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1 | /* AFS cell and server record management | |
2 | * | |
3 | * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/key.h> | |
15 | #include <linux/ctype.h> | |
16 | #include <linux/dns_resolver.h> | |
17 | #include <linux/sched.h> | |
18 | #include <keys/rxrpc-type.h> | |
19 | #include "internal.h" | |
20 | ||
21 | DECLARE_RWSEM(afs_proc_cells_sem); | |
22 | LIST_HEAD(afs_proc_cells); | |
23 | ||
24 | static LIST_HEAD(afs_cells); | |
25 | static DEFINE_RWLOCK(afs_cells_lock); | |
26 | static DECLARE_RWSEM(afs_cells_sem); /* add/remove serialisation */ | |
27 | static DECLARE_WAIT_QUEUE_HEAD(afs_cells_freeable_wq); | |
28 | static struct afs_cell *afs_cell_root; | |
29 | ||
30 | /* | |
31 | * allocate a cell record and fill in its name, VL server address list and | |
32 | * allocate an anonymous key | |
33 | */ | |
34 | static struct afs_cell *afs_cell_alloc(const char *name, unsigned namelen, | |
35 | char *vllist) | |
36 | { | |
37 | struct afs_cell *cell; | |
38 | struct key *key; | |
39 | char keyname[4 + AFS_MAXCELLNAME + 1], *cp, *dp, *next; | |
40 | char *dvllist = NULL, *_vllist = NULL; | |
41 | char delimiter = ':'; | |
42 | int ret; | |
43 | ||
44 | _enter("%*.*s,%s", namelen, namelen, name ?: "", vllist); | |
45 | ||
46 | BUG_ON(!name); /* TODO: want to look up "this cell" in the cache */ | |
47 | ||
48 | if (namelen > AFS_MAXCELLNAME) { | |
49 | _leave(" = -ENAMETOOLONG"); | |
50 | return ERR_PTR(-ENAMETOOLONG); | |
51 | } | |
52 | ||
53 | /* allocate and initialise a cell record */ | |
54 | cell = kzalloc(sizeof(struct afs_cell) + namelen + 1, GFP_KERNEL); | |
55 | if (!cell) { | |
56 | _leave(" = -ENOMEM"); | |
57 | return ERR_PTR(-ENOMEM); | |
58 | } | |
59 | ||
60 | memcpy(cell->name, name, namelen); | |
61 | cell->name[namelen] = 0; | |
62 | ||
63 | atomic_set(&cell->usage, 1); | |
64 | INIT_LIST_HEAD(&cell->link); | |
65 | rwlock_init(&cell->servers_lock); | |
66 | INIT_LIST_HEAD(&cell->servers); | |
67 | init_rwsem(&cell->vl_sem); | |
68 | INIT_LIST_HEAD(&cell->vl_list); | |
69 | spin_lock_init(&cell->vl_lock); | |
70 | ||
71 | /* if the ip address is invalid, try dns query */ | |
72 | if (!vllist || strlen(vllist) < 7) { | |
73 | ret = dns_query("afsdb", name, namelen, "ipv4", &dvllist, NULL); | |
74 | if (ret < 0) { | |
75 | if (ret == -ENODATA || ret == -EAGAIN || ret == -ENOKEY) | |
76 | /* translate these errors into something | |
77 | * userspace might understand */ | |
78 | ret = -EDESTADDRREQ; | |
79 | _leave(" = %d", ret); | |
80 | return ERR_PTR(ret); | |
81 | } | |
82 | _vllist = dvllist; | |
83 | ||
84 | /* change the delimiter for user-space reply */ | |
85 | delimiter = ','; | |
86 | ||
87 | } else { | |
88 | _vllist = vllist; | |
89 | } | |
90 | ||
91 | /* fill in the VL server list from the rest of the string */ | |
92 | do { | |
93 | unsigned a, b, c, d; | |
94 | ||
95 | next = strchr(_vllist, delimiter); | |
96 | if (next) | |
97 | *next++ = 0; | |
98 | ||
99 | if (sscanf(_vllist, "%u.%u.%u.%u", &a, &b, &c, &d) != 4) | |
100 | goto bad_address; | |
101 | ||
102 | if (a > 255 || b > 255 || c > 255 || d > 255) | |
103 | goto bad_address; | |
104 | ||
105 | cell->vl_addrs[cell->vl_naddrs++].s_addr = | |
106 | htonl((a << 24) | (b << 16) | (c << 8) | d); | |
107 | ||
108 | } while (cell->vl_naddrs < AFS_CELL_MAX_ADDRS && (_vllist = next)); | |
109 | ||
110 | /* create a key to represent an anonymous user */ | |
111 | memcpy(keyname, "afs@", 4); | |
