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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* AFS security handling
3 *
4 * Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/init.h>
9#include <linux/slab.h>
10#include <linux/fs.h>
11#include <linux/ctype.h>
12#include <linux/sched.h>
13#include <linux/hashtable.h>
14#include <keys/rxrpc-type.h>
15#include "internal.h"
16
17static DEFINE_HASHTABLE(afs_permits_cache, 10);
18static DEFINE_SPINLOCK(afs_permits_lock);
19
20/*
21 * get a key
22 */
23struct key *afs_request_key(struct afs_cell *cell)
24{
25 struct key *key;
26
27 _enter("{%x}", key_serial(cell->anonymous_key));
28
29 _debug("key %s", cell->anonymous_key->description);
30 key = request_key_net(&key_type_rxrpc, cell->anonymous_key->description,
31 cell->net->net, NULL);
32 if (IS_ERR(key)) {
33 if (PTR_ERR(key) != -ENOKEY) {
34 _leave(" = %ld", PTR_ERR(key));
35 return key;
36 }
37
38 /* act as anonymous user */
39 _leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
40 return key_get(cell->anonymous_key);
41 } else {
42 /* act as authorised user */
43 _leave(" = {%x} [auth]", key_serial(key));
44 return key;
45 }
46}
47
48/*
49 * Get a key when pathwalk is in rcuwalk mode.
50 */
51struct key *afs_request_key_rcu(struct afs_cell *cell)
52{
53 struct key *key;
54
55 _enter("{%x}", key_serial(cell->anonymous_key));
56
57 _debug("key %s", cell->anonymous_key->description);
58 key = request_key_net_rcu(&key_type_rxrpc,
59 cell->anonymous_key->description,
60 cell->net->net);
61 if (IS_ERR(key)) {
62 if (PTR_ERR(key) != -ENOKEY) {
63 _leave(" = %ld", PTR_ERR(key));
64 return key;
65 }
66
67 /* act as anonymous user */
68 _leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
69 return key_get(cell->anonymous_key);
70 } else {
71 /* act as authorised user */
72 _leave(" = {%x} [auth]", key_serial(key));
73 return key;
74 }
75}
76
77/*
78 * Dispose of a list of permits.
79 */
80static void afs_permits_rcu(struct rcu_head *rcu)
81{
82 struct afs_permits *permits =
83 container_of(rcu, struct afs_permits, rcu);
84 int i;
85
86 for (i = 0; i < permits->nr_permits; i++)
87 key_put(permits->permits[i].key);
88 kfree(permits);
89}
90
91/*
92 * Discard a permission cache.
93 */
94void afs_put_permits(struct afs_permits *permits)
95{
96 if (permits && refcount_dec_and_test(&permits->usage)) {
97 spin_lock(&afs_permits_lock);
98 hash_del_rcu(&permits->hash_node);
99 spin_unlock(&afs_permits_lock);
100 call_rcu(&permits->rcu, afs_permits_rcu);
101 }
102}
103
104/*
105 * Clear a permit cache on callback break.
106 */
107void afs_clear_permits(struct afs_vnode *vnode)
108{
109 struct afs_permits *permits;
110
111 spin_lock(&vnode->lock);
112 permits = rcu_dereference_protected(vnode->permit_cache,
113 lockdep_is_held(&vnode->lock));
114 RCU_INIT_POINTER(vnode->permit_cache, NULL);
115 spin_unlock(&vnode->lock);
116
117 afs_put_permits(permits);
118}
119
120/*
121 * Hash a list of permits. Use simple addition to make it easy to add an extra
122 * one at an as-yet indeterminate position in the list.
123 */
124static void afs_hash_permits(struct afs_permits *permits)
125{
126 unsigned long h = permits->nr_permits;
127 int i;
128
129 for (i = 0; i < permits->nr_permits; i++) {
130 h += (unsigned long)permits->permits[i].key / sizeof(void *);
131 h += permits->permits[i].access;
132 }
133
134 permits->h = h;
135}
136
137/*
138 * Cache the CallerAccess result obtained from doing a fileserver operation
139 * that returned a vnode status for a particular key. If a callback break
140 * occurs whilst the operation was in progress then we have to ditch the cache
141 * as the ACL *may* have changed.
