1 | /* Cache handling for host lookup. |
2 | Copyright (C) 2004-2024 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | This program is free software; you can redistribute it and/or modify |
6 | it under the terms of the GNU General Public License as published |
7 | by the Free Software Foundation; version 2 of the License, or |
8 | (at your option) any later version. |
9 | |
10 | This program is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | GNU General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU General Public License |
16 | along with this program; if not, see <https://www.gnu.org/licenses/>. */ |
17 | |
18 | #include <assert.h> |
19 | #include <errno.h> |
20 | #include <grp.h> |
21 | #include <libintl.h> |
22 | #include <string.h> |
23 | #include <time.h> |
24 | #include <unistd.h> |
25 | #include <sys/mman.h> |
26 | #include <scratch_buffer.h> |
27 | #include <config.h> |
28 | |
29 | #include "dbg_log.h" |
30 | #include "nscd.h" |
31 | |
32 | #include "../nss/nsswitch.h" |
33 | |
34 | /* Type of the lookup function. */ |
35 | typedef enum nss_status (*initgroups_dyn_function) (const char *, gid_t, |
36 | long int *, long int *, |
37 | gid_t **, long int, int *); |
38 | |
39 | |
40 | static const initgr_response_header notfound = |
41 | { |
42 | .version = NSCD_VERSION, |
43 | .found = 0, |
44 | .ngrps = 0 |
45 | }; |
46 | |
47 | |
48 | #include "../nss/initgroups-fallback.c" |
49 | |
50 | |
51 | static time_t |
52 | addinitgroupsX (struct database_dyn *db, int fd, request_header *req, |
53 | void *key, uid_t uid, struct hashentry *const he, |
54 | struct datahead *dh) |
55 | { |
56 | /* Search for the entry matching the key. Please note that we don't |
57 | look again in the table whether the dataset is now available. We |
58 | simply insert it. It does not matter if it is in there twice. The |
59 | pruning function only will look at the timestamp. */ |
60 | |
61 | |
62 | /* We allocate all data in one memory block: the iov vector, |
63 | the response header and the dataset itself. */ |
64 | struct dataset |
65 | { |
66 | struct datahead head; |
67 | initgr_response_header resp; |
68 | char strdata[0]; |
69 | } *dataset = NULL; |
70 | |
71 | if (__glibc_unlikely (debug_level > 0)) |
72 | { |
73 | if (he == NULL) |
74 | dbg_log (_("Haven't found \"%s\" in group cache!" ), (char *) key); |
75 | else |
76 | dbg_log (_("Reloading \"%s\" in group cache!" ), (char *) key); |
77 | } |
78 | |
79 | static nss_action_list group_database; |
80 | nss_action_list nip; |
81 | int no_more; |
82 | |
83 | if (group_database == NULL) |
84 | no_more = !__nss_database_get (db: nss_database_group, actions: &group_database); |
85 | else |
86 | no_more = 0; |
87 | nip = group_database; |
88 | |
89 | /* We always use sysconf even if NGROUPS_MAX is defined. That way, the |
90 | limit can be raised in the kernel configuration without having to |
91 | recompile libc. */ |
92 | long int limit = __sysconf (_SC_NGROUPS_MAX); |
93 | |
94 | long int size; |
95 | if (limit > 0) |
96 | /* We limit the size of the initially allocated array. */ |
97 | size = MIN (limit, 64); |
98 | else |
99 | /* No fixed limit on groups. Pick a starting buffer size. */ |
100 | size = 16; |
101 | |
102 | long int start = 0; |
103 | bool all_tryagain = true; |
104 | bool any_success = false; |
105 | |
106 | /* This is temporary memory, we need not (and must not) call |
107 | mempool_alloc. */ |
108 | // XXX This really should use alloca. need to change the backends. |
109 | gid_t *groups = (gid_t *) malloc (size: size * sizeof (gid_t)); |
110 | if (__glibc_unlikely (groups == NULL)) |
111 | /* No more memory. */ |
112 | goto out; |
113 | |
114 | /* Nothing added yet. */ |
115 | while (! no_more) |
116 | { |
117 | long int prev_start = start; |
118 | enum nss_status status; |
119 | initgroups_dyn_function fct; |
120 | fct = __nss_lookup_function (ni: nip, fct_name: "initgroups_dyn" ); |
121 | |
122 | if (fct == NULL) |
123 | { |
124 | status = compat_call (nip, user: key, group: -1, start: &start, size: &size, groupsp: &groups, |
125 | limit, errnop: &errno); |
126 | |
127 | if (nss_next_action (nip, NSS_STATUS_UNAVAIL) != NSS_ACTION_CONTINUE) |
128 | break; |
129 | } |
130 | else |
131 | status = DL_CALL_FCT (fct, (key, -1, &start, &size, &groups, |
132 | limit, &errno)); |
133 | |
134 | /* Remove duplicates. */ |
135 | long int cnt = prev_start; |
