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 33 34 ssize_t __btrfs_getxattr(struct inode *inode, const char *name, 35 void *buffer, size_t size) 36 { 37 struct btrfs_dir_item *di; 38 struct btrfs_root *root = BTRFS_I(inode)->root; 39 struct btrfs_path *path; 40 struct extent_buffer *leaf; 41 int ret = 0; 42 unsigned long data_ptr; 43 44 path = btrfs_alloc_path(); 45 if (!path) 46 return -ENOMEM; 47 48 /* lookup the xattr by name */ 49 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), name, 50 strlen(name), 0); 51 if (!di) { 52 ret = -ENODATA; 53 goto out; 54 } else if (IS_ERR(di)) { 55 ret = PTR_ERR(di); 56 goto out; 57 } 58 59 leaf = path->nodes[0]; 60 /* if size is 0, that means we want the size of the attr */ 61 if (!size) { 62 ret = btrfs_dir_data_len(leaf, di); 63 goto out; 64 } 65 66 /* now get the data out of our dir_item */ 67 if (btrfs_dir_data_len(leaf, di) > size) { 68 ret = -ERANGE; 69 goto out; 70 } 71 72 /* 73 * The way things are packed into the leaf is like this 74 * |struct btrfs_dir_item|name|data| 75 * where name is the xattr name, so security.foo, and data is the 76 * content of the xattr. data_ptr points to the location in memory 77 * where the data starts in the in memory leaf 78 */ 79 data_ptr = (unsigned long)((char *)(di + 1) + 80 btrfs_dir_name_len(leaf, di)); 81 read_extent_buffer(leaf, buffer, data_ptr, 82 btrfs_dir_data_len(leaf, di)); 83 ret = btrfs_dir_data_len(leaf, di); 84 85 out: 86 btrfs_free_path(path); 87 return ret; 88 } 89 90 static int do_setxattr(struct btrfs_trans_handle *trans, 91 struct inode *inode, const char *name, 92 const void *value, size_t size, int flags) 93 { 94 struct btrfs_dir_item *di; 95 struct btrfs_root *root = BTRFS_I(inode)->root; 96 struct btrfs_path *path; 97 size_t name_len = strlen(name); 98 int ret = 0; 99 100 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root)) 101 return -ENOSPC; 102 103 path = btrfs_alloc_path(); 104 if (!path) 105 return -ENOMEM; 106 107 if (flags & XATTR_REPLACE) { 108 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), name, 109 name_len, -1); 110 if (IS_ERR(di)) { 111 ret = PTR_ERR(di); 112 goto out; 113 } else if (!di) { 114 ret = -ENODATA; 115 goto out; 116 } 117 ret = btrfs_delete_one_dir_name(trans, root, path, di); 118 if (ret) 119 goto out; 120 btrfs_release_path(path); 121 122 /* 123 * remove the attribute 124 */ 125 if (!value) 126 goto out; 127 } else { 128 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(inode), 129 name, name_len, 0); 130 if (IS_ERR(di)) { 131 ret = PTR_ERR(di); 132 goto out; 133 } 134 if (!di && !value) 135 goto out; 136 btrfs_release_path(path); 137 } 138 139 again: 140 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), 141 name, name_len, value, size); 142 /* 143 * If we're setting an xattr to a new value but the new value is say 144 * exactly BTRFS_MAX_XATTR_SIZE, we could end up with EOVERFLOW getting 145 * back from split_leaf. This is because it thinks we'll be extending 146 * the existing item size, but we're asking for enough space to add the 147 * item itself. So if we get EOVERFLOW just set ret to EEXIST and let 148 * the rest of the function figure it out. 149 */ 150 if (ret == -EOVERFLOW) 151 ret = -EEXIST; 152 153 if (ret == -EEXIST) { 154 if (flags & XATTR_CREATE) 155 goto out; 156 /* 157 * We can't use the path we already have since we won't have the 158 * proper locking for a delete, so release the path and 159 * re-lookup to delete the thing. 