nat44_classify.c

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/*
 * Copyright (c) 2018 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.
 */
/**
 * @file
 * @brief Classify for one armed NAT44 (in+out interface)
 */

#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/fib/ip4_fib.h>
#include <nat/nat.h>
#include <nat/nat_reass.h>
#include <nat/nat_inlines.h>

vlib_node_registration_t nat44_classify_node;
vlib_node_registration_t nat44_ed_classify_node;
vlib_node_registration_t nat44_det_classify_node;
vlib_node_registration_t nat44_handoff_classify_node;

#define foreach_nat44_classify_error                      \
_(MAX_REASS, "Maximum reassemblies exceeded")             \
_(MAX_FRAG, "Maximum fragments per reassembly exceeded")

typedef enum
{
#define _(sym,str) NAT44_CLASSIFY_ERROR_##sym,
  foreach_nat44_classify_error
#undef _
    NAT44_CLASSIFY_N_ERROR,
} nat44_classify_error_t;

static char *nat44_classify_error_strings[] = {
#define _(sym,string) string,
  foreach_nat44_classify_error
#undef _
};

typedef enum
{
  NAT44_CLASSIFY_NEXT_IN2OUT,
  NAT44_CLASSIFY_NEXT_OUT2IN,
  NAT44_CLASSIFY_NEXT_DROP,
  NAT44_CLASSIFY_N_NEXT,
} nat44_classify_next_t;

typedef struct
{
  u8 next_in2out;
  u8 cached;
} nat44_classify_trace_t;

static u8 *
format_nat44_classify_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 *);
  nat44_classify_trace_t *t = va_arg (*args, nat44_classify_trace_t *);
  char *next;

  if (t->cached)
    s = format (s, "nat44-classify: fragment cached");
  else
    {
      next = t->next_in2out ? "nat44-in2out" : "nat44-out2in";
      s = format (s, "nat44-classify: next %s", next);
    }

  return s;
}

static inline uword
nat44_classify_node_fn_inline (vlib_main_t * vm,
                               vlib_node_runtime_t * node,
                               vlib_frame_t * frame, int is_ed)
{
  u32 n_left_from, *from, *to_next;
  nat44_classify_next_t next_index;
  snat_main_t *sm = &snat_main;
  snat_static_mapping_t *m;
  u32 thread_index = vm->thread_index;
  snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
  u32 *fragments_to_drop = 0;
  u32 *fragments_to_loopback = 0;

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

  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 > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *b0;
          u32 next0 = NAT44_CLASSIFY_NEXT_IN2OUT, sw_if_index0, rx_fib_index0;
          ip4_header_t *ip0;
          snat_address_t *ap;
          snat_session_key_t m_key0;
          clib_bihash_kv_8_8_t kv0, value0;
          clib_bihash_kv_16_8_t ed_kv0, ed_value0;
          udp_header_t *udp0;
          nat_reass_ip4_t *reass0;
          u8 cached0 = 0;

          /* 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);
          ip0 = vlib_buffer_get_current (b0);
          udp0 = ip4_next_header (ip0);

          if (is_ed && ip0->protocol != IP_PROTOCOL_ICMP)
            {
              if (!ip4_is_fragment (ip0) || ip4_is_first_fragment (ip0))
                {
                  /* process leading fragment/whole packet (with L4 header) */
                  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
                  rx_fib_index0 =
                    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
                                                         sw_if_index0);
                  make_ed_kv (&ed_kv0, &ip0->src_address, &ip0->dst_address,
                              ip0->protocol, rx_fib_index0, udp0->src_port,
                              udp0->dst_port);
                  if (ip4_is_fragment (ip0))
                    {
                      reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
                                                             ip0->dst_address,
                                                             ip0->fragment_id,
                                                             ip0->protocol,
                                                             1,
                                                             &fragments_to_drop);
                      if (PREDICT_FALSE (!reass0))
                        {
                          next0 = NAT44_CLASSIFY_NEXT_DROP;
                          b0->error =
                            node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
                          nat_log_notice ("maximum reassemblies exceeded");
                          goto enqueue0;
                        }
                      if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &ed_kv0,
                                                    &ed_value0))
                        {
                          /* session exists so classify as IN2OUT,
                           * save this information for future fragments and set
                           * past fragments to be looped over and reprocessed */
                          reass0->sess_index = ed_value0.value;
                          reass0->classify_next =
                            NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT;
                          nat_ip4_reass_get_frags (reass0,
                                                   &fragments_to_loopback);
                          goto enqueue0;
                        }
                      else
                        {
                          /* session doesn't exist so continue in the code,
                           * save this information for future fragments and set
                           * past fragments to be looped over and reprocessed */
                          reass0->flags |=
                            NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE;
                          nat_ip4_reass_get_frags (reass0,
                                                   &fragments_to_loopback);
                        }
                    }
                  else
                    {
                      /* process whole packet */
                      if (!clib_bihash_search_16_8 (&tsm->in2out_ed, &ed_kv0,
                                                    &ed_value0))
                        goto enqueue0;
                      /* session doesn't exist so continue in code */
                    }
                }
              else
                {
                  /* process non-first fragment */
                  reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
                                                         ip0->dst_address,
                                                         ip0->fragment_id,
                                                         ip0->protocol,
                                                         1,
                                                         &fragments_to_drop);
                  if (PREDICT_FALSE (!reass0))
                    {
                      next0 = NAT44_CLASSIFY_NEXT_DROP;
                      b0->error =
                        node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
                      nat_log_notice ("maximum reassemblies exceeded");
                      goto enqueue0;
                    }
                  /* check if first fragment has arrived */
                  if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NONE &&
                      !(reass0->flags & NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE))
                    {
                      /* first fragment still hasn't arrived, cache this fragment */
                      if (nat_ip4_reass_add_fragment (reass0, bi0,
                                                      &fragments_to_drop))
                        {
                          b0->error =
                            node->errors[NAT44_CLASSIFY_ERROR_MAX_FRAG];
                          nat_log_notice
                            ("maximum fragments per reassembly exceeded");
                          next0 = NAT44_CLASSIFY_NEXT_DROP;
                          goto enqueue0;
                        }
                      cached0 = 1;
                      goto enqueue0;
                    }
                  if (reass0->classify_next ==
                      NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT)
                    goto enqueue0;
                  /* flag NAT_REASS_FLAG_CLASSIFY_ED_CONTINUE is set
                   * so keep the default next0 and continue in code to
                   * potentially find other classification for this packet */
                }
            }

