esp_decrypt.c

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/*
 * esp_decrypt.c : IPSec ESP decrypt 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/l2/l2_input.h>

#include <vnet/ipsec/ipsec.h>
#include <vnet/ipsec/esp.h>
#include <vnet/ipsec/ipsec_io.h>
#include <vnet/ipsec/ipsec_tun.h>

#include <vnet/gre/packet.h>

#define foreach_esp_decrypt_next                \
_(DROP, "error-drop")                           \
_(IP4_INPUT, "ip4-input-no-checksum")           \
_(IP6_INPUT, "ip6-input")                       \
_(L2_INPUT, "l2-input")                         \
_(HANDOFF, "handoff")

#define _(v, s) ESP_DECRYPT_NEXT_##v,
typedef enum
{
  foreach_esp_decrypt_next
#undef _
    ESP_DECRYPT_N_NEXT,
} esp_decrypt_next_t;

#define foreach_esp_decrypt_post_next                  \
_(DROP, "error-drop")                                  \
_(IP4_INPUT, "ip4-input-no-checksum")                  \
_(IP6_INPUT, "ip6-input")                              \
_(L2_INPUT, "l2-input")

#define _(v, s) ESP_DECRYPT_POST_NEXT_##v,
typedef enum
{
  foreach_esp_decrypt_post_next
#undef _
    ESP_DECRYPT_POST_N_NEXT,
} esp_decrypt_post_next_t;

#define foreach_esp_decrypt_error                               \
 _(RX_PKTS, "ESP pkts received")                                \
 _(RX_POST_PKTS, "ESP-POST pkts received")                      \
 _(DECRYPTION_FAILED, "ESP decryption failed")                  \
 _(INTEG_ERROR, "Integrity check failed")                       \
 _(CRYPTO_ENGINE_ERROR, "crypto engine error (packet dropped)") \
 _(REPLAY, "SA replayed packet")                                \
 _(RUNT, "undersized packet")                                   \
 _(NO_BUFFERS, "no buffers (packet dropped)")                   \
 _(OVERSIZED_HEADER, "buffer with oversized header (dropped)")  \
 _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)")      \
 _(TUN_NO_PROTO, "no tunnel protocol")                          \
 _(UNSUP_PAYLOAD, "unsupported payload")                        \


typedef enum
{
#define _(sym,str) ESP_DECRYPT_ERROR_##sym,
  foreach_esp_decrypt_error
#undef _
    ESP_DECRYPT_N_ERROR,
} esp_decrypt_error_t;

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

typedef struct
{
  u32 seq;
  u32 sa_seq;
  u32 sa_seq_hi;
  ipsec_crypto_alg_t crypto_alg;
  ipsec_integ_alg_t integ_alg;
} esp_decrypt_trace_t;

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

  s =
    format (s,
            "esp: crypto %U integrity %U pkt-seq %d sa-seq %u sa-seq-hi %u",
            format_ipsec_crypto_alg, t->crypto_alg, format_ipsec_integ_alg,
            t->integ_alg, t->seq, t->sa_seq, t->sa_seq_hi);
  return s;
}

#define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2)

static_always_inline void
esp_process_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
                 vnet_crypto_op_t * ops, vlib_buffer_t * b[], u16 * nexts,
                 int e)
{
  vnet_crypto_op_t *op = ops;
  u32 n_fail, n_ops = vec_len (ops);

  if (n_ops == 0)
    return;

  n_fail = n_ops - vnet_crypto_process_ops (vm, op, n_ops);

  while (n_fail)
    {
      ASSERT (op - ops < n_ops);
      if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
        {
          u32 err, bi = op->user_data;
          if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
            err = e;
          else
            err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
          b[bi]->error = node->errors[err];
          nexts[bi] = ESP_DECRYPT_NEXT_DROP;
          n_fail--;
        }
      op++;
    }
}

static_always_inline void
esp_process_chained_ops (vlib_main_t * vm, vlib_node_runtime_t * node,
                         vnet_crypto_op_t * ops, vlib_buffer_t * b[],
                         u16 * nexts, vnet_crypto_op_chunk_t * chunks, int e)
{

  vnet_crypto_op_t *op = ops;
  u32 n_fail, n_ops = vec_len (ops);

  if (n_ops == 0)
    return;

  n_fail = n_ops - vnet_crypto_process_chained_ops (vm, op, chunks, n_ops);

  while (n_fail)
    {
      ASSERT (op - ops < n_ops);
      if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
        {
          u32 err, bi = op->user_data;
          if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
            err = e;
          else
            err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
          b[bi]->error = node->errors[err];
          nexts[bi] = ESP_DECRYPT_NEXT_DROP;
          n_fail--;
        }
      op++;
    }
}

always_inline void
esp_remove_tail (vlib_main_t * vm, vlib_buffer_t * b, vlib_buffer_t * last,
                 u16 tail)
{
  vlib_buffer_t *before_last = b;

  if (last->current_length > tail)
    {
      last->current_length -= tail;
      return;
    }
  ASSERT (b->flags & VLIB_BUFFER_NEXT_PRESENT);

  while (b->flags & VLIB_BUFFER_NEXT_PRESENT)
    {
      before_last = b;
      b = vlib_get_buffer (vm, b->next_buffer);
    }
  before_last->current_length -= tail - last->current_length;
  vlib_buffer_free_one (vm, before_last->next_buffer);
  before_last->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
}

/* ICV is splitted in last two buffers so move it to the last buffer and
   return pointer to it */
static_always_inline u8 *
esp_move_icv (vlib_main_t * vm, vlib_buffer_t * first,
              esp_decrypt_packet_data2_t * pd2, u16 icv_sz, u16 * dif)
{
  vlib_buffer_t *before_last, *bp;
  u16 last_sz = pd2->lb->current_length;
  u16 first_sz = icv_sz - last_sz;

  bp = before_last = first;
  while (bp->flags & VLIB_BUFFER_NEXT_PRESENT)
    {
      before_last = bp;
      bp = vlib_get_buffer (vm, bp->next_buffer);
    }

  u8 *lb_curr = vlib_buffer_get_current (pd2->lb);
  memmove (lb_curr + first_sz, lb_curr, last_sz);
  clib_memcpy_fast (lb_curr, vlib_buffer_get_tail (before_last) - first_sz,
                    first_sz);
  before_last->current_length -= first_sz;
  clib_memset (vlib_buffer_get_tail (before_last), 0, first_sz);
  if (dif)
    dif[0] = first_sz;
  pd2->lb = before_last;
  pd2->icv_removed = 1;
  pd2->free_buffer_index = before_last->next_buffer;
  before_last->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
  return lb_curr;
}

static_always_inline i16
esp_insert_esn (vlib_main_t * vm, ipsec_sa_t * sa,
                esp_decrypt_packet_data2_t * pd2, u32 * data_len,
                u8 ** digest, u16 * len, vlib_buffer_t * b, u8 * payload)
{
  if (!ipsec_sa_is_set_USE_ESN (sa))
    return 0;

