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__RCSID("$FreeBSD$"); 19 20#ifdef SANDBOX_CAPSICUM 21 22#include <sys/types.h> 23#include <sys/param.h> 24#include <sys/time.h> 25#include <sys/resource.h> 26#include <sys/capsicum.h> 27 28#include <errno.h> 29#include <stdarg.h> 30#include <stdio.h> 31#include <stdlib.h> 32#include <string.h> 33#include <unistd.h> 34#include <capsicum_helpers.h> 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 47struct ssh_sandbox { 48 struct monitor *monitor; 49 pid_t child_pid; 50}; 51 52struct ssh_sandbox * 53ssh_sandbox_init(struct monitor *monitor) 54{ 55 struct ssh_sandbox *box; 56 57 /* 58 * Strictly, we don't need to maintain any state here but we need 59 * to return non-NULL to satisfy the API. 60 */ 61 debug3("%s: preparing capsicum sandbox", __func__); 62 box = xcalloc(1, sizeof(*box)); 63 box->monitor = monitor; 64 box->child_pid = 0; 65 66 return box; 67} 68 69void 70ssh_sandbox_child(struct ssh_sandbox *box) 71{ 72 struct rlimit rl_zero; 73 cap_rights_t rights; 74 75 caph_cache_tzdata(); 76 77 rl_zero.rlim_cur = rl_zero.rlim_max = 0; 78 79 if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1) 80 fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s", 81 __func__, strerror(errno)); 82#ifndef SANDBOX_SKIP_RLIMIT_NOFILE 83 if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1) 84 fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s", 85 __func__, strerror(errno)); 86#endif 87 if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1) 88 fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s", 89 __func__, strerror(errno)); 90 91 cap_rights_init(&rights); 92 93 if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS) 94 fatal("can't limit stdin: %m"); 95 if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS) 96 fatal("can't limit stdout: %m"); 97 if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS) 98 fatal("can't limit stderr: %m"); 99 100 cap_rights_init(&rights, CAP_READ, CAP_WRITE); 101 if (cap_rights_limit(box->monitor->m_recvfd, &rights) < 0 && 102 errno != ENOSYS) 103 fatal("%s: failed to limit the network socket", __func__); 104 cap_rights_init(&rights, CAP_WRITE); 105 if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) < 0 && 106 errno != ENOSYS) 107 fatal("%s: failed to limit the logging socket", __func__); 108 if (cap_enter() < 0 && errno != ENOSYS) 109 fatal("%s: failed to enter capability mode", __func__); 110 111} 112 113void 114ssh_sandbox_parent_finish(struct ssh_sandbox *box) 115{ 116 free(box); 117 debug3("%s: finished", __func__); 118} 119 120void 121ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid) 122{ 123 box->child_pid = child_pid; 124} 125 126#endif /* SANDBOX_CAPSICUM */ 127