map: fix translation of icmp6 error messages

Translation of ICMPv6 error messages to ICMP error messages fails
because the sender port is not set that leads to securtiy check
failure.

With this commit, during ICMPv6 error messages translation, get the
sender port value from the inner packet.

Type: fix

Change-Id: I1ee295a3685fab4837172edfb629a699f49afbee
Signed-off-by: Alexander Chernavin <achernavin@netgate.com>

2 files changed, 131 insertions, 1 deletions

diff --git a/src/plugins/map/test/test_map_br.py b/src/plugins/map/test/test_map_br.py
index 631517e5d4e..3602ddd2e31 100644
--- a/src/plugins/map/test/test_map_br.py
+++ b/src/plugins/map/test/test_map_br.py
@@ -12,7 +12,7 @@ import scapy.compat
 from scapy.layers.l2 import Ether
 from scapy.packet import Raw
 from scapy.layers.inet import IP, UDP, ICMP, TCP, IPerror, UDPerror
-from scapy.layers.inet6 import IPv6, ICMPv6TimeExceeded, IPv6ExtHdrFragment
+from scapy.layers.inet6 import IPv6, ICMPv6TimeExceeded, ICMPv6PacketTooBig
 from scapy.layers.inet6 import ICMPv6EchoRequest, ICMPv6EchoReply, IPerror6
 
 
@@ -427,6 +427,85 @@ class TestMAPBR(VppTestCase):
         self.assertEqual(rx_pkt[ICMP].id, self.ipv6_udp_or_tcp_map_port)
 
