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1/*
2 * This contains encryption functions for per-file encryption.
3 *
4 * Copyright (C) 2015, Google, Inc.
5 * Copyright (C) 2015, Motorola Mobility
6 *
7 * Written by Michael Halcrow, 2014.
8 *
9 * Filename encryption additions
10 * Uday Savagaonkar, 2014
11 * Encryption policy handling additions
12 * Ildar Muslukhov, 2014
13 * Add fscrypt_pullback_bio_page()
14 * Jaegeuk Kim, 2015.
15 *
16 * This has not yet undergone a rigorous security audit.
17 *
18 * The usage of AES-XTS should conform to recommendations in NIST
19 * Special Publication 800-38E and IEEE P1619/D16.
20 */
21
22#include <linux/pagemap.h>
23#include <linux/mempool.h>
24#include <linux/module.h>
25#include <linux/scatterlist.h>
26#include <linux/ratelimit.h>
27#include <linux/bio.h>
28#include <linux/dcache.h>
29#include <linux/namei.h>
30#include <linux/fscrypto.h>
31#include <linux/ecryptfs.h>
32
33static unsigned int num_prealloc_crypto_pages = 32;
34static unsigned int num_prealloc_crypto_ctxs = 128;
35
36module_param(num_prealloc_crypto_pages, uint, 0444);
37MODULE_PARM_DESC(num_prealloc_crypto_pages,
38 "Number of crypto pages to preallocate");
39module_param(num_prealloc_crypto_ctxs, uint, 0444);
40MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
41 "Number of crypto contexts to preallocate");
42
43static mempool_t *fscrypt_bounce_page_pool = NULL;
44
45static LIST_HEAD(fscrypt_free_ctxs);
46static DEFINE_SPINLOCK(fscrypt_ctx_lock);
47
48static struct workqueue_struct *fscrypt_read_workqueue;
49static DEFINE_MUTEX(fscrypt_init_mutex);
50
51static struct kmem_cache *fscrypt_ctx_cachep;
52struct kmem_cache *fscrypt_info_cachep;
53
54/**
55 * fscrypt_release_ctx() - Releases an encryption context
56 * @ctx: The encryption context to release.
57 *
58 * If the encryption context was allocated from the pre-allocated pool, returns
59 * it to that pool. Else, frees it.
60 *
61 * If there's a bounce page in the context, this frees that.
62 */
63void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
64{
65 unsigned long flags;
66
67 if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) {
68 mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
69 ctx->w.bounce_page = NULL;
70 }
71 ctx->w.control_page = NULL;
72 if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
73 kmem_cache_free(fscrypt_ctx_cachep, ctx);
74 } else {
75 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
76 list_add(&ctx->free_list, &fscrypt_free_ctxs);
77 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
78 }
79}
80EXPORT_SYMBOL(fscrypt_release_ctx);
81
82/**
83 * fscrypt_get_ctx() - Gets an encryption context
84 * @inode: The inode for which we are doing the crypto
85 * @gfp_flags: The gfp flag for memory allocation
86 *
87 * Allocates and initializes an encryption context.
88 *
89 * Return: An allocated and initialized encryption context on success; error
90 * value or NULL otherwise.
91 */
92struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode, gfp_t gfp_flags)
93{
94 struct fscrypt_ctx *ctx = NULL;
95 struct fscrypt_info *ci = inode->i_crypt_info;
96 unsigned long flags;
97
98 if (ci == NULL)
99 return ERR_PTR(-ENOKEY);
100
101 /*
102 * We first try getting the ctx from a free list because in
103 * the common case the ctx will have an allocated and
104 * initialized crypto tfm, so it's probably a worthwhile
105 * optimization. For the bounce page, we first try getting it
106 * from the kernel allocator because that's just about as fast
107 * as getting it from a list and because a cache of free pages
108 * should generally be a "last resort" option for a filesystem
109 * to be able to do its job.
