1 | /* Cache handling for host lookup. |
2 | Copyright (C) 2004-2018 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2004. |
5 | |
6 | This program is free software; you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published |
8 | by the Free Software Foundation; version 2 of the License, or |
9 | (at your option) any later version. |
10 | |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | GNU General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <assert.h> |
20 | #include <errno.h> |
21 | #include <grp.h> |
22 | #include <libintl.h> |
23 | #include <string.h> |
24 | #include <time.h> |
25 | #include <unistd.h> |
26 | #include <sys/mman.h> |
27 | #include <scratch_buffer.h> |
28 | #include <config.h> |
29 | |
30 | #include "dbg_log.h" |
31 | #include "nscd.h" |
32 | #ifdef HAVE_SENDFILE |
33 | # include <kernel-features.h> |
34 | #endif |
35 | |
36 | #include "../nss/nsswitch.h" |
37 | |
38 | #ifdef LINK_OBSOLETE_NSL |
39 | # define DEFAULT_CONFIG "compat [NOTFOUND=return] files" |
40 | #else |
41 | # define DEFAULT_CONFIG "files" |
42 | #endif |
43 | |
44 | /* Type of the lookup function. */ |
45 | typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t, |
46 | long int *, long int *, |
47 | gid_t **, long int, int *); |
48 | |
49 | |
50 | static const initgr_response_header notfound = |
51 | { |
52 | .version = NSCD_VERSION, |
53 | .found = 0, |
54 | .ngrps = 0 |
55 | }; |
56 | |
57 | |
58 | #include "../grp/compat-initgroups.c" |
59 | |
60 | |
61 | static time_t |
62 | addinitgroupsX (struct database_dyn *db, int fd, request_header *req, |
63 | void *key, uid_t uid, struct hashentry *const he, |
64 | struct datahead *dh) |
65 | { |
66 | /* Search for the entry matching the key. Please note that we don't |
67 | look again in the table whether the dataset is now available. We |
68 | simply insert it. It does not matter if it is in there twice. The |
69 | pruning function only will look at the timestamp. */ |
70 | |
71 | |
72 | /* We allocate all data in one memory block: the iov vector, |
73 | the response header and the dataset itself. */ |
74 | struct dataset |
75 | { |
76 | struct datahead head; |
77 | initgr_response_header resp; |
78 | char strdata[0]; |
79 | } *dataset = NULL; |
80 | |
81 | if (__glibc_unlikely (debug_level > 0)) |
82 | { |
83 | if (he == NULL) |
84 | dbg_log (_("Haven't found \"%s\" in group cache!" ), (char *) key); |
85 | else |
86 | dbg_log (_("Reloading \"%s\" in group cache!" ), (char *) key); |
87 | } |
88 | |
89 | static service_user *group_database; |
90 | service_user *nip; |
91 | int no_more; |
92 | |
93 | if (group_database == NULL) |
94 | no_more = __nss_database_lookup ("group" , NULL, DEFAULT_CONFIG, |
95 | &group_database); |
96 | else |
97 | no_more = 0; |
98 | nip = group_database; |
99 | |
100 | /* We always use sysconf even if NGROUPS_MAX is defined. That way, the |
101 | limit can be raised in the kernel configuration without having to |
102 | recompile libc. */ |
103 | long int limit = __sysconf (_SC_NGROUPS_MAX); |
104 | |
105 | long int size; |
106 | if (limit > 0) |
107 | /* We limit the size of the intially allocated array. */ |
108 | size = MIN (limit, 64); |
109 | else |
110 | /* No fixed limit on groups. Pick a starting buffer size. */ |
111 | size = 16; |
112 | |
113 | long int start = 0; |
114 | bool all_tryagain = true; |
115 | bool any_success = false; |
116 | |
117 | /* This is temporary memory, we need not (and must not) call |
118 | mempool_alloc. */ |
119 | // XXX This really should use alloca. need to change the backends. |
120 | gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t)); |
121 | if (__glibc_unlikely (groups == NULL)) |
122 | /* No more memory. */ |
123 | goto out; |
124 | |
125 | /* Nothing added yet. */ |
126 | while (! no_more) |
127 | { |
128 | long int prev_start = start; |
129 | enum nss_status status; |
130 | initgroups_dyn_function fct; |
131 | fct = __nss_lookup_function (nip, "initgroups_dyn" ); |
132 | |
133 | if (fct == NULL) |
134 | { |
135 | status = compat_call (nip, key, -1, &start, &size, &groups, |
136 | limit, &errno); |
137 | |
138 | if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE) |
139 | break; |
140 | } |
141 | else |
142 | status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups, |
143 | limit, &errno)); |
144 | |
145 | /* Remove duplicates. */ |
146 | long int cnt = prev_start; |
147 | while (cnt < start) |
148 | { |
149 | long int inner; |
150 | for (inner = 0; inner < prev_start; ++inner) |
151 | if (groups[inner] == groups[cnt]) |
