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, inode->i_ino, 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 /* first lets see if we already have this xattr */ 106 di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name, 107 strlen(name), -1); 108 if (IS_ERR(di)) { 109 ret = PTR_ERR(di); 110 goto out; 111 } 112 113 /* ok we already have this xattr, lets remove it */ 114 if (di) { 115 /* if we want create only exit */ 116 if (flags & XATTR_CREATE) { 117 ret = -EEXIST; 118 goto out; 119 } 120 121 ret = btrfs_delete_one_dir_name(trans, root, path, di); 122 BUG_ON(ret); 123 btrfs_release_path(root, path); 124 125 /* if we don't have a value then we are removing the xattr */ 126 if (!value) 127 goto out; 128 } else { 129 btrfs_release_path(root, path); 130 131 if (flags & XATTR_REPLACE) { 132 /* we couldn't find the attr to replace */ 133 ret = -ENODATA; 134 goto out; 135 } 136 } 137 138 /* ok we have to create a completely new xattr */ 139 ret = btrfs_insert_xattr_item(trans, root, path, inode->i_ino, 140 name, name_len, value, size); 141 BUG_ON(ret); 142 out: 143 btrfs_free_path(path); 144 return ret; 145 } 146 147 int __btrfs_setxattr(struct btrfs_trans_handle *trans, 148 struct inode *inode, const char *name, 149 const void *value, size_t size, int flags) 150 { 151 struct btrfs_root *root = BTRFS_I(inode)->root; 152 int ret; 153 154 if (trans) 155 return do_setxattr(trans, inode, name, value, size, flags); 156 157 ret = btrfs_reserve_metadata_space(root, 2); 158 if (ret) 159 return ret; 160 161 trans = btrfs_start_transaction(root, 1); 162 if (!trans) { 163 ret = -ENOMEM; 164 goto out; 165 } 166 btrfs_set_trans_block_group(trans, inode); 167 168 ret = do_setxattr(trans, inode, name, value, size, flags); 169 if (ret) 170 goto out; 171 172 inode->i_ctime = CURRENT_TIME; 173 ret = btrfs_update_inode(trans, root, inode); 174 BUG_ON(ret); 175 out: 176 btrfs_end_transaction_throttle(trans, root); 177 btrfs_unreserve_metadata_space(root, 2); 178 return ret; 179 } 180 181 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 182 { 183 struct btrfs_key key, found_key; 184 struct inode *inode = dentry->d_inode; 185 struct btrfs_root *root = BTRFS_I(inode)->root; 186 struct btrfs_path *path; 187 struct btrfs_item *item; 188 struct extent_buffer *leaf; 189 struct btrfs_dir_item *di; 190 int ret = 0, slot, advance; 191 size_t total_size = 0, size_left = size; 192 unsigned long name_ptr; 193 size_t name_len; 194 u32 nritems; 195 196 /* 197 * ok we want all objects associated with this id. 198 * NOTE: we set key.offset = 0; because we want to start with the 199 * first xattr that we find and walk forward 200 */ 201 key.objectid = inode->i_ino; 202 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 203 key.offset = 0; 204 205 path = btrfs_alloc_path(); 206 if (!path) 207 return -ENOMEM; 208 path->reada = 2; 209 210 /* search for our xattrs */ 211 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 212 if (ret < 0) 213 goto err; 214 advance = 0; 215 while (1) { 216 leaf = path->nodes[0]; 217 nritems = btrfs_header_nritems(leaf); 218 slot = path->slots[0]; 219 220 /* this is where we start walking through the path */ 221 if (advance || slot >= nritems) { 222 /* 223 * if we've reached the last slot in this leaf we need 224 * to go to the next leaf and reset everything 225 */ 226 if (slot >= nritems-1) { 227 ret = btrfs_next_leaf(root, path); 228 if (ret) 229 break; 230 leaf = path->nodes[0]; 231 nritems = btrfs_header_nritems(leaf); 232 slot = path->slots[0]; 233 } else { 234 /* 235 * just walking through the slots on this leaf 236 */ 237 slot++; 238 path->slots[0]++; 239 } 240 } 241 advance = 1; 242 243 item = btrfs_item_nr(leaf, slot); 244 btrfs_item_key_to_cpu(leaf, &found_key, slot); 245 246 /* check to make sure this item is what we want */ 247 if (found_key.objectid != key.objectid) 248 break; 249 