1 | /* Cache handling for group lookup. |
2 | Copyright (C) 1998-2016 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998. |
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 <alloca.h> |
20 | #include <assert.h> |
21 | #include <errno.h> |
22 | #include <error.h> |
23 | #include <grp.h> |
24 | #include <libintl.h> |
25 | #include <stdbool.h> |
26 | #include <stddef.h> |
27 | #include <stdio.h> |
28 | #include <stdint.h> |
29 | #include <stdlib.h> |
30 | #include <string.h> |
31 | #include <unistd.h> |
32 | #include <sys/mman.h> |
33 | #include <sys/socket.h> |
34 | #include <stackinfo.h> |
35 | |
36 | #include "nscd.h" |
37 | #include "dbg_log.h" |
38 | #ifdef HAVE_SENDFILE |
39 | # include <kernel-features.h> |
40 | #endif |
41 | |
42 | /* This is the standard reply in case the service is disabled. */ |
43 | static const gr_response_header disabled = |
44 | { |
45 | .version = NSCD_VERSION, |
46 | .found = -1, |
47 | .gr_name_len = 0, |
48 | .gr_passwd_len = 0, |
49 | .gr_gid = -1, |
50 | .gr_mem_cnt = 0, |
51 | }; |
52 | |
53 | /* This is the struct describing how to write this record. */ |
54 | const struct iovec grp_iov_disabled = |
55 | { |
56 | .iov_base = (void *) &disabled, |
57 | .iov_len = sizeof (disabled) |
58 | }; |
59 | |
60 | |
61 | /* This is the standard reply in case we haven't found the dataset. */ |
62 | static const gr_response_header notfound = |
63 | { |
64 | .version = NSCD_VERSION, |
65 | .found = 0, |
66 | .gr_name_len = 0, |
67 | .gr_passwd_len = 0, |
68 | .gr_gid = -1, |
69 | .gr_mem_cnt = 0, |
70 | }; |
71 | |
72 | |
73 | static time_t |
74 | cache_addgr (struct database_dyn *db, int fd, request_header *req, |
75 | const void *key, struct group *grp, uid_t owner, |
76 | struct hashentry *const he, struct datahead *dh, int errval) |
77 | { |
78 | bool all_written = true; |
79 | ssize_t total; |
80 | time_t t = time (NULL); |
81 | |
82 | /* We allocate all data in one memory block: the iov vector, |
83 | the response header and the dataset itself. */ |
84 | struct dataset |
85 | { |
86 | struct datahead head; |
87 | gr_response_header resp; |
88 | char strdata[0]; |
89 | } *dataset; |
90 | |
91 | assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data)); |
92 | |
93 | time_t timeout = MAX_TIMEOUT_VALUE; |
94 | if (grp == NULL) |
95 | { |
96 | if (he != NULL && errval == EAGAIN) |
97 | { |
98 | /* If we have an old record available but cannot find one |
99 | now because the service is not available we keep the old |
100 | record and make sure it does not get removed. */ |
101 | if (reload_count != UINT_MAX) |
102 | /* Do not reset the value if we never not reload the record. */ |
103 | dh->nreloads = reload_count - 1; |
104 | |
105 | /* Reload with the same time-to-live value. */ |
106 | timeout = dh->timeout = t + db->postimeout; |
107 | |
108 | total = 0; |
109 | } |
110 | else |
111 | { |
112 | /* We have no data. This means we send the standard reply for this |
113 | case. */ |
114 | total = sizeof (notfound); |
115 | |
116 | if (fd != -1 |
117 | && TEMP_FAILURE_RETRY (send (fd, ¬found, total, |
118 | MSG_NOSIGNAL)) != total) |
119 | all_written = false; |
120 | |
121 | /* If we have a transient error or cannot permanently store |
122 | the result, so be it. */ |
123 | if (errno == EAGAIN || __builtin_expect (db->negtimeout == 0, 0)) |
124 | { |
125 | /* Mark the old entry as obsolete. */ |
126 | if (dh != NULL) |
127 | dh->usable = false; |
128 | } |
129 | else if ((dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, 1)) != NULL) |
