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bpf: Add file mode configuration into bpf maps

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Introduce the map read/write flags to the eBPF syscalls that returns the
map fd. The flags is used to set up the file mode when construct a new
file descriptor for bpf maps. To not break the backward capability, the
f_flags is set to O_RDWR if the flag passed by syscall is 0. Otherwise
it should be O_RDONLY or O_WRONLY. When the userspace want to modify or
read the map content, it will check the file mode to see if it is
allowed to make the change.

Signed-off-by: Chenbo Feng <fengc@google.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Chenbo Feng 2017-10-18 13:00:22 -07:00 committed by David S. Miller
parent aec72f3392
commit 6e71b04a82
11 changed files with 122 additions and 26 deletions
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8
include/linux/bpf.h
View File

@ -315,11 +315,11 @@ void bpf_map_area_free(void *base);
extern int sysctl_unprivileged_bpf_disabled;
int bpf_map_new_fd(struct bpf_map *map);
int bpf_map_new_fd(struct bpf_map *map, int flags);
int bpf_prog_new_fd(struct bpf_prog *prog);
int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
int bpf_obj_get_user(const char __user *pathname);
int bpf_obj_get_user(const char __user *pathname, int flags);
int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
@ -338,6 +338,8 @@ int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
void *key, void *value, u64 map_flags);
int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
int bpf_get_file_flag(int flags);
/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
* forced to use 'long' read/writes to try to atomically copy long counters.
* Best-effort only. No barriers here, since it _will_ race with concurrent
@ -421,7 +423,7 @@ static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
{
}
static inline int bpf_obj_get_user(const char __user *pathname)
static inline int bpf_obj_get_user(const char __user *pathname, int flags)
{
return -EOPNOTSUPP;
}

6
include/uapi/linux/bpf.h
View File

@ -218,6 +218,10 @@ enum bpf_attach_type {
#define BPF_OBJ_NAME_LEN 16U
/* Flags for accessing BPF object */
#define BPF_F_RDONLY (1U << 3)
#define BPF_F_WRONLY (1U << 4)
union bpf_attr {
struct { /* anonymous struct used by BPF_MAP_CREATE command */
__u32 map_type; /* one of enum bpf_map_type */
@ -260,6 +264,7 @@ union bpf_attr {
struct { /* anonymous struct used by BPF_OBJ_* commands */
__aligned_u64 pathname;
__u32 bpf_fd;
__u32 file_flags;
};
struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
@ -287,6 +292,7 @@ union bpf_attr {
__u32 map_id;
};
__u32 next_id;
__u32 open_flags;
};
struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */

6
kernel/bpf/arraymap.c
View File

@ -19,6 +19,9 @@
#include "map_in_map.h"
#define ARRAY_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
static void bpf_array_free_percpu(struct bpf_array *array)
{
int i;
@ -56,7 +59,8 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
attr->value_size == 0 || attr->map_flags & ~BPF_F_NUMA_NODE ||
attr->value_size == 0 ||
attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
(percpu && numa_node != NUMA_NO_NODE))
return ERR_PTR(-EINVAL);

5
kernel/bpf/devmap.c
View File

@ -50,6 +50,9 @@
#include <linux/bpf.h>
#include <linux/filter.h>
#define DEV_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
struct bpf_dtab_netdev {
struct net_device *dev;
struct bpf_dtab *dtab;
@ -80,7 +83,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE)
attr->value_size != 4 || attr->map_flags & ~DEV_CREATE_FLAG_MASK)
return ERR_PTR(-EINVAL);
dtab = kzalloc(sizeof(*dtab), GFP_USER);

5
kernel/bpf/hashtab.c
View File

@ -18,8 +18,9 @@
#include "bpf_lru_list.h"
#include "map_in_map.h"
#define HTAB_CREATE_FLAG_MASK \
(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE)
#define HTAB_CREATE_FLAG_MASK \
(BPF_F_NO_PREALLOC | BPF_F_NO_COMMON_LRU | BPF_F_NUMA_NODE | \
BPF_F_RDONLY | BPF_F_WRONLY)
struct bucket {
struct hlist_nulls_head head;