110 */
111 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
112 ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
113 struct fscrypt_ctx, free_list);
114 if (ctx)
115 list_del(&ctx->free_list);
116 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
117 if (!ctx) {
118 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
119 if (!ctx)
120 return ERR_PTR(-ENOMEM);
121 ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
122 } else {
123 ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
124 }
125 ctx->flags &= ~FS_WRITE_PATH_FL;
126 return ctx;
127}
128EXPORT_SYMBOL(fscrypt_get_ctx);
129
130/**
131 * fscrypt_complete() - The completion callback for page encryption
132 * @req: The asynchronous encryption request context
133 * @res: The result of the encryption operation
134 */
135static void fscrypt_complete(struct crypto_async_request *req, int res)
136{
137 struct fscrypt_completion_result *ecr = req->data;
138
139 if (res == -EINPROGRESS)
140 return;
141 ecr->res = res;
142 complete(&ecr->completion);
143}
144
145typedef enum {
146 FS_DECRYPT = 0,
147 FS_ENCRYPT,
148} fscrypt_direction_t;
149
150static int do_page_crypto(struct inode *inode,
151 fscrypt_direction_t rw, pgoff_t index,
152 struct page *src_page, struct page *dest_page,
153 gfp_t gfp_flags)
154{
155 u8 xts_tweak[FS_XTS_TWEAK_SIZE];
156 struct skcipher_request *req = NULL;
157 DECLARE_FS_COMPLETION_RESULT(ecr);
158 struct scatterlist dst, src;
159 struct fscrypt_info *ci = inode->i_crypt_info;
160 struct crypto_skcipher *tfm = ci->ci_ctfm;
161 int res = 0;
162
163 req = skcipher_request_alloc(tfm, gfp_flags);
164 if (!req) {
165 printk_ratelimited(KERN_ERR
166 "%s: crypto_request_alloc() failed\n",
167 __func__);
168 return -ENOMEM;
169 }
170
171 skcipher_request_set_callback(
172 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
173 fscrypt_complete, &ecr);
174
175 BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index));
176 memcpy(xts_tweak, &index, sizeof(index));
177 memset(&xts_tweak[sizeof(index)], 0,
178 FS_XTS_TWEAK_SIZE - sizeof(index));
179
180 sg_init_table(&dst, 1);
181 sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
182 sg_init_table(&src, 1);
183 sg_set_page(&src, src_page, PAGE_SIZE, 0);
184 skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
185 xts_tweak);
186 if (rw == FS_DECRYPT)
187 res = crypto_skcipher_decrypt(req);
188 else
189 res = crypto_skcipher_encrypt(req);
190 if (res == -EINPROGRESS || res == -EBUSY) {
191 BUG_ON(req->base.data != &ecr);
192 wait_for_completion(&ecr.completion);
193 res = ecr.res;
194 }
195 skcipher_request_free(req);
196 if (res) {
197 printk_ratelimited(KERN_ERR
198 "%s: crypto_skcipher_encrypt() returned %d\n",
199 __func__, res);
200 return res;
201 }
202 return 0;
203}
204
205static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
206{
207 ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
208 if (ctx->w.bounce_page == NULL)
209 return ERR_PTR(-ENOMEM);
210 ctx->flags |= FS_WRITE_PATH_FL;
211 return ctx->w.bounce_page;
212}
213
214/**
215 * fscypt_encrypt_page() - Encrypts a page
216 * @inode: The inode for which the encryption should take place
217 * @plaintext_page: The page to encrypt. Must be locked.
218 * @gfp_flags: The gfp flag for memory allocation
219 *
220 * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
221 * encryption context.
222 *
223 * Called on the page write path. The caller must call
224 * fscrypt_restore_control_page() on the returned ciphertext page to
225 * release the bounce buffer and the encryption context.
226 *
227 * Return: An allocated page with the encrypted content on success. Else, an
228 * error value or NULL.
