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-rw-r--r--fs/ext4/crypto.c536
1 files changed, 0 insertions, 536 deletions
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
deleted file mode 100644
index 6a6c27373b54..000000000000
--- a/fs/ext4/crypto.c
+++ /dev/null
@@ -1,536 +0,0 @@
1/*
2 * linux/fs/ext4/crypto.c
3 *
4 * Copyright (C) 2015, Google, Inc.
5 *
6 * This contains encryption functions for ext4
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 *
15 * This has not yet undergone a rigorous security audit.
16 *
17 * The usage of AES-XTS should conform to recommendations in NIST
18 * Special Publication 800-38E and IEEE P1619/D16.
19 */
20
21#include <crypto/skcipher.h>
22#include <keys/user-type.h>
23#include <keys/encrypted-type.h>
24#include <linux/ecryptfs.h>
25#include <linux/gfp.h>
26#include <linux/kernel.h>
27#include <linux/key.h>
28#include <linux/list.h>
29#include <linux/mempool.h>
30#include <linux/module.h>
31#include <linux/mutex.h>
32#include <linux/random.h>
33#include <linux/scatterlist.h>
34#include <linux/spinlock_types.h>
35#include <linux/namei.h>
36
37#include "ext4_extents.h"
38#include "xattr.h"
39
40/* Encryption added and removed here! (L: */
41
42static unsigned int num_prealloc_crypto_pages = 32;
43static unsigned int num_prealloc_crypto_ctxs = 128;
44
45module_param(num_prealloc_crypto_pages, uint, 0444);
46MODULE_PARM_DESC(num_prealloc_crypto_pages,
47 "Number of crypto pages to preallocate");
48module_param(num_prealloc_crypto_ctxs, uint, 0444);
49MODULE_PARM_DESC(num_prealloc_crypto_ctxs,
50 "Number of crypto contexts to preallocate");
51
52static mempool_t *ext4_bounce_page_pool;
53
54static LIST_HEAD(ext4_free_crypto_ctxs);
55static DEFINE_SPINLOCK(ext4_crypto_ctx_lock);
56
57static struct kmem_cache *ext4_crypto_ctx_cachep;
58struct kmem_cache *ext4_crypt_info_cachep;
59
60/**
61 * ext4_release_crypto_ctx() - Releases an encryption context
62 * @ctx: The encryption context to release.
63 *
64 * If the encryption context was allocated from the pre-allocated pool, returns
65 * it to that pool. Else, frees it.
66 *
67 * If there's a bounce page in the context, this frees that.
68 */
69void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx)
70{
71 unsigned long flags;
72
73 if (ctx->flags & EXT4_WRITE_PATH_FL && ctx->w.bounce_page)
74 mempool_free(ctx->w.bounce_page, ext4_bounce_page_pool);
75 ctx->w.bounce_page = NULL;
76 ctx->w.control_page = NULL;
77 if (ctx->flags & EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL) {
78 kmem_cache_free(ext4_crypto_ctx_cachep, ctx);
79 } else {
80 spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
81 list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
82 spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
83 }
84}
85
86/**
87 * ext4_get_crypto_ctx() - Gets an encryption context
88 * @inode: The inode for which we are doing the crypto
89 *
90 * Allocates and initializes an encryption context.
91 *
92 * Return: An allocated and initialized encryption context on success; error
93 * value or NULL otherwise.
94 */
95struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,
96 gfp_t gfp_flags)
97{
98 struct ext4_crypto_ctx *ctx = NULL;
99 int res = 0;
100 unsigned long flags;
101 struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
102
103 if (ci == NULL)
104 return ERR_PTR(-ENOKEY);
105
106 /*
107 * We first try getting the ctx from a free list because in
108 * the common case the ctx will have an allocated and
109 * initialized crypto tfm, so it's probably a worthwhile
110 * optimization. For the bounce page, we first try getting it
111 * from the kernel allocator because that's just about as fast
112 * as getting it from a list and because a cache of free pages
113 * should generally be a "last resort" option for a filesystem
114 * to be able to do its job.
