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>

 #define foreach_esp_decrypt_next                \
 _(DROP, "error-drop")                           \
 _(IP4_INPUT, "ip4-input")                       \
 _(IP6_INPUT, "ip6-input")                       \
 _(IPSEC_GRE_INPUT, "ipsec-gre-input")

 #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")                    \
  _(NO_BUFFER, "No buffer (packed dropped)")         \
  _(DECRYPTION_FAILED, "ESP decryption failed")      \
  _(INTEG_ERROR, "Integrity check failed")           \
  _(REPLAY, "SA replayed packet")                    \
  _(NOT_IP, "Not IP packet (dropped)")


 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
 {
   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",
 	      format_ipsec_crypto_alg, t->crypto_alg,
 	      format_ipsec_integ_alg, t->integ_alg);
   return s;
 }

 always_inline void
 esp_decrypt_aes_cbc (ipsec_crypto_alg_t alg,
 		     u8 * in, u8 * out, size_t in_len, u8 * key, u8 * iv)
 {
   esp_main_t *em = &esp_main;
   u32 cpu_index = os_get_cpu_number ();
   EVP_CIPHER_CTX *ctx = &(em->per_thread_data[cpu_index].decrypt_ctx);
   const EVP_CIPHER *cipher = NULL;
   int out_len;

   ASSERT (alg < IPSEC_CRYPTO_N_ALG);

   if (PREDICT_FALSE (em->esp_crypto_algs[alg].type == 0))
     return;

   if (PREDICT_FALSE (alg != em->per_thread_data[cpu_index].last_decrypt_alg))
     {
       cipher = em->esp_crypto_algs[alg].type;
       em->per_thread_data[cpu_index].last_decrypt_alg = alg;
     }

   EVP_DecryptInit_ex (ctx, cipher, NULL, key, iv);

   EVP_DecryptUpdate (ctx, out, &out_len, in, in_len);
   EVP_DecryptFinal_ex (ctx, out + out_len, &out_len);
 }

 static uword
 esp_decrypt_node_fn (vlib_main_t * vm,
 		     vlib_node_runtime_t * node, vlib_frame_t * from_frame)
 {
   u32 n_left_from, *from, next_index, *to_next;
   ipsec_main_t *im = &ipsec_main;
   esp_main_t *em = &esp_main;
   u32 *recycle = 0;
   from = vlib_frame_vector_args (from_frame);
   n_left_from = from_frame->n_vectors;
   u32 cpu_index = os_get_cpu_number ();

   ipsec_alloc_empty_buffers (vm, im);

   u32 *empty_buffers = im->empty_buffers[cpu_index];

   if (PREDICT_FALSE (vec_len (empty_buffers) < n_left_from))
     {
       vlib_node_increment_counter (vm, esp_decrypt_node.index,
 				   ESP_DECRYPT_ERROR_NO_BUFFER, n_left_from);
       goto free_buffers_and_exit;
     }

   next_index = node->cached_next_index;

   while (n_left_from > 0)
     {
       u32 n_left_to_next;

       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

       while (n_left_from > 0 && n_left_to_next > 0)
 	{
 	  u32 i_bi0, o_bi0 = (u32) ~ 0, next0;
 	  vlib_buffer_t *i_b0;
 	  vlib_buffer_t *o_b0 = 0;
 	  esp_header_t *esp0;
 	  ipsec_sa_t *sa0;
 	  u32 sa_index0 = ~0;
 	  u32 seq;
 	  ip4_header_t *ih4 = 0, *oh4 = 0;
 	  ip6_header_t *ih6 = 0, *oh6 = 0;
 	  u8 tunnel_mode = 1;
 	  u8 transport_ip6 = 0;


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

 	  next0 = ESP_DECRYPT_NEXT_DROP;

 	  i_b0 = vlib_get_buffer (vm, i_bi0);
 	  esp0 = vlib_buffer_get_current (i_b0);

 	  sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
 	  sa0 = pool_elt_at_index (im->sad, sa_index0);

 	  seq = clib_host_to_net_u32 (esp0->seq);

