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gerrit-public.fairphone.software / kernel / msm-4.19 / 5612ac83b9d7a32a7f2967d9f6f97e7f3428dfd2 / . / fs / crypto / bio.c
blob: a409a84f1bcab289d676bfd1a2c9e0c39e14c1ad [file] [log] [blame]
Richard Weinberger58ae7462016-12-19 12:25:32 +0100[diff] [blame]1/*
2 * This contains encryption functions for per-file encryption.
3 *
4 * Copyright (C) 2015, Google, Inc.
5 * Copyright (C) 2015, Motorola Mobility
6 *
7 * Written by Michael Halcrow, 2014.
8 *
9 * Filename encryption additions
10 * Uday Savagaonkar, 2014
11 * Encryption policy handling additions
12 * Ildar Muslukhov, 2014
13 * Add fscrypt_pullback_bio_page()
14 * Jaegeuk Kim, 2015.
15 *
16 * This has not yet undergone a rigorous security audit.
17 *
18 * The usage of AES-XTS should conform to recommendations in NIST
19 * Special Publication 800-38E and IEEE P1619/D16.
20 */
21
22#include <linux/pagemap.h>
23#include <linux/module.h>
24#include <linux/bio.h>
25#include <linux/namei.h>
26#include "fscrypt_private.h"
27
28/*
29 * Call fscrypt_decrypt_page on every single page, reusing the encryption
30 * context.
31 */
32static void completion_pages(struct work_struct *work)
33{
34 struct fscrypt_ctx *ctx =
35 container_of(work, struct fscrypt_ctx, r.work);
36 struct bio *bio = ctx->r.bio;
37 struct bio_vec *bv;
38 int i;
39
40 bio_for_each_segment_all(bv, bio, i) {
41 struct page *page = bv->bv_page;
42 int ret = fscrypt_decrypt_page(page->mapping->host, page,
43 PAGE_SIZE, 0, page->index);
44
45 if (ret) {
46 WARN_ON_ONCE(1);
47 SetPageError(page);
48 } else {
49 SetPageUptodate(page);
50 }
51 unlock_page(page);
52 }
53 fscrypt_release_ctx(ctx);
54 bio_put(bio);
55}
56
57void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
58{
59 INIT_WORK(&ctx->r.work, completion_pages);
60 ctx->r.bio = bio;
61 queue_work(fscrypt_read_workqueue, &ctx->r.work);
62}
63EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
64
65void fscrypt_pullback_bio_page(struct page **page, bool restore)
66{
67 struct fscrypt_ctx *ctx;
68 struct page *bounce_page;
69
70 /* The bounce data pages are unmapped. */
71 if ((*page)->mapping)
72 return;
73
74 /* The bounce data page is unmapped. */
75 bounce_page = *page;
76 ctx = (struct fscrypt_ctx *)page_private(bounce_page);
77
78 /* restore control page */
79 *page = ctx->w.control_page;
80
81 if (restore)
82 fscrypt_restore_control_page(bounce_page);
83}
84EXPORT_SYMBOL(fscrypt_pullback_bio_page);
85
86int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
87 sector_t pblk, unsigned int len)
88{
89 struct fscrypt_ctx *ctx;
90 struct page *ciphertext_page = NULL;
91 struct bio *bio;
92 int ret, err = 0;
93
94 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
95
96 ctx = fscrypt_get_ctx(inode, GFP_NOFS);
97 if (IS_ERR(ctx))
98 return PTR_ERR(ctx);
99
100 ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
101 if (IS_ERR(ciphertext_page)) {
102 err = PTR_ERR(ciphertext_page);
103 goto errout;
104 }
105
106 while (len--) {
107 err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
108 ZERO_PAGE(0), ciphertext_page,
109 PAGE_SIZE, 0, GFP_NOFS);
110 if (err)
111 goto errout;
112
113 bio = bio_alloc(GFP_NOWAIT, 1);
114 if (!bio) {
115 err = -ENOMEM;
116 goto errout;
117 }
118 bio->bi_bdev = inode->i_sb->s_bdev;
119 bio->bi_iter.bi_sector =
120 pblk << (inode->i_sb->s_blocksize_bits - 9);
121 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
122 ret = bio_add_page(bio, ciphertext_page,
123 inode->i_sb->s_blocksize, 0);
124 if (ret != inode->i_sb->s_blocksize) {
125 /* should never happen! */
126 WARN_ON(1);
127 bio_put(bio);
128 err = -EIO;
129 goto errout;
130 }
131 err = submit_bio_wait(bio);
132 if ((err == 0) && bio->bi_error)
133 err = -EIO;
134 bio_put(bio);
135 if (err)
136 goto errout;
137 lblk++;
138 pblk++;
139 }
140 err = 0;
141errout:
142 fscrypt_release_ctx(ctx);
143 return err;
144}
145EXPORT_SYMBOL(fscrypt_zeroout_range);