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Commit ffa39380 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Mike Snitzer
Browse files

dm verity: factor out structures and functions useful to separate object 



Prepare for an optional verity object to make use of existing dm-verity
structures and functions.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 03045cba

drivers/md/dm-verity-target.c

+16 −100
Original line number Diff line number Diff line
@@ -14,12 +14,10 @@ 
 * access behavior.

 */



#include "dm-bufio.h"

#include "dm-verity.h"



#include <linux/module.h>

#include <linux/device-mapper.h>

#include <linux/reboot.h>

#include <crypto/hash.h>



#define DM_MSG_PREFIX			"verity"
@@ -28,7 +26,6 @@ 


#define DM_VERITY_DEFAULT_PREFETCH_SIZE	262144



#define DM_VERITY_MAX_LEVELS		63

#define DM_VERITY_MAX_CORRUPTED_ERRS	100



#define DM_VERITY_OPT_LOGGING		"ignore_corruption"
@@ -40,72 +37,6 @@ static unsigned dm_verity_prefetch_cluster = DM_VERITY_DEFAULT_PREFETCH_SIZE; 


module_param_named(prefetch_cluster, dm_verity_prefetch_cluster, uint, S_IRUGO | S_IWUSR);



enum verity_mode {

	DM_VERITY_MODE_EIO,

	DM_VERITY_MODE_LOGGING,

	DM_VERITY_MODE_RESTART

};



enum verity_block_type {

	DM_VERITY_BLOCK_TYPE_DATA,

	DM_VERITY_BLOCK_TYPE_METADATA

};



struct dm_verity {

	struct dm_dev *data_dev;

	struct dm_dev *hash_dev;

	struct dm_target *ti;

	struct dm_bufio_client *bufio;

	char *alg_name;

	struct crypto_shash *tfm;

	u8 *root_digest;	/* digest of the root block */

	u8 *salt;		/* salt: its size is salt_size */

	unsigned salt_size;

	sector_t data_start;	/* data offset in 512-byte sectors */

	sector_t hash_start;	/* hash start in blocks */

	sector_t data_blocks;	/* the number of data blocks */

	sector_t hash_blocks;	/* the number of hash blocks */

	unsigned char data_dev_block_bits;	/* log2(data blocksize) */

	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */

	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */

	unsigned char levels;	/* the number of tree levels */

	unsigned char version;

	unsigned digest_size;	/* digest size for the current hash algorithm */

	unsigned shash_descsize;/* the size of temporary space for crypto */

	int hash_failed;	/* set to 1 if hash of any block failed */

	enum verity_mode mode;	/* mode for handling verification errors */

	unsigned corrupted_errs;/* Number of errors for corrupted blocks */



	struct workqueue_struct *verify_wq;



	/* starting blocks for each tree level. 0 is the lowest level. */

	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];

};



struct dm_verity_io {

	struct dm_verity *v;



	/* original value of bio->bi_end_io */

	bio_end_io_t *orig_bi_end_io;



	sector_t block;

	unsigned n_blocks;



	struct bvec_iter iter;



	struct work_struct work;



	/*

	 * Three variably-size fields follow this struct:

	 *

	 * u8 hash_desc[v->shash_descsize];

	 * u8 real_digest[v->digest_size];

	 * u8 want_digest[v->digest_size];

	 *

	 * To access them use: io_hash_desc(), io_real_digest() and io_want_digest().

	 */

};



struct dm_verity_prefetch_work {

	struct work_struct work;

	struct dm_verity *v;
@@ -113,21 +44,6 @@ struct dm_verity_prefetch_work { 
	unsigned n_blocks;

};



static struct shash_desc *io_hash_desc(struct dm_verity *v, struct dm_verity_io *io)

{

	return (struct shash_desc *)(io + 1);

}



static u8 *io_real_digest(struct dm_verity *v, struct dm_verity_io *io)

{

	return (u8 *)(io + 1) + v->shash_descsize;

}



static u8 *io_want_digest(struct dm_verity *v, struct dm_verity_io *io)

{

	return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;

}



/*

 * Auxiliary structure appended to each dm-bufio buffer. If the value

 * hash_verified is nonzero, hash of the block has been verified.
@@ -236,7 +152,7 @@ static int verity_hash_final(struct dm_verity *v, struct shash_desc *desc, 
	return r;

}



static int verity_hash(struct dm_verity *v, struct shash_desc *desc,

int verity_hash(struct dm_verity *v, struct shash_desc *desc,

		const u8 *data, size_t len, u8 *digest)

{

	int r;
@@ -325,12 +241,12 @@ static int verity_handle_err(struct dm_verity *v, enum verity_block_type type, 
 * Verify hash of a metadata block pertaining to the specified data block

 * ("block" argument) at a specified level ("level" argument).

 *

 * On successful return, io_want_digest(v, io) contains the hash value for

 * a lower tree level or for the data block (if we're at the lowest leve).

 * On successful return, verity_io_want_digest(v, io) contains the hash value

 * for a lower tree level or for the data block (if we're at the lowest level).

 *

 * If "skip_unverified" is true, unverified buffer is skipped and 1 is returned.

 * If "skip_unverified" is false, unverified buffer is hashed and verified

 * against current value of io_want_digest(v, io).

 * against current value of verity_io_want_digest(v, io).

