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https://github.com/samba-team/samba.git
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8b45a42bc8
Signed-off-by: Volker Lendecke <vl@samba.org> Reviewed-by: Jeremy Allison <jra@samba.org>
599 lines
14 KiB
C
599 lines
14 KiB
C
/*
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Unix SMB/CIFS implementation.
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Copyright (C) Jeremy Allison 1998.
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rewritten for version 2.0.6 by Tridge
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef AUTOCONF_TEST
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#include "includes.h"
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#include "system/passwd.h" /* uid_wrapper */
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#include "../lib/util/setid.h"
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#else
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/* we are running this code in autoconf test mode to see which type of setuid
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function works */
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#if defined(HAVE_UNISTD_H)
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#include <unistd.h>
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#endif
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#include <stdbool.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <sys/types.h>
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#include <errno.h>
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#ifdef HAVE_SYS_PRIV_H
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#include <sys/priv.h>
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#endif
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#ifdef HAVE_SYS_ID_H
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#include <sys/id.h>
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#endif
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#define DEBUG(x, y) printf y
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#define smb_panic(x) exit(1)
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#endif
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/* are we running as non-root? This is used by the regresison test code,
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and potentially also for sites that want non-root smbd */
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static uid_t initial_uid;
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static gid_t initial_gid;
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/****************************************************************************
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remember what uid we got started as - this allows us to run correctly
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as non-root while catching trapdoor systems
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****************************************************************************/
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void sec_init(void)
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{
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static int initialized;
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if (!initialized) {
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#ifndef AUTOCONF_TEST
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if (uid_wrapper_enabled()) {
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setenv("UID_WRAPPER_MYUID", "1", 1);
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}
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#endif
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initial_uid = geteuid();
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initial_gid = getegid();
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#ifndef AUTOCONF_TEST
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if (uid_wrapper_enabled()) {
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unsetenv("UID_WRAPPER_MYUID");
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}
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#endif
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initialized = 1;
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}
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}
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/****************************************************************************
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some code (eg. winbindd) needs to know what uid we started as
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****************************************************************************/
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uid_t sec_initial_uid(void)
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{
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return initial_uid;
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}
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/****************************************************************************
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some code (eg. winbindd, profiling shm) needs to know what gid we started as
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****************************************************************************/
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gid_t sec_initial_gid(void)
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{
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return initial_gid;
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}
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/**
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* @brief Check if we are running in root mode.
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*
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* @return Return whether Samba has root privileges
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*/
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bool root_mode(void)
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{
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uid_t euid;
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euid = geteuid();
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#ifndef AUTOCONF_TEST
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if (uid_wrapper_enabled()) {
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return (euid == initial_uid || euid == (uid_t)0);
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}
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#endif
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return (initial_uid == euid);
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}
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/****************************************************************************
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are we running in non-root mode?
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****************************************************************************/
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bool non_root_mode(void)
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{
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return (initial_uid != (uid_t)0);
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}
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/****************************************************************************
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abort if we haven't set the uid correctly
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****************************************************************************/
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static void assert_uid(uid_t ruid, uid_t euid)
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{
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if ((euid != (uid_t)-1 && geteuid() != euid) ||
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(ruid != (uid_t)-1 && getuid() != ruid)) {
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if (!non_root_mode()) {
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DEBUG(0,("Failed to set uid privileges to (%d,%d) now set to (%d,%d)\n",
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(int)ruid, (int)euid,
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(int)getuid(), (int)geteuid()));
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smb_panic("failed to set uid\n");
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exit(1);
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}
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}
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}
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/****************************************************************************
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abort if we haven't set the gid correctly
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****************************************************************************/
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static void assert_gid(gid_t rgid, gid_t egid)
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{
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if ((egid != (gid_t)-1 && getegid() != egid) ||
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(rgid != (gid_t)-1 && getgid() != rgid)) {
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if (!non_root_mode()) {
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DEBUG(0,("Failed to set gid privileges to (%d,%d) now set to (%d,%d) uid=(%d,%d)\n",
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(int)rgid, (int)egid,
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(int)getgid(), (int)getegid(),
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(int)getuid(), (int)geteuid()));
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smb_panic("failed to set gid\n");
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exit(1);
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}
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}
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}
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/****************************************************************************
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Gain root privilege before doing something.
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We want to end up with ruid==euid==0
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****************************************************************************/
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void gain_root_privilege(void)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresuid(0,0,0);
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#endif
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#if USE_SETEUID
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samba_seteuid(0);
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#endif
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#if USE_SETREUID
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samba_setreuid(0, 0);
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#endif
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#if USE_SETUIDX
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samba_setuidx(ID_EFFECTIVE, 0);
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samba_setuidx(ID_REAL, 0);
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#endif
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/* this is needed on some systems */
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samba_setuid(0);
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assert_uid(0, 0);
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}
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/****************************************************************************
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Ensure our real and effective groups are zero.
