src/vnet/ipsec/esp_decrypt.c - fdio/vpp - Gitiles

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

 #include <vnet/gre/gre.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_error                               \
  _(RX_PKTS, "ESP 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")                                   \
  _(CHAINED_BUFFER, "chained 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;
 }

 typedef struct
 {
   union
   {
     struct
     {
       u8 icv_sz;
       u8 iv_sz;
       ipsec_sa_flags_t flags;
       u32 sa_index;
     };
     u64 sa_data;
   };

   u32 seq;
   i16 current_data;
   i16 current_length;
   u16 hdr_sz;
 } esp_decrypt_packet_data_t;

 STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 3 * sizeof (u64));

 #define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2)

 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)
 {
   ipsec_main_t *im = &ipsec_main;
   u32 thread_index = vm->thread_index;
   u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
   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, 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_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;

   vlib_get_buffers (vm, from, b, n_left);
   vec_reset_length (ptd->crypto_ops);
   vec_reset_length (ptd->integ_ops);
   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);
 	}

       if (vlib_buffer_chain_linearize (vm, b[0]) != 1)
 	{
 	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_CHAINED_BUFFER];
 	  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);
 	  cpd.icv_sz = sa0->integ_icv_size;
 	  cpd.iv_sz = sa0->crypto_iv_size;
 	  cpd.flags = sa0->flags;
 	  cpd.sa_index = current_sa_index;
 	}

       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_TRUE (thread_index != sa0->decrypt_thread_index))
 	{
 	  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->current_length = b[0]->current_length;
       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);

       /* we need 4 extra bytes for HMAC calculation when ESN are used */
       if (ipsec_sa_is_set_USE_ESN (sa0) && pd->icv_sz &&
 	  (pd->current_data + pd->current_length + 4 > buffer_data_size))
 	{
 	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_TAIL_SPACE];
 	  next[0] = ESP_DECRYPT_NEXT_DROP;
 	  goto next;
 	}

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

       if (pd->current_length < cpd.icv_sz + esp_sz + cpd.iv_sz)
 	{
 	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_RUNT];
 	  next[0] = ESP_DECRYPT_NEXT_DROP;
 	  goto next;
 	}

       len = pd->current_length - cpd.icv_sz;
       current_sa_pkts += 1;
       current_sa_bytes += pd->current_length;

       if (PREDICT_TRUE (sa0->integ_op_id != VNET_CRYPTO_OP_NONE))
 	{
 	  vnet_crypto_op_t *op;
 	  vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);

 	  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 = b - bufs;
 	  op->digest = payload + len;
 	  op->digest_len = cpd.icv_sz;
 	  op->len = len;
 	  if (ipsec_sa_is_set_USE_ESN (sa0))
 	    {
 	      /* shift ICV by 4 bytes to insert ESN */
 	      u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
 	      u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi);
 	      clib_memcpy_fast (tmp, payload + len, ESP_MAX_ICV_SIZE);
 	      clib_memcpy_fast (payload + len, &seq_hi, sz);
 	      clib_memcpy_fast (payload + len + sz, tmp, ESP_MAX_ICV_SIZE);
 	      op->len += sz;
 	      op->digest += sz;
 	    }
 	}

       payload += esp_sz;
       len -= esp_sz;

       if (sa0->crypto_enc_op_id != VNET_CRYPTO_OP_NONE)
 	{
 	  vnet_crypto_op_t *op;
 	  vec_add2_aligned (ptd->crypto_ops, op, 1, CLIB_CACHE_LINE_BYTES);
 	  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;

 	      esp_aad_fill (op, 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 += cpd.iv_sz;
 	  op->len = len - cpd.iv_sz;
 	  op->user_data = b - bufs;
 	}

       /* next */
     next:
       n_left -= 1;
       next += 1;
       pd += 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 ((n = vec_len (ptd->integ_ops)))
     {
       vnet_crypto_op_t *op = ptd->integ_ops;
       n -= vnet_crypto_process_ops (vm, op, n);
       while (n)
 	{
 	  ASSERT (op - ptd->integ_ops < vec_len (ptd->integ_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 = ESP_DECRYPT_ERROR_INTEG_ERROR;
 	      else
 		err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
 	      bufs[bi]->error = node->errors[err];
 	      nexts[bi] = ESP_DECRYPT_NEXT_DROP;
 	      n--;
 	    }
 	  op++;
 	}
     }
   if ((n = vec_len (ptd->crypto_ops)))
     {
       vnet_crypto_op_t *op = ptd->crypto_ops;
       n -= vnet_crypto_process_ops (vm, op, n);
       while (n)
 	{
 	  ASSERT (op - ptd->crypto_ops < vec_len (ptd->crypto_ops));
 	  if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
 	    {
 	      u32 err, bi;

 	      bi = op->user_data;

 	      if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
 		err = ESP_DECRYPT_ERROR_DECRYPTION_FAILED;
 	      else
 		err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;

 	      bufs[bi]->error = node->errors[err];
 	      nexts[bi] = ESP_DECRYPT_NEXT_DROP;
 	      n--;
 	    }
 	  op++;
 	}
     }

