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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | ||
3 | #include <linux/init.h> | |
4 | #include <linux/fs.h> | |
5 | #include <linux/slab.h> | |
6 | #include <linux/rwsem.h> | |
7 | #include <linux/xattr.h> | |
8 | #include <linux/security.h> | |
9 | #include <linux/posix_acl_xattr.h> | |
10 | #include <linux/iversion.h> | |
11 | #include <linux/fsverity.h> | |
12 | #include <linux/sched/mm.h> | |
13 | #include "ctree.h" | |
14 | #include "btrfs_inode.h" | |
15 | #include "transaction.h" | |
16 | #include "disk-io.h" | |
17 | #include "locking.h" | |
18 | ||
19 | /* | |
20 | * Implementation of the interface defined in struct fsverity_operations. | |
21 | * | |
22 | * The main question is how and where to store the verity descriptor and the | |
23 | * Merkle tree. We store both in dedicated btree items in the filesystem tree, | |
24 | * together with the rest of the inode metadata. This means we'll need to do | |
25 | * extra work to encrypt them once encryption is supported in btrfs, but btrfs | |
26 | * has a lot of careful code around i_size and it seems better to make a new key | |
27 | * type than try and adjust all of our expectations for i_size. | |
28 | * | |
29 | * Note that this differs from the implementation in ext4 and f2fs, where | |
30 | * this data is stored as if it were in the file, but past EOF. However, btrfs | |
31 | * does not have a widespread mechanism for caching opaque metadata pages, so we | |
32 | * do pretend that the Merkle tree pages themselves are past EOF for the | |
33 | * purposes of caching them (as opposed to creating a virtual inode). | |
34 | * | |
35 | * fs verity items are stored under two different key types on disk. | |
36 | * The descriptor items: | |
37 | * [ inode objectid, BTRFS_VERITY_DESC_ITEM_KEY, offset ] | |
38 | * | |
39 | * At offset 0, we store a btrfs_verity_descriptor_item which tracks the | |
40 | * size of the descriptor item and some extra data for encryption. | |
41 | * Starting at offset 1, these hold the generic fs verity descriptor. | |
42 | * The latter are opaque to btrfs, we just read and write them as a blob for | |
43 | * the higher level verity code. The most common descriptor size is 256 bytes. | |
44 | * | |
45 | * The merkle tree items: | |
46 | * [ inode objectid, BTRFS_VERITY_MERKLE_ITEM_KEY, offset ] | |
47 | * | |
48 | * These also start at offset 0, and correspond to the merkle tree bytes. | |
49 | * So when fsverity asks for page 0 of the merkle tree, we pull up one page | |
50 | * starting at offset 0 for this key type. These are also opaque to btrfs, | |
51 | * we're blindly storing whatever fsverity sends down. | |
70524253 BB |
52 | * |
53 | * Another important consideration is the fact that the Merkle tree data scales | |
54 | * linearly with the size of the file (with 4K pages/blocks and SHA-256, it's | |
55 | * ~1/127th the size) so for large files, writing the tree can be a lengthy | |
56 | * operation. For that reason, we guard the whole enable verity operation | |
57 | * (between begin_enable_verity and end_enable_verity) with an orphan item. | |
58 | * Again, because the data can be pretty large, it's quite possible that we | |
59 | * could run out of space writing it, so we try our best to handle errors by | |
60 | * stopping and rolling back rather than aborting the victim transaction. | |
14605409 BB |
61 | */ |
62 | ||
63 | #define MERKLE_START_ALIGN 65536 | |
64 | ||
65 | /* | |
66 | * Compute the logical file offset where we cache the Merkle tree. | |
67 | * | |
68 | * @inode: inode of the verity file | |
69 | * | |
70 | * For the purposes of caching the Merkle tree pages, as required by | |
