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 again: 122 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(inode), 123 name, name_len, value, size); 124 if (ret == -EEXIST) { 125 if (flags & XATTR_CREATE) 126 goto out; 127 /* 128 * We can't use the path we already have since we won't have the 129 * proper locking for a delete, so release the path and 130 * re-lookup to delete the thing. 131 */ 132 btrfs_release_path(path); 133 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), 134 name, name_len, -1); 135 if (IS_ERR(di)) { 136 ret = PTR_ERR(di); 137 goto out; 138 } else if (!di) { 139 /* Shouldn't happen but just in case... */ 140 btrfs_release_path(path); 141 goto again; 142 } 143 144 ret = btrfs_delete_one_dir_name(trans, root, path, di); 145 if (ret) 146 goto out; 147 148 /* 149 * We have a value to set, so go back and try to insert it now. 150 */ 151 if (value) { 152 btrfs_release_path(path); 153 goto again; 154 } 155 } 156 out: 157 btrfs_free_path(path); 158 return ret; 159 } 160 161 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 162 struct inode *inode, const char *name, 163 const void *value, size_t size, int flags) 164 { 165 struct btrfs_root *root = BTRFS_I(inode)->root; 166 int ret; 167 168 if (trans) 169 return do_setxattr(trans, inode, name, value, size, flags); 170 171 trans = btrfs_start_transaction(root, 2); 172 if (IS_ERR(trans)) 173 return PTR_ERR(trans); 174 175 ret = do_setxattr(trans, inode, name, value, size, flags); 176 if (ret) 177 goto out; 178 179 inode->i_ctime = CURRENT_TIME; 180 ret = btrfs_update_inode(trans, root, inode); 181 BUG_ON(ret); 182 out: 183 btrfs_end_transaction_throttle(trans, root); 184 return ret; 185 } 186 187 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 188 { 189 struct btrfs_key key, found_key; 190 struct inode *inode = dentry->d_inode; 191 struct btrfs_root *root = BTRFS_I(inode)->root; 192 struct btrfs_path *path; 193 struct extent_buffer *leaf; 194 struct btrfs_dir_item *di; 195 int ret = 0, slot; 196 size_t total_size = 0, size_left = size; 197 unsigned long name_ptr; 198 size_t name_len; 199 200 /* 201 * ok we want all objects associated with this id. 202 * NOTE: we set key.offset = 0; because we want to start with the 203 * first xattr that we find and walk forward 204 */ 205 key.objectid = btrfs_ino(inode); 206 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 207 key.offset = 0; 208 209 path = btrfs_alloc_path(); 210 if (!path) 211 return -ENOMEM; 212 path->reada = 2; 213 214 /* search for our xattrs */ 215 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 216 if (ret < 0) 217 goto err; 218 219 while (1) { 220 leaf = path->nodes[0]; 221 slot = path->slots[0]; 222 223 /* this is where we start walking through the path */ 224 if (slot >= btrfs_header_nritems(leaf)) { 225 /* 226 * if we've reached the last slot in this leaf we need 227 * to go to the next leaf and reset everything 228 */ 229 ret = btrfs_next_leaf(root, path); 230 if (ret < 0) 231 goto err; 232 else if (ret > 0) 233 break; 234 continue; 235 } 236 237 btrfs_item_key_to_cpu(leaf, &found_key, slot); 238 239 /* check to make sure this item is what we want */ 240 if (found_key.objectid != key.objectid) 241 break; 242 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 243 break; 244 245 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 246 if (verify_dir_item(root, leaf, di)) 247 continue; 248 249 name_len = btrfs_dir_name_len(leaf, di); 250 total_size += name_len + 1; 251 252 /* we are just looking for how big our buffer needs to be */ 253 if (!size) 254 goto next; 255 256 if (!buffer || (name_len + 1) > size_left) { 257 ret = -ERANGE; 258 goto err; 259 } 260 261 name_ptr = (unsigned long)(di + 1); 262 read_extent_buffer(leaf, buffer, name_ptr, name_len); 263 buffer[name_len] = '\0'; 264 265 size_left -= name_len + 1; 266 buffer += name_len + 1; 267 next: 268 path->slots[0]++; 269 } 270 ret = total_size; 271 272 err: 273 btrfs_free_path(path); 274 275 return ret; 276 } 277 278 /* 279 * List of handlers for synthetic system.* attributes. All real ondisk 280 * attributes are handled directly. 281 */ 282 const struct xattr_handler *btrfs_xattr_handlers[] = { 283 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 284 &btrfs_xattr_acl_access_handler, 285 &btrfs_xattr_acl_default_handler, 286 #endif 287 NULL, 288 }; 289 290 /* 291 * Check if the attribute is in a supported namespace. 292 * 293 * This applied after the check for the synthetic attributes in the system 294 * namespace. 295 */ 296 static bool btrfs_is_valid_xattr(const char *name) 297 { 298 return !strncmp(name, XATTR_SECURITY_PREFIX, 299 XATTR_SECURITY_PREFIX_LEN) || 300 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 301 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 302 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 303 } 304 305 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 306 void *buffer, size_t size) 307 { 308 /* 309 * If this is a request for a synthetic attribute in the system.* 310 * namespace use the generic infrastructure to resolve a handler 311 * for it via sb->s_xattr. 312 */ 313 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 314 return generic_getxattr(dentry, name, buffer, size); 315 316 if (!btrfs_is_valid_xattr(name)) 317 return -EOPNOTSUPP; 318 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 319 } 320 321 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 322 size_t size, int flags) 323 { 324 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 325 326 /* 327 * The permission on security.* and system.* is not checked 328 * in permission(). 329 */ 330 if (btrfs_root_readonly(root)) 331 return -EROFS; 332 333 /* 334 * If this is a request for a synthetic attribute in the system.* 335 * namespace use the generic infrastructure to resolve a handler 336 * for it via sb->s_xattr. 337 */ 338 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 339 return generic_setxattr(dentry, name, value, size, flags); 340 341 if (!btrfs_is_valid_xattr(name)) 342 return -EOPNOTSUPP; 343 344 if (size == 0) 345 value = ""; /* empty EA, do not remove */ 346 347 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 348 flags); 349 } 350 351 int btrfs_removexattr(struct dentry *dentry, const char *name) 352 { 353 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 354 355 /* 356 * The permission on security.* and system.* is not checked 357 * in permission(). 358 */ 359 if (btrfs_root_readonly(root)) 360 return -EROFS; 361 362 /* 363 * If this is a request for a synthetic attribute in the system.* 364 * namespace use the generic infrastructure to resolve a handler 365 * for it via sb->s_xattr. 366 */ 367 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 368 return generic_removexattr(dentry, name); 369 370 if (!btrfs_is_valid_xattr(name)) 371 return -EOPNOTSUPP; 372 373 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 374 XATTR_REPLACE); 375 } 376 377 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 378 struct inode *inode, struct inode *dir, 379 const struct qstr *qstr) 380 { 381 int err; 382 size_t len; 383 void *value; 384 char *suffix; 385 char *name; 386 387 err = security_inode_init_security(inode, dir, qstr, &suffix, &value, 388 &len); 389 if (err) { 390 if (err == -EOPNOTSUPP) 391 return 0; 392 return err; 393 } 394 395 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1, 396 GFP_NOFS); 397 if (!name) { 398 err = -ENOMEM; 399 } else { 400 strcpy(name, XATTR_SECURITY_PREFIX); 401 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix); 402 err = __btrfs_setxattr(trans, inode, name, value, len, 0); 403 kfree(name); 404 } 405 406 kfree(suffix); 407 kfree(value); 408 return err; 409 } 410