ipsec: huge anti-replay window support

Type: improvement

Since RFC4303 does not specify the anti-replay window size, VPP should
support multiple window size. It is done through a clib_bitmap.

Signed-off-by: Maxime Peim <mpeim@cisco.com>
Change-Id: I3dfe30efd20018e345418bef298ec7cec19b1cfc

10 files changed, 680 insertions, 168 deletions

diff --git a/src/vnet/ipsec/ah_decrypt.c b/src/vnet/ipsec/ah_decrypt.c
index 5f98693204a..62a6b706362 100644
--- a/src/vnet/ipsec/ah_decrypt.c
+++ b/src/vnet/ipsec/ah_decrypt.c
@@ -128,6 +128,7 @@ ah_decrypt_inline (vlib_main_t * vm,
   from = vlib_frame_vector_args (from_frame);
   n_left = from_frame->n_vectors;
   ipsec_sa_t *sa0 = 0;
+  bool anti_replay_result;
   u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0;
 
   clib_memset (pkt_data, 0, VLIB_FRAME_SIZE * sizeof (pkt_data[0]));
@@ -201,8 +202,17 @@ ah_decrypt_inline (vlib_main_t * vm,
       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 
       /* anti-replay check */
-      if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, ~0, false,
-					       &pd->seq_hi))
+      if (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa0)))
+	{
+	  anti_replay_result = ipsec_sa_anti_replay_and_sn_advance (
+	    sa0, pd->seq, ~0, false, &pd->seq_hi, true);
+	}
+      else
+	{
+	  anti_replay_result = ipsec_sa_anti_replay_and_sn_advance (
+	    sa0, pd->seq, ~0, false, &pd->seq_hi, false);
+	}
+      if (anti_replay_result)
 	{
 	  ah_decrypt_set_next_index (b[0], node, vm->thread_index,
 				     AH_DECRYPT_ERROR_REPLAY, 0, next,
@@ -306,16 +316,32 @@ ah_decrypt_inline (vlib_main_t * vm,
       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 	{
 	  /* redo the anti-reply check. see esp_decrypt for details */
-	  if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, pd->seq_hi,
-						   true, NULL))
+	  if (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa0)))
 	    {
-	      ah_decrypt_set_next_index (b[0], node, vm->thread_index,
-					 AH_DECRYPT_ERROR_REPLAY, 0, next,
-					 AH_DECRYPT_NEXT_DROP, pd->sa_index);
-	      goto trace;
+	      if (ipsec_sa_anti_replay_and_sn_advance (
+		    sa0, pd->seq, pd->seq_hi, true, NULL, true))
+		{
+		  ah_decrypt_set_next_index (
+		    b[0], node, vm->thread_index, AH_DECRYPT_ERROR_REPLAY, 0,
+		    next, AH_DECRYPT_NEXT_DROP, pd->sa_index);
+		  goto trace;
+		}
+	      n_lost = ipsec_sa_anti_replay_advance (
+		sa0, thread_index, pd->seq, pd->seq_hi, true);
+	    }
+	  else
+	    {
+	      if (ipsec_sa_anti_replay_and_sn_advance (
+		    sa0, pd->seq, pd->seq_hi, true, NULL, false))
+		{
+		  ah_decrypt_set_next_index (
+		    b[0], node, vm->thread_index, AH_DECRYPT_ERROR_REPLAY, 0,
+		    next, AH_DECRYPT_NEXT_DROP, pd->sa_index);
+		  goto trace;
+		}
+	      n_lost = ipsec_sa_anti_replay_advance (
+		sa0, thread_index, pd->seq, pd->seq_hi, false);
 	    }
-	  n_lost = ipsec_sa_anti_replay_advance (sa0, thread_index, pd->seq,
-						 pd->seq_hi);
 	  vlib_prefetch_simple_counter (
 	    &ipsec_sa_err_counters[IPSEC_SA_ERROR_LOST], thread_index,
 	    pd->sa_index);
diff --git a/src/vnet/ipsec/esp_decrypt.c b/src/vnet/ipsec/esp_decrypt.c
index 74410a8add1..7b74e6e2c67 100644
--- a/src/vnet/ipsec/esp_decrypt.c
+++ b/src/vnet/ipsec/esp_decrypt.c
@@ -745,6 +745,7 @@ esp_decrypt_post_crypto (vlib_main_t *vm, vlib_node_runtime_t *node,
   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;
+  u64 n_lost;
 
   /*
    * redo the anti-reply check
@@ -753,32 +754,47 @@ esp_decrypt_post_crypto (vlib_main_t *vm, vlib_node_runtime_t *node,
    * 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 time s will be cheked against Ws-1, s+1 checked against Ws
+   * (i.e. the window state is updated/advanced)
+   * so this time the successive s+1 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
+   * check-decrypt-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,
+   * above sequence and cause VPP to perform decrypts 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_and_sn_advance (sa0, pd->seq, pd->seq_hi, true,
-					   NULL))
+  if (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa0)))
     {
-      esp_decrypt_set_next_index (b, node, vm->thread_index,
-				  ESP_DECRYPT_ERROR_REPLAY, 0, next,
-				  ESP_DECRYPT_NEXT_DROP, pd->sa_index);
-      return;
+      if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, pd->seq_hi, true,
+					       NULL, true))
+	{
+	  esp_decrypt_set_next_index (b, node, vm->thread_index,
+				      ESP_DECRYPT_ERROR_REPLAY, 0, next,
+				      ESP_DECRYPT_NEXT_DROP, pd->sa_index);
+	  return;
+	}
+      n_lost = ipsec_sa_anti_replay_advance (sa0, vm->thread_index, pd->seq,
+					     pd->seq_hi, true);
+    }
+  else
+    {
+      if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, pd->seq_hi, true,
+					       NULL, false))
+	{
+	  esp_decrypt_set_next_index (b, node, vm->thread_index,
+				      ESP_DECRYPT_ERROR_REPLAY, 0, next,
+				      ESP_DECRYPT_NEXT_DROP, pd->sa_index);
+	  return;
+	}
+      n_lost = ipsec_sa_anti_replay_advance (sa0, vm->thread_index, pd->seq,
+					     pd->seq_hi, false);
     }
-
-  u64 n_lost =
-    ipsec_sa_anti_replay_advance (sa0, vm->thread_index, pd->seq, pd->seq_hi);
 
   vlib_prefetch_simple_counter (&ipsec_sa_err_counters[IPSEC_SA_ERROR_LOST],
 				vm->thread_index, pd->sa_index);
@@ -1046,6 +1062,7 @@ esp_decrypt_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
   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;
+  bool anti_replay_result;
   vnet_crypto_op_t _op, *op = &_op;
   vnet_crypto_op_t **crypto_ops;
   vnet_crypto_op_t **integ_ops;
@@ -1163,8 +1180,18 @@ esp_decrypt_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
       pd->current_length = b[0]->current_length;
 
