SNAT: IP fragmentation (VPP-890)

Translation of fragmented packets.

Change-Id: I9b1f2e9433ce273638080f32c2d3bff39c49899d
Signed-off-by: Matus Fabian <matfabia@cisco.com>

1 files changed, 493 insertions, 12 deletions

diff --git a/src/plugins/nat/nat64_in2out.c b/src/plugins/nat/nat64_in2out.c
index f78baff4e12..4f94575ebcc 100644
--- a/src/plugins/nat/nat64_in2out.c
+++ b/src/plugins/nat/nat64_in2out.c
@@ -18,6 +18,7 @@
  */
 
 #include <nat/nat64.h>
+#include <nat/nat_reass.h>
 #include <vnet/ip/ip6_to_ip4.h>
 #include <vnet/fib/fib_table.h>
 
@@ -45,14 +46,42 @@ format_nat64_in2out_trace (u8 * s, va_list * args)
   return s;
 }
 
+typedef struct
+{
+  u32 sw_if_index;
+  u32 next_index;
+  u8 cached;
+} nat64_in2out_reass_trace_t;
+
+static u8 *
+format_nat64_in2out_reass_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 *);
+  nat64_in2out_reass_trace_t *t =
+    va_arg (*args, nat64_in2out_reass_trace_t *);
+
+  s =
+    format (s, "NAT64-in2out-reass: sw_if_index %d, next index %d, status %s",
+	    t->sw_if_index, t->next_index,
+	    t->cached ? "cached" : "translated");
+
+  return s;
+}
+
 vlib_node_registration_t nat64_in2out_node;
 vlib_node_registration_t nat64_in2out_slowpath_node;
+vlib_node_registration_t nat64_in2out_reass_node;
+
+#define foreach_nat64_in2out_error                       \
+_(UNSUPPORTED_PROTOCOL, "unsupported protocol")          \
+_(IN2OUT_PACKETS, "good in2out packets processed")       \
+_(NO_TRANSLATION, "no translation")                      \
+_(UNKNOWN, "unknown")                                    \
+_(DROP_FRAGMENT, "Drop fragment")                        \
+_(MAX_REASS, "Maximum reassemblies exceeded")            \
+_(MAX_FRAG, "Maximum fragments per reassembly exceeded")
 
-#define foreach_nat64_in2out_error                 \
-_(UNSUPPORTED_PROTOCOL, "unsupported protocol")    \
-_(IN2OUT_PACKETS, "good in2out packets processed") \
-_(NO_TRANSLATION, "no translation")                \
-_(UNKNOWN, "unknown")
 
 typedef enum
 {
@@ -74,6 +103,7 @@ typedef enum
   NAT64_IN2OUT_NEXT_IP6_LOOKUP,
   NAT64_IN2OUT_NEXT_DROP,
   NAT64_IN2OUT_NEXT_SLOWPATH,
+  NAT64_IN2OUT_NEXT_REASS,
   NAT64_IN2OUT_N_NEXT,
 } nat64_in2out_next_t;
 
@@ -936,13 +966,6 @@ nat64_in2out_node_fn_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  proto0 = ip_proto_to_snat_proto (l4_protocol0);
-	  if (frag_offset0 != 0)
-	    {
-	      next0 = NAT64_IN2OUT_NEXT_DROP;
-	      b0->error =
-		node->errors[NAT64_IN2OUT_ERROR_UNSUPPORTED_PROTOCOL];
-	      goto trace0;
-	    }
 
 	  if (is_slow_path)
 	    {
@@ -979,6 +1002,13 @@ nat64_in2out_node_fn_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 		}
 	    }
 
+	  if (PREDICT_FALSE
+	      (ip60->protocol == IP_PROTOCOL_IPV6_FRAGMENTATION))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_REASS;
+	      goto trace0;
+	    }
+
 	  if (proto0 == SNAT_PROTOCOL_ICMP)
 	    {
 	      if (is_hairpinning (&ip60->dst_address))
@@ -1073,6 +1103,7 @@ VLIB_REGISTER_NODE (nat64_in2out_node) = {
     [NAT64_IN2OUT_NEXT_IP4_LOOKUP] = "ip4-lookup",
     [NAT64_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [NAT64_IN2OUT_NEXT_SLOWPATH] = "nat64-in2out-slowpath",
+    [NAT64_IN2OUT_NEXT_REASS] = "nat64-in2out-reass",
   },
 };
 /* *INDENT-ON* */
@@ -1102,6 +1133,7 @@ VLIB_REGISTER_NODE (nat64_in2out_slowpath_node) = {
     [NAT64_IN2OUT_NEXT_IP4_LOOKUP] = "ip4-lookup",
     [NAT64_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
     [NAT64_IN2OUT_NEXT_SLOWPATH] = "nat64-in2out-slowpath",
+    [NAT64_IN2OUT_NEXT_REASS] = "nat64-in2out-reass",
   },
 };
 /* *INDENT-ON* */
@@ -1109,6 +1141,455 @@ VLIB_REGISTER_NODE (nat64_in2out_slowpath_node) = {
 VLIB_NODE_FUNCTION_MULTIARCH (nat64_in2out_slowpath_node,
 			      nat64_in2out_slowpath_node_fn);
 
