[openssh.git] / uidswap.c

/* $OpenBSD: uidswap.c,v 1.35 2006/08/03 03:34:42 deraadt Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Code for uid-swapping.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"

#include <sys/param.h>
#include <errno.h>
#include <pwd.h>
#include <string.h>
#include <unistd.h>
#include <stdarg.h>

#include <grp.h>

#include "log.h"
#include "uidswap.h"
#include "xmalloc.h"

/*
 * Note: all these functions must work in all of the following cases:
 *    1. euid=0, ruid=0
 *    2. euid=0, ruid!=0
 *    3. euid!=0, ruid!=0
 * Additionally, they must work regardless of whether the system has
 * POSIX saved uids or not.
 */

#if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS)
/* Lets assume that posix saved ids also work with seteuid, even though that
   is not part of the posix specification. */
#define SAVED_IDS_WORK_WITH_SETEUID
/* Saved effective uid. */
static uid_t 	saved_euid = 0;
static gid_t	saved_egid = 0;
#endif

/* Saved effective uid. */
static int	privileged = 0;
static int	temporarily_use_uid_effective = 0;
static gid_t	*saved_egroups = NULL, *user_groups = NULL;
static int	saved_egroupslen = -1, user_groupslen = -1;

/*
 * Temporarily changes to the given uid.  If the effective user
 * id is not root, this does nothing.  This call cannot be nested.
 */
void
temporarily_use_uid(struct passwd *pw)
{
	/* Save the current euid, and egroups. */
#ifdef SAVED_IDS_WORK_WITH_SETEUID
	saved_euid = geteuid();
	saved_egid = getegid();
	debug("temporarily_use_uid: %u/%u (e=%u/%u)",
	    (u_int)pw->pw_uid, (u_int)pw->pw_gid,
	    (u_int)saved_euid, (u_int)saved_egid);
#ifndef HAVE_CYGWIN
	if (saved_euid != 0) {
		privileged = 0;
		return;
	}
#endif
#else
	if (geteuid() != 0) {
		privileged = 0;
		return;
	}
#endif /* SAVED_IDS_WORK_WITH_SETEUID */

	privileged = 1;
	temporarily_use_uid_effective = 1;

	saved_egroupslen = getgroups(0, NULL);
	if (saved_egroupslen < 0)
		fatal("getgroups: %.100s", strerror(errno));
	if (saved_egroupslen > 0) {
		saved_egroups = xrealloc(saved_egroups,
		    saved_egroupslen, sizeof(gid_t));
		if (getgroups(saved_egroupslen, saved_egroups) < 0)
			fatal("getgroups: %.100s", strerror(errno));
	} else { /* saved_egroupslen == 0 */
		if (saved_egroups != NULL)
			xfree(saved_egroups);
	}

	/* set and save the user's groups */
	if (user_groupslen == -1) {
		if (initgroups(pw->pw_name, pw->pw_gid) < 0)
			fatal("initgroups: %s: %.100s", pw->pw_name,
			    strerror(errno));

		user_groupslen = getgroups(0, NULL);
		if (user_groupslen < 0)
			fatal("getgroups: %.100s", strerror(errno));
		if (user_groupslen > 0) {
			user_groups = xrealloc(user_groups,
			    user_groupslen, sizeof(gid_t));
			if (getgroups(user_groupslen, user_groups) < 0)
				fatal("getgroups: %.100s", strerror(errno));
		} else { /* user_groupslen == 0 */
			if (user_groups)
				xfree(user_groups);
		}
	}
	/* Set the effective uid to the given (unprivileged) uid. */
	if (setgroups(user_groupslen, user_groups) < 0)
		fatal("setgroups: %.100s", strerror(errno));
#ifndef SAVED_IDS_WORK_WITH_SETEUID
	/* Propagate the privileged gid to all of our gids. */
	if (setgid(getegid()) < 0)
		debug("setgid %u: %.100s", (u_int) getegid(), strerror(errno));
	/* Propagate the privileged uid to all of our uids. */
	if (setuid(geteuid()) < 0)
		debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno));
#endif /* SAVED_IDS_WORK_WITH_SETEUID */
	if (setegid(pw->pw_gid) < 0)
		fatal("setegid %u: %.100s", (u_int)pw->pw_gid,
		    strerror(errno));
	if (seteuid(pw->pw_uid) == -1)
		fatal("seteuid %u: %.100s", (u_int)pw->pw_uid,
		    strerror(errno));
}

