]>
Commit | Line | Data |
---|---|---|
0b81d077 JK |
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 | ||
0b81d077 JK |
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> | |
03a8bb0e | 29 | #include <linux/namei.h> |
cc4e0df0 | 30 | #include "fscrypt_private.h" |
0b81d077 JK |
31 | |
32 | static unsigned int num_prealloc_crypto_pages = 32; | |
33 | static unsigned int num_prealloc_crypto_ctxs = 128; | |
34 | ||
35 | module_param(num_prealloc_crypto_pages, uint, 0444); | |
36 | MODULE_PARM_DESC(num_prealloc_crypto_pages, | |
37 | "Number of crypto pages to preallocate"); | |
38 | module_param(num_prealloc_crypto_ctxs, uint, 0444); | |
39 | MODULE_PARM_DESC(num_prealloc_crypto_ctxs, | |
40 | "Number of crypto contexts to preallocate"); | |
41 | ||
42 | static mempool_t *fscrypt_bounce_page_pool = NULL; | |
43 | ||
44 | static LIST_HEAD(fscrypt_free_ctxs); | |
45 | static DEFINE_SPINLOCK(fscrypt_ctx_lock); | |
46 | ||
47 | static struct workqueue_struct *fscrypt_read_workqueue; | |
48 | static DEFINE_MUTEX(fscrypt_init_mutex); | |
49 | ||
50 | static struct kmem_cache *fscrypt_ctx_cachep; | |
51 | struct 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 | */ | |
62 | void 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) { |
0b81d077 JK |
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 | } | |
79 | EXPORT_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 |
0b81d077 JK |
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 | 91 | struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode, gfp_t gfp_flags) |
0b81d077 JK |
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); |
0b81d077 JK |
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; |
0b81d077 JK |
125 | return ctx; |
126 | } | |
127 | EXPORT_SYMBOL(fscrypt_get_ctx); | |
128 | ||
129 | /** | |
53fd7550 EB |
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 | 134 | static void page_crypt_complete(struct crypto_async_request *req, int res) |
0b81d077 JK |
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 | ||
144 | typedef enum { | |
145 | FS_DECRYPT = 0, | |
146 | FS_ENCRYPT, | |
147 | } fscrypt_direction_t; | |
148 | ||
0b93e1b9 | 149 | static int do_page_crypto(const struct inode *inode, |
1400451f | 150 | fscrypt_direction_t rw, u64 lblk_num, |
b32e4482 | 151 | struct page *src_page, struct page *dest_page, |
1400451f | 152 | unsigned int len, unsigned int offs, |
b32e4482 | 153 | gfp_t gfp_flags) |
0b81d077 | 154 | { |
fb445437 EB |
155 | struct { |
156 | __le64 index; | |
157 | u8 padding[FS_XTS_TWEAK_SIZE - sizeof(__le64)]; | |
158 | } xts_tweak; | |
d407574e | 159 | struct skcipher_request *req = NULL; |
0b81d077 JK |
160 | DECLARE_FS_COMPLETION_RESULT(ecr); |
161 | struct scatterlist dst, src; | |
162 | struct fscrypt_info *ci = inode->i_crypt_info; | |
d407574e | 163 | struct crypto_skcipher *tfm = ci->ci_ctfm; |
0b81d077 JK |
164 | int res = 0; |
165 | ||
1400451f DG |
166 | BUG_ON(len == 0); |
167 | ||
b32e4482 | 168 | req = skcipher_request_alloc(tfm, gfp_flags); |
0b81d077 JK |
169 | if (!req) { |
170 | printk_ratelimited(KERN_ERR | |
171 | "%s: crypto_request_alloc() failed\n", | |
172 | __func__); | |
173 | return -ENOMEM; | |
174 | } | |
175 | ||
d407574e | 176 | skcipher_request_set_callback( |
