core/common: Change delay_random() to wait_random().

core/embed/trezorhal/common.c

@@ -24,8 +24,8 @@
 #include "common.h"
 #include "display.h"
 #include "flash.h"
-#include "rand.h"
 #include "hmac_drbg.h"
+#include "rand.h"
 
 #include "stm32f4xx_ll_utils.h"
 
@@ -122,7 +122,11 @@ void __assert_func(const char *file, int line, const char *func,
 
 void hal_delay(uint32_t ms) { HAL_Delay(ms); }
 
-void delay_random(void) {
+/*
+ * Generates a delay of random length. Use this to protect sensitive code
+ * against fault injection.
+ */
+void wait_random(void) {
   int wait = drbg_random32() & 0xff;
   volatile int i = 0;
   volatile int j = wait;
@@ -188,7 +192,7 @@ void collect_hw_entropy(void) {
          NULL);
 }
 
-void drbg_init() {
+void drbg_init(void) {
   uint8_t entropy[48];
   random_buffer(entropy, sizeof(entropy));
   hmac_drbg_init(&drbg_ctx, entropy, sizeof(entropy), NULL, 0);

core/embed/trezorhal/common.h

@@ -66,7 +66,7 @@ error_shutdown(const char *line1, const char *line2, const char *line3,
 
 void hal_delay(uint32_t ms);
 
-void delay_random(void);
+void wait_random(void);
 
 void clear_otg_hs_memory(void);
 
@@ -76,7 +76,7 @@ void collect_hw_entropy(void);
 #define HW_ENTROPY_LEN (12 + 32)
 extern uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
 
-void drbg_init();
+void drbg_init(void);
 void drbg_reseed(const uint8_t *entropy, size_t len);
 void drbg_generate(uint8_t *buf, size_t len);
 uint32_t drbg_random32(void);

core/embed/trezorhal/usb.c

@@ -343,7 +343,7 @@ static uint8_t usb_class_deinit(USBD_HandleTypeDef *dev, uint8_t cfg_idx) {
 
 static uint8_t usb_class_setup(USBD_HandleTypeDef *dev,
                                USBD_SetupReqTypedef *req) {
-  delay_random();
+  wait_random();
   if (((req->bmRequest & USB_REQ_TYPE_MASK) != USB_REQ_TYPE_CLASS) &&
       ((req->bmRequest & USB_REQ_TYPE_MASK) != USB_REQ_TYPE_STANDARD) &&
       ((req->bmRequest & USB_REQ_TYPE_MASK) != USB_REQ_TYPE_VENDOR)) {
@@ -472,7 +472,7 @@ static uint8_t usb_class_setup(USBD_HandleTypeDef *dev,
 }
 
 static uint8_t usb_class_data_in(USBD_HandleTypeDef *dev, uint8_t ep_num) {
-  delay_random();
+  wait_random();
   for (int i = 0; i < USBD_MAX_NUM_INTERFACES; i++) {
     switch (usb_ifaces[i].type) {
       case USB_IFACE_TYPE_HID:
@@ -492,7 +492,7 @@ static uint8_t usb_class_data_in(USBD_HandleTypeDef *dev, uint8_t ep_num) {
 }
 
 static uint8_t usb_class_data_out(USBD_HandleTypeDef *dev, uint8_t ep_num) {
-  delay_random();
+  wait_random();
   for (int i = 0; i < USBD_MAX_NUM_INTERFACES; i++) {
     switch (usb_ifaces[i].type) {
       case USB_IFACE_TYPE_HID:
@@ -512,7 +512,7 @@ static uint8_t usb_class_data_out(USBD_HandleTypeDef *dev, uint8_t ep_num) {
 }
 
 static uint8_t usb_class_sof(USBD_HandleTypeDef *dev) {
-  delay_random();
+  wait_random();
   for (int i = 0; i < USBD_MAX_NUM_INTERFACES; i++) {
     switch (usb_ifaces[i].type) {
       case USB_IFACE_TYPE_VCP:

core/embed/unix/common.c

@@ -109,6 +109,8 @@ error_shutdown(const char *line1, const char *line2, const char *line3,
 
 void hal_delay(uint32_t ms) { usleep(1000 * ms); }
 
+void wait_random(void) {}
+
 uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
 
 void collect_hw_entropy(void) { memzero(HW_ENTROPY_DATA, HW_ENTROPY_LEN); }

core/embed/unix/common.h

@@ -56,6 +56,7 @@ error_shutdown(const char *line1, const char *line2, const char *line3,
        : __fatal_error(#expr, msg, __FILE__, __LINE__, __func__))
 
 void hal_delay(uint32_t ms);
+void wait_random(void);
 
 void collect_hw_entropy(void);
 #define HW_ENTROPY_LEN (12 + 32)