Damien Miller | 868ea1e | 2014-01-17 16:47:04 +1100 | [diff] [blame] | 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/param.h> |
| 23 | #include <sys/time.h> |
| 24 | #include <sys/resource.h> |
| 25 | #include <sys/capability.h> |
| 26 | |
| 27 | #include <errno.h> |
| 28 | #include <stdarg.h> |
| 29 | #include <stdio.h> |
| 30 | #include <stdlib.h> |
| 31 | #include <string.h> |
| 32 | #include <unistd.h> |
| 33 | |
| 34 | #include "log.h" |
| 35 | #include "monitor.h" |
| 36 | #include "ssh-sandbox.h" |
| 37 | #include "xmalloc.h" |
| 38 | |
| 39 | /* |
| 40 | * Capsicum sandbox that sets zero nfiles, nprocs and filesize rlimits, |
| 41 | * limits rights on stdout, stdin, stderr, monitor and switches to |
| 42 | * capability mode. |
| 43 | */ |
| 44 | |
| 45 | struct ssh_sandbox { |
| 46 | struct monitor *monitor; |
| 47 | pid_t child_pid; |
| 48 | }; |
| 49 | |
| 50 | struct ssh_sandbox * |
| 51 | ssh_sandbox_init(struct monitor *monitor) |
| 52 | { |
| 53 | struct ssh_sandbox *box; |
| 54 | |
| 55 | /* |
| 56 | * Strictly, we don't need to maintain any state here but we need |
| 57 | * to return non-NULL to satisfy the API. |
| 58 | */ |
| 59 | debug3("%s: preparing capsicum sandbox", __func__); |
| 60 | box = xcalloc(1, sizeof(*box)); |
| 61 | box->monitor = monitor; |
| 62 | box->child_pid = 0; |
| 63 | |
| 64 | return box; |
| 65 | } |
| 66 | |
| 67 | void |
| 68 | ssh_sandbox_child(struct ssh_sandbox *box) |
| 69 | { |
| 70 | struct rlimit rl_zero; |
| 71 | cap_rights_t rights; |
| 72 | |
| 73 | rl_zero.rlim_cur = rl_zero.rlim_max = 0; |
| 74 | |
| 75 | if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1) |
| 76 | fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s", |
| 77 | __func__, strerror(errno)); |
| 78 | if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1) |
| 79 | fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s", |
| 80 | __func__, strerror(errno)); |
| 81 | if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1) |
| 82 | fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s", |
| 83 | __func__, strerror(errno)); |
| 84 | |
| 85 | cap_rights_init(&rights); |
| 86 | |
| 87 | if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS) |
| 88 | fatal("can't limit stdin: %m"); |
| 89 | if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS) |
Darren Tucker | 841f7da | 2014-01-18 22:12:15 +1100 | [diff] [blame] | 90 | fatal("can't limit stdout: %m"); |
Damien Miller | 868ea1e | 2014-01-17 16:47:04 +1100 | [diff] [blame] | 91 | if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS) |
Darren Tucker | 841f7da | 2014-01-18 22:12:15 +1100 | [diff] [blame] | 92 | fatal("can't limit stderr: %m"); |
Damien Miller | 868ea1e | 2014-01-17 16:47:04 +1100 | [diff] [blame] | 93 | |
| 94 | cap_rights_init(&rights, CAP_READ, CAP_WRITE); |
| 95 | if (cap_rights_limit(box->monitor->m_recvfd, &rights) == -1) |
| 96 | fatal("%s: failed to limit the network socket", __func__); |
| 97 | cap_rights_init(&rights, CAP_WRITE); |
| 98 | if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) == -1) |
| 99 | fatal("%s: failed to limit the logging socket", __func__); |
Darren Tucker | 841f7da | 2014-01-18 22:12:15 +1100 | [diff] [blame] | 100 | if (cap_enter() < 0 && errno != ENOSYS) |
Damien Miller | 868ea1e | 2014-01-17 16:47:04 +1100 | [diff] [blame] | 101 | fatal("%s: failed to enter capability mode", __func__); |
| 102 | |
| 103 | } |
| 104 | |
| 105 | void |
| 106 | ssh_sandbox_parent_finish(struct ssh_sandbox *box) |
| 107 | { |
| 108 | free(box); |
| 109 | debug3("%s: finished", __func__); |
| 110 | } |
| 111 | |
| 112 | void |
| 113 | ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid) |
| 114 | { |
| 115 | box->child_pid = child_pid; |
| 116 | } |
| 117 | |
| 118 | #endif /* SANDBOX_CAPSICUM */ |