 */

static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io,

			       sector_t block, int level, bool skip_unverified,
@@ -357,13 +273,13 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 
			goto release_ret_r;

		}



		r = verity_hash(v, io_hash_desc(v, io),

		r = verity_hash(v, verity_io_hash_desc(v, io),

				data, 1 << v->hash_dev_block_bits,

				io_real_digest(v, io));

				verity_io_real_digest(v, io));

		if (unlikely(r < 0))

			goto release_ret_r;



		if (likely(memcmp(io_real_digest(v, io), want_digest,

		if (likely(memcmp(verity_io_real_digest(v, io), want_digest,

				  v->digest_size) == 0))

			aux->hash_verified = 1;

		else if (verity_handle_err(v,
@@ -387,7 +303,7 @@ static int verity_verify_level(struct dm_verity *v, struct dm_verity_io *io, 
 * Find a hash for a given block, write it to digest and verify the integrity

 * of the hash tree if necessary.

 */

static int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,

int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,

			  sector_t block, u8 *digest)

{

	int i;
@@ -430,10 +346,10 @@ static int verity_verify_io(struct dm_verity_io *io) 
	for (b = 0; b < io->n_blocks; b++) {

		int r;

		unsigned todo;

		struct shash_desc *desc = io_hash_desc(v, io);

		struct shash_desc *desc = verity_io_hash_desc(v, io);



		r = verity_hash_for_block(v, io, io->block + b,

					  io_want_digest(v, io));

					  verity_io_want_digest(v, io));

		if (unlikely(r < 0))

			return r;
@@ -462,12 +378,12 @@ static int verity_verify_io(struct dm_verity_io *io) 
			todo -= len;

		} while (todo);



		r = verity_hash_final(v, desc, io_real_digest(v, io));

		r = verity_hash_final(v, desc, verity_io_real_digest(v, io));

		if (unlikely(r < 0))

			return r;



		if (likely(memcmp(io_real_digest(v, io),

				io_want_digest(v, io), v->digest_size) == 0))

		if (likely(memcmp(verity_io_real_digest(v, io),

				  verity_io_want_digest(v, io), v->digest_size) == 0))

			continue;

		else if (verity_handle_err(v, DM_VERITY_BLOCK_TYPE_DATA,

				io->block + b))

drivers/md/dm-verity.h

0 → 100644
+112 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2012 Red Hat, Inc.

 * Copyright (C) 2015 Google, Inc.

 *

 * Author: Mikulas Patocka <mpatocka@redhat.com>

 *

 * Based on Chromium dm-verity driver (C) 2011 The Chromium OS Authors

 *

 * This file is released under the GPLv2.

 */



#ifndef DM_VERITY_H

#define DM_VERITY_H



#include "dm-bufio.h"

#include <linux/device-mapper.h>

#include <crypto/hash.h>



#define DM_VERITY_MAX_LEVELS		63



enum verity_mode {

	DM_VERITY_MODE_EIO,

	DM_VERITY_MODE_LOGGING,

	DM_VERITY_MODE_RESTART

};



enum verity_block_type {

	DM_VERITY_BLOCK_TYPE_DATA,

	DM_VERITY_BLOCK_TYPE_METADATA

};



struct dm_verity {

	struct dm_dev *data_dev;

	struct dm_dev *hash_dev;

	struct dm_target *ti;

	struct dm_bufio_client *bufio;

	char *alg_name;

	struct crypto_shash *tfm;

	u8 *root_digest;	/* digest of the root block */

	u8 *salt;		/* salt: its size is salt_size */

	unsigned salt_size;

	sector_t data_start;	/* data offset in 512-byte sectors */

	sector_t hash_start;	/* hash start in blocks */

	sector_t data_blocks;	/* the number of data blocks */

	sector_t hash_blocks;	/* the number of hash blocks */

	unsigned char data_dev_block_bits;	/* log2(data blocksize) */

	unsigned char hash_dev_block_bits;	/* log2(hash blocksize) */

	unsigned char hash_per_block_bits;	/* log2(hashes in hash block) */

	unsigned char levels;	/* the number of tree levels */

	unsigned char version;

	unsigned digest_size;	/* digest size for the current hash algorithm */

	unsigned shash_descsize;/* the size of temporary space for crypto */

	int hash_failed;	/* set to 1 if hash of any block failed */

	enum verity_mode mode;	/* mode for handling verification errors */

	unsigned corrupted_errs;/* Number of errors for corrupted blocks */



	struct workqueue_struct *verify_wq;



	/* starting blocks for each tree level. 0 is the lowest level. */

	sector_t hash_level_block[DM_VERITY_MAX_LEVELS];

};



struct dm_verity_io {

	struct dm_verity *v;



	/* original value of bio->bi_end_io */

	bio_end_io_t *orig_bi_end_io;



	sector_t block;

	unsigned n_blocks;



	struct bvec_iter iter;



	struct work_struct work;



	/*

	 * Three variably-size fields follow this struct:

	 *

	 * u8 hash_desc[v->shash_descsize];

	 * u8 real_digest[v->digest_size];

	 * u8 want_digest[v->digest_size];

	 *

	 * To access them use: verity_io_hash_desc(), verity_io_real_digest()

	 * and verity_io_want_digest().

	 */

};



static inline struct shash_desc *verity_io_hash_desc(struct dm_verity *v,

						     struct dm_verity_io *io)

{

	return (struct shash_desc *)(io + 1);

}



static inline u8 *verity_io_real_digest(struct dm_verity *v,

					struct dm_verity_io *io)

{

	return (u8 *)(io + 1) + v->shash_descsize;

}



static inline u8 *verity_io_want_digest(struct dm_verity *v,

					struct dm_verity_io *io)

{

	return (u8 *)(io + 1) + v->shash_descsize + v->digest_size;

}



extern int verity_hash(struct dm_verity *v, struct shash_desc *desc,

		       const u8 *data, size_t len, u8 *digest);



extern int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,

				 sector_t block, u8 *digest);



#endif /* DM_VERITY_H */