node.c

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/*
 *------------------------------------------------------------------
 * af_packet.c - linux kernel packet interface
 *
 * Copyright (c) 2016 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 <linux/if_packet.h>

#include <vlib/vlib.h>
#include <vlib/unix/unix.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/devices/devices.h>
#include <vnet/feature/feature.h>
#include <vnet/ethernet/packet.h>

#include <vnet/devices/af_packet/af_packet.h>

#define foreach_af_packet_input_error \
  _(PARTIAL_PKT, "partial packet")

typedef enum
{
#define _(f,s) AF_PACKET_INPUT_ERROR_##f,
  foreach_af_packet_input_error
#undef _
    AF_PACKET_INPUT_N_ERROR,
} af_packet_input_error_t;

static char *af_packet_input_error_strings[] = {
#define _(n,s) s,
  foreach_af_packet_input_error
#undef _
};

typedef struct
{
  u32 next_index;
  u32 hw_if_index;
  int block;
  struct tpacket2_hdr tph;
} af_packet_input_trace_t;

static u8 *
format_af_packet_input_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 *);
  af_packet_input_trace_t *t = va_arg (*args, af_packet_input_trace_t *);
  u32 indent = format_get_indent (s);

  s = format (s, "af_packet: hw_if_index %d next-index %d",
              t->hw_if_index, t->next_index);

  s =
    format (s,
            "\n%Utpacket2_hdr:\n%Ustatus 0x%x len %u snaplen %u mac %u net %u"
            "\n%Usec 0x%x nsec 0x%x vlan %U"
#ifdef TP_STATUS_VLAN_TPID_VALID
            " vlan_tpid %u"
#endif
            ,
            format_white_space, indent + 2,
            format_white_space, indent + 4,
            t->tph.tp_status,
            t->tph.tp_len,
            t->tph.tp_snaplen,
            t->tph.tp_mac,
            t->tph.tp_net,
            format_white_space, indent + 4,
            t->tph.tp_sec,
            t->tph.tp_nsec, format_ethernet_vlan_tci, t->tph.tp_vlan_tci
#ifdef TP_STATUS_VLAN_TPID_VALID
            , t->tph.tp_vlan_tpid
#endif
    );
  return s;
}

always_inline void
buffer_add_to_chain (vlib_main_t * vm, u32 bi, u32 first_bi, u32 prev_bi)
{
  vlib_buffer_t *b = vlib_get_buffer (vm, bi);
  vlib_buffer_t *first_b = vlib_get_buffer (vm, first_bi);
  vlib_buffer_t *prev_b = vlib_get_buffer (vm, prev_bi);

  /* update first buffer */
  first_b->total_length_not_including_first_buffer += b->current_length;

  /* update previous buffer */
  prev_b->next_buffer = bi;
  prev_b->flags |= VLIB_BUFFER_NEXT_PRESENT;

  /* update current buffer */
  b->next_buffer = 0;
}

static_always_inline void
mark_tcp_udp_cksum_calc (vlib_buffer_t * b)
{
  ethernet_header_t *eth = vlib_buffer_get_current (b);
  if (clib_net_to_host_u16 (eth->type) == ETHERNET_TYPE_IP4)
    {
      ip4_header_t *ip4 =
        (vlib_buffer_get_current (b) + sizeof (ethernet_header_t));
      b->flags |= VNET_BUFFER_F_IS_IP4;
      if (ip4->protocol == IP_PROTOCOL_TCP)
        {
          b->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
          ((tcp_header_t
            *) (vlib_buffer_get_current (b) +
                sizeof (ethernet_header_t) +
                ip4_header_bytes (ip4)))->checksum = 0;
        }
      else if (ip4->protocol == IP_PROTOCOL_UDP)
        {
          b->flags |= VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
          ((udp_header_t
            *) (vlib_buffer_get_current (b) +
                sizeof (ethernet_header_t) +
                ip4_header_bytes (ip4)))->checksum = 0;
        }
      vnet_buffer (b)->l3_hdr_offset = sizeof (ethernet_header_t);
      vnet_buffer (b)->l4_hdr_offset =
        sizeof (ethernet_header_t) + ip4_header_bytes (ip4);
    }
  else if (clib_net_to_host_u16 (eth->type) == ETHERNET_TYPE_IP6)
    {
      ip6_header_t *ip6 =
        (vlib_buffer_get_current (b) + sizeof (ethernet_header_t));
      b->flags |= VNET_BUFFER_F_IS_IP6;
      u16 ip6_hdr_len = sizeof (ip6_header_t);
      if (ip6_ext_hdr (ip6->protocol))
        {
          ip6_ext_header_t *p = (void *) (ip6 + 1);
          ip6_hdr_len += ip6_ext_header_len (p);
          while (ip6_ext_hdr (p->next_hdr))
            {
              ip6_hdr_len += ip6_ext_header_len (p);
              p = ip6_ext_next_header (p);
            }
        }
      if (ip6->protocol == IP_PROTOCOL_TCP)
        {
          b->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
          ((tcp_header_t
            *) (vlib_buffer_get_current (b) +
                sizeof (ethernet_header_t) + ip6_hdr_len))->checksum = 0;
        }
      else if (ip6->protocol == IP_PROTOCOL_UDP)
        {
          b->flags |= VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
          ((udp_header_t
            *) (vlib_buffer_get_current (b) +
                sizeof (ethernet_header_t) + ip6_hdr_len))->checksum = 0;
        }
      vnet_buffer (b)->l3_hdr_offset = sizeof (ethernet_header_t);
      vnet_buffer (b)->l4_hdr_offset =
        sizeof (ethernet_header_t) + ip6_hdr_len;
    }
}

