[nss_nonlocal.git] / nonlocal-passwd.c

/*
 * nonlocal-passwd.c
 * passwd database for nss_nonlocal proxy.
 *
 * Copyright © 2007 Anders Kaseorg <andersk@mit.edu> and Tim Abbott
 * <tabbott@mit.edu>
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */


#define _GNU_SOURCE
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <dlfcn.h>
#include <stdio.h>
#include <syslog.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <nss.h>
#include "nsswitch-internal.h"
#include "nonlocal.h"

#define MAGIC_LOCAL_PW_BUFLEN (sysconf(_SC_GETPW_R_SIZE_MAX) + 7)


static service_user *
nss_passwd_nonlocal_database(void)
{
    static service_user *nip = NULL;
    if (nip == NULL)
	__nss_database_lookup("passwd_nonlocal", NULL, "", &nip);

    return nip;
}


enum nss_status
check_nonlocal_uid(const char *user, uid_t uid, int *errnop)
{
    enum nss_status status = NSS_STATUS_SUCCESS;
    struct passwd pwbuf;
    struct passwd *pwbufp = &pwbuf;
    int ret;
    int old_errno = errno;
    int buflen = MAGIC_LOCAL_PW_BUFLEN;
    char *buf = malloc(buflen);
    if (buf == NULL) {
	*errnop = ENOMEM;
	errno = old_errno;
	return NSS_STATUS_TRYAGAIN;
    }
    errno = 0;
    ret = getpwuid_r(uid, pwbufp, buf, buflen, &pwbufp);
    if (ret != 0) {
	*errnop = errno;
	status = NSS_STATUS_TRYAGAIN;
    } else if (pwbufp != NULL) {
	syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name);
	status = NSS_STATUS_NOTFOUND;
    }
    free(buf);
    errno = old_errno;
    return status;
}

enum nss_status
check_nonlocal_user(const char *user, int *errnop)
{
    enum nss_status status = NSS_STATUS_SUCCESS;
    struct passwd pwbuf;
    struct passwd *pwbufp = &pwbuf;
    int ret;
    int old_errno = errno;
    int buflen = MAGIC_LOCAL_PW_BUFLEN;
    char *buf = malloc(buflen);
    if (buf == NULL) {
	*errnop = ENOMEM;
	errno = old_errno;
	return NSS_STATUS_TRYAGAIN;
    }
    errno = 0;
    ret = getpwnam_r(user, pwbufp, buf, buflen, &pwbufp);
    if (ret != 0) {
	*errnop = errno;
	status = NSS_STATUS_TRYAGAIN;
    } else if (pwbufp != NULL) {
	status = NSS_STATUS_NOTFOUND;
    }
    free(buf);
    errno = old_errno;
    return status;
}

static service_user *pwent_nip = NULL;
static void *pwent_fct_start;
static union {
    enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen,
			 int *errnop);
    void *ptr;
} pwent_fct;
static const char *pwent_fct_name = "getpwent_r";

enum nss_status
_nss_nonlocal_setpwent(int stayopen)
{
    static const char *fct_name = "setpwent";
    static void *fct_start = NULL;
    enum nss_status status;
    service_user *nip;
    union {
	enum nss_status (*l)(int stayopen);
	void *ptr;
    } fct;

    nip = nss_passwd_nonlocal_database();
    if (nip == NULL)
	return NSS_STATUS_UNAVAIL;
    if (fct_start == NULL)
	fct_start = __nss_lookup_function(nip, fct_name);
    fct.ptr = fct_start;
    do {
	if (fct.ptr == NULL)
	    status = NSS_STATUS_UNAVAIL;
	else
	    status = DL_CALL_FCT(fct.l, (stayopen));
    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
    if (status != NSS_STATUS_SUCCESS)
	return status;

    pwent_nip = nip;
    if (pwent_fct_start == NULL)
	pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name);
    pwent_fct.ptr = pwent_fct_start;
    return NSS_STATUS_SUCCESS;
}

enum nss_status
_nss_nonlocal_endpwent(void)
{
    static const char *fct_name = "endpwent";
    static void *fct_start = NULL;
    enum nss_status status;
    service_user *nip;
    union {
	enum nss_status (*l)(void);
	void *ptr;
    } fct;

    pwent_nip = NULL;

    nip = nss_passwd_nonlocal_database();
    if (nip == NULL)
	return NSS_STATUS_UNAVAIL;
    if (fct_start == NULL)
	fct_start = __nss_lookup_function(nip, fct_name);
    fct.ptr = fct_start;
    do {
	if (fct.ptr == NULL)
	    status = NSS_STATUS_UNAVAIL;
	else
	    status = DL_CALL_FCT(fct.l, ());
    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
    return status;
}