115 */
116 spin_lock_irqsave(&ext4_crypto_ctx_lock, flags);
117 ctx = list_first_entry_or_null(&ext4_free_crypto_ctxs,
118 struct ext4_crypto_ctx, free_list);
119 if (ctx)
120 list_del(&ctx->free_list);
121 spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);
122 if (!ctx) {
123 ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);
124 if (!ctx) {
125 res = -ENOMEM;
126 goto out;
127 }
128 ctx->flags |= EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
129 } else {
130 ctx->flags &= ~EXT4_CTX_REQUIRES_FREE_ENCRYPT_FL;
131 }
132 ctx->flags &= ~EXT4_WRITE_PATH_FL;
133
134out:
135 if (res) {
136 if (!IS_ERR_OR_NULL(ctx))
137 ext4_release_crypto_ctx(ctx);
138 ctx = ERR_PTR(res);
139 }
140 return ctx;
141}
142
143struct workqueue_struct *ext4_read_workqueue;
144static DEFINE_MUTEX(crypto_init);
145
146/**
147 * ext4_exit_crypto() - Shutdown the ext4 encryption system
148 */
149void ext4_exit_crypto(void)
150{
151 struct ext4_crypto_ctx *pos, *n;
152
153 list_for_each_entry_safe(pos, n, &ext4_free_crypto_ctxs, free_list)
154 kmem_cache_free(ext4_crypto_ctx_cachep, pos);
155 INIT_LIST_HEAD(&ext4_free_crypto_ctxs);
156 if (ext4_bounce_page_pool)
157 mempool_destroy(ext4_bounce_page_pool);
158 ext4_bounce_page_pool = NULL;
159 if (ext4_read_workqueue)
160 destroy_workqueue(ext4_read_workqueue);
161 ext4_read_workqueue = NULL;
162 if (ext4_crypto_ctx_cachep)
163 kmem_cache_destroy(ext4_crypto_ctx_cachep);
164 ext4_crypto_ctx_cachep = NULL;
165 if (ext4_crypt_info_cachep)
166 kmem_cache_destroy(ext4_crypt_info_cachep);
167 ext4_crypt_info_cachep = NULL;
168}
169
170/**
171 * ext4_init_crypto() - Set up for ext4 encryption.
172 *
173 * We only call this when we start accessing encrypted files, since it
174 * results in memory getting allocated that wouldn't otherwise be used.
175 *
176 * Return: Zero on success, non-zero otherwise.
177 */
178int ext4_init_crypto(void)
179{
180 int i, res = -ENOMEM;
181
182 mutex_lock(&crypto_init);
183 if (ext4_read_workqueue)
184 goto already_initialized;
185 ext4_read_workqueue = alloc_workqueue("ext4_crypto", WQ_HIGHPRI, 0);
186 if (!ext4_read_workqueue)
187 goto fail;
188
189 ext4_crypto_ctx_cachep = KMEM_CACHE(ext4_crypto_ctx,
190 SLAB_RECLAIM_ACCOUNT);
191 if (!ext4_crypto_ctx_cachep)
192 goto fail;
193
194 ext4_crypt_info_cachep = KMEM_CACHE(ext4_crypt_info,
195 SLAB_RECLAIM_ACCOUNT);
196 if (!ext4_crypt_info_cachep)
197 goto fail;
198
199 for (i = 0; i < num_prealloc_crypto_ctxs; i++) {
200 struct ext4_crypto_ctx *ctx;
201
202 ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);
203 if (!ctx) {
204 res = -ENOMEM;
205 goto fail;
206 }
207 list_add(&ctx->free_list, &ext4_free_crypto_ctxs);
208 }
209
210 ext4_bounce_page_pool =
211 mempool_create_page_pool(num_prealloc_crypto_pages, 0);
212 if (!ext4_bounce_page_pool) {
213 res = -ENOMEM;
214 goto fail;
215 }
216already_initialized:
217 mutex_unlock(&crypto_init);
218 return 0;
219fail:
220 ext4_exit_crypto();
221 mutex_unlock(&crypto_init);
222 return res;
223}
224
225void ext4_restore_control_page(struct page *data_page)
226{
227 struct ext4_crypto_ctx *ctx =
228 (struct ext4_crypto_ctx *)page_private(data_page);
229
230 set_page_private(data_page, (unsigned long)NULL);
231 ClearPagePrivate(data_page);
232 unlock_page(data_page);
233 ext4_release_crypto_ctx(ctx);
234}
235
236/**
237 * ext4_crypt_complete() - The completion callback for page encryption
238 * @req: The asynchronous encryption request context
239 * @res: The result of the encryption operation
240 */
241static void ext4_crypt_complete(struct crypto_async_request *req, int res)
242{
243 struct ext4_completion_result *ecr = req->data;
244
245 if (res == -EINPROGRESS)
246 return;
247 ecr->res = res;
248 complete(&ecr->completion);
249}
250
251typedef enum {
252 EXT4_DECRYPT = 0,
253 EXT4_ENCRYPT,
