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 int __btrfs_setxattr(struct inode *inode, const char *name,
  89                             const void *value, size_t size, int flags)
  90 {
  91         struct btrfs_dir_item *di;
  92         struct btrfs_root *root = BTRFS_I(inode)->root;
  93         struct btrfs_trans_handle *trans;
  94         struct btrfs_path *path;
  95         int ret = 0, mod = 0;
  96
  97         path = btrfs_alloc_path();
  98         if (!path)
  99                 return -ENOMEM;
 100
 101         trans = btrfs_join_transaction(root, 1);
 102         btrfs_set_trans_block_group(trans, inode);
 103
 104         /* first lets see if we already have this xattr */
 105         di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
 106                                 strlen(name), -1);
 107         if (IS_ERR(di)) {
 108                 ret = PTR_ERR(di);
 109                 goto out;
 110         }
 111
 112         /* ok we already have this xattr, lets remove it */
 113         if (di) {
 114                 /* if we want create only exit */
 115                 if (flags & XATTR_CREATE) {
 116                         ret = -EEXIST;
 117                         goto out;
 118                 }
 119
 120                 ret = btrfs_delete_one_dir_name(trans, root, path, di);
 121                 if (ret)
 122                         goto out;
 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                         mod = 1;
 128                         goto out;
 129                 }
 130         } else {
 131                 btrfs_release_path(root, path);
 132
 133                 if (flags & XATTR_REPLACE) {
 134                         /* we couldn't find the attr to replace */
 135                         ret = -ENODATA;
 136                         goto out;
 137                 }
 138         }
 139
 140         /* ok we have to create a completely new xattr */
 141         ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
 142                                       value, size, inode->i_ino);
 143         if (ret)
 144                 goto out;
 145         mod = 1;
 146
 147 out:
 148         if (mod) {
 149                 inode->i_ctime = CURRENT_TIME;
 150                 ret = btrfs_update_inode(trans, root, inode);
 151         }
 152
 153         btrfs_end_transaction(trans, root);
 154         btrfs_free_path(path);
 155         return ret;
 156 }
 157
 158 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 159 {
 160         struct btrfs_key key, found_key;
 161         struct inode *inode = dentry->d_inode;
 162         struct btrfs_root *root = BTRFS_I(inode)->root;
 163         struct btrfs_path *path;
 164         struct btrfs_item *item;
 165         struct extent_buffer *leaf;
 166         struct btrfs_dir_item *di;
 167         int ret = 0, slot, advance;
 168         size_t total_size = 0, size_left = size;
 169         unsigned long name_ptr;
 170         size_t name_len;
 171         u32 nritems;
 172
 173         /*
 174          * ok we want all objects associated with this id.
 175          * NOTE: we set key.offset = 0; because we want to start with the
 176          * first xattr that we find and walk forward
 177          */
 178         key.objectid = inode->i_ino;
 179         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 180         key.offset = 0;
 181
 182         path = btrfs_alloc_path();
 183         if (!path)
 184                 return -ENOMEM;
 185         path->reada = 2;
 186
 187         /* search for our xattrs */
 188         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 189         if (ret < 0)
 190                 goto err;
 191         advance = 0;
 192         while (1) {
 193                 leaf = path->nodes[0];
 194                 nritems = btrfs_header_nritems(leaf);
 195                 slot = path->slots[0];
 196
 197                 /* this is where we start walking through the path */
 198                 if (advance || slot >= nritems) {
 199                         /*
 200                          * if we've reached the last slot in this leaf we need
 201                          * to go to the next leaf and reset everything
 202                          */
 203                         if (slot >= nritems-1) {
 204                                 ret = btrfs_next_leaf(root, path);
 205                                 if (ret)
 206                                         break;
 207                                 leaf = path->nodes[0];
 208                                 nritems = btrfs_header_nritems(leaf);
 209                                 slot = path->slots[0];
 210                         } else {
 211                                 /*
 212                                  * just walking through the slots on this leaf
 213                                  */
 214                                 slot++;
 215                                 path->slots[0]++;
 216                         }
 217                 }
 218                 advance = 1;
 219
 220                 item = btrfs_item_nr(leaf, slot);
 221                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 222
 223                 /* check to make sure this item is what we want */
 224                 if (found_key.objectid != key.objectid)
 225                         break;
 226                 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
 227                         break;
 228
 229                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 230
 231                 name_len = btrfs_dir_name_len(leaf, di);
 232                 total_size += name_len + 1;
 233
 234                 /* we are just looking for how big our buffer needs to be */
 235                 if (!size)
 236                         continue;
 237
 238                 if (!buffer || (name_len + 1) > size_left) {
 239                         ret = -ERANGE;
 240                         goto err;
 241                 }
 242
 243                 name_ptr = (unsigned long)(di + 1);
 244                 read_extent_buffer(leaf, buffer, name_ptr, name_len);
 245                 buffer[name_len] = '\0';
 246
 247                 size_left -= name_len + 1;
 248                 buffer += name_len + 1;
 249         }
 250         ret = total_size;
 251
 252 err:
 253         btrfs_free_path(path);
 254
 255         return ret;
 256 }
 257
 258 /*
 259  * List of handlers for synthetic system.* attributes.  All real ondisk
 260  * attributes are handled directly.