void
permanently_drop_suid(uid_t uid)
{
	uid_t old_uid = getuid();

	debug("permanently_drop_suid: %u", (u_int)uid);
#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
	if (setresuid(uid, uid, uid) < 0)
		fatal("setresuid %u: %.100s", (u_int)uid, strerror(errno));
#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
	if (setreuid(uid, uid) < 0)
		fatal("setreuid %u: %.100s", (u_int)uid, strerror(errno));
#else
# ifndef SETEUID_BREAKS_SETUID
	if (seteuid(uid) < 0)
		fatal("seteuid %u: %.100s", (u_int)uid, strerror(errno));
# endif
	if (setuid(uid) < 0)
		fatal("setuid %u: %.100s", (u_int)uid, strerror(errno));
#endif

#ifndef HAVE_CYGWIN
	/* Try restoration of UID if changed (test clearing of saved uid) */
	if (old_uid != uid &&
	    (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
		fatal("%s: was able to restore old [e]uid", __func__);
#endif

	/* Verify UID drop was successful */
	if (getuid() != uid || geteuid() != uid) {
		fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
		    __func__, (u_int)getuid(), (u_int)geteuid(), (u_int)uid);
	}
}

/*
 * Restores to the original (privileged) uid.
 */
void
restore_uid(void)
{
	/* it's a no-op unless privileged */
	if (!privileged) {
		debug("restore_uid: (unprivileged)");
		return;
	}
	if (!temporarily_use_uid_effective)
		fatal("restore_uid: temporarily_use_uid not effective");

#ifdef SAVED_IDS_WORK_WITH_SETEUID
	debug("restore_uid: %u/%u", (u_int)saved_euid, (u_int)saved_egid);
	/* Set the effective uid back to the saved privileged uid. */
	if (seteuid(saved_euid) < 0)
		fatal("seteuid %u: %.100s", (u_int)saved_euid, strerror(errno));
	if (setegid(saved_egid) < 0)
		fatal("setegid %u: %.100s", (u_int)saved_egid, strerror(errno));
#else /* SAVED_IDS_WORK_WITH_SETEUID */
	/*
	 * We are unable to restore the real uid to its unprivileged value.
	 * Propagate the real uid (usually more privileged) to effective uid
	 * as well.
	 */
	setuid(getuid());
	setgid(getgid());
#endif /* SAVED_IDS_WORK_WITH_SETEUID */

	if (setgroups(saved_egroupslen, saved_egroups) < 0)
		fatal("setgroups: %.100s", strerror(errno));
	temporarily_use_uid_effective = 0;
}

/*
 * Permanently sets all uids to the given uid.  This cannot be
 * called while temporarily_use_uid is effective.
 */
void
permanently_set_uid(struct passwd *pw)
{
	uid_t old_uid = getuid();
	gid_t old_gid = getgid();

	if (pw == NULL)
		fatal("permanently_set_uid: no user given");
	if (temporarily_use_uid_effective)
		fatal("permanently_set_uid: temporarily_use_uid effective");
	debug("permanently_set_uid: %u/%u", (u_int)pw->pw_uid,
	    (u_int)pw->pw_gid);

#if defined(HAVE_SETRESGID) && !defined(BROKEN_SETRESGID)
	if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0)
		fatal("setresgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
#elif defined(HAVE_SETREGID) && !defined(BROKEN_SETREGID)
	if (setregid(pw->pw_gid, pw->pw_gid) < 0)
		fatal("setregid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
#else
	if (setegid(pw->pw_gid) < 0)
		fatal("setegid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
	if (setgid(pw->pw_gid) < 0)
		fatal("setgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
#endif

#ifdef __APPLE__
	/*
	 * OS X requires initgroups after setgid to opt back into
	 * memberd support for >16 supplemental groups.
	 */
	if (initgroups(pw->pw_name, pw->pw_gid) < 0)
		fatal("initgroups %.100s %u: %.100s",
		    pw->pw_name, (u_int)pw->pw_gid, strerror(errno));
#endif