+typedef struct nat64_in2out_frag_set_ctx_t_
+{
+  vlib_main_t *vm;
+  u32 sess_index;
+  u16 l4_offset;
+  u8 proto;
+  u8 first_frag;
+} nat64_in2out_frag_set_ctx_t;
+
+static int
+nat64_in2out_frag_set_cb (ip6_header_t * ip6, ip4_header_t * ip4, void *arg)
+{
+  nat64_main_t *nm = &nat64_main;
+  nat64_in2out_frag_set_ctx_t *ctx = arg;
+  nat64_db_st_entry_t *ste;
+  nat64_db_bib_entry_t *bibe;
+  udp_header_t *udp;
+
+  ste = nat64_db_st_entry_by_index (&nm->db, ctx->proto, ctx->sess_index);
+  if (!ste)
+    return -1;
+
+  bibe = nat64_db_bib_entry_by_index (&nm->db, ctx->proto, ste->bibe_index);
+  if (!bibe)
+    return -1;
+
+  nat64_session_reset_timeout (ste, ctx->vm);
+
+  if (ctx->first_frag)
+    {
+      udp = (udp_header_t *) u8_ptr_add (ip6, ctx->l4_offset);
+
+      if (ctx->proto == IP_PROTOCOL_TCP)
+	{
+	  u16 *checksum;
+	  ip_csum_t csum;
+	  tcp_header_t *tcp = (tcp_header_t *) udp;
+
+	  checksum = &tcp->checksum;
+	  csum = ip_csum_sub_even (*checksum, tcp->src_port);
+	  csum = ip_csum_sub_even (csum, ip6->src_address.as_u64[0]);
+	  csum = ip_csum_sub_even (csum, ip6->src_address.as_u64[1]);
+	  csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[0]);
+	  csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[1]);
+	  csum = ip_csum_add_even (csum, bibe->out_port);
+	  csum = ip_csum_add_even (csum, bibe->out_addr.as_u32);
+	  csum = ip_csum_add_even (csum, ste->out_r_addr.as_u32);
+	  *checksum = ip_csum_fold (csum);
+	}
+
+      udp->src_port = bibe->out_port;
+    }
+
+  ip4->src_address.as_u32 = bibe->out_addr.as_u32;
+  ip4->dst_address.as_u32 = ste->out_r_addr.as_u32;
+
+  return 0;
+}
+
+static int
+nat64_in2out_frag_hairpinning (vlib_buffer_t * b, ip6_header_t * ip6,
+			       nat64_in2out_frag_set_ctx_t * ctx)
+{
+  nat64_main_t *nm = &nat64_main;
+  nat64_db_st_entry_t *ste;
+  nat64_db_bib_entry_t *bibe;
+  udp_header_t *udp = (udp_header_t *) u8_ptr_add (ip6, ctx->l4_offset);
+  tcp_header_t *tcp = (tcp_header_t *) udp;
+  u16 sport = udp->src_port;
+  u16 dport = udp->dst_port;
+  u16 *checksum;
+  ip_csum_t csum;
+  ip46_address_t saddr, daddr;
+
+  if (ctx->first_frag)
+    {
+      if (ctx->proto == IP_PROTOCOL_UDP)
+	checksum = &udp->checksum;
+      else
+	checksum = &tcp->checksum;
+
+      csum = ip_csum_sub_even (*checksum, ip6->src_address.as_u64[0]);
+      csum = ip_csum_sub_even (csum, ip6->src_address.as_u64[1]);
+      csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[0]);
+      csum = ip_csum_sub_even (csum, ip6->dst_address.as_u64[1]);
+      csum = ip_csum_sub_even (csum, sport);
+      csum = ip_csum_sub_even (csum, dport);
+    }
+
+  ste = nat64_db_st_entry_by_index (&nm->db, ctx->proto, ctx->sess_index);
+  if (!ste)
+    return -1;
+
+  bibe = nat64_db_bib_entry_by_index (&nm->db, ctx->proto, ste->bibe_index);
+  if (!bibe)
+    return -1;
+
+  nat64_session_reset_timeout (ste, ctx->vm);
+
+  sport = bibe->out_port;
+  dport = ste->r_port;
+
+  nat64_compose_ip6 (&ip6->src_address, &bibe->out_addr, bibe->fib_index);
+
+  memset (&saddr, 0, sizeof (saddr));
+  memset (&daddr, 0, sizeof (daddr));
+  saddr.ip4.as_u32 = bibe->out_addr.as_u32;
