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 */
afs_cell_alloc(const char * name,unsigned namelen,char * vllist)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 */
afs_cell_create(const char * name,unsigned namesz,char * vllist,bool retref)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);
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 */
afs_cell_init(char * rootcell)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 */
afs_cell_lookup(const char * name,unsigned namesz,bool dns_cell)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 */
afs_put_cell(struct afs_cell * cell)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 */
afs_cell_destroy(struct afs_cell * cell)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 */
afs_cell_purge(void)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 }
461