SRv6 masquerading proxy plugin

Change-Id: Ia65cf2c7b7fdf84c64e60af4cc815251022c53a9
Signed-off-by: Francois Clad <fclad@cisco.com>

MAINTAINERS

@@ -159,6 +159,11 @@ M:  Hongjun Ni <hongjun.ni@intel.com>
 F:  src/plugins/pppoe/
 F:  src/plugins/pppoe.am
 
+Plugin - IPv6 Segment Routing Masquerading Proxy
+M:	Francois Clad <fclad@cisco.com>
+F:	src/plugins/srv6-am/
+F:	src/plugins/srv6_am.am
+
 Plugin - IPv6 Segment Routing Static Proxy
 M:	Francois Clad <fclad@cisco.com>
 F:	src/plugins/srv6-as/

src/configure.ac

@@ -221,6 +221,7 @@ PLUGIN_ENABLED(marvell)
 PLUGIN_ENABLED(memif)
 PLUGIN_ENABLED(pppoe)
 PLUGIN_ENABLED(sixrd)
+PLUGIN_ENABLED(srv6am)
 PLUGIN_ENABLED(srv6as)
 PLUGIN_ENABLED(nat)
 PLUGIN_ENABLED(stn)

src/plugins/Makefile.am

@@ -83,6 +83,10 @@ if ENABLE_SIXRD_PLUGIN
 include sixrd.am
 endif
 
+if ENABLE_SRV6AM_PLUGIN
+include srv6_am.am
+endif
+
 if ENABLE_SRV6AS_PLUGIN
 include srv6_as.am
 endif