229 */
230struct page *fscrypt_encrypt_page(struct inode *inode,
231 struct page *plaintext_page, gfp_t gfp_flags)
232{
233 struct fscrypt_ctx *ctx;
234 struct page *ciphertext_page = NULL;
235 int err;
236
237 BUG_ON(!PageLocked(plaintext_page));
238
239 ctx = fscrypt_get_ctx(inode, gfp_flags);
240 if (IS_ERR(ctx))
241 return (struct page *)ctx;
242
243 /* The encryption operation will require a bounce page. */
244 ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
245 if (IS_ERR(ciphertext_page))
246 goto errout;
247
248 ctx->w.control_page = plaintext_page;
249 err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
250 plaintext_page, ciphertext_page,
251 gfp_flags);
252 if (err) {
253 ciphertext_page = ERR_PTR(err);
254 goto errout;
255 }
256 SetPagePrivate(ciphertext_page);
257 set_page_private(ciphertext_page, (unsigned long)ctx);
258 lock_page(ciphertext_page);
259 return ciphertext_page;
260
261errout:
262 fscrypt_release_ctx(ctx);
263 return ciphertext_page;
264}
265EXPORT_SYMBOL(fscrypt_encrypt_page);
266
267/**
268 * f2crypt_decrypt_page() - Decrypts a page in-place
269 * @page: The page to decrypt. Must be locked.
270 *
271 * Decrypts page in-place using the ctx encryption context.
272 *
273 * Called from the read completion callback.
274 *
275 * Return: Zero on success, non-zero otherwise.
276 */
277int fscrypt_decrypt_page(struct page *page)
278{
279 BUG_ON(!PageLocked(page));
280
281 return do_page_crypto(page->mapping->host,
282 FS_DECRYPT, page->index, page, page, GFP_NOFS);
283}
284EXPORT_SYMBOL(fscrypt_decrypt_page);
285
286int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
287 sector_t pblk, unsigned int len)
288{
289 struct fscrypt_ctx *ctx;
290 struct page *ciphertext_page = NULL;
291 struct bio *bio;
292 int ret, err = 0;
293
294 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
295
296 ctx = fscrypt_get_ctx(inode, GFP_NOFS);
297 if (IS_ERR(ctx))
298 return PTR_ERR(ctx);
299
300 ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
301 if (IS_ERR(ciphertext_page)) {
302 err = PTR_ERR(ciphertext_page);
303 goto errout;
304 }
305
306 while (len--) {
307 err = do_page_crypto(inode, FS_ENCRYPT, lblk,
308 ZERO_PAGE(0), ciphertext_page,
309 GFP_NOFS);
310 if (err)
311 goto errout;
312
313 bio = bio_alloc(GFP_NOWAIT, 1);
314 if (!bio) {
315 err = -ENOMEM;
316 goto errout;
317 }
318 bio->bi_bdev = inode->i_sb->s_bdev;
319 bio->bi_iter.bi_sector =
320 pblk << (inode->i_sb->s_blocksize_bits - 9);
321 ret = bio_add_page(bio, ciphertext_page,
322 inode->i_sb->s_blocksize, 0);
323 if (ret != inode->i_sb->s_blocksize) {
324 /* should never happen! */
325 WARN_ON(1);
326 bio_put(bio);
327 err = -EIO;
328 goto errout;
329 }
330 err = submit_bio_wait(WRITE, bio);
331 if ((err == 0) && bio->bi_error)
332 err = -EIO;
333 bio_put(bio);
334 if (err)
335 goto errout;
336 lblk++;
337 pblk++;
338 }
339 err = 0;
340errout:
341 fscrypt_release_ctx(ctx);
342 return err;
343}
344EXPORT_SYMBOL(fscrypt_zeroout_range);
345
346/*
347 * Validate dentries for encrypted directories to make sure we aren't
348 * potentially caching stale data after a key has been added or
349 * removed.
350 */
351static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
352{
353 struct dentry *dir;
354 struct fscrypt_info *ci;
355 int dir_has_key, cached_with_key;
356
357 if (flags & LOOKUP_RCU)
358 return -ECHILD;
359
360 dir = dget_parent(dentry);
361 if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
362 dput(dir);
363 return 0;
364 }
365
366 ci = d_inode(dir)->i_crypt_info;
367 if (ci && ci->ci_keyring_key &&
368 (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
369 (1 << KEY_FLAG_REVOKED) |
370 (1 << KEY_FLAG_DEAD))))
371 ci = NULL;
372
373 /* this should eventually be an flag in d_flags */
374 spin_lock(&dentry->d_lock);
375 cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
376 spin_unlock(&dentry->d_lock);
377 dir_has_key = (ci != NULL);
378 dput(dir);
379
380 /*
381 * If the dentry was cached without the key, and it is a
382 * negative dentry, it might be a valid name. We can't check
383 * if the key has since been made available due to locking
384 * reasons, so we fail the validation so ext4_lookup() can do
385 * this check.
