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

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

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Sami Tolvanen 2015-12-03 16:01:51 -05:00 committed by Mike Snitzer
parent 03045cbafa
commit ffa393807c
2 changed files with 128 additions and 100 deletions
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116
drivers/md/dm-verity-target.c
View file

@ -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.
@ -236,8 +152,8 @@ 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,
const u8 *data, size_t len, u8 *digest)
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,
@ -387,8 +303,8 @@ 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,
sector_t block, u8 *digest)
int verity_hash_for_block(struct dm_verity *v, struct dm_verity_io *io,
sector_t block, u8 *digest)
{
int i;
int r;
@ -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))

112
drivers/md/dm-verity.h Normal file
View file

@ -0,0 +1,112 @@
/*
* 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 */