blob: 857f09d09ee9568ece06da8816c98764adcd1ce3 [file] [log] [blame]
David Howells00d3b7a2007-04-26 15:57:07 -07001/* AFS security handling
2 *
David Howellsbe080a62017-11-02 15:27:49 +00003 * Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
David Howells00d3b7a2007-04-26 15:57:07 -07004 * 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>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040016#include <linux/sched.h>
David Howellsbe080a62017-11-02 15:27:49 +000017#include <linux/hashtable.h>
David Howells00d3b7a2007-04-26 15:57:07 -070018#include <keys/rxrpc-type.h>
19#include "internal.h"
20
David Howellsbe080a62017-11-02 15:27:49 +000021static DEFINE_HASHTABLE(afs_permits_cache, 10);
22static DEFINE_SPINLOCK(afs_permits_lock);
23
David Howells00d3b7a2007-04-26 15:57:07 -070024/*
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/*
David Howellsbe080a62017-11-02 15:27:49 +000053 * Dispose of a list of permits.
David Howells00d3b7a2007-04-26 15:57:07 -070054 */
David Howellsbe080a62017-11-02 15:27:49 +000055static void afs_permits_rcu(struct rcu_head *rcu)
David Howells00d3b7a2007-04-26 15:57:07 -070056{
57 struct afs_permits *permits =
58 container_of(rcu, struct afs_permits, rcu);
David Howellsbe080a62017-11-02 15:27:49 +000059 int i;
David Howells00d3b7a2007-04-26 15:57:07 -070060
David Howellsbe080a62017-11-02 15:27:49 +000061 for (i = 0; i < permits->nr_permits; i++)
62 key_put(permits->permits[i].key);
David Howells00d3b7a2007-04-26 15:57:07 -070063 kfree(permits);
64}
65
66/*
David Howellsbe080a62017-11-02 15:27:49 +000067 * Discard a permission cache.
David Howells00d3b7a2007-04-26 15:57:07 -070068 */
David Howellsbe080a62017-11-02 15:27:49 +000069void afs_put_permits(struct afs_permits *permits)
David Howells00d3b7a2007-04-26 15:57:07 -070070{
David Howellsbe080a62017-11-02 15:27:49 +000071 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);
David Howells00d3b7a2007-04-26 15:57:07 -070076 }
David Howells00d3b7a2007-04-26 15:57:07 -070077}
78
79/*
David Howellsbe080a62017-11-02 15:27:49 +000080 * Clear a permit cache on callback break.
David Howells00d3b7a2007-04-26 15:57:07 -070081 */
82void afs_clear_permits(struct afs_vnode *vnode)
83{
84 struct afs_permits *permits;
85
David Howellsbe080a62017-11-02 15:27:49 +000086 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);
David Howellsbe080a62017-11-02 15:27:49 +000090 spin_unlock(&vnode->lock);
David Howells00d3b7a2007-04-26 15:57:07 -070091
David Howellsfd711582019-05-10 23:14:41 +010092 afs_put_permits(permits);
David Howells00d3b7a2007-04-26 15:57:07 -070093}
94
95/*
David Howellsbe080a62017-11-02 15:27:49 +000096 * Hash a list of permits. Use simple addition to make it easy to add an extra
97 * one at an as-yet indeterminate position in the list.
David Howells00d3b7a2007-04-26 15:57:07 -070098 */
David Howellsbe080a62017-11-02 15:27:49 +000099static void afs_hash_permits(struct afs_permits *permits)
David Howells00d3b7a2007-04-26 15:57:07 -0700100{
David Howellsbe080a62017-11-02 15:27:49 +0000101 unsigned long h = permits->nr_permits;
102 int i;
David Howells00d3b7a2007-04-26 15:57:07 -0700103
David Howellsbe080a62017-11-02 15:27:49 +0000104 for (i = 0; i < permits->nr_permits; i++) {
105 h += (unsigned long)permits->permits[i].key / sizeof(void *);
106 h += permits->permits[i].access;
David Howells00d3b7a2007-04-26 15:57:07 -0700107 }
108
David Howellsbe080a62017-11-02 15:27:49 +0000109 permits->h = h;
110}
David Howells00d3b7a2007-04-26 15:57:07 -0700111
David Howellsbe080a62017-11-02 15:27:49 +0000112/*
113 * Cache the CallerAccess result obtained from doing a fileserver operation
114 * that returned a vnode status for a particular key. If a callback break
115 * occurs whilst the operation was in progress then we have to ditch the cache
116 * as the ACL *may* have changed.
