Commit | Line | Data |
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57e5055b JK |
1 | /* |
2 | * linux/fs/f2fs/crypto.c | |
3 | * | |
4 | * Copied from linux/fs/ext4/crypto.c | |
5 | * | |
6 | * Copyright (C) 2015, Google, Inc. | |
7 | * Copyright (C) 2015, Motorola Mobility | |
8 | * | |
9 | * This contains encryption functions for f2fs | |
10 | * | |
11 | * Written by Michael Halcrow, 2014. | |
12 | * | |
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() | |
19 | * Jaegeuk Kim, 2015. | |
20 | * | |
21 | * This has not yet undergone a rigorous security audit. | |
22 | * | |
23 | * The usage of AES-XTS should conform to recommendations in NIST | |
24 | * Special Publication 800-38E and IEEE P1619/D16. | |
25 | */ | |
26 | #include <crypto/hash.h> | |
27 | #include <crypto/sha.h> | |
28 | #include <keys/user-type.h> | |
29 | #include <keys/encrypted-type.h> | |
30 | #include <linux/crypto.h> | |
31 | #include <linux/ecryptfs.h> | |
32 | #include <linux/gfp.h> | |
33 | #include <linux/kernel.h> | |
34 | #include <linux/key.h> | |
35 | #include <linux/list.h> | |
36 | #include <linux/mempool.h> | |
37 | #include <linux/module.h> | |
38 | #include <linux/mutex.h> | |
39 | #include <linux/random.h> | |
40 | #include <linux/scatterlist.h> | |
41 | #include <linux/spinlock_types.h> | |
42 | #include <linux/f2fs_fs.h> | |
43 | #include <linux/ratelimit.h> | |
44 | #include <linux/bio.h> | |
45 | ||
46 | #include "f2fs.h" | |
47 | #include "xattr.h" | |
48 | ||
49 | /* Encryption added and removed here! (L: */ | |
50 | ||
51 | static unsigned int num_prealloc_crypto_pages = 32; | |
52 | static unsigned int num_prealloc_crypto_ctxs = 128; | |
53 | ||
54 | module_param(num_prealloc_crypto_pages, uint, 0444); | |
55 | MODULE_PARM_DESC(num_prealloc_crypto_pages, | |
56 | "Number of crypto pages to preallocate"); | |
57 | module_param(num_prealloc_crypto_ctxs, uint, 0444); | |
58 | MODULE_PARM_DESC(num_prealloc_crypto_ctxs, | |
59 | "Number of crypto contexts to preallocate"); | |
60 | ||
61 | static mempool_t *f2fs_bounce_page_pool; | |
62 | ||
63 | static LIST_HEAD(f2fs_free_crypto_ctxs); | |
64 | static DEFINE_SPINLOCK(f2fs_crypto_ctx_lock); | |
65 | ||
cfc4d971 | 66 | static struct workqueue_struct *f2fs_read_workqueue; |
57e5055b JK |
67 | static DEFINE_MUTEX(crypto_init); |
68 | ||
8bacf6de JK |
69 | static struct kmem_cache *f2fs_crypto_ctx_cachep; |
70 | struct kmem_cache *f2fs_crypt_info_cachep; | |
71 | ||
57e5055b JK |
72 | /** |
73 | * f2fs_release_crypto_ctx() - Releases an encryption context | |
74 | * @ctx: The encryption context to release. | |
75 | * | |
76 | * If the encryption context was allocated from the pre-allocated pool, returns | |
77 | * it to that pool. Else, frees it. | |
78 | * | |
79 | * If there's a bounce page in the context, this frees that. | |
80 | */ | |
81 | void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx) | |
82 | { | |
83 | unsigned long flags; | |
84 | ||
ca40b030 | 85 | if (ctx->flags & F2FS_WRITE_PATH_FL && ctx->w.bounce_page) { |
4683ff83 | 86 | mempool_free(ctx->w.bounce_page, f2fs_bounce_page_pool); |
ca40b030 | 87 | ctx->w.bounce_page = NULL; |
57e5055b | 88 | } |
ca40b030 | 89 | ctx->w.control_page = NULL; |
57e5055b | 90 | if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) { |
8bacf6de | 91 | kmem_cache_free(f2fs_crypto_ctx_cachep, ctx); |
57e5055b JK |
92 | } else { |
93 | spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags); | |
94 | list_add(&ctx->free_list, &f2fs_free_crypto_ctxs); | |
95 | spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags); | |
