src/Cedar/Proto_IKE.c

@@ -463,13 +463,39 @@ void ProcIPsecEspPacketRecv(IKE_SERVER *ike, UDPPACKET *p)
 	seq = READ_UINT(src + sizeof(UINT));
 
 	// Search and retrieve the IPsec SA from SPI
-
-	// thank to @phillibert report, responding to bad SA might lead to amplification
-	// according to RFC4303 we should drop such packets
-
 	ipsec_sa = SearchClientToServerIPsecSaBySpi(ike, spi);
 	if (ipsec_sa == NULL)
 	{
+		// Invalid SPI
+		UINT64 init_cookie = Rand64();
+		UINT64 resp_cookie = 0;
+		IKE_CLIENT *c = NULL;
+		IKE_CLIENT t;
+
+
+		Copy(&t.ClientIP, &p->SrcIP, sizeof(IP));
+		t.ClientPort = p->SrcPort;
+		Copy(&t.ServerIP, &p->DstIP, sizeof(IP));
+		t.ServerPort = p->DestPort;
+		t.CurrentIkeSa = NULL;
+
+		if (p->DestPort == IPSEC_PORT_IPSEC_ESP_RAW)
+		{
+			t.ClientPort = t.ServerPort = IPSEC_PORT_IPSEC_ISAKMP;
+		}
+
+		c = Search(ike->ClientList, &t);
+
+		if (c != NULL && c->CurrentIkeSa != NULL)
+		{
+			init_cookie = c->CurrentIkeSa->InitiatorCookie;
+			resp_cookie = c->CurrentIkeSa->ResponderCookie;
+		}
+
+		SendInformationalExchangePacketEx(ike, (c == NULL ? &t : c), IkeNewNoticeErrorInvalidSpiPayload(spi), false,
+			init_cookie, resp_cookie);
+
+		SendDeleteIPsecSaPacket(ike, (c == NULL ? &t : c), spi);
 		return;
 	}