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samba-mirror/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"
#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 <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)
#define bool int
#endif
/* are we running as non-root? This is used by the regresison 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) {
initial_uid = geteuid();
initial_gid = getegid();
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;
}
/****************************************************************************
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 USE_SETRESUID
setresuid(0,0,0);
#endif
#if USE_SETEUID
seteuid(0);
#endif
#if USE_SETREUID
setreuid(0, 0);
#endif
#if USE_SETUIDX
setuidx(ID_EFFECTIVE, 0);
setuidx(ID_REAL, 0);
#endif
/* this is needed on some systems */
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 USE_SETRESUID
setresgid(0,0,0);
#endif
#if USE_SETREUID
setregid(0,0);
#endif
#if USE_SETEUID
setegid(0);
#endif
#if USE_SETUIDX
setgidx(ID_EFFECTIVE, 0);
setgidx(ID_REAL, 0);
#endif
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 USE_SETRESUID
/* Set the effective as well as the real uid. */
if (setresuid(uid,uid,-1) == -1) {
if (errno == EAGAIN) {
DEBUG(0, ("setresuid failed with EAGAIN. uid(%d) "
"might be over its NPROC limit\n",
(int)uid));
}
}
#endif
#if USE_SETREUID
setreuid(-1,uid);
#endif
#if USE_SETEUID
seteuid(uid);
#endif
#if USE_SETUIDX
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 USE_SETRESUID
setresgid(-1,gid,-1);
#endif
#if USE_SETREUID
setregid(-1,gid);
#endif
#if USE_SETEUID
setegid(gid);
#endif
#if USE_SETUIDX
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 USE_SETRESUID
setresuid(saved_ruid, saved_euid, -1);
#elif USE_SETREUID
setreuid(saved_ruid, -1);
setreuid(-1,saved_euid);
#elif USE_SETUIDX
setuidx(ID_REAL, saved_ruid);
setuidx(ID_EFFECTIVE, saved_euid);
#else
set_effective_uid(saved_euid);
if (getuid() != saved_ruid)
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 USE_SETRESUID
setresgid(saved_rgid, saved_egid, -1);
#elif USE_SETREUID
setregid(saved_rgid, -1);
setregid(-1,saved_egid);
#elif USE_SETUIDX
setgidx(ID_REAL, saved_rgid);
setgidx(ID_EFFECTIVE, saved_egid);
#else
set_effective_gid(saved_egid);
if (getgid() != saved_rgid)
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 USE_SETRESUID
setresuid(geteuid(), -1, -1);
#endif
#if USE_SETREUID
setreuid(0, 0);
setreuid(uid, -1);
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 USE_SETRESUID
setresgid(gid,gid,gid);
setgid(gid);
setresuid(uid,uid,uid);
setuid(uid);
#endif
#if USE_SETREUID
setregid(gid,gid);
setgid(gid);
setreuid(uid,uid);
setuid(uid);
#endif
#if USE_SETEUID
setegid(gid);
setgid(gid);
setuid(uid);
seteuid(uid);
setuid(uid);
#endif
#if USE_SETUIDX
setgidx(ID_REAL, gid);
setgidx(ID_EFFECTIVE, gid);
setgid(gid);
setuidx(ID_REAL, uid);
setuidx(ID_EFFECTIVE, uid);
setuid(uid);
#endif
assert_uid(uid, uid);
assert_gid(gid, gid);
}
#ifdef AUTOCONF_TEST
/****************************************************************************
this function just checks that we don't get ENOSYS back
****************************************************************************/
static int have_syscall(void)
{
errno = 0;
#if USE_SETRESUID
setresuid(-1,-1,-1);
#endif
#if USE_SETREUID
setreuid(-1,-1);
#endif
#if USE_SETEUID
seteuid(-1);
#endif
#if USE_SETUIDX
setuidx(ID_EFFECTIVE, -1);
#endif
if (errno == ENOSYS) return -1;
return 0;
}
main()
{
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);
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);
}