always_inline uword
af_packet_device_input_fn (vlib_main_t * vm, vlib_node_runtime_t * node,
                           vlib_frame_t * frame, af_packet_if_t * apif)
{
  af_packet_main_t *apm = &af_packet_main;
  struct tpacket2_hdr *tph;
  u32 next_index = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
  u32 block = 0;
  u32 rx_frame;
  u32 n_free_bufs;
  u32 n_rx_packets = 0;
  u32 n_rx_bytes = 0;
  u32 *to_next = 0;
  u32 block_size = apif->rx_req->tp_block_size;
  u32 frame_size = apif->rx_req->tp_frame_size;
  u32 frame_num = apif->rx_req->tp_frame_nr;
  u8 *block_start = apif->rx_ring + block * block_size;
  uword n_trace = vlib_get_trace_count (vm, node);
  u32 thread_index = vm->thread_index;
  u32 n_buffer_bytes = vlib_buffer_get_default_data_size (vm);
  u32 min_bufs = apif->rx_req->tp_frame_size / n_buffer_bytes;

  if (apif->per_interface_next_index != ~0)
    next_index = apif->per_interface_next_index;

  n_free_bufs = vec_len (apm->rx_buffers[thread_index]);
  if (PREDICT_FALSE (n_free_bufs < VLIB_FRAME_SIZE))
    {
      vec_validate (apm->rx_buffers[thread_index],
                    VLIB_FRAME_SIZE + n_free_bufs - 1);
      n_free_bufs +=
        vlib_buffer_alloc (vm, &apm->rx_buffers[thread_index][n_free_bufs],
                           VLIB_FRAME_SIZE);
      _vec_len (apm->rx_buffers[thread_index]) = n_free_bufs;
    }

  rx_frame = apif->next_rx_frame;
  tph = (struct tpacket2_hdr *) (block_start + rx_frame * frame_size);
  while ((tph->tp_status & TP_STATUS_USER) && (n_free_bufs > min_bufs))
    {
      vlib_buffer_t *b0 = 0, *first_b0 = 0;
      u32 next0 = next_index;

      u32 n_left_to_next;
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
      while ((tph->tp_status & TP_STATUS_USER) && (n_free_bufs > min_bufs) &&
             n_left_to_next)
        {
          u32 data_len = tph->tp_snaplen;
          u32 offset = 0;
          u32 bi0 = 0, first_bi0 = 0, prev_bi0;

          while (data_len)
            {
              /* grab free buffer */
              u32 last_empty_buffer =
                vec_len (apm->rx_buffers[thread_index]) - 1;
              prev_bi0 = bi0;
              bi0 = apm->rx_buffers[thread_index][last_empty_buffer];
              b0 = vlib_get_buffer (vm, bi0);
              _vec_len (apm->rx_buffers[thread_index]) = last_empty_buffer;
              n_free_bufs--;

              /* copy data */
              u32 bytes_to_copy =
                data_len > n_buffer_bytes ? n_buffer_bytes : data_len;
              u32 vlan_len = 0;
              u32 bytes_copied = 0;
              b0->current_data = 0;
              /* Kernel removes VLAN headers, so reconstruct VLAN */
              if (PREDICT_FALSE (tph->tp_status & TP_STATUS_VLAN_VALID))
                {
                  if (PREDICT_TRUE (offset == 0))
                    {
                      clib_memcpy_fast (vlib_buffer_get_current (b0),
                                        (u8 *) tph + tph->tp_mac,
                                        sizeof (ethernet_header_t));
                      ethernet_header_t *eth = vlib_buffer_get_current (b0);
                      ethernet_vlan_header_t *vlan =
                        (ethernet_vlan_header_t *) (eth + 1);
                      vlan->priority_cfi_and_id =
                        clib_host_to_net_u16 (tph->tp_vlan_tci);
                      vlan->type = eth->type;
                      eth->type = clib_host_to_net_u16 (ETHERNET_TYPE_VLAN);
                      vlan_len = sizeof (ethernet_vlan_header_t);
                      bytes_copied = sizeof (ethernet_header_t);
                    }
                }
              clib_memcpy_fast (((u8 *) vlib_buffer_get_current (b0)) +
                                bytes_copied + vlan_len,
                                (u8 *) tph + tph->tp_mac + offset +
                                bytes_copied, (bytes_to_copy - bytes_copied));

