drivers/md/dm-android-verity.h

/*
 * Copyright (C) 2015 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 */

#ifndef DM_ANDROID_VERITY_H
#define DM_ANDROID_VERITY_H

#include <crypto/sha.h>

#define RSANUMBYTES 256
#define VERITY_METADATA_MAGIC_NUMBER 0xb001b001
#define VERITY_METADATA_MAGIC_DISABLE 0x46464f56
#define VERITY_METADATA_VERSION 0
#define VERITY_STATE_DISABLE 1
#define DATA_BLOCK_SIZE (4 * 1024)
#define VERITY_METADATA_SIZE (8 * DATA_BLOCK_SIZE)
#define VERITY_TABLE_ARGS 10
#define VERITY_COMMANDLINE_PARAM_LENGTH 20
#define BUILD_VARIANT 20

/*
 * <subject>:<sha1-id> is the format for the identifier.
 * subject can either be the Common Name(CN) + Organization Name(O) or
 * just the CN if the it is prefixed with O
 * From https://tools.ietf.org/html/rfc5280#appendix-A
 * ub-organization-name-length INTEGER ::= 64
 * ub-common-name-length INTEGER ::= 64
 *
 * http://lxr.free-electrons.com/source/crypto/asymmetric_keys/x509_cert_parser.c?v=3.9#L278
 * ctx->o_size + 2 + ctx->cn_size + 1
 * + 41 characters for ":" and sha1 id
 * 64 + 2 + 64 + 1 + 1 + 40 (172)
 * setting VERITY_DEFAULT_KEY_ID_LENGTH to 200 characters.
 */
#define VERITY_DEFAULT_KEY_ID_LENGTH 200

#define FEC_MAGIC 0xFECFECFE
#define FEC_BLOCK_SIZE (4 * 1024)
#define FEC_VERSION 0
#define FEC_RSM 255
#define FEC_ARG_LENGTH 300

#define VERITY_TABLE_OPT_RESTART "restart_on_corruption"
#define VERITY_TABLE_OPT_LOGGING "ignore_corruption"
#define VERITY_TABLE_OPT_IGNZERO "ignore_zero_blocks"

#define VERITY_TABLE_OPT_FEC_FORMAT \
	"use_fec_from_device %s fec_start %llu fec_blocks %llu fec_roots %u ignore_zero_blocks"
#define VERITY_TABLE_OPT_FEC_ARGS 9

#define VERITY_DEBUG 0

#define DM_MSG_PREFIX                   "android-verity"

#define DM_LINEAR_ARGS 2
#define DM_LINEAR_TARGET_OFFSET "0"

/*
 * There can be two formats.
 * if fec is present
 * <data_blocks> <verity_tree> <verity_metdata_32K><fec_data><fec_data_4K>
 * if fec is not present
 * <data_blocks> <verity_tree> <verity_metdata_32K>
 */
struct fec_header {
	__le32 magic;
	__le32 version;
	__le32 size;
	__le32 roots;
	__le32 fec_size;
	__le64 inp_size;
	u8 hash[SHA256_DIGEST_SIZE];
} __attribute__((packed));

struct android_metadata_header {
	__le32 magic_number;
	__le32 protocol_version;
	char signature[RSANUMBYTES];
	__le32 table_length;
};

struct android_metadata {
	struct android_metadata_header *header;
	char *verity_table;
};

struct fec_ecc_metadata {
	bool valid;
	u32 roots;
	u64 blocks;
	u64 rounds;
	u64 start;
};

struct bio_read {
	struct page **page_io;
	int number_of_pages;
};

extern struct target_type linear_target;

extern void dm_linear_dtr(struct dm_target *ti);
extern int dm_linear_map(struct dm_target *ti, struct bio *bio);
extern void dm_linear_status(struct dm_target *ti, status_type_t type,
			unsigned status_flags, char *result, unsigned maxlen);
extern int dm_linear_prepare_ioctl(struct dm_target *ti,
                struct block_device **bdev, fmode_t *mode);
extern int dm_linear_iterate_devices(struct dm_target *ti,
			iterate_devices_callout_fn fn, void *data);
extern int dm_linear_ctr(struct dm_target *ti, unsigned int argc, char **argv);
#endif /* DM_ANDROID_VERITY_H */