71 | * fs-verity, it is convenient to do size computations in terms of a file | |
72 | * offset, rather than in terms of page indices. | |
73 | * | |
74 | * Use 64K to be sure it's past the last page in the file, even with 64K pages. | |
75 | * That rounding operation itself can overflow loff_t, so we do it in u64 and | |
76 | * check. | |
77 | * | |
78 | * Returns the file offset on success, negative error code on failure. | |
79 | */ | |
80 | static loff_t merkle_file_pos(const struct inode *inode) | |
81 | { | |
82 | u64 sz = inode->i_size; | |
83 | u64 rounded = round_up(sz, MERKLE_START_ALIGN); | |
84 | ||
85 | if (rounded > inode->i_sb->s_maxbytes) | |
86 | return -EFBIG; | |
87 | ||
88 | return rounded; | |
89 | } | |
90 | ||
91 | /* | |
92 | * Drop all the items for this inode with this key_type. | |
93 | * | |
94 | * @inode: inode to drop items for | |
95 | * @key_type: type of items to drop (BTRFS_VERITY_DESC_ITEM or | |
96 | * BTRFS_VERITY_MERKLE_ITEM) | |
97 | * | |
98 | * Before doing a verity enable we cleanup any existing verity items. | |
99 | * This is also used to clean up if a verity enable failed half way through. | |
100 | * | |
101 | * Returns number of dropped items on success, negative error code on failure. | |
102 | */ | |
103 | static int drop_verity_items(struct btrfs_inode *inode, u8 key_type) | |
104 | { | |
105 | struct btrfs_trans_handle *trans; | |
106 | struct btrfs_root *root = inode->root; | |
107 | struct btrfs_path *path; | |
108 | struct btrfs_key key; | |
109 | int count = 0; | |
110 | int ret; | |
111 | ||
112 | path = btrfs_alloc_path(); | |
113 | if (!path) | |
114 | return -ENOMEM; | |
115 | ||
116 | while (1) { | |
117 | /* 1 for the item being dropped */ | |
118 | trans = btrfs_start_transaction(root, 1); | |
119 | if (IS_ERR(trans)) { | |
120 | ret = PTR_ERR(trans); | |
121 | goto out; | |
122 | } | |
123 | ||
124 | /* | |
125 | * Walk backwards through all the items until we find one that | |
126 | * isn't from our key type or objectid | |
127 | */ | |
128 | key.objectid = btrfs_ino(inode); | |
129 | key.type = key_type; | |
130 | key.offset = (u64)-1; | |
131 | ||
132 | ret = btrfs_search_slot(trans, root, &key, path, -1, 1); | |
133 | if (ret > 0) { | |
134 | ret = 0; | |
135 | /* No more keys of this type, we're done */ | |
136 | if (path->slots[0] == 0) | |
137 | break; | |
138 | path->slots[0]--; | |
139 | } else if (ret < 0) { | |
140 | btrfs_end_transaction(trans); | |
141 | goto out; | |
142 | } | |
143 | ||
144 | btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); | |
145 | ||
146 | /* No more keys of this type, we're done */ | |
147 | if (key.objectid != btrfs_ino(inode) || key.type != key_type) | |
148 | break; | |
149 | ||
150 | /* | |
151 | * This shouldn't be a performance sensitive function because | |
152 | * it's not used as part of truncate. If it ever becomes | |
153 | * perf sensitive, change this to walk forward and bulk delete | |
154 | * items | |
155 | */ | |
156 | ret = btrfs_del_items(trans, root, path, path->slots[0], 1); | |
157 | if (ret) { | |
158 | btrfs_end_transaction(trans); | |
159 | goto out; | |
160 | } | |
161 | count++; | |
162 | btrfs_release_path(path); | |
163 | btrfs_end_transaction(trans); | |
164 | } | |
165 | ret = count; | |
166 | btrfs_end_transaction(trans); | |
167 | out: | |
168 | btrfs_free_path(path); | |
169 | return ret; | |
170 | } | |
171 | ||
172 | /* | |
173 | * Drop all verity items | |
174 | * | |
175 | * @inode: inode to drop verity items for | |
176 | * | |
177 | * In most contexts where we are dropping verity items, we want to do it for all | |
178 | * the types of verity items, not a particular one. | |
179 | * | |
180 | * Returns: 0 on success, negative error code on failure. | |
181 | */ | |