152 | break; |
153 | |
154 | if (inner < prev_start) |
155 | groups[cnt] = groups[--start]; |
156 | else |
157 | ++cnt; |
158 | } |
159 | |
160 | if (status != NSS_STATUS_TRYAGAIN) |
161 | all_tryagain = false; |
162 | |
163 | /* This is really only for debugging. */ |
164 | if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN) |
165 | __libc_fatal ("illegal status in internal_getgrouplist" ); |
166 | |
167 | any_success |= status == NSS_STATUS_SUCCESS; |
168 | |
169 | if (status != NSS_STATUS_SUCCESS |
170 | && nss_next_action (nip, status) == NSS_ACTION_RETURN) |
171 | break; |
172 | |
173 | if (nip->next == NULL) |
174 | no_more = -1; |
175 | else |
176 | nip = nip->next; |
177 | } |
178 | |
179 | bool all_written; |
180 | ssize_t total; |
181 | time_t timeout; |
182 | out: |
183 | all_written = true; |
184 | timeout = MAX_TIMEOUT_VALUE; |
185 | if (!any_success) |
186 | { |
187 | /* Nothing found. Create a negative result record. */ |
188 | total = sizeof (notfound); |
189 | |
190 | if (he != NULL && all_tryagain) |
191 | { |
192 | /* If we have an old record available but cannot find one now |
193 | because the service is not available we keep the old record |
194 | and make sure it does not get removed. */ |
195 | if (reload_count != UINT_MAX && dh->nreloads == reload_count) |
196 | /* Do not reset the value if we never not reload the record. */ |
197 | dh->nreloads = reload_count - 1; |
198 | |
199 | /* Reload with the same time-to-live value. */ |
200 | timeout = dh->timeout = time (NULL) + db->postimeout; |
201 | } |
202 | else |
203 | { |
204 | /* We have no data. This means we send the standard reply for this |
205 | case. */ |
206 | if (fd != -1 |
207 | && TEMP_FAILURE_RETRY (send (fd, ¬found, total, |
208 | MSG_NOSIGNAL)) != total) |
209 | all_written = false; |
210 | |
211 | /* If we have a transient error or cannot permanently store |
212 | the result, so be it. */ |
213 | if (all_tryagain || __builtin_expect (db->negtimeout == 0, 0)) |
214 | { |
215 | /* Mark the old entry as obsolete. */ |
216 | if (dh != NULL) |
217 | dh->usable = false; |
218 | } |
219 | else if ((dataset = mempool_alloc (db, (sizeof (struct dataset) |
220 | + req->key_len), 1)) != NULL) |
221 | { |
222 | timeout = datahead_init_neg (&dataset->head, |
223 | (sizeof (struct dataset) |
224 | + req->key_len), total, |
225 | db->negtimeout); |
226 | |
227 | /* This is the reply. */ |
228 | memcpy (&dataset->resp, ¬found, total); |
229 | |
230 | /* Copy the key data. */ |
231 | char *key_copy = memcpy (dataset->strdata, key, req->key_len); |
232 | |
233 | /* If necessary, we also propagate the data to disk. */ |
234 | if (db->persistent) |
235 | { |
236 | // XXX async OK? |
237 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
238 | msync ((void *) pval, |
239 | ((uintptr_t) dataset & pagesize_m1) |
240 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); |
241 | } |
242 | |
243 | (void) cache_add (req->type, key_copy, req->key_len, |
244 | &dataset->head, true, db, uid, he == NULL); |
245 | |
246 | pthread_rwlock_unlock (&db->lock); |
247 | |
248 | /* Mark the old entry as obsolete. */ |
249 | if (dh != NULL) |
250 | dh->usable = false; |
251 | } |
252 | } |
253 | } |
254 | else |
255 | { |
256 | |
257 | total = offsetof (struct dataset, strdata) + start * sizeof (int32_t); |
258 | |
259 | /* If we refill the cache, first assume the reconrd did not |
260 | change. Allocate memory on the cache since it is likely |
261 | discarded anyway. If it turns out to be necessary to have a |
262 | new record we can still allocate real memory. */ |
263 | bool alloca_used = false; |
264 | dataset = NULL; |
265 | |
266 | if (he == NULL) |
267 | dataset = (struct dataset *) mempool_alloc (db, total + req->key_len, |
268 | 1); |
269 | |
270 | if (dataset == NULL) |
271 | { |
272 | /* We cannot permanently add the result in the moment. But |
273 | we can provide the result as is. Store the data in some |
274 | temporary memory. */ |
275 | dataset = (struct dataset *) alloca (total + req->key_len); |
276 | |
277 | /* We cannot add this record to the permanent database. */ |
278 | alloca_used = true; |
279 | } |
280 | |
281 | timeout = datahead_init_pos (&dataset->head, total + req->key_len, |
282 | total - offsetof (struct dataset, resp), |
283 | he == NULL ? 0 : dh->nreloads + 1, |
284 | db->postimeout); |
285 | |
286 | dataset->resp.version = NSCD_VERSION; |
287 | dataset->resp.found = 1; |
288 | dataset->resp.ngrps = start; |
289 | |
290 | char *cp = dataset->strdata; |
291 | |
