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Commit | Line | Data |
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f6903667 AK |
1 | /* |
2 | * nonlocal-passwd.c | |
3 | * passwd database for nss_nonlocal proxy. | |
4 | * | |
96a1ee0f AK |
5 | * Copyright © 2007–2010 Anders Kaseorg <andersk@mit.edu> and Tim |
6 | * Abbott <tabbott@mit.edu> | |
f6903667 | 7 | * |
96a1ee0f | 8 | * This file is part of nss_nonlocal. |
f6903667 | 9 | * |
96a1ee0f AK |
10 | * nss_nonlocal is free software; you can redistribute it and/or |
11 | * modify it under the terms of the GNU Lesser General Public License | |
12 | * as published by the Free Software Foundation; either version 2.1 of | |
13 | * the License, or (at your option) any later version. | |
f6903667 | 14 | * |
96a1ee0f AK |
15 | * nss_nonlocal is distributed in the hope that it will be useful, but |
16 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * Lesser General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU Lesser General Public | |
21 | * License along with nss_nonlocal; if not, write to the Free Software | |
22 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA | |
23 | * 02110-1301 USA | |
f6903667 AK |
24 | */ |
25 | ||
26 | ||
27 | #define _GNU_SOURCE | |
28 | #include <sys/types.h> | |
29 | #include <unistd.h> | |
30 | #include <stdlib.h> | |
31 | #include <stdint.h> | |
32 | #include <string.h> | |
33 | #include <dlfcn.h> | |
34 | #include <stdio.h> | |
35 | #include <syslog.h> | |
36 | #include <errno.h> | |
37 | #include <pwd.h> | |
38 | #include <grp.h> | |
39 | #include <nss.h> | |
40 | #include "nsswitch-internal.h" | |
41 | #include "nonlocal.h" | |
42 | ||
c1812233 AK |
43 | |
44 | enum nss_status | |
45 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
46 | char *buffer, size_t buflen, int *errnop); | |
47 | enum nss_status | |
48 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
49 | char *buffer, size_t buflen, int *errnop); | |
f7293a54 | 50 | |
f6903667 AK |
51 | |
52 | static service_user * | |
53 | nss_passwd_nonlocal_database(void) | |
54 | { | |
55 | static service_user *nip = NULL; | |
56 | if (nip == NULL) | |
57 | __nss_database_lookup("passwd_nonlocal", NULL, "", &nip); | |
58 | ||
59 | return nip; | |
60 | } | |
61 | ||
62 | ||
f6903667 AK |
63 | enum nss_status |
64 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
65 | { | |
30fb3957 AK |
66 | static const char *fct_name = "getpwuid_r"; |
67 | static service_user *startp = NULL; | |
68 | static void *fct_start = NULL; | |
69 | enum nss_status status; | |
70 | service_user *nip; | |
71 | union { | |
72 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
73 | char *buffer, size_t buflen, int *errnop); | |
74 | void *ptr; | |
75 | } fct; | |
f7293a54 | 76 | struct passwd pwbuf; |
f7293a54 | 77 | int old_errno = errno; |
c1812233 | 78 | |
8870ee9c | 79 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
f7293a54 AK |
80 | char *buf = malloc(buflen); |
81 | if (buf == NULL) { | |
f6903667 | 82 | *errnop = ENOMEM; |
f7293a54 | 83 | errno = old_errno; |
f6903667 AK |
84 | return NSS_STATUS_TRYAGAIN; |
85 | } | |
30fb3957 AK |
86 | |
87 | if (fct_start == NULL && | |
88 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
89 | free(buf); | |
90 | return NSS_STATUS_UNAVAIL; | |
91 | } | |
92 | nip = startp; | |
93 | fct.ptr = fct_start; | |
94 | do { | |
d905b369 | 95 | morebuf: |
c1812233 AK |
96 | if (fct.l == _nss_nonlocal_getpwuid_r) |
97 | status = NSS_STATUS_NOTFOUND; | |
98 | else | |
99 | status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
