diff options
Diffstat (limited to 'common/rollback.c')
| -rw-r--r-- | common/rollback.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/common/rollback.c b/common/rollback.c new file mode 100644 index 0000000000..dbeffaa051 --- /dev/null +++ b/common/rollback.c @@ -0,0 +1,179 @@ +/* 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" + +/* 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_update(int32_t next_min_version) +{ + struct rollback_data data; + uintptr_t offset; + int region; + int32_t current_min_version; + int ret; + + 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; + + if (system_unsafe_to_overwrite(offset, CONFIG_FLASH_ERASE_SIZE)) + return EC_ERROR_ACCESS_DENIED; + + ret = flash_erase(offset, CONFIG_FLASH_ERASE_SIZE); + if (ret) + return ret; + + return flash_write(offset, sizeof(data), (char *)&data); +} + +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"); |