NAT: session number limitation to avoid running out of memory crash (VPP-984)

Change-Id: I7f18f8c4ba609d96950dc1f833feb967d4a099b7
Signed-off-by: Matus Fabian <matfabia@cisco.com>

4 files changed, 120 insertions, 38 deletions

diff --git a/src/plugins/nat/in2out.c b/src/plugins/nat/in2out.c
index dfe103033ae..dbbc67f9327 100755
--- a/src/plugins/nat/in2out.c
+++ b/src/plugins/nat/in2out.c
@@ -101,7 +101,8 @@ _(IN2OUT_PACKETS, "Good in2out packets processed")      \
 _(OUT_OF_PORTS, "Out of ports")                         \
 _(BAD_OUTSIDE_FIB, "Outside VRF ID not found")          \
 _(BAD_ICMP_TYPE, "unsupported ICMP type")               \
-_(NO_TRANSLATION, "No translation")
+_(NO_TRANSLATION, "No translation")                     \
+_(MAX_SESSIONS_EXCEEDED, "Maximum sessions exceeded")
 
 typedef enum {
 #define _(sym,str) SNAT_IN2OUT_ERROR_##sym,
@@ -242,6 +243,12 @@ static u32 slow_path (snat_main_t *sm, vlib_buffer_t *b0,
   u32 outside_fib_index;
   uword * p;
 
+  if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+    {
+      b0->error = node->errors[SNAT_IN2OUT_ERROR_MAX_SESSIONS_EXCEEDED];
+      return SNAT_IN2OUT_NEXT_DROP;
+    }
+
   p = hash_get (sm->ip4_main->fib_index_by_table_id, sm->outside_vrf_id);
   if (! p)
     {
@@ -1064,14 +1071,15 @@ snat_hairpinning_unknown_proto (snat_main_t *sm,
   ip->checksum = ip_csum_fold (sum);
 }
 
-static void
+static snat_session_t *
 snat_in2out_unknown_proto (snat_main_t *sm,
                            vlib_buffer_t * b,
                            ip4_header_t * ip,
                            u32 rx_fib_index,
                            u32 thread_index,
                            f64 now,
-                           vlib_main_t * vm)
+                           vlib_main_t * vm,
+                           vlib_node_runtime_t * node)
 {
   clib_bihash_kv_8_8_t kv, value;
   clib_bihash_kv_16_8_t s_kv, s_value;
@@ -1108,6 +1116,12 @@ snat_in2out_unknown_proto (snat_main_t *sm,
     }
   else
     {
+      if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+        {
+          b->error = node->errors[SNAT_IN2OUT_ERROR_MAX_SESSIONS_EXCEEDED];
+          return 0;
+        }
+
       u_key.addr = ip->src_address;
       u_key.fib_index = rx_fib_index;
       kv.key = u_key.as_u64;
@@ -1198,7 +1212,7 @@ snat_in2out_unknown_proto (snat_main_t *sm,
                   goto create_ses;
                 }
             }
-          return;
+          return 0;
         }
 
 create_ses:
@@ -1342,6 +1356,8 @@ create_ses:
 
   if (vnet_buffer(b)->sw_if_index[VLIB_TX] == ~0)
     vnet_buffer(b)->sw_if_index[VLIB_TX] = sm->outside_fib_index;
+
+  return s;
 }
 
 static snat_session_t *
@@ -1351,7 +1367,8 @@ snat_in2out_lb (snat_main_t *sm,
                 u32 rx_fib_index,
                 u32 thread_index,
                 f64 now,
-                vlib_main_t * vm)
+                vlib_main_t * vm,
+                vlib_node_runtime_t * node)
 {
   nat_ed_ses_key_t key;
   clib_bihash_kv_16_8_t s_kv, s_value;
@@ -1386,6 +1403,12 @@ snat_in2out_lb (snat_main_t *sm,
     }
   else
     {
+      if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
+        {
+          b->error = node->errors[SNAT_IN2OUT_ERROR_MAX_SESSIONS_EXCEEDED];
+          return 0;
+        }
+
       l_key.addr = ip->src_address;
       l_key.port = udp->src_port;
       l_key.protocol = proto;
@@ -1598,8 +1621,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (proto0 == ~0))
                 {
-                  snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0,
-                                             thread_index, now, vm);
+                  s0 = snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0,
+                                                  thread_index, now, vm, node);
+                  if (!s0)
+                    next0 = SNAT_IN2OUT_NEXT_DROP;
                   goto trace00;
                 }
 
@@ -1653,8 +1678,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
                 {
                   if (is_slow_path)
                     {
-                      s0 = snat_in2out_lb(sm, b0, ip0, rx_fib_index0, thread_index,
-                                     now, vm);
+                      s0 = snat_in2out_lb(sm, b0, ip0, rx_fib_index0,
+                                          thread_index, now, vm, node);
+                      if (!s0)
+                        next0 = SNAT_IN2OUT_NEXT_DROP;
                       goto trace00;
                     }
                   else
@@ -1770,8 +1797,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (proto1 == ~0))
                 {
-                  snat_in2out_unknown_proto (sm, b1, ip1, rx_fib_index1,
-                                             thread_index, now, vm);
+                  s1 = snat_in2out_unknown_proto (sm, b1, ip1, rx_fib_index1,
+                                                  thread_index, now, vm, node);
+                  if (!s1)
+                    next1 = SNAT_IN2OUT_NEXT_DROP;
                   goto trace01;
                 }
 
