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); 156