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/*
* Check decoding of socket filters.
*
* Copyright (c) 2017 Dmitry V. Levin <ldv@strace.io>
* Copyright (c) 2017-2021 The strace developers.
* All rights reserved.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "tests.h"
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <linux/filter.h>
/* SO_GET_FILTER was introduced by Linux commit v3.8-rc1~139^2~518 */
#ifndef SO_GET_FILTER
# define SO_GET_FILTER SO_ATTACH_FILTER
#endif
#define HEX_FMT "%#x"
#define PRINT_STMT(pfx, code_fmt, k_fmt, ...) \
printf("%sBPF_STMT(" code_fmt ", " k_fmt ")", pfx, __VA_ARGS__)
#define PRINT_JUMP(pfx, code_fmt, k, jt, jf, ...) \
printf("%sBPF_JUMP(" code_fmt ", %#x, %#x, %#x)", \
pfx, __VA_ARGS__, k, jt, jf)
static const struct sock_filter bpf_filter[] = {
BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_LL_OFF+4),
BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_NET_OFF+8),
BPF_STMT(BPF_LD|BPF_B|BPF_ABS, SKF_AD_OFF+SKF_AD_PROTOCOL),
BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, IPPROTO_UDP, 0, 5),
BPF_STMT(BPF_LD|BPF_W|BPF_LEN, 0),
BPF_JUMP(BPF_JMP|BPF_K|BPF_JGE, 100, 0, 3),
BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 42),
BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, 'a', 0, 1),
BPF_STMT(BPF_RET|BPF_K, -1U),
BPF_STMT(BPF_RET|BPF_K, 0)
};
static void
print_filter(void)
{
PRINT_STMT("[", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
XLAT_FMT "+4",
XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
XLAT_ARGS(SKF_LL_OFF));
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
XLAT_FMT "+8",
XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
XLAT_ARGS(SKF_NET_OFF));
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
XLAT_FMT "+" XLAT_FMT,
XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
XLAT_ARGS(SKF_AD_OFF), XLAT_ARGS(SKF_AD_PROTOCOL));
PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
IPPROTO_UDP, 0, 5,
XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JEQ));
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
HEX_FMT,
XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_W), XLAT_ARGS(BPF_LEN),
0);
PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
100, 0, 3,
XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JGE));
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
HEX_FMT,
XLAT_ARGS(BPF_LD), XLAT_ARGS(BPF_B), XLAT_ARGS(BPF_ABS),
42);
PRINT_JUMP(", ", XLAT_FMT "|" XLAT_FMT "|" XLAT_FMT,
'a', 0, 1,
XLAT_ARGS(BPF_JMP), XLAT_ARGS(BPF_K), XLAT_ARGS(BPF_JEQ));
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT,
HEX_FMT,
XLAT_ARGS(BPF_RET), XLAT_ARGS(BPF_K),
-1U);
PRINT_STMT(", ", XLAT_FMT "|" XLAT_FMT,
HEX_FMT,
XLAT_ARGS(BPF_RET), XLAT_ARGS(BPF_K),
0);
putchar(']');
}
static const char *errstr;
static int
get_filter(int fd, void *val, socklen_t *len)
{
int rc = getsockopt(fd, SOL_SOCKET, SO_GET_FILTER, val, len);
errstr = sprintrc(rc);
return rc;
}
static int
set_filter(int fd, void *val, socklen_t len)
{
int rc = setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, val, len);
errstr = sprintrc(rc);
return rc;
}
int
main(void)
{
int rc;
struct sock_filter *const filter =
tail_memdup(bpf_filter, sizeof(bpf_filter));
void *const efault = filter + ARRAY_SIZE(bpf_filter);
TAIL_ALLOC_OBJECT_CONST_PTR(struct sock_fprog, prog);
TAIL_ALLOC_OBJECT_CONST_PTR(socklen_t, len);
prog->len = ARRAY_SIZE(bpf_filter);
prog->filter = filter;
int fd = socket(AF_INET, SOCK_DGRAM, 0);
if (fd < 0)
perror_msg_and_skip("socket AF_INET SOCK_DGRAM");
/* query sock_filter program length -> 0 */
*len = BPF_MAXINSNS;
rc = get_filter(fd, NULL, len);
if (rc)
perror_msg_and_skip("getsockopt SOL_SOCKET SO_GET_FILTER");
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", NULL, [%u => 0]) "
"= 0\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER),
BPF_MAXINSNS);
/* getsockopt NULL optlen - EFAULT */
rc = get_filter(fd, NULL, NULL);
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", NULL, NULL) "
"= %s\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), errstr);
/* attach a filter */
rc = set_filter(fd, prog, sizeof(*prog));
if (rc)
perror_msg_and_skip("setsockopt SOL_SOCKET SO_ATTACH_FILTER");
printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", {len=%u, filter=",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_FILTER),
prog->len);
print_filter();
printf("}, %u) = 0\n", (unsigned int) sizeof(*prog));
/* setsockopt optlen is too small - EINVAL */
rc = set_filter(fd, prog, sizeof(*prog) - 4);
printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, %u) = %s\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_FILTER), prog,
(unsigned int) sizeof(*prog) - 4, errstr);
#ifdef SO_ATTACH_REUSEPORT_CBPF
rc = setsockopt(fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_CBPF,
prog, sizeof(*prog));
errstr = sprintrc(rc);
printf("setsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", {len=%u, filter=",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_ATTACH_REUSEPORT_CBPF),
prog->len);
print_filter();
printf("}, %u) = %s\n", (unsigned int) sizeof(*prog), errstr);
#endif
/* query sock_filter program length -> ARRAY_SIZE(bpf_filter) */
*len = 0;
rc = get_filter(fd, efault, len);
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [0 => %u]) "
"= %s\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), efault,
(unsigned int) ARRAY_SIZE(bpf_filter), errstr);
/* getsockopt optlen is too small - EINVAL */
*len = ARRAY_SIZE(bpf_filter) - 1;
rc = get_filter(fd, efault, len);
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [%u]) = %s\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER), efault,
(unsigned int) ARRAY_SIZE(bpf_filter) - 1, errstr);
/* getsockopt optval EFAULT */
*len = ARRAY_SIZE(bpf_filter);
rc = get_filter(fd, filter + 1, len);
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", %p, [%u]) = %s\n",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER),
filter + 1, (unsigned int) ARRAY_SIZE(bpf_filter), errstr);
/* getsockopt optlen is too large - truncated */
*len = ARRAY_SIZE(bpf_filter) + 1;
rc = get_filter(fd, filter, len);
printf("getsockopt(%d, " XLAT_FMT ", " XLAT_FMT ", ",
fd, XLAT_ARGS(SOL_SOCKET), XLAT_ARGS(SO_GET_FILTER));
print_filter();
printf(", [%u => %d]) = %s\n",
(unsigned int) ARRAY_SIZE(bpf_filter) + 1, *len, errstr);
puts("+++ exited with 0 +++");
return 0;
}
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