182 | int btrfs_drop_verity_items(struct btrfs_inode *inode) | |
183 | { | |
184 | int ret; | |
185 | ||
186 | ret = drop_verity_items(inode, BTRFS_VERITY_DESC_ITEM_KEY); | |
187 | if (ret < 0) | |
188 | return ret; | |
189 | ret = drop_verity_items(inode, BTRFS_VERITY_MERKLE_ITEM_KEY); | |
190 | if (ret < 0) | |
191 | return ret; | |
192 | ||
193 | return 0; | |
194 | } | |
195 | ||
196 | /* | |
197 | * Insert and write inode items with a given key type and offset. | |
198 | * | |
199 | * @inode: inode to insert for | |
200 | * @key_type: key type to insert | |
201 | * @offset: item offset to insert at | |
202 | * @src: source data to write | |
203 | * @len: length of source data to write | |
204 | * | |
205 | * Write len bytes from src into items of up to 2K length. | |
206 | * The inserted items will have key (ino, key_type, offset + off) where off is | |
207 | * consecutively increasing from 0 up to the last item ending at offset + len. | |
208 | * | |
209 | * Returns 0 on success and a negative error code on failure. | |
210 | */ | |
211 | static int write_key_bytes(struct btrfs_inode *inode, u8 key_type, u64 offset, | |
212 | const char *src, u64 len) | |
213 | { | |
214 | struct btrfs_trans_handle *trans; | |
215 | struct btrfs_path *path; | |
216 | struct btrfs_root *root = inode->root; | |
217 | struct extent_buffer *leaf; | |
218 | struct btrfs_key key; | |
219 | unsigned long copy_bytes; | |
220 | unsigned long src_offset = 0; | |
221 | void *data; | |
222 | int ret = 0; | |
223 | ||
224 | path = btrfs_alloc_path(); | |
225 | if (!path) | |
226 | return -ENOMEM; | |
227 | ||
228 | while (len > 0) { | |
229 | /* 1 for the new item being inserted */ | |
230 | trans = btrfs_start_transaction(root, 1); | |
231 | if (IS_ERR(trans)) { | |
232 | ret = PTR_ERR(trans); | |
233 | break; | |
234 | } | |
235 | ||
236 | key.objectid = btrfs_ino(inode); | |
237 | key.type = key_type; | |
238 | key.offset = offset; | |
239 | ||
240 | /* | |
241 | * Insert 2K at a time mostly to be friendly for smaller leaf | |
242 | * size filesystems | |
243 | */ | |
244 | copy_bytes = min_t(u64, len, 2048); | |
245 | ||
246 | ret = btrfs_insert_empty_item(trans, root, path, &key, copy_bytes); | |
247 | if (ret) { | |
248 | btrfs_end_transaction(trans); | |
249 | break; | |
250 | } | |
251 | ||
252 | leaf = path->nodes[0]; | |
253 | ||
254 | data = btrfs_item_ptr(leaf, path->slots[0], void); | |
255 | write_extent_buffer(leaf, src + src_offset, | |
256 | (unsigned long)data, copy_bytes); | |
257 | offset += copy_bytes; | |
258 | src_offset += copy_bytes; | |
259 | len -= copy_bytes; | |
260 | ||
261 | btrfs_release_path(path); | |
262 | btrfs_end_transaction(trans); | |
263 | } | |
264 | ||
265 | btrfs_free_path(path); | |
266 | return ret; | |
267 | } | |
268 | ||
269 | /* | |
270 | * Read inode items of the given key type and offset from the btree. | |
271 | * | |
272 | * @inode: inode to read items of | |
273 | * @key_type: key type to read | |
274 | * @offset: item offset to read from | |
275 | * @dest: Buffer to read into. This parameter has slightly tricky | |
276 | * semantics. If it is NULL, the function will not do any copying | |
277 | * and will just return the size of all the items up to len bytes. | |
278 | * If dest_page is passed, then the function will kmap_local the | |
279 | * page and ignore dest, but it must still be non-NULL to avoid the | |
280 | * counting-only behavior. | |
281 | * @len: length in bytes to read | |
282 | * @dest_page: copy into this page instead of the dest buffer | |
283 | * | |
284 | * Helper function to read items from the btree. This returns the number of | |
285 | * bytes read or < 0 for errors. We can return short reads if the items don't | |