  /* shift ICV by 4 bytes to insert ESN */
  u32 seq_hi = clib_host_to_net_u32 (sa->seq_hi);
  u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa->seq_hi);

  if (pd2->icv_removed)
    {
      u16 space_left = vlib_buffer_space_left_at_end (vm, pd2->lb);
      if (space_left >= sz)
        {
          clib_memcpy_fast (vlib_buffer_get_tail (pd2->lb), &seq_hi, sz);
          *data_len += sz;
        }
      else
        return sz;

      len[0] = b->current_length;
    }
  else
    {
      clib_memcpy_fast (tmp, payload + len[0], ESP_MAX_ICV_SIZE);
      clib_memcpy_fast (payload + len[0], &seq_hi, sz);
      clib_memcpy_fast (payload + len[0] + sz, tmp, ESP_MAX_ICV_SIZE);
      *data_len += sz;
      *digest += sz;
    }
  return sz;
}

static_always_inline u8 *
esp_move_icv_esn (vlib_main_t * vm, vlib_buffer_t * first,
                  esp_decrypt_packet_data2_t * pd2, u16 icv_sz,
                  ipsec_sa_t * sa, u8 * extra_esn, u32 * len)
{
  u16 dif = 0;
  u8 *digest = esp_move_icv (vm, first, pd2, icv_sz, &dif);
  if (dif)
    *len -= dif;

  if (ipsec_sa_is_set_USE_ESN (sa))
    {
      u8 sz = sizeof (sa->seq_hi);
      u32 seq_hi = clib_host_to_net_u32 (sa->seq_hi);
      u16 space_left = vlib_buffer_space_left_at_end (vm, pd2->lb);

      if (space_left >= sz)
        {
          clib_memcpy_fast (vlib_buffer_get_tail (pd2->lb), &seq_hi, sz);
          *len += sz;
        }
      else
        {
          /* no space for ESN at the tail, use the next buffer
           * (with ICV data) */
          ASSERT (pd2->icv_removed);
          vlib_buffer_t *tmp = vlib_get_buffer (vm, pd2->free_buffer_index);
          clib_memcpy_fast (vlib_buffer_get_current (tmp) - sz, &seq_hi, sz);
          extra_esn[0] = 1;
        }
    }
  return digest;
}

static_always_inline int
esp_decrypt_chain_integ (vlib_main_t * vm, ipsec_per_thread_data_t * ptd,
                         esp_decrypt_packet_data2_t * pd2,
                         ipsec_sa_t * sa0, vlib_buffer_t * b, u8 icv_sz,
                         u8 * start_src, u32 start_len,
                         u8 ** digest, u16 * n_ch, u32 * integ_total_len)
{
  vnet_crypto_op_chunk_t *ch;
  vlib_buffer_t *cb = vlib_get_buffer (vm, b->next_buffer);
  u16 n_chunks = 1;
  u32 total_len;
  vec_add2 (ptd->chunks, ch, 1);
  total_len = ch->len = start_len;
  ch->src = start_src;

  while (1)
    {
      vec_add2 (ptd->chunks, ch, 1);
      n_chunks += 1;
      ch->src = vlib_buffer_get_current (cb);
      if (pd2->lb == cb)
        {
          if (pd2->icv_removed)
            ch->len = cb->current_length;
          else
            ch->len = cb->current_length - icv_sz;
          if (ipsec_sa_is_set_USE_ESN (sa0))
            {
              u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
              u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi);
              u8 *esn;
              vlib_buffer_t *tmp_b;
              u16 space_left = vlib_buffer_space_left_at_end (vm, pd2->lb);
              if (space_left < sz)
                {
                  if (pd2->icv_removed)
                    {
                      /* use pre-data area from the last bufer
                         that was removed from the chain */
                      tmp_b = vlib_get_buffer (vm, pd2->free_buffer_index);
                      esn = tmp_b->data - sz;
                    }
                  else
                    {
                      /* no space, need to allocate new buffer */
                      u32 tmp_bi = 0;
                      if (vlib_buffer_alloc (vm, &tmp_bi, 1) != 1)
                        return -1;
                      tmp_b = vlib_get_buffer (vm, tmp_bi);
                      esn = tmp_b->data;
                      pd2->free_buffer_index = tmp_bi;
                    }
                  clib_memcpy_fast (esn, &seq_hi, sz);

                  vec_add2 (ptd->chunks, ch, 1);
                  n_chunks += 1;
                  ch->src = esn;
                  ch->len = sz;
                }
              else
                {
                  if (pd2->icv_removed)
                    {
                      clib_memcpy_fast (vlib_buffer_get_tail
                                        (pd2->lb), &seq_hi, sz);
                    }
                  else
                    {
                      clib_memcpy_fast (tmp, *digest, ESP_MAX_ICV_SIZE);
                      clib_memcpy_fast (*digest, &seq_hi, sz);
                      clib_memcpy_fast (*digest + sz, tmp, ESP_MAX_ICV_SIZE);
                      *digest += sz;
                    }
                  ch->len += sz;
                }
            }
          total_len += ch->len;
          break;
        }
      else
        total_len += ch->len = cb->current_length;

      if (!(cb->flags & VLIB_BUFFER_NEXT_PRESENT))
        break;

      cb = vlib_get_buffer (vm, cb->next_buffer);
    }

  if (n_ch)
    *n_ch = n_chunks;
  if (integ_total_len)
    *integ_total_len = total_len;

  return 0;
}

static_always_inline u32
esp_decrypt_chain_crypto (vlib_main_t * vm, ipsec_per_thread_data_t * ptd,
                          esp_decrypt_packet_data2_t * pd2,
                          ipsec_sa_t * sa0, vlib_buffer_t * b, u8 icv_sz,
                          u8 * start, u32 start_len, u8 ** tag, u16 * n_ch)
{
  vnet_crypto_op_chunk_t *ch;
  vlib_buffer_t *cb = b;
  u16 n_chunks = 1;
  u32 total_len;
  vec_add2 (ptd->chunks, ch, 1);
  total_len = ch->len = start_len;
  ch->src = ch->dst = start;
  cb = vlib_get_buffer (vm, cb->next_buffer);
  n_chunks = 1;

  while (1)
    {
      vec_add2 (ptd->chunks, ch, 1);
      n_chunks += 1;
      ch->src = ch->dst = vlib_buffer_get_current (cb);
      if (pd2->lb == cb)
        {
          if (ipsec_sa_is_set_IS_AEAD (sa0))
            {
              if (pd2->lb->current_length < icv_sz)
                {
                  u16 dif = 0;
                  *tag = esp_move_icv (vm, b, pd2, icv_sz, &dif);

