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