286 | * exist on disk or aren't big enough to fill the desired length. Supports | |
287 | * reading into a provided buffer (dest) or into the page cache | |
288 | * | |
289 | * Returns number of bytes read or a negative error code on failure. | |
290 | */ | |
291 | static int read_key_bytes(struct btrfs_inode *inode, u8 key_type, u64 offset, | |
292 | char *dest, u64 len, struct page *dest_page) | |
293 | { | |
294 | struct btrfs_path *path; | |
295 | struct btrfs_root *root = inode->root; | |
296 | struct extent_buffer *leaf; | |
297 | struct btrfs_key key; | |
298 | u64 item_end; | |
299 | u64 copy_end; | |
300 | int copied = 0; | |
301 | u32 copy_offset; | |
302 | unsigned long copy_bytes; | |
303 | unsigned long dest_offset = 0; | |
304 | void *data; | |
305 | char *kaddr = dest; | |
306 | int ret; | |
307 | ||
308 | path = btrfs_alloc_path(); | |
309 | if (!path) | |
310 | return -ENOMEM; | |
311 | ||
312 | if (dest_page) | |
313 | path->reada = READA_FORWARD; | |
314 | ||
315 | key.objectid = btrfs_ino(inode); | |
316 | key.type = key_type; | |
317 | key.offset = offset; | |
318 | ||
319 | ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); | |
320 | if (ret < 0) { | |
321 | goto out; | |
322 | } else if (ret > 0) { | |
323 | ret = 0; | |
324 | if (path->slots[0] == 0) | |
325 | goto out; | |
326 | path->slots[0]--; | |
327 | } | |
328 | ||
329 | while (len > 0) { | |
330 | leaf = path->nodes[0]; | |
331 | btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); | |
332 | ||
333 | if (key.objectid != btrfs_ino(inode) || key.type != key_type) | |
334 | break; | |
335 | ||
3212fa14 | 336 | item_end = btrfs_item_size(leaf, path->slots[0]) + key.offset; |
14605409 BB |
337 | |
338 | if (copied > 0) { | |
339 | /* | |
340 | * Once we've copied something, we want all of the items | |
341 | * to be sequential | |
342 | */ | |
343 | if (key.offset != offset) | |
344 | break; | |
345 | } else { | |
346 | /* | |
347 | * Our initial offset might be in the middle of an | |
348 | * item. Make sure it all makes sense. | |
349 | */ | |
350 | if (key.offset > offset) | |
351 | break; | |
352 | if (item_end <= offset) | |
353 | break; | |
354 | } | |
355 | ||
356 | /* desc = NULL to just sum all the item lengths */ | |
357 | if (!dest) | |
358 | copy_end = item_end; | |
359 | else | |
360 | copy_end = min(offset + len, item_end); | |
361 | ||
362 | /* Number of bytes in this item we want to copy */ | |
363 | copy_bytes = copy_end - offset; | |
364 | ||
365 | /* Offset from the start of item for copying */ | |
366 | copy_offset = offset - key.offset; | |
367 | ||
368 | if (dest) { | |
369 | if (dest_page) | |
370 | kaddr = kmap_local_page(dest_page); | |
371 | ||
372 | data = btrfs_item_ptr(leaf, path->slots[0], void); | |
373 | read_extent_buffer(leaf, kaddr + dest_offset, | |
374 | (unsigned long)data + copy_offset, | |
375 | copy_bytes); | |
376 | ||
377 | if (dest_page) | |
378 | kunmap_local(kaddr); | |
379 | } | |
380 | ||
381 | offset += copy_bytes; | |
382 | dest_offset += copy_bytes; | |
383 | len -= copy_bytes; | |
384 | copied += copy_bytes; | |
385 | ||
386 | path->slots[0]++; | |
387 | if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) { | |
388 | /* | |
389 | * We've reached the last slot in this leaf and we need | |
390 | * to go to the next leaf. | |
391 | */ | |
392 | ret = btrfs_next_leaf(root, path); | |
393 | if (ret < 0) { | |
394 | break; | |
395 | } else if (ret > 0) { | |
396 | ret = 0; | |
397 | break; | |
398 | } | |
399 | } | |
400 | } | |
401 | out: | |
402 | btrfs_free_path(path); | |
403 | if (!ret) | |
404 | ret = copied; | |
405 | return ret; | |
406 | } | |
407 | ||
70524253 BB |
408 | /* |
409 | * Delete an fsverity orphan | |
410 | * | |