0b81d077 | 177 | req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, |
53fd7550 | 178 | page_crypt_complete, &ecr); |
0b81d077 | 179 | |
fb445437 | 180 | BUILD_BUG_ON(sizeof(xts_tweak) != FS_XTS_TWEAK_SIZE); |
1400451f | 181 | xts_tweak.index = cpu_to_le64(lblk_num); |
fb445437 | 182 | memset(xts_tweak.padding, 0, sizeof(xts_tweak.padding)); |
0b81d077 JK |
183 | |
184 | sg_init_table(&dst, 1); | |
1400451f | 185 | sg_set_page(&dst, dest_page, len, offs); |
0b81d077 | 186 | sg_init_table(&src, 1); |
1400451f DG |
187 | sg_set_page(&src, src_page, len, offs); |
188 | skcipher_request_set_crypt(req, &src, &dst, len, &xts_tweak); | |
0b81d077 | 189 | if (rw == FS_DECRYPT) |
d407574e | 190 | res = crypto_skcipher_decrypt(req); |
0b81d077 | 191 | else |
d407574e | 192 | res = crypto_skcipher_encrypt(req); |
0b81d077 JK |
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); |
0b81d077 JK |
199 | if (res) { |
200 | printk_ratelimited(KERN_ERR | |
d407574e | 201 | "%s: crypto_skcipher_encrypt() returned %d\n", |
0b81d077 JK |
202 | __func__, res); |
203 | return res; | |
204 | } | |
205 | return 0; | |
206 | } | |
207 | ||
b32e4482 | 208 | static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags) |
0b81d077 | 209 | { |
b32e4482 | 210 | ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags); |
0b81d077 JK |
211 | if (ctx->w.bounce_page == NULL) |
212 | return ERR_PTR(-ENOMEM); | |
6a34e4d2 | 213 | ctx->flags |= FS_CTX_HAS_BOUNCE_BUFFER_FL; |
0b81d077 JK |
214 | return ctx->w.bounce_page; |
215 | } | |
216 | ||
217 | /** | |
218 | * fscypt_encrypt_page() - Encrypts a page | |
1400451f DG |
219 | * @inode: The inode for which the encryption should take place |
220 | * @page: The page to encrypt. Must be locked for bounce-page | |
221 | * encryption. | |
222 | * @len: Length of data to encrypt in @page and encrypted | |
223 | * data in returned page. | |
224 | * @offs: Offset of data within @page and returned | |
225 | * page holding encrypted data. | |
226 | * @lblk_num: Logical block number. This must be unique for multiple | |
227 | * calls with same inode, except when overwriting | |
228 | * previously written data. | |
229 | * @gfp_flags: The gfp flag for memory allocation | |
0b81d077 | 230 | * |
1400451f DG |
231 | * Encrypts @page using the ctx encryption context. Performs encryption |
232 | * either in-place or into a newly allocated bounce page. | |
233 | * Called on the page write path. | |
0b81d077 | 234 | * |
1400451f DG |
235 | * Bounce page allocation is the default. |
236 | * In this case, the contents of @page are encrypted and stored in an | |
237 | * allocated bounce page. @page has to be locked and the caller must call | |
0b81d077 JK |
238 | * fscrypt_restore_control_page() on the returned ciphertext page to |
239 | * release the bounce buffer and the encryption context. | |
240 | * | |
bd7b8290 | 241 | * In-place encryption is used by setting the FS_CFLG_OWN_PAGES flag in |
1400451f DG |
242 | * fscrypt_operations. Here, the input-page is returned with its content |
243 | * encrypted. | |
244 | * | |
245 | * Return: A page with the encrypted content on success. Else, an | |
0b81d077 JK |
246 | * error value or NULL. |
247 | */ | |