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we want to end up with rgid==egid==0
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****************************************************************************/
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void gain_root_group_privilege(void)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresgid(0,0,0);
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#endif
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#if USE_SETREUID
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samba_setregid(0,0);
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#endif
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#if USE_SETEUID
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samba_setegid(0);
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#endif
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#if USE_SETUIDX
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samba_setgidx(ID_EFFECTIVE, 0);
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samba_setgidx(ID_REAL, 0);
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#endif
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samba_setgid(0);
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assert_gid(0, 0);
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}
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/****************************************************************************
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Set effective uid, and possibly the real uid too.
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We want to end up with either:
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ruid==uid and euid==uid
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or
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ruid==0 and euid==uid
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depending on what the local OS will allow us to regain root from.
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****************************************************************************/
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void set_effective_uid(uid_t uid)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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/* Set the effective as well as the real uid. */
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if (samba_setresuid(uid,uid,-1) == -1) {
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if (errno == EAGAIN) {
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DEBUG(0, ("samba_setresuid failed with EAGAIN. uid(%d) "
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"might be over its NPROC limit\n",
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(int)uid));
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}
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}
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#endif
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#if USE_SETREUID
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samba_setreuid(-1,uid);
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#endif
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#if USE_SETEUID
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samba_seteuid(uid);
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#endif
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#if USE_SETUIDX
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samba_setuidx(ID_EFFECTIVE, uid);
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#endif
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assert_uid(-1, uid);
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}
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/****************************************************************************
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Set *only* the effective gid.
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we want to end up with rgid==0 and egid==gid
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****************************************************************************/
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void set_effective_gid(gid_t gid)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresgid(-1,gid,-1);
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#endif
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#if USE_SETREUID
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samba_setregid(-1,gid);
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#endif
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#if USE_SETEUID
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samba_setegid(gid);
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#endif
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#if USE_SETUIDX
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samba_setgidx(ID_EFFECTIVE, gid);
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#endif
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assert_gid(-1, gid);
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}
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static uid_t saved_euid, saved_ruid;
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static gid_t saved_egid, saved_rgid;
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/****************************************************************************
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save the real and effective uid for later restoration. Used by the quotas
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code
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****************************************************************************/
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void save_re_uid(void)
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{
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saved_ruid = getuid();
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saved_euid = geteuid();
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}
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/****************************************************************************
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and restore them!
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****************************************************************************/
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void restore_re_uid_fromroot(void)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresuid(saved_ruid, saved_euid, -1);
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#elif USE_SETREUID
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samba_setreuid(saved_ruid, -1);
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samba_setreuid(-1,saved_euid);
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#elif USE_SETUIDX
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samba_setuidx(ID_REAL, saved_ruid);
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samba_setuidx(ID_EFFECTIVE, saved_euid);
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#else
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set_effective_uid(saved_euid);
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if (getuid() != saved_ruid)
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samba_setuid(saved_ruid);
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set_effective_uid(saved_euid);
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#endif
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assert_uid(saved_ruid, saved_euid);
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}
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void restore_re_uid(void)
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{
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set_effective_uid(0);
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restore_re_uid_fromroot();
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}
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/****************************************************************************
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save the real and effective gid for later restoration. Used by the
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getgroups code
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****************************************************************************/
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void save_re_gid(void)
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{
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saved_rgid = getgid();
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saved_egid = getegid();
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}
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/****************************************************************************
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and restore them!
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****************************************************************************/
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void restore_re_gid(void)
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{
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresgid(saved_rgid, saved_egid, -1);
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#elif USE_SETREUID
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samba_setregid(saved_rgid, -1);
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samba_setregid(-1,saved_egid);
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#elif USE_SETUIDX
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samba_setgidx(ID_REAL, saved_rgid);
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samba_setgidx(ID_EFFECTIVE, saved_egid);
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#else
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set_effective_gid(saved_egid);
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if (getgid() != saved_rgid)
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samba_setgid(saved_rgid);
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set_effective_gid(saved_egid);
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#endif
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assert_gid(saved_rgid, saved_egid);
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}
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/****************************************************************************
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set the real AND effective uid to the current effective uid in a way that
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allows root to be regained.
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This is only possible on some platforms.
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****************************************************************************/
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int set_re_uid(void)
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{
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uid_t uid = geteuid();
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresuid(uid, uid, -1);
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#endif
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#if USE_SETREUID
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samba_setreuid(0, 0);
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samba_setreuid(uid, -1);
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samba_setreuid(-1, uid);
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#endif
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#if USE_SETEUID
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/* can't be done */
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return -1;
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#endif
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#if USE_SETUIDX
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/* can't be done */
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return -1;
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#endif
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assert_uid(uid, uid);
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return 0;
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}
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/****************************************************************************
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Become the specified uid and gid - permanently !