142 */
143void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
144 unsigned int cb_break, struct afs_status_cb *scb)
145{
146 struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
147 afs_access_t caller_access = scb->status.caller_access;
148 size_t size = 0;
149 bool changed = false;
150 int i, j;
151
152 _enter("{%llx:%llu},%x,%x",
153 vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
154
155 rcu_read_lock();
156
157 /* Check for the common case first: We got back the same access as last
158 * time we tried and already have it recorded.
159 */
160 permits = rcu_dereference(vnode->permit_cache);
161 if (permits) {
162 if (!permits->invalidated) {
163 for (i = 0; i < permits->nr_permits; i++) {
164 if (permits->permits[i].key < key)
165 continue;
166 if (permits->permits[i].key > key)
167 break;
168 if (permits->permits[i].access != caller_access) {
169 changed = true;
170 break;
171 }
172
173 if (afs_cb_is_broken(cb_break, vnode)) {
174 changed = true;
175 break;
176 }
177
178 /* The cache is still good. */
179 rcu_read_unlock();
180 return;
181 }
182 }
183
184 changed |= permits->invalidated;
185 size = permits->nr_permits;
186
187 /* If this set of permits is now wrong, clear the permits
188 * pointer so that no one tries to use the stale information.
189 */
190 if (changed) {
191 spin_lock(&vnode->lock);
192 if (permits != rcu_access_pointer(vnode->permit_cache))
193 goto someone_else_changed_it_unlock;
194 RCU_INIT_POINTER(vnode->permit_cache, NULL);
195 spin_unlock(&vnode->lock);
196
197 afs_put_permits(permits);
198 permits = NULL;
199 size = 0;
200 }
201 }
202
203 if (afs_cb_is_broken(cb_break, vnode))
204 goto someone_else_changed_it;
205
206 /* We need a ref on any permits list we want to copy as we'll have to
207 * drop the lock to do memory allocation.
208 */
209 if (permits && !refcount_inc_not_zero(&permits->usage))
210 goto someone_else_changed_it;
211
212 rcu_read_unlock();
213
214 /* Speculatively create a new list with the revised permission set. We
215 * discard this if we find an extant match already in the hash, but
216 * it's easier to compare with memcmp this way.
217 *
218 * We fill in the key pointers at this time, but we don't get the refs
219 * yet.
220 */
221 size++;
222 new = kzalloc(struct_size(new, permits, size), GFP_NOFS);
223 if (!new)
224 goto out_put;
225
226 refcount_set(&new->usage, 1);
227 new->nr_permits = size;
228 i = j = 0;
229 if (permits) {
230 for (i = 0; i < permits->nr_permits; i++) {
231 if (j == i && permits->permits[i].key > key) {
232 new->permits[j].key = key;
233 new->permits[j].access = caller_access;
234 j++;
235 }
236 new->permits[j].key = permits->permits[i].key;
237 new->permits[j].access = permits->permits[i].access;
238 j++;
239 }
240 }
241
242 if (j == i) {
243 new->permits[j].key = key;
244 new->permits[j].access = caller_access;
245 }
246
247 afs_hash_permits(new);
248
249 /* Now see if the permit list we want is actually already available */
250 spin_lock(&afs_permits_lock);
251
252 hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
253 if (xpermits->h != new->h ||
254 xpermits->invalidated ||
255 xpermits->nr_permits != new->nr_permits ||
256 memcmp(xpermits->permits, new->permits,
257 new->nr_permits * sizeof(struct afs_permit)) != 0)
258 continue;
259
260 if (refcount_inc_not_zero(&xpermits->usage)) {
261 replacement = xpermits;
262 goto found;
263 }
264
265 break;
266 }
267
268 for (i = 0; i < new->nr_permits; i++)
269 key_get(new->permits[i].key);
270 hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
271 replacement = new;
272 new = NULL;
273
274found:
275 spin_unlock(&afs_permits_lock);
276
277 kfree(new);
278
279 rcu_read_lock();
280 spin_lock(&vnode->lock);
281 zap = rcu_access_pointer(vnode->permit_cache);
282 if (!afs_cb_is_broken(cb_break, vnode) && zap == permits)
283 rcu_assign_pointer(vnode->permit_cache, replacement);
284 else
285 zap = replacement;
286 spin_unlock(&vnode->lock);
287 rcu_read_unlock();
288 afs_put_permits(zap);
289out_put:
290 afs_put_permits(permits);
291 return;
292
293someone_else_changed_it_unlock:
294 spin_unlock(&vnode->lock);
295someone_else_changed_it:
296 /* Someone else changed the cache under us - don't recheck at this
297 * time.
