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1 | /* | |
2 | * nonlocal-group.c | |
3 | * group database for nss_nonlocal proxy | |
4 | * | |
5 | * Copyright © 2007–2010 Anders Kaseorg <andersk@mit.edu> and Tim | |
6 | * Abbott <tabbott@mit.edu> | |
7 | * | |
8 | * This file is part of nss_nonlocal. | |
9 | * | |
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. | |
14 | * | |
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 | |
24 | */ | |
25 | ||
26 | #define _GNU_SOURCE | |
27 | ||
28 | #include <sys/types.h> | |
29 | #include <dlfcn.h> | |
30 | #include <errno.h> | |
31 | #include <grp.h> | |
32 | #include <nss.h> | |
33 | #include <pwd.h> | |
34 | #include <stdbool.h> | |
35 | #include <stddef.h> | |
36 | #include <stdlib.h> | |
37 | #include <string.h> | |
38 | #include <syslog.h> | |
39 | #include <unistd.h> | |
40 | ||
41 | #include "nsswitch-internal.h" | |
42 | #include "nonlocal.h" | |
43 | ||
44 | /* | |
45 | * If the MAGIC_NONLOCAL_GROUPNAME local group exists, then nonlocal | |
46 | * users will be automatically added to it. Furthermore, if a local | |
47 | * user is added to this group, then that user will inherit any | |
48 | * nonlocal gids from a nonlocal user of the same name, as | |
49 | * supplementary gids. | |
50 | */ | |
51 | #define MAGIC_NONLOCAL_GROUPNAME "nss-nonlocal-users" | |
52 | ||
53 | /* | |
54 | * If the MAGIC_LOCAL_GROUPNAME local group exists, then local users | |
55 | * will be automatically added to it. | |
56 | */ | |
57 | #define MAGIC_LOCAL_GROUPNAME "nss-local-users" | |
58 | ||
59 | /* | |
60 | * If the MAGIC_NONLOCAL_USERNAME local user is added to a local | |
61 | * group, then the local group will inherit the nonlocal membership of | |
62 | * a group of the same gid. | |
63 | */ | |
64 | #define MAGIC_NONLOCAL_USERNAME "nss-nonlocal-users" | |
65 | ||
66 | ||
67 | enum nss_status | |
68 | _nss_nonlocal_getgrnam_r(const char *name, struct group *grp, | |
69 | char *buffer, size_t buflen, int *errnop); | |
70 | ||
71 | enum nss_status | |
72 | _nss_nonlocal_getgrgid_r(gid_t gid, struct group *grp, | |
73 | char *buffer, size_t buflen, int *errnop); | |
74 | ||
75 | ||
76 | static service_user *__nss_group_nonlocal_database; | |
77 | ||
78 | static int | |
79 | internal_function | |
80 | __nss_group_nonlocal_lookup(service_user **ni, const char *fct_name, | |
81 | void **fctp) | |
82 | { | |
83 | if (__nss_group_nonlocal_database == NULL | |
84 | && __nss_database_lookup("group_nonlocal", NULL, NULL, | |
85 | &__nss_group_nonlocal_database) < 0) | |
86 | return -1; | |
87 | ||
88 | *ni = __nss_group_nonlocal_database; | |
89 | ||
90 | *fctp = __nss_lookup_function(*ni, fct_name); | |
91 | return 0; | |
92 | } | |
93 | ||
94 | ||
95 | enum nss_status | |
96 | check_nonlocal_gid(const char *user, const char *group, gid_t gid, int *errnop) | |
97 | { | |
98 | enum nss_status status; | |
99 | struct group gbuf; | |
100 | char *buf; | |
101 | size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX); | |
102 | const struct walk_nss w = { | |
103 | .lookup = &__nss_group_lookup, .fct_name = "getgrgid_r", | |
104 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
105 | }; | |
