cnat: add input feature node

This allows to configure nat on a per-interface basis. Special care must
be taken to ensure the configuration remains consistent.

Type: feature

Change-Id: I352b2dce182e09d30813ce958333bb1ff37d9b4e
Signed-off-by: Aloys Augustin <aloaugus@cisco.com>
Signed-off-by: Nathan Skrzypczak <nathan.skrzypczak@gmail.com>

6 files changed, 507 insertions, 0 deletions

diff --git a/src/plugins/cnat/CMakeLists.txt b/src/plugins/cnat/CMakeLists.txt
index 95b59e97d10..6eb5968e703 100644
--- a/src/plugins/cnat/CMakeLists.txt
+++ b/src/plugins/cnat/CMakeLists.txt
@@ -17,6 +17,7 @@ add_vpp_plugin(cnat
   cnat_client.c
   cnat_node_snat.c
   cnat_node_vip.c
+  cnat_node_feature.c
   cnat_scanner.c
   cnat_session.c
   cnat_translation.c
diff --git a/src/plugins/cnat/cnat.api b/src/plugins/cnat/cnat.api
index 2b79e0d1b8b..a5df8b1e578 100644
--- a/src/plugins/cnat/cnat.api
+++ b/src/plugins/cnat/cnat.api
@@ -167,6 +167,17 @@ autoreply define cnat_add_del_snat_prefix
   vl_api_prefix_t prefix;
 };
 
+enum cnat_snat_policies:u32
+{
+  CNAT_SNAT_POLICY_NONE = 1,
+};
+
+autoreply define cnat_set_snat_policy
+{
+  u32 client_index;
+  u32 context;
+  vl_api_cnat_snat_policies_t policy;
+};
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/plugins/cnat/cnat_api.c b/src/plugins/cnat/cnat_api.c
index 99d9c729282..652e5c09d1a 100644
--- a/src/plugins/cnat/cnat_api.c
+++ b/src/plugins/cnat/cnat_api.c
@@ -337,6 +337,23 @@ static void
   REPLY_MACRO (VL_API_CNAT_ADD_DEL_SNAT_PREFIX_REPLY);
 }
 
+static void
+vl_api_cnat_set_snat_policy_t_handler (vl_api_cnat_set_snat_policy_t *mp)
+{
+  vl_api_cnat_set_snat_policy_reply_t *rmp;
+  int rv = 0;
+  vl_api_cnat_snat_policies_t policy = clib_net_to_host_u32 (mp->policy);
+  switch (policy)
+    {
+    case CNAT_SNAT_POLICY_NONE:
+      cnat_set_snat_policy (NULL);
+      break;
+    default:
+      rv = 1;
+    }
+
+  REPLY_MACRO (VL_API_CNAT_SET_SNAT_POLICY_REPLY);
+}
 #include <cnat/cnat.api.c>
 