       /* anti-reply check */
-      if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, ~0, false,
-					       &pd->seq_hi))
+      if (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa0)))
+	{
+	  anti_replay_result = ipsec_sa_anti_replay_and_sn_advance (
+	    sa0, pd->seq, ~0, false, &pd->seq_hi, true);
+	}
+      else
+	{
+	  anti_replay_result = ipsec_sa_anti_replay_and_sn_advance (
+	    sa0, pd->seq, ~0, false, &pd->seq_hi, false);
+	}
+
+      if (anti_replay_result)
 	{
 	  err = ESP_DECRYPT_ERROR_REPLAY;
 	  esp_decrypt_set_next_index (b[0], node, thread_index, err, n_noop,
diff --git a/src/vnet/ipsec/ipsec.api b/src/vnet/ipsec/ipsec.api
index ad1d21618e6..68efe8f50f7 100644
--- a/src/vnet/ipsec/ipsec.api
+++ b/src/vnet/ipsec/ipsec.api
@@ -191,12 +191,21 @@ define ipsec_sad_entry_add_del_v3
   bool is_add;
   vl_api_ipsec_sad_entry_v3_t entry;
 };
+
 define ipsec_sad_entry_add
 {
   u32 client_index;
   u32 context;
   vl_api_ipsec_sad_entry_v3_t entry;
 };
+
+define ipsec_sad_entry_add_v2
+{
+  u32 client_index;
+  u32 context;
+  vl_api_ipsec_sad_entry_v4_t entry;
+};
+
 autoreply define ipsec_sad_entry_del
 {
   u32 client_index;
@@ -273,6 +282,7 @@ define ipsec_sad_entry_add_del_v3_reply
   i32 retval;
   u32 stat_index;
 };
+
 define ipsec_sad_entry_add_reply
 {
   u32 context;
@@ -280,6 +290,13 @@ define ipsec_sad_entry_add_reply
   u32 stat_index;
 };
 
+define ipsec_sad_entry_add_v2_reply
+{
+  u32 context;
+  i32 retval;
+  u32 stat_index;
+};
+
 /** \brief Add or Update Protection for a tunnel with IPSEC
 
     Tunnel protection directly associates an SA with all packets
@@ -468,6 +485,12 @@ define ipsec_sa_v4_dump
   u32 context;
   u32 sa_id;
 };
+define ipsec_sa_v5_dump
+{
+  u32 client_index;
+  u32 context;
+  u32 sa_id;
+};
 
 /** \brief IPsec security association database response
     @param context - sender context which was passed in the request
@@ -528,7 +551,17 @@ define ipsec_sa_v4_details {
   u64 seq_outbound;
   u64 last_seq_inbound;
   u64 replay_window;
+  u32 thread_index;
+  u32 stat_index;
+};
+define ipsec_sa_v5_details {
+  u32 context;
+  vl_api_ipsec_sad_entry_v4_t entry;
 
+  vl_api_interface_index_t sw_if_index;
+  u64 seq_outbound;
+  u64 last_seq_inbound;
+  u64 replay_window;
   u32 thread_index;
   u32 stat_index;
 };
diff --git a/src/vnet/ipsec/ipsec_api.c b/src/vnet/ipsec/ipsec_api.c
index 7fc68f60369..6e7308ddf75 100644
--- a/src/vnet/ipsec/ipsec_api.c
+++ b/src/vnet/ipsec/ipsec_api.c
@@ -382,10 +382,10 @@ static void vl_api_ipsec_sad_entry_add_del_t_handler
   ip_address_decode2 (&mp->entry.tunnel_src, &tun.t_src);
   ip_address_decode2 (&mp->entry.tunnel_dst, &tun.t_dst);
 
-  rv = ipsec_sa_add_and_lock (id, spi, proto, crypto_alg, &crypto_key,
-			      integ_alg, &integ_key, flags, mp->entry.salt,
-			      htons (mp->entry.udp_src_port),
-			      htons (mp->entry.udp_dst_port), &tun, &sa_index);
+  rv = ipsec_sa_add_and_lock (
+    id, spi, proto, crypto_alg, &crypto_key, integ_alg, &integ_key, flags,
+    mp->entry.salt, htons (mp->entry.udp_src_port),
+    htons (mp->entry.udp_dst_port), 0, &tun, &sa_index);
 
 out:
   /* *INDENT-OFF* */
@@ -456,10 +456,10 @@ static void vl_api_ipsec_sad_entry_add_del_v2_t_handler
   ip_address_decode2 (&mp->entry.tunnel_src, &tun.t_src);
   ip_address_decode2 (&mp->entry.tunnel_dst, &tun.t_dst);
 
-    rv = ipsec_sa_add_and_lock (
-      id, spi, proto, crypto_alg, &crypto_key, integ_alg, &integ_key, flags,
-      mp->entry.salt, htons (mp->entry.udp_src_port),
-      htons (mp->entry.udp_dst_port), &tun, &sa_index);
+  rv = ipsec_sa_add_and_lock (
+    id, spi, proto, crypto_alg, &crypto_key, integ_alg, &integ_key, flags,
+    mp->entry.salt, htons (mp->entry.udp_src_port),
+    htons (mp->entry.udp_dst_port), 0, &tun, &sa_index);
 
 out:
   /* *INDENT-OFF* */
@@ -514,10 +514,10 @@ ipsec_sad_entry_add_v3 (const vl_api_ipsec_sad_entry_v3_t *entry,
   ipsec_key_decode (&entry->crypto_key, &crypto_key);
   ipsec_key_decode (&entry->integrity_key, &integ_key);
 
-  return ipsec_sa_add_and_lock (id, spi, proto, crypto_alg, &crypto_key,
-				integ_alg, &integ_key, flags, entry->salt,
-				htons (entry->udp_src_port),
-				htons (entry->udp_dst_port), &tun, sa_index);
+  return ipsec_sa_add_and_lock (
+    id, spi, proto, crypto_alg, &crypto_key, integ_alg, &integ_key, flags,
+    entry->salt, htons (entry->udp_src_port), htons (entry->udp_dst_port), 0,
+    &tun, sa_index);
 }
 
 static void
@@ -543,6 +543,56 @@ vl_api_ipsec_sad_entry_add_del_v3_t_handler (
 		{ rmp->stat_index = htonl (sa_index); });
 }
 
+static int
+ipsec_sad_entry_add_v4 (const vl_api_ipsec_sad_entry_v4_t *entry,
+			u32 *sa_index)
+{
+  ipsec_key_t crypto_key, integ_key;
+  ipsec_crypto_alg_t crypto_alg;
+  ipsec_integ_alg_t integ_alg;
+  ipsec_protocol_t proto;
+  ipsec_sa_flags_t flags;
+  u32 id, spi;
+  tunnel_t tun = { 0 };
+  int rv;
+
+  id = ntohl (entry->sad_id);
+  spi = ntohl (entry->spi);
+
+  rv = ipsec_proto_decode (entry->protocol, &proto);
+
+  if (rv)
+    return rv;
+
+  rv = ipsec_crypto_algo_decode (entry->crypto_algorithm, &crypto_alg);
+
+  if (rv)
+    return rv;
+
+  rv = ipsec_integ_algo_decode (entry->integrity_algorithm, &integ_alg);
+
+  if (rv)
+    return rv;
+
+  flags = ipsec_sa_flags_decode (entry->flags);
+
+  if (flags & IPSEC_SA_FLAG_IS_TUNNEL)
+    {
+      rv = tunnel_decode (&entry->tunnel, &tun);
+
+      if (rv)
+	return rv;
+    }
+
+  ipsec_key_decode (&entry->crypto_key, &crypto_key);
+  ipsec_key_decode (&entry->integrity_key, &integ_key);
+
+  return ipsec_sa_add_and_lock (
+    id, spi, proto, crypto_alg, &crypto_key, integ_alg, &integ_key, flags,
+    entry->salt, htons (entry->udp_src_port), htons (entry->udp_dst_port),
+    ntohl (entry->anti_replay_window_size), &tun, sa_index);
+}
+
 static void
 vl_api_ipsec_sad_entry_del_t_handler (vl_api_ipsec_sad_entry_del_t *mp)
 {
@@ -568,6 +618,19 @@ vl_api_ipsec_sad_entry_add_t_handler (vl_api_ipsec_sad_entry_add_t *mp)
 }
 
