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Linux/fs/xfs/xfs_acl.c

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  1 /*
  2  * Copyright (c) 2008, Christoph Hellwig
  3  * All Rights Reserved.
  4  *
  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.
  8  *
  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.
 13  *
 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
 17  */
 18 #include "xfs.h"
 19 #include "xfs_log_format.h"
 20 #include "xfs_trans_resv.h"
 21 #include "xfs_acl.h"
 22 #include "xfs_attr.h"
 23 #include "xfs_bmap_btree.h"
 24 #include "xfs_inode.h"
 25 #include "xfs_ag.h"
 26 #include "xfs_sb.h"
 27 #include "xfs_mount.h"
 28 #include "xfs_trace.h"
 29 #include <linux/slab.h>
 30 #include <linux/xattr.h>
 31 #include <linux/posix_acl_xattr.h>
 32 
 33 
 34 /*
 35  * Locking scheme:
 36  *  - all ACL updates are protected by inode->i_mutex, which is taken before
 37  *    calling into this file.
 38  */
 39 
 40 STATIC struct posix_acl *
 41 xfs_acl_from_disk(
 42         struct xfs_acl  *aclp,
 43         int             max_entries)
 44 {
 45         struct posix_acl_entry *acl_e;
 46         struct posix_acl *acl;
 47         struct xfs_acl_entry *ace;
 48         unsigned int count, i;
 49 
 50         count = be32_to_cpu(aclp->acl_cnt);
 51         if (count > max_entries)
 52                 return ERR_PTR(-EFSCORRUPTED);
 53 
 54         acl = posix_acl_alloc(count, GFP_KERNEL);
 55         if (!acl)
 56                 return ERR_PTR(-ENOMEM);
 57 
 58         for (i = 0; i < count; i++) {
 59                 acl_e = &acl->a_entries[i];
 60                 ace = &aclp->acl_entry[i];
 61 
 62                 /*
 63                  * The tag is 32 bits on disk and 16 bits in core.
 64                  *
 65                  * Because every access to it goes through the core
 66                  * format first this is not a problem.
 67                  */
 68                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
 69                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
 70 
 71                 switch (acl_e->e_tag) {
 72                 case ACL_USER:
 73                         acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
 74                         break;
 75                 case ACL_GROUP:
 76                         acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
 77                         break;
 78                 case ACL_USER_OBJ:
 79                 case ACL_GROUP_OBJ:
 80                 case ACL_MASK:
 81                 case ACL_OTHER:
 82                         break;
 83                 default:
 84                         goto fail;
 85                 }
 86         }
 87         return acl;
 88 
 89 fail:
 90         posix_acl_release(acl);
 91         return ERR_PTR(-EINVAL);
 92 }
 93 
 94 STATIC void
 95 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
 96 {
 97         const struct posix_acl_entry *acl_e;
 98         struct xfs_acl_entry *ace;
 99         int i;
100 
101         aclp->acl_cnt = cpu_to_be32(acl->a_count);
102         for (i = 0; i < acl->a_count; i++) {
103                 ace = &aclp->acl_entry[i];
104                 acl_e = &acl->a_entries[i];
105 
106                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
107                 switch (acl_e->e_tag) {
108                 case ACL_USER:
109                         ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
110                         break;
111                 case ACL_GROUP:
112                         ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
113                         break;
114                 default:
115                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
116                         break;
117                 }
118 
119                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
120         }
121 }
122 
123 struct posix_acl *
124 xfs_get_acl(struct inode *inode, int type)
125 {
126         struct xfs_inode *ip = XFS_I(inode);
127         struct posix_acl *acl;
128         struct xfs_acl *xfs_acl;
129         unsigned char *ea_name;
130         int error;
131         int len;
132 
133         acl = get_cached_acl(inode, type);
134         if (acl != ACL_NOT_CACHED)
135                 return acl;
136 
137         trace_xfs_get_acl(ip);
138 
139         switch (type) {
140         case ACL_TYPE_ACCESS:
141                 ea_name = SGI_ACL_FILE;
142                 break;
143         case ACL_TYPE_DEFAULT:
144                 ea_name = SGI_ACL_DEFAULT;
145                 break;
146         default:
147                 BUG();
148         }
149 
150         /*
151          * If we have a cached ACLs value just return it, not need to
152          * go out to the disk.
