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Add negative test for hard reconnect cookie check

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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>
This commit is contained in:
Manuel Pégourié-Gonnard 2020-03-13 11:11:02 +01:00
parent 824655c837
commit baad2de6d8
2 changed files with 62 additions and 0 deletions
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54
programs/test/udp_proxy.c
View file

@ -133,6 +133,7 @@ int main( void )
" modifying CID in first instance of the packet.\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 \
@ -166,6 +167,7 @@ static struct options
unsigned bad_cid; /* inject corrupted CID 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 */
@ -314,6 +316,12 @@ static void get_options( int argc, char *argv[] )
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 );
@ -523,11 +531,40 @@ void print_packet( const packet *p, const char *why )
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 CID record? */
if( opt.bad_cid != 0 &&
strcmp( p->type, "CID" ) == 0 &&
@ -592,6 +629,23 @@ int send_packet( const packet *p, const char *why )
}
}
/* 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 );
}

8
tests/ssl-opt.sh
View file

@ -7318,6 +7318,14 @@ run_test "DTLS client reconnect from same port: no cookies" \
-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)