@@ -1825,8 +1854,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
                 {
                   if (is_slow_path)
                     {
-                      s1 = snat_in2out_lb(sm, b1, ip1, rx_fib_index1, thread_index,
-                                     now, vm);
+                      s1 = snat_in2out_lb(sm, b1, ip1, rx_fib_index1,
+                                          thread_index, now, vm, node);
+                      if (!s1)
+                        next1 = SNAT_IN2OUT_NEXT_DROP;
                       goto trace01;
                     }
                   else
@@ -1978,8 +2009,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (proto0 == ~0))
                 {
-                  snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0,
-                                             thread_index, now, vm);
+                  s0 = snat_in2out_unknown_proto (sm, b0, ip0, rx_fib_index0,
+                                                  thread_index, now, vm, node);
+                  if (!s0)
+                    next0 = SNAT_IN2OUT_NEXT_DROP;
                   goto trace0;
                 }
 
@@ -2034,8 +2067,10 @@ snat_in2out_node_fn_inline (vlib_main_t * vm,
                 {
                   if (is_slow_path)
                     {
-                      s0 = snat_in2out_lb(sm, b0, ip0, rx_fib_index0, thread_index,
-                                     now, vm);
+                      s0 = snat_in2out_lb(sm, b0, ip0, rx_fib_index0,
+                                          thread_index, now, vm, node);
+                      if (!s0)
+                        next0 = SNAT_IN2OUT_NEXT_DROP;
                       goto trace0;
                     }
                   else
diff --git a/src/plugins/nat/nat.c b/src/plugins/nat/nat.c
index 5f3b006efda..612085fc132 100644
--- a/src/plugins/nat/nat.c
+++ b/src/plugins/nat/nat.c
@@ -2216,6 +2216,8 @@ snat_config (vlib_main_t * vm, unformat_input_t * input)
   /* for show commands, etc. */
   sm->translation_buckets = translation_buckets;
   sm->translation_memory_size = translation_memory_size;
+  /* do not exceed load factor 10 */
+  sm->max_translations = 10 * translation_buckets;
   sm->user_buckets = user_buckets;
   sm->user_memory_size = user_memory_size;
   sm->max_translations_per_user = max_translations_per_user;
diff --git a/src/plugins/nat/nat.h b/src/plugins/nat/nat.h
index 20e45952d55..d34ff07b7fe 100644
--- a/src/plugins/nat/nat.h
+++ b/src/plugins/nat/nat.h
@@ -345,6 +345,7 @@ typedef struct snat_main_s {
   u8 deterministic;
   u32 translation_buckets;
   u32 translation_memory_size;
+  u32 max_translations;
   u32 user_buckets;
   u32 user_memory_size;
   u32 max_translations_per_user;
@@ -551,4 +552,13 @@ is_interface_addr(snat_main_t *sm, vlib_node_runtime_t *node, u32 sw_if_index0,
     return 0;
 }
 
+always_inline u8
+maximum_sessions_exceeded (snat_main_t *sm, u32 thread_index)
+{
+  if (pool_elts (sm->per_thread_data[thread_index].sessions) >= sm->max_translations)
+    return 1;
+
+  return 0;
+}
+
 #endif /* __included_nat_h__ */
diff --git a/src/plugins/nat/out2in.c b/src/plugins/nat/out2in.c
index 6472e7ff50c..e5426c1a80e 100755
--- a/src/plugins/nat/out2in.c
+++ b/src/plugins/nat/out2in.c
@@ -87,7 +87,8 @@ vlib_node_registration_t snat_det_out2in_node;
 _(UNSUPPORTED_PROTOCOL, "Unsupported protocol")         \
 _(OUT2IN_PACKETS, "Good out2in packets processed")      \
 _(BAD_ICMP_TYPE, "unsupported ICMP type")               \
-_(NO_TRANSLATION, "No translation")
+_(NO_TRANSLATION, "No translation")                     \
+_(MAX_SESSIONS_EXCEEDED, "Maximum sessions exceeded")
 
 typedef enum {
 #define _(sym,str) SNAT_OUT2IN_ERROR_##sym,
@@ -139,6 +140,12 @@ create_session_for_static_mapping (snat_main_t *sm,
   dlist_elt_t * per_user_list_head_elt;
   ip4_header_t *ip0;
 
+  if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+    {
+      b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
+      return 0;
+    }
+
   ip0 = vlib_buffer_get_current (b0);
 
   user_key.addr = in2out.addr;
@@ -620,14 +627,15 @@ static inline u32 icmp_out2in_slow_path (snat_main_t *sm,
   return next0;
 }
 