298 */
299 rcu_read_unlock();
300 return;
301}
302
303static bool afs_check_permit_rcu(struct afs_vnode *vnode, struct key *key,
304 afs_access_t *_access)
305{
306 const struct afs_permits *permits;
307 int i;
308
309 _enter("{%llx:%llu},%x",
310 vnode->fid.vid, vnode->fid.vnode, key_serial(key));
311
312 /* check the permits to see if we've got one yet */
313 if (key == vnode->volume->cell->anonymous_key) {
314 *_access = vnode->status.anon_access;
315 _leave(" = t [anon %x]", *_access);
316 return true;
317 }
318
319 permits = rcu_dereference(vnode->permit_cache);
320 if (permits) {
321 for (i = 0; i < permits->nr_permits; i++) {
322 if (permits->permits[i].key < key)
323 continue;
324 if (permits->permits[i].key > key)
325 break;
326
327 *_access = permits->permits[i].access;
328 _leave(" = %u [perm %x]", !permits->invalidated, *_access);
329 return !permits->invalidated;
330 }
331 }
332
333 _leave(" = f");
334 return false;
335}
336
337/*
338 * check with the fileserver to see if the directory or parent directory is
339 * permitted to be accessed with this authorisation, and if so, what access it
340 * is granted
341 */
342int afs_check_permit(struct afs_vnode *vnode, struct key *key,
343 afs_access_t *_access)
344{
345 struct afs_permits *permits;
346 bool valid = false;
347 int i, ret;
348
349 _enter("{%llx:%llu},%x",
350 vnode->fid.vid, vnode->fid.vnode, key_serial(key));
351
352 /* check the permits to see if we've got one yet */
353 if (key == vnode->volume->cell->anonymous_key) {
354 _debug("anon");
355 *_access = vnode->status.anon_access;
356 valid = true;
357 } else {
358 rcu_read_lock();
359 permits = rcu_dereference(vnode->permit_cache);
360 if (permits) {
361 for (i = 0; i < permits->nr_permits; i++) {
362 if (permits->permits[i].key < key)
363 continue;
364 if (permits->permits[i].key > key)
365 break;
366
367 *_access = permits->permits[i].access;
368 valid = !permits->invalidated;
369 break;
370 }
371 }
372 rcu_read_unlock();
373 }
374
375 if (!valid) {
376 /* Check the status on the file we're actually interested in
377 * (the post-processing will cache the result).
378 */
379 _debug("no valid permit");
380
381 ret = afs_fetch_status(vnode, key, false, _access);
382 if (ret < 0) {
383 *_access = 0;
384 _leave(" = %d", ret);
385 return ret;
386 }
387 }
388
389 _leave(" = 0 [access %x]", *_access);
390 return 0;
391}
392
393/*
394 * check the permissions on an AFS file
395 * - AFS ACLs are attached to directories only, and a file is controlled by its
396 * parent directory's ACL
397 */
398int afs_permission(struct user_namespace *mnt_userns, struct inode *inode,
399 int mask)
400{
401 struct afs_vnode *vnode = AFS_FS_I(inode);
402 afs_access_t access;
403 struct key *key;
404 int ret = 0;
405
406 _enter("{{%llx:%llu},%lx},%x,",
407 vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
408
409 if (mask & MAY_NOT_BLOCK) {
410 key = afs_request_key_rcu(vnode->volume->cell);
411 if (IS_ERR(key))
412 return -ECHILD;
413
414 ret = -ECHILD;
415 if (!afs_check_validity(vnode) ||
416 !afs_check_permit_rcu(vnode, key, &access))
417 goto error;
418 } else {
419 key = afs_request_key(vnode->volume->cell);
420 if (IS_ERR(key)) {
421 _leave(" = %ld [key]", PTR_ERR(key));
422 return PTR_ERR(key);
423 }
424
425 ret = afs_validate(vnode, key);
426 if (ret < 0)
427 goto error;
428
429 /* check the permits to see if we've got one yet */
430 ret = afs_check_permit(vnode, key, &access);
431 if (ret < 0)
432 goto error;
433 }
434
435 /* interpret the access mask */
436 _debug("REQ %x ACC %x on %s",
437 mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
438
439 ret = 0;
440 if (S_ISDIR(inode->i_mode)) {
441 if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) {
442 if (!(access & AFS_ACE_LOOKUP))
443 goto permission_denied;
444 }
445 if (mask & MAY_WRITE) {
446 if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
