";
array = btf_type_array(t);
if (array_suffix > array_suffixes)
array_suffix -= 2;
id = array->type;
break;
case BTF_KIND_PTR:
kinds |= BTF_KIND_BIT(BTF_KIND_PTR);
if (ptr_suffix > ptr_suffixes)
ptr_suffix -= 1;
id = t->type;
break;
default:
id = 0;
break;
}
if (!id)
break;
t = btf_type_skip_qualifiers(show->btf, id);
}
/* We may not be able to represent this type; bail to be safe */
if (i == BTF_SHOW_MAX_ITER)
return "";
if (!name)
name = btf_name_by_offset(show->btf, t->name_off);
switch (BTF_INFO_KIND(t->info)) {
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
prefix = BTF_INFO_KIND(t->info) == BTF_KIND_STRUCT ?
"struct" : "union";
/* if it's an array of struct/union, parens is already set */
if (!(kinds & (BTF_KIND_BIT(BTF_KIND_ARRAY))))
parens = "{";
break;
case BTF_KIND_ENUM:
case BTF_KIND_ENUM64:
prefix = "enum";
break;
default:
break;
}
/* pointer does not require parens */
if (kinds & BTF_KIND_BIT(BTF_KIND_PTR))
parens = "";
/* typedef does not require struct/union/enum prefix */
if (kinds & BTF_KIND_BIT(BTF_KIND_TYPEDEF))
prefix = "";
if (!name)
name = "";
/* Even if we don't want type name info, we want parentheses etc */
if (show->flags & BTF_SHOW_NONAME)
snprintf(show->state.name, sizeof(show->state.name), "%s",
parens);
else
snprintf(show->state.name, sizeof(show->state.name),
"%s%s%s(%s%s%s%s%s%s)%s",
/* first 3 strings comprise ".member = " */
show_member ? "." : "",
show_member ? member : "",
show_member ? " = " : "",
/* ...next is our prefix (struct, enum, etc) */
prefix,
strlen(prefix) > 0 && strlen(name) > 0 ? " " : "",
/* ...this is the type name itself */
name,
/* ...suffixed by the appropriate '*', '[]' suffixes */
strlen(ptr_suffix) > 0 ? " " : "", ptr_suffix,
array_suffix, parens);
return show->state.name;
}
static const char *__btf_show_indent(struct btf_show *show)
{
const char *indents = " ";
const char *indent = &indents[strlen(indents)];
if ((indent - show->state.depth) >= indents)
return indent - show->state.depth;
return indents;
}
static const char *btf_show_indent(struct btf_show *show)
{
return show->flags & BTF_SHOW_COMPACT ? "" : __btf_show_indent(show);
}
static const char *btf_show_newline(struct btf_show *show)
{
return show->flags & BTF_SHOW_COMPACT ? "" : "\n";
}
static const char *btf_show_delim(struct btf_show *show)
{
if (show->state.depth == 0)
return "";
if ((show->flags & BTF_SHOW_COMPACT) && show->state.type &&
BTF_INFO_KIND(show->state.type->info) == BTF_KIND_UNION)
return "|";
return ",";
}
__printf(2, 3) static void btf_show(struct btf_show *show, const char *fmt, ...)
{
va_list args;
if (!show->state.depth_check) {
va_start(args, fmt);
show->showfn(show, fmt, args);
va_end(args);
}
}
/* Macros are used here as btf_show_type_value[s]() prepends and appends
* format specifiers to the format specifier passed in; these do the work of
* adding indentation, delimiters etc while the caller simply has to specify
* the type value(s) in the format specifier + value(s).
*/
#define btf_show_type_value(show, fmt, value) \
do { \
if ((value) != (__typeof__(value))0 || \
(show->flags & BTF_SHOW_ZERO) || \
show->state.depth == 0) { \
btf_show(show, "%s%s" fmt "%s%s", \
btf_show_indent(show), \
btf_show_name(show), \
value, btf_show_delim(show), \
btf_show_newline(show)); \
if (show->state.depth > show->state.depth_to_show) \
show->state.depth_to_show = show->state.depth; \
} \
} while (0)
#define btf_show_type_values(show, fmt, ...) \
do { \
btf_show(show, "%s%s" fmt "%s%s", btf_show_indent(show), \
btf_show_name(show), \
__VA_ARGS__, btf_show_delim(show), \
btf_show_newline(show)); \
if (show->state.depth > show->state.depth_to_show) \
show->state.depth_to_show = show->state.depth; \
} while (0)
/* How much is left to copy to safe buffer after @data? */
static int btf_show_obj_size_left(struct btf_show *show, void *data)
{
return show->obj.head + show->obj.size - data;
}
/* Is object pointed to by @data of @size already copied to our safe buffer? */
static bool btf_show_obj_is_safe(struct btf_show *show, void *data, int size)
{
return data >= show->obj.data &&
(data + size) < (show->obj.data + BTF_SHOW_OBJ_SAFE_SIZE);
}
/*
* If object pointed to by @data of @size falls within our safe buffer, return
* the equivalent pointer to the same safe data. Assumes
* copy_from_kernel_nofault() has already happened and our safe buffer is
* populated.
*/
static void *__btf_show_obj_safe(struct btf_show *show, void *data, int size)
{
if (btf_show_obj_is_safe(show, data, size))
return show->obj.safe + (data - show->obj.data);
return NULL;
}
/*
* Return a safe-to-access version of data pointed to by @data.
* We do this by copying the relevant amount of information
* to the struct btf_show obj.safe buffer using copy_from_kernel_nofault().
*
* If BTF_SHOW_UNSAFE is specified, just return data as-is; no
* safe copy is needed.
*
* Otherwise we need to determine if we have the required amount
* of data (determined by the @data pointer and the size of the
* largest base type we can encounter (represented by
* BTF_SHOW_OBJ_BASE_TYPE_SIZE). Having that much data ensures
* that we will be able to print some of the current object,
* and if more is needed a copy will be triggered.
* Some objects such as structs will not fit into the buffer;
* in such cases additional copies when we iterate over their
* members may be needed.
*
* btf_show_obj_safe() is used to return a safe buffer for
* btf_show_start_type(); this ensures that as we recurse into
* nested types we always have safe data for the given type.
* This approach is somewhat wasteful; it's possible for example
* that when iterating over a large union we'll end up copying the
* same data repeatedly, but the goal is safety not performance.
* We use stack data as opposed to per-CPU buffers because the
* iteration over a type can take some time, and preemption handling
* would greatly complicate use of the safe buffer.
*/
static void *btf_show_obj_safe(struct btf_show *show,
const struct btf_type *t,
void *data)
{
const struct btf_type *rt;
int size_left, size;
void *safe = NULL;
if (show->flags & BTF_SHOW_UNSAFE)
return data;
rt = btf_resolve_size(show->btf, t, &size);
if (IS_ERR(rt)) {
show->state.status = PTR_ERR(rt);
return NULL;
}
/*
* Is this toplevel object? If so, set total object size and
* initialize pointers. Otherwise check if we still fall within
* our safe object data.
*/
if (show->state.depth == 0) {
show->obj.size = size;
show->obj.head = data;
} else {
/*
* If the size of the current object is > our remaining
* safe buffer we _may_ need to do a new copy. However
* consider the case of a nested struct; it's size pushes
* us over the safe buffer limit, but showing any individual
* struct members does not. In such cases, we don't need
* to initiate a fresh copy yet; however we definitely need
* at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes left
* in our buffer, regardless of the current object size.
* The logic here is that as we resolve types we will
* hit a base type at some point, and we need to be sure
* the next chunk of data is safely available to display
* that type info safely. We cannot rely on the size of
* the current object here because it may be much larger
* than our current buffer (e.g. task_struct is 8k).
* All we want to do here is ensure that we can print the
* next basic type, which we can if either
* - the current type size is within the safe buffer; or
* - at least BTF_SHOW_OBJ_BASE_TYPE_SIZE bytes are left in
* the safe buffer.
*/
safe = __btf_show_obj_safe(show, data,
min(size,
BTF_SHOW_OBJ_BASE_TYPE_SIZE));
}
/*
* We need a new copy to our safe object, either because we haven't
* yet copied and are initializing safe data, or because the data
* we want falls outside the boundaries of the safe object.
*/
if (!safe) {
size_left = btf_show_obj_size_left(show, data);
if (size_left > BTF_SHOW_OBJ_SAFE_SIZE)
size_left = BTF_SHOW_OBJ_SAFE_SIZE;
show->state.status = copy_from_kernel_nofault(show->obj.safe,
data, size_left);
if (!show->state.status) {
show->obj.data = data;
safe = show->obj.safe;
}
}
return safe;
}
/*
* Set the type we are starting to show and return a safe data pointer
* to be used for showing the associated data.
*/
static void *btf_show_start_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id, void *data)
{
show->state.type = t;
show->state.type_id = type_id;
show->state.name[0] = '\0';
return btf_show_obj_safe(show, t, data);
}
static void btf_show_end_type(struct btf_show *show)
{
show->state.type = NULL;
show->state.type_id = 0;
show->state.name[0] = '\0';
}
static void *btf_show_start_aggr_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id, void *data)
{
void *safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return safe_data;
btf_show(show, "%s%s%s", btf_show_indent(show),
btf_show_name(show),
btf_show_newline(show));
show->state.depth++;
return safe_data;
}
static void btf_show_end_aggr_type(struct btf_show *show,
const char *suffix)
{
show->state.depth--;
btf_show(show, "%s%s%s%s", btf_show_indent(show), suffix,
btf_show_delim(show), btf_show_newline(show));
btf_show_end_type(show);
}
static void btf_show_start_member(struct btf_show *show,
const struct btf_member *m)
{
show->state.member = m;
}
static void btf_show_start_array_member(struct btf_show *show)
{
show->state.array_member = 1;
btf_show_start_member(show, NULL);
}
static void btf_show_end_member(struct btf_show *show)
{
show->state.member = NULL;
}
static void btf_show_end_array_member(struct btf_show *show)
{
show->state.array_member = 0;
btf_show_end_member(show);
}
static void *btf_show_start_array_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id,
u16 array_encoding,
void *data)
{
show->state.array_encoding = array_encoding;
show->state.array_terminated = 0;
return btf_show_start_aggr_type(show, t, type_id, data);
}
static void btf_show_end_array_type(struct btf_show *show)
{
show->state.array_encoding = 0;
show->state.array_terminated = 0;
btf_show_end_aggr_type(show, "]");
}
static void *btf_show_start_struct_type(struct btf_show *show,
const struct btf_type *t,
u32 type_id,
void *data)
{
return btf_show_start_aggr_type(show, t, type_id, data);
}
static void btf_show_end_struct_type(struct btf_show *show)
{
btf_show_end_aggr_type(show, "}");
}
__printf(2, 3) static void __btf_verifier_log(struct bpf_verifier_log *log,
const char *fmt, ...)
{
va_list args;
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__printf(2, 3) static void btf_verifier_log(struct btf_verifier_env *env,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__printf(4, 5) static void __btf_verifier_log_type(struct btf_verifier_env *env,
const struct btf_type *t,
bool log_details,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
u8 kind = BTF_INFO_KIND(t->info);
struct btf *btf = env->btf;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
/* btf verifier prints all types it is processing via
* btf_verifier_log_type(..., fmt = NULL).
* Skip those prints for in-kernel BTF verification.
*/
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
__btf_verifier_log(log, "[%u] %s %s%s",
env->log_type_id,
btf_kind_str[kind],
__btf_name_by_offset(btf, t->name_off),
log_details ? " " : "");
if (log_details)
btf_type_ops(t)->log_details(env, t);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
#define btf_verifier_log_type(env, t, ...) \
__btf_verifier_log_type((env), (t), true, __VA_ARGS__)
#define btf_verifier_log_basic(env, t, ...) \
__btf_verifier_log_type((env), (t), false, __VA_ARGS__)
__printf(4, 5)
static void btf_verifier_log_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
struct btf *btf = env->btf;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
/* The CHECK_META phase already did a btf dump.
*
* If member is logged again, it must hit an error in
* parsing this member. It is useful to print out which
* struct this member belongs to.
*/
if (env->phase != CHECK_META)
btf_verifier_log_type(env, struct_type, NULL);
if (btf_type_kflag(struct_type))
__btf_verifier_log(log,
"\t%s type_id=%u bitfield_size=%u bits_offset=%u",
__btf_name_by_offset(btf, member->name_off),
member->type,
BTF_MEMBER_BITFIELD_SIZE(member->offset),
BTF_MEMBER_BIT_OFFSET(member->offset));
else
__btf_verifier_log(log, "\t%s type_id=%u bits_offset=%u",
__btf_name_by_offset(btf, member->name_off),
member->type, member->offset);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
__printf(4, 5)
static void btf_verifier_log_vsi(struct btf_verifier_env *env,
const struct btf_type *datasec_type,
const struct btf_var_secinfo *vsi,
const char *fmt, ...)
{
struct bpf_verifier_log *log = &env->log;
va_list args;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL && !fmt)
return;
if (env->phase != CHECK_META)
btf_verifier_log_type(env, datasec_type, NULL);
__btf_verifier_log(log, "\t type_id=%u offset=%u size=%u",
vsi->type, vsi->offset, vsi->size);
if (fmt && *fmt) {
__btf_verifier_log(log, " ");
va_start(args, fmt);
bpf_verifier_vlog(log, fmt, args);
va_end(args);
}
__btf_verifier_log(log, "\n");
}
static void btf_verifier_log_hdr(struct btf_verifier_env *env,
u32 btf_data_size)
{
struct bpf_verifier_log *log = &env->log;
const struct btf *btf = env->btf;
const struct btf_header *hdr;
if (!bpf_verifier_log_needed(log))
return;
if (log->level == BPF_LOG_KERNEL)
return;
hdr = &btf->hdr;
__btf_verifier_log(log, "magic: 0x%x\n", hdr->magic);
__btf_verifier_log(log, "version: %u\n", hdr->version);
__btf_verifier_log(log, "flags: 0x%x\n", hdr->flags);
__btf_verifier_log(log, "hdr_len: %u\n", hdr->hdr_len);
__btf_verifier_log(log, "type_off: %u\n", hdr->type_off);
__btf_verifier_log(log, "type_len: %u\n", hdr->type_len);
__btf_verifier_log(log, "str_off: %u\n", hdr->str_off);
__btf_verifier_log(log, "str_len: %u\n", hdr->str_len);
__btf_verifier_log(log, "btf_total_size: %u\n", btf_data_size);
}
static int btf_add_type(struct btf_verifier_env *env, struct btf_type *t)
{
struct btf *btf = env->btf;
if (btf->types_size == btf->nr_types) {
/* Expand 'types' array */
struct btf_type **new_types;
u32 expand_by, new_size;
if (btf->start_id + btf->types_size == BTF_MAX_TYPE) {
btf_verifier_log(env, "Exceeded max num of types");
return -E2BIG;
}
expand_by = max_t(u32, btf->types_size >> 2, 16);
new_size = min_t(u32, BTF_MAX_TYPE,
btf->types_size + expand_by);
new_types = kvcalloc(new_size, sizeof(*new_types),
GFP_KERNEL | __GFP_NOWARN);
if (!new_types)
return -ENOMEM;
if (btf->nr_types == 0) {
if (!btf->base_btf) {
/* lazily init VOID type */
new_types[0] = &btf_void;
btf->nr_types++;
}
} else {
memcpy(new_types, btf->types,
sizeof(*btf->types) * btf->nr_types);
}
kvfree(btf->types);
btf->types = new_types;
btf->types_size = new_size;
}
btf->types[btf->nr_types++] = t;
return 0;
}
static int btf_alloc_id(struct btf *btf)
{
int id;
idr_preload(GFP_KERNEL);
spin_lock_bh(&btf_idr_lock);
id = idr_alloc_cyclic(&btf_idr, btf, 1, INT_MAX, GFP_ATOMIC);
if (id > 0)
btf->id = id;
spin_unlock_bh(&btf_idr_lock);
idr_preload_end();
if (WARN_ON_ONCE(!id))
return -ENOSPC;
return id > 0 ? 0 : id;
}
static void btf_free_id(struct btf *btf)
{
unsigned long flags;
/*
* In map-in-map, calling map_delete_elem() on outer
* map will call bpf_map_put on the inner map.
* It will then eventually call btf_free_id()
* on the inner map. Some of the map_delete_elem()
* implementation may have irq disabled, so
* we need to use the _irqsave() version instead
* of the _bh() version.
*/
spin_lock_irqsave(&btf_idr_lock, flags);
idr_remove(&btf_idr, btf->id);
spin_unlock_irqrestore(&btf_idr_lock, flags);
}
static void btf_free_kfunc_set_tab(struct btf *btf)
{
struct btf_kfunc_set_tab *tab = btf->kfunc_set_tab;
int hook;
if (!tab)
return;
/* For module BTF, we directly assign the sets being registered, so
* there is nothing to free except kfunc_set_tab.
*/
if (btf_is_module(btf))
goto free_tab;
for (hook = 0; hook < ARRAY_SIZE(tab->sets); hook++)
kfree(tab->sets[hook]);
free_tab:
kfree(tab);
btf->kfunc_set_tab = NULL;
}
static void btf_free_dtor_kfunc_tab(struct btf *btf)
{
struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
if (!tab)
return;
kfree(tab);
btf->dtor_kfunc_tab = NULL;
}
static void btf_free(struct btf *btf)
{
btf_free_dtor_kfunc_tab(btf);
btf_free_kfunc_set_tab(btf);
kvfree(btf->types);
kvfree(btf->resolved_sizes);
kvfree(btf->resolved_ids);
kvfree(btf->data);
kfree(btf);
}
static void btf_free_rcu(struct rcu_head *rcu)
{
struct btf *btf = container_of(rcu, struct btf, rcu);
btf_free(btf);
}
void btf_get(struct btf *btf)
{
refcount_inc(&btf->refcnt);
}
void btf_put(struct btf *btf)
{
if (btf && refcount_dec_and_test(&btf->refcnt)) {
btf_free_id(btf);
call_rcu(&btf->rcu, btf_free_rcu);
}
}
static int env_resolve_init(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
u32 nr_types = btf->nr_types;
u32 *resolved_sizes = NULL;
u32 *resolved_ids = NULL;
u8 *visit_states = NULL;
resolved_sizes = kvcalloc(nr_types, sizeof(*resolved_sizes),
GFP_KERNEL | __GFP_NOWARN);
if (!resolved_sizes)
goto nomem;
resolved_ids = kvcalloc(nr_types, sizeof(*resolved_ids),
GFP_KERNEL | __GFP_NOWARN);
if (!resolved_ids)
goto nomem;
visit_states = kvcalloc(nr_types, sizeof(*visit_states),
GFP_KERNEL | __GFP_NOWARN);
if (!visit_states)
goto nomem;
btf->resolved_sizes = resolved_sizes;
btf->resolved_ids = resolved_ids;
env->visit_states = visit_states;
return 0;
nomem:
kvfree(resolved_sizes);
kvfree(resolved_ids);
kvfree(visit_states);
return -ENOMEM;
}
static void btf_verifier_env_free(struct btf_verifier_env *env)
{
kvfree(env->visit_states);
kfree(env);
}
static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
const struct btf_type *next_type)
{
switch (env->resolve_mode) {
case RESOLVE_TBD:
/* int, enum or void is a sink */
return !btf_type_needs_resolve(next_type);
case RESOLVE_PTR:
/* int, enum, void, struct, array, func or func_proto is a sink
* for ptr
*/
return !btf_type_is_modifier(next_type) &&
!btf_type_is_ptr(next_type);
case RESOLVE_STRUCT_OR_ARRAY:
/* int, enum, void, ptr, func or func_proto is a sink
* for struct and array
*/
return !btf_type_is_modifier(next_type) &&
!btf_type_is_array(next_type) &&
!btf_type_is_struct(next_type);
default:
BUG();
}
}
static bool env_type_is_resolved(const struct btf_verifier_env *env,
u32 type_id)
{
/* base BTF types should be resolved by now */
if (type_id < env->btf->start_id)
return true;
return env->visit_states[type_id - env->btf->start_id] == RESOLVED;
}
static int env_stack_push(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id)
{
const struct btf *btf = env->btf;
struct resolve_vertex *v;
if (env->top_stack == MAX_RESOLVE_DEPTH)
return -E2BIG;
if (type_id < btf->start_id
|| env->visit_states[type_id - btf->start_id] != NOT_VISITED)
return -EEXIST;
env->visit_states[type_id - btf->start_id] = VISITED;
v = &env->stack[env->top_stack++];
v->t = t;
v->type_id = type_id;
v->next_member = 0;
if (env->resolve_mode == RESOLVE_TBD) {
if (btf_type_is_ptr(t))
env->resolve_mode = RESOLVE_PTR;
else if (btf_type_is_struct(t) || btf_type_is_array(t))
env->resolve_mode = RESOLVE_STRUCT_OR_ARRAY;
}
return 0;
}
static void env_stack_set_next_member(struct btf_verifier_env *env,
u16 next_member)
{
env->stack[env->top_stack - 1].next_member = next_member;
}
static void env_stack_pop_resolved(struct btf_verifier_env *env,
u32 resolved_type_id,
u32 resolved_size)
{
u32 type_id = env->stack[--(env->top_stack)].type_id;
struct btf *btf = env->btf;
type_id -= btf->start_id; /* adjust to local type id */
btf->resolved_sizes[type_id] = resolved_size;
btf->resolved_ids[type_id] = resolved_type_id;
env->visit_states[type_id] = RESOLVED;
}
static const struct resolve_vertex *env_stack_peak(struct btf_verifier_env *env)
{
return env->top_stack ? &env->stack[env->top_stack - 1] : NULL;
}
/* Resolve the size of a passed-in "type"
*
* type: is an array (e.g. u32 array[x][y])
* return type: type "u32[x][y]", i.e. BTF_KIND_ARRAY,
* *type_size: (x * y * sizeof(u32)). Hence, *type_size always
* corresponds to the return type.