0b93e1b9 | 248 | struct page *fscrypt_encrypt_page(const struct inode *inode, |
1400451f DG |
249 | struct page *page, |
250 | unsigned int len, | |
251 | unsigned int offs, | |
252 | u64 lblk_num, gfp_t gfp_flags) | |
7821d4dd | 253 | |
0b81d077 JK |
254 | { |
255 | struct fscrypt_ctx *ctx; | |
1400451f | 256 | struct page *ciphertext_page = page; |
0b81d077 JK |
257 | int err; |
258 | ||
1400451f | 259 | BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0); |
0b81d077 | 260 | |
bd7b8290 | 261 | if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) { |
9e532772 | 262 | /* with inplace-encryption we just encrypt the page */ |
1400451f DG |
263 | err = do_page_crypto(inode, FS_ENCRYPT, lblk_num, |
264 | page, ciphertext_page, | |
265 | len, offs, gfp_flags); | |
9e532772 DG |
266 | if (err) |
267 | return ERR_PTR(err); | |
268 | ||
269 | return ciphertext_page; | |
270 | } | |
271 | ||
bd7b8290 DG |
272 | BUG_ON(!PageLocked(page)); |
273 | ||
b32e4482 | 274 | ctx = fscrypt_get_ctx(inode, gfp_flags); |
0b81d077 JK |
275 | if (IS_ERR(ctx)) |
276 | return (struct page *)ctx; | |
277 | ||
9e532772 DG |
278 | /* The encryption operation will require a bounce page. */ |
279 | ciphertext_page = alloc_bounce_page(ctx, gfp_flags); | |
280 | if (IS_ERR(ciphertext_page)) | |
281 | goto errout; | |
0b81d077 | 282 | |
1400451f DG |
283 | ctx->w.control_page = page; |
284 | err = do_page_crypto(inode, FS_ENCRYPT, lblk_num, | |
285 | page, ciphertext_page, | |
286 | len, offs, gfp_flags); | |
0b81d077 JK |
287 | if (err) { |
288 | ciphertext_page = ERR_PTR(err); | |
289 | goto errout; | |
290 | } | |
9e532772 DG |
291 | SetPagePrivate(ciphertext_page); |
292 | set_page_private(ciphertext_page, (unsigned long)ctx); | |
293 | lock_page(ciphertext_page); | |
0b81d077 JK |
294 | return ciphertext_page; |
295 | ||
296 | errout: | |
297 | fscrypt_release_ctx(ctx); | |
298 | return ciphertext_page; | |
299 | } | |
300 | EXPORT_SYMBOL(fscrypt_encrypt_page); | |
301 | ||
302 | /** | |
7821d4dd | 303 | * fscrypt_decrypt_page() - Decrypts a page in-place |
1400451f DG |
304 | * @inode: The corresponding inode for the page to decrypt. |
305 | * @page: The page to decrypt. Must be locked in case | |
bd7b8290 | 306 | * it is a writeback page (FS_CFLG_OWN_PAGES unset). |
1400451f DG |
307 | * @len: Number of bytes in @page to be decrypted. |
308 | * @offs: Start of data in @page. | |
309 | * @lblk_num: Logical block number. | |
0b81d077 JK |
310 | * |
311 | * Decrypts page in-place using the ctx encryption context. | |
312 | * | |
313 | * Called from the read completion callback. | |
314 | * | |
315 | * Return: Zero on success, non-zero otherwise. | |
316 | */ | |
0b93e1b9 | 317 | int fscrypt_decrypt_page(const struct inode *inode, struct page *page, |
1400451f | 318 | unsigned int len, unsigned int offs, u64 lblk_num) |
0b81d077 | 319 | { |
bd7b8290 DG |
320 | if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES)) |
321 | BUG_ON(!PageLocked(page)); | |
322 | ||
1400451f DG |
323 | return do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page, len, |
324 | offs, GFP_NOFS); | |
0b81d077 JK |
325 | } |
326 | EXPORT_SYMBOL(fscrypt_decrypt_page); | |
327 | ||
0b93e1b9 | 328 | int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, |
