SNAT: NAT packet with unknown L4 protocol if match 1:1 NAT

Change-Id: Ic81c6098d615fdb6a874e532921efd833fed872c
Signed-off-by: Matus Fabian <matfabia@cisco.com>

3 files changed, 153 insertions, 7 deletions

diff --git a/src/plugins/snat/in2out.c b/src/plugins/snat/in2out.c
index 685cdca8045..d396c79c1b2 100644
--- a/src/plugins/snat/in2out.c
+++ b/src/plugins/snat/in2out.c
@@ -967,6 +967,55 @@ static inline u32 icmp_in2out_slow_path (snat_main_t *sm,
   return next0;
 }
 
+static void
+snat_in2out_unknown_proto (snat_main_t *sm,
+                           vlib_buffer_t * b,
+                           ip4_header_t * ip,
+                           u32 rx_fib_index)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  snat_static_mapping_t *m;
+  snat_session_key_t m_key;
+  u32 old_addr, new_addr;
+  ip_csum_t sum;
+
+  m_key.addr = ip->src_address;
+  m_key.port = 0;
+  m_key.protocol = 0;
+  m_key.fib_index = rx_fib_index;
+  kv.key = m_key.as_u64;
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_local, &kv, &value))
+    return;
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  old_addr = ip->src_address.as_u32;
+  new_addr = ip->src_address.as_u32 = m->external_addr.as_u32;
+  sum = ip->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, src_address);
+  ip->checksum = ip_csum_fold (sum);
+
+  /* Hairpinning */
+  m_key.addr = ip->dst_address;
+  m_key.fib_index = sm->outside_fib_index;
+  kv.key = m_key.as_u64;
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    {
+      vnet_buffer(b)->sw_if_index[VLIB_TX] = sm->outside_fib_index;
+      return;
+    }
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  old_addr = ip->dst_address.as_u32;
+  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
+  sum = ip->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
+  ip->checksum = ip_csum_fold (sum);
+
+  vnet_buffer(b)->sw_if_index[VLIB_TX] = vnet_buffer(b)->sw_if_index[VLIB_RX];
+}
+
 static inline uword
 snat_in2out_node_fn_inline (vlib_main_t * vm,
                             vlib_node_runtime_t * node,
@@ -1065,8 +1114,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
           if (is_slow_path)
             {
               if (PREDICT_FALSE (proto0 == ~0))
-                goto trace00;
-              
+                {
+                  snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0);
+                  goto trace00;
+                }
+
               if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                 {
                   next0 = icmp_in2out_slow_path 
@@ -1205,8 +1257,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
           if (is_slow_path)
             {
               if (PREDICT_FALSE (proto1 == ~0))
-                goto trace01;
-              
+                {
+                  snat_in2out_unknown_proto (sm, b1, ip1, rx_fib_index1);
+                  goto trace01;
+                }
+
               if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
                 {
                   next1 = icmp_in2out_slow_path 
@@ -1380,8 +1435,11 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
           if (is_slow_path)
             {
               if (PREDICT_FALSE (proto0 == ~0))
-                goto trace0;
-              
+                {
+                  snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0);
+                  goto trace0;
+                }
+
               if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
                 {
                   next0 = icmp_in2out_slow_path 
diff --git a/src/plugins/snat/out2in.c b/src/plugins/snat/out2in.c
index e8ddcf1cfd7..5c12b473c63 100644
--- a/src/plugins/snat/out2in.c
+++ b/src/plugins/snat/out2in.c
@@ -611,6 +611,37 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
   return next0;
 }
 