#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
	if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)
		fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
	if (setreuid(pw->pw_uid, pw->pw_uid) < 0)
		fatal("setreuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
#else
# ifndef SETEUID_BREAKS_SETUID
	if (seteuid(pw->pw_uid) < 0)
		fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
# endif
	if (setuid(pw->pw_uid) < 0)
		fatal("setuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
#endif

#ifndef HAVE_CYGWIN
	/* Try restoration of GID if changed (test clearing of saved gid) */
	if (old_gid != pw->pw_gid && pw->pw_uid != 0 &&
	    (setgid(old_gid) != -1 || setegid(old_gid) != -1))
		fatal("%s: was able to restore old [e]gid", __func__);
#endif

	/* Verify GID drop was successful */
	if (getgid() != pw->pw_gid || getegid() != pw->pw_gid) {
		fatal("%s: egid incorrect gid:%u egid:%u (should be %u)",
		    __func__, (u_int)getgid(), (u_int)getegid(),
		    (u_int)pw->pw_gid);
	}

#ifndef HAVE_CYGWIN
	/* Try restoration of UID if changed (test clearing of saved uid) */
	if (old_uid != pw->pw_uid &&
	    (setuid(old_uid) != -1 || seteuid(old_uid) != -1))
		fatal("%s: was able to restore old [e]uid", __func__);
#endif