100 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
101 | free(buf); | |
102 | buflen *= 2; | |
103 | buf = malloc(buflen); | |
104 | if (buf == NULL) { | |
105 | *errnop = ENOMEM; | |
106 | errno = old_errno; | |
107 | return NSS_STATUS_TRYAGAIN; | |
108 | } | |
109 | goto morebuf; | |
110 | } | |
30fb3957 AK |
111 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
112 | ||
113 | if (status == NSS_STATUS_SUCCESS) { | |
f7293a54 | 114 | 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 | 115 | status = NSS_STATUS_NOTFOUND; |
30fb3957 AK |
116 | } else if (status != NSS_STATUS_TRYAGAIN) { |
117 | status = NSS_STATUS_SUCCESS; | |
f6903667 | 118 | } |
30fb3957 | 119 | |
f7293a54 | 120 | free(buf); |
f6903667 AK |
121 | return status; |
122 | } | |
123 | ||
cf338316 AK |
124 | enum nss_status |
125 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
126 | { | |
a07a7616 AK |
127 | enum nss_status status = NSS_STATUS_SUCCESS; |
128 | int old_errno = errno; | |
129 | char *end; | |
130 | unsigned long uid; | |
131 | ||
132 | errno = 0; | |
133 | uid = strtoul(pwd->pw_name, &end, 10); | |
134 | if (errno == 0 && *end == '\0' && (uid_t)uid == uid) | |
135 | status = check_nonlocal_uid(user, uid, errnop); | |
136 | errno = old_errno; | |
137 | if (status != NSS_STATUS_SUCCESS) | |
138 | return status; | |
139 | ||
cf338316 AK |
140 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); |
141 | } | |
142 | ||
48479fc7 TA |
143 | enum nss_status |
144 | check_nonlocal_user(const char *user, int *errnop) | |
145 | { | |
30fb3957 AK |
146 | static const char *fct_name = "getpwnam_r"; |
147 | static service_user *startp = NULL; | |
148 | static void *fct_start = NULL; | |
149 | enum nss_status status; | |
150 | service_user *nip; | |
151 | union { | |
152 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
153 | char *buffer, size_t buflen, int *errnop); | |
154 | void *ptr; | |
155 | } fct; | |
48479fc7 | 156 | struct passwd pwbuf; |
48479fc7 | 157 | int old_errno = errno; |
c1812233 | 158 | |
8870ee9c | 159 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
48479fc7 TA |
160 | char *buf = malloc(buflen); |
161 | if (buf == NULL) { | |
162 | *errnop = ENOMEM; | |
163 | errno = old_errno; | |
164 | return NSS_STATUS_TRYAGAIN; | |
165 | } | |
30fb3957 AK |
166 | |
167 | if (fct_start == NULL && | |
168 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
169 | free(buf); | |
170 | return NSS_STATUS_UNAVAIL; | |
48479fc7 | 171 | } |
30fb3957 AK |
172 | nip = startp; |
173 | fct.ptr = fct_start; | |
174 | do { | |
d905b369 | 175 | morebuf: |
c1812233 AK |
176 | if (fct.l == _nss_nonlocal_getpwnam_r) |
177 | status = NSS_STATUS_NOTFOUND; | |
178 | else | |
179 | status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
180 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
181 | free(buf); | |
182 | buflen *= 2; | |
183 | buf = malloc(buflen); | |
184 | if (buf == NULL) { | |
185 | *errnop = ENOMEM; | |
186 | errno = old_errno; | |
187 | return NSS_STATUS_TRYAGAIN; | |
188 | } | |
189 | goto morebuf; | |
190 | } | |
30fb3957 AK |
191 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
192 | ||
193 | if (status == NSS_STATUS_SUCCESS) | |
194 | status = NSS_STATUS_NOTFOUND; | |
195 | else if (status != NSS_STATUS_TRYAGAIN) | |
196 | status = NSS_STATUS_SUCCESS; | |
197 | ||
48479fc7 | 198 | free(buf); |
48479fc7 TA |
199 | return status; |
200 | } | |
f6903667 | 201 | |
1e78305d | 202 | |
f6903667 AK |
203 | static service_user *pwent_nip = NULL; |
204 | static void *pwent_fct_start; | |
