fs/crypto/bio.c

   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_pagecache_blocks(page, bv->bv_len,
  37                                                            bv->bv_offset);
  38                 if (ret)
  39                         SetPageError(page);
  40                 else if (done)
  41                         SetPageUptodate(page);
  42                 if (done)
  43                         unlock_page(page);
  44         }
  45 }
  46
  47 void fscrypt_decrypt_bio(struct bio *bio)
  48 {
  49         __fscrypt_decrypt_bio(bio, false);
  50 }
  51 EXPORT_SYMBOL(fscrypt_decrypt_bio);
  52
  53 static void completion_pages(struct work_struct *work)
  54 {
  55         struct fscrypt_ctx *ctx = container_of(work, struct fscrypt_ctx, work);
  56         struct bio *bio = ctx->bio;
  57
  58         __fscrypt_decrypt_bio(bio, true);
  59         fscrypt_release_ctx(ctx);
  60         bio_put(bio);
  61 }
  62
  63 void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio)
  64 {
  65         INIT_WORK(&ctx->work, completion_pages);
  66         ctx->bio = bio;
  67         fscrypt_enqueue_decrypt_work(&ctx->work);
  68 }
  69 EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
  70
  71 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
  72                                 sector_t pblk, unsigned int len)
  73 {
  74         const unsigned int blockbits = inode->i_blkbits;
  75         const unsigned int blocksize = 1 << blockbits;
  76         struct page *ciphertext_page;
  77         struct bio *bio;
  78         int ret, err = 0;
  79
  80         ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT);
  81         if (!ciphertext_page)
  82                 return -ENOMEM;
  83
  84         while (len--) {
  85                 err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
  86                                           ZERO_PAGE(0), ciphertext_page,
  87                                           blocksize, 0, GFP_NOFS);
  88                 if (err)
  89                         goto errout;
  90
  91                 bio = bio_alloc(GFP_NOWAIT, 1);
  92                 if (!bio) {
  93                         err = -ENOMEM;
  94                         goto errout;
  95                 }
  96                 bio_set_dev(bio, inode->i_sb->s_bdev);
  97                 bio->bi_iter.bi_sector = pblk << (blockbits - 9);
  98                 bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
  99                 ret = bio_add_page(bio, ciphertext_page, blocksize, 0);
 100                 if (WARN_ON(ret != blocksize)) {
 101                         /* should never happen! */
 102                         bio_put(bio);
 103                         err = -EIO;
 104                         goto errout;
 105                 }
 106                 err = submit_bio_wait(bio);
 107                 if (err == 0 && bio->bi_status)
 108                         err = -EIO;
 109                 bio_put(bio);
 110                 if (err)
 111                         goto errout;
 112                 lblk++;
 113                 pblk++;
 114         }
 115         err = 0;
 116 errout:
 117         fscrypt_free_bounce_page(ciphertext_page);
 118         return err;
 119 }
 120 EXPORT_SYMBOL(fscrypt_zeroout_range);