2 * linux/fs/f2fs/crypto.c
4 * Copied from linux/fs/ext4/crypto.c
6 * Copyright (C) 2015, Google, Inc.
7 * Copyright (C) 2015, Motorola Mobility
9 * This contains encryption functions for f2fs
11 * Written by Michael Halcrow, 2014.
13 * Filename encryption additions
14 * Uday Savagaonkar, 2014
15 * Encryption policy handling additions
16 * Ildar Muslukhov, 2014
17 * Remove ext4_encrypted_zeroout(),
18 * add f2fs_restore_and_release_control_page()
21 * This has not yet undergone a rigorous security audit.
23 * The usage of AES-XTS should conform to recommendations in NIST
24 * Special Publication 800-38E and IEEE P1619/D16.
26 #include <crypto/skcipher.h>
27 #include <keys/user-type.h>
28 #include <keys/encrypted-type.h>
29 #include <linux/ecryptfs.h>
30 #include <linux/gfp.h>
31 #include <linux/kernel.h>
32 #include <linux/key.h>
33 #include <linux/list.h>
34 #include <linux/mempool.h>
35 #include <linux/module.h>
36 #include <linux/mutex.h>
37 #include <linux/random.h>
38 #include <linux/scatterlist.h>
39 #include <linux/spinlock_types.h>
40 #include <linux/f2fs_fs.h>
41 #include <linux/ratelimit.h>
42 #include <linux/bio.h>
47 /* Encryption added and removed here! (L: */
49 static unsigned int num_prealloc_crypto_pages
= 32;
50 static unsigned int num_prealloc_crypto_ctxs
= 128;
52 module_param(num_prealloc_crypto_pages
, uint
, 0444);
53 MODULE_PARM_DESC(num_prealloc_crypto_pages
,
54 "Number of crypto pages to preallocate");
55 module_param(num_prealloc_crypto_ctxs
, uint
, 0444);
56 MODULE_PARM_DESC(num_prealloc_crypto_ctxs
,
57 "Number of crypto contexts to preallocate");
59 static mempool_t
*f2fs_bounce_page_pool
;
61 static LIST_HEAD(f2fs_free_crypto_ctxs
);
62 static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock
);
64 static struct workqueue_struct
*f2fs_read_workqueue
;
65 static DEFINE_MUTEX(crypto_init
);
67 static struct kmem_cache
*f2fs_crypto_ctx_cachep
;
68 struct kmem_cache
*f2fs_crypt_info_cachep
;
71 * f2fs_release_crypto_ctx() - Releases an encryption context
72 * @ctx: The encryption context to release.
74 * If the encryption context was allocated from the pre-allocated pool, returns
75 * it to that pool. Else, frees it.
77 * If there's a bounce page in the context, this frees that.
79 void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx
*ctx
)
83 if (ctx
->flags
& F2FS_WRITE_PATH_FL
&& ctx
->w
.bounce_page
) {
84 mempool_free(ctx
->w
.bounce_page
, f2fs_bounce_page_pool
);
85 ctx
->w
.bounce_page
= NULL
;
87 ctx
->w
.control_page
= NULL
;
88 if (ctx
->flags
& F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL
) {
89 kmem_cache_free(f2fs_crypto_ctx_cachep
, ctx
);
91 spin_lock_irqsave(&f2fs_crypto_ctx_lock
, flags
);
92 list_add(&ctx
->free_list
, &f2fs_free_crypto_ctxs
);
93 spin_unlock_irqrestore(&f2fs_crypto_ctx_lock
, flags
);
98 * f2fs_get_crypto_ctx() - Gets an encryption context
99 * @inode: The inode for which we are doing the crypto
101 * Allocates and initializes an encryption context.
103 * Return: An allocated and initialized encryption context on success; error
104 * value or NULL otherwise.
