| 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 "ctree.h" |
| 26 | #include "btrfs_inode.h" |
| 27 | #include "transaction.h" |
| 28 | #include "xattr.h" |
| 29 | #include "disk-io.h" |
| 30 | |
| 31 | |
| 32 | ssize_t __btrfs_getxattr(struct inode *inode, const char *name, |
| 33 | void *buffer, size_t size) |
| 34 | { |
| 35 | struct btrfs_dir_item *di; |
| 36 | struct btrfs_root *root = BTRFS_I(inode)->root; |
| 37 | struct btrfs_path *path; |
| 38 | struct extent_buffer *leaf; |
| 39 | int ret = 0; |
| 40 | unsigned long data_ptr; |
| 41 | |
| 42 | path = btrfs_alloc_path(); |
| 43 | if (!path) |
| 44 | return -ENOMEM; |
| 45 | |
| 46 | /* lookup the xattr by name */ |
| 47 | di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name, |
| 48 | strlen(name), 0); |
| 49 | if (!di) { |
| 50 | ret = -ENODATA; |
| 51 | goto out; |
| 52 | } else if (IS_ERR(di)) { |
| 53 | ret = PTR_ERR(di); |
| 54 | goto out; |
| 55 | } |
| 56 | |
| 57 | leaf = path->nodes[0]; |
| 58 | /* if size is 0, that means we want the size of the attr */ |
| 59 | if (!size) { |
| 60 | ret = btrfs_dir_data_len(leaf, di); |
| 61 | goto out; |
| 62 | } |
| 63 | |
| 64 | /* now get the data out of our dir_item */ |
| 65 | if (btrfs_dir_data_len(leaf, di) > size) { |
| 66 | ret = -ERANGE; |
| 67 | goto out; |
| 68 | } |
| 69 | |
| 70 | /* |
| 71 | * The way things are packed into the leaf is like this |
| 72 | * |struct btrfs_dir_item|name|data| |
| 73 | * where name is the xattr name, so security.foo, and data is the |
| 74 | * content of the xattr. data_ptr points to the location in memory |
| 75 | * where the data starts in the in memory leaf |
| 76 | */ |
| 77 | data_ptr = (unsigned long)((char *)(di + 1) + |
| 78 | btrfs_dir_name_len(leaf, di)); |
| 79 | read_extent_buffer(leaf, buffer, data_ptr, |
| 80 | btrfs_dir_data_len(leaf, di)); |
| 81 | ret = btrfs_dir_data_len(leaf, di); |
| 82 | |
| 83 | out: |
| 84 | btrfs_free_path(path); |
| 85 | return ret; |
| 86 | } |
| 87 | |
| 88 | static int do_setxattr(struct btrfs_trans_handle *trans, |
| 89 | struct inode *inode, const char *name, |
| 90 | const void *value, size_t size, int flags) |
| 91 | { |
| 92 | struct btrfs_dir_item *di; |
| 93 | struct btrfs_root *root = BTRFS_I(inode)->root; |
| 94 | struct btrfs_path *path; |
| 95 | size_t name_len = strlen(name); |
| 96 | int ret = 0; |
| 97 | |
| 98 | if (name_len + size > BTRFS_MAX_XATTR_SIZE(root)) |
| 99 | return -ENOSPC; |
| 100 | |
| 101 | path = btrfs_alloc_path(); |
| 102 | if (!path) |
| 103 | return -ENOMEM; |
| 104 | |
| 105 | if (flags & XATTR_REPLACE) { |
| 106 | di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name, |
| 107 | name_len, -1); |
| 108 | if (IS_ERR(di)) { |
| 109 | ret = PTR_ERR(di); |
| 110 | goto out; |
| 111 | } else if (!di) { |
| 112 | ret = -ENODATA; |
| 113 | goto out; |
| 114 | } |
| 115 | ret = btrfs_delete_one_dir_name(trans, root, path, di); |
| 116 | if (ret) |
| 117 | goto out; |
| 118 | btrfs_release_path(path); |
| 119 | |
| 120 | /* |
| 121 | * remove the attribute |
| 122 | */ |
| 123 | if (!value) |
| 124 | goto out; |
| 125 | } else { |
| 126 | di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), |
| 127 | name, name_len, 0); |
| 128 | if (IS_ERR(di)) { |
| 129 | ret = PTR_ERR(di); |
| 130 | goto out; |
| 131 | } |
| 132 | if (!di && !value) |
| 133 | goto out; |
| 134 | btrfs_release_path(path); |
| 135 | } |
| 136 | |
| 137 | again: |