src/plugins/srv6-am/am.c

@@ -0,0 +1,249 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ *------------------------------------------------------------------
+ * am.c - SRv6 Masquerading Proxy (AM) function
+ *------------------------------------------------------------------
+ */
+
+#include <vnet/vnet.h>
+#include <vnet/adj/adj.h>
+#include <vnet/plugin/plugin.h>
+#include <vpp/app/version.h>
+#include <srv6-am/am.h>
+
+unsigned char function_name[] = "SRv6-AM-plugin";
+unsigned char keyword_str[] = "End.AM";
+unsigned char def_str[] = "Endpoint to SR-unaware appliance via masquerading";
+unsigned char params_str[] = "nh <next-hop> oif <iface-out> iif <iface-in>";
+
+
+/*****************************************/
+/* SRv6 LocalSID instantiation and removal functions */
+static int
+srv6_am_localsid_creation_fn (ip6_sr_localsid_t * localsid)
+{
+  srv6_am_main_t *sm = &srv6_am_main;
+  srv6_am_localsid_t *ls_mem = localsid->plugin_mem;
+  adj_index_t nh_adj_index = ADJ_INDEX_INVALID;
+
+  /* Step 1: Prepare xconnect adjacency for sending packets to the VNF */
+
+  /* Retrieve the adjacency corresponding to the (OIF, next_hop) */
+  nh_adj_index = adj_nbr_add_or_lock (FIB_PROTOCOL_IP6,
+				      VNET_LINK_IP6, &ls_mem->nh_addr,
+				      ls_mem->sw_if_index_out);
+  if (nh_adj_index == ADJ_INDEX_INVALID)
+    return -5;
+
+  localsid->nh_adj = nh_adj_index;
+
+
+  /* Step 2: Prepare inbound policy for packets returning from the VNF */
+
+  /* Sanitise the SW_IF_INDEX */
+  if (pool_is_free_index (sm->vnet_main->interface_main.sw_interfaces,
+			  ls_mem->sw_if_index_in))
+    return -3;
+
+  vnet_sw_interface_t *sw = vnet_get_sw_interface (sm->vnet_main,
+						   ls_mem->sw_if_index_in);
+  if (sw->type != VNET_SW_INTERFACE_TYPE_HARDWARE)
+    return -3;
+
+  int ret = vnet_feature_enable_disable ("ip6-unicast", "srv6-am-rewrite",
+					 ls_mem->sw_if_index_in, 1, 0, 0);
+  if (ret != 0)
+    return -1;
+
+  return 0;
+}
+
+static int
+srv6_am_localsid_removal_fn (ip6_sr_localsid_t * localsid)
+{
+  srv6_am_localsid_t *ls_mem = localsid->plugin_mem;
+
+  /* Remove hardware indirection (from sr_steering.c:137) */
+  int ret = vnet_feature_enable_disable ("ip6-unicast", "srv6-am-rewrite",
+					 ls_mem->sw_if_index_in, 0, 0, 0);
+  if (ret != 0)
+    return -1;
+
+  /* Unlock (OIF, NHOP) adjacency (from sr_localsid.c:103) */
+  adj_unlock (localsid->nh_adj);
+
+  /* Clean up local SID memory */
+  clib_mem_free (localsid->plugin_mem);
+
+  return 0;
+}
+
+/**********************************/
+/* SRv6 LocalSID format functions */
+/*
+ * Prints nicely the parameters of a localsid
+ * Example: print "Table 5"
+ */
+u8 *
+format_srv6_am_localsid (u8 * s, va_list * args)
+{
+  srv6_am_localsid_t *ls_mem = va_arg (*args, void *);
+
+  vnet_main_t *vnm = vnet_get_main ();
+
+  return (format (s,
+		  "Next-hop:\t%U\n"
+		  "\tOutgoing iface: %U\n"
+		  "\tIncoming iface: %U",
+		  format_ip6_address, &ls_mem->nh_addr.ip6,
+		  format_vnet_sw_if_index_name, vnm, ls_mem->sw_if_index_out,
+		  format_vnet_sw_if_index_name, vnm, ls_mem->sw_if_index_in));
+}
+
+/*
+ * Process the parameters of a localsid
+ * Example: process from:
+ * sr localsid address cafe::1 behavior new_srv6_localsid 5
+ * everything from behavior on... so in this case 'new_srv6_localsid 5'
+ * Notice that it MUST match the keyword_str and params_str defined above.
+ */
+uword
+unformat_srv6_am_localsid (unformat_input_t * input, va_list * args)
+{
+  void **plugin_mem_p = va_arg (*args, void **);
+  srv6_am_localsid_t *ls_mem;
+
+  vnet_main_t *vnm = vnet_get_main ();
+
+  ip46_address_t nh_addr;
+  u32 sw_if_index_out;
+  u32 sw_if_index_in;
+
+  if (unformat (input, "end.am nh %U oif %U iif %U",
+		unformat_ip6_address, &nh_addr.ip6,
+		unformat_vnet_sw_interface, vnm, &sw_if_index_out,
+		unformat_vnet_sw_interface, vnm, &sw_if_index_in))
+    {
+      /* Allocate a portion of memory */
+      ls_mem = clib_mem_alloc_aligned_at_offset (sizeof *ls_mem, 0, 0, 1);
+
+      /* Set to zero the memory */
+      memset (ls_mem, 0, sizeof *ls_mem);
+
+      /* Our brand-new car is ready */
+      clib_memcpy (&ls_mem->nh_addr.ip6, &nh_addr.ip6,
+		   sizeof (ip6_address_t));
+      ls_mem->sw_if_index_out = sw_if_index_out;
+      ls_mem->sw_if_index_in = sw_if_index_in;
+
+      /* Dont forget to add it to the localsid */
+      *plugin_mem_p = ls_mem;
+      return 1;
+    }
+  return 0;
+}
+
+/*************************/
+/* SRv6 LocalSID FIB DPO */
+static u8 *
+format_srv6_am_dpo (u8 * s, va_list * args)
+{
+  index_t index = va_arg (*args, index_t);
+  CLIB_UNUSED (u32 indent) = va_arg (*args, u32);
+
+  return (format (s, "SR: dynamic_proxy_index:[%u]", index));
+}
+
+void
+srv6_am_dpo_lock (dpo_id_t * dpo)
+{
+}
+
+void
+srv6_am_dpo_unlock (dpo_id_t * dpo)
+{
+}
+
+const static dpo_vft_t srv6_am_vft = {
+  .dv_lock = srv6_am_dpo_lock,
+  .dv_unlock = srv6_am_dpo_unlock,
+  .dv_format = format_srv6_am_dpo,
+};
+
+const static char *const srv6_am_ip6_nodes[] = {
+  "srv6-am-localsid",
+  NULL,
+};
+
+const static char *const *const srv6_am_nodes[DPO_PROTO_NUM] = {
+  [DPO_PROTO_IP6] = srv6_am_ip6_nodes,
+};
+
+/**********************/
+static clib_error_t *
+srv6_am_init (vlib_main_t * vm)
+{
+  srv6_am_main_t *sm = &srv6_am_main;
+  int rv = 0;
+
+  sm->vlib_main = vm;
+  sm->vnet_main = vnet_get_main ();
+
+  /* Create DPO */
+  sm->srv6_am_dpo_type = dpo_register_new_type (&srv6_am_vft, srv6_am_nodes);
+
+  /* Register SRv6 LocalSID */
+  rv = sr_localsid_register_function (vm,
+				      function_name,
+				      keyword_str,
+				      def_str,
+				      params_str,
+				      &sm->srv6_am_dpo_type,
+				      format_srv6_am_localsid,
+				      unformat_srv6_am_localsid,
+				      srv6_am_localsid_creation_fn,
+				      srv6_am_localsid_removal_fn);
+  if (rv < 0)
+    clib_error_return (0, "SRv6 LocalSID function could not be registered.");
+  else
+    sm->srv6_localsid_behavior_id = rv;
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VNET_FEATURE_INIT (srv6_am_rewrite, static) =
+{
+  .arc_name = "ip6-unicast",
+  .node_name = "srv6-am-rewrite",
+  .runs_before = 0,
+};
+
+VLIB_INIT_FUNCTION (srv6_am_init);
+
+VLIB_PLUGIN_REGISTER () = {
+  .version = VPP_BUILD_VER,
+  .description = "Masquerading SRv6 proxy",
+};
+/* *INDENT-ON* */
+
+/*
+* fd.io coding-style-patch-verification: ON
+*
+* Local Variables:
+* eval: (c-set-style "gnu")
+* End:
+*/

