src/vnet/ip/ip4_source_check.c - fdio/vpp - Gitiles

 /*
  * 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.
  */
 /*
  * ip/ip4_source_check.c: IP v4 check source address (unicast RPF check)
  *
  * Copyright (c) 2008 Eliot Dresselhaus
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */

 #include <vnet/ip/ip.h>
 #include <vnet/fib/ip4_fib.h>
 #include <vnet/fib/fib_urpf_list.h>
 #include <vnet/dpo/load_balance.h>

 /**
  * @file
  * @brief IPv4 Unicast Source Check.
  *
  * This file contains the IPv4 interface unicast source check.
  */


 typedef struct
 {
   u8 packet_data[64];
   index_t urpf;
 } ip4_source_check_trace_t;

 static u8 *
 format_ip4_source_check_trace (u8 * s, va_list * va)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
   ip4_source_check_trace_t *t = va_arg (*va, ip4_source_check_trace_t *);

   s = format (s, "%U",
 	      format_ip4_header, t->packet_data, sizeof (t->packet_data));

   return s;
 }

 typedef enum
 {
   IP4_SOURCE_CHECK_NEXT_DROP,
   IP4_SOURCE_CHECK_N_NEXT,
 } ip4_source_check_next_t;

 typedef enum
 {
   IP4_SOURCE_CHECK_REACHABLE_VIA_RX,
   IP4_SOURCE_CHECK_REACHABLE_VIA_ANY,
 } ip4_source_check_type_t;

 typedef union
 {
   u32 fib_index;
 } ip4_source_check_config_t;

 always_inline uword
 ip4_source_check_inline (vlib_main_t * vm,
 			 vlib_node_runtime_t * node,
 			 vlib_frame_t * frame,
 			 ip4_source_check_type_t source_check_type)
 {
   u32 n_left_from, *from, *to_next;
   u32 next_index;
   vlib_node_runtime_t *error_node =
     vlib_node_get_runtime (vm, ip4_input_node.index);

   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
   next_index = node->cached_next_index;

   if (node->flags & VLIB_NODE_FLAG_TRACE)
     vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
 				   /* stride */ 1,
 				   sizeof (ip4_source_check_trace_t));

   while (n_left_from > 0)
     {
       u32 n_left_to_next;

       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

       while (n_left_from >= 4 && n_left_to_next >= 2)
 	{
 	  vlib_buffer_t *p0, *p1;
 	  ip4_header_t *ip0, *ip1;
 	  ip4_fib_mtrie_t *mtrie0, *mtrie1;
 	  ip4_fib_mtrie_leaf_t leaf0, leaf1;
 	  ip4_source_check_config_t *c0, *c1;
 	  const load_balance_t *lb0, *lb1;
 	  u32 pi0, next0, pass0, lb_index0;
 	  u32 pi1, next1, pass1, lb_index1;

 	  /* Prefetch next iteration. */
 	  {
 	    vlib_buffer_t *p2, *p3;

 	    p2 = vlib_get_buffer (vm, from[2]);
 	    p3 = vlib_get_buffer (vm, from[3]);

 	    vlib_prefetch_buffer_header (p2, LOAD);
 	    vlib_prefetch_buffer_header (p3, LOAD);

 	    CLIB_PREFETCH (p2->data, sizeof (ip0[0]), LOAD);
 	    CLIB_PREFETCH (p3->data, sizeof (ip1[0]), LOAD);
 	  }

 	  pi0 = to_next[0] = from[0];
 	  pi1 = to_next[1] = from[1];
 	  from += 2;
 	  to_next += 2;
 	  n_left_from -= 2;
 	  n_left_to_next -= 2;

 	  p0 = vlib_get_buffer (vm, pi0);
 	  p1 = vlib_get_buffer (vm, pi1);

 	  ip0 = vlib_buffer_get_current (p0);
 	  ip1 = vlib_buffer_get_current (p1);

 	  c0 = vnet_feature_next_with_data (&next0, p0, sizeof (c0[0]));
 	  c1 = vnet_feature_next_with_data (&next1, p1, sizeof (c1[0]));

 	  mtrie0 = &ip4_fib_get (c0->fib_index)->mtrie;
 	  mtrie1 = &ip4_fib_get (c1->fib_index)->mtrie;

 	  leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);
 	  leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, &ip1->src_address);

 	  leaf0 =
 	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);
 	  leaf1 =
 	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 2);

 	  leaf0 =
 	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
 	  leaf1 =
 	    ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 3);

 	  lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
 	  lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);

 	  lb0 = load_balance_get (lb_index0);
 	  lb1 = load_balance_get (lb_index1);