* *elem_type: u32
* *elem_id: id of u32
* *total_nelems: (x * y). Hence, individual elem size is
* (*type_size / *total_nelems)
* *type_id: id of type if it's changed within the function, 0 if not
*
* type: is not an array (e.g. const struct X)
* return type: type "struct X"
* *type_size: sizeof(struct X)
* *elem_type: same as return type ("struct X")
* *elem_id: 0
* *total_nelems: 1
* *type_id: id of type if it's changed within the function, 0 if not
*/
static const struct btf_type *
__btf_resolve_size(const struct btf *btf, const struct btf_type *type,
u32 *type_size, const struct btf_type **elem_type,
u32 *elem_id, u32 *total_nelems, u32 *type_id)
{
const struct btf_type *array_type = NULL;
const struct btf_array *array = NULL;
u32 i, size, nelems = 1, id = 0;
for (i = 0; i < MAX_RESOLVE_DEPTH; i++) {
switch (BTF_INFO_KIND(type->info)) {
/* type->size can be used */
case BTF_KIND_INT:
case BTF_KIND_STRUCT:
case BTF_KIND_UNION:
case BTF_KIND_ENUM:
case BTF_KIND_FLOAT:
case BTF_KIND_ENUM64:
size = type->size;
goto resolved;
case BTF_KIND_PTR:
size = sizeof(void *);
goto resolved;
/* Modifiers */
case BTF_KIND_TYPEDEF:
case BTF_KIND_VOLATILE:
case BTF_KIND_CONST:
case BTF_KIND_RESTRICT:
case BTF_KIND_TYPE_TAG:
id = type->type;
type = btf_type_by_id(btf, type->type);
break;
case BTF_KIND_ARRAY:
if (!array_type)
array_type = type;
array = btf_type_array(type);
if (nelems && array->nelems > U32_MAX / nelems)
return ERR_PTR(-EINVAL);
nelems *= array->nelems;
type = btf_type_by_id(btf, array->type);
break;
/* type without size */
default:
return ERR_PTR(-EINVAL);
}
}
return ERR_PTR(-EINVAL);
resolved:
if (nelems && size > U32_MAX / nelems)
return ERR_PTR(-EINVAL);
*type_size = nelems * size;
if (total_nelems)
*total_nelems = nelems;
if (elem_type)
*elem_type = type;
if (elem_id)
*elem_id = array ? array->type : 0;
if (type_id && id)
*type_id = id;
return array_type ? : type;
}
const struct btf_type *
btf_resolve_size(const struct btf *btf, const struct btf_type *type,
u32 *type_size)
{
return __btf_resolve_size(btf, type, type_size, NULL, NULL, NULL, NULL);
}
static u32 btf_resolved_type_id(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
return btf->resolved_ids[type_id - btf->start_id];
}
/* The input param "type_id" must point to a needs_resolve type */
static const struct btf_type *btf_type_id_resolve(const struct btf *btf,
u32 *type_id)
{
*type_id = btf_resolved_type_id(btf, *type_id);
return btf_type_by_id(btf, *type_id);
}
static u32 btf_resolved_type_size(const struct btf *btf, u32 type_id)
{
while (type_id < btf->start_id)
btf = btf->base_btf;
return btf->resolved_sizes[type_id - btf->start_id];
}
const struct btf_type *btf_type_id_size(const struct btf *btf,
u32 *type_id, u32 *ret_size)
{
const struct btf_type *size_type;
u32 size_type_id = *type_id;
u32 size = 0;
size_type = btf_type_by_id(btf, size_type_id);
if (btf_type_nosize_or_null(size_type))
return NULL;
if (btf_type_has_size(size_type)) {
size = size_type->size;
} else if (btf_type_is_array(size_type)) {
size = btf_resolved_type_size(btf, size_type_id);
} else if (btf_type_is_ptr(size_type)) {
size = sizeof(void *);
} else {
if (WARN_ON_ONCE(!btf_type_is_modifier(size_type) &&
!btf_type_is_var(size_type)))
return NULL;
size_type_id = btf_resolved_type_id(btf, size_type_id);
size_type = btf_type_by_id(btf, size_type_id);
if (btf_type_nosize_or_null(size_type))
return NULL;
else if (btf_type_has_size(size_type))
size = size_type->size;
else if (btf_type_is_array(size_type))
size = btf_resolved_type_size(btf, size_type_id);
else if (btf_type_is_ptr(size_type))
size = sizeof(void *);
else
return NULL;
}
*type_id = size_type_id;
if (ret_size)
*ret_size = size;
return size_type;
}
static int btf_df_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
btf_verifier_log_basic(env, struct_type,
"Unsupported check_member");
return -EINVAL;
}
static int btf_df_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
btf_verifier_log_basic(env, struct_type,
"Unsupported check_kflag_member");
return -EINVAL;
}
/* Used for ptr, array struct/union and float type members.
* int, enum and modifier types have their specific callback functions.
*/
static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
if (BTF_MEMBER_BITFIELD_SIZE(member->offset)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
/* bitfield size is 0, so member->offset represents bit offset only.
* It is safe to call non kflag check_member variants.
*/
return btf_type_ops(member_type)->check_member(env, struct_type,
member,
member_type);
}
static int btf_df_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
btf_verifier_log_basic(env, v->t, "Unsupported resolve");
return -EINVAL;
}
static void btf_df_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offsets,
struct btf_show *show)
{
btf_show(show, "<unsupported kind:%u>", BTF_INFO_KIND(t->info));
}
static int btf_int_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 int_data = btf_type_int(member_type);
u32 struct_bits_off = member->offset;
u32 struct_size = struct_type->size;
u32 nr_copy_bits;
u32 bytes_offset;
if (U32_MAX - struct_bits_off < BTF_INT_OFFSET(int_data)) {
btf_verifier_log_member(env, struct_type, member,
"bits_offset exceeds U32_MAX");
return -EINVAL;
}
struct_bits_off += BTF_INT_OFFSET(int_data);
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
nr_copy_bits = BTF_INT_BITS(int_data) +
BITS_PER_BYTE_MASKED(struct_bits_off);
if (nr_copy_bits > BITS_PER_U128) {
btf_verifier_log_member(env, struct_type, member,
"nr_copy_bits exceeds 128");
return -EINVAL;
}
if (struct_size < bytes_offset ||
struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_int_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off, nr_bits, nr_int_data_bits, bytes_offset;
u32 int_data = btf_type_int(member_type);
u32 struct_size = struct_type->size;
u32 nr_copy_bits;
/* a regular int type is required for the kflag int member */
if (!btf_type_int_is_regular(member_type)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member base type");
return -EINVAL;
}
/* check sanity of bitfield size */
nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
nr_int_data_bits = BTF_INT_BITS(int_data);
if (!nr_bits) {
/* Not a bitfield member, member offset must be at byte
* boundary.
*/
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member offset");
return -EINVAL;
}
nr_bits = nr_int_data_bits;
} else if (nr_bits > nr_int_data_bits) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
nr_copy_bits = nr_bits + BITS_PER_BYTE_MASKED(struct_bits_off);
if (nr_copy_bits > BITS_PER_U128) {
btf_verifier_log_member(env, struct_type, member,
"nr_copy_bits exceeds 128");
return -EINVAL;
}
if (struct_size < bytes_offset ||
struct_size - bytes_offset < BITS_ROUNDUP_BYTES(nr_copy_bits)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_int_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 int_data, nr_bits, meta_needed = sizeof(int_data);
u16 encoding;
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
int_data = btf_type_int(t);
if (int_data & ~BTF_INT_MASK) {
btf_verifier_log_basic(env, t, "Invalid int_data:%x",
int_data);
return -EINVAL;
}
nr_bits = BTF_INT_BITS(int_data) + BTF_INT_OFFSET(int_data);
if (nr_bits > BITS_PER_U128) {
btf_verifier_log_type(env, t, "nr_bits exceeds %zu",
BITS_PER_U128);
return -EINVAL;
}
if (BITS_ROUNDUP_BYTES(nr_bits) > t->size) {
btf_verifier_log_type(env, t, "nr_bits exceeds type_size");
return -EINVAL;
}
/*
* Only one of the encoding bits is allowed and it
* should be sufficient for the pretty print purpose (i.e. decoding).
* Multiple bits can be allowed later if it is found
* to be insufficient.
*/
encoding = BTF_INT_ENCODING(int_data);
if (encoding &&
encoding != BTF_INT_SIGNED &&
encoding != BTF_INT_CHAR &&
encoding != BTF_INT_BOOL) {
btf_verifier_log_type(env, t, "Unsupported encoding");
return -ENOTSUPP;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_int_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
int int_data = btf_type_int(t);
btf_verifier_log(env,
"size=%u bits_offset=%u nr_bits=%u encoding=%s",
t->size, BTF_INT_OFFSET(int_data),
BTF_INT_BITS(int_data),
btf_int_encoding_str(BTF_INT_ENCODING(int_data)));
}
static void btf_int128_print(struct btf_show *show, void *data)
{
/* data points to a __int128 number.
* Suppose
* int128_num = *(__int128 *)data;
* The below formulas shows what upper_num and lower_num represents:
* upper_num = int128_num >> 64;
* lower_num = int128_num & 0xffffffffFFFFFFFFULL;
*/
u64 upper_num, lower_num;
#ifdef __BIG_ENDIAN_BITFIELD
upper_num = *(u64 *)data;
lower_num = *(u64 *)(data + 8);
#else
upper_num = *(u64 *)(data + 8);
lower_num = *(u64 *)data;
#endif
if (upper_num == 0)
btf_show_type_value(show, "0x%llx", lower_num);
else
btf_show_type_values(show, "0x%llx%016llx", upper_num,
lower_num);
}
static void btf_int128_shift(u64 *print_num, u16 left_shift_bits,
u16 right_shift_bits)
{
u64 upper_num, lower_num;
#ifdef __BIG_ENDIAN_BITFIELD
upper_num = print_num[0];
lower_num = print_num[1];
#else
upper_num = print_num[1];
lower_num = print_num[0];
#endif
/* shake out un-needed bits by shift/or operations */
if (left_shift_bits >= 64) {
upper_num = lower_num << (left_shift_bits - 64);
lower_num = 0;
} else {
upper_num = (upper_num << left_shift_bits) |
(lower_num >> (64 - left_shift_bits));
lower_num = lower_num << left_shift_bits;
}
if (right_shift_bits >= 64) {
lower_num = upper_num >> (right_shift_bits - 64);
upper_num = 0;
} else {
lower_num = (lower_num >> right_shift_bits) |
(upper_num << (64 - right_shift_bits));
upper_num = upper_num >> right_shift_bits;
}
#ifdef __BIG_ENDIAN_BITFIELD
print_num[0] = upper_num;
print_num[1] = lower_num;
#else
print_num[0] = lower_num;
print_num[1] = upper_num;
#endif
}
static void btf_bitfield_show(void *data, u8 bits_offset,
u8 nr_bits, struct btf_show *show)
{
u16 left_shift_bits, right_shift_bits;
u8 nr_copy_bytes;
u8 nr_copy_bits;
u64 print_num[2] = {};
nr_copy_bits = nr_bits + bits_offset;
nr_copy_bytes = BITS_ROUNDUP_BYTES(nr_copy_bits);
memcpy(print_num, data, nr_copy_bytes);
#ifdef __BIG_ENDIAN_BITFIELD
left_shift_bits = bits_offset;
#else
left_shift_bits = BITS_PER_U128 - nr_copy_bits;
#endif
right_shift_bits = BITS_PER_U128 - nr_bits;
btf_int128_shift(print_num, left_shift_bits, right_shift_bits);
btf_int128_print(show, print_num);
}
static void btf_int_bits_show(const struct btf *btf,
const struct btf_type *t,
void *data, u8 bits_offset,
struct btf_show *show)
{
u32 int_data = btf_type_int(t);
u8 nr_bits = BTF_INT_BITS(int_data);
u8 total_bits_offset;
/*
* bits_offset is at most 7.
* BTF_INT_OFFSET() cannot exceed 128 bits.
*/
total_bits_offset = bits_offset + BTF_INT_OFFSET(int_data);
data += BITS_ROUNDDOWN_BYTES(total_bits_offset);
bits_offset = BITS_PER_BYTE_MASKED(total_bits_offset);
btf_bitfield_show(data, bits_offset, nr_bits, show);
}
static void btf_int_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
u32 int_data = btf_type_int(t);
u8 encoding = BTF_INT_ENCODING(int_data);
bool sign = encoding & BTF_INT_SIGNED;
u8 nr_bits = BTF_INT_BITS(int_data);
void *safe_data;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
if (bits_offset || BTF_INT_OFFSET(int_data) ||
BITS_PER_BYTE_MASKED(nr_bits)) {
btf_int_bits_show(btf, t, safe_data, bits_offset, show);
goto out;
}
switch (nr_bits) {
case 128:
btf_int128_print(show, safe_data);
break;
case 64:
if (sign)
btf_show_type_value(show, "%lld", *(s64 *)safe_data);
else
btf_show_type_value(show, "%llu", *(u64 *)safe_data);
break;
case 32:
if (sign)
btf_show_type_value(show, "%d", *(s32 *)safe_data);
else
btf_show_type_value(show, "%u", *(u32 *)safe_data);
break;
case 16:
if (sign)
btf_show_type_value(show, "%d", *(s16 *)safe_data);
else
btf_show_type_value(show, "%u", *(u16 *)safe_data);
break;
case 8:
if (show->state.array_encoding == BTF_INT_CHAR) {
/* check for null terminator */
if (show->state.array_terminated)
break;
if (*(char *)data == '\0') {
show->state.array_terminated = 1;
break;
}
if (isprint(*(char *)data)) {
btf_show_type_value(show, "'%c'",
*(char *)safe_data);
break;
}
}
if (sign)
btf_show_type_value(show, "%d", *(s8 *)safe_data);
else
btf_show_type_value(show, "%u", *(u8 *)safe_data);
break;
default:
btf_int_bits_show(btf, t, safe_data, bits_offset, show);
break;
}
out:
btf_show_end_type(show);
}
static const struct btf_kind_operations int_ops = {
.check_meta = btf_int_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_int_check_member,
.check_kflag_member = btf_int_check_kflag_member,
.log_details = btf_int_log,
.show = btf_int_show,
};
static int btf_modifier_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
const struct btf_type *resolved_type;
u32 resolved_type_id = member->type;
struct btf_member resolved_member;
struct btf *btf = env->btf;
resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
if (!resolved_type) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member");
return -EINVAL;
}
resolved_member = *member;
resolved_member.type = resolved_type_id;
return btf_type_ops(resolved_type)->check_member(env, struct_type,
&resolved_member,
resolved_type);
}
static int btf_modifier_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
const struct btf_type *resolved_type;
u32 resolved_type_id = member->type;
struct btf_member resolved_member;
struct btf *btf = env->btf;
resolved_type = btf_type_id_size(btf, &resolved_type_id, NULL);
if (!resolved_type) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member");
return -EINVAL;
}
resolved_member = *member;
resolved_member.type = resolved_type_id;
return btf_type_ops(resolved_type)->check_kflag_member(env, struct_type,
&resolved_member,
resolved_type);
}
static int btf_ptr_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_size, struct_bits_off, bytes_offset;
struct_size = struct_type->size;
struct_bits_off = member->offset;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
if (struct_size - bytes_offset < sizeof(void *)) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_ref_type_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const char *value;
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!BTF_TYPE_ID_VALID(t->type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
/* typedef/type_tag type must have a valid name, and other ref types,
* volatile, const, restrict, should have a null name.
*/
if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF) {
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
} else if (BTF_INFO_KIND(t->info) == BTF_KIND_TYPE_TAG) {
value = btf_name_by_offset(env->btf, t->name_off);
if (!value || !value[0]) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
} else {
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_modifier_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *t = v->t;
const struct btf_type *next_type;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
/* Figure out the resolved next_type_id with size.
* They will be stored in the current modifier's
* resolved_ids and resolved_sizes such that it can
* save us a few type-following when we use it later (e.g. in
* pretty print).
*/
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
if (env_type_is_resolved(env, next_type_id))
next_type = btf_type_id_resolve(btf, &next_type_id);
/* "typedef void new_void", "const void"...etc */
if (!btf_type_is_void(next_type) &&
!btf_type_is_fwd(next_type) &&
!btf_type_is_func_proto(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static int btf_var_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
if (btf_type_is_modifier(next_type)) {
const struct btf_type *resolved_type;
u32 resolved_type_id;
resolved_type_id = next_type_id;
resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
if (btf_type_is_ptr(resolved_type) &&
!env_type_is_resolve_sink(env, resolved_type) &&
!env_type_is_resolved(env, resolved_type_id))
return env_stack_push(env, resolved_type,
resolved_type_id);
}
/* We must resolve to something concrete at this point, no
* forward types or similar that would resolve to size of
* zero is allowed.
*/
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static int btf_ptr_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || btf_type_is_resolve_source_only(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
/* If the modifier was RESOLVED during RESOLVE_STRUCT_OR_ARRAY,
* the modifier may have stopped resolving when it was resolved
* to a ptr (last-resolved-ptr).
*
* We now need to continue from the last-resolved-ptr to
* ensure the last-resolved-ptr will not referring back to
* the current ptr (t).
*/
if (btf_type_is_modifier(next_type)) {
const struct btf_type *resolved_type;
u32 resolved_type_id;
resolved_type_id = next_type_id;
resolved_type = btf_type_id_resolve(btf, &resolved_type_id);
if (btf_type_is_ptr(resolved_type) &&
!env_type_is_resolve_sink(env, resolved_type) &&
!env_type_is_resolved(env, resolved_type_id))
return env_stack_push(env, resolved_type,
resolved_type_id);
}
if (!btf_type_id_size(btf, &next_type_id, NULL)) {
if (env_type_is_resolved(env, next_type_id))
next_type = btf_type_id_resolve(btf, &next_type_id);
if (!btf_type_is_void(next_type) &&
!btf_type_is_fwd(next_type) &&
!btf_type_is_func_proto(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static void btf_modifier_show(const struct btf *btf,
const struct btf_type *t,
u32 type_id, void *data,
u8 bits_offset, struct btf_show *show)
{
if (btf->resolved_ids)
t = btf_type_id_resolve(btf, &type_id);
else
t = btf_type_skip_modifiers(btf, type_id, NULL);
btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}
static void btf_var_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
t = btf_type_id_resolve(btf, &type_id);
btf_type_ops(t)->show(btf, t, type_id, data, bits_offset, show);
}
static void btf_ptr_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
void *safe_data;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
/* It is a hashed value unless BTF_SHOW_PTR_RAW is specified */
if (show->flags & BTF_SHOW_PTR_RAW)
btf_show_type_value(show, "0x%px", *(void **)safe_data);
else
btf_show_type_value(show, "0x%p", *(void **)safe_data);
btf_show_end_type(show);
}
static void btf_ref_type_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "type_id=%u", t->type);
}
static struct btf_kind_operations modifier_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_modifier_resolve,
.check_member = btf_modifier_check_member,
.check_kflag_member = btf_modifier_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_modifier_show,
};
static struct btf_kind_operations ptr_ops = {
.check_meta = btf_ref_type_check_meta,
.resolve = btf_ptr_resolve,
.check_member = btf_ptr_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_ptr_show,
};
static s32 btf_fwd_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (t->type) {
btf_verifier_log_type(env, t, "type != 0");
return -EINVAL;
}
/* fwd type must have a valid name */
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static void btf_fwd_type_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "%s", btf_type_kflag(t) ? "union" : "struct");
}
static struct btf_kind_operations fwd_ops = {
.check_meta = btf_fwd_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_fwd_type_log,
.show = btf_df_show,
};
static int btf_array_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
u32 array_type_id, array_size;
struct btf *btf = env->btf;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
array_type_id = member->type;
btf_type_id_size(btf, &array_type_id, &array_size);
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < array_size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_array_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_array *array = btf_type_array(t);
u32 meta_needed = sizeof(*array);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
/* array type should not have a name */
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (t->size) {
btf_verifier_log_type(env, t, "size != 0");
return -EINVAL;
}
/* Array elem type and index type cannot be in type void,
* so !array->type and !array->index_type are not allowed.
