ah_encrypt.c

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/*
 * ah_encrypt.c : IPSec AH encrypt node
 *
 * 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.
 */

#include <vnet/vnet.h>
#include <vnet/api_errno.h>
#include <vnet/ip/ip.h>

#include <vnet/ipsec/ipsec.h>
#include <vnet/ipsec/esp.h>
#include <vnet/ipsec/ah.h>

#define foreach_ah_encrypt_next                   \
_(DROP, "error-drop")                              \
_(IP4_LOOKUP, "ip4-lookup")                        \
_(IP6_LOOKUP, "ip6-lookup")                        \
_(INTERFACE_OUTPUT, "interface-output")

#define _(v, s) AH_ENCRYPT_NEXT_##v,
typedef enum
{
  foreach_ah_encrypt_next
#undef _
    AH_ENCRYPT_N_NEXT,
} ah_encrypt_next_t;

#define foreach_ah_encrypt_error                   \
 _(RX_PKTS, "AH pkts received")                    \
 _(SEQ_CYCLED, "sequence number cycled")


typedef enum
{
#define _(sym,str) AH_ENCRYPT_ERROR_##sym,
  foreach_ah_encrypt_error
#undef _
    AH_ENCRYPT_N_ERROR,
} ah_encrypt_error_t;

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

vlib_node_registration_t ah_encrypt_node;

typedef struct
{
  u32 spi;
  u32 seq;
  ipsec_integ_alg_t integ_alg;
} ah_encrypt_trace_t;

/* packet trace format function */
static u8 *
format_ah_encrypt_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 *);
  ah_encrypt_trace_t *t = va_arg (*args, ah_encrypt_trace_t *);

  s = format (s, "ah: spi %u seq %u integrity %U",
              t->spi, t->seq, format_ipsec_integ_alg, t->integ_alg);
  return s;
}

static uword
ah_encrypt_node_fn (vlib_main_t * vm,
                    vlib_node_runtime_t * node, vlib_frame_t * from_frame)
{
  u32 n_left_from, *from, *to_next = 0, next_index;
  int icv_size = 0;
  from = vlib_frame_vector_args (from_frame);
  n_left_from = from_frame->n_vectors;
  ipsec_main_t *im = &ipsec_main;
  ipsec_proto_main_t *em = &ipsec_proto_main;
  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 i_bi0, next0;
          vlib_buffer_t *i_b0 = 0;
          u32 sa_index0;
          ipsec_sa_t *sa0;
          ip4_and_ah_header_t *ih0, *oh0 = 0;
          ip6_and_ah_header_t *ih6_0, *oh6_0 = 0;
          u8 is_ipv6;
          u8 ip_hdr_size;
          u8 next_hdr_type;
          u8 transport_mode = 0;
          u8 tos = 0;
          u8 ttl = 0;
          u8 hop_limit = 0;
          u32 ip_version_traffic_class_and_flow_label = 0;

          i_bi0 = from[0];
          from += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;
          next0 = AH_ENCRYPT_NEXT_DROP;

          i_b0 = vlib_get_buffer (vm, i_bi0);
          to_next[0] = i_bi0;
          to_next += 1;
          sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
          sa0 = pool_elt_at_index (im->sad, sa_index0);

          if (PREDICT_FALSE (esp_seq_advance (sa0)))
            {
              clib_warning ("sequence number counter has cycled SPI %u",
                            sa0->spi);
              vlib_node_increment_counter (vm, ah_encrypt_node.index,
                                           AH_ENCRYPT_ERROR_SEQ_CYCLED, 1);
              //TODO need to confirm if below is needed
              to_next[0] = i_bi0;
              to_next += 1;
              goto trace;
            }


          sa0->total_data_size += i_b0->current_length;

          ssize_t adv;
          ih0 = vlib_buffer_get_current (i_b0);
          ttl = ih0->ip4.ttl;
          tos = ih0->ip4.tos;