| 138 | ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), |
| 139 | name, name_len, value, size); |
| 140 | /* |
| 141 | * If we're setting an xattr to a new value but the new value is say |
| 142 | * exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting |
| 143 | * back from split_leaf. This is because it thinks we'll be extending |
| 144 | * the existing item size, but we're asking for enough space to add the |
| 145 | * item itself. So if we get EOVERFLOW just set ret to EEXIST and let |
| 146 | * the rest of the function figure it out. |
| 147 | */ |
| 148 | if (ret == -EOVERFLOW) |
| 149 | ret = -EEXIST; |
| 150 | |
| 151 | if (ret == -EEXIST) { |
| 152 | if (flags & XATTR_CREATE) |
| 153 | goto out; |
| 154 | /* |
| 155 | * We can't use the path we already have since we won't have the |
| 156 | * proper locking for a delete, so release the path and |
| 157 | * re-lookup to delete the thing. |
| 158 | */ |
| 159 | btrfs_release_path(path); |
| 160 | di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), |
| 161 | name, name_len, -1); |
| 162 | if (IS_ERR(di)) { |
| 163 | ret = PTR_ERR(di); |
| 164 | goto out; |
| 165 | } else if (!di) { |
| 166 | /* Shouldn't happen but just in case... */ |
| 167 | btrfs_release_path(path); |
| 168 | goto again; |
| 169 | } |
| 170 | |
| 171 | ret = btrfs_delete_one_dir_name(trans, root, path, di); |
| 172 | if (ret) |
| 173 | goto out; |
| 174 | |
| 175 | /* |
| 176 | * We have a value to set, so go back and try to insert it now. |
| 177 | */ |
| 178 | if (value) { |
| 179 | btrfs_release_path(path); |
| 180 | goto again; |
| 181 | } |
| 182 | } |
| 183 | out: |
| 184 | btrfs_free_path(path); |
| 185 | return ret; |
| 186 | } |
| 187 | |
| 188 | /* |
| 189 | * @value: "" makes the attribute to empty, NULL removes it |
| 190 | */ |
| 191 | int __btrfs_setxattr(struct btrfs_trans_handle *trans, |
| 192 | struct inode *inode, const char *name, |
| 193 | const void *value, size_t size, int flags) |
| 194 | { |
| 195 | struct btrfs_root *root = BTRFS_I(inode)->root; |
| 196 | int ret; |
| 197 | |
| 198 | if (trans) |
| 199 | return do_setxattr(trans, inode, name, value, size, flags); |
| 200 | |
| 201 | trans = btrfs_start_transaction(root, 2); |
| 202 | if (IS_ERR(trans)) |
| 203 | return PTR_ERR(trans); |
| 204 | |
| 205 | ret = do_setxattr(trans, inode, name, value, size, flags); |
| 206 | if (ret) |
| 207 | goto out; |
| 208 | |
| 209 | inode_inc_iversion(inode); |
| 210 | inode->i_ctime = CURRENT_TIME; |
| 211 | set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); |
| 212 | ret = btrfs_update_inode(trans, root, inode); |
| 213 | BUG_ON(ret); |
| 214 | out: |
| 215 | btrfs_end_transaction(trans, root); |
| 216 | return ret; |
| 217 | } |
| 218 | |
| 219 | ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) |
| 220 | { |
| 221 | struct btrfs_key key, found_key; |
| 222 | struct inode *inode = dentry->d_inode; |
| 223 | struct btrfs_root *root = BTRFS_I(inode)->root; |
| 224 | struct btrfs_path *path; |
| 225 | struct extent_buffer *leaf; |
| 226 | struct btrfs_dir_item *di; |
| 227 | int ret = 0, slot; |
| 228 | size_t total_size = 0, size_left = size; |
| 229 | unsigned long name_ptr; |
| 230 | size_t name_len; |
| 231 | |
| 232 | /* |
| 233 | * ok we want all objects associated with this id. |
| 234 | * NOTE: we set key.offset = 0; because we want to start with the |
| 235 | * first xattr that we find and walk forward |
