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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>
27#include <linux/bio.h>
28#include <linux/dcache.h>
29#include <linux/namei.h>
30#include <linux/fscrypto.h>
31#include <linux/ecryptfs.h>
32
33static unsigned int num_prealloc_crypto_pages = 32;
34static unsigned int num_prealloc_crypto_ctxs = 128;
35
36module_param(num_prealloc_crypto_pages, uint, 0444);
37MODULE_PARM_DESC(num_prealloc_crypto_pages,
38 "Number of crypto pages to preallocate");
39module_param(num_prealloc_crypto_ctxs, uint, 0444);
40MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
41 "Number of crypto contexts to preallocate");
42
43static mempool_t *fscrypt_bounce_page_pool = NULL;
44
45static LIST_HEAD(fscrypt_free_ctxs);
46static DEFINE_SPINLOCK(fscrypt_ctx_lock);
47
48static struct workqueue_struct *fscrypt_read_workqueue;
49static DEFINE_MUTEX(fscrypt_init_mutex);
50
51static struct kmem_cache *fscrypt_ctx_cachep;
52struct kmem_cache *fscrypt_info_cachep;
53
54
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60
61
62
63void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
64{
65 unsigned long flags;
66
67 if (ctx->flags & FS_WRITE_PATH_FL && ctx->w.bounce_page) {
68 mempool_free(ctx->w.bounce_page, fscrypt_bounce_page_pool);
69 ctx->w.bounce_page = NULL;
70 }
71 ctx->w.control_page = NULL;
72 if (ctx->flags & FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
73 kmem_cache_free(fscrypt_ctx_cachep, ctx);
74 } else {
75 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
76 list_add(&ctx->free_list, &fscrypt_free_ctxs);
77 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
78 }
79}
80EXPORT_SYMBOL(fscrypt_release_ctx);
81
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89
90
91
92struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode, gfp_t gfp_flags)
93{
94 struct fscrypt_ctx *ctx = NULL;
95 struct fscrypt_info *ci = inode->i_crypt_info;
96 unsigned long flags;
97
98 if (ci == NULL)
99 return ERR_PTR(-ENOKEY);
100
101
102
103
104
105
106
107
108
109
110
111 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
112 ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
113 struct fscrypt_ctx, free_list);
114 if (ctx)
115 list_del(&ctx->free_list);
116 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
117 if (!ctx) {
118 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
119 if (!ctx)
120 return ERR_PTR(-ENOMEM);
121 ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
122 } else {
123 ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
124 }
125 ctx->flags &= ~FS_WRITE_PATH_FL;
126 return ctx;
127}
128EXPORT_SYMBOL(fscrypt_get_ctx);
129
130
131
132
133
134
135static void fscrypt_complete(struct crypto_async_request *req, int res)
136{
137 struct fscrypt_completion_result *ecr = req->data;
138
139 if (res == -EINPROGRESS)
140 return;
141 ecr->res = res;
142 complete(&ecr->completion);
143}
144
145typedef enum {
146 FS_DECRYPT = 0,
147 FS_ENCRYPT,
148} fscrypt_direction_t;
149
150static int do_page_crypto(struct inode *inode,
151 fscrypt_direction_t rw, pgoff_t index,
152 struct page *src_page, struct page *dest_page,
153 gfp_t gfp_flags)
154{
155 u8 xts_tweak[FS_XTS_TWEAK_SIZE];
156 struct skcipher_request *req = NULL;
157 DECLARE_FS_COMPLETION_RESULT(ecr);
158 struct scatterlist dst, src;
159 struct fscrypt_info *ci = inode->i_crypt_info;
160 struct crypto_skcipher *tfm = ci->ci_ctfm;
161 int res = 0;
162
163 req = skcipher_request_alloc(tfm, gfp_flags);
164 if (!req) {
165 printk_ratelimited(KERN_ERR
166 "%s: crypto_request_alloc() failed\n",
167 __func__);
168 return -ENOMEM;
169 }
170
171 skcipher_request_set_callback(
172 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
173 fscrypt_complete, &ecr);
174
175 BUILD_BUG_ON(FS_XTS_TWEAK_SIZE < sizeof(index));
176 memcpy(xts_tweak, &index, sizeof(index));
177 memset(&xts_tweak[sizeof(index)], 0,
178 FS_XTS_TWEAK_SIZE - sizeof(index));
179
180 sg_init_table(&dst, 1);
181 sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
182 sg_init_table(&src, 1);
183 sg_set_page(&src, src_page, PAGE_SIZE, 0);
184 skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
185 xts_tweak);
186 if (rw == FS_DECRYPT)
