Dmitry V. Levin
485f8fb250
* tests/seccomp.c: New file. * tests/seccomp.test: New test. * tests/Makefile.am (check_PROGRAMS): Add seccomp. (TESTS): Add seccomp.test. * tests/.gitignore: Add seccomp.
114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stddef.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <errno.h>
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#include <sys/syscall.h>
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#ifdef HAVE_PRCTL
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# include <sys/prctl.h>
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#endif
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#ifdef HAVE_LINUX_SECCOMP_H
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# include <linux/seccomp.h>
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#endif
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#ifdef HAVE_LINUX_FILTER_H
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# include <linux/filter.h>
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#endif
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#if defined HAVE_PRCTL \
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&& defined PR_SET_NO_NEW_PRIVS \
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&& defined PR_SET_SECCOMP \
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&& defined SECCOMP_MODE_FILTER \
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&& defined SECCOMP_RET_ERRNO \
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&& defined BPF_JUMP \
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&& defined BPF_STMT
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#define SOCK_FILTER_ALLOW_SYSCALL(nr) \
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BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, __NR_ ## nr, 0, 1), \
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BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW)
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#define SOCK_FILTER_DENY_SYSCALL(nr, err) \
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BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, __NR_ ## nr, 0, 1), \
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BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ERRNO | (SECCOMP_RET_DATA & (err)))
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#define SOCK_FILTER_KILL_PROCESS \
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BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL)
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#define PRINT_ALLOW_SYSCALL(nr) \
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printf("BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, %#x, 0, 0x1), " \
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"BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW), ", \
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__NR_ ## nr)
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#define PRINT_DENY_SYSCALL(nr, err) \
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printf("BPF_JUMP(BPF_JMP | BPF_K | BPF_JEQ, %#x, 0, 0x1), " \
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"BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ERRNO | %#x), ", \
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__NR_ ## nr, err)
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static const struct sock_filter filter[] = {
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/* load syscall number */
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BPF_STMT(BPF_LD | BPF_W | BPF_ABS, offsetof(struct seccomp_data, nr)),
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/* allow syscalls */
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SOCK_FILTER_ALLOW_SYSCALL(close),
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SOCK_FILTER_ALLOW_SYSCALL(exit),
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SOCK_FILTER_ALLOW_SYSCALL(exit_group),
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/* deny syscalls */
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SOCK_FILTER_DENY_SYSCALL(sync, EBUSY),
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SOCK_FILTER_DENY_SYSCALL(setsid, EPERM),
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/* kill process */
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SOCK_FILTER_KILL_PROCESS
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};
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static const struct sock_fprog prog = {
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.len = sizeof(filter) / sizeof(filter[0]),
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.filter = (struct sock_filter *) filter,
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};
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int
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main(void)
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{
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int fds[2];
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puts("prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) = 0");
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printf("prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, [");
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printf("BPF_STMT(BPF_LD | BPF_W | BPF_ABS, %#x), ",
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(unsigned) offsetof(struct seccomp_data, nr));
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PRINT_ALLOW_SYSCALL(close);
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PRINT_ALLOW_SYSCALL(exit);
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PRINT_ALLOW_SYSCALL(exit_group);
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PRINT_DENY_SYSCALL(sync, EBUSY),
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PRINT_DENY_SYSCALL(setsid, EPERM),
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printf("BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_KILL)");
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puts("]) = 0");
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puts("+++ exited with 0 +++");
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fflush(stdout);
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close(0);
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close(1);
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if (pipe(fds) ||
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prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
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prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) ||
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close(0) || close(1))
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_exit(77);
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_exit(0);
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}
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#else
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int main(void) { return 77; }
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#endif
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