 static void
+vl_api_ipsec_sad_entry_add_v2_t_handler (vl_api_ipsec_sad_entry_add_v2_t *mp)
+{
+  vl_api_ipsec_sad_entry_add_reply_t *rmp;
+  u32 sa_index = ~0;
+  int rv;
+
+  rv = ipsec_sad_entry_add_v4 (&mp->entry, &sa_index);
+
+  REPLY_MACRO2 (VL_API_IPSEC_SAD_ENTRY_ADD_V2_REPLY,
+		{ rmp->stat_index = htonl (sa_index); });
+}
+
+static void
 vl_api_ipsec_sad_entry_update_t_handler (vl_api_ipsec_sad_entry_update_t *mp)
 {
   vl_api_ipsec_sad_entry_update_reply_t *rmp;
@@ -953,7 +1016,10 @@ send_ipsec_sa_details (ipsec_sa_t * sa, void *arg)
       mp->last_seq_inbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
     }
   if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
-    mp->replay_window = clib_host_to_net_u64 (sa->replay_window);
+    {
+      mp->replay_window =
+	clib_host_to_net_u64 (ipsec_sa_anti_replay_get_64b_window (sa));
+    }
 
   mp->stat_index = clib_host_to_net_u32 (sa->stat_index);
 
@@ -1040,7 +1106,10 @@ send_ipsec_sa_v2_details (ipsec_sa_t * sa, void *arg)
       mp->last_seq_inbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
     }
   if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
-    mp->replay_window = clib_host_to_net_u64 (sa->replay_window);
+    {
+      mp->replay_window =
+	clib_host_to_net_u64 (ipsec_sa_anti_replay_get_64b_window (sa));
+    }
 
   mp->stat_index = clib_host_to_net_u32 (sa->stat_index);
 
@@ -1120,7 +1189,10 @@ send_ipsec_sa_v3_details (ipsec_sa_t *sa, void *arg)
       mp->last_seq_inbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
     }
   if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
-    mp->replay_window = clib_host_to_net_u64 (sa->replay_window);
+    {
+      mp->replay_window =
+	clib_host_to_net_u64 (ipsec_sa_anti_replay_get_64b_window (sa));
+    }
 
   mp->stat_index = clib_host_to_net_u32 (sa->stat_index);
 
@@ -1200,7 +1272,10 @@ send_ipsec_sa_v4_details (ipsec_sa_t *sa, void *arg)
       mp->last_seq_inbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
     }
   if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
-    mp->replay_window = clib_host_to_net_u64 (sa->replay_window);
+    {
+      mp->replay_window =
+	clib_host_to_net_u64 (ipsec_sa_anti_replay_get_64b_window (sa));
+    }
 
   mp->thread_index = clib_host_to_net_u32 (sa->thread_index);
   mp->stat_index = clib_host_to_net_u32 (sa->stat_index);
@@ -1227,8 +1302,95 @@ vl_api_ipsec_sa_v4_dump_t_handler (vl_api_ipsec_sa_v4_dump_t *mp)
   ipsec_sa_walk (send_ipsec_sa_v4_details, &ctx);
 }
 
