fs/btrfs/xattr.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/init.h>
  20 #include <linux/fs.h>
  21 #include <linux/slab.h>
  22 #include <linux/rwsem.h>
  23 #include <linux/xattr.h>
  24 #include <linux/security.h>
  25 #include "ctree.h"
  26 #include "btrfs_inode.h"
  27 #include "transaction.h"
  28 #include "xattr.h"
  29 #include "disk-io.h"
  30
  31
  32 ssize_t __btrfs_getxattr(struct inode *inode, const char *name,
  33                                 void *buffer, size_t size)
  34 {
  35         struct btrfs_dir_item *di;
  36         struct btrfs_root *root = BTRFS_I(inode)->root;
  37         struct btrfs_path *path;
  38         struct extent_buffer *leaf;
  39         int ret = 0;
  40         unsigned long data_ptr;
  41
  42         path = btrfs_alloc_path();
  43         if (!path)
  44                 return -ENOMEM;
  45
  46         /* lookup the xattr by name */
  47         di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
  48                                 strlen(name), 0);
  49         if (!di) {
  50                 ret = -ENODATA;
  51                 goto out;
  52         } else if (IS_ERR(di)) {
  53                 ret = PTR_ERR(di);
  54                 goto out;
  55         }
  56
  57         leaf = path->nodes[0];
  58         /* if size is 0, that means we want the size of the attr */
  59         if (!size) {
  60                 ret = btrfs_dir_data_len(leaf, di);
  61                 goto out;
  62         }
  63
  64         /* now get the data out of our dir_item */
  65         if (btrfs_dir_data_len(leaf, di) > size) {
  66                 ret = -ERANGE;
  67                 goto out;
  68         }
  69
  70         /*
  71          * The way things are packed into the leaf is like this
  72          * |struct btrfs_dir_item|name|data|
  73          * where name is the xattr name, so security.foo, and data is the
  74          * content of the xattr.  data_ptr points to the location in memory
  75          * where the data starts in the in memory leaf
  76          */
  77         data_ptr = (unsigned long)((char *)(di + 1) +
  78                                    btrfs_dir_name_len(leaf, di));
  79         read_extent_buffer(leaf, buffer, data_ptr,
  80                            btrfs_dir_data_len(leaf, di));
  81         ret = btrfs_dir_data_len(leaf, di);
  82
  83 out:
  84         btrfs_free_path(path);
  85         return ret;
  86 }
  87
  88 static int do_setxattr(struct btrfs_trans_handle *trans,
  89                        struct inode *inode, const char *name,
  90                        const void *value, size_t size, int flags)
  91 {
  92         struct btrfs_dir_item *di;
  93         struct btrfs_root *root = BTRFS_I(inode)->root;
  94         struct btrfs_path *path;
  95         size_t name_len = strlen(name);
  96         int ret = 0;
  97
  98         if (name_len + size > BTRFS_MAX_XATTR_SIZE(root))
  99                 return -ENOSPC;
 100
 101         path = btrfs_alloc_path();
 102         if (!path)
 103                 return -ENOMEM;
 104
 105         /* first lets see if we already have this xattr */
 106         di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
 107                                 strlen(name), -1);
 108         if (IS_ERR(di)) {
 109                 ret = PTR_ERR(di);
 110                 goto out;
 111         }
 112
 113         /* ok we already have this xattr, lets remove it */
 114         if (di) {
 115                 /* if we want create only exit */
 116                 if (flags & XATTR_CREATE) {
 117                         ret = -EEXIST;
 118                         goto out;
 119                 }
 120
 121                 ret = btrfs_delete_one_dir_name(trans, root, path, di);
 122                 BUG_ON(ret);
 123                 btrfs_release_path(root, path);
 124
 125                 /* if we don't have a value then we are removing the xattr */
 126                 if (!value)
 127                         goto out;
 128         } else {
 129                 btrfs_release_path(root, path);
 130
 131                 if (flags & XATTR_REPLACE) {
 132                         /* we couldn't find the attr to replace */
 133                         ret = -ENODATA;
 134                         goto out;
 135                 }
 136         }
 137
 138         /* ok we have to create a completely new xattr */
 139         ret = btrfs_insert_xattr_item(trans, root, path, inode->i_ino,
 140                                       name, name_len, value, size);
 141         BUG_ON(ret);
 142 out:
 143         btrfs_free_path(path);
 144         return ret;
 145 }
 146
 147 int __btrfs_setxattr(struct btrfs_trans_handle *trans,
 148                      struct inode *inode, const char *name,
 149                      const void *value, size_t size, int flags)
 150 {
