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(inode), name, 51 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_path *path; 98 size_t name_len = strlen(name); 99 int ret = 0; 100 101 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root)) 102 return -ENOSPC; 103 104 path = btrfs_alloc_path(); 105 if (!path) 106 return -ENOMEM; 107 path->skip_release_on_error = 1; 108 109 if (!value) { 110 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), 111 name, name_len, -1); 112 if (!di && (flags & XATTR_REPLACE)) 113 ret = -ENODATA; 114 else if (di) 115 ret = btrfs_delete_one_dir_name(trans, root, path, di); 116 goto out; 117 } 118 119 /* 120 * For a replace we can't just do the insert blindly. 121 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 122 * doesn't exist. If it exists, fall down below to the insert/replace 123 * path - we can't race with a concurrent xattr delete, because the VFS 124 * locks the inode's i_mutex before calling setxattr or removexattr. 125 */ 126 if (flags & XATTR_REPLACE) { 127 ASSERT(mutex_is_locked(&inode->i_mutex)); 128 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), 129 name, name_len, 0); 130 if (!di) { 131 ret = -ENODATA; 132 goto out; 133 } 134 btrfs_release_path(path); 135 di = NULL; 136 } 137 138 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), 139 name, name_len, value, size); 140 if (ret == -EOVERFLOW) { 141 /* 142 * We have an existing item in a leaf, split_leaf couldn't 143 * expand it. That item might have or not a dir_item that 144 * matches our target xattr, so lets check. 145 */ 146 ret = 0; 147 btrfs_assert_tree_locked(path->nodes[0]); 148 di = btrfs_match_dir_item_name(root, path, name, name_len); 149 if (!di && !(flags & XATTR_REPLACE)) { 150 ret = -ENOSPC; 151 goto out; 152 } 153 } else if (ret == -EEXIST) { 154 ret = 0; 155 di = btrfs_match_dir_item_name(root, path, name, name_len); 156 ASSERT(di); /* logic error */ 157 } else if (ret) { 158 goto out; 159 } 160 161 if (di && (flags & XATTR_CREATE)) { 162 ret = -EEXIST; 163 goto out; 164 } 165 166 if (di) { 167 /* 168 * We're doing a replace, and it must be atomic, that is, at 169 * any point in time we have either the old or the new xattr 170 * value in the tree. We don't want readers (getxattr and 171 * listxattrs) to miss a value, this is specially important 172 * for ACLs. 173 */ 174 const int slot = path->slots[0]; 175 struct extent_buffer *leaf = path->nodes[0]; 176 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 177 const u32 item_size = btrfs_item_size_nr(leaf, slot); 178 const u32 data_size = sizeof(*di) + name_len + size; 179 struct btrfs_item *item; 180 unsigned long data_ptr; 181 char *ptr; 182 183 if (size > old_data_len) { 184 if (btrfs_leaf_free_space(root, leaf) < 185 (size - old_data_len)) { 186 ret = -ENOSPC; 187 goto out; 188 } 189 } 190 191 if (old_data_len + name_len + sizeof(*di) == item_size) { 192 /* No other xattrs packed in the same leaf item. */ 193 if (size > old_data_len) 194 btrfs_extend_item(root, path, 195 size - old_data_len); 196 else if (size < old_data_len) 197 btrfs_truncate_item(root, path, data_size, 1); 198 } else { 199 /* There are other xattrs packed in the same item. */ 200 ret = btrfs_delete_one_dir_name(trans, root, path, di); 201 if (ret) 202 goto out; 203 btrfs_extend_item(root, path, data_size); 204 } 205 206 item = btrfs_item_nr(slot); 207 ptr = btrfs_item_ptr(leaf, slot, char); 208 ptr += btrfs_item_size(leaf, item) - data_size; 209 di = (struct btrfs_dir_item *)ptr; 210 btrfs_set_dir_data_len(leaf, di, size); 211 data_ptr = ((unsigned long)(di + 1)) + name_len; 212 write_extent_buffer(leaf, value, data_ptr, size); 213 btrfs_mark_buffer_dirty(leaf); 214 } else { 215 /* 216 * Insert, and we had space for the