+static walk_rc_t
+send_ipsec_sa_v5_details (ipsec_sa_t *sa, void *arg)
+{
+  ipsec_dump_walk_ctx_t *ctx = arg;
+  vl_api_ipsec_sa_v5_details_t *mp;
+
+  mp = vl_msg_api_alloc (sizeof (*mp));
+  clib_memset (mp, 0, sizeof (*mp));
+  mp->_vl_msg_id = ntohs (REPLY_MSG_ID_BASE + VL_API_IPSEC_SA_V5_DETAILS);
+  mp->context = ctx->context;
+
+  mp->entry.sad_id = htonl (sa->id);
+  mp->entry.spi = htonl (sa->spi);
+  mp->entry.protocol = ipsec_proto_encode (sa->protocol);
+
+  mp->entry.crypto_algorithm = ipsec_crypto_algo_encode (sa->crypto_alg);
+  ipsec_key_encode (&sa->crypto_key, &mp->entry.crypto_key);
+
+  mp->entry.integrity_algorithm = ipsec_integ_algo_encode (sa->integ_alg);
+  ipsec_key_encode (&sa->integ_key, &mp->entry.integrity_key);
+
+  mp->entry.flags = ipsec_sad_flags_encode (sa);
+  mp->entry.salt = clib_host_to_net_u32 (sa->salt);
+
+  if (ipsec_sa_is_set_IS_PROTECT (sa))
+    {
+      ipsec_sa_dump_match_ctx_t ctx = {
+	.sai = sa - ipsec_sa_pool,
+	.sw_if_index = ~0,
+      };
+      ipsec_tun_protect_walk (ipsec_sa_dump_match_sa, &ctx);
+
+      mp->sw_if_index = htonl (ctx.sw_if_index);
+    }
+  else
+    mp->sw_if_index = ~0;
+
+  if (ipsec_sa_is_set_IS_TUNNEL (sa))
+    tunnel_encode (&sa->tunnel, &mp->entry.tunnel);
+
+  if (ipsec_sa_is_set_UDP_ENCAP (sa))
+    {
+      mp->entry.udp_src_port = sa->udp_hdr.src_port;
+      mp->entry.udp_dst_port = sa->udp_hdr.dst_port;
+    }
+
+  mp->seq_outbound = clib_host_to_net_u64 (((u64) sa->seq));
+  mp->last_seq_inbound = clib_host_to_net_u64 (((u64) sa->seq));
+  if (ipsec_sa_is_set_USE_ESN (sa))
+    {
+      mp->seq_outbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
+      mp->last_seq_inbound |= (u64) (clib_host_to_net_u32 (sa->seq_hi));
+    }
+  if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
+    {
+      mp->replay_window =
+	clib_host_to_net_u64 (ipsec_sa_anti_replay_get_64b_window (sa));
+
+      mp->entry.anti_replay_window_size =
+	clib_host_to_net_u32 (IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (sa));
+    }
+
+  mp->thread_index = clib_host_to_net_u32 (sa->thread_index);
+  mp->stat_index = clib_host_to_net_u32 (sa->stat_index);
+
+  vl_api_send_msg (ctx->reg, (u8 *) mp);
+
+  return (WALK_CONTINUE);
+}
+
+static void
+vl_api_ipsec_sa_v5_dump_t_handler (vl_api_ipsec_sa_v5_dump_t *mp)
+{
+  vl_api_registration_t *reg;
+
+  reg = vl_api_client_index_to_registration (mp->client_index);
+  if (!reg)
+    return;
+
+  ipsec_dump_walk_ctx_t ctx = {
+    .reg = reg,
+    .context = mp->context,
+  };
+
+  ipsec_sa_walk (send_ipsec_sa_v5_details, &ctx);
+}
+
 static void
-vl_api_ipsec_backend_dump_t_handler (vl_api_ipsec_backend_dump_t * mp)
+vl_api_ipsec_backend_dump_t_handler (vl_api_ipsec_backend_dump_t *mp)
 {
   vl_api_registration_t *rp;
   ipsec_main_t *im = &ipsec_main;
diff --git a/src/vnet/ipsec/ipsec_cli.c b/src/vnet/ipsec/ipsec_cli.c
index 6cb9aba4d8a..5aef630a33f 100644
--- a/src/vnet/ipsec/ipsec_cli.c
+++ b/src/vnet/ipsec/ipsec_cli.c
@@ -88,6 +88,7 @@ ipsec_sa_add_del_command_fn (vlib_main_t * vm,
   unformat_input_t _line_input, *line_input = &_line_input;
   ipsec_crypto_alg_t crypto_alg;
   ipsec_integ_alg_t integ_alg;
+  u32 anti_replay_window_size;
   ipsec_protocol_t proto;
   ipsec_sa_flags_t flags;
   clib_error_t *error;
@@ -105,6 +106,7 @@ ipsec_sa_add_del_command_fn (vlib_main_t * vm,
   is_add = 0;
   flags = IPSEC_SA_FLAG_NONE;
   proto = IPSEC_PROTOCOL_ESP;
+  anti_replay_window_size = 0;
   integ_alg = IPSEC_INTEG_ALG_NONE;
   crypto_alg = IPSEC_CRYPTO_ALG_NONE;
   udp_src = udp_dst = IPSEC_UDP_PORT_NONE;
@@ -153,6 +155,9 @@ ipsec_sa_add_del_command_fn (vlib_main_t * vm,
 	udp_src = i;
       else if (unformat (line_input, "udp-dst-port %d", &i))
 	udp_dst = i;
+      else if (unformat (line_input, "anti-replay-size %d",
+			 &anti_replay_window_size))
+	flags |= IPSEC_SA_FLAG_USE_ANTI_REPLAY;
       else if (unformat (line_input, "inbound"))
 	flags |= IPSEC_SA_FLAG_IS_INBOUND;
       else if (unformat (line_input, "use-anti-replay"))
@@ -184,9 +189,10 @@ ipsec_sa_add_del_command_fn (vlib_main_t * vm,
 	  error = clib_error_return (0, "missing spi");
 	  goto done;
 	}
-      rv = ipsec_sa_add_and_lock (id, spi, proto, crypto_alg, &ck, integ_alg,
-				  &ik, flags, clib_host_to_net_u32 (salt),
-				  udp_src, udp_dst, &tun, &sai);
+      rv =
+	ipsec_sa_add_and_lock (id, spi, proto, crypto_alg, &ck, integ_alg, &ik,
+			       flags, clib_host_to_net_u32 (salt), udp_src,
+			       udp_dst, anti_replay_window_size, &tun, &sai);
     }
   else
     {
diff --git a/src/vnet/ipsec/ipsec_format.c b/src/vnet/ipsec/ipsec_format.c
index d1511acdc26..12381ceaa13 100644
--- a/src/vnet/ipsec/ipsec_format.c
+++ b/src/vnet/ipsec/ipsec_format.c
@@ -466,16 +466,18 @@ format_ipsec_sa (u8 * s, va_list * args)
   s = format (s, "\n   salt 0x%x", clib_net_to_host_u32 (sa->salt));
   s = format (s, "\n   thread-index:%d", sa->thread_index);
   s = format (s, "\n   seq %u seq-hi %u", sa->seq, sa->seq_hi);
-  s = format (s, "\n   window %U", format_ipsec_replay_window,
-	      sa->replay_window);
-  s = format (s, "\n   crypto alg %U",
-	      format_ipsec_crypto_alg, sa->crypto_alg);
+  s = format (s, "\n   window-size: %llu",
+	      IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (sa));
+  s = format (s, "\n   window: Bl <- %U Tl", format_ipsec_replay_window,
+	      ipsec_sa_anti_replay_get_64b_window (sa));
+  s =
+    format (s, "\n   crypto alg %U", format_ipsec_crypto_alg, sa->crypto_alg);
   if (sa->crypto_alg && (flags & IPSEC_FORMAT_INSECURE))
     s = format (s, " key %U", format_ipsec_key, &sa->crypto_key);
   else
     s = format (s, " key [redacted]");
-  s = format (s, "\n   integrity alg %U",
-	      format_ipsec_integ_alg, sa->integ_alg);
+  s =
+    format (s, "\n   integrity alg %U", format_ipsec_integ_alg, sa->integ_alg);
   if (sa->integ_alg && (flags & IPSEC_FORMAT_INSECURE))
     s = format (s, " key %U", format_ipsec_key, &sa->integ_key);
   else
diff --git a/src/vnet/ipsec/ipsec_sa.c b/src/vnet/ipsec/ipsec_sa.c
index 98160cde389..1656b9aa0cc 100644
--- a/src/vnet/ipsec/ipsec_sa.c
+++ b/src/vnet/ipsec/ipsec_sa.c
@@ -329,7 +329,8 @@ ipsec_sa_add_and_lock (u32 id, u32 spi, ipsec_protocol_t proto,
 		       ipsec_crypto_alg_t crypto_alg, const ipsec_key_t *ck,
 		       ipsec_integ_alg_t integ_alg, const ipsec_key_t *ik,
 		       ipsec_sa_flags_t flags, u32 salt, u16 src_port,
-		       u16 dst_port, const tunnel_t *tun, u32 *sa_out_index)
+		       u16 dst_port, u32 anti_replay_window_size,
+		       const tunnel_t *tun, u32 *sa_out_index)
 {
   vlib_main_t *vm = vlib_get_main ();
   ipsec_main_t *im = &ipsec_main;
@@ -379,6 +380,9 @@ ipsec_sa_add_and_lock (u32 id, u32 spi, ipsec_protocol_t proto,
   ipsec_sa_set_crypto_alg (sa, crypto_alg);
   ipsec_sa_set_async_op_ids (sa);
 
+  if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa) && anti_replay_window_size > 64)
+    ipsec_sa_set_ANTI_REPLAY_HUGE (sa);
+
   clib_memcpy (&sa->crypto_key, ck, sizeof (sa->crypto_key));
 
   sa->crypto_sync_key_index = vnet_crypto_key_add (
@@ -488,6 +492,18 @@ ipsec_sa_add_and_lock (u32 id, u32 spi, ipsec_protocol_t proto,
 				 !ipsec_sa_is_set_IS_TUNNEL_V6 (sa));
     }
 
+  /* window size rounded up to next power of 2 */
+  if (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa))
+    {
+      anti_replay_window_size = 1 << max_log2 (anti_replay_window_size);
+      sa->replay_window_huge =
+	clib_bitmap_set_region (0, 0, 1, anti_replay_window_size);
+    }
+  else
+    {
+      sa->replay_window = ~0;
+    }
+
   hash_set (im->sa_index_by_sa_id, sa->id, sa_index);
 
   if (sa_out_index)
@@ -525,6 +541,8 @@ ipsec_sa_del (ipsec_sa_t * sa)
   vnet_crypto_key_del (vm, sa->crypto_sync_key_index);
   if (sa->integ_alg != IPSEC_INTEG_ALG_NONE)
     vnet_crypto_key_del (vm, sa->integ_sync_key_index);
+  if (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa))
+    clib_bitmap_free (sa->replay_window_huge);
   pool_put (ipsec_sa_pool, sa);
 }
 
diff --git a/src/vnet/ipsec/ipsec_sa.h b/src/vnet/ipsec/ipsec_sa.h
index cd90ef5c441..47058511036 100644
--- a/src/vnet/ipsec/ipsec_sa.h
+++ b/src/vnet/ipsec/ipsec_sa.h
@@ -121,7 +121,8 @@ typedef struct ipsec_key_t_
   _ (256, IS_CTR, "ctr")                                                      \
   _ (512, IS_ASYNC, "async")                                                  \
   _ (1024, NO_ALGO_NO_DROP, "no-algo-no-drop")                                \
-  _ (2048, IS_NULL_GMAC, "null-gmac")
+  _ (2048, IS_NULL_GMAC, "null-gmac")                                         \
+  _ (4096, ANTI_REPLAY_HUGE, "anti-replay-huge")
 
 typedef enum ipsec_sad_flags_t_
 {
@@ -167,7 +168,11 @@ typedef struct
 
   clib_pcg64i_random_t iv_prng;
 
