fs/btrfs/acl.c

   1 /*
   2  * Copyright (C) 2007 Red Hat.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/string.h>
  21 #include <linux/xattr.h>
  22 #include <linux/posix_acl_xattr.h>
  23 #include <linux/posix_acl.h>
  24 #include <linux/sched.h>
  25
  26 #include "ctree.h"
  27 #include "btrfs_inode.h"
  28 #include "xattr.h"
  29
  30 #ifdef CONFIG_FS_POSIX_ACL
  31
  32 static void btrfs_update_cached_acl(struct inode *inode,
  33                                     struct posix_acl **p_acl,
  34                                     struct posix_acl *acl)
  35 {
  36         spin_lock(&inode->i_lock);
  37         if (*p_acl && *p_acl != BTRFS_ACL_NOT_CACHED)
  38                 posix_acl_release(*p_acl);
  39         *p_acl = posix_acl_dup(acl);
  40         spin_unlock(&inode->i_lock);
  41 }
  42
  43 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  44 {
  45         int size;
  46         const char *name;
  47         char *value = NULL;
  48         struct posix_acl *acl = NULL, **p_acl;
  49
  50         switch (type) {
  51         case ACL_TYPE_ACCESS:
  52                 name = POSIX_ACL_XATTR_ACCESS;
  53                 p_acl = &BTRFS_I(inode)->i_acl;
  54                 break;
  55         case ACL_TYPE_DEFAULT:
  56                 name = POSIX_ACL_XATTR_DEFAULT;
  57                 p_acl = &BTRFS_I(inode)->i_default_acl;
  58                 break;
  59         default:
  60                 return ERR_PTR(-EINVAL);
  61         }
  62
  63         spin_lock(&inode->i_lock);
  64         if (*p_acl != BTRFS_ACL_NOT_CACHED)
  65                 acl = posix_acl_dup(*p_acl);
  66         spin_unlock(&inode->i_lock);
  67
  68         if (acl)
  69                 return acl;
  70
  71
  72         size = __btrfs_getxattr(inode, name, "", 0);
  73         if (size > 0) {
  74                 value = kzalloc(size, GFP_NOFS);
  75                 if (!value)
  76                         return ERR_PTR(-ENOMEM);
  77                 size = __btrfs_getxattr(inode, name, value, size);
  78                 if (size > 0) {
  79                         acl = posix_acl_from_xattr(value, size);
  80                         btrfs_update_cached_acl(inode, p_acl, acl);
  81                 }
  82                 kfree(value);
  83         } else if (size == -ENOENT) {
  84                 acl = NULL;
  85                 btrfs_update_cached_acl(inode, p_acl, acl);
  86         }
  87
  88         return acl;
  89 }
  90
  91 static int btrfs_xattr_get_acl(struct inode *inode, int type,
  92                                void *value, size_t size)
  93 {
  94         struct posix_acl *acl;
  95         int ret = 0;
  96
  97         acl = btrfs_get_acl(inode, type);
  98
  99         if (IS_ERR(acl))
 100                 return PTR_ERR(acl);
 101         if (acl == NULL)
 102                 return -ENODATA;
 103         ret = posix_acl_to_xattr(acl, value, size);
 104         posix_acl_release(acl);
 105
 106         return ret;
 107 }
 108
 109 /*
 110  * Needs to be called with fs_mutex held
 111  */
 112 static int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 113 {
 114         int ret, size = 0;
 115         const char *name;
 116         struct posix_acl **p_acl;
 117         char *value = NULL;
 118         mode_t mode;
 119
 120         if (acl) {
 121                 ret = posix_acl_valid(acl);
 122                 if (ret < 0)
 123                         return ret;
 124                 ret = 0;
 125         }
 126
 127         switch (type) {
 128         case ACL_TYPE_ACCESS:
 129                 mode = inode->i_mode;
 130                 ret = posix_acl_equiv_mode(acl, &mode);
 131                 if (ret < 0)
 132                         return ret;
 133                 ret = 0;
 134                 inode->i_mode = mode;
 135                 name = POSIX_ACL_XATTR_ACCESS;
 136                 p_acl = &BTRFS_I(inode)->i_acl;
 137                 break;
 138         case ACL_TYPE_DEFAULT:
 139                 if (!S_ISDIR(inode->i_mode))
 140                         return acl ? -EINVAL : 0;
 141                 name = POSIX_ACL_XATTR_DEFAULT;
 142                 p_acl = &BTRFS_I(inode)->i_default_acl;
 143                 break;
 144         default:
 145                 return -EINVAL;
 146         }
 147
 148         if (acl) {
 149                 size = posix_acl_xattr_size(acl->a_count);
 150                 value = kmalloc(size, GFP_NOFS);
 151                 if (!value) {
 152                         ret = -ENOMEM;
 153                         goto out;
 154                 }
 155
 156                 ret = posix_acl_to_xattr(acl, value, size);
 157                 if (ret < 0)
 158                         goto out;
 159         }
 160
 161         ret = __btrfs_setxattr(inode, name, value, size, 0);
 162
 163 out:
 164         if (value)
 165                 kfree(value);
 166
 167         if (!ret)
 168                 btrfs_update_cached_acl(inode, p_acl, acl);
 169
 170         return ret;
 171 }
 172
 173 static int btrfs_xattr_set_acl(struct inode *inode, int type,
 174                                const void *value, size_t size)
 175 {
 176         int ret = 0;
 177         struct posix_acl *acl = NULL;
 178
 179         if (value) {
 180                 acl = posix_acl_from_xattr(value, size);
 181                 if (acl == NULL) {
 182                         value = NULL;
 183                         size = 0;