 	  /* anti-replay check */
 	  if (sa0->use_anti_replay)
 	    {
 	      int rv = 0;

 	      if (PREDICT_TRUE (sa0->use_esn))
 		rv = esp_replay_check_esn (sa0, seq);
 	      else
 		rv = esp_replay_check (sa0, seq);

 	      if (PREDICT_FALSE (rv))
 		{
 		  clib_warning ("anti-replay SPI %u seq %u", sa0->spi, seq);
 		  vlib_node_increment_counter (vm, esp_decrypt_node.index,
 					       ESP_DECRYPT_ERROR_REPLAY, 1);
 		  o_bi0 = i_bi0;
 		  to_next[0] = o_bi0;
 		  to_next += 1;
 		  goto trace;
 		}
 	    }

 	  sa0->total_data_size += i_b0->current_length;

 	  if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 	    {
 	      u8 sig[64];
 	      int icv_size = em->esp_integ_algs[sa0->integ_alg].trunc_size;
 	      memset (sig, 0, sizeof (sig));
 	      u8 *icv =
 		vlib_buffer_get_current (i_b0) + i_b0->current_length -
 		icv_size;
 	      i_b0->current_length -= icv_size;

 	      hmac_calc (sa0->integ_alg, sa0->integ_key, sa0->integ_key_len,
 			 (u8 *) esp0, i_b0->current_length, sig, sa0->use_esn,
 			 sa0->seq_hi);

 	      if (PREDICT_FALSE (memcmp (icv, sig, icv_size)))
 		{
 		  vlib_node_increment_counter (vm, esp_decrypt_node.index,
 					       ESP_DECRYPT_ERROR_INTEG_ERROR,
 					       1);
 		  o_bi0 = i_bi0;
 		  to_next[0] = o_bi0;
 		  to_next += 1;
 		  goto trace;
 		}
 	    }

 	  if (PREDICT_TRUE (sa0->use_anti_replay))
 	    {
 	      if (PREDICT_TRUE (sa0->use_esn))
 		esp_replay_advance_esn (sa0, seq);
 	      else
 		esp_replay_advance (sa0, seq);
 	    }

 	  /* grab free buffer */
 	  uword last_empty_buffer = vec_len (empty_buffers) - 1;
 	  o_bi0 = empty_buffers[last_empty_buffer];
 	  to_next[0] = o_bi0;
 	  to_next += 1;
 	  o_b0 = vlib_get_buffer (vm, o_bi0);
 	  vlib_prefetch_buffer_with_index (vm,
 					   empty_buffers[last_empty_buffer -
 							 1], STORE);
 	  _vec_len (empty_buffers) = last_empty_buffer;

 	  /* add old buffer to the recycle list */
 	  vec_add1 (recycle, i_bi0);

 	  if (sa0->crypto_alg >= IPSEC_CRYPTO_ALG_AES_CBC_128 &&
 	      sa0->crypto_alg <= IPSEC_CRYPTO_ALG_AES_CBC_256)
 	    {
 	      const int BLOCK_SIZE = 16;
 	      const int IV_SIZE = 16;
 	      esp_footer_t *f0;
 	      u8 ip_hdr_size = 0;

 	      int blocks =
 		(i_b0->current_length - sizeof (esp_header_t) -
 		 IV_SIZE) / BLOCK_SIZE;

 	      o_b0->current_data = sizeof (ethernet_header_t);

 	      /* transport mode */
 	      if (PREDICT_FALSE (!sa0->is_tunnel && !sa0->is_tunnel_ip6))
 		{
 		  tunnel_mode = 0;
 		  ih4 =
 		    (ip4_header_t *) (i_b0->data +
 				      sizeof (ethernet_header_t));
 		  if (PREDICT_TRUE
 		      ((ih4->ip_version_and_header_length & 0xF0) != 0x40))
 		    {
 		      if (PREDICT_TRUE
 			  ((ih4->ip_version_and_header_length & 0xF0) ==
 			   0x60))
 			{
 			  transport_ip6 = 1;
 			  ip_hdr_size = sizeof (ip6_header_t);
 			  ih6 =
 			    (ip6_header_t *) (i_b0->data +
 					      sizeof (ethernet_header_t));
 			  oh6 = vlib_buffer_get_current (o_b0);
 			}
 		      else
 			{
 			  vlib_node_increment_counter (vm,
 						       esp_decrypt_node.index,
 						       ESP_DECRYPT_ERROR_NOT_IP,
 						       1);
 			  o_b0 = 0;
 			  goto trace;
 			}
 		    }
 		  else
 		    {
 		      oh4 = vlib_buffer_get_current (o_b0);
 		      ip_hdr_size = sizeof (ip4_header_t);
 		    }
 		}