96 | } | |
97 | } | |
98 | ||
57e5055b JK |
99 | /** |
100 | * f2fs_get_crypto_ctx() - Gets an encryption context | |
101 | * @inode: The inode for which we are doing the crypto | |
102 | * | |
103 | * Allocates and initializes an encryption context. | |
104 | * | |
105 | * Return: An allocated and initialized encryption context on success; error | |
106 | * value or NULL otherwise. | |
107 | */ | |
108 | struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode) | |
109 | { | |
110 | struct f2fs_crypto_ctx *ctx = NULL; | |
57e5055b JK |
111 | unsigned long flags; |
112 | struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; | |
113 | ||
edf3fb8e | 114 | if (ci == NULL) |
7e8e754a | 115 | return ERR_PTR(-ENOKEY); |
edf3fb8e | 116 | |
57e5055b JK |
117 | /* |
118 | * We first try getting the ctx from a free list because in | |
119 | * the common case the ctx will have an allocated and | |
120 | * initialized crypto tfm, so it's probably a worthwhile | |
121 | * optimization. For the bounce page, we first try getting it | |
122 | * from the kernel allocator because that's just about as fast | |
123 | * as getting it from a list and because a cache of free pages | |
124 | * should generally be a "last resort" option for a filesystem | |
125 | * to be able to do its job. | |
126 | */ | |
127 | spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags); | |
128 | ctx = list_first_entry_or_null(&f2fs_free_crypto_ctxs, | |
129 | struct f2fs_crypto_ctx, free_list); | |
130 | if (ctx) | |
131 | list_del(&ctx->free_list); | |
132 | spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags); | |
133 | if (!ctx) { | |
8bacf6de | 134 | ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS); |
26bf3dc7 JK |
135 | if (!ctx) |
136 | return ERR_PTR(-ENOMEM); | |
57e5055b JK |
137 | ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL; |
138 | } else { | |
139 | ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL; | |
140 | } | |
ca40b030 | 141 | ctx->flags &= ~F2FS_WRITE_PATH_FL; |
57e5055b JK |
142 | return ctx; |
143 | } | |
144 | ||
145 | /* | |
146 | * Call f2fs_decrypt on every single page, reusing the encryption | |
147 | * context. | |
148 | */ | |
149 | static void completion_pages(struct work_struct *work) | |
150 | { | |
151 | struct f2fs_crypto_ctx *ctx = | |
ca40b030 JK |
152 | container_of(work, struct f2fs_crypto_ctx, r.work); |
153 | struct bio *bio = ctx->r.bio; | |
57e5055b JK |
154 | struct bio_vec *bv; |
155 | int i; | |
156 | ||
157 | bio_for_each_segment_all(bv, bio, i) { | |
158 | struct page *page = bv->bv_page; | |
159 | int ret = f2fs_decrypt(ctx, page); | |
160 | ||
161 | if (ret) { | |
162 | WARN_ON_ONCE(1); | |
163 | SetPageError(page); | |
164 | } else | |
165 | SetPageUptodate(page); | |
166 | unlock_page(page); | |
167 | } | |
168 | f2fs_release_crypto_ctx(ctx); | |
169 | bio_put(bio); | |
170 | } | |
171 | ||
172 | void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *ctx, struct bio *bio) | |
173 | { | |
ca40b030 JK |
174 | INIT_WORK(&ctx->r.work, completion_pages); |
175 | ctx->r.bio = bio; | |
176 | queue_work(f2fs_read_workqueue, &ctx->r.work); | |
57e5055b JK |
177 | } |
178 | ||
cfc4d971 | 179 | static void f2fs_crypto_destroy(void) |
57e5055b JK |
180 | { |
181 | struct f2fs_crypto_ctx *pos, *n; | |
182 | ||
26bf3dc7 | 183 | list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list) |
8bacf6de | 184 | kmem_cache_free(f2fs_crypto_ctx_cachep, pos); |
57e5055b JK |
185 | INIT_LIST_HEAD(&f2fs_free_crypto_ctxs); |
186 | if (f2fs_bounce_page_pool) | |
187 | mempool_destroy(f2fs_bounce_page_pool); | |