187 res = crypto_skcipher_decrypt(req);
188 else
189 res = crypto_skcipher_encrypt(req);
190 if (res == -EINPROGRESS || res == -EBUSY) {
191 BUG_ON(req->base.data != &ecr);
192 wait_for_completion(&ecr.completion);
193 res = ecr.res;
194 }
195 skcipher_request_free(req);
196 if (res) {
197 printk_ratelimited(KERN_ERR
198 "%s: crypto_skcipher_encrypt() returned %d\n",
199 __func__, res);
200 return res;
201 }
202 return 0;
203}
204
205static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
206{
207 ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
208 if (ctx->w.bounce_page == NULL)
209 return ERR_PTR(-ENOMEM);
210 ctx->flags |= FS_WRITE_PATH_FL;
211 return ctx->w.bounce_page;
212}
213
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228
229
230struct page *fscrypt_encrypt_page(struct inode *inode,
231 struct page *plaintext_page, gfp_t gfp_flags)
232{
233 struct fscrypt_ctx *ctx;
234 struct page *ciphertext_page = NULL;
235 int err;
236
237 BUG_ON(!PageLocked(plaintext_page));
238
239 ctx = fscrypt_get_ctx(inode, gfp_flags);
240 if (IS_ERR(ctx))
241 return (struct page *)ctx;
242
243
244 ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
245 if (IS_ERR(ciphertext_page))
246 goto errout;
247
248 ctx->w.control_page = plaintext_page;
249 err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
250 plaintext_page, ciphertext_page,
251 gfp_flags);
252 if (err) {
253 ciphertext_page = ERR_PTR(err);
254 goto errout;
255 }
256 SetPagePrivate(ciphertext_page);
257 set_page_private(ciphertext_page, (unsigned long)ctx);
258 lock_page(ciphertext_page);
259 return ciphertext_page;
260
261errout:
262 fscrypt_release_ctx(ctx);
263 return ciphertext_page;
264}
265EXPORT_SYMBOL(fscrypt_encrypt_page);
266
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273
274
275
276
277int fscrypt_decrypt_page(struct page *page)
278{
279 BUG_ON(!PageLocked(page));
280
281 return do_page_crypto(page->mapping->host,
282 FS_DECRYPT, page->index, page, page, GFP_NOFS);
283}
284EXPORT_SYMBOL(fscrypt_decrypt_page);
285
286int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,
287 sector_t pblk, unsigned int len)
288{
289 struct fscrypt_ctx *ctx;
290 struct page *ciphertext_page = NULL;
291 struct bio *bio;
292 int ret, err = 0;
293
294 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
295
296 ctx = fscrypt_get_ctx(inode, GFP_NOFS);
297 if (IS_ERR(ctx))
298 return PTR_ERR(ctx);
299
300 ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
301 if (IS_ERR(ciphertext_page)) {
302 err = PTR_ERR(ciphertext_page);
303 goto errout;
304 }
305
306 while (len--) {
307 err = do_page_crypto(inode, FS_ENCRYPT, lblk,
308 ZERO_PAGE(0), ciphertext_page,
309 GFP_NOFS);
310 if (err)
311 goto errout;
312
313 bio = bio_alloc(GFP_NOWAIT, 1);
314 if (!bio) {
315 err = -ENOMEM;
316 goto errout;
317 }
318 bio->bi_bdev = inode->i_sb->s_bdev;
319 bio->bi_iter.bi_sector =
320 pblk << (inode->i_sb->s_blocksize_bits - 9);
321 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
322 ret = bio_add_page(bio, ciphertext_page,
323 inode->i_sb->s_blocksize, 0);
324 if (ret != inode->i_sb->s_blocksize) {
325
326 WARN_ON(1);
327 bio_put(bio);
328 err = -EIO;
329 goto errout;
330 }
331 err = submit_bio_wait(bio);
332 if ((err == 0) && bio->bi_error)
333 err = -EIO;
334 bio_put(bio);
335 if (err)
336 goto errout;
337 lblk++;
338 pblk++;
339 }
340 err = 0;
341errout:
342 fscrypt_release_ctx(ctx);
343 return err;
344}
345EXPORT_SYMBOL(fscrypt_zeroout_range);
346
347
348
349
350
351
352static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
353{
354 struct dentry *dir;
355 struct fscrypt_info *ci;
356 int dir_has_key, cached_with_key;
357
358 if (flags & LOOKUP_RCU)
359 return -ECHILD;
360
361 dir = dget_parent(dentry);
362 if (!d_inode(dir)->i_sb->s_cop->is_encrypted(d_inode(dir))) {
363 dput(dir);
364 return 0;
365 }
366
367 ci = d_inode(dir)->i_crypt_info;
368 if (ci && ci->ci_keyring_key &&
369 (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
370 (1 << KEY_FLAG_REVOKED) |
371 (1 << KEY_FLAG_DEAD))))
372 ci = NULL;
373
374
375 spin_lock(&dentry->d_lock);
376 cached_with_key = dentry->d_flags & DCACHE_ENCRYPTED_WITH_KEY;
377 spin_unlock(&dentry->d_lock);
378 dir_has_key = (ci != NULL);
