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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_inode_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 if (WARN_ON_ONCE(!fscrypt_bounce_page_pool)) {
53 /*
54 * Oops, the filesystem called a function that uses the bounce
55 * page pool, but it didn't set needs_bounce_pages.
56 */
57 return NULL;
58 }
59 return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
60}
61
62/**
63 * fscrypt_free_bounce_page() - free a ciphertext bounce page
64 * @bounce_page: the bounce page to free, or NULL
65 *
66 * Free a bounce page that was allocated by fscrypt_encrypt_pagecache_blocks(),
67 * or by fscrypt_alloc_bounce_page() directly.
68 */
69void fscrypt_free_bounce_page(struct page *bounce_page)
70{
71 if (!bounce_page)
72 return;
73 set_page_private(bounce_page, (unsigned long)NULL);
74 ClearPagePrivate(bounce_page);
75 mempool_free(bounce_page, fscrypt_bounce_page_pool);
76}
77EXPORT_SYMBOL(fscrypt_free_bounce_page);
78
79/*
80 * Generate the IV for the given data unit index within the given file.
81 * For filenames encryption, index == 0.
82 *
83 * Keep this in sync with fscrypt_limit_io_blocks(). fscrypt_limit_io_blocks()
84 * needs to know about any IV generation methods where the low bits of IV don't
85 * simply contain the data unit index (e.g., IV_INO_LBLK_32).
86 */
87void fscrypt_generate_iv(union fscrypt_iv *iv, u64 index,
88 const struct fscrypt_inode_info *ci)
89{
90 u8 flags = fscrypt_policy_flags(&ci->ci_policy);
91
92 memset(iv, 0, ci->ci_mode->ivsize);
93
94 if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) {
95 WARN_ON_ONCE(index > U32_MAX);
96 WARN_ON_ONCE(ci->ci_inode->i_ino > U32_MAX);
97 index |= (u64)ci->ci_inode->i_ino << 32;
98 } else if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) {
99 WARN_ON_ONCE(index > U32_MAX);
100 index = (u32)(ci->ci_hashed_ino + index);
101 } else if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) {
102 memcpy(iv->nonce, ci->ci_nonce, FSCRYPT_FILE_NONCE_SIZE);
103 }
104 iv->index = cpu_to_le64(index);
105}
106
107/* Encrypt or decrypt a single "data unit" of file contents. */
108int fscrypt_crypt_data_unit(const struct fscrypt_inode_info *ci,
109 fscrypt_direction_t rw, u64 index,
110 struct page *src_page, struct page *dest_page,
111 unsigned int len, unsigned int offs,
112 gfp_t gfp_flags)
113{
114 union fscrypt_iv iv;
115 struct skcipher_request *req = NULL;
116 DECLARE_CRYPTO_WAIT(wait);
117 struct scatterlist dst, src;
118 struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
119 int res = 0;
120
121 if (WARN_ON_ONCE(len <= 0))
122 return -EINVAL;
123 if (WARN_ON_ONCE(len % FSCRYPT_CONTENTS_ALIGNMENT != 0))
124 return -EINVAL;
125
126 fscrypt_generate_iv(&iv, index, ci);
127
128 req = skcipher_request_alloc(tfm, gfp_flags);
129 if (!req)
130 return -ENOMEM;
131
132 skcipher_request_set_callback(
133 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
134 crypto_req_done, &wait);
135
136 sg_init_table(&dst, 1);
137 sg_set_page(&dst, dest_page, len, offs);
138 sg_init_table(&src, 1);
139 sg_set_page(&src, src_page, len, offs);
140 skcipher_request_set_crypt(req, &src, &dst, len, &iv);
141 if (rw == FS_DECRYPT)
142 res = crypto_wait_req(crypto_skcipher_decrypt(req), &wait);
143 else
144 res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
145 skcipher_request_free(req);
146 if (res) {
147 fscrypt_err(ci->ci_inode,
148 "%scryption failed for data unit %llu: %d",
149 (rw == FS_DECRYPT ? "De" : "En"), index, res);
150 return res;
151 }
152 return 0;
153}
154
155/**
156 * fscrypt_encrypt_pagecache_blocks() - Encrypt data from a pagecache page
157 * @page: the locked pagecache page containing the data to encrypt
158 * @len: size of the data to encrypt, in bytes
159 * @offs: offset within @page of the data to encrypt, in bytes
160 * @gfp_flags: memory allocation flags; see details below
161 *
162 * This allocates a new bounce page and encrypts the given data into it. The
163 * length and offset of the data must be aligned to the file's crypto data unit
164 * size. Alignment to the filesystem block size fulfills this requirement, as
165 * the filesystem block size is always a multiple of the data unit size.
166 *
167 * In the bounce page, the ciphertext data will be located at the same offset at
168 * which the plaintext data was located in the source page. Any other parts of
169 * the bounce page will be left uninitialized.
170 *
171 * This is for use by the filesystem's ->writepages() method.
