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/*
* Copyright (c) 2011 Dag-Erling Smorgrav
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#ifdef SANDBOX_CAPSICUM
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/capability.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "log.h"
#include "monitor.h"
#include "ssh-sandbox.h"
#include "xmalloc.h"
/*
* Capsicum sandbox that sets zero nfiles, nprocs and filesize rlimits,
* limits rights on stdout, stdin, stderr, monitor and switches to
* capability mode.
*/
struct ssh_sandbox {
struct monitor *monitor;
pid_t child_pid;
};
struct ssh_sandbox *
ssh_sandbox_init(struct monitor *monitor)
{
struct ssh_sandbox *box;
/*
* Strictly, we don't need to maintain any state here but we need
* to return non-NULL to satisfy the API.
*/
debug3("%s: preparing capsicum sandbox", __func__);
box = xcalloc(1, sizeof(*box));
box->monitor = monitor;
box->child_pid = 0;
return box;
}
void
ssh_sandbox_child(struct ssh_sandbox *box)
{
struct rlimit rl_zero;
cap_rights_t rights;
rl_zero.rlim_cur = rl_zero.rlim_max = 0;
if (setrlimit(RLIMIT_FSIZE, &rl_zero) == -1)
fatal("%s: setrlimit(RLIMIT_FSIZE, { 0, 0 }): %s",
__func__, strerror(errno));
#ifndef SANDBOX_SKIP_RLIMIT_NOFILE
if (setrlimit(RLIMIT_NOFILE, &rl_zero) == -1)
fatal("%s: setrlimit(RLIMIT_NOFILE, { 0, 0 }): %s",
__func__, strerror(errno));
#endif
if (setrlimit(RLIMIT_NPROC, &rl_zero) == -1)
fatal("%s: setrlimit(RLIMIT_NPROC, { 0, 0 }): %s",
__func__, strerror(errno));
cap_rights_init(&rights);
if (cap_rights_limit(STDIN_FILENO, &rights) < 0 && errno != ENOSYS)
fatal("can't limit stdin: %m");
if (cap_rights_limit(STDOUT_FILENO, &rights) < 0 && errno != ENOSYS)
fatal("can't limit stdout: %m");
if (cap_rights_limit(STDERR_FILENO, &rights) < 0 && errno != ENOSYS)
fatal("can't limit stderr: %m");
cap_rights_init(&rights, CAP_READ, CAP_WRITE);
if (cap_rights_limit(box->monitor->m_recvfd, &rights) < 0 &&
errno != ENOSYS)
fatal("%s: failed to limit the network socket", __func__);
cap_rights_init(&rights, CAP_WRITE);
if (cap_rights_limit(box->monitor->m_log_sendfd, &rights) < 0 &&
errno != ENOSYS)
fatal("%s: failed to limit the logging socket", __func__);
if (cap_enter() < 0 && errno != ENOSYS)
fatal("%s: failed to enter capability mode", __func__);
}
void
ssh_sandbox_parent_finish(struct ssh_sandbox *box)
{
free(box);
debug3("%s: finished", __func__);
}
void
ssh_sandbox_parent_preauth(struct ssh_sandbox *box, pid_t child_pid)
{
box->child_pid = child_pid;
}
#endif /* SANDBOX_CAPSICUM */