blob: e10bad7e83df5bdb3dbab3073adb7a1e2105839a [file] [log] [blame]
Damien Miller868ea1e2014-01-17 16:47:04 +11001/*
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>
Darren Tuckerdd9d9b32017-08-28 16:48:27 +100025#include <sys/capsicum.h>
Damien Miller868ea1e2014-01-17 16:47:04 +110026
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
45struct ssh_sandbox {
46 struct monitor *monitor;
47 pid_t child_pid;
48};
49
50struct ssh_sandbox *
51ssh_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
67void
68ssh_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));
Damien Miller2035b222014-01-26 09:39:53 +110078#ifndef SANDBOX_SKIP_RLIMIT_NOFILE
Damien Miller868ea1e2014-01-17 16:47:04 +110079 if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1)
80 fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s",
81 __func__, strerror(errno));
Damien Miller2035b222014-01-26 09:39:53 +110082#endif
Damien Miller868ea1e2014-01-17 16:47:04 +110083 if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1)
84 fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s",
85 __func__, strerror(errno));
86
87 cap_rights_init(&rights);
88
89 if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS)
90 fatal("can't limit stdin: %m");
91 if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS)
Darren Tucker841f7da2014-01-18 22:12:15 +110092 fatal("can't limit stdout: %m");
Damien Miller868ea1e2014-01-17 16:47:04 +110093 if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS)
Darren Tucker841f7da2014-01-18 22:12:15 +110094 fatal("can't limit stderr: %m");
Damien Miller868ea1e2014-01-17 16:47:04 +110095
96 cap_rights_init(&rights, CAP_READ, CAP_WRITE);
Damien Millera0959da2014-02-05 10:33:45 +110097 if (cap_rights_limit(box->monitor->m_recvfd, &rights) < 0 &&
98 errno != ENOSYS)
Damien Miller868ea1e2014-01-17 16:47:04 +110099 fatal("%s: failed to limit the network socket", __func__);
100 cap_rights_init(&rights, CAP_WRITE);
Damien Millera0959da2014-02-05 10:33:45 +1100101 if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) < 0 &&
102 errno != ENOSYS)
Damien Miller868ea1e2014-01-17 16:47:04 +1100103 fatal("%s: failed to limit the logging socket", __func__);
Darren Tucker841f7da2014-01-18 22:12:15 +1100104 if (cap_enter() < 0 && errno != ENOSYS)
Damien Miller868ea1e2014-01-17 16:47:04 +1100105 fatal("%s: failed to enter capability mode", __func__);
106
107}
108
109void
110ssh_sandbox_parent_finish(struct ssh_sandbox *box)
111{
112 free(box);
113 debug3("%s: finished", __func__);
114}
115
116void
117ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
118{
119 box->child_pid = child_pid;
120}
121
122#endif /* SANDBOX_CAPSICUM */