diff options
Diffstat (limited to 'src/security/vboot/vbnv.c')
| -rw-r--r-- | src/security/vboot/vbnv.c | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/src/security/vboot/vbnv.c b/src/security/vboot/vbnv.c new file mode 100644 index 0000000000..0fecacd4d2 --- /dev/null +++ b/src/security/vboot/vbnv.c @@ -0,0 +1,155 @@ +/* + * This file is part of the coreboot project. + * + * Copyright (C) 2016 Google Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * 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. + */ + +#include <arch/early_variables.h> +#include <string.h> +#include <types.h> +#include <security/vboot/vbnv.h> +#include <security/vboot/vbnv_layout.h> + +static int vbnv_initialized CAR_GLOBAL; +static uint8_t vbnv[VBOOT_VBNV_BLOCK_SIZE] CAR_GLOBAL; + +/* Wrappers for accessing the variables marked as CAR_GLOBAL. */ +static inline int is_vbnv_initialized(void) +{ + return car_get_var(vbnv_initialized); +} + +static inline uint8_t *vbnv_data_addr(int index) +{ + uint8_t *vbnv_arr = car_get_var_ptr(vbnv); + + return &vbnv_arr[index]; +} + +static inline uint8_t vbnv_data(int index) +{ + return *vbnv_data_addr(index); +} + +/* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. */ +static uint8_t crc8_vbnv(const uint8_t *data, int len) +{ + unsigned crc = 0; + int i, j; + + for (j = len; j; j--, data++) { + crc ^= (*data << 8); + for (i = 8; i; i--) { + if (crc & 0x8000) + crc ^= (0x1070 << 3); + crc <<= 1; + } + } + + return (uint8_t) (crc >> 8); +} + +void vbnv_reset(uint8_t *vbnv_copy) +{ + memset(vbnv_copy, 0, VBOOT_VBNV_BLOCK_SIZE); +} + +/* Read VBNV data into cache. */ +static void vbnv_setup(void) +{ + if (!is_vbnv_initialized()) { + read_vbnv(vbnv_data_addr(0)); + car_set_var(vbnv_initialized, 1); + } +} + +/* Verify VBNV header and checksum. */ +int verify_vbnv(uint8_t *vbnv_copy) +{ + return (HEADER_SIGNATURE == (vbnv_copy[HEADER_OFFSET] & HEADER_MASK)) && + (crc8_vbnv(vbnv_copy, CRC_OFFSET) == vbnv_copy[CRC_OFFSET]); +} + +/* Re-generate VBNV checksum. */ +void regen_vbnv_crc(uint8_t *vbnv_copy) +{ + vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET); +} + +/* + * Read VBNV data from configured storage backend. + * If VBNV verification fails, reset the vbnv copy. + */ +void read_vbnv(uint8_t *vbnv_copy) +{ + if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS)) + read_vbnv_cmos(vbnv_copy); + else if (IS_ENABLED(CONFIG_VBOOT_VBNV_EC)) + read_vbnv_ec(vbnv_copy); + else if (IS_ENABLED(CONFIG_VBOOT_VBNV_FLASH)) + read_vbnv_flash(vbnv_copy); + + /* Check data for consistency */ + if (!verify_vbnv(vbnv_copy)) + vbnv_reset(vbnv_copy); +} + +/* + * Write VBNV data to configured storage backend. + * This assumes that the caller has updated the CRC already. + */ +void save_vbnv(const uint8_t *vbnv_copy) +{ + if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS)) + save_vbnv_cmos(vbnv_copy); + else if (IS_ENABLED(CONFIG_VBOOT_VBNV_EC)) + save_vbnv_ec(vbnv_copy); + else if (IS_ENABLED(CONFIG_VBOOT_VBNV_FLASH)) + save_vbnv_flash(vbnv_copy); + + /* Clear initialized flag to force cached data to be updated */ + car_set_var(vbnv_initialized, 0); +} + +/* Save a recovery reason into VBNV. */ +void set_recovery_mode_into_vbnv(int recovery_reason) +{ + uint8_t vbnv_copy[VBOOT_VBNV_BLOCK_SIZE]; + + read_vbnv(vbnv_copy); + + vbnv_copy[RECOVERY_OFFSET] = recovery_reason; + vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET); + + save_vbnv(vbnv_copy); +} + +/* Read the recovery reason from VBNV. */ +int get_recovery_mode_from_vbnv(void) +{ + vbnv_setup(); + return vbnv_data(RECOVERY_OFFSET); +} + +/* Read the BOOT_OPROM_NEEDED flag from VBNV. */ +int vboot_wants_oprom(void) +{ + vbnv_setup(); + return (vbnv_data(BOOT_OFFSET) & BOOT_OPROM_NEEDED) ? 1 : 0; +} + +void vbnv_init(uint8_t *vbnv_copy) +{ + if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS)) + vbnv_init_cmos(vbnv_copy); + read_vbnv(vbnv_copy); +} |