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(fs_info, path, 189 size - old_data_len); 190 else if (size < old_data_len) 191 btrfs_truncate_item(path, 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_trans(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 struct btrfs_trans_handle *trans; 228 int ret; 229 230 trans = btrfs_start_transaction(root, 2); 231 if (IS_ERR(trans)) 232 return PTR_ERR(trans); 233 234 ret = btrfs_setxattr(trans, inode, name, value, size, flags); 235 if (ret) 236 goto out; 237 238 inode_inc_iversion(inode); 239 inode->i_ctime = current_time(inode); 240 set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags); 241 ret = btrfs_update_inode(trans, root, inode); 242 BUG_ON(ret); 243 out: 244 btrfs_end_transaction(trans); 245 return ret; 246 } 247 248 ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size) 249 { 250 struct btrfs_key key; 251 struct inode *inode = d_inode(dentry); 252 struct btrfs_root *root = BTRFS_I(inode)->root; 253 struct btrfs_path *path; 254 int ret = 0; 255 size_t total_size = 0, size_left = size; 256 257 /* 258 * ok we want all objects associated with this id. 259 * NOTE: we set key.offset = 0; because we want to start with the 260 * first xattr that we find and walk forward 261 */ 262 key.objectid = btrfs_ino(BTRFS_I(inode)); 263 key.type = BTRFS_XATTR_ITEM_KEY; 264 key.offset = 0; 265 266 path = btrfs_alloc_path(); 267 if (!path) 268 return -ENOMEM; 269 path->reada = READA_FORWARD; 270 271 /* search for our xattrs */ 272 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 273 if (ret < 0) 274 goto err; 275 276 while (1) { 277 struct extent_buffer *leaf; 278 int slot; 279 struct btrfs_dir_item *di; 280 struct btrfs_key found_key; 281 u32 item_size; 282 u32 cur; 283 284 leaf = path->nodes[0]; 285 slot = path->slots[0]; 286 287 /* this is where we start walking through the path */ 288 if (slot >= btrfs_header_nritems(leaf)) { 289 /* 290 * if we've reached the last slot in this leaf we need 291 * to go to the next leaf and reset everything 292 */ 293 ret = btrfs_next_leaf(root, path); 294 if (ret < 0) 295 goto err; 296 else if (ret > 0) 297 break; 298 continue; 299 } 300 301 btrfs_item_key_to_cpu(leaf, &found_key, slot); 302 303 /* check to make sure this item is what we want */ 304 if (found_key.objectid != key.objectid) 305 break; 306 if (found_key.type > BTRFS_XATTR_ITEM_KEY) 307 break; 308 if (found_key.type < BTRFS_XATTR_ITEM_KEY) 309 goto next_item; 310 311 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item); 312 item_size = btrfs_item_size_nr(leaf, slot); 313 cur = 0; 314 while (cur < item_size) { 315 u16 name_len = btrfs_dir_name_len(leaf, di); 316 u16 data_len = btrfs_dir_data_len(leaf, di); 317 u32 this_len = sizeof(*di) + name_len + data_len; 318 unsigned long name_ptr = (unsigned long)(di + 1); 319 320 total_size += name_len + 1; 321 /* 322 * We are just looking for how big our buffer needs to 323 * be. 324 */ 325 if (!size) 326 goto next; 327 328 if (!buffer || (name_len + 1) > size_left) { 329 ret = -ERANGE; 330 goto err; 331 } 332 333 read_extent_buffer(leaf, buffer, name_ptr, name_len); 334 buffer[name_len] = '\0'; 335 336 size_left -= name_len + 1; 337 buffer += name_len + 1; 338 next: 339 cur += this_len; 340 di = (struct btrfs_dir_item *)((char *)di + this_len); 341 } 342 next_item: 