| blob | 58e4a25065f05d13fc27051951e4a6116afcbb9c |
1 ext4 crypto: add ext4 encryption facilities
3 From: Michael Halcrow <mhalcrow@google.com>
5 On encrypt, we will re-assign the buffer_heads to point to a bounce
6 page rather than the control_page (which is the original page to write
7 that contains the plaintext). The block I/O occurs against the bounce
8 page. On write completion, we re-assign the buffer_heads to the
9 original plaintext page.
11 On decrypt, we will attach a read completion callback to the bio
12 struct. This read completion will decrypt the read contents in-place
13 prior to setting the page up-to-date.
15 The current encryption mode, AES-256-XTS, lacks cryptographic
16 integrity. AES-256-GCM is in-plan, but we will need to devise a
17 mechanism for handling the integrity data.
19 Signed-off-by: Michael Halcrow <mhalcrow@google.com>
20 Signed-off-by: Ildar Muslukhov <ildarm@google.com>
21 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
22 diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile
23 index 3886ee4..1b1c561 100644
24 --- a/fs/ext4/Makefile
25 +++ b/fs/ext4/Makefile
26 @@ -12,4 +12,4 @@ ext4-y := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o page-io.o \
28 ext4-$(CONFIG_EXT4_FS_POSIX_ACL) += acl.o
29 ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o
30 -ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o
31 +ext4-$(CONFIG_EXT4_FS_ENCRYPTION) += crypto_policy.o crypto.o
32 diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
33 new file mode 100644
34 index 0000000..49b1656
35 --- /dev/null
36 +++ b/fs/ext4/crypto.c
37 @@ -0,0 +1,558 @@
38 +/*
39 + * linux/fs/ext4/crypto.c
40 + *
41 + * Copyright (C) 2015, Google, Inc.
42 + *
43 + * This contains encryption functions for ext4
44 + *
45 + * Written by Michael Halcrow, 2014.
46 + *
47 + * Filename encryption additions
48 + * Uday Savagaonkar, 2014
49 + * Encryption policy handling additions
50 + * Ildar Muslukhov, 2014
51 + *
52 + * This has not yet undergone a rigorous security audit.
53 + *
54 + * The usage of AES-XTS should conform to recommendations in NIST
55 + * Special Publication 800-38E and IEEE P1619/D16.
56 + */
57 +
58 +#include <crypto/hash.h>
59 +#include <crypto/sha.h>
60 +#include <keys/user-type.h>
61 +#include <keys/encrypted-type.h>
62 +#include <linux/crypto.h>
63 +#include <linux/ecryptfs.h>
64 +#include <linux/gfp.h>
65 +#include <linux/kernel.h>
66 +#include <linux/key.h>
67 +#include <linux/list.h>
68 +#include <linux/mempool.h>
69 +#include <linux/module.h>
70 +#include <linux/mutex.h>
71 +#include <linux/random.h>
72 +#include <linux/scatterlist.h>
73 +#include <linux/spinlock_types.h>
74 +
75 +#include "ext4_extents.h"
76 +#include "xattr.h"
77 +
78 +/* Encryption added and removed here! (L: */
79 +
80 +static unsigned int num_prealloc_crypto_pages = 32;
81 +static unsigned int num_prealloc_crypto_ctxs = 128;
82 +
83 +module_param(num_prealloc_crypto_pages, uint, 0444);
84 +MODULE_PARM_DESC(num_prealloc_crypto_pages,
85 + "Number of crypto pages to preallocate");
86 +module_param(num_prealloc_crypto_ctxs, uint, 0444);
87 +MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
88 + "Number of crypto contexts to preallocate");
89 +
90 +static mempool_t *ext4_bounce_page_pool;
91 +
92 +static LIST_HEAD(ext4_free_crypto_ctxs);
93 +static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
94 +
95 +/**
96 + * ext4_release_crypto_ctx() - Releases an encryption context
97 + * @ctx: The encryption context to release.
98 + *
99 + * If the encryption context was allocated from the pre-allocated pool, returns
100 + * it to that pool. Else, frees it.
101 + *
102 + * If there's a bounce page in the context, this frees that.