 	  /* Pass multicast. */
 	  pass0 = ip4_address_is_multicast (&ip0->src_address)
 	    || ip0->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);
 	  pass1 = ip4_address_is_multicast (&ip1->src_address)
 	    || ip1->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);

 	  if (IP4_SOURCE_CHECK_REACHABLE_VIA_RX == source_check_type)
 	    {
 	      pass0 |= fib_urpf_check (lb0->lb_urpf,
 				       vnet_buffer (p0)->sw_if_index
 				       [VLIB_RX]);
 	      pass1 |=
 		fib_urpf_check (lb1->lb_urpf,
 				vnet_buffer (p1)->sw_if_index[VLIB_RX]);
 	    }
 	  else
 	    {
 	      pass0 |= fib_urpf_check_size (lb0->lb_urpf);
 	      pass1 |= fib_urpf_check_size (lb1->lb_urpf);
 	    }
 	  next0 = (pass0 ? next0 : IP4_SOURCE_CHECK_NEXT_DROP);
 	  next1 = (pass1 ? next1 : IP4_SOURCE_CHECK_NEXT_DROP);

 	  p0->error =
 	    error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];
 	  p1->error =
 	    error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];

 	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   pi0, pi1, next0, next1);
 	}

       while (n_left_from > 0 && n_left_to_next > 0)
 	{
 	  vlib_buffer_t *p0;
 	  ip4_header_t *ip0;
 	  ip4_fib_mtrie_t *mtrie0;
 	  ip4_fib_mtrie_leaf_t leaf0;
 	  ip4_source_check_config_t *c0;
 	  u32 pi0, next0, pass0, lb_index0;
 	  const load_balance_t *lb0;

 	  pi0 = from[0];
 	  to_next[0] = pi0;
 	  from += 1;
 	  to_next += 1;
 	  n_left_from -= 1;
 	  n_left_to_next -= 1;

 	  p0 = vlib_get_buffer (vm, pi0);
 	  ip0 = vlib_buffer_get_current (p0);

 	  c0 = vnet_feature_next_with_data (&next0, p0, sizeof (c0[0]));

 	  mtrie0 = &ip4_fib_get (c0->fib_index)->mtrie;

 	  leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);

 	  leaf0 =
 	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);

 	  leaf0 =
 	    ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);

 	  lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);

 	  lb0 = load_balance_get (lb_index0);

 	  /* Pass multicast. */
 	  pass0 = ip4_address_is_multicast (&ip0->src_address)
 	    || ip0->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);

 	  if (IP4_SOURCE_CHECK_REACHABLE_VIA_RX == source_check_type)
 	    {
 	      pass0 |= fib_urpf_check (lb0->lb_urpf,
 				       vnet_buffer (p0)->sw_if_index
 				       [VLIB_RX]);
 	    }
 	  else
 	    {
 	      pass0 |= fib_urpf_check_size (lb0->lb_urpf);
 	    }

 	  next0 = (pass0 ? next0 : IP4_SOURCE_CHECK_NEXT_DROP);
 	  p0->error =
 	    error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];

 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   pi0, next0);
 	}

       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }

   return frame->n_vectors;
 }

 static uword
 ip4_source_check_reachable_via_any (vlib_main_t * vm,
 				    vlib_node_runtime_t * node,
 				    vlib_frame_t * frame)
 {
   return ip4_source_check_inline (vm, node, frame,
 				  IP4_SOURCE_CHECK_REACHABLE_VIA_ANY);
 }

 static uword
 ip4_source_check_reachable_via_rx (vlib_main_t * vm,
 				   vlib_node_runtime_t * node,
 				   vlib_frame_t * frame)
 {
   return ip4_source_check_inline (vm, node, frame,
 				  IP4_SOURCE_CHECK_REACHABLE_VIA_RX);
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (ip4_check_source_reachable_via_any) = {
   .function = ip4_source_check_reachable_via_any,
   .name = "ip4-source-check-via-any",
   .vector_size = sizeof (u32),

