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/*-
* Copyright (c) 2012 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Pawel Jakub Dawidek under sponsorship from
* the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $P4: //depot/projects/trustedbsd/openbsm/bin/auditdistd/sandbox.c#3 $
*/
#include <config/config.h>
#include <sys/param.h>
#ifdef HAVE_JAIL
#include <sys/jail.h>
#endif
#ifdef HAVE_CAP_ENTER
#include <sys/capability.h>
#endif
#include <errno.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include "pjdlog.h"
#include "sandbox.h"
static int
groups_compare(const void *grp0, const void *grp1)
{
gid_t gr0 = *(const gid_t *)grp0;
gid_t gr1 = *(const gid_t *)grp1;
return (gr0 <= gr1 ? (gr0 < gr1 ? -1 : 0) : 1);
}
int
sandbox(const char *user, bool capsicum, const char *fmt, ...)
{
#ifdef HAVE_JAIL
struct jail jailst;
char *jailhost;
va_list ap;
#endif
struct passwd *pw;
uid_t ruid, euid;
gid_t rgid, egid;
#ifdef HAVE_GETRESUID
uid_t suid;
#endif
#ifdef HAVE_GETRESGID
gid_t sgid;
#endif
gid_t *groups, *ggroups;
bool jailed;
int ngroups, ret;
PJDLOG_ASSERT(user != NULL);
PJDLOG_ASSERT(fmt != NULL);
ret = -1;
groups = NULL;
ggroups = NULL;
/*
* According to getpwnam(3) we have to clear errno before calling the
* function to be able to distinguish between an error and missing
* entry (with is not treated as error by getpwnam(3)).
*/
errno = 0;
pw = getpwnam(user);
if (pw == NULL) {
if (errno != 0) {
pjdlog_errno(LOG_ERR,
"Unable to find info about '%s' user", user);
goto out;
} else {
pjdlog_error("'%s' user doesn't exist.", user);
errno = ENOENT;
goto out;
}
}
ngroups = sysconf(_SC_NGROUPS_MAX);
if (ngroups == -1) {
pjdlog_errno(LOG_WARNING,
"Unable to obtain maximum number of groups");
ngroups = NGROUPS_MAX;
}
ngroups++; /* For base gid. */
groups = malloc(sizeof(groups[0]) * ngroups);
if (groups == NULL) {
pjdlog_error("Unable to allocate memory for %d groups.",
ngroups);
goto out;
}
if (getgrouplist(user, pw->pw_gid, groups, &ngroups) == -1) {
pjdlog_error("Unable to obtain groups of user %s.", user);
goto out;
}
#ifdef HAVE_JAIL
va_start(ap, fmt);
(void)vasprintf(&jailhost, fmt, ap);
va_end(ap);
if (jailhost == NULL) {
pjdlog_error("Unable to allocate memory for jail host name.");
goto out;
}
bzero(&jailst, sizeof(jailst));
jailst.version = JAIL_API_VERSION;
jailst.path = pw->pw_dir;
jailst.hostname = jailhost;
if (jail(&jailst) >= 0) {
jailed = true;
} else {
jailed = false;
pjdlog_errno(LOG_WARNING,
"Unable to jail to directory %s", pw->pw_dir);
}
free(jailhost);
#else /* !HAVE_JAIL */
jailed = false;
#endif /* !HAVE_JAIL */
if (!jailed) {
if (chroot(pw->pw_dir) == -1) {
pjdlog_errno(LOG_ERR,
"Unable to change root directory to %s",
pw->pw_dir);
goto out;
}
}
PJDLOG_VERIFY(chdir("/") == 0);
if (setgroups(ngroups, groups) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set groups");
goto out;
}
if (setgid(pw->pw_gid) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set gid to %u",
(unsigned int)pw->pw_gid);
goto out;
}
if (setuid(pw->pw_uid) == -1) {
pjdlog_errno(LOG_ERR, "Unable to set uid to %u",
(unsigned int)pw->pw_uid);
goto out;
}
#ifdef HAVE_CAP_ENTER
if (capsicum) {
capsicum = (cap_enter() == 0);
if (!capsicum) {
pjdlog_common(LOG_DEBUG, 1, errno,
"Unable to sandbox using capsicum");
}
}
#else /* !HAVE_CAP_ENTER */
capsicum = false;
#endif /* !HAVE_CAP_ENTER */
/*
* Better be sure that everything succeeded.
*/
#ifdef HAVE_GETRESUID
PJDLOG_VERIFY(getresuid(&ruid, &euid, &suid) == 0);
PJDLOG_VERIFY(suid == pw->pw_uid);
#else
ruid = getuid();
euid = geteuid();
#endif
PJDLOG_VERIFY(ruid == pw->pw_uid);
PJDLOG_VERIFY(euid == pw->pw_uid);
#ifdef HAVE_GETRESGID
PJDLOG_VERIFY(getresgid(&rgid, &egid, &sgid) == 0);
PJDLOG_VERIFY(sgid == pw->pw_gid);
#else
rgid = getgid();
egid = getegid();
#endif
PJDLOG_VERIFY(rgid == pw->pw_gid);
PJDLOG_VERIFY(egid == pw->pw_gid);
PJDLOG_VERIFY(getgroups(0, NULL) == ngroups);
ggroups = malloc(sizeof(ggroups[0]) * ngroups);
if (ggroups == NULL) {
pjdlog_error("Unable to allocate memory for %d groups.",
ngroups);
goto out;
}
PJDLOG_VERIFY(getgroups(ngroups, ggroups) == ngroups);
qsort(groups, (size_t)ngroups, sizeof(groups[0]), groups_compare);
qsort(ggroups, (size_t)ngroups, sizeof(ggroups[0]), groups_compare);
PJDLOG_VERIFY(bcmp(groups, ggroups, sizeof(groups[0]) * ngroups) == 0);
pjdlog_debug(1,
"Privileges successfully dropped using %s%s+setgid+setuid.",
capsicum ? "capsicum+" : "", jailed ? "jail" : "chroot");
ret = 0;
out:
if (groups != NULL)
free(groups);
if (ggroups != NULL)
free(ggroups);
return (ret);
}
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