130 | { |
131 | timeout = datahead_init_neg (&dataset->head, |
132 | (sizeof (struct dataset) |
133 | + req->key_len), total, |
134 | db->negtimeout); |
135 | |
136 | /* This is the reply. */ |
137 | memcpy (&dataset->resp, ¬found, total); |
138 | |
139 | /* Copy the key data. */ |
140 | memcpy (dataset->strdata, key, req->key_len); |
141 | |
142 | /* If necessary, we also propagate the data to disk. */ |
143 | if (db->persistent) |
144 | { |
145 | // XXX async OK? |
146 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
147 | msync ((void *) pval, |
148 | ((uintptr_t) dataset & pagesize_m1) |
149 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); |
150 | } |
151 | |
152 | (void) cache_add (req->type, &dataset->strdata, req->key_len, |
153 | &dataset->head, true, db, owner, he == NULL); |
154 | |
155 | pthread_rwlock_unlock (&db->lock); |
156 | |
157 | /* Mark the old entry as obsolete. */ |
158 | if (dh != NULL) |
159 | dh->usable = false; |
160 | } |
161 | } |
162 | } |
163 | else |
164 | { |
165 | /* Determine the I/O structure. */ |
166 | size_t gr_name_len = strlen (grp->gr_name) + 1; |
167 | size_t gr_passwd_len = strlen (grp->gr_passwd) + 1; |
168 | size_t gr_mem_cnt = 0; |
169 | uint32_t *gr_mem_len; |
170 | size_t gr_mem_len_total = 0; |
171 | char *gr_name; |
172 | char *cp; |
173 | const size_t key_len = strlen (key); |
174 | const size_t buf_len = 3 * sizeof (grp->gr_gid) + key_len + 1; |
175 | size_t alloca_used = 0; |
176 | char *buf = alloca_account (buf_len, alloca_used); |
177 | ssize_t n; |
178 | size_t cnt; |
179 | |
180 | /* We need this to insert the `bygid' entry. */ |
181 | int key_offset; |
182 | n = snprintf (buf, buf_len, "%d%c%n%s" , grp->gr_gid, '\0', |
183 | &key_offset, (char *) key) + 1; |
184 | |
185 | /* Determine the length of all members. */ |
186 | while (grp->gr_mem[gr_mem_cnt]) |
187 | ++gr_mem_cnt; |
188 | gr_mem_len = alloca_account (gr_mem_cnt * sizeof (uint32_t), alloca_used); |
189 | for (gr_mem_cnt = 0; grp->gr_mem[gr_mem_cnt]; ++gr_mem_cnt) |
190 | { |
191 | gr_mem_len[gr_mem_cnt] = strlen (grp->gr_mem[gr_mem_cnt]) + 1; |
192 | gr_mem_len_total += gr_mem_len[gr_mem_cnt]; |
193 | } |
194 | |
195 | total = (offsetof (struct dataset, strdata) |
196 | + gr_mem_cnt * sizeof (uint32_t) |
197 | + gr_name_len + gr_passwd_len + gr_mem_len_total); |
198 | |
199 | /* If we refill the cache, first assume the reconrd did not |
200 | change. Allocate memory on the cache since it is likely |
201 | discarded anyway. If it turns out to be necessary to have a |
202 | new record we can still allocate real memory. */ |
203 | bool dataset_temporary = false; |
204 | bool dataset_malloced = false; |
205 | dataset = NULL; |
206 | |
207 | if (he == NULL) |
208 | dataset = (struct dataset *) mempool_alloc (db, total + n, 1); |
209 | |
210 | if (dataset == NULL) |
211 | { |
212 | /* We cannot permanently add the result in the moment. But |
213 | we can provide the result as is. Store the data in some |
214 | temporary memory. */ |
215 | if (! __libc_use_alloca (alloca_used + total + n)) |
216 | { |
217 | dataset = malloc (total + n); |
218 | /* Perhaps we should log a message that we were unable |
219 | to allocate memory for a large request. */ |
220 | if (dataset == NULL) |
221 | goto out; |
222 | dataset_malloced = true; |
223 | } |
224 | else |
225 | dataset = alloca_account (total + n, alloca_used); |
226 | |
227 | /* We cannot add this record to the permanent database. */ |
228 | dataset_temporary = true; |