                  /* this chunk does not contain crypto data */
                  n_chunks -= 1;
                  /* and fix previous chunk's length as it might have
                     been changed */
                  ASSERT (n_chunks > 0);
                  if (pd2->lb == b)
                    {
                      total_len -= dif;
                      ch[-1].len -= dif;
                    }
                  else
                    {
                      total_len = total_len + pd2->lb->current_length -
                        ch[-1].len;
                      ch[-1].len = pd2->lb->current_length;
                    }
                  break;
                }
              else
                *tag = vlib_buffer_get_tail (pd2->lb) - icv_sz;
            }

          if (pd2->icv_removed)
            total_len += ch->len = cb->current_length;
          else
            total_len += ch->len = cb->current_length - icv_sz;
        }
      else
        total_len += ch->len = cb->current_length;

      if (!(cb->flags & VLIB_BUFFER_NEXT_PRESENT))
        break;

      cb = vlib_get_buffer (vm, cb->next_buffer);
    }

  if (n_ch)
    *n_ch = n_chunks;

  return total_len;
}

static_always_inline void
esp_decrypt_prepare_sync_op (vlib_main_t * vm, vlib_node_runtime_t * node,
                             ipsec_per_thread_data_t * ptd,
                             vnet_crypto_op_t *** crypto_ops,
                             vnet_crypto_op_t *** integ_ops,
                             vnet_crypto_op_t * op,
                             ipsec_sa_t * sa0, u8 * payload,
                             u16 len, u8 icv_sz, u8 iv_sz,
                             esp_decrypt_packet_data_t * pd,
                             esp_decrypt_packet_data2_t * pd2,
                             vlib_buffer_t * b, u16 * next, u32 index)
{
  const u8 esp_sz = sizeof (esp_header_t);

  if (PREDICT_TRUE (sa0->integ_op_id != VNET_CRYPTO_OP_NONE))
    {
      vnet_crypto_op_init (op, sa0->integ_op_id);
      op->key_index = sa0->integ_key_index;
      op->src = payload;
      op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
      op->user_data = index;
      op->digest = payload + len;
      op->digest_len = icv_sz;
      op->len = len;

      if (pd->is_chain)
        {
          /* buffer is chained */
          op->len = pd->current_length;

          /* special case when ICV is splitted and needs to be reassembled
           * first -> move it to the last buffer. Also take into account
           * that ESN needs to be added after encrypted data and may or
           * may not fit in the tail.*/
          if (pd2->lb->current_length < icv_sz)
            {
              u8 extra_esn = 0;
              op->digest =
                esp_move_icv_esn (vm, b, pd2, icv_sz, sa0,
                                  &extra_esn, &op->len);

              if (extra_esn)
                {
                  /* esn is in the last buffer, that was unlinked from
                   * the chain */
                  op->len = b->current_length;
                }
              else
                {
                  if (pd2->lb == b)
                    {
                      /* we now have a single buffer of crypto data, adjust
                       * the length (second buffer contains only ICV) */
                      *integ_ops = &ptd->integ_ops;
                      *crypto_ops = &ptd->crypto_ops;
                      len = b->current_length;
                      goto out;
                    }
                }
            }
          else
            op->digest = vlib_buffer_get_tail (pd2->lb) - icv_sz;

          op->flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;
          op->chunk_index = vec_len (ptd->chunks);
          if (esp_decrypt_chain_integ (vm, ptd, pd2, sa0, b, icv_sz,
                                       payload, pd->current_length,
                                       &op->digest, &op->n_chunks, 0) < 0)
            {
              b->error = node->errors[ESP_DECRYPT_ERROR_NO_BUFFERS];
              next[0] = ESP_DECRYPT_NEXT_DROP;
              return;
            }
        }
      else
        esp_insert_esn (vm, sa0, pd2, &op->len, &op->digest, &len, b,
                        payload);
    out:
      vec_add_aligned (*(integ_ops[0]), op, 1, CLIB_CACHE_LINE_BYTES);
    }

  payload += esp_sz;
  len -= esp_sz;

  if (sa0->crypto_dec_op_id != VNET_CRYPTO_OP_NONE)
    {
      vnet_crypto_op_init (op, sa0->crypto_dec_op_id);
      op->key_index = sa0->crypto_key_index;
      op->iv = payload;

      if (ipsec_sa_is_set_IS_AEAD (sa0))
        {
          esp_header_t *esp0;
          esp_aead_t *aad;
          u8 *scratch;

          /*
           * construct the AAD and the nonce (Salt || IV) in a scratch
           * space in front of the IP header.
           */
          scratch = payload - esp_sz;
          esp0 = (esp_header_t *) (scratch);

          scratch -= (sizeof (*aad) + pd->hdr_sz);
          op->aad = scratch;

          op->aad_len = esp_aad_fill (op->aad, esp0, sa0);

          /*
           * we don't need to refer to the ESP header anymore so we
           * can overwrite it with the salt and use the IV where it is
           * to form the nonce = (Salt + IV)
           */
          op->iv -= sizeof (sa0->salt);
          clib_memcpy_fast (op->iv, &sa0->salt, sizeof (sa0->salt));

          op->tag = payload + len;
          op->tag_len = 16;
        }
      op->src = op->dst = payload += iv_sz;
      op->len = len - iv_sz;
      op->user_data = index;

      if (pd->is_chain && (pd2->lb != b))
        {
          /* buffer is chained */
          op->flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;
          op->chunk_index = vec_len (ptd->chunks);
          esp_decrypt_chain_crypto (vm, ptd, pd2, sa0, b, icv_sz,
                                    payload, len - pd->iv_sz + pd->icv_sz,
                                    &op->tag, &op->n_chunks);
        }

      vec_add_aligned (*(crypto_ops[0]), op, 1, CLIB_CACHE_LINE_BYTES);
    }
}

static_always_inline int
esp_decrypt_prepare_async_frame (vlib_main_t * vm,
                                 vlib_node_runtime_t * node,
                                 ipsec_per_thread_data_t * ptd,
                                 vnet_crypto_async_frame_t ** f,
                                 ipsec_sa_t * sa0, u8 * payload, u16 len,
                                 u8 icv_sz, u8 iv_sz,
                                 esp_decrypt_packet_data_t * pd,
                                 esp_decrypt_packet_data2_t * pd2, u32 bi,
                                 vlib_buffer_t * b, u16 * next,
                                 u16 async_next)
{
  const u8 esp_sz = sizeof (esp_header_t);
  u32 current_protect_index = vnet_buffer (b)->ipsec.protect_index;
  esp_decrypt_packet_data_t *async_pd = &(esp_post_data (b))->decrypt_data;
  esp_decrypt_packet_data2_t *async_pd2 = esp_post_data2 (b);
  u8 *tag = payload + len, *iv = payload + esp_sz, *aad = 0;
  u32 key_index;
  u32 crypto_len, integ_len = 0;
  i16 crypto_start_offset, integ_start_offset = 0;
  u8 flags = 0;

  if (!ipsec_sa_is_set_IS_AEAD (sa0))
    {
      /* linked algs */
      key_index = sa0->linked_key_index;
      integ_start_offset = payload - b->data;
      integ_len = len;

      if (pd->is_chain)
        {
          /* buffer is chained */
          integ_len = pd->current_length;

