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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 | #include <sys/types.h> | |
28 | #include <unistd.h> | |
29 | #include <stdlib.h> | |
30 | #include <stdint.h> | |
31 | #include <string.h> | |
32 | #include <dlfcn.h> | |
33 | #include <stdio.h> | |
34 | #include <syslog.h> | |
35 | #include <errno.h> | |
36 | #include <grp.h> | |
37 | #include <nss.h> | |
38 | #include "nsswitch-internal.h" | |
39 | #include "nonlocal.h" | |
40 | ||
41 | #define MAGIC_NONLOCAL_GROUPNAME "nss-nonlocal-users" | |
42 | #define MAGIC_LOCAL_GROUPNAME "nss-local-users" | |
43 | ||
44 | ||
45 | enum nss_status | |
46 | _nss_nonlocal_getgrnam_r(const char *name, struct group *grp, | |
47 | char *buffer, size_t buflen, int *errnop); | |
48 | ||
49 | enum nss_status | |
50 | _nss_nonlocal_getgrgid_r(gid_t gid, struct group *grp, | |
51 | char *buffer, size_t buflen, int *errnop); | |
52 | ||
53 | ||
54 | static service_user *__nss_group_nonlocal_database; | |
55 | ||
56 | static int | |
57 | internal_function | |
58 | __nss_group_nonlocal_lookup(service_user **ni, const char *fct_name, | |
59 | void **fctp) | |
60 | { | |
61 | if (__nss_group_nonlocal_database == NULL | |
62 | && __nss_database_lookup("group_nonlocal", NULL, NULL, | |
63 | &__nss_group_nonlocal_database) < 0) | |
64 | return -1; | |
65 | ||
66 | *ni = __nss_group_nonlocal_database; | |
67 | ||
68 | *fctp = __nss_lookup_function(*ni, fct_name); | |
69 | return 0; | |
70 | } | |
71 | ||
72 | ||
73 | enum nss_status | |
74 | check_nonlocal_gid(const char *user, gid_t gid, int *errnop) | |
75 | { | |
76 | enum nss_status status; | |
77 | struct group gbuf; | |
78 | char *buf; | |
79 | size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX); | |
80 | const struct walk_nss w = { | |
81 | .lookup = &__nss_group_lookup, .fct_name = "getgrgid_r", | |
82 | .status = &status, .errnop = errnop, .buf = &buf, .buflen = &buflen | |
83 | }; | |
84 | const __typeof__(&_nss_nonlocal_getgrgid_r) self = &_nss_nonlocal_getgrgid_r; | |
85 | #define args (gid, &gbuf, buf, buflen, errnop) | |
86 | #include "walk_nss.h" | |
87 | #undef args | |
88 | ||
89 | if (status == NSS_STATUS_SUCCESS) { | |
90 | syslog(LOG_DEBUG, "nss_nonlocal: removing local group %u (%s) from non-local user %s\n", gbuf.gr_gid, gbuf.gr_name, user); | |
91 | free(buf); | |
92 | status = NSS_STATUS_NOTFOUND; | |
93 | } else if (status != NSS_STATUS_TRYAGAIN) { | |
94 | status = NSS_STATUS_SUCCESS; | |
95 | } | |
96 | ||
97 | return status; | |
98 | } | |
99 | ||
100 | enum nss_status | |
101 | check_nonlocal_group(const char *user, struct group *grp, int *errnop) | |
102 | { | |
103 | enum nss_status status = NSS_STATUS_SUCCESS; | |
104 | int old_errno = errno; | |
105 | char *end; | |
106 | unsigned long gid; | |
107 | ||
108 | errno = 0; | |
109 | gid = strtoul(grp->gr_name, &end, 10); | |
110 | if (errno == 0 && *end == '\0' && (gid_t)gid == gid) { | |
111 | errno = old_errno; | |
112 | status = check_nonlocal_gid(user, gid, errnop); | |
113 | } else | |
114 | errno = old_errno; | |
115 | if (status != NSS_STATUS_SUCCESS) | |
116 | return status; | |
117 | ||
118 | return check_nonlocal_gid(user, grp->gr_gid, errnop); | |
119 | } | |
120 | ||
121 | enum nss_status | |