188 | f2fs_bounce_page_pool = NULL; | |
57e5055b JK |
189 | } |
190 | ||
191 | /** | |
cfc4d971 | 192 | * f2fs_crypto_initialize() - Set up for f2fs encryption. |
57e5055b JK |
193 | * |
194 | * We only call this when we start accessing encrypted files, since it | |
195 | * results in memory getting allocated that wouldn't otherwise be used. | |
196 | * | |
197 | * Return: Zero on success, non-zero otherwise. | |
198 | */ | |
cfc4d971 | 199 | int f2fs_crypto_initialize(void) |
57e5055b | 200 | { |
8bacf6de | 201 | int i, res = -ENOMEM; |
57e5055b | 202 | |
cfc4d971 JK |
203 | if (f2fs_bounce_page_pool) |
204 | return 0; | |
205 | ||
57e5055b | 206 | mutex_lock(&crypto_init); |
cfc4d971 | 207 | if (f2fs_bounce_page_pool) |
57e5055b JK |
208 | goto already_initialized; |
209 | ||
57e5055b JK |
210 | for (i = 0; i < num_prealloc_crypto_ctxs; i++) { |
211 | struct f2fs_crypto_ctx *ctx; | |
212 | ||
8bacf6de | 213 | ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_KERNEL); |
cfc4d971 | 214 | if (!ctx) |
57e5055b | 215 | goto fail; |
57e5055b JK |
216 | list_add(&ctx->free_list, &f2fs_free_crypto_ctxs); |
217 | } | |
218 | ||
cfc4d971 | 219 | /* must be allocated at the last step to avoid race condition above */ |
57e5055b JK |
220 | f2fs_bounce_page_pool = |
221 | mempool_create_page_pool(num_prealloc_crypto_pages, 0); | |
cfc4d971 | 222 | if (!f2fs_bounce_page_pool) |
57e5055b | 223 | goto fail; |
cfc4d971 | 224 | |
57e5055b JK |
225 | already_initialized: |
226 | mutex_unlock(&crypto_init); | |
227 | return 0; | |
228 | fail: | |
cfc4d971 | 229 | f2fs_crypto_destroy(); |
57e5055b JK |
230 | mutex_unlock(&crypto_init); |
231 | return res; | |
232 | } | |
233 | ||
cfc4d971 JK |
234 | /** |
235 | * f2fs_exit_crypto() - Shutdown the f2fs encryption system | |
236 | */ | |
237 | void f2fs_exit_crypto(void) | |
238 | { | |
239 | f2fs_crypto_destroy(); | |
240 | ||
241 | if (f2fs_read_workqueue) | |
242 | destroy_workqueue(f2fs_read_workqueue); | |
243 | if (f2fs_crypto_ctx_cachep) | |
244 | kmem_cache_destroy(f2fs_crypto_ctx_cachep); | |
245 | if (f2fs_crypt_info_cachep) | |
246 | kmem_cache_destroy(f2fs_crypt_info_cachep); | |
247 | } | |
248 | ||
249 | int __init f2fs_init_crypto(void) | |
250 | { | |
251 | int res = -ENOMEM; | |
252 | ||
253 | f2fs_read_workqueue = alloc_workqueue("f2fs_crypto", WQ_HIGHPRI, 0); | |
254 | if (!f2fs_read_workqueue) | |
255 | goto fail; | |
256 | ||
257 | f2fs_crypto_ctx_cachep = KMEM_CACHE(f2fs_crypto_ctx, | |
258 | SLAB_RECLAIM_ACCOUNT); | |
259 | if (!f2fs_crypto_ctx_cachep) | |
260 | goto fail; | |
261 | ||
262 | f2fs_crypt_info_cachep = KMEM_CACHE(f2fs_crypt_info, | |
263 | SLAB_RECLAIM_ACCOUNT); | |
264 | if (!f2fs_crypt_info_cachep) | |
265 | goto fail; | |
266 | ||
267 | return 0; | |
268 | fail: | |
269 | f2fs_exit_crypto(); | |
270 | return res; | |
271 | } | |
272 | ||
57e5055b JK |
273 | void f2fs_restore_and_release_control_page(struct page **page) |
274 | { | |
275 | struct f2fs_crypto_ctx *ctx; | |
276 | struct page *bounce_page; | |
277 | ||
278 | /* The bounce data pages are unmapped. */ | |
279 | if ((*page)->mapping) | |
280 | return; | |
281 | ||
282 | /* The bounce data page is unmapped. */ | |
283 | bounce_page = *page; | |
284 | ctx = (struct f2fs_crypto_ctx *)page_private(bounce_page); | |
285 | ||
286 | /* restore control page */ | |
ca40b030 | 287 | *page = ctx->w.control_page; |
57e5055b JK |
288 | |
289 | f2fs_restore_control_page(bounce_page); | |
290 | } | |
291 | ||
292 | void f2fs_restore_control_page(struct page *data_page) | |
293 | { | |