 	      esp_decrypt_aes_cbc (sa0->crypto_alg,
 				   esp0->data + IV_SIZE,
 				   (u8 *) vlib_buffer_get_current (o_b0) +
 				   ip_hdr_size, BLOCK_SIZE * blocks,
 				   sa0->crypto_key, esp0->data);

 	      o_b0->current_length = (blocks * 16) - 2 + ip_hdr_size;
 	      o_b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
 	      f0 =
 		(esp_footer_t *) ((u8 *) vlib_buffer_get_current (o_b0) +
 				  o_b0->current_length);
 	      o_b0->current_length -= f0->pad_length;

 	      /* tunnel mode */
 	      if (PREDICT_TRUE (tunnel_mode))
 		{
 		  if (PREDICT_TRUE (f0->next_header == IP_PROTOCOL_IP_IN_IP))
 		    {
 		      next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
 		      oh4 = vlib_buffer_get_current (o_b0);
 		    }
 		  else if (f0->next_header == IP_PROTOCOL_IPV6)
 		    next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
 		  else
 		    {
 		      clib_warning ("next header: 0x%x", f0->next_header);
 		      vlib_node_increment_counter (vm, esp_decrypt_node.index,
 						   ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
 						   1);
 		      o_b0 = 0;
 		      goto trace;
 		    }
 		}
 	      /* transport mode */
 	      else
 		{
 		  if (PREDICT_FALSE (transport_ip6))
 		    {
 		      next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
 		      oh6->ip_version_traffic_class_and_flow_label =
 			ih6->ip_version_traffic_class_and_flow_label;
 		      oh6->protocol = f0->next_header;
 		      oh6->hop_limit = ih6->hop_limit;
 		      oh6->src_address.as_u64[0] = ih6->src_address.as_u64[0];
 		      oh6->src_address.as_u64[1] = ih6->src_address.as_u64[1];
 		      oh6->dst_address.as_u64[0] = ih6->dst_address.as_u64[0];
 		      oh6->dst_address.as_u64[1] = ih6->dst_address.as_u64[1];
 		      oh6->payload_length =
 			clib_host_to_net_u16 (vlib_buffer_length_in_chain
 					      (vm,
 					       o_b0) - sizeof (ip6_header_t));
 		    }
 		  else
 		    {
 		      next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
 		      oh4->ip_version_and_header_length = 0x45;
 		      oh4->tos = ih4->tos;
 		      oh4->fragment_id = 0;
 		      oh4->flags_and_fragment_offset = 0;
 		      oh4->ttl = ih4->ttl;
 		      oh4->protocol = f0->next_header;
 		      oh4->src_address.as_u32 = ih4->src_address.as_u32;
 		      oh4->dst_address.as_u32 = ih4->dst_address.as_u32;
 		      oh4->length =
 			clib_host_to_net_u16 (vlib_buffer_length_in_chain
 					      (vm, o_b0));
 		      oh4->checksum = ip4_header_checksum (oh4);
 		    }
 		}

 	      /* for IPSec-GRE tunnel next node is ipsec-gre-input */
 	      if (PREDICT_FALSE
 		  ((vnet_buffer (i_b0)->ipsec.flags) &
 		   IPSEC_FLAG_IPSEC_GRE_TUNNEL))
 		next0 = ESP_DECRYPT_NEXT_IPSEC_GRE_INPUT;

 	      vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 	    }

 	trace:
 	  if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
 	    {
 	      if (o_b0)
 		{
 		  o_b0->flags |= VLIB_BUFFER_IS_TRACED;
 		  o_b0->trace_index = i_b0->trace_index;
 		  esp_decrypt_trace_t *tr =
 		    vlib_add_trace (vm, node, o_b0, sizeof (*tr));
 		  tr->crypto_alg = sa0->crypto_alg;
 		  tr->integ_alg = sa0->integ_alg;
 		}
 	    }

