firmware: use OTP block 3 for storing randomness

embed/bootloader/main.c

@@ -187,11 +187,9 @@ secbool load_vendor_header_keys(const uint8_t * const data, vendor_header * cons
     return load_vendor_header(data, BOOTLOADER_KEY_M, BOOTLOADER_KEY_N, BOOTLOADER_KEYS, vhdr);
 }
 
-#define OTP_BLOCK_VENDOR_KEYS_LOCK 2
-
 static secbool check_vendor_keys_lock(const vendor_header * const vhdr) {
     uint8_t lock[FLASH_OTP_BLOCK_SIZE];
-    ensure(flash_otp_read(OTP_BLOCK_VENDOR_KEYS_LOCK, 0, lock, FLASH_OTP_BLOCK_SIZE), NULL);
+    ensure(flash_otp_read(FLASH_OTP_BLOCK_VENDOR_KEYS_LOCK, 0, lock, FLASH_OTP_BLOCK_SIZE), NULL);
     if (0 == memcmp(lock, "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF", FLASH_OTP_BLOCK_SIZE)) {
         return sectrue;
     }
@@ -204,8 +202,6 @@ static secbool check_vendor_keys_lock(const vendor_header * const vhdr) {
 
 #if PRODUCTION
 
-#define OTP_BLOCK_BOOTLOADER_VERSION 1
-
 static void check_bootloader_version(void)
 {
     uint8_t bits[FLASH_OTP_BLOCK_SIZE];
@@ -216,10 +212,10 @@ static void check_bootloader_version(void)
              bits[i / 8] |= (1 << (7 - (i % 8)));
         }
     }
-    ensure(flash_otp_write(OTP_BLOCK_BOOTLOADER_VERSION, 0, bits, FLASH_OTP_BLOCK_SIZE), NULL);
+    ensure(flash_otp_write(FLASH_OTP_BLOCK_BOOTLOADER_VERSION, 0, bits, FLASH_OTP_BLOCK_SIZE), NULL);
 
     uint8_t bits2[FLASH_OTP_BLOCK_SIZE];
-    ensure(flash_otp_read(OTP_BLOCK_BOOTLOADER_VERSION, 0, bits2, FLASH_OTP_BLOCK_SIZE), NULL);
+    ensure(flash_otp_read(FLASH_OTP_BLOCK_BOOTLOADER_VERSION, 0, bits2, FLASH_OTP_BLOCK_SIZE), NULL);
 
     ensure(sectrue * (0 == memcmp(bits, bits2, FLASH_OTP_BLOCK_SIZE)), "Bootloader downgraded");
 }

embed/extmod/modtrezorio/modtrezorio-flash.h

@@ -89,7 +89,7 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorio_FlashOTP_lock_obj, mod_trezorio_Fl
 ///     '''
 STATIC mp_obj_t mod_trezorio_FlashOTP_is_locked(mp_obj_t self, mp_obj_t block) {
     uint8_t b = trezor_obj_get_uint8(block);
-    return flash_otp_is_locked(b) ? mp_const_true : mp_const_false;
+    return (sectrue == flash_otp_is_locked(b)) ? mp_const_true : mp_const_false;
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_trezorio_FlashOTP_is_locked_obj, mod_trezorio_FlashOTP_is_locked);
 

embed/prodtest/main.c

@@ -328,7 +328,7 @@ static void test_otp_read(void)
 {
     uint8_t data[32];
     memzero(data, sizeof(data));
-    ensure(flash_otp_read(0, 0, data, sizeof(data)), NULL);
+    ensure(flash_otp_read(FLASH_OTP_BLOCK_BATCH, 0, data, sizeof(data)), NULL);
 
     // strip trailing 0xFF
     for (size_t i = 0; i < sizeof(data); i++) {
@@ -351,7 +351,7 @@ static void test_otp_write(const char *args)
     char data[32];
     memzero(data, sizeof(data));
     strncpy(data, args, sizeof(data) - 1);
-    ensure(flash_otp_write(0, 0, (const uint8_t *) data, sizeof(data)), NULL);
+    ensure(flash_otp_write(FLASH_OTP_BLOCK_BATCH, 0, (const uint8_t *) data, sizeof(data)), NULL);
     ensure(flash_otp_lock(0), NULL);
     vcp_printf("OK");
 }
@@ -376,7 +376,7 @@ int main(void)
 