205 | static union { | |
206 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
207 | int *errnop); | |
208 | void *ptr; | |
209 | } pwent_fct; | |
210 | static const char *pwent_fct_name = "getpwent_r"; | |
211 | ||
212 | enum nss_status | |
213 | _nss_nonlocal_setpwent(int stayopen) | |
214 | { | |
215 | static const char *fct_name = "setpwent"; | |
216 | static void *fct_start = NULL; | |
217 | enum nss_status status; | |
218 | service_user *nip; | |
219 | union { | |
220 | enum nss_status (*l)(int stayopen); | |
221 | void *ptr; | |
222 | } fct; | |
223 | ||
224 | nip = nss_passwd_nonlocal_database(); | |
225 | if (nip == NULL) | |
226 | return NSS_STATUS_UNAVAIL; | |
227 | if (fct_start == NULL) | |
228 | fct_start = __nss_lookup_function(nip, fct_name); | |
229 | fct.ptr = fct_start; | |
230 | do { | |
231 | if (fct.ptr == NULL) | |
232 | status = NSS_STATUS_UNAVAIL; | |
233 | else | |
234 | status = DL_CALL_FCT(fct.l, (stayopen)); | |
235 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
236 | if (status != NSS_STATUS_SUCCESS) | |
237 | return status; | |
238 | ||
239 | pwent_nip = nip; | |
240 | if (pwent_fct_start == NULL) | |
241 | pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name); | |
242 | pwent_fct.ptr = pwent_fct_start; | |
243 | return NSS_STATUS_SUCCESS; | |
244 | } | |
245 | ||
246 | enum nss_status | |
247 | _nss_nonlocal_endpwent(void) | |
248 | { | |
249 | static const char *fct_name = "endpwent"; | |
250 | static void *fct_start = NULL; | |
251 | enum nss_status status; | |
252 | service_user *nip; | |
253 | union { | |
254 | enum nss_status (*l)(void); | |
255 | void *ptr; | |
256 | } fct; | |
257 | ||
258 | pwent_nip = NULL; | |
259 | ||
260 | nip = nss_passwd_nonlocal_database(); | |
261 | if (nip == NULL) | |
262 | return NSS_STATUS_UNAVAIL; | |
263 | if (fct_start == NULL) | |
264 | fct_start = __nss_lookup_function(nip, fct_name); | |
265 | fct.ptr = fct_start; | |
266 | do { | |
267 | if (fct.ptr == NULL) | |
268 | status = NSS_STATUS_UNAVAIL; | |
269 | else | |
270 | status = DL_CALL_FCT(fct.l, ()); | |
271 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
272 | return status; | |
273 | } | |
274 | ||
275 | enum nss_status | |
276 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
277 | int *errnop) | |
278 | { | |
279 | enum nss_status status; | |
a360549e TA |
280 | |
281 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
c1812233 | 282 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
a360549e TA |
283 | return NSS_STATUS_UNAVAIL; |
284 | ||
f6903667 AK |
285 | if (pwent_nip == NULL) { |
286 | status = _nss_nonlocal_setpwent(0); | |
287 | if (status != NSS_STATUS_SUCCESS) | |
288 | return status; | |
289 | } | |
290 | do { | |
291 | if (pwent_fct.ptr == NULL) | |
292 | status = NSS_STATUS_UNAVAIL; | |
293 | else { | |
294 | int nonlocal_errno; | |
295 | do | |
a360549e | 296 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); |
f6903667 | 297 | while (status == NSS_STATUS_SUCCESS && |
cf338316 | 298 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); |
f6903667 AK |
299 | } |
300 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
301 | return status; | |
302 | ||
303 | if (status == NSS_STATUS_SUCCESS) | |
304 | return NSS_STATUS_SUCCESS; | |
305 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
306 | ||
307 | pwent_nip = NULL; | |
308 | return NSS_STATUS_NOTFOUND; | |
309 | } | |
310 | ||
311 | ||
312 | enum nss_status | |
313 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
314 | char *buffer, size_t buflen, int *errnop) | |
315 | { | |