15
kernel/bpf/inode.c
View File

@ -295,7 +295,7 @@ out:
}
static void *bpf_obj_do_get(const struct filename *pathname,
enum bpf_type *type)
enum bpf_type *type, int flags)
{
struct inode *inode;
struct path path;
@ -307,7 +307,7 @@ static void *bpf_obj_do_get(const struct filename *pathname,
return ERR_PTR(ret);
inode = d_backing_inode(path.dentry);
ret = inode_permission(inode, MAY_WRITE);
ret = inode_permission(inode, ACC_MODE(flags));
if (ret)
goto out;
@ -326,18 +326,23 @@ out:
return ERR_PTR(ret);
}
int bpf_obj_get_user(const char __user *pathname)
int bpf_obj_get_user(const char __user *pathname, int flags)
{
enum bpf_type type = BPF_TYPE_UNSPEC;
struct filename *pname;
int ret = -ENOENT;
int f_flags;
void *raw;
f_flags = bpf_get_file_flag(flags);
if (f_flags < 0)
return f_flags;
pname = getname(pathname);
if (IS_ERR(pname))
return PTR_ERR(pname);
raw = bpf_obj_do_get(pname, &type);
raw = bpf_obj_do_get(pname, &type, f_flags);
if (IS_ERR(raw)) {
ret = PTR_ERR(raw);
goto out;
@ -346,7 +351,7 @@ int bpf_obj_get_user(const char __user *pathname)
if (type == BPF_TYPE_PROG)
ret = bpf_prog_new_fd(raw);
else if (type == BPF_TYPE_MAP)
ret = bpf_map_new_fd(raw);
ret = bpf_map_new_fd(raw, f_flags);
else
goto out;

3
kernel/bpf/lpm_trie.c
View File

@ -495,7 +495,8 @@ out:
#define LPM_KEY_SIZE_MAX LPM_KEY_SIZE(LPM_DATA_SIZE_MAX)
#define LPM_KEY_SIZE_MIN LPM_KEY_SIZE(LPM_DATA_SIZE_MIN)
#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE)
#define LPM_CREATE_FLAG_MASK (BPF_F_NO_PREALLOC | BPF_F_NUMA_NODE | \
BPF_F_RDONLY | BPF_F_WRONLY)
static struct bpf_map *trie_alloc(union bpf_attr *attr)
{

5
kernel/bpf/sockmap.c
View File

@ -40,6 +40,9 @@
#include <linux/list.h>
#include <net/strparser.h>
#define SOCK_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
struct bpf_stab {
struct bpf_map map;
struct sock **sock_map;
@ -489,7 +492,7 @@ static struct bpf_map *sock_map_alloc(union bpf_attr *attr)
/* check sanity of attributes */
if (attr->max_entries == 0 || attr->key_size != 4 ||
attr->value_size != 4 || attr->map_flags & ~BPF_F_NUMA_NODE)
attr->value_size != 4 || attr->map_flags & ~SOCK_CREATE_FLAG_MASK)
return ERR_PTR(-EINVAL);
if (attr->value_size > KMALLOC_MAX_SIZE)

5
kernel/bpf/stackmap.c
View File

@ -11,6 +11,9 @@
#include <linux/perf_event.h>
#include "percpu_freelist.h"
#define STACK_CREATE_FLAG_MASK \
(BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
struct stack_map_bucket {
struct pcpu_freelist_node fnode;
u32 hash;
@ -60,7 +63,7 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr)
if (!capable(CAP_SYS_ADMIN))
return ERR_PTR(-EPERM);
if (attr->map_flags & ~BPF_F_NUMA_NODE)
if (attr->map_flags & ~STACK_CREATE_FLAG_MASK)
return ERR_PTR(-EINVAL);
/* check sanity of attributes */