106 | const __typeof__(&_nss_nonlocal_getgrgid_r) self = &_nss_nonlocal_getgrgid_r; | |
107 | #define args (gid, &gbuf, buf, buflen, errnop) | |
108 | #include "walk_nss.h" | |
109 | #undef args | |
110 | ||
111 | if (status == NSS_STATUS_TRYAGAIN) | |
112 | return status; | |
113 | else if (status != NSS_STATUS_SUCCESS) | |
114 | return NSS_STATUS_SUCCESS; | |
115 | ||
116 | if (group == NULL || strcmp(gbuf.gr_name, group) == 0) { | |
117 | char *const *mem; | |
118 | for (mem = gbuf.gr_mem; *mem != NULL; mem++) | |
119 | if (strcmp(*mem, MAGIC_NONLOCAL_USERNAME) == 0) { | |
120 | status = check_nonlocal_user(*mem, errnop); | |
121 | if (status == NSS_STATUS_TRYAGAIN) { | |
122 | free(buf); | |
123 | return status; | |
124 | } else if (status == NSS_STATUS_NOTFOUND) { | |
125 | free(buf); | |
126 | return NSS_STATUS_SUCCESS; | |
127 | } | |
128 | break; | |
129 | } | |
130 | } | |
131 | ||
132 | syslog(LOG_DEBUG, "nss_nonlocal: removing local group %u (%s) from non-local user %s\n", gbuf.gr_gid, gbuf.gr_name, user); | |
133 | free(buf); | |
134 | return NSS_STATUS_NOTFOUND; | |
135 | } | |
136 | ||
137 | enum nss_status | |
138 | check_nonlocal_group(const char *user, struct group *grp, int *errnop) | |
139 | { | |
140 | enum nss_status status = NSS_STATUS_SUCCESS; | |
141 | int old_errno = errno; | |
142 | char *end; | |
143 | unsigned long gid; | |
144 | ||
145 | errno = 0; | |
146 | gid = strtoul(grp->gr_name, &end, 10); | |
147 | if (errno == 0 && *end == '\0' && (gid_t)gid == gid) { | |
148 | errno = old_errno; | |
149 | status = check_nonlocal_gid(user, grp->gr_name, gid, errnop); | |
150 | } else | |
151 | errno = old_errno; | |
152 | if (status != NSS_STATUS_SUCCESS) | |
153 | return status; | |
154 | ||
155 | return check_nonlocal_gid(user, grp->gr_name, grp->gr_gid, errnop); | |
156 | } | |
157 | ||
158 | enum nss_status | |
159 | get_local_group(const char *name, struct group *grp, char **buffer, int *errnop) | |
160 | { | |
161 | enum nss_status status; | |
162 | size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX); | |
163 | const struct walk_nss w = { | |
164 | .lookup = &__nss_group_lookup, .fct_name = "getgrnam_r", | |
165 | .status = &status, .errnop = errnop, .buf = buffer, .buflen = &buflen | |
166 | }; | |
167 | const __typeof__(&_nss_nonlocal_getgrnam_r) self = &_nss_nonlocal_getgrnam_r; | |
168 | #define args (name, grp, *buffer, buflen, errnop) | |
169 | #include "walk_nss.h" | |
170 | #undef args | |
171 | return status; | |
172 | } | |
173 | ||
174 | static bool grent_initialized = false; | |
175 | static service_user *grent_startp, *grent_nip; | |
176 | static void *grent_fct_start; | |
177 | static union { | |
178 | enum nss_status (*l)(struct group *grp, char *buffer, size_t buflen, | |
179 | int *errnop); | |
180 | void *ptr; | |
181 | } grent_fct; | |
182 | static const char *grent_fct_name = "getgrent_r"; | |
183 | ||
184 | enum nss_status | |
185 | _nss_nonlocal_setgrent(int stayopen) | |
186 | { | |
187 | enum nss_status status; | |
188 | const struct walk_nss w = { | |
189 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "setgrent", | |
190 | .status = &status | |
191 | }; | |
192 | const __typeof__(&_nss_nonlocal_setgrent) self = NULL; | |
193 | #define args (stayopen) | |
