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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 |
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 | ||
c1812233 AK |
46 | |
47 | enum nss_status | |
48 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
49 | char *buffer, size_t buflen, int *errnop); | |
50 | enum nss_status | |
51 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
52 | char *buffer, size_t buflen, int *errnop); | |
f7293a54 | 53 | |
f6903667 AK |
54 | |
55 | static service_user * | |
56 | nss_passwd_nonlocal_database(void) | |
57 | { | |
58 | static service_user *nip = NULL; | |
59 | if (nip == NULL) | |
60 | __nss_database_lookup("passwd_nonlocal", NULL, "", &nip); | |
61 | ||
62 | return nip; | |
63 | } | |
64 | ||
65 | ||
f6903667 AK |
66 | enum nss_status |
67 | check_nonlocal_uid(const char *user, uid_t uid, int *errnop) | |
68 | { | |
30fb3957 AK |
69 | static const char *fct_name = "getpwuid_r"; |
70 | static service_user *startp = NULL; | |
71 | static void *fct_start = NULL; | |
72 | enum nss_status status; | |
73 | service_user *nip; | |
74 | union { | |
75 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
76 | char *buffer, size_t buflen, int *errnop); | |
77 | void *ptr; | |
78 | } fct; | |
f7293a54 | 79 | struct passwd pwbuf; |
f7293a54 | 80 | int old_errno = errno; |
c1812233 | 81 | |
8870ee9c | 82 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
f7293a54 AK |
83 | char *buf = malloc(buflen); |
84 | if (buf == NULL) { | |
f6903667 | 85 | *errnop = ENOMEM; |
f7293a54 | 86 | errno = old_errno; |
f6903667 AK |
87 | return NSS_STATUS_TRYAGAIN; |
88 | } | |
30fb3957 AK |
89 | |
90 | if (fct_start == NULL && | |
91 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
92 | free(buf); | |
93 | return NSS_STATUS_UNAVAIL; | |
94 | } | |
95 | nip = startp; | |
96 | fct.ptr = fct_start; | |
97 | do { | |
d905b369 | 98 | morebuf: |
c1812233 AK |
99 | if (fct.l == _nss_nonlocal_getpwuid_r) |
100 | status = NSS_STATUS_NOTFOUND; | |
101 | else | |
102 | status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
103 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
104 | free(buf); | |
105 | buflen *= 2; | |
106 | buf = malloc(buflen); | |
107 | if (buf == NULL) { | |
108 | *errnop = ENOMEM; | |
109 | errno = old_errno; | |
110 | return NSS_STATUS_TRYAGAIN; | |
111 | } | |
112 | goto morebuf; | |
113 | } | |
30fb3957 AK |
114 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
115 | ||
116 | if (status == NSS_STATUS_SUCCESS) { | |
f7293a54 | 117 | 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 | 118 | status = NSS_STATUS_NOTFOUND; |
30fb3957 AK |
119 | } else if (status != NSS_STATUS_TRYAGAIN) { |
120 | status = NSS_STATUS_SUCCESS; | |
f6903667 | 121 | } |
30fb3957 | 122 | |
f7293a54 | 123 | free(buf); |
f6903667 AK |
124 | return status; |
125 | } | |
126 | ||
cf338316 AK |
127 | enum nss_status |
128 | check_nonlocal_passwd(const char *user, struct passwd *pwd, int *errnop) | |
129 | { | |
a07a7616 AK |
130 | enum nss_status status = NSS_STATUS_SUCCESS; |
131 | int old_errno = errno; | |
132 | char *end; | |
133 | unsigned long uid; | |
134 | ||
135 | errno = 0; | |
136 | uid = strtoul(pwd->pw_name, &end, 10); | |
137 | if (errno == 0 && *end == '\0' && (uid_t)uid == uid) | |
138 | status = check_nonlocal_uid(user, uid, errnop); | |
139 | errno = old_errno; | |
140 | if (status != NSS_STATUS_SUCCESS) | |
141 | return status; | |
142 | ||
cf338316 AK |
143 | return check_nonlocal_uid(user, pwd->pw_uid, errnop); |
144 | } | |
145 | ||
48479fc7 TA |
146 | enum nss_status |
147 | check_nonlocal_user(const char *user, int *errnop) | |
148 | { | |
30fb3957 AK |
149 | static const char *fct_name = "getpwnam_r"; |
150 | static service_user *startp = NULL; | |
151 | static void *fct_start = NULL; | |
152 | enum nss_status status; | |
153 | service_user *nip; | |
154 | union { | |
155 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
156 | char *buffer, size_t buflen, int *errnop); | |
157 | void *ptr; | |
158 | } fct; | |
48479fc7 | 159 | struct passwd pwbuf; |
48479fc7 | 160 | int old_errno = errno; |
c1812233 | 161 | |
8870ee9c | 162 | size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); |
48479fc7 TA |
163 | char *buf = malloc(buflen); |
164 | if (buf == NULL) { | |