   .n_next_nodes = IP4_SOURCE_CHECK_N_NEXT,
   .next_nodes = {
     [IP4_SOURCE_CHECK_NEXT_DROP] = "ip4-drop",
   },

   .format_buffer = format_ip4_header,
   .format_trace = format_ip4_source_check_trace,
 };
 /* *INDENT-ON* */

 VLIB_NODE_FUNCTION_MULTIARCH (ip4_check_source_reachable_via_any,
 			      ip4_source_check_reachable_via_any);

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (ip4_check_source_reachable_via_rx) = {
   .function = ip4_source_check_reachable_via_rx,
   .name = "ip4-source-check-via-rx",
   .vector_size = sizeof (u32),

   .n_next_nodes = IP4_SOURCE_CHECK_N_NEXT,
   .next_nodes = {
     [IP4_SOURCE_CHECK_NEXT_DROP] = "ip4-drop",
   },

   .format_buffer = format_ip4_header,
   .format_trace = format_ip4_source_check_trace,
 };
 /* *INDENT-ON* */

 VLIB_NODE_FUNCTION_MULTIARCH (ip4_check_source_reachable_via_rx,
 			      ip4_source_check_reachable_via_rx);

 static clib_error_t *
 set_ip_source_check (vlib_main_t * vm,
 		     unformat_input_t * input, vlib_cli_command_t * cmd)
 {
   unformat_input_t _line_input, *line_input = &_line_input;
   vnet_main_t *vnm = vnet_get_main ();
   ip4_main_t *im = &ip4_main;
   clib_error_t *error = 0;
   u32 sw_if_index, is_del;
   ip4_source_check_config_t config;
   char *feature_name = "ip4-source-check-via-rx";

   sw_if_index = ~0;
   is_del = 0;

   if (!unformat_user (input, unformat_line_input, line_input))
     return 0;

   while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
     {
       if (unformat_user
 	  (line_input, unformat_vnet_sw_interface, vnm, &sw_if_index))
 	;
       else if (unformat (line_input, "del"))
 	is_del = 1;
       else if (unformat (line_input, "loose"))
 	feature_name = "ip4-source-check-via-any";
       else
 	{
 	  error = unformat_parse_error (line_input);
 	  goto done;
 	}
     }

   if (~0 == sw_if_index)
     {
       error = clib_error_return (0, "unknown interface `%U'",
 				 format_unformat_error, line_input);
       goto done;
     }

   config.fib_index = im->fib_index_by_sw_if_index[sw_if_index];
   vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index,
 			       is_del == 0, &config, sizeof (config));
 done:
   unformat_free (line_input);