+  daddr.ip4.as_u32 = ste->out_r_addr.as_u32;
+
+  ste =
+    nat64_db_st_entry_find (&nm->db, &daddr, &saddr, dport, sport, ctx->proto,
+			    0, 0);
+
+  if (ste)
+    {
+      bibe =
+	nat64_db_bib_entry_by_index (&nm->db, ctx->proto, ste->bibe_index);
+      if (!bibe)
+	return -1;
+    }
+  else
+    {
+      bibe =
+	nat64_db_bib_entry_find (&nm->db, &daddr, dport, ctx->proto, 0, 0);
+
+      if (!bibe)
+	return -1;
+
+      ste =
+	nat64_db_st_entry_create (&nm->db, bibe, &ip6->src_address,
+				  &saddr.ip4, sport);
+    }
+
+  ip6->dst_address.as_u64[0] = bibe->in_addr.as_u64[0];
+  ip6->dst_address.as_u64[1] = bibe->in_addr.as_u64[1];
+
+  if (ctx->first_frag)
+    {
+      udp->dst_port = bibe->in_port;
+      udp->src_port = sport;
+      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[0]);
+      csum = ip_csum_add_even (csum, ip6->src_address.as_u64[1]);
+      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[0]);
+      csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[1]);
+      csum = ip_csum_add_even (csum, udp->src_port);
+      csum = ip_csum_add_even (csum, udp->dst_port);
+      *checksum = ip_csum_fold (csum);
+    }
+
+  return 0;
+}
+
+static uword
+nat64_in2out_reass_node_fn (vlib_main_t * vm,
+			    vlib_node_runtime_t * node, vlib_frame_t * frame)
+{
+  u32 n_left_from, *from, *to_next;
+  nat64_in2out_next_t next_index;
+  u32 pkts_processed = 0;
+  u32 *fragments_to_drop = 0;
+  u32 *fragments_to_loopback = 0;
+  nat64_main_t *nm = &nat64_main;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = frame->n_vectors;
+  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 bi0;
+	  vlib_buffer_t *b0;
+	  u32 next0;
+	  u8 cached0 = 0;
+	  ip6_header_t *ip60;
+	  u16 l4_offset0, frag_offset0;
+	  u8 l4_protocol0;
+	  nat_reass_ip6_t *reass0;
+	  ip6_frag_hdr_t *frag0;
+	  nat64_db_bib_entry_t *bibe0;
+	  nat64_db_st_entry_t *ste0;
+	  udp_header_t *udp0;
+	  snat_protocol_t proto0;
+	  u32 sw_if_index0, fib_index0;
+	  ip46_address_t saddr0, daddr0;
+	  nat64_in2out_frag_set_ctx_t ctx0;
+
+	  /* speculatively enqueue b0 to the current next frame */
+	  bi0 = from[0];
+	  to_next[0] = bi0;
+	  from += 1;
+	  to_next += 1;
+	  n_left_from -= 1;
+	  n_left_to_next -= 1;
+
+	  b0 = vlib_get_buffer (vm, bi0);
+	  next0 = NAT64_IN2OUT_NEXT_IP4_LOOKUP;
+
+	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
+	  fib_index0 =
+	    fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP6,
+						 sw_if_index0);
+
+	  if (PREDICT_FALSE (nat_reass_is_drop_frag (1)))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_DROP;
+	      b0->error = node->errors[NAT64_IN2OUT_ERROR_DROP_FRAGMENT];
+	      goto trace0;
+	    }
+
+	  ip60 = (ip6_header_t *) vlib_buffer_get_current (b0);
+
+	  if (PREDICT_FALSE
+	      (ip6_parse
+	       (ip60, b0->current_length, &l4_protocol0, &l4_offset0,
+		&frag_offset0)))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_DROP;
+	      b0->error = node->errors[NAT64_IN2OUT_ERROR_UNKNOWN];
+	      goto trace0;
+	    }
+
+	  if (PREDICT_FALSE
+	      (!(l4_protocol0 == IP_PROTOCOL_TCP