386 *
387 * We also fail the validation if the dentry was created with
388 * the key present, but we no longer have the key, or vice versa.
389 */
390 if ((!cached_with_key && d_is_negative(dentry)) ||
391 (!cached_with_key && dir_has_key) ||
392 (cached_with_key && !dir_has_key))
393 return 0;
394 return 1;
395}
396
397const struct dentry_operations fscrypt_d_ops = {
398 .d_revalidate = fscrypt_d_revalidate,
399};
400EXPORT_SYMBOL(fscrypt_d_ops);
401
402/*
403 * Call fscrypt_decrypt_page on every single page, reusing the encryption
404 * context.
405 */
406static void completion_pages(struct work_struct *work)
407{
408 struct fscrypt_ctx *ctx =
409 container_of(work, struct fscrypt_ctx, r.work);
410 struct bio *bio = ctx->r.bio;
411 struct bio_vec *bv;
412 int i;
413
414 bio_for_each_segment_all(bv, bio, i) {
415 struct page *page = bv->bv_page;
416 int ret = fscrypt_decrypt_page(page);
417
418 if (ret) {
419 WARN_ON_ONCE(1);
420 SetPageError(page);
421 } else {
422 SetPageUptodate(page);
423 }
424 unlock_page(page);
425 }
426 fscrypt_release_ctx(ctx);
427 bio_put(bio);
428}
429
430void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
431{
432 INIT_WORK(&ctx->r.work, completion_pages);
433 ctx->r.bio = bio;
434 queue_work(fscrypt_read_workqueue, &ctx->r.work);
435}
436EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
437
438void fscrypt_pullback_bio_page(struct page **page, bool restore)
439{
440 struct fscrypt_ctx *ctx;
441 struct page *bounce_page;
442
443 /* The bounce data pages are unmapped. */
444 if ((*page)->mapping)
445 return;
446
447 /* The bounce data page is unmapped. */
448 bounce_page = *page;
449 ctx = (struct fscrypt_ctx *)page_private(bounce_page);
450
451 /* restore control page */
452 *page = ctx->w.control_page;
453
454 if (restore)
455 fscrypt_restore_control_page(bounce_page);
456}
457EXPORT_SYMBOL(fscrypt_pullback_bio_page);
458
459void fscrypt_restore_control_page(struct page *page)
460{
461 struct fscrypt_ctx *ctx;
462
463 ctx = (struct fscrypt_ctx *)page_private(page);
464 set_page_private(page, (unsigned long)NULL);
465 ClearPagePrivate(page);
466 unlock_page(page);
467 fscrypt_release_ctx(ctx);
468}
469EXPORT_SYMBOL(fscrypt_restore_control_page);
470
471static void fscrypt_destroy(void)
472{
473 struct fscrypt_ctx *pos, *n;
474
475 list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
476 kmem_cache_free(fscrypt_ctx_cachep, pos);
477 INIT_LIST_HEAD(&fscrypt_free_ctxs);
478 mempool_destroy(fscrypt_bounce_page_pool);
479 fscrypt_bounce_page_pool = NULL;
480}
481
482/**
483 * fscrypt_initialize() - allocate major buffers for fs encryption.
484 *
485 * We only call this when we start accessing encrypted files, since it
486 * results in memory getting allocated that wouldn't otherwise be used.
487 *
488 * Return: Zero on success, non-zero otherwise.