447 AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
448 goto permission_denied;
449 }
450 } else {
451 if (!(access & AFS_ACE_LOOKUP))
452 goto permission_denied;
453 if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
454 goto permission_denied;
455 if (mask & (MAY_EXEC | MAY_READ)) {
456 if (!(access & AFS_ACE_READ))
457 goto permission_denied;
458 if (!(inode->i_mode & S_IRUSR))
459 goto permission_denied;
460 } else if (mask & MAY_WRITE) {
461 if (!(access & AFS_ACE_WRITE))
462 goto permission_denied;
463 if (!(inode->i_mode & S_IWUSR))
464 goto permission_denied;
465 }
466 }
467
468 key_put(key);
469 _leave(" = %d", ret);
470 return ret;
471
472permission_denied:
473 ret = -EACCES;
474error:
475 key_put(key);
476 _leave(" = %d", ret);
477 return ret;
478}
479
480void __exit afs_clean_up_permit_cache(void)
481{
482 int i;
483
484 for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
485 WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
486
487}
1/* AFS security handling
2 *
3 * Copyright (C) 2007, 2017 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/init.h>
13#include <linux/slab.h>
14#include <linux/fs.h>
15#include <linux/ctype.h>
16#include <linux/sched.h>
17#include <linux/hashtable.h>
18#include <keys/rxrpc-type.h>
19#include "internal.h"
20
21static DEFINE_HASHTABLE(afs_permits_cache, 10);
22static DEFINE_SPINLOCK(afs_permits_lock);
23
24/*
25 * get a key
26 */
27struct key *afs_request_key(struct afs_cell *cell)
28{
29 struct key *key;
30
31 _enter("{%x}", key_serial(cell->anonymous_key));
32
33 _debug("key %s", cell->anonymous_key->description);
34 key = request_key(&key_type_rxrpc, cell->anonymous_key->description,
35 NULL);
36 if (IS_ERR(key)) {
37 if (PTR_ERR(key) != -ENOKEY) {
38 _leave(" = %ld", PTR_ERR(key));
39 return key;
40 }
41
42 /* act as anonymous user */
43 _leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
44 return key_get(cell->anonymous_key);
45 } else {
46 /* act as authorised user */
47 _leave(" = {%x} [auth]", key_serial(key));
48 return key;
49 }
50}
51
52/*
53 * Dispose of a list of permits.
54 */
55static void afs_permits_rcu(struct rcu_head *rcu)
56{
57 struct afs_permits *permits =
58 container_of(rcu, struct afs_permits, rcu);
59 int i;
60
61 for (i = 0; i < permits->nr_permits; i++)
62 key_put(permits->permits[i].key);
63 kfree(permits);
64}
65
66/*
67 * Discard a permission cache.
68 */
69void afs_put_permits(struct afs_permits *permits)
70{
71 if (permits && refcount_dec_and_test(&permits->usage)) {
72 spin_lock(&afs_permits_lock);
73 hash_del_rcu(&permits->hash_node);
74 spin_unlock(&afs_permits_lock);
75 call_rcu(&permits->rcu, afs_permits_rcu);
76 }
77}
78
79/*
80 * Clear a permit cache on callback break.
81 */
82void afs_clear_permits(struct afs_vnode *vnode)
83{
84 struct afs_permits *permits;
85
86 spin_lock(&vnode->lock);
87 permits = rcu_dereference_protected(vnode->permit_cache,
88 lockdep_is_held(&vnode->lock));
89 RCU_INIT_POINTER(vnode->permit_cache, NULL);
90 vnode->cb_break++;
91 spin_unlock(&vnode->lock);
92
93 if (permits)
94 afs_put_permits(permits);
95}
96
97/*
98 * Hash a list of permits. Use simple addition to make it easy to add an extra
99 * one at an as-yet indeterminate position in the list.
100 */
101static void afs_hash_permits(struct afs_permits *permits)
102{
103 unsigned long h = permits->nr_permits;
104 int i;
105
106 for (i = 0; i < permits->nr_permits; i++) {
107 h += (unsigned long)permits->permits[i].key / sizeof(void *);
108 h += permits->permits[i].access;
109 }
110
111 permits->h = h;
112}
113
114/*
115 * Cache the CallerAccess result obtained from doing a fileserver operation
116 * that returned a vnode status for a particular key. If a callback break
117 * occurs whilst the operation was in progress then we have to ditch the cache
118 * as the ACL *may* have changed.
