gre: set proper fib index for unnumbered interfaces, unset fib index before forwarding gre payload

This commit introduces 2 fixes:
1) After GRE decapsulation sw_if_index[VLIB_TX] is set as fib index of GRE tunnel.
But since GRE tunnel can work on v4 endpoints and have v6 payload, we need to reset it.
In case we get IPv6 packet inside IPv4 GRE tunnel (or vice-versa) fib index can be (and usually is) invalid.
2) Check that ip-table and ip6-table are the same when setting interface as an unnumbered one.

Also, fix for the pipe test include setting the right unnumbered interface for the pipes

Type: fix

Signed-off-by: Stanislav Zaikin <zstaseg@gmail.com>
Change-Id: Id13d239cfdd21e0db6b1c9725f01c40d4af4d800

src/vnet/gre/node.c

@@ -301,6 +301,9 @@ gre_input (vlib_main_t * vm,
 	  vnet_buffer (b[1])->sw_if_index[VLIB_RX] = tun_sw_if_index[1];
 	}
 
+      vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~0;
+      vnet_buffer (b[1])->sw_if_index[VLIB_TX] = (u32) ~0;
+
       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 	gre_trace (vm, node, b[0], tun_sw_if_index[0], ip6[0], ip4[0],
 		   is_ipv6);
@@ -411,6 +414,8 @@ gre_input (vlib_main_t * vm,
 	  vnet_buffer (b[0])->sw_if_index[VLIB_RX] = tun_sw_if_index[0];
 	}
 
+      vnet_buffer (b[0])->sw_if_index[VLIB_TX] = (u32) ~0;
+
       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 	gre_trace (vm, node, b[0], tun_sw_if_index[0], ip6[0], ip4[0],
 		   is_ipv6);

src/vnet/interface.c

@@ -1610,20 +1610,58 @@ vnet_hw_interface_change_mac_address (vnet_main_t * vnm, u32 hw_if_index,
     (vnm, hw_if_index, mac_address);
 }
 
+static int
+vnet_sw_interface_check_table_same (u32 unnumbered_sw_if_index,
+				    u32 ip_sw_if_index)
+{
+  vec_validate (ip4_main.fib_index_by_sw_if_index, unnumbered_sw_if_index);
+  vec_validate (ip4_main.mfib_index_by_sw_if_index, unnumbered_sw_if_index);
+  vec_validate (ip6_main.fib_index_by_sw_if_index, unnumbered_sw_if_index);
+  vec_validate (ip6_main.mfib_index_by_sw_if_index, unnumbered_sw_if_index);
+
+  vec_validate (ip4_main.fib_index_by_sw_if_index, ip_sw_if_index);
+  vec_validate (ip4_main.mfib_index_by_sw_if_index, ip_sw_if_index);
+  vec_validate (ip6_main.fib_index_by_sw_if_index, ip_sw_if_index);
+  vec_validate (ip6_main.mfib_index_by_sw_if_index, ip_sw_if_index);
+
+  if (ip4_main.fib_index_by_sw_if_index[unnumbered_sw_if_index] !=
+      ip4_main.fib_index_by_sw_if_index[ip_sw_if_index])
+    return VNET_API_ERROR_UNEXPECTED_INTF_STATE;
+
+  if (ip4_main.mfib_index_by_sw_if_index[unnumbered_sw_if_index] !=
+      ip4_main.mfib_index_by_sw_if_index[ip_sw_if_index])
+    return VNET_API_ERROR_UNEXPECTED_INTF_STATE;
+
+  if (ip6_main.fib_index_by_sw_if_index[unnumbered_sw_if_index] !=
+      ip6_main.fib_index_by_sw_if_index[ip_sw_if_index])
+    return VNET_API_ERROR_UNEXPECTED_INTF_STATE;
+
+  if (ip6_main.mfib_index_by_sw_if_index[unnumbered_sw_if_index] !=
+      ip6_main.mfib_index_by_sw_if_index[ip_sw_if_index])
+    return VNET_API_ERROR_UNEXPECTED_INTF_STATE;
+
+  return 0;
+}
+
 /* update the unnumbered state of an interface*/
-void
+int
 vnet_sw_interface_update_unnumbered (u32 unnumbered_sw_if_index,
 				     u32 ip_sw_if_index, u8 enable)
 {
   vnet_main_t *vnm = vnet_get_main ();
   vnet_sw_interface_t *si;
   u32 was_unnum;
+  int rv = 0;
 
   si = vnet_get_sw_interface (vnm, unnumbered_sw_if_index);
   was_unnum = (si->flags & VNET_SW_INTERFACE_FLAG_UNNUMBERED);
 
   if (enable)
     {
+      rv = vnet_sw_interface_check_table_same (unnumbered_sw_if_index,
+					       ip_sw_if_index);
+      if (rv != 0)
+	return rv;
       si->flags |= VNET_SW_INTERFACE_FLAG_UNNUMBERED;
       si->unnumbered_sw_if_index = ip_sw_if_index;
 