-  u64 replay_window;
+  union
+  {
+    u64 replay_window;
+    clib_bitmap_t *replay_window_huge;
+  };
   dpo_id_t dpo;
 
   vnet_crypto_key_index_t crypto_key_index;
@@ -254,94 +259,149 @@ STATIC_ASSERT (STRUCT_OFFSET_OF (vnet_buffer_opaque_t, ipsec.sad_index) ==
 		 STRUCT_OFFSET_OF (vnet_buffer_opaque_t, ip.save_protocol),
 	       "IPSec data is overlapping with IP data");
 
-#define _(a,v,s)                                                        \
-  always_inline int                                                     \
-  ipsec_sa_is_set_##v (const ipsec_sa_t *sa) {                          \
-    return (sa->flags & IPSEC_SA_FLAG_##v);                             \
+#define _(a, v, s)                                                            \
+  always_inline bool ipsec_sa_is_set_##v (const ipsec_sa_t *sa)               \
+  {                                                                           \
+    return (sa->flags & IPSEC_SA_FLAG_##v);                                   \
   }
 foreach_ipsec_sa_flags
 #undef _
-#define _(a,v,s)                                                        \
-  always_inline int                                                     \
-  ipsec_sa_set_##v (ipsec_sa_t *sa) {                                   \
-    return (sa->flags |= IPSEC_SA_FLAG_##v);                            \
+#define _(a, v, s)                                                            \
+  always_inline void ipsec_sa_set_##v (ipsec_sa_t *sa)                        \
+  {                                                                           \
+    sa->flags |= IPSEC_SA_FLAG_##v;                                           \
   }
   foreach_ipsec_sa_flags
 #undef _
-#define _(a,v,s)                                                        \
-  always_inline int                                                     \
-  ipsec_sa_unset_##v (ipsec_sa_t *sa) {                                 \
-    return (sa->flags &= ~IPSEC_SA_FLAG_##v);                           \
+#define _(a, v, s)                                                            \
+  always_inline int ipsec_sa_unset_##v (ipsec_sa_t *sa)                       \
+  {                                                                           \
+    return (sa->flags &= ~IPSEC_SA_FLAG_##v);                                 \
   }
-  foreach_ipsec_sa_flags
+    foreach_ipsec_sa_flags
 #undef _
-/**
- * @brief
- * SA packet & bytes counters
- */
-extern vlib_combined_counter_main_t ipsec_sa_counters;
+  /**
+   * @brief
+   * SA packet & bytes counters
+   */
+  extern vlib_combined_counter_main_t ipsec_sa_counters;
 extern vlib_simple_counter_main_t ipsec_sa_err_counters[IPSEC_SA_N_ERRORS];
 
-extern void ipsec_mk_key (ipsec_key_t * key, const u8 * data, u8 len);
+extern void ipsec_mk_key (ipsec_key_t *key, const u8 *data, u8 len);
 
 extern int ipsec_sa_update (u32 id, u16 src_port, u16 dst_port,
 			    const tunnel_t *tun, bool is_tun);
-extern int
-ipsec_sa_add_and_lock (u32 id, u32 spi, ipsec_protocol_t proto,
-		       ipsec_crypto_alg_t crypto_alg, const ipsec_key_t *ck,
-		       ipsec_integ_alg_t integ_alg, const ipsec_key_t *ik,
-		       ipsec_sa_flags_t flags, u32 salt, u16 src_port,
-		       u16 dst_port, const tunnel_t *tun, u32 *sa_out_index);
+extern int ipsec_sa_add_and_lock (
+  u32 id, u32 spi, ipsec_protocol_t proto, ipsec_crypto_alg_t crypto_alg,
+  const ipsec_key_t *ck, ipsec_integ_alg_t integ_alg, const ipsec_key_t *ik,
+  ipsec_sa_flags_t flags, u32 salt, u16 src_port, u16 dst_port,
+  u32 anti_replay_window_size, const tunnel_t *tun, u32 *sa_out_index);
 extern int ipsec_sa_bind (u32 id, u32 worker, bool bind);
 extern index_t ipsec_sa_find_and_lock (u32 id);
 extern int ipsec_sa_unlock_id (u32 id);
 extern void ipsec_sa_unlock (index_t sai);
 extern void ipsec_sa_lock (index_t sai);
 extern void ipsec_sa_clear (index_t sai);
-extern void ipsec_sa_set_crypto_alg (ipsec_sa_t * sa,
+extern void ipsec_sa_set_crypto_alg (ipsec_sa_t *sa,
 				     ipsec_crypto_alg_t crypto_alg);
-extern void ipsec_sa_set_integ_alg (ipsec_sa_t * sa,
+extern void ipsec_sa_set_integ_alg (ipsec_sa_t *sa,
 				    ipsec_integ_alg_t integ_alg);
 extern void ipsec_sa_set_async_mode (ipsec_sa_t *sa, int is_enabled);
 
-typedef walk_rc_t (*ipsec_sa_walk_cb_t) (ipsec_sa_t * sa, void *ctx);
+typedef walk_rc_t (*ipsec_sa_walk_cb_t) (ipsec_sa_t *sa, void *ctx);
 extern void ipsec_sa_walk (ipsec_sa_walk_cb_t cd, void *ctx);
 
 extern u8 *format_ipsec_replay_window (u8 *s, va_list *args);
-extern u8 *format_ipsec_crypto_alg (u8 * s, va_list * args);
-extern u8 *format_ipsec_integ_alg (u8 * s, va_list * args);
-extern u8 *format_ipsec_sa (u8 * s, va_list * args);
-extern u8 *format_ipsec_key (u8 * s, va_list * args);
-extern uword unformat_ipsec_crypto_alg (unformat_input_t * input,
-					va_list * args);
-extern uword unformat_ipsec_integ_alg (unformat_input_t * input,
-				       va_list * args);
-extern uword unformat_ipsec_key (unformat_input_t * input, va_list * args);
-
-#define IPSEC_UDP_PORT_NONE ((u16)~0)
+extern u8 *format_ipsec_crypto_alg (u8 *s, va_list *args);
+extern u8 *format_ipsec_integ_alg (u8 *s, va_list *args);
+extern u8 *format_ipsec_sa (u8 *s, va_list *args);
+extern u8 *format_ipsec_key (u8 *s, va_list *args);
+extern uword unformat_ipsec_crypto_alg (unformat_input_t *input,
+					va_list *args);
+extern uword unformat_ipsec_integ_alg (unformat_input_t *input, va_list *args);
+extern uword unformat_ipsec_key (unformat_input_t *input, va_list *args);
+
+#define IPSEC_UDP_PORT_NONE ((u16) ~0)
 
 /*
  * Anti Replay definitions
  */
 
-#define IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (64)
-#define IPSEC_SA_ANTI_REPLAY_WINDOW_MAX_INDEX (IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE-1)
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE(_sa)                                 \
+  (u32) (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (_sa)) ?             \
+		 clib_bitmap_bytes (_sa->replay_window_huge) * 8 :                  \
+		 BITS (_sa->replay_window))
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN(_sa, _is_huge)             \
+  (u32) (_is_huge ? clib_bitmap_bytes (_sa->replay_window_huge) * 8 :         \
+			  BITS (_sa->replay_window))
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_N_SEEN(_sa)                               \
+  (u64) (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (_sa)) ?             \
+		 clib_bitmap_count_set_bits (_sa->replay_window_huge) :             \
+		 count_set_bits (_sa->replay_window))
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_N_SEEN_KNOWN_WIN(_sa, _is_huge)           \
+  (u64) (_is_huge ? clib_bitmap_count_set_bits (_sa->replay_window_huge) :    \
+			  count_set_bits (_sa->replay_window))
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_MAX_INDEX(_sa)                            \
+  (u32) (IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (_sa) - 1)
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_MAX_INDEX_KNOWN_WIN(_sa, _is_huge)        \
+  (u32) (IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (_sa, _is_huge) - 1)
 
