Use crypto safe random numbers

configure.ac

@@ -954,6 +954,8 @@ AS_IF([test "x$enable_post_processing" = "xyes"],
                          [
                            glib-2.0 >= $glib_version
                            jansson >= $jansson_version
+                           libssl >= $ssl_version
+                           libcrypto
                            libavutil
                            libavcodec
                            libavformat

fuzzers/rtcp_fuzzer.c

@@ -13,6 +13,11 @@ gboolean janus_log_colors = FALSE;
 char *janus_log_global_prefix = NULL;
 int lock_debug = 0;
 
+/* This is to avoid linking with openSSL */
+int RAND_bytes(uint8_t *key, int len) {
+	return 0;
+}
+
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 	/* Sanity Checks */
 	/* Max UDP payload with MTU=1500 */

fuzzers/sdp_fuzzer.c

@@ -14,6 +14,11 @@ char *janus_log_global_prefix = NULL;
 int lock_debug = 0;
 int refcount_debug = 0;
 
+/* This is to avoid linking with openSSL */
+int RAND_bytes(uint8_t *key, int len) {
+	return 0;
+}
+
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 	/* Since we're fuzzing SDP, and that in our case SDP always comes
 	 * from a Jansson call, this will need to be a valid string */

janus.c

@@ -4996,6 +4996,11 @@ gint main(int argc, char *argv[])
 	SSL_library_init();
 	SSL_load_error_strings();
 	OpenSSL_add_all_algorithms();
+	/* check if random pool looks ok (this does not give any guarantees for later, though) */
+	if(RAND_status() != 1) {
+		JANUS_LOG(LOG_FATAL, "\tOpenSSL PRNG is not properly seeded, cannot generate random numbers\n");
+		exit(1);
+	}
 	/* ... and DTLS-SRTP in particular */
 	const char *dtls_ciphers = NULL;
 	item = janus_config_get(config, config_certs, janus_config_type_item, "dtls_ciphers");

plugins/janus_nosip.c

@@ -786,11 +786,6 @@ int janus_nosip_init(janus_callbacks *callback, const char *config_path) {
 	}
 	JANUS_LOG(LOG_VERB, "Local IP set to %s\n", local_ip);
 
-#ifdef HAVE_SRTP_2
-	/* Init randomizer (for randum numbers in SRTP) */
-	RAND_poll();
-#endif
-
 	sessions = g_hash_table_new_full(NULL, NULL, NULL, (GDestroyNotify)janus_nosip_session_destroy);
 	messages = g_async_queue_new_full((GDestroyNotify) janus_nosip_message_free);
 	/* This is the callback we'll need to invoke to contact the Janus core */

plugins/janus_sip.c

@@ -1924,11 +1924,6 @@ int janus_sip_init(janus_callbacks *callback, const char *config_path) {
 	}
 	JANUS_LOG(LOG_VERB, "Local IP set to %s\n", local_ip);
 
-#ifdef HAVE_SRTP_2
-	/* Init randomizer (for randum numbers in SRTP) */
-	RAND_poll();
-#endif
-
 	/* Setup sofia */
 	su_init();
 	if(notify_events && callback->events_is_enabled()) {

utils.c

@@ -21,6 +21,7 @@
 #include <inttypes.h>
 
 #include <zlib.h>
+#include <openssl/rand.h>
 
 #include "utils.h"
 #include "debug.h"
@@ -71,23 +72,25 @@ gboolean janus_strcmp_const_time(const void *str1, const void *str2) {
 }
 
 guint32 janus_random_uint32(void) {
-	return g_random_int();
+	guint32 ret = 0;
+	if (RAND_bytes((void *)&ret, sizeof(ret)) != 1) {
+		JANUS_LOG(LOG_FATAL, "\tOpenSSL RAND_bytes() failed\n");
+		exit(1);
+	}
+	return ret;
+}
+
+guint64 janus_random_uint64_full(void) {
+	guint64 ret = 0;
+	if (RAND_bytes((void *)&ret, sizeof(ret)) != 1) {
+		JANUS_LOG(LOG_FATAL, "\tOpenSSL RAND_bytes() failed\n");
+		exit(1);
+	}
+	return ret;
 }
 
 guint64 janus_random_uint64(void) {
-	/*
-	 * FIXME This needs to be improved, and use something that generates
-	 * more strongly random stuff... using /dev/urandom is probably not
-	 * a good idea, as we don't want to make it harder to cross compile Janus
-	 *
-	 * TODO Look into what libssl and/or libcrypto provide in that respect
-	 *
-	 * PS: JavaScript only supports integer up to 2^53, so we need to
-	 * make sure the number is below 9007199254740992 for safety
-	 */
-	guint64 num = g_random_int() & 0x1FFFFF;
-	num = (num << 32) | g_random_int();
-	return num;
+	return janus_random_uint64_full() & 0x1FFFFFFFFFFFFF;
 }
 
 char *janus_random_uuid(void) {
@@ -100,8 +103,8 @@ char *janus_random_uuid(void) {
 	const char *template = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";
 	const char *samples = "0123456789abcdef";
 	union { unsigned char b[16]; uint64_t word[2]; } rnd;
-	rnd.word[0] = janus_random_uint64();
-	rnd.word[1] = janus_random_uint64();
+	rnd.word[0] = janus_random_uint64_full();
+	rnd.word[1] = janus_random_uint64_full();
 	/* Generate the string */
 	char uuid[37], *dst = uuid;
 	const char *p = template;

utils.h

@@ -62,15 +62,29 @@ gboolean janus_strcmp_const_time(const void *str1, const void *str2);
 
 /*! \brief Helper to generate random 32-bit unsigned integers (useful for SSRCs, etc.)
  * @note Currently just wraps g_random_int()
- * @returns A random 32-bit unsigned integer */
+ * @returns A (crypto-safe) random 32-bit unsigned integer */
 guint32 janus_random_uint32(void);
 
-/*! \brief Helper to generate random 64-bit unsigned integers (useful for Janus IDs)
+/*! \brief Helper to generate random 64-bit unsigned integers
+ * @note Unlike janus_random_uint64(), which actually only generates 52 bits, this
+ * generates the full 64 bits. See the janus_random_uint64() docstring for details.
  * @returns A random 64-bit unsigned integer */
+guint64 janus_random_uint64_full(void);
+
+/*! \brief Helper to generate random 52 bit unsigned integers
+ * @note The reason for 52 instead of 64 bits: Javascript does not have real integers,
+ * its builtin "number" type is a float64. Thus, only integer values up to
+ * Number.MAX_SAFE_INTEGER == 2^53 - 1 == 9007199254740991
+ * can be safely represented in Javascript. This method returns such numbers.
+ * Use this method instead of janus_random_uint64_full() whenever you generate numbers which
+ * might end up in Javascript (via JSON API).
+ * This method is called janus_random_uint64() instead of janus_random_uint52() (or similar)
+ * for backwards compatibility.
+ * @returns A (crypto-safe) random 64-bit unsigned integer */
 guint64 janus_random_uint64(void);
 
 /*! \brief Helper to generate random UUIDs (needed by some plugins)
- * @returns A random UUID string, which must be deallocated with \c g_free */
+ * @returns A (crypto-safe) random UUID string, which must be deallocated with \c g_free */
 char *janus_random_uuid(void);
 
 /*! \brief Helper to generate an allocated copy of a guint64 number