          /* *INDENT-OFF* */
          vec_foreach (ap, sm->addresses)
            {
              if (ip0->dst_address.as_u32 == ap->addr.as_u32)
                {
                  next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
                  goto enqueue0;
                }
            }
          /* *INDENT-ON* */

          if (PREDICT_FALSE (pool_elts (sm->static_mappings)))
            {
              m_key0.addr = ip0->dst_address;
              m_key0.port = 0;
              m_key0.protocol = 0;
              m_key0.fib_index = 0;
              kv0.key = m_key0.as_u64;
              /* try to classify the fragment based on IP header alone */
              if (!clib_bihash_search_8_8 (&sm->static_mapping_by_external,
                                           &kv0, &value0))
                {
                  m = pool_elt_at_index (sm->static_mappings, value0.value);
                  if (m->local_addr.as_u32 != m->external_addr.as_u32)
                    next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
                  goto enqueue0;
                }
              if (!ip4_is_fragment (ip0) || ip4_is_first_fragment (ip0))
                {
                  /* process leading fragment/whole packet (with L4 header) */
                  m_key0.port = clib_net_to_host_u16 (udp0->dst_port);
                  m_key0.protocol = ip_proto_to_snat_proto (ip0->protocol);
                  kv0.key = m_key0.as_u64;
                  if (!clib_bihash_search_8_8
                      (&sm->static_mapping_by_external, &kv0, &value0))
                    {
                      m =
                        pool_elt_at_index (sm->static_mappings, value0.value);
                      if (m->local_addr.as_u32 != m->external_addr.as_u32)
                        next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
                    }
                  if (ip4_is_fragment (ip0))
                    {
                      reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
                                                             ip0->dst_address,
                                                             ip0->fragment_id,
                                                             ip0->protocol,
                                                             1,
                                                             &fragments_to_drop);
                      if (PREDICT_FALSE (!reass0))
                        {
                          next0 = NAT44_CLASSIFY_NEXT_DROP;
                          b0->error =
                            node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
                          nat_log_notice ("maximum reassemblies exceeded");
                          goto enqueue0;
                        }
                      /* save classification for future fragments and set past
                       * fragments to be looped over and reprocessed */
                      if (next0 == NAT44_CLASSIFY_NEXT_OUT2IN)
                        reass0->classify_next =
                          NAT_REASS_IP4_CLASSIFY_NEXT_OUT2IN;
                      else
                        reass0->classify_next =
                          NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT;
                      nat_ip4_reass_get_frags (reass0,
                                               &fragments_to_loopback);
                    }
                }
              else
                {
                  /* process non-first fragment */
                  reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
                                                         ip0->dst_address,
                                                         ip0->fragment_id,
                                                         ip0->protocol,
                                                         1,
                                                         &fragments_to_drop);
                  if (PREDICT_FALSE (!reass0))
                    {
                      next0 = NAT44_CLASSIFY_NEXT_DROP;
                      b0->error =
                        node->errors[NAT44_CLASSIFY_ERROR_MAX_REASS];
                      nat_log_notice ("maximum reassemblies exceeded");
                      goto enqueue0;
                    }
                  if (reass0->classify_next == NAT_REASS_IP4_CLASSIFY_NONE)
                    /* first fragment still hasn't arrived */
                    {
                      if (nat_ip4_reass_add_fragment (reass0, bi0,
                                                      &fragments_to_drop))
                        {
                          b0->error =
                            node->errors[NAT44_CLASSIFY_ERROR_MAX_FRAG];
                          nat_log_notice
                            ("maximum fragments per reassembly exceeded");
                          next0 = NAT44_CLASSIFY_NEXT_DROP;
                          goto enqueue0;
                        }
                      cached0 = 1;
                      goto enqueue0;
                    }
                  else if (reass0->classify_next ==
                           NAT_REASS_IP4_CLASSIFY_NEXT_OUT2IN)
                    next0 = NAT44_CLASSIFY_NEXT_OUT2IN;
                  else if (reass0->classify_next ==
                           NAT_REASS_IP4_CLASSIFY_NEXT_IN2OUT)
                    next0 = NAT44_CLASSIFY_NEXT_IN2OUT;
                }
            }

