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strace/bpf.c
Dmitry V. Levin 805d6ea570 bpf: enhance decoding of BPF_MAP_LOOKUP_ELEM and BPF_MAP_GET_NEXT_KEY 
Print union bpf_attr.value field of BPF_MAP_LOOKUP_ELEM command
and union bpf_attr.next_key field of BPF_MAP_GET_NEXT_KEY command
on entering syscall.  These fields are addresses specified to the
kernel from userspace.  The amount of data written by the kernel
to these addresses is specified at the map creation time
by BPF_MAP_CREATE command and is not available at this point.

* bpf.c (decode_BPF_MAP_LOOKUP_ELEM): Print union bpf_attr.value
on entering syscall.
(decode_BPF_MAP_GET_NEXT_KEY): Print union bpf_attr.next_key
on entering syscall.
(bpf_map_io): Remove.
* tests/bpf.c (print_BPF_MAP_DELETE_ELEM_first,
print_BPF_MAP_DELETE_ELEM_attr, print_BPF_MAP_GET_NEXT_KEY_first,
print_BPF_MAP_GET_NEXT_KEY_attr): Replace macro redirects with
new functions.
(print_BPF_MAP_LOOKUP_ELEM_first, print_BPF_MAP_LOOKUP_ELEM_attr,
2017-07-27 20:11:33 +00:00

333 lines
8.8 KiB
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/*
* Copyright (c) 2015-2017 Dmitry V. Levin <ldv@altlinux.org>
* Copyright (c) 2017 Quentin Monnet <quentin.monnet@6wind.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "defs.h"
#include "print_fields.h"
#ifdef HAVE_LINUX_BPF_H
# include <linux/bpf.h>
#endif
#include "xlat/bpf_commands.h"
#include "xlat/bpf_map_types.h"
#include "xlat/bpf_map_flags.h"
#include "xlat/bpf_prog_types.h"
#include "xlat/bpf_prog_flags.h"
#include "xlat/bpf_map_update_elem_flags.h"
#include "xlat/bpf_attach_type.h"
#include "xlat/bpf_attach_flags.h"
#define DECL_BPF_CMD_DECODER(bpf_cmd_decoder) \
int \
bpf_cmd_decoder(struct tcb *const tcp, \
const kernel_ulong_t addr, \
const unsigned int size, \
void *const data) \
/* End of DECL_BPF_CMD_DECODER definition. */
#define DEF_BPF_CMD_DECODER(bpf_cmd) \
static DECL_BPF_CMD_DECODER(decode_ ## bpf_cmd)
#define BPF_CMD_ENTRY(bpf_cmd) \
[bpf_cmd] = decode_ ## bpf_cmd
typedef DECL_BPF_CMD_DECODER((*bpf_cmd_decoder_t));
static int
decode_attr_extra_data(struct tcb *const tcp,
const char *data,
unsigned int size,
const size_t attr_size)
{
if (size <= attr_size)
return 0;
data += attr_size;
size -= attr_size;
unsigned int i;
for (i = 0; i < size; ++i) {
if (data[i]) {
tprints(", ");
if (abbrev(tcp))
tprints("...");
else
print_quoted_string(data, size,
QUOTE_FORCE_HEX);
return RVAL_DECODED;
}
}
return 0;
}
DEF_BPF_CMD_DECODER(BPF_MAP_CREATE)
{
struct {
uint32_t map_type, key_size, value_size, max_entries,
map_flags, inner_map_fd;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_XVAL("{", attr, map_type, bpf_map_types,
"BPF_MAP_TYPE_???");
PRINT_FIELD_U(", ", attr, key_size);
PRINT_FIELD_U(", ", attr, value_size);
PRINT_FIELD_U(", ", attr, max_entries);
PRINT_FIELD_FLAGS(", ", attr, map_flags, bpf_map_flags, "BPF_F_???");
PRINT_FIELD_FD(", ", attr, inner_map_fd, tcp);
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED | RVAL_FD;
}
DEF_BPF_CMD_DECODER(BPF_MAP_LOOKUP_ELEM)
{
struct bpf_io_elem_struct {
uint32_t map_fd;
uint64_t ATTRIBUTE_ALIGNED(8) key, value;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, map_fd, tcp);
PRINT_FIELD_X(", ", attr, key);
PRINT_FIELD_X(", ", attr, value);
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
DEF_BPF_CMD_DECODER(BPF_MAP_UPDATE_ELEM)
{
struct {
uint32_t map_fd;
uint64_t ATTRIBUTE_ALIGNED(8) key;
uint64_t ATTRIBUTE_ALIGNED(8) value;
uint64_t flags;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, map_fd, tcp);
PRINT_FIELD_X(", ", attr, key);
PRINT_FIELD_X(", ", attr, value);
PRINT_FIELD_XVAL(", ", attr, flags, bpf_map_update_elem_flags,
"BPF_???");
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
DEF_BPF_CMD_DECODER(BPF_MAP_DELETE_ELEM)
{
struct {
uint32_t map_fd;
