[add] Fetch RNG from env at startup then stick with it

LedgerHQ · Dec 19, 2023 · dc9fe08 · dc9fe08
1 parent f347988
commit dc9fe08
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Showing 12 changed files with 60 additions and 47 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -8,8 +8,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [0.5.0] - 2024-??-??
 
 ### Added
-- Seed is fetched from the environment during the Speculos launch and stored internally for further
-  use. This avoids several Speculos instances from messing up with each other's seeds.
+- Seed, RNG are fetched from the environment during the Speculos launch and stored internally for
+  further use. This avoids several Speculos instances from messing up with each other's environment
+  variables.
 
 ## [0.4.1] - 2023-12-19
 

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
@@ -56,7 +56,7 @@ add_library(emu
         emulate_blue_2.2.5.c
         emulate_lnsp_1.0.c
         emulate_unified_sdk.c
-        seed.c
+        environment.c
         svc.c)
 
 add_dependencies(emu openssl)

diff --git a/src/bolos/cx.c b/src/bolos/cx.c
@@ -4,32 +4,20 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <time.h>
 #include <unistd.h>
 
 #include "emulate.h"
+#include "environment.h"
 
 static bool initialized = false;
 
-static unsigned int get_rng_seed_from_env(const char *name)
-{
-  char *p;
-
-  p = getenv(name);
-  if (p != NULL) {
-    return atoi(p);
-  } else {
-    return time(NULL);
-  }
-}
-
 /* not secure, but this is clearly not the goal of this emulator */
 unsigned long sys_cx_rng(uint8_t *buffer, unsigned int length)
 {
   unsigned int i;
 
   if (!initialized) {
-    srand(get_rng_seed_from_env("RNG_SEED"));
+    srand(get_env_rng());
     initialized = true;
   }
 

diff --git a/src/bolos/os_bip32.c b/src/bolos/os_bip32.c
@@ -9,7 +9,7 @@
 #include "cx.h"
 #include "cx_utils.h"
 #include "emulate.h"
-#include "seed.h"
+#include "environment.h"
 
 #define BIP32_HARDEN_MASK      0x80000000
 #define BIP32_SECP_SEED_LENGTH 12
@@ -444,7 +444,7 @@ unsigned long sys_os_perso_derive_node_with_seed_key(
     sk_length = seed_key_length;
   }
 
-  seed_size = get_seed(seed, sizeof(seed));
+  seed_size = get_env_seed(seed, sizeof(seed));
 
   if (mode == HDW_SLIP21) {
     ret = hdw_slip21(sk, sk_length, seed, seed_size, (const uint8_t *)path,

diff --git a/src/bolos/os_eip2333.c b/src/bolos/os_eip2333.c
@@ -6,8 +6,8 @@
 #include "cx.h"
 #include "cx_utils.h"
 #include "emulate.h"
+#include "environment.h"
 #include "exception.h"
-#include "seed.h"
 
 #define MAX_SEED_SIZE          64
 #define CX_SHA256_SIZE         32
@@ -142,7 +142,7 @@ unsigned long sys_os_perso_derive_eip2333(cx_curve_t curve,
     THROW(EXCEPTION);
   }
 
-  seed_size = get_seed(seed, sizeof(seed));
+  seed_size = get_env_seed(seed, sizeof(seed));
 
   cx_derive_master_sk(seed, seed_size, sk);
   if (privateKey != NULL) {

diff --git a/src/seed.c → src/environment.c b/src/seed.c → src/environment.c
@@ -3,8 +3,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <time.h>
 
-#include "seed.h"
+#include "environment.h"
 
 /* glory promote mansion idle axis finger extra february uncover one trip
  * resource lawn turtle enact monster seven myth punch hobby comfort wild raise
@@ -16,11 +17,13 @@ static uint8_t default_seed[MAX_SEED_SIZE] =
     "\x11\x44\x13\x2f\x35\xe2\x06\x87\x35\x64";
 
 const char *SEED_ENV_NAME = "SPECULOS_SEED";
-typedef struct {
+const char *RNG_ENV_NAME = "RNG_SEED";
+
+static struct {
   size_t size;
   uint8_t seed[MAX_SEED_SIZE];
-} seed_t;
-static seed_t actual_seed = { 0 };
+} actual_seed = { 0 };
+static unsigned int actual_rng = 0;
 
 static int unhex(uint8_t *dst, size_t dst_size, const char *src,
                  size_t src_size)
@@ -59,7 +62,7 @@ static int unhex(uint8_t *dst, size_t dst_size, const char *src,
   return src_size / 2;
 }
 
-void init_seed()
+void init_env_seed()
 {
   ssize_t size;
   char *p;
@@ -86,8 +89,25 @@ void init_seed()
   actual_seed.size = size;
 }
 