          /* special case when ICV is splitted and needs to be reassembled
           * first -> move it to the last buffer. Also take into account
           * that ESN needs to be added after encrypted data and may or
           * may not fit in the tail.*/
          if (pd2->lb->current_length < icv_sz)
            {
              u8 extra_esn = 0;
              tag = esp_move_icv_esn (vm, b, pd2, icv_sz, sa0,
                                      &extra_esn, &integ_len);

              if (extra_esn)
                {
                  /* esn is in the last buffer, that was unlinked from
                   * the chain */
                  integ_len = b->current_length;
                }
              else
                {
                  if (pd2->lb == b)
                    {
                      /* we now have a single buffer of crypto data, adjust
                       * the length (second buffer contains only ICV) */
                      len = b->current_length;
                      goto out;
                    }
                }
            }
          else
            tag = vlib_buffer_get_tail (pd2->lb) - icv_sz;

          flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;
          if (esp_decrypt_chain_integ (vm, ptd, pd2, sa0, b, icv_sz, payload,
                                       pd->current_length, &tag,
                                       0, &integ_len) < 0)
            {
              /* allocate buffer failed, will not add to frame and drop */
              b->error = node->errors[ESP_DECRYPT_ERROR_NO_BUFFERS];
              next[0] = ESP_DECRYPT_NEXT_DROP;
              return -1;
            }
        }
      else
        esp_insert_esn (vm, sa0, pd2, &integ_len, &tag, &len, b, payload);
    }
  else
    key_index = sa0->crypto_key_index;

out:
  /* crypto */
  payload += esp_sz;
  len -= esp_sz;
  iv = payload;

  if (ipsec_sa_is_set_IS_AEAD (sa0))
    {
      esp_header_t *esp0;
      u8 *scratch;

      /*
       * construct the AAD and the nonce (Salt || IV) in a scratch
       * space in front of the IP header.
       */
      scratch = payload - esp_sz;
      esp0 = (esp_header_t *) (scratch);

      scratch -= (sizeof (esp_aead_t) + pd->hdr_sz);
      aad = scratch;

      esp_aad_fill (aad, esp0, sa0);

      /*
       * we don't need to refer to the ESP header anymore so we
       * can overwrite it with the salt and use the IV where it is
       * to form the nonce = (Salt + IV)
       */
      iv -= sizeof (sa0->salt);
      clib_memcpy_fast (iv, &sa0->salt, sizeof (sa0->salt));

      tag = payload + len;
    }

  crypto_start_offset = (payload += iv_sz) - b->data;
  crypto_len = len - iv_sz;

  if (pd->is_chain && (pd2->lb != b))
    {
      /* buffer is chained */
      flags |= VNET_CRYPTO_OP_FLAG_CHAINED_BUFFERS;

      crypto_len = esp_decrypt_chain_crypto (vm, ptd, pd2, sa0, b, icv_sz,
                                             payload,
                                             len - pd->iv_sz + pd->icv_sz,
                                             &tag, 0);
    }

  *async_pd = *pd;
  *async_pd2 = *pd2;
  pd->protect_index = current_protect_index;

  /* for AEAD integ_len - crypto_len will be negative, it is ok since it
   * is ignored by the engine. */
  return vnet_crypto_async_add_to_frame (vm, f, key_index, crypto_len,
                                         integ_len - crypto_len,
                                         crypto_start_offset,
                                         integ_start_offset,
                                         bi, async_next, iv, tag, aad, flags);
}

static_always_inline void
esp_decrypt_post_crypto (vlib_main_t * vm, vlib_node_runtime_t * node,
                         esp_decrypt_packet_data_t * pd,
                         esp_decrypt_packet_data2_t * pd2, vlib_buffer_t * b,
                         u16 * next, int is_ip6, int is_tun, int is_async)
{
  ipsec_main_t *im = &ipsec_main;
  ipsec_sa_t *sa0 = vec_elt_at_index (im->sad, pd->sa_index);
  vlib_buffer_t *lb = b;
  const u8 esp_sz = sizeof (esp_header_t);
  const u8 tun_flags = IPSEC_SA_FLAG_IS_TUNNEL | IPSEC_SA_FLAG_IS_TUNNEL_V6;
  u8 pad_length = 0, next_header = 0;
  u16 icv_sz;

  /*
   * redo the anti-reply check
   * in this frame say we have sequence numbers, s, s+1, s+1, s+1
   * and s and s+1 are in the window. When we did the anti-replay
   * check above we did so against the state of the window (W),
   * after packet s-1. So each of the packets in the sequence will be
   * accepted.
   * This time s will be cheked against Ws-1, s+1 chceked against Ws
   * (i.e. the window state is updated/advnaced)
   * so this time the successive s+! packet will be dropped.
   * This is a consequence of batching the decrypts. If the
   * check-dcrypt-advance process was done for each packet it would
   * be fine. But we batch the decrypts because it's much more efficient
   * to do so in SW and if we offload to HW and the process is async.
   *
   * You're probably thinking, but this means an attacker can send the
   * above sequence and cause VPP to perform decrpyts that will fail,
   * and that's true. But if the attacker can determine s (a valid
   * sequence number in the window) which is non-trivial, it can generate
   * a sequence s, s+1, s+2, s+3, ... s+n and nothing will prevent any
   * implementation, sequential or batching, from decrypting these.
   */
  if (ipsec_sa_anti_replay_check (sa0, pd->seq))
    {
      b->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
      next[0] = ESP_DECRYPT_NEXT_DROP;
      return;
    }

  ipsec_sa_anti_replay_advance (sa0, pd->seq);

