1 /* AFS security handling
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/init.h>
13 #include <linux/slab.h>
15 #include <linux/ctype.h>
16 #include <linux/sched.h>
17 #include <keys/rxrpc-type.h>
23 struct key
*afs_request_key(struct afs_cell
*cell
)
27 _enter("{%x}", key_serial(cell
->anonymous_key
));
29 _debug("key %s", cell
->anonymous_key
->description
);
30 key
= request_key(&key_type_rxrpc
, cell
->anonymous_key
->description
,
33 if (PTR_ERR(key
) != -ENOKEY
) {
34 _leave(" = %ld", PTR_ERR(key
));
38 /* act as anonymous user */
39 _leave(" = {%x} [anon]", key_serial(cell
->anonymous_key
));
40 return key_get(cell
->anonymous_key
);
42 /* act as authorised user */
43 _leave(" = {%x} [auth]", key_serial(key
));
49 * dispose of a permits list
51 void afs_zap_permits(struct rcu_head
*rcu
)
53 struct afs_permits
*permits
=
54 container_of(rcu
, struct afs_permits
, rcu
);
57 _enter("{%d}", permits
->count
);
59 for (loop
= permits
->count
- 1; loop
>= 0; loop
--)
60 key_put(permits
->permits
[loop
].key
);
65 * dispose of a permits list in which all the key pointers have been copied
67 static void afs_dispose_of_permits(struct rcu_head
*rcu
)
69 struct afs_permits
*permits
=
70 container_of(rcu
, struct afs_permits
, rcu
);
72 _enter("{%d}", permits
->count
);
78 * get the authorising vnode - this is the specified inode itself if it's a
79 * directory or it's the parent directory if the specified inode is a file or
81 * - the caller must release the ref on the inode
83 static struct afs_vnode
*afs_get_auth_inode(struct afs_vnode
*vnode
,
86 struct afs_vnode
*auth_vnode
;
87 struct inode
*auth_inode
;
91 if (S_ISDIR(vnode
->vfs_inode
.i_mode
)) {
92 auth_inode
= igrab(&vnode
->vfs_inode
);
93 ASSERT(auth_inode
!= NULL
);
95 auth_inode
= afs_iget(vnode
->vfs_inode
.i_sb
, key
,
96 &vnode
->status
.parent
, NULL
, NULL
);
97 if (IS_ERR(auth_inode
))
98 return ERR_CAST(auth_inode
);
101 auth_vnode
= AFS_FS_I(auth_inode
);
102 _leave(" = {%x}", auth_vnode
->fid
.vnode
);
107 * clear the permit cache on a directory vnode
109 void afs_clear_permits(struct afs_vnode
*vnode
)
111 struct afs_permits
*permits
;
113 _enter("{%x:%u}", vnode
->fid
.vid
, vnode
->fid
.vnode
);
115 mutex_lock(&vnode
->permits_lock
);
116 permits
= vnode
->permits
;
117 RCU_INIT_POINTER(vnode
->permits
, NULL
);
118 mutex_unlock(&vnode
->permits_lock
);
121 call_rcu(&permits
->rcu
, afs_zap_permits
);
126 * add the result obtained for a vnode to its or its parent directory's cache
127 * for the key used to access it
129 void afs_cache_permit(struct afs_vnode
*vnode
, struct key
*key
, long acl_order
)
131 struct afs_permits
*permits
, *xpermits
;
132 struct afs_permit
*permit
;
133 struct afs_vnode
*auth_vnode
;
136 _enter("{%x:%u},%x,%lx",
137 vnode
->fid
.vid
, vnode
->fid
.vnode
, key_serial(key
), acl_order
);
139 auth_vnode
= afs_get_auth_inode(vnode
, key
);
140 if (IS_ERR(auth_vnode
)) {
141 _leave(" [get error %ld]", PTR_ERR(auth_vnode
));
145 mutex_lock(&auth_vnode
->permits_lock
);
147 /* guard against a rename being detected whilst we waited for the
149 if (memcmp(&auth_vnode
->fid
, &vnode
->status
.parent
,
150 sizeof(struct afs_fid
)) != 0) {
155 /* have to be careful as the directory's callback may be broken between
156 * us receiving the status we're trying to cache and us getting the
157 * lock to update the cache for the status */
158 if (auth_vnode
->acl_order
- acl_order
> 0) {
159 _debug("ACL changed?");
163 /* always update the anonymous mask */
164 _debug("anon access %x", vnode
->status
.anon_access
);
165 auth_vnode
->status
.anon_access
= vnode
->status
.anon_access
;
166 if (key
== vnode
->volume
->cell
->anonymous_key
)
169 xpermits
= auth_vnode
->permits
;
172 /* see if the permit is already in the list
173 * - if it is then we just amend the list
175 count
= xpermits
->count
;
176 permit
= xpermits
->permits
;
177 for (loop
= count
; loop
> 0; loop
--) {
178 if (permit
->key
== key
) {
179 permit
->access_mask
=
180 vnode
->status
.caller_access
;
187 permits
= kmalloc(sizeof(*permits
) + sizeof(*permit