292 | /* Copy the GID values. If the size of the types match this is |
293 | very simple. */ |
294 | if (sizeof (gid_t) == sizeof (int32_t)) |
295 | cp = mempcpy (cp, groups, start * sizeof (gid_t)); |
296 | else |
297 | { |
298 | gid_t *gcp = (gid_t *) cp; |
299 | |
300 | for (int i = 0; i < start; ++i) |
301 | *gcp++ = groups[i]; |
302 | |
303 | cp = (char *) gcp; |
304 | } |
305 | |
306 | /* Finally the user name. */ |
307 | memcpy (cp, key, req->key_len); |
308 | |
309 | assert (cp == dataset->strdata + total - offsetof (struct dataset, |
310 | strdata)); |
311 | |
312 | /* Now we can determine whether on refill we have to create a new |
313 | record or not. */ |
314 | if (he != NULL) |
315 | { |
316 | assert (fd == -1); |
317 | |
318 | if (total + req->key_len == dh->allocsize |
319 | && total - offsetof (struct dataset, resp) == dh->recsize |
320 | && memcmp (&dataset->resp, dh->data, |
321 | dh->allocsize - offsetof (struct dataset, resp)) == 0) |
322 | { |
323 | /* The data has not changed. We will just bump the |
324 | timeout value. Note that the new record has been |
325 | allocated on the stack and need not be freed. */ |
326 | dh->timeout = dataset->head.timeout; |
327 | ++dh->nreloads; |
328 | } |
329 | else |
330 | { |
331 | /* We have to create a new record. Just allocate |
332 | appropriate memory and copy it. */ |
333 | struct dataset *newp |
334 | = (struct dataset *) mempool_alloc (db, total + req->key_len, |
335 | 1); |
336 | if (newp != NULL) |
337 | { |
338 | /* Adjust pointer into the memory block. */ |
339 | cp = (char *) newp + (cp - (char *) dataset); |
340 | |
341 | dataset = memcpy (newp, dataset, total + req->key_len); |
342 | alloca_used = false; |
343 | } |
344 | |
345 | /* Mark the old record as obsolete. */ |
346 | dh->usable = false; |
347 | } |
348 | } |
349 | else |
350 | { |
351 | /* We write the dataset before inserting it to the database |
352 | since while inserting this thread might block and so would |
353 | unnecessarily let the receiver wait. */ |
354 | assert (fd != -1); |
355 | |
356 | #ifdef HAVE_SENDFILE |
357 | if (__builtin_expect (db->mmap_used, 1) && !alloca_used) |
358 | { |
359 | assert (db->wr_fd != -1); |
360 | assert ((char *) &dataset->resp > (char *) db->data); |
361 | assert ((char *) dataset - (char *) db->head |
362 | + total |
363 | <= (sizeof (struct database_pers_head) |
364 | + db->head->module * sizeof (ref_t) |
365 | + db->head->data_size)); |
366 | ssize_t written = sendfileall (fd, db->wr_fd, |
367 | (char *) &dataset->resp |
368 | - (char *) db->head, |
369 | dataset->head.recsize); |
370 | if (written != dataset->head.recsize) |
371 | { |
372 | # ifndef __ASSUME_SENDFILE |
373 | if (written == -1 && errno == ENOSYS) |
374 | goto use_write; |
375 | # endif |
376 | all_written = false; |
377 | } |
378 | } |
379 | else |
380 | # ifndef __ASSUME_SENDFILE |
381 | use_write: |
382 | # endif |
383 | #endif |
384 | if (writeall (fd, &dataset->resp, dataset->head.recsize) |
385 | != dataset->head.recsize) |
386 | all_written = false; |
387 | } |
388 | |
389 | |
390 | /* Add the record to the database. But only if it has not been |
391 | stored on the stack. */ |
392 | if (! alloca_used) |
393 | { |
394 | /* If necessary, we also propagate the data to disk. */ |
395 | if (db->persistent) |
396 | { |
397 | // XXX async OK? |
398 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
399 | msync ((void *) pval, |
400 | ((uintptr_t) dataset & pagesize_m1) + total + |
401 | req->key_len, MS_ASYNC); |
402 | } |
403 | |
404 | (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true, |
405 | db, uid, he == NULL); |
406 | |
407 | pthread_rwlock_unlock (&db->lock); |
408 | } |
409 | } |
410 | |
411 | free (groups); |
412 | |
413 | if (__builtin_expect (!all_written, 0) && debug_level > 0) |
414 | { |
415 | char buf[256]; |
416 | dbg_log (_("short write in %s: %s" ), __FUNCTION__, |
417 | strerror_r (errno, buf, sizeof (buf))); |
418 | } |
419 | |
420 | return timeout; |
421 | } |
422 | |
423 | |
424 | void |
425 | addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key, |
426 | uid_t uid) |
427 | { |
428 | addinitgroupsX (db, fd, req, key, uid, NULL, NULL); |
429 | } |
430 | |
431 | |
432 | time_t |
433 | readdinitgroups (struct database_dyn *db, struct hashentry *he, |
434 | struct datahead *dh) |
435 | { |
436 | request_header req = |
437 | { |
438 | .type = INITGROUPS, |
439 | .key_len = he->len |
440 | }; |
441 | |
442 | return addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
443 | } |
444 | |