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-rw-r--r--source3/lib/util_sec.c598
1 files changed, 598 insertions, 0 deletions
diff --git a/source3/lib/util_sec.c b/source3/lib/util_sec.c
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+/*
+ Unix SMB/CIFS implementation.
+ Copyright (C) Jeremy Allison 1998.
+ rewritten for version 2.0.6 by Tridge
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef AUTOCONF_TEST
+#include "includes.h"
+#include "system/passwd.h" /* uid_wrapper */
+#include "../lib/util/setid.h"
+
+#else
+/* we are running this code in autoconf test mode to see which type of setuid
+ function works */
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <errno.h>
+
+#ifdef HAVE_SYS_PRIV_H
+#include <sys/priv.h>
+#endif
+#ifdef HAVE_SYS_ID_H
+#include <sys/id.h>
+#endif
+
+#define DEBUG(x, y) printf y
+#define smb_panic(x) exit(1)
+#endif
+
+/* are we running as non-root? This is used by the regression test code,
+ and potentially also for sites that want non-root smbd */
+static uid_t initial_uid;
+static gid_t initial_gid;
+
+/****************************************************************************
+remember what uid we got started as - this allows us to run correctly
+as non-root while catching trapdoor systems
+****************************************************************************/
+
+void sec_init(void)
+{
+ static int initialized;
+
+ if (!initialized) {
+
+#ifndef AUTOCONF_TEST
+ if (uid_wrapper_enabled()) {
+ setenv("UID_WRAPPER_MYUID", "1", 1);
+ }
+#endif
+
+ initial_uid = geteuid();
+ initial_gid = getegid();
+
+#ifndef AUTOCONF_TEST
+ if (uid_wrapper_enabled()) {
+ unsetenv("UID_WRAPPER_MYUID");
+ }
+#endif
+
+ initialized = 1;
+ }
+}
+
+/****************************************************************************
+some code (eg. winbindd) needs to know what uid we started as
+****************************************************************************/
+uid_t sec_initial_uid(void)
+{
+ return initial_uid;
+}
+
+/****************************************************************************
+some code (eg. winbindd, profiling shm) needs to know what gid we started as
+****************************************************************************/
+gid_t sec_initial_gid(void)
+{
+ return initial_gid;
+}
+
+/**
+ * @brief Check if we are running in root mode.
+ *
+ * @return Return whether Samba has root privileges
+ */
+bool root_mode(void)
+{
+ uid_t euid;
+
+ euid = geteuid();
+
+#ifndef AUTOCONF_TEST
+ if (uid_wrapper_enabled()) {
+ return (euid == initial_uid || euid == (uid_t)0);
+ }
+#endif
+
+ return (initial_uid == euid);
+}
+
+/****************************************************************************
+are we running in non-root mode?
+****************************************************************************/
+bool non_root_mode(void)
+{
+ return (initial_uid != (uid_t)0);
+}
+
+/****************************************************************************
+abort if we haven't set the uid correctly
+****************************************************************************/
+static void assert_uid(uid_t ruid, uid_t euid)
+{
+ if ((euid != (uid_t)-1 && geteuid() != euid) ||
+ (ruid != (uid_t)-1 && getuid() != ruid)) {
+ if (!non_root_mode()) {
+ DEBUG(0,("Failed to set uid privileges to (%d,%d) now set to (%d,%d)\n",
+ (int)ruid, (int)euid,
+ (int)getuid(), (int)geteuid()));
+ smb_panic("failed to set uid\n");
+ exit(1);
+ }
+ }
+}
+
+/****************************************************************************
+abort if we haven't set the gid correctly
+****************************************************************************/
+static void assert_gid(gid_t rgid, gid_t egid)
+{
+ if ((egid != (gid_t)-1 && getegid() != egid) ||
+ (rgid != (gid_t)-1 && getgid() != rgid)) {
+ if (!non_root_mode()) {
+ DEBUG(0,("Failed to set gid privileges to (%d,%d) now set to (%d,%d) uid=(%d,%d)\n",
+ (int)rgid, (int)egid,
+ (int)getgid(), (int)getegid(),
+ (int)getuid(), (int)geteuid()));
+ smb_panic("failed to set gid\n");
+ exit(1);
+ }
+ }
+}
+
+/****************************************************************************
+ Gain root privilege before doing something.
