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 "fs.h" 17#include "messages.h" 18#include "btrfs_inode.h" 19#include "transaction.h" 20#include "xattr.h" 21#include "disk-io.h" 22#include "props.h" 23#include "locking.h" 24#include "accessors.h" 25#include "dir-item.h" 26 27int btrfs_getxattr(struct inode *inode, const char *name, 28 void *buffer, size_t size) 29{ 30 struct btrfs_dir_item *di; 31 struct btrfs_root *root = BTRFS_I(inode)->root; 32 struct btrfs_path *path; 33 struct extent_buffer *leaf; 34 int ret = 0; 35 unsigned long data_ptr; 36 37 path = btrfs_alloc_path(); 38 if (!path) 39 return -ENOMEM; 40 41 /* lookup the xattr by name */ 42 di = btrfs_lookup_xattr(NULL, root, path, btrfs_ino(BTRFS_I(inode)), 43 name, strlen(name), 0); 44 if (!di) { 45 ret = -ENODATA; 46 goto out; 47 } else if (IS_ERR(di)) { 48 ret = PTR_ERR(di); 49 goto out; 50 } 51 52 leaf = path->nodes[0]; 53 /* if size is 0, that means we want the size of the attr */ 54 if (!size) { 55 ret = btrfs_dir_data_len(leaf, di); 56 goto out; 57 } 58 59 /* now get the data out of our dir_item */ 60 if (btrfs_dir_data_len(leaf, di) > size) { 61 ret = -ERANGE; 62 goto out; 63 } 64 65 /* 66 * The way things are packed into the leaf is like this 67 * |struct btrfs_dir_item|name|data| 68 * where name is the xattr name, so security.foo, and data is the 69 * content of the xattr. data_ptr points to the location in memory 70 * where the data starts in the in memory leaf 71 */ 72 data_ptr = (unsigned long)((char *)(di + 1) + 73 btrfs_dir_name_len(leaf, di)); 74 read_extent_buffer(leaf, buffer, data_ptr, 75 btrfs_dir_data_len(leaf, di)); 76 ret = btrfs_dir_data_len(leaf, di); 77 78out: 79 btrfs_free_path(path); 80 return ret; 81} 82 83int btrfs_setxattr(struct btrfs_trans_handle *trans, struct inode *inode, 84 const char *name, const void *value, size_t size, int flags) 85{ 86 struct btrfs_dir_item *di = NULL; 87 struct btrfs_root *root = BTRFS_I(inode)->root; 88 struct btrfs_fs_info *fs_info = root->fs_info; 89 struct btrfs_path *path; 90 size_t name_len = strlen(name); 91 int ret = 0; 92 93 ASSERT(trans); 94 95 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) 96 return -ENOSPC; 97 98 path = btrfs_alloc_path(); 99 if (!path) 100 return -ENOMEM; 101 path->skip_release_on_error = 1; 102 103 if (!value) { 104 di = btrfs_lookup_xattr(trans, root, path, 105 btrfs_ino(BTRFS_I(inode)), name, name_len, -1); 106 if (!di && (flags & XATTR_REPLACE)) 107 ret = -ENODATA; 108 else if (IS_ERR(di)) 109 ret = PTR_ERR(di); 110 else if (di) 111 ret = btrfs_delete_one_dir_name(trans, root, path, di); 112 goto out; 113 } 114 115 /* 116 * For a replace we can't just do the insert blindly. 117 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 118 * doesn't exist. If it exists, fall down below to the insert/replace 119 * path - we can't race with a concurrent xattr delete, because the VFS 120 * locks the inode's i_mutex before calling setxattr or removexattr. 121 */ 122 if (flags & XATTR_REPLACE) { 123 ASSERT(inode_is_locked(inode)); 124 di = btrfs_lookup_xattr(NULL, root, path, 125 btrfs_ino(BTRFS_I(inode)), name, name_len, 0); 126 if (!di) 127 ret = -ENODATA; 128 else if (IS_ERR(di)) 129 ret = PTR_ERR(di); 130 if (ret) 131 goto out; 132 btrfs_release_path(path); 133 di = NULL; 134 } 135 136 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), 137 name, name_len, value, size); 138 if (ret == -EOVERFLOW) { 139 /* 140 * We have an existing item in a leaf, split_leaf couldn't 141 * expand it. That item might have or not a dir_item that 142 * matches our target xattr, so lets check. 143 */ 144 ret = 0; 145 btrfs_assert_tree_write_locked(path->nodes[0]); 146 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 147 if (!di && !