411 | * @trans: transaction to do the delete in | |
412 | * @inode: inode to orphan | |
413 | * | |
414 | * Capture verity orphan specific logic that is repeated in the couple places | |
415 | * we delete verity orphans. Specifically, handling ENOENT and ignoring inodes | |
416 | * with 0 links. | |
417 | * | |
418 | * Returns zero on success or a negative error code on failure. | |
419 | */ | |
420 | static int del_orphan(struct btrfs_trans_handle *trans, struct btrfs_inode *inode) | |
421 | { | |
422 | struct btrfs_root *root = inode->root; | |
423 | int ret; | |
424 | ||
425 | /* | |
426 | * If the inode has no links, it is either already unlinked, or was | |
427 | * created with O_TMPFILE. In either case, it should have an orphan from | |
428 | * that other operation. Rather than reference count the orphans, we | |
429 | * simply ignore them here, because we only invoke the verity path in | |
430 | * the orphan logic when i_nlink is 1. | |
431 | */ | |
432 | if (!inode->vfs_inode.i_nlink) | |
433 | return 0; | |
434 | ||
435 | ret = btrfs_del_orphan_item(trans, root, btrfs_ino(inode)); | |
436 | if (ret == -ENOENT) | |
437 | ret = 0; | |
438 | return ret; | |
439 | } | |
440 | ||
14605409 BB |
441 | /* |
442 | * Rollback in-progress verity if we encounter an error. | |
443 | * | |
444 | * @inode: inode verity had an error for | |
445 | * | |
446 | * We try to handle recoverable errors while enabling verity by rolling it back | |
447 | * and just failing the operation, rather than having an fs level error no | |
448 | * matter what. However, any error in rollback is unrecoverable. | |
449 | * | |
450 | * Returns 0 on success, negative error code on failure. | |
451 | */ | |
452 | static int rollback_verity(struct btrfs_inode *inode) | |
453 | { | |
acbee9af | 454 | struct btrfs_trans_handle *trans = NULL; |
14605409 BB |
455 | struct btrfs_root *root = inode->root; |
456 | int ret; | |
457 | ||
458 | ASSERT(inode_is_locked(&inode->vfs_inode)); | |
459 | truncate_inode_pages(inode->vfs_inode.i_mapping, inode->vfs_inode.i_size); | |
460 | clear_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); | |
461 | ret = btrfs_drop_verity_items(inode); | |
462 | if (ret) { | |
463 | btrfs_handle_fs_error(root->fs_info, ret, | |
464 | "failed to drop verity items in rollback %llu", | |
465 | (u64)inode->vfs_inode.i_ino); | |
466 | goto out; | |
467 | } | |
468 | ||
70524253 BB |
469 | /* |
470 | * 1 for updating the inode flag | |
471 | * 1 for deleting the orphan | |
472 | */ | |
473 | trans = btrfs_start_transaction(root, 2); | |
14605409 BB |
474 | if (IS_ERR(trans)) { |
475 | ret = PTR_ERR(trans); | |
acbee9af | 476 | trans = NULL; |
14605409 BB |
477 | btrfs_handle_fs_error(root->fs_info, ret, |
478 | "failed to start transaction in verity rollback %llu", | |
479 | (u64)inode->vfs_inode.i_ino); | |
480 | goto out; | |
481 | } | |
482 | inode->ro_flags &= ~BTRFS_INODE_RO_VERITY; | |
483 | btrfs_sync_inode_flags_to_i_flags(&inode->vfs_inode); | |
484 | ret = btrfs_update_inode(trans, root, inode); | |
485 | if (ret) { | |
486 | btrfs_abort_transaction(trans, ret); | |
487 | goto out; | |
488 | } | |
70524253 BB |
489 | ret = del_orphan(trans, inode); |
490 | if (ret) { | |
491 | btrfs_abort_transaction(trans, ret); | |
492 | goto out; | |
493 | } | |
14605409 | 494 | out: |
acbee9af FM |
495 | if (trans) |
496 | btrfs_end_transaction(trans); | |
14605409 BB |
497 | return ret; |
498 | } | |
499 | ||
500 | /* | |
501 | * Finalize making the file a valid verity file | |
502 | * | |
503 | * @inode: inode to be marked as verity | |
504 | * @desc: contents of the verity descriptor to write (not NULL) | |
505 | * @desc_size: size of the verity descriptor | |
506 | * | |