122 | get_local_group(const char *name, struct group *grp, char **buffer, int *errnop) | |
123 | { | |
124 | enum nss_status status; | |
125 | size_t buflen = sysconf(_SC_GETGR_R_SIZE_MAX); | |
126 | const struct walk_nss w = { | |
127 | .lookup = &__nss_group_lookup, .fct_name = "getgrnam_r", | |
128 | .status = &status, .errnop = errnop, .buf = buffer, .buflen = &buflen | |
129 | }; | |
130 | const __typeof__(&_nss_nonlocal_getgrnam_r) self = &_nss_nonlocal_getgrnam_r; | |
131 | #define args (name, grp, *buffer, buflen, errnop) | |
132 | #include "walk_nss.h" | |
133 | #undef args | |
134 | return status; | |
135 | } | |
136 | ||
137 | static service_user *grent_startp, *grent_nip; | |
138 | static void *grent_fct_start; | |
139 | static union { | |
140 | enum nss_status (*l)(struct group *grp, char *buffer, size_t buflen, | |
141 | int *errnop); | |
142 | void *ptr; | |
143 | } grent_fct; | |
144 | static const char *grent_fct_name = "getgrent_r"; | |
145 | ||
146 | enum nss_status | |
147 | _nss_nonlocal_setgrent(int stayopen) | |
148 | { | |
149 | enum nss_status status; | |
150 | const struct walk_nss w = { | |
151 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "setgrent", | |
152 | .status = &status | |
153 | }; | |
154 | const __typeof__(&_nss_nonlocal_setgrent) self = NULL; | |
155 | #define args (stayopen) | |
156 | #include "walk_nss.h" | |
157 | #undef args | |
158 | if (status != NSS_STATUS_SUCCESS) | |
159 | return status; | |
160 | ||
161 | if (grent_fct_start == NULL) | |
162 | __nss_group_nonlocal_lookup(&grent_startp, grent_fct_name, | |
163 | &grent_fct_start); | |
164 | grent_nip = grent_startp; | |
165 | grent_fct.ptr = grent_fct_start; | |
166 | return NSS_STATUS_SUCCESS; | |
167 | } | |
168 | ||
169 | enum nss_status | |
170 | _nss_nonlocal_endgrent(void) | |
171 | { | |
172 | enum nss_status status; | |
173 | const struct walk_nss w = { | |
174 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "endgrent", | |
175 | .status = &status | |
176 | }; | |
177 | const __typeof__(&_nss_nonlocal_endgrent) self = NULL; | |
178 | ||
179 | grent_nip = NULL; | |
180 | ||
181 | #define args () | |
182 | #include "walk_nss.h" | |
183 | #undef args | |
184 | return status; | |
185 | } | |
186 | ||
187 | enum nss_status | |
188 | _nss_nonlocal_getgrent_r(struct group *grp, char *buffer, size_t buflen, | |
189 | int *errnop) | |
190 | { | |
191 | enum nss_status status; | |
192 | ||
193 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
194 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
195 | return NSS_STATUS_UNAVAIL; | |
196 | ||
197 | if (grent_nip == NULL) { | |
198 | status = _nss_nonlocal_setgrent(0); | |
199 | if (status != NSS_STATUS_SUCCESS) | |
200 | return status; | |
201 | } | |
202 | do { | |
203 | if (grent_fct.ptr == NULL) | |
204 | status = NSS_STATUS_UNAVAIL; | |
205 | else { | |
206 | int nonlocal_errno; | |
207 | do | |
208 | status = DL_CALL_FCT(grent_fct.l, (grp, buffer, buflen, errnop)); | |
209 | while (status == NSS_STATUS_SUCCESS && | |
210 | check_nonlocal_group("(unknown)", grp, &nonlocal_errno) != NSS_STATUS_SUCCESS); | |
211 | } | |
212 | if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) | |
213 | return status; | |
214 | ||
215 | if (status == NSS_STATUS_SUCCESS) | |
216 | return NSS_STATUS_SUCCESS; | |