172 *
173 * The bounce page allocation is mempool-backed, so it will always succeed when
174 * @gfp_flags includes __GFP_DIRECT_RECLAIM, e.g. when it's GFP_NOFS. However,
175 * only the first page of each bio can be allocated this way. To prevent
176 * deadlocks, for any additional pages a mask like GFP_NOWAIT must be used.
177 *
178 * Return: the new encrypted bounce page on success; an ERR_PTR() on failure
179 */
180struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
181 unsigned int len,
182 unsigned int offs,
183 gfp_t gfp_flags)
184
185{
186 const struct inode *inode = page->mapping->host;
187 const struct fscrypt_inode_info *ci = inode->i_crypt_info;
188 const unsigned int du_bits = ci->ci_data_unit_bits;
189 const unsigned int du_size = 1U << du_bits;
190 struct page *ciphertext_page;
191 u64 index = ((u64)page->index << (PAGE_SHIFT - du_bits)) +
192 (offs >> du_bits);
193 unsigned int i;
194 int err;
195
196 if (WARN_ON_ONCE(!PageLocked(page)))
197 return ERR_PTR(-EINVAL);
198
199 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, du_size)))
200 return ERR_PTR(-EINVAL);
201
202 ciphertext_page = fscrypt_alloc_bounce_page(gfp_flags);
203 if (!ciphertext_page)
204 return ERR_PTR(-ENOMEM);
205
206 for (i = offs; i < offs + len; i += du_size, index++) {
207 err = fscrypt_crypt_data_unit(ci, FS_ENCRYPT, index,
208 page, ciphertext_page,
209 du_size, i, gfp_flags);
210 if (err) {
211 fscrypt_free_bounce_page(ciphertext_page);
212 return ERR_PTR(err);
213 }
214 }
215 SetPagePrivate(ciphertext_page);
216 set_page_private(ciphertext_page, (unsigned long)page);
217 return ciphertext_page;
218}
219EXPORT_SYMBOL(fscrypt_encrypt_pagecache_blocks);
220
221/**
222 * fscrypt_encrypt_block_inplace() - Encrypt a filesystem block in-place
223 * @inode: The inode to which this block belongs
224 * @page: The page containing the block to encrypt
225 * @len: Size of block to encrypt. This must be a multiple of
226 * FSCRYPT_CONTENTS_ALIGNMENT.
227 * @offs: Byte offset within @page at which the block to encrypt begins
228 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
229 * number of the block within the file
230 * @gfp_flags: Memory allocation flags
231 *
232 * Encrypt a possibly-compressed filesystem block that is located in an
233 * arbitrary page, not necessarily in the original pagecache page. The @inode
234 * and @lblk_num must be specified, as they can't be determined from @page.
235 *
236 * This is not compatible with fscrypt_operations::supports_subblock_data_units.
237 *
238 * Return: 0 on success; -errno on failure
239 */
240int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
241 unsigned int len, unsigned int offs,
242 u64 lblk_num, gfp_t gfp_flags)
243{
244 if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
245 return -EOPNOTSUPP;
246 return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_ENCRYPT,
247 lblk_num, page, page, len, offs,
248 gfp_flags);
249}
250EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
251
252/**
253 * fscrypt_decrypt_pagecache_blocks() - Decrypt data from a pagecache folio
254 * @folio: the pagecache folio containing the data to decrypt
255 * @len: size of the data to decrypt, in bytes
256 * @offs: offset within @folio of the data to decrypt, in bytes
257 *
258 * Decrypt data that has just been read from an encrypted file. The data must
259 * be located in a pagecache folio that is still locked and not yet uptodate.
260 * The length and offset of the data must be aligned to the file's crypto data
261 * unit size. Alignment to the filesystem block size fulfills this requirement,
262 * as the filesystem block size is always a multiple of the data unit size.
263 *
264 * Return: 0 on success; -errno on failure
265 */
266int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
267 size_t offs)
268{
269 const struct inode *inode = folio->mapping->host;
270 const struct fscrypt_inode_info *ci = inode->i_crypt_info;
271 const unsigned int du_bits = ci->ci_data_unit_bits;
272 const unsigned int du_size = 1U << du_bits;
273 u64 index = ((u64)folio->index << (PAGE_SHIFT - du_bits)) +
274 (offs >> du_bits);
275 size_t i;
276 int err;
277
278 if (WARN_ON_ONCE(!folio_test_locked(folio)))
279 return -EINVAL;
280
281 if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, du_size)))
282 return -EINVAL;
283
284 for (i = offs; i < offs + len; i += du_size, index++) {
285 struct page *page = folio_page(folio, i >> PAGE_SHIFT);
286
287 err = fscrypt_crypt_data_unit(ci, FS_DECRYPT, index, page,
288 page, du_size, i & ~PAGE_MASK,
289 GFP_NOFS);
290 if (err)
291 return err;
292 }
293 return 0;
294}
295EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
296
297/**
298 * fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place
299 * @inode: The inode to which this block belongs
300 * @page: The page containing the block to decrypt
301 * @len: Size of block to decrypt. This must be a multiple of
302 * FSCRYPT_CONTENTS_ALIGNMENT.