| 236 | */ |
| 237 | key.objectid = btrfs_ino(inode); |
| 238 | btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); |
| 239 | key.offset = 0; |
| 240 | |
| 241 | path = btrfs_alloc_path(); |
| 242 | if (!path) |
| 243 | return -ENOMEM; |
| 244 | path->reada = 2; |
| 245 | |
| 246 | /* search for our xattrs */ |
| 247 | ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); |
| 248 | if (ret < 0) |
| 249 | goto err; |
| 250 | |
| 251 | while (1) { |
| 252 | leaf = path->nodes[0]; |
| 253 | slot = path->slots[0]; |
| 254 | |
| 255 | /* this is where we start walking through the path */ |
| 256 | if (slot >= btrfs_header_nritems(leaf)) { |
| 257 | /* |
| 258 | * if we've reached the last slot in this leaf we need |
| 259 | * to go to the next leaf and reset everything |
| 260 | */ |
| 261 | ret = btrfs_next_leaf(root, path); |
| 262 | if (ret < 0) |
| 263 | goto err; |
| 264 | else if (ret > 0) |
| 265 | break; |
| 266 | continue; |
| 267 | } |
| 268 | |
| 269 | btrfs_item_key_to_cpu(leaf, &found_key, slot); |
| 270 | |
| 271 | /* check to make sure this item is what we want */ |
| 272 | if (found_key.objectid != key.objectid) |
| 273 | break; |
| 274 | if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) |
| 275 | break; |
| 276 | |
| 277 | di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); |
| 278 | if (verify_dir_item(root, leaf, di)) |
| 279 | goto next; |
| 280 | |
| 281 | name_len = btrfs_dir_name_len(leaf, di); |
| 282 | total_size += name_len + 1; |
| 283 | |
| 284 | /* we are just looking for how big our buffer needs to be */ |
| 285 | if (!size) |
| 286 | goto next; |
| 287 | |
| 288 | if (!buffer || (name_len + 1) > size_left) { |
| 289 | ret = -ERANGE; |
| 290 | goto err; |
| 291 | } |
| 292 | |
| 293 | name_ptr = (unsigned long)(di + 1); |
| 294 | read_extent_buffer(leaf, buffer, name_ptr, name_len); |
| 295 | buffer[name_len] = '\0'; |
| 296 | |
| 297 | size_left -= name_len + 1; |
| 298 | buffer += name_len + 1; |
| 299 | next: |
| 300 | path->slots[0]++; |
| 301 | } |
| 302 | ret = total_size; |
| 303 | |
| 304 | err: |
| 305 | btrfs_free_path(path); |
| 306 | |
| 307 | return ret; |
| 308 | } |
| 309 | |
| 310 | /* |
| 311 | * List of handlers for synthetic system.* attributes. All real ondisk |
| 312 | * attributes are handled directly. |
| 313 | */ |
| 314 | const struct xattr_handler *btrfs_xattr_handlers[] = { |
| 315 | #ifdef CONFIG_BTRFS_FS_POSIX_ACL |
| 316 | &btrfs_xattr_acl_access_handler, |
| 317 | &btrfs_xattr_acl_default_handler, |
| 318 | #endif |
| 319 | NULL, |
| 320 | }; |
| 321 | |
| 322 | /* |
| 323 | * Check if the attribute is in a supported namespace. |
| 324 | * |
| 325 | * This applied after the check for the synthetic attributes in the system |
| 326 | * namespace. |
| 327 | */ |
| 328 | static bool btrfs_is_valid_xattr(const char *name) |
| 329 | { |
| 330 | return !strncmp(name, XATTR_SECURITY_PREFIX, |
| 331 | XATTR_SECURITY_PREFIX_LEN) || |
| 332 | !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || |
| 333 | !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || |
| 334 | !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); |
| 335 | } |
| 336 | |
| 337 | ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, |
| 338 | void *buffer, size_t size) |
| 339 | { |
| 340 | /* |
| 341 | * If this is a request for a synthetic attribute in the system.* |