119 */
120void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
121 unsigned int cb_break)
122{
123 struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
124 afs_access_t caller_access = READ_ONCE(vnode->status.caller_access);
125 size_t size = 0;
126 bool changed = false;
127 int i, j;
128
129 _enter("{%x:%u},%x,%x",
130 vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
131
132 rcu_read_lock();
133
134 /* Check for the common case first: We got back the same access as last
135 * time we tried and already have it recorded.
136 */
137 permits = rcu_dereference(vnode->permit_cache);
138 if (permits) {
139 if (!permits->invalidated) {
140 for (i = 0; i < permits->nr_permits; i++) {
141 if (permits->permits[i].key < key)
142 continue;
143 if (permits->permits[i].key > key)
144 break;
145 if (permits->permits[i].access != caller_access) {
146 changed = true;
147 break;
148 }
149
150 if (cb_break != afs_cb_break_sum(vnode, vnode->cb_interest)) {
151 changed = true;
152 break;
153 }
154
155 /* The cache is still good. */
156 rcu_read_unlock();
157 return;
158 }
159 }
160
161 changed |= permits->invalidated;
162 size = permits->nr_permits;
163
164 /* If this set of permits is now wrong, clear the permits
165 * pointer so that no one tries to use the stale information.
166 */
167 if (changed) {
168 spin_lock(&vnode->lock);
169 if (permits != rcu_access_pointer(vnode->permit_cache))
170 goto someone_else_changed_it_unlock;
171 RCU_INIT_POINTER(vnode->permit_cache, NULL);
172 spin_unlock(&vnode->lock);
173
174 afs_put_permits(permits);
175 permits = NULL;
176 size = 0;
177 }
178 }
179
180 if (cb_break != afs_cb_break_sum(vnode, vnode->cb_interest))
181 goto someone_else_changed_it;
182
183 /* We need a ref on any permits list we want to copy as we'll have to
184 * drop the lock to do memory allocation.
185 */
186 if (permits && !refcount_inc_not_zero(&permits->usage))
187 goto someone_else_changed_it;
188
189 rcu_read_unlock();
190
191 /* Speculatively create a new list with the revised permission set. We
192 * discard this if we find an extant match already in the hash, but
193 * it's easier to compare with memcmp this way.
194 *
195 * We fill in the key pointers at this time, but we don't get the refs
196 * yet.
197 */
198 size++;
199 new = kzalloc(sizeof(struct afs_permits) +
200 sizeof(struct afs_permit) * size, GFP_NOFS);
201 if (!new)
202 goto out_put;
203
204 refcount_set(&new->usage, 1);
205 new->nr_permits = size;
206 i = j = 0;
207 if (permits) {
208 for (i = 0; i < permits->nr_permits; i++) {
209 if (j == i && permits->permits[i].key > key) {
210 new->permits[j].key = key;
211 new->permits[j].access = caller_access;
212 j++;
213 }
214 new->permits[j].key = permits->permits[i].key;
215 new->permits[j].access = permits->permits[i].access;
216 j++;
217 }
218 }
219
220 if (j == i) {
221 new->permits[j].key = key;
222 new->permits[j].access = caller_access;
223 }
224
225 afs_hash_permits(new);
226
227 /* Now see if the permit list we want is actually already available */
228 spin_lock(&afs_permits_lock);
229
230 hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
231 if (xpermits->h != new->h ||
232 xpermits->invalidated ||
233 xpermits->nr_permits != new->nr_permits ||
234 memcmp(xpermits->permits, new->permits,
235 new->nr_permits * sizeof(struct afs_permit)) != 0)
236 continue;
237
238 if (refcount_inc_not_zero(&xpermits->usage)) {
239 replacement = xpermits;
240 goto found;
241 }
242
243 break;
244 }
245
246 for (i = 0; i < new->nr_permits; i++)
247 key_get(new->permits[i].key);
248 hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
249 replacement = new;
250 new = NULL;
251
252found:
253 spin_unlock(&afs_permits_lock);
254
255 kfree(new);
256
257 spin_lock(&vnode->lock);
258 zap = rcu_access_pointer(vnode->permit_cache);
259 if (cb_break == afs_cb_break_sum(vnode, vnode->cb_interest) &&
260 zap == permits)
261 rcu_assign_pointer(vnode->permit_cache, replacement);
262 else
263 zap = replacement;
264 spin_unlock(&vnode->lock);
265 afs_put_permits(zap);
266out_put:
267 afs_put_permits(permits);
268 return;
269
270someone_else_changed_it_unlock:
271 spin_unlock(&vnode->lock);
272someone_else_changed_it:
273 /* Someone else changed the cache under us - don't recheck at this
274 * time.
