Add negative test for hard reconnect cookie check
The server must check client reachability (we chose to do that by checking a
cookie) before destroying the existing association (RFC 6347 section 4.2.8).
Let's make sure we do, by having a proxy-in-the-middle inject a ClientHello -
the server should notice, but not destroy the connection.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index e96e91b..bca53c0 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -130,6 +130,7 @@
" bad_ad=0/1 default: 0 (don't add bad ApplicationData)\n" \
" protect_hvr=0/1 default: 0 (don't protect HelloVerifyRequest)\n" \
" protect_len=%%d default: (don't protect packets of this size)\n" \
+ " inject_clihlo=0/1 default: 0 (don't inject fake ClientHello)\n" \
"\n" \
" seed=%%d default: (use current time)\n" \
USAGE_PACK \
@@ -162,6 +163,7 @@
int bad_ad; /* inject corrupted ApplicationData record */
int protect_hvr; /* never drop or delay HelloVerifyRequest */
int protect_len; /* never drop/delay packet of the given size*/
+ int inject_clihlo; /* inject fake ClientHello after handshake */
unsigned pack; /* merge packets into single datagram for
* at most \c merge milliseconds if > 0 */
unsigned int seed; /* seed for "random" events */
@@ -304,6 +306,12 @@
if( opt.protect_len < 0 )
exit_usage( p, q );
}
+ else if( strcmp( p, "inject_clihlo" ) == 0 )
+ {
+ opt.inject_clihlo = atoi( q );
+ if( opt.inject_clihlo < 0 || opt.inject_clihlo > 1 )
+ exit_usage( p, q );
+ }
else if( strcmp( p, "seed" ) == 0 )
{
opt.seed = atoi( q );
@@ -503,11 +511,40 @@
fflush( stdout );
}
+/*
+ * In order to test the server's behaviour when receiving a ClientHello after
+ * the connection is established (this could be a hard reset from the client,
+ * but the server must not drop the existing connection before establishing
+ * client reachability, see RFC 6347 Section 4.2.8), we memorize the first
+ * ClientHello we see (which can't have a cookie), then replay it after the
+ * first ApplicationData record - then we're done.
+ *
+ * This is controlled by the inject_clihlo option.
+ *
+ * We want an explicit state and a place to store the packet.
+ */
+static enum {
+ ich_init, /* haven't seen the first ClientHello yet */
+ ich_cached, /* cached the initial ClientHello */
+ ich_injected, /* ClientHello already injected, done */
+} inject_clihlo_state;
+
+static packet initial_clihlo;
+
int send_packet( const packet *p, const char *why )
{
int ret;
mbedtls_net_context *dst = p->dst;
+ /* save initial ClientHello? */
+ if( opt.inject_clihlo != 0 &&
+ inject_clihlo_state == ich_init &&
+ strcmp( p->type, "ClientHello" ) == 0 )
+ {
+ memcpy( &initial_clihlo, p, sizeof( packet ) );
+ inject_clihlo_state = ich_cached;
+ }
+
/* insert corrupted ApplicationData record? */
if( opt.bad_ad &&
strcmp( p->type, "ApplicationData" ) == 0 )
@@ -553,6 +590,23 @@
}
}
+ /* Inject ClientHello after first ApplicationData */
+ if( opt.inject_clihlo != 0 &&
+ inject_clihlo_state == ich_cached &&
+ strcmp( p->type, "ApplicationData" ) == 0 )
+ {
+ print_packet( &initial_clihlo, "injected" );
+
+ if( ( ret = dispatch_data( dst, initial_clihlo.buf,
+ initial_clihlo.len ) ) <= 0 )
+ {
+ mbedtls_printf( " ! dispatch returned %d\n", ret );
+ return( ret );
+ }
+
+ inject_clihlo_state = ich_injected;
+ }
+
return( 0 );
}
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 9fbf592..5a53f50 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -5798,6 +5798,14 @@
-s "The operation timed out" \
-S "Client initiated reconnection from same port"
+run_test "DTLS client reconnect from same port: attacker-injected" \
+ -p "$P_PXY inject_clihlo=1" \
+ "$P_SRV dtls=1 exchanges=2 debug_level=1" \
+ "$P_CLI dtls=1 exchanges=2" \
+ 0 \
+ -s "possible client reconnect from the same port" \
+ -S "Client initiated reconnection from same port"
+
# Tests for various cases of client authentication with DTLS
# (focused on handshake flows and message parsing)