194 | #include "walk_nss.h" | |
195 | #undef args | |
196 | if (status != NSS_STATUS_SUCCESS) | |
197 | return status; | |
198 | ||
199 | if (!grent_initialized) { | |
200 | __nss_group_nonlocal_lookup(&grent_startp, grent_fct_name, | |
201 | &grent_fct_start); | |
202 | __sync_synchronize(); | |
203 | grent_initialized = true; | |
204 | } | |
205 | grent_nip = grent_startp; | |
206 | grent_fct.ptr = grent_fct_start; | |
207 | return NSS_STATUS_SUCCESS; | |
208 | } | |
209 | ||
210 | enum nss_status | |
211 | _nss_nonlocal_endgrent(void) | |
212 | { | |
213 | enum nss_status status; | |
214 | const struct walk_nss w = { | |
215 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "endgrent", | |
216 | .status = &status | |
217 | }; | |
218 | const __typeof__(&_nss_nonlocal_endgrent) self = NULL; | |
219 | ||
220 | grent_nip = NULL; | |
221 | ||
222 | #define args () | |
223 | #include "walk_nss.h" | |
224 | #undef args | |
225 | return status; | |
226 | } | |
227 | ||
228 | enum nss_status | |
229 | _nss_nonlocal_getgrent_r(struct group *grp, char *buffer, size_t buflen, | |
230 | int *errnop) | |
231 | { | |
232 | enum nss_status status; | |
233 | ||
234 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
235 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
236 | return NSS_STATUS_UNAVAIL; | |
237 | ||
238 | if (grent_nip == NULL) { | |
239 | status = _nss_nonlocal_setgrent(0); | |
240 | if (status != NSS_STATUS_SUCCESS) | |
241 | return status; | |
242 | } | |
243 | do { | |
244 | if (grent_fct.ptr == NULL) | |
245 | status = NSS_STATUS_UNAVAIL; | |
246 | else { | |
247 | int nonlocal_errno; | |
248 | do | |
249 | status = DL_CALL_FCT(grent_fct.l, (grp, buffer, buflen, errnop)); | |
250 | while (status == NSS_STATUS_SUCCESS && | |
251 | check_nonlocal_group("(unknown)", grp, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
252 | } | |
253 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
254 | return status; | |
255 | ||
256 | if (status == NSS_STATUS_SUCCESS) | |
257 | return NSS_STATUS_SUCCESS; | |
258 | } while (__nss_next(&grent_nip, grent_fct_name, &grent_fct.ptr, status, 0) == 0); | |
259 | ||
260 | grent_nip = NULL; | |
261 | return NSS_STATUS_NOTFOUND; | |
262 | } | |
263 | ||
264 | ||
265 | enum nss_status | |
266 | _nss_nonlocal_getgrnam_r(const char *name, struct group *grp, | |
267 | char *buffer, size_t buflen, int *errnop) | |
268 | { | |
269 | enum nss_status status; | |
270 | const struct walk_nss w = { | |
271 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "getgrnam_r", | |
272 | .status = &status, .errnop = errnop | |
273 | }; | |
274 | const __typeof__(&_nss_nonlocal_getgrnam_r) self = NULL; | |
275 | ||
276 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
277 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
278 | return NSS_STATUS_UNAVAIL; | |
279 | ||
280 | #define args (name, grp, buffer, buflen, errnop) | |
281 | #include "walk_nss.h" | |
282 | #undef args | |
283 | if (status != NSS_STATUS_SUCCESS) | |
284 | return status; | |
285 | ||
286 | if (strcmp(name, grp->gr_name) != 0) { | |
287 | syslog(LOG_ERR, "nss_nonlocal: discarding group %s from lookup for group %s\n", grp->gr_name, name); | |
