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/*
* Check verbose decoding of seccomp SECCOMP_SET_MODE_FILTER.
*
* Copyright (c) 2015-2016 Dmitry V. Levin <ldv@altlinux.org>
* Copyright (c) 2016-2017 The strace developers.
* 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 "tests.h"
#include <errno.h>
#include <stddef.h>
#include <stdio.h>
#include <asm/unistd.h>
#include <unistd.h>
#ifdef HAVE_PRCTL
# include <sys/prctl.h>
#endif
#ifdef HAVE_LINUX_SECCOMP_H
# include <linux/seccomp.h>
#endif
#ifdef HAVE_LINUX_FILTER_H
# include <linux/filter.h>
#endif
#if defined __NR_seccomp \
&& defined PR_SET_NO_NEW_PRIVS \
&& defined SECCOMP_SET_MODE_FILTER \
&& defined SECCOMP_RET_ERRNO \
&& defined BPF_JUMP \
&& defined BPF_STMT
#define SOCK_FILTER_ALLOW_SYSCALL(nr) \
BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, __NR_ ## nr, 0, 1), \
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW)
#define SOCK_FILTER_DENY_SYSCALL(nr, err) \
BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, __NR_ ## nr, 0, 1), \
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO|(SECCOMP_RET_DATA & (err)))
#define SOCK_FILTER_KILL_PROCESS \
BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL)
#define PRINT_ALLOW_SYSCALL(nr) \
tprintf("BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, %#x, 0, 0x1), " \
"BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW), ", \
__NR_ ## nr)
#define PRINT_DENY_SYSCALL(nr, err) \
tprintf("BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, %#x, 0, 0x1), " \
"BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO|%#x), ", \
__NR_ ## nr, err)
static const struct sock_filter filter_c[] = {
/* load syscall number */
BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, nr)),
/* allow syscalls */
SOCK_FILTER_ALLOW_SYSCALL(close),
SOCK_FILTER_ALLOW_SYSCALL(exit),
SOCK_FILTER_ALLOW_SYSCALL(exit_group),
/* deny syscalls */
SOCK_FILTER_DENY_SYSCALL(sync, EBUSY),
SOCK_FILTER_DENY_SYSCALL(setsid, EPERM),
/* kill process */
SOCK_FILTER_KILL_PROCESS
};
#ifndef BPF_MAXINSNS
# define BPF_MAXINSNS 4096
#endif
int
main(void)
{
tprintf("%s", "");
static const char kill_stmt_txt[] =
"BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL)";
struct sock_filter *const filter =
tail_memdup(filter_c, sizeof(filter_c));
struct sock_filter *const big_filter =
tail_alloc(sizeof(*big_filter) * (BPF_MAXINSNS + 1));
TAIL_ALLOC_OBJECT_CONST_PTR(struct sock_fprog, prog);
int fds[2];
if (pipe(fds))
perror_msg_and_fail("pipe");
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0))
perror_msg_and_skip("PR_SET_NO_NEW_PRIVS");
prog->filter = filter + ARRAY_SIZE(filter_c);
prog->len = 1;
syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, prog);
tprintf("seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=1, filter=%p})"
" = -1 EFAULT (%m)\n", prog->filter);
prog->filter = filter + ARRAY_SIZE(filter_c) - 1;
prog->len = 3;
syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, prog);
tprintf("seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=%u"
", filter=[%s, %p]}) = -1 EFAULT (%m)\n",
prog->len, kill_stmt_txt, filter + ARRAY_SIZE(filter_c));
prog->len = 0;
syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, prog);
tprintf("seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=0, filter=[]})"
" = -1 EINVAL (%m)\n");
unsigned int i;
for (i = 0; i <= BPF_MAXINSNS; ++i) {
const struct sock_filter stmt =
BPF_STMT(BPF_CLASS(i), i << 16);
big_filter[i] = stmt;
}
prog->filter = big_filter;
prog->len = BPF_MAXINSNS + 1;
tprintf("seccomp(SECCOMP_SET_MODE_FILTER, %s, {len=%u, filter=[",
"SECCOMP_FILTER_FLAG_TSYNC|0xfffffffe", prog->len);
for (i = 0; i < BPF_MAXINSNS; ++i) {
if (i)
tprintf(", ");
switch(BPF_CLASS(i)) {
case BPF_LD:
tprintf("BPF_STMT(BPF_LD|BPF_W|BPF_IMM, %#x)", i << 16);
break;
case BPF_LDX:
tprintf("BPF_STMT(BPF_LDX|BPF_W|BPF_IMM, %#x)", i << 16);
break;
case BPF_ST:
tprintf("BPF_STMT(BPF_ST, %#x)", i << 16);
break;
case BPF_STX:
tprintf("BPF_STMT(BPF_STX, %#x)", i << 16);
break;
case BPF_ALU:
tprintf("BPF_STMT(BPF_ALU|BPF_K|BPF_ADD, %#x)", i << 16);
break;
case BPF_JMP:
tprintf("BPF_STMT(BPF_JMP|BPF_K|BPF_JA, %#x)", i << 16);
break;
case BPF_RET:
tprintf("BPF_STMT(BPF_RET|BPF_K, %#x"
" /* SECCOMP_RET_??? */)", i << 16);
break;
case BPF_MISC:
tprintf("BPF_STMT(BPF_MISC|BPF_TAX, %#x)", i << 16);
break;
}
}
tprintf(", ...]})");
syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, -1, prog);
tprintf(" = -1 EINVAL (%m)\n");
prog->filter = filter;
prog->len = ARRAY_SIZE(filter_c);
tprintf("seccomp(SECCOMP_SET_MODE_FILTER, 0, {len=%u, filter=[",
prog->len);
tprintf("BPF_STMT(BPF_LD|BPF_W|BPF_ABS, %#x), ",
(unsigned) offsetof(struct seccomp_data, nr));
PRINT_ALLOW_SYSCALL(close);
PRINT_ALLOW_SYSCALL(exit);
PRINT_ALLOW_SYSCALL(exit_group);
PRINT_DENY_SYSCALL(sync, EBUSY),
PRINT_DENY_SYSCALL(setsid, EPERM),
tprintf("%s]}) = 0\n+++ exited with 0 +++\n", kill_stmt_txt);
if (syscall(__NR_seccomp, SECCOMP_SET_MODE_FILTER, 0, prog))
perror_msg_and_skip("SECCOMP_SET_MODE_FILTER");
if (close(0) || close(1))
_exit(77);
_exit(0);
}
#else
SKIP_MAIN_UNDEFINED("__NR_seccomp && PR_SET_NO_NEW_PRIVS"
" && SECCOMP_SET_MODE_FILTER && SECCOMP_RET_ERRNO"
" && BPF_JUMP && BPF_STMT")
#endif
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