*/
if (!array->type || !BTF_TYPE_ID_VALID(array->type)) {
btf_verifier_log_type(env, t, "Invalid elem");
return -EINVAL;
}
if (!array->index_type || !BTF_TYPE_ID_VALID(array->index_type)) {
btf_verifier_log_type(env, t, "Invalid index");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static int btf_array_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_array *array = btf_type_array(v->t);
const struct btf_type *elem_type, *index_type;
u32 elem_type_id, index_type_id;
struct btf *btf = env->btf;
u32 elem_size;
/* Check array->index_type */
index_type_id = array->index_type;
index_type = btf_type_by_id(btf, index_type_id);
if (btf_type_nosize_or_null(index_type) ||
btf_type_is_resolve_source_only(index_type)) {
btf_verifier_log_type(env, v->t, "Invalid index");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, index_type) &&
!env_type_is_resolved(env, index_type_id))
return env_stack_push(env, index_type, index_type_id);
index_type = btf_type_id_size(btf, &index_type_id, NULL);
if (!index_type || !btf_type_is_int(index_type) ||
!btf_type_int_is_regular(index_type)) {
btf_verifier_log_type(env, v->t, "Invalid index");
return -EINVAL;
}
/* Check array->type */
elem_type_id = array->type;
elem_type = btf_type_by_id(btf, elem_type_id);
if (btf_type_nosize_or_null(elem_type) ||
btf_type_is_resolve_source_only(elem_type)) {
btf_verifier_log_type(env, v->t,
"Invalid elem");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, elem_type) &&
!env_type_is_resolved(env, elem_type_id))
return env_stack_push(env, elem_type, elem_type_id);
elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
if (!elem_type) {
btf_verifier_log_type(env, v->t, "Invalid elem");
return -EINVAL;
}
if (btf_type_is_int(elem_type) && !btf_type_int_is_regular(elem_type)) {
btf_verifier_log_type(env, v->t, "Invalid array of int");
return -EINVAL;
}
if (array->nelems && elem_size > U32_MAX / array->nelems) {
btf_verifier_log_type(env, v->t,
"Array size overflows U32_MAX");
return -EINVAL;
}
env_stack_pop_resolved(env, elem_type_id, elem_size * array->nelems);
return 0;
}
static void btf_array_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_array *array = btf_type_array(t);
btf_verifier_log(env, "type_id=%u index_type_id=%u nr_elems=%u",
array->type, array->index_type, array->nelems);
}
static void __btf_array_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_array *array = btf_type_array(t);
const struct btf_kind_operations *elem_ops;
const struct btf_type *elem_type;
u32 i, elem_size = 0, elem_type_id;
u16 encoding = 0;
elem_type_id = array->type;
elem_type = btf_type_skip_modifiers(btf, elem_type_id, NULL);
if (elem_type && btf_type_has_size(elem_type))
elem_size = elem_type->size;
if (elem_type && btf_type_is_int(elem_type)) {
u32 int_type = btf_type_int(elem_type);
encoding = BTF_INT_ENCODING(int_type);
/*
* BTF_INT_CHAR encoding never seems to be set for
* char arrays, so if size is 1 and element is
* printable as a char, we'll do that.
*/
if (elem_size == 1)
encoding = BTF_INT_CHAR;
}
if (!btf_show_start_array_type(show, t, type_id, encoding, data))
return;
if (!elem_type)
goto out;
elem_ops = btf_type_ops(elem_type);
for (i = 0; i < array->nelems; i++) {
btf_show_start_array_member(show);
elem_ops->show(btf, elem_type, elem_type_id, data,
bits_offset, show);
data += elem_size;
btf_show_end_array_member(show);
if (show->state.array_terminated)
break;
}
out:
btf_show_end_array_type(show);
}
static void btf_array_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *m = show->state.member;
/*
* First check if any members would be shown (are non-zero).
* See comments above "struct btf_show" definition for more
* details on how this works at a high-level.
*/
if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
if (!show->state.depth_check) {
show->state.depth_check = show->state.depth + 1;
show->state.depth_to_show = 0;
}
__btf_array_show(btf, t, type_id, data, bits_offset, show);
show->state.member = m;
if (show->state.depth_check != show->state.depth + 1)
return;
show->state.depth_check = 0;
if (show->state.depth_to_show <= show->state.depth)
return;
/*
* Reaching here indicates we have recursed and found
* non-zero array member(s).
*/
}
__btf_array_show(btf, t, type_id, data, bits_offset, show);
}
static struct btf_kind_operations array_ops = {
.check_meta = btf_array_check_meta,
.resolve = btf_array_resolve,
.check_member = btf_array_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_array_log,
.show = btf_array_show,
};
static int btf_struct_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < member_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_struct_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
bool is_union = BTF_INFO_KIND(t->info) == BTF_KIND_UNION;
const struct btf_member *member;
u32 meta_needed, last_offset;
struct btf *btf = env->btf;
u32 struct_size = t->size;
u32 offset;
u16 i;
meta_needed = btf_type_vlen(t) * sizeof(*member);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
/* struct type either no name or a valid one */
if (t->name_off &&
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
last_offset = 0;
for_each_member(i, t, member) {
if (!btf_name_offset_valid(btf, member->name_off)) {
btf_verifier_log_member(env, t, member,
"Invalid member name_offset:%u",
member->name_off);
return -EINVAL;
}
/* struct member either no name or a valid one */
if (member->name_off &&
!btf_name_valid_identifier(btf, member->name_off)) {
btf_verifier_log_member(env, t, member, "Invalid name");
return -EINVAL;
}
/* A member cannot be in type void */
if (!member->type || !BTF_TYPE_ID_VALID(member->type)) {
btf_verifier_log_member(env, t, member,
"Invalid type_id");
return -EINVAL;
}
offset = __btf_member_bit_offset(t, member);
if (is_union && offset) {
btf_verifier_log_member(env, t, member,
"Invalid member bits_offset");
return -EINVAL;
}
/*
* ">" instead of ">=" because the last member could be
* "char a[0];"
*/
if (last_offset > offset) {
btf_verifier_log_member(env, t, member,
"Invalid member bits_offset");
return -EINVAL;
}
if (BITS_ROUNDUP_BYTES(offset) > struct_size) {
btf_verifier_log_member(env, t, member,
"Member bits_offset exceeds its struct size");
return -EINVAL;
}
btf_verifier_log_member(env, t, member, NULL);
last_offset = offset;
}
return meta_needed;
}
static int btf_struct_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_member *member;
int err;
u16 i;
/* Before continue resolving the next_member,
* ensure the last member is indeed resolved to a
* type with size info.
*/
if (v->next_member) {
const struct btf_type *last_member_type;
const struct btf_member *last_member;
u16 last_member_type_id;
last_member = btf_type_member(v->t) + v->next_member - 1;
last_member_type_id = last_member->type;
if (WARN_ON_ONCE(!env_type_is_resolved(env,
last_member_type_id)))
return -EINVAL;
last_member_type = btf_type_by_id(env->btf,
last_member_type_id);
if (btf_type_kflag(v->t))
err = btf_type_ops(last_member_type)->check_kflag_member(env, v->t,
last_member,
last_member_type);
else
err = btf_type_ops(last_member_type)->check_member(env, v->t,
last_member,
last_member_type);
if (err)
return err;
}
for_each_member_from(i, v->next_member, v->t, member) {
u32 member_type_id = member->type;
const struct btf_type *member_type = btf_type_by_id(env->btf,
member_type_id);
if (btf_type_nosize_or_null(member_type) ||
btf_type_is_resolve_source_only(member_type)) {
btf_verifier_log_member(env, v->t, member,
"Invalid member");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, member_type) &&
!env_type_is_resolved(env, member_type_id)) {
env_stack_set_next_member(env, i + 1);
return env_stack_push(env, member_type, member_type_id);
}
if (btf_type_kflag(v->t))
err = btf_type_ops(member_type)->check_kflag_member(env, v->t,
member,
member_type);
else
err = btf_type_ops(member_type)->check_member(env, v->t,
member,
member_type);
if (err)
return err;
}
env_stack_pop_resolved(env, 0, 0);
return 0;
}
static void btf_struct_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
enum btf_field_type {
BTF_FIELD_SPIN_LOCK,
BTF_FIELD_TIMER,
BTF_FIELD_KPTR,
};
enum {
BTF_FIELD_IGNORE = 0,
BTF_FIELD_FOUND = 1,
};
struct btf_field_info {
u32 type_id;
u32 off;
enum bpf_kptr_type type;
};
static int btf_find_struct(const struct btf *btf, const struct btf_type *t,
u32 off, int sz, struct btf_field_info *info)
{
if (!__btf_type_is_struct(t))
return BTF_FIELD_IGNORE;
if (t->size != sz)
return BTF_FIELD_IGNORE;
info->off = off;
return BTF_FIELD_FOUND;
}
static int btf_find_kptr(const struct btf *btf, const struct btf_type *t,
u32 off, int sz, struct btf_field_info *info)
{
enum bpf_kptr_type type;
u32 res_id;
/* For PTR, sz is always == 8 */
if (!btf_type_is_ptr(t))
return BTF_FIELD_IGNORE;
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_type_tag(t))
return BTF_FIELD_IGNORE;
/* Reject extra tags */
if (btf_type_is_type_tag(btf_type_by_id(btf, t->type)))
return -EINVAL;
if (!strcmp("kptr", __btf_name_by_offset(btf, t->name_off)))
type = BPF_KPTR_UNREF;
else if (!strcmp("kptr_ref", __btf_name_by_offset(btf, t->name_off)))
type = BPF_KPTR_REF;
else
return -EINVAL;
/* Get the base type */
t = btf_type_skip_modifiers(btf, t->type, &res_id);
/* Only pointer to struct is allowed */
if (!__btf_type_is_struct(t))
return -EINVAL;
info->type_id = res_id;
info->off = off;
info->type = type;
return BTF_FIELD_FOUND;
}
static int btf_find_struct_field(const struct btf *btf, const struct btf_type *t,
const char *name, int sz, int align,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const struct btf_member *member;
struct btf_field_info tmp;
int ret, idx = 0;
u32 i, off;
for_each_member(i, t, member) {
const struct btf_type *member_type = btf_type_by_id(btf,
member->type);
if (name && strcmp(__btf_name_by_offset(btf, member_type->name_off), name))
continue;
off = __btf_member_bit_offset(t, member);
if (off % 8)
/* valid C code cannot generate such BTF */
return -EINVAL;
off /= 8;
if (off % align)
return -EINVAL;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
case BTF_FIELD_TIMER:
ret = btf_find_struct(btf, member_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
case BTF_FIELD_KPTR:
ret = btf_find_kptr(btf, member_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
default:
return -EFAULT;
}
if (ret == BTF_FIELD_IGNORE)
continue;
if (idx >= info_cnt)
return -E2BIG;
++idx;
}
return idx;
}
static int btf_find_datasec_var(const struct btf *btf, const struct btf_type *t,
const char *name, int sz, int align,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const struct btf_var_secinfo *vsi;
struct btf_field_info tmp;
int ret, idx = 0;
u32 i, off;
for_each_vsi(i, t, vsi) {
const struct btf_type *var = btf_type_by_id(btf, vsi->type);
const struct btf_type *var_type = btf_type_by_id(btf, var->type);
off = vsi->offset;
if (name && strcmp(__btf_name_by_offset(btf, var_type->name_off), name))
continue;
if (vsi->size != sz)
continue;
if (off % align)
return -EINVAL;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
case BTF_FIELD_TIMER:
ret = btf_find_struct(btf, var_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
case BTF_FIELD_KPTR:
ret = btf_find_kptr(btf, var_type, off, sz,
idx < info_cnt ? &info[idx] : &tmp);
if (ret < 0)
return ret;
break;
default:
return -EFAULT;
}
if (ret == BTF_FIELD_IGNORE)
continue;
if (idx >= info_cnt)
return -E2BIG;
++idx;
}
return idx;
}
static int btf_find_field(const struct btf *btf, const struct btf_type *t,
enum btf_field_type field_type,
struct btf_field_info *info, int info_cnt)
{
const char *name;
int sz, align;
switch (field_type) {
case BTF_FIELD_SPIN_LOCK:
name = "bpf_spin_lock";
sz = sizeof(struct bpf_spin_lock);
align = __alignof__(struct bpf_spin_lock);
break;
case BTF_FIELD_TIMER:
name = "bpf_timer";
sz = sizeof(struct bpf_timer);
align = __alignof__(struct bpf_timer);
break;
case BTF_FIELD_KPTR:
name = NULL;
sz = sizeof(u64);
align = 8;
break;
default:
return -EFAULT;
}
if (__btf_type_is_struct(t))
return btf_find_struct_field(btf, t, name, sz, align, field_type, info, info_cnt);
else if (btf_type_is_datasec(t))
return btf_find_datasec_var(btf, t, name, sz, align, field_type, info, info_cnt);
return -EINVAL;
}
/* find 'struct bpf_spin_lock' in map value.
* return >= 0 offset if found
* and < 0 in case of error
*/
int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t)
{
struct btf_field_info info;
int ret;
ret = btf_find_field(btf, t, BTF_FIELD_SPIN_LOCK, &info, 1);
if (ret < 0)
return ret;
if (!ret)
return -ENOENT;
return info.off;
}
int btf_find_timer(const struct btf *btf, const struct btf_type *t)
{
struct btf_field_info info;
int ret;
ret = btf_find_field(btf, t, BTF_FIELD_TIMER, &info, 1);
if (ret < 0)
return ret;
if (!ret)
return -ENOENT;
return info.off;
}
struct bpf_map_value_off *btf_parse_kptrs(const struct btf *btf,
const struct btf_type *t)
{
struct btf_field_info info_arr[BPF_MAP_VALUE_OFF_MAX];
struct bpf_map_value_off *tab;
struct btf *kernel_btf = NULL;
struct module *mod = NULL;
int ret, i, nr_off;
ret = btf_find_field(btf, t, BTF_FIELD_KPTR, info_arr, ARRAY_SIZE(info_arr));
if (ret < 0)
return ERR_PTR(ret);
if (!ret)
return NULL;
nr_off = ret;
tab = kzalloc(offsetof(struct bpf_map_value_off, off[nr_off]), GFP_KERNEL | __GFP_NOWARN);
if (!tab)
return ERR_PTR(-ENOMEM);
for (i = 0; i < nr_off; i++) {
const struct btf_type *t;
s32 id;
/* Find type in map BTF, and use it to look up the matching type
* in vmlinux or module BTFs, by name and kind.
*/
t = btf_type_by_id(btf, info_arr[i].type_id);
id = bpf_find_btf_id(__btf_name_by_offset(btf, t->name_off), BTF_INFO_KIND(t->info),
&kernel_btf);
if (id < 0) {
ret = id;
goto end;
}
/* Find and stash the function pointer for the destruction function that
* needs to be eventually invoked from the map free path.
*/
if (info_arr[i].type == BPF_KPTR_REF) {
const struct btf_type *dtor_func;
const char *dtor_func_name;
unsigned long addr;
s32 dtor_btf_id;
/* This call also serves as a whitelist of allowed objects that
* can be used as a referenced pointer and be stored in a map at
* the same time.
*/
dtor_btf_id = btf_find_dtor_kfunc(kernel_btf, id);
if (dtor_btf_id < 0) {
ret = dtor_btf_id;
goto end_btf;
}
dtor_func = btf_type_by_id(kernel_btf, dtor_btf_id);
if (!dtor_func) {
ret = -ENOENT;
goto end_btf;
}
if (btf_is_module(kernel_btf)) {
mod = btf_try_get_module(kernel_btf);
if (!mod) {
ret = -ENXIO;
goto end_btf;
}
}
/* We already verified dtor_func to be btf_type_is_func
* in register_btf_id_dtor_kfuncs.
*/
dtor_func_name = __btf_name_by_offset(kernel_btf, dtor_func->name_off);
addr = kallsyms_lookup_name(dtor_func_name);
if (!addr) {
ret = -EINVAL;
goto end_mod;
}
tab->off[i].kptr.dtor = (void *)addr;
}
tab->off[i].offset = info_arr[i].off;
tab->off[i].type = info_arr[i].type;
tab->off[i].kptr.btf_id = id;
tab->off[i].kptr.btf = kernel_btf;
tab->off[i].kptr.module = mod;
}
tab->nr_off = nr_off;
return tab;
end_mod:
module_put(mod);
end_btf:
btf_put(kernel_btf);
end:
while (i--) {
btf_put(tab->off[i].kptr.btf);
if (tab->off[i].kptr.module)
module_put(tab->off[i].kptr.module);
}
kfree(tab);
return ERR_PTR(ret);
}
static void __btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *member;
void *safe_data;
u32 i;
safe_data = btf_show_start_struct_type(show, t, type_id, data);
if (!safe_data)
return;
for_each_member(i, t, member) {
const struct btf_type *member_type = btf_type_by_id(btf,
member->type);
const struct btf_kind_operations *ops;
u32 member_offset, bitfield_size;
u32 bytes_offset;
u8 bits8_offset;
btf_show_start_member(show, member);
member_offset = __btf_member_bit_offset(t, member);
bitfield_size = __btf_member_bitfield_size(t, member);
bytes_offset = BITS_ROUNDDOWN_BYTES(member_offset);
bits8_offset = BITS_PER_BYTE_MASKED(member_offset);
if (bitfield_size) {
safe_data = btf_show_start_type(show, member_type,
member->type,
data + bytes_offset);
if (safe_data)
btf_bitfield_show(safe_data,
bits8_offset,
bitfield_size, show);
btf_show_end_type(show);
} else {
ops = btf_type_ops(member_type);
ops->show(btf, member_type, member->type,
data + bytes_offset, bits8_offset, show);
}
btf_show_end_member(show);
}
btf_show_end_struct_type(show);
}
static void btf_struct_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_member *m = show->state.member;
/*
* First check if any members would be shown (are non-zero).
* See comments above "struct btf_show" definition for more
* details on how this works at a high-level.
*/
if (show->state.depth > 0 && !(show->flags & BTF_SHOW_ZERO)) {
if (!show->state.depth_check) {
show->state.depth_check = show->state.depth + 1;
show->state.depth_to_show = 0;
}
__btf_struct_show(btf, t, type_id, data, bits_offset, show);
/* Restore saved member data here */
show->state.member = m;
if (show->state.depth_check != show->state.depth + 1)
return;
show->state.depth_check = 0;
if (show->state.depth_to_show <= show->state.depth)
return;
/*
* Reaching here indicates we have recursed and found
* non-zero child values.
*/
}
__btf_struct_show(btf, t, type_id, data, bits_offset, show);
}
static struct btf_kind_operations struct_ops = {
.check_meta = btf_struct_check_meta,
.resolve = btf_struct_resolve,
.check_member = btf_struct_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_struct_log,
.show = btf_struct_show,
};
static int btf_enum_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off = member->offset;
u32 struct_size, bytes_offset;
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
if (struct_size - bytes_offset < member_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static int btf_enum_check_kflag_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u32 struct_bits_off, nr_bits, bytes_end, struct_size;
u32 int_bitsize = sizeof(int) * BITS_PER_BYTE;
struct_bits_off = BTF_MEMBER_BIT_OFFSET(member->offset);
nr_bits = BTF_MEMBER_BITFIELD_SIZE(member->offset);
if (!nr_bits) {
if (BITS_PER_BYTE_MASKED(struct_bits_off)) {
btf_verifier_log_member(env, struct_type, member,
"Member is not byte aligned");
return -EINVAL;
}
nr_bits = int_bitsize;
} else if (nr_bits > int_bitsize) {
btf_verifier_log_member(env, struct_type, member,
"Invalid member bitfield_size");
return -EINVAL;
}
struct_size = struct_type->size;
bytes_end = BITS_ROUNDUP_BYTES(struct_bits_off + nr_bits);
if (struct_size < bytes_end) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static s32 btf_enum_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_enum *enums = btf_type_enum(t);
struct btf *btf = env->btf;
const char *fmt_str;
u16 i, nr_enums;
u32 meta_needed;
nr_enums = btf_type_vlen(t);
meta_needed = nr_enums * sizeof(*enums);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (t->size > 8 || !is_power_of_2(t->size)) {
btf_verifier_log_type(env, t, "Unexpected size");
return -EINVAL;
}
/* enum type either no name or a valid one */
if (t->name_off &&
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
for (i = 0; i < nr_enums; i++) {
if (!btf_name_offset_valid(btf, enums[i].name_off)) {
btf_verifier_log(env, "\tInvalid name_offset:%u",
enums[i].name_off);
return -EINVAL;
}
/* enum member must have a valid name */
if (!enums[i].name_off ||
!btf_name_valid_identifier(btf, enums[i].name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (env->log.level == BPF_LOG_KERNEL)
continue;
fmt_str = btf_type_kflag(t) ? "\t%s val=%d\n" : "\t%s val=%u\n";
btf_verifier_log(env, fmt_str,
__btf_name_by_offset(btf, enums[i].name_off),
enums[i].val);
}
return meta_needed;
}
static void btf_enum_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
static void btf_enum_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_enum *enums = btf_type_enum(t);
u32 i, nr_enums = btf_type_vlen(t);
void *safe_data;
int v;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
v = *(int *)safe_data;
for (i = 0; i < nr_enums; i++) {
if (v != enums[i].val)
continue;
btf_show_type_value(show, "%s",
__btf_name_by_offset(btf,
enums[i].name_off));
btf_show_end_type(show);
return;
}
if (btf_type_kflag(t))
btf_show_type_value(show, "%d", v);
else
btf_show_type_value(show, "%u", v);
btf_show_end_type(show);
}
static struct btf_kind_operations enum_ops = {
.check_meta = btf_enum_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_enum_check_member,
.check_kflag_member = btf_enum_check_kflag_member,
.log_details = btf_enum_log,
.show = btf_enum_show,
};
static s32 btf_enum64_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_enum64 *enums = btf_type_enum64(t);
struct btf *btf = env->btf;
const char *fmt_str;
u16 i, nr_enums;
u32 meta_needed;
nr_enums = btf_type_vlen(t);
meta_needed = nr_enums * sizeof(*enums);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (t->size > 8 || !is_power_of_2(t->size)) {
btf_verifier_log_type(env, t, "Unexpected size");
return -EINVAL;
}
/* enum type either no name or a valid one */
if (t->name_off &&
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
for (i = 0; i < nr_enums; i++) {
if (!btf_name_offset_valid(btf, enums[i].name_off)) {
btf_verifier_log(env, "\tInvalid name_offset:%u",
enums[i].name_off);
return -EINVAL;
}
/* enum member must have a valid name */
if (!enums[i].name_off ||
!btf_name_valid_identifier(btf, enums[i].name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (env->log.level == BPF_LOG_KERNEL)
continue;
fmt_str = btf_type_kflag(t) ? "\t%s val=%lld\n" : "\t%s val=%llu\n";
btf_verifier_log(env, fmt_str,
__btf_name_by_offset(btf, enums[i].name_off),
btf_enum64_value(enums + i));
}
return meta_needed;
}
static void btf_enum64_show(const struct btf *btf, const struct btf_type *t,
u32 type_id, void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_enum64 *enums = btf_type_enum64(t);
u32 i, nr_enums = btf_type_vlen(t);
void *safe_data;
s64 v;
safe_data = btf_show_start_type(show, t, type_id, data);
if (!safe_data)
return;
v = *(u64 *)safe_data;
for (i = 0; i < nr_enums; i++) {
if (v != btf_enum64_value(enums + i))
continue;
btf_show_type_value(show, "%s",
__btf_name_by_offset(btf,
enums[i].name_off));
btf_show_end_type(show);
return;
}
if (btf_type_kflag(t))
btf_show_type_value(show, "%lld", v);
else
btf_show_type_value(show, "%llu", v);
btf_show_end_type(show);
}
static struct btf_kind_operations enum64_ops = {
.check_meta = btf_enum64_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_enum_check_member,
.check_kflag_member = btf_enum_check_kflag_member,
.log_details = btf_enum_log,
.show = btf_enum64_show,
};
static s32 btf_func_proto_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 meta_needed = btf_type_vlen(t) * sizeof(struct btf_param);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (t->name_off) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_func_proto_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_param *args = (const struct btf_param *)(t + 1);
u16 nr_args = btf_type_vlen(t), i;
btf_verifier_log(env, "return=%u args=(", t->type);
if (!nr_args) {
btf_verifier_log(env, "void");
goto done;
}
if (nr_args == 1 && !args[0].type) {
/* Only one vararg */
btf_verifier_log(env, "vararg");
goto done;
}
btf_verifier_log(env, "%u %s", args[0].type,
__btf_name_by_offset(env->btf,
args[0].name_off));
for (i = 1; i < nr_args - 1; i++)
btf_verifier_log(env, ", %u %s", args[i].type,
__btf_name_by_offset(env->btf,
args[i].name_off));
if (nr_args > 1) {
const struct btf_param *last_arg = &args[nr_args - 1];
if (last_arg->type)
btf_verifier_log(env, ", %u %s", last_arg->type,
__btf_name_by_offset(env->btf,
last_arg->name_off));
else
btf_verifier_log(env, ", vararg");
}
done:
btf_verifier_log(env, ")");
}
static struct btf_kind_operations func_proto_ops = {
.check_meta = btf_func_proto_check_meta,
.resolve = btf_df_resolve,
/*
* BTF_KIND_FUNC_PROTO cannot be directly referred by
* a struct's member.