 /*
  * sequence number less than the lower bound are outside of the window
  * From RFC4303 Appendix A:
  *  Bl = Tl - W + 1
  */
-#define IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND(_tl) (_tl - IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE + 1)
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND(_sa)                          \
+  (u32) (_sa->seq - IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (_sa) + 1)
+
+#define IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND_KNOWN_WIN(_sa, _is_huge)      \
+  (u32) (_sa->seq -                                                           \
+	 IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN (_sa, _is_huge) + 1)
+
+always_inline u64
+ipsec_sa_anti_replay_get_64b_window (const ipsec_sa_t *sa)
+{
+  if (!ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa))
+    return sa->replay_window;
+
+  u64 w;
+  u32 window_size = IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE (sa);
+  u32 tl_win_index = sa->seq & (window_size - 1);
+
+  if (PREDICT_TRUE (tl_win_index >= 63))
+    return clib_bitmap_get_multiple (sa->replay_window_huge, tl_win_index - 63,
+				     64);
+
+  w = clib_bitmap_get_multiple_no_check (sa->replay_window_huge, 0,
+					 tl_win_index + 1)
+      << (63 - tl_win_index);
+  w |= clib_bitmap_get_multiple_no_check (sa->replay_window_huge,
+					  window_size - 63 + tl_win_index,
+					  63 - tl_win_index);
+
+  return w;
+}
 
 always_inline int
-ipsec_sa_anti_replay_check (const ipsec_sa_t *sa, u32 seq)
+ipsec_sa_anti_replay_check (const ipsec_sa_t *sa, u32 seq, bool ar_huge)
 {
-  if (ipsec_sa_is_set_USE_ANTI_REPLAY (sa) &&
-      sa->replay_window & (1ULL << (sa->seq - seq)))
-    return 1;
+  u32 window_size = IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN (sa, ar_huge);
+
+  /* we assume that the packet is in the window.
+   * if the packet falls left (sa->seq - seq >= window size),
+   * the result is wrong */
+
+  if (ar_huge)
+    return clib_bitmap_get (sa->replay_window_huge, seq & (window_size - 1));
   else
-    return 0;
+    return (sa->replay_window >> (window_size + seq - sa->seq - 1)) & 1;
+
+  return 0;
 }
 
 /*
@@ -361,10 +421,14 @@ ipsec_sa_anti_replay_check (const ipsec_sa_t *sa, u32 seq)
 always_inline int
 ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 				     u32 hi_seq_used, bool post_decrypt,
-				     u32 *hi_seq_req)
+				     u32 *hi_seq_req, bool ar_huge)
 {
   ASSERT ((post_decrypt == false) == (hi_seq_req != 0));
 
+  u32 window_size = IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN (sa, ar_huge);
+  u32 window_lower_bound =
+    IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND_KNOWN_WIN (sa, ar_huge);
+
   if (!ipsec_sa_is_set_USE_ESN (sa))
     {
       if (hi_seq_req)
@@ -377,14 +441,11 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
       if (PREDICT_TRUE (seq > sa->seq))
 	return 0;
 
-      u32 diff = sa->seq - seq;
-
-      if (IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE > diff)
-	return ((sa->replay_window & (1ULL << diff)) ? 1 : 0);
-      else
+      /* does the packet fall out on the left of the window */
+      if (sa->seq >= seq + window_size)
 	return 1;
 
-      return 0;
+      return ipsec_sa_anti_replay_check (sa, seq, ar_huge);
     }
 
   if (!ipsec_sa_is_set_USE_ANTI_REPLAY (sa))
@@ -424,14 +485,15 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
        */
       return 0;
     }
-  if (PREDICT_TRUE (sa->seq >= (IPSEC_SA_ANTI_REPLAY_WINDOW_MAX_INDEX)))
+
+  if (PREDICT_TRUE (sa->seq >= window_size - 1))
     {
       /*
-       * the last sequence number VPP recieved is more than one
+       * the last sequence number VPP received is more than one
        * window size greater than zero.
        * Case A from RFC4303 Appendix A.
        */
-      if (seq < IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND (sa->seq))
+      if (seq < window_lower_bound)
 	{
 	  /*
 	   * the received sequence number is lower than the lower bound
@@ -443,7 +505,7 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 	    {
 	      if (hi_seq_used == sa->seq_hi)
 		/* the high sequence number used to succesfully decrypt this
-		 * packet is the same as the last-sequnence number of the SA.
+		 * packet is the same as the last-sequence number of the SA.
 		 * that means this packet did not cause a wrap.
 		 * this packet is thus out of window and should be dropped */
 		return 1;
@@ -455,8 +517,8 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 	    }
 	  else
 	    {
-	      /* pre-decrypt it might be the might that casues a wrap, we
-	       * need to decrpyt to find out */
+	      /* pre-decrypt it might be the packet that causes a wrap, we
+	       * need to decrypt it to find out */
 	      if (hi_seq_req)
 		*hi_seq_req = sa->seq_hi + 1;
 	      return 0;
@@ -465,17 +527,17 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
       else
 	{
 	  /*
-	   * the recieved sequence number greater than the low
+	   * the received sequence number greater than the low
 	   * end of the window.
 	   */
 	  if (hi_seq_req)
 	    *hi_seq_req = sa->seq_hi;
 	  if (seq <= sa->seq)
 	    /*
-	     * The recieved seq number is within bounds of the window
+	     * The received seq number is within bounds of the window
 	     * check if it's a duplicate
 	     */
-	    return (ipsec_sa_anti_replay_check (sa, seq));
+	    return ipsec_sa_anti_replay_check (sa, seq, ar_huge);
 	  else
 	    /*
 	     * The received sequence number is greater than the window
@@ -488,14 +550,14 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
   else
     {
       /*
-       * the last sequence number VPP recieved is within one window
+       * the last sequence number VPP received is within one window
        * size of zero, i.e. 0 < TL < WINDOW_SIZE, the lower bound is thus a
        * large sequence number.
-       * Note that the check below uses unsiged integer arthimetic, so the
+       * Note that the check below uses unsigned integer arithmetic, so the
        * RHS will be a larger number.
        * Case B from RFC4303 Appendix A.
        */
-      if (seq < IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND (sa->seq))
+      if (seq < window_lower_bound)
 	{
 	  /*
 	   * the sequence number is less than the lower bound.
@@ -508,7 +570,7 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 	       */
 	      if (hi_seq_req)
 		*hi_seq_req = sa->seq_hi;
-	      return (ipsec_sa_anti_replay_check (sa, seq));
+	      return ipsec_sa_anti_replay_check (sa, seq, ar_huge);
 	    }
 	  else
 	    {
@@ -516,7 +578,7 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 	       * the packet is less the window lower bound or greater than
 	       * the higher bound, depending on how you look at it...
 	       * We're assuming, given that the last sequence number received,
-	       * TL < WINDOW_SIZE, that a largeer seq num is more likely to be
+	       * TL < WINDOW_SIZE, that a larger seq num is more likely to be
 	       * a packet that moves the window forward, than a packet that has
 	       * wrapped the high sequence again. If it were the latter then
 	       * we've lost close to 2^32 packets.
@@ -529,15 +591,14 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
       else
 	{
 	  /*
-	   * the packet seq number is between the lower bound (a large nubmer)
-	   * and MAX_SEQ_NUM. This is in the window since the window upper bound
-	   * tl > 0.
-	   * However, since TL is the other side of 0 to the received
-	   * packet, the SA has moved on to a higher sequence number.
+	   * the packet seq number is between the lower bound (a large number)
+	   * and MAX_SEQ_NUM. This is in the window since the window upper
+	   * bound tl > 0. However, since TL is the other side of 0 to the
+	   * received packet, the SA has moved on to a higher sequence number.
 	   */
 	  if (hi_seq_req)
 	    *hi_seq_req = sa->seq_hi - 1;
-	  return (ipsec_sa_anti_replay_check (sa, seq));
+	  return ipsec_sa_anti_replay_check (sa, seq, ar_huge);
 	}
     }
 
