1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2007 Red Hat. All rights reserved. 4 */ 5 6 #include <linux/init.h> 7 #include <linux/fs.h> 8 #include <linux/slab.h> 9 #include <linux/rwsem.h> 10 #include <linux/xattr.h> 11 #include <linux/security.h> 12 #include <linux/posix_acl_xattr.h> 13 #include <linux/iversion.h> 14 #include "ctree.h" 15 #include "btrfs_inode.h" 16 #include "transaction.h" 17 #include "xattr.h" 18 #include "disk-io.h" 19 #include "props.h" 20 #include "locking.h" 21 22 int btrfs_getxattr(struct inode *inode, const char *name, 23 void *buffer, size_t size) 24 { 25 struct btrfs_dir_item *di; 26 struct btrfs_root *root = BTRFS_I(inode)->root; 27 struct btrfs_path *path; 28 struct extent_buffer *leaf; 29 int ret = 0; 30 unsigned long data_ptr; 31 32 path = btrfs_alloc_path(); 33 if (!path) 34 return -ENOMEM; 35 36 /* lookup the xattr by name */ 37 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)), 38 name, strlen(name), 0); 39 if (!di) { 40 ret = -ENODATA; 41 goto out; 42 } else if (IS_ERR(di)) { 43 ret = PTR_ERR(di); 44 goto out; 45 } 46 47 leaf = path->nodes[0]; 48 /* if size is 0, that means we want the size of the attr */ 49 if (!size) { 50 ret = btrfs_dir_data_len(leaf, di); 51 goto out; 52 } 53 54 /* now get the data out of our dir_item */ 55 if (btrfs_dir_data_len(leaf, di) > size) { 56 ret = -ERANGE; 57 goto out; 58 } 59 60 /* 61 * The way things are packed into the leaf is like this 62 * |struct btrfs_dir_item|name|data| 63 * where name is the xattr name, so security.foo, and data is the 64 * content of the xattr. data_ptr points to the location in memory 65 * where the data starts in the in memory leaf 66 */ 67 data_ptr = (unsigned long)((char *)(di + 1) + 68 btrfs_dir_name_len(leaf, di)); 69 read_extent_buffer(leaf, buffer, data_ptr, 70 btrfs_dir_data_len(leaf, di)); 71 ret = btrfs_dir_data_len(leaf, di); 72 73 out: 74 btrfs_free_path(path); 75 return ret; 76 } 77 78 static int do_setxattr(struct btrfs_trans_handle *trans, 79 struct inode *inode, const char *name, 80 const void *value, size_t size, int flags) 81 { 82 struct btrfs_dir_item *di = NULL; 83 struct btrfs_root *root = BTRFS_I(inode)->root; 84 struct btrfs_fs_info *fs_info = root->fs_info; 85 struct btrfs_path *path; 86 size_t name_len = strlen(name); 87 int ret = 0; 88 89 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) 90 return -ENOSPC; 91 92 path = btrfs_alloc_path(); 93 if (!path) 94 return -ENOMEM; 95 path->skip_release_on_error = 1; 96 97 if (!value) { 98 di = btrfs_lookup_xattr(trans, root, path, 99 btrfs_ino(BTRFS_I(inode)), name, name_len, -1); 100 if (!di && (flags & XATTR_REPLACE)) 101 ret = -ENODATA; 102 else if (IS_ERR(di)) 103 ret = PTR_ERR(di); 104 else if (di) 105 ret = btrfs_delete_one_dir_name(trans, root, path, di); 106 goto out; 107 } 108 109 /* 110 * For a replace we can't just do the insert blindly. 111 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 112 * doesn't exist. If it exists, fall down below to the insert/replace 113 * path - we can't race with a concurrent xattr delete, because the VFS 114 * locks the inode's i_mutex before calling setxattr or removexattr. 115 */ 116 if (flags & XATTR_REPLACE) { 117 ASSERT(inode_is_locked(inode)); 118 di = btrfs_lookup_xattr(NULL, root, path, 119 btrfs_ino(BTRFS_I(inode)), name, name_len, 0); 120 if (!di) 121 ret = -ENODATA; 122 else if (IS_ERR(di)) 123 ret = PTR_ERR(di); 124 if (ret) 125 goto out; 126 btrfs_release_path(path); 127 di = NULL; 128 } 129 130 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), 131 name, name_len, value, size); 132 if (ret == -EOVERFLOW) { 133 /* 134 * We have an existing item in a leaf, split_leaf couldn't 135 * expand it. That item might have or not a dir_item that 136 * matches our target xattr, so lets check. 137 */ 138 ret = 0; 139 btrfs_assert_tree_locked(path->nodes[0]); 140 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 141 if (!di && !