88
kernel/bpf/syscall.c
View File

@ -34,6 +34,8 @@
#define IS_FD_HASH(map) ((map)->map_type == BPF_MAP_TYPE_HASH_OF_MAPS)
#define IS_FD_MAP(map) (IS_FD_ARRAY(map) || IS_FD_HASH(map))
#define BPF_OBJ_FLAG_MASK (BPF_F_RDONLY | BPF_F_WRONLY)
DEFINE_PER_CPU(int, bpf_prog_active);
static DEFINE_IDR(prog_idr);
static DEFINE_SPINLOCK(prog_idr_lock);
@ -294,17 +296,48 @@ static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp)
}
#endif
static ssize_t bpf_dummy_read(struct file *filp, char __user *buf, size_t siz,
loff_t *ppos)
{
/* We need this handler such that alloc_file() enables
* f_mode with FMODE_CAN_READ.
*/
return -EINVAL;
}
static ssize_t bpf_dummy_write(struct file *filp, const char __user *buf,
size_t siz, loff_t *ppos)
{
/* We need this handler such that alloc_file() enables
* f_mode with FMODE_CAN_WRITE.
*/
return -EINVAL;
}
static const struct file_operations bpf_map_fops = {
#ifdef CONFIG_PROC_FS
.show_fdinfo = bpf_map_show_fdinfo,
#endif
.release = bpf_map_release,
.read = bpf_dummy_read,
.write = bpf_dummy_write,
};
int bpf_map_new_fd(struct bpf_map *map)
int bpf_map_new_fd(struct bpf_map *map, int flags)
{
return anon_inode_getfd("bpf-map", &bpf_map_fops, map,
O_RDWR | O_CLOEXEC);
flags | O_CLOEXEC);
}
int bpf_get_file_flag(int flags)
{
if ((flags & BPF_F_RDONLY) && (flags & BPF_F_WRONLY))
return -EINVAL;
if (flags & BPF_F_RDONLY)
return O_RDONLY;
if (flags & BPF_F_WRONLY)
return O_WRONLY;
return O_RDWR;
}
/* helper macro to check that unused fields 'union bpf_attr' are zero */
@ -344,12 +377,17 @@ static int map_create(union bpf_attr *attr)
{
int numa_node = bpf_map_attr_numa_node(attr);
struct bpf_map *map;
int f_flags;
int err;
err = CHECK_ATTR(BPF_MAP_CREATE);
if (err)
return -EINVAL;
f_flags = bpf_get_file_flag(attr->map_flags);
if (f_flags < 0)
return f_flags;
if (numa_node != NUMA_NO_NODE &&
((unsigned int)numa_node >= nr_node_ids ||
!node_online(numa_node)))
@ -375,7 +413,7 @@ static int map_create(union bpf_attr *attr)
if (err)
goto free_map;
err = bpf_map_new_fd(map);
err = bpf_map_new_fd(map, f_flags);
if (err < 0) {
/* failed to allocate fd.
* bpf_map_put() is needed because the above
@ -490,6 +528,11 @@ static int map_lookup_elem(union bpf_attr *attr)
if (IS_ERR(map))
return PTR_ERR(map);
if (!(f.file->f_mode & FMODE_CAN_READ)) {
err = -EPERM;
goto err_put;
}
key = memdup_user(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
@ -570,6 +613,11 @@ static int map_update_elem(union bpf_attr *attr)
if (IS_ERR(map))
return PTR_ERR(map);
if (!(f.file->f_mode & FMODE_CAN_WRITE)) {
err = -EPERM;
goto err_put;
}
key = memdup_user(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
@ -659,6 +707,11 @@ static int map_delete_elem(union bpf_attr *attr)
if (IS_ERR(map))
return PTR_ERR(map);
if (!(f.file->f_mode & FMODE_CAN_WRITE)) {
err = -EPERM;
goto err_put;
}
key = memdup_user(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
@ -702,6 +755,11 @@ static int map_get_next_key(union bpf_attr *attr)
if (IS_ERR(map))
return PTR_ERR(map);
if (!(f.file->f_mode & FMODE_CAN_READ)) {
err = -EPERM;
goto err_put;
}
if (ukey) {
key = memdup_user(ukey, map->key_size);
if (IS_ERR(key)) {
@ -908,6 +966,8 @@ static const struct file_operations bpf_prog_fops = {
.show_fdinfo = bpf_prog_show_fdinfo,
#endif
.release = bpf_prog_release,
.read = bpf_dummy_read,
.write = bpf_dummy_write,
};
int bpf_prog_new_fd(struct bpf_prog *prog)
@ -1117,11 +1177,11 @@ free_prog_nouncharge:
return err;
}
#define BPF_OBJ_LAST_FIELD bpf_fd
#define BPF_OBJ_LAST_FIELD file_flags
static int bpf_obj_pin(const union bpf_attr *attr)
{
if (CHECK_ATTR(BPF_OBJ))
if (CHECK_ATTR(BPF_OBJ) || attr->file_flags != 0)
return -EINVAL;
return bpf_obj_pin_user(attr->bpf_fd, u64_to_user_ptr(attr->pathname));
@ -1129,10 +1189,12 @@ static int bpf_obj_pin(const union bpf_attr *attr)
static int bpf_obj_get(const union bpf_attr *attr)
{
if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0)
if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0 ||
attr->file_flags & ~BPF_OBJ_FLAG_MASK)
return -EINVAL;
return bpf_obj_get_user(u64_to_user_ptr(attr->pathname));
return bpf_obj_get_user(u64_to_user_ptr(attr->pathname),
attr->file_flags);
}
#ifdef CONFIG_CGROUP_BPF
@ -1392,20 +1454,26 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
return fd;
}
#define BPF_MAP_GET_FD_BY_ID_LAST_FIELD map_id
#define BPF_MAP_GET_FD_BY_ID_LAST_FIELD open_flags
static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
{
struct bpf_map *map;
u32 id = attr->map_id;
int f_flags;
int fd;
if (CHECK_ATTR(BPF_MAP_GET_FD_BY_ID))
if (CHECK_ATTR(BPF_MAP_GET_FD_BY_ID) ||
attr->open_flags & ~BPF_OBJ_FLAG_MASK)
return -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
f_flags = bpf_get_file_flag(attr->open_flags);
if (f_flags < 0)
return f_flags;
spin_lock_bh(&map_idr_lock);
map = idr_find(&map_idr, id);
if (map)
@ -1417,7 +1485,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
if (IS_ERR(map))
return PTR_ERR(map);
fd = bpf_map_new_fd(map);
fd = bpf_map_new_fd(map, f_flags);
if (fd < 0)
bpf_map_put(map);

2
net/netfilter/xt_bpf.c
View File

@ -56,7 +56,7 @@ static int __bpf_mt_check_path(const char *path, struct bpf_prog **ret)
int retval, fd;
set_fs(KERNEL_DS);
fd = bpf_obj_get_user(path);
fd = bpf_obj_get_user(path, 0);
set_fs(oldfs);
if (fd < 0)
return fd;