linux/fs/crypto/bio.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Utility functions for file contents encryption/decryption on
 * block device-based filesystems.
 *
 * Copyright (C) 2015, Google, Inc.
 * Copyright (C) 2015, Motorola Mobility
 */

#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/bio.h>
#include <linux/namei.h>
#include "fscrypt_private.h"

/**
 * fscrypt_decrypt_bio() - decrypt the contents of a bio
 * @bio: the bio to decrypt
 *
 * Decrypt the contents of a "read" bio following successful completion of the
 * underlying disk read.  The bio must be reading a whole number of blocks of an
 * encrypted file directly into the page cache.  If the bio is reading the
 * ciphertext into bounce pages instead of the page cache (for example, because
 * the file is also compressed, so decompression is required after decryption),
 * then this function isn't applicable.  This function may sleep, so it must be
 * called from a workqueue rather than from the bio's bi_end_io callback.
 *
 * Return: %true on success; %false on failure.  On failure, bio->bi_status is
 *	   also set to an error status.
 */
bool fscrypt_decrypt_bio(struct bio *bio)
{ … }
EXPORT_SYMBOL(…);

static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
					      pgoff_t lblk, sector_t pblk,
					      unsigned int len)
{ … }

/**
 * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file
 * @inode: the file's inode
 * @lblk: the first file logical block to zero out
 * @pblk: the first filesystem physical block to zero out
 * @len: number of blocks to zero out
 *
 * Zero out filesystem blocks in an encrypted regular file on-disk, i.e. write
 * ciphertext blocks which decrypt to the all-zeroes block.  The blocks must be
 * both logically and physically contiguous.  It's also assumed that the
 * filesystem only uses a single block device, ->s_bdev.
 *
 * Note that since each block uses a different IV, this involves writing a
 * different ciphertext to each block; we can't simply reuse the same one.
 *
 * Return: 0 on success; -errno on failure.
 */
int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
			  sector_t pblk, unsigned int len)
{ … }
EXPORT_SYMBOL(…);