l2_efp_filter.c

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/*
 * l2_efp_filter.c : layer 2 egress EFP Filter processing
 *
 * Copyright (c) 2013 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.
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/ethernet/packet.h>
#include <vnet/l2/feat_bitmap.h>
#include <vnet/l2/l2_output.h>
#include <vnet/ethernet/ethernet.h>

#include <vppinfra/error.h>
#include <vppinfra/cache.h>

typedef struct {

  // Next nodes for features and output interfaces
  l2_output_next_nodes_st next_nodes;

  /* convenience variables */
  vlib_main_t * vlib_main;
  vnet_main_t * vnet_main;
} l2_efp_filter_main_t;


typedef struct {
  /* per-pkt trace data */ 
  u8 src[6];
  u8 dst[6];
  u8  raw[12]; // raw data (vlans)
  u32 sw_if_index;
} l2_efp_filter_trace_t;

/* packet trace format function */
static u8 * format_l2_efp_filter_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  l2_efp_filter_trace_t * t = va_arg (*args, l2_efp_filter_trace_t *);
  
  s = format (s, "l2-output-vtr: sw_if_index %d dst %U src %U data "
              "%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
              t->sw_if_index,
              format_ethernet_address, t->dst,
              format_ethernet_address, t->src,
              t->raw[0], t->raw[1], t->raw[2], t->raw[3], t->raw[4], t->raw[5],
              t->raw[6], t->raw[7], t->raw[8], t->raw[9], t->raw[10], t->raw[11]);
  return s;
}

l2_efp_filter_main_t l2_efp_filter_main;

static vlib_node_registration_t l2_efp_filter_node;

#define foreach_l2_efp_filter_error                     \
_(L2_EFP_FILTER, "L2 EFP filter packets")               \
_(DROP,          "L2 EFP filter post-rewrite drops")

typedef enum {
#define _(sym,str) L2_EFP_FILTER_ERROR_##sym,
  foreach_l2_efp_filter_error
#undef _
  L2_EFP_FILTER_N_ERROR,
} l2_efp_filter_error_t;

static char * l2_efp_filter_error_strings[] = {
#define _(sym,string) string,
  foreach_l2_efp_filter_error
#undef _
};

typedef enum {  
  L2_EFP_FILTER_NEXT_DROP,
  L2_EFP_FILTER_N_NEXT,
} l2_efp_filter_next_t;


// Extract fields from the packet that will be used in interface classification
static_always_inline void
extract_keys (vnet_main_t * vnet_main,
              u32 sw_if_index0,
              vlib_buffer_t * b0, 
              u32 * port_sw_if_index0, 
              u16 * first_ethertype0,
              u16 * outer_id0,
              u16 * inner_id0,
              u32 * match_flags0)
{
  ethernet_header_t * e0;
  ethernet_vlan_header_t * h0;
  u32 tag_len;
  u32 tag_num;

  *port_sw_if_index0 = vnet_get_sup_sw_interface (vnet_main, sw_if_index0)->sw_if_index;

  e0 = vlib_buffer_get_current (b0);
  h0 = (ethernet_vlan_header_t *)(e0+1);

  *first_ethertype0 = clib_net_to_host_u16(e0->type);
  *outer_id0 = clib_net_to_host_u16 (h0[0].priority_cfi_and_id);
  *inner_id0 = clib_net_to_host_u16 (h0[1].priority_cfi_and_id);

  tag_len = vnet_buffer(b0)->l2.l2_len - sizeof(ethernet_header_t);
  tag_num = tag_len / sizeof(ethernet_vlan_header_t);
  *match_flags0 = eth_create_valid_subint_match_flags (tag_num);
}

/* 
 * EFP filtering is a basic switch feature which prevents an interface from 
 * transmitting a packet that doesn't match the interface's ingress match 
 * criteria. The check has two parts, one performed before egress vlan tag 
 * rewrite and one after.
 *
 * The pre-rewrite check insures the packet matches what an ingress packet looks 
 * like after going through the interface's ingress tag rewrite operation. Only 
 * pushed tags are compared. So:
 * - if the ingress vlan tag rewrite pushes no tags (or is not enabled),
 *   any packet passes the filter
 * - if the ingress vlan tag rewrite pushes one tag,
 *   the packet must have at least one tag, and the outer tag must match the pushed tag
 * - if the ingress vlan tag rewrite pushes two tags,
 *   the packet must have at least two tags, and the outer two tags must match the pushed tags
 *
 * The pre-rewrite check is performed in the l2-output node.
 *
 * The post-rewrite check insures the packet matches what an ingress packet looks 
 * like before going through the interface's ingress tag rewrite operation. It verifies 
 * that such a packet arriving on the wire at this port would be classified as arriving
 * an input interface equal to the packet's output interface. This can be done by running
 * the output packet's vlan tags and output port through the interface classification,
 * and checking if the resulting interface matches the output interface.
 *
 * The post-rewrite check is performed here.
 */