303 * @offs: Byte offset within @page at which the block to decrypt begins
304 * @lblk_num: Filesystem logical block number of the block, i.e. the 0-based
305 * number of the block within the file
306 *
307 * Decrypt a possibly-compressed filesystem block that is located in an
308 * arbitrary page, not necessarily in the original pagecache page. The @inode
309 * and @lblk_num must be specified, as they can't be determined from @page.
310 *
311 * This is not compatible with fscrypt_operations::supports_subblock_data_units.
312 *
313 * Return: 0 on success; -errno on failure
314 */
315int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
316 unsigned int len, unsigned int offs,
317 u64 lblk_num)
318{
319 if (WARN_ON_ONCE(inode->i_sb->s_cop->supports_subblock_data_units))
320 return -EOPNOTSUPP;
321 return fscrypt_crypt_data_unit(inode->i_crypt_info, FS_DECRYPT,
322 lblk_num, page, page, len, offs,
323 GFP_NOFS);
324}
325EXPORT_SYMBOL(fscrypt_decrypt_block_inplace);
326
327/**
328 * fscrypt_initialize() - allocate major buffers for fs encryption.
329 * @sb: the filesystem superblock
330 *
331 * We only call this when we start accessing encrypted files, since it
332 * results in memory getting allocated that wouldn't otherwise be used.
333 *
334 * Return: 0 on success; -errno on failure
335 */
336int fscrypt_initialize(struct super_block *sb)
337{
338 int err = 0;
339 mempool_t *pool;
340
341 /* pairs with smp_store_release() below */
342 if (likely(smp_load_acquire(&fscrypt_bounce_page_pool)))
343 return 0;
344
345 /* No need to allocate a bounce page pool if this FS won't use it. */
346 if (!sb->s_cop->needs_bounce_pages)
347 return 0;
348
349 mutex_lock(&fscrypt_init_mutex);
350 if (fscrypt_bounce_page_pool)
351 goto out_unlock;
352
353 err = -ENOMEM;
354 pool = mempool_create_page_pool(num_prealloc_crypto_pages, 0);
355 if (!pool)
356 goto out_unlock;
357 /* pairs with smp_load_acquire() above */
358 smp_store_release(&fscrypt_bounce_page_pool, pool);
359 err = 0;
360out_unlock:
361 mutex_unlock(&fscrypt_init_mutex);
362 return err;
363}
364
365void fscrypt_msg(const struct inode *inode, const char *level,
366 const char *fmt, ...)
367{
368 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
369 DEFAULT_RATELIMIT_BURST);
370 struct va_format vaf;
371 va_list args;
372
373 if (!__ratelimit(&rs))
374 return;
375
376 va_start(args, fmt);
377 vaf.fmt = fmt;
378 vaf.va = &args;
379 if (inode && inode->i_ino)
380 printk("%sfscrypt (%s, inode %lu): %pV\n",
381 level, inode->i_sb->s_id, inode->i_ino, &vaf);
382 else if (inode)
383 printk("%sfscrypt (%s): %pV\n", level, inode->i_sb->s_id, &vaf);
384 else
385 printk("%sfscrypt: %pV\n", level, &vaf);
386 va_end(args);
387}
388
389/**
390 * fscrypt_init() - Set up for fs encryption.
391 *
392 * Return: 0 on success; -errno on failure
393 */
394static int __init fscrypt_init(void)
395{
396 int err = -ENOMEM;
397
398 /*
399 * Use an unbound workqueue to allow bios to be decrypted in parallel
400 * even when they happen to complete on the same CPU. This sacrifices
401 * locality, but it's worthwhile since decryption is CPU-intensive.
402 *
403 * Also use a high-priority workqueue to prioritize decryption work,
404 * which blocks reads from completing, over regular application tasks.
405 */
406 fscrypt_read_workqueue = alloc_workqueue("fscrypt_read_queue",
407 WQ_UNBOUND | WQ_HIGHPRI,
408 num_online_cpus());
409 if (!fscrypt_read_workqueue)
410 goto fail;
411
412 fscrypt_inode_info_cachep = KMEM_CACHE(fscrypt_inode_info,
413 SLAB_RECLAIM_ACCOUNT);
414 if (!fscrypt_inode_info_cachep)
415 goto fail_free_queue;
416
417 err = fscrypt_init_keyring();
418 if (err)
419 goto fail_free_inode_info;
420
421 return 0;
422
423fail_free_inode_info:
424 kmem_cache_destroy(fscrypt_inode_info_cachep);
425fail_free_queue:
426 destroy_workqueue(fscrypt_read_workqueue);
427fail:
428 return err;
429}
430late_initcall(fscrypt_init)