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 static int do_setxattr(struct btrfs_trans_handle *trans, 80 struct inode *inode, const char *name, 81 const void *value, size_t size, int flags) 82 { 83 struct btrfs_dir_item *di = NULL; 84 struct btrfs_root *root = BTRFS_I(inode)->root; 85 struct btrfs_fs_info *fs_info = root->fs_info; 86 struct btrfs_path *path; 87 size_t name_len = strlen(name); 88 int ret = 0; 89 90 if (name_len + size > BTRFS_MAX_XATTR_SIZE(root->fs_info)) 91 return -ENOSPC; 92 93 path = btrfs_alloc_path(); 94 if (!path) 95 return -ENOMEM; 96 path->skip_release_on_error = 1; 97 98 if (!value) { 99 di = btrfs_lookup_xattr(trans, root, path, 100 btrfs_ino(BTRFS_I(inode)), name, name_len, -1); 101 if (!di && (flags & XATTR_REPLACE)) 102 ret = -ENODATA; 103 else if (IS_ERR(di)) 104 ret = PTR_ERR(di); 105 else if (di) 106 ret = btrfs_delete_one_dir_name(trans, root, path, di); 107 goto out; 108 } 109 110 /* 111 * For a replace we can't just do the insert blindly. 112 * Do a lookup first (read-only btrfs_search_slot), and return if xattr 113 * doesn't exist. If it exists, fall down below to the insert/replace 114 * path - we can't race with a concurrent xattr delete, because the VFS 115 * locks the inode's i_mutex before calling setxattr or removexattr. 116 */ 117 if (flags & XATTR_REPLACE) { 118 ASSERT(inode_is_locked(inode)); 119 di = btrfs_lookup_xattr(NULL, root, path, 120 btrfs_ino(BTRFS_I(inode)), name, name_len, 0); 121 if (!di) 122 ret = -ENODATA; 123 else if (IS_ERR(di)) 124 ret = PTR_ERR(di); 125 if (ret) 126 goto out; 127 btrfs_release_path(path); 128 di = NULL; 129 } 130 131 ret = btrfs_insert_xattr_item(trans, root, path, btrfs_ino(BTRFS_I(inode)), 132 name, name_len, value, size); 133 if (ret == -EOVERFLOW) { 134 /* 135 * We have an existing item in a leaf, split_leaf couldn't 136 * expand it. That item might have or not a dir_item that 137 * matches our target xattr, so lets check. 138 */ 139 ret = 0; 140 btrfs_assert_tree_locked(path->nodes[0]); 141 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 142 if (!di && !(flags & XATTR_REPLACE)) { 143 ret = -ENOSPC; 144 goto out; 145 } 146 } else if (ret == -EEXIST) { 147 ret = 0; 148 di = btrfs_match_dir_item_name(fs_info, path, name, name_len); 149 ASSERT(di); /* logic error */ 150 } else if (ret) { 151 goto out; 152 } 153 154 if (di && (flags & XATTR_CREATE)) { 155 ret = -EEXIST; 156 goto out; 157 } 158 159 if (di) { 160 /* 161 * We're doing a replace, and it must be atomic, that is, at 162 * any point in time we have either the old or the new xattr 163 * value in the tree. We don't want readers (getxattr and 164 * listxattrs) to miss a value, this is specially important 165 * for ACLs. 166 */ 167 const int slot = path->slots[0]; 168 struct extent_buffer *leaf = path->nodes[0]; 169 const u16 old_data_len = btrfs_dir_data_len(leaf, di); 170 const u32 item_size = btrfs_item_size_nr(leaf, slot); 171 const u32 data_size = sizeof(*di) + name_len + size; 172 struct btrfs_item *item; 173 unsigned long data_ptr; 174 char *ptr; 175 176 if (size > old_data_len) { 177 if (btrfs_leaf_free_space(fs_info, leaf) < 178 (size - old_data_len)) { 179 ret = -ENOSPC; 180 goto out; 181 } 182 } 183 184 if (old_data_len + name_len + sizeof(*di) == item_size) { 185 /* No other xattrs packed in the same leaf item. */ 186 if (size > old_data_len) 187 btrfs_extend_item(fs_info, path, 188 size - old_data_len); 189 else if (size < old_data_len) 190 btrfs_truncate_item(fs_info, path, 191 data_size, 1); 192 } else { 193 /* There are other xattrs packed in the same item. */ 194 ret = btrfs_delete_one_dir_name(trans, root, path, di); 195 if (ret) 196 goto out; 197 