src/plugins/srv6-am/am.h

@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2015 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef __included_srv6_am_h__
+#define __included_srv6_am_h__
+
+#include <vnet/vnet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/srv6/sr.h>
+#include <vnet/srv6/sr_packet.h>
+
+#include <vppinfra/error.h>
+#include <vppinfra/elog.h>
+
+typedef struct
+{
+  u16 msg_id_base;		  /**< API message ID base */
+
+  vlib_main_t *vlib_main;	  /**< [convenience] vlib main */
+  vnet_main_t *vnet_main;	  /**< [convenience] vnet main */
+
+  dpo_type_t srv6_am_dpo_type;	  /**< DPO type */
+
+  u32 srv6_localsid_behavior_id;  /**< SRv6 LocalSID behavior number */
+} srv6_am_main_t;
+
+/*
+ * This is the memory that will be stored per each localsid
+ * the user instantiates
+ */
+typedef struct
+{
+  ip46_address_t nh_addr;		/**< Proxied device address */
+  u32 sw_if_index_out;					    /**< Outgoing iface to proxied device */
+  u32 sw_if_index_in;					    /**< Incoming iface from proxied device */
+} srv6_am_localsid_t;
+
+srv6_am_main_t srv6_am_main;
+
+format_function_t format_srv6_am_localsid;
+unformat_function_t unformat_srv6_am_localsid;
+
+void srv6_am_dpo_lock (dpo_id_t * dpo);
+void srv6_am_dpo_unlock (dpo_id_t * dpo);
+
+extern vlib_node_registration_t srv6_am_localsid_node;
+
+#endif /* __included_srv6_am_h__ */
+
+/*
+* fd.io coding-style-patch-verification: ON
+*
+* Local Variables:
+* eval: (c-set-style "gnu")
+* End:
+*/