 184                 } else if (IS_ERR(acl)) {
 185                         return PTR_ERR(acl);
 186                 }
 187         }
 188
 189         ret = btrfs_set_acl(inode, acl, type);
 190
 191         posix_acl_release(acl);
 192
 193         return ret;
 194 }
 195
 196
 197 static int btrfs_xattr_acl_access_get(struct inode *inode, const char *name,
 198                                       void *value, size_t size)
 199 {
 200         return btrfs_xattr_get_acl(inode, ACL_TYPE_ACCESS, value, size);
 201 }
 202
 203 static int btrfs_xattr_acl_access_set(struct inode *inode, const char *name,
 204                                       const void *value, size_t size, int flags)
 205 {
 206         return btrfs_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 207 }
 208
 209 static int btrfs_xattr_acl_default_get(struct inode *inode, const char *name,
 210                                        void *value, size_t size)
 211 {
 212         return btrfs_xattr_get_acl(inode, ACL_TYPE_DEFAULT, value, size);
 213 }
 214
 215 static int btrfs_xattr_acl_default_set(struct inode *inode, const char *name,
 216                                        const void *value, size_t size, int flags)
 217 {
 218         return btrfs_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 219 }
 220
 221 int btrfs_check_acl(struct inode *inode, int mask)
 222 {
 223         struct posix_acl *acl;
 224         int error = -EAGAIN;
 225
 226         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 227
 228         if (IS_ERR(acl))
 229                 return PTR_ERR(acl);
 230         if (acl) {
 231                 error = posix_acl_permission(inode, acl, mask);
 232                 posix_acl_release(acl);
 233         }
 234
 235         return error;
 236 }
 237
 238 /*
 239  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 240  * stuff has been fixed to work with that.  If the locking stuff changes, we
 241  * need to re-evaluate the acl locking stuff.
 242  */
 243 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 244 {
 245         struct posix_acl *acl = NULL;
 246         int ret = 0;
 247
 248         /* this happens with subvols */
 249         if (!dir)
 250                 return 0;
 251
 252         if (!S_ISLNK(inode->i_mode)) {
 253                 if (IS_POSIXACL(dir)) {
 254                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 255                         if (IS_ERR(acl))
 256                                 return PTR_ERR(acl);
 257                 }
 258
 259                 if (!acl)
 260                         inode->i_mode &= ~current->fs->umask;
 261         }
 262
 263         if (IS_POSIXACL(dir) && acl) {
 264                 struct posix_acl *clone;
 265                 mode_t mode;
 266
 267                 if (S_ISDIR(inode->i_mode)) {
 268                         ret = btrfs_set_acl(inode, acl, ACL_TYPE_DEFAULT);
 269                         if (ret)
 270                                 goto failed;
 271                 }
 272                 clone = posix_acl_clone(acl, GFP_NOFS);
 273                 ret = -ENOMEM;
 274                 if (!clone)
 275                         goto failed;
 276
 277                 mode = inode->i_mode;
 278                 ret = posix_acl_create_masq(clone, &mode);
 279                 if (ret >= 0) {
 280                         inode->i_mode = mode;
 281                         if (ret > 0) {
 282                                 /* we need an acl */
 283                                 ret = btrfs_set_acl(inode, clone,
 284                                                     ACL_TYPE_ACCESS);
 285                         }
 286                 }
 287         }
 288 failed:
 289         posix_acl_release(acl);
 290
 291         return ret;
 292 }
 293
 294 int btrfs_acl_chmod(struct inode *inode)
 295 {
 296         struct posix_acl *acl, *clone;
 297         int ret = 0;
 298
 299         if (S_ISLNK(inode->i_mode))
 300                 return -EOPNOTSUPP;
 301
 302         if (!IS_POSIXACL(inode))
 303                 return 0;
 304
 305         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 306         if (IS_ERR(acl) || !acl)
 307                 return PTR_ERR(acl);
 308
 309         clone = posix_acl_clone(acl, GFP_KERNEL);
 310         posix_acl_release(acl);
 311         if (!clone)
 312                 return -ENOMEM;
 313
 314         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 315         if (!ret)
 316                 ret = btrfs_set_acl(inode, clone, ACL_TYPE_ACCESS);
 317
 318         posix_acl_release(clone);
 319
 320         return ret;
 321 }
 322
 323 struct xattr_handler btrfs_xattr_acl_default_handler = {
 324         .prefix = POSIX_ACL_XATTR_DEFAULT,
 325         .get    = btrfs_xattr_acl_default_get,
 326         .set    = btrfs_xattr_acl_default_set,
 327 };
 328
 329 struct xattr_handler btrfs_xattr_acl_access_handler = {
 330         .prefix = POSIX_ACL_XATTR_ACCESS,
 331         .get    = btrfs_xattr_acl_access_get,
 332         .set    = btrfs_xattr_acl_access_set,
 333 };
 334
 335 #else /* CONFIG_FS_POSIX_ACL */
 336
 337 int btrfs_acl_chmod(struct inode *inode)
 338 {
 339         return 0;
 340 }
 341
 342 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 343 {
 344         return 0;
 345 }
 346
 347 int btrfs_check_acl(struct inode *inode, int mask)
 348 {
 349         return 0;
 350 }
 351
 352 #endif /* CONFIG_FS_POSIX_ACL */