	/* Verify UID drop was successful */
	if (getuid() != pw->pw_uid || geteuid() != pw->pw_uid) {
		fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
		    __func__, (u_int)getuid(), (u_int)geteuid(),
		    (u_int)pw->pw_uid);
	}
}
Commit	Line	Data
31652869	1	/* $OpenBSD: uidswap.c,v 1.35 2006/08/03 03:34:42 deraadt Exp $ */
8efc0c15	2	/*
5260325f	3	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	4	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	5	* All rights reserved
5260325f	6	* Code for uid-swapping.
bcbf86ec	7	*
	8	* As far as I am concerned, the code I have written for this software
	9	* can be used freely for any purpose. Any derived versions of this
	10	* software must be clearly marked as such, and if the derived work is
	11	* incompatible with the protocol description in the RFC file, it must be
	12	* called by a name other than "ssh" or "Secure Shell".
5260325f	13	*/
8efc0c15	14
8efc0c15	15	#include "includes.h"
8efc0c15	16
536c14e8	17	#include <sys/param.h>
028094f4	18	#include <errno.h>
b1842393	19	#include <pwd.h>
00146caa	20	#include <string.h>
5188ba17	21	#include <unistd.h>
31652869	22	#include <stdarg.h>
b1842393	23
16fbe330	24	#include <grp.h>
16fbe330	25
42f11eb2	26	#include "log.h"
8efc0c15	27	#include "uidswap.h"
13dff404	28	#include "xmalloc.h"
8efc0c15	29
5260325f	30	/*
	31	* Note: all these functions must work in all of the following cases:
	32	* 1. euid=0, ruid=0
	33	* 2. euid=0, ruid!=0
	34	* 3. euid!=0, ruid!=0
	35	* Additionally, they must work regardless of whether the system has
	36	* POSIX saved uids or not.
	37	*/
8efc0c15	38
0096ac62	39	#if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS)
8efc0c15	40	/* Lets assume that posix saved ids also work with seteuid, even though that
8efc0c15	41	is not part of the posix specification. */
0096ac62	42	#define SAVED_IDS_WORK_WITH_SETEUID
	43	/* Saved effective uid. */
	44	static uid_t saved_euid = 0;
	45	static gid_t saved_egid = 0;
	46	#endif
f8252c48	47
8efc0c15	48	/* Saved effective uid. */
63bd8c36	49	static int privileged = 0;
63bd8c36	50	static int temporarily_use_uid_effective = 0;
13dff404	51	static gid_t saved_egroups = NULL, user_groups = NULL;
63bd8c36	52	static int saved_egroupslen = -1, user_groupslen = -1;
f8252c48	53
5260325f	54	/*
	55	* Temporarily changes to the given uid. If the effective user
	56	* id is not root, this does nothing. This call cannot be nested.
	57	*/
6ae2364d	58	void
63bd8c36	59	temporarily_use_uid(struct passwd *pw)
8efc0c15	60	{
f8252c48	61	/* Save the current euid, and egroups. */
0096ac62	62	#ifdef SAVED_IDS_WORK_WITH_SETEUID
f8252c48	63	saved_euid = geteuid();
0096ac62	64	saved_egid = getegid();
0df3a240	65	debug("temporarily_use_uid: %u/%u (e=%u/%u)",
	66	(u_int)pw->pw_uid, (u_int)pw->pw_gid,
	67	(u_int)saved_euid, (u_int)saved_egid);
c2736f7f	68	#ifndef HAVE_CYGWIN
f8252c48	69	if (saved_euid != 0) {
	70	privileged = 0;
	71	return;
	72	}
c2736f7f	73	#endif
0096ac62	74	#else
	75	if (geteuid() != 0) {
	76	privileged = 0;
	77	return;
	78	}
	79	#endif /* SAVED_IDS_WORK_WITH_SETEUID */
	80
f8252c48	81	privileged = 1;
f8252c48	82	temporarily_use_uid_effective = 1;
13dff404	83
13dff404	84	saved_egroupslen = getgroups(0, NULL);
f8252c48	85	if (saved_egroupslen < 0)
f8252c48	86	fatal("getgroups: %.100s", strerror(errno));
13dff404	87	if (saved_egroupslen > 0) {
13dff404	88	saved_egroups = xrealloc(saved_egroups,
c5d10563	89	saved_egroupslen, sizeof(gid_t));
13dff404	90	if (getgroups(saved_egroupslen, saved_egroups) < 0)
	91	fatal("getgroups: %.100s", strerror(errno));
	92	} else { /* saved_egroupslen == 0 */
972fc531	93	if (saved_egroups != NULL)
13dff404	94	xfree(saved_egroups);
13dff404	95	}
f8252c48	96
	97	/* set and save the user's groups */
	98	if (user_groupslen == -1) {
	99	if (initgroups(pw->pw_name, pw->pw_gid) < 0)
	100	fatal("initgroups: %s: %.100s", pw->pw_name,
	101	strerror(errno));