112 | dp = keyname + 4; | |
113 | cp = cell->name; | |
114 | do { | |
115 | *dp++ = toupper(*cp); | |
116 | } while (*cp++); | |
117 | ||
118 | key = rxrpc_get_null_key(keyname); | |
119 | if (IS_ERR(key)) { | |
120 | _debug("no key"); | |
121 | ret = PTR_ERR(key); | |
122 | goto error; | |
123 | } | |
124 | cell->anonymous_key = key; | |
125 | ||
126 | _debug("anon key %p{%x}", | |
127 | cell->anonymous_key, key_serial(cell->anonymous_key)); | |
128 | ||
129 | _leave(" = %p", cell); | |
130 | return cell; | |
131 | ||
132 | bad_address: | |
133 | printk(KERN_ERR "kAFS: bad VL server IP address\n"); | |
134 | ret = -EINVAL; | |
135 | error: | |
136 | key_put(cell->anonymous_key); | |
137 | kfree(dvllist); | |
138 | kfree(cell); | |
139 | _leave(" = %d", ret); | |
140 | return ERR_PTR(ret); | |
141 | } | |
142 | ||
143 | /* | |
144 | * afs_cell_crate() - create a cell record | |
145 | * @name: is the name of the cell. | |
146 | * @namsesz: is the strlen of the cell name. | |
147 | * @vllist: is a colon separated list of IP addresses in "a.b.c.d" format. | |
148 | * @retref: is T to return the cell reference when the cell exists. | |
149 | */ | |
150 | struct afs_cell *afs_cell_create(const char *name, unsigned namesz, | |
151 | char *vllist, bool retref) | |
152 | { | |
153 | struct afs_cell *cell; | |
154 | int ret; | |
155 | ||
156 | _enter("%*.*s,%s", namesz, namesz, name ?: "", vllist); | |
157 | ||
158 | down_write(&afs_cells_sem); | |
159 | read_lock(&afs_cells_lock); | |
160 | list_for_each_entry(cell, &afs_cells, link) { | |
161 | if (strncasecmp(cell->name, name, namesz) == 0) | |
162 | goto duplicate_name; | |
163 | } | |
164 | read_unlock(&afs_cells_lock); | |
165 | ||
166 | cell = afs_cell_alloc(name, namesz, vllist); | |
167 | if (IS_ERR(cell)) { | |
168 | _leave(" = %ld", PTR_ERR(cell)); | |
169 | up_write(&afs_cells_sem); | |
170 | return cell; | |
171 | } | |
172 | ||
173 | /* add a proc directory for this cell */ | |
174 | ret = afs_proc_cell_setup(cell); | |
175 | if (ret < 0) | |
176 | goto error; | |
177 | ||
178 | #ifdef CONFIG_AFS_FSCACHE | |
179 | /* put it up for caching (this never returns an error) */ | |
180 | cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index, | |
181 | &afs_cell_cache_index_def, | |
182 | cell, true); | |
183 | #endif | |
184 | ||
185 | /* add to the cell lists */ | |
186 | write_lock(&afs_cells_lock); | |
187 | list_add_tail(&cell->link, &afs_cells); | |
188 | write_unlock(&afs_cells_lock); | |
189 | ||
190 | down_write(&afs_proc_cells_sem); | |
191 | list_add_tail(&cell->proc_link, &afs_proc_cells); | |
192 | up_write(&afs_proc_cells_sem); | |
193 | up_write(&afs_cells_sem); | |
194 | ||
195 | _leave(" = %p", cell); | |
196 | return cell; | |
197 | ||
198 | error: | |
199 | up_write(&afs_cells_sem); | |
200 | key_put(cell->anonymous_key); | |
201 | kfree(cell); | |
202 | _leave(" = %d", ret); | |
203 | return ERR_PTR(ret); | |
204 | ||
205 | duplicate_name: | |
206 | if (retref && !IS_ERR(cell)) | |
207 | afs_get_cell(cell); | |
208 | ||
209 | read_unlock(&afs_cells_lock); | |
210 | up_write(&afs_cells_sem); | |
211 | ||
212 | if (retref) { | |
213 | _leave(" = %p", cell); | |
214 | return cell; | |
215 | } | |
216 | ||
217 | _leave(" = -EEXIST"); | |
218 | return ERR_PTR(-EEXIST); | |
219 | } | |
220 | ||
221 | /* | |
222 | * set the root cell information | |
223 | * - can be called with a module parameter string | |