507 | * Do the actual work of finalizing verity after successfully writing the Merkle | |
508 | * tree: | |
509 | * | |
510 | * - write out the descriptor items | |
511 | * - mark the inode with the verity flag | |
70524253 | 512 | * - delete the orphan item |
14605409 BB |
513 | * - mark the ro compat bit |
514 | * - clear the in progress bit | |
515 | * | |
516 | * Returns 0 on success, negative error code on failure. | |
517 | */ | |
518 | static int finish_verity(struct btrfs_inode *inode, const void *desc, | |
519 | size_t desc_size) | |
520 | { | |
521 | struct btrfs_trans_handle *trans = NULL; | |
522 | struct btrfs_root *root = inode->root; | |
523 | struct btrfs_verity_descriptor_item item; | |
524 | int ret; | |
525 | ||
526 | /* Write out the descriptor item */ | |
527 | memset(&item, 0, sizeof(item)); | |
528 | btrfs_set_stack_verity_descriptor_size(&item, desc_size); | |
529 | ret = write_key_bytes(inode, BTRFS_VERITY_DESC_ITEM_KEY, 0, | |
530 | (const char *)&item, sizeof(item)); | |
531 | if (ret) | |
532 | goto out; | |
533 | ||
534 | /* Write out the descriptor itself */ | |
535 | ret = write_key_bytes(inode, BTRFS_VERITY_DESC_ITEM_KEY, 1, | |
536 | desc, desc_size); | |
537 | if (ret) | |
538 | goto out; | |
539 | ||
70524253 BB |
540 | /* |
541 | * 1 for updating the inode flag | |
542 | * 1 for deleting the orphan | |
543 | */ | |
544 | trans = btrfs_start_transaction(root, 2); | |
14605409 BB |
545 | if (IS_ERR(trans)) { |
546 | ret = PTR_ERR(trans); | |
547 | goto out; | |
548 | } | |
549 | inode->ro_flags |= BTRFS_INODE_RO_VERITY; | |
550 | btrfs_sync_inode_flags_to_i_flags(&inode->vfs_inode); | |
551 | ret = btrfs_update_inode(trans, root, inode); | |
70524253 BB |
552 | if (ret) |
553 | goto end_trans; | |
554 | ret = del_orphan(trans, inode); | |
14605409 BB |
555 | if (ret) |
556 | goto end_trans; | |
557 | clear_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); | |
558 | btrfs_set_fs_compat_ro(root->fs_info, VERITY); | |
559 | end_trans: | |
560 | btrfs_end_transaction(trans); | |
561 | out: | |
562 | return ret; | |
563 | ||
564 | } | |
565 | ||
566 | /* | |
567 | * fsverity op that begins enabling verity. | |
568 | * | |
569 | * @filp: file to enable verity on | |
570 | * | |
70524253 BB |
571 | * Begin enabling fsverity for the file. We drop any existing verity items, add |
572 | * an orphan and set the in progress bit. | |
14605409 BB |
573 | * |
574 | * Returns 0 on success, negative error code on failure. | |
575 | */ | |
576 | static int btrfs_begin_enable_verity(struct file *filp) | |
577 | { | |
578 | struct btrfs_inode *inode = BTRFS_I(file_inode(filp)); | |
70524253 BB |
579 | struct btrfs_root *root = inode->root; |
580 | struct btrfs_trans_handle *trans; | |
14605409 BB |
581 | int ret; |
582 | ||
583 | ASSERT(inode_is_locked(file_inode(filp))); | |
584 | ||
585 | if (test_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags)) | |
586 | return -EBUSY; | |
587 | ||
70524253 BB |
588 | /* |
589 | * This should almost never do anything, but theoretically, it's | |
590 | * possible that we failed to enable verity on a file, then were | |
591 | * interrupted or failed while rolling back, failed to cleanup the | |
592 | * orphan, and finally attempt to enable verity again. | |
593 | */ | |
14605409 BB |
594 | ret = btrfs_drop_verity_items(inode); |
595 | if (ret) | |
596 | return ret; | |
597 | ||
70524253 BB |
598 | /* 1 for the orphan item */ |
599 | trans = btrfs_start_transaction(root, 1); | |
600 | if (IS_ERR(trans)) | |
601 | return PTR_ERR(trans); | |
602 | ||
603 | ret = btrfs_orphan_add(trans, inode); | |
604 | if (!ret) | |
605 | set_bit(BTRFS_INODE_VERITY_IN_PROGRESS, &inode->runtime_flags); | |
606 | btrfs_end_transaction(trans); | |
14605409 BB |