294 | struct f2fs_crypto_ctx *ctx = | |
295 | (struct f2fs_crypto_ctx *)page_private(data_page); | |
296 | ||
297 | set_page_private(data_page, (unsigned long)NULL); | |
298 | ClearPagePrivate(data_page); | |
299 | unlock_page(data_page); | |
300 | f2fs_release_crypto_ctx(ctx); | |
301 | } | |
302 | ||
303 | /** | |
304 | * f2fs_crypt_complete() - The completion callback for page encryption | |
305 | * @req: The asynchronous encryption request context | |
306 | * @res: The result of the encryption operation | |
307 | */ | |
308 | static void f2fs_crypt_complete(struct crypto_async_request *req, int res) | |
309 | { | |
310 | struct f2fs_completion_result *ecr = req->data; | |
311 | ||
312 | if (res == -EINPROGRESS) | |
313 | return; | |
314 | ecr->res = res; | |
315 | complete(&ecr->completion); | |
316 | } | |
317 | ||
318 | typedef enum { | |
319 | F2FS_DECRYPT = 0, | |
320 | F2FS_ENCRYPT, | |
321 | } f2fs_direction_t; | |
322 | ||
323 | static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx, | |
324 | struct inode *inode, | |
325 | f2fs_direction_t rw, | |
326 | pgoff_t index, | |
327 | struct page *src_page, | |
328 | struct page *dest_page) | |
329 | { | |
330 | u8 xts_tweak[F2FS_XTS_TWEAK_SIZE]; | |
331 | struct ablkcipher_request *req = NULL; | |
332 | DECLARE_F2FS_COMPLETION_RESULT(ecr); | |
333 | struct scatterlist dst, src; | |
26bf3dc7 JK |
334 | struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info; |
335 | struct crypto_ablkcipher *tfm = ci->ci_ctfm; | |
57e5055b JK |
336 | int res = 0; |
337 | ||
26bf3dc7 | 338 | req = ablkcipher_request_alloc(tfm, GFP_NOFS); |
57e5055b JK |
339 | if (!req) { |
340 | printk_ratelimited(KERN_ERR | |
341 | "%s: crypto_request_alloc() failed\n", | |
342 | __func__); | |
343 | return -ENOMEM; | |
344 | } | |
345 | ablkcipher_request_set_callback( | |
346 | req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, | |
347 | f2fs_crypt_complete, &ecr); | |
348 | ||
349 | BUILD_BUG_ON(F2FS_XTS_TWEAK_SIZE < sizeof(index)); | |
350 | memcpy(xts_tweak, &index, sizeof(index)); | |
351 | memset(&xts_tweak[sizeof(index)], 0, | |
352 | F2FS_XTS_TWEAK_SIZE - sizeof(index)); | |
353 | ||
354 | sg_init_table(&dst, 1); | |
355 | sg_set_page(&dst, dest_page, PAGE_CACHE_SIZE, 0); | |
356 | sg_init_table(&src, 1); | |
357 | sg_set_page(&src, src_page, PAGE_CACHE_SIZE, 0); | |
358 | ablkcipher_request_set_crypt(req, &src, &dst, PAGE_CACHE_SIZE, | |
359 | xts_tweak); | |
360 | if (rw == F2FS_DECRYPT) | |
361 | res = crypto_ablkcipher_decrypt(req); | |
362 | else | |
363 | res = crypto_ablkcipher_encrypt(req); | |
364 | if (res == -EINPROGRESS || res == -EBUSY) { | |
365 | BUG_ON(req->base.data != &ecr); | |
366 | wait_for_completion(&ecr.completion); | |
367 | res = ecr.res; | |
368 | } | |
369 | ablkcipher_request_free(req); | |
370 | if (res) { | |
371 | printk_ratelimited(KERN_ERR | |
372 | "%s: crypto_ablkcipher_encrypt() returned %d\n", | |
373 | __func__, res); | |
374 | return res; | |
375 | } | |
376 | return 0; | |
377 | } | |
378 | ||
43f54cd5 JK |
379 | static struct page *alloc_bounce_page(struct f2fs_crypto_ctx *ctx) |
380 | { | |
381 | ctx->w.bounce_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOWAIT); | |
382 | if (ctx->w.bounce_page == NULL) | |
383 | return ERR_PTR(-ENOMEM); | |
384 | ctx->flags |= F2FS_WRITE_PATH_FL; | |
385 | return ctx->w.bounce_page; | |
386 | } | |
387 | ||
57e5055b JK |
388 | /** |
389 | * f2fs_encrypt() - Encrypts a page | |
390 | * @inode: The inode for which the encryption should take place | |
391 | * @plaintext_page: The page to encrypt. Must be locked. | |
