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1 | // SPDX-License-Identifier: GPL-2.0 | |
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/module.h> | |
25 | #include <linux/bio.h> | |
26 | #include <linux/namei.h> | |
27 | #include "fscrypt_private.h" | |
28 | ||
29 | /* | |
30 | * Call fscrypt_decrypt_page on every single page, reusing the encryption | |
31 | * context. | |
32 | */ | |
33 | static void completion_pages(struct work_struct *work) | |
34 | { | |
35 | struct fscrypt_ctx *ctx = | |
36 | container_of(work, struct fscrypt_ctx, r.work); | |
37 | struct bio *bio = ctx->r.bio; | |
38 | struct bio_vec *bv; | |
39 | int i; | |
40 | ||
41 | bio_for_each_segment_all(bv, bio, i) { | |
42 | struct page *page = bv->bv_page; | |
43 | int ret = fscrypt_decrypt_page(page->mapping->host, page, | |
44 | PAGE_SIZE, 0, page->index); | |
45 | ||
46 | if (ret) { | |
47 | WARN_ON_ONCE(1); | |
48 | SetPageError(page); | |
49 | } else { | |
50 | SetPageUptodate(page); | |
51 | } | |
52 | unlock_page(page); | |
53 | } | |
54 | fscrypt_release_ctx(ctx); | |
55 | bio_put(bio); | |
56 | } | |
57 | ||
58 | void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio) | |
59 | { | |
60 | INIT_WORK(&ctx->r.work, completion_pages); | |
61 | ctx->r.bio = bio; | |
62 | queue_work(fscrypt_read_workqueue, &ctx->r.work); | |
63 | } | |
64 | EXPORT_SYMBOL(fscrypt_decrypt_bio_pages); | |
65 | ||
66 | void fscrypt_pullback_bio_page(struct page **page, bool restore) | |
67 | { | |
68 | struct fscrypt_ctx *ctx; | |
69 | struct page *bounce_page; | |
70 | ||
71 | /* The bounce data pages are unmapped. */ | |
72 | if ((*page)->mapping) | |
73 | return; | |
74 | ||
75 | /* The bounce data page is unmapped. */ | |
76 | bounce_page = *page; | |
77 | ctx = (struct fscrypt_ctx *)page_private(bounce_page); | |
78 | ||
79 | /* restore control page */ | |
80 | *page = ctx->w.control_page; | |
81 | ||
82 | if (restore) | |
83 | fscrypt_restore_control_page(bounce_page); | |
84 | } | |
85 | EXPORT_SYMBOL(fscrypt_pullback_bio_page); | |
86 | ||
87 | int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, | |
88 | sector_t pblk, unsigned int len) | |
89 | { | |
90 | struct fscrypt_ctx *ctx; | |
91 | struct page *ciphertext_page = NULL; | |
92 | struct bio *bio; | |
93 | int ret, err = 0; | |
94 | ||
95 | BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE); | |
96 | ||
97 | ctx = fscrypt_get_ctx(inode, GFP_NOFS); | |
98 | if (IS_ERR(ctx)) | |
99 | return PTR_ERR(ctx); | |
100 | ||
101 | ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT); | |
102 | if (IS_ERR(ciphertext_page)) { | |
103 | err = PTR_ERR(ciphertext_page); | |
104 | goto errout; | |
105 | } | |
106 | ||
107 | while (len--) { | |
108 | err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk, | |
109 | ZERO_PAGE(0), ciphertext_page, | |
110 | PAGE_SIZE, 0, GFP_NOFS); | |
111 | if (err) | |
112 | goto errout; | |
113 | ||
114 | bio = bio_alloc(GFP_NOWAIT, 1); | |
115 | if (!bio) { | |
116 | err = -ENOMEM; | |
117 | goto errout; | |
118 | } | |
119 | bio_set_dev(bio, inode->i_sb->s_bdev); | |
120 | bio->bi_iter.bi_sector = | |
121 | pblk << (inode->i_sb->s_blocksize_bits - 9); | |
122 | bio_set_op_attrs(bio, REQ_OP_WRITE, 0); | |
123 | ret = bio_add_page(bio, ciphertext_page, | |
124 | inode->i_sb->s_blocksize, 0); | |
125 | if (ret != inode->i_sb->s_blocksize) { | |
126 | /* should never happen! */ | |
127 | WARN_ON(1); | |
128 | bio_put(bio); | |
129 | err = -EIO; | |
130 | goto errout; | |
131 | } | |
132 | err = submit_bio_wait(bio); | |
133 | if (err == 0 && bio->bi_status) | |
134 | err = -EIO; | |
135 | bio_put(bio); | |
136 | if (err) | |
137 | goto errout; | |
138 | lblk++; | |
139 | pblk++; | |
140 | } | |
141 | err = 0; | |
142 | errout: | |
143 | fscrypt_release_ctx(ctx); | |
144 | return err; | |
145 | } | |
146 | EXPORT_SYMBOL(fscrypt_zeroout_range); |