*
* It should be a function pointer instead.
* (i.e. struct's member -> BTF_KIND_PTR -> BTF_KIND_FUNC_PROTO)
*
* Hence, there is no btf_func_check_member().
*/
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_func_proto_log,
.show = btf_df_show,
};
static s32 btf_func_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (!t->name_off ||
!btf_name_valid_identifier(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
btf_verifier_log_type(env, t, "Invalid func linkage");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_func_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
int err;
err = btf_func_check(env, t);
if (err)
return err;
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static struct btf_kind_operations func_ops = {
.check_meta = btf_func_check_meta,
.resolve = btf_func_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_ref_type_log,
.show = btf_df_show,
};
static s32 btf_var_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_var *var;
u32 meta_needed = sizeof(*var);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!t->name_off ||
!__btf_name_valid(env->btf, t->name_off, true)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
/* A var cannot be in type void */
if (!t->type || !BTF_TYPE_ID_VALID(t->type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
var = btf_type_var(t);
if (var->linkage != BTF_VAR_STATIC &&
var->linkage != BTF_VAR_GLOBAL_ALLOCATED) {
btf_verifier_log_type(env, t, "Linkage not supported");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static void btf_var_log(struct btf_verifier_env *env, const struct btf_type *t)
{
const struct btf_var *var = btf_type_var(t);
btf_verifier_log(env, "type_id=%u linkage=%u", t->type, var->linkage);
}
static const struct btf_kind_operations var_ops = {
.check_meta = btf_var_check_meta,
.resolve = btf_var_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_var_log,
.show = btf_var_show,
};
static s32 btf_datasec_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_var_secinfo *vsi;
u64 last_vsi_end_off = 0, sum = 0;
u32 i, meta_needed;
meta_needed = btf_type_vlen(t) * sizeof(*vsi);
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
if (!t->size) {
btf_verifier_log_type(env, t, "size == 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (!t->name_off ||
!btf_name_valid_section(env->btf, t->name_off)) {
btf_verifier_log_type(env, t, "Invalid name");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
for_each_vsi(i, t, vsi) {
/* A var cannot be in type void */
if (!vsi->type || !BTF_TYPE_ID_VALID(vsi->type)) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid type_id");
return -EINVAL;
}
if (vsi->offset < last_vsi_end_off || vsi->offset >= t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid offset");
return -EINVAL;
}
if (!vsi->size || vsi->size > t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid size");
return -EINVAL;
}
last_vsi_end_off = vsi->offset + vsi->size;
if (last_vsi_end_off > t->size) {
btf_verifier_log_vsi(env, t, vsi,
"Invalid offset+size");
return -EINVAL;
}
btf_verifier_log_vsi(env, t, vsi, NULL);
sum += vsi->size;
}
if (t->size < sum) {
btf_verifier_log_type(env, t, "Invalid btf_info size");
return -EINVAL;
}
return meta_needed;
}
static int btf_datasec_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_var_secinfo *vsi;
struct btf *btf = env->btf;
u16 i;
for_each_vsi_from(i, v->next_member, v->t, vsi) {
u32 var_type_id = vsi->type, type_id, type_size = 0;
const struct btf_type *var_type = btf_type_by_id(env->btf,
var_type_id);
if (!var_type || !btf_type_is_var(var_type)) {
btf_verifier_log_vsi(env, v->t, vsi,
"Not a VAR kind member");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, var_type) &&
!env_type_is_resolved(env, var_type_id)) {
env_stack_set_next_member(env, i + 1);
return env_stack_push(env, var_type, var_type_id);
}
type_id = var_type->type;
if (!btf_type_id_size(btf, &type_id, &type_size)) {
btf_verifier_log_vsi(env, v->t, vsi, "Invalid type");
return -EINVAL;
}
if (vsi->size < type_size) {
btf_verifier_log_vsi(env, v->t, vsi, "Invalid size");
return -EINVAL;
}
}
env_stack_pop_resolved(env, 0, 0);
return 0;
}
static void btf_datasec_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u vlen=%u", t->size, btf_type_vlen(t));
}
static void btf_datasec_show(const struct btf *btf,
const struct btf_type *t, u32 type_id,
void *data, u8 bits_offset,
struct btf_show *show)
{
const struct btf_var_secinfo *vsi;
const struct btf_type *var;
u32 i;
if (!btf_show_start_type(show, t, type_id, data))
return;
btf_show_type_value(show, "section (\"%s\") = {",
__btf_name_by_offset(btf, t->name_off));
for_each_vsi(i, t, vsi) {
var = btf_type_by_id(btf, vsi->type);
if (i)
btf_show(show, ",");
btf_type_ops(var)->show(btf, var, vsi->type,
data + vsi->offset, bits_offset, show);
}
btf_show_end_type(show);
}
static const struct btf_kind_operations datasec_ops = {
.check_meta = btf_datasec_check_meta,
.resolve = btf_datasec_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_datasec_log,
.show = btf_datasec_show,
};
static s32 btf_float_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&
t->size != 16) {
btf_verifier_log_type(env, t, "Invalid type_size");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return 0;
}
static int btf_float_check_member(struct btf_verifier_env *env,
const struct btf_type *struct_type,
const struct btf_member *member,
const struct btf_type *member_type)
{
u64 start_offset_bytes;
u64 end_offset_bytes;
u64 misalign_bits;
u64 align_bytes;
u64 align_bits;
/* Different architectures have different alignment requirements, so
* here we check only for the reasonable minimum. This way we ensure
* that types after CO-RE can pass the kernel BTF verifier.
*/
align_bytes = min_t(u64, sizeof(void *), member_type->size);
align_bits = align_bytes * BITS_PER_BYTE;
div64_u64_rem(member->offset, align_bits, &misalign_bits);
if (misalign_bits) {
btf_verifier_log_member(env, struct_type, member,
"Member is not properly aligned");
return -EINVAL;
}
start_offset_bytes = member->offset / BITS_PER_BYTE;
end_offset_bytes = start_offset_bytes + member_type->size;
if (end_offset_bytes > struct_type->size) {
btf_verifier_log_member(env, struct_type, member,
"Member exceeds struct_size");
return -EINVAL;
}
return 0;
}
static void btf_float_log(struct btf_verifier_env *env,
const struct btf_type *t)
{
btf_verifier_log(env, "size=%u", t->size);
}
static const struct btf_kind_operations float_ops = {
.check_meta = btf_float_check_meta,
.resolve = btf_df_resolve,
.check_member = btf_float_check_member,
.check_kflag_member = btf_generic_check_kflag_member,
.log_details = btf_float_log,
.show = btf_df_show,
};
static s32 btf_decl_tag_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
const struct btf_decl_tag *tag;
u32 meta_needed = sizeof(*tag);
s32 component_idx;
const char *value;
if (meta_left < meta_needed) {
btf_verifier_log_basic(env, t,
"meta_left:%u meta_needed:%u",
meta_left, meta_needed);
return -EINVAL;
}
value = btf_name_by_offset(env->btf, t->name_off);
if (!value || !value[0]) {
btf_verifier_log_type(env, t, "Invalid value");
return -EINVAL;
}
if (btf_type_vlen(t)) {
btf_verifier_log_type(env, t, "vlen != 0");
return -EINVAL;
}
if (btf_type_kflag(t)) {
btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");
return -EINVAL;
}
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx < -1) {
btf_verifier_log_type(env, t, "Invalid component_idx");
return -EINVAL;
}
btf_verifier_log_type(env, t, NULL);
return meta_needed;
}
static int btf_decl_tag_resolve(struct btf_verifier_env *env,
const struct resolve_vertex *v)
{
const struct btf_type *next_type;
const struct btf_type *t = v->t;
u32 next_type_id = t->type;
struct btf *btf = env->btf;
s32 component_idx;
u32 vlen;
next_type = btf_type_by_id(btf, next_type_id);
if (!next_type || !btf_type_is_decl_tag_target(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid type_id");
return -EINVAL;
}
if (!env_type_is_resolve_sink(env, next_type) &&
!env_type_is_resolved(env, next_type_id))
return env_stack_push(env, next_type, next_type_id);
component_idx = btf_type_decl_tag(t)->component_idx;
if (component_idx != -1) {
if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {
btf_verifier_log_type(env, v->t, "Invalid component_idx");
return -EINVAL;
}
if (btf_type_is_struct(next_type)) {
vlen = btf_type_vlen(next_type);
} else {
/* next_type should be a function */
next_type = btf_type_by_id(btf, next_type->type);
vlen = btf_type_vlen(next_type);
}
if ((u32)component_idx >= vlen) {
btf_verifier_log_type(env, v->t, "Invalid component_idx");
return -EINVAL;
}
}
env_stack_pop_resolved(env, next_type_id, 0);
return 0;
}
static void btf_decl_tag_log(struct btf_verifier_env *env, const struct btf_type *t)
{
btf_verifier_log(env, "type=%u component_idx=%d", t->type,
btf_type_decl_tag(t)->component_idx);
}
static const struct btf_kind_operations decl_tag_ops = {
.check_meta = btf_decl_tag_check_meta,
.resolve = btf_decl_tag_resolve,
.check_member = btf_df_check_member,
.check_kflag_member = btf_df_check_kflag_member,
.log_details = btf_decl_tag_log,
.show = btf_df_show,
};
static int btf_func_proto_check(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_type *ret_type;
const struct btf_param *args;
const struct btf *btf;
u16 nr_args, i;
int err;
btf = env->btf;
args = (const struct btf_param *)(t + 1);
nr_args = btf_type_vlen(t);
/* Check func return type which could be "void" (t->type == 0) */
if (t->type) {
u32 ret_type_id = t->type;
ret_type = btf_type_by_id(btf, ret_type_id);
if (!ret_type) {
btf_verifier_log_type(env, t, "Invalid return type");
return -EINVAL;
}
if (btf_type_needs_resolve(ret_type) &&
!env_type_is_resolved(env, ret_type_id)) {
err = btf_resolve(env, ret_type, ret_type_id);
if (err)
return err;
}
/* Ensure the return type is a type that has a size */
if (!btf_type_id_size(btf, &ret_type_id, NULL)) {
btf_verifier_log_type(env, t, "Invalid return type");
return -EINVAL;
}
}
if (!nr_args)
return 0;
/* Last func arg type_id could be 0 if it is a vararg */
if (!args[nr_args - 1].type) {
if (args[nr_args - 1].name_off) {
btf_verifier_log_type(env, t, "Invalid arg#%u",
nr_args);
return -EINVAL;
}
nr_args--;
}
err = 0;
for (i = 0; i < nr_args; i++) {
const struct btf_type *arg_type;
u32 arg_type_id;
arg_type_id = args[i].type;
arg_type = btf_type_by_id(btf, arg_type_id);
if (!arg_type) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
if (args[i].name_off &&
(!btf_name_offset_valid(btf, args[i].name_off) ||
!btf_name_valid_identifier(btf, args[i].name_off))) {
btf_verifier_log_type(env, t,
"Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
if (btf_type_needs_resolve(arg_type) &&
!env_type_is_resolved(env, arg_type_id)) {
err = btf_resolve(env, arg_type, arg_type_id);
if (err)
break;
}
if (!btf_type_id_size(btf, &arg_type_id, NULL)) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
err = -EINVAL;
break;
}
}
return err;
}
static int btf_func_check(struct btf_verifier_env *env,
const struct btf_type *t)
{
const struct btf_type *proto_type;
const struct btf_param *args;
const struct btf *btf;
u16 nr_args, i;
btf = env->btf;
proto_type = btf_type_by_id(btf, t->type);
if (!proto_type || !btf_type_is_func_proto(proto_type)) {
btf_verifier_log_type(env, t, "Invalid type_id");
return -EINVAL;
}
args = (const struct btf_param *)(proto_type + 1);
nr_args = btf_type_vlen(proto_type);
for (i = 0; i < nr_args; i++) {
if (!args[i].name_off && args[i].type) {
btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
return -EINVAL;
}
}
return 0;
}
static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = {
[BTF_KIND_INT] = &int_ops,
[BTF_KIND_PTR] = &ptr_ops,
[BTF_KIND_ARRAY] = &array_ops,
[BTF_KIND_STRUCT] = &struct_ops,
[BTF_KIND_UNION] = &struct_ops,
[BTF_KIND_ENUM] = &enum_ops,
[BTF_KIND_FWD] = &fwd_ops,
[BTF_KIND_TYPEDEF] = &modifier_ops,
[BTF_KIND_VOLATILE] = &modifier_ops,
[BTF_KIND_CONST] = &modifier_ops,
[BTF_KIND_RESTRICT] = &modifier_ops,
[BTF_KIND_FUNC] = &func_ops,
[BTF_KIND_FUNC_PROTO] = &func_proto_ops,
[BTF_KIND_VAR] = &var_ops,
[BTF_KIND_DATASEC] = &datasec_ops,
[BTF_KIND_FLOAT] = &float_ops,
[BTF_KIND_DECL_TAG] = &decl_tag_ops,
[BTF_KIND_TYPE_TAG] = &modifier_ops,
[BTF_KIND_ENUM64] = &enum64_ops,
};
static s32 btf_check_meta(struct btf_verifier_env *env,
const struct btf_type *t,
u32 meta_left)
{
u32 saved_meta_left = meta_left;
s32 var_meta_size;
if (meta_left < sizeof(*t)) {
btf_verifier_log(env, "[%u] meta_left:%u meta_needed:%zu",
env->log_type_id, meta_left, sizeof(*t));
return -EINVAL;
}
meta_left -= sizeof(*t);
if (t->info & ~BTF_INFO_MASK) {
btf_verifier_log(env, "[%u] Invalid btf_info:%x",
env->log_type_id, t->info);
return -EINVAL;
}
if (BTF_INFO_KIND(t->info) > BTF_KIND_MAX ||
BTF_INFO_KIND(t->info) == BTF_KIND_UNKN) {
btf_verifier_log(env, "[%u] Invalid kind:%u",
env->log_type_id, BTF_INFO_KIND(t->info));
return -EINVAL;
}
if (!btf_name_offset_valid(env->btf, t->name_off)) {
btf_verifier_log(env, "[%u] Invalid name_offset:%u",
env->log_type_id, t->name_off);
return -EINVAL;
}
var_meta_size = btf_type_ops(t)->check_meta(env, t, meta_left);
if (var_meta_size < 0)
return var_meta_size;
meta_left -= var_meta_size;
return saved_meta_left - meta_left;
}
static int btf_check_all_metas(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
struct btf_header *hdr;
void *cur, *end;
hdr = &btf->hdr;
cur = btf->nohdr_data + hdr->type_off;
end = cur + hdr->type_len;
env->log_type_id = btf->base_btf ? btf->start_id : 1;
while (cur < end) {
struct btf_type *t = cur;
s32 meta_size;
meta_size = btf_check_meta(env, t, end - cur);
if (meta_size < 0)
return meta_size;
btf_add_type(env, t);
cur += meta_size;
env->log_type_id++;
}
return 0;
}
static bool btf_resolve_valid(struct btf_verifier_env *env,
const struct btf_type *t,
u32 type_id)
{
struct btf *btf = env->btf;
if (!env_type_is_resolved(env, type_id))
return false;
if (btf_type_is_struct(t) || btf_type_is_datasec(t))
return !btf_resolved_type_id(btf, type_id) &&
!btf_resolved_type_size(btf, type_id);
if (btf_type_is_decl_tag(t) || btf_type_is_func(t))
return btf_resolved_type_id(btf, type_id) &&
!btf_resolved_type_size(btf, type_id);
if (btf_type_is_modifier(t) || btf_type_is_ptr(t) ||
btf_type_is_var(t)) {
t = btf_type_id_resolve(btf, &type_id);
return t &&
!btf_type_is_modifier(t) &&
!btf_type_is_var(t) &&
!btf_type_is_datasec(t);
}
if (btf_type_is_array(t)) {
const struct btf_array *array = btf_type_array(t);
const struct btf_type *elem_type;
u32 elem_type_id = array->type;
u32 elem_size;
elem_type = btf_type_id_size(btf, &elem_type_id, &elem_size);
return elem_type && !btf_type_is_modifier(elem_type) &&
(array->nelems * elem_size ==
btf_resolved_type_size(btf, type_id));
}
return false;
}
static int btf_resolve(struct btf_verifier_env *env,
const struct btf_type *t, u32 type_id)
{
u32 save_log_type_id = env->log_type_id;
const struct resolve_vertex *v;
int err = 0;
env->resolve_mode = RESOLVE_TBD;
env_stack_push(env, t, type_id);
while (!err && (v = env_stack_peak(env))) {
env->log_type_id = v->type_id;
err = btf_type_ops(v->t)->resolve(env, v);
}
env->log_type_id = type_id;
if (err == -E2BIG) {
btf_verifier_log_type(env, t,
"Exceeded max resolving depth:%u",
MAX_RESOLVE_DEPTH);
} else if (err == -EEXIST) {
btf_verifier_log_type(env, t, "Loop detected");
}
/* Final sanity check */
if (!err && !btf_resolve_valid(env, t, type_id)) {
btf_verifier_log_type(env, t, "Invalid resolve state");
err = -EINVAL;
}
env->log_type_id = save_log_type_id;
return err;
}
static int btf_check_all_types(struct btf_verifier_env *env)
{
struct btf *btf = env->btf;
const struct btf_type *t;
u32 type_id, i;
int err;
err = env_resolve_init(env);
if (err)
return err;
env->phase++;
for (i = btf->base_btf ? 0 : 1; i < btf->nr_types; i++) {
type_id = btf->start_id + i;
t = btf_type_by_id(btf, type_id);
env->log_type_id = type_id;
if (btf_type_needs_resolve(t) &&
!env_type_is_resolved(env, type_id)) {
err = btf_resolve(env, t, type_id);
if (err)
return err;
}
if (btf_type_is_func_proto(t)) {
err = btf_func_proto_check(env, t);
if (err)
return err;
}
}
return 0;
}
static int btf_parse_type_sec(struct btf_verifier_env *env)
{
const struct btf_header *hdr = &env->btf->hdr;
int err;
/* Type section must align to 4 bytes */
if (hdr->type_off & (sizeof(u32) - 1)) {
btf_verifier_log(env, "Unaligned type_off");
return -EINVAL;
}
if (!env->btf->base_btf && !hdr->type_len) {
btf_verifier_log(env, "No type found");
return -EINVAL;
}
err = btf_check_all_metas(env);
if (err)
return err;
return btf_check_all_types(env);
}
static int btf_parse_str_sec(struct btf_verifier_env *env)
{
const struct btf_header *hdr;
struct btf *btf = env->btf;
const char *start, *end;
hdr = &btf->hdr;
start = btf->nohdr_data + hdr->str_off;
end = start + hdr->str_len;
if (end != btf->data + btf->data_size) {
btf_verifier_log(env, "String section is not at the end");
return -EINVAL;
}
btf->strings = start;
if (btf->base_btf && !hdr->str_len)
return 0;
if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_NAME_OFFSET || end[-1]) {
btf_verifier_log(env, "Invalid string section");
return -EINVAL;
}
if (!btf->base_btf && start[0]) {
btf_verifier_log(env, "Invalid string section");
return -EINVAL;
}
return 0;
}
static const size_t btf_sec_info_offset[] = {
offsetof(struct btf_header, type_off),
offsetof(struct btf_header, str_off),
};
static int btf_sec_info_cmp(const void *a, const void *b)
{
const struct btf_sec_info *x = a;
const struct btf_sec_info *y = b;