254} ext4_direction_t;
255
256static int ext4_page_crypto(struct inode *inode,
257 ext4_direction_t rw,
258 pgoff_t index,
259 struct page *src_page,
260 struct page *dest_page,
261 gfp_t gfp_flags)
262
263{
264 u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
265 struct skcipher_request *req = NULL;
266 DECLARE_EXT4_COMPLETION_RESULT(ecr);
267 struct scatterlist dst, src;
268 struct ext4_crypt_info *ci = EXT4_I(inode)->i_crypt_info;
269 struct crypto_skcipher *tfm = ci->ci_ctfm;
270 int res = 0;
271
272 req = skcipher_request_alloc(tfm, gfp_flags);
273 if (!req) {
274 printk_ratelimited(KERN_ERR
275 "%s: crypto_request_alloc() failed\n",
276 __func__);
277 return -ENOMEM;
278 }
279 skcipher_request_set_callback(
280 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
281 ext4_crypt_complete, &ecr);
282
283 BUILD_BUG_ON(EXT4_XTS_TWEAK_SIZE < sizeof(index));
284 memcpy(xts_tweak, &index, sizeof(index));
285 memset(&xts_tweak[sizeof(index)], 0,
286 EXT4_XTS_TWEAK_SIZE - sizeof(index));
287
288 sg_init_table(&dst, 1);
289 sg_set_page(&dst, dest_page, PAGE_SIZE, 0);
290 sg_init_table(&src, 1);
291 sg_set_page(&src, src_page, PAGE_SIZE, 0);
292 skcipher_request_set_crypt(req, &src, &dst, PAGE_SIZE,
293 xts_tweak);
294 if (rw == EXT4_DECRYPT)
295 res = crypto_skcipher_decrypt(req);
296 else
297 res = crypto_skcipher_encrypt(req);
298 if (res == -EINPROGRESS || res == -EBUSY) {
299 wait_for_completion(&ecr.completion);
300 res = ecr.res;
301 }
302 skcipher_request_free(req);
303 if (res) {
304 printk_ratelimited(
305 KERN_ERR
306 "%s: crypto_skcipher_encrypt() returned %d\n",
307 __func__, res);
308 return res;
309 }
310 return 0;
311}
312
313static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx,
314 gfp_t gfp_flags)
315{
316 ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);
317 if (ctx->w.bounce_page == NULL)
318 return ERR_PTR(-ENOMEM);
319 ctx->flags |= EXT4_WRITE_PATH_FL;
320 return ctx->w.bounce_page;
321}
322
323/**
324 * ext4_encrypt() - Encrypts a page
325 * @inode: The inode for which the encryption should take place
326 * @plaintext_page: The page to encrypt. Must be locked.
327 *
328 * Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
329 * encryption context.
330 *
331 * Called on the page write path. The caller must call
332 * ext4_restore_control_page() on the returned ciphertext page to
333 * release the bounce buffer and the encryption context.
334 *
335 * Return: An allocated page with the encrypted content on success. Else, an
336 * error value or NULL.
337 */
338struct page *ext4_encrypt(struct inode *inode,
339 struct page *plaintext_page,
340 gfp_t gfp_flags)
341{
342 struct ext4_crypto_ctx *ctx;
343 struct page *ciphertext_page = NULL;
344 int err;
345
346 BUG_ON(!PageLocked(plaintext_page));
347
348 ctx = ext4_get_crypto_ctx(inode, gfp_flags);
349 if (IS_ERR(ctx))
350 return (struct page *) ctx;
351
352 /* The encryption operation will require a bounce page. */
353 ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
354 if (IS_ERR(ciphertext_page))
355 goto errout;
356 ctx->w.control_page = plaintext_page;
357 err = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,
358 plaintext_page, ciphertext_page, gfp_flags);
359 if (err) {
360 ciphertext_page = ERR_PTR(err);
361 errout:
362 ext4_release_crypto_ctx(ctx);
363 return ciphertext_page;
364 }
365 SetPagePrivate(ciphertext_page);
366 set_page_private(ciphertext_page, (unsigned long)ctx);
367 lock_page(ciphertext_page);
368 return ciphertext_page;
369}
370
371/**
372 * ext4_decrypt() - Decrypts a page in-place
373 * @ctx: The encryption context.
374 * @page: The page to decrypt. Must be locked.
375 *
376 * Decrypts page in-place using the ctx encryption context.
377 *
378 * Called from the read completion callback.
379 *
380 * Return: Zero on success, non-zero otherwise.
