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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This contains encryption functions for per-file encryption.
4 *
5 * Copyright (C) 2015, Google, Inc.
6 * Copyright (C) 2015, Motorola Mobility
7 *
8 * Written by Michael Halcrow, 2014.
9 *
10 * Filename encryption additions
11 * Uday Savagaonkar, 2014
12 * Encryption policy handling additions
13 * Ildar Muslukhov, 2014
14 * Add fscrypt_pullback_bio_page()
15 * Jaegeuk Kim, 2015.
16 *
17 * This has not yet undergone a rigorous security audit.
18 *
19 * The usage of AES-XTS should conform to recommendations in NIST
20 * Special Publication 800-38E and IEEE P1619/D16.
21 */
22
23#include <linux/pagemap.h>
24#include <linux/mempool.h>
25#include <linux/module.h>
26#include <linux/scatterlist.h>
27#include <linux/ratelimit.h>
28#include <linux/dcache.h>
29#include <linux/namei.h>
30#include <crypto/aes.h>
31#include <crypto/skcipher.h>
32#include "fscrypt_private.h"
33
34static unsigned int num_prealloc_crypto_pages = 32;
35static unsigned int num_prealloc_crypto_ctxs = 128;
36
37module_param(num_prealloc_crypto_pages, uint, 0444);
38MODULE_PARM_DESC(num_prealloc_crypto_pages,
39 "Number of crypto pages to preallocate");
40module_param(num_prealloc_crypto_ctxs, uint, 0444);
41MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
42 "Number of crypto contexts to preallocate");
43
44static mempool_t *fscrypt_bounce_page_pool = NULL;
45
46static LIST_HEAD(fscrypt_free_ctxs);
47static DEFINE_SPINLOCK(fscrypt_ctx_lock);
48
49static struct workqueue_struct *fscrypt_read_workqueue;
50static DEFINE_MUTEX(fscrypt_init_mutex);
51
52static struct kmem_cache *fscrypt_ctx_cachep;
53struct kmem_cache *fscrypt_info_cachep;
54
55void fscrypt_enqueue_decrypt_work(struct work_struct *work)
56{
57 queue_work(fscrypt_read_workqueue, work);
58}
59EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
60
61/**
62 * fscrypt_release_ctx() - Release a decryption context
63 * @ctx: The decryption context to release.
64 *
65 * If the decryption context was allocated from the pre-allocated pool, return
66 * it to that pool. Else, free it.
67 */
68void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
69{
70 unsigned long flags;
71
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
82/**
83 * fscrypt_get_ctx() - Get a decryption context
84 * @gfp_flags: The gfp flag for memory allocation
85 *
86 * Allocate and initialize a decryption context.
87 *
88 * Return: A new decryption context on success; an ERR_PTR() otherwise.
89 */
90struct fscrypt_ctx *fscrypt_get_ctx(gfp_t gfp_flags)
91{
92 struct fscrypt_ctx *ctx;
93 unsigned long flags;
94
95 /*
96 * First try getting a ctx from the free list so that we don't have to
97 * call into the slab allocator.
98 */
99 spin_lock_irqsave(&fscrypt_ctx_lock, flags);
100 ctx = list_first_entry_or_null(&fscrypt_free_ctxs,
101 struct fscrypt_ctx, free_list);
102 if (ctx)
103 list_del(&ctx->free_list);
104 spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
105 if (!ctx) {
106 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
107 if (!ctx)
108 return ERR_PTR(-ENOMEM);
109 ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
110 } else {
111 ctx->flags &= ~FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
112 }
113 return ctx;
114}
115EXPORT_SYMBOL(fscrypt_get_ctx);
116
117struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
118{
119 return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
120}
121
122/**
123 * fscrypt_free_bounce_page() - free a ciphertext bounce page
124 *
125 * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
126 * or by fscrypt_alloc_bounce_page() directly.