103 + */
104 +void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
105 +{
106 + unsigned long flags;
107 +
108 + if (ctx->bounce_page) {
109 + if (ctx->flags & EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL)
110 + __free_page(ctx->bounce_page);
111 + else
112 + mempool_free(ctx->bounce_page, ext4_bounce_page_pool);
113 + ctx->bounce_page = NULL;
114 + }
115 + ctx->control_page = NULL;
116 + if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
117 + if (ctx->tfm)
118 + crypto_free_tfm(ctx->tfm);
119 + kfree(ctx);
120 + } else {
121 + spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
122 + list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
123 + spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
124 + }
125 +}
126 +
127 +/**
128 + * ext4_alloc_and_init_crypto_ctx() - Allocates and inits an encryption context
129 + * @mask: The allocation mask.
130 + *
131 + * Return: An allocated and initialized encryption context on success. An error
132 + * value or NULL otherwise.
133 + */
134 +static struct ext4_crypto_ctx *ext4_alloc_and_init_crypto_ctx(gfp_t mask)
135 +{
136 + struct ext4_crypto_ctx *ctx = kzalloc(sizeof(struct ext4_crypto_ctx),
137 + mask);
138 +
139 + if (!ctx)
140 + return ERR_PTR(-ENOMEM);
141 + return ctx;
142 +}
143 +
144 +/**
145 + * ext4_get_crypto_ctx() - Gets an encryption context
146 + * @inode: The inode for which we are doing the crypto
147 + *
148 + * Allocates and initializes an encryption context.
149 + *
150 + * Return: An allocated and initialized encryption context on success; error
151 + * value or NULL otherwise.
152 + */
153 +struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)
154 +{
155 + struct ext4_crypto_ctx *ctx = NULL;
156 + int res = 0;
157 + unsigned long flags;
158 + struct ext4_encryption_key *key = &EXT4_I(inode)->i_encryption_key;
159 +
160 + if (!ext4_read_workqueue)
161 + ext4_init_crypto();
162 +
163 + /*
164 + * We first try getting the ctx from a free list because in
165 + * the common case the ctx will have an allocated and
166 + * initialized crypto tfm, so it's probably a worthwhile
167 + * optimization. For the bounce page, we first try getting it
168 + * from the kernel allocator because that's just about as fast
169 + * as getting it from a list and because a cache of free pages
170 + * should generally be a "last resort" option for a filesystem
171 + * to be able to do its job.
172 + */
173 + spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
174 + ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,
175 + struct ext4_crypto_ctx, free_list);
176 + if (ctx)
177 + list_del(&ctx->free_list);
178 + spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
179 + if (!ctx) {
180 + ctx = ext4_alloc_and_init_crypto_ctx(GFP_NOFS);
181 + if (IS_ERR(ctx)) {
182 + res = PTR_ERR(ctx);
183 + goto out;
184 + }
185 + ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
186 + } else {
187 + ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
188 + }
189 +
190 + /* Allocate a new Crypto API context if we don't already have
191 + * one or if it isn't the right mode. */
192 + BUG_ON(key->mode == EXT4_ENCRYPTION_MODE_INVALID);
193 + if (ctx->tfm && (ctx->mode != key->mode)) {
194 + crypto_free_tfm(ctx->tfm);
195 + ctx->tfm = NULL;
196 + ctx->mode = EXT4_ENCRYPTION_MODE_INVALID;
197 + }
198 + if (!ctx->tfm) {
199 + switch (key->mode) {
200 + case EXT4_ENCRYPTION_MODE_AES_256_XTS:
201 + ctx->tfm = crypto_ablkcipher_tfm(
202 + crypto_alloc_ablkcipher("xts(aes)", 0, 0));
203 + break;
204 + case EXT4_ENCRYPTION_MODE_AES_256_GCM:
205 + /* TODO(mhalcrow): AEAD w/ gcm(aes);
206 + * crypto_aead_setauthsize() */
207 + ctx->tfm = ERR_PTR(-ENOTSUPP);
208 + break;
209 + default:
210 + BUG();
211 + }
212 + if (IS_ERR_OR_NULL(ctx->tfm)) {
213 + res = PTR_ERR(ctx->tfm);
214 + ctx->tfm = NULL;
215 + goto out;
216 + }
217 + ctx->mode = key->mode;
218 + }
219 + BUG_ON(key->size != ext4_encryption_key_size(key->mode));
220 +
221 + /* There shouldn't be a bounce page attached to the crypto