   return error;
 }

 /*?
  * This command adds the 'ip4-source-check-via-rx' graph node for
  * a given interface. By adding the IPv4 source check graph node to
  * an interface, the code verifies that the source address of incoming
  * unicast packets are reachable over the incoming interface. Two flavours
  * are supported (the default is strict):
  * - loose: accept ingress packet if there is a route to reach the source
  * - strict: accept ingress packet if it arrived on an interface which
  *          the route to the source uses. i.e. an interface that the source
  *          is reachable via.
  *
  * @cliexpar
  * @parblock
  * Example of graph node before range checking is enabled:
  * @cliexstart{show vlib graph ip4-source-check-via-rx}
  *            Name                      Next                    Previous
  * ip4-source-check-via-rx         ip4-drop [0]
  * @cliexend
  *
  * Example of how to enable unicast source checking on an interface:
  * @cliexcmd{set interface ip source-check GigabitEthernet2/0/0 loose}
  *
  * Example of graph node after range checking is enabled:
  * @cliexstart{show vlib graph ip4-source-check-via-rx}
  *            Name                      Next                    Previous
  * ip4-source-check-via-rx         ip4-drop [0]           ip4-input-no-checksum
  *                           ip4-source-and-port-range-         ip4-input
  * @cliexend
  *
  * Example of how to display the feature enabed on an interface:
  * @cliexstart{show ip interface features GigabitEthernet2/0/0}
  * IP feature paths configured on GigabitEthernet2/0/0...
  *
  * ipv4 unicast:
  *   ip4-source-check-via-rx
  *   ip4-lookup
  *
  * ipv4 multicast:
  *   ip4-lookup-multicast
  *
  * ipv4 multicast:
  *   interface-output
  *
  * ipv6 unicast:
  *   ip6-lookup
  *
  * ipv6 multicast:
  *   ip6-lookup
  *
  * ipv6 multicast:
  *   interface-output
  * @cliexend
  *
  * Example of how to disable unicast source checking on an interface:
  * @cliexcmd{set interface ip source-check GigabitEthernet2/0/0 del}
  * @endparblock
 ?*/
 /* *INDENT-OFF* */
 VLIB_CLI_COMMAND (set_interface_ip_source_check_command, static) = {
   .path = "set interface ip source-check",
   .function = set_ip_source_check,
   .short_help = "set interface ip source-check <interface> [strict|loose] [del]",
 };
 /* *INDENT-ON* */

 static clib_error_t *
 ip_source_check_accept (vlib_main_t * vm,
 			unformat_input_t * input, vlib_cli_command_t * cmd)
 {
   unformat_input_t _line_input, *line_input = &_line_input;
   fib_prefix_t pfx = {
     .fp_proto = FIB_PROTOCOL_IP4,
   };
   clib_error_t *error = NULL;
   u32 table_id, is_add, fib_index;

   is_add = 1;
   table_id = ~0;

   /* Get a line of input. */
   if (!unformat_user (input, unformat_line_input, line_input))
     return 0;

   while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
     {
       if (unformat (line_input, "table %d", &table_id))
 	;
       else if (unformat (line_input, "del"))
 	is_add = 0;
       else if (unformat (line_input, "add"))
 	is_add = 1;
       else if (unformat (line_input, "%U/%d",
 			 unformat_ip4_address, &pfx.fp_addr.ip4, &pfx.fp_len))
 	pfx.fp_proto = FIB_PROTOCOL_IP4;
       else
 	{
 	  error = unformat_parse_error (line_input);
 	  goto done;
 	}
     }

   if (~0 != table_id)
     {
       fib_index = fib_table_find (pfx.fp_proto, table_id);
       if (~0 == fib_index)
 	{
 	  error = clib_error_return (0, "Nonexistent table id %d", table_id);
 	  goto done;
 	}
     }
   else
     {
       fib_index = 0;
     }

   if (is_add)
     {
       fib_table_entry_special_add (fib_index,
 				   &pfx,
 				   FIB_SOURCE_URPF_EXEMPT,
 				   FIB_ENTRY_FLAG_DROP);
     }
   else
     {
       fib_table_entry_special_remove (fib_index,
 				      &pfx, FIB_SOURCE_URPF_EXEMPT);
     }

 done:
   unformat_free (line_input);

   return error;
 }

 /*?
  * Add an exemption for a prefix to pass the Unicast Reverse Path
  * Forwarding (uRPF) loose check. This is for testing purposes only.
  * If the '<em>table</em>' is not enter it is defaulted to 0. Default
  * is to '<em>add</em>'. VPP always performs a loose uRPF check for
  * for-us traffic.
  *
  * @cliexpar
  * Example of how to add a uRPF exception to a FIB table to pass the
  * loose RPF tests:
  * @cliexcmd{ip urpf-accept table 7 add}
 ?*/
 /* *INDENT-OFF* */
 VLIB_CLI_COMMAND (ip_source_check_accept_command, static) = {
   .path = "ip urpf-accept",
   .function = ip_source_check_accept,
   .short_help = "ip urpf-accept [table <table-id>] [add|del]",
 };
 /* *INDENT-ON* */


 /* Dummy init function to get us linked in. */
 clib_error_t *
 ip4_source_check_init (vlib_main_t * vm)
 {
   return 0;
 }

