| 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 | } |