chore(legacy): drop support for RANDOM_DEV_FILE

Replacing it with trezor-crypto's na(t)ive RNG, which we can reseed over
debuglink.

legacy/Makefile.include

@@ -75,7 +75,6 @@ CFLAGS   += $(OPTFLAGS) \
             $(FPUFLAGS) \
             $(CONFFLAG) \
             -DSTM32F2 \
-            -DRAND_PLATFORM_INDEPENDENT=1 \
             -I$(TOOLCHAIN_DIR)/include \
             -I$(TOP_DIR) \
             -I$(TOP_DIR)gen \
@@ -105,10 +104,6 @@ LIBDEPS  += $(TOP_DIR)/libtrezor.a $(TOP_DIR)emulator/libemulator.a
 CFLAGS   += $(shell pkg-config --cflags sdl2 SDL2_image)
 LDLIBS   += $(shell pkg-config --libs sdl2 SDL2_image)
 
-ifdef RANDOM_DEV_FILE
-CFLAGS += -DRANDOM_DEV_FILE=\"$(RANDOM_DEV_FILE)\"
-endif
-
 else
 ifdef APPVER
 CFLAGS   += -DAPPVER=$(APPVER)
@@ -118,6 +113,7 @@ LDSCRIPT  = $(TOP_DIR)/memory.ld
 endif
 
 CFLAGS   += -DEMULATOR=0
+CFLAGS   += -DRAND_PLATFORM_INDEPENDENT=1
 
 LDFLAGS  += --static \
             -Wl,--start-group \

legacy/emulator/Makefile

@@ -5,7 +5,6 @@ OBJS += setup.o
 OBJS += buttons.o
 OBJS += memory.o
 OBJS += oled.o
-OBJS += rng.o
 OBJS += timer.o
 OBJS += udp.o
 

legacy/emulator/emulator.h

@@ -27,7 +27,6 @@
 #include <stddef.h>
 
 void emulatorPoll(void);
-void emulatorRandom(void *buffer, size_t size);
 
 void emulatorSocketInit(void);
 size_t emulatorSocketRead(int *iface, void *buffer, size_t size,

legacy/emulator/rng.c

@@ -1,32 +0,0 @@
-/*
- * This file is part of the Trezor project, https://trezor.io/
- *
- * Copyright (C) 2017 Saleem Rashid <trezor@saleemrashid.com>
- *
- * This library is free software: you can redistribute it and/or modify
- * it under the terms of the GNU Lesser General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public License
- * along with this library.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "rng.h"
-
-uint32_t random32(void) {
-  static uint32_t last = 0;
-  uint32_t new = 0;
-
-  do {
-    emulatorRandom(&new, sizeof(new));
-  } while (last == new);
-
-  last = new;
-  return new;
-}

legacy/emulator/setup.c

@@ -34,49 +34,19 @@
 
 #define EMULATOR_FLASH_FILE "emulator.img"
 
-#ifndef RANDOM_DEV_FILE
-#define RANDOM_DEV_FILE "/dev/urandom"
-#endif
-
 uint8_t *emulator_flash_base = NULL;
 
 uint32_t __stack_chk_guard;
 
-static int random_fd = -1;
-
-static void setup_urandom(void);
 static void setup_flash(void);
 
-void setup(void) {
+void setup(void) { setup_flash(); }
-  setup_urandom();
-  setup_flash();
-}
 
 void __attribute__((noreturn)) shutdown(void) {
   sleep(5);
   exit(4);
 }
 
-void emulatorRandom(void *buffer, size_t size) {
-  ssize_t n = 0, len = 0;
-  do {
-    n = read(random_fd, (char *)buffer + len, size - len);
-    if (n < 0) {
-      perror("Failed to read " RANDOM_DEV_FILE);
-      exit(1);
-    }
-    len += n;
-  } while (len != (ssize_t)size);
-}
-
-static void setup_urandom(void) {
-  random_fd = open(RANDOM_DEV_FILE, O_RDONLY);
-  if (random_fd < 0) {
-    perror("Failed to open " RANDOM_DEV_FILE);
-    exit(1);
-  }
-}
-
 static void setup_flash(void) {
   int fd = open(EMULATOR_FLASH_FILE, O_RDWR | O_SYNC | O_CREAT, 0644);
   if (fd < 0) {

legacy/firmware/.changelog.d/2115.removed

@@ -0,0 +1 @@
+\[emulator] Removed support for /dev/urandom or custom entropy source.