| rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame] | 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 | static void __fscrypt_decrypt_bio(struct bio *bio, bool done) |
| 30 | { |
| 31 | struct bio_vec *bv; |
| 32 | int i; |
| 33 | |
| 34 | bio_for_each_segment_all(bv, bio, i) { |
| 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 | WARN_ON_ONCE(1); |
| 41 | SetPageError(page); |
| 42 | } else if (done) { |
| 43 | SetPageUptodate(page); |
| 44 | } |
| 45 | if (done) |
| 46 | unlock_page(page); |
| 47 | } |
| 48 | } |
| 49 | |
| 50 | void fscrypt_decrypt_bio(struct bio *bio) |
| 51 | { |
| 52 | __fscrypt_decrypt_bio(bio, false); |
| 53 | } |
| 54 | EXPORT_SYMBOL(fscrypt_decrypt_bio); |
| 55 | |
| 56 | static void completion_pages(struct work_struct *work) |
| 57 | { |
| 58 | struct fscrypt_ctx *ctx = |
| 59 | container_of(work, struct fscrypt_ctx, r.work); |
| 60 | struct bio *bio = ctx->r.bio; |
| 61 | |
| 62 | __fscrypt_decrypt_bio(bio, true); |
| 63 | fscrypt_release_ctx(ctx); |
| 64 | bio_put(bio); |
| 65 | } |
| 66 | |
| 67 | void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio) |
| 68 | { |
| 69 | INIT_WORK(&ctx->r.work, completion_pages); |
| 70 | ctx->r.bio = bio; |
| 71 | fscrypt_enqueue_decrypt_work(&ctx->r.work); |
| 72 | } |
| 73 | EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio); |
| 74 | |
| 75 | void fscrypt_pullback_bio_page(struct page **page, bool restore) |
| 76 | { |
| 77 | struct fscrypt_ctx *ctx; |
| 78 | struct page *bounce_page; |
| 79 | |
| 80 | /* The bounce data pages are unmapped. */ |
| 81 | if ((*page)->mapping) |
| 82 | return; |
| 83 | |
| 84 | /* The bounce data page is unmapped. */ |
| 85 | bounce_page = *page; |
| 86 | ctx = (struct fscrypt_ctx *)page_private(bounce_page); |
| 87 | |
| 88 | /* restore control page */ |
| 89 | *page = ctx->w.control_page; |
| 90 | |
| 91 | if (restore) |
| 92 | fscrypt_restore_control_page(bounce_page); |
| 93 | } |
| 94 | EXPORT_SYMBOL(fscrypt_pullback_bio_page); |
| 95 | |
| 96 | int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, |
| 97 | sector_t pblk, unsigned int len) |
| 98 | { |
| 99 | struct fscrypt_ctx *ctx; |
| 100 | struct page *ciphertext_page = NULL; |
| 101 | struct bio *bio; |
| 102 | int ret, err = 0; |
| 103 | |
| 104 | BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE); |
| 105 | |
| 106 | ctx = fscrypt_get_ctx(inode, GFP_NOFS); |
| 107 | if (IS_ERR(ctx)) |
| 108 | return PTR_ERR(ctx); |
| 109 | |
| 110 | ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT); |
| 111 | if (IS_ERR(ciphertext_page)) { |
| 112 | err = PTR_ERR(ciphertext_page); |
| 113 | goto errout; |
| 114 | } |
| 115 | |
| 116 | while (len--) { |
| 117 | err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk, |
| 118 | ZERO_PAGE(0), ciphertext_page, |
| 119 | PAGE_SIZE, 0, GFP_NOFS); |
| 120 | if (err) |
| 121 | goto errout; |
| 122 | |
| 123 | bio = bio_alloc(GFP_NOWAIT, 1); |
| 124 | if (!bio) { |
| 125 | err = -ENOMEM; |
| 126 | goto errout; |
| 127 | } |
| 128 | bio_set_dev(bio, inode->i_sb->s_bdev); |
| 129 | bio->bi_iter.bi_sector = |
| 130 | pblk << (inode->i_sb->s_blocksize_bits - 9); |
| 131 | bio_set_op_attrs(bio, REQ_OP_WRITE, 0); |
| 132 | ret = bio_add_page(bio, ciphertext_page, |
| 133 | inode->i_sb->s_blocksize, 0); |
| 134 | if (ret != inode->i_sb->s_blocksize) { |
| 135 | /* should never happen! */ |
| 136 | WARN_ON(1); |
| 137 | bio_put(bio); |
| 138 | err = -EIO; |
| 139 | goto errout; |
| 140 | } |
| 141 | err = submit_bio_wait(bio); |
| 142 | if (err == 0 && bio->bi_status) |
| 143 | err = -EIO; |
| 144 | bio_put(bio); |
| 145 | if (err) |
| 146 | goto errout; |
| 147 | lblk++; |
| 148 | pblk++; |
| 149 | } |
| 150 | err = 0; |
| 151 | errout: |
| 152 | fscrypt_release_ctx(ctx); |
| 153 | return err; |
| 154 | } |
| 155 | EXPORT_SYMBOL(fscrypt_zeroout_range); |