return (int)(x->off - y->off) ? : (int)(x->len - y->len);
}
static int btf_check_sec_info(struct btf_verifier_env *env,
u32 btf_data_size)
{
struct btf_sec_info secs[ARRAY_SIZE(btf_sec_info_offset)];
u32 total, expected_total, i;
const struct btf_header *hdr;
const struct btf *btf;
btf = env->btf;
hdr = &btf->hdr;
/* Populate the secs from hdr */
for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++)
secs[i] = *(struct btf_sec_info *)((void *)hdr +
btf_sec_info_offset[i]);
sort(secs, ARRAY_SIZE(btf_sec_info_offset),
sizeof(struct btf_sec_info), btf_sec_info_cmp, NULL);
/* Check for gaps and overlap among sections */
total = 0;
expected_total = btf_data_size - hdr->hdr_len;
for (i = 0; i < ARRAY_SIZE(btf_sec_info_offset); i++) {
if (expected_total < secs[i].off) {
btf_verifier_log(env, "Invalid section offset");
return -EINVAL;
}
if (total < secs[i].off) {
/* gap */
btf_verifier_log(env, "Unsupported section found");
return -EINVAL;
}
if (total > secs[i].off) {
btf_verifier_log(env, "Section overlap found");
return -EINVAL;
}
if (expected_total - total < secs[i].len) {
btf_verifier_log(env,
"Total section length too long");
return -EINVAL;
}
total += secs[i].len;
}
/* There is data other than hdr and known sections */
if (expected_total != total) {
btf_verifier_log(env, "Unsupported section found");
return -EINVAL;
}
return 0;
}
static int btf_parse_hdr(struct btf_verifier_env *env)
{
u32 hdr_len, hdr_copy, btf_data_size;
const struct btf_header *hdr;
struct btf *btf;
int err;
btf = env->btf;
btf_data_size = btf->data_size;
if (btf_data_size < offsetofend(struct btf_header, hdr_len)) {
btf_verifier_log(env, "hdr_len not found");
return -EINVAL;
}
hdr = btf->data;
hdr_len = hdr->hdr_len;
if (btf_data_size < hdr_len) {
btf_verifier_log(env, "btf_header not found");
return -EINVAL;
}
/* Ensure the unsupported header fields are zero */
if (hdr_len > sizeof(btf->hdr)) {
u8 *expected_zero = btf->data + sizeof(btf->hdr);
u8 *end = btf->data + hdr_len;
for (; expected_zero < end; expected_zero++) {
if (*expected_zero) {
btf_verifier_log(env, "Unsupported btf_header");
return -E2BIG;
}
}
}
hdr_copy = min_t(u32, hdr_len, sizeof(btf->hdr));
memcpy(&btf->hdr, btf->data, hdr_copy);
hdr = &btf->hdr;
btf_verifier_log_hdr(env, btf_data_size);
if (hdr->magic != BTF_MAGIC) {
btf_verifier_log(env, "Invalid magic");
return -EINVAL;
}
if (hdr->version != BTF_VERSION) {
btf_verifier_log(env, "Unsupported version");
return -ENOTSUPP;
}
if (hdr->flags) {
btf_verifier_log(env, "Unsupported flags");
return -ENOTSUPP;
}
if (!btf->base_btf && btf_data_size == hdr->hdr_len) {
btf_verifier_log(env, "No data");
return -EINVAL;
}
err = btf_check_sec_info(env, btf_data_size);
if (err)
return err;
return 0;
}
static int btf_check_type_tags(struct btf_verifier_env *env,
struct btf *btf, int start_id)
{
int i, n, good_id = start_id - 1;
bool in_tags;
n = btf_nr_types(btf);
for (i = start_id; i < n; i++) {
const struct btf_type *t;
int chain_limit = 32;
u32 cur_id = i;
t = btf_type_by_id(btf, i);
if (!t)
return -EINVAL;
if (!btf_type_is_modifier(t))
continue;
cond_resched();
in_tags = btf_type_is_type_tag(t);
while (btf_type_is_modifier(t)) {
if (!chain_limit--) {
btf_verifier_log(env, "Max chain length or cycle detected");
return -ELOOP;
}
if (btf_type_is_type_tag(t)) {
if (!in_tags) {
btf_verifier_log(env, "Type tags don't precede modifiers");
return -EINVAL;
}
} else if (in_tags) {
in_tags = false;
}
if (cur_id <= good_id)
break;
/* Move to next type */
cur_id = t->type;
t = btf_type_by_id(btf, cur_id);
if (!t)
return -EINVAL;
}
good_id = i;
}
return 0;
}
static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size,
u32 log_level, char __user *log_ubuf, u32 log_size)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL;
u8 *data;
int err;
if (btf_data_size > BTF_MAX_SIZE)
return ERR_PTR(-E2BIG);
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
if (log_level || log_ubuf || log_size) {
/* user requested verbose verifier output
* and supplied buffer to store the verification trace
*/
log->level = log_level;
log->ubuf = log_ubuf;
log->len_total = log_size;
/* log attributes have to be sane */
if (!bpf_verifier_log_attr_valid(log)) {
err = -EINVAL;
goto errout;
}
}
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
data = kvmalloc(btf_data_size, GFP_KERNEL | __GFP_NOWARN);
if (!data) {
err = -ENOMEM;
goto errout;
}
btf->data = data;
btf->data_size = btf_data_size;
if (copy_from_bpfptr(data, btf_data, btf_data_size)) {
err = -EFAULT;
goto errout;
}
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_parse_type_sec(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, 1);
if (err)
goto errout;
if (log->level && bpf_verifier_log_full(log)) {
err = -ENOSPC;
goto errout;
}
btf_verifier_env_free(env);
refcount_set(&btf->refcnt, 1);
return btf;
errout:
btf_verifier_env_free(env);
if (btf)
btf_free(btf);
return ERR_PTR(err);
}
extern char __weak __start_BTF[];
extern char __weak __stop_BTF[];
extern struct btf *btf_vmlinux;
#define BPF_MAP_TYPE(_id, _ops)
#define BPF_LINK_TYPE(_id, _name)
static union {
struct bpf_ctx_convert {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
prog_ctx_type _id##_prog; \
kern_ctx_type _id##_kern;
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
} *__t;
/* 't' is written once under lock. Read many times. */
const struct btf_type *t;
} bpf_ctx_convert;
enum {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
__ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
__ctx_convert_unused, /* to avoid empty enum in extreme .config */
};
static u8 bpf_ctx_convert_map[] = {
#define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \
[_id] = __ctx_convert##_id,
#include <linux/bpf_types.h>
#undef BPF_PROG_TYPE
0, /* avoid empty array */
};
#undef BPF_MAP_TYPE
#undef BPF_LINK_TYPE
static const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, enum bpf_prog_type prog_type,
int arg)
{
const struct btf_type *conv_struct;
const struct btf_type *ctx_struct;
const struct btf_member *ctx_type;
const char *tname, *ctx_tname;
conv_struct = bpf_ctx_convert.t;
if (!conv_struct) {
bpf_log(log, "btf_vmlinux is malformed\n");
return NULL;
}
t = btf_type_by_id(btf, t->type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_struct(t)) {
/* Only pointer to struct is supported for now.
* That means that BPF_PROG_TYPE_TRACEPOINT with BTF
* is not supported yet.
* BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
*/
return NULL;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
return NULL;
}
/* prog_type is valid bpf program type. No need for bounds check. */
ctx_type = btf_type_member(conv_struct) + bpf_ctx_convert_map[prog_type] * 2;
/* ctx_struct is a pointer to prog_ctx_type in vmlinux.
* Like 'struct __sk_buff'
*/
ctx_struct = btf_type_by_id(btf_vmlinux, ctx_type->type);
if (!ctx_struct)
/* should not happen */
return NULL;
ctx_tname = btf_name_by_offset(btf_vmlinux, ctx_struct->name_off);
if (!ctx_tname) {
/* should not happen */
bpf_log(log, "Please fix kernel include/linux/bpf_types.h\n");
return NULL;
}
/* only compare that prog's ctx type name is the same as
* kernel expects. No need to compare field by field.
* It's ok for bpf prog to do:
* struct __sk_buff {};
* int socket_filter_bpf_prog(struct __sk_buff *skb)
* { // no fields of skb are ever used }
*/
if (strcmp(ctx_tname, tname))
return NULL;
return ctx_type;
}
static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
struct btf *btf,
const struct btf_type *t,
enum bpf_prog_type prog_type,
int arg)
{
const struct btf_member *prog_ctx_type, *kern_ctx_type;
prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg);
if (!prog_ctx_type)
return -ENOENT;
kern_ctx_type = prog_ctx_type + 1;
return kern_ctx_type->type;
}
BTF_ID_LIST(bpf_ctx_convert_btf_id)
BTF_ID(struct, bpf_ctx_convert)
struct btf *btf_parse_vmlinux(void)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL;
int err;
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
log->level = BPF_LOG_KERNEL;
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
btf->data = __start_BTF;
btf->data_size = __stop_BTF - __start_BTF;
btf->kernel_btf = true;
snprintf(btf->name, sizeof(btf->name), "vmlinux");
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_check_all_metas(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, 1);
if (err)
goto errout;
/* btf_parse_vmlinux() runs under bpf_verifier_lock */
bpf_ctx_convert.t = btf_type_by_id(btf, bpf_ctx_convert_btf_id[0]);
bpf_struct_ops_init(btf, log);
refcount_set(&btf->refcnt, 1);
err = btf_alloc_id(btf);
if (err)
goto errout;
btf_verifier_env_free(env);
return btf;
errout:
btf_verifier_env_free(env);
if (btf) {
kvfree(btf->types);
kfree(btf);
}
return ERR_PTR(err);
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
static struct btf *btf_parse_module(const char *module_name, const void *data, unsigned int data_size)
{
struct btf_verifier_env *env = NULL;
struct bpf_verifier_log *log;
struct btf *btf = NULL, *base_btf;
int err;
base_btf = bpf_get_btf_vmlinux();
if (IS_ERR(base_btf))
return base_btf;
if (!base_btf)
return ERR_PTR(-EINVAL);
env = kzalloc(sizeof(*env), GFP_KERNEL | __GFP_NOWARN);
if (!env)
return ERR_PTR(-ENOMEM);
log = &env->log;
log->level = BPF_LOG_KERNEL;
btf = kzalloc(sizeof(*btf), GFP_KERNEL | __GFP_NOWARN);
if (!btf) {
err = -ENOMEM;
goto errout;
}
env->btf = btf;
btf->base_btf = base_btf;
btf->start_id = base_btf->nr_types;
btf->start_str_off = base_btf->hdr.str_len;
btf->kernel_btf = true;
snprintf(btf->name, sizeof(btf->name), "%s", module_name);
btf->data = kvmalloc(data_size, GFP_KERNEL | __GFP_NOWARN);
if (!btf->data) {
err = -ENOMEM;
goto errout;
}
memcpy(btf->data, data, data_size);
btf->data_size = data_size;
err = btf_parse_hdr(env);
if (err)
goto errout;
btf->nohdr_data = btf->data + btf->hdr.hdr_len;
err = btf_parse_str_sec(env);
if (err)
goto errout;
err = btf_check_all_metas(env);
if (err)
goto errout;
err = btf_check_type_tags(env, btf, btf_nr_types(base_btf));
if (err)
goto errout;
btf_verifier_env_free(env);
refcount_set(&btf->refcnt, 1);
return btf;
errout:
btf_verifier_env_free(env);
if (btf) {
kvfree(btf->data);
kvfree(btf->types);
kfree(btf);
}
return ERR_PTR(err);
}
#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog)
{
struct bpf_prog *tgt_prog = prog->aux->dst_prog;
if (tgt_prog)
return tgt_prog->aux->btf;
else
return prog->aux->attach_btf;
}
static bool is_int_ptr(struct btf *btf, const struct btf_type *t)
{
/* t comes in already as a pointer */
t = btf_type_by_id(btf, t->type);
/* allow const */
if (BTF_INFO_KIND(t->info) == BTF_KIND_CONST)
t = btf_type_by_id(btf, t->type);
return btf_type_is_int(t);
}
bool btf_ctx_access(int off, int size, enum bpf_access_type type,
const struct bpf_prog *prog,
struct bpf_insn_access_aux *info)
{
const struct btf_type *t = prog->aux->attach_func_proto;
struct bpf_prog *tgt_prog = prog->aux->dst_prog;
struct btf *btf = bpf_prog_get_target_btf(prog);
const char *tname = prog->aux->attach_func_name;
struct bpf_verifier_log *log = info->log;
const struct btf_param *args;
const char *tag_value;
u32 nr_args, arg;
int i, ret;
if (off % 8) {
bpf_log(log, "func '%s' offset %d is not multiple of 8\n",
tname, off);
return false;
}
arg = off / 8;
args = (const struct btf_param *)(t + 1);
/* if (t == NULL) Fall back to default BPF prog with
* MAX_BPF_FUNC_REG_ARGS u64 arguments.
*/
nr_args = t ? btf_type_vlen(t) : MAX_BPF_FUNC_REG_ARGS;
if (prog->aux->attach_btf_trace) {
/* skip first 'void *__data' argument in btf_trace_##name typedef */
args++;
nr_args--;
}
if (arg > nr_args) {
bpf_log(log, "func '%s' doesn't have %d-th argument\n",
tname, arg + 1);
return false;
}
if (arg == nr_args) {
switch (prog->expected_attach_type) {
case BPF_LSM_CGROUP:
case BPF_LSM_MAC:
case BPF_TRACE_FEXIT:
/* When LSM programs are attached to void LSM hooks
* they use FEXIT trampolines and when attached to
* int LSM hooks, they use MODIFY_RETURN trampolines.
*
* While the LSM programs are BPF_MODIFY_RETURN-like
* the check:
*
* if (ret_type != 'int')
* return -EINVAL;
*
* is _not_ done here. This is still safe as LSM hooks
* have only void and int return types.
*/
if (!t)
return true;
t = btf_type_by_id(btf, t->type);
break;
case BPF_MODIFY_RETURN:
/* For now the BPF_MODIFY_RETURN can only be attached to
* functions that return an int.
*/
if (!t)
return false;
t = btf_type_skip_modifiers(btf, t->type, NULL);
if (!btf_type_is_small_int(t)) {
bpf_log(log,
"ret type %s not allowed for fmod_ret\n",
btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
break;
default:
bpf_log(log, "func '%s' doesn't have %d-th argument\n",
tname, arg + 1);
return false;
}
} else {
if (!t)
/* Default prog with MAX_BPF_FUNC_REG_ARGS args */
return true;
t = btf_type_by_id(btf, args[arg].type);
}
/* skip modifiers */
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_small_int(t) || btf_is_any_enum(t))
/* accessing a scalar */
return true;
if (!btf_type_is_ptr(t)) {
bpf_log(log,
"func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n",
tname, arg,
__btf_name_by_offset(btf, t->name_off),
btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
/* check for PTR_TO_RDONLY_BUF_OR_NULL or PTR_TO_RDWR_BUF_OR_NULL */
for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
u32 type, flag;
type = base_type(ctx_arg_info->reg_type);
flag = type_flag(ctx_arg_info->reg_type);
if (ctx_arg_info->offset == off && type == PTR_TO_BUF &&
(flag & PTR_MAYBE_NULL)) {
info->reg_type = ctx_arg_info->reg_type;
return true;
}
}
if (t->type == 0)
/* This is a pointer to void.
* It is the same as scalar from the verifier safety pov.
* No further pointer walking is allowed.
*/
return true;
if (is_int_ptr(btf, t))
return true;
/* this is a pointer to another type */
for (i = 0; i < prog->aux->ctx_arg_info_size; i++) {
const struct bpf_ctx_arg_aux *ctx_arg_info = &prog->aux->ctx_arg_info[i];
if (ctx_arg_info->offset == off) {
if (!ctx_arg_info->btf_id) {
bpf_log(log,"invalid btf_id for context argument offset %u\n", off);
return false;
}
info->reg_type = ctx_arg_info->reg_type;
info->btf = btf_vmlinux;
info->btf_id = ctx_arg_info->btf_id;
return true;
}
}
info->reg_type = PTR_TO_BTF_ID;
if (tgt_prog) {
enum bpf_prog_type tgt_type;
if (tgt_prog->type == BPF_PROG_TYPE_EXT)
tgt_type = tgt_prog->aux->saved_dst_prog_type;
else
tgt_type = tgt_prog->type;
ret = btf_translate_to_vmlinux(log, btf, t, tgt_type, arg);
if (ret > 0) {
info->btf = btf_vmlinux;
info->btf_id = ret;
return true;
} else {
return false;
}
}
info->btf = btf;
info->btf_id = t->type;
t = btf_type_by_id(btf, t->type);
if (btf_type_is_type_tag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
if (strcmp(tag_value, "user") == 0)
info->reg_type |= MEM_USER;
if (strcmp(tag_value, "percpu") == 0)
info->reg_type |= MEM_PERCPU;
}
/* skip modifiers */
while (btf_type_is_modifier(t)) {
info->btf_id = t->type;
t = btf_type_by_id(btf, t->type);
}
if (!btf_type_is_struct(t)) {
bpf_log(log,
"func '%s' arg%d type %s is not a struct\n",
tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]);
return false;
}
bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n",
tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)],
__btf_name_by_offset(btf, t->name_off));
return true;
}
enum bpf_struct_walk_result {
/* < 0 error */
WALK_SCALAR = 0,
WALK_PTR,
WALK_STRUCT,
};
static int btf_struct_walk(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, int off, int size,
u32 *next_btf_id, enum bpf_type_flag *flag)
{
u32 i, moff, mtrue_end, msize = 0, total_nelems = 0;
const struct btf_type *mtype, *elem_type = NULL;
const struct btf_member *member;
const char *tname, *mname, *tag_value;
u32 vlen, elem_id, mid;
again:
tname = __btf_name_by_offset(btf, t->name_off);
if (!btf_type_is_struct(t)) {
bpf_log(log, "Type '%s' is not a struct\n", tname);
return -EINVAL;
}
vlen = btf_type_vlen(t);
if (off + size > t->size) {
/* If the last element is a variable size array, we may
* need to relax the rule.
*/
struct btf_array *array_elem;
if (vlen == 0)
goto error;
member = btf_type_member(t) + vlen - 1;
mtype = btf_type_skip_modifiers(btf, member->type,
NULL);
if (!btf_type_is_array(mtype))
goto error;
array_elem = (struct btf_array *)(mtype + 1);
if (array_elem->nelems != 0)
goto error;
moff = __btf_member_bit_offset(t, member) / 8;
if (off < moff)
goto error;
/* Only allow structure for now, can be relaxed for
* other types later.
*/
t = btf_type_skip_modifiers(btf, array_elem->type,
NULL);
if (!btf_type_is_struct(t))
goto error;
off = (off - moff) % t->size;
goto again;
error:
bpf_log(log, "access beyond struct %s at off %u size %u\n",
tname, off, size);
return -EACCES;
}
for_each_member(i, t, member) {
/* offset of the field in bytes */
moff = __btf_member_bit_offset(t, member) / 8;
if (off + size <= moff)
/* won't find anything, field is already too far */
break;
if (__btf_member_bitfield_size(t, member)) {
u32 end_bit = __btf_member_bit_offset(t, member) +
__btf_member_bitfield_size(t, member);
/* off <= moff instead of off == moff because clang
* does not generate a BTF member for anonymous
* bitfield like the ":16" here:
* struct {
* int :16;
* int x:8;
* };
*/
if (off <= moff &&
BITS_ROUNDUP_BYTES(end_bit) <= off + size)
return WALK_SCALAR;
/* off may be accessing a following member
*
* or
*
* Doing partial access at either end of this
* bitfield. Continue on this case also to
* treat it as not accessing this bitfield
* and eventually error out as field not
* found to keep it simple.
* It could be relaxed if there was a legit
* partial access case later.