229 | } |
230 | |
231 | timeout = datahead_init_pos (&dataset->head, total + n, |
232 | total - offsetof (struct dataset, resp), |
233 | he == NULL ? 0 : dh->nreloads + 1, |
234 | db->postimeout); |
235 | |
236 | dataset->resp.version = NSCD_VERSION; |
237 | dataset->resp.found = 1; |
238 | dataset->resp.gr_name_len = gr_name_len; |
239 | dataset->resp.gr_passwd_len = gr_passwd_len; |
240 | dataset->resp.gr_gid = grp->gr_gid; |
241 | dataset->resp.gr_mem_cnt = gr_mem_cnt; |
242 | |
243 | cp = dataset->strdata; |
244 | |
245 | /* This is the member string length array. */ |
246 | cp = mempcpy (cp, gr_mem_len, gr_mem_cnt * sizeof (uint32_t)); |
247 | gr_name = cp; |
248 | cp = mempcpy (cp, grp->gr_name, gr_name_len); |
249 | cp = mempcpy (cp, grp->gr_passwd, gr_passwd_len); |
250 | |
251 | for (cnt = 0; cnt < gr_mem_cnt; ++cnt) |
252 | cp = mempcpy (cp, grp->gr_mem[cnt], gr_mem_len[cnt]); |
253 | |
254 | /* Finally the stringified GID value. */ |
255 | memcpy (cp, buf, n); |
256 | char *key_copy = cp + key_offset; |
257 | assert (key_copy == (char *) rawmemchr (cp, '\0') + 1); |
258 | |
259 | assert (cp == dataset->strdata + total - offsetof (struct dataset, |
260 | strdata)); |
261 | |
262 | /* Now we can determine whether on refill we have to create a new |
263 | record or not. */ |
264 | if (he != NULL) |
265 | { |
266 | assert (fd == -1); |
267 | |
268 | if (total + n == dh->allocsize |
269 | && total - offsetof (struct dataset, resp) == dh->recsize |
270 | && memcmp (&dataset->resp, dh->data, |
271 | dh->allocsize - offsetof (struct dataset, resp)) == 0) |
272 | { |
273 | /* The data has not changed. We will just bump the |
274 | timeout value. Note that the new record has been |
275 | allocated on the stack and need not be freed. */ |
276 | dh->timeout = dataset->head.timeout; |
277 | ++dh->nreloads; |
278 | |
279 | /* If the new record was allocated via malloc, then we must free |
280 | it here. */ |
281 | if (dataset_malloced) |
282 | free (dataset); |
283 | } |
284 | else |
285 | { |
286 | /* We have to create a new record. Just allocate |
287 | appropriate memory and copy it. */ |
288 | struct dataset *newp |
289 | = (struct dataset *) mempool_alloc (db, total + n, 1); |
290 | if (newp != NULL) |
291 | { |
292 | /* Adjust pointers into the memory block. */ |
293 | gr_name = (char *) newp + (gr_name - (char *) dataset); |
294 | cp = (char *) newp + (cp - (char *) dataset); |
295 | key_copy = (char *) newp + (key_copy - (char *) dataset); |
296 | |
297 | dataset = memcpy (newp, dataset, total + n); |
298 | dataset_temporary = false; |
299 | } |
300 | |
301 | /* Mark the old record as obsolete. */ |
302 | dh->usable = false; |
303 | } |
304 | } |
305 | else |
306 | { |
307 | /* We write the dataset before inserting it to the database |
308 | since while inserting this thread might block and so would |
309 | unnecessarily let the receiver wait. */ |
310 | assert (fd != -1); |
311 | |
312 | #ifdef HAVE_SENDFILE |
313 | if (__builtin_expect (db->mmap_used, 1) && ! dataset_temporary) |
314 | { |
315 | assert (db->wr_fd != -1); |
316 | assert ((char *) &dataset->resp > (char *) db->data); |
317 | assert ((char *) dataset - (char *) db->head |
318 | + total |
319 | <= (sizeof (struct database_pers_head) |
320 | + db->head->module * sizeof (ref_t) |
321 | + db->head->data_size)); |
322 | ssize_t written = sendfileall (fd, db->wr_fd, |
323 | (char *) &dataset->resp |
324 | - (char *) db->head, |
325 | dataset->head.recsize); |