136 | while (cnt < start) |
137 | { |
138 | long int inner; |
139 | for (inner = 0; inner < prev_start; ++inner) |
140 | if (groups[inner] == groups[cnt]) |
141 | break; |
142 | |
143 | if (inner < prev_start) |
144 | groups[cnt] = groups[--start]; |
145 | else |
146 | ++cnt; |
147 | } |
148 | |
149 | if (status != NSS_STATUS_TRYAGAIN) |
150 | all_tryagain = false; |
151 | |
152 | /* This is really only for debugging. */ |
153 | if (NSS_STATUS_TRYAGAIN > status || status > NSS_STATUS_RETURN) |
154 | __libc_fatal (message: "Illegal status in internal_getgrouplist.\n" ); |
155 | |
156 | any_success |= status == NSS_STATUS_SUCCESS; |
157 | |
158 | if (status != NSS_STATUS_SUCCESS |
159 | && nss_next_action (nip, status) == NSS_ACTION_RETURN) |
160 | break; |
161 | |
162 | if (nip[1].module == NULL) |
163 | no_more = -1; |
164 | else |
165 | ++nip; |
166 | } |
167 | |
168 | bool all_written; |
169 | ssize_t total; |
170 | time_t timeout; |
171 | out: |
172 | all_written = true; |
173 | timeout = MAX_TIMEOUT_VALUE; |
174 | if (!any_success) |
175 | { |
176 | /* Nothing found. Create a negative result record. */ |
177 | total = sizeof (notfound); |
178 | |
179 | if (he != NULL && all_tryagain) |
180 | { |
181 | /* If we have an old record available but cannot find one now |
182 | because the service is not available we keep the old record |
183 | and make sure it does not get removed. */ |
184 | if (reload_count != UINT_MAX && dh->nreloads == reload_count) |
185 | /* Do not reset the value if we never not reload the record. */ |
186 | dh->nreloads = reload_count - 1; |
187 | |
188 | /* Reload with the same time-to-live value. */ |
189 | timeout = dh->timeout = time (NULL) + db->postimeout; |
190 | } |
191 | else |
192 | { |
193 | /* We have no data. This means we send the standard reply for this |
194 | case. */ |
195 | if (fd != -1 |
196 | && TEMP_FAILURE_RETRY (send (fd, ¬found, total, |
197 | MSG_NOSIGNAL)) != total) |
198 | all_written = false; |
199 | |
200 | /* If we have a transient error or cannot permanently store |
201 | the result, so be it. */ |
202 | if (all_tryagain || __builtin_expect (db->negtimeout == 0, 0)) |
203 | { |
204 | /* Mark the old entry as obsolete. */ |
205 | if (dh != NULL) |
206 | dh->usable = false; |
207 | } |
208 | else if ((dataset = mempool_alloc (db, len: (sizeof (struct dataset) |
209 | + req->key_len), data_alloc: 1)) != NULL) |
210 | { |
211 | timeout = datahead_init_neg (head: &dataset->head, |
212 | allocsize: (sizeof (struct dataset) |
213 | + req->key_len), recsize: total, |
214 | ttl: db->negtimeout); |
215 | |
216 | /* This is the reply. */ |
217 | memcpy (dest: &dataset->resp, src: ¬found, n: total); |
218 | |
219 | /* Copy the key data. */ |
220 | char *key_copy = memcpy (dest: dataset->strdata, src: key, n: req->key_len); |
221 | |
222 | /* If necessary, we also propagate the data to disk. */ |
223 | if (db->persistent) |
224 | { |
225 | // XXX async OK? |
226 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
227 | msync (addr: (void *) pval, |
228 | len: ((uintptr_t) dataset & pagesize_m1) |
229 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); |
230 | } |
231 | |
232 | (void) cache_add (type: req->type, key: key_copy, len: req->key_len, |
233 | packet: &dataset->head, true, table: db, owner: uid, prune_wakeup: he == NULL); |
234 | |
235 | pthread_rwlock_unlock (rwlock: &db->lock); |
236 | |
237 | /* Mark the old entry as obsolete. */ |
238 | if (dh != NULL) |
239 | dh->usable = false; |
240 | } |
241 | } |
242 | } |
243 | else |
244 | { |
245 | |
246 | total = offsetof (struct dataset, strdata) + start * sizeof (int32_t); |
247 | |
248 | /* If we refill the cache, first assume the reconrd did not |
249 | change. Allocate memory on the cache since it is likely |
250 | discarded anyway. If it turns out to be necessary to have a |
251 | new record we can still allocate real memory. */ |
252 | bool alloca_used = false; |
253 | dataset = NULL; |
254 | |
255 | if (he == NULL) |
256 | dataset = (struct dataset *) mempool_alloc (db, len: total + req->key_len, |
257 | data_alloc: 1); |
258 | |
259 | if (dataset == NULL) |
260 | { |
261 | /* We cannot permanently add the result in the moment. But |
262 | we can provide the result as is. Store the data in some |
263 | temporary memory. */ |
264 | dataset = (struct dataset *) alloca (total + req->key_len); |
265 | |
