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 int __btrfs_setxattr(struct inode *inode, const char *name, 89 const void *value, size_t size, int flags) 90 { 91 struct btrfs_dir_item *di; 92 struct btrfs_root *root = BTRFS_I(inode)->root; 93 struct btrfs_trans_handle *trans; 94 struct btrfs_path *path; 95 int ret = 0, mod = 0; 96 97 path = btrfs_alloc_path(); 98 if (!path) 99 return -ENOMEM; 100 101 trans = btrfs_join_transaction(root, 1); 102 btrfs_set_trans_block_group(trans, inode); 103 104 /* first lets see if we already have this xattr */ 105 di = btrfs_lookup_xattr(trans, root, path, inode->i_ino, name, 106 strlen(name), -1); 107 if (IS_ERR(di)) { 108 ret = PTR_ERR(di); 109 goto out; 110 } 111 112 /* ok we already have this xattr, lets remove it */ 113 if (di) { 114 /* if we want create only exit */ 115 if (flags & XATTR_CREATE) { 116 ret = -EEXIST; 117 goto out; 118 } 119 120 ret = btrfs_delete_one_dir_name(trans, root, path, di); 121 if (ret) 122 goto out; 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 mod = 1; 128 goto out; 129 } 130 } else { 131 btrfs_release_path(root, path); 132 133 if (flags & XATTR_REPLACE) { 134 /* we couldn't find the attr to replace */ 135 ret = -ENODATA; 136 goto out; 137 } 138 } 139 140 /* ok we have to create a completely new xattr */ 141 ret = btrfs_insert_xattr_item(trans, root, name, strlen(name), 142 value, size, inode->i_ino); 143 if (ret) 144 goto out; 145 mod = 1; 146 147 out: 148 if (mod) { 149 inode->i_ctime = CURRENT_TIME; 150 ret = btrfs_update_inode(trans, root, inode); 151 } 152 153 btrfs_end_transaction(trans, root); 154 btrfs_free_path(path); 155 return ret; 156 } 157 158 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 159 { 160 struct btrfs_key key, found_key; 161 struct inode *inode = dentry->d_inode; 162 struct btrfs_root *root = BTRFS_I(inode)->root; 163 struct btrfs_path *path; 164 struct btrfs_item *item; 165 struct extent_buffer *leaf; 166 struct btrfs_dir_item *di; 167 int ret = 0, slot, advance; 168 size_t total_size = 0, size_left = size; 169 unsigned long name_ptr; 170 size_t name_len; 171 u32 nritems; 172 173 /* 174 * ok we want all objects associated with this id. 175 * NOTE: we set key.offset = 0; because we want to start with the 176 * first xattr that we find and walk forward 177 */ 178 key.objectid = inode->i_ino; 179 btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY); 180 key.offset = 0; 181 182 path = btrfs_alloc_path(); 183 if (!path) 184 return -ENOMEM; 185 path->reada = 2; 186 187 /* search for our xattrs */ 188 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 189 if (ret < 0) 190 goto err; 191 advance = 0; 192 while (1) { 193 leaf = path->nodes[0]; 194 nritems = btrfs_header_nritems(leaf); 195 slot = path->slots[0]; 196 197 /* this is where we start walking through the path */ 198 if (advance || slot >= nritems) { 199 /* 200 * if we've reached the last slot in this leaf we need 201 * to go to the next leaf and reset everything 202 */ 203 if (slot >= nritems-1) { 204 ret = btrfs_next_leaf(root, path); 205 if (ret) 206 break; 207 leaf = path->nodes[0]; 208 nritems = btrfs_header_nritems(leaf); 209 slot = path->slots[0]; 210 } else { 211 /* 212 * just walking through the slots on this leaf 213 */ 214 slot++; 215 path->slots[0]++; 216 } 217 } 218 advance = 1; 219 220 item = btrfs_item_nr(leaf, slot); 221 btrfs_item_key_to_cpu(leaf, &found_key, slot); 222 223 /* check to make sure this item is what we want */ 224 if (found_key.objectid != key.objectid) 225 break; 226 if (btrfs_key_type(&found_key) != BTRFS_XATTR_ITEM_KEY) 227 break; 228 229 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 230 231 name_len = btrfs_dir_name_len(leaf, di); 232 total_size += name_len + 1; 233 234 /* we are just looking for how big our buffer needs to be */ 235 if (!size) 236 continue; 237 238 if (!buffer || (name_len + 1) > size_left) { 239 ret = -ERANGE; 240 goto err; 241 } 242 243 name_ptr = (unsigned long)(di + 1); 244 read_extent_buffer(leaf, buffer, name_ptr, name_len); 245 buffer[name_len] = '\0'; 246 247 size_left -= name_len + 1; 248 buffer += name_len + 1; 249 } 250 ret = total_size; 251 252 err: 253 btrfs_free_path(path); 254 255 return ret; 256 } 257 258 /* 259 * List of handlers for synthetic system.