crypto: testmgr - move to generic async completion
[linux-block.git] / fs / crypto / crypto.c
CommitLineData
0b81d077
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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
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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>
0b81d077 27#include <linux/dcache.h>
03a8bb0e 28#include <linux/namei.h>
b7e7cf7a 29#include <crypto/aes.h>
cc4e0df0 30#include "fscrypt_private.h"
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31
32static unsigned int num_prealloc_crypto_pages = 32;
33static unsigned int num_prealloc_crypto_ctxs = 128;
34
35module_param(num_prealloc_crypto_pages, uint, 0444);
36MODULE_PARM_DESC(num_prealloc_crypto_pages,
37 "Number of crypto pages to preallocate");
38module_param(num_prealloc_crypto_ctxs, uint, 0444);
39MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
40 "Number of crypto contexts to preallocate");
41
42static mempool_t *fscrypt_bounce_page_pool = NULL;
43
44static LIST_HEAD(fscrypt_free_ctxs);
45static DEFINE_SPINLOCK(fscrypt_ctx_lock);
46
58ae7468 47struct workqueue_struct *fscrypt_read_workqueue;
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48static DEFINE_MUTEX(fscrypt_init_mutex);
49
50static struct kmem_cache *fscrypt_ctx_cachep;
51struct kmem_cache *fscrypt_info_cachep;
52
53/**
54 * fscrypt_release_ctx() - Releases an encryption context
55 * @ctx: The encryption context to release.
56 *
57 * If the encryption context was allocated from the pre-allocated pool, returns
58 * it to that pool. Else, frees it.
59 *
60 * If there's a bounce page in the context, this frees that.
61 */
62void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
63{
64 unsigned long flags;
65
6a34e4d2 66 if (ctx->flags & FS_CTX_HAS_BOUNCE_BUFFER_FL && ctx->w.bounce_page) {
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67 mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
68 ctx->w.bounce_page = NULL;
69 }
70 ctx->w.control_page = NULL;
71 if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
72 kmem_cache_free(fscrypt_ctx_cachep, ctx);
73 } else {
74 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
75 list_add(&ctx->free_list, &fscrypt_free_ctxs);
76 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
77 }
78}
79EXPORT_SYMBOL(fscrypt_release_ctx);
80
81/**
82 * fscrypt_get_ctx() - Gets an encryption context
83 * @inode: The inode for which we are doing the crypto
b32e4482 84 * @gfp_flags: The gfp flag for memory allocation
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85 *
86 * Allocates and initializes an encryption context.
87 *
88 * Return: An allocated and initialized encryption context on success; error
89 * value or NULL otherwise.
90 */
0b93e1b9 91struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode, gfp_t gfp_flags)
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92{
93 struct fscrypt_ctx *ctx = NULL;
94 struct fscrypt_info *ci = inode->i_crypt_info;
95 unsigned long flags;
96
97 if (ci == NULL)
98 return ERR_PTR(-ENOKEY);
99
100 /*
101 * We first try getting the ctx from a free list because in
102 * the common case the ctx will have an allocated and
103 * initialized crypto tfm, so it's probably a worthwhile
104 * optimization. For the bounce page, we first try getting it
105 * from the kernel allocator because that's just about as fast
106 * as getting it from a list and because a cache of free pages
107 * should generally be a "last resort" option for a filesystem
108 * to be able to do its job.