316 | static const char *fct_name = "getpwnam_r"; | |
317 | static void *fct_start = NULL; | |
318 | enum nss_status status; | |
319 | service_user *nip; | |
320 | union { | |
321 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
322 | char *buffer, size_t buflen, int *errnop); | |
323 | void *ptr; | |
324 | } fct; | |
325 | int group_errno; | |
326 | ||
a360549e | 327 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 328 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
48479fc7 TA |
329 | return NSS_STATUS_UNAVAIL; |
330 | ||
f6903667 AK |
331 | nip = nss_passwd_nonlocal_database(); |
332 | if (nip == NULL) | |
333 | return NSS_STATUS_UNAVAIL; | |
334 | if (fct_start == NULL) | |
335 | fct_start = __nss_lookup_function(nip, fct_name); | |
336 | fct.ptr = fct_start; | |
337 | do { | |
338 | if (fct.ptr == NULL) | |
339 | status = NSS_STATUS_UNAVAIL; | |
340 | else | |
341 | status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop)); | |
342 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
343 | break; | |
344 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
345 | if (status != NSS_STATUS_SUCCESS) | |
346 | return status; | |
347 | ||
22562df0 AK |
348 | if (strcmp(name, pwd->pw_name) != 0) { |
349 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
350 | return NSS_STATUS_NOTFOUND; | |
351 | } | |
352 | ||
cf338316 | 353 | status = check_nonlocal_passwd(name, pwd, errnop); |
f6903667 AK |
354 | if (status != NSS_STATUS_SUCCESS) |
355 | return status; | |
356 | ||
357 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
358 | NSS_STATUS_SUCCESS) | |
359 | pwd->pw_gid = 65534 /* nogroup */; | |
360 | return NSS_STATUS_SUCCESS; | |
361 | } | |
362 | ||
363 | enum nss_status | |
364 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
365 | char *buffer, size_t buflen, int *errnop) | |
366 | { | |
367 | static const char *fct_name = "getpwuid_r"; | |
368 | static void *fct_start = NULL; | |
369 | enum nss_status status; | |
370 | service_user *nip; | |
371 | union { | |
372 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
373 | char *buffer, size_t buflen, int *errnop); | |
374 | void *ptr; | |
375 | } fct; | |
376 | int group_errno; | |
377 | ||
a360549e | 378 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 379 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
f6903667 AK |
380 | return NSS_STATUS_UNAVAIL; |
381 | ||
382 | nip = nss_passwd_nonlocal_database(); | |
383 | if (nip == NULL) | |
384 | return NSS_STATUS_UNAVAIL; | |
385 | if (fct_start == NULL) | |
386 | fct_start = __nss_lookup_function(nip, fct_name); | |
387 | fct.ptr = fct_start; | |
388 | do { | |
389 | if (fct.ptr == NULL) | |
390 | status = NSS_STATUS_UNAVAIL; | |
391 | else | |
392 | status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop)); | |
393 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
394 | break; | |
395 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
396 | if (status != NSS_STATUS_SUCCESS) | |
397 | return status; | |
398 | ||
8027fdc4 AK |
399 | if (uid != pwd->pw_uid) { |
400 | syslog(LOG_ERR, "nss_nonlocal: discarding uid %d from lookup for uid %d\n", pwd->pw_uid, uid); | |
401 | return NSS_STATUS_NOTFOUND; | |
402 | } | |
403 | ||
cf338316 | 404 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); |
f6903667 AK |
405 | if (status != NSS_STATUS_SUCCESS) |
406 | return status; | |
407 | ||
408 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
409 | NSS_STATUS_SUCCESS) | |
410 | pwd->pw_gid = 65534 /* nogroup */; | |
411 | return NSS_STATUS_SUCCESS; | |
412 | } |