/*

   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

#if defined(HAVE_GRP_H)

#include <grp.h> /* setgroups() */

#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);

}