392 | * | |
393 | * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx | |
394 | * encryption context. | |
395 | * | |
396 | * Called on the page write path. The caller must call | |
397 | * f2fs_restore_control_page() on the returned ciphertext page to | |
398 | * release the bounce buffer and the encryption context. | |
399 | * | |
400 | * Return: An allocated page with the encrypted content on success. Else, an | |
401 | * error value or NULL. | |
402 | */ | |
403 | struct page *f2fs_encrypt(struct inode *inode, | |
404 | struct page *plaintext_page) | |
405 | { | |
406 | struct f2fs_crypto_ctx *ctx; | |
407 | struct page *ciphertext_page = NULL; | |
408 | int err; | |
409 | ||
410 | BUG_ON(!PageLocked(plaintext_page)); | |
411 | ||
412 | ctx = f2fs_get_crypto_ctx(inode); | |
413 | if (IS_ERR(ctx)) | |
414 | return (struct page *)ctx; | |
415 | ||
416 | /* The encryption operation will require a bounce page. */ | |
43f54cd5 JK |
417 | ciphertext_page = alloc_bounce_page(ctx); |
418 | if (IS_ERR(ciphertext_page)) | |
4683ff83 | 419 | goto err_out; |
4683ff83 | 420 | |
ca40b030 | 421 | ctx->w.control_page = plaintext_page; |
57e5055b JK |
422 | err = f2fs_page_crypto(ctx, inode, F2FS_ENCRYPT, plaintext_page->index, |
423 | plaintext_page, ciphertext_page); | |
43f54cd5 JK |
424 | if (err) { |
425 | ciphertext_page = ERR_PTR(err); | |
4683ff83 | 426 | goto err_out; |
43f54cd5 | 427 | } |
4683ff83 | 428 | |
57e5055b JK |
429 | SetPagePrivate(ciphertext_page); |
430 | set_page_private(ciphertext_page, (unsigned long)ctx); | |
431 | lock_page(ciphertext_page); | |
432 | return ciphertext_page; | |
4683ff83 JK |
433 | |
434 | err_out: | |
435 | f2fs_release_crypto_ctx(ctx); | |
43f54cd5 | 436 | return ciphertext_page; |
57e5055b JK |
437 | } |
438 | ||
439 | /** | |
440 | * f2fs_decrypt() - Decrypts a page in-place | |
441 | * @ctx: The encryption context. | |
442 | * @page: The page to decrypt. Must be locked. | |
443 | * | |
444 | * Decrypts page in-place using the ctx encryption context. | |
445 | * | |
446 | * Called from the read completion callback. | |
447 | * | |
448 | * Return: Zero on success, non-zero otherwise. | |
449 | */ | |
450 | int f2fs_decrypt(struct f2fs_crypto_ctx *ctx, struct page *page) | |
451 | { | |
452 | BUG_ON(!PageLocked(page)); | |
453 | ||
454 | return f2fs_page_crypto(ctx, page->mapping->host, | |
455 | F2FS_DECRYPT, page->index, page, page); | |
456 | } | |
457 | ||
458 | /* | |
459 | * Convenience function which takes care of allocating and | |
460 | * deallocating the encryption context | |
461 | */ | |
462 | int f2fs_decrypt_one(struct inode *inode, struct page *page) | |
463 | { | |
464 | struct f2fs_crypto_ctx *ctx = f2fs_get_crypto_ctx(inode); | |
465 | int ret; | |
466 | ||
7e8e754a JK |
467 | if (IS_ERR(ctx)) |
468 | return PTR_ERR(ctx); | |
57e5055b JK |
469 | ret = f2fs_decrypt(ctx, page); |
470 | f2fs_release_crypto_ctx(ctx); | |
471 | return ret; | |
472 | } | |
473 | ||
474 | bool f2fs_valid_contents_enc_mode(uint32_t mode) | |
475 | { | |
476 | return (mode == F2FS_ENCRYPTION_MODE_AES_256_XTS); | |
477 | } | |
478 | ||
479 | /** | |
480 | * f2fs_validate_encryption_key_size() - Validate the encryption key size | |
481 | * @mode: The key mode. | |
482 | * @size: The key size to validate. | |
483 | * | |
484 | * Return: The validated key size for @mode. Zero if invalid. | |
485 | */ | |
486 | uint32_t f2fs_validate_encryption_key_size(uint32_t mode, uint32_t size) | |
487 | { | |
488 | if (size == f2fs_encryption_key_size(mode)) | |
489 | return size; | |
490 | return 0; | |
491 | } |