*/
continue;
}
/* In case of "off" is pointing to holes of a struct */
if (off < moff)
break;
/* type of the field */
mid = member->type;
mtype = btf_type_by_id(btf, member->type);
mname = __btf_name_by_offset(btf, member->name_off);
mtype = __btf_resolve_size(btf, mtype, &msize,
&elem_type, &elem_id, &total_nelems,
&mid);
if (IS_ERR(mtype)) {
bpf_log(log, "field %s doesn't have size\n", mname);
return -EFAULT;
}
mtrue_end = moff + msize;
if (off >= mtrue_end)
/* no overlap with member, keep iterating */
continue;
if (btf_type_is_array(mtype)) {
u32 elem_idx;
/* __btf_resolve_size() above helps to
* linearize a multi-dimensional array.
*
* The logic here is treating an array
* in a struct as the following way:
*
* struct outer {
* struct inner array[2][2];
* };
*
* looks like:
*
* struct outer {
* struct inner array_elem0;
* struct inner array_elem1;
* struct inner array_elem2;
* struct inner array_elem3;
* };
*
* When accessing outer->array[1][0], it moves
* moff to "array_elem2", set mtype to
* "struct inner", and msize also becomes
* sizeof(struct inner). Then most of the
* remaining logic will fall through without
* caring the current member is an array or
* not.
*
* Unlike mtype/msize/moff, mtrue_end does not
* change. The naming difference ("_true") tells
* that it is not always corresponding to
* the current mtype/msize/moff.
* It is the true end of the current
* member (i.e. array in this case). That
* will allow an int array to be accessed like
* a scratch space,
* i.e. allow access beyond the size of
* the array's element as long as it is
* within the mtrue_end boundary.
*/
/* skip empty array */
if (moff == mtrue_end)
continue;
msize /= total_nelems;
elem_idx = (off - moff) / msize;
moff += elem_idx * msize;
mtype = elem_type;
mid = elem_id;
}
/* the 'off' we're looking for is either equal to start
* of this field or inside of this struct
*/
if (btf_type_is_struct(mtype)) {
/* our field must be inside that union or struct */
t = mtype;
/* return if the offset matches the member offset */
if (off == moff) {
*next_btf_id = mid;
return WALK_STRUCT;
}
/* adjust offset we're looking for */
off -= moff;
goto again;
}
if (btf_type_is_ptr(mtype)) {
const struct btf_type *stype, *t;
enum bpf_type_flag tmp_flag = 0;
u32 id;
if (msize != size || off != moff) {
bpf_log(log,
"cannot access ptr member %s with moff %u in struct %s with off %u size %u\n",
mname, moff, tname, off, size);
return -EACCES;
}
/* check type tag */
t = btf_type_by_id(btf, mtype->type);
if (btf_type_is_type_tag(t)) {
tag_value = __btf_name_by_offset(btf, t->name_off);
/* check __user tag */
if (strcmp(tag_value, "user") == 0)
tmp_flag = MEM_USER;
/* check __percpu tag */
if (strcmp(tag_value, "percpu") == 0)
tmp_flag = MEM_PERCPU;
}
stype = btf_type_skip_modifiers(btf, mtype->type, &id);
if (btf_type_is_struct(stype)) {
*next_btf_id = id;
*flag = tmp_flag;
return WALK_PTR;
}
}
/* Allow more flexible access within an int as long as
* it is within mtrue_end.
* Since mtrue_end could be the end of an array,
* that also allows using an array of int as a scratch
* space. e.g. skb->cb[].
*/
if (off + size > mtrue_end) {
bpf_log(log,
"access beyond the end of member %s (mend:%u) in struct %s with off %u size %u\n",
mname, mtrue_end, tname, off, size);
return -EACCES;
}
return WALK_SCALAR;
}
bpf_log(log, "struct %s doesn't have field at offset %d\n", tname, off);
return -EINVAL;
}
int btf_struct_access(struct bpf_verifier_log *log, const struct btf *btf,
const struct btf_type *t, int off, int size,
enum bpf_access_type atype __maybe_unused,
u32 *next_btf_id, enum bpf_type_flag *flag)
{
enum bpf_type_flag tmp_flag = 0;
int err;
u32 id;
do {
err = btf_struct_walk(log, btf, t, off, size, &id, &tmp_flag);
switch (err) {
case WALK_PTR:
/* If we found the pointer or scalar on t+off,
* we're done.
*/
*next_btf_id = id;
*flag = tmp_flag;
return PTR_TO_BTF_ID;
case WALK_SCALAR:
return SCALAR_VALUE;
case WALK_STRUCT:
/* We found nested struct, so continue the search
* by diving in it. At this point the offset is
* aligned with the new type, so set it to 0.
*/
t = btf_type_by_id(btf, id);
off = 0;
break;
default:
/* It's either error or unknown return value..
* scream and leave.
*/
if (WARN_ONCE(err > 0, "unknown btf_struct_walk return value"))
return -EINVAL;
return err;
}
} while (t);
return -EINVAL;
}
/* Check that two BTF types, each specified as an BTF object + id, are exactly
* the same. Trivial ID check is not enough due to module BTFs, because we can
* end up with two different module BTFs, but IDs point to the common type in
* vmlinux BTF.
*/
static bool btf_types_are_same(const struct btf *btf1, u32 id1,
const struct btf *btf2, u32 id2)
{
if (id1 != id2)
return false;
if (btf1 == btf2)
return true;
return btf_type_by_id(btf1, id1) == btf_type_by_id(btf2, id2);
}
bool btf_struct_ids_match(struct bpf_verifier_log *log,
const struct btf *btf, u32 id, int off,
const struct btf *need_btf, u32 need_type_id,
bool strict)
{
const struct btf_type *type;
enum bpf_type_flag flag;
int err;
/* Are we already done? */
if (off == 0 && btf_types_are_same(btf, id, need_btf, need_type_id))
return true;
/* In case of strict type match, we do not walk struct, the top level
* type match must succeed. When strict is true, off should have already
* been 0.
*/
if (strict)
return false;
again:
type = btf_type_by_id(btf, id);
if (!type)
return false;
err = btf_struct_walk(log, btf, type, off, 1, &id, &flag);
if (err != WALK_STRUCT)
return false;
/* We found nested struct object. If it matches
* the requested ID, we're done. Otherwise let's
* continue the search with offset 0 in the new
* type.
*/
if (!btf_types_are_same(btf, id, need_btf, need_type_id)) {
off = 0;
goto again;
}
return true;
}
static int __get_type_size(struct btf *btf, u32 btf_id,
const struct btf_type **bad_type)
{
const struct btf_type *t;
if (!btf_id)
/* void */
return 0;
t = btf_type_by_id(btf, btf_id);
while (t && btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!t) {
*bad_type = btf_type_by_id(btf, 0);
return -EINVAL;
}
if (btf_type_is_ptr(t))
/* kernel size of pointer. Not BPF's size of pointer*/
return sizeof(void *);
if (btf_type_is_int(t) || btf_is_any_enum(t))
return t->size;
*bad_type = t;
return -EINVAL;
}
int btf_distill_func_proto(struct bpf_verifier_log *log,
struct btf *btf,
const struct btf_type *func,
const char *tname,
struct btf_func_model *m)
{
const struct btf_param *args;
const struct btf_type *t;
u32 i, nargs;
int ret;
if (!func) {
/* BTF function prototype doesn't match the verifier types.
* Fall back to MAX_BPF_FUNC_REG_ARGS u64 args.
*/
for (i = 0; i < MAX_BPF_FUNC_REG_ARGS; i++)
m->arg_size[i] = 8;
m->ret_size = 8;
m->nr_args = MAX_BPF_FUNC_REG_ARGS;
return 0;
}
args = (const struct btf_param *)(func + 1);
nargs = btf_type_vlen(func);
if (nargs > MAX_BPF_FUNC_ARGS) {
bpf_log(log,
"The function %s has %d arguments. Too many.\n",
tname, nargs);
return -EINVAL;
}
ret = __get_type_size(btf, func->type, &t);
if (ret < 0) {
bpf_log(log,
"The function %s return type %s is unsupported.\n",
tname, btf_kind_str[BTF_INFO_KIND(t->info)]);
return -EINVAL;
}
m->ret_size = ret;
for (i = 0; i < nargs; i++) {
if (i == nargs - 1 && args[i].type == 0) {
bpf_log(log,
"The function %s with variable args is unsupported.\n",
tname);
return -EINVAL;
}
ret = __get_type_size(btf, args[i].type, &t);
if (ret < 0) {
bpf_log(log,
"The function %s arg%d type %s is unsupported.\n",
tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]);
return -EINVAL;
}
if (ret == 0) {
bpf_log(log,
"The function %s has malformed void argument.\n",
tname);
return -EINVAL;
}
m->arg_size[i] = ret;
}
m->nr_args = nargs;
return 0;
}
/* Compare BTFs of two functions assuming only scalars and pointers to context.
* t1 points to BTF_KIND_FUNC in btf1
* t2 points to BTF_KIND_FUNC in btf2
* Returns:
* EINVAL - function prototype mismatch
* EFAULT - verifier bug
* 0 - 99% match. The last 1% is validated by the verifier.
*/
static int btf_check_func_type_match(struct bpf_verifier_log *log,
struct btf *btf1, const struct btf_type *t1,
struct btf *btf2, const struct btf_type *t2)
{
const struct btf_param *args1, *args2;
const char *fn1, *fn2, *s1, *s2;
u32 nargs1, nargs2, i;
fn1 = btf_name_by_offset(btf1, t1->name_off);
fn2 = btf_name_by_offset(btf2, t2->name_off);
if (btf_func_linkage(t1) != BTF_FUNC_GLOBAL) {
bpf_log(log, "%s() is not a global function\n", fn1);
return -EINVAL;
}
if (btf_func_linkage(t2) != BTF_FUNC_GLOBAL) {
bpf_log(log, "%s() is not a global function\n", fn2);
return -EINVAL;
}
t1 = btf_type_by_id(btf1, t1->type);
if (!t1 || !btf_type_is_func_proto(t1))
return -EFAULT;
t2 = btf_type_by_id(btf2, t2->type);
if (!t2 || !btf_type_is_func_proto(t2))
return -EFAULT;
args1 = (const struct btf_param *)(t1 + 1);
nargs1 = btf_type_vlen(t1);
args2 = (const struct btf_param *)(t2 + 1);
nargs2 = btf_type_vlen(t2);
if (nargs1 != nargs2) {
bpf_log(log, "%s() has %d args while %s() has %d args\n",
fn1, nargs1, fn2, nargs2);
return -EINVAL;
}
t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
if (t1->info != t2->info) {
bpf_log(log,
"Return type %s of %s() doesn't match type %s of %s()\n",
btf_type_str(t1), fn1,
btf_type_str(t2), fn2);
return -EINVAL;
}
for (i = 0; i < nargs1; i++) {
t1 = btf_type_skip_modifiers(btf1, args1[i].type, NULL);
t2 = btf_type_skip_modifiers(btf2, args2[i].type, NULL);
if (t1->info != t2->info) {
bpf_log(log, "arg%d in %s() is %s while %s() has %s\n",
i, fn1, btf_type_str(t1),
fn2, btf_type_str(t2));
return -EINVAL;
}
if (btf_type_has_size(t1) && t1->size != t2->size) {
bpf_log(log,
"arg%d in %s() has size %d while %s() has %d\n",
i, fn1, t1->size,
fn2, t2->size);
return -EINVAL;
}
/* global functions are validated with scalars and pointers
* to context only. And only global functions can be replaced.
* Hence type check only those types.
*/
if (btf_type_is_int(t1) || btf_is_any_enum(t1))
continue;
if (!btf_type_is_ptr(t1)) {
bpf_log(log,
"arg%d in %s() has unrecognized type\n",
i, fn1);
return -EINVAL;
}
t1 = btf_type_skip_modifiers(btf1, t1->type, NULL);
t2 = btf_type_skip_modifiers(btf2, t2->type, NULL);
if (!btf_type_is_struct(t1)) {
bpf_log(log,
"arg%d in %s() is not a pointer to context\n",
i, fn1);
return -EINVAL;
}
if (!btf_type_is_struct(t2)) {
bpf_log(log,
"arg%d in %s() is not a pointer to context\n",
i, fn2);
return -EINVAL;
}
/* This is an optional check to make program writing easier.
* Compare names of structs and report an error to the user.
* btf_prepare_func_args() already checked that t2 struct
* is a context type. btf_prepare_func_args() will check
* later that t1 struct is a context type as well.
*/
s1 = btf_name_by_offset(btf1, t1->name_off);
s2 = btf_name_by_offset(btf2, t2->name_off);
if (strcmp(s1, s2)) {
bpf_log(log,
"arg%d %s(struct %s *) doesn't match %s(struct %s *)\n",
i, fn1, s1, fn2, s2);
return -EINVAL;
}
}
return 0;
}
/* Compare BTFs of given program with BTF of target program */
int btf_check_type_match(struct bpf_verifier_log *log, const struct bpf_prog *prog,
struct btf *btf2, const struct btf_type *t2)
{
struct btf *btf1 = prog->aux->btf;
const struct btf_type *t1;
u32 btf_id = 0;
if (!prog->aux->func_info) {
bpf_log(log, "Program extension requires BTF\n");
return -EINVAL;
}
btf_id = prog->aux->func_info[0].type_id;
if (!btf_id)
return -EFAULT;
t1 = btf_type_by_id(btf1, btf_id);
if (!t1 || !btf_type_is_func(t1))
return -EFAULT;
return btf_check_func_type_match(log, btf1, t1, btf2, t2);
}
static u32 *reg2btf_ids[__BPF_REG_TYPE_MAX] = {
#ifdef CONFIG_NET
[PTR_TO_SOCKET] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK],
[PTR_TO_SOCK_COMMON] = &btf_sock_ids[BTF_SOCK_TYPE_SOCK_COMMON],
[PTR_TO_TCP_SOCK] = &btf_sock_ids[BTF_SOCK_TYPE_TCP],
#endif
};
/* Returns true if struct is composed of scalars, 4 levels of nesting allowed */
static bool __btf_type_is_scalar_struct(struct bpf_verifier_log *log,
const struct btf *btf,
const struct btf_type *t, int rec)
{
const struct btf_type *member_type;
const struct btf_member *member;
u32 i;
if (!btf_type_is_struct(t))
return false;
for_each_member(i, t, member) {
const struct btf_array *array;
member_type = btf_type_skip_modifiers(btf, member->type, NULL);
if (btf_type_is_struct(member_type)) {
if (rec >= 3) {
bpf_log(log, "max struct nesting depth exceeded\n");
return false;
}
if (!__btf_type_is_scalar_struct(log, btf, member_type, rec + 1))
return false;
continue;
}
if (btf_type_is_array(member_type)) {
array = btf_type_array(member_type);
if (!array->nelems)
return false;
member_type = btf_type_skip_modifiers(btf, array->type, NULL);
if (!btf_type_is_scalar(member_type))
return false;
continue;
}
if (!btf_type_is_scalar(member_type))
return false;
}
return true;
}
static bool is_kfunc_arg_mem_size(const struct btf *btf,
const struct btf_param *arg,
const struct bpf_reg_state *reg)
{
int len, sfx_len = sizeof("__sz") - 1;
const struct btf_type *t;
const char *param_name;
t = btf_type_skip_modifiers(btf, arg->type, NULL);
if (!btf_type_is_scalar(t) || reg->type != SCALAR_VALUE)
return false;
/* In the future, this can be ported to use BTF tagging */
param_name = btf_name_by_offset(btf, arg->name_off);
if (str_is_empty(param_name))
return false;
len = strlen(param_name);
if (len < sfx_len)
return false;
param_name += len - sfx_len;
if (strncmp(param_name, "__sz", sfx_len))
return false;
return true;
}
static int btf_check_func_arg_match(struct bpf_verifier_env *env,
const struct btf *btf, u32 func_id,
struct bpf_reg_state *regs,
bool ptr_to_mem_ok,
u32 kfunc_flags)
{
enum bpf_prog_type prog_type = resolve_prog_type(env->prog);
bool rel = false, kptr_get = false, trusted_arg = false;
struct bpf_verifier_log *log = &env->log;
u32 i, nargs, ref_id, ref_obj_id = 0;
bool is_kfunc = btf_is_kernel(btf);
const char *func_name, *ref_tname;
const struct btf_type *t, *ref_t;
const struct btf_param *args;
int ref_regno = 0, ret;
t = btf_type_by_id(btf, func_id);
if (!t || !btf_type_is_func(t)) {
/* These checks were already done by the verifier while loading
* struct bpf_func_info or in add_kfunc_call().
*/
bpf_log(log, "BTF of func_id %u doesn't point to KIND_FUNC\n",
func_id);
return -EFAULT;
}
func_name = btf_name_by_offset(btf, t->name_off);
t = btf_type_by_id(btf, t->type);
if (!t || !btf_type_is_func_proto(t)) {
bpf_log(log, "Invalid BTF of func %s\n", func_name);
return -EFAULT;
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Function %s has %d > %d args\n", func_name, nargs,
MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
if (is_kfunc) {
/* Only kfunc can be release func */
rel = kfunc_flags & KF_RELEASE;
kptr_get = kfunc_flags & KF_KPTR_GET;
trusted_arg = kfunc_flags & KF_TRUSTED_ARGS;
}
/* check that BTF function arguments match actual types that the
* verifier sees.
*/
for (i = 0; i < nargs; i++) {
enum bpf_arg_type arg_type = ARG_DONTCARE;
u32 regno = i + 1;
struct bpf_reg_state *reg = &regs[regno];
t = btf_type_skip_modifiers(btf, args[i].type, NULL);
if (btf_type_is_scalar(t)) {
if (reg->type == SCALAR_VALUE)
continue;
bpf_log(log, "R%d is not a scalar\n", regno);
return -EINVAL;
}
if (!btf_type_is_ptr(t)) {
bpf_log(log, "Unrecognized arg#%d type %s\n",
i, btf_type_str(t));
return -EINVAL;
}
/* Check if argument must be a referenced pointer, args + i has
* been verified to be a pointer (after skipping modifiers).
*/
if (is_kfunc && trusted_arg && !reg->ref_obj_id) {
bpf_log(log, "R%d must be referenced\n", regno);
return -EINVAL;
}
ref_t = btf_type_skip_modifiers(btf, t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
/* Trusted args have the same offset checks as release arguments */
if (trusted_arg || (rel && reg->ref_obj_id))
arg_type |= OBJ_RELEASE;
ret = check_func_arg_reg_off(env, reg, regno, arg_type);
if (ret < 0)
return ret;
/* kptr_get is only true for kfunc */
if (i == 0 && kptr_get) {
struct bpf_map_value_off_desc *off_desc;
if (reg->type != PTR_TO_MAP_VALUE) {
bpf_log(log, "arg#0 expected pointer to map value\n");
return -EINVAL;
}
/* check_func_arg_reg_off allows var_off for
* PTR_TO_MAP_VALUE, but we need fixed offset to find
* off_desc.
*/
if (!tnum_is_const(reg->var_off)) {
bpf_log(log, "arg#0 must have constant offset\n");
return -EINVAL;
}
off_desc = bpf_map_kptr_off_contains(reg->map_ptr, reg->off + reg->var_off.value);
if (!off_desc || off_desc->type != BPF_KPTR_REF) {
bpf_log(log, "arg#0 no referenced kptr at map value offset=%llu\n",
reg->off + reg->var_off.value);
return -EINVAL;
}
if (!btf_type_is_ptr(ref_t)) {
bpf_log(log, "arg#0 BTF type must be a double pointer\n");
return -EINVAL;
}
ref_t = btf_type_skip_modifiers(btf, ref_t->type, &ref_id);
ref_tname = btf_name_by_offset(btf, ref_t->name_off);
if (!btf_type_is_struct(ref_t)) {
bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n",
func_name, i, btf_type_str(ref_t), ref_tname);
return -EINVAL;
}
if (!btf_struct_ids_match(log, btf, ref_id, 0, off_desc->kptr.btf,
off_desc->kptr.btf_id, true)) {
bpf_log(log, "kernel function %s args#%d expected pointer to %s %s\n",
func_name, i, btf_type_str(ref_t), ref_tname);
return -EINVAL;
}
/* rest of the arguments can be anything, like normal kfunc */
} else if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
/* If function expects ctx type in BTF check that caller
* is passing PTR_TO_CTX.
*/
if (reg->type != PTR_TO_CTX) {
bpf_log(log,
"arg#%d expected pointer to ctx, but got %s\n",
i, btf_type_str(t));
return -EINVAL;
}
} else if (is_kfunc && (reg->type == PTR_TO_BTF_ID ||
(reg2btf_ids[base_type(reg->type)] && !type_flag(reg->type)))) {
const struct btf_type *reg_ref_t;
const struct btf *reg_btf;
const char *reg_ref_tname;
u32 reg_ref_id;
if (!btf_type_is_struct(ref_t)) {
bpf_log(log, "kernel function %s args#%d pointer type %s %s is not supported\n",
func_name, i, btf_type_str(ref_t),
ref_tname);
return -EINVAL;
}
if (reg->type == PTR_TO_BTF_ID) {
reg_btf = reg->btf;
reg_ref_id = reg->btf_id;
/* Ensure only one argument is referenced PTR_TO_BTF_ID */
if (reg->ref_obj_id) {
if (ref_obj_id) {
bpf_log(log, "verifier internal error: more than one arg with ref_obj_id R%d %u %u\n",
regno, reg->ref_obj_id, ref_obj_id);
return -EFAULT;
}
ref_regno = regno;
ref_obj_id = reg->ref_obj_id;
}
} else {
reg_btf = btf_vmlinux;
reg_ref_id = *reg2btf_ids[base_type(reg->type)];
}
reg_ref_t = btf_type_skip_modifiers(reg_btf, reg_ref_id,
&reg_ref_id);
reg_ref_tname = btf_name_by_offset(reg_btf,
reg_ref_t->name_off);
if (!btf_struct_ids_match(log, reg_btf, reg_ref_id,
reg->off, btf, ref_id,
trusted_arg || (rel && reg->ref_obj_id))) {
bpf_log(log, "kernel function %s args#%d expected pointer to %s %s but R%d has a pointer to %s %s\n",
func_name, i,
btf_type_str(ref_t), ref_tname,
regno, btf_type_str(reg_ref_t),
reg_ref_tname);
return -EINVAL;
}
} else if (ptr_to_mem_ok) {
const struct btf_type *resolve_ret;
u32 type_size;
if (is_kfunc) {
bool arg_mem_size = i + 1 < nargs && is_kfunc_arg_mem_size(btf, &args[i + 1], &regs[regno + 1]);
/* Permit pointer to mem, but only when argument
* type is pointer to scalar, or struct composed
* (recursively) of scalars.