222 + * context at this point. */
223 + BUG_ON(ctx->bounce_page);
224 +
225 +out:
226 + if (res) {
227 + if (!IS_ERR_OR_NULL(ctx))
228 + ext4_release_crypto_ctx(ctx);
229 + ctx = ERR_PTR(res);
230 + }
231 + return ctx;
232 +}
233 +
234 +struct workqueue_struct *ext4_read_workqueue;
235 +static DEFINE_MUTEX(crypto_init);
236 +
237 +/**
238 + * ext4_exit_crypto() - Shutdown the ext4 encryption system
239 + */
240 +void ext4_exit_crypto(void)
241 +{
242 + struct ext4_crypto_ctx *pos, *n;
243 +
244 + list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list) {
245 + if (pos->bounce_page) {
246 + if (pos->flags &
247 + EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL) {
248 + __free_page(pos->bounce_page);
249 + } else {
250 + mempool_free(pos->bounce_page,
251 + ext4_bounce_page_pool);
252 + }
253 + }
254 + if (pos->tfm)
255 + crypto_free_tfm(pos->tfm);
256 + kfree(pos);
257 + }
258 + INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
259 + if (ext4_bounce_page_pool)
260 + mempool_destroy(ext4_bounce_page_pool);
261 + ext4_bounce_page_pool = NULL;
262 + if (ext4_read_workqueue)
263 + destroy_workqueue(ext4_read_workqueue);
264 + ext4_read_workqueue = NULL;
265 +}
266 +
267 +/**
268 + * ext4_init_crypto() - Set up for ext4 encryption.
269 + *
270 + * We only call this when we start accessing encrypted files, since it
271 + * results in memory getting allocated that wouldn't otherwise be used.
272 + *
273 + * Return: Zero on success, non-zero otherwise.
274 + */
275 +int ext4_init_crypto(void)
276 +{
277 + int i, res;
278 +
279 + mutex_lock(&crypto_init);
280 + if (ext4_read_workqueue)
281 + goto already_initialized;
282 + ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
283 + if (!ext4_read_workqueue) {
284 + res = -ENOMEM;
285 + goto fail;
286 + }
287 +
288 + for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
289 + struct ext4_crypto_ctx *ctx;
290 +
291 + ctx = ext4_alloc_and_init_crypto_ctx(GFP_KERNEL);
292 + if (IS_ERR(ctx)) {
293 + res = PTR_ERR(ctx);
294 + goto fail;
295 + }
296 + list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
297 + }
298 +
299 + ext4_bounce_page_pool =
300 + mempool_create_page_pool(num_prealloc_crypto_pages, 0);
301 + if (!ext4_bounce_page_pool) {
302 + res = -ENOMEM;
303 + goto fail;
304 + }
305 +already_initialized:
306 + mutex_unlock(&crypto_init);
307 + return 0;
308 +fail:
309 + ext4_exit_crypto();
310 + mutex_unlock(&crypto_init);
311 + return res;
312 +}
313 +
314 +void ext4_restore_control_page(struct page *data_page)
315 +{
316 + struct ext4_crypto_ctx *ctx =
317 + (struct ext4_crypto_ctx *)page_private(data_page);
318 +
319 + set_page_private(data_page, (unsigned long)NULL);
320 + ClearPagePrivate(data_page);
321 + unlock_page(data_page);
322 + ext4_release_crypto_ctx(ctx);
323 +}
324 +
325 +/**
326 + * ext4_crypt_complete() - The completion callback for page encryption
327 + * @req: The asynchronous encryption request context
328 + * @res: The result of the encryption operation
329 + */
330 +static void ext4_crypt_complete(struct crypto_async_request *req, int res)
331 +{
332 + struct ext4_completion_result *ecr = req->data;
333 +
334 + if (res == -EINPROGRESS)
335 + return;
336 + ecr->res = res;
337 + complete(&ecr->completion);
338 +}
339 +
340 +typedef enum {
341 + EXT4_DECRYPT = 0,
342 + EXT4_ENCRYPT,
343 +} ext4_direction_t;
344 +
345 +static int ext4_page_crypto(struct ext4_crypto_ctx *ctx,
346 + struct inode *inode,
347 + ext4_direction_t rw,
348 + pgoff_t index,
349 + struct page *src_page,
350 + struct page *dest_page)
351 +
352 +{
353 + u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
354 + struct ablkcipher_request *req = NULL;
355 + DECLARE_EXT4_COMPLETION_RESULT(ecr);
356 + struct scatterlist dst, src;
357 + struct ext4_inode_info *ei = EXT4_I(inode);
358 + struct crypto_ablkcipher *atfm = __crypto_ablkcipher_cast(ctx->tfm);
359 + int res = 0;
360 +
361 + BUG_ON(!ctx->tfm);
362 + BUG_ON(ctx->mode != ei->i_encryption_key.mode);
363 +