 static clib_error_t *
diff --git a/src/plugins/cnat/cnat_node_feature.c b/src/plugins/cnat/cnat_node_feature.c
new file mode 100644
index 00000000000..10293de5069
--- /dev/null
+++ b/src/plugins/cnat/cnat_node_feature.c
@@ -0,0 +1,409 @@
+/*
+ * Copyright (c) 2020 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 <vlibmemory/api.h>
+#include <cnat/cnat_node.h>
+#include <cnat/cnat_translation.h>
+#include <cnat/cnat_inline.h>
+#include <cnat/cnat_src_policy.h>
+#include <cnat/cnat_snat.h>
+
+#include <vnet/dpo/load_balance.h>
+#include <vnet/dpo/load_balance_map.h>
+
+#include <vnet/ip/ip4_inlines.h>
+#include <vnet/ip/ip6_inlines.h>
+
+typedef enum cnat_feature_next_
+{
+  CNAT_FEATURE_NEXT_DROP,
+  CNAT_FEATURE_N_NEXT,
+} cnat_feature_next_t;
+
+vlib_node_registration_t cnat_input_feature_ip4_node;
+vlib_node_registration_t cnat_input_feature_ip6_node;
+vlib_node_registration_t cnat_output_feature_ip4_node;
+vlib_node_registration_t cnat_output_feature_ip6_node;
+
+always_inline uword
+cnat_input_feature_fn (vlib_main_t *vm, vlib_node_runtime_t *node,
+		       vlib_buffer_t *b, cnat_node_ctx_t *ctx,
+		       int session_not_found, cnat_session_t *session)
+{
+  vlib_combined_counter_main_t *cntm = &cnat_translation_counters;
+  const cnat_translation_t *ct = NULL;
+  ip4_header_t *ip4 = NULL;
+  ip_protocol_t iproto;
+  ip6_header_t *ip6 = NULL;
+  udp_header_t *udp0;
+  cnat_client_t *cc;
+  u32 next0;
+  index_t cti;
+  u8 trace_flags = 0;
+
+  /* By default follow arc default next */
+  vnet_feature_next (&next0, b);
+
+  if (AF_IP4 == ctx->af)
+    {
+      ip4 = vlib_buffer_get_current (b);
+      iproto = ip4->protocol;
+      udp0 = (udp_header_t *) (ip4 + 1);
+      cc = cnat_client_ip4_find (
+	&ip4->dst_address); /* TODO do this only if no session? */
+    }
+  else
+    {
+      ip6 = vlib_buffer_get_current (b);
+      iproto = ip6->protocol;
+      udp0 = (udp_header_t *) (ip6 + 1);
+      cc = cnat_client_ip6_find (&ip6->dst_address); /* TODO: same as above */
+    }
+
+  if (session->key.cs_proto == 0)
+    goto trace;
+
+  if (!session_not_found)
+    /* session table hit */
+    cnat_timestamp_update (session->value.cs_ts_index, ctx->now);
+  else if (!cc)
+    goto trace; /* dst address is not a vip */
+  else
+    {
+      ct = cnat_find_translation (
+	cc->parent_cci, clib_host_to_net_u16 (udp0->dst_port), iproto);
+      if (NULL == ct)
+	/* Dont translate  */
+	/* TODO: create identity session to avoid slowpath ? */
+	goto trace;
+
+      /* New flow, create the sessions */
+      const load_balance_t *lb0;
+      cnat_ep_trk_t *trk0;
+      u32 rsession_flags = CNAT_SESSION_FLAG_NO_CLIENT;
+      u32 dpoi_index = -1;
+
+      lb0 = load_balance_get (ct->ct_lb.dpoi_index);
+      if (!lb0->lb_n_buckets)
+	/* Can't translate TODO: should drop / reject? */
+	goto trace;
+
+      /* session table miss */
+      trk0 = cnat_load_balance (ct, ctx->af, ip4, ip6, &dpoi_index);
+      if (PREDICT_FALSE (NULL == trk0))
+	{
+	  /* Dont translate & Follow the fib programming */
+	  vnet_buffer (b)->ip.adj_index[VLIB_TX] = cc->cc_parent.dpoi_index;
+	  next0 = cc->cc_parent.dpoi_next_node;
+	  goto trace;
+	}
+
+      ip46_address_copy (&session->value.cs_ip[VLIB_TX],
+			 &trk0->ct_ep[VLIB_TX].ce_ip.ip);
+
+      /* never source nat in this node */
+      if (AF_IP4 == ctx->af)
+	ip46_address_set_ip4 (&session->value.cs_ip[VLIB_RX],
+			      &ip4->src_address);
+      else
+	ip46_address_set_ip6 (&session->value.cs_ip[VLIB_RX],
+			      &ip6->src_address);
+
+      session->value.cs_port[VLIB_TX] =
+	clib_host_to_net_u16 (trk0->ct_ep[VLIB_TX].ce_port);
+      session->value.cs_port[VLIB_RX] = udp0->src_port;
+
+      const dpo_id_t *dpo0;
+      const load_balance_t *lb1;
+      fib_entry_t *fib_entry;
+      fib_entry = fib_entry_get (trk0->ct_fei);
+
+      lb1 = load_balance_get (fib_entry->fe_lb /*[fct] */.dpoi_index);
+      dpo0 = load_balance_get_bucket_i (lb1, 0);
+
+      session->value.dpoi_next_node = dpo0->dpoi_next_node;
+      session->value.cs_lbi = dpo0->dpoi_index;
+
+      if (trk0->ct_flags & CNAT_TRK_FLAG_NO_NAT)
+	session->value.flags |= CNAT_SESSION_FLAG_NO_NAT;
+
+      /* refcnt session in current client */
+      cnat_client_cnt_session (cc);
+      cnat_session_create (session, ctx, CNAT_LOCATION_OUTPUT, rsession_flags);
+      trace_flags |= CNAT_TRACE_SESSION_CREATED;
+    }
+
+  next0 = session->value.dpoi_next_node;
+  vnet_buffer (b)->ip.adj_index[VLIB_TX] = session->value.cs_lbi;
+
+  if (session->value.flags & CNAT_SESSION_FLAG_NO_NAT)
+    goto trace;
+
+  if (AF_IP4 == ctx->af)
+    cnat_translation_ip4 (session, ip4, udp0);
+  else
+    cnat_translation_ip6 (session, ip6, udp0);
+
+  if (NULL != ct)
+    {
+      cti = ct - cnat_translation_pool;
+      vlib_increment_combined_counter (cntm, ctx->thread_index, cti, 1,
+				       vlib_buffer_length_in_chain (vm, b));
+    }
+
+trace:
+  if (PREDICT_FALSE (ctx->do_trace))
+    {
+      trace_flags |= session_not_found ? 0 : CNAT_TRACE_SESSION_FOUND;
+      cnat_add_trace (vm, node, b, session, ct, trace_flags);
+    }
+  return next0;
+}
+
+VLIB_NODE_FN (cnat_input_feature_ip4_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_input_feature_fn, AF_IP4,
+			     CNAT_LOCATION_INPUT, 1 /* do_trace */);
+  return cnat_node_inline (vm, node, frame, cnat_input_feature_fn, AF_IP4,
+			   CNAT_LOCATION_INPUT, 0 /* do_trace */);
+}
+
+VLIB_REGISTER_NODE (cnat_input_feature_ip4_node) = {
+  .name = "cnat-input-ip4",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = CNAT_N_ERROR,
+  .error_strings = cnat_error_strings,
+  .n_next_nodes = IP_LOOKUP_N_NEXT,
+  .next_nodes = IP4_LOOKUP_NEXT_NODES,
+};
+
+VNET_FEATURE_INIT (cnat_in_ip4_feature, static) = {
+  .arc_name = "ip4-unicast",
+  .node_name = "cnat-input-ip4",
+  .runs_before = VNET_FEATURES ("acl-plugin-in-ip4-fa"),
+};
+
+VLIB_NODE_FN (cnat_input_feature_ip6_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_input_feature_fn, AF_IP6,
+			     CNAT_LOCATION_INPUT, 1 /* do_trace */);
+  return cnat_node_inline (vm, node, frame, cnat_input_feature_fn, AF_IP6,
+			   CNAT_LOCATION_INPUT, 0 /* do_trace */);
+}
+
+VLIB_REGISTER_NODE (cnat_input_feature_ip6_node) = {
+  .name = "cnat-input-ip6",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = CNAT_N_ERROR,
+  .error_strings = cnat_error_strings,
+  .n_next_nodes = CNAT_FEATURE_N_NEXT,
+  .next_nodes = {
+      [CNAT_FEATURE_NEXT_DROP] = "error-drop",
+  },
+};
+
+VNET_FEATURE_INIT (cnat_in_ip6_feature, static) = {
+  .arc_name = "ip6-unicast",
+  .node_name = "cnat-input-ip6",
+  .runs_before = VNET_FEATURES ("acl-plugin-in-ip6-fa"),
+};
+
+/* output feature node, creates snat sessions when required and
+ * translates back for existing sessions */
+always_inline uword
+cnat_output_feature_fn (vlib_main_t *vm, vlib_node_runtime_t *node,
+			vlib_buffer_t *b, cnat_node_ctx_t *ctx,
+			int session_not_found, cnat_session_t *session)
+{
+  cnat_main_t *cm = &cnat_main;
+  cnat_snat_policy_main_t *cms = &cnat_snat_policy_main;
+  ip4_header_t *ip4 = NULL;
+  ip_protocol_t iproto;
+  ip6_header_t *ip6 = NULL;
+  udp_header_t *udp0;
+  u32 iph_offset = 0;
+  u32 next0;
+  u16 sport;
+  u8 do_snat = 0;
+  u8 trace_flags = 0;
+  int rv;
+
+  /* By default follow arc default next */
+  vnet_feature_next (&next0, b);
+  iph_offset = vnet_buffer (b)->ip.save_rewrite_length;
+
+  if (AF_IP4 == ctx->af)
+    {
+      ip4 = (ip4_header_t *) ((u8 *) vlib_buffer_get_current (b) + iph_offset);
+      iproto = ip4->protocol;
+      udp0 = (udp_header_t *) (ip4 + 1);
+    }
+  else
+    {
+      ip6 = (ip6_header_t *) ((u8 *) vlib_buffer_get_current (b) + iph_offset);
+      iproto = ip6->protocol;
+      udp0 = (udp_header_t *) (ip6 + 1);
+    }
+
+  if (session->key.cs_proto == 0)
+    goto trace;
+
+  if (!session_not_found)
+    {
+      /* session table hit */
+      cnat_timestamp_update (session->value.cs_ts_index, ctx->now);
+    }
+  else if (!cms->snat_policy)
+    goto trace;
+  else
+    {