| 342 | * namespace use the generic infrastructure to resolve a handler |
| 343 | * for it via sb->s_xattr. |
| 344 | */ |
| 345 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| 346 | return generic_getxattr(dentry, name, buffer, size); |
| 347 | |
| 348 | if (!btrfs_is_valid_xattr(name)) |
| 349 | return -EOPNOTSUPP; |
| 350 | return __btrfs_getxattr(dentry->d_inode, name, buffer, size); |
| 351 | } |
| 352 | |
| 353 | int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, |
| 354 | size_t size, int flags) |
| 355 | { |
| 356 | struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; |
| 357 | |
| 358 | /* |
| 359 | * The permission on security.* and system.* is not checked |
| 360 | * in permission(). |
| 361 | */ |
| 362 | if (btrfs_root_readonly(root)) |
| 363 | return -EROFS; |
| 364 | |
| 365 | /* |
| 366 | * If this is a request for a synthetic attribute in the system.* |
| 367 | * namespace use the generic infrastructure to resolve a handler |
| 368 | * for it via sb->s_xattr. |
| 369 | */ |
| 370 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| 371 | return generic_setxattr(dentry, name, value, size, flags); |
| 372 | |
| 373 | if (!btrfs_is_valid_xattr(name)) |
| 374 | return -EOPNOTSUPP; |
| 375 | |
| 376 | if (size == 0) |
| 377 | value = ""; /* empty EA, do not remove */ |
| 378 | |
| 379 | return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, |
| 380 | flags); |
| 381 | } |
| 382 | |
| 383 | int btrfs_removexattr(struct dentry *dentry, const char *name) |
| 384 | { |
| 385 | struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; |
| 386 | |
| 387 | /* |
| 388 | * The permission on security.* and system.* is not checked |
| 389 | * in permission(). |
| 390 | */ |
| 391 | if (btrfs_root_readonly(root)) |
| 392 | return -EROFS; |
| 393 | |
| 394 | /* |
| 395 | * If this is a request for a synthetic attribute in the system.* |
| 396 | * namespace use the generic infrastructure to resolve a handler |
| 397 | * for it via sb->s_xattr. |
| 398 | */ |
| 399 | if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) |
| 400 | return generic_removexattr(dentry, name); |
| 401 | |
| 402 | if (!btrfs_is_valid_xattr(name)) |
| 403 | return -EOPNOTSUPP; |
| 404 | |
| 405 | return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, |
| 406 | XATTR_REPLACE); |
| 407 | } |
| 408 | |
| 409 | int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array, |
| 410 | void *fs_info) |
| 411 | { |
| 412 | const struct xattr *xattr; |
| 413 | struct btrfs_trans_handle *trans = fs_info; |
| 414 | char *name; |
| 415 | int err = 0; |
| 416 | |
| 417 | for (xattr = xattr_array; xattr->name != NULL; xattr++) { |
| 418 | name = kmalloc(XATTR_SECURITY_PREFIX_LEN + |
| 419 | strlen(xattr->name) + 1, GFP_NOFS); |
| 420 | if (!name) { |
| 421 | err = -ENOMEM; |
| 422 | break; |
| 423 | } |
| 424 | strcpy(name, XATTR_SECURITY_PREFIX); |
| 425 | strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); |
| 426 | err = __btrfs_setxattr(trans, inode, name, |
| 427 | xattr->value, xattr->value_len, 0); |
| 428 | kfree(name); |
| 429 | if (err < 0) |
| 430 | break; |
| 431 | } |
| 432 | return err; |
| 433 | } |
| 434 | |
| 435 | int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, |
| 436 | struct inode *inode, struct inode *dir, |
| 437 | const struct qstr *qstr) |
| 438 | { |
| 439 | return security_inode_init_security(inode, dir, qstr, |
| 440 | &btrfs_initxattrs, trans); |
| 441 | } |