364 + if (ctx->mode != EXT4_ENCRYPTION_MODE_AES_256_XTS) {
365 + printk_ratelimited(KERN_ERR
366 + "%s: unsupported crypto algorithm: %d\n",
367 + __func__, ctx->mode);
368 + return -ENOTSUPP;
369 + }
370 +
371 + crypto_ablkcipher_clear_flags(atfm, ~0);
372 + crypto_tfm_set_flags(ctx->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
373 +
374 + res = crypto_ablkcipher_setkey(atfm, ei->i_encryption_key.raw,
375 + ei->i_encryption_key.size);
376 + if (res) {
377 + printk_ratelimited(KERN_ERR
378 + "%s: crypto_ablkcipher_setkey() failed\n",
379 + __func__);
380 + return res;
381 + }
382 + req = ablkcipher_request_alloc(atfm, GFP_NOFS);
383 + if (!req) {
384 + printk_ratelimited(KERN_ERR
385 + "%s: crypto_request_alloc() failed\n",
386 + __func__);
387 + return -ENOMEM;
388 + }
389 + ablkcipher_request_set_callback(
390 + req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
391 + ext4_crypt_complete, &ecr);
392 +
393 + BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));
394 + memcpy(xts_tweak, &index, sizeof(index));
395 + memset(&xts_tweak[sizeof(index)], 0,
396 + EXT4_XTS_TWEAK_SIZE - sizeof(index));
397 +
398 + sg_init_table(&dst, 1);
399 + sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0);
400 + sg_init_table(&src, 1);
401 + sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0);
402 + ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE,
403 + xts_tweak);
404 + if (rw == EXT4_DECRYPT)
405 + res = crypto_ablkcipher_decrypt(req);
406 + else
407 + res = crypto_ablkcipher_encrypt(req);
408 + if (res == -EINPROGRESS || res == -EBUSY) {
409 + BUG_ON(req->base.data != &ecr);
410 + wait_for_completion(&ecr.completion);
411 + res = ecr.res;
412 + }
413 + ablkcipher_request_free(req);
414 + if (res) {
415 + printk_ratelimited(
416 + KERN_ERR
417 + "%s: crypto_ablkcipher_encrypt() returned %d\n",
418 + __func__, res);
419 + return res;
420 + }
421 + return 0;
422 +}
423 +
424 +/**
425 + * ext4_encrypt() - Encrypts a page
426 + * @inode: The inode for which the encryption should take place
427 + * @plaintext_page: The page to encrypt. Must be locked.
428 + *
429 + * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
430 + * encryption context.
431 + *
432 + * Called on the page write path. The caller must call
433 + * ext4_restore_control_page() on the returned ciphertext page to
434 + * release the bounce buffer and the encryption context.
435 + *
436 + * Return: An allocated page with the encrypted content on success. Else, an
437 + * error value or NULL.
438 + */
439 +struct page *ext4_encrypt(struct inode *inode,
440 + struct page *plaintext_page)
441 +{
442 + struct ext4_crypto_ctx *ctx;
443 + struct page *ciphertext_page = NULL;
444 + int err;
445 +
446 + BUG_ON(!PageLocked(plaintext_page));
447 +
448 + ctx = ext4_get_crypto_ctx(inode);
449 + if (IS_ERR(ctx))
450 + return (struct page *) ctx;
451 +
452 + /* The encryption operation will require a bounce page. */
453 + ciphertext_page = alloc_page(GFP_NOFS);
454 + if (!ciphertext_page) {
455 + /* This is a potential bottleneck, but at least we'll have
456 + * forward progress. */
457 + ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
458 + GFP_NOFS);
459 + if (WARN_ON_ONCE(!ciphertext_page)) {
460 + ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
461 + GFP_NOFS | __GFP_WAIT);
462 + }
463 + ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
464 + } else {
465 + ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
466 + }
467 + ctx->bounce_page = ciphertext_page;
468 + ctx->control_page = plaintext_page;
469 + err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, plaintext_page->index,
470 + plaintext_page, ciphertext_page);
471 + if (err) {
472 + ext4_release_crypto_ctx(ctx);
473 + return ERR_PTR(err);
474 + }
475 + SetPagePrivate(ciphertext_page);
476 + set_page_private(ciphertext_page, (unsigned long)ctx);
477 + lock_page(ciphertext_page);
478 + return ciphertext_page;
479 +}
480 +
481 +/**
482 + * ext4_decrypt() - Decrypts a page in-place
483 + * @ctx: The encryption context.