+static void
+snat_out2in_unknown_proto (snat_main_t *sm,
+                           vlib_buffer_t * b,
+                           ip4_header_t * ip,
+                           u32 rx_fib_index)
+{
+  clib_bihash_kv_8_8_t kv, value;
+  snat_static_mapping_t *m;
+  snat_session_key_t m_key;
+  u32 old_addr, new_addr;
+  ip_csum_t sum;
+
+  m_key.addr = ip->dst_address;
+  m_key.port = 0;
+  m_key.protocol = 0;
+  m_key.fib_index = rx_fib_index;
+  kv.key = m_key.as_u64;
+  if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
+    return;
+
+  m = pool_elt_at_index (sm->static_mappings, value.value);
+
+  old_addr = ip->dst_address.as_u32;
+  new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
+  sum = ip->checksum;
+  sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
+  ip->checksum = ip_csum_fold (sum);
+
+  vnet_buffer(b)->sw_if_index[VLIB_TX] = m->fib_index;
+}
+
 static uword
 snat_out2in_node_fn (vlib_main_t * vm,
 		  vlib_node_runtime_t * node,
@@ -703,7 +734,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
           proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
           if (PREDICT_FALSE (proto0 == ~0))
+            {
+              snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0);
               goto trace0;
+            }
 
           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
             {
@@ -838,7 +872,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
           proto1 = ip_proto_to_snat_proto (ip1->protocol);
 
           if (PREDICT_FALSE (proto1 == ~0))
+            {
+              snat_out2in_unknown_proto(sm, b1, ip1, rx_fib_index1);
               goto trace1;
+            }
 
           if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
             {
@@ -997,7 +1034,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
           proto0 = ip_proto_to_snat_proto (ip0->protocol);
 
           if (PREDICT_FALSE (proto0 == ~0))
+            {
+              snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0);
               goto trace00;
+            }
 
           if (PREDICT_FALSE(ip0->ttl == 1))
             {
diff --git a/test/test_snat.py b/test/test_snat.py
index ee689e6ac3e..e148fbae56c 100644
--- a/test/test_snat.py
+++ b/test/test_snat.py
@@ -9,7 +9,7 @@ from scapy.layers.inet import IP, TCP, UDP, ICMP
 from scapy.layers.inet import IPerror, TCPerror, UDPerror, ICMPerror
 from scapy.layers.inet6 import IPv6, ICMPv6EchoRequest, ICMPv6EchoReply
 from scapy.layers.inet6 import ICMPv6DestUnreach, IPerror6
-from scapy.layers.l2 import Ether, ARP
+from scapy.layers.l2 import Ether, ARP, GRE
 from scapy.data import IP_PROTOS
 from scapy.packet import bind_layers
 from util import ppp
@@ -1835,6 +1835,54 @@ class TestSNAT(MethodHolder):
         capture = self.pg8.get_capture(len(pkts))
         self.verify_capture_out(capture)
 
+    def test_static_unknown_proto(self):
+        """ 1:1 NAT translate packet with unknown protocol """
+        nat_ip = "10.0.0.10"
+        self.snat_add_static_mapping(self.pg0.remote_ip4, nat_ip)
+        self.vapi.snat_interface_add_del_feature(self.pg0.sw_if_index)
+        self.vapi.snat_interface_add_del_feature(self.pg1.sw_if_index,
+                                                 is_inside=0)
+
+        # in2out
+        p = (Ether(dst=self.pg0.local_mac, src=self.pg0.remote_mac) /
+             IP(src=self.pg0.remote_ip4, dst=self.pg1.remote_ip4) /
+             GRE() /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg0.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg1.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, nat_ip)
+            self.assertEqual(packet[IP].dst, self.pg1.remote_ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.check_ip_checksum(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
+        # out2in
+        p = (Ether(dst=self.pg1.local_mac, src=self.pg1.remote_mac) /
+             IP(src=self.pg1.remote_ip4, dst=nat_ip) /
+             GRE() /
+             IP(src=self.pg2.remote_ip4, dst=self.pg2.remote_ip4) /
+             TCP(sport=1234, dport=1234))
+        self.pg1.add_stream(p)
+        self.pg_enable_capture(self.pg_interfaces)
+        self.pg_start()
+        p = self.pg0.get_capture(1)
+        packet = p[0]
+        try:
+            self.assertEqual(packet[IP].src, self.pg1.remote_ip4)
+            self.assertEqual(packet[IP].dst, self.pg0.remote_ip4)
+            self.assertTrue(packet.haslayer(GRE))
+            self.check_ip_checksum(packet)
+        except:
+            self.logger.error(ppp("Unexpected or invalid packet:", packet))
+            raise
+
     def tearDown(self):
         super(TestSNAT, self).tearDown()
         if not self.vpp_dead: