/* 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; }