326 | if (written != dataset->head.recsize) |
327 | { |
328 | # ifndef __ASSUME_SENDFILE |
329 | if (written == -1 && errno == ENOSYS) |
330 | goto use_write; |
331 | # endif |
332 | all_written = false; |
333 | } |
334 | } |
335 | else |
336 | # ifndef __ASSUME_SENDFILE |
337 | use_write: |
338 | # endif |
339 | #endif |
340 | if (writeall (fd, &dataset->resp, dataset->head.recsize) |
341 | != dataset->head.recsize) |
342 | all_written = false; |
343 | } |
344 | |
345 | /* Add the record to the database. But only if it has not been |
346 | stored on the stack. */ |
347 | if (! dataset_temporary) |
348 | { |
349 | /* If necessary, we also propagate the data to disk. */ |
350 | if (db->persistent) |
351 | { |
352 | // XXX async OK? |
353 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
354 | msync ((void *) pval, |
355 | ((uintptr_t) dataset & pagesize_m1) + total + n, |
356 | MS_ASYNC); |
357 | } |
358 | |
359 | /* NB: in the following code we always must add the entry |
360 | marked with FIRST first. Otherwise we end up with |
361 | dangling "pointers" in case a latter hash entry cannot be |
362 | added. */ |
363 | bool first = true; |
364 | |
365 | /* If the request was by GID, add that entry first. */ |
366 | if (req->type == GETGRBYGID) |
367 | { |
368 | if (cache_add (GETGRBYGID, cp, key_offset, &dataset->head, true, |
369 | db, owner, he == NULL) < 0) |
370 | goto out; |
371 | |
372 | first = false; |
373 | } |
374 | /* If the key is different from the name add a separate entry. */ |
375 | else if (strcmp (key_copy, gr_name) != 0) |
376 | { |
377 | if (cache_add (GETGRBYNAME, key_copy, key_len + 1, |
378 | &dataset->head, true, db, owner, he == NULL) < 0) |
379 | goto out; |
380 | |
381 | first = false; |
382 | } |
383 | |
384 | /* We have to add the value for both, byname and byuid. */ |
385 | if ((req->type == GETGRBYNAME || db->propagate) |
386 | && __builtin_expect (cache_add (GETGRBYNAME, gr_name, |
387 | gr_name_len, |
388 | &dataset->head, first, db, owner, |
389 | he == NULL) |
390 | == 0, 1)) |
391 | { |
392 | if (req->type == GETGRBYNAME && db->propagate) |
393 | (void) cache_add (GETGRBYGID, cp, key_offset, &dataset->head, |
394 | false, db, owner, false); |
395 | } |
396 | |
397 | out: |
398 | pthread_rwlock_unlock (&db->lock); |
399 | } |
400 | } |
401 | |
402 | if (__builtin_expect (!all_written, 0) && debug_level > 0) |
403 | { |
404 | char buf[256]; |
405 | dbg_log (_("short write in %s: %s" ), __FUNCTION__, |
406 | strerror_r (errno, buf, sizeof (buf))); |
407 | } |
408 | |
409 | return timeout; |
410 | } |
411 | |
412 | |
413 | union keytype |
414 | { |
415 | void *v; |
416 | gid_t g; |
417 | }; |
418 | |
419 | |
420 | static int |
421 | lookup (int type, union keytype key, struct group *resultbufp, char *buffer, |
422 | size_t buflen, struct group **grp) |
423 | { |
424 | if (type == GETGRBYNAME) |
425 | return __getgrnam_r (key.v, resultbufp, buffer, buflen, grp); |
426 | else |
427 | return __getgrgid_r (key.g, resultbufp, buffer, buflen, grp); |
428 | } |
429 | |
430 | |
431 | static time_t |
432 | addgrbyX (struct database_dyn *db, int fd, request_header *req, |
433 | union keytype key, const char *keystr, uid_t uid, |
434 | struct hashentry *he, struct datahead *dh) |
435 | { |
436 | /* Search for the entry matching the key. Please note that we don't |
437 | look again in the table whether the dataset is now available. We |
438 | simply insert it. It does not matter if it is in there twice. The |
439 | pruning function only will look at the timestamp. */ |