+		 || l4_protocol0 == IP_PROTOCOL_UDP)))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_DROP;
+	      b0->error = node->errors[NAT64_IN2OUT_ERROR_DROP_FRAGMENT];
+	      goto trace0;
+	    }
+
+	  udp0 = (udp_header_t *) u8_ptr_add (ip60, l4_offset0);
+	  frag0 = (ip6_frag_hdr_t *) u8_ptr_add (ip60, frag_offset0);
+	  proto0 = ip_proto_to_snat_proto (l4_protocol0);
+
+	  reass0 = nat_ip6_reass_find_or_create (ip60->src_address,
+						 ip60->dst_address,
+						 frag0->identification,
+						 l4_protocol0,
+						 1, &fragments_to_drop);
+
+	  if (PREDICT_FALSE (!reass0))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_DROP;
+	      b0->error = node->errors[NAT64_IN2OUT_ERROR_MAX_REASS];
+	      goto trace0;
+	    }
+
+	  if (PREDICT_TRUE (ip6_frag_hdr_offset (frag0)))
+	    {
+	      ctx0.first_frag = 0;
+	      if (PREDICT_FALSE (reass0->sess_index == (u32) ~ 0))
+		{
+		  if (nat_ip6_reass_add_fragment (reass0, bi0))
+		    {
+		      b0->error = node->errors[NAT64_IN2OUT_ERROR_MAX_FRAG];
+		      next0 = NAT64_IN2OUT_NEXT_DROP;
+		      goto trace0;
+		    }
+		  cached0 = 1;
+		  goto trace0;
+		}
+	    }
+	  else
+	    {
+	      ctx0.first_frag = 1;
+
+	      saddr0.as_u64[0] = ip60->src_address.as_u64[0];
+	      saddr0.as_u64[1] = ip60->src_address.as_u64[1];
+	      daddr0.as_u64[0] = ip60->dst_address.as_u64[0];
+	      daddr0.as_u64[1] = ip60->dst_address.as_u64[1];
+
+	      ste0 =
+		nat64_db_st_entry_find (&nm->db, &saddr0, &daddr0,
+					udp0->src_port, udp0->dst_port,
+					l4_protocol0, fib_index0, 1);
+	      if (!ste0)
+		{
+		  bibe0 =
+		    nat64_db_bib_entry_find (&nm->db, &saddr0, udp0->src_port,
+					     l4_protocol0, fib_index0, 1);
+		  if (!bibe0)
+		    {
+		      u16 out_port0;
+		      ip4_address_t out_addr0;
+		      if (nat64_alloc_out_addr_and_port
+			  (fib_index0, proto0, &out_addr0, &out_port0))
+			{
+			  next0 = NAT64_IN2OUT_NEXT_DROP;
+			  b0->error =
+			    node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
+			  goto trace0;
+			}
+
+		      bibe0 =
+			nat64_db_bib_entry_create (&nm->db,
+						   &ip60->src_address,
+						   &out_addr0, udp0->src_port,
+						   clib_host_to_net_u16
+						   (out_port0), fib_index0,
+						   l4_protocol0, 0);
+		      if (!bibe0)
+			{
+			  next0 = NAT64_IN2OUT_NEXT_DROP;
+			  b0->error =
+			    node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
+			  goto trace0;
+			}
+		    }
+		  nat64_extract_ip4 (&ip60->dst_address, &daddr0.ip4,
+				     fib_index0);
+		  ste0 =
+		    nat64_db_st_entry_create (&nm->db, bibe0,
+					      &ip60->dst_address, &daddr0.ip4,
+					      udp0->dst_port);
+		  if (!ste0)
+		    {
+		      next0 = NAT64_IN2OUT_NEXT_DROP;
+		      b0->error =
+			node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
+		      goto trace0;
+		    }
+		}
+	      reass0->sess_index =
+		nat64_db_st_entry_get_index (&nm->db, ste0);
+
+	      nat_ip6_reass_get_frags (reass0, &fragments_to_loopback);
+	    }
+
+	  ctx0.sess_index = reass0->sess_index;
+	  ctx0.proto = l4_protocol0;
+	  ctx0.vm = vm;
+	  ctx0.l4_offset = l4_offset0;
+
+	  if (PREDICT_FALSE (is_hairpinning (&ip60->dst_address)))
+	    {
