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 /* first lets see if we already have this xattr */ 106 di = btrfs_lookup_xattr(trans, root, path, btrfs_ino(inode), 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(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(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, btrfs_ino(inode), 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 trans = btrfs_start_transaction(root, 2); 158 if (IS_ERR(trans)) 159 return PTR_ERR(trans); 160 161 ret = do_setxattr(trans, inode, name, value, size, flags); 162 if (ret) 163 goto out; 164 165 inode->i_ctime = CURRENT_TIME; 166 ret = btrfs_update_inode(trans, root, inode); 167 BUG_ON(ret); 168 out: 169 btrfs_end_transaction_throttle(trans, root); 170 return ret; 171 } 172 173 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 174 { 175 struct btrfs_key key, found_key; 176 struct inode *inode = dentry->d_inode; 177 struct btrfs_root *root = BTRFS_I(inode)->root; 178 struct btrfs_path *path; 179 struct extent_buffer *leaf; 180 struct btrfs_dir_item *di; 181 int ret = 0, slot; 182 size_t total_size = 0, size_left = size; 183 unsigned long name_ptr; 184 size_t name_len; 185 186 /* 187 * ok we want all objects associated with this id. 188 * NOTE: we set key.offset = 0; because we want to start with the 189 * first xattr that we find and walk forward 190 */ 191 key.objectid = btrfs_ino(inode); 192 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 193 key.offset = 0; 194 195 path = btrfs_alloc_path(); 196 if (!path) 197 return -ENOMEM; 198 path->reada = 2; 199 200 /* search for our xattrs */ 201 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 202 if (ret < 0) 203 goto err; 204 205 while (1) { 206 leaf = path->nodes[0]; 207 slot = path->slots[0]; 208 209 /* this is where we start walking through the path */ 210 if (slot >= btrfs_header_nritems(leaf)) { 211 /* 212 * if we've reached the last slot in this leaf we need 213 * to go to the next leaf and reset everything 214 */ 215 ret = btrfs_next_leaf(root, path); 216 if (ret < 0) 217 goto err; 218 else if (ret > 0) 219 break; 220 continue; 221 } 222 223 btrfs_item_key_to_cpu(leaf, &found_key, slot); 224 225 /* check to make sure this item is what we want */ 226 if (found_key.objectid != key.objectid) 227 break; 228 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 229 break; 230 231 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 232 if (verify_dir_item(root, leaf, di)) 233 continue; 234 235 name_len = btrfs_dir_name_len(leaf, di); 236 total_size += name_len + 1; 237 238 /* we are just looking for how big our buffer needs to be */ 239 if (!size) 240 goto next; 241 242 if (!buffer || (name_len + 1) > size_left) { 243 ret = -ERANGE; 244 goto err; 245 } 246 247 name_ptr = (unsigned long)(di + 1); 248 read_extent_buffer(leaf, buffer, name_ptr, name_len); 249 buffer[name_len] = '\0'; 250 251 size_left -= name_len + 1; 252 buffer += name_len + 1; 253 next: 254 path->slots[0]++; 255 } 256 ret = total_size; 257 258 err: 259 btrfs_free_path(path); 260 261 return ret; 262 } 263 264 /* 265 * List of handlers for synthetic system.* attributes. All real ondisk 266 * attributes are handled directly. 267 */ 268 const struct xattr_handler *btrfs_xattr_handlers[] = { 269 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 270 &btrfs_xattr_acl_access_handler, 271 &btrfs_xattr_acl_default_handler, 272 #endif 273 NULL, 274 }; 275 276 /* 277 * Check if the attribute is in a supported namespace. 278 * 279 * This applied after the check for the synthetic attributes in the system 280 * namespace. 281 */ 282 static bool btrfs_is_valid_xattr(const char *name) 283 { 284 return !strncmp(name, XATTR_SECURITY_PREFIX, 285 XATTR_SECURITY_PREFIX_LEN) || 286 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 287 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 288 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 289 } 290 291 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 292 void *buffer, size_t size) 293 { 294 /* 295 * If this is a request for a synthetic attribute in the system.* 296 * namespace use the generic infrastructure to resolve a handler 297 * for it via sb->s_xattr. 298 */ 299 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 300 return generic_getxattr(dentry, name, buffer, size); 301 302 if (!btrfs_is_valid_xattr(name)) 303 return -EOPNOTSUPP; 304 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 305 } 306 307 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 308 size_t size, int flags) 309 { 310 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 311 312 /* 313 * The permission on security.* and system.* is not checked 314 * in permission(). 315 */ 316 if (btrfs_root_readonly(root)) 317 return -EROFS; 318 319 /* 320 * If this is a request for a synthetic attribute in the system.* 321 * namespace use the generic infrastructure to resolve a handler 322 * for it via sb->s_xattr. 323 */ 324 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 325 return generic_setxattr(dentry, name, value, size, flags); 326 327 if (!btrfs_is_valid_xattr(name)) 328 return -EOPNOTSUPP; 329 330 if (size == 0) 331 value = ""; /* empty EA, do not remove */ 332 333 return __btrfs_setxattr(NULL, dentry->d_inode, name, value, size, 334 flags); 335 } 336 337 int btrfs_removexattr(struct dentry *dentry, const char *name) 338 { 339 struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root; 340 341 /* 342 * The permission on security.* and system.* is not checked 343 * in permission(). 344 */ 345 if (btrfs_root_readonly(root)) 346 return -EROFS; 347 348 /* 349 * If this is a request for a synthetic attribute in the system.* 350 * namespace use the generic infrastructure to resolve a handler 351 * for it via sb->s_xattr. 352 */ 353 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 354 return generic_removexattr(dentry, name); 355 356 if (!btrfs_is_valid_xattr(name)) 357 return -EOPNOTSUPP; 358 359 return __btrfs_setxattr(NULL, dentry->d_inode, name, NULL, 0, 360 XATTR_REPLACE); 361 } 362 363 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 364 struct inode *inode, struct inode *dir, 365 const struct qstr *qstr) 366 { 367 int err; 368 size_t len; 369 void *value; 370 char *suffix; 371 char *name; 372 373 err = security_inode_init_security(inode, dir, qstr, &suffix, &value, 374 &len); 375 if (err) { 376 if (err == -EOPNOTSUPP) 377 return 0; 378 return err; 379 } 380 381 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1, 382 GFP_NOFS); 383 if (!name) { 384 err = -ENOMEM; 385 } else { 386 strcpy(name, XATTR_SECURITY_PREFIX); 387 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix); 388 err = __btrfs_setxattr(trans, inode, name, value, len, 0); 389 kfree(name); 390 } 391 392 kfree(suffix); 393 kfree(value); 394 return err; 395 } 396