0b81d077 JK |
329 | sector_t pblk, unsigned int len) |
330 | { | |
331 | struct fscrypt_ctx *ctx; | |
332 | struct page *ciphertext_page = NULL; | |
333 | struct bio *bio; | |
334 | int ret, err = 0; | |
335 | ||
09cbfeaf | 336 | BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE); |
0b81d077 | 337 | |
b32e4482 | 338 | ctx = fscrypt_get_ctx(inode, GFP_NOFS); |
0b81d077 JK |
339 | if (IS_ERR(ctx)) |
340 | return PTR_ERR(ctx); | |
341 | ||
b32e4482 | 342 | ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT); |
0b81d077 JK |
343 | if (IS_ERR(ciphertext_page)) { |
344 | err = PTR_ERR(ciphertext_page); | |
345 | goto errout; | |
346 | } | |
347 | ||
348 | while (len--) { | |
349 | err = do_page_crypto(inode, FS_ENCRYPT, lblk, | |
b32e4482 | 350 | ZERO_PAGE(0), ciphertext_page, |
7821d4dd | 351 | PAGE_SIZE, 0, GFP_NOFS); |
0b81d077 JK |
352 | if (err) |
353 | goto errout; | |
354 | ||
b32e4482 | 355 | bio = bio_alloc(GFP_NOWAIT, 1); |
0b81d077 JK |
356 | if (!bio) { |
357 | err = -ENOMEM; | |
358 | goto errout; | |
359 | } | |
360 | bio->bi_bdev = inode->i_sb->s_bdev; | |
361 | bio->bi_iter.bi_sector = | |
362 | pblk << (inode->i_sb->s_blocksize_bits - 9); | |
95fe6c1a | 363 | bio_set_op_attrs(bio, REQ_OP_WRITE, 0); |
0b81d077 JK |
364 | ret = bio_add_page(bio, ciphertext_page, |
365 | inode->i_sb->s_blocksize, 0); | |
366 | if (ret != inode->i_sb->s_blocksize) { | |
367 | /* should never happen! */ | |
368 | WARN_ON(1); | |
369 | bio_put(bio); | |
370 | err = -EIO; | |
371 | goto errout; | |
372 | } | |
4e49ea4a | 373 | err = submit_bio_wait(bio); |
0b81d077 JK |
374 | if ((err == 0) && bio->bi_error) |
375 | err = -EIO; | |
376 | bio_put(bio); | |
377 | if (err) | |
378 | goto errout; | |
379 | lblk++; | |
380 | pblk++; | |
381 | } | |
382 | err = 0; | |
383 | errout: | |
384 | fscrypt_release_ctx(ctx); | |
385 | return err; | |
386 | } | |
387 | EXPORT_SYMBOL(fscrypt_zeroout_range); | |
388 | ||
389 | /* | |
390 | * Validate dentries for encrypted directories to make sure we aren't | |
391 | * potentially caching stale data after a key has been added or | |
392 | * removed. | |
393 | */ | |
394 | static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags) | |
395 | { | |
d7d75352 JK |
396 | struct dentry *dir; |
397 | struct fscrypt_info *ci; | |
0b81d077 JK |
398 | int dir_has_key, cached_with_key; |
399 | ||
03a8bb0e JK |
400 | if (flags & LOOKUP_RCU) |
401 | return -ECHILD; | |
402 | ||
d7d75352 JK |
403 | dir = dget_parent(dentry); |
404 | if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) { | |
405 | dput(dir); | |
0b81d077 | 406 | return 0; |
d7d75352 | 407 | } |
0b81d077 | 408 | |
d7d75352 | 409 | ci = d_inode(dir)->i_crypt_info; |
0b81d077 JK |
410 | if (ci && ci->ci_keyring_key && |
411 | (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) | | |
412 | (1 << KEY_FLAG_REVOKED) | | |
413 | (1 << KEY_FLAG_DEAD)))) | |
414 | ci = NULL; | |
415 | ||
416 | /* this should eventually be an flag in d_flags */ | |
417 | spin_lock(&dentry->d_lock); | |
418 | cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY; | |
419 | spin_unlock(&dentry->d_lock); | |
420 | dir_has_key = (ci != NULL); | |
d7d75352 | 421 | dput(dir); |
0b81d077 JK |
422 | |
423 | /* | |
