[nss_nonlocal.git] / nonlocal-passwd.c

/*
 * nonlocal-passwd.c
 * passwd database for nss_nonlocal proxy.
 *
 * Copyright © 2007 Anders Kaseorg <andersk@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;
}


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;

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