117 */
118void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
David Howellsa58823a2019-05-09 15:16:10 +0100119 unsigned int cb_break, struct afs_status_cb *scb)
David Howellsbe080a62017-11-02 15:27:49 +0000120{
David Howells1bcab122017-12-01 11:40:43 +0000121 struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
David Howellsa58823a2019-05-09 15:16:10 +0100122 afs_access_t caller_access = scb->status.caller_access;
David Howellsbe080a62017-11-02 15:27:49 +0000123 size_t size = 0;
124 bool changed = false;
125 int i, j;
David Howells00d3b7a2007-04-26 15:57:07 -0700126
David Howells3b6492d2018-10-20 00:57:57 +0100127 _enter("{%llx:%llu},%x,%x",
David Howellsbe080a62017-11-02 15:27:49 +0000128 vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
David Howells00d3b7a2007-04-26 15:57:07 -0700129
David Howellsbe080a62017-11-02 15:27:49 +0000130 rcu_read_lock();
David Howells00d3b7a2007-04-26 15:57:07 -0700131
David Howellsbe080a62017-11-02 15:27:49 +0000132 /* Check for the common case first: We got back the same access as last
133 * time we tried and already have it recorded.
134 */
135 permits = rcu_dereference(vnode->permit_cache);
136 if (permits) {
137 if (!permits->invalidated) {
138 for (i = 0; i < permits->nr_permits; i++) {
139 if (permits->permits[i].key < key)
140 continue;
141 if (permits->permits[i].key > key)
142 break;
143 if (permits->permits[i].access != caller_access) {
144 changed = true;
145 break;
146 }
147
David Howells18ac6182018-10-20 00:57:59 +0100148 if (afs_cb_is_broken(cb_break, vnode,
149 vnode->cb_interest)) {
David Howellsbe080a62017-11-02 15:27:49 +0000150 changed = true;
151 break;
152 }
153
154 /* The cache is still good. */
155 rcu_read_unlock();
156 return;
David Howells00d3b7a2007-04-26 15:57:07 -0700157 }
David Howellsbe080a62017-11-02 15:27:49 +0000158 }
159
160 changed |= permits->invalidated;
161 size = permits->nr_permits;
162
163 /* If this set of permits is now wrong, clear the permits
164 * pointer so that no one tries to use the stale information.
165 */
166 if (changed) {
167 spin_lock(&vnode->lock);
168 if (permits != rcu_access_pointer(vnode->permit_cache))
169 goto someone_else_changed_it_unlock;
170 RCU_INIT_POINTER(vnode->permit_cache, NULL);
171 spin_unlock(&vnode->lock);
172
173 afs_put_permits(permits);
174 permits = NULL;
175 size = 0;
David Howells00d3b7a2007-04-26 15:57:07 -0700176 }
177 }
178
David Howells18ac6182018-10-20 00:57:59 +0100179 if (afs_cb_is_broken(cb_break, vnode, vnode->cb_interest))
David Howellsbe080a62017-11-02 15:27:49 +0000180 goto someone_else_changed_it;
David Howells00d3b7a2007-04-26 15:57:07 -0700181
David Howellsbe080a62017-11-02 15:27:49 +0000182 /* We need a ref on any permits list we want to copy as we'll have to
183 * drop the lock to do memory allocation.