+      /* TODO: handle errors? */
+      cms->snat_policy (vm, b, session, ctx, &do_snat);
+      if (do_snat != 1)
+	goto trace;
+
+      if (AF_IP4 == ctx->af)
+	{
+	  if (ip_address_is_zero (&cm->snat_ip4.ce_ip))
+	    goto trace;
+
+	  ip46_address_set_ip4 (&session->value.cs_ip[VLIB_RX],
+				&ip_addr_v4 (&cm->snat_ip4.ce_ip));
+	  ip46_address_set_ip4 (&session->value.cs_ip[VLIB_TX],
+				&ip4->dst_address);
+	}
+      else
+	{
+	  if (ip_address_is_zero (&cm->snat_ip6.ce_ip))
+	    goto trace;
+
+	  ip46_address_set_ip6 (&session->value.cs_ip[VLIB_RX],
+				&ip_addr_v6 (&cm->snat_ip6.ce_ip));
+	  ip46_address_set_ip6 (&session->value.cs_ip[VLIB_TX],
+				&ip6->dst_address);
+	}
+      sport = 0;
+      rv = cnat_allocate_port (&sport, iproto);
+      if (rv)
+	{
+	  vlib_node_increment_counter (vm, cnat_output_feature_ip6_node.index,
+				       CNAT_ERROR_EXHAUSTED_PORTS, 1);
+	  next0 = CNAT_FEATURE_NEXT_DROP;
+	  goto trace;
+	}
+      session->value.cs_port[VLIB_RX] = sport;
+      session->value.cs_port[VLIB_TX] = sport;
+      if (iproto == IP_PROTOCOL_TCP || iproto == IP_PROTOCOL_UDP)
+	session->value.cs_port[VLIB_TX] = udp0->dst_port;
+
+      session->value.cs_lbi = INDEX_INVALID;
+      session->value.flags =
+	CNAT_SESSION_FLAG_NO_CLIENT | CNAT_SESSION_FLAG_ALLOC_PORT;
+
+      trace_flags |= CNAT_TRACE_SESSION_CREATED;
+      cnat_session_create (session, ctx, CNAT_LOCATION_INPUT,
+			   CNAT_SESSION_FLAG_NO_CLIENT);
+    }
+
+  if (AF_IP4 == ctx->af)
+    cnat_translation_ip4 (session, ip4, udp0);
+  else
+    cnat_translation_ip6 (session, ip6, udp0);
+
+trace:
+  if (PREDICT_FALSE (ctx->do_trace))
+    {
+      trace_flags |= do_snat ? 0 : CNAT_TRACE_NO_NAT;
+      trace_flags |= session_not_found ? 0 : CNAT_TRACE_SESSION_FOUND;
+      cnat_add_trace (vm, node, b, session, NULL, trace_flags);
+    }
+  return next0;
+}
+
+VLIB_NODE_FN (cnat_output_feature_ip4_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_output_feature_fn, AF_IP4,
+			     CNAT_LOCATION_OUTPUT, 1 /* do_trace */);
+  return cnat_node_inline (vm, node, frame, cnat_output_feature_fn, AF_IP4,
+			   CNAT_LOCATION_OUTPUT, 0 /* do_trace */);
+}
+
+VLIB_REGISTER_NODE (cnat_output_feature_ip4_node) = {
+  .name = "cnat-output-ip4",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = CNAT_N_ERROR,
+  .error_strings = cnat_error_strings,
+  .n_next_nodes = CNAT_FEATURE_N_NEXT,
+  .next_nodes = {
+      [CNAT_FEATURE_NEXT_DROP] = "error-drop",
+  },
+};
+
+VNET_FEATURE_INIT (cnat_out_ip4_feature, static) = {
+  .arc_name = "ip4-output",
+  .node_name = "cnat-output-ip4",
+  .runs_before = VNET_FEATURES ("gso-ip4"),
+  .runs_after = VNET_FEATURES ("acl-plugin-out-ip4-fa"),
+};
+
+VLIB_NODE_FN (cnat_output_feature_ip6_node)
+(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
+{
+  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
+    return cnat_node_inline (vm, node, frame, cnat_output_feature_fn, AF_IP6,
+			     CNAT_LOCATION_OUTPUT, 1 /* do_trace */);
+  return cnat_node_inline (vm, node, frame, cnat_output_feature_fn, AF_IP6,
+			   CNAT_LOCATION_OUTPUT, 0 /* do_trace */);
+}
+
+VLIB_REGISTER_NODE (cnat_output_feature_ip6_node) = {
+  .name = "cnat-output-ip6",
+  .vector_size = sizeof (u32),
+  .format_trace = format_cnat_trace,
+  .type = VLIB_NODE_TYPE_INTERNAL,
+  .n_errors = CNAT_N_ERROR,
+  .error_strings = cnat_error_strings,
+  .n_next_nodes = CNAT_FEATURE_N_NEXT,
+  .next_nodes = {
+      [CNAT_FEATURE_NEXT_DROP] = "error-drop",
+  },
+};
+
+VNET_FEATURE_INIT (cnat_out_ip6_feature, static) = {
+  .arc_name = "ip6-output",
+  .node_name = "cnat-output-ip6",
+  .runs_before = VNET_FEATURES ("gso-ip6"),
+  .runs_after = VNET_FEATURES ("acl-plugin-out-ip6-fa"),
+};
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/plugins/cnat/cnat_snat.c b/src/plugins/cnat/cnat_snat.c
index 68b2f2b11bf..b063715d585 100644
--- a/src/plugins/cnat/cnat_snat.c
+++ b/src/plugins/cnat/cnat_snat.c
@@ -17,6 +17,59 @@
 #include <cnat/cnat_snat.h>
 #include <cnat/cnat_translation.h>
 