* When arg_mem_size is true, the pointer can be
* void *.
*/
if (!btf_type_is_scalar(ref_t) &&
!__btf_type_is_scalar_struct(log, btf, ref_t, 0) &&
(arg_mem_size ? !btf_type_is_void(ref_t) : 1)) {
bpf_log(log,
"arg#%d pointer type %s %s must point to %sscalar, or struct with scalar\n",
i, btf_type_str(ref_t), ref_tname, arg_mem_size ? "void, " : "");
return -EINVAL;
}
/* Check for mem, len pair */
if (arg_mem_size) {
if (check_kfunc_mem_size_reg(env, &regs[regno + 1], regno + 1)) {
bpf_log(log, "arg#%d arg#%d memory, len pair leads to invalid memory access\n",
i, i + 1);
return -EINVAL;
}
i++;
continue;
}
}
resolve_ret = btf_resolve_size(btf, ref_t, &type_size);
if (IS_ERR(resolve_ret)) {
bpf_log(log,
"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(ref_t), ref_tname,
PTR_ERR(resolve_ret));
return -EINVAL;
}
if (check_mem_reg(env, reg, regno, type_size))
return -EINVAL;
} else {
bpf_log(log, "reg type unsupported for arg#%d %sfunction %s#%d\n", i,
is_kfunc ? "kernel " : "", func_name, func_id);
return -EINVAL;
}
}
/* Either both are set, or neither */
WARN_ON_ONCE((ref_obj_id && !ref_regno) || (!ref_obj_id && ref_regno));
/* We already made sure ref_obj_id is set only for one argument. We do
* allow (!rel && ref_obj_id), so that passing such referenced
* PTR_TO_BTF_ID to other kfuncs works. Note that rel is only true when
* is_kfunc is true.
*/
if (rel && !ref_obj_id) {
bpf_log(log, "release kernel function %s expects refcounted PTR_TO_BTF_ID\n",
func_name);
return -EINVAL;
}
/* returns argument register number > 0 in case of reference release kfunc */
return rel ? ref_regno : 0;
}
/* Compare BTF of a function with given bpf_reg_state.
* Returns:
* EFAULT - there is a verifier bug. Abort verification.
* EINVAL - there is a type mismatch or BTF is not available.
* 0 - BTF matches with what bpf_reg_state expects.
* Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
*/
int btf_check_subprog_arg_match(struct bpf_verifier_env *env, int subprog,
struct bpf_reg_state *regs)
{
struct bpf_prog *prog = env->prog;
struct btf *btf = prog->aux->btf;
bool is_global;
u32 btf_id;
int err;
if (!prog->aux->func_info)
return -EINVAL;
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id)
return -EFAULT;
if (prog->aux->func_info_aux[subprog].unreliable)
return -EINVAL;
is_global = prog->aux->func_info_aux[subprog].linkage == BTF_FUNC_GLOBAL;
err = btf_check_func_arg_match(env, btf, btf_id, regs, is_global, 0);
/* Compiler optimizations can remove arguments from static functions
* or mismatched type can be passed into a global function.
* In such cases mark the function as unreliable from BTF point of view.
*/
if (err)
prog->aux->func_info_aux[subprog].unreliable = true;
return err;
}
int btf_check_kfunc_arg_match(struct bpf_verifier_env *env,
const struct btf *btf, u32 func_id,
struct bpf_reg_state *regs,
u32 kfunc_flags)
{
return btf_check_func_arg_match(env, btf, func_id, regs, true, kfunc_flags);
}
/* Convert BTF of a function into bpf_reg_state if possible
* Returns:
* EFAULT - there is a verifier bug. Abort verification.
* EINVAL - cannot convert BTF.
* 0 - Successfully converted BTF into bpf_reg_state
* (either PTR_TO_CTX or SCALAR_VALUE).
*/
int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
struct bpf_reg_state *regs)
{
struct bpf_verifier_log *log = &env->log;
struct bpf_prog *prog = env->prog;
enum bpf_prog_type prog_type = prog->type;
struct btf *btf = prog->aux->btf;
const struct btf_param *args;
const struct btf_type *t, *ref_t;
u32 i, nargs, btf_id;
const char *tname;
if (!prog->aux->func_info ||
prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) {
bpf_log(log, "Verifier bug\n");
return -EFAULT;
}
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id) {
bpf_log(log, "Global functions need valid BTF\n");
return -EFAULT;
}
t = btf_type_by_id(btf, btf_id);
if (!t || !btf_type_is_func(t)) {
/* These checks were already done by the verifier while loading
* struct bpf_func_info
*/
bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
subprog);
return -EFAULT;
}
tname = btf_name_by_offset(btf, t->name_off);
if (log->level & BPF_LOG_LEVEL)
bpf_log(log, "Validating %s() func#%d...\n",
tname, subprog);
if (prog->aux->func_info_aux[subprog].unreliable) {
bpf_log(log, "Verifier bug in function %s()\n", tname);
return -EFAULT;
}
if (prog_type == BPF_PROG_TYPE_EXT)
prog_type = prog->aux->dst_prog->type;
t = btf_type_by_id(btf, t->type);
if (!t || !btf_type_is_func_proto(t)) {
bpf_log(log, "Invalid type of function %s()\n", tname);
return -EFAULT;
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
if (nargs > MAX_BPF_FUNC_REG_ARGS) {
bpf_log(log, "Global function %s() with %d > %d args. Buggy compiler.\n",
tname, nargs, MAX_BPF_FUNC_REG_ARGS);
return -EINVAL;
}
/* check that function returns int */
t = btf_type_by_id(btf, t->type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (!btf_type_is_int(t) && !btf_is_any_enum(t)) {
bpf_log(log,
"Global function %s() doesn't return scalar. Only those are supported.\n",
tname);
return -EINVAL;
}
/* Convert BTF function arguments into verifier types.
* Only PTR_TO_CTX and SCALAR are supported atm.
*/
for (i = 0; i < nargs; i++) {
struct bpf_reg_state *reg = &regs[i + 1];
t = btf_type_by_id(btf, args[i].type);
while (btf_type_is_modifier(t))
t = btf_type_by_id(btf, t->type);
if (btf_type_is_int(t) || btf_is_any_enum(t)) {
reg->type = SCALAR_VALUE;
continue;
}
if (btf_type_is_ptr(t)) {
if (btf_get_prog_ctx_type(log, btf, t, prog_type, i)) {
reg->type = PTR_TO_CTX;
continue;
}
t = btf_type_skip_modifiers(btf, t->type, NULL);
ref_t = btf_resolve_size(btf, t, &reg->mem_size);
if (IS_ERR(ref_t)) {
bpf_log(log,
"arg#%d reference type('%s %s') size cannot be determined: %ld\n",
i, btf_type_str(t), btf_name_by_offset(btf, t->name_off),
PTR_ERR(ref_t));
return -EINVAL;
}
reg->type = PTR_TO_MEM | PTR_MAYBE_NULL;
reg->id = ++env->id_gen;
continue;
}
bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
i, btf_kind_str[BTF_INFO_KIND(t->info)], tname);
return -EINVAL;
}
return 0;
}
static void btf_type_show(const struct btf *btf, u32 type_id, void *obj,
struct btf_show *show)
{
const struct btf_type *t = btf_type_by_id(btf, type_id);
show->btf = btf;
memset(&show->state, 0, sizeof(show->state));
memset(&show->obj, 0, sizeof(show->obj));
btf_type_ops(t)->show(btf, t, type_id, obj, 0, show);
}
static void btf_seq_show(struct btf_show *show, const char *fmt,
va_list args)
{
seq_vprintf((struct seq_file *)show->target, fmt, args);
}
int btf_type_seq_show_flags(const struct btf *btf, u32 type_id,
void *obj, struct seq_file *m, u64 flags)
{
struct btf_show sseq;
sseq.target = m;
sseq.showfn = btf_seq_show;
sseq.flags = flags;
btf_type_show(btf, type_id, obj, &sseq);
return sseq.state.status;
}
void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
struct seq_file *m)
{
(void) btf_type_seq_show_flags(btf, type_id, obj, m,
BTF_SHOW_NONAME | BTF_SHOW_COMPACT |
BTF_SHOW_ZERO | BTF_SHOW_UNSAFE);
}
struct btf_show_snprintf {
struct btf_show show;
int len_left; /* space left in string */
int len; /* length we would have written */
};
static void btf_snprintf_show(struct btf_show *show, const char *fmt,
va_list args)
{
struct btf_show_snprintf *ssnprintf = (struct btf_show_snprintf *)show;
int len;
len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
if (len < 0) {
ssnprintf->len_left = 0;
ssnprintf->len = len;
} else if (len >= ssnprintf->len_left) {
/* no space, drive on to get length we would have written */
ssnprintf->len_left = 0;
ssnprintf->len += len;
} else {
ssnprintf->len_left -= len;
ssnprintf->len += len;
show->target += len;
}
}
int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
char *buf, int len, u64 flags)
{
struct btf_show_snprintf ssnprintf;
ssnprintf.show.target = buf;
ssnprintf.show.flags = flags;
ssnprintf.show.showfn = btf_snprintf_show;
ssnprintf.len_left = len;
ssnprintf.len = 0;
btf_type_show(btf, type_id, obj, (struct btf_show *)&ssnprintf);
/* If we encountered an error, return it. */
if (ssnprintf.show.state.status)
return ssnprintf.show.state.status;
/* Otherwise return length we would have written */
return ssnprintf.len;
}
#ifdef CONFIG_PROC_FS
static void bpf_btf_show_fdinfo(struct seq_file *m, struct file *filp)
{
const struct btf *btf = filp->private_data;
seq_printf(m, "btf_id:\t%u\n", btf->id);
}
#endif
static int btf_release(struct inode *inode, struct file *filp)
{
btf_put(filp->private_data);
return 0;
}
const struct file_operations btf_fops = {
#ifdef CONFIG_PROC_FS
.show_fdinfo = bpf_btf_show_fdinfo,
#endif
.release = btf_release,
};
static int __btf_new_fd(struct btf *btf)
{
return anon_inode_getfd("btf", &btf_fops, btf, O_RDONLY | O_CLOEXEC);
}
int btf_new_fd(const union bpf_attr *attr, bpfptr_t uattr)
{
struct btf *btf;
int ret;
btf = btf_parse(make_bpfptr(attr->btf, uattr.is_kernel),
attr->btf_size, attr->btf_log_level,
u64_to_user_ptr(attr->btf_log_buf),
attr->btf_log_size);
if (IS_ERR(btf))
return PTR_ERR(btf);
ret = btf_alloc_id(btf);
if (ret) {
btf_free(btf);
return ret;
}
/*
* The BTF ID is published to the userspace.
* All BTF free must go through call_rcu() from
* now on (i.e. free by calling btf_put()).
*/
ret = __btf_new_fd(btf);
if (ret < 0)
btf_put(btf);
return ret;
}
struct btf *btf_get_by_fd(int fd)
{
struct btf *btf;
struct fd f;
f = fdget(fd);
if (!f.file)
return ERR_PTR(-EBADF);
if (f.file->f_op != &btf_fops) {
fdput(f);
return ERR_PTR(-EINVAL);
}
btf = f.file->private_data;
refcount_inc(&btf->refcnt);
fdput(f);
return btf;
}
int btf_get_info_by_fd(const struct btf *btf,
const union bpf_attr *attr,
union bpf_attr __user *uattr)
{
struct bpf_btf_info __user *uinfo;
struct bpf_btf_info info;
u32 info_copy, btf_copy;
void __user *ubtf;
char __user *uname;
u32 uinfo_len, uname_len, name_len;
int ret = 0;
uinfo = u64_to_user_ptr(attr->info.info);
uinfo_len = attr->info.info_len;
info_copy = min_t(u32, uinfo_len, sizeof(info));
memset(&info, 0, sizeof(info));
if (copy_from_user(&info, uinfo, info_copy))
return -EFAULT;
info.id = btf->id;
ubtf = u64_to_user_ptr(info.btf);
btf_copy = min_t(u32, btf->data_size, info.btf_size);
if (copy_to_user(ubtf, btf->data, btf_copy))
return -EFAULT;
info.btf_size = btf->data_size;
info.kernel_btf = btf->kernel_btf;
uname = u64_to_user_ptr(info.name);
uname_len = info.name_len;
if (!uname ^ !uname_len)
return -EINVAL;
name_len = strlen(btf->name);
info.name_len = name_len;
if (uname) {
if (uname_len >= name_len + 1) {
if (copy_to_user(uname, btf->name, name_len + 1))
return -EFAULT;
} else {
char zero = '\0';
if (copy_to_user(uname, btf->name, uname_len - 1))
return -EFAULT;
if (put_user(zero, uname + uname_len - 1))
return -EFAULT;
/* let user-space know about too short buffer */
ret = -ENOSPC;
}
}
if (copy_to_user(uinfo, &info, info_copy) ||
put_user(info_copy, &uattr->info.info_len))
return -EFAULT;
return ret;
}
int btf_get_fd_by_id(u32 id)
{
struct btf *btf;
int fd;
rcu_read_lock();
btf = idr_find(&btf_idr, id);
if (!btf || !refcount_inc_not_zero(&btf->refcnt))
btf = ERR_PTR(-ENOENT);
rcu_read_unlock();
if (IS_ERR(btf))
return PTR_ERR(btf);
fd = __btf_new_fd(btf);
if (fd < 0)
btf_put(btf);
return fd;
}
u32 btf_obj_id(const struct btf *btf)
{
return btf->id;
}
bool btf_is_kernel(const struct btf *btf)
{
return btf->kernel_btf;
}
bool btf_is_module(const struct btf *btf)
{
return btf->kernel_btf && strcmp(btf->name, "vmlinux") != 0;
}
static int btf_id_cmp_func(const void *a, const void *b)
{
const int *pa = a, *pb = b;
return *pa - *pb;
}
bool btf_id_set_contains(const struct btf_id_set *set, u32 id)
{
return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;
}
static void *btf_id_set8_contains(const struct btf_id_set8 *set, u32 id)
{
return bsearch(&id, set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func);
}
enum {
BTF_MODULE_F_LIVE = (1 << 0),
};
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module {
struct list_head list;
struct module *module;
struct btf *btf;
struct bin_attribute *sysfs_attr;
int flags;
};
static LIST_HEAD(btf_modules);
static DEFINE_MUTEX(btf_module_mutex);
static ssize_t
btf_module_read(struct file *file, struct kobject *kobj,
struct bin_attribute *bin_attr,
char *buf, loff_t off, size_t len)
{
const struct btf *btf = bin_attr->private;
memcpy(buf, btf->data + off, len);
return len;
}
static void purge_cand_cache(struct btf *btf);
static int btf_module_notify(struct notifier_block *nb, unsigned long op,
void *module)
{
struct btf_module *btf_mod, *tmp;
struct module *mod = module;
struct btf *btf;
int err = 0;
if (mod->btf_data_size == 0 ||
(op != MODULE_STATE_COMING && op != MODULE_STATE_LIVE &&
op != MODULE_STATE_GOING))
goto out;
switch (op) {
case MODULE_STATE_COMING:
btf_mod = kzalloc(sizeof(*btf_mod), GFP_KERNEL);
if (!btf_mod) {
err = -ENOMEM;
goto out;
}
btf = btf_parse_module(mod->name, mod->btf_data, mod->btf_data_size);
if (IS_ERR(btf)) {
pr_warn("failed to validate module [%s] BTF: %ld\n",
mod->name, PTR_ERR(btf));
kfree(btf_mod);
if (!IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH))
err = PTR_ERR(btf);
goto out;
}
err = btf_alloc_id(btf);
if (err) {
btf_free(btf);
kfree(btf_mod);
goto out;
}
purge_cand_cache(NULL);
mutex_lock(&btf_module_mutex);
btf_mod->module = module;
btf_mod->btf = btf;
list_add(&btf_mod->list, &btf_modules);
mutex_unlock(&btf_module_mutex);
if (IS_ENABLED(CONFIG_SYSFS)) {
struct bin_attribute *attr;
attr = kzalloc(sizeof(*attr), GFP_KERNEL);
if (!attr)
goto out;
sysfs_bin_attr_init(attr);
attr->attr.name = btf->name;
attr->attr.mode = 0444;
attr->size = btf->data_size;
attr->private = btf;
attr->read = btf_module_read;
err = sysfs_create_bin_file(btf_kobj, attr);
if (err) {
pr_warn("failed to register module [%s] BTF in sysfs: %d\n",
mod->name, err);
kfree(attr);
err = 0;
goto out;
}
btf_mod->sysfs_attr = attr;
}
break;
case MODULE_STATE_LIVE:
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
btf_mod->flags |= BTF_MODULE_F_LIVE;
break;
}
mutex_unlock(&btf_module_mutex);
break;
case MODULE_STATE_GOING:
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
list_del(&btf_mod->list);
if (btf_mod->sysfs_attr)
sysfs_remove_bin_file(btf_kobj, btf_mod->sysfs_attr);
purge_cand_cache(btf_mod->btf);
btf_put(btf_mod->btf);
kfree(btf_mod->sysfs_attr);
kfree(btf_mod);
break;
}
mutex_unlock(&btf_module_mutex);
break;
}
out:
return notifier_from_errno(err);
}
static struct notifier_block btf_module_nb = {
.notifier_call = btf_module_notify,
};
static int __init btf_module_init(void)
{
register_module_notifier(&btf_module_nb);
return 0;
}
fs_initcall(btf_module_init);
#endif /* CONFIG_DEBUG_INFO_BTF_MODULES */
struct module *btf_try_get_module(const struct btf *btf)
{
struct module *res = NULL;
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->btf != btf)
continue;
/* We must only consider module whose __init routine has
* finished, hence we must check for BTF_MODULE_F_LIVE flag,
* which is set from the notifier callback for
* MODULE_STATE_LIVE.
*/
if ((btf_mod->flags & BTF_MODULE_F_LIVE) && try_module_get(btf_mod->module))
res = btf_mod->module;
break;
}
mutex_unlock(&btf_module_mutex);
#endif
return res;
}
/* Returns struct btf corresponding to the struct module.
* This function can return NULL or ERR_PTR.
*/
static struct btf *btf_get_module_btf(const struct module *module)
{
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
struct btf_module *btf_mod, *tmp;
#endif
struct btf *btf = NULL;
if (!module) {
btf = bpf_get_btf_vmlinux();
if (!IS_ERR_OR_NULL(btf))
btf_get(btf);
return btf;
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
mutex_lock(&btf_module_mutex);
list_for_each_entry_safe(btf_mod, tmp, &btf_modules, list) {
if (btf_mod->module != module)
continue;
btf_get(btf_mod->btf);
btf = btf_mod->btf;
break;
}
mutex_unlock(&btf_module_mutex);
#endif
return btf;
}
BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
{
struct btf *btf = NULL;
int btf_obj_fd = 0;
long ret;
if (flags)
return -EINVAL;
if (name_sz <= 1 || name[name_sz - 1])
return -EINVAL;
ret = bpf_find_btf_id(name, kind, &btf);
if (ret > 0 && btf_is_module(btf)) {
btf_obj_fd = __btf_new_fd(btf);
if (btf_obj_fd < 0) {
btf_put(btf);
return btf_obj_fd;
}
return ret | (((u64)btf_obj_fd) << 32);
}
if (ret > 0)
btf_put(btf);
return ret;
}
const struct bpf_func_proto bpf_btf_find_by_name_kind_proto = {
.func = bpf_btf_find_by_name_kind,
.gpl_only = false,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_MEM | MEM_RDONLY,
.arg2_type = ARG_CONST_SIZE,
.arg3_type = ARG_ANYTHING,
.arg4_type = ARG_ANYTHING,
};
BTF_ID_LIST_GLOBAL(btf_tracing_ids, MAX_BTF_TRACING_TYPE)
#define BTF_TRACING_TYPE(name, type) BTF_ID(struct, type)
BTF_TRACING_TYPE_xxx
#undef BTF_TRACING_TYPE
/* Kernel Function (kfunc) BTF ID set registration API */
static int btf_populate_kfunc_set(struct btf *btf, enum btf_kfunc_hook hook,
struct btf_id_set8 *add_set)
{
bool vmlinux_set = !btf_is_module(btf);
struct btf_kfunc_set_tab *tab;
struct btf_id_set8 *set;
u32 set_cnt;
int ret;
if (hook >= BTF_KFUNC_HOOK_MAX) {
ret = -EINVAL;
goto end;
}
if (!add_set->cnt)
return 0;
tab = btf->kfunc_set_tab;
if (!tab) {
tab = kzalloc(sizeof(*tab), GFP_KERNEL | __GFP_NOWARN);
if (!tab)
return -ENOMEM;
btf->kfunc_set_tab = tab;
}
set = tab->sets[hook];
/* Warn when register_btf_kfunc_id_set is called twice for the same hook
* for module sets.
