1 /* 2 * Copyright (c) 2011 Dag-Erling Smorgrav 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 15 */ 16 17 #include "includes.h" 18 19 #ifdef SANDBOX_CAPSICUM 20 21 #include <sys/types.h> 22 #include <sys/time.h> 23 #include <sys/resource.h> 24 #include <sys/capsicum.h> 25 26 #include <errno.h> 27 #include <stdarg.h> 28 #include <stdio.h> 29 #include <stdlib.h> 30 #include <string.h> 31 #include <unistd.h> 32 #ifdef HAVE_CAPSICUM_HELPERS_H 33 #include <capsicum_helpers.h> 34 #endif 35 36 #include "log.h" 37 #include "monitor.h" 38 #include "ssh-sandbox.h" 39 #include "xmalloc.h" 40 41 /* 42 * Capsicum sandbox that sets zero nfiles, nprocs and filesize rlimits, 43 * limits rights on stdout, stdin, stderr, monitor and switches to 44 * capability mode. 45 */ 46 47 struct ssh_sandbox { 48 int m_recvfd; 49 int m_log_sendfd; 50 }; 51 52 struct ssh_sandbox * 53 ssh_sandbox_init(struct monitor *monitor) 54 { 55 struct ssh_sandbox *box; 56 57 debug3("%s: preparing capsicum sandbox", __func__); 58 box = xcalloc(1, sizeof(*box)); 59 box->m_recvfd = monitor->m_recvfd; 60 box->m_log_sendfd = monitor->m_log_sendfd; 61 return box; 62 } 63 64 void 65 ssh_sandbox_child(struct ssh_sandbox *box) 66 { 67 struct rlimit rl_zero; 68 cap_rights_t rights; 69 70 #ifdef HAVE_CAPH_CACHE_TZDATA 71 caph_cache_tzdata(); 72 #endif 73 74 rl_zero.rlim_cur = rl_zero.rlim_max = 0; 75 76 if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1) 77 fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s", 78 __func__, strerror(errno)); 79 #ifndef SANDBOX_SKIP_RLIMIT_NOFILE 80 if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1) 81 fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s", 82 __func__, strerror(errno)); 83 #endif 84 if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1) 85 fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s", 86 __func__, strerror(errno)); 87 88 cap_rights_init(&rights); 89 90 if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS) 91 fatal("can't limit stdin: %m"); 92 if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS) 93 fatal("can't limit stdout: %m"); 94 if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS) 95 fatal("can't limit stderr: %m"); 96 97 cap_rights_init(&rights, CAP_READ, CAP_WRITE); 98 if (cap_rights_limit(box->m_recvfd, &rights) < 0 && 99 errno != ENOSYS) 100 fatal("%s: failed to limit the network socket", __func__); 101 cap_rights_init(&rights, CAP_WRITE); 102 if (cap_rights_limit(box->m_log_sendfd, &rights) < 0 && 103 errno != ENOSYS) 104 fatal("%s: failed to limit the logging socket", __func__); 105 if (cap_enter() < 0 && errno != ENOSYS) 106 fatal("%s: failed to enter capability mode", __func__); 107 108 } 109 110 #endif /* SANDBOX_CAPSICUM */ 111