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 } 442