381 */
382int ext4_decrypt(struct page *page)
383{
384 BUG_ON(!PageLocked(page));
385
386 return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,
387 page->index, page, page, GFP_NOFS);
388}
389
390int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,
391 ext4_fsblk_t pblk, ext4_lblk_t len)
392{
393 struct ext4_crypto_ctx *ctx;
394 struct page *ciphertext_page = NULL;
395 struct bio *bio;
396 int ret, err = 0;
397
398#if 0
399 ext4_msg(inode->i_sb, KERN_CRIT,
400 "ext4_encrypted_zeroout ino %lu lblk %u len %u",
401 (unsigned long) inode->i_ino, lblk, len);
402#endif
403
404 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
405
406 ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);
407 if (IS_ERR(ctx))
408 return PTR_ERR(ctx);
409
410 ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
411 if (IS_ERR(ciphertext_page)) {
412 err = PTR_ERR(ciphertext_page);
413 goto errout;
414 }
415
416 while (len--) {
417 err = ext4_page_crypto(inode, EXT4_ENCRYPT, lblk,
418 ZERO_PAGE(0), ciphertext_page,
419 GFP_NOFS);
420 if (err)
421 goto errout;
422
423 bio = bio_alloc(GFP_NOWAIT, 1);
424 if (!bio) {
425 err = -ENOMEM;
426 goto errout;
427 }
428 bio->bi_bdev = inode->i_sb->s_bdev;
429 bio->bi_iter.bi_sector =
430 pblk << (inode->i_sb->s_blocksize_bits - 9);
431 ret = bio_add_page(bio, ciphertext_page,
432 inode->i_sb->s_blocksize, 0);
433 if (ret != inode->i_sb->s_blocksize) {
434 /* should never happen! */
435 ext4_msg(inode->i_sb, KERN_ERR,
436 "bio_add_page failed: %d", ret);
437 WARN_ON(1);
438 bio_put(bio);
439 err = -EIO;
440 goto errout;
441 }
442 err = submit_bio_wait(WRITE, bio);
443 if ((err == 0) && bio->bi_error)
444 err = -EIO;
445 bio_put(bio);
446 if (err)
447 goto errout;
448 lblk++; pblk++;
449 }
450 err = 0;
451errout:
452 ext4_release_crypto_ctx(ctx);
453 return err;
454}
455
456bool ext4_valid_contents_enc_mode(uint32_t mode)
457{
458 return (mode == EXT4_ENCRYPTION_MODE_AES_256_XTS);
459}
460
461/**
462 * ext4_validate_encryption_key_size() - Validate the encryption key size
463 * @mode: The key mode.
464 * @size: The key size to validate.
465 *
466 * Return: The validated key size for @mode. Zero if invalid.
467 */
468uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size)
469{
470 if (size == ext4_encryption_key_size(mode))
471 return size;
472 return 0;
473}
474
475/*
476 * Validate dentries for encrypted directories to make sure we aren't
477 * potentially caching stale data after a key has been added or
478 * removed.
479 */
480static int ext4_d_revalidate(struct dentry *dentry, unsigned int flags)
481{
482 struct dentry *dir;
483 struct ext4_crypt_info *ci;
484 int dir_has_key, cached_with_key;
485
486 if (flags & LOOKUP_RCU)
487 return -ECHILD;
488
489 dir = dget_parent(dentry);
490 if (!ext4_encrypted_inode(d_inode(dir))) {
491 dput(dir);
492 return 0;
493 }
494 ci = EXT4_I(d_inode(dir))->i_crypt_info;
495 if (ci && ci->ci_keyring_key &&
496 (ci->ci_keyring_key->flags & ((1 << KEY_FLAG_INVALIDATED) |
497 (1 << KEY_FLAG_REVOKED) |
498 (1 << KEY_FLAG_DEAD))))
499 ci = NULL;
500
501 /* this should eventually be an flag in d_flags */
502 cached_with_key = dentry->d_fsdata != NULL;
503 dir_has_key = (ci != NULL);
504 dput(dir);
505
506 /*
507 * If the dentry was cached without the key, and it is a
508 * negative dentry, it might be a valid name. We can't check
509 * if the key has since been made available due to locking
510 * reasons, so we fail the validation so ext4_lookup() can do
511 * this check.
512 *
513 * We also fail the validation if the dentry was created with
514 * the key present, but we no longer have the key, or vice versa.
515 */
516 if ((!cached_with_key && d_is_negative(dentry)) ||
517 (!cached_with_key && dir_has_key) ||
518 (cached_with_key && !dir_has_key)) {
519#if 0 /* Revalidation debug */
520 char buf[80];
521 char *cp = simple_dname(dentry, buf, sizeof(buf));
522
523 if (IS_ERR(cp))
524 cp = (char *) "???";
525 pr_err("revalidate: %s %p %d %d %d\n", cp, dentry->d_fsdata,
526 cached_with_key, d_is_negative(dentry),
527 dir_has_key);
528#endif
529 return 0;
530 }
531 return 1;
532}
533
534const struct dentry_operations ext4_encrypted_d_ops = {
535 .d_revalidate = ext4_d_revalidate,
536};
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