440 | size_t buflen = 1024; |
441 | char *buffer = (char *) alloca (buflen); |
442 | struct group resultbuf; |
443 | struct group *grp; |
444 | bool use_malloc = false; |
445 | int errval = 0; |
446 | |
447 | if (__glibc_unlikely (debug_level > 0)) |
448 | { |
449 | if (he == NULL) |
450 | dbg_log (_("Haven't found \"%s\" in group cache!" ), keystr); |
451 | else |
452 | dbg_log (_("Reloading \"%s\" in group cache!" ), keystr); |
453 | } |
454 | |
455 | while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0 |
456 | && (errval = errno) == ERANGE) |
457 | { |
458 | errno = 0; |
459 | |
460 | if (__glibc_unlikely (buflen > 32768)) |
461 | { |
462 | char *old_buffer = buffer; |
463 | buflen *= 2; |
464 | buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen); |
465 | if (buffer == NULL) |
466 | { |
467 | /* We ran out of memory. We cannot do anything but |
468 | sending a negative response. In reality this should |
469 | never happen. */ |
470 | grp = NULL; |
471 | buffer = old_buffer; |
472 | |
473 | /* We set the error to indicate this is (possibly) a |
474 | temporary error and that it does not mean the entry |
475 | is not available at all. */ |
476 | errval = EAGAIN; |
477 | break; |
478 | } |
479 | use_malloc = true; |
480 | } |
481 | else |
482 | /* Allocate a new buffer on the stack. If possible combine it |
483 | with the previously allocated buffer. */ |
484 | buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen); |
485 | } |
486 | |
487 | time_t timeout = cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval); |
488 | |
489 | if (use_malloc) |
490 | free (buffer); |
491 | |
492 | return timeout; |
493 | } |
494 | |
495 | |
496 | void |
497 | addgrbyname (struct database_dyn *db, int fd, request_header *req, |
498 | void *key, uid_t uid) |
499 | { |
500 | union keytype u = { .v = key }; |
501 | |
502 | addgrbyX (db, fd, req, u, key, uid, NULL, NULL); |
503 | } |
504 | |
505 | |
506 | time_t |
507 | readdgrbyname (struct database_dyn *db, struct hashentry *he, |
508 | struct datahead *dh) |
509 | { |
510 | request_header req = |
511 | { |
512 | .type = GETGRBYNAME, |
513 | .key_len = he->len |
514 | }; |
515 | union keytype u = { .v = db->data + he->key }; |
516 | |
517 | return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh); |
518 | } |
519 | |
520 | |
521 | void |
522 | addgrbygid (struct database_dyn *db, int fd, request_header *req, |
523 | void *key, uid_t uid) |
524 | { |
525 | char *ep; |
526 | gid_t gid = strtoul ((char *) key, &ep, 10); |
527 | |
528 | if (*(char *) key == '\0' || *ep != '\0') /* invalid numeric uid */ |
529 | { |
530 | if (debug_level > 0) |
531 | dbg_log (_("Invalid numeric gid \"%s\"!" ), (char *) key); |
532 | |
533 | errno = EINVAL; |
534 | return; |
535 | } |
536 | |
537 | union keytype u = { .g = gid }; |
538 | |
539 | addgrbyX (db, fd, req, u, key, uid, NULL, NULL); |
540 | } |
541 | |
542 | |
543 | time_t |
544 | readdgrbygid (struct database_dyn *db, struct hashentry *he, |
545 | struct datahead *dh) |
546 | { |
547 | char *ep; |
548 | gid_t gid = strtoul (db->data + he->key, &ep, 10); |
549 | |
550 | /* Since the key has been added before it must be OK. */ |
551 | assert (*(db->data + he->key) != '\0' && *ep == '\0'); |
552 | |
553 | request_header req = |
554 | { |
555 | .type = GETGRBYGID, |
556 | .key_len = he->len |
557 | }; |
558 | union keytype u = { .g = gid }; |
559 | |
560 | return addgrbyX (db, -1, &req, u, db->data + he->key, he->owner, he, dh); |
561 | } |
562 | |