static uword
l2_efp_filter_node_fn (vlib_main_t * vm,
                       vlib_node_runtime_t * node,
                       vlib_frame_t * frame)
{
  u32 n_left_from, * from, * to_next;
  l2_efp_filter_next_t next_index;
  l2_efp_filter_main_t * msm = &l2_efp_filter_main;
  vlib_node_t *n = vlib_get_node (vm, l2_efp_filter_node.index);
  u32 node_counter_base_index = n->error_heap_index;
  vlib_error_main_t * em = &vm->error_main;
  u32 cached_sw_if_index = ~0;
  u32 cached_next_index = ~0;

  /* invalidate cache to begin with */
  cached_sw_if_index = ~0;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors; /* number of packets to process */
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      /* get space to enqueue frame to graph node "next_index" */
      vlib_get_next_frame (vm, node, next_index,
                           to_next, n_left_to_next);

      while (n_left_from >= 6 && n_left_to_next >= 2)
        {
          u32 bi0, bi1;
          vlib_buffer_t * b0, * b1;
          u32 next0, next1;
          u32 sw_if_index0, sw_if_index1;
          u32 feature_bitmap0, feature_bitmap1;
          u16 first_ethertype0, first_ethertype1;
          u16 outer_id0, inner_id0, outer_id1, inner_id1;
          u32 match_flags0, match_flags1;
          u32 port_sw_if_index0, subint_sw_if_index0, port_sw_if_index1, subint_sw_if_index1;
          vnet_hw_interface_t * hi0, * hi1;
          main_intf_t * main_intf0, * main_intf1;
          vlan_intf_t * vlan_intf0, * vlan_intf1;
          qinq_intf_t * qinq_intf0, * qinq_intf1;
          u32 is_l20, is_l21;
          __attribute__((unused)) u32 matched0, matched1;
          u8 error0, error1;
          
          /* Prefetch next iteration. */
          {
            vlib_buffer_t * p2, * p3, * p4, * p5;
            __attribute__((unused)) u32 sw_if_index2, sw_if_index3;
            
            p2 = vlib_get_buffer (vm, from[2]);
            p3 = vlib_get_buffer (vm, from[3]);
            p4 = vlib_get_buffer (vm, from[4]);
            p5 = vlib_get_buffer (vm, from[5]);
            
            // Prefetch the buffer header and packet for the N+2 loop iteration
            vlib_prefetch_buffer_header (p4, LOAD);
            vlib_prefetch_buffer_header (p5, LOAD);

            CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
            CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);

            // Prefetch the input config for the N+1 loop iteration
            // This depends on the buffer header above
            sw_if_index2 = vnet_buffer(p2)->sw_if_index[VLIB_TX];
            sw_if_index3 = vnet_buffer(p3)->sw_if_index[VLIB_TX];
            //TODO CLIB_PREFETCH (vec_elt_at_index(l2output_main.configs, sw_if_index2), CLIB_CACHE_LINE_BYTES, LOAD);
            //TODO CLIB_PREFETCH (vec_elt_at_index(l2output_main.configs, sw_if_index3), CLIB_CACHE_LINE_BYTES, LOAD);
          }

          /* speculatively enqueue b0 and b1 to the current next frame */
          /* bi is "buffer index", b is pointer to the buffer */
          to_next[0] = bi0 = from[0];
          to_next[1] = bi1 = from[1];
          from += 2;
          to_next += 2;
          n_left_from -= 2;
          n_left_to_next -= 2;

          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);
 
          /* TX interface handles */
          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];
          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_TX];

          // process 2 packets
          em->counters[node_counter_base_index + L2_EFP_FILTER_ERROR_L2_EFP_FILTER] += 2;

          // Remove ourself from the feature bitmap
          feature_bitmap0 = vnet_buffer(b0)->l2.feature_bitmap & ~L2OUTPUT_FEAT_EFP_FILTER;
          feature_bitmap1 = vnet_buffer(b1)->l2.feature_bitmap & ~L2OUTPUT_FEAT_EFP_FILTER;

          // Determine next node
          l2_output_dispatch (msm->vlib_main,
                              msm->vnet_main,
                              node,
                              l2_efp_filter_node.index,
                              &cached_sw_if_index,
                              &cached_next_index,
                              &msm->next_nodes,
                              b0,
                              sw_if_index0,
                              feature_bitmap0,
                              &next0);
          l2_output_dispatch (msm->vlib_main,
                              msm->vnet_main,
                              node,
                              l2_efp_filter_node.index,
                              &cached_sw_if_index,
                              &cached_next_index,
                              &msm->next_nodes,
                              b1,
                              sw_if_index1,
                              feature_bitmap1,
                              &next1);