btrfs_extend_item(fs_info, path, data_size); 198 } 199 200 item = btrfs_item_nr(slot); 201 ptr = btrfs_item_ptr(leaf, slot, char); 202 ptr += btrfs_item_size(leaf, item) - data_size; 203 di = (struct btrfs_dir_item *)ptr; 204 btrfs_set_dir_data_len(leaf, di, size); 205 data_ptr = ((unsigned long)(di + 1)) + name_len; 206 write_extent_buffer(leaf, value, data_ptr, size); 207 btrfs_mark_buffer_dirty(leaf); 208 } else { 209 /* 210 * Insert, and we had space for the xattr, so path->slots[0] is 211 * where our xattr dir_item is and btrfs_insert_xattr_item() 212 * filled it. 213 */ 214 } 215 out: 216 btrfs_free_path(path); 217 return ret; 218 } 219 220 /* 221 * @value: "" makes the attribute to empty, NULL removes it 222 */ 223 int btrfs_setxattr(struct btrfs_trans_handle *trans, 224 struct inode *inode, const char *name, 225 const void *value, size_t size, int flags) 226 { 227 struct btrfs_root *root = BTRFS_I(inode)->root; 228 int ret; 229 230 if (btrfs_root_readonly(root)) 231 return -EROFS; 232 233 if (trans) 234 return do_setxattr(trans, inode, name, value, size, flags); 235 236 trans = btrfs_start_transaction(root, 2); 237 if (IS_ERR(trans)) 238 return PTR_ERR(trans); 239 240 ret = do_setxattr(trans, inode, name, value, size, flags); 241 if (ret) 242 goto out; 243 244 inode_inc_iversion(inode); 245 inode->i_ctime = current_time(inode); 246 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 247 ret = btrfs_update_inode(trans, root, inode); 248 BUG_ON(ret); 249 out: 250 btrfs_end_transaction(trans); 251 return ret; 252 } 253 254 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 255 { 256 struct btrfs_key key; 257 struct inode *inode = d_inode(dentry); 258 struct btrfs_root *root = BTRFS_I(inode)->root; 259 struct btrfs_path *path; 260 int ret = 0; 261 size_t total_size = 0, size_left = size; 262 263 /* 264 * ok we want all objects associated with this id. 265 * NOTE: we set key.offset = 0; because we want to start with the 266 * first xattr that we find and walk forward 267 */ 268 key.objectid = btrfs_ino(BTRFS_I(inode)); 269 key.type = BTRFS_XATTR_ITEM_KEY; 270 key.offset = 0; 271 272 path = btrfs_alloc_path(); 273 if (!path) 274 return -ENOMEM; 275 path->reada = READA_FORWARD; 276 277 /* search for our xattrs */ 278 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 279 if (ret < 0) 280 goto err; 281 282 while (1) { 283 struct extent_buffer *leaf; 284 int slot; 285 struct btrfs_dir_item *di; 286 struct btrfs_key found_key; 287 u32 item_size; 288 u32 cur; 289 290 leaf = path->nodes[0]; 291 slot = path->slots[0]; 292 293 /* this is where we start walking through the path */ 294 if (slot >= btrfs_header_nritems(leaf)) { 295 /* 296 * if we've reached the last slot in this leaf we need 297 * to go to the next leaf and reset everything 298 */ 299 ret = btrfs_next_leaf(root, path); 300 if (ret < 0) 301 goto err; 302 else if (ret > 0) 303 break; 304 continue; 305 } 306 307 btrfs_item_key_to_cpu(leaf, &found_key, slot); 308 309 /* check to make sure this item is what we want */ 310 if (found_key.objectid != key.objectid) 311 break; 312 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 313 break; 314 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 315 goto next_item; 316 317 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 318 item_size = btrfs_item_size_nr(leaf, slot); 319 cur = 0; 320 while (cur < item_size) { 321 u16 name_len = btrfs_dir_name_len(leaf, di); 322 u16 data_len = btrfs_dir_data_len(leaf, di); 323 u32 this_len = sizeof(*di) + name_len + data_len; 324 unsigned long name_ptr = (unsigned long)(di + 1); 325 326 total_size += name_len + 1; 327 /* 328 * We are just looking for how big our