@@ -547,45 +608,148 @@ ipsec_sa_anti_replay_and_sn_advance (const ipsec_sa_t *sa, u32 seq,
 }
 
 always_inline u32
-ipsec_sa_anti_replay_window_shift (ipsec_sa_t *sa, u32 inc)
+ipsec_sa_anti_replay_window_shift (ipsec_sa_t *sa, u32 inc, bool ar_huge)
 {
   u32 n_lost = 0;
+  u32 seen = 0;
+  u32 window_size = IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN (sa, ar_huge);
 
-  if (inc < IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE)
+  if (inc < window_size)
     {
-      if (sa->seq > IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE)
+      if (ar_huge)
+	{
+	  /* the number of packets we saw in this section of the window */
+	  clib_bitmap_t *window = sa->replay_window_huge;
+	  u32 window_lower_bound = (sa->seq + 1) & (window_size - 1);
+	  u32 window_next_lower_bound =
+	    (window_lower_bound + inc) & (window_size - 1);
+
+	  uword i_block, i_word_start, i_word_end, full_words;
+	  uword n_blocks = window_size >> log2_uword_bits;
+	  uword mask;
+
+	  i_block = window_lower_bound >> log2_uword_bits;
+
+	  i_word_start = window_lower_bound & (uword_bits - 1);
+	  i_word_end = window_next_lower_bound & (uword_bits - 1);
+
+	  /* We stay in the same word */
+	  if (i_word_start + inc <= uword_bits)
+	    {
+	      mask = pow2_mask (inc) << i_word_start;
+	      seen += count_set_bits (window[i_block] & mask);
+	      window[i_block] &= ~mask;
+	    }
+	  else
+	    {
+	      full_words = (inc + i_word_start - uword_bits - i_word_end) >>
+			   log2_uword_bits;
+
+	      /* count set bits in the first word */
+	      mask = (uword) ~0 << i_word_start;
+	      seen += count_set_bits (window[i_block] & mask);
+	      window[i_block] &= ~mask;
+	      i_block = (i_block + 1) & (n_blocks - 1);
+
+	      /* count set bits in the next full words */
+	      /* even if the last word need to be fully counted, we treat it
+	       * apart */
+	      while (full_words >= 8)
+		{
+		  if (full_words >= 16)
+		    {
+		      /* prefect the next 8 blocks (64 bytes) */
+		      clib_prefetch_store (
+			&window[(i_block + 8) & (n_blocks - 1)]);
+		    }
+
+		  seen += count_set_bits (window[i_block]);
+		  seen +=
+		    count_set_bits (window[(i_block + 1) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 2) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 3) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 4) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 5) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 6) & (n_blocks - 1)]);
+		  seen +=
+		    count_set_bits (window[(i_block + 7) & (n_blocks - 1)]);
+		  window[i_block] = 0;
+		  window[(i_block + 1) & (n_blocks - 1)] = 0;
+		  window[(i_block + 2) & (n_blocks - 1)] = 0;
+		  window[(i_block + 3) & (n_blocks - 1)] = 0;
+		  window[(i_block + 4) & (n_blocks - 1)] = 0;
+		  window[(i_block + 5) & (n_blocks - 1)] = 0;
+		  window[(i_block + 6) & (n_blocks - 1)] = 0;
+		  window[(i_block + 7) & (n_blocks - 1)] = 0;
+
+		  i_block = (i_block + 8) & (n_blocks - 1);
+		  full_words -= 8;
+		}
+	      while (full_words > 0)
+		{
+		  // last word is treated after the loop
+		  seen += count_set_bits (window[i_block]);
+		  window[i_block] = 0;
+		  i_block = (i_block + 1) & (n_blocks - 1);
+		  full_words--;
+		}
+
+	      /* the last word */
+	      mask = pow2_mask (i_word_end);
+	      seen += count_set_bits (window[i_block] & mask);
+	      window[i_block] &= ~mask;
+	    }
+
+	  clib_bitmap_set_no_check (window,
+				    (sa->seq + inc) & (window_size - 1), 1);
+	}
+      else
 	{
 	  /*
 	   * count how many holes there are in the portion
 	   * of the window that we will right shift of the end
 	   * as a result of this increments
 	   */
-	  u64 mask = (((u64) 1 << inc) - 1) << (BITS (u64) - inc);
-	  u64 old = sa->replay_window & mask;
+	  u64 old = sa->replay_window & pow2_mask (inc);
 	  /* the number of packets we saw in this section of the window */
-	  u64 seen = count_set_bits (old);
-
-	  /*
-	   * the number we missed is the size of the window section
-	   * minus the number we saw.
-	   */
-	  n_lost = inc - seen;
+	  seen = count_set_bits (old);
+	  sa->replay_window =
+	    ((sa->replay_window) >> inc) | (1ULL << (window_size - 1));
 	}
-      sa->replay_window = ((sa->replay_window) << inc) | 1;
+
+      /*
+       * the number we missed is the size of the window section
+       * minus the number we saw.
+       */
+      n_lost = inc - seen;
     }
   else
     {
       /* holes in the replay window are lost packets */
-      n_lost = BITS (u64) - count_set_bits (sa->replay_window);
+      n_lost = window_size - IPSEC_SA_ANTI_REPLAY_WINDOW_N_SEEN (sa);
 
       /* any sequence numbers that now fall outside the window
        * are forever lost */
-      n_lost += inc - IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE;
+      n_lost += inc - window_size;
 
-      sa->replay_window = 1;
+      if (PREDICT_FALSE (ipsec_sa_is_set_ANTI_REPLAY_HUGE (sa)))
+	{
+	  clib_bitmap_zero (sa->replay_window_huge);
+	  clib_bitmap_set_no_check (sa->replay_window_huge,
+				    (sa->seq + inc) & (window_size - 1), 1);
+	}
+      else
+	{
+	  sa->replay_window = 1ULL << (window_size - 1);
+	}
     }
 
