GBP: iVXLAN reflection check

packets should not egress on an iVXLAN tunnel if they
arrived on one.

Change-Id: I9adca30252364b4878f99e254aebc73b70a5d4d6
Signed-off-by: Neale Ranns <nranns@cisco.com>

6 files changed, 83 insertions, 16 deletions

diff --git a/src/plugins/gbp/gbp_policy_dpo.c b/src/plugins/gbp/gbp_policy_dpo.c
index 5fb04ff4df5..c3a51a46236 100644
--- a/src/plugins/gbp/gbp_policy_dpo.c
+++ b/src/plugins/gbp/gbp_policy_dpo.c
@@ -16,6 +16,7 @@
 #include <vnet/dpo/dvr_dpo.h>
 #include <vnet/dpo/drop_dpo.h>
 #include <vnet/vxlan-gbp/vxlan_gbp_packet.h>
+#include <vnet/vxlan-gbp/vxlan_gbp.h>
 
 #include <plugins/gbp/gbp.h>
 #include <plugins/gbp/gbp_policy_dpo.h>
@@ -153,6 +154,13 @@ gbp_policy_dpo_interpose (const dpo_id_t * original,
   gpd_clone->gpd_sclass = gpd->gpd_sclass;
   gpd_clone->gpd_sw_if_index = gpd->gpd_sw_if_index;
 
+  /*
+   * if no interface is provided, grab one from the parent
+   * on which we stack
+   */
+  if (~0 == gpd_clone->gpd_sw_if_index)
+    gpd_clone->gpd_sw_if_index = dpo_get_urpf (parent);
+
   dpo_stack (gbp_policy_dpo_type,
 	     gpd_clone->gpd_proto, &gpd_clone->gpd_dpo, parent);
 
@@ -286,6 +294,15 @@ gbp_policy_dpo_inline (vlib_main_t * vm,
 	  gpd0 = gbp_policy_dpo_get (vnet_buffer (b0)->ip.adj_index[VLIB_TX]);
 	  vnet_buffer (b0)->ip.adj_index[VLIB_TX] = gpd0->gpd_dpo.dpoi_index;
 
+	  /*
+	   * Reflection check; in and out on an ivxlan tunnel
+	   */
+	  if ((~0 != vxlan_gbp_tunnel_by_sw_if_index (gpd0->gpd_sw_if_index))
+	      && (vnet_buffer2 (b0)->gbp.flags & VXLAN_GBP_GPFLAGS_R))
+	    {
+	      goto trace;
+	    }
+
 	  if (vnet_buffer2 (b0)->gbp.flags & VXLAN_GBP_GPFLAGS_A)
 	    {
 	      next0 = gpd0->gpd_dpo.dpoi_next_node;
diff --git a/src/plugins/gbp/gbp_policy_node.c b/src/plugins/gbp/gbp_policy_node.c
index ff21e7d0e2e..1f2ac4310e0 100644
--- a/src/plugins/gbp/gbp_policy_node.c
+++ b/src/plugins/gbp/gbp_policy_node.c
@@ -17,9 +17,11 @@
 #include <plugins/gbp/gbp_policy_dpo.h>
 
 #include <vnet/vxlan-gbp/vxlan_gbp_packet.h>
+#include <vnet/vxlan-gbp/vxlan_gbp.h>
 
 #define foreach_gbp_policy                      \
-  _(DENY,    "deny")
+  _(DENY,    "deny")                            \
+  _(REFLECTION, "reflection")
 
 typedef enum
 {
@@ -37,10 +39,8 @@ static char *gbp_policy_error_strings[] = {
 
 typedef enum
 {
-#define _(sym,str) GBP_POLICY_NEXT_##sym,
-  foreach_gbp_policy
-#undef _
-    GBP_POLICY_N_NEXT,
+  GBP_POLICY_NEXT_DROP,
+  GBP_POLICY_N_NEXT,
 } gbp_policy_next_t;
 
 /**
@@ -53,6 +53,7 @@ typedef struct gbp_policy_trace_t_
   u32 dst_epg;
   u32 acl_index;
   u32 allowed;
+  u32 flags;
 } gbp_policy_trace_t;
 
 always_inline dpo_proto_t
@@ -138,7 +139,7 @@ gbp_policy_inline (vlib_main_t * vm,
 	  index_t gci0;
 
 	  gc0 = NULL;
-	  next0 = GBP_POLICY_NEXT_DENY;
+	  next0 = GBP_POLICY_NEXT_DROP;
 	  bi0 = from[0];
 	  to_next[0] = bi0;
 	  from += 1;
@@ -151,7 +152,16 @@ gbp_policy_inline (vlib_main_t * vm,
 	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_TX];
 