 151         struct btrfs_root *root = BTRFS_I(inode)->root;
 152         int ret;
 153
 154         if (trans)
 155                 return do_setxattr(trans, inode, name, value, size, flags);
 156
 157         trans = btrfs_start_transaction(root, 2);
 158         if (IS_ERR(trans))
 159                 return PTR_ERR(trans);
 160
 161         btrfs_set_trans_block_group(trans, inode);
 162
 163         ret = do_setxattr(trans, inode, name, value, size, flags);
 164         if (ret)
 165                 goto out;
 166
 167         inode->i_ctime = CURRENT_TIME;
 168         ret = btrfs_update_inode(trans, root, inode);
 169         BUG_ON(ret);
 170 out:
 171         btrfs_end_transaction_throttle(trans, root);
 172         return ret;
 173 }
 174
 175 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 176 {
 177         struct btrfs_key key, found_key;
 178         struct inode *inode = dentry->d_inode;
 179         struct btrfs_root *root = BTRFS_I(inode)->root;
 180         struct btrfs_path *path;
 181         struct btrfs_item *item;
 182         struct extent_buffer *leaf;
 183         struct btrfs_dir_item *di;
 184         int ret = 0, slot, advance;
 185         size_t total_size = 0, size_left = size;
 186         unsigned long name_ptr;
 187         size_t name_len;
 188         u32 nritems;
 189
 190         /*
 191          * ok we want all objects associated with this id.
 192          * NOTE: we set key.offset = 0; because we want to start with the
 193          * first xattr that we find and walk forward
 194          */
 195         key.objectid = inode->i_ino;
 196         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 197         key.offset = 0;
 198
 199         path = btrfs_alloc_path();
 200         if (!path)
 201                 return -ENOMEM;
 202         path->reada = 2;
 203
 204         /* search for our xattrs */
 205         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 206         if (ret < 0)
 207                 goto err;
 208         advance = 0;
 209         while (1) {
 210                 leaf = path->nodes[0];
 211                 nritems = btrfs_header_nritems(leaf);
 212                 slot = path->slots[0];
 213
 214                 /* this is where we start walking through the path */
 215                 if (advance || slot >= nritems) {
 216                         /*
 217                          * if we've reached the last slot in this leaf we need
 218                          * to go to the next leaf and reset everything
 219                          */
 220                         if (slot >= nritems-1) {
 221                                 ret = btrfs_next_leaf(root, path);
 222                                 if (ret)
 223                                         break;
 224                                 leaf = path->nodes[0];
 225                                 nritems = btrfs_header_nritems(leaf);
 226                                 slot = path->slots[0];
 227                         } else {
 228                                 /*
 229                                  * just walking through the slots on this leaf
 230                                  */
 231                                 slot++;
 232                                 path->slots[0]++;
 233                         }
 234                 }
 235                 advance = 1;
 236
 237                 item = btrfs_item_nr(leaf, slot);
 238                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 239
 240                 /* check to make sure this item is what we want */
 241                 if (found_key.objectid != key.objectid)
 242                         break;
 243                 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
 244                         break;
 245
 246                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 247
 248                 name_len = btrfs_dir_name_len(leaf, di);
 249                 total_size += name_len + 1;
 250
 251                 /* we are just looking for how big our buffer needs to be */
 252                 if (!size)
 253                         continue;
 254
 255                 if (!buffer || (name_len + 1) > size_left) {
 256                         ret = -ERANGE;
 257                         goto err;
 258                 }
 259
 260                 name_ptr = (unsigned long)(di + 1);
 261                 read_extent_buffer(leaf, buffer, name_ptr, name_len);
 262                 buffer[name_len] = '\0';
 263
 264                 size_left -= name_len + 1;
 265                 buffer += name_len + 1;
 266         }
 267         ret = total_size;
 268
 269 err:
 270         btrfs_free_path(path);
 271
 272         return ret;
 273 }
 274
 275 /*
 276  * List of handlers for synthetic system.* attributes.  All real ondisk
 277  * attributes are handled directly.