484 + * @page: The page to decrypt. Must be locked.
485 + *
486 + * Decrypts page in-place using the ctx encryption context.
487 + *
488 + * Called from the read completion callback.
489 + *
490 + * Return: Zero on success, non-zero otherwise.
491 + */
492 +int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page)
493 +{
494 + BUG_ON(!PageLocked(page));
495 +
496 + return ext4_page_crypto(ctx, page->mapping->host,
497 + EXT4_DECRYPT, page->index, page, page);
498 +}
499 +
500 +/*
501 + * Convenience function which takes care of allocating and
502 + * deallocating the encryption context
503 + */
504 +int ext4_decrypt_one(struct inode *inode, struct page *page)
505 +{
506 + int ret;
507 +
508 + struct ext4_crypto_ctx *ctx = ext4_get_crypto_ctx(inode);
509 +
510 + if (!ctx)
511 + return -ENOMEM;
512 + ret = ext4_decrypt(ctx, page);
513 + ext4_release_crypto_ctx(ctx);
514 + return ret;
515 +}
516 +
517 +int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex)
518 +{
519 + struct ext4_crypto_ctx *ctx;
520 + struct page *ciphertext_page = NULL;
521 + struct bio *bio;
522 + ext4_lblk_t lblk = ex->ee_block;
523 + ext4_fsblk_t pblk = ext4_ext_pblock(ex);
524 + unsigned int len = ext4_ext_get_actual_len(ex);
525 + int err = 0;
526 +
527 + BUG_ON(inode->i_sb->s_blocksize != PAGE_CACHE_SIZE);
528 +
529 + ctx = ext4_get_crypto_ctx(inode);
530 + if (IS_ERR(ctx))
531 + return PTR_ERR(ctx);
532 +
533 + ciphertext_page = alloc_page(GFP_NOFS);
534 + if (!ciphertext_page) {
535 + /* This is a potential bottleneck, but at least we'll have
536 + * forward progress. */
537 + ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
538 + GFP_NOFS);
539 + if (WARN_ON_ONCE(!ciphertext_page)) {
540 + ciphertext_page = mempool_alloc(ext4_bounce_page_pool,
541 + GFP_NOFS | __GFP_WAIT);
542 + }
543 + ctx->flags &= ~EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
544 + } else {
545 + ctx->flags |= EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
546 + }
547 + ctx->bounce_page = ciphertext_page;
548 +
549 + while (len--) {
550 + err = ext4_page_crypto(ctx, inode, EXT4_ENCRYPT, lblk,
551 + ZERO_PAGE(0), ciphertext_page);
552 + if (err)
553 + goto errout;
554 +
555 + bio = bio_alloc(GFP_KERNEL, 1);
556 + if (!bio) {
557 + err = -ENOMEM;
558 + goto errout;
559 + }
560 + bio->bi_bdev = inode->i_sb->s_bdev;
561 + bio->bi_iter.bi_sector = pblk;
562 + err = bio_add_page(bio, ciphertext_page,
563 + inode->i_sb->s_blocksize, 0);
564 + if (err) {
565 + bio_put(bio);
566 + goto errout;
567 + }
568 + err = submit_bio_wait(WRITE, bio);
569 + if (err)
570 + goto errout;
571 + }
572 + err = 0;
573 +errout:
574 + ext4_release_crypto_ctx(ctx);
575 + return err;
576 +}
577 +
578 +bool ext4_valid_contents_enc_mode(uint32_t mode)
579 +{
580 + return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);
581 +}
582 +
583 +/**
584 + * ext4_validate_encryption_key_size() - Validate the encryption key size
585 + * @mode: The key mode.