127 */
128void fscrypt_free_bounce_page(struct page *bounce_page)
129{
130 if (!bounce_page)
131 return;
132 set_page_private(bounce_page, (unsigned long)NULL);
133 ClearPagePrivate(bounce_page);
134 mempool_free(bounce_page, fscrypt_bounce_page_pool);
135}
136EXPORT_SYMBOL(fscrypt_free_bounce_page);
137
138void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
139 const struct fscrypt_info *ci)
140{
141 memset(iv, 0, ci->ci_mode->ivsize);
142 iv->lblk_num = cpu_to_le64(lblk_num);
143
144 if (fscrypt_is_direct_key_policy(&ci->ci_policy))
145 memcpy(iv->nonce, ci->ci_nonce, FS_KEY_DERIVATION_NONCE_SIZE);
146
147 if (ci->ci_essiv_tfm != NULL)
148 crypto_cipher_encrypt_one(ci->ci_essiv_tfm, iv->raw, iv->raw);
149}
150
151/* Encrypt or decrypt a single filesystem block of file contents */
152int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
153 u64 lblk_num, struct page *src_page,
154 struct page *dest_page, unsigned int len,
155 unsigned int offs, gfp_t gfp_flags)
156{
157 union fscrypt_iv iv;
158 struct skcipher_request *req = NULL;
159 DECLARE_CRYPTO_WAIT(wait);
160 struct scatterlist dst, src;
161 struct fscrypt_info *ci = inode->i_crypt_info;
162 struct crypto_skcipher *tfm = ci->ci_ctfm;
163 int res = 0;
164
165 if (WARN_ON_ONCE(len <= 0))
166 return -EINVAL;
167 if (WARN_ON_ONCE(len % FS_CRYPTO_BLOCK_SIZE != 0))
168 return -EINVAL;
169
170 fscrypt_generate_iv(&iv, lblk_num, ci);
171
172 req = skcipher_request_alloc(tfm, gfp_flags);
173 if (!req)
174 return -ENOMEM;
175
176 skcipher_request_set_callback(
177 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
178 crypto_req_done, &wait);
179
180 sg_init_table(&dst, 1);
181 sg_set_page(&dst, dest_page, len, offs);
182 sg_init_table(&src, 1);
183 sg_set_page(&src, src_page, len, offs);
184 skcipher_request_set_crypt(req, &src, &dst, len, &iv);
185 if (rw == FS_DECRYPT)
186 res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
187 else
188 res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
189 skcipher_request_free(req);
190 if (res) {
191 fscrypt_err(inode, "%scryption failed for block %llu: %d",
192 (rw == FS_DECRYPT ? "De" : "En"), lblk_num, res);
193 return res;
194 }
195 return 0;
196}
197
198/**
199 * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a pagecache page
200 * @page: The locked pagecache page containing the block(s) to encrypt
201 * @len: Total size of the block(s) to encrypt. Must be a nonzero
202 * multiple of the filesystem's block size.
203 * @offs: Byte offset within @page of the first block to encrypt. Must be
204 * a multiple of the filesystem's block size.
205 * @gfp_flags: Memory allocation flags
206 *
207 * A new bounce page is allocated, and the specified block(s) are encrypted into
208 * it. In the bounce page, the ciphertext block(s) will be located at the same
209 * offsets at which the plaintext block(s) were located in the source page; any
210 * other parts of the bounce page will be left uninitialized. However, normally
211 * blocksize == PAGE_SIZE and the whole page is encrypted at once.
212 *
213 * This is for use by the filesystem's ->writepages() method.
214 *
215 * Return: the new encrypted bounce page on success; an ERR_PTR() on failure
216 */
217struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
218 unsigned int len,
219 unsigned int offs,
220 gfp_t gfp_flags)
221
222{
223 const struct inode *inode = page->mapping->host;
224 const unsigned int blockbits = inode->i_blkbits;
225 const unsigned int blocksize = 1 << blockbits;
226 struct page *ciphertext_page;
227 u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
228 (offs >> blockbits);
229 unsigned int i;
230 int err;
231
232 if (WARN_ON_ONCE(!PageLocked(page)))
233 return ERR_PTR(-EINVAL);
234
235 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
236 return ERR_PTR(-EINVAL);
237
238 ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
239 if (!ciphertext_page)
240 return ERR_PTR(-ENOMEM);
241
242 for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
243 err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num,
244 page, ciphertext_page,
245 blocksize, i, gfp_flags);
246 if (err) {
247 fscrypt_free_bounce_page(ciphertext_page);
248 return ERR_PTR(err);
249 }
250 }
251 SetPagePrivate(ciphertext_page);
252 set_page_private(ciphertext_page, (unsigned long)page);
253 return ciphertext_page;
254}
255EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks);
256
257/**
258 * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
259 * @inode: The inode to which this block belongs
260 * @page: The page containing the block to encrypt
261 * @len: Size of block to encrypt. Doesn't need to be a multiple of the
262 * fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE.