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there should be no way back if possible
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****************************************************************************/
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void become_user_permanently(uid_t uid, gid_t gid)
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{
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/*
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* First - gain root privilege. We do this to ensure
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* we can lose it again.
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*/
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gain_root_privilege();
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gain_root_group_privilege();
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresgid(gid,gid,gid);
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samba_setgid(gid);
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samba_setresuid(uid,uid,uid);
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samba_setuid(uid);
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#endif
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#if USE_SETREUID
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samba_setregid(gid,gid);
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samba_setgid(gid);
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samba_setreuid(uid,uid);
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samba_setuid(uid);
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#endif
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#if USE_SETEUID
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samba_setegid(gid);
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samba_setgid(gid);
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samba_setuid(uid);
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samba_seteuid(uid);
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samba_setuid(uid);
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#endif
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#if USE_SETUIDX
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samba_setgidx(ID_REAL, gid);
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samba_setgidx(ID_EFFECTIVE, gid);
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samba_setgid(gid);
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samba_setuidx(ID_REAL, uid);
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samba_setuidx(ID_EFFECTIVE, uid);
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samba_setuid(uid);
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#endif
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assert_uid(uid, uid);
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assert_gid(gid, gid);
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}
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#if defined(HAVE_LINUX_THREAD_CREDENTIALS) && defined(HAVE___THREAD)
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struct set_thread_credentials_cache {
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bool active;
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uid_t uid;
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gid_t gid;
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size_t setlen;
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uintptr_t gidset;
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};
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static __thread struct set_thread_credentials_cache cache;
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#endif
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/**********************************************************
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Function to set thread specific credentials. Leave
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saved-set uid/gid alone.Must be thread-safe code.
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**********************************************************/
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int set_thread_credentials(uid_t uid,
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gid_t gid,
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size_t setlen,
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const gid_t *gidset)
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{
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#if defined(HAVE_LINUX_THREAD_CREDENTIALS)
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/*
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* With Linux thread-specific credentials
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* we know we have setresuid/setresgid
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* available.
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*/
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#ifdef HAVE___THREAD
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if (cache.active &&
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cache.uid == uid &&
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cache.gid == gid &&
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cache.setlen == setlen &&
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(const gid_t *)cache.gidset == gidset)
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{
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return 0;
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}
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#endif /* HAVE___THREAD */
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/* Become root. */
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/* Set ru=0, eu=0 */
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if (samba_setresuid(0, 0, -1) != 0) {
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return -1;
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}
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/* Set our primary gid. */
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/* Set rg=gid, eg=gid */
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if (samba_setresgid(gid, gid, -1) != 0) {
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return -1;
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}
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/* Set extra groups list. */
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if (samba_setgroups(setlen, gidset) != 0) {
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return -1;
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}
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/* Become the requested user. */
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/* Set ru=uid, eu=uid */
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if (samba_setresuid(uid, uid, -1) != 0) {
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return -1;
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}
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if (geteuid() != uid || getuid() != uid ||
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getegid() != gid || getgid() != gid) {
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smb_panic("set_thread_credentials failed\n");
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return -1;
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}
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#ifdef HAVE___THREAD
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cache.active = true;
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cache.uid = uid;
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cache.gid = gid;
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cache.setlen = setlen;
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cache.gidset = (uintptr_t)gidset;
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#endif /* HAVE___THREAD */
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return 0;
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#else
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errno = ENOSYS;
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return -1;
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#endif
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}
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#ifdef AUTOCONF_TEST
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/****************************************************************************
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this function just checks that we don't get ENOSYS back
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****************************************************************************/
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static int have_syscall(void)
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{
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errno = 0;
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#if defined(USE_SETRESUID) || defined(HAVE_LINUX_THREAD_CREDENTIALS)
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samba_setresuid(-1,-1,-1);
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#endif
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#if USE_SETREUID
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samba_setreuid(-1,-1);
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#endif
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#if USE_SETEUID
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samba_seteuid(-1);
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#endif
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#if USE_SETUIDX
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samba_setuidx(ID_EFFECTIVE, -1);
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#endif
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if (errno == ENOSYS) {
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return -1;
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}
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return 0;
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}
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int main(void)
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{
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if (getuid() != 0) {
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#if (defined(AIX) && defined(USE_SETREUID))
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/* setreuid is badly broken on AIX 4.1, we avoid it completely */
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fprintf(stderr,"avoiding possibly broken setreuid\n");
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exit(1);
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#endif
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/* if not running as root then at least check to see if we get ENOSYS - this
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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);
|
|
}
|