  if (pd->is_chain)
    {
      lb = pd2->lb;
      icv_sz = pd2->icv_removed ? 0 : pd->icv_sz;
      if (pd2->free_buffer_index)
        {
          vlib_buffer_free_one (vm, pd2->free_buffer_index);
          lb->next_buffer = 0;
        }
      if (lb->current_length < sizeof (esp_footer_t) + icv_sz)
        {
          /* esp footer is either splitted in two buffers or in the before
           * last buffer */

          vlib_buffer_t *before_last = b, *bp = b;
          while (bp->flags & VLIB_BUFFER_NEXT_PRESENT)
            {
              before_last = bp;
              bp = vlib_get_buffer (vm, bp->next_buffer);
            }
          u8 *bt = vlib_buffer_get_tail (before_last);

          if (lb->current_length == icv_sz)
            {
              esp_footer_t *f = (esp_footer_t *) (bt - sizeof (*f));
              pad_length = f->pad_length;
              next_header = f->next_header;
            }
          else
            {
              pad_length = (bt - 1)[0];
              next_header = ((u8 *) vlib_buffer_get_current (lb))[0];
            }
        }
      else
        {
          esp_footer_t *f =
            (esp_footer_t *) (lb->data + lb->current_data +
                              lb->current_length - sizeof (esp_footer_t) -
                              icv_sz);
          pad_length = f->pad_length;
          next_header = f->next_header;
        }
    }
  else
    {
      icv_sz = pd->icv_sz;
      esp_footer_t *f =
        (esp_footer_t *) (lb->data + lb->current_data + lb->current_length -
                          sizeof (esp_footer_t) - icv_sz);
      pad_length = f->pad_length;
      next_header = f->next_header;
    }

  u16 adv = pd->iv_sz + esp_sz;
  u16 tail = sizeof (esp_footer_t) + pad_length + icv_sz;
  u16 tail_orig = sizeof (esp_footer_t) + pad_length + pd->icv_sz;
  b->flags &= ~VLIB_BUFFER_TOTAL_LENGTH_VALID;

  if ((pd->flags & tun_flags) == 0 && !is_tun)  /* transport mode */
    {
      u8 udp_sz = (is_ip6 == 0 && pd->flags & IPSEC_SA_FLAG_UDP_ENCAP) ?
        sizeof (udp_header_t) : 0;
      u16 ip_hdr_sz = pd->hdr_sz - udp_sz;
      u8 *old_ip = b->data + pd->current_data - ip_hdr_sz - udp_sz;
      u8 *ip = old_ip + adv + udp_sz;

      if (is_ip6 && ip_hdr_sz > 64)
        memmove (ip, old_ip, ip_hdr_sz);
      else
        clib_memcpy_le64 (ip, old_ip, ip_hdr_sz);

      b->current_data = pd->current_data + adv - ip_hdr_sz;
      b->current_length += ip_hdr_sz - adv;
      esp_remove_tail (vm, b, lb, tail);

      if (is_ip6)
        {
          ip6_header_t *ip6 = (ip6_header_t *) ip;
          u16 len = clib_net_to_host_u16 (ip6->payload_length);
          len -= adv + tail_orig;
          ip6->payload_length = clib_host_to_net_u16 (len);
          ip6->protocol = next_header;
          next[0] = ESP_DECRYPT_NEXT_IP6_INPUT;
        }
      else
        {
          ip4_header_t *ip4 = (ip4_header_t *) ip;
          ip_csum_t sum = ip4->checksum;
          u16 len = clib_net_to_host_u16 (ip4->length);
          len = clib_host_to_net_u16 (len - adv - tail_orig - udp_sz);
          sum = ip_csum_update (sum, ip4->protocol, next_header,
                                ip4_header_t, protocol);
          sum = ip_csum_update (sum, ip4->length, len, ip4_header_t, length);
          ip4->checksum = ip_csum_fold (sum);
          ip4->protocol = next_header;
          ip4->length = len;
          next[0] = ESP_DECRYPT_NEXT_IP4_INPUT;
        }
    }
  else
    {
      if (PREDICT_TRUE (next_header == IP_PROTOCOL_IP_IN_IP))
        {
          next[0] = ESP_DECRYPT_NEXT_IP4_INPUT;
          b->current_data = pd->current_data + adv;
          b->current_length = pd->current_length - adv;
          esp_remove_tail (vm, b, lb, tail);
        }
      else if (next_header == IP_PROTOCOL_IPV6)
        {
          next[0] = ESP_DECRYPT_NEXT_IP6_INPUT;
          b->current_data = pd->current_data + adv;
          b->current_length = pd->current_length - adv;
          esp_remove_tail (vm, b, lb, tail);
        }
      else
        {
          if (is_tun && next_header == IP_PROTOCOL_GRE)
            {
              gre_header_t *gre;

              b->current_data = pd->current_data + adv;
              b->current_length = pd->current_length - adv - tail;

              gre = vlib_buffer_get_current (b);

              vlib_buffer_advance (b, sizeof (*gre));

              switch (clib_net_to_host_u16 (gre->protocol))
                {
                case GRE_PROTOCOL_teb:
                  vnet_update_l2_len (b);
                  next[0] = ESP_DECRYPT_NEXT_L2_INPUT;
                  break;
                case GRE_PROTOCOL_ip4:
                  next[0] = ESP_DECRYPT_NEXT_IP4_INPUT;
                  break;
                case GRE_PROTOCOL_ip6:
                  next[0] = ESP_DECRYPT_NEXT_IP6_INPUT;
                  break;
                default:
                  b->error = node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
                  next[0] = ESP_DECRYPT_NEXT_DROP;
                  break;
                }
            }
          else
            {
              next[0] = ESP_DECRYPT_NEXT_DROP;
              b->error = node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
              return;
            }
        }
      if (is_tun)
        {
          if (ipsec_sa_is_set_IS_PROTECT (sa0))
            {
              /*
               * There are two encap possibilities
               * 1) the tunnel and ths SA are prodiving encap, i.e. it's
               *   MAC | SA-IP | TUN-IP | ESP | PAYLOAD
               * implying the SA is in tunnel mode (on a tunnel interface)
               * 2) only the tunnel provides encap
               *   MAC | TUN-IP | ESP | PAYLOAD
               * implying the SA is in transport mode.
               *
               * For 2) we need only strip the tunnel encap and we're good.
               *  since the tunnel and crypto ecnap (int the tun=protect
               * object) are the same and we verified above that these match
               * for 1) we need to strip the SA-IP outer headers, to
               * reveal the tunnel IP and then check that this matches
               * the configured tunnel.
               */
              const ipsec_tun_protect_t *itp;

              if (is_async)
                itp = ipsec_tun_protect_get (pd->protect_index);
              else
                itp =
                  ipsec_tun_protect_get (vnet_buffer (b)->
                                         ipsec.protect_index);