 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
 					   n_left_to_next, o_bi0, next0);
 	}
       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }
   vlib_node_increment_counter (vm, esp_decrypt_node.index,
 			       ESP_DECRYPT_ERROR_RX_PKTS,
 			       from_frame->n_vectors);

 free_buffers_and_exit:
   if (recycle)
     vlib_buffer_free (vm, recycle, vec_len (recycle));
   vec_free (recycle);
   return from_frame->n_vectors;
 }


 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (esp_decrypt_node) = {
   .function = esp_decrypt_node_fn,
   .name = "esp-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 = {
 #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
     foreach_esp_decrypt_next
 #undef _
   },
 };
 /* *INDENT-ON* */

 VLIB_NODE_FUNCTION_MULTIARCH (esp_decrypt_node, esp_decrypt_node_fn)
 /*
  * 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>

	#define foreach_esp_decrypt_next \
	_(DROP, "error-drop") \
	_(IP4_INPUT, "ip4-input") \
	_(IP6_INPUT, "ip6-input") \
	_(IPSEC_GRE_INPUT, "ipsec-gre-input")

	#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") \
	_(NO_BUFFER, "No buffer (packed dropped)") \
	_(DECRYPTION_FAILED, "ESP decryption failed") \
	_(INTEG_ERROR, "Integrity check failed") \
	_(REPLAY, "SA replayed packet") \
	_(NOT_IP, "Not IP packet (dropped)")


	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
	{
	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",
	format_ipsec_crypto_alg, t->crypto_alg,
	format_ipsec_integ_alg, t->integ_alg);
	return s;
	}

	always_inline void
	esp_decrypt_aes_cbc (ipsec_crypto_alg_t alg,
	u8 * in, u8 * out, size_t in_len, u8 * key, u8 * iv)
	{
	esp_main_t *em = &esp_main;
	u32 cpu_index = os_get_cpu_number ();
	EVP_CIPHER_CTX *ctx = &(em->per_thread_data[cpu_index].decrypt_ctx);
	const EVP_CIPHER *cipher = NULL;
	int out_len;

	ASSERT (alg < IPSEC_CRYPTO_N_ALG);

	if (PREDICT_FALSE (em->esp_crypto_algs[alg].type == 0))
	return;

	if (PREDICT_FALSE (alg != em->per_thread_data[cpu_index].last_decrypt_alg))
	{
	cipher = em->esp_crypto_algs[alg].type;
	em->per_thread_data[cpu_index].last_decrypt_alg = alg;
	}

	EVP_DecryptInit_ex (ctx, cipher, NULL, key, iv);

	EVP_DecryptUpdate (ctx, out, &out_len, in, in_len);
	EVP_DecryptFinal_ex (ctx, out + out_len, &out_len);
	}

	static uword
	esp_decrypt_node_fn (vlib_main_t * vm,
	vlib_node_runtime_t * node, vlib_frame_t * from_frame)
	{
	u32 n_left_from, from, next_index, to_next;
	ipsec_main_t *im = &ipsec_main;
	esp_main_t *em = &esp_main;
	u32 *recycle = 0;
	from = vlib_frame_vector_args (from_frame);
	n_left_from = from_frame->n_vectors;
	u32 cpu_index = os_get_cpu_number ();

	ipsec_alloc_empty_buffers (vm, im);

	u32 *empty_buffers = im->empty_buffers[cpu_index];

	if (PREDICT_FALSE (vec_len (empty_buffers) < n_left_from))
	{
	vlib_node_increment_counter (vm, esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_NO_BUFFER, n_left_from);
	goto free_buffers_and_exit;
	}

	next_index = node->cached_next_index;

	while (n_left_from > 0)
	{
	u32 n_left_to_next;

	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	u32 i_bi0, o_bi0 = (u32) ~ 0, next0;
	vlib_buffer_t *i_b0;
	vlib_buffer_t *o_b0 = 0;
	esp_header_t *esp0;
	ipsec_sa_t *sa0;
	u32 sa_index0 = ~0;
	u32 seq;
	ip4_header_t ih4 = 0, oh4 = 0;
	ip6_header_t ih6 = 0, oh6 = 0;
	u8 tunnel_mode = 1;
	u8 transport_ip6 = 0;


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

	next0 = ESP_DECRYPT_NEXT_DROP;

	i_b0 = vlib_get_buffer (vm, i_bi0);
	esp0 = vlib_buffer_get_current (i_b0);

	sa_index0 = vnet_buffer (i_b0)->ipsec.sad_index;
	sa0 = pool_elt_at_index (im->sad, sa_index0);

	seq = clib_host_to_net_u32 (esp0->seq);