607 | |
608 | return 0; | |
609 | } | |
610 | ||
611 | /* | |
612 | * fsverity op that ends enabling verity. | |
613 | * | |
614 | * @filp: file we are finishing enabling verity on | |
615 | * @desc: verity descriptor to write out (NULL in error conditions) | |
616 | * @desc_size: size of the verity descriptor (variable with signatures) | |
617 | * @merkle_tree_size: size of the merkle tree in bytes | |
618 | * | |
619 | * If desc is null, then VFS is signaling an error occurred during verity | |
620 | * enable, and we should try to rollback. Otherwise, attempt to finish verity. | |
621 | * | |
622 | * Returns 0 on success, negative error code on error. | |
623 | */ | |
624 | static int btrfs_end_enable_verity(struct file *filp, const void *desc, | |
625 | size_t desc_size, u64 merkle_tree_size) | |
626 | { | |
627 | struct btrfs_inode *inode = BTRFS_I(file_inode(filp)); | |
628 | int ret = 0; | |
629 | int rollback_ret; | |
630 | ||
631 | ASSERT(inode_is_locked(file_inode(filp))); | |
632 | ||
633 | if (desc == NULL) | |
634 | goto rollback; | |
635 | ||
636 | ret = finish_verity(inode, desc, desc_size); | |
637 | if (ret) | |
638 | goto rollback; | |
639 | return ret; | |
640 | ||
641 | rollback: | |
642 | rollback_ret = rollback_verity(inode); | |
643 | if (rollback_ret) | |
644 | btrfs_err(inode->root->fs_info, | |
645 | "failed to rollback verity items: %d", rollback_ret); | |
646 | return ret; | |
647 | } | |
648 | ||
649 | /* | |
650 | * fsverity op that gets the struct fsverity_descriptor. | |
651 | * | |
652 | * @inode: inode to get the descriptor of | |
653 | * @buf: output buffer for the descriptor contents | |
654 | * @buf_size: size of the output buffer. 0 to query the size | |
655 | * | |
656 | * fsverity does a two pass setup for reading the descriptor, in the first pass | |
657 | * it calls with buf_size = 0 to query the size of the descriptor, and then in | |
658 | * the second pass it actually reads the descriptor off disk. | |
659 | * | |
660 | * Returns the size on success or a negative error code on failure. | |
661 | */ | |
38622010 | 662 | int btrfs_get_verity_descriptor(struct inode *inode, void *buf, size_t buf_size) |
14605409 BB |
663 | { |
664 | u64 true_size; | |
665 | int ret = 0; | |
666 | struct btrfs_verity_descriptor_item item; | |
667 | ||
668 | memset(&item, 0, sizeof(item)); | |
669 | ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_DESC_ITEM_KEY, 0, | |
670 | (char *)&item, sizeof(item), NULL); | |
671 | if (ret < 0) | |
672 | return ret; | |
673 | ||
674 | if (item.reserved[0] != 0 || item.reserved[1] != 0) | |
675 | return -EUCLEAN; | |
676 | ||
677 | true_size = btrfs_stack_verity_descriptor_size(&item); | |
678 | if (true_size > INT_MAX) | |
679 | return -EUCLEAN; | |
680 | ||
681 | if (buf_size == 0) | |
682 | return true_size; | |
683 | if (buf_size < true_size) | |
684 | return -ERANGE; | |
685 | ||
686 | ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_DESC_ITEM_KEY, 1, | |
687 | buf, buf_size, NULL); | |
688 | if (ret < 0) | |
689 | return ret; | |
690 | if (ret != true_size) | |
691 | return -EIO; | |
692 | ||
693 | return true_size; | |
694 | } | |
695 | ||
696 | /* | |
697 | * fsverity op that reads and caches a merkle tree page. | |
698 | * | |
699 | * @inode: inode to read a merkle tree page for | |
700 | * @index: page index relative to the start of the merkle tree | |
701 | * @num_ra_pages: number of pages to readahead. Optional, we ignore it | |
702 | * | |
703 | * The Merkle tree is stored in the filesystem btree, but its pages are cached | |
704 | * with a logical position past EOF in the inode's mapping. | |
705 | * | |
706 | * Returns the page we read, or an ERR_PTR on error. | |
707 | */ | |
