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_inc_iversion(inode); 200 inode->i_ctime = CURRENT_TIME; 201 ret = btrfs_update_inode(trans, root, inode); 202 BUG_ON(ret); 203 out: 204 btrfs_end_transaction(trans, root); 205 return ret; 206 } 207 208 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 209 { 210 struct btrfs_key key, found_key; 211 struct inode *inode = dentry->d_inode; 212 struct btrfs_root *root = BTRFS_I(inode)->root; 213 struct btrfs_path *path; 214 struct extent_buffer *leaf; 215 struct btrfs_dir_item *di; 216 int ret = 0, slot; 217 size_t total_size = 0, size_left = size; 218 unsigned long name_ptr; 219 size_t name_len; 220 221 /* 222 * ok we want all objects associated with this id. 223 * NOTE: we set key.offset = 0; because we want to start with the 224 * first xattr that we find and walk forward 225 */ 226 key.objectid = btrfs_ino(inode); 227 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 228 key.offset = 0; 229 230 path = btrfs_alloc_path(); 231 if (!path) 232 return -ENOMEM; 233 path->reada = 2; 234 235 /* search for our xattrs */ 236 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 237 if (ret < 0) 238 goto err; 239 240 while (1) { 241 leaf = path->nodes[0]; 242 slot = path->slots[0]; 243 244 /* this is where we start walking through the path */ 245 if (slot >= btrfs_header_nritems(leaf)) { 246 /* 247 * if we've reached the last slot in this leaf we need 248 * to go to the next leaf and reset everything 249 */ 250 ret = btrfs_next_leaf(root, path); 251 if (ret < 0) 252 goto err; 253 else if (ret > 0) 254 break; 255 continue; 256 } 257 258 btrfs_item_key_to_cpu(leaf, &found_key, slot); 259 260 /* check to make sure this item is what we want */ 261 if (found_key.objectid != key.objectid) 262 break; 263 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 264 break; 265 266 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 267 if (verify_dir_item(root, leaf, di)) 268 continue; 269 270 name_len = btrfs_dir_name_len(leaf, di); 271 total_size += name_len + 1; 272 273 /* we are just looking for how big our buffer needs to be */ 274 if (!size) 275 goto next; 276 277 if (!buffer || (name_len + 1) > size_left) { 278 ret = -ERANGE; 279 goto err; 280 } 281 282 name_ptr = (unsigned long)(di + 1); 283 read_extent_buffer(leaf, buffer, name_ptr, name_len); 284 buffer[name_len] = '\0'; 285 286 size_left -= name_len + 1; 287 buffer += name_len + 1; 288 next: 289 path->slots[0]++; 290 } 291 ret = total_size; 292 293 err: 294 btrfs_free_path(path); 295 296 return ret; 297 } 298 299 /* 300 * List of handlers for synthetic system.* attributes. All real ondisk 301 * attributes are handled directly. 302 */ 303 const struct xattr_handler *btrfs_xattr_handlers[] = { 304 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 305 &btrfs_xattr_acl_access_handler, 306 &btrfs_xattr_acl_default_handler, 307 #endif 308 NULL, 309 }; 310 311 /* 312 * Check if the attribute is in a supported namespace. 313 * 314 * This applied after the check for the synthetic attributes in the system 315 * namespace. 316 */ 317 static bool btrfs_is_valid_xattr(const char *name) 318 { 319 return !strncmp(name, XATTR_SECURITY_PREFIX, 320 XATTR_SECURITY_PREFIX_LEN) || 321 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 322 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 323 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 324 } 325 326 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 327 void *buffer, size_t size) 328 { 329 /* 330 * If this is a request for a synthetic attribute in the system.* 331 * namespace use the generic infrastructure to resolve a handler 332 * for it via sb->s_xattr. 333 */ 334 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 335 return generic_getxattr(dentry, name, buffer, size); 336 337 if (!btrfs_is_valid_xattr(name)) 338 return -EOPNOTSUPP; 339 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 340 } 341 342 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 343 size_t size, int flags) 344 { 345 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 346 347 /* 348 * The permission on security.* and system.* is not checked 349 * in permission(). 350 */ 351 if (btrfs_root_readonly(root)) 352 return -EROFS; 353 354 /* 355 * If this is a request for a synthetic attribute in the system.* 356 * namespace use the generic infrastructure to resolve a handler 357 * for it via sb->s_xattr. 358 */ 359 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 360 return generic_setxattr(dentry, name, value, size, flags); 361 362 if (!btrfs_is_valid_xattr(name)) 363 return -EOPNOTSUPP; 364 365 if (size == 0) 366 value = ""; /* empty EA, do not remove */ 367 368 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 369 flags); 370 } 371 372 int btrfs_removexattr(struct dentry *dentry, const char *name) 373 { 374 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 375 376 /* 377 * The permission on security.* and system.* is not checked 378 * in permission(). 379 */ 380 if (btrfs_root_readonly(root)) 381 return -EROFS; 382 383 /* 384 * If this is a request for a synthetic attribute in the system.* 385 * namespace use the generic infrastructure to resolve a handler 386 * for it via sb->s_xattr. 387 */ 388 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 389 return generic_removexattr(dentry, name); 390 391 if (!btrfs_is_valid_xattr(name)) 392 return -EOPNOTSUPP; 393 394 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 395 XATTR_REPLACE); 396 } 397 398 int btrfs_initxattrs(struct inode *inode, const struct xattr *xattr_array, 399 void *fs_info) 400 { 401 const struct xattr *xattr; 402 struct btrfs_trans_handle *trans = fs_info; 403 char *name; 404 int err = 0; 405 406 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 407 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 408 strlen(xattr->name) + 1, GFP_NOFS); 409 if (!name) { 410 err = -ENOMEM; 411 break; 412 } 413 strcpy(name, XATTR_SECURITY_PREFIX); 414 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 415 err = __btrfs_setxattr(trans, inode, name, 416 xattr->value, xattr->value_len, 0); 417 kfree(name); 418 if (err < 0) 419 break; 420 } 421 return err; 422 } 423 424 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 425 struct inode *inode, struct inode *dir, 426 const struct qstr *qstr) 427 { 428 return security_inode_init_security(inode, dir, qstr, 429 &btrfs_initxattrs, trans); 430 } 431