489 */
490int fscrypt_initialize(void)
491{
492 int i, res = -ENOMEM;
493
494 if (fscrypt_bounce_page_pool)
495 return 0;
496
497 mutex_lock(&fscrypt_init_mutex);
498 if (fscrypt_bounce_page_pool)
499 goto already_initialized;
500
501 for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
502 struct fscrypt_ctx *ctx;
503
504 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
505 if (!ctx)
506 goto fail;
507 list_add(&ctx->free_list, &fscrypt_free_ctxs);
508 }
509
510 fscrypt_bounce_page_pool =
511 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
512 if (!fscrypt_bounce_page_pool)
513 goto fail;
514
515already_initialized:
516 mutex_unlock(&fscrypt_init_mutex);
517 return 0;
518fail:
519 fscrypt_destroy();
520 mutex_unlock(&fscrypt_init_mutex);
521 return res;
522}
523EXPORT_SYMBOL(fscrypt_initialize);
524
525/**
526 * fscrypt_init() - Set up for fs encryption.
527 */
528static int __init fscrypt_init(void)
529{
530 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
531 WQ_HIGHPRI, 0);
532 if (!fscrypt_read_workqueue)
533 goto fail;
534
535 fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
536 if (!fscrypt_ctx_cachep)
537 goto fail_free_queue;
538
539 fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
540 if (!fscrypt_info_cachep)
541 goto fail_free_ctx;
542
543 return 0;
544
545fail_free_ctx:
546 kmem_cache_destroy(fscrypt_ctx_cachep);
547fail_free_queue:
548 destroy_workqueue(fscrypt_read_workqueue);
549fail:
550 return -ENOMEM;
551}
552module_init(fscrypt_init)
553
554/**
555 * fscrypt_exit() - Shutdown the fs encryption system
556 */
557static void __exit fscrypt_exit(void)
558{
559 fscrypt_destroy();
560
561 if (fscrypt_read_workqueue)
562 destroy_workqueue(fscrypt_read_workqueue);
563 kmem_cache_destroy(fscrypt_ctx_cachep);
564 kmem_cache_destroy(fscrypt_info_cachep);
565}
566module_exit(fscrypt_exit);
567
568MODULE_LICENSE("GPL");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This contains encryption functions for per-file encryption.
4 *
5 * Copyright (C) 2015, Google, Inc.
6 * Copyright (C) 2015, Motorola Mobility
7 *
8 * Written by Michael Halcrow, 2014.
9 *
10 * Filename encryption additions
11 * Uday Savagaonkar, 2014
12 * Encryption policy handling additions
13 * Ildar Muslukhov, 2014
14 * Add fscrypt_pullback_bio_page()
15 * Jaegeuk Kim, 2015.
16 *
17 * This has not yet undergone a rigorous security audit.
18 *
19 * The usage of AES-XTS should conform to recommendations in NIST
20 * Special Publication 800-38E and IEEE P1619/D16.
21 */
22
23#include <linux/pagemap.h>
24#include <linux/mempool.h>
25#include <linux/module.h>
26#include <linux/scatterlist.h>
27#include <linux/ratelimit.h>
28#include <crypto/skcipher.h>
29#include "fscrypt_private.h"
30
31static unsigned int num_prealloc_crypto_pages = 32;
32
33module_param(num_prealloc_crypto_pages, uint, 0444);
34MODULE_PARM_DESC(num_prealloc_crypto_pages,
35 "Number of crypto pages to preallocate");
36
37static mempool_t *fscrypt_bounce_page_pool = NULL;
38
39static struct workqueue_struct *fscrypt_read_workqueue;
40static DEFINE_MUTEX(fscrypt_init_mutex);
41
42struct kmem_cache *fscrypt_inode_info_cachep;
43
44void fscrypt_enqueue_decrypt_work(struct work_struct *work)
45{
46 queue_work(fscrypt_read_workqueue, work);
47}
48EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
49
50struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
51{
52 if (WARN_ON_ONCE(!fscrypt_bounce_page_pool)) {
53 /*
54 * Oops, the filesystem called a function that uses the bounce
55 * page pool, but it didn't set needs_bounce_pages.
56 */
57 return NULL;
58 }
59 return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
60}
61
62/**
63 * fscrypt_free_bounce_page() - free a ciphertext bounce page
64 * @bounce_page: the bounce page to free, or NULL
65 *
66 * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
67 * or by fscrypt_alloc_bounce_page() directly.