              if (PREDICT_TRUE (next_header == IP_PROTOCOL_IP_IN_IP))
                {
                  const ip4_header_t *ip4;

                  ip4 = vlib_buffer_get_current (b);

                  if (!ip46_address_is_equal_v4 (&itp->itp_tun.src,
                                                 &ip4->dst_address) ||
                      !ip46_address_is_equal_v4 (&itp->itp_tun.dst,
                                                 &ip4->src_address))
                    {
                      next[0] = ESP_DECRYPT_NEXT_DROP;
                      b->error = node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
                    }
                }
              else if (next_header == IP_PROTOCOL_IPV6)
                {
                  const ip6_header_t *ip6;

                  ip6 = vlib_buffer_get_current (b);

                  if (!ip46_address_is_equal_v6 (&itp->itp_tun.src,
                                                 &ip6->dst_address) ||
                      !ip46_address_is_equal_v6 (&itp->itp_tun.dst,
                                                 &ip6->src_address))
                    {
                      next[0] = ESP_DECRYPT_NEXT_DROP;
                      b->error = node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
                    }
                }
            }
        }
    }
}

always_inline uword
esp_decrypt_inline (vlib_main_t * vm,
                    vlib_node_runtime_t * node, vlib_frame_t * from_frame,
                    int is_ip6, int is_tun, u16 async_next)
{
  ipsec_main_t *im = &ipsec_main;
  u32 thread_index = vm->thread_index;
  u16 len;
  ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index);
  u32 *from = vlib_frame_vector_args (from_frame);
  u32 n_left = from_frame->n_vectors;
  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
  u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
  esp_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data;
  esp_decrypt_packet_data2_t pkt_data2[VLIB_FRAME_SIZE], *pd2 = pkt_data2;
  esp_decrypt_packet_data_t cpd = { };
  u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
  const u8 esp_sz = sizeof (esp_header_t);
  ipsec_sa_t *sa0 = 0;
  vnet_crypto_op_t _op, *op = &_op;
  vnet_crypto_op_t **crypto_ops = &ptd->crypto_ops;
  vnet_crypto_op_t **integ_ops = &ptd->integ_ops;
  vnet_crypto_async_frame_t *async_frame = 0;
  int is_async = im->async_mode;
  vnet_crypto_async_op_id_t last_async_op = ~0;
  u16 n_async_drop = 0;

  vlib_get_buffers (vm, from, b, n_left);
  if (!is_async)
    {
      vec_reset_length (ptd->crypto_ops);
      vec_reset_length (ptd->integ_ops);
      vec_reset_length (ptd->chained_crypto_ops);
      vec_reset_length (ptd->chained_integ_ops);
    }
  vec_reset_length (ptd->chunks);
  clib_memset_u16 (nexts, -1, n_left);

  while (n_left > 0)
    {
      u8 *payload;

      if (n_left > 2)
        {
          u8 *p;
          vlib_prefetch_buffer_header (b[2], LOAD);
          p = vlib_buffer_get_current (b[1]);
          CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD);
          p -= CLIB_CACHE_LINE_BYTES;
          CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD);
        }

      u32 n_bufs = vlib_buffer_chain_linearize (vm, b[0]);
      if (n_bufs == 0)
        {
          b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_BUFFERS];
          esp_set_next_index (is_async, from, nexts, from[b - bufs],
                              &n_async_drop, ESP_DECRYPT_NEXT_DROP, next);
          next[0] = ESP_DECRYPT_NEXT_DROP;
          goto next;
        }

      if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index)
        {
          if (current_sa_pkts)
            vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
                                             current_sa_index,
                                             current_sa_pkts,
                                             current_sa_bytes);
          current_sa_bytes = current_sa_pkts = 0;

          current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;
          sa0 = pool_elt_at_index (im->sad, current_sa_index);

          /* fetch the second cacheline ASAP */
          CLIB_PREFETCH (sa0->cacheline1, CLIB_CACHE_LINE_BYTES, LOAD);
          cpd.icv_sz = sa0->integ_icv_size;
          cpd.iv_sz = sa0->crypto_iv_size;
          cpd.flags = sa0->flags;
          cpd.sa_index = current_sa_index;

          /* submit frame when op_id is different then the old one */
          if (is_async && last_async_op != sa0->crypto_async_dec_op_id)
            {
              if (async_frame && async_frame->n_elts)
                {
                  if (vnet_crypto_async_submit_open_frame (vm, async_frame))
                    esp_async_recycle_failed_submit (async_frame, b, from,
                                                     nexts, &n_async_drop,
                                                     ESP_DECRYPT_NEXT_DROP,
                                                     ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR);
                }
              async_frame =
                vnet_crypto_async_get_frame (vm, sa0->crypto_async_dec_op_id);
              last_async_op = sa0->crypto_async_dec_op_id;
            }
        }

      if (PREDICT_FALSE (~0 == sa0->decrypt_thread_index))
        {
          /* this is the first packet to use this SA, claim the SA
           * for this thread. this could happen simultaneously on
           * another thread */
          clib_atomic_cmp_and_swap (&sa0->decrypt_thread_index, ~0,
                                    ipsec_sa_assign_thread (thread_index));
        }

      if (PREDICT_FALSE (thread_index != sa0->decrypt_thread_index))
        {
          esp_set_next_index (is_async, from, nexts, from[b - bufs],
                              &n_async_drop, ESP_DECRYPT_NEXT_HANDOFF, next);
          next[0] = ESP_DECRYPT_NEXT_HANDOFF;
          goto next;
        }

      /* store packet data for next round for easier prefetch */
      pd->sa_data = cpd.sa_data;
      pd->current_data = b[0]->current_data;
      pd->hdr_sz = pd->current_data - vnet_buffer (b[0])->l3_hdr_offset;
      payload = b[0]->data + pd->current_data;
      pd->seq = clib_host_to_net_u32 (((esp_header_t *) payload)->seq);
      pd->is_chain = 0;
      pd2->lb = b[0];
      pd2->free_buffer_index = 0;
      pd2->icv_removed = 0;

      if (n_bufs > 1)
        {
          pd->is_chain = 1;
          /* find last buffer in the chain */
          while (pd2->lb->flags & VLIB_BUFFER_NEXT_PRESENT)
            pd2->lb = vlib_get_buffer (vm, pd2->lb->next_buffer);

          crypto_ops = &ptd->chained_crypto_ops;
          integ_ops = &ptd->chained_integ_ops;
        }

      pd->current_length = b[0]->current_length;

