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 <linux/sched/mm.h> 15 #include "ctree.h" 16 #include "btrfs_inode.h" 17 #include "transaction.h" 18 #include "xattr.h" 19 #include "disk-io.h" 20 #include "props.h" 21 #include "locking.h" 22 23 int btrfs_getxattr(struct inode *inode, const char *name, 24 void *buffer, size_t size) 25 { 26 struct btrfs_dir_item *di; 27 struct btrfs_root *root = BTRFS_I(inode)->root; 28 struct btrfs_path *path; 29 struct extent_buffer *leaf; 30 int ret = 0; 31 unsigned long data_ptr; 32 33 path = btrfs_alloc_path(); 34 if (!path) 35 return -ENOMEM; 36 37 /* lookup the xattr by name */ 38 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)), 39 name, strlen(name), 0); 40 if (!di) { 41 ret = -ENODATA; 42 goto out; 43 } else if (IS_ERR(di)) { 44 ret = PTR_ERR(di); 45 goto out; 46 } 47 48 leaf = path->nodes[0]; 49 /* if size is 0, that means we want the size of the attr */ 50 if (!size) { 51 ret = btrfs_dir_data_len(leaf, di); 52 goto out; 53 } 54 55 /* now get the data out of our dir_item */ 56 if (btrfs_dir_data_len(leaf, di) > size) { 57 ret = -ERANGE; 58 goto out; 59 } 60 61 /* 62 * The way things are packed into the leaf is like this 63 * |struct btrfs_dir_item|name|data| 64 * where name is the xattr name, so security.foo, and data is the 65 * content of the xattr. data_ptr points to the location in memory 66 * where the data starts in the in memory leaf 67 */ 68 data_ptr = (unsigned long)((char *)(di + 1) + 69 btrfs_dir_name_len(leaf, di)); 70 read_extent_buffer(leaf, buffer, data_ptr, 71 btrfs_dir_data_len(leaf, di)); 72 ret = btrfs_dir_data_len(leaf, di); 73 74 out: 75 btrfs_free_path(path); 76 return ret; 77 } 78 79 int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode, 80 const char *name, 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 ASSERT(trans); 90 91 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) 92 return -ENOSPC; 93 94 path = btrfs_alloc_path(); 95 if (!path) 96 return -ENOMEM; 97 path->skip_release_on_error = 1; 98 99 if (!value) { 100 di = btrfs_lookup_xattr(trans, root, path, 101 btrfs_ino(BTRFS_I(inode)), name, name_len, -1); 102 if (!di && (flags & XATTR_REPLACE)) 103 ret = -ENODATA; 104 else if (IS_ERR(di)) 105 ret = PTR_ERR(di); 106 else if (di) 107 ret = btrfs_delete_one_dir_name(trans, root, path, di); 108 goto out; 109 } 110 111 /* 112 * For a replace we can't just do the insert blindly. 113 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 114 * doesn't exist. If it exists, fall down below to the insert/replace 115 * path - we can't race with a concurrent xattr delete, because the VFS 116 * locks the inode's i_mutex before calling setxattr or removexattr. 117 */ 118 if (flags & XATTR_REPLACE) { 119 ASSERT(inode_is_locked(inode)); 120 di = btrfs_lookup_xattr(NULL, root, path, 121 btrfs_ino(BTRFS_I(inode)), name, name_len, 0); 122 if (!di) 123 ret = -ENODATA; 124 else if (IS_ERR(di)) 125 ret = PTR_ERR(di); 126 if (ret) 127 goto out; 128 btrfs_release_path(path); 129 di = NULL; 130 } 131 132 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), 133 name, name_len, value, size); 134 if (ret == -EOVERFLOW) { 135 /* 136 * We have an existing item in a leaf, split_leaf couldn't 137 * expand it. That item might have or not a dir_item that 138 * matches our target xattr, so lets check. 139 */ 140 ret = 0; 141 btrfs_assert_tree_locked(path->nodes[0]); 142 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 143 if (!di && !