68 */
69void fscrypt_free_bounce_page(struct page *bounce_page)
70{
71 if (!bounce_page)
72 return;
73 set_page_private(bounce_page, (unsigned long)NULL);
74 ClearPagePrivate(bounce_page);
75 mempool_free(bounce_page, fscrypt_bounce_page_pool);
76}
77EXPORT_SYMBOL(fscrypt_free_bounce_page);
78
79/*
80 * Generate the IV for the given data unit index within the given file.
81 * For filenames encryption, index == 0.
82 *
83 * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks()
84 * needs to know about any IV generation methods where the low bits of IV don't
85 * simply contain the data unit index (e.g., IV_INO_LBLK_32).
86 */
87void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index,
88 const struct fscrypt_inode_info *ci)
89{
90 u8 flags = fscrypt_policy_flags(&ci->ci_policy);
91
92 memset(iv, 0, ci->ci_mode->ivsize);
93
94 if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
95 WARN_ON_ONCE(index > U32_MAX);
96 WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX);
97 index |= (u64)ci->ci_inode->i_ino << 32;
98 } else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {
99 WARN_ON_ONCE(index > U32_MAX);
100 index = (u32)(ci->ci_hashed_ino + index);
101 } else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {
102 memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE);
103 }
104 iv->index = cpu_to_le64(index);
105}
106
107/* Encrypt or decrypt a single "data unit" of file contents. */
108int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
109 fscrypt_direction_t rw, u64 index,
110 struct page *src_page, struct page *dest_page,
111 unsigned int len, unsigned int offs,
112 gfp_t gfp_flags)
113{
114 union fscrypt_iv iv;
115 struct skcipher_request *req = NULL;
116 DECLARE_CRYPTO_WAIT(wait);
117 struct scatterlist dst, src;
118 struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
119 int res = 0;
120
121 if (WARN_ON_ONCE(len <= 0))
122 return -EINVAL;
123 if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0))
124 return -EINVAL;
125
126 fscrypt_generate_iv(&iv, index, ci);
127
128 req = skcipher_request_alloc(tfm, gfp_flags);
129 if (!req)
130 return -ENOMEM;
131
132 skcipher_request_set_callback(
133 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
134 crypto_req_done, &wait);
135
136 sg_init_table(&dst, 1);
137 sg_set_page(&dst, dest_page, len, offs);
138 sg_init_table(&src, 1);
139 sg_set_page(&src, src_page, len, offs);
140 skcipher_request_set_crypt(req, &src, &dst, len, &iv);
141 if (rw == FS_DECRYPT)
142 res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
143 else
144 res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
145 skcipher_request_free(req);
146 if (res) {
147 fscrypt_err(ci->ci_inode,
148 "%scryption failed for data unit %llu: %d",
149 (rw == FS_DECRYPT ? "De" : "En"), index, res);
150 return res;
151 }
152 return 0;
153}
154
155/**
156 * fscrypt_encrypt_pagecache_blocks() - Encrypt data from a pagecache page
157 * @page: the locked pagecache page containing the data to encrypt
158 * @len: size of the data to encrypt, in bytes
159 * @offs: offset within @page of the data to encrypt, in bytes
160 * @gfp_flags: memory allocation flags; see details below
161 *
162 * This allocates a new bounce page and encrypts the given data into it. The
163 * length and offset of the data must be aligned to the file's crypto data unit
164 * size. Alignment to the filesystem block size fulfills this requirement, as
165 * the filesystem block size is always a multiple of the data unit size.
166 *
167 * In the bounce page, the ciphertext data will be located at the same offset at
168 * which the plaintext data was located in the source page. Any other parts of
169 * the bounce page will be left uninitialized.
170 *
171 * This is for use by the filesystem's ->writepages() method.
172 *
173 * The bounce page allocation is mempool-backed, so it will always succeed when
174 * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS. However,
175 * only the first page of each bio can be allocated this way. To prevent
176 * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used.