xattr, so path->slots[0] is 217 * where our xattr dir_item is and btrfs_insert_xattr_item() 218 * filled it. 219 */ 220 } 221 out: 222 btrfs_free_path(path); 223 return ret; 224 } 225 226 /* 227 * @value: "" makes the attribute to empty, NULL removes it 228 */ 229 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 230 struct inode *inode, const char *name, 231 const void *value, size_t size, int flags) 232 { 233 struct btrfs_root *root = BTRFS_I(inode)->root; 234 int ret; 235 236 if (trans) 237 return do_setxattr(trans, inode, name, value, size, flags); 238 239 trans = btrfs_start_transaction(root, 2); 240 if (IS_ERR(trans)) 241 return PTR_ERR(trans); 242 243 ret = do_setxattr(trans, inode, name, value, size, flags); 244 if (ret) 245 goto out; 246 247 inode_inc_iversion(inode); 248 inode->i_ctime = CURRENT_TIME; 249 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 250 ret = btrfs_update_inode(trans, root, inode); 251 BUG_ON(ret); 252 out: 253 btrfs_end_transaction(trans, root); 254 return ret; 255 } 256 257 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 258 { 259 struct btrfs_key key, found_key; 260 struct inode *inode = dentry->d_inode; 261 struct btrfs_root *root = BTRFS_I(inode)->root; 262 struct btrfs_path *path; 263 struct extent_buffer *leaf; 264 struct btrfs_dir_item *di; 265 int ret = 0, slot; 266 size_t total_size = 0, size_left = size; 267 unsigned long name_ptr; 268 size_t name_len; 269 270 /* 271 * ok we want all objects associated with this id. 272 * NOTE: we set key.offset = 0; because we want to start with the 273 * first xattr that we find and walk forward 274 */ 275 key.objectid = btrfs_ino(inode); 276 key.type = BTRFS_XATTR_ITEM_KEY; 277 key.offset = 0; 278 279 path = btrfs_alloc_path(); 280 if (!path) 281 return -ENOMEM; 282 path->reada = 2; 283 284 /* search for our xattrs */ 285 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 286 if (ret < 0) 287 goto err; 288 289 while (1) { 290 leaf = path->nodes[0]; 291 slot = path->slots[0]; 292 293 /* this is where we start walking through the path */ 294 if (slot >= btrfs_header_nritems(leaf)) { 295 /* 296 * if we've reached the last slot in this leaf we need 297 * to go to the next leaf and reset everything 298 */ 299 ret = btrfs_next_leaf(root, path); 300 if (ret < 0) 301 goto err; 302 else if (ret > 0) 303 break; 304 continue; 305 } 306 307 btrfs_item_key_to_cpu(leaf, &found_key, slot); 308 309 /* check to make sure this item is what we want */ 310 if (found_key.objectid != key.objectid) 311 break; 312 if (found_key.type != BTRFS_XATTR_ITEM_KEY) 313 break; 314 315 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 316 if (verify_dir_item(root, leaf, di)) 317 goto next; 318 319 name_len = btrfs_dir_name_len(leaf, di); 320 total_size += name_len + 1; 321 322 /* we are just looking for how big our buffer needs to be */ 323 if (!size) 324 goto next; 325 326 if (!buffer || (name_len + 1) > size_left) { 327 ret = -ERANGE; 328 goto err; 329 } 330 331 name_ptr = (unsigned long)(di + 1); 332 read_extent_buffer(leaf, buffer, name_ptr, name_len); 333 buffer[name_len] = '\0'; 334 335 size_left -= name_len + 1; 336 buffer += name_len + 1; 337 next: 338 path->slots[0]++; 339 } 340 ret = total_size; 341 342 err: 343 btrfs_free_path(path); 344 345 return ret; 346 } 347 348 /* 349 * List of handlers for synthetic system.* attributes. All real ondisk 350 * attributes are handled directly. 351 */ 352 const struct xattr_handler *btrfs_xattr_handlers[] = { 353 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 354 &posix_acl_access_xattr_handler, 355 &posix_acl_default_xattr_handler, 356 #endif 357 NULL, 358 }; 359 360 /* 361 * Check if the attribute is in a supported namespace. 