160 */ 161 btrfs_release_path(path); 162 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), 163 name, name_len, -1); 164 if (IS_ERR(di)) { 165 ret = PTR_ERR(di); 166 goto out; 167 } else if (!di) { 168 /* Shouldn't happen but just in case... */ 169 btrfs_release_path(path); 170 goto again; 171 } 172 173 ret = btrfs_delete_one_dir_name(trans, root, path, di); 174 if (ret) 175 goto out; 176 177 /* 178 * We have a value to set, so go back and try to insert it now. 179 */ 180 if (value) { 181 btrfs_release_path(path); 182 goto again; 183 } 184 } 185 out: 186 btrfs_free_path(path); 187 return ret; 188 } 189 190 /* 191 * @value: "" makes the attribute to empty, NULL removes it 192 */ 193 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 194 struct inode *inode, const char *name, 195 const void *value, size_t size, int flags) 196 { 197 struct btrfs_root *root = BTRFS_I(inode)->root; 198 int ret; 199 200 if (trans) 201 return do_setxattr(trans, inode, name, value, size, flags); 202 203 trans = btrfs_start_transaction(root, 2); 204 if (IS_ERR(trans)) 205 return PTR_ERR(trans); 206 207 ret = do_setxattr(trans, inode, name, value, size, flags); 208 if (ret) 209 goto out; 210 211 inode_inc_iversion(inode); 212 inode->i_ctime = CURRENT_TIME; 213 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 214 ret = btrfs_update_inode(trans, root, inode); 215 BUG_ON(ret); 216 out: 217 btrfs_end_transaction(trans, root); 218 return ret; 219 } 220 221 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 222 { 223 struct btrfs_key key, found_key; 224 struct inode *inode = dentry->d_inode; 225 struct btrfs_root *root = BTRFS_I(inode)->root; 226 struct btrfs_path *path; 227 struct extent_buffer *leaf; 228 struct btrfs_dir_item *di; 229 int ret = 0, slot; 230 size_t total_size = 0, size_left = size; 231 unsigned long name_ptr; 232 size_t name_len; 233 234 /* 235 * ok we want all objects associated with this id. 236 * NOTE: we set key.offset = 0; because we want to start with the 237 * first xattr that we find and walk forward 238 */ 239 key.objectid = btrfs_ino(inode); 240 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 241 key.offset = 0; 242 243 path = btrfs_alloc_path(); 244 if (!path) 245 return -ENOMEM; 246 path->reada = 2; 247 248 /* search for our xattrs */ 249 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 250 if (ret < 0) 251 goto err; 252 253 while (1) { 254 leaf = path->nodes[0]; 255 slot = path->slots[0]; 256 257 /* this is where we start walking through the path */ 258 if (slot >= btrfs_header_nritems(leaf)) { 259 /* 260 * if we've reached the last slot in this leaf we need 261 * to go to the next leaf and reset everything 262 */ 263 ret = btrfs_next_leaf(root, path); 264 if (ret < 0) 265 goto err; 266 else if (ret > 0) 267 break; 268 continue; 269 } 270 271 btrfs_item_key_to_cpu(leaf, &found_key, slot); 272 273 /* check to make sure this item is what we want */ 274 if (found_key.objectid != key.objectid) 275 break; 276 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 277 break; 278 279 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 280 if (verify_dir_item(root, leaf, di)) 281 goto next; 282 283 name_len = btrfs_dir_name_len(leaf, di); 284 total_size += name_len + 1; 285 286 /* we are just looking for how big our buffer needs to be */ 287 if (!size) 288 goto next; 289 290 if (!buffer || (name_len + 1) > size_left) { 291 ret = -ERANGE; 292 goto err; 293 } 294 295 name_ptr = (unsigned long)(di + 1); 296 read_extent_buffer(leaf, buffer, name_ptr, name_len); 297 buffer[name_len] = '\0'; 298 299 size_left -= name_len + 1; 300 buffer += name_len + 1; 301 next: 302 path->slots[0]++; 303 } 304 ret = total_size; 305 306 err: 307 btrfs_free_path(path); 308 309 return ret; 310 } 311 312 /* 313 * List of handlers for synthetic system.* attributes. All real ondisk 314 * attributes are handled directly. 315 */ 316 const struct xattr_handler *btrfs_xattr_handlers[] = { 317 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 318 &posix_acl_access_xattr_handler, 319 &posix_acl_default_xattr_handler, 320 #endif 321 NULL, 322 }; 323 324 /* 325 * Check if the attribute is in a supported namespace. 