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 <linux/posix_acl_xattr.h> 26 #include "ctree.h" 27 #include "btrfs_inode.h" 28 #include "transaction.h" 29 #include "xattr.h" 30 #include "disk-io.h" 31 #include "props.h" 32 #include "locking.h" 33 34 35 ssize_t __btrfs_getxattr(struct inode *inode, const char *name, 36 void *buffer, size_t size) 37 { 38 struct btrfs_dir_item *di; 39 struct btrfs_root *root = BTRFS_I(inode)->root; 40 struct btrfs_path *path; 41 struct extent_buffer *leaf; 42 int ret = 0; 43 unsigned long data_ptr; 44 45 path = btrfs_alloc_path(); 46 if (!path) 47 return -ENOMEM; 48 49 /* lookup the xattr by name */ 50 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)), 51 name, strlen(name), 0); 52 if (!di) { 53 ret = -ENODATA; 54 goto out; 55 } else if (IS_ERR(di)) { 56 ret = PTR_ERR(di); 57 goto out; 58 } 59 60 leaf = path->nodes[0]; 61 /* if size is 0, that means we want the size of the attr */ 62 if (!size) { 63 ret = btrfs_dir_data_len(leaf, di); 64 goto out; 65 } 66 67 /* now get the data out of our dir_item */ 68 if (btrfs_dir_data_len(leaf, di) > size) { 69 ret = -ERANGE; 70 goto out; 71 } 72 73 /* 74 * The way things are packed into the leaf is like this 75 * |struct btrfs_dir_item|name|data| 76 * where name is the xattr name, so security.foo, and data is the 77 * content of the xattr. data_ptr points to the location in memory 78 * where the data starts in the in memory leaf 79 */ 80 data_ptr = (unsigned long)((char *)(di + 1) + 81 btrfs_dir_name_len(leaf, di)); 82 read_extent_buffer(leaf, buffer, data_ptr, 83 btrfs_dir_data_len(leaf, di)); 84 ret = btrfs_dir_data_len(leaf, di); 85 86 out: 87 btrfs_free_path(path); 88 return ret; 89 } 90 91 static int do_setxattr(struct btrfs_trans_handle *trans, 92 struct inode *inode, const char *name, 93 const void *value, size_t size, int flags) 94 { 95 struct btrfs_dir_item *di = NULL; 96 struct btrfs_root *root = BTRFS_I(inode)->root; 97 struct btrfs_fs_info *fs_info = root->fs_info; 98 struct btrfs_path *path; 99 size_t name_len = strlen(name); 100 int ret = 0; 101 102 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) 103 return -ENOSPC; 104 105 path = btrfs_alloc_path(); 106 if (!path) 107 return -ENOMEM; 108 path->skip_release_on_error = 1; 109 110 if (!value) { 111 di = btrfs_lookup_xattr(trans, root, path, 112 btrfs_ino(BTRFS_I(inode)), name, name_len, -1); 113 if (!di && (flags & XATTR_REPLACE)) 114 ret = -ENODATA; 115 else if (IS_ERR(di)) 116 ret = PTR_ERR(di); 117 else if (di) 118 ret = btrfs_delete_one_dir_name(trans, root, path, di); 119 goto out; 120 } 121 122 /* 123 * For a replace we can't just do the insert blindly. 124 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 125 * doesn't exist. If it exists, fall down below to the insert/replace 126 * path - we can't race with a concurrent xattr delete, because the VFS 127 * locks the inode's i_mutex before calling setxattr or removexattr. 128 */ 129 if (flags & XATTR_REPLACE) { 130 ASSERT(inode_is_locked(inode)); 131 di = btrfs_lookup_xattr(NULL, root, path, 132 btrfs_ino(BTRFS_I(inode)), name, name_len, 0); 133 if (!di) 134 ret = -ENODATA; 135 else if (IS_ERR(di)) 136 ret = PTR_ERR(di); 137 if (ret) 138 goto out; 139 btrfs_release_path(path); 140 di = NULL; 141 } 142 143 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), 144 name, name_len, value, size); 145 if (ret == -EOVERFLOW) { 146 /* 147 * We have an existing item in a leaf, split_leaf couldn't 148 * expand it. That item might have or not a dir_item that 149 * matches our target xattr, so lets check. 150 */ 151 ret = 0; 152 btrfs_assert_tree_locked(path->nodes[0]); 153 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 154 if (!di && !