              /* fill buffer header */
              b0->current_length = bytes_to_copy + vlan_len;

              if (offset == 0)
                {
                  b0->total_length_not_including_first_buffer = 0;
                  b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
                  vnet_buffer (b0)->sw_if_index[VLIB_RX] = apif->sw_if_index;
                  vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
                  first_bi0 = bi0;
                  first_b0 = vlib_get_buffer (vm, first_bi0);
                  if (tph->tp_status & TP_STATUS_CSUMNOTREADY)
                    mark_tcp_udp_cksum_calc (first_b0);
                }
              else
                buffer_add_to_chain (vm, bi0, first_bi0, prev_bi0);

              offset += bytes_to_copy;
              data_len -= bytes_to_copy;
            }
          n_rx_packets++;
          n_rx_bytes += tph->tp_snaplen;
          to_next[0] = first_bi0;
          to_next += 1;
          n_left_to_next--;

          /* drop partial packets */
          if (PREDICT_FALSE (tph->tp_len != tph->tp_snaplen))
            {
              next0 = VNET_DEVICE_INPUT_NEXT_DROP;
              first_b0->error =
                node->errors[AF_PACKET_INPUT_ERROR_PARTIAL_PKT];
            }
          else
            {
              next0 = VNET_DEVICE_INPUT_NEXT_ETHERNET_INPUT;
              /* redirect if feature path enabled */
              vnet_feature_start_device_input_x1 (apif->sw_if_index, &next0,
                                                  first_b0);
            }

          /* trace */
          VLIB_BUFFER_TRACE_TRAJECTORY_INIT (first_b0);
          if (PREDICT_FALSE (n_trace > 0))
            {
              af_packet_input_trace_t *tr;
              vlib_trace_buffer (vm, node, next0, first_b0,     /* follow_chain */
                                 0);
              vlib_set_trace_count (vm, node, --n_trace);
              tr = vlib_add_trace (vm, node, first_b0, sizeof (*tr));
              tr->next_index = next0;
              tr->hw_if_index = apif->hw_if_index;
              clib_memcpy_fast (&tr->tph, tph, sizeof (struct tpacket2_hdr));
            }

          /* enque and take next packet */
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
                                           n_left_to_next, first_bi0, next0);

          /* next packet */
          tph->tp_status = TP_STATUS_KERNEL;
          rx_frame = (rx_frame + 1) % frame_num;
          tph = (struct tpacket2_hdr *) (block_start + rx_frame * frame_size);
        }

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

  apif->next_rx_frame = rx_frame;

  vlib_increment_combined_counter
    (vnet_get_main ()->interface_main.combined_sw_if_counters
     + VNET_INTERFACE_COUNTER_RX,
     vlib_get_thread_index (), apif->hw_if_index, n_rx_packets, n_rx_bytes);

  vnet_device_increment_rx_packets (thread_index, n_rx_packets);
  return n_rx_packets;
}

VLIB_NODE_FN (af_packet_input_node) (vlib_main_t * vm,
                                     vlib_node_runtime_t * node,
                                     vlib_frame_t * frame)
{
  u32 n_rx_packets = 0;
  af_packet_main_t *apm = &af_packet_main;
  vnet_device_input_runtime_t *rt = (void *) node->runtime_data;
  vnet_device_and_queue_t *dq;

  foreach_device_and_queue (dq, rt->devices_and_queues)
  {
    af_packet_if_t *apif;
    apif = vec_elt_at_index (apm->interfaces, dq->dev_instance);
    if (apif->is_admin_up)
      n_rx_packets += af_packet_device_input_fn (vm, node, frame, apif);
  }

  return n_rx_packets;
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (af_packet_input_node) = {
  .name = "af-packet-input",
  .sibling_of = "device-input",
  .format_trace = format_af_packet_input_trace,
  .type = VLIB_NODE_TYPE_INPUT,
  .state = VLIB_NODE_STATE_INTERRUPT,
  .n_errors = AF_PACKET_INPUT_N_ERROR,
  .error_strings = af_packet_input_error_strings,
};
/* *INDENT-ON* */


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