@@ -1660,6 +1698,8 @@ vnet_sw_interface_update_unnumbered (u32 unnumbered_sw_if_index,
       ip4_sw_interface_enable_disable (unnumbered_sw_if_index, enable);
       ip6_sw_interface_enable_disable (unnumbered_sw_if_index, enable);
     }
+
+  return 0;
 }
 
 vnet_l3_packet_type_t

src/vnet/interface_api.c

@@ -682,8 +682,8 @@ static void vl_api_sw_interface_set_unnumbered_t_handler
       goto done;
     }
 
-  vnet_sw_interface_update_unnumbered (unnumbered_sw_if_index,
-				       sw_if_index, mp->is_add);
+  rv = vnet_sw_interface_update_unnumbered (unnumbered_sw_if_index,
+					    sw_if_index, mp->is_add);
 done:
   REPLY_MACRO (VL_API_SW_INTERFACE_SET_UNNUMBERED_REPLY);
 }

src/vnet/interface_cli.c

@@ -976,8 +976,23 @@ set_unnumbered (vlib_main_t * vm,
     return clib_error_return (0, "When enabling unnumbered specify the"
 			      " IP enabled interface that it uses");
 
-  vnet_sw_interface_update_unnumbered (unnumbered_sw_if_index,
-				       inherit_from_sw_if_index, enable);
+  int rv = vnet_sw_interface_update_unnumbered (
+    unnumbered_sw_if_index, inherit_from_sw_if_index, enable);
+
+  switch (rv)
+    {
+    case 0:
+      break;
+
+    case VNET_API_ERROR_UNEXPECTED_INTF_STATE:
+      return clib_error_return (
+	0,
+	"When enabling unnumbered both interfaces must be in the same tables");
+
+    default:
+      return clib_error_return (
+	0, "vnet_sw_interface_update_unnumbered returned %d", rv);
+    }
 
   return (NULL);
 }

src/vnet/interface_funcs.h

@@ -430,8 +430,8 @@ void vnet_sw_interface_set_protocol_mtu (vnet_main_t * vnm, u32 sw_if_index,
 					 u32 mtu[]);
 
 /* update the unnumbered state of an interface */
-void vnet_sw_interface_update_unnumbered (u32 sw_if_index,
-					  u32 ip_sw_if_index, u8 enable);
+int vnet_sw_interface_update_unnumbered (u32 sw_if_index, u32 ip_sw_if_index,
+					 u8 enable);
 
 int vnet_sw_interface_stats_collect_enable_disable (u32 sw_if_index,
 						    u8 enable);

test/test_pipe.py

@@ -53,11 +53,13 @@ class VppPipe(VppInterface):
                 return True
         return False
 
-    def set_unnumbered(self, ip_sw_if_index, is_add=True):
-        res = self._test.vapi.sw_interface_set_unnumbered(ip_sw_if_index,
-                                                          self.east, is_add)
-        res = self._test.vapi.sw_interface_set_unnumbered(ip_sw_if_index,
-                                                          self.west, is_add)
+    def set_unnumbered(self, ip_sw_if_index, is_east, is_add=True):
+        if is_east:
+            res = self._test.vapi.sw_interface_set_unnumbered(
+                ip_sw_if_index, self.east, is_add)
+        else:
+            res = self._test.vapi.sw_interface_set_unnumbered(
+                ip_sw_if_index, self.west, is_add)
 
 
 class TestPipe(VppTestCase):
@@ -203,8 +205,8 @@ class TestPipe(VppTestCase):
         self.send_and_assert_no_replies(self.pg2, p_east * NUM_PKTS)
 
         # IP enable the Pipes by making them unnumbered
-        pipes[0].set_unnumbered(self.pg2.sw_if_index)
-        pipes[1].set_unnumbered(self.pg3.sw_if_index)
+        pipes[1].set_unnumbered(self.pg2.sw_if_index, True)
+        pipes[1].set_unnumbered(self.pg3.sw_if_index, False)
 
         self.send_and_expect(self.pg2, p_east * NUM_PKTS, self.pg3)