343 path->slots[0]++; 344 } 345 ret = total_size; 346 347 err: 348 btrfs_free_path(path); 349 350 return ret; 351 } 352 353 static int btrfs_xattr_handler_get(const struct xattr_handler *handler, 354 struct dentry *unused, struct inode *inode, 355 const char *name, void *buffer, size_t size) 356 { 357 name = xattr_full_name(handler, name); 358 return btrfs_getxattr(inode, name, buffer, size); 359 } 360 361 static int btrfs_xattr_handler_set(const struct xattr_handler *handler, 362 struct dentry *unused, struct inode *inode, 363 const char *name, const void *buffer, 364 size_t size, int flags) 365 { 366 name = xattr_full_name(handler, name); 367 return btrfs_setxattr_trans(inode, name, buffer, size, flags); 368 } 369 370 static int btrfs_xattr_handler_set_prop(const struct xattr_handler *handler, 371 struct dentry *unused, struct inode *inode, 372 const char *name, const void *value, 373 size_t size, int flags) 374 { 375 name = xattr_full_name(handler, name); 376 return btrfs_set_prop_trans(inode, name, value, size, flags); 377 } 378 379 static const struct xattr_handler btrfs_security_xattr_handler = { 380 .prefix = XATTR_SECURITY_PREFIX, 381 .get = btrfs_xattr_handler_get, 382 .set = btrfs_xattr_handler_set, 383 }; 384 385 static const struct xattr_handler btrfs_trusted_xattr_handler = { 386 .prefix = XATTR_TRUSTED_PREFIX, 387 .get = btrfs_xattr_handler_get, 388 .set = btrfs_xattr_handler_set, 389 }; 390 391 static const struct xattr_handler btrfs_user_xattr_handler = { 392 .prefix = XATTR_USER_PREFIX, 393 .get = btrfs_xattr_handler_get, 394 .set = btrfs_xattr_handler_set, 395 }; 396 397 static const struct xattr_handler btrfs_btrfs_xattr_handler = { 398 .prefix = XATTR_BTRFS_PREFIX, 399 .get = btrfs_xattr_handler_get, 400 .set = btrfs_xattr_handler_set_prop, 401 }; 402 403 const struct xattr_handler *btrfs_xattr_handlers[] = { 404 &btrfs_security_xattr_handler, 405 #ifdef CONFIG_BTRFS_FS_POSIX_ACL 406 &posix_acl_access_xattr_handler, 407 &posix_acl_default_xattr_handler, 408 #endif 409 &btrfs_trusted_xattr_handler, 410 &btrfs_user_xattr_handler, 411 &btrfs_btrfs_xattr_handler, 412 NULL, 413 }; 414 415 static int btrfs_initxattrs(struct inode *inode, 416 const struct xattr *xattr_array, void *fs_private) 417 { 418 struct btrfs_trans_handle *trans = fs_private; 419 const struct xattr *xattr; 420 unsigned int nofs_flag; 421 char *name; 422 int err = 0; 423 424 /* 425 * We're holding a transaction handle, so use a NOFS memory allocation 426 * context to avoid deadlock if reclaim happens. 427 */ 428 nofs_flag = memalloc_nofs_save(); 429 for (xattr = xattr_array; xattr->name != NULL; xattr++) { 430 name = kmalloc(XATTR_SECURITY_PREFIX_LEN + 431 strlen(xattr->name) + 1, GFP_KERNEL); 432 if (!name) { 433 err = -ENOMEM; 434 break; 435 } 436 strcpy(name, XATTR_SECURITY_PREFIX); 437 strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name); 438 err = btrfs_setxattr(trans, inode, name, xattr->value, 439 xattr->value_len, 0); 440 kfree(name); 441 if (err < 0) 442 break; 443 } 444 memalloc_nofs_restore(nofs_flag); 445 return err; 446 } 447 448 int btrfs_xattr_security_init(struct btrfs_trans_handle *trans, 449 struct inode *inode, struct inode *dir, 450 const struct qstr *qstr) 451 { 452 return security_inode_init_security(inode, dir, qstr, 453 &btrfs_initxattrs, trans); 454 } 455