184 */
David Howellsfe342cf2018-04-09 21:12:31 +0100185 if (permits && !refcount_inc_not_zero(&permits->usage))
David Howellsbe080a62017-11-02 15:27:49 +0000186 goto someone_else_changed_it;
David Howells00d3b7a2007-04-26 15:57:07 -0700187
David Howellsbe080a62017-11-02 15:27:49 +0000188 rcu_read_unlock();
David Howells00d3b7a2007-04-26 15:57:07 -0700189
David Howellsbe080a62017-11-02 15:27:49 +0000190 /* Speculatively create a new list with the revised permission set. We
191 * discard this if we find an extant match already in the hash, but
192 * it's easier to compare with memcmp this way.
193 *
194 * We fill in the key pointers at this time, but we don't get the refs
195 * yet.
196 */
197 size++;
198 new = kzalloc(sizeof(struct afs_permits) +
199 sizeof(struct afs_permit) * size, GFP_NOFS);
200 if (!new)
David Howells1bcab122017-12-01 11:40:43 +0000201 goto out_put;
David Howells00d3b7a2007-04-26 15:57:07 -0700202
David Howellsbe080a62017-11-02 15:27:49 +0000203 refcount_set(&new->usage, 1);
204 new->nr_permits = size;
205 i = j = 0;
206 if (permits) {
207 for (i = 0; i < permits->nr_permits; i++) {
208 if (j == i && permits->permits[i].key > key) {
209 new->permits[j].key = key;
210 new->permits[j].access = caller_access;
211 j++;
212 }
213 new->permits[j].key = permits->permits[i].key;
214 new->permits[j].access = permits->permits[i].access;
215 j++;
216 }
217 }
218
219 if (j == i) {
220 new->permits[j].key = key;
221 new->permits[j].access = caller_access;
222 }
223
224 afs_hash_permits(new);
225
David Howellsbe080a62017-11-02 15:27:49 +0000226 /* Now see if the permit list we want is actually already available */
227 spin_lock(&afs_permits_lock);
228
229 hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
230 if (xpermits->h != new->h ||
231 xpermits->invalidated ||
232 xpermits->nr_permits != new->nr_permits ||
233 memcmp(xpermits->permits, new->permits,
234 new->nr_permits * sizeof(struct afs_permit)) != 0)
235 continue;
236
237 if (refcount_inc_not_zero(&xpermits->usage)) {
238 replacement = xpermits;
239 goto found;
240 }
241
242 break;
243 }
244
245 for (i = 0; i < new->nr_permits; i++)
246 key_get(new->permits[i].key);
247 hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
248 replacement = new;
249 new = NULL;
250
251found:
252 spin_unlock(&afs_permits_lock);
253
254 kfree(new);
255
256 spin_lock(&vnode->lock);
David Howells1bcab122017-12-01 11:40:43 +0000257 zap = rcu_access_pointer(vnode->permit_cache);
David Howells18ac6182018-10-20 00:57:59 +0100258 if (!afs_cb_is_broken(cb_break, vnode, vnode->cb_interest) &&
David Howells1bcab122017-12-01 11:40:43 +0000259 zap == permits)
260 rcu_assign_pointer(vnode->permit_cache, replacement);
261 else
262 zap = replacement;
David Howellsbe080a62017-11-02 15:27:49 +0000263 spin_unlock(&vnode->lock);
David Howells1bcab122017-12-01 11:40:43 +0000264 afs_put_permits(zap);
265out_put:
David Howellsbe080a62017-11-02 15:27:49 +0000266 afs_put_permits(permits);
267 return;
268
269someone_else_changed_it_unlock:
270 spin_unlock(&vnode->lock);
271someone_else_changed_it:
272 /* Someone else changed the cache under us - don't recheck at this
273 * time.
