/*- * 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. */ #include <config/config.h> #include <sys/param.h> #ifdef HAVE_JAIL #include <sys/jail.h> #endif #ifdef HAVE_CAP_ENTER #include <sys/capsicum.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); }