        enqueue0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              nat44_classify_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->cached = cached0;
              if (!cached0)
                t->next_in2out = next0 == NAT44_CLASSIFY_NEXT_IN2OUT ? 1 : 0;
            }

          if (cached0)
            {
              n_left_to_next++;
              to_next--;
            }
          else
            /* 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);

          if (n_left_from == 0 && vec_len (fragments_to_loopback))
            {
              from = vlib_frame_vector_args (frame);
              u32 len = vec_len (fragments_to_loopback);
              if (len <= VLIB_FRAME_SIZE)
                {
                  clib_memcpy (from, fragments_to_loopback,
                               sizeof (u32) * len);
                  n_left_from = len;
                  vec_reset_length (fragments_to_loopback);
                }
              else
                {
                  clib_memcpy (from,
                               fragments_to_loopback + (len -
                                                        VLIB_FRAME_SIZE),
                               sizeof (u32) * VLIB_FRAME_SIZE);
                  n_left_from = VLIB_FRAME_SIZE;
                  _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
                }
            }
        }

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

  nat_send_all_to_node (vm, fragments_to_drop, node, 0,
                        NAT44_CLASSIFY_NEXT_DROP);

  vec_free (fragments_to_drop);

  return frame->n_vectors;
}

static uword
nat44_classify_node_fn (vlib_main_t * vm,
                        vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  return nat44_classify_node_fn_inline (vm, node, frame, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_classify_node) = {
  .function = nat44_classify_node_fn,
  .name = "nat44-classify",
  .vector_size = sizeof (u32),
  .format_trace = format_nat44_classify_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(nat44_classify_error_strings),
  .error_strings = nat44_classify_error_strings,
  .n_next_nodes = NAT44_CLASSIFY_N_NEXT,
  .next_nodes = {
    [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-in2out",
    [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-out2in",
    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (nat44_classify_node, nat44_classify_node_fn);
static uword
nat44_ed_classify_node_fn (vlib_main_t * vm,
                           vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  return nat44_classify_node_fn_inline (vm, node, frame, 1);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_ed_classify_node) = {
  .function = nat44_ed_classify_node_fn,
  .name = "nat44-ed-classify",
  .vector_size = sizeof (u32),
  .format_trace = format_nat44_classify_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_next_nodes = NAT44_CLASSIFY_N_NEXT,
  .next_nodes = {
    [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-ed-in2out",
    [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-ed-out2in",
    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (nat44_ed_classify_node,
                              nat44_ed_classify_node_fn);

static uword
nat44_det_classify_node_fn (vlib_main_t * vm,
                            vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  return nat44_classify_node_fn_inline (vm, node, frame, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_det_classify_node) = {
  .function = nat44_det_classify_node_fn,
  .name = "nat44-det-classify",
  .vector_size = sizeof (u32),
  .format_trace = format_nat44_classify_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_next_nodes = NAT44_CLASSIFY_N_NEXT,
  .next_nodes = {
    [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-det-in2out",
    [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-det-out2in",
    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (nat44_det_classify_node,
                              nat44_det_classify_node_fn);

static uword
nat44_handoff_classify_node_fn (vlib_main_t * vm,
                                vlib_node_runtime_t * node,
                                vlib_frame_t * frame)
{
  return nat44_classify_node_fn_inline (vm, node, frame, 0);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (nat44_handoff_classify_node) = {
  .function = nat44_handoff_classify_node_fn,
  .name = "nat44-handoff-classify",
  .vector_size = sizeof (u32),
  .format_trace = format_nat44_classify_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_next_nodes = NAT44_CLASSIFY_N_NEXT,
  .next_nodes = {
    [NAT44_CLASSIFY_NEXT_IN2OUT] = "nat44-in2out-worker-handoff",
    [NAT44_CLASSIFY_NEXT_OUT2IN] = "nat44-out2in-worker-handoff",
    [NAT44_CLASSIFY_NEXT_DROP] = "error-drop",
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (nat44_handoff_classify_node,
                              nat44_handoff_classify_node_fn);
/* *INDENT-ON* */

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