      /* anti-reply check */
      if (ipsec_sa_anti_replay_check (sa0, pd->seq))
        {
          b[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
          esp_set_next_index (is_async, from, nexts, from[b - bufs],
                              &n_async_drop, ESP_DECRYPT_NEXT_DROP, next);
          goto next;
        }

      if (pd->current_length < cpd.icv_sz + esp_sz + cpd.iv_sz)
        {
          b[0]->error = node->errors[ESP_DECRYPT_ERROR_RUNT];
          esp_set_next_index (is_async, from, nexts, from[b - bufs],
                              &n_async_drop, ESP_DECRYPT_NEXT_DROP, next);
          goto next;
        }

      len = pd->current_length - cpd.icv_sz;
      current_sa_pkts += 1;
      current_sa_bytes += vlib_buffer_length_in_chain (vm, b[0]);

      if (is_async)
        {
          int ret = esp_decrypt_prepare_async_frame (vm, node, ptd,
                                                     &async_frame,
                                                     sa0, payload, len,
                                                     cpd.icv_sz,
                                                     cpd.iv_sz,
                                                     pd, pd2,
                                                     from[b - bufs],
                                                     b[0], next, async_next);
          if (PREDICT_FALSE (ret < 0))
            {
              b[0]->error = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
              esp_set_next_index (1, from, nexts, from[b - bufs],
                                  &n_async_drop, ESP_DECRYPT_NEXT_DROP, next);
              /* when next[0] is ESP_DECRYPT_NEXT_DROP we only have to drop
               * the current packet. Otherwise it is frame submission error
               * thus we have to drop the whole frame.
               */
              if (next[0] != ESP_DECRYPT_NEXT_DROP && async_frame->n_elts)
                esp_async_recycle_failed_submit (async_frame, b, from,
                                                 nexts, &n_async_drop,
                                                 ESP_DECRYPT_NEXT_DROP,
                                                 ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR);
              goto next;
            }
        }
      else
        esp_decrypt_prepare_sync_op (vm, node, ptd, &crypto_ops, &integ_ops,
                                     op, sa0, payload, len, cpd.icv_sz,
                                     cpd.iv_sz, pd, pd2, b[0], next,
                                     b - bufs);
      /* next */
    next:
      n_left -= 1;
      next += 1;
      pd += 1;
      pd2 += 1;
      b += 1;
    }

  if (PREDICT_TRUE (~0 != current_sa_index))
    vlib_increment_combined_counter (&ipsec_sa_counters, thread_index,
                                     current_sa_index, current_sa_pkts,
                                     current_sa_bytes);

  if (is_async)
    {
      if (async_frame && async_frame->n_elts)
        {
          if (vnet_crypto_async_submit_open_frame (vm, async_frame) < 0)
            esp_async_recycle_failed_submit (async_frame, b, from, nexts,
                                             &n_async_drop,
                                             ESP_DECRYPT_NEXT_DROP,
                                             ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR);
        }

      /* no post process in async */
      vlib_node_increment_counter (vm, node->node_index,
                                   ESP_DECRYPT_ERROR_RX_PKTS, n_left);
      if (n_async_drop)
        vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_async_drop);

      return n_left;
    }
  else
    {
      esp_process_ops (vm, node, ptd->integ_ops, bufs, nexts,
                       ESP_DECRYPT_ERROR_INTEG_ERROR);
      esp_process_chained_ops (vm, node, ptd->chained_integ_ops, bufs, nexts,
                               ptd->chunks, ESP_DECRYPT_ERROR_INTEG_ERROR);

      esp_process_ops (vm, node, ptd->crypto_ops, bufs, nexts,
                       ESP_DECRYPT_ERROR_DECRYPTION_FAILED);
      esp_process_chained_ops (vm, node, ptd->chained_crypto_ops, bufs, nexts,
                               ptd->chunks,
                               ESP_DECRYPT_ERROR_DECRYPTION_FAILED);
    }

  /* Post decryption ronud - adjust packet data start and length and next
     node */

  n_left = from_frame->n_vectors;
  next = nexts;
  pd = pkt_data;
  pd2 = pkt_data2;
  b = bufs;

  while (n_left)
    {
      if (n_left >= 2)
        {
          void *data = b[1]->data + pd[1].current_data;

          /* buffer metadata */
          vlib_prefetch_buffer_header (b[1], LOAD);

          /* esp_footer_t */
          CLIB_PREFETCH (data + pd[1].current_length - pd[1].icv_sz - 2,
                         CLIB_CACHE_LINE_BYTES, LOAD);

          /* packet headers */
          CLIB_PREFETCH (data - CLIB_CACHE_LINE_BYTES,
                         CLIB_CACHE_LINE_BYTES * 2, LOAD);
        }

      /* save the sa_index as GRE_teb post_crypto changes L2 opaque */
      if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
        current_sa_index = vnet_buffer (b[0])->ipsec.sad_index;

      if (next[0] >= ESP_DECRYPT_N_NEXT)
        esp_decrypt_post_crypto (vm, node, pd, pd2, b[0], next, is_ip6,
                                 is_tun, 0);

      /* trace: */
      if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
        {
          esp_decrypt_trace_t *tr;
          tr = vlib_add_trace (vm, node, b[0], sizeof (*tr));
          sa0 = pool_elt_at_index (im->sad, current_sa_index);
          tr->crypto_alg = sa0->crypto_alg;
          tr->integ_alg = sa0->integ_alg;
          tr->seq = pd->seq;
          tr->sa_seq = sa0->last_seq;
          tr->sa_seq_hi = sa0->seq_hi;
        }

      /* next */
      n_left -= 1;
      next += 1;
      pd += 1;
      pd2 += 1;
      b += 1;
    }

  n_left = from_frame->n_vectors;
  vlib_node_increment_counter (vm, node->node_index,
                               ESP_DECRYPT_ERROR_RX_PKTS, n_left);

  vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);

  return n_left;
}

always_inline uword
esp_decrypt_post_inline (vlib_main_t * vm,
                         vlib_node_runtime_t * node,
                         vlib_frame_t * from_frame, int is_ip6, int is_tun)
{
  ipsec_main_t *im = &ipsec_main;
  u32 *from = vlib_frame_vector_args (from_frame);
  u32 n_left = from_frame->n_vectors;
  vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
  u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
  vlib_get_buffers (vm, from, b, n_left);

  while (n_left > 0)
    {
      esp_decrypt_packet_data_t *pd = &(esp_post_data (b[0]))->decrypt_data;

      if (n_left > 2)
        {
          vlib_prefetch_buffer_header (b[2], LOAD);
          vlib_prefetch_buffer_header (b[1], LOAD);
        }

      if (!pd->is_chain)
        esp_decrypt_post_crypto (vm, node, pd, 0, b[0], next, is_ip6, is_tun,
                                 1);
      else
        {
          esp_decrypt_packet_data2_t *pd2 = esp_post_data2 (b[0]);
          esp_decrypt_post_crypto (vm, node, pd, pd2, b[0], next, is_ip6,
                                   is_tun, 1);
        }

