1 | /* Cache handling for host lookup. |
2 | Copyright (C) 2004-2016 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 | |
29 | #include "dbg_log.h" |
30 | #include "nscd.h" |
31 | #ifdef HAVE_SENDFILE |
32 | # include <kernel-features.h> |
33 | #endif |
34 | |
35 | #include "../nss/nsswitch.h" |
36 | |
37 | |
38 | /* Type of the lookup function. */ |
39 | typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t, |
40 | long int *, long int *, |
41 | gid_t **, long int, int *); |
42 | |
43 | |
44 | static const initgr_response_header notfound = |
45 | { |
46 | .version = NSCD_VERSION, |
47 | .found = 0, |
48 | .ngrps = 0 |
49 | }; |
50 | |
51 | |
52 | #include "../grp/compat-initgroups.c" |
53 | |
54 | |
55 | static time_t |
56 | addinitgroupsX (struct database_dyn *db, int fd, request_header *req, |
57 | void *key, uid_t uid, struct hashentry *const he, |
58 | struct datahead *dh) |
59 | { |
60 | /* Search for the entry matching the key. Please note that we don't |
61 | look again in the table whether the dataset is now available. We |
62 | simply insert it. It does not matter if it is in there twice. The |
63 | pruning function only will look at the timestamp. */ |
64 | |
65 | |
66 | /* We allocate all data in one memory block: the iov vector, |
67 | the response header and the dataset itself. */ |
68 | struct dataset |
69 | { |
70 | struct datahead head; |
71 | initgr_response_header resp; |
72 | char strdata[0]; |
73 | } *dataset = NULL; |
74 | |
75 | if (__glibc_unlikely (debug_level > 0)) |
76 | { |
77 | if (he == NULL) |
78 | dbg_log (_("Haven't found \"%s\" in group cache!" ), (char *) key); |
79 | else |
80 | dbg_log (_("Reloading \"%s\" in group cache!" ), (char *) key); |
81 | } |
82 | |
83 | static service_user *group_database; |
84 | service_user *nip; |
85 | int no_more; |
86 | |
87 | if (group_database == NULL) |
88 | no_more = __nss_database_lookup ("group" , NULL, |
89 | "compat [NOTFOUND=return] files" , |
90 | &group_database); |
91 | else |
92 | no_more = 0; |
93 | nip = group_database; |
94 | |
95 | /* We always use sysconf even if NGROUPS_MAX is defined. That way, the |
96 | limit can be raised in the kernel configuration without having to |
97 | recompile libc. */ |
98 | long int limit = __sysconf (_SC_NGROUPS_MAX); |
99 | |
100 | long int size; |
101 | if (limit > 0) |
102 | /* We limit the size of the intially allocated array. */ |
103 | size = MIN (limit, 64); |
104 | else |
105 | /* No fixed limit on groups. Pick a starting buffer size. */ |
106 | size = 16; |
107 | |
108 | long int start = 0; |
109 | bool all_tryagain = true; |
110 | bool any_success = false; |
111 | |
112 | /* This is temporary memory, we need not (and must not) call |
113 | mempool_alloc. */ |
114 | // XXX This really should use alloca. need to change the backends. |
115 | gid_t *groups = (gid_t *) malloc (size * sizeof (gid_t)); |
116 | if (__glibc_unlikely (groups == NULL)) |
117 | /* No more memory. */ |
118 | goto out; |
119 | |
120 | /* Nothing added yet. */ |
121 | while (! no_more) |
122 | { |
123 | long int prev_start = start; |
124 | enum nss_status status; |
125 | initgroups_dyn_function fct; |
126 | fct = __nss_lookup_function (nip, "initgroups_dyn" ); |
127 | |
128 | if (fct == NULL) |
129 | { |
130 | status = compat_call (nip, key, -1, &start, &size, &groups, |
131 | limit, &errno); |
132 | |
133 | if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE) |
134 | break; |
135 | } |
136 | else |
137 | status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups, |
138 | limit, &errno)); |
139 | |
140 | /* Remove duplicates. */ |
141 | long int cnt = prev_start; |
142 | while (cnt < start) |
143 | { |
144 | long int inner; |
145 | for (inner = 0; inner < prev_start; ++inner) |
146 | if (groups[inner] == groups[cnt]) |
147 | break; |
148 | |
149 | if (inner < prev_start) |
150 | groups[cnt] = groups[--start]; |
151 | else |
152 | ++cnt; |
153 | } |
154 | |
155 | if (status != NSS_STATUS_TRYAGAIN) |
156 | all_tryagain = false; |
157 | |
158 | /* This is really only for debugging. */ |
159 | if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN) |
160 | __libc_fatal ("illegal status in internal_getgrouplist" ); |
161 | |
162 | any_success |= status == NSS_STATUS_SUCCESS; |
163 | |
164 | if (status != NSS_STATUS_SUCCESS |