288 | return NSS_STATUS_NOTFOUND; | |
289 | } | |
290 | ||
291 | return check_nonlocal_group(name, grp, errnop); | |
292 | } | |
293 | ||
294 | enum nss_status | |
295 | _nss_nonlocal_getgrgid_r(gid_t gid, struct group *grp, | |
296 | char *buffer, size_t buflen, int *errnop) | |
297 | { | |
298 | enum nss_status status; | |
299 | const struct walk_nss w = { | |
300 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "getgrgid_r", | |
301 | .status = &status, .errnop = errnop | |
302 | }; | |
303 | const __typeof__(&_nss_nonlocal_getgrgid_r) self = NULL; | |
304 | ||
305 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
306 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
307 | return NSS_STATUS_UNAVAIL; | |
308 | ||
309 | #define args (gid, grp, buffer, buflen, errnop) | |
310 | #include "walk_nss.h" | |
311 | #undef args | |
312 | if (status != NSS_STATUS_SUCCESS) | |
313 | return status; | |
314 | ||
315 | if (gid != grp->gr_gid) { | |
316 | syslog(LOG_ERR, "nss_nonlocal: discarding gid %d from lookup for gid %d\n", grp->gr_gid, gid); | |
317 | return NSS_STATUS_NOTFOUND; | |
318 | } | |
319 | ||
320 | return check_nonlocal_group(grp->gr_name, grp, errnop); | |
321 | } | |
322 | ||
323 | static bool | |
324 | add_group(gid_t group, long int *start, long int *size, gid_t **groupsp, | |
325 | long int limit, int *errnop, enum nss_status *status) | |
326 | { | |
327 | int i, old_errno = errno; | |
328 | for (i = 0; i < *start; ++i) | |
329 | if ((*groupsp)[i] == group) | |
330 | return true; | |
331 | if (*start + 1 > *size) { | |
332 | gid_t *newgroups; | |
333 | long int newsize = 2 * *size; | |
334 | if (limit > 0) { | |
335 | if (*size >= limit) { | |
336 | *status = NSS_STATUS_SUCCESS; | |
337 | return false; | |
338 | } | |
339 | if (newsize > limit) | |
340 | newsize = limit; | |
341 | } | |
342 | newgroups = realloc(*groupsp, newsize * sizeof((*groupsp)[0])); | |
343 | errno = old_errno; | |
344 | if (newgroups == NULL) { | |
345 | *errnop = ENOMEM; | |
346 | *status = NSS_STATUS_TRYAGAIN; | |
347 | return false; | |
348 | } | |
349 | *groupsp = newgroups; | |
350 | *size = newsize; | |
351 | } | |
352 | (*groupsp)[(*start)++] = group; | |
353 | return true; | |
354 | } | |
355 | ||
356 | enum nss_status | |
357 | _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start, | |
358 | long int *size, gid_t **groupsp, long int limit, | |
359 | int *errnop) | |
360 | { | |
361 | enum nss_status status; | |
362 | const struct walk_nss w = { | |
363 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "initgroups_dyn", | |
364 | .status = &status, .errnop = errnop | |
365 | }; | |
366 | const __typeof__(&_nss_nonlocal_initgroups_dyn) self = NULL; | |
367 | ||
368 | struct group local_users_group, nonlocal_users_group; | |
369 | bool is_nonlocal = true; | |
370 | char *buffer; | |
371 | int in, out, i; | |
372 | ||
373 | /* Check that the user is a nonlocal user, or a member of the | |
374 | * MAGIC_NONLOCAL_GROUPNAME group, before adding any groups. */ | |
375 | status = check_nonlocal_user(user, errnop); | |
376 | if (status == NSS_STATUS_TRYAGAIN) { | |
377 | return status; | |
378 | } else if (status != NSS_STATUS_SUCCESS) { | |
379 | is_nonlocal = false; | |
380 | ||