          is_ipv6 = (ih0->ip4.ip_version_and_header_length & 0xF0) == 0x60;
          /* is ipv6 */
          if (PREDICT_TRUE (sa0->is_tunnel))
            {
              if (PREDICT_TRUE (!is_ipv6))
                adv = -sizeof (ip4_and_ah_header_t);
              else
                adv = -sizeof (ip6_and_ah_header_t);
            }
          else
            {
              adv = -sizeof (ah_header_t);
            }

          icv_size =
            em->ipsec_proto_main_integ_algs[sa0->integ_alg].trunc_size;
          const u8 padding_len = ah_calc_icv_padding_len (icv_size, is_ipv6);
          adv -= padding_len;
          /*transport mode save the eth header before it is overwritten */
          if (PREDICT_FALSE (!sa0->is_tunnel))
            {
              ethernet_header_t *ieh0 = (ethernet_header_t *)
                ((u8 *) vlib_buffer_get_current (i_b0) -
                 sizeof (ethernet_header_t));
              ethernet_header_t *oeh0 =
                (ethernet_header_t *) ((u8 *) ieh0 + (adv - icv_size));
              clib_memcpy (oeh0, ieh0, sizeof (ethernet_header_t));
            }

          vlib_buffer_advance (i_b0, adv - icv_size);

          if (PREDICT_FALSE (is_ipv6))
            {                   /* is ipv6 */
              ih6_0 = (ip6_and_ah_header_t *) ih0;
              ip_hdr_size = sizeof (ip6_header_t);
              oh6_0 = vlib_buffer_get_current (i_b0);

              hop_limit = ih6_0->ip6.hop_limit;
              ip_version_traffic_class_and_flow_label =
                ih6_0->ip6.ip_version_traffic_class_and_flow_label;
              if (PREDICT_TRUE (sa0->is_tunnel))
                {
                  next_hdr_type = IP_PROTOCOL_IPV6;
                }
              else
                {
                  next_hdr_type = ih6_0->ip6.protocol;
                  memmove (oh6_0, ih6_0, sizeof (ip6_header_t));
                }

              oh6_0->ip6.protocol = IP_PROTOCOL_IPSEC_AH;
              oh6_0->ip6.hop_limit = 0;
              oh6_0->ip6.ip_version_traffic_class_and_flow_label = 0x60;
              oh6_0->ah.reserved = 0;
              oh6_0->ah.nexthdr = next_hdr_type;
              oh6_0->ah.spi = clib_net_to_host_u32 (sa0->spi);
              oh6_0->ah.seq_no = clib_net_to_host_u32 (sa0->seq);
              oh6_0->ip6.payload_length =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, i_b0) -
                                      sizeof (ip6_header_t));
              oh6_0->ah.hdrlen =
                (sizeof (ah_header_t) + icv_size + padding_len) / 4 - 2;
            }
          else
            {
              ip_hdr_size = sizeof (ip4_header_t);
              oh0 = vlib_buffer_get_current (i_b0);
              memset (oh0, 0, sizeof (ip4_and_ah_header_t));

              if (PREDICT_TRUE (sa0->is_tunnel))
                {
                  next_hdr_type = IP_PROTOCOL_IP_IN_IP;
                }
              else
                {
                  next_hdr_type = ih0->ip4.protocol;
                  memmove (oh0, ih0, sizeof (ip4_header_t));
                }

              oh0->ip4.length =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, i_b0));
              oh0->ip4.ip_version_and_header_length = 0x45;
              oh0->ip4.fragment_id = 0;
              oh0->ip4.flags_and_fragment_offset = 0;
              oh0->ip4.ttl = 0;
              oh0->ip4.tos = 0;
              oh0->ip4.protocol = IP_PROTOCOL_IPSEC_AH;
              oh0->ah.spi = clib_net_to_host_u32 (sa0->spi);
              oh0->ah.seq_no = clib_net_to_host_u32 (sa0->seq);
              oh0->ip4.checksum = 0;
              oh0->ah.nexthdr = next_hdr_type;
              oh0->ah.hdrlen =
                (sizeof (ah_header_t) + icv_size + padding_len) / 4 - 2;
            }