     char dom[32];
     // format: TREZOR2-YYMMDD
-    if (sectrue == flash_otp_read(0, 0, (uint8_t *)dom, 32) && 0 == memcmp(dom, "TREZOR2-", 8) && dom[31] == 0) {
+    if (sectrue == flash_otp_read(FLASH_OTP_BLOCK_BATCH, 0, (uint8_t *)dom, 32) && 0 == memcmp(dom, "TREZOR2-", 8) && dom[31] == 0) {
         display_qrcode(DISPLAY_RESX / 2, DISPLAY_RESY / 2, dom, strlen(dom), 4);
         display_text_center(DISPLAY_RESX / 2, DISPLAY_RESY - 30, dom + 8, -1, FONT_BOLD, COLOR_WHITE, COLOR_BLACK);
     }

embed/trezorhal/common.c

@@ -24,6 +24,8 @@
 #include "common.h"
 #include "display.h"
 #include "rng.h"
+#include "rand.h"
+#include "flash.h"
 
 #include "stm32f4xx_ll_utils.h"
 
@@ -136,10 +138,20 @@ uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
 
 void collect_hw_entropy(void)
 {
+    // collect entropy from UUID
     uint32_t w = LL_GetUID_Word0();
     memcpy(HW_ENTROPY_DATA, &w, 4);
     w = LL_GetUID_Word1();
     memcpy(HW_ENTROPY_DATA + 4, &w, 4);
     w = LL_GetUID_Word2();
     memcpy(HW_ENTROPY_DATA + 8, &w, 4);
+
+    // set entropy in the OTP randomness block
+    if (secfalse == flash_otp_is_locked(FLASH_OTP_BLOCK_RANDOMNESS)) {
+        uint8_t entropy[FLASH_OTP_BLOCK_SIZE];
+        random_buffer(entropy, FLASH_OTP_BLOCK_SIZE);
+        ensure(flash_otp_write(FLASH_OTP_BLOCK_RANDOMNESS, 0, entropy, FLASH_OTP_BLOCK_SIZE), NULL);
+    }
+    // collect entropy from OTP randomness block
+    ensure(flash_otp_read(FLASH_OTP_BLOCK_RANDOMNESS, 0, HW_ENTROPY_DATA + 12, FLASH_OTP_BLOCK_SIZE), NULL);
 }

embed/trezorhal/common.h

@@ -45,7 +45,7 @@ void clear_otg_hs_memory(void);
 extern uint32_t __stack_chk_guard;
 
 void collect_hw_entropy(void);
-#define HW_ENTROPY_LEN 12
+#define HW_ENTROPY_LEN (12 + 32)
 extern uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
 
 // the following functions are defined in util.s

embed/trezorhal/flash.c

@@ -197,5 +197,5 @@ secbool flash_otp_lock(uint8_t block)
 
 secbool flash_otp_is_locked(uint8_t block)
 {
-    return *(__IO uint8_t *)(FLASH_OTP_LOCK_BASE + block) == 0x00;
+    return sectrue * (0x00 == *(__IO uint8_t *)(FLASH_OTP_LOCK_BASE + block));
 }

embed/trezorhal/flash.h

@@ -82,6 +82,12 @@ secbool __wur flash_write_word(uint8_t sector, uint32_t offset, uint32_t data);
 #define FLASH_OTP_NUM_BLOCKS      16
 #define FLASH_OTP_BLOCK_SIZE      32
 
+// OTP blocks allocation
+#define FLASH_OTP_BLOCK_BATCH                 0
+#define FLASH_OTP_BLOCK_BOOTLOADER_VERSION    1
+#define FLASH_OTP_BLOCK_VENDOR_KEYS_LOCK      2
+#define FLASH_OTP_BLOCK_RANDOMNESS            3
+
 secbool __wur flash_otp_read(uint8_t block, uint8_t offset, uint8_t *data, uint8_t datalen);
 secbool __wur flash_otp_write(uint8_t block, uint8_t offset, const uint8_t *data, uint8_t datalen);
 secbool __wur flash_otp_lock(uint8_t block);

embed/unix/common.h

@@ -41,7 +41,7 @@ void __attribute__((noreturn)) error_shutdown(const char *line1, const char *lin
 void hal_delay(uint32_t ms);
 
 void collect_hw_entropy(void);
-#define HW_ENTROPY_LEN 12
+#define HW_ENTROPY_LEN (12 + 32)
 extern uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
 
 #endif