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 return ret; 217 } 218 219 /* 220 * @value: "" makes the attribute to empty, NULL removes it 221 */ 222 int btrfs_setxattr_trans(struct inode *inode, const char *name, 223 const void *value, size_t size, int flags) 224 { 225 struct btrfs_root *root = BTRFS_I(inode)->root; 226 struct btrfs_trans_handle *trans; 227 int ret; 228 229 trans = btrfs_start_transaction(root, 2); 230 if (IS_ERR(trans)) 231 return PTR_ERR(trans); 232 233 ret = btrfs_setxattr(trans, inode, name, value, size, flags); 234 if (ret) 235 goto out; 236 237 inode_inc_iversion(inode); 238 inode->i_ctime = current_time(inode); 239 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 240 ret = btrfs_update_inode(trans, root, inode); 241 BUG_ON(ret); 242 out: 243 btrfs_end_transaction(trans); 244 return ret; 245 } 246 247 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 248 { 249 struct btrfs_key key; 250 struct inode *inode = d_inode(dentry); 251 struct btrfs_root *root = BTRFS_I(inode)->root; 252 struct btrfs_path *path; 253 int ret = 0; 254 size_t total_size = 0, size_left = size; 255 256 /* 257 * ok we want all objects associated with this id. 258 * NOTE: we set key.offset = 0; because we want to start with the 259 * first xattr that we find and walk forward 260 */ 261 key.objectid = btrfs_ino(BTRFS_I(inode)); 262 key.type = BTRFS_XATTR_ITEM_KEY; 263 key.offset = 0; 264 265 path = btrfs_alloc_path(); 266 if (!path) 267 return -ENOMEM; 268 path->reada = READA_FORWARD; 269 270 /* search for our xattrs */ 271 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 272 if (ret < 0) 273 goto err; 274 275 while (1) { 276 struct extent_buffer *leaf; 277 int slot; 278 struct btrfs_dir_item *di; 279 struct btrfs_key found_key; 280 u32 item_size; 281 u32 cur; 282 283 leaf = path->nodes[0]; 284 slot = path->slots[0]; 285 286 /* this is where we start walking through the path */ 287 if (slot >= btrfs_header_nritems(leaf)) { 288 /* 289 * if we've reached the last slot in this leaf we need 290 * to go to the next leaf and reset everything 291 */ 292 ret = btrfs_next_leaf(root, path); 293 if (ret < 0) 294 goto err; 295 else if (ret > 0) 296 break; 297 continue; 298 } 299 300 btrfs_item_key_to_cpu(leaf, &found_key, slot); 301 302 /* check to make sure this item is what we want */ 303 if (found_key.objectid != key.objectid) 304 break; 305 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 306 break; 307 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 308 goto next_item; 309 310 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 311 item_size = btrfs_item_size_nr(leaf, slot); 312 cur = 0; 313 while (cur < item_size) { 314 u16 name_len = btrfs_dir_name_len(leaf, di); 315 u16 data_len = btrfs_dir_data_len(leaf, di); 316 u32 this_len = sizeof(*di) + name_len + data_len; 317 unsigned long name_ptr = (unsigned long)(di + 1); 318 319 total_size += name_len + 1; 320 /* 321 * We are just looking for how big our buffer needs to 322 * be. 323 */ 324 if (!size) 325 goto next; 326 327 if (!buffer || (name_len + 1) > size_left) { 328 ret = -ERANGE; 329 goto err; 330 } 331 332 read_extent_buffer(leaf, buffer, name_ptr, name_len); 333 buffer[name_len] = '\0'; 334 335 size_left -= name_len + 1; 336 buffer += name_len + 1; 337 next: 338 cur += this_len; 339 di = (struct btrfs_dir_item *)((char *)di + this_len); 340 } 341 next_item: 342 path->slots[0]++; 343 } 344 ret = total_size; 345 346 err: 347 btrfs_free_path(path); 348 349 return ret; 350 } 351 352 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 353 struct dentry *unused, struct inode *inode, 354 const