buffer needs to 329 * be. 330 */ 331 if (!size) 332 goto next; 333 334 if (!buffer || (name_len + 1) > size_left) { 335 ret = -ERANGE; 336 goto err; 337 } 338 339 read_extent_buffer(leaf, buffer, name_ptr, name_len); 340 buffer[name_len] = '\0'; 341 342 size_left -= name_len + 1; 343 buffer += name_len + 1; 344 next: 345 cur += this_len; 346 di = (struct btrfs_dir_item *)((char *)di + this_len); 347 } 348 next_item: 349 path->slots[0]++; 350 } 351 ret = total_size; 352 353 err: 354 btrfs_free_path(path); 355 356 return ret; 357 } 358 359 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 360 struct dentry *unused, struct inode *inode, 361 const char *name, void *buffer, size_t size) 362 { 363 name = xattr_full_name(handler, name); 364 return btrfs_getxattr(inode, name, buffer, size); 365 } 366 367 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 368 struct dentry *unused, struct inode *inode, 369 const char *name, const void *buffer, 370 size_t size, int flags) 371 { 372 name = xattr_full_name(handler, name); 373 return btrfs_setxattr(NULL, inode, name, buffer, size, flags); 374 } 375 376 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 377 struct dentry *unused, struct inode *inode, 378 const char *name, const void *value, 379 size_t size, int flags) 380 { 381 name = xattr_full_name(handler, name); 382 return btrfs_set_prop(inode, name, value, size, flags); 383 } 384 385 static const struct xattr_handler btrfs_security_xattr_handler = { 386 .prefix = XATTR_SECURITY_PREFIX, 387 .get = btrfs_xattr_handler_get, 388 .set = btrfs_xattr_handler_set, 389 }; 390 391 static const struct xattr_handler btrfs_trusted_xattr_handler = { 392 .prefix = XATTR_TRUSTED_PREFIX, 393 .get = btrfs_xattr_handler_get, 394 .set = btrfs_xattr_handler_set, 395 }; 396 397 static const struct xattr_handler btrfs_user_xattr_handler = { 398 .prefix = XATTR_USER_PREFIX, 399 .get = btrfs_xattr_handler_get, 400 .set = btrfs_xattr_handler_set, 401 }; 402 403 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 404 .prefix = XATTR_BTRFS_PREFIX, 405 .get = btrfs_xattr_handler_get, 406 .set = btrfs_xattr_handler_set_prop, 407 }; 408 409 const struct xattr_handler *btrfs_xattr_handlers[] = { 410 &btrfs_security_xattr_handler, 411 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 412 &posix_acl_access_xattr_handler, 413 &posix_acl_default_xattr_handler, 414 #endif 415 &btrfs_trusted_xattr_handler, 416 &btrfs_user_xattr_handler, 417 &btrfs_btrfs_xattr_handler, 418 NULL, 419 }; 420 421 static int btrfs_initxattrs(struct inode *inode, 422 const struct xattr *xattr_array, void *fs_info) 423 { 424 const struct xattr *xattr; 425 struct btrfs_trans_handle *trans = fs_info; 426 unsigned int nofs_flag; 427 char *name; 428 int err = 0; 429 430 /* 431 * We're holding a transaction handle, so use a NOFS memory allocation 432 * context to avoid deadlock if reclaim happens. 433 */ 434 nofs_flag = memalloc_nofs_save(); 435 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 436 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 437 strlen(xattr->name) + 1, GFP_KERNEL); 438 if (!name) { 439 err = -ENOMEM; 440 break; 441 } 442 strcpy(name, XATTR_SECURITY_PREFIX); 443 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 444 err = btrfs_setxattr(trans, inode, name, xattr->value, 445 xattr->value_len, 0); 446 kfree(name); 447 if (err < 0) 448 break; 449 } 450 memalloc_nofs_restore(nofs_flag); 451 return err; 452 } 453 454 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 455 struct inode *inode, struct inode *dir, 456 const struct qstr *qstr) 457 { 458 return security_inode_init_security(inode, dir, qstr, 459 &btrfs_initxattrs, trans); 460 } 461