274 */
David Howellsfe342cf2018-04-09 21:12:31 +0100275 rcu_read_unlock();
David Howellsbe080a62017-11-02 15:27:49 +0000276 return;
David Howells00d3b7a2007-04-26 15:57:07 -0700277}
278
279/*
280 * check with the fileserver to see if the directory or parent directory is
281 * permitted to be accessed with this authorisation, and if so, what access it
282 * is granted
283 */
David Howells0fafdc92017-11-13 16:59:50 +0000284int afs_check_permit(struct afs_vnode *vnode, struct key *key,
285 afs_access_t *_access)
David Howells00d3b7a2007-04-26 15:57:07 -0700286{
287 struct afs_permits *permits;
David Howellsbe080a62017-11-02 15:27:49 +0000288 bool valid = false;
289 int i, ret;
David Howells00d3b7a2007-04-26 15:57:07 -0700290
David Howells3b6492d2018-10-20 00:57:57 +0100291 _enter("{%llx:%llu},%x",
David Howells416351f2007-05-09 02:33:45 -0700292 vnode->fid.vid, vnode->fid.vnode, key_serial(key));
David Howells00d3b7a2007-04-26 15:57:07 -0700293
David Howells00d3b7a2007-04-26 15:57:07 -0700294 /* check the permits to see if we've got one yet */
David Howellsbe080a62017-11-02 15:27:49 +0000295 if (key == vnode->volume->cell->anonymous_key) {
David Howells00d3b7a2007-04-26 15:57:07 -0700296 _debug("anon");
David Howellsbe080a62017-11-02 15:27:49 +0000297 *_access = vnode->status.anon_access;
David Howells00d3b7a2007-04-26 15:57:07 -0700298 valid = true;
299 } else {
David Howells00d3b7a2007-04-26 15:57:07 -0700300 rcu_read_lock();
David Howellsbe080a62017-11-02 15:27:49 +0000301 permits = rcu_dereference(vnode->permit_cache);
David Howells00d3b7a2007-04-26 15:57:07 -0700302 if (permits) {
David Howellsbe080a62017-11-02 15:27:49 +0000303 for (i = 0; i < permits->nr_permits; i++) {
304 if (permits->permits[i].key < key)
305 continue;
306 if (permits->permits[i].key > key)
David Howells00d3b7a2007-04-26 15:57:07 -0700307 break;
David Howellsbe080a62017-11-02 15:27:49 +0000308
309 *_access = permits->permits[i].access;
310 valid = !permits->invalidated;
311 break;
David Howells00d3b7a2007-04-26 15:57:07 -0700312 }
313 }
314 rcu_read_unlock();
315 }
316
317 if (!valid) {
David Howellsbe080a62017-11-02 15:27:49 +0000318 /* Check the status on the file we're actually interested in
319 * (the post-processing will cache the result).
320 */
David Howells00d3b7a2007-04-26 15:57:07 -0700321 _debug("no valid permit");
322
David Howellsa58823a2019-05-09 15:16:10 +0100323 ret = afs_fetch_status(vnode, key, false, _access);
David Howells00d3b7a2007-04-26 15:57:07 -0700324 if (ret < 0) {
David Howells00d3b7a2007-04-26 15:57:07 -0700325 *_access = 0;
326 _leave(" = %d", ret);
327 return ret;
328 }
329 }
330
David Howells00d3b7a2007-04-26 15:57:07 -0700331 _leave(" = 0 [access %x]", *_access);
332 return 0;
333}
334
335/*
336 * check the permissions on an AFS file
337 * - AFS ACLs are attached to directories only, and a file is controlled by its
338 * parent directory's ACL
339 */
Al Viro10556cb22011-06-20 19:28:19 -0400340int afs_permission(struct inode *inode, int mask)
David Howells00d3b7a2007-04-26 15:57:07 -0700341{
342 struct afs_vnode *vnode = AFS_FS_I(inode);
Andrew Morton69759452008-02-08 04:20:53 -0800343 afs_access_t uninitialized_var(access);
David Howells00d3b7a2007-04-26 15:57:07 -0700344 struct key *key;