217 | } while (__nss_next(&grent_nip, grent_fct_name, &grent_fct.ptr, status, 0) == 0); | |
218 | ||
219 | grent_nip = NULL; | |
220 | return NSS_STATUS_NOTFOUND; | |
221 | } | |
222 | ||
223 | ||
224 | enum nss_status | |
225 | _nss_nonlocal_getgrnam_r(const char *name, struct group *grp, | |
226 | char *buffer, size_t buflen, int *errnop) | |
227 | { | |
228 | enum nss_status status; | |
229 | const struct walk_nss w = { | |
230 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "getgrnam_r", | |
231 | .status = &status, .errnop = errnop | |
232 | }; | |
233 | const __typeof__(&_nss_nonlocal_getgrnam_r) self = NULL; | |
234 | ||
235 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
236 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
237 | return NSS_STATUS_UNAVAIL; | |
238 | ||
239 | #define args (name, grp, buffer, buflen, errnop) | |
240 | #include "walk_nss.h" | |
241 | #undef args | |
242 | if (status != NSS_STATUS_SUCCESS) | |
243 | return status; | |
244 | ||
245 | if (strcmp(name, grp->gr_name) != 0) { | |
246 | syslog(LOG_ERR, "nss_nonlocal: discarding group %s from lookup for group %s\n", grp->gr_name, name); | |
247 | return NSS_STATUS_NOTFOUND; | |
248 | } | |
249 | ||
250 | return check_nonlocal_group(name, grp, errnop); | |
251 | } | |
252 | ||
253 | enum nss_status | |
254 | _nss_nonlocal_getgrgid_r(gid_t gid, struct group *grp, | |
255 | char *buffer, size_t buflen, int *errnop) | |
256 | { | |
257 | enum nss_status status; | |
258 | const struct walk_nss w = { | |
259 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "getgrgid_r", | |
260 | .status = &status, .errnop = errnop | |
261 | }; | |
262 | const __typeof__(&_nss_nonlocal_getgrgid_r) self = NULL; | |
263 | ||
264 | char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); | |
265 | if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') | |
266 | return NSS_STATUS_UNAVAIL; | |
267 | ||
268 | #define args (gid, grp, buffer, buflen, errnop) | |
269 | #include "walk_nss.h" | |
270 | #undef args | |
271 | if (status != NSS_STATUS_SUCCESS) | |
272 | return status; | |
273 | ||
274 | if (gid != grp->gr_gid) { | |
275 | syslog(LOG_ERR, "nss_nonlocal: discarding gid %d from lookup for gid %d\n", grp->gr_gid, gid); | |
276 | return NSS_STATUS_NOTFOUND; | |
277 | } | |
278 | ||
279 | return check_nonlocal_group(grp->gr_name, grp, errnop); | |
280 | } | |
281 | ||
282 | enum nss_status | |
283 | _nss_nonlocal_initgroups_dyn(const char *user, gid_t group, long int *start, | |
284 | long int *size, gid_t **groupsp, long int limit, | |
285 | int *errnop) | |
286 | { | |
287 | enum nss_status status; | |
288 | const struct walk_nss w = { | |
289 | .lookup = &__nss_group_nonlocal_lookup, .fct_name = "initgroups_dyn", | |
290 | .status = &status, .errnop = errnop | |
291 | }; | |
292 | const __typeof__(&_nss_nonlocal_initgroups_dyn) self = NULL; | |
293 | ||
294 | struct group local_users_group, nonlocal_users_group; | |
295 | gid_t local_users_gid, gid; | |
296 | int is_local = 0; | |
297 | char *buffer; | |
298 | int old_errno; | |
299 | int in, out, i; | |
300 | ||
301 | /* Check that the user is a nonlocal user before adding any groups. */ | |
302 | status = check_nonlocal_user(user, errnop); | |
303 | if (status == NSS_STATUS_TRYAGAIN) | |