enum nss_status
_nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen,
			 int *errnop)
{
    enum nss_status status;
    if (pwent_nip == NULL) {
	status = _nss_nonlocal_setpwent(0);
	if (status != NSS_STATUS_SUCCESS)
	    return status;
    }
    do {
	if (pwent_fct.ptr == NULL)
	    status = NSS_STATUS_UNAVAIL;
	else {
	    int nonlocal_errno;
	    do
		status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop));	
	    while (status == NSS_STATUS_SUCCESS &&
		   check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS);
	}
	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
	    return status;

	if (status == NSS_STATUS_SUCCESS)
	    return NSS_STATUS_SUCCESS;
    } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0);

    pwent_nip = NULL;
    return NSS_STATUS_NOTFOUND;
}


enum nss_status
_nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd,
			 char *buffer, size_t buflen, int *errnop)
{
    static const char *fct_name = "getpwnam_r";
    static void *fct_start = NULL;
    enum nss_status status;
    service_user *nip;
    union {
	enum nss_status (*l)(const char *name, struct passwd *pwd,
			     char *buffer, size_t buflen, int *errnop);
	void *ptr;
    } fct;
    int group_errno;

    if (buflen == MAGIC_LOCAL_PW_BUFLEN)
	return NSS_STATUS_UNAVAIL;

    nip = nss_passwd_nonlocal_database();
    if (nip == NULL)
	return NSS_STATUS_UNAVAIL;
    if (fct_start == NULL)
	fct_start = __nss_lookup_function(nip, fct_name);
    fct.ptr = fct_start;
    do {
	if (fct.ptr == NULL)
	    status = NSS_STATUS_UNAVAIL;
	else
	    status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop));
	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
	    break;
    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
    if (status != NSS_STATUS_SUCCESS)
	return status;

    status = check_nonlocal_uid(name, pwd->pw_uid, errnop);
    if (status != NSS_STATUS_SUCCESS)
	return status;

    if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) !=
	NSS_STATUS_SUCCESS)
	pwd->pw_gid = 65534 /* nogroup */;
    return NSS_STATUS_SUCCESS;
}

enum nss_status
_nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd,
			 char *buffer, size_t buflen, int *errnop)
{
    static const char *fct_name = "getpwuid_r";
    static void *fct_start = NULL;
    enum nss_status status;
    service_user *nip;
    union {
	enum nss_status (*l)(uid_t uid, struct passwd *pwd,
			     char *buffer, size_t buflen, int *errnop);
	void *ptr;
    } fct;
    int group_errno;

    if (buflen == MAGIC_LOCAL_PW_BUFLEN)
	return NSS_STATUS_UNAVAIL;

    nip = nss_passwd_nonlocal_database();
    if (nip == NULL)
	return NSS_STATUS_UNAVAIL;
    if (fct_start == NULL)
	fct_start = __nss_lookup_function(nip, fct_name);
    fct.ptr = fct_start;
    do {
	if (fct.ptr == NULL)
	    status = NSS_STATUS_UNAVAIL;
	else
	    status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop));
	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
	    break;
    } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
    if (status != NSS_STATUS_SUCCESS)
	return status;

    status = check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, errnop);
    if (status != NSS_STATUS_SUCCESS)
	return status;

