xfs: cache negative ACLs if there is no attribute fork
[linux-2.6.git] / fs / xfs / linux-2.6 / xfs_acl.c
blob13c4e4fd5c6eda7007d9a607b6bc7981c95888cb
1 /*
2 * Copyright (c) 2008, Christoph Hellwig
3 * All Rights Reserved.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation.
9 * This program is distributed in the hope that it would be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 #include "xfs.h"
19 #include "xfs_acl.h"
20 #include "xfs_attr.h"
21 #include "xfs_bmap_btree.h"
22 #include "xfs_inode.h"
23 #include "xfs_vnodeops.h"
24 #include "xfs_trace.h"
25 #include <linux/slab.h>
26 #include <linux/xattr.h>
27 #include <linux/posix_acl_xattr.h>
31 * Locking scheme:
32 * - all ACL updates are protected by inode->i_mutex, which is taken before
33 * calling into this file.
36 STATIC struct posix_acl *
37 xfs_acl_from_disk(struct xfs_acl *aclp)
39 struct posix_acl_entry *acl_e;
40 struct posix_acl *acl;
41 struct xfs_acl_entry *ace;
42 int count, i;
44 count = be32_to_cpu(aclp->acl_cnt);
46 acl = posix_acl_alloc(count, GFP_KERNEL);
47 if (!acl)
48 return ERR_PTR(-ENOMEM);
50 for (i = 0; i < count; i++) {
51 acl_e = &acl->a_entries[i];
52 ace = &aclp->acl_entry[i];
55 * The tag is 32 bits on disk and 16 bits in core.
57 * Because every access to it goes through the core
58 * format first this is not a problem.
60 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
61 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
63 switch (acl_e->e_tag) {
64 case ACL_USER:
65 case ACL_GROUP:
66 acl_e->e_id = be32_to_cpu(ace->ae_id);
67 break;
68 case ACL_USER_OBJ:
69 case ACL_GROUP_OBJ:
70 case ACL_MASK:
71 case ACL_OTHER:
72 acl_e->e_id = ACL_UNDEFINED_ID;
73 break;
74 default:
75 goto fail;
78 return acl;
80 fail:
81 posix_acl_release(acl);
82 return ERR_PTR(-EINVAL);
85 STATIC void
86 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
88 const struct posix_acl_entry *acl_e;
89 struct xfs_acl_entry *ace;
90 int i;
92 aclp->acl_cnt = cpu_to_be32(acl->a_count);
93 for (i = 0; i < acl->a_count; i++) {
94 ace = &aclp->acl_entry[i];
95 acl_e = &acl->a_entries[i];
97 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
98 ace->ae_id = cpu_to_be32(acl_e->e_id);
99 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
103 struct posix_acl *
104 xfs_get_acl(struct inode *inode, int type)
106 struct xfs_inode *ip = XFS_I(inode);
107 struct posix_acl *acl;
108 struct xfs_acl *xfs_acl;
109 int len = sizeof(struct xfs_acl);
110 unsigned char *ea_name;
111 int error;
113 acl = get_cached_acl(inode, type);
114 if (acl != ACL_NOT_CACHED)
115 return acl;
117 switch (type) {
118 case ACL_TYPE_ACCESS:
119 ea_name = SGI_ACL_FILE;
120 break;
121 case ACL_TYPE_DEFAULT:
122 ea_name = SGI_ACL_DEFAULT;
123 break;
124 default:
125 BUG();
129 * If we have a cached ACLs value just return it, not need to
130 * go out to the disk.
133 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
134 if (!xfs_acl)
135 return ERR_PTR(-ENOMEM);
137 error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
138 &len, ATTR_ROOT);
139 if (error) {
141 * If the attribute doesn't exist make sure we have a negative
142 * cache entry, for any other error assume it is transient and
143 * leave the cache entry as ACL_NOT_CACHED.
145 if (error == -ENOATTR) {
146 acl = NULL;
147 goto out_update_cache;
149 goto out;
152 acl = xfs_acl_from_disk(xfs_acl);
153 if (IS_ERR(acl))
154 goto out;
156 out_update_cache:
157 set_cached_acl(inode, type, acl);
158 out:
159 kfree(xfs_acl);
160 return acl;
163 STATIC int
164 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
166 struct xfs_inode *ip = XFS_I(inode);
167 unsigned char *ea_name;
168 int error;
170 if (S_ISLNK(inode->i_mode))
171 return -EOPNOTSUPP;
173 switch (type) {
174 case ACL_TYPE_ACCESS:
175 ea_name = SGI_ACL_FILE;
176 break;
177 case ACL_TYPE_DEFAULT:
178 if (!S_ISDIR(inode->i_mode))
179 return acl ? -EACCES : 0;
180 ea_name = SGI_ACL_DEFAULT;
181 break;
182 default:
183 return -EINVAL;
186 if (acl) {
187 struct xfs_acl *xfs_acl;
188 int len;
190 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
191 if (!xfs_acl)
192 return -ENOMEM;
194 xfs_acl_to_disk(xfs_acl, acl);
195 len = sizeof(struct xfs_acl) -
196 (sizeof(struct xfs_acl_entry) *
197 (XFS_ACL_MAX_ENTRIES - acl->a_count));
199 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
200 len, ATTR_ROOT);
202 kfree(xfs_acl);
203 } else {
205 * A NULL ACL argument means we want to remove the ACL.
207 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
210 * If the attribute didn't exist to start with that's fine.
