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 static struct xattr_handler *btrfs_xattr_handler_map[] = {
  30         [BTRFS_XATTR_INDEX_USER]                = &btrfs_xattr_user_handler,
  31 #ifdef CONFIG_FS_POSIX_ACL
  32 //      [BTRFS_XATTR_INDEX_POSIX_ACL_ACCESS]    = &btrfs_xattr_acl_access_handler,
  33 //      [BTRFS_XATTR_INDEX_POSIX_ACL_DEFAULT]   = &btrfs_xattr_acl_default_handler,
  34 #endif
  35         [BTRFS_XATTR_INDEX_TRUSTED]             = &btrfs_xattr_trusted_handler,
  36         [BTRFS_XATTR_INDEX_SECURITY]            = &btrfs_xattr_security_handler,
  37 //      [BTRFS_XATTR_INDEX_SYSTEM]              = &btrfs_xattr_system_handler,
  38 };
  39 struct xattr_handler *btrfs_xattr_handlers[] = {
  40         &btrfs_xattr_user_handler,
  41 #ifdef CONFIG_FS_POSIX_ACL
  42 //      &btrfs_xattr_acl_access_handler,
  43 //      &btrfs_xattr_acl_default_handler,
  44 #endif
  45         &btrfs_xattr_trusted_handler,
  46         &btrfs_xattr_security_handler,
  47 //      &btrfs_xattr_system_handler,
  48         NULL,
  49 };
  50
  51 /*
  52  * @param name - the xattr name
  53  * @return - the xattr_handler for the xattr, NULL if its not found
  54  *
  55  * use this with listxattr where we don't already know the type of xattr we
  56  * have
  57  */
  58 static struct xattr_handler *find_btrfs_xattr_handler(struct extent_buffer *l,
  59                                                       unsigned long name_ptr,
  60                                                       u16 name_len)
  61 {
  62         struct xattr_handler *handler = NULL;
  63         int i = 0;
  64
  65         for (handler = btrfs_xattr_handlers[i]; handler != NULL; i++,
  66              handler = btrfs_xattr_handlers[i]) {
  67                 u16 prefix_len = strlen(handler->prefix);
  68
  69                 if (name_len < prefix_len)
  70                         continue;
  71
  72                 if (memcmp_extent_buffer(l, handler->prefix, name_ptr,
  73                                          prefix_len) == 0)
  74                         break;
  75         }
  76
  77         return handler;
  78 }
  79
  80 /*
  81  * @param name_index - the index for the xattr handler
  82  * @return the xattr_handler if we found it, NULL otherwise
  83  *
  84  * use this if we know the type of the xattr already
  85  */
  86 static struct xattr_handler *btrfs_xattr_handler(int name_index)
  87 {
  88         struct xattr_handler *handler = NULL;
  89
  90         if (name_index >= 0 &&
  91             name_index < ARRAY_SIZE(btrfs_xattr_handler_map))
  92                 handler = btrfs_xattr_handler_map[name_index];
  93
  94         return handler;
  95 }
  96
  97 static inline char *get_name(const char *name, int name_index)
  98 {
  99         char *ret = NULL;
 100         struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 101         int prefix_len;
 102
 103         if (!handler)
 104                 return ret;
 105
 106         prefix_len = strlen(handler->prefix);
 107
 108         ret = kmalloc(strlen(name) + prefix_len + 1, GFP_KERNEL);
 109         if (!ret)
 110                 return ret;
 111
 112         memcpy(ret, handler->prefix, prefix_len);
 113         memcpy(ret+prefix_len, name, strlen(name));
 114         ret[prefix_len + strlen(name)] = '\0';
 115
 116         return ret;
 117 }
 118
 119 size_t btrfs_xattr_generic_list(struct inode *inode, char *list,
 120                                 size_t list_size, const char *name,
 121                                 size_t name_len)
 122 {
 123         if (list && (name_len+1) <= list_size) {
 124                 memcpy(list, name, name_len);
 125                 list[name_len] = '\0';
 126         } else
 127                 return -ERANGE;
 128
 129         return name_len+1;
 130 }
 131
 132 ssize_t btrfs_xattr_get(struct inode *inode, int name_index,
 133                         const char *attr_name, void *buffer, size_t size)
 134 {
 135         struct btrfs_dir_item *di;
 136         struct btrfs_root *root = BTRFS_I(inode)->root;
 137         struct btrfs_path *path;
 138         struct extent_buffer *leaf;
 139         struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 140         int ret = 0;
 141         unsigned long data_ptr;
 142         char *name;
 143
 144         if (!handler)
 145                 return -EOPNOTSUPP;
 146         name = get_name(attr_name, name_index);
 147         if (!name)
 148                 return -ENOMEM;
 149
 150         path = btrfs_alloc_path();
 151         if (!path) {
 152                 kfree(name);
 153                 return -ENOMEM;
 154         }
 155
 156         /* lookup the xattr by name */
 157         di = btrfs_lookup_xattr(NULL, root, path, inode->i_ino, name,
 158                                 strlen(name), 0);
 159         if (!di || IS_ERR(di)) {
 160                 ret = -ENODATA;
 161                 goto out;
 162         }
 163
 164         leaf = path->nodes[0];
 165         /* if size is 0, that means we want the size of the attr */
 166         if (!size) {
 167                 ret = btrfs_dir_data_len(leaf, di);
 168                 goto out;
 169         }
 170
 171         /* now get the data out of our dir_item */
 172         if (btrfs_dir_data_len(leaf, di) > size) {
 173                 ret = -ERANGE;
 174                 goto out;
 175         }
 176         data_ptr = (unsigned long)((char *)(di + 1) +
 177                                    btrfs_dir_name_len(leaf, di));
 178         read_extent_buffer(leaf, buffer, data_ptr,
 179                            btrfs_dir_data_len(leaf, di));
 180         ret = btrfs_dir_data_len(leaf, di);
 181
 182 out:
 183         kfree(name);
 184         btrfs_free_path(path);
 185         return ret;
 186 }
 187
 188 int btrfs_xattr_set(struct inode *inode, int name_index,
 189                     const char *attr_name, const void *value, size_t size,
 190                     int flags)
 191 {
 192         struct btrfs_dir_item *di;
 193         struct btrfs_root *root = BTRFS_I(inode)->root;
 194         struct btrfs_trans_handle *trans;
 195         struct btrfs_path *path;
 196         struct xattr_handler *handler = btrfs_xattr_handler(name_index);
 197         char *name;
 198         int ret = 0, mod = 0;
 199         if (!handler)
 200                 return -EOPNOTSUPP;
 201         name = get_name(attr_name, name_index);
 202         if (!name)
 203                 return -ENOMEM;
 204
 205         path = btrfs_alloc_path();
 206         if (!path) {
 207                 kfree(name);
 208                 return -ENOMEM;
 209         }
 210
 211         trans = btrfs_start_transaction(root, 1);
 212         btrfs_set_trans_block_group(trans, inode);
 213
 214         /* first lets see if we already have this xattr */
 215         di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name,
 216                                 strlen(name), -1);
 217         if (IS_ERR(di)) {
 218                 ret = PTR_ERR(di);
 219                 goto out;
 220         }
 221
 222         /* ok we already have this xattr, lets remove it */
 223         if (di) {
 224                 /* if we want create only exit */
 225                 if (flags & XATTR_CREATE) {
 226                         ret = -EEXIST;
 227                         goto out;
 228                 }
 229
 230                 ret = btrfs_delete_one_dir_name(trans, root, path, di);
 231                 if (ret)
 232                         goto out;
 233                 btrfs_release_path(root, path);
 234
 235                 /* if we don't have a value then we are removing the xattr */
 236                 if (!value) {
 237                         mod = 1;
 238                         goto out;
 239                 }
 240         } else if (flags & XATTR_REPLACE) {
 241                 /* we couldn't find the attr to replace, so error out */
 242                 ret = -ENODATA;
 243                 goto out;
 244         }
 245
 246         /* ok we have to create a completely new xattr */
 247         ret = btrfs_insert_xattr_item(trans, root, name, strlen(name),
 248                                       value, size, inode->i_ino);
 249         if (ret)
 250                 goto out;
 251         mod = 1;
 252
 253 out:
 254         if (mod) {
 255                 inode->i_ctime = CURRENT_TIME;
 256                 ret = btrfs_update_inode(trans, root, inode);
 257         }
 258
 259         btrfs_end_transaction(trans, root);
 260         kfree(name);
 261         btrfs_free_path(path);
 262
 263         return ret;
 264 }
 265
 266 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size)
 267 {
 268         struct btrfs_key key, found_key;
 269         struct inode *inode = dentry->d_inode;
 270         struct btrfs_root *root = BTRFS_I(inode)->root;
 271         struct btrfs_path *path;
 272         struct btrfs_item *item;
 273         struct extent_buffer *leaf;
 274         struct btrfs_dir_item *di;
 275         struct xattr_handler *handler;
 276         int ret = 0, slot, advance;
 277         size_t total_size = 0, size_left = size, written;
 278         unsigned long name_ptr;
 279         char *name;
 280         u32 nritems;
 281
 282         /*
 283          * ok we want all objects associated with this id.
 284          * NOTE: we set key.offset = 0; because we want to start with the
 285          * first xattr that we find and walk forward
 286          */
 287         key.objectid = inode->i_ino;
 288         btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
 289         key.offset = 0;
 290
 291         path = btrfs_alloc_path();
 292         if (!path)
 293                 return -ENOMEM;
 294         path->reada = 2;
 295
 296         /* search for our xattrs */
 297         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 298         if (ret < 0)
 299                 goto err;
 300         ret = 0;
 301         advance = 0;
 302         while (1) {
 303                 leaf = path->nodes[0];
 304                 nritems = btrfs_header_nritems(leaf);
 305                 slot = path->slots[0];
 306
 307                 /* this is where we start walking through the path */
 308                 if (advance || slot >= nritems) {
 309                         /*
 310                          * if we've reached the last slot in this leaf we need
 311                          * to go to the next leaf and reset everything
 312                          */
 313                         if (slot >= nritems-1) {
 314                                 ret = btrfs_next_leaf(root, path);
 315                                 if (ret)
 316                                         break;
 317                                 leaf = path->nodes[0];
 318                                 nritems = btrfs_header_nritems(leaf);
 319                                 slot = path->slots[0];
 320                         } else {
 321                                 /*
 322                                  * just walking through the slots on this leaf
 323                                  */
 324                                 slot++;
 325                                 path->slots[0]++;
 326                         }
 327                 }
 328                 advance = 1;
 329
 330                 item = btrfs_item_nr(leaf, slot);
 331                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
 332
 333                 /* check to make sure this item is what we want */
 334                 if (found_key.objectid != key.objectid)
 335                         break;
 336                 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY)
 337                         break;
 338
 339                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 340
 341                 total_size += btrfs_dir_name_len(leaf, di)+1;
 342
 343                 /* we are just looking for how big our buffer needs to be */
 344                 if (!size)
 345                         continue;
 346
 347                 /* find our handler for this xattr */
 348                 name_ptr = (unsigned long)(di + 1);
 349                 handler = find_btrfs_xattr_handler(leaf, name_ptr,
 350                                                    btrfs_dir_name_len(leaf, di));
 351                 if (!handler) {
 352                         printk(KERN_ERR "btrfs: unsupported xattr found\n");
 353                         continue;
 354                 }
 355
 356                 name = kmalloc(btrfs_dir_name_len(leaf, di), GFP_KERNEL);
 357                 read_extent_buffer(leaf, name, name_ptr,
 358                                    btrfs_dir_name_len(leaf, di));
 359
 360                 /* call the list function associated with this xattr */
 361                 written = handler->list(inode, buffer, size_left, name,
 362                                         btrfs_dir_name_len(leaf, di));
 363                 kfree(name);
 364
 365                 if (written < 0) {
 366                         ret = -ERANGE;
 367                         break;
 368                 }
 369
 370                 size_left -= written;
 371                 buffer += written;
 372         }
 373         ret = total_size;
 374
 375 err:
 376         btrfs_free_path(path);
 377
 378         return ret;
 379 }
 380
 381 /*
 382  * Handler functions
 383  */
 384 #define BTRFS_XATTR_SETGET_FUNCS(name, index)                           \
 385 static int btrfs_xattr_##name##_get(struct inode *inode,                \
 386                                     const char *name, void *value,      \
 387                                     size_t size)                        \
 388 {                                                                       \
 389         if (*name == '\0')                                              \
 390                 return -EINVAL;                                         \
 391         return btrfs_xattr_get(inode, index, name, value, size);        \
 392 }                                                                       \
 393 static int btrfs_xattr_##name##_set(struct inode *inode,                \
 394                                     const char *name, const void *value,\
 395                                     size_t size, int flags)             \
 396 {                                                                       \
 397         if (*name == '\0')                                              \
 398                 return -EINVAL;                                         \
 399         return btrfs_xattr_set(inode, index, name, value, size, flags); \
 400 }
 401
 402 BTRFS_XATTR_SETGET_FUNCS(security, BTRFS_XATTR_INDEX_SECURITY);
 403 BTRFS_XATTR_SETGET_FUNCS(system, BTRFS_XATTR_INDEX_SYSTEM);
 404 BTRFS_XATTR_SETGET_FUNCS(user, BTRFS_XATTR_INDEX_USER);
 405 BTRFS_XATTR_SETGET_FUNCS(trusted, BTRFS_XATTR_INDEX_TRUSTED);
 406
 407 struct xattr_handler btrfs_xattr_security_handler = {
 408         .prefix = XATTR_SECURITY_PREFIX,
 409         .list   = btrfs_xattr_generic_list,
 410         .get    = btrfs_xattr_security_get,
 411         .set    = btrfs_xattr_security_set,
 412 };
 413
 414 struct xattr_handler btrfs_xattr_system_handler = {
 415         .prefix = XATTR_SYSTEM_PREFIX,
 416         .list   = btrfs_xattr_generic_list,
 417         .get    = btrfs_xattr_system_get,
 418         .set    = btrfs_xattr_system_set,
 419 };
 420
 421 struct xattr_handler btrfs_xattr_user_handler = {
 422         .prefix = XATTR_USER_PREFIX,
 423         .list   = btrfs_xattr_generic_list,
 424         .get    = btrfs_xattr_user_get,
 425         .set    = btrfs_xattr_user_set,
 426 };
 427
 428 struct xattr_handler btrfs_xattr_trusted_handler = {
 429         .prefix = XATTR_TRUSTED_PREFIX,
 430         .list   = btrfs_xattr_generic_list,
 431         .get    = btrfs_xattr_trusted_get,
 432         .set    = btrfs_xattr_trusted_set,
 433 };