nat: timed out session scavenging upgrade

Patch changes the behavior of session scavenging and fixes multiple
nat issues. Allows proper session clearing and removes issue with lingering sessions
in session db. Patch also updates and fixes CLI/API calls for better readability
of session state metrics. Fixes security issue that would allow attacker to
reuse timed out session in both directions (in2out/out2in).

Type: improvement

Signed-off-by: Filip Varga <fivarga@cisco.com>
Change-Id: I78897585a2a57291fad5db6d457941aa0a0457bd

1 files changed, 86 insertions, 5 deletions

diff --git a/src/plugins/nat/nat_format.c b/src/plugins/nat/nat_format.c
index 17f64b9b222..71bdaa6662c 100644
--- a/src/plugins/nat/nat_format.c
+++ b/src/plugins/nat/nat_format.c
@@ -18,6 +18,7 @@
  */
 
 #include <nat/nat.h>
+#include <nat/nat_inlines.h>
 #include <nat/nat_det.h>
 
 uword
@@ -173,7 +174,9 @@ format_snat_session (u8 * s, va_list * args)
 u8 *
 format_snat_user (u8 * s, va_list * args)
 {
-  snat_main_per_thread_data_t *sm =
+
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm =
     va_arg (*args, snat_main_per_thread_data_t *);
   snat_user_t *u = va_arg (*args, snat_user_t *);
   int verbose = va_arg (*args, int);
@@ -191,20 +194,20 @@ format_snat_user (u8 * s, va_list * args)
   if (u->nsessions || u->nstaticsessions)
     {
       head_index = u->sessions_per_user_list_head_index;
-      head = pool_elt_at_index (sm->list_pool, head_index);
+      head = pool_elt_at_index (tsm->list_pool, head_index);
 
       elt_index = head->next;
-      elt = pool_elt_at_index (sm->list_pool, elt_index);
+      elt = pool_elt_at_index (tsm->list_pool, elt_index);
       session_index = elt->value;
 
       while (session_index != ~0)
 	{
-	  sess = pool_elt_at_index (sm->sessions, session_index);
+	  sess = pool_elt_at_index (tsm->sessions, session_index);
 
 	  s = format (s, "  %U\n", format_snat_session, sm, sess);
 
 	  elt_index = elt->next;
-	  elt = pool_elt_at_index (sm->list_pool, elt_index);
+	  elt = pool_elt_at_index (tsm->list_pool, elt_index);
 	  session_index = elt->value;
 	}
     }
@@ -213,6 +216,84 @@ format_snat_user (u8 * s, va_list * args)
 }
 
 u8 *
+format_snat_user_v2 (u8 * s, va_list * args)
+{
+
+  snat_main_t *sm = &snat_main;
+  snat_main_per_thread_data_t *tsm =
+    va_arg (*args, snat_main_per_thread_data_t *);
+  snat_user_t *u = va_arg (*args, snat_user_t *);
+  u64 now = va_arg (*args, u64);
+
+  dlist_elt_t *head, *elt;
+  u32 elt_index, head_index;
+  u32 session_index;
+  snat_session_t *sess;
+
+  u32 udp_sessions = 0;
+  u32 tcp_sessions = 0;
+  u32 icmp_sessions = 0;
+
+  u32 timed_out = 0;
+  u32 transitory = 0;
+  u32 established = 0;
+
+  u64 sess_timeout_time;
+
+  if (u->nsessions || u->nstaticsessions)
+    {
+      head_index = u->sessions_per_user_list_head_index;
+      head = pool_elt_at_index (tsm->list_pool, head_index);
+
+      elt_index = head->next;
+      elt = pool_elt_at_index (tsm->list_pool, elt_index);
+      session_index = elt->value;
+
+      while (session_index != ~0)
+	{
+	  sess = pool_elt_at_index (tsm->sessions, session_index);
+
+	  sess_timeout_time = sess->last_heard +
+	    (f64) nat44_session_get_timeout (sm, sess);
+	  if (now >= sess_timeout_time)
+	    timed_out++;
+
+	  switch (sess->in2out.protocol)
+	    {
+	    case SNAT_PROTOCOL_ICMP:
+	      icmp_sessions++;
+	      break;
+	    case SNAT_PROTOCOL_TCP:
+	      tcp_sessions++;
+	      if (sess->state)
+		transitory++;
+	      else
+		established++;
+	      break;
+	    case SNAT_PROTOCOL_UDP:
+	    default:
+	      udp_sessions++;
+	      break;
+
+	    }
+
+	  elt_index = elt->next;
+	  elt = pool_elt_at_index (tsm->list_pool, elt_index);
+	  session_index = elt->value;
+	}
+    }
+
+  s = format (s, "%U: %d dynamic translations, %d static translations\n",
+	      format_ip4_address, &u->addr, u->nsessions, u->nstaticsessions);
+  s = format (s, "\t%u timed out, %u transitory, %u established\n",
+	      timed_out, transitory, established);
+  s = format (s, "\t%u tcp sessions, %u udp sessions, %u icmp sessions\n",
+	      tcp_sessions, udp_sessions, icmp_sessions);
+
+  return s;
+}
+
+u8 *
 format_snat_static_mapping (u8 * s, va_list * args)
 {
   snat_static_mapping_t *m = va_arg (*args, snat_static_mapping_t *);