165 | *errnop = ENOMEM; | |
166 | errno = old_errno; | |
167 | return NSS_STATUS_TRYAGAIN; | |
168 | } | |
30fb3957 AK |
169 | |
170 | if (fct_start == NULL && | |
171 | __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { | |
172 | free(buf); | |
173 | return NSS_STATUS_UNAVAIL; | |
48479fc7 | 174 | } |
30fb3957 AK |
175 | nip = startp; |
176 | fct.ptr = fct_start; | |
177 | do { | |
d905b369 | 178 | morebuf: |
c1812233 AK |
179 | if (fct.l == _nss_nonlocal_getpwnam_r) |
180 | status = NSS_STATUS_NOTFOUND; | |
181 | else | |
182 | status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); | |
d905b369 AK |
183 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { |
184 | free(buf); | |
185 | buflen *= 2; | |
186 | buf = malloc(buflen); | |
187 | if (buf == NULL) { | |
188 | *errnop = ENOMEM; | |
189 | errno = old_errno; | |
190 | return NSS_STATUS_TRYAGAIN; | |
191 | } | |
192 | goto morebuf; | |
193 | } | |
30fb3957 AK |
194 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); |
195 | ||
196 | if (status == NSS_STATUS_SUCCESS) | |
197 | status = NSS_STATUS_NOTFOUND; | |
198 | else if (status != NSS_STATUS_TRYAGAIN) | |
199 | status = NSS_STATUS_SUCCESS; | |
200 | ||
48479fc7 | 201 | free(buf); |
48479fc7 TA |
202 | return status; |
203 | } | |
f6903667 | 204 | |
1e78305d | 205 | |
f6903667 AK |
206 | static service_user *pwent_nip = NULL; |
207 | static void *pwent_fct_start; | |
208 | static union { | |
209 | enum nss_status (*l)(struct passwd *pwd, char *buffer, size_t buflen, | |
210 | int *errnop); | |
211 | void *ptr; | |
212 | } pwent_fct; | |
213 | static const char *pwent_fct_name = "getpwent_r"; | |
214 | ||
215 | enum nss_status | |
216 | _nss_nonlocal_setpwent(int stayopen) | |
217 | { | |
218 | static const char *fct_name = "setpwent"; | |
219 | static void *fct_start = NULL; | |
220 | enum nss_status status; | |
221 | service_user *nip; | |
222 | union { | |
223 | enum nss_status (*l)(int stayopen); | |
224 | void *ptr; | |
225 | } fct; | |
226 | ||
227 | nip = nss_passwd_nonlocal_database(); | |
228 | if (nip == NULL) | |
229 | return NSS_STATUS_UNAVAIL; | |
230 | if (fct_start == NULL) | |
231 | fct_start = __nss_lookup_function(nip, fct_name); | |
232 | fct.ptr = fct_start; | |
233 | do { | |
234 | if (fct.ptr == NULL) | |
235 | status = NSS_STATUS_UNAVAIL; | |
236 | else | |
237 | status = DL_CALL_FCT(fct.l, (stayopen)); | |
238 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
239 | if (status != NSS_STATUS_SUCCESS) | |
240 | return status; | |
241 | ||
242 | pwent_nip = nip; | |
243 | if (pwent_fct_start == NULL) | |
244 | pwent_fct_start = __nss_lookup_function(nip, pwent_fct_name); | |
245 | pwent_fct.ptr = pwent_fct_start; | |
246 | return NSS_STATUS_SUCCESS; | |
247 | } | |
248 | ||
249 | enum nss_status | |
250 | _nss_nonlocal_endpwent(void) | |
251 | { | |
252 | static const char *fct_name = "endpwent"; | |
253 | static void *fct_start = NULL; | |
254 | enum nss_status status; | |
255 | service_user *nip; | |
256 | union { | |
257 | enum nss_status (*l)(void); | |
258 | void *ptr; | |
259 | } fct; | |
260 | ||
261 | pwent_nip = NULL; | |
262 | ||
263 | nip = nss_passwd_nonlocal_database(); | |
264 | if (nip == NULL) | |
265 | return NSS_STATUS_UNAVAIL; | |
266 | if (fct_start == NULL) | |
267 | fct_start = __nss_lookup_function(nip, fct_name); | |
268 | fct.ptr = fct_start; | |
269 | do { | |
270 | if (fct.ptr == NULL) | |
271 | status = NSS_STATUS_UNAVAIL; | |
272 | else | |
273 | status = DL_CALL_FCT(fct.l, ()); | |
274 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
275 | return status; | |
276 | } | |
277 | ||
278 | enum nss_status | |
279 | _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, | |
280 | int *errnop) | |
281 | { | |
282 | enum nss_status status; | |
a360549e TA |
283 | |
284 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
c1812233 | 285 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
a360549e TA |
286 | return NSS_STATUS_UNAVAIL; |
287 | ||
f6903667 AK |
288 | if (pwent_nip == NULL) { |
289 | status = _nss_nonlocal_setpwent(0); | |
290 | if (status != NSS_STATUS_SUCCESS) | |
291 | return status; | |
292 | } | |
293 | do { | |
294 | if (pwent_fct.ptr == NULL) | |
295 | status = NSS_STATUS_UNAVAIL; | |
296 | else { | |
297 | int nonlocal_errno; | |