224 | * - can be called from a write to /proc/fs/afs/rootcell | |
225 | */ | |
226 | int afs_cell_init(char *rootcell) | |
227 | { | |
228 | struct afs_cell *old_root, *new_root; | |
229 | char *cp; | |
230 | ||
231 | _enter(""); | |
232 | ||
233 | if (!rootcell) { | |
234 | /* module is loaded with no parameters, or built statically. | |
235 | * - in the future we might initialize cell DB here. | |
236 | */ | |
237 | _leave(" = 0 [no root]"); | |
238 | return 0; | |
239 | } | |
240 | ||
241 | cp = strchr(rootcell, ':'); | |
242 | if (!cp) | |
243 | _debug("kAFS: no VL server IP addresses specified"); | |
244 | else | |
245 | *cp++ = 0; | |
246 | ||
247 | /* allocate a cell record for the root cell */ | |
248 | new_root = afs_cell_create(rootcell, strlen(rootcell), cp, false); | |
249 | if (IS_ERR(new_root)) { | |
250 | _leave(" = %ld", PTR_ERR(new_root)); | |
251 | return PTR_ERR(new_root); | |
252 | } | |
253 | ||
254 | /* install the new cell */ | |
255 | write_lock(&afs_cells_lock); | |
256 | old_root = afs_cell_root; | |
257 | afs_cell_root = new_root; | |
258 | write_unlock(&afs_cells_lock); | |
259 | afs_put_cell(old_root); | |
260 | ||
261 | _leave(" = 0"); | |
262 | return 0; | |
263 | } | |
264 | ||
265 | /* | |
266 | * lookup a cell record | |
267 | */ | |
268 | struct afs_cell *afs_cell_lookup(const char *name, unsigned namesz, | |
269 | bool dns_cell) | |
270 | { | |
271 | struct afs_cell *cell; | |
272 | ||
273 | _enter("\"%*.*s\",", namesz, namesz, name ?: ""); | |
274 | ||
275 | down_read(&afs_cells_sem); | |
276 | read_lock(&afs_cells_lock); | |
277 | ||
278 | if (name) { | |
279 | /* if the cell was named, look for it in the cell record list */ | |
280 | list_for_each_entry(cell, &afs_cells, link) { | |
281 | if (strncmp(cell->name, name, namesz) == 0) { | |
282 | afs_get_cell(cell); | |
283 | goto found; | |
284 | } | |
285 | } | |
286 | cell = ERR_PTR(-ENOENT); | |
287 | if (dns_cell) | |
288 | goto create_cell; | |
289 | found: | |
290 | ; | |
291 | } else { | |
292 | cell = afs_cell_root; | |
293 | if (!cell) { | |
294 | /* this should not happen unless user tries to mount | |
295 | * when root cell is not set. Return an impossibly | |
296 | * bizarre errno to alert the user. Things like | |
297 | * ENOENT might be "more appropriate" but they happen | |
298 | * for other reasons. | |
299 | */ | |
300 | cell = ERR_PTR(-EDESTADDRREQ); | |
301 | } else { | |
302 | afs_get_cell(cell); | |
303 | } | |
304 | ||
305 | } | |
306 | ||
307 | read_unlock(&afs_cells_lock); | |
308 | up_read(&afs_cells_sem); | |
309 | _leave(" = %p", cell); | |
310 | return cell; | |
311 | ||
312 | create_cell: | |
313 | read_unlock(&afs_cells_lock); | |
314 | up_read(&afs_cells_sem); | |
315 | ||
316 | cell = afs_cell_create(name, namesz, NULL, true); | |
317 | ||
318 | _leave(" = %p", cell); | |
319 | return cell; | |
320 | } | |
321 | ||
322 | #if 0 | |
323 | /* | |
324 | * try and get a cell record | |
325 | */ | |
326 | struct afs_cell *afs_get_cell_maybe(struct afs_cell *cell) | |
327 | { | |
328 | write_lock(&afs_cells_lock); | |
329 | ||
330 | if (cell && !list_empty(&cell->link)) | |
331 | afs_get_cell(cell); | |
332 | else | |
333 | cell = NULL; | |
334 | ||
335 | write_unlock(&afs_cells_lock); | |
336 | return cell; | |
337 | } | |
338 | #endif /* 0 */ | |
339 | ||
340 | /* | |
341 | * destroy a cell record | |
342 | */ | |
343 | void afs_put_cell(struct afs_cell *cell) | |
344 | { | |
345 | if (!cell) | |
346 | return; | |
347 | ||