	/* anti-replay check */
	if (sa0->use_anti_replay)
	{
	int rv = 0;

	if (PREDICT_TRUE (sa0->use_esn))
	rv = esp_replay_check_esn (sa0, seq);
	else
	rv = esp_replay_check (sa0, seq);

	if (PREDICT_FALSE (rv))
	{
	clib_warning ("anti-replay SPI %u seq %u", sa0->spi, seq);
	vlib_node_increment_counter (vm, esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_REPLAY, 1);
	o_bi0 = i_bi0;
	to_next[0] = o_bi0;
	to_next += 1;
	goto trace;
	}
	}

	sa0->total_data_size += i_b0->current_length;

	if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
	{
	u8 sig[64];
	int icv_size = em->esp_integ_algs[sa0->integ_alg].trunc_size;
	memset (sig, 0, sizeof (sig));
	u8 *icv =
	vlib_buffer_get_current (i_b0) + i_b0->current_length -
	icv_size;
	i_b0->current_length -= icv_size;

	hmac_calc (sa0->integ_alg, sa0->integ_key, sa0->integ_key_len,
	(u8 *) esp0, i_b0->current_length, sig, sa0->use_esn,
	sa0->seq_hi);

	if (PREDICT_FALSE (memcmp (icv, sig, icv_size)))
	{
	vlib_node_increment_counter (vm, esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_INTEG_ERROR,
	1);
	o_bi0 = i_bi0;
	to_next[0] = o_bi0;
	to_next += 1;
	goto trace;
	}
	}

	if (PREDICT_TRUE (sa0->use_anti_replay))
	{
	if (PREDICT_TRUE (sa0->use_esn))
	esp_replay_advance_esn (sa0, seq);
	else
	esp_replay_advance (sa0, seq);
	}

	/* grab free buffer */
	uword last_empty_buffer = vec_len (empty_buffers) - 1;
	o_bi0 = empty_buffers[last_empty_buffer];
	to_next[0] = o_bi0;
	to_next += 1;
	o_b0 = vlib_get_buffer (vm, o_bi0);
	vlib_prefetch_buffer_with_index (vm,
	empty_buffers[last_empty_buffer -
	1], STORE);
	_vec_len (empty_buffers) = last_empty_buffer;

	/* add old buffer to the recycle list */
	vec_add1 (recycle, i_bi0);

	if (sa0->crypto_alg >= IPSEC_CRYPTO_ALG_AES_CBC_128 &&
	sa0->crypto_alg <= IPSEC_CRYPTO_ALG_AES_CBC_256)
	{
	const int BLOCK_SIZE = 16;
	const int IV_SIZE = 16;
	esp_footer_t *f0;
	u8 ip_hdr_size = 0;

	int blocks =
	(i_b0->current_length - sizeof (esp_header_t) -
	IV_SIZE) / BLOCK_SIZE;

	o_b0->current_data = sizeof (ethernet_header_t);

	/* transport mode */
	if (PREDICT_FALSE (!sa0->is_tunnel && !sa0->is_tunnel_ip6))
	{
	tunnel_mode = 0;
	ih4 =
	(ip4_header_t *) (i_b0->data +
	sizeof (ethernet_header_t));
	if (PREDICT_TRUE
	((ih4->ip_version_and_header_length & 0xF0) != 0x40))
	{
	if (PREDICT_TRUE
	((ih4->ip_version_and_header_length & 0xF0) ==
	0x60))
	{
	transport_ip6 = 1;
	ip_hdr_size = sizeof (ip6_header_t);
	ih6 =
	(ip6_header_t *) (i_b0->data +
	sizeof (ethernet_header_t));
	oh6 = vlib_buffer_get_current (o_b0);
	}
	else
	{
	vlib_node_increment_counter (vm,
	esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_NOT_IP,
	1);
	o_b0 = 0;
	goto trace;
	}
	}
	else
	{
	oh4 = vlib_buffer_get_current (o_b0);
	ip_hdr_size = sizeof (ip4_header_t);
	}
	}

	esp_decrypt_aes_cbc (sa0->crypto_alg,
	esp0->data + IV_SIZE,
	(u8 *) vlib_buffer_get_current (o_b0) +
	ip_hdr_size, BLOCK_SIZE * blocks,
	sa0->crypto_key, esp0->data);

	o_b0->current_length = (blocks * 16) - 2 + ip_hdr_size;
	o_b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
	f0 =
	(esp_footer_t ) ((u8 ) vlib_buffer_get_current (o_b0) +
	o_b0->current_length);
	o_b0->current_length -= f0->pad_length;