 	  /*
-	   * If the A0bit is set then policy has already been applied
+	   * Reflection check; in and out on an ivxlan tunnel
+	   */
+	  if ((~0 != vxlan_gbp_tunnel_by_sw_if_index (sw_if_index0)) &&
+	      (vnet_buffer2 (b0)->gbp.flags & VXLAN_GBP_GPFLAGS_R))
+	    {
+	      goto trace;
+	    }
+
+	  /*
+	   * If the A-bit is set then policy has already been applied
 	   * and we skip enforcement here.
 	   */
 	  if (vnet_buffer2 (b0)->gbp.flags & VXLAN_GBP_GPFLAGS_A)
@@ -165,6 +175,7 @@ gbp_policy_inline (vlib_main_t * vm,
 	      key0.as_u32 = ~0;
 	      goto trace;
 	    }
+
 	  /*
 	   * determine the src and dst EPG
 	   */
@@ -307,8 +318,9 @@ gbp_policy_inline (vlib_main_t * vm,
 		vlib_add_trace (vm, node, b0, sizeof (*t));
 	      t->sclass = key0.gck_src;
 	      t->dst_epg = key0.gck_dst;
-	      t->acl_index = (gc0 ? gc0->gc_acl_index : ~0),
-		t->allowed = (next0 != GBP_POLICY_NEXT_DENY);
+	      t->acl_index = (gc0 ? gc0->gc_acl_index : ~0);
+	      t->allowed = (next0 != GBP_POLICY_NEXT_DROP);
+	      t->flags = vnet_buffer2 (b0)->gbp.flags;
 	    }
 
 	  /* verify speculative enqueue, maybe switch current next frame */
@@ -346,8 +358,9 @@ format_gbp_policy_trace (u8 * s, va_list * args)
   gbp_policy_trace_t *t = va_arg (*args, gbp_policy_trace_t *);
 
   s =
-    format (s, "sclass:%d, dst:%d, acl:%d allowed:%d",
-	    t->sclass, t->dst_epg, t->acl_index, t->allowed);
+    format (s, "sclass:%d, dst:%d, acl:%d allowed:%d flags:%U",
+	    t->sclass, t->dst_epg, t->acl_index, t->allowed,
+	    format_vxlan_gbp_header_gpflags, t->flags);
 
   return s;
 }
@@ -365,7 +378,7 @@ VLIB_REGISTER_NODE (gbp_policy_port_node) = {
   .n_next_nodes = GBP_POLICY_N_NEXT,
 
   .next_nodes = {
-    [GBP_POLICY_NEXT_DENY] = "error-drop",
+    [GBP_POLICY_NEXT_DROP] = "error-drop",
   },
 };
 
diff --git a/src/vnet/vxlan-gbp/decap.c b/src/vnet/vxlan-gbp/decap.c
index c520e25dcf2..23995c49fcb 100644
--- a/src/vnet/vxlan-gbp/decap.c
+++ b/src/vnet/vxlan-gbp/decap.c
@@ -330,7 +330,8 @@ vxlan_gbp_input (vlib_main_t * vm,
 	      pkts_decapsulated++;
 	    }
 
-	  vnet_buffer2 (b0)->gbp.flags = vxlan_gbp_get_gpflags (vxlan_gbp0);
+	  vnet_buffer2 (b0)->gbp.flags = (vxlan_gbp_get_gpflags (vxlan_gbp0) |
+					  VXLAN_GBP_GPFLAGS_R);
 	  vnet_buffer2 (b0)->gbp.sclass = vxlan_gbp_get_sclass (vxlan_gbp0);
 
 
@@ -370,7 +371,9 @@ vxlan_gbp_input (vlib_main_t * vm,
 		(rx_counter, thread_index, t1->sw_if_index, 1, len1);
 	    }
 