+cnat_snat_policy_main_t cnat_snat_policy_main;
+
+void
+cnat_set_snat_policy (cnat_snat_policy_t fp)
+{
+  cnat_snat_policy_main.snat_policy = fp;
+}
+
+static clib_error_t *
+cnat_snat_policy_cmd (vlib_main_t *vm, unformat_input_t *input,
+		      vlib_cli_command_t *cmd)
+{
+  cnat_snat_policy_t fp = NULL;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "none"))
+	;
+      else
+	return clib_error_return (0, "unknown input '%U'",
+				  format_unformat_error, input);
+    }
+
+  cnat_set_snat_policy (fp);
+  return NULL;
+}
+
+VLIB_CLI_COMMAND (cnat_snat_policy_command, static) = {
+  .path = "cnat set snat policy",
+  .short_help = "cnat set snat policy {none,k8s}",
+  .function = cnat_snat_policy_cmd,
+};
+
+static clib_error_t *
+show_cnat_snat_policy_cmd (vlib_main_t *vm, unformat_input_t *input,
+			   vlib_cli_command_t *cmd)
+{
+  u8 *s = format (NULL, "snat policy: ");
+  if (cnat_snat_policy_main.snat_policy == NULL)
+    s = format (s, "none");
+  else
+    s = format (s, "unknown (%x)", cnat_snat_policy_main.snat_policy);
+
+  vlib_cli_output (vm, (char *) s);
+  return NULL;
+}
+
+VLIB_CLI_COMMAND (show_cnat_snat_policy_command, static) = {
+  .path = "show cnat snat policy",
+  .short_help = "show cnat snat policy",
+  .function = show_cnat_snat_policy_cmd,
+};
+
 static void
 cnat_compute_prefix_lengths_in_search_order (cnat_snat_pfx_table_t *
 					     table, ip_address_family_t af)
diff --git a/src/plugins/cnat/cnat_snat.h b/src/plugins/cnat/cnat_snat.h
index 6ebb8034dbc..e34cf03bd92 100644
--- a/src/plugins/cnat/cnat_snat.h
+++ b/src/plugins/cnat/cnat_snat.h
@@ -17,12 +17,28 @@
 #define __CNAT_SNAT_H__
 
 #include <cnat/cnat_types.h>
+#include <cnat/cnat_session.h>
 
+/* function to use to decide whether to snat connections in the output
+   feature */
+typedef void (*cnat_snat_policy_t) (vlib_main_t *vm, vlib_buffer_t *b,
+				    cnat_session_t *session,
+				    cnat_node_ctx_t *ctx, u8 *do_snat);
+
+typedef struct cnat_snat_policy_main_t_
+{
+  /* SNAT policy for the output feature node */
+  cnat_snat_policy_t snat_policy;
+
+} cnat_snat_policy_main_t;
+
+extern cnat_snat_policy_main_t cnat_snat_policy_main;
 
 extern void cnat_set_snat (ip4_address_t * ip4, ip6_address_t * ip6,
 			   u32 sw_if_index);
 extern int cnat_add_snat_prefix (ip_prefix_t * pfx);
 extern int cnat_del_snat_prefix (ip_prefix_t * pfx);
+extern void cnat_set_snat_policy (cnat_snat_policy_t fp);
 
 int cnat_search_snat_prefix (ip46_address_t * addr, ip_address_family_t af);