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