13dff404	102
13dff404	103	user_groupslen = getgroups(0, NULL);
f8252c48	104	if (user_groupslen < 0)
f8252c48	105	fatal("getgroups: %.100s", strerror(errno));
13dff404	106	if (user_groupslen > 0) {
13dff404	107	user_groups = xrealloc(user_groups,
c5d10563	108	user_groupslen, sizeof(gid_t));
13dff404	109	if (getgroups(user_groupslen, user_groups) < 0)
	110	fatal("getgroups: %.100s", strerror(errno));
	111	} else { /* user_groupslen == 0 */
	112	if (user_groups)
	113	xfree(user_groups);
	114	}
f8252c48	115	}
f8252c48	116	/* Set the effective uid to the given (unprivileged) uid. */
d98d029a	117	if (setgroups(user_groupslen, user_groups) < 0)
63bd8c36	118	fatal("setgroups: %.100s", strerror(errno));
0096ac62	119	#ifndef SAVED_IDS_WORK_WITH_SETEUID
	120	/* Propagate the privileged gid to all of our gids. */
	121	if (setgid(getegid()) < 0)
	122	debug("setgid %u: %.100s", (u_int) getegid(), strerror(errno));
	123	/* Propagate the privileged uid to all of our uids. */
	124	if (setuid(geteuid()) < 0)
	125	debug("setuid %u: %.100s", (u_int) geteuid(), strerror(errno));
	126	#endif /* SAVED_IDS_WORK_WITH_SETEUID */
d98d029a	127	if (setegid(pw->pw_gid) < 0)
caa49784	128	fatal("setegid %u: %.100s", (u_int)pw->pw_gid,
f8252c48	129	strerror(errno));
f8252c48	130	if (seteuid(pw->pw_uid) == -1)
caa49784	131	fatal("seteuid %u: %.100s", (u_int)pw->pw_uid,
f8252c48	132	strerror(errno));
8efc0c15	133	}
f8252c48	134
3c33c1b6	135	void
	136	permanently_drop_suid(uid_t uid)
	137	{
	138	uid_t old_uid = getuid();
	139
	140	debug("permanently_drop_suid: %u", (u_int)uid);
	141	#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
	142	if (setresuid(uid, uid, uid) < 0)
	143	fatal("setresuid %u: %.100s", (u_int)uid, strerror(errno));
	144	#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
	145	if (setreuid(uid, uid) < 0)
	146	fatal("setreuid %u: %.100s", (u_int)uid, strerror(errno));
	147	#else
	148	# ifndef SETEUID_BREAKS_SETUID
	149	if (seteuid(uid) < 0)
	150	fatal("seteuid %u: %.100s", (u_int)uid, strerror(errno));
	151	# endif
	152	if (setuid(uid) < 0)
	153	fatal("setuid %u: %.100s", (u_int)uid, strerror(errno));
	154	#endif
	155
	156	#ifndef HAVE_CYGWIN
	157	/* Try restoration of UID if changed (test clearing of saved uid) */
	158	if (old_uid != uid &&
	159	(setuid(old_uid) != -1 \|\| seteuid(old_uid) != -1))
	160	fatal("%s: was able to restore old [e]uid", __func__);
	161	#endif
	162
	163	/* Verify UID drop was successful */
	164	if (getuid() != uid \|\| geteuid() != uid) {
	165	fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
	166	__func__, (u_int)getuid(), (u_int)geteuid(), (u_int)uid);
	167	}
	168	}
	169
5260325f	170	/*
a3626e12	171	* Restores to the original (privileged) uid.
5260325f	172	*/
6ae2364d	173	void
1e3b8b07	174	restore_uid(void)
8efc0c15	175	{
63bd8c36	176	/* it's a no-op unless privileged */
0df3a240	177	if (!privileged) {
0df3a240	178	debug("restore_uid: (unprivileged)");
63bd8c36	179	return;
0df3a240	180	}
63bd8c36	181	if (!temporarily_use_uid_effective)
63bd8c36	182	fatal("restore_uid: temporarily_use_uid not effective");
0096ac62	183
0096ac62	184	#ifdef SAVED_IDS_WORK_WITH_SETEUID
13979d47	185	debug("restore_uid: %u/%u", (u_int)saved_euid, (u_int)saved_egid);
a3626e12	186	/* Set the effective uid back to the saved privileged uid. */
5260325f	187	if (seteuid(saved_euid) < 0)
caa49784	188	fatal("seteuid %u: %.100s", (u_int)saved_euid, strerror(errno));
0096ac62	189	if (setegid(saved_egid) < 0)
caa49784	190	fatal("setegid %u: %.100s", (u_int)saved_egid, strerror(errno));
0096ac62	191	#else /* SAVED_IDS_WORK_WITH_SETEUID */
	192	/*
	193	* We are unable to restore the real uid to its unprivileged value.
	194	* Propagate the real uid (usually more privileged) to effective uid
	195	* as well.
	196	*/
	197	setuid(getuid());
	198	setgid(getgid());
	199	#endif /* SAVED_IDS_WORK_WITH_SETEUID */
	200