(flags & XATTR_REPLACE)) { 148 ret = -ENOSPC; 149 goto out; 150 } 151 } else if (ret == -EEXIST) { 152 ret = 0; 153 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 154 ASSERT(di); /* logic error */ 155 } else if (ret) { 156 goto out; 157 } 158 159 if (di && (flags & XATTR_CREATE)) { 160 ret = -EEXIST; 161 goto out; 162 } 163 164 if (di) { 165 /* 166 * We're doing a replace, and it must be atomic, that is, at 167 * any point in time we have either the old or the new xattr 168 * value in the tree. We don't want readers (getxattr and 169 * listxattrs) to miss a value, this is specially important 170 * for ACLs. 171 */ 172 const int slot = path->slots[0]; 173 struct extent_buffer *leaf = path->nodes[0]; 174 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 175 const u32 item_size = btrfs_item_size(leaf, slot); 176 const u32 data_size = sizeof(*di) + name_len + size; 177 unsigned long data_ptr; 178 char *ptr; 179 180 if (size > old_data_len) { 181 if (btrfs_leaf_free_space(leaf) < 182 (size - old_data_len)) { 183 ret = -ENOSPC; 184 goto out; 185 } 186 } 187 188 if (old_data_len + name_len + sizeof(*di) == item_size) { 189 /* No other xattrs packed in the same leaf item. */ 190 if (size > old_data_len) 191 btrfs_extend_item(trans, path, size - old_data_len); 192 else if (size < old_data_len) 193 btrfs_truncate_item(trans, path, data_size, 1); 194 } else { 195 /* There are other xattrs packed in the same item. */ 196 ret = btrfs_delete_one_dir_name(trans, root, path, di); 197 if (ret) 198 goto out; 199 btrfs_extend_item(trans, path, data_size); 200 } 201 202 ptr = btrfs_item_ptr(leaf, slot, char); 203 ptr += btrfs_item_size(leaf, slot) - data_size; 204 di = (struct btrfs_dir_item *)ptr; 205 btrfs_set_dir_data_len(leaf, di, size); 206 data_ptr = ((unsigned long)(di + 1)) + name_len; 207 write_extent_buffer(leaf, value, data_ptr, size); 208 btrfs_mark_buffer_dirty(trans, leaf); 209 } else { 210 /* 211 * Insert, and we had space for the xattr, so path->slots[0] is 212 * where our xattr dir_item is and btrfs_insert_xattr_item() 213 * filled it. 214 */ 215 } 216out: 217 btrfs_free_path(path); 218 if (!ret) { 219 set_bit(BTRFS_INODE_COPY_EVERYTHING, 220 &BTRFS_I(inode)->runtime_flags); 221 clear_bit(BTRFS_INODE_NO_XATTRS, &BTRFS_I(inode)->runtime_flags); 222 } 223 return ret; 224} 225 226/* 227 * @value: "" makes the attribute to empty, NULL removes it 228 */ 229int btrfs_setxattr_trans(struct inode *inode, const char *name, 230 const void *value, size_t size, int flags) 231{ 232 struct btrfs_root *root = BTRFS_I(inode)->root; 233 struct btrfs_trans_handle *trans; 234 const bool start_trans = (current->journal_info == NULL); 235 int ret; 236 237 if (start_trans) { 238 /* 239 * 1 unit for inserting/updating/deleting the xattr 240 * 1 unit for the inode item update 241 */ 242 trans = btrfs_start_transaction(root, 2); 243 if (IS_ERR(trans)) 244 return PTR_ERR(trans); 245 } else { 246 /* 247 * This can happen when smack is enabled and a directory is being 248 * created. It happens through d_instantiate_new(), which calls 249 * smack_d_instantiate(), which in turn calls __vfs_setxattr() to 250 * set the transmute xattr (XATTR_NAME_SMACKTRANSMUTE) on the 251 * inode. We have already reserved space for the xattr and inode 252 * update at btrfs_mkdir(), so just use the transaction handle. 253 * We don't join or start a transaction, as that will reset the 254 * block_rsv of the handle and trigger a warning for the start 255 * case. 256 */ 257 ASSERT(strncmp(name, XATTR_SECURITY_PREFIX, 258 XATTR_SECURITY_PREFIX_LEN) == 0); 259 trans = current->journal_info; 260 } 261 262 ret = btrfs_setxattr(trans, inode, name, value, size, flags); 263 if (ret) 264 goto out; 265 266 inode_inc_iversion(inode); 267 inode_set_ctime_current(inode); 268 ret = btrfs_update_inode(trans, BTRFS_I(inode)); 269 if (ret) 270 btrfs_abort_transaction(trans, ret); 271out: 272 if (start_trans) 