263 * @offs: Byte offset within @page at which the block to encrypt begins
264 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
265 * number of the block within the file
266 * @gfp_flags: Memory allocation flags
267 *
268 * Encrypt a possibly-compressed filesystem block that is located in an
269 * arbitrary page, not necessarily in the original pagecache page. The @inode
270 * and @lblk_num must be specified, as they can't be determined from @page.
271 *
272 * Return: 0 on success; -errno on failure
273 */
274int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
275 unsigned int len, unsigned int offs,
276 u64 lblk_num, gfp_t gfp_flags)
277{
278 return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page,
279 len, offs, gfp_flags);
280}
281EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
282
283/**
284 * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a pagecache page
285 * @page: The locked pagecache page containing the block(s) to decrypt
286 * @len: Total size of the block(s) to decrypt. Must be a nonzero
287 * multiple of the filesystem's block size.
288 * @offs: Byte offset within @page of the first block to decrypt. Must be
289 * a multiple of the filesystem's block size.
290 *
291 * The specified block(s) are decrypted in-place within the pagecache page,
292 * which must still be locked and not uptodate. Normally, blocksize ==
293 * PAGE_SIZE and the whole page is decrypted at once.
294 *
295 * This is for use by the filesystem's ->readpages() method.
296 *
297 * Return: 0 on success; -errno on failure
298 */
299int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
300 unsigned int offs)
301{
302 const struct inode *inode = page->mapping->host;
303 const unsigned int blockbits = inode->i_blkbits;
304 const unsigned int blocksize = 1 << blockbits;
305 u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
306 (offs >> blockbits);
307 unsigned int i;
308 int err;
309
310 if (WARN_ON_ONCE(!PageLocked(page)))
311 return -EINVAL;
312
313 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
314 return -EINVAL;
315
316 for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
317 err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page,
318 page, blocksize, i, GFP_NOFS);
319 if (err)
320 return err;
321 }
322 return 0;
323}
324EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
325
326/**
327 * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
328 * @inode: The inode to which this block belongs
329 * @page: The page containing the block to decrypt
330 * @len: Size of block to decrypt. Doesn't need to be a multiple of the
331 * fs block size, but must be a multiple of FS_CRYPTO_BLOCK_SIZE.
332 * @offs: Byte offset within @page at which the block to decrypt begins
333 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
334 * number of the block within the file
335 *
336 * Decrypt a possibly-compressed filesystem block that is located in an
337 * arbitrary page, not necessarily in the original pagecache page. The @inode
338 * and @lblk_num must be specified, as they can't be determined from @page.
339 *
340 * Return: 0 on success; -errno on failure
341 */
342int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
343 unsigned int len, unsigned int offs,
344 u64 lblk_num)
345{
346 return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
347 len, offs, GFP_NOFS);
348}
349EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
350
351/*
352 * Validate dentries in encrypted directories to make sure we aren't potentially
353 * caching stale dentries after a key has been added.
354 */
355static int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags)
356{
357 struct dentry *dir;
358 int err;
359 int valid;
360
361 /*
362 * Plaintext names are always valid, since fscrypt doesn't support
363 * reverting to ciphertext names without evicting the directory's inode
364 * -- which implies eviction of the dentries in the directory.
365 */
366 if (!(dentry->d_flags & DCACHE_ENCRYPTED_NAME))
367 return 1;
368
369 /*
370 * Ciphertext name; valid if the directory's key is still unavailable.
371 *
372 * Although fscrypt forbids rename() on ciphertext names, we still must
373 * use dget_parent() here rather than use ->d_parent directly. That's
374 * because a corrupted fs image may contain directory hard links, which
375 * the VFS handles by moving the directory's dentry tree in the dcache
376 * each time ->lookup() finds the directory and it already has a dentry
377 * elsewhere. Thus ->d_parent can be changing, and we must safely grab
378 * a reference to some ->d_parent to prevent it from being freed.
379 */
380
381 if (flags & LOOKUP_RCU)
382 return -ECHILD;
383
384 dir = dget_parent(dentry);
385 err = fscrypt_get_encryption_info(d_inode(dir));
386 valid = !fscrypt_has_encryption_key(d_inode(dir));
387 dput(dir);
388
389 if (err < 0)
390 return err;
391
392 return valid;
393}
394
395const struct dentry_operations fscrypt_d_ops = {
396 .d_revalidate = fscrypt_d_revalidate,
397};
398
399static void fscrypt_destroy(void)
400{
401 struct fscrypt_ctx *pos, *n;
402
403 list_for_each_entry_safe(pos, n, &fscrypt_free_ctxs, free_list)
404 kmem_cache_free(fscrypt_ctx_cachep, pos);
405 INIT_LIST_HEAD(&fscrypt_free_ctxs);
406 mempool_destroy(fscrypt_bounce_page_pool);
407 fscrypt_bounce_page_pool = NULL;
408}
409
410/**
411 * fscrypt_initialize() - allocate major buffers for fs encryption.
412 * @cop_flags: fscrypt operations flags
413 *
414 * We only call this when we start accessing encrypted files, since it
415 * results in memory getting allocated that wouldn't otherwise be used.
416 *
417 * Return: Zero on success, non-zero otherwise.
418 */
419int fscrypt_initialize(unsigned int cop_flags)
420{
421 int i, res = -ENOMEM;
422
423 /* No need to allocate a bounce page pool if this FS won't use it. */
424 if (cop_flags & FS_CFLG_OWN_PAGES)
425 return 0;
426
427 mutex_lock(&fscrypt_init_mutex);
428 if (fscrypt_bounce_page_pool)
429 goto already_initialized;
430
431 for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
432 struct fscrypt_ctx *ctx;
433
434 ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
435 if (!ctx)
436 goto fail;
437 list_add(&ctx->free_list, &fscrypt_free_ctxs);
438 }
439
440 fscrypt_bounce_page_pool =
441 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
442 if (!fscrypt_bounce_page_pool)
443 goto fail;
444
445already_initialized:
446 mutex_unlock(&fscrypt_init_mutex);
447 return 0;
448fail:
449 fscrypt_destroy();
450 mutex_unlock(&fscrypt_init_mutex);
451 return res;
452}
453
454void fscrypt_msg(const struct inode *inode, const char *level,
455 const char *fmt, ...)
456{
457 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
458 DEFAULT_RATELIMIT_BURST);
459 struct va_format vaf;
460 va_list args;
461
462 if (!__ratelimit(&rs))
463 return;
464
465 va_start(args, fmt);
466 vaf.fmt = fmt;
467 vaf.va = &args;
468 if (inode)
469 printk("%sfscrypt (%s, inode %lu): %pV\n",
470 level, inode->i_sb->s_id, inode->i_ino, &vaf);
471 else
472 printk("%sfscrypt: %pV\n", level, &vaf);
473 va_end(args);
474}
475
476/**
477 * fscrypt_init() - Set up for fs encryption.
478 */
479static int __init fscrypt_init(void)
480{
481 int err = -ENOMEM;
482
483 /*
484 * Use an unbound workqueue to allow bios to be decrypted in parallel
485 * even when they happen to complete on the same CPU. This sacrifices
486 * locality, but it's worthwhile since decryption is CPU-intensive.
487 *
488 * Also use a high-priority workqueue to prioritize decryption work,
489 * which blocks reads from completing, over regular application tasks.
490 */
491 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
492 WQ_UNBOUND | WQ_HIGHPRI,
493 num_online_cpus());
494 if (!fscrypt_read_workqueue)
495 goto fail;
496
497 fscrypt_ctx_cachep = KMEM_CACHE(fscrypt_ctx, SLAB_RECLAIM_ACCOUNT);
498 if (!fscrypt_ctx_cachep)
499 goto fail_free_queue;
500
501 fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
502 if (!fscrypt_info_cachep)
503 goto fail_free_ctx;
504
505 err = fscrypt_init_keyring();
506 if (err)
507 goto fail_free_info;
508
509 return 0;
510
511fail_free_info:
512 kmem_cache_destroy(fscrypt_info_cachep);
513fail_free_ctx:
514 kmem_cache_destroy(fscrypt_ctx_cachep);
515fail_free_queue:
516 destroy_workqueue(fscrypt_read_workqueue);
517fail:
518 return err;
519}
520late_initcall(fscrypt_init)
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * This contains encryption functions for per-file encryption.
4 *
5 * Copyright (C) 2015, Google, Inc.
6 * Copyright (C) 2015, Motorola Mobility
7 *
8 * Written by Michael Halcrow, 2014.
9 *
10 * Filename encryption additions
11 * Uday Savagaonkar, 2014
12 * Encryption policy handling additions
13 * Ildar Muslukhov, 2014
14 * Add fscrypt_pullback_bio_page()
15 * Jaegeuk Kim, 2015.
16 *
17 * This has not yet undergone a rigorous security audit.
18 *
19 * The usage of AES-XTS should conform to recommendations in NIST
20 * Special Publication 800-38E and IEEE P1619/D16.
21 */
22
23#include <linux/pagemap.h>
24#include <linux/mempool.h>
25#include <linux/module.h>
26#include <linux/scatterlist.h>
27#include <linux/ratelimit.h>
28#include <crypto/skcipher.h>
29#include "fscrypt_private.h"
30
31static unsigned int num_prealloc_crypto_pages = 32;
32
33module_param(num_prealloc_crypto_pages, uint, 0444);
34MODULE_PARM_DESC(num_prealloc_crypto_pages,
35 "Number of crypto pages to preallocate");
36
37static mempool_t *fscrypt_bounce_page_pool = NULL;
38
39static struct workqueue_struct *fscrypt_read_workqueue;
40static DEFINE_MUTEX(fscrypt_init_mutex);
41
42struct kmem_cache *fscrypt_info_cachep;
43
44void fscrypt_enqueue_decrypt_work(struct work_struct *work)
45{
46 queue_work(fscrypt_read_workqueue, work);
47}
48EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
49
50struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
51{
52 return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
53}
54
55/**
56 * fscrypt_free_bounce_page() - free a ciphertext bounce page
57 * @bounce_page: the bounce page to free, or NULL
58 *
59 * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
60 * or by fscrypt_alloc_bounce_page() directly.
61 */
62void fscrypt_free_bounce_page(struct page *bounce_page)
63{
64 if (!bounce_page)
65 return;
66 set_page_private(bounce_page, (unsigned long)NULL);
67 ClearPagePrivate(bounce_page);
68 mempool_free(bounce_page, fscrypt_bounce_page_pool);
69}
70EXPORT_SYMBOL(fscrypt_free_bounce_page);
71
72/*
73 * Generate the IV for the given logical block number within the given file.
74 * For filenames encryption, lblk_num == 0.
75 *
76 * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks()
77 * needs to know about any IV generation methods where the low bits of IV don't
78 * simply contain the lblk_num (e.g., IV_INO_LBLK_32).
79 */
80void fscrypt_generate_iv(union fscrypt_iv *iv, u64 lblk_num,
81 const struct fscrypt_info *ci)
82{
83 u8 flags = fscrypt_policy_flags(&ci->ci_policy);
84
85 memset(iv, 0, ci->ci_mode->ivsize);
86
87 if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
88 WARN_ON_ONCE(lblk_num > U32_MAX);
89 WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX);
90 lblk_num |= (u64)ci->ci_inode->i_ino << 32;
91 } else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {
92 WARN_ON_ONCE(lblk_num > U32_MAX);
93 lblk_num = (u32)(ci->ci_hashed_ino + lblk_num);
94 } else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {
95 memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE);
96 }
97 iv->lblk_num = cpu_to_le64(lblk_num);
98}
99
100/* Encrypt or decrypt a single filesystem block of file contents */
101int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw,
102 u64 lblk_num, struct page *src_page,
103 struct page *dest_page, unsigned int len,
104 unsigned int offs, gfp_t gfp_flags)
105{
106 union fscrypt_iv iv;
107 struct skcipher_request *req = NULL;
108 DECLARE_CRYPTO_WAIT(wait);
109 struct scatterlist dst, src;
110 struct fscrypt_info *ci = inode->i_crypt_info;
111 struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
112 int res = 0;
113
114 if (WARN_ON_ONCE(len <= 0))
115 return -EINVAL;
116 if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0))
117 return -EINVAL;
118
119 fscrypt_generate_iv(&iv, lblk_num, ci);
120
121 req = skcipher_request_alloc(tfm, gfp_flags);
122 if (!req)
123 return -ENOMEM;
124
125 skcipher_request_set_callback(
126 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
127 crypto_req_done, &wait);
128
129 sg_init_table(&dst, 1);
130 sg_set_page(&dst, dest_page, len, offs);
131 sg_init_table(&src, 1);
132 sg_set_page(&src, src_page, len, offs);
133 skcipher_request_set_crypt(req, &src, &dst, len, &iv);
134 if (rw == FS_DECRYPT)
135 res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
136 else
137 res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
138 skcipher_request_free(req);
139 if (res) {
140 fscrypt_err(inode, "%scryption failed for block %llu: %d",
141 (rw == FS_DECRYPT ? "De" : "En"), lblk_num, res);
142 return res;
143 }
144 return 0;
145}
146
147/**
148 * fscrypt_encrypt_pagecache_blocks() - Encrypt filesystem blocks from a
149 * pagecache page
150 * @page: The locked pagecache page containing the block(s) to encrypt
151 * @len: Total size of the block(s) to encrypt. Must be a nonzero
152 * multiple of the filesystem's block size.