212 if (error == -ENOATTR)
213 error = 0;
216 if (!error)
217 set_cached_acl(inode, type, acl);
218 return error;
222 xfs_check_acl(struct inode *inode, int mask)
224 struct posix_acl *acl;
225 int error = -EAGAIN;
227 trace_xfs_check_acl(XFS_I(inode));
229 acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
230 if (IS_ERR(acl))
231 return PTR_ERR(acl);
232 if (acl) {
233 error = posix_acl_permission(inode, acl, mask);
234 posix_acl_release(acl);
237 return error;
240 static int
241 xfs_set_mode(struct inode *inode, mode_t mode)
243 int error = 0;
245 if (mode != inode->i_mode) {
246 struct iattr iattr;
248 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
249 iattr.ia_mode = mode;
250 iattr.ia_ctime = current_fs_time(inode->i_sb);
252 error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
255 return error;
258 static int
259 xfs_acl_exists(struct inode *inode, unsigned char *name)
261 int len = sizeof(struct xfs_acl);
263 return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
264 ATTR_ROOT|ATTR_KERNOVAL) == 0);
268 posix_acl_access_exists(struct inode *inode)
270 return xfs_acl_exists(inode, SGI_ACL_FILE);
274 posix_acl_default_exists(struct inode *inode)
276 if (!S_ISDIR(inode->i_mode))
277 return 0;
278 return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
282 * No need for i_mutex because the inode is not yet exposed to the VFS.
285 xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
287 struct posix_acl *clone;
288 mode_t mode;
289 int error = 0, inherit = 0;
291 if (S_ISDIR(inode->i_mode)) {
292 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
293 if (error)
294 return error;
297 clone = posix_acl_clone(default_acl, GFP_KERNEL);
298 if (!clone)
299 return -ENOMEM;
301 mode = inode->i_mode;
302 error = posix_acl_create_masq(clone, &mode);
303 if (error < 0)
304 goto out_release_clone;
307 * If posix_acl_create_masq returns a positive value we need to
308 * inherit a permission that can't be represented using the Unix
309 * mode bits and we actually need to set an ACL.
311 if (error > 0)
312 inherit = 1;
314 error = xfs_set_mode(inode, mode);
315 if (error)
316 goto out_release_clone;
318 if (inherit)
319 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
321 out_release_clone:
322 posix_acl_release(clone);
323 return error;
327 xfs_acl_chmod(struct inode *inode)
329 struct posix_acl *acl, *clone;
330 int error;
332 if (S_ISLNK(inode->i_mode))
333 return -EOPNOTSUPP;
335 acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
336 if (IS_ERR(acl) || !acl)
337 return PTR_ERR(acl);
339 clone = posix_acl_clone(acl, GFP_KERNEL);
340 posix_acl_release(acl);
341 if (!clone)
342 return -ENOMEM;
344 error = posix_acl_chmod_masq(clone, inode->i_mode);
345 if (!error)
346 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
348 posix_acl_release(clone);
349 return error;
352 static int
353 xfs_xattr_acl_get(struct dentry *dentry, const char *name,
354 void *value, size_t size, int type)
356 struct posix_acl *acl;
357 int error;
359 acl = xfs_get_acl(dentry->d_inode, type);
360 if (IS_ERR(acl))
361 return PTR_ERR(acl);
362 if (acl == NULL)
363 return -ENODATA;
365 error = posix_acl_to_xattr(acl, value, size);
366 posix_acl_release(acl);
368 return error;
371 static int
372 xfs_xattr_acl_set(struct dentry *dentry, const char *name,
373 const void *value, size_t size, int flags, int type)
375 struct inode *inode = dentry->d_inode;
376 struct posix_acl *acl = NULL;
377 int error = 0;
379 if (flags & XATTR_CREATE)
380 return -EINVAL;
381 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
382 return value ? -EACCES : 0;
383 if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
384 return -EPERM;
386 if (!value)
387 goto set_acl;
389 acl = posix_acl_from_xattr(value, size);
390 if (!acl) {
392 * acl_set_file(3) may request that we set default ACLs with
393 * zero length -- defend (gracefully) against that here.
395 goto out;
397 if (IS_ERR(acl)) {
398 error = PTR_ERR(acl);
399 goto out;
402 error = posix_acl_valid(acl);
403 if (error)
404 goto out_release;
406 error = -EINVAL;
407 if (acl->a_count > XFS_ACL_MAX_ENTRIES)
408 goto out_release;
410 if (type == ACL_TYPE_ACCESS) {
411 mode_t mode = inode->i_mode;
412 error = posix_acl_equiv_mode(acl, &mode);
414 if (error <= 0) {
415 posix_acl_release(acl);
416 acl = NULL;
418 if (error < 0)
419 return error;
422 error = xfs_set_mode(inode, mode);
423 if (error)
424 goto out_release;
427 set_acl:
428 error = xfs_set_acl(inode, type, acl);
429 out_release:
430 posix_acl_release(acl);
431 out:
432 return error;
435 const struct xattr_handler xfs_xattr_acl_access_handler = {
436 .prefix = POSIX_ACL_XATTR_ACCESS,
437 .flags = ACL_TYPE_ACCESS,
438 .get = xfs_xattr_acl_get,
439 .set = xfs_xattr_acl_set,
442 const struct xattr_handler xfs_xattr_acl_default_handler = {
443 .prefix = POSIX_ACL_XATTR_DEFAULT,
444 .flags = ACL_TYPE_DEFAULT,
445 .get = xfs_xattr_acl_get,
446 .set = xfs_xattr_acl_set,