(flags & XATTR_REPLACE)) { 142 ret = -ENOSPC; 143 goto out; 144 } 145 } else if (ret == -EEXIST) { 146 ret = 0; 147 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 148 ASSERT(di); /* logic error */ 149 } else if (ret) { 150 goto out; 151 } 152 153 if (di && (flags & XATTR_CREATE)) { 154 ret = -EEXIST; 155 goto out; 156 } 157 158 if (di) { 159 /* 160 * We're doing a replace, and it must be atomic, that is, at 161 * any point in time we have either the old or the new xattr 162 * value in the tree. We don't want readers (getxattr and 163 * listxattrs) to miss a value, this is specially important 164 * for ACLs. 165 */ 166 const int slot = path->slots[0]; 167 struct extent_buffer *leaf = path->nodes[0]; 168 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 169 const u32 item_size = btrfs_item_size_nr(leaf, slot); 170 const u32 data_size = sizeof(*di) + name_len + size; 171 struct btrfs_item *item; 172 unsigned long data_ptr; 173 char *ptr; 174 175 if (size > old_data_len) { 176 if (btrfs_leaf_free_space(fs_info, leaf) < 177 (size - old_data_len)) { 178 ret = -ENOSPC; 179 goto out; 180 } 181 } 182 183 if (old_data_len + name_len + sizeof(*di) == item_size) { 184 /* No other xattrs packed in the same leaf item. */ 185 if (size > old_data_len) 186 btrfs_extend_item(fs_info, path, 187 size - old_data_len); 188 else if (size < old_data_len) 189 btrfs_truncate_item(fs_info, path, 190 data_size, 1); 191 } else { 192 /* There are other xattrs packed in the same item. */ 193 ret = btrfs_delete_one_dir_name(trans, root, path, di); 194 if (ret) 195 goto out; 196 btrfs_extend_item(fs_info, path, data_size); 197 } 198 199 item = btrfs_item_nr(slot); 200 ptr = btrfs_item_ptr(leaf, slot, char); 201 ptr += btrfs_item_size(leaf, item) - data_size; 202 di = (struct btrfs_dir_item *)ptr; 203 btrfs_set_dir_data_len(leaf, di, size); 204 data_ptr = ((unsigned long)(di + 1)) + name_len; 205 write_extent_buffer(leaf, value, data_ptr, size); 206 btrfs_mark_buffer_dirty(leaf); 207 } else { 208 /* 209 * Insert, and we had space for the xattr, so path->slots[0] is 210 * where our xattr dir_item is and btrfs_insert_xattr_item() 211 * filled it. 212 */ 213 } 214 out: 215 btrfs_free_path(path); 216 return ret; 217 } 218 219 /* 220 * @value: "" makes the attribute to empty, NULL removes it 221 */ 222 int btrfs_setxattr(struct btrfs_trans_handle *trans, 223 struct inode *inode, const char *name, 224 const void *value, size_t size, int flags) 225 { 226 struct btrfs_root *root = BTRFS_I(inode)->root; 227 int ret; 228 229 if (btrfs_root_readonly(root)) 230 return -EROFS; 231 232 if (trans) 233 return do_setxattr(trans, inode, name, value, size, flags); 234 235 trans = btrfs_start_transaction(root, 2); 236 if (IS_ERR(trans)) 237 return PTR_ERR(trans); 238 239 ret = do_setxattr(trans, inode, name, value, size, flags); 240 if (ret) 241 goto out; 242 243 inode_inc_iversion(inode); 244 inode->i_ctime = current_time(inode); 245 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 246 ret = btrfs_update_inode(trans, root, inode); 247 BUG_ON(ret); 248 out: 249 btrfs_end_transaction(trans); 250 return ret; 251 } 252 253 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 254 { 255 struct btrfs_key key; 256 struct inode *inode = d_inode(dentry); 257 struct btrfs_root *root = BTRFS_I(inode)->root; 258 struct btrfs_path *path; 259 int ret = 0; 260 size_t total_size = 0, size_left = size; 261 262 /* 263 * ok we want all objects associated with this id. 264 * NOTE: we set key.offset = 0; because we want to start with the 265 * first xattr that we find and walk forward 266 */ 267 key.objectid = btrfs_ino(BTRFS_I(inode)); 268 key.type = BTRFS_XATTR_ITEM_KEY; 269 key.offset = 0; 270 271 path = btrfs_alloc_path(); 272 if (!path) 273 return -ENOMEM; 274 path->reada = READA_FORWARD; 275 276 /* search for our xattrs */ 277 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 278 if (ret < 0) 279 goto err; 280 281 while (1) { 282 struct extent_buffer *leaf; 283 int slot; 284 struct btrfs_dir_item *di; 285 struct btrfs_key found_key; 286 u32 item_size; 287 u32 cur; 288 289 leaf = path->nodes[0]; 290 slot = path->slots[0]; 291 292 /* this is where we start walking through the path */ 293 if (slot >= btrfs_header_nritems(leaf)) { 294 /* 295 * if we've reached the last slot in this leaf we need 296 * to go to the next leaf and reset everything 297 */ 298 ret = btrfs_next_leaf(root, path); 299 if (ret < 0) 300 goto err; 301 else if (ret > 0) 302 break; 303 