275 */
276 rcu_read_unlock();
277 return;
278}
279
280/*
281 * check with the fileserver to see if the directory or parent directory is
282 * permitted to be accessed with this authorisation, and if so, what access it
283 * is granted
284 */
285int afs_check_permit(struct afs_vnode *vnode, struct key *key,
286 afs_access_t *_access)
287{
288 struct afs_permits *permits;
289 bool valid = false;
290 int i, ret;
291
292 _enter("{%x:%u},%x",
293 vnode->fid.vid, vnode->fid.vnode, key_serial(key));
294
295 /* check the permits to see if we've got one yet */
296 if (key == vnode->volume->cell->anonymous_key) {
297 _debug("anon");
298 *_access = vnode->status.anon_access;
299 valid = true;
300 } else {
301 rcu_read_lock();
302 permits = rcu_dereference(vnode->permit_cache);
303 if (permits) {
304 for (i = 0; i < permits->nr_permits; i++) {
305 if (permits->permits[i].key < key)
306 continue;
307 if (permits->permits[i].key > key)
308 break;
309
310 *_access = permits->permits[i].access;
311 valid = !permits->invalidated;
312 break;
313 }
314 }
315 rcu_read_unlock();
316 }
317
318 if (!valid) {
319 /* Check the status on the file we're actually interested in
320 * (the post-processing will cache the result).
321 */
322 _debug("no valid permit");
323
324 ret = afs_fetch_status(vnode, key, false);
325 if (ret < 0) {
326 *_access = 0;
327 _leave(" = %d", ret);
328 return ret;
329 }
330 *_access = vnode->status.caller_access;
331 }
332
333 _leave(" = 0 [access %x]", *_access);
334 return 0;
335}
336
337/*
338 * check the permissions on an AFS file
339 * - AFS ACLs are attached to directories only, and a file is controlled by its
340 * parent directory's ACL
341 */
342int afs_permission(struct inode *inode, int mask)
343{
344 struct afs_vnode *vnode = AFS_FS_I(inode);
345 afs_access_t uninitialized_var(access);
346 struct key *key;
347 int ret;
348
349 if (mask & MAY_NOT_BLOCK)
350 return -ECHILD;
351
352 _enter("{{%x:%u},%lx},%x,",
353 vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
354
355 key = afs_request_key(vnode->volume->cell);
356 if (IS_ERR(key)) {
357 _leave(" = %ld [key]", PTR_ERR(key));
358 return PTR_ERR(key);
359 }
360
361 ret = afs_validate(vnode, key);
362 if (ret < 0)
363 goto error;
364
365 /* check the permits to see if we've got one yet */
366 ret = afs_check_permit(vnode, key, &access);
367 if (ret < 0)
368 goto error;
369
370 /* interpret the access mask */
371 _debug("REQ %x ACC %x on %s",
372 mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
373
374 if (S_ISDIR(inode->i_mode)) {
375 if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) {
376 if (!(access & AFS_ACE_LOOKUP))
377 goto permission_denied;
378 }
379 if (mask & MAY_WRITE) {
380 if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
381 AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
382 goto permission_denied;
383 }
384 } else {
385 if (!(access & AFS_ACE_LOOKUP))
386 goto permission_denied;
387 if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
388 goto permission_denied;
389 if (mask & (MAY_EXEC | MAY_READ)) {
390 if (!(access & AFS_ACE_READ))
391 goto permission_denied;
392 if (!(inode->i_mode & S_IRUSR))
393 goto permission_denied;
394 } else if (mask & MAY_WRITE) {
395 if (!(access & AFS_ACE_WRITE))
396 goto permission_denied;
397 if (!(inode->i_mode & S_IWUSR))
398 goto permission_denied;
399 }
400 }
401
402 key_put(key);
403 _leave(" = %d", ret);
404 return ret;
405
406permission_denied:
407 ret = -EACCES;
408error:
409 key_put(key);
410 _leave(" = %d", ret);
411 return ret;
412}
413
414void __exit afs_clean_up_permit_cache(void)
415{
416 int i;
417
418 for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
419 WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
420
421}