153 * @offs: Byte offset within @page of the first block to encrypt. Must be
154 * a multiple of the filesystem's block size.
155 * @gfp_flags: Memory allocation flags. See details below.
156 *
157 * A new bounce page is allocated, and the specified block(s) are encrypted into
158 * it. In the bounce page, the ciphertext block(s) will be located at the same
159 * offsets at which the plaintext block(s) were located in the source page; any
160 * other parts of the bounce page will be left uninitialized. However, normally
161 * blocksize == PAGE_SIZE and the whole page is encrypted at once.
162 *
163 * This is for use by the filesystem's ->writepages() method.
164 *
165 * The bounce page allocation is mempool-backed, so it will always succeed when
166 * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS. However,
167 * only the first page of each bio can be allocated this way. To prevent
168 * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used.
169 *
170 * Return: the new encrypted bounce page on success; an ERR_PTR() on failure
171 */
172struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
173 unsigned int len,
174 unsigned int offs,
175 gfp_t gfp_flags)
176
177{
178 const struct inode *inode = page->mapping->host;
179 const unsigned int blockbits = inode->i_blkbits;
180 const unsigned int blocksize = 1 << blockbits;
181 struct page *ciphertext_page;
182 u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
183 (offs >> blockbits);
184 unsigned int i;
185 int err;
186
187 if (WARN_ON_ONCE(!PageLocked(page)))
188 return ERR_PTR(-EINVAL);
189
190 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
191 return ERR_PTR(-EINVAL);
192
193 ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
194 if (!ciphertext_page)
195 return ERR_PTR(-ENOMEM);
196
197 for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
198 err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num,
199 page, ciphertext_page,
200 blocksize, i, gfp_flags);
201 if (err) {
202 fscrypt_free_bounce_page(ciphertext_page);
203 return ERR_PTR(err);
204 }
205 }
206 SetPagePrivate(ciphertext_page);
207 set_page_private(ciphertext_page, (unsigned long)page);
208 return ciphertext_page;
209}
210EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks);
211
212/**
213 * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
214 * @inode: The inode to which this block belongs
215 * @page: The page containing the block to encrypt
216 * @len: Size of block to encrypt. This must be a multiple of
217 * FSCRYPT_CONTENTS_ALIGNMENT.
218 * @offs: Byte offset within @page at which the block to encrypt begins
219 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
220 * number of the block within the file
221 * @gfp_flags: Memory allocation flags
222 *
223 * Encrypt a possibly-compressed filesystem block that is located in an
224 * arbitrary page, not necessarily in the original pagecache page. The @inode
225 * and @lblk_num must be specified, as they can't be determined from @page.
226 *
227 * Return: 0 on success; -errno on failure
228 */
229int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
230 unsigned int len, unsigned int offs,
231 u64 lblk_num, gfp_t gfp_flags)
232{
233 return fscrypt_crypt_block(inode, FS_ENCRYPT, lblk_num, page, page,
234 len, offs, gfp_flags);
235}
236EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
237
238/**
239 * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a
240 * pagecache page
241 * @page: The locked pagecache page containing the block(s) to decrypt
242 * @len: Total size of the block(s) to decrypt. Must be a nonzero
243 * multiple of the filesystem's block size.
244 * @offs: Byte offset within @page of the first block to decrypt. Must be
245 * a multiple of the filesystem's block size.
246 *
247 * The specified block(s) are decrypted in-place within the pagecache page,
248 * which must still be locked and not uptodate. Normally, blocksize ==
249 * PAGE_SIZE and the whole page is decrypted at once.
250 *
251 * This is for use by the filesystem's ->readahead() method.