586 + * @size: The key size to validate.
587 + *
588 + * Return: The validated key size for @mode. Zero if invalid.
589 + */
590 +uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
591 +{
592 + if (size == ext4_encryption_key_size(mode))
593 + return size;
594 + return 0;
595 +}
596 diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
597 index 532b69c..a4bf762 100644
598 --- a/fs/ext4/crypto_policy.c
599 +++ b/fs/ext4/crypto_policy.c
600 @@ -52,6 +52,13 @@ static int ext4_create_encryption_context_from_policy(
601 ctx.format = EXT4_ENCRYPTION_CONTEXT_FORMAT_V1;
602 memcpy(ctx.master_key_descriptor, policy->master_key_descriptor,
603 EXT4_KEY_DESCRIPTOR_SIZE);
604 + if (!ext4_valid_contents_enc_mode(policy->contents_encryption_mode)) {
605 + printk(KERN_WARNING
606 + "%s: Invalid contents encryption mode %d\n", __func__,
607 + policy->contents_encryption_mode);
608 + res = -EINVAL;
609 + goto out;
610 + }
611 ctx.contents_encryption_mode = policy->contents_encryption_mode;
612 ctx.filenames_encryption_mode = policy->filenames_encryption_mode;
613 BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
614 @@ -60,6 +67,7 @@ static int ext4_create_encryption_context_from_policy(
615 res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
616 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
617 sizeof(ctx), 0);
618 +out:
619 if (!res)
620 ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
621 return res;
622 diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
623 index e0956b7..620179e 100644
624 --- a/fs/ext4/ext4.h
625 +++ b/fs/ext4/ext4.h
626 @@ -951,6 +951,11 @@ struct ext4_inode_info {
628 /* Precomputed uuid+inum+igen checksum for seeding inode checksums */
629 __u32 i_csum_seed;
630 +
631 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
632 + /* Encryption params */
633 + struct ext4_encryption_key i_encryption_key;
634 +#endif
635 };
637 /*
638 @@ -1355,6 +1360,12 @@ struct ext4_sb_info {
639 struct ratelimit_state s_err_ratelimit_state;
640 struct ratelimit_state s_warning_ratelimit_state;
641 struct ratelimit_state s_msg_ratelimit_state;
642 +
643 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
644 + /* Encryption */
645 + uint32_t s_file_encryption_mode;
646 + uint32_t s_dir_encryption_mode;
647 +#endif
648 };
650 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
651 @@ -1470,6 +1481,18 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
652 #define EXT4_SB(sb) (sb)
653 #endif
655 +/*
656 + * Returns true if the inode is inode is encrypted
657 + */
658 +static inline int ext4_encrypted_inode(struct inode *inode)
659 +{
660 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
661 + return ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT);
662 +#else
663 + return 0;
664 +#endif
665 +}
666 +
667 #define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime
669 /*
670 @@ -2014,6 +2037,35 @@ int ext4_process_policy(const struct ext4_encryption_policy *policy,
671 int ext4_get_policy(struct inode *inode,
672 struct ext4_encryption_policy *policy);
674 +/* crypto.c */
675 +bool ext4_valid_contents_enc_mode(uint32_t mode);
676 +uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);
677 +extern struct workqueue_struct *ext4_read_workqueue;
678 +struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode);
679 +void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);
680 +void ext4_restore_control_page(struct page *data_page);
681 +struct page *ext4_encrypt(struct inode *inode,
682 + struct page *plaintext_page);
683 +int ext4_decrypt(struct ext4_crypto_ctx *ctx, struct page *page);
684 +int ext4_decrypt_one(struct inode *inode, struct page *page);
685 +int ext4_encrypted_zeroout(struct inode *inode, struct ext4_extent *ex);
686 +
687 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