348 | _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name); | |
349 | ||
350 | ASSERTCMP(atomic_read(&cell->usage), >, 0); | |
351 | ||
352 | /* to prevent a race, the decrement and the dequeue must be effectively | |
353 | * atomic */ | |
354 | write_lock(&afs_cells_lock); | |
355 | ||
356 | if (likely(!atomic_dec_and_test(&cell->usage))) { | |
357 | write_unlock(&afs_cells_lock); | |
358 | _leave(""); | |
359 | return; | |
360 | } | |
361 | ||
362 | ASSERT(list_empty(&cell->servers)); | |
363 | ASSERT(list_empty(&cell->vl_list)); | |
364 | ||
365 | write_unlock(&afs_cells_lock); | |
366 | ||
367 | wake_up(&afs_cells_freeable_wq); | |
368 | ||
369 | _leave(" [unused]"); | |
370 | } | |
371 | ||
372 | /* | |
373 | * destroy a cell record | |
374 | * - must be called with the afs_cells_sem write-locked | |
375 | * - cell->link should have been broken by the caller | |
376 | */ | |
377 | static void afs_cell_destroy(struct afs_cell *cell) | |
378 | { | |
379 | _enter("%p{%d,%s}", cell, atomic_read(&cell->usage), cell->name); | |
380 | ||
381 | ASSERTCMP(atomic_read(&cell->usage), >=, 0); | |
382 | ASSERT(list_empty(&cell->link)); | |
383 | ||
384 | /* wait for everyone to stop using the cell */ | |
385 | if (atomic_read(&cell->usage) > 0) { | |
386 | DECLARE_WAITQUEUE(myself, current); | |
387 | ||
388 | _debug("wait for cell %s", cell->name); | |
389 | set_current_state(TASK_UNINTERRUPTIBLE); | |
390 | add_wait_queue(&afs_cells_freeable_wq, &myself); | |
391 | ||
392 | while (atomic_read(&cell->usage) > 0) { | |
393 | schedule(); | |
394 | set_current_state(TASK_UNINTERRUPTIBLE); | |
395 | } | |
396 | ||
397 | remove_wait_queue(&afs_cells_freeable_wq, &myself); | |
398 | set_current_state(TASK_RUNNING); | |
399 | } | |
400 | ||
401 | _debug("cell dead"); | |
402 | ASSERTCMP(atomic_read(&cell->usage), ==, 0); | |
403 | ASSERT(list_empty(&cell->servers)); | |
404 | ASSERT(list_empty(&cell->vl_list)); | |
405 | ||
406 | afs_proc_cell_remove(cell); | |
407 | ||
408 | down_write(&afs_proc_cells_sem); | |
409 | list_del_init(&cell->proc_link); | |
410 | up_write(&afs_proc_cells_sem); | |
411 | ||
412 | #ifdef CONFIG_AFS_FSCACHE | |
413 | fscache_relinquish_cookie(cell->cache, 0); | |
414 | #endif | |
415 | key_put(cell->anonymous_key); | |
416 | kfree(cell); | |
417 | ||
418 | _leave(" [destroyed]"); | |
419 | } | |
420 | ||
421 | /* | |
422 | * purge in-memory cell database on module unload or afs_init() failure | |
423 | * - the timeout daemon is stopped before calling this | |
424 | */ | |
425 | void afs_cell_purge(void) | |
426 | { | |
427 | struct afs_cell *cell; | |
428 | ||
429 | _enter(""); | |
430 | ||
431 | afs_put_cell(afs_cell_root); | |
432 | ||
433 | down_write(&afs_cells_sem); | |
434 | ||
435 | while (!list_empty(&afs_cells)) { | |
436 | cell = NULL; | |
437 | ||
438 | /* remove the next cell from the front of the list */ | |
439 | write_lock(&afs_cells_lock); | |
440 | ||
441 | if (!list_empty(&afs_cells)) { | |
442 | cell = list_entry(afs_cells.next, | |
443 | struct afs_cell, link); | |
444 | list_del_init(&cell->link); | |
445 | } | |
446 | ||
447 | write_unlock(&afs_cells_lock); | |
448 | ||
449 | if (cell) { | |
450 | _debug("PURGING CELL %s (%d)", | |
451 | cell->name, atomic_read(&cell->usage)); | |
452 | ||
453 | /* now the cell should be left with no references */ | |
454 | afs_cell_destroy(cell); | |
455 | } | |
456 | } | |
457 | ||
458 | up_write(&afs_cells_sem); | |
459 | _leave(""); | |
460 | } |