252 *
253 * Return: 0 on success; -errno on failure
254 */
255int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
256 unsigned int offs)
257{
258 const struct inode *inode = page->mapping->host;
259 const unsigned int blockbits = inode->i_blkbits;
260 const unsigned int blocksize = 1 << blockbits;
261 u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
262 (offs >> blockbits);
263 unsigned int i;
264 int err;
265
266 if (WARN_ON_ONCE(!PageLocked(page)))
267 return -EINVAL;
268
269 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
270 return -EINVAL;
271
272 for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
273 err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page,
274 page, blocksize, i, GFP_NOFS);
275 if (err)
276 return err;
277 }
278 return 0;
279}
280EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
281
282/**
283 * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
284 * @inode: The inode to which this block belongs
285 * @page: The page containing the block to decrypt
286 * @len: Size of block to decrypt. This must be a multiple of
287 * FSCRYPT_CONTENTS_ALIGNMENT.
288 * @offs: Byte offset within @page at which the block to decrypt begins
289 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
290 * number of the block within the file
291 *
292 * Decrypt a possibly-compressed filesystem block that is located in an
293 * arbitrary page, not necessarily in the original pagecache page. The @inode
294 * and @lblk_num must be specified, as they can't be determined from @page.
295 *
296 * Return: 0 on success; -errno on failure
297 */
298int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
299 unsigned int len, unsigned int offs,
300 u64 lblk_num)
301{
302 return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
303 len, offs, GFP_NOFS);
304}
305EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
306
307/**
308 * fscrypt_initialize() - allocate major buffers for fs encryption.
309 * @cop_flags: fscrypt operations flags
310 *
311 * We only call this when we start accessing encrypted files, since it
312 * results in memory getting allocated that wouldn't otherwise be used.
313 *
314 * Return: 0 on success; -errno on failure
315 */
316int fscrypt_initialize(unsigned int cop_flags)
317{
318 int err = 0;
319
320 /* No need to allocate a bounce page pool if this FS won't use it. */
321 if (cop_flags & FS_CFLG_OWN_PAGES)
322 return 0;
323
324 mutex_lock(&fscrypt_init_mutex);
325 if (fscrypt_bounce_page_pool)
326 goto out_unlock;
327
328 err = -ENOMEM;
329 fscrypt_bounce_page_pool =
330 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
331 if (!fscrypt_bounce_page_pool)
332 goto out_unlock;
333
334 err = 0;
335out_unlock:
336 mutex_unlock(&fscrypt_init_mutex);
337 return err;
338}
339
340void fscrypt_msg(const struct inode *inode, const char *level,
341 const char *fmt, ...)
342{
343 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
344 DEFAULT_RATELIMIT_BURST);
345 struct va_format vaf;
346 va_list args;
347
348 if (!__ratelimit(&rs))
349 return;
350
351 va_start(args, fmt);
352 vaf.fmt = fmt;
353 vaf.va = &args;
354 if (inode && inode->i_ino)
355 printk("%sfscrypt (%s, inode %lu): %pV\n",
356 level, inode->i_sb->s_id, inode->i_ino, &vaf);
357 else if (inode)
358 printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf);
359 else
360 printk("%sfscrypt: %pV\n", level, &vaf);
361 va_end(args);
362}
363
364/**
365 * fscrypt_init() - Set up for fs encryption.
366 *
367 * Return: 0 on success; -errno on failure
368 */
369static int __init fscrypt_init(void)
370{
371 int err = -ENOMEM;
372
373 /*
374 * Use an unbound workqueue to allow bios to be decrypted in parallel
375 * even when they happen to complete on the same CPU. This sacrifices
376 * locality, but it's worthwhile since decryption is CPU-intensive.
377 *
378 * Also use a high-priority workqueue to prioritize decryption work,
379 * which blocks reads from completing, over regular application tasks.
380 */
381 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
382 WQ_UNBOUND | WQ_HIGHPRI,
383 num_online_cpus());
384 if (!fscrypt_read_workqueue)
385 goto fail;
386
387 fscrypt_info_cachep = KMEM_CACHE(fscrypt_info, SLAB_RECLAIM_ACCOUNT);
388 if (!fscrypt_info_cachep)
389 goto fail_free_queue;
390
391 err = fscrypt_init_keyring();
392 if (err)
393 goto fail_free_info;
394
395 return 0;
396
397fail_free_info:
398 kmem_cache_destroy(fscrypt_info_cachep);
399fail_free_queue:
400 destroy_workqueue(fscrypt_read_workqueue);
401fail:
402 return err;
403}
404late_initcall(fscrypt_init)