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Linux kernel mirror (for testing)
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linux
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
29static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
30{
31 struct bio_vec *bv;
32 struct bvec_iter_all iter_all;
33
34 bio_for_each_segment_all(bv, bio, iter_all) {
35 struct page *page = bv->bv_page;
36 int ret = fscrypt_decrypt_page(page->mapping->host, page,
37 PAGE_SIZE, 0, page->index);
38
39 if (ret)
40 SetPageError(page);
41 else if (done)
42 SetPageUptodate(page);
43 if (done)
44 unlock_page(page);
45 }
46}
47
48void fscrypt_decrypt_bio(struct bio *bio)
49{
50 __fscrypt_decrypt_bio(bio, false);
51}
52EXPORT_SYMBOL(fscrypt_decrypt_bio);
53
54static void completion_pages(struct work_struct *work)
55{
56 struct fscrypt_ctx *ctx =
57 container_of(work, struct fscrypt_ctx, r.work);
58 struct bio *bio = ctx->r.bio;
59
60 __fscrypt_decrypt_bio(bio, true);
61 fscrypt_release_ctx(ctx);
62 bio_put(bio);
63}
64
65void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio)
66{
67 INIT_WORK(&ctx->r.work, completion_pages);
68 ctx->r.bio = bio;
69 fscrypt_enqueue_decrypt_work(&ctx->r.work);
70}
71EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
72
73void fscrypt_pullback_bio_page(struct page **page, bool restore)
74{
75 struct fscrypt_ctx *ctx;
76 struct page *bounce_page;
77
78 /* The bounce data pages are unmapped. */
79 if ((*page)->mapping)
80 return;
81
82 /* The bounce data page is unmapped. */
83 bounce_page = *page;
84 ctx = (struct fscrypt_ctx *)page_private(bounce_page);
85
86 /* restore control page */
87 *page = ctx->w.control_page;
88
89 if (restore)
90 fscrypt_restore_control_page(bounce_page);
91}
92EXPORT_SYMBOL(fscrypt_pullback_bio_page);
93
94int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
95 sector_t pblk, unsigned int len)
96{
97 struct fscrypt_ctx *ctx;
98 struct page *ciphertext_page = NULL;
99 struct bio *bio;
100 int ret, err = 0;
101
102 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
103
104 ctx = fscrypt_get_ctx(GFP_NOFS);
105 if (IS_ERR(ctx))
106 return PTR_ERR(ctx);
107
108 ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
109 if (IS_ERR(ciphertext_page)) {
110 err = PTR_ERR(ciphertext_page);
111 goto errout;
112 }
113
114 while (len--) {
115 err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
116 ZERO_PAGE(0), ciphertext_page,
117 PAGE_SIZE, 0, GFP_NOFS);
118 if (err)
119 goto errout;
120
121 bio = bio_alloc(GFP_NOWAIT, 1);
122 if (!bio) {
123 err = -ENOMEM;
124 goto errout;
125 }
126 bio_set_dev(bio, inode->i_sb->s_bdev);
127 bio->bi_iter.bi_sector =
128 pblk << (inode->i_sb->s_blocksize_bits - 9);
129 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
130 ret = bio_add_page(bio, ciphertext_page,
131 inode->i_sb->s_blocksize, 0);
132 if (ret != inode->i_sb->s_blocksize) {
133 /* should never happen! */
134 WARN_ON(1);
135 bio_put(bio);
136 err = -EIO;
137 goto errout;
138 }
139 err = submit_bio_wait(bio);
140 if (err == 0 && bio->bi_status)
141 err = -EIO;
142 bio_put(bio);
143 if (err)
144 goto errout;
145 lblk++;
146 pblk++;
147 }
148 err = 0;
149errout:
150 fscrypt_release_ctx(ctx);
151 return err;
152}
153EXPORT_SYMBOL(fscrypt_zeroout_range);