+ We want to end up with ruid==euid==0
+****************************************************************************/
+void gain_root_privilege(void)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresuid(0,0,0);
+#endif
+
+#if USE_SETEUID
+ samba_seteuid(0);
+#endif
+
+#if USE_SETREUID
+ samba_setreuid(0, 0);
+#endif
+
+#if USE_SETUIDX
+ samba_setuidx(ID_EFFECTIVE, 0);
+ samba_setuidx(ID_REAL, 0);
+#endif
+
+ /* this is needed on some systems */
+ samba_setuid(0);
+
+ assert_uid(0, 0);
+}
+
+
+/****************************************************************************
+ Ensure our real and effective groups are zero.
+ we want to end up with rgid==egid==0
+****************************************************************************/
+void gain_root_group_privilege(void)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresgid(0,0,0);
+#endif
+
+#if USE_SETREUID
+ samba_setregid(0,0);
+#endif
+
+#if USE_SETEUID
+ samba_setegid(0);
+#endif
+
+#if USE_SETUIDX
+ samba_setgidx(ID_EFFECTIVE, 0);
+ samba_setgidx(ID_REAL, 0);
+#endif
+
+ samba_setgid(0);
+
+ assert_gid(0, 0);
+}
+
+
+/****************************************************************************
+ Set effective uid, and possibly the real uid too.
+ We want to end up with either:
+
+ ruid==uid and euid==uid
+
+ or
+
+ ruid==0 and euid==uid
+
+ depending on what the local OS will allow us to regain root from.
+****************************************************************************/
+void set_effective_uid(uid_t uid)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ /* Set the effective as well as the real uid. */
+ if (samba_setresuid(uid,uid,-1) == -1) {
+ if (errno == EAGAIN) {
+ DEBUG(0, ("samba_setresuid failed with EAGAIN. uid(%d) "
+ "might be over its NPROC limit\n",
+ (int)uid));
+ }
+ }
+#endif
+
+#if USE_SETREUID
+ samba_setreuid(-1,uid);
+#endif
+
+#if USE_SETEUID
+ samba_seteuid(uid);
+#endif
+
+#if USE_SETUIDX
+ samba_setuidx(ID_EFFECTIVE, uid);
+#endif
+
+ assert_uid(-1, uid);
+}
+
+/****************************************************************************
+ Set *only* the effective gid.
+ we want to end up with rgid==0 and egid==gid
+****************************************************************************/
+void set_effective_gid(gid_t gid)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresgid(-1,gid,-1);
+#endif
+
+#if USE_SETREUID
+ samba_setregid(-1,gid);
+#endif
+
+#if USE_SETEUID
+ samba_setegid(gid);
+#endif
+
+#if USE_SETUIDX
+ samba_setgidx(ID_EFFECTIVE, gid);
+#endif
+
+ assert_gid(-1, gid);
+}
+
+static uid_t saved_euid, saved_ruid;
+static gid_t saved_egid, saved_rgid;
+
+/****************************************************************************
+ save the real and effective uid for later restoration. Used by the quotas
+ code
+****************************************************************************/
+void save_re_uid(void)
+{
+ saved_ruid = getuid();
+ saved_euid = geteuid();
+}
+
+
+/****************************************************************************
+ and restore them!