 261  */
 262 struct xattr_handler *btrfs_xattr_handlers[] = {
 263 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 264         &btrfs_xattr_acl_access_handler,
 265         &btrfs_xattr_acl_default_handler,
 266 #endif
 267         NULL,
 268 };
 269
 270 /*
 271  * Check if the attribute is in a supported namespace.
 272  *
 273  * This applied after the check for the synthetic attributes in the system
 274  * namespace.
 275  */
 276 static bool btrfs_is_valid_xattr(const char *name)
 277 {
 278         return !strncmp(name, XATTR_SECURITY_PREFIX,
 279                         XATTR_SECURITY_PREFIX_LEN) ||
 280                !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) ||
 281                !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) ||
 282                !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN);
 283 }
 284
 285 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
 286                        void *buffer, size_t size)
 287 {
 288         /*
 289          * If this is a request for a synthetic attribute in the system.*
 290          * namespace use the generic infrastructure to resolve a handler
 291          * for it via sb->s_xattr.
 292          */
 293         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 294                 return generic_getxattr(dentry, name, buffer, size);
 295
 296         if (!btrfs_is_valid_xattr(name))
 297                 return -EOPNOTSUPP;
 298         return __btrfs_getxattr(dentry->d_inode, name, buffer, size);
 299 }
 300
 301 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
 302                    size_t size, int flags)
 303 {
 304         /*
 305          * If this is a request for a synthetic attribute in the system.*
 306          * namespace use the generic infrastructure to resolve a handler
 307          * for it via sb->s_xattr.
 308          */
 309         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 310                 return generic_setxattr(dentry, name, value, size, flags);
 311
 312         if (!btrfs_is_valid_xattr(name))
 313                 return -EOPNOTSUPP;
 314
 315         if (size == 0)
 316                 value = "";  /* empty EA, do not remove */
 317         return __btrfs_setxattr(dentry->d_inode, name, value, size, flags);
 318 }
 319
 320 int btrfs_removexattr(struct dentry *dentry, const char *name)
 321 {
 322         /*
 323          * If this is a request for a synthetic attribute in the system.*
 324          * namespace use the generic infrastructure to resolve a handler
 325          * for it via sb->s_xattr.
 326          */
 327         if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
 328                 return generic_removexattr(dentry, name);
 329
 330         if (!btrfs_is_valid_xattr(name))
 331                 return -EOPNOTSUPP;
 332         return __btrfs_setxattr(dentry->d_inode, name, NULL, 0, XATTR_REPLACE);
 333 }
 334
 335 int btrfs_xattr_security_init(struct inode *inode, struct inode *dir)
 336 {
 337         int err;
 338         size_t len;
 339         void *value;
 340         char *suffix;
 341         char *name;
 342
 343         err = security_inode_init_security(inode, dir, &suffix, &value, &len);
 344         if (err) {
 345                 if (err == -EOPNOTSUPP)
 346                         return 0;
 347                 return err;
 348         }
 349
 350         name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1,
 351                        GFP_NOFS);
 352         if (!name) {
 353                 err = -ENOMEM;
 354         } else {
 355                 strcpy(name, XATTR_SECURITY_PREFIX);
 356                 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix);
 357                 err = __btrfs_setxattr(inode, name, value, len, 0);
 358                 kfree(name);
 359         }
 360
 361         kfree(suffix);
 362         kfree(value);
 363         return err;
 364 }