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