     #
+    # Translation of ICMP Packet Too Big v6 -> v4 direction
+    # Received packet should be translated into an IPv4 Dest Unreachable.
+    #
+
+    def test_map_t_packet_too_big_ip6_to_ip4(self):
+        """ MAP-T packet too big IPv6 -> IPv4 """
+
+        eth = Ether(src=self.pg1.remote_mac,
+                    dst=self.pg1.local_mac)
+        ip = IPv6(src=self.ipv6_cpe_address,
+                  dst=self.ipv6_map_address)
+        icmp = ICMPv6PacketTooBig(mtu=1280)
+        ip_inner = IPv6(src=self.ipv6_map_address,
+                        dst=self.ipv6_cpe_address)
+        udp_inner = UDP(sport=self.ipv6_udp_or_tcp_internet_port,
+                        dport=self.ipv6_udp_or_tcp_map_port)
+        payload = "H" * 10
+        tx_pkt = eth / ip / icmp / ip_inner / udp_inner / payload
+
+        self.pg_send(self.pg1, tx_pkt * 1)
+
+        rx_pkts = self.pg0.get_capture(1)
+        rx_pkt = rx_pkts[0]
+
+        self.v4_address_check(rx_pkt)
+        self.assertEqual(rx_pkt[IP].proto, IP(proto="icmp").proto)
+        self.assertEqual(rx_pkt[ICMP].type, ICMP(type="dest-unreach").type)
+        self.assertEqual(rx_pkt[ICMP].code,
+                         ICMP(code="fragmentation-needed").code)
+        self.assertEqual(rx_pkt[ICMP].nexthopmtu,
+                         tx_pkt[ICMPv6PacketTooBig].mtu - 20)
+        self.assertTrue(rx_pkt.haslayer(IPerror))
+        self.assertTrue(rx_pkt.haslayer(UDPerror))
+        self.assertEqual(rx_pkt[IP].src, rx_pkt[IPerror].dst)
+        self.assertEqual(rx_pkt[IP].dst, rx_pkt[IPerror].src)
+        self.assertEqual(rx_pkt[UDPerror].sport,
+                         self.ipv4_udp_or_tcp_internet_port)
+        self.assertEqual(rx_pkt[UDPerror].dport, self.ipv4_udp_or_tcp_map_port)
+
+    #
+    # Translation of ICMP Time Exceeded v6 -> v4 direction
+    # Received packet should be translated into an IPv4 Time Exceeded.
+    #
+
+    def test_map_t_time_exceeded_ip6_to_ip4(self):
+        """ MAP-T time exceeded IPv6 -> IPv4 """
+
+        eth = Ether(src=self.pg1.remote_mac,
+                    dst=self.pg1.local_mac)
+        ip = IPv6(src=self.ipv6_cpe_address,
+                  dst=self.ipv6_map_address)
+        icmp = ICMPv6TimeExceeded()
+        ip_inner = IPv6(src=self.ipv6_map_address,
+                        dst=self.ipv6_cpe_address, hlim=1)
+        udp_inner = UDP(sport=self.ipv6_udp_or_tcp_internet_port,
+                        dport=self.ipv6_udp_or_tcp_map_port)
+        payload = "H" * 10
+        tx_pkt = eth / ip / icmp / ip_inner / udp_inner / payload
+
+        self.pg_send(self.pg1, tx_pkt * 1)
+
+        rx_pkts = self.pg0.get_capture(1)
+        rx_pkt = rx_pkts[0]
+
+        self.v4_address_check(rx_pkt)
+        self.assertEqual(rx_pkt[IP].proto, IP(proto="icmp").proto)
+        self.assertEqual(rx_pkt[ICMP].type, ICMP(type="time-exceeded").type)
+        self.assertEqual(rx_pkt[ICMP].code,
+                         ICMP(code="ttl-zero-during-transit").code)
+        self.assertEqual(rx_pkt[ICMP].ttl, tx_pkt[IPv6][1].hlim)
+        self.assertTrue(rx_pkt.haslayer(IPerror))
+        self.assertTrue(rx_pkt.haslayer(UDPerror))
+        self.assertEqual(rx_pkt[IP].src, rx_pkt[IPerror].dst)
+        self.assertEqual(rx_pkt[IP].dst, rx_pkt[IPerror].src)
+        self.assertEqual(rx_pkt[UDPerror].sport,
+                         self.ipv4_udp_or_tcp_internet_port)
+        self.assertEqual(rx_pkt[UDPerror].dport, self.ipv4_udp_or_tcp_map_port)
+
+    #
     # Spoofed IPv4 Source Address v6 -> v4 direction
     # Send a packet with a wrong IPv4 address embedded in bits 72-103.
     # The BR should either drop the packet, or rewrite the spoofed
diff --git a/src/vnet/ip/ip6_to_ip4.h b/src/vnet/ip/ip6_to_ip4.h
index 17a11e6df0a..6a533e3b54e 100644
--- a/src/vnet/ip/ip6_to_ip4.h
+++ b/src/vnet/ip/ip6_to_ip4.h
@@ -170,6 +170,57 @@ ip6_get_port (vlib_main_t * vm, vlib_buffer_t * b, ip6_header_t * ip6,
 	  if (dst_port)
 	    *dst_port = ((u16 *) (icmp))[2];
 	}
+      else if (clib_net_to_host_u16 (ip6->payload_length) >= 64)
+	{
+	  u16 ip6_pay_len;
+	  ip6_header_t *inner_ip6;
+	  u8 inner_l4_protocol;
+	  u16 inner_l4_offset;
+	  u16 inner_frag_offset;
+	  u8 *inner_l4;
+
+	  ip6_pay_len = clib_net_to_host_u16 (ip6->payload_length);
+	  inner_ip6 = (ip6_header_t *) u8_ptr_add (icmp, 8);
+
+	  if (ip6_parse (vm, b, inner_ip6, ip6_pay_len - 8,
+			 &inner_l4_protocol, &inner_l4_offset,
+			 &inner_frag_offset))
+	    return 0;
+
+	  if (inner_frag_offset &&
+	      ip6_frag_hdr_offset (((ip6_frag_hdr_t *)
+				    u8_ptr_add (inner_ip6,
+						inner_frag_offset))))
+	    return 0;
+
+	  inner_l4 = u8_ptr_add (inner_ip6, inner_l4_offset);
+	  if (inner_l4_protocol == IP_PROTOCOL_TCP ||
+	      inner_l4_protocol == IP_PROTOCOL_UDP)
+	    {
+	      if (src_port)
+		*src_port = ((udp_header_t *) (inner_l4))->dst_port;
+	      if (dst_port)
+		*dst_port = ((udp_header_t *) (inner_l4))->src_port;
+	    }
+	  else if (inner_l4_protocol == IP_PROTOCOL_ICMP6)
+	    {
+	      icmp46_header_t *inner_icmp = (icmp46_header_t *) (inner_l4);
+	      if (inner_icmp->type == ICMP6_echo_request)
+		{
+		  if (src_port)
+		    *src_port = ((u16 *) (inner_icmp))[2];
+		  if (dst_port)
+		    *dst_port = ((u16 *) (inner_icmp))[2];
+		}
+	      else if (inner_icmp->type == ICMP6_echo_reply)
+		{
+		  if (src_port)
+		    *src_port = ((u16 *) (inner_icmp))[2];
+		  if (dst_port)
+		    *dst_port = ((u16 *) (inner_icmp))[2];
+		}
+	    }
+	}
     }
   return 1;
 }