-size_t get_seed(uint8_t *seed, size_t max_size)
+size_t get_env_seed(uint8_t *seed, size_t max_size)
 {
   memcpy(seed, actual_seed.seed, max_size);
   return (actual_seed.size < max_size) ? actual_seed.size : max_size;
 }
+
+void init_env_rng()
+{
+  char *p;
+  p = getenv(RNG_ENV_NAME);
+  if (p != NULL) {
+    actual_rng = atoi(p);
+    fprintf(stderr, "[*] Seed initialized from environment: '%ud'\n", actual_rng);
+  } else {
+    actual_rng = time(NULL);
+    fprintf(stderr, "[*] Seed initialized by default: '%ud'\n", actual_rng);
+  }
+}
+
+unsigned int get_env_rng() {
+  return actual_rng;
+}
diff --git a/src/environment.h b/src/environment.h
@@ -0,0 +1,11 @@
+#pragma once
+
+#include <stdint.h>
+
+#define MAX_SEED_SIZE 64
+
+void init_env_seed();
+size_t get_env_seed(uint8_t *seed, size_t max_size);
+
+void init_env_rng();
+unsigned int get_env_rng();
diff --git a/src/launcher.c b/src/launcher.c
@@ -13,8 +13,8 @@
 #include <unistd.h>
 
 #include "emulate.h"
+#include "environment.h"
 #include "fonts.h"
-#include "seed.h"
 #include "svc.h"
 
 #define LOAD_ADDR     ((void *)0x40000000)
@@ -723,7 +723,8 @@ int main(int argc, char *argv[])
   extra_rampage_size = 0;
 
   fprintf(stderr, "[*] speculos launcher revision: " GIT_REVISION "\n");
-  init_seed();
+  init_env_seed();
+  init_env_rng();
 
   while ((opt = getopt(argc, argv, "c:tr:s:m:k:a:f:")) != -1) {
     switch (opt) {

diff --git a/src/seed.h b/src/seed.h
diff --git a/tests/syscalls/test_bip32.c b/tests/syscalls/test_bip32.c
@@ -11,7 +11,7 @@
 #include "bolos/cx_utils.h"
 #include "bolos/os_bip32.h"
 #include "emulate.h"
-#include "seed.h"
+#include "environment.h"
 #include "utils.h"
 
 #define MAX_CHAIN_LEN 5
@@ -579,7 +579,7 @@ static void test_bip32_vector(const bip32_test_vector *v)
   memset(&extkey, 0, sizeof(extkey));
 
   assert_int_equal(setenv("SPECULOS_SEED", v->seed, 1), 0);
-  init_seed();
+  init_env_seed();
 
   for (i = 0; i < v->chain_len; i++) {
     path[i] = v->chain[i].index;
@@ -601,7 +601,7 @@ static void test_bip32_vector(const bip32_test_vector *v)
 static void test_bip32(void **state __attribute__((unused)))
 {
   size_t i;
-  init_seed();
+  init_env_seed();
   for (i = 0; i < ARRAY_SIZE(test_vectors); i++) {
     test_bip32_vector(&test_vectors[i]);
   }
@@ -616,7 +616,7 @@ static void test_bolos_vector(const struct bolos_vector *v)
   size_t sk_length;
   ssize_t path_len;
   uint8_t *p;
-  init_seed();
+  init_env_seed();
 
   switch (v->mode) {
   case 0:

diff --git a/tests/syscalls/test_eip2333.c b/tests/syscalls/test_eip2333.c
@@ -11,7 +11,7 @@
 #include "bolos/cx.h"
 #include "bolos/cx_utils.h"
 #include "emulate.h"
-#include "seed.h"
+#include "environment.h"
 #include "utils.h"
 
 #define MAX_PATH_LEN 10
@@ -229,7 +229,7 @@ static void test_eip_vector(const eip2333_test_vector *v)
   int path_len;
 
   assert_int_equal(setenv("SPECULOS_SEED", v->seed, 1), 0);
-  init_seed();
+  init_env_seed();
 
   path_len = get_path(v->path, path, MAX_PATH_LEN);
   assert_int_equal(path_len, 1);
@@ -247,7 +247,7 @@ static void test_eip2333_derive(void **state __attribute__((unused)))
   unsigned int i;
 
   assert_int_equal(setenv("SPECULOS_SEED", default_seed, 1), 0);
-  init_seed();
+  init_env_seed();
 
   for (i = 0; i < ARRAY_SIZE(test_vectors); i++) {
     test_eip_vector(&test_vectors[i]);
@@ -260,7 +260,7 @@ static void test_bolos_vector(const bolos_test_vector *v)
   unsigned int path[10];
   int path_len;
 
-  init_seed();
+  init_env_seed();
   path_len = get_path(v->path, path, MAX_PATH_LEN);
   assert_int_equal(path_len, v->path_len);
 

diff --git a/tests/syscalls/test_slip21.c b/tests/syscalls/test_slip21.c
@@ -9,7 +9,7 @@
 #include "bolos/cx.h"
 #include "bolos/os_bip32.h"
 #include "emulate.h"
-#include "seed.h"
+#include "environment.h"
 
 void test_slip21(void **state __attribute__((unused)))
 {
@@ -31,7 +31,7 @@ void test_slip21(void **state __attribute__((unused)))
              1),
       0);
 
-  init_seed();
+  init_env_seed();
 
   sys_os_perso_derive_node_with_seed_key(HDW_SLIP21, CX_CURVE_SECP256K1,
                                          (uint32_t *)SLIP77_LABEL, 10, key,