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