(flags & XATTR_REPLACE)) { 144 ret = -ENOSPC; 145 goto out; 146 } 147 } else if (ret == -EEXIST) { 148 ret = 0; 149 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 150 ASSERT(di); /* logic error */ 151 } else if (ret) { 152 goto out; 153 } 154 155 if (di && (flags & XATTR_CREATE)) { 156 ret = -EEXIST; 157 goto out; 158 } 159 160 if (di) { 161 /* 162 * We're doing a replace, and it must be atomic, that is, at 163 * any point in time we have either the old or the new xattr 164 * value in the tree. We don't want readers (getxattr and 165 * listxattrs) to miss a value, this is specially important 166 * for ACLs. 167 */ 168 const int slot = path->slots[0]; 169 struct extent_buffer *leaf = path->nodes[0]; 170 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 171 const u32 item_size = btrfs_item_size_nr(leaf, slot); 172 const u32 data_size = sizeof(*di) + name_len + size; 173 struct btrfs_item *item; 174 unsigned long data_ptr; 175 char *ptr; 176 177 if (size > old_data_len) { 178 if (btrfs_leaf_free_space(leaf) < 179 (size - old_data_len)) { 180 ret = -ENOSPC; 181 goto out; 182 } 183 } 184 185 if (old_data_len + name_len + sizeof(*di) == item_size) { 186 /* No other xattrs packed in the same leaf item. */ 187 if (size > old_data_len) 188 btrfs_extend_item(path, size - old_data_len); 189 else if (size < old_data_len) 190 btrfs_truncate_item(path, 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(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 if (!ret) { 217 set_bit(BTRFS_INODE_COPY_EVERYTHING, 218 &BTRFS_I(inode)->runtime_flags); 219 clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags); 220 } 221 return ret; 222 } 223 224 /* 225 * @value: "" makes the attribute to empty, NULL removes it 226 */ 227 int btrfs_setxattr_trans(struct inode *inode, const char *name, 228 const void *value, size_t size, int flags) 229 { 230 struct btrfs_root *root = BTRFS_I(inode)->root; 231 struct btrfs_trans_handle *trans; 232 int ret; 233 234 trans = btrfs_start_transaction(root, 2); 235 if (IS_ERR(trans)) 236 return PTR_ERR(trans); 237 238 ret = btrfs_setxattr(trans, inode, name, value, size, flags); 239 if (ret) 240 goto out; 241 242 inode_inc_iversion(inode); 243 inode->i_ctime = current_time(inode); 244 ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); 245 BUG_ON(ret); 246 out: 247 btrfs_end_transaction(trans); 248 return ret; 249 } 250 251 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 252 { 253 struct btrfs_key key; 254 struct inode *inode = d_inode(dentry); 255 struct btrfs_root *root = BTRFS_I(inode)->root; 256 struct btrfs_path *path; 257 int ret = 0; 258 size_t total_size = 0, size_left = size; 259 260 /* 261 * ok we want all objects associated with this id. 262 * NOTE: we set key.offset = 0; because we want to start with the 263 * first xattr that we find and walk forward 264 */ 265 key.objectid = btrfs_ino(BTRFS_I(inode)); 266 key.type = BTRFS_XATTR_ITEM_KEY; 267 key.offset = 0; 268 269 path = btrfs_alloc_path(); 270 if (!path) 271 return -ENOMEM; 272 path->reada = READA_FORWARD; 273 274 /* search for our xattrs */ 275 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 276 if (ret < 0) 277 goto err; 278 279 while (1) { 280 struct extent_buffer *leaf; 281 int slot; 282 struct btrfs_dir_item *di; 283 struct btrfs_key found_key; 284 u32 item_size; 285 u32 cur; 286 287 leaf = path->nodes[0]; 288 slot = path->slots[0]; 289 290 /* this is where we start walking through the path */ 291 if (slot >= btrfs_header_nritems(leaf)) { 292 /* 293 * if we've reached the last slot in this leaf we need 294 * to go to the next leaf and reset everything 295 */ 296 ret = btrfs_next_leaf(root, path); 297 if (ret < 0) 298 goto err; 299 else if (ret > 0) 300 break; 301 continue; 302 } 303 304 btrfs_item_key_to_cpu(leaf, &found_key, slot); 305 306 /* check to make sure this item is what we want */ 307 if (found_key.objectid != key.objectid) 308 break; 309 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 310 break; 311 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 312 goto next_item; 313 314 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 315 item_size = btrfs_item_size_nr(leaf, slot); 316 cur = 0; 317 while (cur < item_size) { 318 u16 name_len = btrfs_dir_name_len(leaf, di); 319 u16 data_len = btrfs_dir_data_len(leaf, di); 320 u32 this_len = sizeof(*di) + name_len + data_len; 321 unsigned long name_ptr = (unsigned long)(di + 1); 322 323 total_size += name_len + 1; 324 /* 325 * We are just looking for how big our buffer needs to 326 * be. 327 */ 328 if (!size) 329 goto next; 330 331 if (!buffer || (name_len + 1) > size_left) { 332 ret = -ERANGE; 333 goto err; 