d98d029a	201	if (setgroups(saved_egroupslen, saved_egroups) < 0)
63bd8c36	202	fatal("setgroups: %.100s", strerror(errno));
63bd8c36	203	temporarily_use_uid_effective = 0;
8efc0c15	204	}
8efc0c15	205
5260325f	206	/*
	207	* Permanently sets all uids to the given uid. This cannot be
	208	* called while temporarily_use_uid is effective.
	209	*/
6ae2364d	210	void
63bd8c36	211	permanently_set_uid(struct passwd *pw)
8efc0c15	212	{
688eed4a	213	uid_t old_uid = getuid();
	214	gid_t old_gid = getgid();
	215
82aeee5d	216	if (pw == NULL)
82aeee5d	217	fatal("permanently_set_uid: no user given");
63bd8c36	218	if (temporarily_use_uid_effective)
95f20fe8	219	fatal("permanently_set_uid: temporarily_use_uid effective");
0df3a240	220	debug("permanently_set_uid: %u/%u", (u_int)pw->pw_uid,
0df3a240	221	(u_int)pw->pw_gid);
688eed4a	222
9a3fe0e2	223	#if defined(HAVE_SETRESGID) && !defined(BROKEN_SETRESGID)
688eed4a	224	if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) < 0)
688eed4a	225	fatal("setresgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
3b8dff69	226	#elif defined(HAVE_SETREGID) && !defined(BROKEN_SETREGID)
688eed4a	227	if (setregid(pw->pw_gid, pw->pw_gid) < 0)
	228	fatal("setregid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
	229	#else
fa5120a0	230	if (setegid(pw->pw_gid) < 0)
fa5120a0	231	fatal("setegid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
63bd8c36	232	if (setgid(pw->pw_gid) < 0)
caa49784	233	fatal("setgid %u: %.100s", (u_int)pw->pw_gid, strerror(errno));
688eed4a	234	#endif
688eed4a	235
a25d08b3	236	#ifdef __APPLE__
	237	/*
	238	* OS X requires initgroups after setgid to opt back into
	239	* memberd support for >16 supplemental groups.
	240	*/
	241	if (initgroups(pw->pw_name, pw->pw_gid) < 0)
	242	fatal("initgroups %.100s %u: %.100s",
	243	pw->pw_name, (u_int)pw->pw_gid, strerror(errno));
	244	#endif
	245
9a3fe0e2	246	#if defined(HAVE_SETRESUID) && !defined(BROKEN_SETRESUID)
688eed4a	247	if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) < 0)
688eed4a	248	fatal("setresuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
3b8dff69	249	#elif defined(HAVE_SETREUID) && !defined(BROKEN_SETREUID)
f5db6a03	250	if (setreuid(pw->pw_uid, pw->pw_uid) < 0)
f5db6a03	251	fatal("setreuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
688eed4a	252	#else
688eed4a	253	# ifndef SETEUID_BREAKS_SETUID
fa5120a0	254	if (seteuid(pw->pw_uid) < 0)
fa5120a0	255	fatal("seteuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
688eed4a	256	# endif
a3626e12	257	if (setuid(pw->pw_uid) < 0)
caa49784	258	fatal("setuid %u: %.100s", (u_int)pw->pw_uid, strerror(errno));
688eed4a	259	#endif
688eed4a	260
8f817407	261	#ifndef HAVE_CYGWIN
688eed4a	262	/* Try restoration of GID if changed (test clearing of saved gid) */
8f817407	263	if (old_gid != pw->pw_gid && pw->pw_uid != 0 &&
688eed4a	264	(setgid(old_gid) != -1 \|\| setegid(old_gid) != -1))
f5db6a03	265	fatal("%s: was able to restore old [e]gid", __func__);
8f817407	266	#endif
688eed4a	267
	268	/* Verify GID drop was successful */
	269	if (getgid() != pw->pw_gid \|\| getegid() != pw->pw_gid) {
aff51935	270	fatal("%s: egid incorrect gid:%u egid:%u (should be %u)",
aff51935	271	__func__, (u_int)getgid(), (u_int)getegid(),
688eed4a	272	(u_int)pw->pw_gid);
	273	}
	274
51e7d820	275	#ifndef HAVE_CYGWIN
688eed4a	276	/* Try restoration of UID if changed (test clearing of saved uid) */
aff51935	277	if (old_uid != pw->pw_uid &&
688eed4a	278	(setuid(old_uid) != -1 \|\| seteuid(old_uid) != -1))
f5db6a03	279	fatal("%s: was able to restore old [e]uid", __func__);
51e7d820	280	#endif
688eed4a	281
	282	/* Verify UID drop was successful */
	283	if (getuid() != pw->pw_uid \|\| geteuid() != pw->pw_uid) {
aff51935	284	fatal("%s: euid incorrect uid:%u euid:%u (should be %u)",
aff51935	285	__func__, (u_int)getuid(), (u_int)geteuid(),
688eed4a	286	(u_int)pw->pw_uid);
688eed4a	287	}
8efc0c15	288	}