1 /* 2 * Check verbose decoding of prctl PR_SET_SECCOMP SECCOMP_MODE_FILTER. 3 * 4 * Copyright (c) 2015-2016 Dmitry V. Levin <ldv (at) altlinux.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 */ 29 30 #include "tests.h" 31 #include <stddef.h> 32 #include <unistd.h> 33 #include <stdio.h> 34 #include <errno.h> 35 #include <asm/unistd.h> 36 37 #ifdef HAVE_PRCTL 38 # include <sys/prctl.h> 39 #endif 40 #ifdef HAVE_LINUX_SECCOMP_H 41 # include <linux/seccomp.h> 42 #endif 43 #ifdef HAVE_LINUX_FILTER_H 44 # include <linux/filter.h> 45 #endif 46 47 #if defined HAVE_PRCTL \ 48 && defined PR_SET_NO_NEW_PRIVS \ 49 && defined PR_SET_SECCOMP \ 50 && defined SECCOMP_MODE_FILTER \ 51 && defined SECCOMP_RET_ERRNO \ 52 && defined BPF_JUMP \ 53 && defined BPF_STMT 54 55 #define SOCK_FILTER_ALLOW_SYSCALL(nr) \ 56 BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, __NR_ ## nr, 0, 1), \ 57 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW) 58 59 #define SOCK_FILTER_DENY_SYSCALL(nr, err) \ 60 BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, __NR_ ## nr, 0, 1), \ 61 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO|(SECCOMP_RET_DATA & (err))) 62 63 #define SOCK_FILTER_KILL_PROCESS \ 64 BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL) 65 66 #define PRINT_ALLOW_SYSCALL(nr) \ 67 printf("BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, %#x, 0, 0x1), " \ 68 "BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ALLOW), ", \ 69 __NR_ ## nr) 70 71 #define PRINT_DENY_SYSCALL(nr, err) \ 72 printf("BPF_JUMP(BPF_JMP|BPF_K|BPF_JEQ, %#x, 0, 0x1), " \ 73 "BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_ERRNO|%#x), ", \ 74 __NR_ ## nr, err) 75 76 static const struct sock_filter filter[] = { 77 /* load syscall number */ 78 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, offsetof(struct seccomp_data, nr)), 79 80 /* allow syscalls */ 81 SOCK_FILTER_ALLOW_SYSCALL(close), 82 SOCK_FILTER_ALLOW_SYSCALL(exit), 83 SOCK_FILTER_ALLOW_SYSCALL(exit_group), 84 85 /* deny syscalls */ 86 SOCK_FILTER_DENY_SYSCALL(sync, EBUSY), 87 SOCK_FILTER_DENY_SYSCALL(setsid, EPERM), 88 89 /* kill process */ 90 SOCK_FILTER_KILL_PROCESS 91 }; 92 93 static const struct sock_fprog prog = { 94 .len = ARRAY_SIZE(filter), 95 .filter = (struct sock_filter *) filter, 96 }; 97 98 int 99 main(void) 100 { 101 int fds[2]; 102 103 puts("prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) = 0"); 104 105 printf("prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, {len=%u, filter=[", 106 prog.len); 107 108 printf("BPF_STMT(BPF_LD|BPF_W|BPF_ABS, %#x), ", 109 (unsigned) offsetof(struct seccomp_data, nr)); 110 111 PRINT_ALLOW_SYSCALL(close); 112 PRINT_ALLOW_SYSCALL(exit); 113 PRINT_ALLOW_SYSCALL(exit_group); 114 115 PRINT_DENY_SYSCALL(sync, EBUSY), 116 PRINT_DENY_SYSCALL(setsid, EPERM), 117 118 printf("BPF_STMT(BPF_RET|BPF_K, SECCOMP_RET_KILL)"); 119 120 puts("]}) = 0"); 121 puts("+++ exited with 0 +++"); 122 123 fflush(stdout); 124 close(0); 125 close(1); 126 127 if (pipe(fds)) 128 perror_msg_and_fail("pipe"); 129 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) 130 perror_msg_and_skip("PR_SET_NO_NEW_PRIVS"); 131 if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog)) 132 perror_msg_and_skip("PR_SET_SECCOMP"); 133 if (close(0) || close(1)) 134 _exit(77); 135 136 _exit(0); 137 } 138 139 #else 140 141 SKIP_MAIN_UNDEFINED("HAVE_PRCTL && PR_SET_NO_NEW_PRIVS && PR_SET_SECCOMP" 142 " && SECCOMP_MODE_FILTER && SECCOMP_RET_ERRNO" 143 " && BPF_JUMP && BPF_STMT") 144 145 #endif 146