 VLIB_INIT_FUNCTION (ip4_source_check_init);

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* 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.
	*/
	/*
	* ip/ip4_source_check.c: IP v4 check source address (unicast RPF check)
	*
	* Copyright (c) 2008 Eliot Dresselhaus
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
	* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
	* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
	* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/

	#include <vnet/ip/ip.h>
	#include <vnet/fib/ip4_fib.h>
	#include <vnet/fib/fib_urpf_list.h>
	#include <vnet/dpo/load_balance.h>

	/**
	* @file
	* @brief IPv4 Unicast Source Check.
	*
	* This file contains the IPv4 interface unicast source check.
	*/


	typedef struct
	{
	u8 packet_data[64];
	index_t urpf;
	} ip4_source_check_trace_t;

	static u8 *
	format_ip4_source_check_trace (u8 * s, va_list * va)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (va, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (va, vlib_node_t );
	ip4_source_check_trace_t t = va_arg (va, ip4_source_check_trace_t *);

	s = format (s, "%U",
	format_ip4_header, t->packet_data, sizeof (t->packet_data));

	return s;
	}

	typedef enum
	{
	IP4_SOURCE_CHECK_NEXT_DROP,
	IP4_SOURCE_CHECK_N_NEXT,
	} ip4_source_check_next_t;

	typedef enum
	{
	IP4_SOURCE_CHECK_REACHABLE_VIA_RX,
	IP4_SOURCE_CHECK_REACHABLE_VIA_ANY,
	} ip4_source_check_type_t;

	typedef union
	{
	u32 fib_index;
	} ip4_source_check_config_t;

	always_inline uword
	ip4_source_check_inline (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	vlib_frame_t * frame,
	ip4_source_check_type_t source_check_type)
	{
	u32 n_left_from, from, to_next;
	u32 next_index;
	vlib_node_runtime_t *error_node =
	vlib_node_get_runtime (vm, ip4_input_node.index);

	from = vlib_frame_vector_args (frame);
	n_left_from = frame->n_vectors;
	next_index = node->cached_next_index;

	if (node->flags & VLIB_NODE_FLAG_TRACE)
	vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
	/* stride */ 1,
	sizeof (ip4_source_check_trace_t));

	while (n_left_from > 0)
	{
	u32 n_left_to_next;

	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	while (n_left_from >= 4 && n_left_to_next >= 2)
	{
	vlib_buffer_t p0, p1;
	ip4_header_t ip0, ip1;
	ip4_fib_mtrie_t mtrie0, mtrie1;
	ip4_fib_mtrie_leaf_t leaf0, leaf1;
	ip4_source_check_config_t c0, c1;
	const load_balance_t lb0, lb1;
	u32 pi0, next0, pass0, lb_index0;
	u32 pi1, next1, pass1, lb_index1;

	/* Prefetch next iteration. */
	{
	vlib_buffer_t p2, p3;

	p2 = vlib_get_buffer (vm, from[2]);
	p3 = vlib_get_buffer (vm, from[3]);

	vlib_prefetch_buffer_header (p2, LOAD);
	vlib_prefetch_buffer_header (p3, LOAD);

	CLIB_PREFETCH (p2->data, sizeof (ip0[0]), LOAD);
	CLIB_PREFETCH (p3->data, sizeof (ip1[0]), LOAD);
	}

	pi0 = to_next[0] = from[0];
	pi1 = to_next[1] = from[1];
	from += 2;
	to_next += 2;
	n_left_from -= 2;
	n_left_to_next -= 2;

	p0 = vlib_get_buffer (vm, pi0);
	p1 = vlib_get_buffer (vm, pi1);

	ip0 = vlib_buffer_get_current (p0);
	ip1 = vlib_buffer_get_current (p1);

	c0 = vnet_feature_next_with_data (&next0, p0, sizeof (c0[0]));
	c1 = vnet_feature_next_with_data (&next1, p1, sizeof (c1[0]));

	mtrie0 = &ip4_fib_get (c0->fib_index)->mtrie;
	mtrie1 = &ip4_fib_get (c1->fib_index)->mtrie;

	leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);
	leaf1 = ip4_fib_mtrie_lookup_step_one (mtrie1, &ip1->src_address);

	leaf0 =
	ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);
	leaf1 =
	ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 2);

	leaf0 =
	ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);
	leaf1 =
	ip4_fib_mtrie_lookup_step (mtrie1, leaf1, &ip1->src_address, 3);

	lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);
	lb_index1 = ip4_fib_mtrie_leaf_get_adj_index (leaf1);

	lb0 = load_balance_get (lb_index0);
	lb1 = load_balance_get (lb_index1);