266 | /* We cannot add this record to the permanent database. */ |
267 | alloca_used = true; |
268 | } |
269 | |
270 | timeout = datahead_init_pos (head: &dataset->head, allocsize: total + req->key_len, |
271 | recsize: total - offsetof (struct dataset, resp), |
272 | nreloads: he == NULL ? 0 : dh->nreloads + 1, |
273 | ttl: db->postimeout); |
274 | |
275 | dataset->resp.version = NSCD_VERSION; |
276 | dataset->resp.found = 1; |
277 | dataset->resp.ngrps = start; |
278 | |
279 | char *cp = dataset->strdata; |
280 | |
281 | /* Copy the GID values. If the size of the types match this is |
282 | very simple. */ |
283 | if (sizeof (gid_t) == sizeof (int32_t)) |
284 | cp = mempcpy (cp, groups, start * sizeof (gid_t)); |
285 | else |
286 | { |
287 | gid_t *gcp = (gid_t *) cp; |
288 | |
289 | for (int i = 0; i < start; ++i) |
290 | *gcp++ = groups[i]; |
291 | |
292 | cp = (char *) gcp; |
293 | } |
294 | |
295 | /* Finally the user name. */ |
296 | memcpy (dest: cp, src: key, n: req->key_len); |
297 | |
298 | assert (cp == dataset->strdata + total - offsetof (struct dataset, |
299 | strdata)); |
300 | |
301 | /* Now we can determine whether on refill we have to create a new |
302 | record or not. */ |
303 | if (he != NULL) |
304 | { |
305 | assert (fd == -1); |
306 | |
307 | if (total + req->key_len == dh->allocsize |
308 | && total - offsetof (struct dataset, resp) == dh->recsize |
309 | && memcmp (s1: &dataset->resp, s2: dh->data, |
310 | n: dh->allocsize - offsetof (struct dataset, resp)) == 0) |
311 | { |
312 | /* The data has not changed. We will just bump the |
313 | timeout value. Note that the new record has been |
314 | allocated on the stack and need not be freed. */ |
315 | dh->timeout = dataset->head.timeout; |
316 | ++dh->nreloads; |
317 | } |
318 | else |
319 | { |
320 | /* We have to create a new record. Just allocate |
321 | appropriate memory and copy it. */ |
322 | struct dataset *newp |
323 | = (struct dataset *) mempool_alloc (db, len: total + req->key_len, |
324 | data_alloc: 1); |
325 | if (newp != NULL) |
326 | { |
327 | /* Adjust pointer into the memory block. */ |
328 | cp = (char *) newp + (cp - (char *) dataset); |
329 | |
330 | dataset = memcpy (dest: newp, src: dataset, n: total + req->key_len); |
331 | alloca_used = false; |
332 | } |
333 | |
334 | /* Mark the old record as obsolete. */ |
335 | dh->usable = false; |
336 | } |
337 | } |
338 | else |
339 | { |
340 | /* We write the dataset before inserting it to the database |
341 | since while inserting this thread might block and so would |
342 | unnecessarily let the receiver wait. */ |
343 | assert (fd != -1); |
344 | |
345 | if (writeall (fd, buf: &dataset->resp, len: dataset->head.recsize) |
346 | != dataset->head.recsize) |
347 | all_written = false; |
348 | } |
349 | |
350 | |
351 | /* Add the record to the database. But only if it has not been |
352 | stored on the stack. */ |
353 | if (! alloca_used) |
354 | { |
355 | /* If necessary, we also propagate the data to disk. */ |
356 | if (db->persistent) |
357 | { |
358 | // XXX async OK? |
359 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
360 | msync (addr: (void *) pval, |
361 | len: ((uintptr_t) dataset & pagesize_m1) + total |
362 | + req->key_len, MS_ASYNC); |
363 | } |
364 | |
365 | (void) cache_add (type: INITGROUPS, key: cp, len: req->key_len, packet: &dataset->head, true, |
366 | table: db, owner: uid, prune_wakeup: he == NULL); |
367 | |
368 | pthread_rwlock_unlock (rwlock: &db->lock); |
369 | } |
370 | } |
371 | |
372 | free (ptr: groups); |
373 | |
374 | if (__builtin_expect (!all_written, 0) && debug_level > 0) |
375 | { |
376 | char buf[256]; |
377 | dbg_log (_("short write in %s: %s" ), __FUNCTION__, |
378 | strerror_r (errno, buf: buf, buflen: sizeof (buf))); |
379 | } |
380 | |
381 | return timeout; |
382 | } |
383 | |
384 | |
385 | void |
386 | addinitgroups (struct database_dyn *db, int fd, request_header *req, void *key, |
387 | uid_t uid) |
388 | { |
389 | addinitgroupsX (db, fd, req, key, uid, NULL, NULL); |
390 | } |
391 | |
392 | |
393 | time_t |
394 | readdinitgroups (struct database_dyn *db, struct hashentry *he, |
395 | struct datahead *dh) |
396 | { |
397 | request_header req = |
398 | { |
399 | .type = INITGROUPS, |
400 | .key_len = he->len |
401 | }; |
402 | |
403 | return addinitgroupsX (db, fd: -1, req: &req, key: db->data + he->key, uid: he->owner, he, dh); |
404 | } |
405 | |