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