424 | * If the dentry was cached without the key, and it is a | |
425 | * negative dentry, it might be a valid name. We can't check | |
426 | * if the key has since been made available due to locking | |
427 | * reasons, so we fail the validation so ext4_lookup() can do | |
428 | * this check. | |
429 | * | |
430 | * We also fail the validation if the dentry was created with | |
431 | * the key present, but we no longer have the key, or vice versa. | |
432 | */ | |
433 | if ((!cached_with_key && d_is_negative(dentry)) || | |
434 | (!cached_with_key && dir_has_key) || | |
435 | (cached_with_key && !dir_has_key)) | |
436 | return 0; | |
437 | return 1; | |
438 | } | |
439 | ||
440 | const struct dentry_operations fscrypt_d_ops = { | |
441 | .d_revalidate = fscrypt_d_revalidate, | |
442 | }; | |
443 | EXPORT_SYMBOL(fscrypt_d_ops); | |
444 | ||
445 | /* | |
446 | * Call fscrypt_decrypt_page on every single page, reusing the encryption | |
447 | * context. | |
448 | */ | |
449 | static void completion_pages(struct work_struct *work) | |
450 | { | |
451 | struct fscrypt_ctx *ctx = | |
452 | container_of(work, struct fscrypt_ctx, r.work); | |
453 | struct bio *bio = ctx->r.bio; | |
454 | struct bio_vec *bv; | |
455 | int i; | |
456 | ||
457 | bio_for_each_segment_all(bv, bio, i) { | |
458 | struct page *page = bv->bv_page; | |
7821d4dd | 459 | int ret = fscrypt_decrypt_page(page->mapping->host, page, |
9c4bb8a3 | 460 | PAGE_SIZE, 0, page->index); |
0b81d077 JK |
461 | |
462 | if (ret) { | |
463 | WARN_ON_ONCE(1); | |
464 | SetPageError(page); | |
465 | } else { | |
466 | SetPageUptodate(page); | |
467 | } | |
468 | unlock_page(page); | |
469 | } | |
470 | fscrypt_release_ctx(ctx); | |
471 | bio_put(bio); | |
472 | } | |
473 | ||
474 | void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio) | |
475 | { | |
476 | INIT_WORK(&ctx->r.work, completion_pages); | |
477 | ctx->r.bio = bio; | |
478 | queue_work(fscrypt_read_workqueue, &ctx->r.work); | |
479 | } | |
480 | EXPORT_SYMBOL(fscrypt_decrypt_bio_pages); | |
481 | ||
482 | void fscrypt_pullback_bio_page(struct page **page, bool restore) | |
483 | { | |
484 | struct fscrypt_ctx *ctx; | |
485 | struct page *bounce_page; | |
486 | ||
487 | /* The bounce data pages are unmapped. */ | |
488 | if ((*page)->mapping) | |
489 | return; | |
490 | ||
491 | /* The bounce data page is unmapped. */ | |
492 | bounce_page = *page; | |
493 | ctx = (struct fscrypt_ctx *)page_private(bounce_page); | |
494 | ||
495 | /* restore control page */ | |
496 | *page = ctx->w.control_page; | |
497 | ||
498 | if (restore) | |
499 | fscrypt_restore_control_page(bounce_page); | |
500 | } | |
501 | EXPORT_SYMBOL(fscrypt_pullback_bio_page); | |
502 | ||
503 | void fscrypt_restore_control_page(struct page *page) | |
504 | { | |
505 | struct fscrypt_ctx *ctx; | |
506 | ||
507 | ctx = (struct fscrypt_ctx *)page_private(page); | |
508 | set_page_private(page, (unsigned long)NULL); | |
509 | ClearPagePrivate(page); | |
510 | unlock_page(page); | |
511 | fscrypt_release_ctx(ctx); | |
512 | } | |
513 | EXPORT_SYMBOL(fscrypt_restore_control_page); | |
514 | ||
515 | static void fscrypt_destroy(void) | |
516 | { | |
517 | struct fscrypt_ctx *pos, *n; | |
518 | ||