    if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) !=
	NSS_STATUS_SUCCESS)
	pwd->pw_gid = 65534 /* nogroup */;
    return NSS_STATUS_SUCCESS;
}
Commit	Line	Data
f6903667 AK	1	/*
	2	* nonlocal-passwd.c
	3	* passwd database for nss_nonlocal proxy.
	4	*
48479fc7 TA	5	* Copyright © 2007 Anders Kaseorg <andersk@mit.edu> and Tim Abbott
48479fc7 TA	6	* <tabbott@mit.edu>
f6903667 AK	7	*
	8	* Permission is hereby granted, free of charge, to any person
	9	* obtaining a copy of this software and associated documentation
	10	* files (the "Software"), to deal in the Software without
	11	* restriction, including without limitation the rights to use, copy,
	12	* modify, merge, publish, distribute, sublicense, and/or sell copies
	13	* of the Software, and to permit persons to whom the Software is
	14	* furnished to do so, subject to the following conditions:
	15	*
	16	* The above copyright notice and this permission notice shall be
	17	* included in all copies or substantial portions of the Software.
	18	*
	19	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	20	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	21	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	22	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
	23	* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
	24	* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
	25	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	26	* SOFTWARE.
	27	*/
	28
	29
	30	#define _GNU_SOURCE
	31	#include <sys/types.h>
	32	#include <unistd.h>
	33	#include <stdlib.h>
	34	#include <stdint.h>
	35	#include <string.h>
	36	#include <dlfcn.h>
	37	#include <stdio.h>
	38	#include <syslog.h>
	39	#include <errno.h>
	40	#include <pwd.h>
	41	#include <grp.h>
	42	#include <nss.h>
	43	#include "nsswitch-internal.h"
	44	#include "nonlocal.h"
	45
f7293a54 AK	46	#define MAGIC_LOCAL_PW_BUFLEN (sysconf(_SC_GETPW_R_SIZE_MAX) + 7)
f7293a54 AK	47
f6903667 AK	48
	49	static service_user *
	50	nss_passwd_nonlocal_database(void)
	51	{
	52	static service_user *nip = NULL;
	53	if (nip == NULL)
	54	__nss_database_lookup("passwd_nonlocal", NULL, "", &nip);
	55
	56	return nip;
	57	}
	58
	59
f6903667 AK	60	enum nss_status
	61	check_nonlocal_uid(const char user, uid_t uid, int errnop)
	62	{
f7293a54 AK	63	enum nss_status status = NSS_STATUS_SUCCESS;
	64	struct passwd pwbuf;
	65	struct passwd *pwbufp = &pwbuf;
	66	int ret;
	67	int old_errno = errno;
	68	int buflen = MAGIC_LOCAL_PW_BUFLEN;
	69	char *buf = malloc(buflen);
	70	if (buf == NULL) {
f6903667	71	*errnop = ENOMEM;
f7293a54	72	errno = old_errno;
f6903667 AK	73	return NSS_STATUS_TRYAGAIN;
f6903667 AK	74	}
f7293a54 AK	75	errno = 0;
	76	ret = getpwuid_r(uid, pwbufp, buf, buflen, &pwbufp);
	77	if (ret != 0) {
	78	*errnop = errno;
	79	status = NSS_STATUS_TRYAGAIN;
	80	} else if (pwbufp != NULL) {
	81	syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name);
f6903667	82	status = NSS_STATUS_NOTFOUND;
f6903667	83	}
f7293a54 AK	84	free(buf);
f7293a54 AK	85	errno = old_errno;
f6903667 AK	86	return status;
	87	}
	88
48479fc7 TA	89	enum nss_status
	90	check_nonlocal_user(const char user, int errnop)
	91	{
	92	enum nss_status status = NSS_STATUS_SUCCESS;
	93	struct passwd pwbuf;
	94	struct passwd *pwbufp = &pwbuf;
	95	int ret;
	96	int old_errno = errno;
	97	int buflen = MAGIC_LOCAL_PW_BUFLEN;
	98	char *buf = malloc(buflen);
	99	if (buf == NULL) {
	100	*errnop = ENOMEM;
	101	errno = old_errno;
	102	return NSS_STATUS_TRYAGAIN;
	103	}
	104	errno = 0;
	105	ret = getpwnam_r(user, pwbufp, buf, buflen, &pwbufp);
	106	if (ret != 0) {
	107	*errnop = errno;
	108	status = NSS_STATUS_TRYAGAIN;
	109	} else if (pwbufp != NULL) {
	110	status = NSS_STATUS_NOTFOUND;
	111	}
	112	free(buf);
	113	errno = old_errno;
	114	return status;
	115	}
f6903667 AK	116
	117	static service_user *pwent_nip = NULL;
	118	static void *pwent_fct_start;
	119	static union {
	120	enum nss_status (l)(struct passwd pwd, char *buffer, size_t buflen,
	121	int *errnop);
	122	void *ptr;
	123	} pwent_fct;
	124	static const char *pwent_fct_name = "getpwent_r";
	125
	126	enum nss_status
	127	_nss_nonlocal_setpwent(int stayopen)
	128	{
	129	static const char *fct_name = "setpwent";
	130	static void *fct_start = NULL;
	131	enum nss_status status;
	132	service_user *nip;
	133	union {
	134	enum nss_status (*l)(int stayopen);
	135	void *ptr;
	136	} fct;
	137
	138	nip = nss_passwd_nonlocal_database();
	139	if (nip == NULL)
	140	return NSS_STATUS_UNAVAIL;
	141	if (fct_start == NULL)
	142	fct_start = __nss_lookup_function(nip, fct_name);
	143	fct.ptr = fct_start;
	144	do {
	145	if (fct.ptr == NULL)
	146	status = NSS_STATUS_UNAVAIL;
	147	else
	148	status = DL_CALL_FCT(fct.l, (stayopen));