326 * 327 * This applied after the check for the synthetic attributes in the system 328 * namespace. 329 */ 330 static bool btrfs_is_valid_xattr(const char *name) 331 { 332 return !strncmp(name, XATTR_SECURITY_PREFIX, 333 XATTR_SECURITY_PREFIX_LEN) || 334 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 335 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 336 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN) || 337 !strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN); 338 } 339 340 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 341 void *buffer, size_t size) 342 { 343 /* 344 * If this is a request for a synthetic attribute in the system.* 345 * namespace use the generic infrastructure to resolve a handler 346 * for it via sb->s_xattr. 347 */ 348 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 349 return generic_getxattr(dentry, name, buffer, size); 350 351 if (!btrfs_is_valid_xattr(name)) 352 return -EOPNOTSUPP; 353 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 354 } 355 356 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 357 size_t size, int flags) 358 { 359 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 360 361 /* 362 * The permission on security.* and system.* is not checked 363 * in permission(). 364 */ 365 if (btrfs_root_readonly(root)) 366 return -EROFS; 367 368 /* 369 * If this is a request for a synthetic attribute in the system.* 370 * namespace use the generic infrastructure to resolve a handler 371 * for it via sb->s_xattr. 372 */ 373 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 374 return generic_setxattr(dentry, name, value, size, flags); 375 376 if (!btrfs_is_valid_xattr(name)) 377 return -EOPNOTSUPP; 378 379 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN)) 380 return btrfs_set_prop(dentry->d_inode, name, 381 value, size, flags); 382 383 if (size == 0) 384 value = ""; /* empty EA, do not remove */ 385 386 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 387 flags); 388 } 389 390 int btrfs_removexattr(struct dentry *dentry, const char *name) 391 { 392 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 393 394 /* 395 * The permission on security.* and system.* is not checked 396 * in permission(). 397 */ 398 if (btrfs_root_readonly(root)) 399 return -EROFS; 400 401 /* 402 * If this is a request for a synthetic attribute in the system.* 403 * namespace use the generic infrastructure to resolve a handler 404 * for it via sb->s_xattr. 405 */ 406 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 407 return generic_removexattr(dentry, name); 408 409 if (!btrfs_is_valid_xattr(name)) 410 return -EOPNOTSUPP; 411 412 if (!strncmp(name, XATTR_BTRFS_PREFIX, XATTR_BTRFS_PREFIX_LEN)) 413 return btrfs_set_prop(dentry->d_inode, name, 414 NULL, 0, XATTR_REPLACE); 415 416 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 417 XATTR_REPLACE); 418 } 419 420 static int btrfs_initxattrs(struct inode *inode, 421 const struct xattr *xattr_array, void *fs_info) 422 { 423 const struct xattr *xattr; 424 struct btrfs_trans_handle *trans = fs_info; 425 char *name; 426 int err = 0; 427 428 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 429 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 430 strlen(xattr->name) + 1, GFP_NOFS); 431 if (!name) { 432 err = -ENOMEM; 433 break; 434 } 435 strcpy(name, XATTR_SECURITY_PREFIX); 436 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 437 err = __btrfs_setxattr(trans, inode, name, 438 xattr->value, xattr->value_len, 0); 439 kfree(name); 440 if (err < 0) 441 break; 442 } 443 return err; 444 } 445 446 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 447 struct inode *inode, struct inode *dir, 448 const struct qstr *qstr) 449 { 450 return security_inode_init_security(inode, dir, qstr, 451 &btrfs_initxattrs, trans); 452 } 453