(flags & XATTR_REPLACE)) { 155 ret = -ENOSPC; 156 goto out; 157 } 158 } else if (ret == -EEXIST) { 159 ret = 0; 160 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 161 ASSERT(di); /* logic error */ 162 } else if (ret) { 163 goto out; 164 } 165 166 if (di && (flags & XATTR_CREATE)) { 167 ret = -EEXIST; 168 goto out; 169 } 170 171 if (di) { 172 /* 173 * We're doing a replace, and it must be atomic, that is, at 174 * any point in time we have either the old or the new xattr 175 * value in the tree. We don't want readers (getxattr and 176 * listxattrs) to miss a value, this is specially important 177 * for ACLs. 178 */ 179 const int slot = path->slots[0]; 180 struct extent_buffer *leaf = path->nodes[0]; 181 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 182 const u32 item_size = btrfs_item_size_nr(leaf, slot); 183 const u32 data_size = sizeof(*di) + name_len + size; 184 struct btrfs_item *item; 185 unsigned long data_ptr; 186 char *ptr; 187 188 if (size > old_data_len) { 189 if (btrfs_leaf_free_space(fs_info, leaf) < 190 (size - old_data_len)) { 191 ret = -ENOSPC; 192 goto out; 193 } 194 } 195 196 if (old_data_len + name_len + sizeof(*di) == item_size) { 197 /* No other xattrs packed in the same leaf item. */ 198 if (size > old_data_len) 199 btrfs_extend_item(fs_info, path, 200 size - old_data_len); 201 else if (size < old_data_len) 202 btrfs_truncate_item(fs_info, path, 203 data_size, 1); 204 } else { 205 /* There are other xattrs packed in the same item. */ 206 ret = btrfs_delete_one_dir_name(trans, root, path, di); 207 if (ret) 208 goto out; 209 btrfs_extend_item(fs_info, path, data_size); 210 } 211 212 item = btrfs_item_nr(slot); 213 ptr = btrfs_item_ptr(leaf, slot, char); 214 ptr += btrfs_item_size(leaf, item) - data_size; 215 di = (struct btrfs_dir_item *)ptr; 216 btrfs_set_dir_data_len(leaf, di, size); 217 data_ptr = ((unsigned long)(di + 1)) + name_len; 218 write_extent_buffer(leaf, value, data_ptr, size); 219 btrfs_mark_buffer_dirty(leaf); 220 } else { 221 /* 222 * Insert, and we had space for the xattr, so path->slots[0] is 223 * where our xattr dir_item is and btrfs_insert_xattr_item() 224 * filled it. 225 */ 226 } 227 out: 228 btrfs_free_path(path); 229 return ret; 230 } 231 232 /* 233 * @value: "" makes the attribute to empty, NULL removes it 234 */ 235 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 236 struct inode *inode, const char *name, 237 const void *value, size_t size, int flags) 238 { 239 struct btrfs_root *root = BTRFS_I(inode)->root; 240 int ret; 241 242 if (btrfs_root_readonly(root)) 243 return -EROFS; 244 245 if (trans) 246 return do_setxattr(trans, inode, name, value, size, flags); 247 248 trans = btrfs_start_transaction(root, 2); 249 if (IS_ERR(trans)) 250 return PTR_ERR(trans); 251 252 ret = do_setxattr(trans, inode, name, value, size, flags); 253 if (ret) 254 goto out; 255 256 inode_inc_iversion(inode); 257 inode->i_ctime = current_time(inode); 258 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 259 ret = btrfs_update_inode(trans, root, inode); 260 BUG_ON(ret); 261 out: 262 btrfs_end_transaction(trans); 263 return ret; 264 } 265 266 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 267 { 268 struct btrfs_key key; 269 struct inode *inode = d_inode(dentry); 270 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 271 struct btrfs_root *root = BTRFS_I(inode)->root; 272 struct btrfs_path *path; 273 int ret = 0; 274 size_t total_size = 0, size_left = size; 275 276 /* 277 * ok we want all objects associated with this id. 278 * NOTE: we set key.offset = 0; because we want to start with the 279 * first xattr that we find and walk forward 280 */ 281 key.objectid = btrfs_ino(BTRFS_I(inode)); 282 key.type = BTRFS_XATTR_ITEM_KEY; 283 key.offset = 0; 284 285 path = btrfs_alloc_path(); 286 if (!path) 287 return -ENOMEM; 288 path->reada = READA_FORWARD; 289 290 /* search for our xattrs */ 291 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 292 if (ret < 0) 293 goto err; 294 295 while (1) { 296 struct extent_buffer *leaf; 297 int slot; 298 struct btrfs_dir_item *di; 299 struct btrfs_key found_key; 300 u32 item_size; 301 u32 cur; 302 303 leaf = path->nodes[0]; 304 slot = path->slots[0]; 305 306 /* this is where we start walking through the path */ 307 if (slot >= btrfs_header_nritems(leaf)) { 308 /* 309 * if we've reached the last slot in this leaf we need 310 * to go to the next leaf and reset everything 311 */ 312 ret = btrfs_next_leaf(root, path); 313 if (ret < 0) 314 goto err; 315 else if (ret > 0) 316 break; 317 continue; 318 } 319 320 btrfs_item_key_to_cpu(leaf, &found_key, slot); 321 322 /* check to make sure this item is what we want */ 323 if (found_key.objectid != key.objectid) 324 break; 325 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 326 break; 327 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 328 goto next_item; 329 330 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 331 item_size = btrfs_item_size_nr(leaf, slot); 332 cur = 0; 333 while (cur < item_size) { 334 u16 name_len = btrfs_dir_name_len(leaf, di); 335 u16 data_len = btrfs_dir_data_len(leaf, di); 336 u32 this_len = sizeof(*di) + name_len + data_len; 337 unsigned long name_ptr = (unsigned long)(di + 1); 338 339 if (verify_dir_item(fs_info, leaf, di)) { 340 ret = -EIO; 341 goto err; 342 } 343 344 total_size += name_len + 1; 345 /* 346 * We are just looking for how big our buffer needs to 347 * be. 348 */ 349 if (!size) 350 goto next; 351 352 if (!buffer || (name_len + 1) > size_left) { 353 ret = -ERANGE; 354 goto err; 355 } 356 357 read_extent_buffer(leaf, buffer, name_ptr, name_len); 358 buffer[name_len] = '\0'; 359 360 size_left -= name_len + 1; 361 buffer += name_len + 1; 362 next: 363 cur += this_len; 364 di = (struct btrfs_dir_item *)((char *)di + this_len); 365 } 366 next_item: 367 path->slots[0]++; 368 } 369 ret = total_size; 370 371 err: 372 btrfs_free_path(path); 373 374 return ret; 375 } 376 377 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 378 struct dentry *unused, struct inode *inode, 379 const char *name, void *buffer, size_t size) 380 { 381 name = xattr_full_name(handler, name); 382 return __btrfs_getxattr(inode, name, buffer, size); 383 } 384 385 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 386 struct dentry *unused, struct inode *inode, 387 const char *name, const void *buffer, 388 size_t size, int flags) 389 { 390 name = xattr_full_name(handler, name); 391 return __btrfs_setxattr(NULL, inode, name, buffer, size, flags); 392 } 393 394 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 395 struct dentry *unused, struct inode *inode, 396 const char *name, const void *value, 397 size_t size, int flags) 398 { 399 name = xattr_full_name(handler, name); 400 return btrfs_set_prop(inode, name, value, size, flags); 401 } 402 403 static const struct xattr_handler btrfs_security_xattr_handler = { 404 .prefix = XATTR_SECURITY_PREFIX, 405 .get = btrfs_xattr_handler_get, 406 .set = btrfs_xattr_handler_set, 407 }; 408 409 static const struct xattr_handler btrfs_trusted_xattr_handler = { 410 .prefix = XATTR_TRUSTED_PREFIX, 411 .get = btrfs_xattr_handler_get, 412 .set = btrfs_xattr_handler_set, 413 }; 414 415 static const struct xattr_handler btrfs_user_xattr_handler = { 416 .prefix = XATTR_USER_PREFIX, 417 .get = btrfs_xattr_handler_get, 418 .set = btrfs_xattr_handler_set, 419 }; 420 421 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 422 .prefix = XATTR_BTRFS_PREFIX, 423 .get = btrfs_xattr_handler_get, 424 .set = btrfs_xattr_handler_set_prop, 425 }; 426 427 const struct xattr_handler *btrfs_xattr_handlers[] = { 428 &btrfs_security_xattr_handler, 429 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 430 &posix_acl_access_xattr_handler, 431 &posix_acl_default_xattr_handler, 432 #endif 433 &btrfs_trusted_xattr_handler, 434 &btrfs_user_xattr_handler, 435 &btrfs_btrfs_xattr_handler, 436 NULL, 437 }; 438 439 static int btrfs_initxattrs(struct inode *inode, 440 const struct xattr *xattr_array, void *fs_info) 441 { 442 const struct xattr *xattr; 443 struct btrfs_trans_handle *trans = fs_info; 444 char *name; 445 int err = 0; 446 447 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 448 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 449 strlen(xattr->name) + 1, GFP_KERNEL); 450 if (!name) { 451 err = -ENOMEM; 452 break; 453 } 454 strcpy(name, XATTR_SECURITY_PREFIX); 455 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 456 err = __btrfs_setxattr(trans, inode, name, 457 xattr->value, xattr->value_len, 0); 458 kfree(name); 459 if (err < 0) 460 break; 461 } 462 return err; 463 } 464 465 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 466 struct inode *inode, struct inode *dir, 467 const struct qstr *qstr) 468 { 469 return security_inode_init_security(inode, dir, qstr, 470 &btrfs_initxattrs, trans); 471 } 472