153          */
154         len = XFS_ACL_MAX_SIZE(ip->i_mount);
155         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
156         if (!xfs_acl)
157                 return ERR_PTR(-ENOMEM);
158 
159         error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
160                                                         &len, ATTR_ROOT);
161         if (error) {
162                 /*
163                  * If the attribute doesn't exist make sure we have a negative
164                  * cache entry, for any other error assume it is transient and
165                  * leave the cache entry as ACL_NOT_CACHED.
166                  */
167                 if (error == -ENOATTR) {
168                         acl = NULL;
169                         goto out_update_cache;
170                 }
171                 goto out;
172         }
173 
174         acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
175         if (IS_ERR(acl))
176                 goto out;
177 
178 out_update_cache:
179         set_cached_acl(inode, type, acl);
180 out:
181         kmem_free(xfs_acl);
182         return acl;
183 }
184 
185 STATIC int
186 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
187 {
188         struct xfs_inode *ip = XFS_I(inode);
189         unsigned char *ea_name;
190         int error;
191 
192         if (S_ISLNK(inode->i_mode))
193                 return -EOPNOTSUPP;
194 
195         switch (type) {
196         case ACL_TYPE_ACCESS:
197                 ea_name = SGI_ACL_FILE;
198                 break;
199         case ACL_TYPE_DEFAULT:
200                 if (!S_ISDIR(inode->i_mode))
201                         return acl ? -EACCES : 0;
202                 ea_name = SGI_ACL_DEFAULT;
203                 break;
204         default:
205                 return -EINVAL;
206         }
207 
208         if (acl) {
209                 struct xfs_acl *xfs_acl;
210                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
211 
212                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
213                 if (!xfs_acl)
214                         return -ENOMEM;
215 
216                 xfs_acl_to_disk(xfs_acl, acl);
217 
218                 /* subtract away the unused acl entries */
219                 len -= sizeof(struct xfs_acl_entry) *
220                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
221 
222                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
223                                 len, ATTR_ROOT);
224 
225                 kmem_free(xfs_acl);
226         } else {
227                 /*
228                  * A NULL ACL argument means we want to remove the ACL.
229                  */
230                 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
231 
232                 /*
233                  * If the attribute didn't exist to start with that's fine.
234                  */
235                 if (error == -ENOATTR)
236                         error = 0;
237         }
238 
239         if (!error)
240                 set_cached_acl(inode, type, acl);
241         return error;
242 }
243 
244 static int
245 xfs_set_mode(struct inode *inode, umode_t mode)
246 {
247         int error = 0;
248 
249         if (mode != inode->i_mode) {
250                 struct iattr iattr;
251 
252                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
253                 iattr.ia_mode = mode;
254                 iattr.ia_ctime = current_fs_time(inode->i_sb);
255 
256                 error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
257         }
258 
259         return error;
260 }
261 
262 static int
263 xfs_acl_exists(struct inode *inode, unsigned char *name)
264 {
265         int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
266 
267         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
268                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
269 }
270 
271 int
272 posix_acl_access_exists(struct inode *inode)
273 {
274         return xfs_acl_exists(inode, SGI_ACL_FILE);
275 }
276 
277 int
278 posix_acl_default_exists(struct inode *inode)
279 {
280         if (!S_ISDIR(inode->i_mode))
281                 return 0;
282         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
283 }
284 
285 /*
286  * No need for i_mutex because the inode is not yet exposed to the VFS.