*/
if (WARN_ON_ONCE(set && !vmlinux_set)) {
ret = -EINVAL;
goto end;
}
/* We don't need to allocate, concatenate, and sort module sets, because
* only one is allowed per hook. Hence, we can directly assign the
* pointer and return.
*/
if (!vmlinux_set) {
tab->sets[hook] = add_set;
return 0;
}
/* In case of vmlinux sets, there may be more than one set being
* registered per hook. To create a unified set, we allocate a new set
* and concatenate all individual sets being registered. While each set
* is individually sorted, they may become unsorted when concatenated,
* hence re-sorting the final set again is required to make binary
* searching the set using btf_id_set8_contains function work.
*/
set_cnt = set ? set->cnt : 0;
if (set_cnt > U32_MAX - add_set->cnt) {
ret = -EOVERFLOW;
goto end;
}
if (set_cnt + add_set->cnt > BTF_KFUNC_SET_MAX_CNT) {
ret = -E2BIG;
goto end;
}
/* Grow set */
set = krealloc(tab->sets[hook],
offsetof(struct btf_id_set8, pairs[set_cnt + add_set->cnt]),
GFP_KERNEL | __GFP_NOWARN);
if (!set) {
ret = -ENOMEM;
goto end;
}
/* For newly allocated set, initialize set->cnt to 0 */
if (!tab->sets[hook])
set->cnt = 0;
tab->sets[hook] = set;
/* Concatenate the two sets */
memcpy(set->pairs + set->cnt, add_set->pairs, add_set->cnt * sizeof(set->pairs[0]));
set->cnt += add_set->cnt;
sort(set->pairs, set->cnt, sizeof(set->pairs[0]), btf_id_cmp_func, NULL);
return 0;
end:
btf_free_kfunc_set_tab(btf);
return ret;
}
static u32 *__btf_kfunc_id_set_contains(const struct btf *btf,
enum btf_kfunc_hook hook,
u32 kfunc_btf_id)
{
struct btf_id_set8 *set;
u32 *id;
if (hook >= BTF_KFUNC_HOOK_MAX)
return NULL;
if (!btf->kfunc_set_tab)
return NULL;
set = btf->kfunc_set_tab->sets[hook];
if (!set)
return NULL;
id = btf_id_set8_contains(set, kfunc_btf_id);
if (!id)
return NULL;
/* The flags for BTF ID are located next to it */
return id + 1;
}
static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
{
switch (prog_type) {
case BPF_PROG_TYPE_XDP:
return BTF_KFUNC_HOOK_XDP;
case BPF_PROG_TYPE_SCHED_CLS:
return BTF_KFUNC_HOOK_TC;
case BPF_PROG_TYPE_STRUCT_OPS:
return BTF_KFUNC_HOOK_STRUCT_OPS;
case BPF_PROG_TYPE_TRACING:
return BTF_KFUNC_HOOK_TRACING;
case BPF_PROG_TYPE_SYSCALL:
return BTF_KFUNC_HOOK_SYSCALL;
default:
return BTF_KFUNC_HOOK_MAX;
}
}
/* Caution:
* Reference to the module (obtained using btf_try_get_module) corresponding to
* the struct btf *MUST* be held when calling this function from verifier
* context. This is usually true as we stash references in prog's kfunc_btf_tab;
* keeping the reference for the duration of the call provides the necessary
* protection for looking up a well-formed btf->kfunc_set_tab.
*/
u32 *btf_kfunc_id_set_contains(const struct btf *btf,
enum bpf_prog_type prog_type,
u32 kfunc_btf_id)
{
enum btf_kfunc_hook hook;
hook = bpf_prog_type_to_kfunc_hook(prog_type);
return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id);
}
/* This function must be invoked only from initcalls/module init functions */
int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
const struct btf_kfunc_id_set *kset)
{
enum btf_kfunc_hook hook;
struct btf *btf;
int ret;
btf = btf_get_module_btf(kset->owner);
if (!btf) {
if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
pr_err("missing vmlinux BTF, cannot register kfuncs\n");
return -ENOENT;
}
if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
pr_err("missing module BTF, cannot register kfuncs\n");
return -ENOENT;
}
return 0;
}
if (IS_ERR(btf))
return PTR_ERR(btf);
hook = bpf_prog_type_to_kfunc_hook(prog_type);
ret = btf_populate_kfunc_set(btf, hook, kset->set);
btf_put(btf);
return ret;
}
EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
{
struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;
struct btf_id_dtor_kfunc *dtor;
if (!tab)
return -ENOENT;
/* Even though the size of tab->dtors[0] is > sizeof(u32), we only need
* to compare the first u32 with btf_id, so we can reuse btf_id_cmp_func.
*/
BUILD_BUG_ON(offsetof(struct btf_id_dtor_kfunc, btf_id) != 0);
dtor = bsearch(&btf_id, tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func);
if (!dtor)
return -ENOENT;
return dtor->kfunc_btf_id;
}
static int btf_check_dtor_kfuncs(struct btf *btf, const struct btf_id_dtor_kfunc *dtors, u32 cnt)
{
const struct btf_type *dtor_func, *dtor_func_proto, *t;
const struct btf_param *args;
s32 dtor_btf_id;
u32 nr_args, i;
for (i = 0; i < cnt; i++) {
dtor_btf_id = dtors[i].kfunc_btf_id;
dtor_func = btf_type_by_id(btf, dtor_btf_id);
if (!dtor_func || !btf_type_is_func(dtor_func))
return -EINVAL;
dtor_func_proto = btf_type_by_id(btf, dtor_func->type);
if (!dtor_func_proto || !btf_type_is_func_proto(dtor_func_proto))
return -EINVAL;
/* Make sure the prototype of the destructor kfunc is 'void func(type *)' */
t = btf_type_by_id(btf, dtor_func_proto->type);
if (!t || !btf_type_is_void(t))
return -EINVAL;
nr_args = btf_type_vlen(dtor_func_proto);
if (nr_args != 1)
return -EINVAL;
args = btf_params(dtor_func_proto);
t = btf_type_by_id(btf, args[0].type);
/* Allow any pointer type, as width on targets Linux supports
* will be same for all pointer types (i.e. sizeof(void *))
*/
if (!t || !btf_type_is_ptr(t))
return -EINVAL;
}
return 0;
}
/* This function must be invoked only from initcalls/module init functions */
int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
struct module *owner)
{
struct btf_id_dtor_kfunc_tab *tab;
struct btf *btf;
u32 tab_cnt;
int ret;
btf = btf_get_module_btf(owner);
if (!btf) {
if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
return -ENOENT;
}
if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
pr_err("missing module BTF, cannot register dtor kfuncs\n");
return -ENOENT;
}
return 0;
}
if (IS_ERR(btf))
return PTR_ERR(btf);
if (add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
ret = -E2BIG;
goto end;
}
/* Ensure that the prototype of dtor kfuncs being registered is sane */
ret = btf_check_dtor_kfuncs(btf, dtors, add_cnt);
if (ret < 0)
goto end;
tab = btf->dtor_kfunc_tab;
/* Only one call allowed for modules */
if (WARN_ON_ONCE(tab && btf_is_module(btf))) {
ret = -EINVAL;
goto end;
}
tab_cnt = tab ? tab->cnt : 0;
if (tab_cnt > U32_MAX - add_cnt) {
ret = -EOVERFLOW;
goto end;
}
if (tab_cnt + add_cnt >= BTF_DTOR_KFUNC_MAX_CNT) {
pr_err("cannot register more than %d kfunc destructors\n", BTF_DTOR_KFUNC_MAX_CNT);
ret = -E2BIG;
goto end;
}
tab = krealloc(btf->dtor_kfunc_tab,
offsetof(struct btf_id_dtor_kfunc_tab, dtors[tab_cnt + add_cnt]),
GFP_KERNEL | __GFP_NOWARN);
if (!tab) {
ret = -ENOMEM;
goto end;
}
if (!btf->dtor_kfunc_tab)
tab->cnt = 0;
btf->dtor_kfunc_tab = tab;
memcpy(tab->dtors + tab->cnt, dtors, add_cnt * sizeof(tab->dtors[0]));
tab->cnt += add_cnt;
sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
return 0;
end:
btf_free_dtor_kfunc_tab(btf);
btf_put(btf);
return ret;
}
EXPORT_SYMBOL_GPL(register_btf_id_dtor_kfuncs);
#define MAX_TYPES_ARE_COMPAT_DEPTH 2
/* Check local and target types for compatibility. This check is used for
* type-based CO-RE relocations and follow slightly different rules than
* field-based relocations. This function assumes that root types were already
* checked for name match. Beyond that initial root-level name check, names
* are completely ignored. Compatibility rules are as follows:
* - any two STRUCTs/UNIONs/FWDs/ENUMs/INTs/ENUM64s are considered compatible, but
* kind should match for local and target types (i.e., STRUCT is not
* compatible with UNION);
* - for ENUMs/ENUM64s, the size is ignored;
* - for INT, size and signedness are ignored;
* - for ARRAY, dimensionality is ignored, element types are checked for
* compatibility recursively;
* - CONST/VOLATILE/RESTRICT modifiers are ignored;
* - TYPEDEFs/PTRs are compatible if types they pointing to are compatible;
* - FUNC_PROTOs are compatible if they have compatible signature: same
* number of input args and compatible return and argument types.
* These rules are not set in stone and probably will be adjusted as we get
* more experience with using BPF CO-RE relocations.
*/
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id)
{
return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id,
MAX_TYPES_ARE_COMPAT_DEPTH);
}
#define MAX_TYPES_MATCH_DEPTH 2
int bpf_core_types_match(const struct btf *local_btf, u32 local_id,
const struct btf *targ_btf, u32 targ_id)
{
return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false,
MAX_TYPES_MATCH_DEPTH);
}
static bool bpf_core_is_flavor_sep(const char *s)
{
/* check X___Y name pattern, where X and Y are not underscores */
return s[0] != '_' && /* X */
s[1] == '_' && s[2] == '_' && s[3] == '_' && /* ___ */
s[4] != '_'; /* Y */
}
size_t bpf_core_essential_name_len(const char *name)
{
size_t n = strlen(name);
int i;
for (i = n - 5; i >= 0; i--) {
if (bpf_core_is_flavor_sep(name + i))
return i + 1;
}
return n;
}
struct bpf_cand_cache {
const char *name;
u32 name_len;
u16 kind;
u16 cnt;
struct {
const struct btf *btf;
u32 id;
} cands[];
};
static void bpf_free_cands(struct bpf_cand_cache *cands)
{
if (!cands->cnt)
/* empty candidate array was allocated on stack */
return;
kfree(cands);
}
static void bpf_free_cands_from_cache(struct bpf_cand_cache *cands)
{
kfree(cands->name);
kfree(cands);
}
#define VMLINUX_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *vmlinux_cand_cache[VMLINUX_CAND_CACHE_SIZE];
#define MODULE_CAND_CACHE_SIZE 31
static struct bpf_cand_cache *module_cand_cache[MODULE_CAND_CACHE_SIZE];
static DEFINE_MUTEX(cand_cache_mutex);
static void __print_cand_cache(struct bpf_verifier_log *log,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc;
int i, j;
for (i = 0; i < cache_size; i++) {
cc = cache[i];
if (!cc)
continue;
bpf_log(log, "[%d]%s(", i, cc->name);
for (j = 0; j < cc->cnt; j++) {
bpf_log(log, "%d", cc->cands[j].id);
if (j < cc->cnt - 1)
bpf_log(log, " ");
}
bpf_log(log, "), ");
}
}
static void print_cand_cache(struct bpf_verifier_log *log)
{
mutex_lock(&cand_cache_mutex);
bpf_log(log, "vmlinux_cand_cache:");
__print_cand_cache(log, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
bpf_log(log, "\nmodule_cand_cache:");
__print_cand_cache(log, module_cand_cache, MODULE_CAND_CACHE_SIZE);
bpf_log(log, "\n");
mutex_unlock(&cand_cache_mutex);
}
static u32 hash_cands(struct bpf_cand_cache *cands)
{
return jhash(cands->name, cands->name_len, 0);
}
static struct bpf_cand_cache *check_cand_cache(struct bpf_cand_cache *cands,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc = cache[hash_cands(cands) % cache_size];
if (cc && cc->name_len == cands->name_len &&
!strncmp(cc->name, cands->name, cands->name_len))
return cc;
return NULL;
}
static size_t sizeof_cands(int cnt)
{
return offsetof(struct bpf_cand_cache, cands[cnt]);
}
static struct bpf_cand_cache *populate_cand_cache(struct bpf_cand_cache *cands,
struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache **cc = &cache[hash_cands(cands) % cache_size], *new_cands;
if (*cc) {
bpf_free_cands_from_cache(*cc);
*cc = NULL;
}
new_cands = kmemdup(cands, sizeof_cands(cands->cnt), GFP_KERNEL);
if (!new_cands) {
bpf_free_cands(cands);
return ERR_PTR(-ENOMEM);
}
/* strdup the name, since it will stay in cache.
* the cands->name points to strings in prog's BTF and the prog can be unloaded.
*/
new_cands->name = kmemdup_nul(cands->name, cands->name_len, GFP_KERNEL);
bpf_free_cands(cands);
if (!new_cands->name) {
kfree(new_cands);
return ERR_PTR(-ENOMEM);
}
*cc = new_cands;
return new_cands;
}
#ifdef CONFIG_DEBUG_INFO_BTF_MODULES
static void __purge_cand_cache(struct btf *btf, struct bpf_cand_cache **cache,
int cache_size)
{
struct bpf_cand_cache *cc;
int i, j;
for (i = 0; i < cache_size; i++) {
cc = cache[i];
if (!cc)
continue;
if (!btf) {
/* when new module is loaded purge all of module_cand_cache,
* since new module might have candidates with the name
* that matches cached cands.
*/
bpf_free_cands_from_cache(cc);
cache[i] = NULL;
continue;
}
/* when module is unloaded purge cache entries
* that match module's btf
*/
for (j = 0; j < cc->cnt; j++)
if (cc->cands[j].btf == btf) {
bpf_free_cands_from_cache(cc);
cache[i] = NULL;
break;
}
}
}
static void purge_cand_cache(struct btf *btf)
{
mutex_lock(&cand_cache_mutex);
__purge_cand_cache(btf, module_cand_cache, MODULE_CAND_CACHE_SIZE);
mutex_unlock(&cand_cache_mutex);
}
#endif
static struct bpf_cand_cache *
bpf_core_add_cands(struct bpf_cand_cache *cands, const struct btf *targ_btf,
int targ_start_id)
{
struct bpf_cand_cache *new_cands;
const struct btf_type *t;
const char *targ_name;
size_t targ_essent_len;
int n, i;
n = btf_nr_types(targ_btf);
for (i = targ_start_id; i < n; i++) {
t = btf_type_by_id(targ_btf, i);
if (btf_kind(t) != cands->kind)
continue;
targ_name = btf_name_by_offset(targ_btf, t->name_off);
if (!targ_name)
continue;
/* the resched point is before strncmp to make sure that search
* for non-existing name will have a chance to schedule().
*/
cond_resched();
if (strncmp(cands->name, targ_name, cands->name_len) != 0)
continue;
targ_essent_len = bpf_core_essential_name_len(targ_name);
if (targ_essent_len != cands->name_len)
continue;
/* most of the time there is only one candidate for a given kind+name pair */
new_cands = kmalloc(sizeof_cands(cands->cnt + 1), GFP_KERNEL);
if (!new_cands) {
bpf_free_cands(cands);
return ERR_PTR(-ENOMEM);
}
memcpy(new_cands, cands, sizeof_cands(cands->cnt));
bpf_free_cands(cands);
cands = new_cands;
cands->cands[cands->cnt].btf = targ_btf;
cands->cands[cands->cnt].id = i;
cands->cnt++;
}
return cands;
}
static struct bpf_cand_cache *
bpf_core_find_cands(struct bpf_core_ctx *ctx, u32 local_type_id)
{
struct bpf_cand_cache *cands, *cc, local_cand = {};
const struct btf *local_btf = ctx->btf;
const struct btf_type *local_type;
const struct btf *main_btf;
size_t local_essent_len;
struct btf *mod_btf;
const char *name;
int id;
main_btf = bpf_get_btf_vmlinux();
if (IS_ERR(main_btf))
return ERR_CAST(main_btf);
if (!main_btf)
return ERR_PTR(-EINVAL);
local_type = btf_type_by_id(local_btf, local_type_id);
if (!local_type)
return ERR_PTR(-EINVAL);
name = btf_name_by_offset(local_btf, local_type->name_off);
if (str_is_empty(name))
return ERR_PTR(-EINVAL);
local_essent_len = bpf_core_essential_name_len(name);
cands = &local_cand;
cands->name = name;
cands->kind = btf_kind(local_type);
cands->name_len = local_essent_len;
cc = check_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
/* cands is a pointer to stack here */
if (cc) {
if (cc->cnt)
return cc;
goto check_modules;
}
/* Attempt to find target candidates in vmlinux BTF first */
cands = bpf_core_add_cands(cands, main_btf, 1);
if (IS_ERR(cands))
return ERR_CAST(cands);
/* cands is a pointer to kmalloced memory here if cands->cnt > 0 */
/* populate cache even when cands->cnt == 0 */
cc = populate_cand_cache(cands, vmlinux_cand_cache, VMLINUX_CAND_CACHE_SIZE);
if (IS_ERR(cc))
return ERR_CAST(cc);
/* if vmlinux BTF has any candidate, don't go for module BTFs */
if (cc->cnt)
return cc;
check_modules:
/* cands is a pointer to stack here and cands->cnt == 0 */
cc = check_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
if (cc)
/* if cache has it return it even if cc->cnt == 0 */
return cc;
/* If candidate is not found in vmlinux's BTF then search in module's BTFs */
spin_lock_bh(&btf_idr_lock);
idr_for_each_entry(&btf_idr, mod_btf, id) {
if (!btf_is_module(mod_btf))
continue;
/* linear search could be slow hence unlock/lock
* the IDR to avoiding holding it for too long
*/
btf_get(mod_btf);
spin_unlock_bh(&btf_idr_lock);
cands = bpf_core_add_cands(cands, mod_btf, btf_nr_types(main_btf));
if (IS_ERR(cands)) {
btf_put(mod_btf);
return ERR_CAST(cands);
}
spin_lock_bh(&btf_idr_lock);
btf_put(mod_btf);
}
spin_unlock_bh(&btf_idr_lock);
/* cands is a pointer to kmalloced memory here if cands->cnt > 0
* or pointer to stack if cands->cnd == 0.
* Copy it into the cache even when cands->cnt == 0 and
* return the result.
*/
return populate_cand_cache(cands, module_cand_cache, MODULE_CAND_CACHE_SIZE);
}
int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
int relo_idx, void *insn)
{
bool need_cands = relo->kind != BPF_CORE_TYPE_ID_LOCAL;
struct bpf_core_cand_list cands = {};
struct bpf_core_relo_res targ_res;
struct bpf_core_spec *specs;
int err;
/* ~4k of temp memory necessary to convert LLVM spec like "0:1:0:5"
* into arrays of btf_ids of struct fields and array indices.
*/
specs = kcalloc(3, sizeof(*specs), GFP_KERNEL);
if (!specs)
return -ENOMEM;
if (need_cands) {
struct bpf_cand_cache *cc;
int i;
mutex_lock(&cand_cache_mutex);
cc = bpf_core_find_cands(ctx, relo->type_id);
if (IS_ERR(cc)) {
bpf_log(ctx->log, "target candidate search failed for %d\n",
relo->type_id);
err = PTR_ERR(cc);
goto out;
}
if (cc->cnt) {
cands.cands = kcalloc(cc->cnt, sizeof(*cands.cands), GFP_KERNEL);
if (!cands.cands) {
err = -ENOMEM;
goto out;
}
}
for (i = 0; i < cc->cnt; i++) {
bpf_log(ctx->log,
"CO-RE relocating %s %s: found target candidate [%d]\n",
btf_kind_str[cc->kind], cc->name, cc->cands[i].id);
cands.cands[i].btf = cc->cands[i].btf;
cands.cands[i].id = cc->cands[i].id;
}
cands.len = cc->cnt;
/* cand_cache_mutex needs to span the cache lookup and
* copy of btf pointer into bpf_core_cand_list,
* since module can be unloaded while bpf_core_calc_relo_insn
* is working with module's btf.
*/
}
err = bpf_core_calc_relo_insn((void *)ctx->log, relo, relo_idx, ctx->btf, &cands, specs,
&targ_res);
if (err)
goto out;
err = bpf_core_patch_insn((void *)ctx->log, insn, relo->insn_off / 8, relo, relo_idx,
&targ_res);
out:
kfree(specs);
if (need_cands) {
kfree(cands.cands);
mutex_unlock(&cand_cache_mutex);
if (ctx->log->level & BPF_LOG_LEVEL2)
print_cand_cache(ctx->log);
}
return err;
}
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