[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"


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;
}


static __thread int local_only = 0;

enum nss_status
local_getpwuid_r(uid_t uid, struct passwd *pwd,
		 char *buffer, size_t buflen, int *errnop)
{
    int old_local_only = local_only;
    int old_errno = errno;
    int ret;
    errno = *errnop;
    local_only = 1;

    ret = getpwuid_r(uid, pwd, buffer, buflen, &pwd);

    local_only = old_local_only;
    *errnop = errno;
    errno = old_errno;

    if (pwd != NULL)
	return NSS_STATUS_SUCCESS;
    else if (ret == 0)
	return NSS_STATUS_NOTFOUND;
    else
	return NSS_STATUS_TRYAGAIN;
}

enum nss_status
check_nonlocal_uid(const char *user, uid_t uid, int *errnop)
{
    struct passwd local_pwd;
    int local_errno = errno;
    enum nss_status local_status, status = NSS_STATUS_SUCCESS;
    int local_buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
    char *local_buffer = malloc(local_buflen);
    if (local_buffer == NULL) {
	*errnop = ENOMEM;
	errno = local_errno;
	return NSS_STATUS_TRYAGAIN;
    }
    local_errno = 0;
    local_status = local_getpwuid_r(uid, &local_pwd, local_buffer,
				    local_buflen, &local_errno);
    if (local_status == NSS_STATUS_SUCCESS) {
	syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, local_pwd.pw_name);
	status = NSS_STATUS_NOTFOUND;
    } else if (local_status != NSS_STATUS_NOTFOUND &&
	       local_status != NSS_STATUS_UNAVAIL) {
	*errnop = local_errno;
	status = local_status;
    }
    free(local_buffer);
    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 (local_only == 1)
	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
	45
	46	static service_user *
	47	nss_passwd_nonlocal_database(void)
	48	{
	49	static service_user *nip = NULL;
	50	if (nip == NULL)
	51	__nss_database_lookup("passwd_nonlocal", NULL, "", &nip);
	52
	53	return nip;
	54	}
	55
	56
	57	static __thread int local_only = 0;
	58
	59	enum nss_status
	60	local_getpwuid_r(uid_t uid, struct passwd *pwd,
	61	char buffer, size_t buflen, int errnop)
	62	{
	63	int old_local_only = local_only;
	64	int old_errno = errno;
65	int ret;
66	errno = *errnop;
67	local_only = 1;
68
69	ret = getpwuid_r(uid, pwd, buffer, buflen, &pwd);
70
71	local_only = old_local_only;
72	*errnop = errno;
73	errno = old_errno;
74
75	if (pwd != NULL)
76	return NSS_STATUS_SUCCESS;
77	else if (ret == 0)
78	return NSS_STATUS_NOTFOUND;
79	else
80	return NSS_STATUS_TRYAGAIN;
81	}
82
83	enum nss_status
84	check_nonlocal_uid(const char user, uid_t uid, int errnop)
85	{
86	struct passwd local_pwd;
87	int local_errno = errno;
88	enum nss_status local_status, status = NSS_STATUS_SUCCESS;
89	int local_buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
90	char *local_buffer = malloc(local_buflen);
91	if (local_buffer == NULL) {
92	*errnop = ENOMEM;
93	errno = local_errno;
94	return NSS_STATUS_TRYAGAIN;
95	}
96	local_errno = 0;
97	local_status = local_getpwuid_r(uid, &local_pwd, local_buffer,
98	local_buflen, &local_errno);
99	if (local_status == NSS_STATUS_SUCCESS) {
100	syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, local_pwd.pw_name);
101	status = NSS_STATUS_NOTFOUND;
102	} else if (local_status != NSS_STATUS_NOTFOUND &&
103	local_status != NSS_STATUS_UNAVAIL) {
104	*errnop = local_errno;
105	status = local_status;
106	}
107	free(local_buffer);
108	return status;
109	}
110
111
112	static service_user *pwent_nip = NULL;
113	static void *pwent_fct_start;
114	static union {
115	enum nss_status (l)(struct passwd pwd, char *buffer, size_t buflen,
116	int *errnop);
117	void *ptr;
118	} pwent_fct;
119	static const char *pwent_fct_name = "getpwent_r";
120
121	enum nss_status
122	_nss_nonlocal_setpwent(int stayopen)
123	{
124	static const char *fct_name = "setpwent";
125	static void *fct_start = NULL;
126	enum nss_status status;
127	service_user *nip;
128	union {
129	enum nss_status (*l)(int stayopen);
130	void *ptr;
131	} fct;
132
133	nip = nss_passwd_nonlocal_database();
134	if (nip == NULL)
135	return NSS_STATUS_UNAVAIL;
136	if (fct_start == NULL)
137	fct_start = __nss_lookup_function(nip, fct_name);
138	fct.ptr = fct_start;
139	do {
140	if (fct.ptr == NULL)
141	status = NSS_STATUS_UNAVAIL;
142	else
143	status = DL_CALL_FCT(fct.l, (stayopen));
144	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
145	if (status != NSS_STATUS_SUCCESS)