287  */
288 int
289 xfs_inherit_acl(struct inode *inode, struct posix_acl *acl)
290 {
291         umode_t mode = inode->i_mode;
292         int error = 0, inherit = 0;
293 
294         if (S_ISDIR(inode->i_mode)) {
295                 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, acl);
296                 if (error)
297                         goto out;
298         }
299 
300         error = posix_acl_create(&acl, GFP_KERNEL, &mode);
301         if (error < 0)
302                 return error;
303 
304         /*
305          * If posix_acl_create returns a positive value we need to
306          * inherit a permission that can't be represented using the Unix
307          * mode bits and we actually need to set an ACL.
308          */
309         if (error > 0)
310                 inherit = 1;
311 
312         error = xfs_set_mode(inode, mode);
313         if (error)
314                 goto out;
315 
316         if (inherit)
317                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
318 
319 out:
320         posix_acl_release(acl);
321         return error;
322 }
323 
324 int
325 xfs_acl_chmod(struct inode *inode)
326 {
327         struct posix_acl *acl;
328         int error;
329 
330         if (S_ISLNK(inode->i_mode))
331                 return -EOPNOTSUPP;
332 
333         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
334         if (IS_ERR(acl) || !acl)
335                 return PTR_ERR(acl);
336 
337         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
338         if (error)
339                 return error;
340 
341         error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
342         posix_acl_release(acl);
343         return error;
344 }
345 
346 static int
347 xfs_xattr_acl_get(struct dentry *dentry, const char *name,
348                 void *value, size_t size, int type)
349 {
350         struct posix_acl *acl;
351         int error;
352 
353         acl = xfs_get_acl(dentry->d_inode, type);
354         if (IS_ERR(acl))
355                 return PTR_ERR(acl);
356         if (acl == NULL)
357                 return -ENODATA;
358 
359         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
360         posix_acl_release(acl);
361 
362         return error;
363 }
364 
365 static int
366 xfs_xattr_acl_set(struct dentry *dentry, const char *name,
367                 const void *value, size_t size, int flags, int type)
368 {
369         struct inode *inode = dentry->d_inode;
370         struct posix_acl *acl = NULL;
371         int error = 0;
372 
373         if (flags & XATTR_CREATE)
374                 return -EINVAL;
375         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
376                 return value ? -EACCES : 0;
377         if (!inode_owner_or_capable(inode))
378                 return -EPERM;
379 
380         if (!value)
381                 goto set_acl;
382 
383         acl = posix_acl_from_xattr(&init_user_ns, value, size);
384         if (!acl) {
385                 /*
386                  * acl_set_file(3) may request that we set default ACLs with
387                  * zero length -- defend (gracefully) against that here.
388                  */
389                 goto out;
390         }
391         if (IS_ERR(acl)) {
392                 error = PTR_ERR(acl);
393                 goto out;
394         }
395 
396         error = posix_acl_valid(acl);
397         if (error)
398                 goto out_release;
399 
400         error = -EINVAL;
401         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
402                 goto out_release;
403 
404         if (type == ACL_TYPE_ACCESS) {
405                 umode_t mode;
406                 struct posix_acl *old_acl = acl;
407 
408                 error = posix_acl_update_mode(inode, &mode, &acl);
409 
410                 if (error)
411                         goto out_release;
412                 if (!acl)
413                         posix_acl_release(old_acl);
414 
415                 error = xfs_set_mode(inode, mode);
416                 if (error)
417                         goto out_release;
418         }
419 
420  set_acl:
421         error = xfs_set_acl(inode, type, acl);
422  out_release:
423         posix_acl_release(acl);
424  out:
425         return error;
426 }
427 
428 const struct xattr_handler xfs_xattr_acl_access_handler = {
429         .prefix = POSIX_ACL_XATTR_ACCESS,
430         .flags  = ACL_TYPE_ACCESS,
431         .get    = xfs_xattr_acl_get,
432         .set    = xfs_xattr_acl_set,
433 };
434 
435 const struct xattr_handler xfs_xattr_acl_default_handler = {
436         .prefix = POSIX_ACL_XATTR_DEFAULT,
437         .flags  = ACL_TYPE_DEFAULT,
438         .get    = xfs_xattr_acl_get,
439         .set    = xfs_xattr_acl_set,
440 };
441 

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