2 * This contains encryption functions for per-file encryption.
4 * Copyright (C) 2015, Google, Inc.
5 * Copyright (C) 2015, Motorola Mobility
7 * Written by Michael Halcrow, 2014.
9 * Filename encryption additions
10 * Uday Savagaonkar, 2014
11 * Encryption policy handling additions
12 * Ildar Muslukhov, 2014
13 * Add fscrypt_pullback_bio_page()
16 * This has not yet undergone a rigorous security audit.
18 * The usage of AES-XTS should conform to recommendations in NIST
19 * Special Publication 800-38E and IEEE P1619/D16.
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"
29 * Call fscrypt_decrypt_page on every single page, reusing the encryption
32 static void completion_pages(struct work_struct *work)
34 struct fscrypt_ctx *ctx =
35 container_of(work, struct fscrypt_ctx, r.work);
36 struct bio *bio = ctx->r.bio;
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);
49 SetPageUptodate(page);
53 fscrypt_release_ctx(ctx);
57 void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
59 INIT_WORK(&ctx->r.work, completion_pages);
61 queue_work(fscrypt_read_workqueue, &ctx->r.work);
63 EXPORT_SYMBOL(fscrypt_decrypt_bio_pages);
65 void fscrypt_pullback_bio_page(struct page **page, bool restore)
67 struct fscrypt_ctx *ctx;
68 struct page *bounce_page;
70 /* The bounce data pages are unmapped. */
74 /* The bounce data page is unmapped. */
76 ctx = (struct fscrypt_ctx *)page_private(bounce_page);
78 /* restore control page */
79 *page = ctx->w.control_page;
82 fscrypt_restore_control_page(bounce_page);
84 EXPORT_SYMBOL(fscrypt_pullback_bio_page);
86 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
87 sector_t pblk, unsigned int len)
89 struct fscrypt_ctx *ctx;
90 struct page *ciphertext_page = NULL;
94 BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
96 ctx = fscrypt_get_ctx(inode, GFP_NOFS);
100 ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
101 if (IS_ERR(ciphertext_page)) {
102 err = PTR_ERR(ciphertext_page);
107 err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
108 ZERO_PAGE(0), ciphertext_page,
109 PAGE_SIZE, 0, GFP_NOFS);
113 bio = bio_alloc(GFP_NOWAIT, 1);
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! */
131 err = submit_bio_wait(bio);
132 if ((err == 0) && bio->bi_error)
142 fscrypt_release_ctx(ctx);
145 EXPORT_SYMBOL(fscrypt_zeroout_range);