) * (count
+ 1),
193 memcpy(permits
->permits
, xpermits
->permits
,
194 count
* sizeof(struct afs_permit
));
196 _debug("key %x access %x",
197 key_serial(key
), vnode
->status
.caller_access
);
198 permits
->permits
[count
].access_mask
= vnode
->status
.caller_access
;
199 permits
->permits
[count
].key
= key_get(key
);
200 permits
->count
= count
+ 1;
202 rcu_assign_pointer(auth_vnode
->permits
, permits
);
204 call_rcu(&xpermits
->rcu
, afs_dispose_of_permits
);
207 mutex_unlock(&auth_vnode
->permits_lock
);
208 iput(&auth_vnode
->vfs_inode
);
213 * check with the fileserver to see if the directory or parent directory is
214 * permitted to be accessed with this authorisation, and if so, what access it
217 static int afs_check_permit(struct afs_vnode
*vnode
, struct key
*key
,
218 afs_access_t
*_access
)
220 struct afs_permits
*permits
;
221 struct afs_permit
*permit
;
222 struct afs_vnode
*auth_vnode
;
227 vnode
->fid
.vid
, vnode
->fid
.vnode
, key_serial(key
));
229 auth_vnode
= afs_get_auth_inode(vnode
, key
);
230 if (IS_ERR(auth_vnode
)) {
232 _leave(" = %ld", PTR_ERR(auth_vnode
));
233 return PTR_ERR(auth_vnode
);
236 ASSERT(S_ISDIR(auth_vnode
->vfs_inode
.i_mode
));
238 /* check the permits to see if we've got one yet */
239 if (key
== auth_vnode
->volume
->cell
->anonymous_key
) {
241 *_access
= auth_vnode
->status
.anon_access
;
246 permits
= rcu_dereference(auth_vnode
->permits
);
248 permit
= permits
->permits
;
249 for (loop
= permits
->count
; loop
> 0; loop
--) {
250 if (permit
->key
== key
) {
251 _debug("found in cache");
252 *_access
= permit
->access_mask
;
263 /* check the status on the file we're actually interested in
264 * (the post-processing will cache the result on auth_vnode) */
265 _debug("no valid permit");
267 set_bit(AFS_VNODE_CB_BROKEN
, &vnode
->flags
);
268 ret
= afs_vnode_fetch_status(vnode
, auth_vnode
, key
);
270 iput(&auth_vnode
->vfs_inode
);
272 _leave(" = %d", ret
);
275 *_access
= vnode
->status
.caller_access
;
278 iput(&auth_vnode
->vfs_inode
);
279 _leave(" = 0 [access %x]", *_access
);
284 * check the permissions on an AFS file
285 * - AFS ACLs are attached to directories only, and a file is controlled by its
286 * parent directory's ACL
288 int afs_permission(struct inode
*inode
, int mask
)
290 struct afs_vnode
*vnode
= AFS_FS_I(inode
);
291 afs_access_t
uninitialized_var(access
);
295 if (mask
& MAY_NOT_BLOCK
)
298 _enter("{{%x:%u},%lx},%x,",
299 vnode
->fid
.vid
, vnode
->fid
.vnode
, vnode
->flags
, mask
);
301 key
= afs_request_key(vnode
->volume
->cell
);
303 _leave(" = %ld [key]", PTR_ERR(key
));
307 /* if the promise has expired, we need to check the server again */
308 if (!vnode
->cb_promised
) {
309 _debug("not promised");
310 ret
= afs_vnode_fetch_status(vnode
, NULL
, key
);
313 _debug("new promise [fl=%lx]", vnode
->flags
);
316 /* check the permits to see if we've got one yet */
317 ret
= afs_check_permit(vnode
, key
, &access
);
321 /* interpret the access mask */
322 _debug("REQ %x ACC %x on %s",
323 mask
, access
, S_ISDIR(inode
->i_mode
) ? "dir" : "file");
325 if (S_ISDIR(inode
->i_mode
)) {
326 if (mask
& MAY_EXEC
) {
327 if (!(access
& AFS_ACE_LOOKUP
))
328 goto permission_denied
;
329 } else if (mask
& MAY_READ
) {
330 if (!(access
& AFS_ACE_READ
))
331 goto permission_denied
;
332 } else if (mask
& MAY_WRITE
) {
333 if (!(access
& (AFS_ACE_DELETE
| /* rmdir, unlink, rename from */
334 AFS_ACE_INSERT
| /* create, mkdir, symlink, rename to */
335 AFS_ACE_WRITE
))) /* chmod */
336 goto permission_denied
;
341 if (!(access
& AFS_ACE_LOOKUP
))
342 goto permission_denied
;
343 if ((mask
& MAY_EXEC
) && !(inode
->i_mode
& S_IXUSR
))
344 goto permission_denied
;
345 if (mask
& (MAY_EXEC
| MAY_READ
)) {
346 if (!(access
& AFS_ACE_READ
))
347 goto permission_denied
;
348 if (!(inode
->i_mode
& S_IRUSR
))
349 goto permission_denied
;
350 } else if (mask
& MAY_WRITE
) {
351 if (!(access
& AFS_ACE_WRITE
))
352 goto permission_denied
;
353 if (!(inode
->i_mode
& S_IWUSR
))
354 goto permission_denied
;
359 _leave(" = %d", ret
);
366 _leave(" = %d", ret
);