334 } 335 336 read_extent_buffer(leaf, buffer, name_ptr, name_len); 337 buffer[name_len] = '\0'; 338 339 size_left -= name_len + 1; 340 buffer += name_len + 1; 341 next: 342 cur += this_len; 343 di = (struct btrfs_dir_item *)((char *)di + this_len); 344 } 345 next_item: 346 path->slots[0]++; 347 } 348 ret = total_size; 349 350 err: 351 btrfs_free_path(path); 352 353 return ret; 354 } 355 356 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 357 struct dentry *unused, struct inode *inode, 358 const char *name, void *buffer, size_t size) 359 { 360 name = xattr_full_name(handler, name); 361 return btrfs_getxattr(inode, name, buffer, size); 362 } 363 364 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 365 struct dentry *unused, struct inode *inode, 366 const char *name, const void *buffer, 367 size_t size, int flags) 368 { 369 name = xattr_full_name(handler, name); 370 return btrfs_setxattr_trans(inode, name, buffer, size, flags); 371 } 372 373 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 374 struct dentry *unused, struct inode *inode, 375 const char *name, const void *value, 376 size_t size, int flags) 377 { 378 int ret; 379 struct btrfs_trans_handle *trans; 380 struct btrfs_root *root = BTRFS_I(inode)->root; 381 382 name = xattr_full_name(handler, name); 383 ret = btrfs_validate_prop(name, value, size); 384 if (ret) 385 return ret; 386 387 trans = btrfs_start_transaction(root, 2); 388 if (IS_ERR(trans)) 389 return PTR_ERR(trans); 390 391 ret = btrfs_set_prop(trans, inode, name, value, size, flags); 392 if (!ret) { 393 inode_inc_iversion(inode); 394 inode->i_ctime = current_time(inode); 395 ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); 396 BUG_ON(ret); 397 } 398 399 btrfs_end_transaction(trans); 400 401 return ret; 402 } 403 404 static const struct xattr_handler btrfs_security_xattr_handler = { 405 .prefix = XATTR_SECURITY_PREFIX, 406 .get = btrfs_xattr_handler_get, 407 .set = btrfs_xattr_handler_set, 408 }; 409 410 static const struct xattr_handler btrfs_trusted_xattr_handler = { 411 .prefix = XATTR_TRUSTED_PREFIX, 412 .get = btrfs_xattr_handler_get, 413 .set = btrfs_xattr_handler_set, 414 }; 415 416 static const struct xattr_handler btrfs_user_xattr_handler = { 417 .prefix = XATTR_USER_PREFIX, 418 .get = btrfs_xattr_handler_get, 419 .set = btrfs_xattr_handler_set, 420 }; 421 422 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 423 .prefix = XATTR_BTRFS_PREFIX, 424 .get = btrfs_xattr_handler_get, 425 .set = btrfs_xattr_handler_set_prop, 426 }; 427 428 const struct xattr_handler *btrfs_xattr_handlers[] = { 429 &btrfs_security_xattr_handler, 430 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 431 &posix_acl_access_xattr_handler, 432 &posix_acl_default_xattr_handler, 433 #endif 434 &btrfs_trusted_xattr_handler, 435 &btrfs_user_xattr_handler, 436 &btrfs_btrfs_xattr_handler, 437 NULL, 438 }; 439 440 static int btrfs_initxattrs(struct inode *inode, 441 const struct xattr *xattr_array, void *fs_private) 442 { 443 struct btrfs_trans_handle *trans = fs_private; 444 const struct xattr *xattr; 445 unsigned int nofs_flag; 446 char *name; 447 int err = 0; 448 449 /* 450 * We're holding a transaction handle, so use a NOFS memory allocation 451 * context to avoid deadlock if reclaim happens. 452 */ 453 nofs_flag = memalloc_nofs_save(); 454 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 455 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 456 strlen(xattr->name) + 1, GFP_KERNEL); 457 if (!name) { 458 err = -ENOMEM; 459 break; 460 } 461 strcpy(name, XATTR_SECURITY_PREFIX); 462 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 463 err = btrfs_setxattr(trans, inode, name, xattr->value, 464 xattr->value_len, 0); 465 kfree(name); 466 if (err < 0) 467 break; 468 } 469 memalloc_nofs_restore(nofs_flag); 470 return err; 471 } 472 473 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 474 struct inode *inode, struct inode *dir, 475 const struct qstr *qstr) 476 { 477 return security_inode_init_security(inode, dir, qstr, 478 &btrfs_initxattrs, trans); 479 } 480