146	return status;
147
148	pwent_nip = nip;
149	if (pwent_fct_start == NULL)
150	pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name);
151	pwent_fct.ptr = pwent_fct_start;
152	return NSS_STATUS_SUCCESS;
153	}
154
155	enum nss_status
156	_nss_nonlocal_endpwent(void)
157	{
158	static const char *fct_name = "endpwent";
159	static void *fct_start = NULL;
160	enum nss_status status;
161	service_user *nip;
162	union {
163	enum nss_status (*l)(void);
164	void *ptr;
165	} fct;
166
167	pwent_nip = NULL;
168
169	nip = nss_passwd_nonlocal_database();
170	if (nip == NULL)
171	return NSS_STATUS_UNAVAIL;
172	if (fct_start == NULL)
173	fct_start = __nss_lookup_function(nip, fct_name);
174	fct.ptr = fct_start;
175	do {
176	if (fct.ptr == NULL)
177	status = NSS_STATUS_UNAVAIL;
178	else
179	status = DL_CALL_FCT(fct.l, ());
180	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
181	return status;
182	}
183
184	enum nss_status
185	_nss_nonlocal_getpwent_r(struct passwd pwd, char buffer, size_t buflen,
186	int *errnop)
187	{
188	enum nss_status status;
189	if (pwent_nip == NULL) {
190	status = _nss_nonlocal_setpwent(0);
191	if (status != NSS_STATUS_SUCCESS)
192	return status;
193	}
194	do {
195	if (pwent_fct.ptr == NULL)
196	status = NSS_STATUS_UNAVAIL;
197	else {
198	int nonlocal_errno;
199	do
200	status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop));
201	while (status == NSS_STATUS_SUCCESS &&
202	check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS);
203	}
204	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
205	return status;
206
207	if (status == NSS_STATUS_SUCCESS)
208	return NSS_STATUS_SUCCESS;
209	} while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0);
210
211	pwent_nip = NULL;
212	return NSS_STATUS_NOTFOUND;
213	}
214
215
216	enum nss_status
217	_nss_nonlocal_getpwnam_r(const char name, struct passwd pwd,
218	char buffer, size_t buflen, int errnop)
219	{
220	static const char *fct_name = "getpwnam_r";
221	static void *fct_start = NULL;
222	enum nss_status status;
223	service_user *nip;
224	union {
225	enum nss_status (l)(const char name, struct passwd *pwd,
226	char buffer, size_t buflen, int errnop);
227	void *ptr;
228	} fct;
229	int group_errno;
230
231	nip = nss_passwd_nonlocal_database();
232	if (nip == NULL)
233	return NSS_STATUS_UNAVAIL;
234	if (fct_start == NULL)
235	fct_start = __nss_lookup_function(nip, fct_name);
236	fct.ptr = fct_start;
237	do {
238	if (fct.ptr == NULL)
239	status = NSS_STATUS_UNAVAIL;
240	else
241	status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop));
242	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
243	break;
244	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
245	if (status != NSS_STATUS_SUCCESS)
246	return status;
247
248	status = check_nonlocal_uid(name, pwd->pw_uid, errnop);
249	if (status != NSS_STATUS_SUCCESS)
250	return status;
251
252	if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) !=
253	NSS_STATUS_SUCCESS)
254	pwd->pw_gid = 65534 /* nogroup */;
255	return NSS_STATUS_SUCCESS;
256	}
257
258	enum nss_status
259	_nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd,
260	char buffer, size_t buflen, int errnop)
261	{
262	static const char *fct_name = "getpwuid_r";
263	static void *fct_start = NULL;
264	enum nss_status status;
265	service_user *nip;
266	union {
267	enum nss_status (l)(uid_t uid, struct passwd pwd,
268	char buffer, size_t buflen, int errnop);
269	void *ptr;
270	} fct;
271	int group_errno;
272
273	if (local_only == 1)
274	return NSS_STATUS_UNAVAIL;
275
276	nip = nss_passwd_nonlocal_database();
277	if (nip == NULL)
278	return NSS_STATUS_UNAVAIL;
279	if (fct_start == NULL)
280	fct_start = __nss_lookup_function(nip, fct_name);
281	fct.ptr = fct_start;
282	do {
283	if (fct.ptr == NULL)
284	status = NSS_STATUS_UNAVAIL;
285	else
286	status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop));
287	if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE)
288	break;
289	} while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0);
290	if (status != NSS_STATUS_SUCCESS)
291	return status;
292
293	status = check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, errnop);
294	if (status != NSS_STATUS_SUCCESS)
295	return status;
296
297	if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) !=
298	NSS_STATUS_SUCCESS)
299	pwd->pw_gid = 65534 /* nogroup */;
300	return NSS_STATUS_SUCCESS;
301	}