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

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

   while (n_left)
     {
       const u8 tun_flags = IPSEC_SA_FLAG_IS_TUNNEL |
 	IPSEC_SA_FLAG_IS_TUNNEL_V6;

       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);
 	}

       if (next[0] < ESP_DECRYPT_N_NEXT)
 	goto trace;

       sa0 = vec_elt_at_index (im->sad, pd->sa_index);

       /*
        * 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[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
 	  next[0] = ESP_DECRYPT_NEXT_DROP;
 	  goto trace;
 	}

       ipsec_sa_anti_replay_advance (sa0, pd->seq);

       esp_footer_t *f = (esp_footer_t *) (b[0]->data + pd->current_data +
 					  pd->current_length - sizeof (*f) -
 					  pd->icv_sz);
       u16 adv = pd->iv_sz + esp_sz;
       u16 tail = sizeof (esp_footer_t) + f->pad_length + pd->icv_sz;

       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[0]->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[0]->current_data = pd->current_data + adv - ip_hdr_sz;
 	  b[0]->current_length = pd->current_length + ip_hdr_sz - tail - adv;

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

 		  b[0]->current_data = pd->current_data + adv;
 		  b[0]->current_length = pd->current_length - adv - tail;

 		  gre = vlib_buffer_get_current (b[0]);

 		  vlib_buffer_advance (b[0], sizeof (*gre));

 		  switch (clib_net_to_host_u16 (gre->protocol))
 		    {
 		    case GRE_PROTOCOL_teb:
 		      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[0]->error =
 			node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
 		      next[0] = ESP_DECRYPT_NEXT_DROP;
 		      break;
 		    }
 		}
 	      else
 		{
 		  next[0] = ESP_DECRYPT_NEXT_DROP;
 		  b[0]->error = node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
 		  goto trace;
 		}
 	    }
 	  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;

 		  itp = ipsec_tun_protect_get
 		    (vnet_buffer (b[0])->ipsec.protect_index);

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

 		      ip4 = vlib_buffer_get_current (b[0]);

 		      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[0]->error =
 			    node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
 			}
 		    }
 		  else if (f->next_header == IP_PROTOCOL_IPV6)
 		    {
 		      const ip6_header_t *ip6;

 		      ip6 = vlib_buffer_get_current (b[0]);

 		      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[0]->error =
 			    node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
 			}
 		    }
 		}
 	    }
 	}

     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,
 				   vnet_buffer (b[0])->ipsec.sad_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;
       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);

   b = bufs;
   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);
 }

 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);
 }

 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);
 }

 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);
 }

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

 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* 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/ipsec/ipsec.h>
	#include <vnet/ipsec/esp.h>
	#include <vnet/ipsec/ipsec_io.h>
	#include <vnet/ipsec/ipsec_tun.h>

	#include <vnet/gre/gre.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_error \
	_(RX_PKTS, "ESP 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") \
	_(CHAINED_BUFFER, "chained 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;
	}

	typedef struct
	{
	union
	{
	struct
	{
	u8 icv_sz;
	u8 iv_sz;
	ipsec_sa_flags_t flags;
	u32 sa_index;
	};
	u64 sa_data;
	};

	u32 seq;
	i16 current_data;
	i16 current_length;
	u16 hdr_sz;
	} esp_decrypt_packet_data_t;

	STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 3 * sizeof (u64));

	#define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2)

	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)
	{
	ipsec_main_t *im = &ipsec_main;
	u32 thread_index = vm->thread_index;
	u16 buffer_data_size = vlib_buffer_get_default_data_size (vm);
	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, 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_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;

	vlib_get_buffers (vm, from, b, n_left);
	vec_reset_length (ptd->crypto_ops);
	vec_reset_length (ptd->integ_ops);
	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);
	}

	if (vlib_buffer_chain_linearize (vm, b[0]) != 1)
	{
	b[0]->error = node->errors[ESP_DECRYPT_ERROR_CHAINED_BUFFER];
	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);
	cpd.icv_sz = sa0->integ_icv_size;
	cpd.iv_sz = sa0->crypto_iv_size;
	cpd.flags = sa0->flags;
	cpd.sa_index = current_sa_index;
	}

	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_TRUE (thread_index != sa0->decrypt_thread_index))
	{
	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->current_length = b[0]->current_length;
	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);

	/* we need 4 extra bytes for HMAC calculation when ESN are used */
	if (ipsec_sa_is_set_USE_ESN (sa0) && pd->icv_sz &&
	(pd->current_data + pd->current_length + 4 > buffer_data_size))
	{
	b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_TAIL_SPACE];
	next[0] = ESP_DECRYPT_NEXT_DROP;
	goto next;
	}

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

	if (pd->current_length < cpd.icv_sz + esp_sz + cpd.iv_sz)
	{
	b[0]->error = node->errors[ESP_DECRYPT_ERROR_RUNT];
	next[0] = ESP_DECRYPT_NEXT_DROP;
	goto next;
	}

	len = pd->current_length - cpd.icv_sz;
	current_sa_pkts += 1;
	current_sa_bytes += pd->current_length;

	if (PREDICT_TRUE (sa0->integ_op_id != VNET_CRYPTO_OP_NONE))
	{
	vnet_crypto_op_t *op;
	vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES);