	/* tunnel mode */
	if (PREDICT_TRUE (tunnel_mode))
	{
	if (PREDICT_TRUE (f0->next_header == IP_PROTOCOL_IP_IN_IP))
	{
	next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
	oh4 = vlib_buffer_get_current (o_b0);
	}
	else if (f0->next_header == IP_PROTOCOL_IPV6)
	next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
	else
	{
	clib_warning ("next header: 0x%x", f0->next_header);
	vlib_node_increment_counter (vm, esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_DECRYPTION_FAILED,
	1);
	o_b0 = 0;
	goto trace;
	}
	}
	/* transport mode */
	else
	{
	if (PREDICT_FALSE (transport_ip6))
	{
	next0 = ESP_DECRYPT_NEXT_IP6_INPUT;
	oh6->ip_version_traffic_class_and_flow_label =
	ih6->ip_version_traffic_class_and_flow_label;
	oh6->protocol = f0->next_header;
	oh6->hop_limit = ih6->hop_limit;
	oh6->src_address.as_u64[0] = ih6->src_address.as_u64[0];
	oh6->src_address.as_u64[1] = ih6->src_address.as_u64[1];
	oh6->dst_address.as_u64[0] = ih6->dst_address.as_u64[0];
	oh6->dst_address.as_u64[1] = ih6->dst_address.as_u64[1];
	oh6->payload_length =
	clib_host_to_net_u16 (vlib_buffer_length_in_chain
	(vm,
	o_b0) - sizeof (ip6_header_t));
	}
	else
	{
	next0 = ESP_DECRYPT_NEXT_IP4_INPUT;
	oh4->ip_version_and_header_length = 0x45;
	oh4->tos = ih4->tos;
	oh4->fragment_id = 0;
	oh4->flags_and_fragment_offset = 0;
	oh4->ttl = ih4->ttl;
	oh4->protocol = f0->next_header;
	oh4->src_address.as_u32 = ih4->src_address.as_u32;
	oh4->dst_address.as_u32 = ih4->dst_address.as_u32;
	oh4->length =
	clib_host_to_net_u16 (vlib_buffer_length_in_chain
	(vm, o_b0));
	oh4->checksum = ip4_header_checksum (oh4);
	}
	}

	/* for IPSec-GRE tunnel next node is ipsec-gre-input */
	if (PREDICT_FALSE
	((vnet_buffer (i_b0)->ipsec.flags) &
	IPSEC_FLAG_IPSEC_GRE_TUNNEL))
	next0 = ESP_DECRYPT_NEXT_IPSEC_GRE_INPUT;

	vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
	}

	trace:
	if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
	{
	if (o_b0)
	{
	o_b0->flags \|= VLIB_BUFFER_IS_TRACED;
	o_b0->trace_index = i_b0->trace_index;
	esp_decrypt_trace_t *tr =
	vlib_add_trace (vm, node, o_b0, sizeof (*tr));
	tr->crypto_alg = sa0->crypto_alg;
	tr->integ_alg = sa0->integ_alg;
	}
	}

	vlib_validate_buffer_enqueue_x1 (vm, node, next_index, to_next,
	n_left_to_next, o_bi0, next0);
	}
	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}
	vlib_node_increment_counter (vm, esp_decrypt_node.index,
	ESP_DECRYPT_ERROR_RX_PKTS,
	from_frame->n_vectors);

	free_buffers_and_exit:
	if (recycle)
	vlib_buffer_free (vm, recycle, vec_len (recycle));
	vec_free (recycle);
	return from_frame->n_vectors;
	}


	/* INDENT-OFF */
	VLIB_REGISTER_NODE (esp_decrypt_node) = {
	.function = esp_decrypt_node_fn,
	.name = "esp-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 = {
	#define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
	foreach_esp_decrypt_next
	#undef _
	},
	};
	/* INDENT-ON */

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