105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* This file is part of the coreboot project. */
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#include <string.h>
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#include <types.h>
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#include <security/vboot/vbnv.h>
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#include <security/vboot/vbnv_layout.h>
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static int vbnv_initialized;
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static uint8_t vbnv[VBOOT_VBNV_BLOCK_SIZE];
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/* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. */
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static uint8_t crc8_vbnv(const uint8_t *data, int len)
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{
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unsigned int crc = 0;
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int i, j;
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for (j = len; j; j--, data++) {
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crc ^= (*data << 8);
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for (i = 8; i; i--) {
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if (crc & 0x8000)
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crc ^= (0x1070 << 3);
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crc <<= 1;
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}
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}
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return (uint8_t) (crc >> 8);
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}
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void vbnv_reset(uint8_t *vbnv_copy)
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{
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memset(vbnv_copy, 0, VBOOT_VBNV_BLOCK_SIZE);
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}
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/* Read VBNV data into cache. */
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static void vbnv_setup(void)
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{
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if (!vbnv_initialized) {
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read_vbnv(vbnv);
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vbnv_initialized = 1;
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}
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}
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/* Verify VBNV header and checksum. */
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int verify_vbnv(uint8_t *vbnv_copy)
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{
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return (HEADER_SIGNATURE == (vbnv_copy[HEADER_OFFSET] & HEADER_MASK)) &&
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(crc8_vbnv(vbnv_copy, CRC_OFFSET) == vbnv_copy[CRC_OFFSET]);
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}
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/* Re-generate VBNV checksum. */
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void regen_vbnv_crc(uint8_t *vbnv_copy)
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{
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vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET);
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}
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/*
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* Read VBNV data from configured storage backend.
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* If VBNV verification fails, reset the vbnv copy.
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*/
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void read_vbnv(uint8_t *vbnv_copy)
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{
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if (CONFIG(VBOOT_VBNV_CMOS))
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read_vbnv_cmos(vbnv_copy);
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else if (CONFIG(VBOOT_VBNV_EC))
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read_vbnv_ec(vbnv_copy);
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else if (CONFIG(VBOOT_VBNV_FLASH))
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read_vbnv_flash(vbnv_copy);
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/* Check data for consistency */
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if (!verify_vbnv(vbnv_copy))
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vbnv_reset(vbnv_copy);
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}
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/*
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* Write VBNV data to configured storage backend.
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* This assumes that the caller has updated the CRC already.
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*/
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void save_vbnv(const uint8_t *vbnv_copy)
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{
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if (CONFIG(VBOOT_VBNV_CMOS))
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save_vbnv_cmos(vbnv_copy);
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else if (CONFIG(VBOOT_VBNV_EC))
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save_vbnv_ec(vbnv_copy);
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else if (CONFIG(VBOOT_VBNV_FLASH))
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save_vbnv_flash(vbnv_copy);
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/* Clear initialized flag to force cached data to be updated */
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vbnv_initialized = 0;
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}
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/* Read the USB Device Controller(UDC) enable flag from VBNV. */
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int vbnv_udc_enable_flag(void)
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{
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vbnv_setup();
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return (vbnv[DEV_FLAGS_OFFSET] & DEV_ENABLE_UDC) ? 1 : 0;
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}
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void vbnv_init(uint8_t *vbnv_copy)
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{
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if (CONFIG(VBOOT_VBNV_CMOS))
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vbnv_init_cmos(vbnv_copy);
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read_vbnv(vbnv_copy);
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}
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