345 int ret;
346
Al Viro10556cb22011-06-20 19:28:19 -0400347 if (mask & MAY_NOT_BLOCK)
Nick Pigginb74c79e2011-01-07 17:49:58 +1100348 return -ECHILD;
349
David Howells3b6492d2018-10-20 00:57:57 +0100350 _enter("{{%llx:%llu},%lx},%x,",
David Howells260a9802007-04-26 15:59:35 -0700351 vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
David Howells00d3b7a2007-04-26 15:57:07 -0700352
353 key = afs_request_key(vnode->volume->cell);
354 if (IS_ERR(key)) {
355 _leave(" = %ld [key]", PTR_ERR(key));
356 return PTR_ERR(key);
357 }
358
David Howellsc435ee32017-11-02 15:27:49 +0000359 ret = afs_validate(vnode, key);
360 if (ret < 0)
361 goto error;
David Howells260a9802007-04-26 15:59:35 -0700362
David Howells00d3b7a2007-04-26 15:57:07 -0700363 /* check the permits to see if we've got one yet */
364 ret = afs_check_permit(vnode, key, &access);
David Howells260a9802007-04-26 15:59:35 -0700365 if (ret < 0)
366 goto error;
David Howells00d3b7a2007-04-26 15:57:07 -0700367
368 /* interpret the access mask */
369 _debug("REQ %x ACC %x on %s",
370 mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
371
372 if (S_ISDIR(inode->i_mode)) {
David Howells378831e2018-05-16 21:25:46 +0100373 if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) {
David Howells00d3b7a2007-04-26 15:57:07 -0700374 if (!(access & AFS_ACE_LOOKUP))
375 goto permission_denied;
David Howells378831e2018-05-16 21:25:46 +0100376 }
377 if (mask & MAY_WRITE) {
David Howells00d3b7a2007-04-26 15:57:07 -0700378 if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
Marc Dionnefd249822017-07-06 15:50:18 +0100379 AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
David Howells00d3b7a2007-04-26 15:57:07 -0700380 goto permission_denied;
David Howells00d3b7a2007-04-26 15:57:07 -0700381 }
382 } else {
383 if (!(access & AFS_ACE_LOOKUP))
384 goto permission_denied;
Marc Dionne627f4692017-03-16 16:27:44 +0000385 if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
386 goto permission_denied;
David Howells00d3b7a2007-04-26 15:57:07 -0700387 if (mask & (MAY_EXEC | MAY_READ)) {
388 if (!(access & AFS_ACE_READ))
389 goto permission_denied;
Marc Dionne627f4692017-03-16 16:27:44 +0000390 if (!(inode->i_mode & S_IRUSR))
391 goto permission_denied;
David Howells00d3b7a2007-04-26 15:57:07 -0700392 } else if (mask & MAY_WRITE) {
393 if (!(access & AFS_ACE_WRITE))
394 goto permission_denied;
Marc Dionne627f4692017-03-16 16:27:44 +0000395 if (!(inode->i_mode & S_IWUSR))
396 goto permission_denied;
David Howells00d3b7a2007-04-26 15:57:07 -0700397 }
398 }
399
400 key_put(key);
David Howells260a9802007-04-26 15:59:35 -0700401 _leave(" = %d", ret);
402 return ret;
David Howells00d3b7a2007-04-26 15:57:07 -0700403
404permission_denied:
David Howells260a9802007-04-26 15:59:35 -0700405 ret = -EACCES;
406error:
David Howells00d3b7a2007-04-26 15:57:07 -0700407 key_put(key);
David Howells260a9802007-04-26 15:59:35 -0700408 _leave(" = %d", ret);
409 return ret;
David Howells00d3b7a2007-04-26 15:57:07 -0700410}
David Howellsbe080a62017-11-02 15:27:49 +0000411
412void __exit afs_clean_up_permit_cache(void)
413{
414 int i;
415
416 for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
417 WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
418
419}