          // perform the efp filter check on two packets

          extract_keys (msm->vnet_main,
                        sw_if_index0,
                        b0, 
                        &port_sw_if_index0, 
                        &first_ethertype0,
                        &outer_id0,
                        &inner_id0,
                        &match_flags0);

          extract_keys (msm->vnet_main,
                        sw_if_index1,
                        b1, 
                        &port_sw_if_index1, 
                        &first_ethertype1,
                        &outer_id1,
                        &inner_id1,
                        &match_flags1);

          eth_vlan_table_lookups (&ethernet_main,
                                  msm->vnet_main,
                                  port_sw_if_index0,
                                  first_ethertype0, 
                                  outer_id0,
                                  inner_id0,
                                  &hi0,
                                  &main_intf0, 
                                  &vlan_intf0,
                                  &qinq_intf0);

          eth_vlan_table_lookups (&ethernet_main,
                                  msm->vnet_main,
                                  port_sw_if_index1,
                                  first_ethertype1, 
                                  outer_id1,
                                  inner_id1,
                                  &hi1,
                                  &main_intf1, 
                                  &vlan_intf1,
                                  &qinq_intf1);

          matched0 = eth_identify_subint (hi0,
                                          b0,
                                          match_flags0, 
                                          main_intf0, 
                                          vlan_intf0, 
                                          qinq_intf0, 
                                          &subint_sw_if_index0, 
                                          &error0, 
                                          &is_l20);

          matched1 = eth_identify_subint (hi1,
                                          b1,
                                          match_flags1, 
                                          main_intf1, 
                                          vlan_intf1, 
                                          qinq_intf1, 
                                          &subint_sw_if_index1, 
                                          &error1, 
                                          &is_l21);

          if (PREDICT_FALSE (sw_if_index0 != subint_sw_if_index0)) {
            // Drop packet
            next0 = L2_EFP_FILTER_NEXT_DROP;
            b0->error = node->errors[L2_EFP_FILTER_ERROR_DROP];
          }

          if (PREDICT_FALSE (sw_if_index1 != subint_sw_if_index1)) {
            // Drop packet
            next1 = L2_EFP_FILTER_NEXT_DROP;
            b1->error = node->errors[L2_EFP_FILTER_ERROR_DROP];
          }

          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE))) {
            if (b0->flags & VLIB_BUFFER_IS_TRACED) {
              ethernet_header_t * h0 = vlib_buffer_get_current (b0);
              l2_efp_filter_trace_t *t = 
                 vlib_add_trace (vm, node, b0, sizeof (*t));
              t->sw_if_index = sw_if_index0;
              clib_memcpy(t->src, h0->src_address, 6);
              clib_memcpy(t->dst, h0->dst_address, 6);
              clib_memcpy(t->raw, &h0->type, sizeof(t->raw));
            }
            if (b1->flags & VLIB_BUFFER_IS_TRACED) {
              ethernet_header_t * h1 = vlib_buffer_get_current (b1);
              l2_efp_filter_trace_t *t =
                 vlib_add_trace (vm, node, b1, sizeof (*t));
              t->sw_if_index = sw_if_index1;
              clib_memcpy(t->src, h1->src_address, 6);
              clib_memcpy(t->dst, h1->dst_address, 6);
              clib_memcpy(t->raw, &h1->type, sizeof(t->raw));
            }
          }

          /* verify speculative enqueues, maybe switch current next frame */
          /* if next0==next1==next_index then nothing special needs to be done */
          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, next0, next1);
        }
      
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t * b0;
          u32 next0;
          u32 sw_if_index0;
          u32 feature_bitmap0;
          u16 first_ethertype0;
          u16 outer_id0, inner_id0;
          u32 match_flags0;
          u32 port_sw_if_index0, subint_sw_if_index0;
          vnet_hw_interface_t * hi0;
          main_intf_t * main_intf0;
          vlan_intf_t * vlan_intf0;
          qinq_intf_t * qinq_intf0;
          u32 is_l20;
          __attribute__((unused)) u32 matched0;
          u8 error0;

          /* speculatively enqueue b0 to the current next frame */
          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);
          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];

          // process 1 packet
          em->counters[node_counter_base_index + L2_EFP_FILTER_ERROR_L2_EFP_FILTER] += 1;

          // Remove ourself from the feature bitmap
          feature_bitmap0 = vnet_buffer(b0)->l2.feature_bitmap & ~L2OUTPUT_FEAT_EFP_FILTER;

          // Determine next node
          l2_output_dispatch (msm->vlib_main,
                              msm->vnet_main,
                              node,
                              l2_efp_filter_node.index,
                              &cached_sw_if_index,
                              &cached_next_index,
                              &msm->next_nodes,
                              b0,
                              sw_if_index0,
                              feature_bitmap0,
                              &next0);