109 */
110 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
111 ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
112 struct fscrypt_ctx, free_list);
113 if (ctx)
114 list_del(&ctx->free_list);
115 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
116 if (!ctx) {
b32e4482 117 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
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118 if (!ctx)
119 return ERR_PTR(-ENOMEM);
120 ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
121 } else {
122 ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
123 }
6a34e4d2 124 ctx->flags &= ~FS_CTX_HAS_BOUNCE_BUFFER_FL;
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125 return ctx;
126}
127EXPORT_SYMBOL(fscrypt_get_ctx);
128
129/**
53fd7550
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130 * page_crypt_complete() - completion callback for page crypto
131 * @req: The asynchronous cipher request context
132 * @res: The result of the cipher operation
0b81d077 133 */
53fd7550 134static void page_crypt_complete(struct crypto_async_request *req, int res)
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135{
136 struct fscrypt_completion_result *ecr = req->data;
137
138 if (res == -EINPROGRESS)
139 return;
140 ecr->res = res;
141 complete(&ecr->completion);
142}
143
58ae7468
RW
144int fscrypt_do_page_crypto(const struct inode *inode, fscrypt_direction_t rw,
145 u64 lblk_num, struct page *src_page,
146 struct page *dest_page, unsigned int len,
147 unsigned int offs, gfp_t gfp_flags)
0b81d077 148{
fb445437
EB
149 struct {
150 __le64 index;
b7e7cf7a
DW
151 u8 padding[FS_IV_SIZE - sizeof(__le64)];
152 } iv;
d407574e 153 struct skcipher_request *req = NULL;
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154 DECLARE_FS_COMPLETION_RESULT(ecr);
155 struct scatterlist dst, src;
156 struct fscrypt_info *ci = inode->i_crypt_info;
d407574e 157 struct crypto_skcipher *tfm = ci->ci_ctfm;
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158 int res = 0;
159
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160 BUG_ON(len == 0);
161
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162 BUILD_BUG_ON(sizeof(iv) != FS_IV_SIZE);
163 BUILD_BUG_ON(AES_BLOCK_SIZE != FS_IV_SIZE);
164 iv.index = cpu_to_le64(lblk_num);
165 memset(iv.padding, 0, sizeof(iv.padding));
166
167 if (ci->ci_essiv_tfm != NULL) {
168 crypto_cipher_encrypt_one(ci->ci_essiv_tfm, (u8 *)&iv,
169 (u8 *)&iv);
170 }
171
b32e4482 172 req = skcipher_request_alloc(tfm, gfp_flags);
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173 if (!req) {
174 printk_ratelimited(KERN_ERR
175 "%s: crypto_request_alloc() failed\n",
176 __func__);
177 return -ENOMEM;
178 }
179
d407574e 180 skcipher_request_set_callback(
0b81d077 181 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
53fd7550 182 page_crypt_complete, &ecr);
0b81d077 183
0b81d077 184 sg_init_table(&dst, 1);
1400451f 185 sg_set_page(&dst, dest_page, len, offs);
0b81d077 186 sg_init_table(&src, 1);
1400451f 187 sg_set_page(&src, src_page, len, offs);
b7e7cf7a 188 skcipher_request_set_crypt(req, &src, &dst, len, &iv);
0b81d077 189 if (rw == FS_DECRYPT)
d407574e 190 res = crypto_skcipher_decrypt(req);
0b81d077 191 else
d407574e 192 res = crypto_skcipher_encrypt(req);
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193 if (res == -EINPROGRESS || res == -EBUSY) {
194 BUG_ON(req->base.data != &ecr);
195 wait_for_completion(&ecr.completion);
196 res = ecr.res;
197 }
d407574e 198 skcipher_request_free(req);
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199 if (res) {
200 printk_ratelimited(KERN_ERR
d407574e 201 "%s: crypto_skcipher_encrypt() returned %d\n",
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202 __func__, res);
203 return res;
204 }
205 return 0;
206}
207
58ae7468
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208struct page *fscrypt_alloc_bounce_page(struct fscrypt_ctx *ctx,
209 gfp_t gfp_flags)
0b81d077 210{
b32e4482 211 ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
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212 if (ctx->w.bounce_page == NULL)
213 return ERR_PTR(-ENOMEM);
6a34e4d2 214 ctx->flags |= FS_CTX_HAS_BOUNCE_BUFFER_FL;
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215 return ctx->w.bounce_page;
216}
217
218/**
219 * fscypt_encrypt_page() - Encrypts a page
1400451f
DG
220 * @inode: The inode for which the encryption should take place
221 * @page: The page to encrypt. Must be locked for bounce-page
222 * encryption.
223 * @len: Length of data to encrypt in @page and encrypted
224 * data in returned page.
225 * @offs: Offset of data within @page and returned
226 * page holding encrypted data.
227 * @lblk_num: Logical block number. This must be unique for multiple
228 * calls with same inode, except when overwriting
229 * previously written data.
230 * @gfp_flags: The gfp flag for memory allocation
0b81d077 231 *
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232 * Encrypts @page using the ctx encryption context. Performs encryption
233 * either in-place or into a newly allocated bounce page.
234 * Called on the page write path.
0b81d077 235 *
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236 * Bounce page allocation is the default.
237 * In this case, the contents of @page are encrypted and stored in an
238 * allocated bounce page. @page has to be locked and the caller must call
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239 * fscrypt_restore_control_page() on the returned ciphertext page to
240 * release the bounce buffer and the encryption context.
241 *
bd7b8290 242 * In-place encryption is used by setting the FS_CFLG_OWN_PAGES flag in
1400451f
DG
243 * fscrypt_operations. Here, the input-page is returned with its content
244 * encrypted.
245 *
246 * Return: A page with the encrypted content on success. Else, an
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247 * error value or NULL.
248 */
0b93e1b9 249struct page *fscrypt_encrypt_page(const struct inode *inode,
1400451f
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250 struct page *page,
251 unsigned int len,
252 unsigned int offs,
253 u64 lblk_num, gfp_t gfp_flags)
7821d4dd 254
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255{
256 struct fscrypt_ctx *ctx;
1400451f 257 struct page *ciphertext_page = page;
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258 int err;
259
1400451f 260 BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);
0b81d077 261
bd7b8290 262 if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
9e532772 263 /* with inplace-encryption we just encrypt the page */
58ae7468
RW
264 err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num, page,
265 ciphertext_page, len, offs,
266 gfp_flags);
9e532772
DG
267 if (err)
268 return ERR_PTR(err);
269
270 return ciphertext_page;
271 }
272
bd7b8290
DG
273 BUG_ON(!PageLocked(page));
274
b32e4482 275 ctx = fscrypt_get_ctx(inode, gfp_flags);
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276 if (IS_ERR(ctx))
277 return (struct page *)ctx;
278
9e532772 279 /* The encryption operation will require a bounce page. */
58ae7468 280 ciphertext_page = fscrypt_alloc_bounce_page(ctx, gfp_flags);
9e532772
DG
281 if (IS_ERR(ciphertext_page))
282 goto errout;
0b81d077 283
1400451f 284 ctx->w.control_page = page;
58ae7468
RW
285 err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk_num,
286 page, ciphertext_page, len, offs,
287 gfp_flags);
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JK
288 if (err) {
289 ciphertext_page = ERR_PTR(err);
290 goto errout;
291 }
9e532772
DG
292 SetPagePrivate(ciphertext_page);
293 set_page_private(ciphertext_page, (unsigned long)ctx);
294 lock_page(ciphertext_page);
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295 return ciphertext_page;
296
297errout:
298 fscrypt_release_ctx(ctx);
299 return ciphertext_page;
300}
301EXPORT_SYMBOL(fscrypt_encrypt_page);
302
303/**
7821d4dd 304 * fscrypt_decrypt_page() - Decrypts a page in-place
1400451f
DG
305 * @inode: The corresponding inode for the page to decrypt.
306 * @page: The page to decrypt. Must be locked in case
bd7b8290 307 * it is a writeback page (FS_CFLG_OWN_PAGES unset).
1400451f
DG
308 * @len: Number of bytes in @page to be decrypted.
309 * @offs: Start of data in @page.
310 * @lblk_num: Logical block number.
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311 *
312 * Decrypts page in-place using the ctx encryption context.
313 *
314 * Called from the read completion callback.
315 *
316 * Return: Zero on success, non-zero otherwise.
317 */
0b93e1b9 318int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
1400451f 319 unsigned int len, unsigned int offs, u64 lblk_num)
0b81d077 320{
bd7b8290
DG
321 if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
322 BUG_ON(!PageLocked(page));
323
58ae7468
RW
324 return fscrypt_do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page,
325 len, offs, GFP_NOFS);
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326}
327EXPORT_SYMBOL(fscrypt_decrypt_page);
328
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329/*
330 * Validate dentries for encrypted directories to make sure we aren't
331 * potentially caching stale data after a key has been added or
332 * removed.
333 */
334static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
335{
d7d75352 336 struct dentry *dir;
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337 int dir_has_key, cached_with_key;
338
03a8bb0e
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339 if (flags & LOOKUP_RCU)
340 return -ECHILD;
341
d7d75352
JK
342 dir = dget_parent(dentry);
343 if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
344 dput(dir);
0b81d077 345 return 0;
d7d75352 346 }
0b81d077 347
0b81d077
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348 /* this should eventually be an flag in d_flags */
349 spin_lock(&dentry->d_lock);
350 cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
351 spin_unlock(&dentry->d_lock);
1b53cf98 352 dir_has_key = (d_inode(dir)->i_crypt_info != NULL);
d7d75352 353 dput(dir);
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354
355 /*
356 * If the dentry was cached without the key, and it is a
357 * negative dentry, it might be a valid name. We can't check
358 * if the key has since been made available due to locking
359 * reasons, so we fail the validation so ext4_lookup() can do
360 * this check.