688 +int ext4_init_crypto(void);
689 +void ext4_exit_crypto(void);
690 +static inline int ext4_sb_has_crypto(struct super_block *sb)
691 +{
692 + return EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_ENCRYPT);
693 +}
694 +#else
695 +static inline int ext4_init_crypto(void) { return 0; }
696 +static inline void ext4_exit_crypto(void) { }
697 +static inline int ext4_sb_has_crypto(struct super_block *sb)
698 +{
699 + return 0;
700 +}
701 +#endif
702 +
703 /* dir.c */
704 extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
705 struct file *,
706 diff --git a/fs/ext4/ext4_crypto.h b/fs/ext4/ext4_crypto.h
707 index a69d2ba..9d5d2e5 100644
708 --- a/fs/ext4/ext4_crypto.h
709 +++ b/fs/ext4/ext4_crypto.h
710 @@ -46,4 +46,59 @@ struct ext4_encryption_context {
711 char nonce[EXT4_KEY_DERIVATION_NONCE_SIZE];
712 } __attribute__((__packed__));
714 +/* Encryption parameters */
715 +#define EXT4_XTS_TWEAK_SIZE 16
716 +#define EXT4_AES_128_ECB_KEY_SIZE 16
717 +#define EXT4_AES_256_GCM_KEY_SIZE 32
718 +#define EXT4_AES_256_CBC_KEY_SIZE 32
719 +#define EXT4_AES_256_CTS_KEY_SIZE 32
720 +#define EXT4_AES_256_XTS_KEY_SIZE 64
721 +#define EXT4_MAX_KEY_SIZE 64
722 +
723 +struct ext4_encryption_key {
724 + uint32_t mode;
725 + char raw[EXT4_MAX_KEY_SIZE];
726 + uint32_t size;
727 +};
728 +
729 +#define EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL 0x00000001
730 +#define EXT4_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL 0x00000002
731 +
732 +struct ext4_crypto_ctx {
733 + struct crypto_tfm *tfm; /* Crypto API context */
734 + struct page *bounce_page; /* Ciphertext page on write path */
735 + struct page *control_page; /* Original page on write path */
736 + struct bio *bio; /* The bio for this context */
737 + struct work_struct work; /* Work queue for read complete path */
738 + struct list_head free_list; /* Free list */
739 + int flags; /* Flags */
740 + int mode; /* Encryption mode for tfm */
741 +};
742 +
743 +struct ext4_completion_result {
744 + struct completion completion;
745 + int res;
746 +};
747 +
748 +#define DECLARE_EXT4_COMPLETION_RESULT(ecr) \
749 + struct ext4_completion_result ecr = { \
750 + COMPLETION_INITIALIZER((ecr).completion), 0 }
751 +
752 +static inline int ext4_encryption_key_size(int mode)
753 +{
754 + switch (mode) {
755 + case EXT4_ENCRYPTION_MODE_AES_256_XTS:
756 + return EXT4_AES_256_XTS_KEY_SIZE;
757 + case EXT4_ENCRYPTION_MODE_AES_256_GCM:
758 + return EXT4_AES_256_GCM_KEY_SIZE;
759 + case EXT4_ENCRYPTION_MODE_AES_256_CBC:
760 + return EXT4_AES_256_CBC_KEY_SIZE;
761 + case EXT4_ENCRYPTION_MODE_AES_256_CTS:
762 + return EXT4_AES_256_CTS_KEY_SIZE;
763 + default:
764 + BUG();
765 + }
766 + return 0;
767 +}
768 +
769 #endif /* _EXT4_CRYPTO_H */
770 diff --git a/fs/ext4/super.c b/fs/ext4/super.c
771 index 74c5f53..1a44e74 100644
772 --- a/fs/ext4/super.c
773 +++ b/fs/ext4/super.c
774 @@ -893,6 +893,9 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
775 atomic_set(&ei->i_ioend_count, 0);
776 atomic_set(&ei->i_unwritten, 0);
777 INIT_WORK(&ei->i_rsv_conversion_work, ext4_end_io_rsv_work);
778 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
779 + ei->i_encryption_key.mode = EXT4_ENCRYPTION_MODE_INVALID;
780 +#endif
782 return &ei->vfs_inode;
783 }
784 @@ -3439,6 +3442,11 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
785 if (sb->s_bdev->bd_part)
786 sbi->s_sectors_written_start =
787 part_stat_read(sb->s_bdev->bd_part, sectors[1]);
788 +#ifdef CONFIG_EXT4_FS_ENCRYPTION
789 + /* Modes of operations for file and directory encryption. */
790 + sbi->s_file_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
791 + sbi->s_dir_encryption_mode = EXT4_ENCRYPTION_MODE_INVALID;
792 +#endif
794 /* Cleanup superblock name */
795 for (cp = sb->s_id; (cp = strchr(cp, '/'));)