Make anti-replay a runtime option

include/polarssl/ssl.h

@@ -229,6 +229,9 @@
 #define SSL_RENEGOTIATION_DISABLED      0
 #define SSL_RENEGOTIATION_ENABLED       1
 
+#define SSL_ANTI_REPLAY_DISABLED        0
+#define SSL_ANTI_REPLAY_ENABLED         1
+
 #define SSL_RENEGOTIATION_NOT_ENFORCED  -1
 #define SSL_RENEGO_MAX_RECORDS_DEFAULT  16
 
@@ -828,6 +831,7 @@ struct _ssl_context
 #if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
     uint64_t in_window_top;     /*!< last validated record seq_num    */
     uint64_t in_window;         /*!< bitmask for replay detection     */
+    char anti_replay;           /*!< is anti-replay on?               */
 #endif
 
     size_t in_hslen;            /*!< current handshake message length,
@@ -1246,6 +1250,19 @@ void ssl_set_dtls_cookies( ssl_context *ssl,
                            void *p_cookie );
 #endif /* POLARSSL_SSL_DTLS_HELLO_VERIFY */
 
+#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
+/**
+ * \brief          Enable or disable anti-replay protection for DTLS.
+ *                 (DTLS only, no effect on TLS.)
+ *                 Default: enebled.
+ *
+ * \param ssl      SSL context
+ * \param mode     SSL_ANTI_REPLAY_ENABLED or SSL_ANTI_REPLAY_DISABLED.
+ */
+void ssl_set_dtls_anti_replay( ssl_context *ssl, char mode );
+#endif /* POLARSSL_SSL_DTLS_ANTI_REPLAY */
+
+
 /**
  * \brief          Set the session cache callbacks (server-side only)
  *                 If not set, no session resuming is done.

library/ssl_tls.c

@@ -2733,6 +2733,9 @@ int ssl_dtls_replay_check( ssl_context *ssl )
     uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
     uint64_t bit;
 
+    if( ssl->anti_replay == SSL_ANTI_REPLAY_DISABLED )
+        return( 0 );
+
     if( rec_seqnum > ssl->in_window_top )
         return( 0 );
 
@@ -2754,6 +2757,9 @@ void ssl_dtls_replay_update( ssl_context *ssl )
 {
     uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
 
+    if( ssl->anti_replay == SSL_ANTI_REPLAY_DISABLED )
+        return;
+
     if( rec_seqnum > ssl->in_window_top )
     {
         /* Update window_top and the contents of the window */
@@ -4528,6 +4534,10 @@ int ssl_init( ssl_context *ssl )
     ssl->f_cookie_check = ssl_cookie_check_dummy;
 #endif
 
+#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
+    ssl->anti_replay = SSL_ANTI_REPLAY_ENABLED;
+#endif
+
     if( ( ret = ssl_handshake_init( ssl ) ) != 0 )
         return( ret );
 
@@ -4745,6 +4755,13 @@ int ssl_set_transport( ssl_context *ssl, int transport )
     return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
 }
 
+#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
+void ssl_set_dtls_anti_replay( ssl_context *ssl, char mode )
+{
+    ssl->anti_replay = mode;
+}
+#endif
+
 void ssl_set_authmode( ssl_context *ssl, int authmode )
 {
     ssl->authmode   = authmode;

programs/ssl/ssl_server2.c

@@ -122,6 +122,7 @@ int main( int argc, char *argv[] )
 #define DFL_DHM_FILE            NULL
 #define DFL_TRANSPORT           SSL_TRANSPORT_STREAM
 #define DFL_COOKIES             1
+#define DFL_ANTI_REPLAY         -1
 
 #define LONG_RESPONSE "<p>01-blah-blah-blah-blah-blah-blah-blah-blah-blah\r\n" \
     "02-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah-blah\r\n"  \
@@ -184,6 +185,7 @@ struct options
     const char *dhm_file;       /* the file with the DH parameters          */
     int transport;              /* TLS or DTLS?                             */
     int cookies;                /* Use cookies for DTLS? -1 to break them   */
+    int anti_replay;            /* Use anti-replay for DTLS? -1 for default */
 } opt;
 
 static void my_debug( void *ctx, int level, const char *str )
@@ -310,11 +312,18 @@ static int my_send( void *ctx, const unsigned char *buf, size_t len )
 #if defined(POLARSSL_SSL_DTLS_HELLO_VERIFY)
 #define USAGE_COOKIES \
     "    cookies=0/1/-1      default: 1 (enabled)\n"        \
-    "                        0: disabled, -1: broken\n"
+    "                        0: disabled, -1: library default (broken)\n"
 #else
 #define USAGE_COOKIES ""
 #endif
 
+#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
+#define USAGE_ANTI_REPLAY \
+    "    anti_replay=0/1      default: (library default = enabled)\n"
+#else
+#define USAGE_ANTI_REPLAY ""
+#endif
+
 #define USAGE \
     "\n usage: ssl_server2 param=<>...\n"                   \
     "\n acceptable parameters:\n"                           \
@@ -340,6 +349,7 @@ static int my_send( void *ctx, const unsigned char *buf, size_t len )
     USAGE_TICKETS                                           \
     USAGE_CACHE                                             \
     USAGE_COOKIES                                           \
+    USAGE_ANTI_REPLAY                                       \
     USAGE_MAX_FRAG_LEN                                      \
     USAGE_ALPN                                              \
     "\n"                                                    \
@@ -740,6 +750,7 @@ int main( int argc, char *argv[] )
     opt.dhm_file            = DFL_DHM_FILE;
     opt.transport           = DFL_TRANSPORT;
     opt.cookies             = DFL_COOKIES;
+    opt.anti_replay         = DFL_ANTI_REPLAY;
 
     for( i = 1; i < argc; i++ )
     {
@@ -963,6 +974,12 @@ int main( int argc, char *argv[] )
             if( opt.cookies < -1 || opt.cookies > 1)
                 goto usage;
         }
+        else if( strcmp( p, "anti_replay" ) == 0 )
+        {
+            opt.anti_replay = atoi( q );
+            if( opt.anti_replay < 0 || opt.anti_replay > 1)
+                goto usage;
+        }
         else if( strcmp( p, "sni" ) == 0 )
         {
             opt.sni = q;
@@ -1400,6 +1417,13 @@ int main( int argc, char *argv[] )
         {
             ; /* Nothing to do */
         }
+
+#if defined(POLARSSL_SSL_DTLS_ANTI_REPLAY)
+        if( opt.anti_replay != DFL_ANTI_REPLAY )
+        {
+            ssl_set_dtls_anti_replay( &ssl, opt.anti_replay );
+        }
+#endif
     }
 #endif /* POLARSSL_SSL_PROTO_DTLS */
 

tests/ssl-opt.sh

@@ -2133,6 +2133,18 @@ run_test    "DTLS proxy: duplicate every packet" \
             -s "Extra-header:" \
             -c "HTTP/1.0 200 OK"
 
+run_test    "DTLS proxy: duplicate every packet, server anti-replay off" \
+            -p "$P_PXY duplicate=1" \
+            "$P_SRV dtls=1 debug_level=1 anti_replay=0" \
+            "$P_CLI dtls=1 debug_level=1" \
+            0 \
+            -c "replayed record" \
+            -S "replayed record" \
+            -c "discarding invalid record" \
+            -s "discarding invalid record" \
+            -s "Extra-header:" \
+            -c "HTTP/1.0 200 OK"
+
 run_test    "DTLS proxy: inject invalid AD record" \
             -p "$P_PXY bad_ad=1" \
             "$P_SRV dtls=1 debug_level=1" \