          // perform the efp filter check on one packet

          extract_keys (msm->vnet_main,
                        sw_if_index0,
                        b0, 
                        &port_sw_if_index0, 
                        &first_ethertype0,
                        &outer_id0,
                        &inner_id0,
                        &match_flags0);

          eth_vlan_table_lookups (&ethernet_main,
                                  msm->vnet_main,
                                  port_sw_if_index0,
                                  first_ethertype0, 
                                  outer_id0,
                                  inner_id0,
                                  &hi0,
                                  &main_intf0, 
                                  &vlan_intf0,
                                  &qinq_intf0);

          matched0 = eth_identify_subint (hi0,
                                          b0,
                                          match_flags0, 
                                          main_intf0, 
                                          vlan_intf0, 
                                          qinq_intf0, 
                                          &subint_sw_if_index0, 
                                          &error0, 
                                          &is_l20);

          if (PREDICT_FALSE (sw_if_index0 != subint_sw_if_index0)) {
            // Drop packet
            next0 = L2_EFP_FILTER_NEXT_DROP;
            b0->error = node->errors[L2_EFP_FILTER_ERROR_DROP];
          }

          if (PREDICT_FALSE((node->flags & VLIB_NODE_FLAG_TRACE) 
                            && (b0->flags & VLIB_BUFFER_IS_TRACED))) {
            ethernet_header_t * h0 = vlib_buffer_get_current (b0);
            l2_efp_filter_trace_t *t = 
               vlib_add_trace (vm, node, b0, sizeof (*t));
            t->sw_if_index = sw_if_index0;
            clib_memcpy(t->src, h0->src_address, 6);
            clib_memcpy(t->dst, h0->dst_address, 6);
            clib_memcpy(t->raw, &h0->type, sizeof(t->raw));
          }

          /* verify speculative enqueue, maybe switch current next frame */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, next0);
        }

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

  return frame->n_vectors;
}


VLIB_REGISTER_NODE (l2_efp_filter_node,static) = {
  .function = l2_efp_filter_node_fn,
  .name = "l2-efp-filter",
  .vector_size = sizeof (u32),
  .format_trace = format_l2_efp_filter_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  
  .n_errors = ARRAY_LEN(l2_efp_filter_error_strings),
  .error_strings = l2_efp_filter_error_strings,

  .n_next_nodes = L2_EFP_FILTER_N_NEXT,

  /* edit / add dispositions here */
  .next_nodes = {
       [L2_EFP_FILTER_NEXT_DROP]  = "error-drop",
  },
};

clib_error_t *l2_efp_filter_init (vlib_main_t *vm)
{
  l2_efp_filter_main_t * mp = &l2_efp_filter_main;
 
  mp->vlib_main = vm;
  mp->vnet_main = vnet_get_main();

  // Initialize the feature next-node indexes
  feat_bitmap_init_next_nodes(vm,
                              l2_efp_filter_node.index,
                              L2OUTPUT_N_FEAT,
                              l2output_get_feat_names(),
                              mp->next_nodes.feat_next_node_index);

  // Initialize the output node mapping table
  l2output_init_output_node_vec(&mp->next_nodes.output_node_index_vec);

  return 0;
}

VLIB_INIT_FUNCTION (l2_efp_filter_init);


// Enable/disable the EFP Filter check on the subinterface
void l2_efp_filter_configure (vnet_main_t * vnet_main,
                              u32           sw_if_index,
                              u32           enable)
{
  // set the interface flag
  l2output_intf_bitmap_enable(sw_if_index, L2OUTPUT_FEAT_EFP_FILTER, enable);
}


// set subinterface egress efp filter enable/disable
// The CLI format is:
//    set interface l2 efp-filter <interface> [disable]]
static clib_error_t *
int_l2_efp_filter (vlib_main_t * vm,
                   unformat_input_t * input,
                   vlib_cli_command_t * cmd)
{
  vnet_main_t * vnm = vnet_get_main();
  clib_error_t * error = 0;
  u32 sw_if_index;
  u32 enable;

  if (! unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
    {
      error = clib_error_return (0, "unknown interface `%U'",
                                 format_unformat_error, input);
      goto done;
    }

  enable = 1;
  if (unformat (input, "disable")) {
    enable = 0;
  }

  // enable/disable the feature
  l2_efp_filter_configure (vnm, sw_if_index, enable);

 done:
  return error;
}


VLIB_CLI_COMMAND (int_l2_efp_filter_cli, static) = {
  .path = "set interface l2 efp-filter",
  .short_help = "set interface l2 efp-filter <interface> [disable]",
  .function = int_l2_efp_filter,
};