continue; 304 } 305 306 btrfs_item_key_to_cpu(leaf, &found_key, slot); 307 308 /* check to make sure this item is what we want */ 309 if (found_key.objectid != key.objectid) 310 break; 311 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 312 break; 313 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 314 goto next_item; 315 316 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 317 item_size = btrfs_item_size_nr(leaf, slot); 318 cur = 0; 319 while (cur < item_size) { 320 u16 name_len = btrfs_dir_name_len(leaf, di); 321 u16 data_len = btrfs_dir_data_len(leaf, di); 322 u32 this_len = sizeof(*di) + name_len + data_len; 323 unsigned long name_ptr = (unsigned long)(di + 1); 324 325 total_size += name_len + 1; 326 /* 327 * We are just looking for how big our buffer needs to 328 * be. 329 */ 330 if (!size) 331 goto next; 332 333 if (!buffer || (name_len + 1) > size_left) { 334 ret = -ERANGE; 335 goto err; 336 } 337 338 read_extent_buffer(leaf, buffer, name_ptr, name_len); 339 buffer[name_len] = '\0'; 340 341 size_left -= name_len + 1; 342 buffer += name_len + 1; 343 next: 344 cur += this_len; 345 di = (struct btrfs_dir_item *)((char *)di + this_len); 346 } 347 next_item: 348 path->slots[0]++; 349 } 350 ret = total_size; 351 352 err: 353 btrfs_free_path(path); 354 355 return ret; 356 } 357 358 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 359 struct dentry *unused, struct inode *inode, 360 const char *name, void *buffer, size_t size) 361 { 362 name = xattr_full_name(handler, name); 363 return btrfs_getxattr(inode, name, buffer, size); 364 } 365 366 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 367 struct dentry *unused, struct inode *inode, 368 const char *name, const void *buffer, 369 size_t size, int flags) 370 { 371 name = xattr_full_name(handler, name); 372 return btrfs_setxattr(NULL, inode, name, buffer, size, flags); 373 } 374 375 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 376 struct dentry *unused, struct inode *inode, 377 const char *name, const void *value, 378 size_t size, int flags) 379 { 380 name = xattr_full_name(handler, name); 381 return btrfs_set_prop(inode, name, value, size, flags); 382 } 383 384 static const struct xattr_handler btrfs_security_xattr_handler = { 385 .prefix = XATTR_SECURITY_PREFIX, 386 .get = btrfs_xattr_handler_get, 387 .set = btrfs_xattr_handler_set, 388 }; 389 390 static const struct xattr_handler btrfs_trusted_xattr_handler = { 391 .prefix = XATTR_TRUSTED_PREFIX, 392 .get = btrfs_xattr_handler_get, 393 .set = btrfs_xattr_handler_set, 394 }; 395 396 static const struct xattr_handler btrfs_user_xattr_handler = { 397 .prefix = XATTR_USER_PREFIX, 398 .get = btrfs_xattr_handler_get, 399 .set = btrfs_xattr_handler_set, 400 }; 401 402 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 403 .prefix = XATTR_BTRFS_PREFIX, 404 .get = btrfs_xattr_handler_get, 405 .set = btrfs_xattr_handler_set_prop, 406 }; 407 408 const struct xattr_handler *btrfs_xattr_handlers[] = { 409 &btrfs_security_xattr_handler, 410 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 411 &posix_acl_access_xattr_handler, 412 &posix_acl_default_xattr_handler, 413 #endif 414 &btrfs_trusted_xattr_handler, 415 &btrfs_user_xattr_handler, 416 &btrfs_btrfs_xattr_handler, 417 NULL, 418 }; 419 420 static int btrfs_initxattrs(struct inode *inode, 421 const struct xattr *xattr_array, void *fs_info) 422 { 423 const struct xattr *xattr; 424 struct btrfs_trans_handle *trans = fs_info; 425 char *name; 426 int err = 0; 427 428 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 429 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 430 strlen(xattr->name) + 1, GFP_KERNEL); 431 if (!name) { 432 err = -ENOMEM; 433 break; 434 } 435 strcpy(name, XATTR_SECURITY_PREFIX); 436 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 437 err = btrfs_setxattr(trans, inode, name, xattr->value, 438 xattr->value_len, 0); 439 kfree(name); 440 if (err < 0) 441 break; 442 } 443 return err; 444 } 445 446 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 447 struct inode *inode, struct inode *dir, 448 const struct qstr *qstr) 449 { 450 return security_inode_init_security(inode, dir, qstr, 451 &btrfs_initxattrs, trans); 452 } 453