	/* Pass multicast. */
	pass0 = ip4_address_is_multicast (&ip0->src_address)
	\|\| ip0->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);
	pass1 = ip4_address_is_multicast (&ip1->src_address)
	\|\| ip1->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);

	if (IP4_SOURCE_CHECK_REACHABLE_VIA_RX == source_check_type)
	{
	pass0 \|= fib_urpf_check (lb0->lb_urpf,
	vnet_buffer (p0)->sw_if_index
	[VLIB_RX]);
	pass1 \|=
	fib_urpf_check (lb1->lb_urpf,
	vnet_buffer (p1)->sw_if_index[VLIB_RX]);
	}
	else
	{
	pass0 \|= fib_urpf_check_size (lb0->lb_urpf);
	pass1 \|= fib_urpf_check_size (lb1->lb_urpf);
	}
	next0 = (pass0 ? next0 : IP4_SOURCE_CHECK_NEXT_DROP);
	next1 = (pass1 ? next1 : IP4_SOURCE_CHECK_NEXT_DROP);

	p0->error =
	error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];
	p1->error =
	error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];

	vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
	to_next, n_left_to_next,
	pi0, pi1, next0, next1);
	}

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	vlib_buffer_t *p0;
	ip4_header_t *ip0;
	ip4_fib_mtrie_t *mtrie0;
	ip4_fib_mtrie_leaf_t leaf0;
	ip4_source_check_config_t *c0;
	u32 pi0, next0, pass0, lb_index0;
	const load_balance_t *lb0;

	pi0 = from[0];
	to_next[0] = pi0;
	from += 1;
	to_next += 1;
	n_left_from -= 1;
	n_left_to_next -= 1;

	p0 = vlib_get_buffer (vm, pi0);
	ip0 = vlib_buffer_get_current (p0);

	c0 = vnet_feature_next_with_data (&next0, p0, sizeof (c0[0]));

	mtrie0 = &ip4_fib_get (c0->fib_index)->mtrie;

	leaf0 = ip4_fib_mtrie_lookup_step_one (mtrie0, &ip0->src_address);

	leaf0 =
	ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 2);

	leaf0 =
	ip4_fib_mtrie_lookup_step (mtrie0, leaf0, &ip0->src_address, 3);

	lb_index0 = ip4_fib_mtrie_leaf_get_adj_index (leaf0);

	lb0 = load_balance_get (lb_index0);

	/* Pass multicast. */
	pass0 = ip4_address_is_multicast (&ip0->src_address)
	\|\| ip0->src_address.as_u32 == clib_host_to_net_u32 (0xFFFFFFFF);

	if (IP4_SOURCE_CHECK_REACHABLE_VIA_RX == source_check_type)
	{
	pass0 \|= fib_urpf_check (lb0->lb_urpf,
	vnet_buffer (p0)->sw_if_index
	[VLIB_RX]);
	}
	else
	{
	pass0 \|= fib_urpf_check_size (lb0->lb_urpf);
	}

	next0 = (pass0 ? next0 : IP4_SOURCE_CHECK_NEXT_DROP);
	p0->error =
	error_node->errors[IP4_ERROR_UNICAST_SOURCE_CHECK_FAILS];

	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next,
	pi0, next0);
	}

	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}

	return frame->n_vectors;
	}

	static uword
	ip4_source_check_reachable_via_any (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	vlib_frame_t * frame)
	{
	return ip4_source_check_inline (vm, node, frame,
	IP4_SOURCE_CHECK_REACHABLE_VIA_ANY);
	}

	static uword
	ip4_source_check_reachable_via_rx (vlib_main_t * vm,
	vlib_node_runtime_t * node,
	vlib_frame_t * frame)
	{
	return ip4_source_check_inline (vm, node, frame,
	IP4_SOURCE_CHECK_REACHABLE_VIA_RX);
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (ip4_check_source_reachable_via_any) = {
	.function = ip4_source_check_reachable_via_any,
	.name = "ip4-source-check-via-any",
	.vector_size = sizeof (u32),

