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https://github.com/torvalds/linux
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d2d0727b16
Currently, bounce page handling for writes to encrypted files is unnecessarily complicated. A fscrypt_ctx is allocated along with each bounce page, page_private(bounce_page) points to this fscrypt_ctx, and fscrypt_ctx::w::control_page points to the original pagecache page. However, because writes don't use the fscrypt_ctx for anything else, there's no reason why page_private(bounce_page) can't just point to the original pagecache page directly. Therefore, this patch makes this change. In the process, it also cleans up the API exposed to filesystems that allows testing whether a page is a bounce page, getting the pagecache page from a bounce page, and freeing a bounce page. Reviewed-by: Chandan Rajendra <chandan@linux.ibm.com> Signed-off-by: Eric Biggers <ebiggers@google.com>
126 lines
2.9 KiB
C
126 lines
2.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This contains encryption functions for per-file encryption.
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*
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* Copyright (C) 2015, Google, Inc.
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* Copyright (C) 2015, Motorola Mobility
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*
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* Written by Michael Halcrow, 2014.
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*
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* Filename encryption additions
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* Uday Savagaonkar, 2014
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* Encryption policy handling additions
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* Ildar Muslukhov, 2014
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* Add fscrypt_pullback_bio_page()
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* Jaegeuk Kim, 2015.
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*
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* This has not yet undergone a rigorous security audit.
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*
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* The usage of AES-XTS should conform to recommendations in NIST
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* Special Publication 800-38E and IEEE P1619/D16.
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*/
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#include <linux/pagemap.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/namei.h>
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#include "fscrypt_private.h"
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static void __fscrypt_decrypt_bio(struct bio *bio, bool done)
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{
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struct bio_vec *bv;
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struct bvec_iter_all iter_all;
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bio_for_each_segment_all(bv, bio, iter_all) {
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struct page *page = bv->bv_page;
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int ret = fscrypt_decrypt_page(page->mapping->host, page,
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PAGE_SIZE, 0, page->index);
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if (ret)
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SetPageError(page);
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else if (done)
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SetPageUptodate(page);
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if (done)
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unlock_page(page);
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}
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}
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void fscrypt_decrypt_bio(struct bio *bio)
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{
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__fscrypt_decrypt_bio(bio, false);
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}
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EXPORT_SYMBOL(fscrypt_decrypt_bio);
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static void completion_pages(struct work_struct *work)
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{
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struct fscrypt_ctx *ctx =
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container_of(work, struct fscrypt_ctx, r.work);
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struct bio *bio = ctx->r.bio;
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__fscrypt_decrypt_bio(bio, true);
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fscrypt_release_ctx(ctx);
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bio_put(bio);
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}
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void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx, struct bio *bio)
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{
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INIT_WORK(&ctx->r.work, completion_pages);
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ctx->r.bio = bio;
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fscrypt_enqueue_decrypt_work(&ctx->r.work);
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}
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EXPORT_SYMBOL(fscrypt_enqueue_decrypt_bio);
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int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
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sector_t pblk, unsigned int len)
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{
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struct page *ciphertext_page;
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struct bio *bio;
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int ret, err = 0;
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BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);
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ciphertext_page = fscrypt_alloc_bounce_page(GFP_NOWAIT);
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if (!ciphertext_page)
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return -ENOMEM;
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while (len--) {
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err = fscrypt_do_page_crypto(inode, FS_ENCRYPT, lblk,
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ZERO_PAGE(0), ciphertext_page,
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PAGE_SIZE, 0, GFP_NOFS);
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if (err)
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goto errout;
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bio = bio_alloc(GFP_NOWAIT, 1);
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if (!bio) {
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err = -ENOMEM;
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goto errout;
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}
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bio_set_dev(bio, inode->i_sb->s_bdev);
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bio->bi_iter.bi_sector =
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pblk << (inode->i_sb->s_blocksize_bits - 9);
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bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
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ret = bio_add_page(bio, ciphertext_page,
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inode->i_sb->s_blocksize, 0);
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if (ret != inode->i_sb->s_blocksize) {
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/* should never happen! */
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WARN_ON(1);
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bio_put(bio);
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err = -EIO;
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goto errout;
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}
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err = submit_bio_wait(bio);
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if (err == 0 && bio->bi_status)
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err = -EIO;
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bio_put(bio);
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if (err)
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goto errout;
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lblk++;
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pblk++;
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}
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err = 0;
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errout:
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fscrypt_free_bounce_page(ciphertext_page);
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return err;
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}
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EXPORT_SYMBOL(fscrypt_zeroout_range);
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