165 | && nss_next_action (nip, status) == NSS_ACTION_RETURN) |
166 | break; |
167 | |
168 | if (nip->next == NULL) |
169 | no_more = -1; |
170 | else |
171 | nip = nip->next; |
172 | } |
173 | |
174 | bool all_written; |
175 | ssize_t total; |
176 | time_t timeout; |
177 | out: |
178 | all_written = true; |
179 | timeout = MAX_TIMEOUT_VALUE; |
180 | if (!any_success) |
181 | { |
182 | /* Nothing found. Create a negative result record. */ |
183 | total = sizeof (notfound); |
184 | |
185 | if (he != NULL && all_tryagain) |
186 | { |
187 | /* If we have an old record available but cannot find one now |
188 | because the service is not available we keep the old record |
189 | and make sure it does not get removed. */ |
190 | if (reload_count != UINT_MAX && dh->nreloads == reload_count) |
191 | /* Do not reset the value if we never not reload the record. */ |
192 | dh->nreloads = reload_count - 1; |
193 | |
194 | /* Reload with the same time-to-live value. */ |
195 | timeout = dh->timeout = time (NULL) + db->postimeout; |
196 | } |
197 | else |
198 | { |
199 | /* We have no data. This means we send the standard reply for this |
200 | case. */ |
201 | if (fd != -1 |
202 | && TEMP_FAILURE_RETRY (send (fd, ¬found, total, |
203 | MSG_NOSIGNAL)) != total) |
204 | all_written = false; |
205 | |
206 | /* If we have a transient error or cannot permanently store |
207 | the result, so be it. */ |
208 | if (all_tryagain || __builtin_expect (db->negtimeout == 0, 0)) |
209 | { |
210 | /* Mark the old entry as obsolete. */ |
211 | if (dh != NULL) |
212 | dh->usable = false; |
213 | } |
214 | else if ((dataset = mempool_alloc (db, (sizeof (struct dataset) |
215 | + req->key_len), 1)) != NULL) |
216 | { |
217 | timeout = datahead_init_neg (&dataset->head, |
218 | (sizeof (struct dataset) |
219 | + req->key_len), total, |
220 | db->negtimeout); |
221 | |
222 | /* This is the reply. */ |
223 | memcpy (&dataset->resp, ¬found, total); |
224 | |
225 | /* Copy the key data. */ |
226 | char *key_copy = memcpy (dataset->strdata, key, req->key_len); |
227 | |
228 | /* If necessary, we also propagate the data to disk. */ |
229 | if (db->persistent) |
230 | { |
231 | // XXX async OK? |
232 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
233 | msync ((void *) pval, |
234 | ((uintptr_t) dataset & pagesize_m1) |
235 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); |
236 | } |
237 | |
238 | (void) cache_add (req->type, key_copy, req->key_len, |
239 | &dataset->head, true, db, uid, he == NULL); |
240 | |
241 | pthread_rwlock_unlock (&db->lock); |
242 | |
243 | /* Mark the old entry as obsolete. */ |
244 | if (dh != NULL) |
245 | dh->usable = false; |
246 | } |
247 | } |
248 | } |
249 | else |
250 | { |
251 | |
252 | total = offsetof (struct dataset, strdata) + start * sizeof (int32_t); |
253 | |
254 | /* If we refill the cache, first assume the reconrd did not |
255 | change. Allocate memory on the cache since it is likely |
256 | discarded anyway. If it turns out to be necessary to have a |
257 | new record we can still allocate real memory. */ |
258 | bool alloca_used = false; |
259 | dataset = NULL; |
260 | |
261 | if (he == NULL) |
262 | dataset = (struct dataset *) mempool_alloc (db, total + req->key_len, |
263 | 1); |
264 | |
265 | if (dataset == NULL) |
266 | { |
267 | /* We cannot permanently add the result in the moment. But |
268 | we can provide the result as is. Store the data in some |
269 | temporary memory. */ |
270 | dataset = (struct dataset *) alloca (total + req->key_len); |
271 | |
272 | /* We cannot add this record to the permanent database. */ |
273 | alloca_used = true; |
274 | } |
275 | |
276 | timeout = datahead_init_pos (&dataset->head, total + req->key_len, |
277 | total - offsetof (struct dataset, resp), |
278 | he == NULL ? 0 : dh->nreloads + 1, |
279 | db->postimeout); |
280 | |
281 | dataset->resp.version = NSCD_VERSION; |
282 | dataset->resp.found = 1; |
283 | dataset->resp.ngrps = start; |
284 | |
285 | char *cp = dataset->strdata; |
286 | |
287 | /* Copy the GID values. If the size of the types match this is |
288 | very simple. */ |
289 | if (sizeof (gid_t) == sizeof (int32_t)) |
290 | cp = mempcpy (cp, groups, start * sizeof (gid_t)); |
291 | else |
292 | { |
293 | gid_t *gcp = (gid_t *) cp; |
294 | |