+****************************************************************************/
+
+void restore_re_uid_fromroot(void)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresuid(saved_ruid, saved_euid, -1);
+#elif USE_SETREUID
+ samba_setreuid(saved_ruid, -1);
+ samba_setreuid(-1,saved_euid);
+#elif USE_SETUIDX
+ samba_setuidx(ID_REAL, saved_ruid);
+ samba_setuidx(ID_EFFECTIVE, saved_euid);
+#else
+ set_effective_uid(saved_euid);
+ if (getuid() != saved_ruid)
+ samba_setuid(saved_ruid);
+ set_effective_uid(saved_euid);
+#endif
+
+ assert_uid(saved_ruid, saved_euid);
+}
+
+void restore_re_uid(void)
+{
+ set_effective_uid(0);
+ restore_re_uid_fromroot();
+}
+
+/****************************************************************************
+ save the real and effective gid for later restoration. Used by the
+ getgroups code
+****************************************************************************/
+void save_re_gid(void)
+{
+ saved_rgid = getgid();
+ saved_egid = getegid();
+}
+
+/****************************************************************************
+ and restore them!
+****************************************************************************/
+void restore_re_gid(void)
+{
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresgid(saved_rgid, saved_egid, -1);
+#elif USE_SETREUID
+ samba_setregid(saved_rgid, -1);
+ samba_setregid(-1,saved_egid);
+#elif USE_SETUIDX
+ samba_setgidx(ID_REAL, saved_rgid);
+ samba_setgidx(ID_EFFECTIVE, saved_egid);
+#else
+ set_effective_gid(saved_egid);
+ if (getgid() != saved_rgid)
+ samba_setgid(saved_rgid);
+ set_effective_gid(saved_egid);
+#endif
+
+ assert_gid(saved_rgid, saved_egid);
+}
+
+
+/****************************************************************************
+ set the real AND effective uid to the current effective uid in a way that
+ allows root to be regained.
+ This is only possible on some platforms.
+****************************************************************************/
+int set_re_uid(void)
+{
+ uid_t uid = geteuid();
+
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresuid(uid, uid, -1);
+#endif
+
+#if USE_SETREUID
+ samba_setreuid(0, 0);
+ samba_setreuid(uid, -1);
+ samba_setreuid(-1, uid);
+#endif
+
+#if USE_SETEUID
+ /* can't be done */
+ return -1;
+#endif
+
+#if USE_SETUIDX
+ /* can't be done */
+ return -1;
+#endif
+
+ assert_uid(uid, uid);
+ return 0;
+}
+
+
+/****************************************************************************
+ Become the specified uid and gid - permanently !
+ there should be no way back if possible
+****************************************************************************/
+void become_user_permanently(uid_t uid, gid_t gid)
+{
+ /*
+ * First - gain root privilege. We do this to ensure
+ * we can lose it again.
+ */
+
+ gain_root_privilege();
+ gain_root_group_privilege();
+
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresgid(gid,gid,gid);
+ samba_setgid(gid);
+ samba_setresuid(uid,uid,uid);
+ samba_setuid(uid);
+#endif
+
+#if USE_SETREUID
+ samba_setregid(gid,gid);
+ samba_setgid(gid);
+ samba_setreuid(uid,uid);
+ samba_setuid(uid);
+#endif
+
+#if USE_SETEUID
+ samba_setegid(gid);
+ samba_setgid(gid);
+ samba_setuid(uid);
+ samba_seteuid(uid);
+ samba_setuid(uid);
+#endif
+
+#if USE_SETUIDX
+ samba_setgidx(ID_REAL, gid);
+ samba_setgidx(ID_EFFECTIVE, gid);
+ samba_setgid(gid);
+ samba_setuidx(ID_REAL, uid);
+ samba_setuidx(ID_EFFECTIVE, uid);
+ samba_setuid(uid);
+#endif
+
+ assert_uid(uid, uid);
+ assert_gid(gid, gid);
+}
+
+#if defined(HAVE_LINUX_THREAD_CREDENTIALS) && defined(HAVE___THREAD)
+ struct set_thread_credentials_cache {
+ bool active;
+ uid_t uid;
+ gid_t gid;
+ size_t setlen;
+ uintptr_t gidset;
+ };
+static __thread struct set_thread_credentials_cache cache;
+#endif
+
+/**********************************************************
+ Function to set thread specific credentials. Leave
+ saved-set uid/gid alone.Must be thread-safe code.
