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/* Copyright 2017 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.
*/
/* Rollback protection logic. */
#include "common.h"
#include "console.h"
#include "flash.h"
#include "rollback.h"
#include "system.h"
#include "util.h"
/* Console output macros */
#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
/* Number of rollback regions */
#define ROLLBACK_REGIONS 2
/*
* Note: Do not change this structure without also updating
* common/firmware_image.S .image.ROLLBACK section.
*/
struct rollback_data {
int32_t rollback_min_version;
uint32_t cookie;
};
/* We need at least 2 erasable blocks in the rollback region. */
BUILD_ASSERT(CONFIG_ROLLBACK_SIZE >= ROLLBACK_REGIONS*CONFIG_FLASH_ERASE_SIZE);
BUILD_ASSERT(sizeof(struct rollback_data) <= CONFIG_FLASH_ERASE_SIZE);
static uintptr_t get_rollback_offset(int region)
{
return CONFIG_ROLLBACK_OFF + region * CONFIG_FLASH_ERASE_SIZE;
}
static int read_rollback(int region, struct rollback_data *data)
{
uintptr_t offset;
offset = get_rollback_offset(region);
if (flash_read(offset, sizeof(*data), (char *)data))
return EC_ERROR_UNKNOWN;
return EC_SUCCESS;
}
/*
* Get the most recent rollback information.
*
* @rollback_min_version: Minimum version to accept for rollback protection,
* or 0 if no rollback information is present.
*
* Return most recent region index on success (>= 0, or 0 if no rollback
* region is valid), negative value on error.
*/
static int get_latest_rollback(int32_t *rollback_min_version)
{
int region;
int min_region = 0;
*rollback_min_version = 0;
for (region = 0; region < ROLLBACK_REGIONS; region++) {
struct rollback_data data;
if (read_rollback(region, &data))
return -1;
/* Check if not initialized or invalid cookie. */
if (data.cookie != CROS_EC_ROLLBACK_COOKIE)
continue;
if (data.rollback_min_version > *rollback_min_version) {
min_region = region;
*rollback_min_version = data.rollback_min_version;
}
}
return min_region;
}
int32_t rollback_get_minimum_version(void)
{
int32_t rollback_min_version;
if (get_latest_rollback(&rollback_min_version) < 0)
return -1;
return rollback_min_version;
}
int rollback_lock(void)
{
int ret;
/* Already locked */
if (flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW)
return EC_SUCCESS;
CPRINTS("Protecting rollback");
/* This may do nothing if WP is not enabled, or RO is not protected. */
ret = flash_set_protect(EC_FLASH_PROTECT_ROLLBACK_AT_BOOT, -1);
if (!(flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW) &&
flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_AT_BOOT) {
/*
* If flash protection is still not enabled (some chips may
* be able to enable it immediately), reboot.
*/
cflush();
system_reset(SYSTEM_RESET_HARD | SYSTEM_RESET_PRESERVE_FLAGS);
}
return ret;
}
int rollback_update(int32_t next_min_version)
{
struct rollback_data data;
uintptr_t offset;
int region;
int32_t current_min_version;
if (flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW)
return EC_ERROR_ACCESS_DENIED;
region = get_latest_rollback(¤t_min_version);
if (region < 0)
return EC_ERROR_UNKNOWN;
/* Do not accept to decrement the value. */
if (next_min_version < current_min_version)
return EC_ERROR_INVAL;
/* No need to update if version is already correct. */
if (next_min_version == current_min_version)
return EC_SUCCESS;
/* Use the other region. */
region = (region + 1) % ROLLBACK_REGIONS;
offset = get_rollback_offset(region);
data.rollback_min_version = next_min_version;
data.cookie = CROS_EC_ROLLBACK_COOKIE;
/* Offset should never be part of active image. */
if (system_unsafe_to_overwrite(offset, CONFIG_FLASH_ERASE_SIZE))
return EC_ERROR_UNKNOWN;
if (flash_erase(offset, CONFIG_FLASH_ERASE_SIZE))
return EC_ERROR_UNKNOWN;
if (flash_write(offset, sizeof(data), (char *)&data))
return EC_ERROR_UNKNOWN;
return EC_SUCCESS;
}
static int command_rollback_info(int argc, char **argv)
{
int region, ret, min_region;
int32_t rollback_min_version;
min_region = get_latest_rollback(&rollback_min_version);
if (min_region < 0)
return EC_ERROR_UNKNOWN;
ccprintf("rollback minimum version: %d\n", rollback_min_version);
for (region = 0; region < ROLLBACK_REGIONS; region++) {
struct rollback_data data;
ret = read_rollback(region, &data);
if (ret)
return ret;
ccprintf("rollback %d: %08x %08x%s\n",
region, data.rollback_min_version, data.cookie,
min_region == region ? " *" : "");
}
return EC_SUCCESS;
}
DECLARE_SAFE_CONSOLE_COMMAND(rollbackinfo, command_rollback_info,
NULL,
"Print rollback info");
static int command_rollback_update(int argc, char **argv)
{
int32_t min_version;
char *e;
if (argc < 2)
return EC_ERROR_PARAM_COUNT;
min_version = strtoi(argv[1], &e, 0);
if (*e || min_version < 0)
return EC_ERROR_PARAM1;
return rollback_update(min_version);
}
DECLARE_CONSOLE_COMMAND(rollbackupdate, command_rollback_update,
"min_version",
"Update rollback info");
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