379 dput(dir);
380
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386
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388
389
390
391 if ((!cached_with_key && d_is_negative(dentry)) ||
392 (!cached_with_key && dir_has_key) ||
393 (cached_with_key && !dir_has_key))
394 return 0;
395 return 1;
396}
397
398const struct dentry_operations fscrypt_d_ops = {
399 .d_revalidate = fscrypt_d_revalidate,
400};
401EXPORT_SYMBOL(fscrypt_d_ops);
402
403
404
405
406
407static void completion_pages(struct work_struct *work)
408{
409 struct fscrypt_ctx *ctx =
410 container_of(work, struct fscrypt_ctx, r.work);
411 struct bio *bio = ctx->r.bio;
412 struct bio_vec *bv;
413 int i;
414
415 bio_for_each_segment_all(bv, bio, i) {
416 struct page *page = bv->bv_page;
417 int ret = fscrypt_decrypt_page(page);
418
419 if (ret) {
420 WARN_ON_ONCE(1);
421 SetPageError(page);
422 } else {
423 SetPageUptodate(page);
424 }
425 unlock_page(page);
426 }
427 fscrypt_release_ctx(ctx);
428 bio_put(bio);
429}
430
431void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
432{
433 INIT_WORK(&ctx->r.work, completion_pages);
434 ctx->r.bio = bio;
435 queue_work(fscrypt_read_workqueue, &ctx->r.work);
436}
437EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
438
439void fscrypt_pullback_bio_page(struct page **page, bool restore)
440{
441 struct fscrypt_ctx *ctx;
442 struct page *bounce_page;
443
444
445 if ((*page)->mapping)
446 return;
447
448
449 bounce_page = *page;
450 ctx = (struct fscrypt_ctx *)page_private(bounce_page);
451
452
453 *page = ctx->w.control_page;
454
455 if (restore)
456 fscrypt_restore_control_page(bounce_page);
457}
458EXPORT_SYMBOL(fscrypt_pullback_bio_page);
459
460void fscrypt_restore_control_page(struct page *page)
461{
462 struct fscrypt_ctx *ctx;
463
464 ctx = (struct fscrypt_ctx *)page_private(page);
465 set_page_private(page, (unsigned long)NULL);
466 ClearPagePrivate(page);
467 unlock_page(page);
468 fscrypt_release_ctx(ctx);
469}
470EXPORT_SYMBOL(fscrypt_restore_control_page);
471
472static void fscrypt_destroy(void)
473{
474 struct fscrypt_ctx *pos, *n;
475
476 list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
477 kmem_cache_free(fscrypt_ctx_cachep, pos);
478 INIT_LIST_HEAD(&fscrypt_free_ctxs);
479 mempool_destroy(fscrypt_bounce_page_pool);
480 fscrypt_bounce_page_pool = NULL;
481}
482
483
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486
487
488
489
490
491int fscrypt_initialize(void)
492{
493 int i, res = -ENOMEM;
494
495 if (fscrypt_bounce_page_pool)
496 return 0;
497
498 mutex_lock(&fscrypt_init_mutex);
499 if (fscrypt_bounce_page_pool)
500 goto already_initialized;
501
502 for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
503 struct fscrypt_ctx *ctx;
504
505 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
506 if (!ctx)
507 goto fail;
508 list_add(&ctx->free_list, &fscrypt_free_ctxs);
509 }
510
511 fscrypt_bounce_page_pool =
512 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
513 if (!fscrypt_bounce_page_pool)
514 goto fail;
515
516already_initialized:
517 mutex_unlock(&fscrypt_init_mutex);
518 return 0;
519fail:
520 fscrypt_destroy();
521 mutex_unlock(&fscrypt_init_mutex);
522 return res;
523}
524EXPORT_SYMBOL(fscrypt_initialize);
525
526
527
528
529static int __init fscrypt_init(void)
530{
531 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
532 WQ_HIGHPRI, 0);
533 if (!fscrypt_read_workqueue)
534 goto fail;
535
536 fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
537 if (!fscrypt_ctx_cachep)
538 goto fail_free_queue;
539
540 fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
541 if (!fscrypt_info_cachep)
542 goto fail_free_ctx;
543
544 return 0;
545
546fail_free_ctx:
547 kmem_cache_destroy(fscrypt_ctx_cachep);
548fail_free_queue:
549 destroy_workqueue(fscrypt_read_workqueue);
550fail:
551 return -ENOMEM;
552}
553module_init(fscrypt_init)
554
555
556
557
558static void __exit fscrypt_exit(void)
559{
560 fscrypt_destroy();
561
562 if (fscrypt_read_workqueue)
563 destroy_workqueue(fscrypt_read_workqueue);
564 kmem_cache_destroy(fscrypt_ctx_cachep);
565 kmem_cache_destroy(fscrypt_info_cachep);
566}
567module_exit(fscrypt_exit);
568
569MODULE_LICENSE("GPL");
570