char *name, void *buffer, size_t size) 355 { 356 name = xattr_full_name(handler, name); 357 return btrfs_getxattr(inode, name, buffer, size); 358 } 359 360 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 361 struct dentry *unused, struct inode *inode, 362 const char *name, const void *buffer, 363 size_t size, int flags) 364 { 365 name = xattr_full_name(handler, name); 366 return btrfs_setxattr_trans(inode, name, buffer, size, flags); 367 } 368 369 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 370 struct dentry *unused, struct inode *inode, 371 const char *name, const void *value, 372 size_t size, int flags) 373 { 374 int ret; 375 struct btrfs_trans_handle *trans; 376 struct btrfs_root *root = BTRFS_I(inode)->root; 377 378 name = xattr_full_name(handler, name); 379 ret = btrfs_validate_prop(name, value, size); 380 if (ret) 381 return ret; 382 383 trans = btrfs_start_transaction(root, 2); 384 if (IS_ERR(trans)) 385 return PTR_ERR(trans); 386 387 ret = btrfs_set_prop(trans, inode, name, value, size, flags); 388 if (!ret) { 389 inode_inc_iversion(inode); 390 inode->i_ctime = current_time(inode); 391 set_bit(BTRFS_INODE_COPY_EVERYTHING, 392 &BTRFS_I(inode)->runtime_flags); 393 ret = btrfs_update_inode(trans, root, inode); 394 BUG_ON(ret); 395 } 396 397 btrfs_end_transaction(trans); 398 399 return ret; 400 } 401 402 static const struct xattr_handler btrfs_security_xattr_handler = { 403 .prefix = XATTR_SECURITY_PREFIX, 404 .get = btrfs_xattr_handler_get, 405 .set = btrfs_xattr_handler_set, 406 }; 407 408 static const struct xattr_handler btrfs_trusted_xattr_handler = { 409 .prefix = XATTR_TRUSTED_PREFIX, 410 .get = btrfs_xattr_handler_get, 411 .set = btrfs_xattr_handler_set, 412 }; 413 414 static const struct xattr_handler btrfs_user_xattr_handler = { 415 .prefix = XATTR_USER_PREFIX, 416 .get = btrfs_xattr_handler_get, 417 .set = btrfs_xattr_handler_set, 418 }; 419 420 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 421 .prefix = XATTR_BTRFS_PREFIX, 422 .get = btrfs_xattr_handler_get, 423 .set = btrfs_xattr_handler_set_prop, 424 }; 425 426 const struct xattr_handler *btrfs_xattr_handlers[] = { 427 &btrfs_security_xattr_handler, 428 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 429 &posix_acl_access_xattr_handler, 430 &posix_acl_default_xattr_handler, 431 #endif 432 &btrfs_trusted_xattr_handler, 433 &btrfs_user_xattr_handler, 434 &btrfs_btrfs_xattr_handler, 435 NULL, 436 }; 437 438 static int btrfs_initxattrs(struct inode *inode, 439 const struct xattr *xattr_array, void *fs_private) 440 { 441 struct btrfs_trans_handle *trans = fs_private; 442 const struct xattr *xattr; 443 unsigned int nofs_flag; 444 char *name; 445 int err = 0; 446 447 /* 448 * We're holding a transaction handle, so use a NOFS memory allocation 449 * context to avoid deadlock if reclaim happens. 450 */ 451 nofs_flag = memalloc_nofs_save(); 452 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 453 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 454 strlen(xattr->name) + 1, GFP_KERNEL); 455 if (!name) { 456 err = -ENOMEM; 457 break; 458 } 459 strcpy(name, XATTR_SECURITY_PREFIX); 460 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 461 err = btrfs_setxattr(trans, inode, name, xattr->value, 462 xattr->value_len, 0); 463 kfree(name); 464 if (err < 0) 465 break; 466 } 467 memalloc_nofs_restore(nofs_flag); 468 return err; 469 } 470 471 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 472 struct inode *inode, struct inode *dir, 473 const struct qstr *qstr) 474 { 475 return security_inode_init_security(inode, dir, qstr, 476 &btrfs_initxattrs, trans); 477 } 478