519 | list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list) | |
520 | kmem_cache_free(fscrypt_ctx_cachep, pos); | |
521 | INIT_LIST_HEAD(&fscrypt_free_ctxs); | |
522 | mempool_destroy(fscrypt_bounce_page_pool); | |
523 | fscrypt_bounce_page_pool = NULL; | |
524 | } | |
525 | ||
526 | /** | |
527 | * fscrypt_initialize() - allocate major buffers for fs encryption. | |
f32d7ac2 | 528 | * @cop_flags: fscrypt operations flags |
0b81d077 JK |
529 | * |
530 | * We only call this when we start accessing encrypted files, since it | |
531 | * results in memory getting allocated that wouldn't otherwise be used. | |
532 | * | |
533 | * Return: Zero on success, non-zero otherwise. | |
534 | */ | |
f32d7ac2 | 535 | int fscrypt_initialize(unsigned int cop_flags) |
0b81d077 JK |
536 | { |
537 | int i, res = -ENOMEM; | |
538 | ||
f32d7ac2 DG |
539 | /* |
540 | * No need to allocate a bounce page pool if there already is one or | |
541 | * this FS won't use it. | |
542 | */ | |
543 | if (cop_flags & FS_CFLG_OWN_PAGES || fscrypt_bounce_page_pool) | |
0b81d077 JK |
544 | return 0; |
545 | ||
546 | mutex_lock(&fscrypt_init_mutex); | |
547 | if (fscrypt_bounce_page_pool) | |
548 | goto already_initialized; | |
549 | ||
550 | for (i = 0; i < num_prealloc_crypto_ctxs; i++) { | |
551 | struct fscrypt_ctx *ctx; | |
552 | ||
553 | ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS); | |
554 | if (!ctx) | |
555 | goto fail; | |
556 | list_add(&ctx->free_list, &fscrypt_free_ctxs); | |
557 | } | |
558 | ||
559 | fscrypt_bounce_page_pool = | |
560 | mempool_create_page_pool(num_prealloc_crypto_pages, 0); | |
561 | if (!fscrypt_bounce_page_pool) | |
562 | goto fail; | |
563 | ||
564 | already_initialized: | |
565 | mutex_unlock(&fscrypt_init_mutex); | |
566 | return 0; | |
567 | fail: | |
568 | fscrypt_destroy(); | |
569 | mutex_unlock(&fscrypt_init_mutex); | |
570 | return res; | |
571 | } | |
0b81d077 JK |
572 | |
573 | /** | |
574 | * fscrypt_init() - Set up for fs encryption. | |
575 | */ | |
576 | static int __init fscrypt_init(void) | |
577 | { | |
578 | fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue", | |
579 | WQ_HIGHPRI, 0); | |
580 | if (!fscrypt_read_workqueue) | |
581 | goto fail; | |
582 | ||
583 | fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT); | |
584 | if (!fscrypt_ctx_cachep) | |
585 | goto fail_free_queue; | |
586 | ||
587 | fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT); | |
588 | if (!fscrypt_info_cachep) | |
589 | goto fail_free_ctx; | |
590 | ||
591 | return 0; | |
592 | ||
593 | fail_free_ctx: | |
594 | kmem_cache_destroy(fscrypt_ctx_cachep); | |
595 | fail_free_queue: | |
596 | destroy_workqueue(fscrypt_read_workqueue); | |
597 | fail: | |
598 | return -ENOMEM; | |
599 | } | |
600 | module_init(fscrypt_init) | |
601 | ||
602 | /** | |
603 | * fscrypt_exit() - Shutdown the fs encryption system | |
604 | */ | |
605 | static void __exit fscrypt_exit(void) | |
606 | { | |
607 | fscrypt_destroy(); | |
608 | ||
609 | if (fscrypt_read_workqueue) | |
610 | destroy_workqueue(fscrypt_read_workqueue); | |
611 | kmem_cache_destroy(fscrypt_ctx_cachep); | |
612 | kmem_cache_destroy(fscrypt_info_cachep); | |
613 | } | |
614 | module_exit(fscrypt_exit); | |
615 | ||
616 | MODULE_LICENSE("GPL"); |