	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 = b - bufs;
	op->digest = payload + len;
	op->digest_len = cpd.icv_sz;
	op->len = len;
	if (ipsec_sa_is_set_USE_ESN (sa0))
	{
	/* shift ICV by 4 bytes to insert ESN */
	u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
	u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi);
	clib_memcpy_fast (tmp, payload + len, ESP_MAX_ICV_SIZE);
	clib_memcpy_fast (payload + len, &seq_hi, sz);
	clib_memcpy_fast (payload + len + sz, tmp, ESP_MAX_ICV_SIZE);
	op->len += sz;
	op->digest += sz;
	}
	}

	payload += esp_sz;
	len -= esp_sz;

	if (sa0->crypto_enc_op_id != VNET_CRYPTO_OP_NONE)
	{
	vnet_crypto_op_t *op;
	vec_add2_aligned (ptd->crypto_ops, op, 1, CLIB_CACHE_LINE_BYTES);
	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;

	esp_aad_fill (op, 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 += cpd.iv_sz;
	op->len = len - cpd.iv_sz;
	op->user_data = b - bufs;
	}

	/* next */
	next:
	n_left -= 1;
	next += 1;
	pd += 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 ((n = vec_len (ptd->integ_ops)))
	{
	vnet_crypto_op_t *op = ptd->integ_ops;
	n -= vnet_crypto_process_ops (vm, op, n);
	while (n)
	{
	ASSERT (op - ptd->integ_ops < vec_len (ptd->integ_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 = ESP_DECRYPT_ERROR_INTEG_ERROR;
	else
	err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;
	bufs[bi]->error = node->errors[err];
	nexts[bi] = ESP_DECRYPT_NEXT_DROP;
	n--;
	}
	op++;
	}
	}
	if ((n = vec_len (ptd->crypto_ops)))
	{
	vnet_crypto_op_t *op = ptd->crypto_ops;
	n -= vnet_crypto_process_ops (vm, op, n);
	while (n)
	{
	ASSERT (op - ptd->crypto_ops < vec_len (ptd->crypto_ops));
	if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED)
	{
	u32 err, bi;

	bi = op->user_data;

	if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC)
	err = ESP_DECRYPT_ERROR_DECRYPTION_FAILED;
	else
	err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR;

	bufs[bi]->error = node->errors[err];
	nexts[bi] = ESP_DECRYPT_NEXT_DROP;
	n--;
	}
	op++;
	}
	}

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

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

	while (n_left)
	{
	const u8 tun_flags = IPSEC_SA_FLAG_IS_TUNNEL \|
	IPSEC_SA_FLAG_IS_TUNNEL_V6;

	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);
	}

	if (next[0] < ESP_DECRYPT_N_NEXT)
	goto trace;

	sa0 = vec_elt_at_index (im->sad, pd->sa_index);

	/*
	* 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[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
	next[0] = ESP_DECRYPT_NEXT_DROP;
	goto trace;
	}

	ipsec_sa_anti_replay_advance (sa0, pd->seq);

	esp_footer_t f = (esp_footer_t ) (b[0]->data + pd->current_data +
	pd->current_length - sizeof (*f) -
	pd->icv_sz);
	u16 adv = pd->iv_sz + esp_sz;
	u16 tail = sizeof (esp_footer_t) + f->pad_length + pd->icv_sz;

	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[0]->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[0]->current_data = pd->current_data + adv - ip_hdr_sz;
	b[0]->current_length = pd->current_length + ip_hdr_sz - tail - adv;

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

	b[0]->current_data = pd->current_data + adv;
	b[0]->current_length = pd->current_length - adv - tail;

	gre = vlib_buffer_get_current (b[0]);

	vlib_buffer_advance (b[0], sizeof (*gre));

	switch (clib_net_to_host_u16 (gre->protocol))
	{
	case GRE_PROTOCOL_teb:
	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[0]->error =
	node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
	next[0] = ESP_DECRYPT_NEXT_DROP;
	break;
	}
	}
	else
	{
	next[0] = ESP_DECRYPT_NEXT_DROP;
	b[0]->error = node->errors[ESP_DECRYPT_ERROR_UNSUP_PAYLOAD];
	goto trace;
	}
	}
	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;

	itp = ipsec_tun_protect_get
	(vnet_buffer (b[0])->ipsec.protect_index);

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

	ip4 = vlib_buffer_get_current (b[0]);

	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[0]->error =
	node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
	}
	}
	else if (f->next_header == IP_PROTOCOL_IPV6)
	{
	const ip6_header_t *ip6;

	ip6 = vlib_buffer_get_current (b[0]);

	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[0]->error =
	node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
	}
	}
	}
	}
	}

	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,
	vnet_buffer (b[0])->ipsec.sad_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;
	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);

	b = bufs;
	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);
	}

	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);
	}

	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);
	}

	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);
	}

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

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