uint64_t ATTRIBUTE_ALIGNED(8) key;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, map_fd, tcp);
PRINT_FIELD_X(", ", attr, key);
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
DEF_BPF_CMD_DECODER(BPF_MAP_GET_NEXT_KEY)
{
struct bpf_io_elem_struct {
uint32_t map_fd;
uint64_t ATTRIBUTE_ALIGNED(8) key, next_key;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, map_fd, tcp);
PRINT_FIELD_X(", ", attr, key);
PRINT_FIELD_X(", ", attr, next_key);
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
DEF_BPF_CMD_DECODER(BPF_PROG_LOAD)
{
struct bpf_prog_load {
uint32_t prog_type, insn_cnt;
uint64_t ATTRIBUTE_ALIGNED(8) insns, license;
uint32_t log_level, log_size;
uint64_t ATTRIBUTE_ALIGNED(8) log_buf;
uint32_t kern_version, prog_flags;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_XVAL("{", attr, prog_type, bpf_prog_types,
"BPF_PROG_TYPE_???");
PRINT_FIELD_U(", ", attr, insn_cnt);
PRINT_FIELD_X(", ", attr, insns);
PRINT_FIELD_STR(", ", attr, license, tcp);
PRINT_FIELD_U(", ", attr, log_level);
PRINT_FIELD_U(", ", attr, log_size);
PRINT_FIELD_X(", ", attr, log_buf);
PRINT_FIELD_U(", ", attr, kern_version);
PRINT_FIELD_FLAGS(", ", attr, prog_flags, bpf_prog_flags, "BPF_F_???");
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED | RVAL_FD;
}
DEF_BPF_CMD_DECODER(BPF_OBJ_PIN)
{
struct bpf_obj {
uint64_t ATTRIBUTE_ALIGNED(8) pathname;
uint32_t bpf_fd;
} attr = {};
const size_t attr_size =
offsetofend(struct bpf_obj, bpf_fd);
const unsigned int len = size < attr_size ? size : attr_size;
memcpy(&attr, data, len);
PRINT_FIELD_PATH("{", attr, pathname, tcp);
PRINT_FIELD_FD(", ", attr, bpf_fd, tcp);
decode_attr_extra_data(tcp, data, size, attr_size);
tprints("}");
return RVAL_DECODED | RVAL_FD;
}
#define decode_BPF_OBJ_GET decode_BPF_OBJ_PIN
DEF_BPF_CMD_DECODER(BPF_PROG_ATTACH)
{
struct {
uint32_t target_fd, attach_bpf_fd, attach_type, attach_flags;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, target_fd, tcp);
PRINT_FIELD_FD(", ", attr, attach_bpf_fd, tcp);
PRINT_FIELD_XVAL(", ", attr, attach_type, bpf_attach_type, "BPF_???");
PRINT_FIELD_FLAGS(", ", attr, attach_flags, bpf_attach_flags,
"BPF_F_???");
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
DEF_BPF_CMD_DECODER(BPF_PROG_DETACH)
{
struct {
uint32_t target_fd, dummy, attach_type;
} attr = {};
const unsigned int len = size < sizeof(attr) ? size : sizeof(attr);
memcpy(&attr, data, len);
PRINT_FIELD_FD("{", attr, target_fd, tcp);
PRINT_FIELD_XVAL(", ", attr, attach_type, bpf_attach_type, "BPF_???");
decode_attr_extra_data(tcp, data, size, sizeof(attr));
tprints("}");
return RVAL_DECODED;
}
SYS_FUNC(bpf)
{
static const bpf_cmd_decoder_t bpf_cmd_decoders[] = {
BPF_CMD_ENTRY(BPF_MAP_CREATE),
BPF_CMD_ENTRY(BPF_MAP_LOOKUP_ELEM),
BPF_CMD_ENTRY(BPF_MAP_UPDATE_ELEM),
BPF_CMD_ENTRY(BPF_MAP_DELETE_ELEM),
BPF_CMD_ENTRY(BPF_MAP_GET_NEXT_KEY),
BPF_CMD_ENTRY(BPF_PROG_LOAD),
BPF_CMD_ENTRY(BPF_OBJ_PIN),
BPF_CMD_ENTRY(BPF_OBJ_GET),
BPF_CMD_ENTRY(BPF_PROG_ATTACH),
BPF_CMD_ENTRY(BPF_PROG_DETACH),
};
const unsigned int cmd = tcp->u_arg[0];
const kernel_ulong_t addr = tcp->u_arg[1];
const unsigned int size = tcp->u_arg[2];
int rc;
if (entering(tcp)) {
static size_t page_size;
static char *buf;
if (!buf) {
page_size = get_pagesize();
buf = xmalloc(page_size);
}
printxval(bpf_commands, cmd, "BPF_???");
tprints(", ");
if (size > 0
&& size <= get_pagesize()
&& cmd < ARRAY_SIZE(bpf_cmd_decoders)
&& bpf_cmd_decoders[cmd]) {
rc = umoven_or_printaddr(tcp, addr, size, buf)
? RVAL_DECODED
: bpf_cmd_decoders[cmd](tcp, addr, size, buf);
} else {
printaddr(addr);
rc = RVAL_DECODED;
}
} else {
rc = bpf_cmd_decoders[cmd](tcp, addr, size, NULL) | RVAL_DECODED;
}
if (rc & RVAL_DECODED)
tprintf(", %u", size);
return rc;
}
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