samba-mirror/source3/lib/util_sec.c

/*
   Unix SMB/Netbios implementation.
   Version 2.0
   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef AUTOCONF_TEST
#include "includes.h"
extern int DEBUGLEVEL;
#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)
#endif

/****************************************************************************
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)) {
		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)) {
		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 *only* the effective uid.
 we want to end up with ruid==0 and euid==uid
****************************************************************************/
void set_effective_uid(uid_t uid)
{
#if USE_SETRESUID
	setresuid(-1,uid,-1);
#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;

/****************************************************************************
 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(void)
{
	set_effective_uid(0);

#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);
}

/****************************************************************************
 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