| /* 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(); |
| 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; |
| } |