273 btrfs_end_transaction(trans); 274 return ret; 275} 276 277ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 278{ 279 struct btrfs_key found_key; 280 struct btrfs_key key; 281 struct inode *inode = d_inode(dentry); 282 struct btrfs_root *root = BTRFS_I(inode)->root; 283 struct btrfs_path *path; 284 int iter_ret = 0; 285 int ret = 0; 286 size_t total_size = 0, size_left = size; 287 288 /* 289 * ok we want all objects associated with this id. 290 * NOTE: we set key.offset = 0; because we want to start with the 291 * first xattr that we find and walk forward 292 */ 293 key.objectid = btrfs_ino(BTRFS_I(inode)); 294 key.type = BTRFS_XATTR_ITEM_KEY; 295 key.offset = 0; 296 297 path = btrfs_alloc_path(); 298 if (!path) 299 return -ENOMEM; 300 path->reada = READA_FORWARD; 301 302 /* search for our xattrs */ 303 btrfs_for_each_slot(root, &key, &found_key, path, iter_ret) { 304 struct extent_buffer *leaf; 305 int slot; 306 struct btrfs_dir_item *di; 307 u32 item_size; 308 u32 cur; 309 310 leaf = path->nodes[0]; 311 slot = path->slots[0]; 312 313 /* check to make sure this item is what we want */ 314 if (found_key.objectid != key.objectid) 315 break; 316 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 317 break; 318 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 319 continue; 320 321 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 322 item_size = btrfs_item_size(leaf, slot); 323 cur = 0; 324 while (cur < item_size) { 325 u16 name_len = btrfs_dir_name_len(leaf, di); 326 u16 data_len = btrfs_dir_data_len(leaf, di); 327 u32 this_len = sizeof(*di) + name_len + data_len; 328 unsigned long name_ptr = (unsigned long)(di + 1); 329 330 total_size += name_len + 1; 331 /* 332 * We are just looking for how big our buffer needs to 333 * be. 334 */ 335 if (!size) 336 goto next; 337 338 if (!buffer || (name_len + 1) > size_left) { 339 iter_ret = -ERANGE; 340 break; 341 } 342 343 read_extent_buffer(leaf, buffer, name_ptr, name_len); 344 buffer[name_len] = '\0'; 345 346 size_left -= name_len + 1; 347 buffer += name_len + 1; 348next: 349 cur += this_len; 350 di = (struct btrfs_dir_item *)((char *)di + this_len); 351 } 352 } 353 354 if (iter_ret < 0) 355 ret = iter_ret; 356 else 357 ret = total_size; 358 359 btrfs_free_path(path); 360 361 return ret; 362} 363 364static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 365 struct dentry *unused, struct inode *inode, 366 const char *name, void *buffer, size_t size) 367{ 368 name = xattr_full_name(handler, name); 369 return btrfs_getxattr(inode, name, buffer, size); 370} 371 372static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 373 struct mnt_idmap *idmap, 374 struct dentry *unused, struct inode *inode, 375 const char *name, const void *buffer, 376 size_t size, int flags) 377{ 378 if (btrfs_root_readonly(BTRFS_I(inode)->root)) 379 return -EROFS; 380 381 name = xattr_full_name(handler, name); 382 return btrfs_setxattr_trans(inode, name, buffer, size, flags); 383} 384 385static int btrfs_xattr_handler_get_security(const struct xattr_handler *handler, 386 struct dentry *unused, 387 struct inode *inode, 388 const char *name, void *buffer, 389 size_t size) 390{ 391 int ret; 392 bool is_cap = false; 393 394 name = xattr_full_name(handler, name); 395 396 /* 397 * security.capability doesn't cache the results, so calls into us 398 * constantly to see if there's a capability xattr. Cache the result 399 * here in order to avoid wasting time doing lookups for xattrs we know 400 * don't exist. 