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/* SPDX-License-Identifier: GPL-2.0-only */
#include <assert.h>
#include <string.h>
#include <types.h>
#include <security/vboot/misc.h>
#include <security/vboot/vbnv.h>
#include <security/vboot/vbnv_layout.h>
#include <vb2_api.h>
static bool vbnv_initialized;
/* 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 int 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);
}
/* 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 (CONFIG(VBOOT_VBNV_CMOS))
read_vbnv_cmos(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_FLASH))
read_vbnv_flash(vbnv_copy);
else
dead_code();
/* 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 (CONFIG(VBOOT_VBNV_CMOS))
save_vbnv_cmos(vbnv_copy);
else if (CONFIG(VBOOT_VBNV_FLASH))
save_vbnv_flash(vbnv_copy);
else
dead_code();
}
/* Read the USB Device Controller(UDC) enable flag from VBNV. */
int vbnv_udc_enable_flag(void)
{
struct vb2_context *ctx = vboot_get_context();
/* This function is expected to be called after temporary nvdata storage in vboot
context is initialized. */
assert(vbnv_initialized);
return (ctx->nvdata[DEV_FLAGS_OFFSET] & DEV_ENABLE_UDC) ? 1 : 0;
}
void vbnv_init(void)
{
struct vb2_context *ctx;
/* NV data already initialized and read */
if (vbnv_initialized)
return;
ctx = vboot_get_context();
if (CONFIG(VBOOT_VBNV_CMOS))
vbnv_init_cmos(ctx->nvdata);
read_vbnv(ctx->nvdata);
vbnv_initialized = true;
}
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