	149	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
	150	if (status != NSS_STATUS_SUCCESS)
	151	return status;
	152
	153	pwent_nip = nip;
	154	if (pwent_fct_start == NULL)
	155	pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name);
	156	pwent_fct.ptr = pwent_fct_start;
	157	return NSS_STATUS_SUCCESS;
	158	}
	159
	160	enum nss_status
	161	_nss_nonlocal_endpwent(void)
	162	{
	163	static const char *fct_name = "endpwent";
	164	static void *fct_start = NULL;
	165	enum nss_status status;
	166	service_user *nip;
	167	union {
	168	enum nss_status (*l)(void);
	169	void *ptr;
	170	} fct;
	171
	172	pwent_nip = NULL;
	173
	174	nip = nss_passwd_nonlocal_database();
	175	if (nip == NULL)
	176	return NSS_STATUS_UNAVAIL;
	177	if (fct_start == NULL)
	178	fct_start = __nss_lookup_function(nip, fct_name);
	179	fct.ptr = fct_start;
180	do {
181	if (fct.ptr == NULL)
182	status = NSS_STATUS_UNAVAIL;
183	else
184	status = DL_CALL_FCT(fct.l, ());
185	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
186	return status;
187	}
188
189	enum nss_status
190	_nss_nonlocal_getpwent_r(struct passwd pwd, char buffer, size_t buflen,
191	int *errnop)
192	{
193	enum nss_status status;
194	if (pwent_nip == NULL) {
195	status = _nss_nonlocal_setpwent(0);
196	if (status != NSS_STATUS_SUCCESS)
197	return status;
198	}
199	do {
200	if (pwent_fct.ptr == NULL)
201	status = NSS_STATUS_UNAVAIL;
202	else {
203	int nonlocal_errno;
204	do
205	status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop));
206	while (status == NSS_STATUS_SUCCESS &&
207	check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS);
208	}
209	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
210	return status;
211
212	if (status == NSS_STATUS_SUCCESS)
213	return NSS_STATUS_SUCCESS;
214	} while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0);
215
216	pwent_nip = NULL;
217	return NSS_STATUS_NOTFOUND;
218	}
219
220
221	enum nss_status
222	_nss_nonlocal_getpwnam_r(const char name, struct passwd pwd,
223	char buffer, size_t buflen, int errnop)
224	{
225	static const char *fct_name = "getpwnam_r";
226	static void *fct_start = NULL;
227	enum nss_status status;
228	service_user *nip;
229	union {
230	enum nss_status (l)(const char name, struct passwd *pwd,
231	char buffer, size_t buflen, int errnop);
232	void *ptr;
233	} fct;
234	int group_errno;
235
48479fc7 TA	236	if (buflen == MAGIC_LOCAL_PW_BUFLEN)
	237	return NSS_STATUS_UNAVAIL;
	238
f6903667 AK	239	nip = nss_passwd_nonlocal_database();
	240	if (nip == NULL)
	241	return NSS_STATUS_UNAVAIL;
	242	if (fct_start == NULL)
	243	fct_start = __nss_lookup_function(nip, fct_name);
	244	fct.ptr = fct_start;
	245	do {
	246	if (fct.ptr == NULL)
	247	status = NSS_STATUS_UNAVAIL;
	248	else
	249	status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop));
	250	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
	251	break;
	252	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
	253	if (status != NSS_STATUS_SUCCESS)
	254	return status;
	255
	256	status = check_nonlocal_uid(name, pwd->pw_uid, errnop);
	257	if (status != NSS_STATUS_SUCCESS)
	258	return status;
	259
	260	if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) !=
	261	NSS_STATUS_SUCCESS)
	262	pwd->pw_gid = 65534 /* nogroup */;
	263	return NSS_STATUS_SUCCESS;
	264	}
	265
	266	enum nss_status
	267	_nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd,
	268	char buffer, size_t buflen, int errnop)
	269	{
	270	static const char *fct_name = "getpwuid_r";
	271	static void *fct_start = NULL;
	272	enum nss_status status;
	273	service_user *nip;
	274	union {
	275	enum nss_status (l)(uid_t uid, struct passwd pwd,
	276	char buffer, size_t buflen, int errnop);
	277	void *ptr;
	278	} fct;
	279	int group_errno;
	280
f7293a54	281	if (buflen == MAGIC_LOCAL_PW_BUFLEN)
f6903667 AK	282	return NSS_STATUS_UNAVAIL;
	283
	284	nip = nss_passwd_nonlocal_database();
	285	if (nip == NULL)
	286	return NSS_STATUS_UNAVAIL;
	287	if (fct_start == NULL)
	288	fct_start = __nss_lookup_function(nip, fct_name);
	289	fct.ptr = fct_start;
	290	do {
	291	if (fct.ptr == NULL)
	292	status = NSS_STATUS_UNAVAIL;
	293	else
	294	status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop));
	295	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
	296	break;
	297	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
	298	if (status != NSS_STATUS_SUCCESS)
	299	return status;
	300
	301	status = check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, errnop);
	302	if (status != NSS_STATUS_SUCCESS)
	303	return status;
	304
	305	if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) !=
	306	NSS_STATUS_SUCCESS)
	307	pwd->pw_gid = 65534 /* nogroup */;
	308	return NSS_STATUS_SUCCESS;
	309	}