      /*trace: */
      if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
        {
          ipsec_sa_t *sa0 = pool_elt_at_index (im->sad, pd->sa_index);
          esp_decrypt_trace_t *tr;
          esp_decrypt_packet_data_t *async_pd =
            &(esp_post_data (b[0]))->decrypt_data;
          tr = vlib_add_trace (vm, node, b[0], sizeof (*tr));
          sa0 = pool_elt_at_index (im->sad, async_pd->sa_index);

          tr->crypto_alg = sa0->crypto_alg;
          tr->integ_alg = sa0->integ_alg;
          tr->seq = pd->seq;
          tr->sa_seq = sa0->last_seq;
          tr->sa_seq_hi = sa0->seq_hi;
        }

      n_left--;
      next++;
      b++;
    }

  n_left = from_frame->n_vectors;
  vlib_node_increment_counter (vm, node->node_index,
                               ESP_DECRYPT_ERROR_RX_POST_PKTS, n_left);

  vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left);

  return n_left;
}

VLIB_NODE_FN (esp4_decrypt_node) (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * from_frame)
{
  return esp_decrypt_inline (vm, node, from_frame, 0, 0,
                             esp_decrypt_async_next.esp4_post_next);
}

VLIB_NODE_FN (esp4_decrypt_post_node) (vlib_main_t * vm,
                                       vlib_node_runtime_t * node,
                                       vlib_frame_t * from_frame)
{
  return esp_decrypt_post_inline (vm, node, from_frame, 0, 0);
}

VLIB_NODE_FN (esp4_decrypt_tun_node) (vlib_main_t * vm,
                                      vlib_node_runtime_t * node,
                                      vlib_frame_t * from_frame)
{
  return esp_decrypt_inline (vm, node, from_frame, 0, 1,
                             esp_decrypt_async_next.esp4_tun_post_next);
}

VLIB_NODE_FN (esp4_decrypt_tun_post_node) (vlib_main_t * vm,
                                           vlib_node_runtime_t * node,
                                           vlib_frame_t * from_frame)
{
  return esp_decrypt_post_inline (vm, node, from_frame, 0, 1);
}

VLIB_NODE_FN (esp6_decrypt_node) (vlib_main_t * vm,
                                  vlib_node_runtime_t * node,
                                  vlib_frame_t * from_frame)
{
  return esp_decrypt_inline (vm, node, from_frame, 1, 0,
                             esp_decrypt_async_next.esp6_post_next);
}

VLIB_NODE_FN (esp6_decrypt_post_node) (vlib_main_t * vm,
                                       vlib_node_runtime_t * node,
                                       vlib_frame_t * from_frame)
{
  return esp_decrypt_post_inline (vm, node, from_frame, 1, 0);
}

VLIB_NODE_FN (esp6_decrypt_tun_node) (vlib_main_t * vm,
                                      vlib_node_runtime_t * node,
                                      vlib_frame_t * from_frame)
{
  return esp_decrypt_inline (vm, node, from_frame, 1, 1,
                             esp_decrypt_async_next.esp6_tun_post_next);
}

VLIB_NODE_FN (esp6_decrypt_tun_post_node) (vlib_main_t * vm,
                                           vlib_node_runtime_t * node,
                                           vlib_frame_t * from_frame)
{
  return esp_decrypt_post_inline (vm, node, from_frame, 1, 1);
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (esp4_decrypt_node) = {
  .name = "esp4-decrypt",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = ESP_DECRYPT_N_NEXT,
  .next_nodes = {
    [ESP_DECRYPT_NEXT_DROP] = "ip4-drop",
    [ESP_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
    [ESP_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
    [ESP_DECRYPT_NEXT_L2_INPUT] = "l2-input",
    [ESP_DECRYPT_NEXT_HANDOFF] = "esp4-decrypt-handoff",
  },
};

VLIB_REGISTER_NODE (esp4_decrypt_post_node) = {
  .name = "esp4-decrypt-post",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .sibling_of = "esp4-decrypt",
};

VLIB_REGISTER_NODE (esp6_decrypt_node) = {
  .name = "esp6-decrypt",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = ESP_DECRYPT_N_NEXT,
  .next_nodes = {
    [ESP_DECRYPT_NEXT_DROP] = "ip6-drop",
    [ESP_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
    [ESP_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
    [ESP_DECRYPT_NEXT_L2_INPUT] = "l2-input",
    [ESP_DECRYPT_NEXT_HANDOFF]=  "esp6-decrypt-handoff",
  },
};

VLIB_REGISTER_NODE (esp6_decrypt_post_node) = {
  .name = "esp6-decrypt-post",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .sibling_of = "esp6-decrypt",
};

VLIB_REGISTER_NODE (esp4_decrypt_tun_node) = {
  .name = "esp4-decrypt-tun",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
  .error_strings = esp_decrypt_error_strings,
  .n_next_nodes = ESP_DECRYPT_N_NEXT,
  .next_nodes = {
    [ESP_DECRYPT_NEXT_DROP] = "ip4-drop",
    [ESP_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
    [ESP_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
    [ESP_DECRYPT_NEXT_L2_INPUT] = "l2-input",
    [ESP_DECRYPT_NEXT_HANDOFF] = "esp4-decrypt-tun-handoff",
  },
};

VLIB_REGISTER_NODE (esp4_decrypt_tun_post_node) = {
  .name = "esp4-decrypt-tun-post",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .sibling_of = "esp4-decrypt-tun",
};

VLIB_REGISTER_NODE (esp6_decrypt_tun_node) = {
  .name = "esp6-decrypt-tun",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
  .error_strings = esp_decrypt_error_strings,
  .n_next_nodes = ESP_DECRYPT_N_NEXT,
  .next_nodes = {
    [ESP_DECRYPT_NEXT_DROP] = "ip6-drop",
    [ESP_DECRYPT_NEXT_IP4_INPUT] = "ip4-input-no-checksum",
    [ESP_DECRYPT_NEXT_IP6_INPUT] = "ip6-input",
    [ESP_DECRYPT_NEXT_L2_INPUT] = "l2-input",
    [ESP_DECRYPT_NEXT_HANDOFF]=  "esp6-decrypt-tun-handoff",
  },
};

VLIB_REGISTER_NODE (esp6_decrypt_tun_post_node) = {
  .name = "esp6-decrypt-tun-post",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_decrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .sibling_of = "esp6-decrypt-tun",
};
/* *INDENT-ON* */

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