 278  */
 279 const struct xattr_handler *btrfs_xattr_handlers[] = {
 280 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 281         &btrfs_xattr_acl_access_handler,
 282         &btrfs_xattr_acl_default_handler,
 283 #endif
 284         NULL,
 285 };
 286
 287 /*
 288  * Check if the attribute is in a supported namespace.
 289  *
 290  * This applied after the check for the synthetic attributes in the system
 291  * namespace.
 292  */
 293 static bool btrfs_is_valid_xattr(const char *name)
 294 {
 295         return !strncmp(name, XATTR_SECURITY_PREFIX,
 296                         XATTR_SECURITY_PREFIX_LEN) ||
 297                !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
 298                !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
 299                !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
 300 }
 301
 302 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
 303                        void *buffer, size_t size)
 304 {
 305         /*
 306          * If this is a request for a synthetic attribute in the system.*
 307          * namespace use the generic infrastructure to resolve a handler
 308          * for it via sb->s_xattr.
 309          */
 310         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 311                 return generic_getxattr(dentry, name, buffer, size);
 312
 313         if (!btrfs_is_valid_xattr(name))
 314                 return -EOPNOTSUPP;
 315         return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
 316 }
 317
 318 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 319                    size_t size, int flags)
 320 {
 321         /*
 322          * If this is a request for a synthetic attribute in the system.*
 323          * namespace use the generic infrastructure to resolve a handler
 324          * for it via sb->s_xattr.
 325          */
 326         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 327                 return generic_setxattr(dentry, name, value, size, flags);
 328
 329         if (!btrfs_is_valid_xattr(name))
 330                 return -EOPNOTSUPP;
 331
 332         if (size == 0)
 333                 value = "";  /* empty EA, do not remove */
 334
 335         return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size,
 336                                 flags);
 337 }
 338
 339 int btrfs_removexattr(struct dentry *dentry, const char *name)
 340 {
 341         /*
 342          * If this is a request for a synthetic attribute in the system.*
 343          * namespace use the generic infrastructure to resolve a handler
 344          * for it via sb->s_xattr.
 345          */
 346         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 347                 return generic_removexattr(dentry, name);
 348
 349         if (!btrfs_is_valid_xattr(name))
 350                 return -EOPNOTSUPP;
 351
 352         return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0,
 353                                 XATTR_REPLACE);
 354 }
 355
 356 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans,
 357                               struct inode *inode, struct inode *dir)
 358 {
 359         int err;
 360         size_t len;
 361         void *value;
 362         char *suffix;
 363         char *name;
 364
 365         err = security_inode_init_security(inode, dir, &suffix, &value, &len);
 366         if (err) {
 367                 if (err == -EOPNOTSUPP)
 368                         return 0;
 369                 return err;
 370         }
 371
 372         name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
 373                        GFP_NOFS);
 374         if (!name) {
 375                 err = -ENOMEM;
 376         } else {
 377                 strcpy(name, XATTR_SECURITY_PREFIX);
 378                 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
 379                 err = __btrfs_setxattr(trans, inode, name, value, len, 0);
 380                 kfree(name);
 381         }
 382
 383         kfree(suffix);
 384         kfree(value);
 385         return err;
 386 }