	.n_next_nodes = IP4_SOURCE_CHECK_N_NEXT,
	.next_nodes = {
	[IP4_SOURCE_CHECK_NEXT_DROP] = "ip4-drop",
	},

	.format_buffer = format_ip4_header,
	.format_trace = format_ip4_source_check_trace,
	};
	/* INDENT-ON */

	VLIB_NODE_FUNCTION_MULTIARCH (ip4_check_source_reachable_via_any,
	ip4_source_check_reachable_via_any);

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (ip4_check_source_reachable_via_rx) = {
	.function = ip4_source_check_reachable_via_rx,
	.name = "ip4-source-check-via-rx",
	.vector_size = sizeof (u32),

	.n_next_nodes = IP4_SOURCE_CHECK_N_NEXT,
	.next_nodes = {
	[IP4_SOURCE_CHECK_NEXT_DROP] = "ip4-drop",
	},

	.format_buffer = format_ip4_header,
	.format_trace = format_ip4_source_check_trace,
	};
	/* INDENT-ON */

	VLIB_NODE_FUNCTION_MULTIARCH (ip4_check_source_reachable_via_rx,
	ip4_source_check_reachable_via_rx);

	static clib_error_t *
	set_ip_source_check (vlib_main_t * vm,
	unformat_input_t * input, vlib_cli_command_t * cmd)
	{
	unformat_input_t _line_input, *line_input = &_line_input;
	vnet_main_t *vnm = vnet_get_main ();
	ip4_main_t *im = &ip4_main;
	clib_error_t *error = 0;
	u32 sw_if_index, is_del;
	ip4_source_check_config_t config;
	char *feature_name = "ip4-source-check-via-rx";

	sw_if_index = ~0;
	is_del = 0;

	if (!unformat_user (input, unformat_line_input, line_input))
	return 0;

	while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
	{
	if (unformat_user
	(line_input, unformat_vnet_sw_interface, vnm, &sw_if_index))
	;
	else if (unformat (line_input, "del"))
	is_del = 1;
	else if (unformat (line_input, "loose"))
	feature_name = "ip4-source-check-via-any";
	else
	{
	error = unformat_parse_error (line_input);
	goto done;
	}
	}

	if (~0 == sw_if_index)
	{
	error = clib_error_return (0, "unknown interface `%U'",
	format_unformat_error, line_input);
	goto done;
	}

	config.fib_index = im->fib_index_by_sw_if_index[sw_if_index];
	vnet_feature_enable_disable ("ip4-unicast", feature_name, sw_if_index,
	is_del == 0, &config, sizeof (config));
	done:
	unformat_free (line_input);