src/plugins/srv6-am/am_plugin_doc.md

@@ -0,0 +1,91 @@
+# SRv6 endpoint to SR-unaware appliance via masquerading (End.AM) {#srv6_am_plugin_doc}
+
+## Overview
+
+The "Endpoint to SR-unaware appliance via masquerading" (End.AM) is a two-parts
+function for processing SRv6 **inserted** traffic on behalf of an SR-unaware
+appliance. The first part decrements the Segments Left value and **replaces the
+IPv6 Destination Address with the last segment in the SRH**, while the second
+restores the IPv6 Destination Address with the active segment in the traffic
+coming back from the appliance.
+
+In this scenario, we assume that the appliance can only inspect, drop or perform
+limited changes to the packets. In particular, the appliance must not change the
+IP Destination Address of the packet, terminate a transport connection nor
+generate arbitrary packets. For example, Firewalls, Intrusion Detection Systems,
+Deep Packet Inspectors are among the appliances that can be supported in this
+scenario.
+
+## Pseudo-code
+
+When instantiating an End.AM SID, the following parameters are required:
+
+- APP-ADDR: IP or Ethernet address of the appliance
+- IFACE-OUT: local interface for sending traffic towards the appliance
+- IFACE-IN: local interface receiving the traffic coming back from the appliance
+
+Packets can be sent to and received from an appliance on the same interface
+(IFACE-IN = IFACE-OUT).
+
+### Masquerading
+
+Upon receiving a packet destined to S, where S is a local End.AM SID, a node N
+does:
+
+	IF NH=SRH & SL > 0 THEN                      			;; Ref1
+		Decrement SL
+		Write the last SID in the DA
+		Forward the packet on IFACE-OUT
+	ELSE
+		Drop the packet
+
+**Ref1:** an End.AM must not be the last SID.
+
+### De-masquerading
+
+Upon receiving a non-link-local IPv6 packet on IFACE-IN, a node N does:
+
+	IF NH=SRH THEN
+		Replace IP DA with SRH[SL]
+		Lookup DA in the appropriate table and proceed accordingly
+
+De-masquerading is a policy attached to IFACE-IN that intercepts all packets
+coming back from the appliance and restores the destination address.  This
+occurs before any lookup on the packet destination address (e.g. in "My Local
+SIDs" table or in the FIB) is performed.
+
+## Benefits
+
+The End.AM masquerading function brings the following benefits:
+
+1. The appliance receives a packet with the source and destination addresses
+respectively set as the original source and the final destination.
+2. The appliance does not try and inspect the SRH, as RFC2460 specifies that
+routing extension headers are not examined or processed by transit nodes.
+
+## Limitations
+
+An End.AM SID may be present in any number of segment lists at the same time.
+
+However, since the returning traffic from the appliance is processed based on
+the receiving interface (IFACE-IN), this interface may only be bound to a single
+End.AM SID at a time.
+
+In the case of a bi-directional service chain, the same End.AM SID and receiving
+interface (IFACE-IN) may be used in both directions.
+
+## Configuration
+
+The following CLI instantiates a new End.AM segment that sends masqueraded
+traffic on interface `IFACE-OUT` towards an appliance at address `APP-ADDR` and
+restores the active segment in the IPv6 header of the packets coming back on
+interface `IFACE-IN`.
+
+	sr localsid address SID behavior end.am nh APP-ADDR oif IFACE-OUT iif IFACE-IN
+
+For example, the following command configures the SID `1::A1` with an End.AM
+function for sending traffic on interface `GigabitEthernet0/8/0` to the appliance at
+address `A1::`, and receiving it back on interface `GigabitEthernet0/9/0`.
+
+	sr localsid address 1::A1 behavior end.am nh A1:: oif GigabitEthernet0/8/0 iif GigabitEthernet0/9/0
+

src/plugins/srv6_am.am

@@ -0,0 +1,22 @@
+# Copyright (c) 2016 Cisco Systems, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+vppplugins_LTLIBRARIES += srv6am_plugin.la
+
+srv6am_plugin_la_SOURCES =			\
+	srv6-am/am.c	\
+	srv6-am/node.c
+
+noinst_HEADERS += srv6-am/am.h
+
+# vi:syntax=automake