361 *
362 * We also fail the validation if the dentry was created with
363 * the key present, but we no longer have the key, or vice versa.
364 */
365 if ((!cached_with_key && d_is_negative(dentry)) ||
366 (!cached_with_key && dir_has_key) ||
367 (cached_with_key && !dir_has_key))
368 return 0;
369 return 1;
370}
371
372const struct dentry_operations fscrypt_d_ops = {
373 .d_revalidate = fscrypt_d_revalidate,
374};
375EXPORT_SYMBOL(fscrypt_d_ops);
376
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377void fscrypt_restore_control_page(struct page *page)
378{
379 struct fscrypt_ctx *ctx;
380
381 ctx = (struct fscrypt_ctx *)page_private(page);
382 set_page_private(page, (unsigned long)NULL);
383 ClearPagePrivate(page);
384 unlock_page(page);
385 fscrypt_release_ctx(ctx);
386}
387EXPORT_SYMBOL(fscrypt_restore_control_page);
388
389static void fscrypt_destroy(void)
390{
391 struct fscrypt_ctx *pos, *n;
392
393 list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
394 kmem_cache_free(fscrypt_ctx_cachep, pos);
395 INIT_LIST_HEAD(&fscrypt_free_ctxs);
396 mempool_destroy(fscrypt_bounce_page_pool);
397 fscrypt_bounce_page_pool = NULL;
398}
399
400/**
401 * fscrypt_initialize() - allocate major buffers for fs encryption.
f32d7ac2 402 * @cop_flags: fscrypt operations flags
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403 *
404 * We only call this when we start accessing encrypted files, since it
405 * results in memory getting allocated that wouldn't otherwise be used.
406 *
407 * Return: Zero on success, non-zero otherwise.
408 */
f32d7ac2 409int fscrypt_initialize(unsigned int cop_flags)
0b81d077
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410{
411 int i, res = -ENOMEM;
412
f32d7ac2
DG
413 /*
414 * No need to allocate a bounce page pool if there already is one or
415 * this FS won't use it.
416 */
417 if (cop_flags & FS_CFLG_OWN_PAGES || fscrypt_bounce_page_pool)
0b81d077
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418 return 0;
419
420 mutex_lock(&fscrypt_init_mutex);
421 if (fscrypt_bounce_page_pool)
422 goto already_initialized;
423
424 for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
425 struct fscrypt_ctx *ctx;
426
427 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
428 if (!ctx)
429 goto fail;
430 list_add(&ctx->free_list, &fscrypt_free_ctxs);
431 }
432
433 fscrypt_bounce_page_pool =
434 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
435 if (!fscrypt_bounce_page_pool)
436 goto fail;
437
438already_initialized:
439 mutex_unlock(&fscrypt_init_mutex);
440 return 0;
441fail:
442 fscrypt_destroy();
443 mutex_unlock(&fscrypt_init_mutex);
444 return res;
445}
0b81d077
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446
447/**
448 * fscrypt_init() - Set up for fs encryption.
449 */
450static int __init fscrypt_init(void)
451{
452 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
453 WQ_HIGHPRI, 0);
454 if (!fscrypt_read_workqueue)
455 goto fail;
456
457 fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
458 if (!fscrypt_ctx_cachep)
459 goto fail_free_queue;
460
461 fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
462 if (!fscrypt_info_cachep)
463 goto fail_free_ctx;
464
465 return 0;
466
467fail_free_ctx:
468 kmem_cache_destroy(fscrypt_ctx_cachep);
469fail_free_queue:
470 destroy_workqueue(fscrypt_read_workqueue);
471fail:
472 return -ENOMEM;
473}
474module_init(fscrypt_init)
475
476/**
477 * fscrypt_exit() - Shutdown the fs encryption system
478 */
479static void __exit fscrypt_exit(void)
480{
481 fscrypt_destroy();
482
483 if (fscrypt_read_workqueue)
484 destroy_workqueue(fscrypt_read_workqueue);
485 kmem_cache_destroy(fscrypt_ctx_cachep);
486 kmem_cache_destroy(fscrypt_info_cachep);
b7e7cf7a
DW
487
488 fscrypt_essiv_cleanup();
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JK
489}
490module_exit(fscrypt_exit);
491
492MODULE_LICENSE("GPL");