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 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 48 void fscrypt_decrypt_bio(struct bio *bio) 49 { 50 __fscrypt_decrypt_bio(bio, false); 51 } 52 EXPORT_SYMBOL(fscrypt_decrypt_bio); 53 54 static 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 65 void 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 } 71 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio); 72 73 void 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 } 92 EXPORT_SYMBOL(fscrypt_pullback_bio_page); 93 94 int 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; 149 errout: 150 fscrypt_release_ctx(ctx); 151 return err; 152 } 153 EXPORT_SYMBOL(fscrypt_zeroout_range); 154