+	      next0 = NAT64_IN2OUT_NEXT_IP6_LOOKUP;
+	      if (nat64_in2out_frag_hairpinning (b0, ip60, &ctx0))
+		{
+		  next0 = NAT64_IN2OUT_NEXT_DROP;
+		  b0->error = node->errors[NAT64_IN2OUT_ERROR_NO_TRANSLATION];
+		}
+	      goto trace0;
+	    }
+	  else
+	    {
+	      if (ip6_to_ip4_fragmented (b0, nat64_in2out_frag_set_cb, &ctx0))
+		{
+		  next0 = NAT64_IN2OUT_NEXT_DROP;
+		  b0->error = node->errors[NAT64_IN2OUT_ERROR_UNKNOWN];
+		  goto trace0;
+		}
+	    }
+
+	trace0:
+	  if (PREDICT_FALSE
+	      ((node->flags & VLIB_NODE_FLAG_TRACE)
+	       && (b0->flags & VLIB_BUFFER_IS_TRACED)))
+	    {
+	      nat64_in2out_reass_trace_t *t =
+		vlib_add_trace (vm, node, b0, sizeof (*t));
+	      t->cached = cached0;
+	      t->sw_if_index = sw_if_index0;
+	      t->next_index = next0;
+	    }
+
+	  if (cached0)
+	    {
+	      n_left_to_next++;
+	      to_next--;
+	    }
+	  else
+	    {
+	      pkts_processed += next0 != NAT64_IN2OUT_NEXT_DROP;
+
+	      /* verify speculative enqueue, maybe switch current next frame */
+	      vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
+					       to_next, n_left_to_next,
+					       bi0, next0);
+	    }
+
+	  if (n_left_from == 0 && vec_len (fragments_to_loopback))
+	    {
+	      from = vlib_frame_vector_args (frame);
+	      u32 len = vec_len (fragments_to_loopback);
+	      if (len <= VLIB_FRAME_SIZE)
+		{
+		  clib_memcpy (from, fragments_to_loopback,
+			       sizeof (u32) * len);
+		  n_left_from = len;
+		  vec_reset_length (fragments_to_loopback);
+		}
+	      else
+		{
+		  clib_memcpy (from,
+			       fragments_to_loopback + (len -
+							VLIB_FRAME_SIZE),
+			       sizeof (u32) * VLIB_FRAME_SIZE);
+		  n_left_from = VLIB_FRAME_SIZE;
+		  _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
+		}
+	    }
+	}
+
+      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
+    }
+
+  vlib_node_increment_counter (vm, nat64_in2out_reass_node.index,
+			       NAT64_IN2OUT_ERROR_IN2OUT_PACKETS,
+			       pkts_processed);
+
+  nat_send_all_to_node (vm, fragments_to_drop, node,
+			&node->errors[NAT64_IN2OUT_ERROR_DROP_FRAGMENT],
+			NAT64_IN2OUT_NEXT_DROP);
+
+  vec_free (fragments_to_drop);
+  vec_free (fragments_to_loopback);
+  return frame->n_vectors;
+}
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (nat64_in2out_reass_node) = {
+  .function = nat64_in2out_reass_node_fn,
+  .name = "nat64-in2out-reass",
+  .vector_size = sizeof (u32),
+  .format_trace = format_nat64_in2out_reass_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = ARRAY_LEN (nat64_in2out_error_strings),
+  .error_strings = nat64_in2out_error_strings,
+  .n_next_nodes = NAT64_IN2OUT_N_NEXT,
+  /* edit / add dispositions here */
+  .next_nodes = {
+    [NAT64_IN2OUT_NEXT_DROP] = "error-drop",
+    [NAT64_IN2OUT_NEXT_IP4_LOOKUP] = "ip4-lookup",
+    [NAT64_IN2OUT_NEXT_IP6_LOOKUP] = "ip6-lookup",
+    [NAT64_IN2OUT_NEXT_SLOWPATH] = "nat64-in2out-slowpath",
+    [NAT64_IN2OUT_NEXT_REASS] = "nat64-in2out-reass",
+  },
+};
+/* *INDENT-ON* */
+
+VLIB_NODE_FUNCTION_MULTIARCH (nat64_in2out_reass_node,
+			      nat64_in2out_reass_node_fn);
+
 /*
  * fd.io coding-style-patch-verification: ON
  *