298 | do | |
a360549e | 299 | status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); |
f6903667 | 300 | while (status == NSS_STATUS_SUCCESS && |
cf338316 | 301 | check_nonlocal_passwd(pwd->pw_name, pwd, &nonlocal_errno) != NSS_STATUS_SUCCESS); |
f6903667 AK |
302 | } |
303 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
304 | return status; | |
305 | ||
306 | if (status == NSS_STATUS_SUCCESS) | |
307 | return NSS_STATUS_SUCCESS; | |
308 | } while (__nss_next(&pwent_nip, pwent_fct_name, &pwent_fct.ptr, status, 0) == 0); | |
309 | ||
310 | pwent_nip = NULL; | |
311 | return NSS_STATUS_NOTFOUND; | |
312 | } | |
313 | ||
314 | ||
315 | enum nss_status | |
316 | _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, | |
317 | char *buffer, size_t buflen, int *errnop) | |
318 | { | |
319 | static const char *fct_name = "getpwnam_r"; | |
320 | static void *fct_start = NULL; | |
321 | enum nss_status status; | |
322 | service_user *nip; | |
323 | union { | |
324 | enum nss_status (*l)(const char *name, struct passwd *pwd, | |
325 | char *buffer, size_t buflen, int *errnop); | |
326 | void *ptr; | |
327 | } fct; | |
328 | int group_errno; | |
329 | ||
a360549e | 330 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 331 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
48479fc7 TA |
332 | return NSS_STATUS_UNAVAIL; |
333 | ||
f6903667 AK |
334 | nip = nss_passwd_nonlocal_database(); |
335 | if (nip == NULL) | |
336 | return NSS_STATUS_UNAVAIL; | |
337 | if (fct_start == NULL) | |
338 | fct_start = __nss_lookup_function(nip, fct_name); | |
339 | fct.ptr = fct_start; | |
340 | do { | |
341 | if (fct.ptr == NULL) | |
342 | status = NSS_STATUS_UNAVAIL; | |
343 | else | |
344 | status = DL_CALL_FCT(fct.l, (name, pwd, buffer, buflen, errnop)); | |
345 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
346 | break; | |
347 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
348 | if (status != NSS_STATUS_SUCCESS) | |
349 | return status; | |
350 | ||
22562df0 AK |
351 | if (strcmp(name, pwd->pw_name) != 0) { |
352 | syslog(LOG_ERR, "nss_nonlocal: discarding user %s from lookup for user %s\n", pwd->pw_name, name); | |
353 | return NSS_STATUS_NOTFOUND; | |
354 | } | |
355 | ||
cf338316 | 356 | status = check_nonlocal_passwd(name, pwd, errnop); |
f6903667 AK |
357 | if (status != NSS_STATUS_SUCCESS) |
358 | return status; | |
359 | ||
360 | if (check_nonlocal_gid(name, pwd->pw_gid, &group_errno) != | |
361 | NSS_STATUS_SUCCESS) | |
362 | pwd->pw_gid = 65534 /* nogroup */; | |
363 | return NSS_STATUS_SUCCESS; | |
364 | } | |
365 | ||
366 | enum nss_status | |
367 | _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, | |
368 | char *buffer, size_t buflen, int *errnop) | |
369 | { | |
370 | static const char *fct_name = "getpwuid_r"; | |
371 | static void *fct_start = NULL; | |
372 | enum nss_status status; | |
373 | service_user *nip; | |
374 | union { | |
375 | enum nss_status (*l)(uid_t uid, struct passwd *pwd, | |
376 | char *buffer, size_t buflen, int *errnop); | |
377 | void *ptr; | |
378 | } fct; | |
379 | int group_errno; | |
380 | ||
a360549e | 381 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); |
c1812233 | 382 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') |
f6903667 AK |
383 | return NSS_STATUS_UNAVAIL; |
384 | ||
385 | nip = nss_passwd_nonlocal_database(); | |
386 | if (nip == NULL) | |
387 | return NSS_STATUS_UNAVAIL; | |
388 | if (fct_start == NULL) | |
389 | fct_start = __nss_lookup_function(nip, fct_name); | |
390 | fct.ptr = fct_start; | |
391 | do { | |
392 | if (fct.ptr == NULL) | |
393 | status = NSS_STATUS_UNAVAIL; | |
394 | else | |
395 | status = DL_CALL_FCT(fct.l, (uid, pwd, buffer, buflen, errnop)); | |
396 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
397 | break; | |
398 | } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); | |
399 | if (status != NSS_STATUS_SUCCESS) | |
400 | return status; | |
401 | ||
cf338316 | 402 | status = check_nonlocal_passwd(pwd->pw_name, pwd, errnop); |
f6903667 AK |
403 | if (status != NSS_STATUS_SUCCESS) |
404 | return status; | |
405 | ||
406 | if (check_nonlocal_gid(pwd->pw_name, pwd->pw_gid, &group_errno) != | |
407 | NSS_STATUS_SUCCESS) | |
408 | pwd->pw_gid = 65534 /* nogroup */; | |
409 | return NSS_STATUS_SUCCESS; | |
410 | } |