401 */ 402 if (strcmp(name, XATTR_NAME_CAPS) == 0) { 403 is_cap = true; 404 if (test_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags)) 405 return -ENODATA; 406 } 407 408 ret = btrfs_getxattr(inode, name, buffer, size); 409 if (ret == -ENODATA && is_cap) 410 set_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags); 411 return ret; 412} 413 414static int btrfs_xattr_handler_set_security(const struct xattr_handler *handler, 415 struct mnt_idmap *idmap, 416 struct dentry *unused, 417 struct inode *inode, 418 const char *name, 419 const void *buffer, 420 size_t size, int flags) 421{ 422 if (btrfs_root_readonly(BTRFS_I(inode)->root)) 423 return -EROFS; 424 425 name = xattr_full_name(handler, name); 426 if (strcmp(name, XATTR_NAME_CAPS) == 0) 427 clear_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags); 428 429 return btrfs_setxattr_trans(inode, name, buffer, size, flags); 430} 431 432static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 433 struct mnt_idmap *idmap, 434 struct dentry *unused, struct inode *inode, 435 const char *name, const void *value, 436 size_t size, int flags) 437{ 438 int ret; 439 struct btrfs_trans_handle *trans; 440 struct btrfs_root *root = BTRFS_I(inode)->root; 441 442 name = xattr_full_name(handler, name); 443 ret = btrfs_validate_prop(BTRFS_I(inode), name, value, size); 444 if (ret) 445 return ret; 446 447 if (btrfs_ignore_prop(BTRFS_I(inode), name)) 448 return 0; 449 450 trans = btrfs_start_transaction(root, 2); 451 if (IS_ERR(trans)) 452 return PTR_ERR(trans); 453 454 ret = btrfs_set_prop(trans, inode, name, value, size, flags); 455 if (!ret) { 456 inode_inc_iversion(inode); 457 inode_set_ctime_current(inode); 458 ret = btrfs_update_inode(trans, BTRFS_I(inode)); 459 if (ret) 460 btrfs_abort_transaction(trans, ret); 461 } 462 463 btrfs_end_transaction(trans); 464 465 return ret; 466} 467 468static const struct xattr_handler btrfs_security_xattr_handler = { 469 .prefix = XATTR_SECURITY_PREFIX, 470 .get = btrfs_xattr_handler_get_security, 471 .set = btrfs_xattr_handler_set_security, 472}; 473 474static const struct xattr_handler btrfs_trusted_xattr_handler = { 475 .prefix = XATTR_TRUSTED_PREFIX, 476 .get = btrfs_xattr_handler_get, 477 .set = btrfs_xattr_handler_set, 478}; 479 480static const struct xattr_handler btrfs_user_xattr_handler = { 481 .prefix = XATTR_USER_PREFIX, 482 .get = btrfs_xattr_handler_get, 483 .set = btrfs_xattr_handler_set, 484}; 485 486static const struct xattr_handler btrfs_btrfs_xattr_handler = { 487 .prefix = XATTR_BTRFS_PREFIX, 488 .get = btrfs_xattr_handler_get, 489 .set = btrfs_xattr_handler_set_prop, 490}; 491 492const struct xattr_handler * const btrfs_xattr_handlers[] = { 493 &btrfs_security_xattr_handler, 494 &btrfs_trusted_xattr_handler, 495 &btrfs_user_xattr_handler, 496 &btrfs_btrfs_xattr_handler, 497 NULL, 498}; 499 500static int btrfs_initxattrs(struct inode *inode, 501 const struct xattr *xattr_array, void *fs_private) 502{ 503 struct btrfs_trans_handle *trans = fs_private; 504 const struct xattr *xattr; 505 unsigned int nofs_flag; 506 char *name; 507 int err = 0; 508 509 /* 510 * We're holding a transaction handle, so use a NOFS memory allocation 511 * context to avoid deadlock if reclaim happens. 512 */ 513 nofs_flag = memalloc_nofs_save(); 514 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 515 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 516 strlen(xattr->name) + 1, GFP_KERNEL); 517 if (!name) { 518 err = -ENOMEM; 519 break; 520 } 521 strcpy(name, XATTR_SECURITY_PREFIX); 522 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 523 524 if (strcmp(name, XATTR_NAME_CAPS) == 0) 525 clear_bit(BTRFS_INODE_NO_CAP_XATTR, &BTRFS_I(inode)->runtime_flags); 526 527 err = btrfs_setxattr(trans, inode, name, xattr->value, 528 xattr->value_len, 0); 529 kfree(name); 530 if (err < 0) 531 break; 532 } 533 memalloc_nofs_restore(nofs_flag); 534 return err; 535} 536 537int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 538 struct inode *inode, struct inode *dir, 539 const struct qstr *qstr) 540{ 541 return security_inode_init_security(inode, dir, qstr, 542 &btrfs_initxattrs, trans); 543} 544