-	  vnet_buffer2 (b1)->gbp.flags = vxlan_gbp_get_gpflags (vxlan_gbp1);
+	  vnet_buffer2 (b1)->gbp.flags = (vxlan_gbp_get_gpflags (vxlan_gbp1) |
+					  VXLAN_GBP_GPFLAGS_R);
+
 	  vnet_buffer2 (b1)->gbp.sclass = vxlan_gbp_get_sclass (vxlan_gbp1);
 
 	  vnet_update_l2_len (b0);
@@ -476,7 +479,9 @@ vxlan_gbp_input (vlib_main_t * vm,
 	      vlib_increment_combined_counter
 		(rx_counter, thread_index, t0->sw_if_index, 1, len0);
 	    }
-	  vnet_buffer2 (b0)->gbp.flags = vxlan_gbp_get_gpflags (vxlan_gbp0);
+	  vnet_buffer2 (b0)->gbp.flags = (vxlan_gbp_get_gpflags (vxlan_gbp0) |
+					  VXLAN_GBP_GPFLAGS_R);
+
 	  vnet_buffer2 (b0)->gbp.sclass = vxlan_gbp_get_sclass (vxlan_gbp0);
 
 	  /* Required to make the l2 tag push / pop code work on l2 subifs */
diff --git a/src/vnet/vxlan-gbp/vxlan_gbp.h b/src/vnet/vxlan-gbp/vxlan_gbp.h
index 6580f38e119..af2e1809099 100644
--- a/src/vnet/vxlan-gbp/vxlan_gbp.h
+++ b/src/vnet/vxlan-gbp/vxlan_gbp.h
@@ -226,6 +226,17 @@ int vnet_vxlan_gbp_tunnel_del (u32 sw_if_indexp);
 void vnet_int_vxlan_gbp_bypass_mode (u32 sw_if_index, u8 is_ip6,
 				     u8 is_enable);
 
+always_inline u32
+vxlan_gbp_tunnel_by_sw_if_index (u32 sw_if_index)
+{
+  vxlan_gbp_main_t *vxm = &vxlan_gbp_main;
+
+  if (sw_if_index >= vec_len (vxm->tunnel_index_by_sw_if_index))
+    return ~0;
+
+  return (vxm->tunnel_index_by_sw_if_index[sw_if_index]);
+}
+
 #endif /* included_vnet_vxlan_gbp_h */
 
 /*
diff --git a/src/vnet/vxlan-gbp/vxlan_gbp_packet.h b/src/vnet/vxlan-gbp/vxlan_gbp_packet.h
index 33bccd6aed6..58fe00323b0 100644
--- a/src/vnet/vxlan-gbp/vxlan_gbp_packet.h
+++ b/src/vnet/vxlan-gbp/vxlan_gbp_packet.h
@@ -63,6 +63,11 @@
  *   Group membership being encapsulated by VXLAN. Its value is source
  *   class id.
  *
+ * FOR INTERNAL USE ONLY
+ * R bit: Bit 12 of the initial word is defined as the reflection bit
+ *   Set on packet rx checked on tx and dropped if set. this prevents
+ *   packets recieved on an iVXLAN tunnel being reflected back to
+ *   another.
  */
 
 typedef struct
@@ -103,7 +108,8 @@ typedef enum
 _ (0x40, D)                       \
 _ (0x20, E)                       \
 _ (0x10, S)                       \
-_ (0x08, A)
+_ (0x08, A)                       \
+_ (0x04, R)
 
 typedef enum
 {
diff --git a/test/test_gbp.py b/test/test_gbp.py
index 17e9f93e938..7f9032970d5 100644
--- a/test/test_gbp.py
+++ b/test/test_gbp.py
@@ -3562,6 +3562,21 @@ class TestGBP(VppTestCase):
         self.assertFalse(find_gbp_endpoint(self, ip="10.222.0.1"))
 
         #
+        # ping from host in remote to remote external subnets
+        #   this is dropped by reflection check.
+        #
+        p = (Ether(src=self.pg7.remote_mac, dst=self.pg7.local_mac) /
+             IP(src=self.pg7.remote_ip4, dst=self.pg7.local_ip4) /
+             UDP(sport=1234, dport=48879) /
+             VXLAN(vni=445, gpid=4222, flags=0x88, gpflags='A') /
+             Ether(src=self.pg0.remote_mac, dst=str(self.router_mac)) /
+             IP(src="10.222.0.1", dst="10.222.0.2") /
+             UDP(sport=1234, dport=1234) /
+             Raw('\xa5' * 100))
+
+        rxs = self.send_and_assert_no_replies(self.pg7, p * 3)
+
+        #
         # cleanup
         #
         self.pg7.unconfig_ip4()