106 struct f2fs_crypto_ctx
*f2fs_get_crypto_ctx(struct inode
*inode
)
108 struct f2fs_crypto_ctx
*ctx
= NULL
;
110 struct f2fs_crypt_info
*ci
= F2FS_I(inode
)->i_crypt_info
;
113 return ERR_PTR(-ENOKEY
);
116 * We first try getting the ctx from a free list because in
117 * the common case the ctx will have an allocated and
118 * initialized crypto tfm, so it's probably a worthwhile
119 * optimization. For the bounce page, we first try getting it
120 * from the kernel allocator because that's just about as fast
121 * as getting it from a list and because a cache of free pages
122 * should generally be a "last resort" option for a filesystem
123 * to be able to do its job.
125 spin_lock_irqsave(&f2fs_crypto_ctx_lock
, flags
);
126 ctx
= list_first_entry_or_null(&f2fs_free_crypto_ctxs
,
127 struct f2fs_crypto_ctx
, free_list
);
129 list_del(&ctx
->free_list
);
130 spin_unlock_irqrestore(&f2fs_crypto_ctx_lock
, flags
);
132 ctx
= kmem_cache_zalloc(f2fs_crypto_ctx_cachep
, GFP_NOFS
);
134 return ERR_PTR(-ENOMEM
);
135 ctx
->flags
|= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL
;
137 ctx
->flags
&= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL
;
139 ctx
->flags
&= ~F2FS_WRITE_PATH_FL
;
144 * Call f2fs_decrypt on every single page, reusing the encryption
147 static void completion_pages(struct work_struct
*work
)
149 struct f2fs_crypto_ctx
*ctx
=
150 container_of(work
, struct f2fs_crypto_ctx
, r
.work
);
151 struct bio
*bio
= ctx
->r
.bio
;
155 bio_for_each_segment_all(bv
, bio
, i
) {
156 struct page
*page
= bv
->bv_page
;
157 int ret
= f2fs_decrypt(ctx
, page
);
163 SetPageUptodate(page
);
166 f2fs_release_crypto_ctx(ctx
);
170 void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx
*ctx
, struct bio
*bio
)
172 INIT_WORK(&ctx
->r
.work
, completion_pages
);
174 queue_work(f2fs_read_workqueue
, &ctx
->r
.work
);
177 static void f2fs_crypto_destroy(void)
179 struct f2fs_crypto_ctx
*pos
, *n
;
181 list_for_each_entry_safe(pos
, n
, &f2fs_free_crypto_ctxs
, free_list
)
182 kmem_cache_free(f2fs_crypto_ctx_cachep
, pos
);
183 INIT_LIST_HEAD(&f2fs_free_crypto_ctxs
);
184 if (f2fs_bounce_page_pool
)
185 mempool_destroy(f2fs_bounce_page_pool
);
186 f2fs_bounce_page_pool
= NULL
;
190 * f2fs_crypto_initialize() - Set up for f2fs encryption.
192 * We only call this when we start accessing encrypted files, since it
193 * results in memory getting allocated that wouldn't otherwise be used.
195 * Return: Zero on success, non-zero otherwise.
197 int f2fs_crypto_initialize(void)
199 int i
, res
= -ENOMEM
;
201 if (f2fs_bounce_page_pool
)
204 mutex_lock(&crypto_init
);
205 if (f2fs_bounce_page_pool
)
206 goto already_initialized
;
208 for (i
= 0; i
< num_prealloc_crypto_ctxs
; i
++) {
209 struct f2fs_crypto_ctx
*ctx
;
211 ctx
= kmem_cache_zalloc(f2fs_crypto_ctx_cachep
, GFP_KERNEL
);
214 list_add(&ctx
->free_list
, &f2fs_free_crypto_ctxs
);
217 /* must be allocated at the last step to avoid race condition above */
218 f2fs_bounce_page_pool
=
219 mempool_create_page_pool(num_prealloc_crypto_pages
, 0);
220 if (!f2fs_bounce_page_pool
)
224 mutex_unlock(&crypto_init
);
227 f2fs_crypto_destroy();
228 mutex_unlock(&crypto_init
);
233 * f2fs_exit_crypto() - Shutdown the f2fs encryption system
235 void f2fs_exit_crypto(void)
237 f2fs_crypto_destroy();
239 if (f2fs_read_workqueue
)
240 destroy_workqueue(f2fs_read_workqueue
);
241 if (f2fs_crypto_ctx_cachep
)
242 kmem_cache_destroy(f2fs_crypto_ctx_cachep
);
