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