l2_efp_filter.c

Go to the documentation of this file.

/*
 * 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>

/**
 * @file
 * @brief EFP-filter - Ethernet Flow Point Filter.
 *
 * It is possible to transmit a packet out a subinterface with VLAN tags
 * that are not compatible with that subinterface. In other words, if that
 * packet arrived on the output port, it would not be classified as coming
 * from the output subinterface. This can happen in various ways: through
 * misconfiguration, by putting subinterfaces with different VLAN encaps in
 * the same bridge-domain, etc. The EFP Filter Check detects such packets
 * and drops them. It consists of two checks, one that verifies the packet
 * prior to output VLAN tag rewrite and one that verifies the packet after
 * VLAN tag rewrite.
 *
 */
typedef struct
{
  /* Next nodes for L2 output features */
  u32 l2_out_feat_next[32];

  /* 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;

  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;
          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);
             * 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;

          /* Determine next node */
          next0 = vnet_l2_feature_next (b0, msm->l2_out_feat_next,
                                        L2OUTPUT_FEAT_EFP_FILTER);
          next1 = vnet_l2_feature_next (b1, msm->l2_out_feat_next,
                                        L2OUTPUT_FEAT_EFP_FILTER);

          /* 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,
                                          match_flags0,
                                          main_intf0,
                                          vlan_intf0,
                                          qinq_intf0,
                                          &subint_sw_if_index0,
                                          &error0, &is_l20);

          matched1 = eth_identify_subint (hi1,
                                          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_fast (t->src, h0->src_address, 6);
                  clib_memcpy_fast (t->dst, h0->dst_address, 6);
                  clib_memcpy_fast (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_fast (t->src, h1->src_address, 6);
                  clib_memcpy_fast (t->dst, h1->dst_address, 6);
                  clib_memcpy_fast (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;
          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;

          /* Determine next node */
          next0 = vnet_l2_feature_next (b0, msm->l2_out_feat_next,
                                        L2OUTPUT_FEAT_EFP_FILTER);

          /* 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,
                                          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_fast (t->src, h0->src_address, 6);
              clib_memcpy_fast (t->dst, h0->dst_address, 6);
              clib_memcpy_fast (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;
}


/* *INDENT-OFF* */
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",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (l2_efp_filter_node, l2_efp_filter_node_fn)
     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->l2_out_feat_next);

  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, u8 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;
}


/*?
 * 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. This command enables or disables the EFP filtering
 * for a given sub-interface.
 *
 * @cliexpar
 * Example of how to enable a Layer 2 efp-filter on a sub-interface:
 * @cliexcmd{set interface l2 efp-filter GigabitEthernet0/8/0.200}
 * Example of how to disable a Layer 2 efp-filter on a sub-interface:
 * @cliexcmd{set interface l2 efp-filter GigabitEthernet0/8/0.200 disable}
?*/
/* *INDENT-OFF* */
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,
};
/* *INDENT-ON* */


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