243 if (f2fs_crypt_info_cachep
)
244 kmem_cache_destroy(f2fs_crypt_info_cachep
);
247 int __init
f2fs_init_crypto(void)
251 f2fs_read_workqueue
= alloc_workqueue("f2fs_crypto", WQ_HIGHPRI
, 0);
252 if (!f2fs_read_workqueue
)
255 f2fs_crypto_ctx_cachep
= KMEM_CACHE(f2fs_crypto_ctx
,
256 SLAB_RECLAIM_ACCOUNT
);
257 if (!f2fs_crypto_ctx_cachep
)
260 f2fs_crypt_info_cachep
= KMEM_CACHE(f2fs_crypt_info
,
261 SLAB_RECLAIM_ACCOUNT
);
262 if (!f2fs_crypt_info_cachep
)
271 void f2fs_restore_and_release_control_page(struct page
**page
)
273 struct f2fs_crypto_ctx
*ctx
;
274 struct page
*bounce_page
;
276 /* The bounce data pages are unmapped. */
277 if ((*page
)->mapping
)
280 /* The bounce data page is unmapped. */
282 ctx
= (struct f2fs_crypto_ctx
*)page_private(bounce_page
);
284 /* restore control page */
285 *page
= ctx
->w
.control_page
;
287 f2fs_restore_control_page(bounce_page
);
290 void f2fs_restore_control_page(struct page
*data_page
)
292 struct f2fs_crypto_ctx
*ctx
=
293 (struct f2fs_crypto_ctx
*)page_private(data_page
);
295 set_page_private(data_page
, (unsigned long)NULL
);
296 ClearPagePrivate(data_page
);
297 unlock_page(data_page
);
298 f2fs_release_crypto_ctx(ctx
);
302 * f2fs_crypt_complete() - The completion callback for page encryption
303 * @req: The asynchronous encryption request context
304 * @res: The result of the encryption operation
306 static void f2fs_crypt_complete(struct crypto_async_request
*req
, int res
)
308 struct f2fs_completion_result
*ecr
= req
->data
;
310 if (res
== -EINPROGRESS
)
313 complete(&ecr
->completion
);
321 static int f2fs_page_crypto(struct f2fs_crypto_ctx
*ctx
,
325 struct page
*src_page
,
326 struct page
*dest_page
)
328 u8 xts_tweak
[F2FS_XTS_TWEAK_SIZE
];
329 struct skcipher_request
*req
= NULL
;
330 DECLARE_F2FS_COMPLETION_RESULT(ecr
);
331 struct scatterlist dst
, src
;
332 struct f2fs_crypt_info
*ci
= F2FS_I(inode
)->i_crypt_info
;
333 struct crypto_skcipher
*tfm
= ci
->ci_ctfm
;
336 req
= skcipher_request_alloc(tfm
, GFP_NOFS
);
338 printk_ratelimited(KERN_ERR
339 "%s: crypto_request_alloc() failed\n",
343 skcipher_request_set_callback(
344 req
, CRYPTO_TFM_REQ_MAY_BACKLOG
| CRYPTO_TFM_REQ_MAY_SLEEP
,
345 f2fs_crypt_complete
, &ecr
);
347 BUILD_BUG_ON(F2FS_XTS_TWEAK_SIZE
< sizeof(index
));
348 memcpy(xts_tweak
, &index
, sizeof(index
));
349 memset(&xts_tweak
[sizeof(index
)], 0,
350 F2FS_XTS_TWEAK_SIZE
- sizeof(index
));
352 sg_init_table(&dst
, 1);
353 sg_set_page(&dst
, dest_page
, PAGE_CACHE_SIZE
, 0);
354 sg_init_table(&src
, 1);
355 sg_set_page(&src
, src_page
, PAGE_CACHE_SIZE
, 0);
356 skcipher_request_set_crypt(req
, &src
, &dst
, PAGE_CACHE_SIZE
,
358 if (rw
== F2FS_DECRYPT
)
359 res
= crypto_skcipher_decrypt(req
);
361 res
= crypto_skcipher_encrypt(req
);
362 if (res
== -EINPROGRESS
|| res
== -EBUSY
) {
363 BUG_ON(req
->base
.data
!= &ecr
);
364 wait_for_completion(&ecr
.completion
);
367 skcipher_request_free(req
);
369 printk_ratelimited(KERN_ERR
370 "%s: crypto_skcipher_encrypt() returned %d\n",
377 static struct page
*alloc_bounce_page(struct f2fs_crypto_ctx
*ctx
)
379 ctx
->w
.bounce_page
= mempool_alloc(f2fs_bounce_page_pool
, GFP_NOWAIT
);
380 if (ctx
->w
.bounce_page
== NULL
)
381 return ERR_PTR(-ENOMEM
);
382 ctx
->flags
|= F2FS_WRITE_PATH_FL
;
383 return ctx
->w
.bounce_page
;
387 * f2fs_encrypt() - Encrypts a page
388 * @inode: The inode for which the encryption should take place
389 * @plaintext_page: The page to encrypt. Must be locked.
391 * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
392 * encryption context.
394 * Called on the page write path. The caller must call
395 * f2fs_restore_control_page() on the returned ciphertext page to
396 * release the bounce buffer and the encryption context.
398 * Return: An allocated page with the encrypted content on success. Else, an
399 * error value or NULL.
401 struct page
*f2fs_encrypt(struct inode
*inode
,
402 struct page
*plaintext_page
)
404 struct f2fs_crypto_ctx
*ctx
;
405 struct page
*ciphertext_page
= NULL
;
408 BUG_ON(!PageLocked(plaintext_page
));
410 ctx
= f2fs_get_crypto_ctx(inode
);
412 return (struct page
*)ctx
;
414 /* The encryption operation will require a bounce page. */
415 ciphertext_page
= alloc_bounce_page(ctx
);
416 if (IS_ERR(ciphertext_page
))
419 ctx
->w
.control_page
= plaintext_page
;
420 err
= f2fs_page_crypto(ctx
, inode
, F2FS_ENCRYPT
, plaintext_page
->index
,
421 plaintext_page
, ciphertext_page
);
423 ciphertext_page
= ERR_PTR(err
);
427 SetPagePrivate(ciphertext_page
);
428 set_page_private(ciphertext_page
, (unsigned long)ctx
);
429 lock_page(ciphertext_page
);
430 return ciphertext_page
;
433 f2fs_release_crypto_ctx(ctx
);
434 return ciphertext_page
;
438 * f2fs_decrypt() - Decrypts a page in-place
439 * @ctx: The encryption context.
440 * @page: The page to decrypt. Must be locked.
442 * Decrypts page in-place using the ctx encryption context.
444 * Called from the read completion callback.
446 * Return: Zero on success, non-zero otherwise.
448 int f2fs_decrypt(struct f2fs_crypto_ctx
*ctx
, struct page
*page
)
450 BUG_ON(!PageLocked(page
));
452 return f2fs_page_crypto(ctx
, page
->mapping
->host
,
453 F2FS_DECRYPT
, page
->index
, page
, page
);
457 * Convenience function which takes care of allocating and
458 * deallocating the encryption context
460 int f2fs_decrypt_one(struct inode
*inode
, struct page
*page
)
462 struct f2fs_crypto_ctx
*ctx
= f2fs_get_crypto_ctx(inode
);
467 ret
= f2fs_decrypt(ctx
, page
);
468 f2fs_release_crypto_ctx(ctx
);
472 bool f2fs_valid_contents_enc_mode(uint32_t mode
)
474 return (mode
== F2FS_ENCRYPTION_MODE_AES_256_XTS
);
478 * f2fs_validate_encryption_key_size() - Validate the encryption key size
479 * @mode: The key mode.
480 * @size: The key size to validate.
482 * Return: The validated key size for @mode. Zero if invalid.
484 uint32_t f2fs_validate_encryption_key_size(uint32_t mode
, uint32_t size
)
486 if (size
== f2fs_encryption_key_size(mode
))