-static void
+static snat_session_t *
 snat_out2in_unknown_proto (snat_main_t *sm,
                            vlib_buffer_t * b,
                            ip4_header_t * ip,
                            u32 rx_fib_index,
                            u32 thread_index,
                            f64 now,
-                           vlib_main_t * vm)
+                           vlib_main_t * vm,
+                           vlib_node_runtime_t * node)
 {
   clib_bihash_kv_8_8_t kv, value;
   clib_bihash_kv_16_8_t s_kv, s_value;
@@ -660,13 +668,22 @@ snat_out2in_unknown_proto (snat_main_t *sm,
     }
   else
     {
+      if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+        {
+          b->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
+          return 0;
+        }
+
       m_key.addr = ip->dst_address;
       m_key.port = 0;
       m_key.protocol = 0;
       m_key.fib_index = rx_fib_index;
       kv.key = m_key.as_u64;
       if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
-        return;
+        {
+          b->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
+          return 0;
+        }
 
       m = pool_elt_at_index (sm->static_mappings, value.value);
 
@@ -753,6 +770,8 @@ snat_out2in_unknown_proto (snat_main_t *sm,
   clib_dlist_remove (tsm->list_pool, s->per_user_index);
   clib_dlist_addtail (tsm->list_pool, s->per_user_list_head_index,
                       s->per_user_index);
+
+  return s;
 }
 
 static snat_session_t *
@@ -762,7 +781,8 @@ snat_out2in_lb (snat_main_t *sm,
                 u32 rx_fib_index,
                 u32 thread_index,
                 f64 now,
-                vlib_main_t * vm)
+                vlib_main_t * vm,
+                vlib_node_runtime_t * node)
 {
   nat_ed_ses_key_t key;
   clib_bihash_kv_16_8_t s_kv, s_value;
@@ -797,6 +817,12 @@ snat_out2in_lb (snat_main_t *sm,
     }
   else
     {
+      if (PREDICT_FALSE (maximum_sessions_exceeded(sm, thread_index)))
+        {
+          b->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
+          return 0;
+        }
+
       e_key.addr = ip->dst_address;
       e_key.port = udp->dst_port;
       e_key.protocol = proto;
@@ -998,8 +1024,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_FALSE (proto0 == ~0))
             {
-              snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
-                                        thread_index, now, vm);
+              s0 = snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
+                                             thread_index, now, vm, node);
+              if (!s0)
+                next0 = SNAT_OUT2IN_NEXT_DROP;
               goto trace0;
             }
 
@@ -1042,7 +1070,6 @@ snat_out2in_node_fn (vlib_main_t * vm,
                                                      thread_index);
               if (!s0)
                 {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
                   next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace0;
                 }
@@ -1051,8 +1078,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (value0.value == ~0ULL))
                 {
-                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index, now,
-                                 vm);
+                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index,
+                                      now, vm, node);
+                  if (!s0)
+                    next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace0;
                 }
               else
@@ -1150,8 +1179,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_FALSE (proto1 == ~0))
             {
-              snat_out2in_unknown_proto(sm, b1, ip1, rx_fib_index1,
-                                        thread_index, now, vm);
+              s1 = snat_out2in_unknown_proto(sm, b1, ip1, rx_fib_index1,
+                                             thread_index, now, vm, node);
+              if (!s1)
+                next1 = SNAT_OUT2IN_NEXT_DROP;
               goto trace1;
             }
 
@@ -1194,7 +1225,6 @@ snat_out2in_node_fn (vlib_main_t * vm,
                                                      thread_index);
               if (!s1)
                 {
-                  b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
                   next1 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace1;
                 }
@@ -1203,8 +1233,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (value1.value == ~0ULL))
                 {
-                  s1 = snat_out2in_lb(sm, b1, ip1, rx_fib_index1, thread_index, now,
-                                 vm);
+                  s1 = snat_out2in_lb(sm, b1, ip1, rx_fib_index1, thread_index,
+                                      now, vm, node);
+                  if (!s1)
+                    next1 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace1;
                 }
               else
@@ -1328,8 +1360,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
 
           if (PREDICT_FALSE (proto0 == ~0))
             {
-              snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
-                                        thread_index, now, vm);
+              s0 = snat_out2in_unknown_proto(sm, b0, ip0, rx_fib_index0,
+                                             thread_index, now, vm, node);
+              if (!s0)
+                next0 = SNAT_OUT2IN_NEXT_DROP;
               goto trace00;
             }
 
@@ -1383,8 +1417,7 @@ snat_out2in_node_fn (vlib_main_t * vm,
                                                      thread_index);
               if (!s0)
                 {
-                  b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
-                    next0 = SNAT_OUT2IN_NEXT_DROP;
+                  next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace00;
                 }
             }
@@ -1392,8 +1425,10 @@ snat_out2in_node_fn (vlib_main_t * vm,
             {
               if (PREDICT_FALSE (value0.value == ~0ULL))
                 {
-                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index, now,
-                                 vm);
+                  s0 = snat_out2in_lb(sm, b0, ip0, rx_fib_index0, thread_index,
+                                      now, vm, node);
+                  if (!s0)
+                    next0 = SNAT_OUT2IN_NEXT_DROP;
                   goto trace00;
                 }
               else