Commit 5fee3609 authored by Satya Tangirala's avatar Satya Tangirala Committed by Eric Biggers
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fscrypt: add inline encryption support 



Add support for inline encryption to fs/crypto/.  With "inline
encryption", the block layer handles the decryption/encryption as part
of the bio, instead of the filesystem doing the crypto itself via
Linux's crypto API. This model is needed in order to take advantage of
the inline encryption hardware present on most modern mobile SoCs.

To use inline encryption, the filesystem needs to be mounted with
'-o inlinecrypt'. Blk-crypto will then be used instead of the traditional
filesystem-layer crypto whenever possible to encrypt the contents
of any encrypted files in that filesystem. Fscrypt still provides the key
and IV to use, and the actual ciphertext on-disk is still the same;
therefore it's testable using the existing fscrypt ciphertext verification
tests.

Note that since blk-crypto has a fallback to Linux's crypto API, and
also supports all the encryption modes currently supported by fscrypt,
this feature is usable and testable even without actual inline
encryption hardware.

Per-filesystem changes will be needed to set encryption contexts when
submitting bios and to implement the 'inlinecrypt' mount option.  This
patch just adds the common code.

Signed-off-by: default avatarSatya Tangirala <satyat@google.com>
Reviewed-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
Reviewed-by: default avatarEric Biggers <ebiggers@google.com>
Reviewed-by: default avatarTheodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20200702015607.1215430-3-satyat@google.com


Co-developed-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
parent 457e7a13

Documentation/filesystems/fscrypt.rst

+3 −0
Original line number Diff line number Diff line
@@ -1255,6 +1255,7 @@ f2fs encryption using `kvm-xfstests 
<https://github.com/tytso/xfstests-bld/blob/master/Documentation/kvm-quickstart.md>`_::



    kvm-xfstests -c ext4,f2fs -g encrypt

    kvm-xfstests -c ext4,f2fs -g encrypt -m inlinecrypt



UBIFS encryption can also be tested this way, but it should be done in

a separate command, and it takes some time for kvm-xfstests to set up
@@ -1276,6 +1277,7 @@ This tests the encrypted I/O paths more thoroughly. To do this with 
kvm-xfstests, use the "encrypt" filesystem configuration::



    kvm-xfstests -c ext4/encrypt,f2fs/encrypt -g auto

    kvm-xfstests -c ext4/encrypt,f2fs/encrypt -g auto -m inlinecrypt



Because this runs many more tests than "-g encrypt" does, it takes

much longer to run; so also consider using `gce-xfstests
@@ -1283,3 +1285,4 @@ much longer to run; so also consider using `gce-xfstests 
instead of kvm-xfstests::



    gce-xfstests -c ext4/encrypt,f2fs/encrypt -g auto

    gce-xfstests -c ext4/encrypt,f2fs/encrypt -g auto -m inlinecrypt

fs/crypto/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -24,3 +24,9 @@ config FS_ENCRYPTION_ALGS 
	select CRYPTO_SHA256

	select CRYPTO_SHA512

	select CRYPTO_XTS



config FS_ENCRYPTION_INLINE_CRYPT

	bool "Enable fscrypt to use inline crypto"

	depends on FS_ENCRYPTION && BLK_INLINE_ENCRYPTION

	help

	  Enable fscrypt to use inline encryption hardware if available.

fs/crypto/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -11,3 +11,4 @@ fscrypto-y := crypto.o \ 
	      policy.o



fscrypto-$(CONFIG_BLOCK) += bio.o

fscrypto-$(CONFIG_FS_ENCRYPTION_INLINE_CRYPT) += inline_crypt.o

fs/crypto/bio.c

+51 −0
Original line number Diff line number Diff line
@@ -41,6 +41,53 @@ void fscrypt_decrypt_bio(struct bio *bio) 
}

EXPORT_SYMBOL(fscrypt_decrypt_bio);



static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,

					      pgoff_t lblk, sector_t pblk,

					      unsigned int len)

{

	const unsigned int blockbits = inode->i_blkbits;

	const unsigned int blocks_per_page = 1 << (PAGE_SHIFT - blockbits);

	struct bio *bio;

	int ret, err = 0;

	int num_pages = 0;



	/* This always succeeds since __GFP_DIRECT_RECLAIM is set. */

	bio = bio_alloc(GFP_NOFS, BIO_MAX_PAGES);



	while (len) {

		unsigned int blocks_this_page = min(len, blocks_per_page);

		unsigned int bytes_this_page = blocks_this_page << blockbits;



		if (num_pages == 0) {

			fscrypt_set_bio_crypt_ctx(bio, inode, lblk, GFP_NOFS);

			bio_set_dev(bio, inode->i_sb->s_bdev);

			bio->bi_iter.bi_sector =

					pblk << (blockbits - SECTOR_SHIFT);

			bio_set_op_attrs(bio, REQ_OP_WRITE, 0);

		}

		ret = bio_add_page(bio, ZERO_PAGE(0), bytes_this_page, 0);

		if (WARN_ON(ret != bytes_this_page)) {

			err = -EIO;

			goto out;

		}

		num_pages++;

		len -= blocks_this_page;

		lblk += blocks_this_page;

		pblk += blocks_this_page;

		if (num_pages == BIO_MAX_PAGES || !len ||

		    !fscrypt_mergeable_bio(bio, inode, lblk)) {

			err = submit_bio_wait(bio);

			if (err)

				goto out;

			bio_reset(bio);

			num_pages = 0;

		}

	}

out:

	bio_put(bio);

	return err;

}



/**

 * fscrypt_zeroout_range() - zero out a range of blocks in an encrypted file

 * @inode: the file's inode
@@ -75,6 +122,10 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk, 
	if (len == 0)

		return 0;



	if (fscrypt_inode_uses_inline_crypto(inode))

		return fscrypt_zeroout_range_inline_crypt(inode, lblk, pblk,

							  len);



	BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_PAGES);

	nr_pages = min_t(unsigned int, ARRAY_SIZE(pages),

			 (len + blocks_per_page - 1) >> blocks_per_page_bits);

fs/crypto/crypto.c

+1 −1
Original line number Diff line number Diff line
@@ -100,7 +100,7 @@ int fscrypt_crypt_block(const struct inode *inode, fscrypt_direction_t rw, 
	DECLARE_CRYPTO_WAIT(wait);

	struct scatterlist dst, src;

	struct fscrypt_info *ci = inode->i_crypt_info;

	struct crypto_skcipher *tfm = ci->ci_ctfm;

	struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;

	int res = 0;



	if (WARN_ON_ONCE(len <= 0))

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