177 *
178 * Return: the new encrypted bounce page on success; an ERR_PTR() on failure
179 */
180struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
181 unsigned int len,
182 unsigned int offs,
183 gfp_t gfp_flags)
184
185{
186 const struct inode *inode = page->mapping->host;
187 const struct fscrypt_inode_info *ci = inode->i_crypt_info;
188 const unsigned int du_bits = ci->ci_data_unit_bits;
189 const unsigned int du_size = 1U << du_bits;
190 struct page *ciphertext_page;
191 u64 index = ((u64)page->index << (PAGE_SHIFT - du_bits)) +
192 (offs >> du_bits);
193 unsigned int i;
194 int err;
195
196 if (WARN_ON_ONCE(!PageLocked(page)))
197 return ERR_PTR(-EINVAL);
198
199 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, du_size)))
200 return ERR_PTR(-EINVAL);
201
202 ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
203 if (!ciphertext_page)
204 return ERR_PTR(-ENOMEM);
205
206 for (i = offs; i < offs + len; i += du_size, index++) {
207 err = fscrypt_crypt_data_unit(ci, FS_ENCRYPT, index,
208 page, ciphertext_page,
209 du_size, i, gfp_flags);
210 if (err) {
211 fscrypt_free_bounce_page(ciphertext_page);
212 return ERR_PTR(err);
213 }
214 }
215 SetPagePrivate(ciphertext_page);
216 set_page_private(ciphertext_page, (unsigned long)page);
217 return ciphertext_page;
218}
219EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks);
220
221/**
222 * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
223 * @inode: The inode to which this block belongs
224 * @page: The page containing the block to encrypt
225 * @len: Size of block to encrypt. This must be a multiple of
226 * FSCRYPT_CONTENTS_ALIGNMENT.
227 * @offs: Byte offset within @page at which the block to encrypt begins
228 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
229 * number of the block within the file
230 * @gfp_flags: Memory allocation flags
231 *
232 * Encrypt a possibly-compressed filesystem block that is located in an
233 * arbitrary page, not necessarily in the original pagecache page. The @inode
234 * and @lblk_num must be specified, as they can't be determined from @page.
235 *
236 * This is not compatible with fscrypt_operations::supports_subblock_data_units.
237 *
238 * Return: 0 on success; -errno on failure
239 */
240int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
241 unsigned int len, unsigned int offs,
242 u64 lblk_num, gfp_t gfp_flags)
243{
244 if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
245 return -EOPNOTSUPP;
246 return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_ENCRYPT,
247 lblk_num, page, page, len, offs,
248 gfp_flags);
249}
250EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
251
252/**
253 * fscrypt_decrypt_pagecache_blocks() - Decrypt data from a pagecache folio
254 * @folio: the pagecache folio containing the data to decrypt
255 * @len: size of the data to decrypt, in bytes
256 * @offs: offset within @folio of the data to decrypt, in bytes
257 *
258 * Decrypt data that has just been read from an encrypted file. The data must
259 * be located in a pagecache folio that is still locked and not yet uptodate.
260 * The length and offset of the data must be aligned to the file's crypto data
261 * unit size. Alignment to the filesystem block size fulfills this requirement,
262 * as the filesystem block size is always a multiple of the data unit size.
263 *
264 * Return: 0 on success; -errno on failure
265 */
266int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
267 size_t offs)
268{
269 const struct inode *inode = folio->mapping->host;
270 const struct fscrypt_inode_info *ci = inode->i_crypt_info;
271 const unsigned int du_bits = ci->ci_data_unit_bits;
272 const unsigned int du_size = 1U << du_bits;
273 u64 index = ((u64)folio->index << (PAGE_SHIFT - du_bits)) +
274 (offs >> du_bits);
275 size_t i;
276 int err;
277
278 if (WARN_ON_ONCE(!folio_test_locked(folio)))
279 return -EINVAL;
280
281 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, du_size)))
282 return -EINVAL;
283
284 for (i = offs; i < offs + len; i += du_size, index++) {
285 struct page *page = folio_page(folio, i >> PAGE_SHIFT);
286
287 err = fscrypt_crypt_data_unit(ci, FS_DECRYPT, index, page,
288 page, du_size, i & ~PAGE_MASK,
289 GFP_NOFS);
290 if (err)
291 return err;
292 }
293 return 0;
294}
295EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
296
297/**
298 * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
299 * @inode: The inode to which this block belongs
300 * @page: The page containing the block to decrypt
301 * @len: Size of block to decrypt. This must be a multiple of
302 * FSCRYPT_CONTENTS_ALIGNMENT.