304 | return status; | |
305 | else if (status != NSS_STATUS_SUCCESS) | |
306 | is_local = 1; | |
307 | ||
308 | old_errno = errno; | |
309 | ||
310 | status = get_local_group(MAGIC_LOCAL_GROUPNAME, | |
311 | &local_users_group, &buffer, errnop); | |
312 | if (status == NSS_STATUS_SUCCESS) { | |
313 | local_users_gid = local_users_group.gr_gid; | |
314 | free(buffer); | |
315 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
316 | return status; | |
317 | } else { | |
318 | syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!", | |
319 | MAGIC_LOCAL_GROUPNAME); | |
320 | local_users_gid = -1; | |
321 | } | |
322 | ||
323 | if (is_local) { | |
324 | gid = local_users_gid; | |
325 | } else { | |
326 | status = get_local_group(MAGIC_NONLOCAL_GROUPNAME, | |
327 | &nonlocal_users_group, &buffer, errnop); | |
328 | if (status == NSS_STATUS_SUCCESS) { | |
329 | gid = nonlocal_users_group.gr_gid; | |
330 | free(buffer); | |
331 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
332 | return status; | |
333 | } else { | |
334 | syslog(LOG_WARNING, "nss_nonlocal: Group %s does not exist locally!", | |
335 | MAGIC_NONLOCAL_GROUPNAME); | |
336 | gid = -1; | |
337 | } | |
338 | } | |
339 | ||
340 | if (gid != -1) { | |
341 | int i; | |
342 | for (i = 0; i < *start; ++i) | |
343 | if ((*groupsp)[i] == gid) | |
344 | break; | |
345 | if (i >= *start) { | |
346 | if (*start + 1 > *size) { | |
347 | gid_t *newgroups; | |
348 | long int newsize = 2 * *size; | |
349 | if (limit > 0) { | |
350 | if (*size >= limit) | |
351 | return NSS_STATUS_SUCCESS; | |
352 | if (newsize > limit) | |
353 | newsize = limit; | |
354 | } | |
355 | newgroups = realloc(*groupsp, newsize * sizeof((*groupsp)[0])); | |
356 | errno = old_errno; | |
357 | if (newgroups == NULL) { | |
358 | *errnop = ENOMEM; | |
359 | return NSS_STATUS_TRYAGAIN; | |
360 | } | |
361 | *groupsp = newgroups; | |
362 | *size = newsize; | |
363 | } | |
364 | (*groupsp)[(*start)++] = gid; | |
365 | } | |
366 | } | |
367 | ||
368 | if (is_local) | |
369 | return NSS_STATUS_SUCCESS; | |
370 | ||
371 | in = out = *start; | |
372 | ||
373 | #define args (user, group, start, size, groupsp, limit, errnop) | |
374 | #include "walk_nss.h" | |
375 | #undef args | |
376 | if (status != NSS_STATUS_SUCCESS) | |
377 | return status; | |
378 | ||
379 | for (; in < *start; ++in) { | |
380 | int nonlocal_errno = *errnop; | |
381 | ||
382 | for (i = 0; i < out; ++i) | |
383 | if ((*groupsp)[i] == (*groupsp)[in]) | |
384 | break; | |
385 | if (i < out) | |
386 | continue; | |
387 | ||
388 | /* Don't let users get into MAGIC_LOCAL_GROUPNAME from nonlocal reasons. */ | |
389 | if (local_users_gid == (*groupsp)[in]) { | |
390 | syslog(LOG_WARNING, "nss_nonlocal: Nonlocal user %s removed from special local users group %s", | |
391 | user, MAGIC_LOCAL_GROUPNAME); | |
392 | continue; | |
393 | } | |
394 | ||
395 | status = check_nonlocal_gid(user, (*groupsp)[in], &nonlocal_errno); | |
396 | if (status == NSS_STATUS_SUCCESS) { | |
397 | (*groupsp)[out++] = (*groupsp)[in]; | |
398 | } else if (status == NSS_STATUS_TRYAGAIN) { | |
399 | *start = out; | |
400 | *errnop = nonlocal_errno; | |
401 | return status; | |
402 | } | |
403 | } | |
404 | ||
405 | *start = out; | |
406 | return NSS_STATUS_SUCCESS; | |
407 | } |