295 | for (int i = 0; i < start; ++i) |
296 | *gcp++ = groups[i]; |
297 | |
298 | cp = (char *) gcp; |
299 | } |
300 | |
301 | /* Finally the user name. */ |
302 | memcpy (cp, key, req->key_len); |
303 | |
304 | assert (cp == dataset->strdata + total - offsetof (struct dataset, |
305 | strdata)); |
306 | |
307 | /* Now we can determine whether on refill we have to create a new |
308 | record or not. */ |
309 | if (he != NULL) |
310 | { |
311 | assert (fd == -1); |
312 | |
313 | if (total + req->key_len == dh->allocsize |
314 | && total - offsetof (struct dataset, resp) == dh->recsize |
315 | && memcmp (&dataset->resp, dh->data, |
316 | dh->allocsize - offsetof (struct dataset, resp)) == 0) |
317 | { |
318 | /* The data has not changed. We will just bump the |
319 | timeout value. Note that the new record has been |
320 | allocated on the stack and need not be freed. */ |
321 | dh->timeout = dataset->head.timeout; |
322 | ++dh->nreloads; |
323 | } |
324 | else |
325 | { |
326 | /* We have to create a new record. Just allocate |
327 | appropriate memory and copy it. */ |
328 | struct dataset *newp |
329 | = (struct dataset *) mempool_alloc (db, total + req->key_len, |
330 | 1); |
331 | if (newp != NULL) |
332 | { |
333 | /* Adjust pointer into the memory block. */ |
334 | cp = (char *) newp + (cp - (char *) dataset); |
335 | |
336 | dataset = memcpy (newp, dataset, total + req->key_len); |
337 | alloca_used = false; |
338 | } |
339 | |
340 | /* Mark the old record as obsolete. */ |
341 | dh->usable = false; |
342 | } |
343 | } |
344 | else |
345 | { |
346 | /* We write the dataset before inserting it to the database |
347 | since while inserting this thread might block and so would |
348 | unnecessarily let the receiver wait. */ |
349 | assert (fd != -1); |
350 | |
351 | #ifdef HAVE_SENDFILE |
352 | if (__builtin_expect (db->mmap_used, 1) && !alloca_used) |
353 | { |
354 | assert (db->wr_fd != -1); |
355 | assert ((char *) &dataset->resp > (char *) db->data); |
356 | assert ((char *) dataset - (char *) db->head |
357 | + total |
358 | <= (sizeof (struct database_pers_head) |
359 | + db->head->module * sizeof (ref_t) |
360 | + db->head->data_size)); |
361 | ssize_t written = sendfileall (fd, db->wr_fd, |
362 | (char *) &dataset->resp |
363 | - (char *) db->head, |
364 | dataset->head.recsize); |
365 | if (written != dataset->head.recsize) |
366 | { |
367 | # ifndef __ASSUME_SENDFILE |
368 | if (written == -1 && errno == ENOSYS) |
369 | goto use_write; |
370 | # endif |
371 | all_written = false; |
372 | } |
373 | } |
374 | else |
375 | # ifndef __ASSUME_SENDFILE |
376 | use_write: |
377 | # endif |
378 | #endif |
379 | if (writeall (fd, &dataset->resp, dataset->head.recsize) |
380 | != dataset->head.recsize) |
381 | all_written = false; |
382 | } |
383 | |
384 | |
385 | /* Add the record to the database. But only if it has not been |
386 | stored on the stack. */ |
387 | if (! alloca_used) |
388 | { |
389 | /* If necessary, we also propagate the data to disk. */ |
390 | if (db->persistent) |
391 | { |
392 | // XXX async OK? |
393 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
394 | msync ((void *) pval, |
395 | ((uintptr_t) dataset & pagesize_m1) + total + |
396 | req->key_len, MS_ASYNC); |
397 | } |
398 | |
399 | (void) cache_add (INITGROUPS, cp, req->key_len, &dataset->head, true, |
400 | db, uid, he == NULL); |
401 | |
402 | pthread_rwlock_unlock (&db->lock); |
403 | } |
404 | } |
405 | |
406 | free (groups); |
407 | |
408 | if (__builtin_expect (!all_written, 0) && debug_level > 0) |
409 | { |
410 | char buf[256]; |
411 | dbg_log (_("short write in %s: %s" ), __FUNCTION__, |
412 | strerror_r (errno, buf, sizeof (buf))); |
413 | } |
414 | |
415 | return timeout; |
416 | } |
417 | |
418 | |
419 | void |
420 | addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key, |
421 | uid_t uid) |
422 | { |
423 | addinitgroupsX (db, fd, req, key, uid, NULL, NULL); |
424 | } |
425 | |
426 | |
427 | time_t |
428 | readdinitgroups (struct database_dyn *db, struct hashentry *he, |
429 | struct datahead *dh) |
430 | { |
431 | request_header req = |
432 | { |
433 | .type = INITGROUPS, |
434 | .key_len = he->len |
435 | }; |
436 | |
437 | return addinitgroupsX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
438 | } |
439 | |