* attributes. All real ondisk 260 * attributes are handled directly. 261 */ 262 struct xattr_handler *btrfs_xattr_handlers[] = { 263 #ifdef CONFIG_FS_POSIX_ACL 264 &btrfs_xattr_acl_access_handler, 265 &btrfs_xattr_acl_default_handler, 266 #endif 267 NULL, 268 }; 269 270 /* 271 * Check if the attribute is in a supported namespace. 272 * 273 * This applied after the check for the synthetic attributes in the system 274 * namespace. 275 */ 276 static bool btrfs_is_valid_xattr(const char *name) 277 { 278 return !strncmp(name, XATTR_SECURITY_PREFIX, 279 XATTR_SECURITY_PREFIX_LEN) || 280 !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN) || 281 !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) || 282 !strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN); 283 } 284 285 ssize_t btrfs_getxattr(struct dentry *dentry, const char *name, 286 void *buffer, size_t size) 287 { 288 /* 289 * If this is a request for a synthetic attribute in the system.* 290 * namespace use the generic infrastructure to resolve a handler 291 * for it via sb->s_xattr. 292 */ 293 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 294 return generic_getxattr(dentry, name, buffer, size); 295 296 if (!btrfs_is_valid_xattr(name)) 297 return -EOPNOTSUPP; 298 return __btrfs_getxattr(dentry->d_inode, name, buffer, size); 299 } 300 301 int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value, 302 size_t size, int flags) 303 { 304 /* 305 * If this is a request for a synthetic attribute in the system.* 306 * namespace use the generic infrastructure to resolve a handler 307 * for it via sb->s_xattr. 308 */ 309 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 310 return generic_setxattr(dentry, name, value, size, flags); 311 312 if (!btrfs_is_valid_xattr(name)) 313 return -EOPNOTSUPP; 314 315 if (size == 0) 316 value = ""; /* empty EA, do not remove */ 317 return __btrfs_setxattr(dentry->d_inode, name, value, size, flags); 318 } 319 320 int btrfs_removexattr(struct dentry *dentry, const char *name) 321 { 322 /* 323 * If this is a request for a synthetic attribute in the system.* 324 * namespace use the generic infrastructure to resolve a handler 325 * for it via sb->s_xattr. 326 */ 327 if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) 328 return generic_removexattr(dentry, name); 329 330 if (!btrfs_is_valid_xattr(name)) 331 return -EOPNOTSUPP; 332 return __btrfs_setxattr(dentry->d_inode, name, NULL, 0, XATTR_REPLACE); 333 } 334 335 int btrfs_xattr_security_init(struct inode *inode, struct inode *dir) 336 { 337 int err; 338 size_t len; 339 void *value; 340 char *suffix; 341 char *name; 342 343 err = security_inode_init_security(inode, dir, &suffix, &value, &len); 344 if (err) { 345 if (err == -EOPNOTSUPP) 346 return 0; 347 return err; 348 } 349 350 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + strlen(suffix) + 1, 351 GFP_NOFS); 352 if (!name) { 353 err = -ENOMEM; 354 } else { 355 strcpy(name, XATTR_SECURITY_PREFIX); 356 strcpy(name + XATTR_SECURITY_PREFIX_LEN, suffix); 357 err = __btrfs_setxattr(inode, name, value, len, 0); 358 kfree(name); 359 } 360 361 kfree(suffix); 362 kfree(value); 363 return err; 364 } 365