303 * @offs: Byte offset within @page at which the block to decrypt begins
304 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
305 * number of the block within the file
306 *
307 * Decrypt a possibly-compressed filesystem block that is located in an
308 * arbitrary page, not necessarily in the original pagecache page. The @inode
309 * and @lblk_num must be specified, as they can't be determined from @page.
310 *
311 * This is not compatible with fscrypt_operations::supports_subblock_data_units.
312 *
313 * Return: 0 on success; -errno on failure
314 */
315int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
316 unsigned int len, unsigned int offs,
317 u64 lblk_num)
318{
319 if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
320 return -EOPNOTSUPP;
321 return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_DECRYPT,
322 lblk_num, page, page, len, offs,
323 GFP_NOFS);
324}
325EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
326
327/**
328 * fscrypt_initialize() - allocate major buffers for fs encryption.
329 * @sb: the filesystem superblock
330 *
331 * We only call this when we start accessing encrypted files, since it
332 * results in memory getting allocated that wouldn't otherwise be used.
333 *
334 * Return: 0 on success; -errno on failure
335 */
336int fscrypt_initialize(struct super_block *sb)
337{
338 int err = 0;
339 mempool_t *pool;
340
341 /* pairs with smp_store_release() below */
342 if (likely(smp_load_acquire(&fscrypt_bounce_page_pool)))
343 return 0;
344
345 /* No need to allocate a bounce page pool if this FS won't use it. */
346 if (!sb->s_cop->needs_bounce_pages)
347 return 0;
348
349 mutex_lock(&fscrypt_init_mutex);
350 if (fscrypt_bounce_page_pool)
351 goto out_unlock;
352
353 err = -ENOMEM;
354 pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0);
355 if (!pool)
356 goto out_unlock;
357 /* pairs with smp_load_acquire() above */
358 smp_store_release(&fscrypt_bounce_page_pool, pool);
359 err = 0;
360out_unlock:
361 mutex_unlock(&fscrypt_init_mutex);
362 return err;
363}
364
365void fscrypt_msg(const struct inode *inode, const char *level,
366 const char *fmt, ...)
367{
368 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
369 DEFAULT_RATELIMIT_BURST);
370 struct va_format vaf;
371 va_list args;
372
373 if (!__ratelimit(&rs))
374 return;
375
376 va_start(args, fmt);
377 vaf.fmt = fmt;
378 vaf.va = &args;
379 if (inode && inode->i_ino)
380 printk("%sfscrypt (%s, inode %lu): %pV\n",
381 level, inode->i_sb->s_id, inode->i_ino, &vaf);
382 else if (inode)
383 printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf);
384 else
385 printk("%sfscrypt: %pV\n", level, &vaf);
386 va_end(args);
387}
388
389/**
390 * fscrypt_init() - Set up for fs encryption.
391 *
392 * Return: 0 on success; -errno on failure
393 */
394static int __init fscrypt_init(void)
395{
396 int err = -ENOMEM;
397
398 /*
399 * Use an unbound workqueue to allow bios to be decrypted in parallel
400 * even when they happen to complete on the same CPU. This sacrifices
401 * locality, but it's worthwhile since decryption is CPU-intensive.
402 *
403 * Also use a high-priority workqueue to prioritize decryption work,
404 * which blocks reads from completing, over regular application tasks.
405 */
406 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
407 WQ_UNBOUND | WQ_HIGHPRI,
408 num_online_cpus());
409 if (!fscrypt_read_workqueue)
410 goto fail;
411
412 fscrypt_inode_info_cachep = KMEM_CACHE(fscrypt_inode_info,
413 SLAB_RECLAIM_ACCOUNT);
414 if (!fscrypt_inode_info_cachep)
415 goto fail_free_queue;
416
417 err = fscrypt_init_keyring();
418 if (err)
419 goto fail_free_inode_info;
420
421 return 0;
422
423fail_free_inode_info:
424 kmem_cache_destroy(fscrypt_inode_info_cachep);
425fail_free_queue:
426 destroy_workqueue(fscrypt_read_workqueue);
427fail:
428 return err;
429}
430late_initcall(fscrypt_init)