+**********************************************************/
+
+int set_thread_credentials(uid_t uid,
+ gid_t gid,
+ size_t setlen,
+ const gid_t *gidset)
+{
+#if defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ /*
+ * With Linux thread-specific credentials
+ * we know we have setresuid/setresgid
+ * available.
+ */
+#ifdef HAVE___THREAD
+ if (cache.active &&
+ cache.uid == uid &&
+ cache.gid == gid &&
+ cache.setlen == setlen &&
+ (const gid_t *)cache.gidset == gidset)
+ {
+ return 0;
+ }
+#endif /* HAVE___THREAD */
+
+ /* Become root. */
+ /* Set ru=0, eu=0 */
+ if (samba_setresuid(0, 0, -1) != 0) {
+ return -1;
+ }
+ /* Set our primary gid. */
+ /* Set rg=gid, eg=gid */
+ if (samba_setresgid(gid, gid, -1) != 0) {
+ return -1;
+ }
+ /* Set extra groups list. */
+ if (samba_setgroups(setlen, gidset) != 0) {
+ return -1;
+ }
+ /* Become the requested user. */
+ /* Set ru=uid, eu=uid */
+ if (samba_setresuid(uid, uid, -1) != 0) {
+ return -1;
+ }
+ if (geteuid() != uid || getuid() != uid ||
+ getegid() != gid || getgid() != gid) {
+ smb_panic("set_thread_credentials failed\n");
+ return -1;
+ }
+
+#ifdef HAVE___THREAD
+ cache.active = true;
+ cache.uid = uid;
+ cache.gid = gid;
+ cache.setlen = setlen;
+ cache.gidset = (uintptr_t)gidset;
+#endif /* HAVE___THREAD */
+
+ return 0;
+#else
+ errno = ENOSYS;
+ return -1;
+#endif
+}
+
+#ifdef AUTOCONF_TEST
+
+/****************************************************************************
+this function just checks that we don't get ENOSYS back
+****************************************************************************/
+static int have_syscall(void)
+{
+ errno = 0;
+
+#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
+ samba_setresuid(-1,-1,-1);
+#endif
+
+#if USE_SETREUID
+ samba_setreuid(-1,-1);
+#endif
+
+#if USE_SETEUID
+ samba_seteuid(-1);
+#endif
+
+#if USE_SETUIDX
+ samba_setuidx(ID_EFFECTIVE, -1);
+#endif
+
+ if (errno == ENOSYS) {
+ return -1;
+ }
+ return 0;
+}
+
+int main(void)
+{
+ if (getuid() != 0) {
+#if (defined(AIX) && defined(USE_SETREUID))
+ /* setreuid is badly broken on AIX 4.1, we avoid it completely */
+ fprintf(stderr,"avoiding possibly broken setreuid\n");
+ exit(1);
+#endif
+
+ /* if not running as root then at least check to see if we get ENOSYS - this
+ handles Linux 2.0.x with glibc 2.1 */
+ fprintf(stderr,"not running as root: checking for ENOSYS\n");
+ exit(have_syscall());
+ }
+
+ gain_root_privilege();
+ gain_root_group_privilege();
+ set_effective_gid(1);
+ set_effective_uid(1);
+ save_re_uid();
+ restore_re_uid();
+ gain_root_privilege();
+ gain_root_group_privilege();
+ become_user_permanently(1, 1);
+ samba_setuid(0);
+ if (getuid() == 0) {
+ fprintf(stderr,"uid not set permanently\n");
+ exit(1);
+ }
+
+ printf("OK\n");
+
+ exit(0);
+}
+#endif
+
+/****************************************************************************
+Check if we are setuid root. Used in libsmb and smbpasswd paranoia checks.
+****************************************************************************/
+bool is_setuid_root(void)
+{
+ return (geteuid() == (uid_t)0) && (getuid() != (uid_t)0);
+}