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 250 break; 251 252 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 253 254 name_len = btrfs_dir_name_len(leaf, di); 255 total_size += name_len + 1; 256 257 /* we are just looking for how big our buffer needs to be */ 258 if (!size) 259 continue; 260 261 if (!buffer || (name_len + 1) > size_left) { 262 ret = -ERANGE; 263 goto err; 264 } 265 266 name_ptr = (unsigned long)(di + 1); 267 read_extent_buffer(leaf, buffer, name_ptr, name_len); 268 buffer[name_len] = '\0'; 269 270 size_left -= name_len + 1; 271 buffer += name_len + 1; 272 } 273 ret = total_size; 274 275 err: 276 btrfs_free_path(path); 277 278 return ret; 279 } 280 281 /* 282 * List of handlers for synthetic system.* attributes. All real ondisk 283 * attributes are handled directly. 284 */ 285 struct xattr_handler *btrfs_xattr_handlers[] = { 286 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 287 &btrfs_xattr_acl_access_handler, 288 &btrfs_xattr_acl_default_handler, 289 #endif 290 NULL, 291 }; 292 293 /* 294 * Check if the attribute is in a supported namespace. 295 * 296 * This applied after the check for the synthetic attributes in the system 297 * namespace. 298 */ 299 static bool btrfs_is_valid_xattr(const char *name) 300 { 301 return !strncmp(name, XATTR_SECURITY_PREFIX, 302 XATTR_SECURITY_PREFIX_LEN) || 303 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 304 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 305 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 306 } 307 308 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 309 void *buffer, size_t size) 310 { 311 /* 312 * If this is a request for a synthetic attribute in the system.* 313 * namespace use the generic infrastructure to resolve a handler 314 * for it via sb->s_xattr. 315 */ 316 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 317 return generic_getxattr(dentry, name, buffer, size); 318 319 if (!btrfs_is_valid_xattr(name)) 320 return -EOPNOTSUPP; 321 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 322 } 323 324 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 325 size_t size, int flags) 326 { 327 /* 328 * If this is a request for a synthetic attribute in the system.* 329 * namespace use the generic infrastructure to resolve a handler 330 * for it via sb->s_xattr. 331 */ 332 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 333 return generic_setxattr(dentry, name, value, size, flags); 334 335 if (!btrfs_is_valid_xattr(name)) 336 return -EOPNOTSUPP; 337 338 if (size == 0) 339 value = ""; /* empty EA, do not remove */ 340 341 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 342 flags); 343 } 344 345 int btrfs_removexattr(struct dentry *dentry, const char *name) 346 { 347 /* 348 * If this is a request for a synthetic attribute in the system.* 349 * namespace use the generic infrastructure to resolve a handler 350 * for it via sb->s_xattr. 351 */ 352 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 353 return generic_removexattr(dentry, name); 354 355 if (!btrfs_is_valid_xattr(name)) 356 return -EOPNOTSUPP; 357 358 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 359 XATTR_REPLACE); 360 } 361 362 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 363 struct inode *inode, struct inode *dir) 364 { 365 int err; 366 size_t len; 367 void *value; 368 char *suffix; 369 char *name; 370 371 err = security_inode_init_security(inode, dir, &suffix, &value, &len); 372 if (err) { 373 if (err == -EOPNOTSUPP) 374 return 0; 375 return err; 376 } 377 378 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1, 379 GFP_NOFS); 380 if (!name) { 381 err = -ENOMEM; 382 } else { 383 strcpy(name, XATTR_SECURITY_PREFIX); 384 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix); 385 err = __btrfs_setxattr(trans, inode, name, value, len, 0); 386 kfree(name); 387 } 388 389 kfree(suffix); 390 kfree(value); 391 return err; 392 } 393