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![Eric Biggers](/assets/img/avatar_default.png)
Currently, fscrypt provides fscrypt_decrypt_bio_pages() which decrypts a bio's pages asynchronously, then unlocks them afterwards. But, this assumes that decryption is the last "postprocessing step" for the bio, so it's incompatible with additional postprocessing steps such as authenticity verification after decryption. Therefore, rename the existing fscrypt_decrypt_bio_pages() to fscrypt_enqueue_decrypt_bio(). Then, add fscrypt_decrypt_bio() which decrypts the pages in the bio synchronously without unlocking the pages, nor setting them Uptodate; and add fscrypt_enqueue_decrypt_work(), which enqueues work on the fscrypt_read_workqueue. The new functions will be used by filesystems that support both fscrypt and fs-verity. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
155 lines
3.5 KiB
C
155 lines
3.5 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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int i;
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bio_for_each_segment_all(bv, bio, i) {
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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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WARN_ON_ONCE(1);
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SetPageError(page);
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} else if (done) {
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SetPageUptodate(page);
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}
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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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void fscrypt_pullback_bio_page(struct page **page, bool restore)
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{
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struct fscrypt_ctx *ctx;
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struct page *bounce_page;
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/* The bounce data pages are unmapped. */
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if ((*page)->mapping)
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return;
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/* The bounce data page is unmapped. */
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bounce_page = *page;
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ctx = (struct fscrypt_ctx *)page_private(bounce_page);
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/* restore control page */
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*page = ctx->w.control_page;
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if (restore)
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fscrypt_restore_control_page(bounce_page);
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}
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EXPORT_SYMBOL(fscrypt_pullback_bio_page);
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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 fscrypt_ctx *ctx;
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struct page *ciphertext_page = NULL;
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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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ctx = fscrypt_get_ctx(inode, GFP_NOFS);
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if (IS_ERR(ctx))
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return PTR_ERR(ctx);
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ciphertext_page = fscrypt_alloc_bounce_page(ctx, GFP_NOWAIT);
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if (IS_ERR(ciphertext_page)) {
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err = PTR_ERR(ciphertext_page);
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goto errout;
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}
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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_release_ctx(ctx);
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return err;
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}
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EXPORT_SYMBOL(fscrypt_zeroout_range);
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