          if (PREDICT_TRUE
              (!is_ipv6 && sa0->is_tunnel && !sa0->is_tunnel_ip6))
            {
              oh0->ip4.src_address.as_u32 = sa0->tunnel_src_addr.ip4.as_u32;
              oh0->ip4.dst_address.as_u32 = sa0->tunnel_dst_addr.ip4.as_u32;

              next0 = AH_ENCRYPT_NEXT_IP4_LOOKUP;
              vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
            }
          else if (is_ipv6 && sa0->is_tunnel && sa0->is_tunnel_ip6)
            {
              oh6_0->ip6.src_address.as_u64[0] =
                sa0->tunnel_src_addr.ip6.as_u64[0];
              oh6_0->ip6.src_address.as_u64[1] =
                sa0->tunnel_src_addr.ip6.as_u64[1];
              oh6_0->ip6.dst_address.as_u64[0] =
                sa0->tunnel_dst_addr.ip6.as_u64[0];
              oh6_0->ip6.dst_address.as_u64[1] =
                sa0->tunnel_dst_addr.ip6.as_u64[1];

              next0 = AH_ENCRYPT_NEXT_IP6_LOOKUP;
              vnet_buffer (i_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
            }
          else
            {
              transport_mode = 1;
              next0 = AH_ENCRYPT_NEXT_INTERFACE_OUTPUT;
            }

          u8 sig[64];
          memset (sig, 0, sizeof (sig));
          u8 *digest =
            vlib_buffer_get_current (i_b0) + ip_hdr_size +
            sizeof (ah_header_t);
          memset (digest, 0, icv_size);

          unsigned size = hmac_calc (sa0->integ_alg, sa0->integ_key,
                                     sa0->integ_key_len,
                                     vlib_buffer_get_current (i_b0),
                                     i_b0->current_length, sig, sa0->use_esn,
                                     sa0->seq_hi);

          memcpy (digest, sig, size);
          if (PREDICT_FALSE (is_ipv6))
            {
              oh6_0->ip6.hop_limit = hop_limit;
              oh6_0->ip6.ip_version_traffic_class_and_flow_label =
                ip_version_traffic_class_and_flow_label;
            }
          else
            {
              oh0->ip4.ttl = ttl;
              oh0->ip4.tos = tos;
              oh0->ip4.checksum = ip4_header_checksum (&oh0->ip4);
            }

          if (transport_mode)
            vlib_buffer_advance (i_b0, -sizeof (ethernet_header_t));

        trace:
          if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              i_b0->flags |= VLIB_BUFFER_IS_TRACED;
              ah_encrypt_trace_t *tr =
                vlib_add_trace (vm, node, i_b0, sizeof (*tr));
              tr->spi = sa0->spi;
              tr->seq = sa0->seq - 1;
              tr->integ_alg = sa0->integ_alg;
            }

          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next, i_bi0,
                                           next0);
        }
      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }
  vlib_node_increment_counter (vm, ah_encrypt_node.index,
                               AH_ENCRYPT_ERROR_RX_PKTS,
                               from_frame->n_vectors);

  return from_frame->n_vectors;
}


/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ah_encrypt_node) = {
  .function = ah_encrypt_node_fn,
  .name = "ah-encrypt",
  .vector_size = sizeof (u32),
  .format_trace = format_ah_encrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = ARRAY_LEN(ah_encrypt_error_strings),
  .error_strings = ah_encrypt_error_strings,

  .n_next_nodes = AH_ENCRYPT_N_NEXT,
  .next_nodes = {
#define _(s,n) [AH_ENCRYPT_NEXT_##s] = n,
    foreach_ah_encrypt_next
#undef _
  },
};
/* *INDENT-ON* */

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