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fix(core/bootloader): fix unlocking bootloader granting HDP access on U5

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This commit is contained in:
tychovrahe 2024-09-05 16:28:28 +02:00 committed by TychoVrahe
parent 422b376ebd
commit be9255ae04
3 changed files with 47 additions and 10 deletions
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3
core/embed/trezorhal/secret.h
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@ -56,6 +56,9 @@ secbool secret_optiga_get(uint8_t dest[SECRET_OPTIGA_KEY_LEN]);
// Checks if the optiga pairing secret is present in the secret storage
secbool secret_optiga_present(void);
// Checks if the optiga pairing secret can be written to the secret storage
secbool secret_optiga_writable(void);
// Erases optiga pairing secret from the secret storage
void secret_optiga_erase(void);

2
core/embed/trezorhal/stm32f4/secret.c
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@ -102,6 +102,8 @@ secbool secret_optiga_present(void) {
return (sectrue != secret_wiped()) * sectrue;
}
secbool secret_optiga_writable(void) { return secret_wiped(); }
void secret_optiga_erase(void) { secret_erase(); }
void secret_prepare_fw(secbool allow_run_with_secret, secbool _trust_all) {

46
core/embed/trezorhal/stm32u5/secret.c
View File

@ -176,6 +176,29 @@ secbool secret_optiga_present(void) {
return secret_present(SECRET_OPTIGA_KEY_OFFSET, SECRET_OPTIGA_KEY_LEN);
}
secbool secret_optiga_writable(void) {
const uint32_t offset = SECRET_OPTIGA_KEY_OFFSET;
const uint32_t len = SECRET_OPTIGA_KEY_LEN;
const uint8_t *const secret =
(uint8_t *)flash_area_get_address(&SECRET_AREA, offset, len);
if (secret == NULL) {
return secfalse;
}
int secret_empty_bytes = 0;
for (int i = 0; i < len; i++) {
// 0xFF being the default value of the flash memory (before any write)
// 0x00 being the value of the flash memory after manual erase
if (secret[i] == 0xFF) {
secret_empty_bytes++;
}
}
return sectrue * (secret_empty_bytes == len);
}
// Backs up the optiga pairing secret from the secret storage to the backup
// register
static void secret_optiga_cache(void) {
@ -270,17 +293,26 @@ void secret_prepare_fw(secbool allow_run_with_secret, secbool trust_all) {
secret_bhk_lock();
#ifdef USE_OPTIGA
secret_optiga_uncache();
if (sectrue == allow_run_with_secret) {
if (secfalse != secret_optiga_present()) {
secbool optiga_secret_present = secret_optiga_present();
secbool optiga_secret_writable = secret_optiga_writable();
if (sectrue == trust_all && sectrue == allow_run_with_secret &&
sectrue == optiga_secret_writable && secfalse == optiga_secret_present) {
// Secret is not present and the secret sector is writable.
// This means the U5 chip is unprovisioned.
// Allow trusted firmware (prodtest presumably) to access the secret sector,
// early return here.
return;
}
if (sectrue == allow_run_with_secret && sectrue == optiga_secret_present) {
// Firmware is trusted and the Optiga secret is present, make it available.
secret_optiga_cache();
secret_disable_access();
}
} else {
if (secfalse != secret_optiga_present()) {
// Disable access unconditionally.
secret_disable_access();
if (sectrue != trust_all && sectrue == optiga_secret_present) {
// Untrusted firmware, locked bootloader. Show the restricted screen.
show_install_restricted_screen();
}
secret_disable_access();
}
#else
secret_disable_access();
#endif