362 * 363 * This applied after the check for the synthetic attributes in the system 364 * namespace. 365 */ 366 static bool btrfs_is_valid_xattr(const char *name) 367 { 368 return !strncmp(name, XATTR_SECURITY_PREFIX, 369 XATTR_SECURITY_PREFIX_LEN) || 370 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 371 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 372 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) || 373 !strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN); 374 } 375 376 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 377 void *buffer, size_t size) 378 { 379 /* 380 * If this is a request for a synthetic attribute in the system.* 381 * namespace use the generic infrastructure to resolve a handler 382 * for it via sb->s_xattr. 383 */ 384 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 385 return generic_getxattr(dentry, name, buffer, size); 386 387 if (!btrfs_is_valid_xattr(name)) 388 return -EOPNOTSUPP; 389 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 390 } 391 392 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 393 size_t size, int flags) 394 { 395 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 396 397 /* 398 * The permission on security.* and system.* is not checked 399 * in permission(). 400 */ 401 if (btrfs_root_readonly(root)) 402 return -EROFS; 403 404 /* 405 * If this is a request for a synthetic attribute in the system.* 406 * namespace use the generic infrastructure to resolve a handler 407 * for it via sb->s_xattr. 408 */ 409 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 410 return generic_setxattr(dentry, name, value, size, flags); 411 412 if (!btrfs_is_valid_xattr(name)) 413 return -EOPNOTSUPP; 414 415 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN)) 416 return btrfs_set_prop(dentry->d_inode, name, 417 value, size, flags); 418 419 if (size == 0) 420 value = ""; /* empty EA, do not remove */ 421 422 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 423 flags); 424 } 425 426 int btrfs_removexattr(struct dentry *dentry, const char *name) 427 { 428 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 429 430 /* 431 * The permission on security.* and system.* is not checked 432 * in permission(). 433 */ 434 if (btrfs_root_readonly(root)) 435 return -EROFS; 436 437 /* 438 * If this is a request for a synthetic attribute in the system.* 439 * namespace use the generic infrastructure to resolve a handler 440 * for it via sb->s_xattr. 441 */ 442 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 443 return generic_removexattr(dentry, name); 444 445 if (!btrfs_is_valid_xattr(name)) 446 return -EOPNOTSUPP; 447 448 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN)) 449 return btrfs_set_prop(dentry->d_inode, name, 450 NULL, 0, XATTR_REPLACE); 451 452 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 453 XATTR_REPLACE); 454 } 455 456 static int btrfs_initxattrs(struct inode *inode, 457 const struct xattr *xattr_array, void *fs_info) 458 { 459 const struct xattr *xattr; 460 struct btrfs_trans_handle *trans = fs_info; 461 char *name; 462 int err = 0; 463 464 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 465 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 466 strlen(xattr->name) + 1, GFP_NOFS); 467 if (!name) { 468 err = -ENOMEM; 469 break; 470 } 471 strcpy(name, XATTR_SECURITY_PREFIX); 472 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 473 err = __btrfs_setxattr(trans, inode, name, 474 xattr->value, xattr->value_len, 0); 475 kfree(name); 476 if (err < 0) 477 break; 478 } 479 return err; 480 } 481 482 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 483 struct inode *inode, struct inode *dir, 484 const struct qstr *qstr) 485 { 486 return security_inode_init_security(inode, dir, qstr, 487 &btrfs_initxattrs, trans); 488 } 489