-  return (n_lost);
+  return n_lost;
 }
 
 /*
@@ -599,9 +763,10 @@ ipsec_sa_anti_replay_window_shift (ipsec_sa_t *sa, u32 inc)
  */
 always_inline u64
 ipsec_sa_anti_replay_advance (ipsec_sa_t *sa, u32 thread_index, u32 seq,
-			      u32 hi_seq)
+			      u32 hi_seq, bool ar_huge)
 {
   u64 n_lost = 0;
+  u32 window_size = IPSEC_SA_ANTI_REPLAY_WINDOW_SIZE_KNOWN_WIN (sa, ar_huge);
   u32 pos;
 
   if (ipsec_sa_is_set_USE_ESN (sa))
@@ -611,25 +776,33 @@ ipsec_sa_anti_replay_advance (ipsec_sa_t *sa, u32 thread_index, u32 seq,
       if (wrap == 0 && seq > sa->seq)
 	{
 	  pos = seq - sa->seq;
-	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos);
+	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos, ar_huge);
 	  sa->seq = seq;
 	}
       else if (wrap > 0)
 	{
-	  pos = ~seq + sa->seq + 1;
-	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos);
+	  pos = seq + ~sa->seq + 1;
+	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos, ar_huge);
 	  sa->seq = seq;
 	  sa->seq_hi = hi_seq;
 	}
       else if (wrap < 0)
 	{
 	  pos = ~seq + sa->seq + 1;
-	  sa->replay_window |= (1ULL << pos);
+	  if (ar_huge)
+	    clib_bitmap_set_no_check (sa->replay_window_huge,
+				      seq & (window_size - 1), 1);
+	  else
+	    sa->replay_window |= (1ULL << (window_size - 1 - pos));
 	}
       else
 	{
 	  pos = sa->seq - seq;
-	  sa->replay_window |= (1ULL << pos);
+	  if (ar_huge)
+	    clib_bitmap_set_no_check (sa->replay_window_huge,
+				      seq & (window_size - 1), 1);
+	  else
+	    sa->replay_window |= (1ULL << (window_size - 1 - pos));
 	}
     }
   else
@@ -637,13 +810,17 @@ ipsec_sa_anti_replay_advance (ipsec_sa_t *sa, u32 thread_index, u32 seq,
       if (seq > sa->seq)
 	{
 	  pos = seq - sa->seq;
-	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos);
+	  n_lost = ipsec_sa_anti_replay_window_shift (sa, pos, ar_huge);
 	  sa->seq = seq;
 	}
       else
 	{
 	  pos = sa->seq - seq;
-	  sa->replay_window |= (1ULL << pos);
+	  if (ar_huge)
+	    clib_bitmap_set_no_check (sa->replay_window_huge,
+				      seq & (window_size - 1), 1);
+	  else
+	    sa->replay_window |= (1ULL << (window_size - 1 - pos));
 	}
     }
 
diff --git a/src/vnet/ipsec/ipsec_test.c b/src/vnet/ipsec/ipsec_test.c
index 9b42ae71a80..86d09f18a5c 100644
--- a/src/vnet/ipsec/ipsec_test.c
+++ b/src/vnet/ipsec/ipsec_test.c
@@ -282,6 +282,12 @@ vl_api_ipsec_sad_entry_add_reply_t_handler (
 {
 }
 
+static void
+vl_api_ipsec_sad_entry_add_v2_reply_t_handler (
+  vl_api_ipsec_sad_entry_add_reply_t *mp)
+{
+}
+
 static int
 api_ipsec_sad_entry_del (vat_main_t *vat)
 {
@@ -342,6 +348,18 @@ api_ipsec_sa_v3_dump (vat_main_t *vat)
 }
 
 static int
+api_ipsec_sa_v4_dump (vat_main_t *vat)
+{
+  return -1;
+}
+
+static int
+api_ipsec_sa_v5_dump (vat_main_t *vat)
+{
+  return -1;
+}
+
+static int
 api_ipsec_tunnel_protect_dump (vat_main_t *vat)
 {
   return -1;
@@ -365,6 +383,12 @@ api_ipsec_sad_entry_add (vat_main_t *vat)
   return -1;
 }
 
+static int
+api_ipsec_sad_entry_add_v2 (vat_main_t *vat)
+{
+  return -1;
+}
+
 static void
 vl_api_ipsec_spd_entry_add_del_reply_t_handler (
   vl_api_ipsec_spd_entry_add_del_reply_t *mp)
@@ -394,6 +418,16 @@ vl_api_ipsec_sa_v3_details_t_handler (vl_api_ipsec_sa_v3_details_t *mp)
 {
 }
 
+static void
+vl_api_ipsec_sa_v4_details_t_handler (vl_api_ipsec_sa_v4_details_t *mp)
+{
+}
+
+static void
+vl_api_ipsec_sa_v5_details_t_handler (vl_api_ipsec_sa_v5_details_t *mp)
+{
+}
+
 static int
 api_ipsec_spd_interface_dump (vat_main_t *vat)
 {
@@ -446,17 +480,6 @@ api_ipsec_sa_dump (vat_main_t *vam)
 }
 
 static void
-vl_api_ipsec_sa_v4_details_t_handler (vl_api_ipsec_sa_v4_details_t *mp)
-{
-}
-
-static int
-api_ipsec_sa_v4_dump (vat_main_t *mp)
-{
-  return -1;
-}
-
-static void
 vl_api_ipsec_sa_details_t_handler (vl_api_ipsec_sa_details_t *mp)
 {
   vat_main_t *vam = &vat_main;
diff --git a/src/vnet/ipsec/ipsec_types.api b/src/vnet/ipsec/ipsec_types.api
index 9adcc6aa8eb..37c1141ab46 100644
--- a/src/vnet/ipsec/ipsec_types.api
+++ b/src/vnet/ipsec/ipsec_types.api
@@ -196,9 +196,6 @@ typedef ipsec_spd_entry_v2
 
 
 /** \brief IPsec: Security Association Database entry
-    @param client_index - opaque cookie to identify the sender
-    @param context - sender context, to match reply w/ request
-    @param is_add - add SAD entry if non-zero, else delete
     @param sad_id - sad id
     @param spi - security parameter index
     @param protocol - 0 = AH, 1 = ESP
@@ -206,6 +203,7 @@ typedef ipsec_spd_entry_v2
     @param crypto_key - crypto keying material
     @param integrity_algorithm - one of the supported algorithms
     @param integrity_key - integrity keying material
+    @param flags - SA flags (see ipsec_sad_flags above)
     @param tunnel_src_address - IPsec tunnel source address IPv6 if is_tunnel_ipv6 is non-zero, else IPv4. Only valid if is_tunnel is non-zero
     @param tunnel_dst_address - IPsec tunnel destination address IPv6 if is_tunnel_ipv6 is non-zero, else IPv4. Only valid if is_tunnel is non-zero
     @param tx_table_id - the FIB id used for encapsulated packets
@@ -290,6 +288,46 @@ typedef ipsec_sad_entry_v3
   u16 udp_dst_port [default=4500];
 };
 
+/** \brief IPsec: Security Association Database entry
+    @param sad_id - sad id
+    @param spi - security parameter index
+    @param protocol - 0 = AH, 1 = ESP
+    @param crypto_algorithm - a supported crypto algorithm
+    @param crypto_key - crypto keying material
+    @param integrity_algorithm - one of the supported algorithms
+    @param integrity_key - integrity keying material
+    @param flags - SA flags (see ipsec_sad_flags above)
+    @param tunnel - tunnel description (see vnet/tunnel/tunnel_types.api)
+    @param salt - for use with counter mode ciphers
+    @param udp_src_port - If using UDP Encapsulation, use this source port for
+                          TX. It is ignored for RX.
+    @param udp_dst_port - If using UDP Encapsulation, use this destination port
+                          for TX. Expect traffic on this port for RX.
+    @param anti_replay_window_size - AR window size to use. The supplied value is round up to the nearest power of 2.
+ */
+typedef ipsec_sad_entry_v4
+{
+  u32 sad_id;
+  u32 spi;
+
+  vl_api_ipsec_proto_t protocol;
+
+  vl_api_ipsec_crypto_alg_t crypto_algorithm;
+  vl_api_key_t crypto_key;
+
+  vl_api_ipsec_integ_alg_t integrity_algorithm;
+  vl_api_key_t integrity_key;
+
+  vl_api_ipsec_sad_flags_t flags;
+
+  vl_api_tunnel_t tunnel;
+
+  u32 salt;
+  u16 udp_src_port [default=4500];
+  u16 udp_dst_port [default=4500];
+
+  u32 anti_replay_window_size [default=64];
+};
 
 /*
  * Local Variables: