panda/board/bootstub.c

67 lines
1.2 KiB
C

#ifdef STM32F4
#define PANDA
#include "stm32f4xx.h"
#else
#include "stm32f2xx.h"
#endif
#include "early.h"
#include "libc.h"
#include "crypto/rsa.h"
#include "crypto/sha.h"
#include "obj/cert.h"
void lock_bootloader() {
if (FLASH->OPTCR & FLASH_OPTCR_nWRP_0) {
FLASH->OPTKEYR = 0x08192A3B;
FLASH->OPTKEYR = 0x4C5D6E7F;
// write protect the bootloader
FLASH->OPTCR &= ~FLASH_OPTCR_nWRP_0;
// OPT program
FLASH->OPTCR |= FLASH_OPTCR_OPTSTRT;
while (FLASH->SR & FLASH_SR_BSY);
// relock it
FLASH->OPTCR |= FLASH_OPTCR_OPTLOCK;
// reset
NVIC_SystemReset();
}
}
void __initialize_hardware_early() {
lock_bootloader();
early();
}
void fail() {
enter_bootloader_mode = ENTER_BOOTLOADER_MAGIC;
NVIC_SystemReset();
}
int main() {
clock_init();
// validate length
int len = _app_start[0];
if (len < 8) fail();
// compute SHA hash
char digest[SHA_DIGEST_SIZE];
SHA_hash(&_app_start[1], len-4, digest);
// verify RSA signature
if (!RSA_verify(&rsa_key, ((void*)&_app_start[0]) + len, RSANUMBYTES, digest, SHA_DIGEST_SIZE)) {
fail();
}
// jump to flash
((void(*)()) _app_start[1])();
return 0;
}