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/* Copyright 2016 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef VBOOT_REFERENCE_BDB_NVM_H_
#define VBOOT_REFERENCE_BDB_NVM_H_
#include <stdint.h>
#include "bdb_struct.h"
#include "bdb_api.h"
enum nvm_type {
NVM_TYPE_WP_PRIMARY,
NVM_TYPE_WP_SECONDARY,
NVM_TYPE_RW_PRIMARY,
NVM_TYPE_RW_SECONDARY,
};
#define NVM_RW_MAGIC 0x3052766e
/* Size in bytes of encrypted BUC (Boot Unlock Code) */
#define BUC_ENC_DIGEST_SIZE 32
/* Size in bytes of HMAC of struct NVM-RW */
#define NVM_HMAC_SIZE BDB_SHA256_DIGEST_SIZE
#define NVM_RW_FLAG_BUC_PRESENT (1 << 0)
#define NVM_RW_FLAG_DFM_DISABLE (1 << 1)
#define NVM_RW_FLAG_DOSM (1 << 2)
/* This is the minimum size of the data needed to learn the actual size */
#define NVM_MIN_STRUCT_SIZE 8
#define NVM_HEADER_VERSION_MAJOR 1
#define NVM_HEADER_VERSION_MINOR 1
/* Maximum number of retries for writing NVM */
#define NVM_MAX_WRITE_RETRY 2
struct nvmrw {
/* Magic number to identify struct */
uint32_t struct_magic;
/* Structure version */
uint8_t struct_major_version;
uint8_t struct_minor_version;
/* Size of struct in bytes. 96 for version 1.0 */
uint16_t struct_size;
/* Number of updates to structure contents */
uint32_t update_count;
/* Flags: NVM_RW_FLAG_* */
uint32_t flags;
/* Minimum valid kernel data key version */
uint32_t min_kernel_data_key_version;
/* Minimum valid kernel version */
uint32_t min_kernel_version;
/* Type of BUC */
uint8_t buc_type;
uint8_t reserved0[7];
/* Encrypted BUC */
uint8_t buc_enc_digest[BUC_ENC_DIGEST_SIZE];
/* SHA-256 HMAC of the struct contents. Add new fields before this. */
uint8_t hmac[NVM_HMAC_SIZE];
} __attribute__((packed));
/*
* List of variables stored in NVM-RW. This should be exported and used by
* firmware and futility to access data in NVM-RW.
*/
enum nvmrw_var {
NVMRW_VAR_UPDATE_COUNT,
NVMRW_VAR_FLAGS,
NVMRW_VAR_MIN_KERNEL_DATA_KEY_VERSION,
NVMRW_VAR_MIN_KERNEL_VERSION,
NVMRW_VAR_BUC_TYPE,
NVMRW_VAR_FLAG_BUC_PRESENT,
NVMRW_VAR_FLAG_DFM_DISABLE,
NVMRW_VAR_FLAG_DOSM,
};
/* Size of the version 1.0 */
#define NVM_RW_MIN_STRUCT_SIZE 96
/* 4 Kbit EEPROM divided by 4 regions (RO,RW) x (1st,2nd) = 128 KB */
#define NVM_RW_MAX_STRUCT_SIZE 128
/* For nvm_rw_read and nvm_write */
struct vba_context;
/**
* Read NVM-RW contents into the context
*
* @param ctx struct vba_context
* @return BDB_SUCCESS or BDB_ERROR_NVM_*
*/
int nvmrw_read(struct vba_context *ctx);
/**
* Write to NVM-RW from the context
*
* @param ctx struct vba_context
* @param type NVM_TYPE_RW_*
* @return BDB_SUCCESS or BDB_ERROR_NVM_*
*/
int nvmrw_write(struct vba_context *ctx, enum nvm_type type);
/**
* Get a value of NVM-RW variable
*
* Callers are responsible for init and verify of ctx->nvmrw.
*
* @param ctx struct vba_context
* @param var Index of the variable
* @param val Destination where the value is stored
* @return BDB_SUCCESS or BDB_ERROR_NVM_*
*/
int nvmrw_get(struct vba_context *ctx, enum nvmrw_var var, uint32_t *val);
/**
* Set a value in NVM-RW variable
*
* Callers are responsible for init and verify of ctx->nvmrw.
*
* @param ctx struct vba_context
* @param var Index of the variable
* @param val Value to be set
* @return BDB_SUCCESS or BDB_ERROR_NVM_*
*/
int nvmrw_set(struct vba_context *ctx, enum nvmrw_var var, uint32_t val);
#endif
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