381 | status = get_local_group(MAGIC_LOCAL_GROUPNAME, | |
382 | &local_users_group, &buffer, errnop); | |
383 | if (status == NSS_STATUS_SUCCESS) { | |
384 | free(buffer); | |
385 | if (!add_group(local_users_group.gr_gid, start, size, groupsp, | |
386 | limit, errnop, &status)) | |
387 | return status; | |
388 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
389 | return status; | |
390 | } else { | |
391 | syslog(LOG_WARNING, | |
392 | "nss_nonlocal: Group %s does not exist locally!", | |
393 | MAGIC_LOCAL_GROUPNAME); | |
394 | } | |
395 | } | |
396 | ||
397 | status = get_local_group(MAGIC_NONLOCAL_GROUPNAME, | |
398 | &nonlocal_users_group, &buffer, errnop); | |
399 | if (status == NSS_STATUS_SUCCESS) { | |
400 | free(buffer); | |
401 | if (is_nonlocal) { | |
402 | if (!add_group(nonlocal_users_group.gr_gid, start, size, groupsp, | |
403 | limit, errnop, &status)) | |
404 | return status; | |
405 | } else { | |
406 | int i; | |
407 | for (i = 0; i < *start; ++i) { | |
408 | if ((*groupsp)[i] == nonlocal_users_group.gr_gid) { | |
409 | is_nonlocal = true; | |
410 | break; | |
411 | } | |
412 | } | |
413 | ||
414 | if (is_nonlocal) { | |
415 | struct passwd pwbuf; | |
416 | char *buf; | |
417 | int nonlocal_errno = *errnop; | |
418 | status = get_nonlocal_passwd(user, &pwbuf, &buf, errnop); | |
419 | ||
420 | if (status == NSS_STATUS_SUCCESS) { | |
421 | nonlocal_errno = *errnop; | |
422 | status = check_nonlocal_gid(user, NULL, pwbuf.pw_gid, | |
423 | &nonlocal_errno); | |
424 | free(buf); | |
425 | } | |
426 | ||
427 | if (status == NSS_STATUS_SUCCESS) { | |
428 | if (!add_group(pwbuf.pw_gid, start, size, groupsp, limit, | |
429 | errnop, &status)) | |
430 | return status; | |
431 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
432 | *errnop = nonlocal_errno; | |
433 | return status; | |
434 | } | |
435 | } | |
436 | } | |
437 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
438 | if (is_nonlocal) | |
439 | return status; | |
440 | } else { | |
441 | syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!", | |
442 | MAGIC_NONLOCAL_GROUPNAME); | |
443 | } | |
444 | ||
445 | if (!is_nonlocal) | |
446 | return NSS_STATUS_SUCCESS; | |
447 | ||
448 | in = out = *start; | |
449 | ||
450 | #define args (user, group, start, size, groupsp, limit, errnop) | |
451 | #include "walk_nss.h" | |
452 | #undef args | |
453 | if (status == NSS_STATUS_NOTFOUND || status == NSS_STATUS_UNAVAIL) | |
454 | return NSS_STATUS_SUCCESS; | |
455 | else if (status != NSS_STATUS_SUCCESS) | |
456 | return status; | |
457 | ||
458 | for (; in < *start; ++in) { | |
459 | int nonlocal_errno = *errnop; | |
460 | ||
461 | for (i = 0; i < out; ++i) | |
462 | if ((*groupsp)[i] == (*groupsp)[in]) | |
463 | break; | |
464 | if (i < out) | |
465 | continue; | |
466 | ||
467 | status = check_nonlocal_gid(user, NULL, (*groupsp)[in], | |
468 | &nonlocal_errno); | |
469 | if (status == NSS_STATUS_SUCCESS) { | |
470 | (*groupsp)[out++] = (*groupsp)[in]; | |
471 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
472 | *start = out; | |
473 | *errnop = nonlocal_errno; | |
474 | return status; | |
475 | } | |
476 | } | |
477 | ||
478 | *start = out; | |
479 | return NSS_STATUS_SUCCESS; | |
480 | } |