708 | static struct page *btrfs_read_merkle_tree_page(struct inode *inode, | |
709 | pgoff_t index, | |
710 | unsigned long num_ra_pages) | |
711 | { | |
712 | struct page *page; | |
713 | u64 off = (u64)index << PAGE_SHIFT; | |
714 | loff_t merkle_pos = merkle_file_pos(inode); | |
715 | int ret; | |
716 | ||
717 | if (merkle_pos < 0) | |
718 | return ERR_PTR(merkle_pos); | |
719 | if (merkle_pos > inode->i_sb->s_maxbytes - off - PAGE_SIZE) | |
720 | return ERR_PTR(-EFBIG); | |
721 | index += merkle_pos >> PAGE_SHIFT; | |
722 | again: | |
723 | page = find_get_page_flags(inode->i_mapping, index, FGP_ACCESSED); | |
724 | if (page) { | |
725 | if (PageUptodate(page)) | |
726 | return page; | |
727 | ||
728 | lock_page(page); | |
729 | /* | |
730 | * We only insert uptodate pages, so !Uptodate has to be | |
731 | * an error | |
732 | */ | |
733 | if (!PageUptodate(page)) { | |
734 | unlock_page(page); | |
735 | put_page(page); | |
736 | return ERR_PTR(-EIO); | |
737 | } | |
738 | unlock_page(page); | |
739 | return page; | |
740 | } | |
741 | ||
742 | page = __page_cache_alloc(mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS)); | |
743 | if (!page) | |
744 | return ERR_PTR(-ENOMEM); | |
745 | ||
746 | /* | |
747 | * Merkle item keys are indexed from byte 0 in the merkle tree. | |
748 | * They have the form: | |
749 | * | |
750 | * [ inode objectid, BTRFS_MERKLE_ITEM_KEY, offset in bytes ] | |
751 | */ | |
752 | ret = read_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY, off, | |
753 | page_address(page), PAGE_SIZE, page); | |
754 | if (ret < 0) { | |
755 | put_page(page); | |
756 | return ERR_PTR(ret); | |
757 | } | |
758 | if (ret < PAGE_SIZE) | |
759 | memzero_page(page, ret, PAGE_SIZE - ret); | |
760 | ||
761 | SetPageUptodate(page); | |
762 | ret = add_to_page_cache_lru(page, inode->i_mapping, index, GFP_NOFS); | |
763 | ||
764 | if (!ret) { | |
765 | /* Inserted and ready for fsverity */ | |
766 | unlock_page(page); | |
767 | } else { | |
768 | put_page(page); | |
769 | /* Did someone race us into inserting this page? */ | |
770 | if (ret == -EEXIST) | |
771 | goto again; | |
772 | page = ERR_PTR(ret); | |
773 | } | |
774 | return page; | |
775 | } | |
776 | ||
777 | /* | |
778 | * fsverity op that writes a Merkle tree block into the btree. | |
779 | * | |
780 | * @inode: inode to write a Merkle tree block for | |
781 | * @buf: Merkle tree data block to write | |
782 | * @index: index of the block in the Merkle tree | |
783 | * @log_blocksize: log base 2 of the Merkle tree block size | |
784 | * | |
785 | * Note that the block size could be different from the page size, so it is not | |
786 | * safe to assume that index is a page index. | |
787 | * | |
788 | * Returns 0 on success or negative error code on failure | |
789 | */ | |
790 | static int btrfs_write_merkle_tree_block(struct inode *inode, const void *buf, | |
791 | u64 index, int log_blocksize) | |
792 | { | |
793 | u64 off = index << log_blocksize; | |
794 | u64 len = 1ULL << log_blocksize; | |
795 | loff_t merkle_pos = merkle_file_pos(inode); | |
796 | ||
797 | if (merkle_pos < 0) | |
798 | return merkle_pos; | |
799 | if (merkle_pos > inode->i_sb->s_maxbytes - off - len) | |
800 | return -EFBIG; | |
801 | ||
802 | return write_key_bytes(BTRFS_I(inode), BTRFS_VERITY_MERKLE_ITEM_KEY, | |
803 | off, buf, len); | |
804 | } | |
805 | ||
806 | const struct fsverity_operations btrfs_verityops = { | |
807 | .begin_enable_verity = btrfs_begin_enable_verity, | |
808 | .end_enable_verity = btrfs_end_enable_verity, | |
809 | .get_verity_descriptor = btrfs_get_verity_descriptor, | |
810 | .read_merkle_tree_page = btrfs_read_merkle_tree_page, | |
811 | .write_merkle_tree_block = btrfs_write_merkle_tree_block, | |
812 | }; |