	return error;
	}

	/*?
	* This command adds the 'ip4-source-check-via-rx' graph node for
	* a given interface. By adding the IPv4 source check graph node to
	* an interface, the code verifies that the source address of incoming
	* unicast packets are reachable over the incoming interface. Two flavours
	* are supported (the default is strict):
	* - loose: accept ingress packet if there is a route to reach the source
	* - strict: accept ingress packet if it arrived on an interface which
	* the route to the source uses. i.e. an interface that the source
	* is reachable via.
	*
	* @cliexpar
	* @parblock
	* Example of graph node before range checking is enabled:
	* @cliexstart{show vlib graph ip4-source-check-via-rx}
	* Name Next Previous
	* ip4-source-check-via-rx ip4-drop [0]
	* @cliexend
	*
	* Example of how to enable unicast source checking on an interface:
	* @cliexcmd{set interface ip source-check GigabitEthernet2/0/0 loose}
	*
	* Example of graph node after range checking is enabled:
	* @cliexstart{show vlib graph ip4-source-check-via-rx}
	* Name Next Previous
	* ip4-source-check-via-rx ip4-drop [0] ip4-input-no-checksum
	* ip4-source-and-port-range- ip4-input
	* @cliexend
	*
	* Example of how to display the feature enabed on an interface:
	* @cliexstart{show ip interface features GigabitEthernet2/0/0}
	* IP feature paths configured on GigabitEthernet2/0/0...
	*
	* ipv4 unicast:
	* ip4-source-check-via-rx
	* ip4-lookup
	*
	* ipv4 multicast:
	* ip4-lookup-multicast
	*
	* ipv4 multicast:
	* interface-output
	*
	* ipv6 unicast:
	* ip6-lookup
	*
	* ipv6 multicast:
	* ip6-lookup
	*
	* ipv6 multicast:
	* interface-output
	* @cliexend
	*
	* Example of how to disable unicast source checking on an interface:
	* @cliexcmd{set interface ip source-check GigabitEthernet2/0/0 del}
	* @endparblock
	?*/
	/* INDENT-OFF */
	VLIB_CLI_COMMAND (set_interface_ip_source_check_command, static) = {
	.path = "set interface ip source-check",
	.function = set_ip_source_check,
	.short_help = "set interface ip source-check <interface> [strict\|loose] [del]",
	};
	/* INDENT-ON */

	static clib_error_t *
	ip_source_check_accept (vlib_main_t * vm,
	unformat_input_t * input, vlib_cli_command_t * cmd)
	{
	unformat_input_t _line_input, *line_input = &_line_input;
	fib_prefix_t pfx = {
	.fp_proto = FIB_PROTOCOL_IP4,
	};
	clib_error_t *error = NULL;
	u32 table_id, is_add, fib_index;

	is_add = 1;
	table_id = ~0;

	/* Get a line of input. */
	if (!unformat_user (input, unformat_line_input, line_input))
	return 0;

	while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
	{
	if (unformat (line_input, "table %d", &table_id))
	;
	else if (unformat (line_input, "del"))
	is_add = 0;
	else if (unformat (line_input, "add"))
	is_add = 1;
	else if (unformat (line_input, "%U/%d",
	unformat_ip4_address, &pfx.fp_addr.ip4, &pfx.fp_len))
	pfx.fp_proto = FIB_PROTOCOL_IP4;
	else
	{
	error = unformat_parse_error (line_input);
	goto done;
	}
	}

	if (~0 != table_id)
	{
	fib_index = fib_table_find (pfx.fp_proto, table_id);
	if (~0 == fib_index)
	{
	error = clib_error_return (0, "Nonexistent table id %d", table_id);
	goto done;
	}
	}
	else
	{
	fib_index = 0;
	}

	if (is_add)
	{
	fib_table_entry_special_add (fib_index,
	&pfx,
	FIB_SOURCE_URPF_EXEMPT,
	FIB_ENTRY_FLAG_DROP);
	}
	else
	{
	fib_table_entry_special_remove (fib_index,
	&pfx, FIB_SOURCE_URPF_EXEMPT);
	}

	done:
	unformat_free (line_input);

	return error;
	}

	/*?
	* Add an exemption for a prefix to pass the Unicast Reverse Path
	* Forwarding (uRPF) loose check. This is for testing purposes only.
	* If the '<em>table</em>' is not enter it is defaulted to 0. Default
	* is to '<em>add</em>'. VPP always performs a loose uRPF check for
	* for-us traffic.
	*
	* @cliexpar
	* Example of how to add a uRPF exception to a FIB table to pass the
	* loose RPF tests:
	* @cliexcmd{ip urpf-accept table 7 add}
	?*/
	/* INDENT-OFF */
	VLIB_CLI_COMMAND (ip_source_check_accept_command, static) = {
	.path = "ip urpf-accept",
	.function = ip_source_check_accept,
	.short_help = "ip urpf-accept [table <table-id>] [add\|del]",
	};
	/* INDENT-ON */


	/* Dummy init function to get us linked in. */
	clib_error_t *
	ip4_source_check_init (vlib_main_t * vm)
	{
	return 0;
	}

	VLIB_INIT_FUNCTION (ip4_source_check_init);

	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/