ip: rate-limit the sending of ICMP error messages

Type: improvement

For error conditions, such as TTL expired, dest unreach, etc, Rate limit the sending of ICMP error messages.
The rate limiting is done based on src,dst IP address of the received packet.
the rate limit has been chosen, somewhat arbitrarily, to be 1e-3. This is the same limit as the ARP throttling.

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: I4a0b791cde8c941a9bf37de6aa5da56779d3cef4

1 files changed, 29 insertions, 1 deletions

diff --git a/src/vnet/ip/icmp4.c b/src/vnet/ip/icmp4.c
index 5f9ffa3b2b7..857c3b1d2a5 100644
--- a/src/vnet/ip/icmp4.c
+++ b/src/vnet/ip/icmp4.c
@@ -41,6 +41,7 @@
 #include <vnet/ip/ip.h>
 #include <vnet/pg/pg.h>
 #include <vnet/ip/ip_sas.h>
+#include <vnet/util/throttle.h>
 
 static char *icmp_error_strings[] = {
 #define _(f,s) s,
@@ -48,6 +49,9 @@ static char *icmp_error_strings[] = {
 #undef _
 };
 
+/** ICMP throttling */
+static throttle_t icmp_throttle;
+
 static u8 *
 format_ip4_icmp_type_and_code (u8 * s, va_list * args)
 {
@@ -255,11 +259,14 @@ ip4_icmp_error (vlib_main_t * vm,
   u32 *from, *to_next;
   uword n_left_from, n_left_to_next;
   ip4_icmp_error_next_t next_index;
+  u32 thread_index = vm->thread_index;
 
   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
   next_index = node->cached_next_index;
 
+  u64 seed = throttle_seed (&icmp_throttle, thread_index, vlib_time_now (vm));
+
   if (node->flags & VLIB_NODE_FLAG_TRACE)
     vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
 				   /* stride */ 1,
@@ -289,6 +296,21 @@ ip4_icmp_error (vlib_main_t * vm,
 	  ip_csum_t sum;
 
 	  org_p0 = vlib_get_buffer (vm, org_pi0);
+	  ip0 = vlib_buffer_get_current (org_p0);
+
+	  /* Rate limit based on the src,dst addresses in the original packet
+	   */
+	  u64 r0 =
+	    (u64) ip0->dst_address.as_u32 << 32 | ip0->src_address.as_u32;
+
+	  if (throttle_check (&icmp_throttle, thread_index, r0, seed))
+	    {
+	      vlib_error_count (vm, node->node_index, ICMP4_ERROR_DROP, 1);
+	      from += 1;
+	      n_left_from -= 1;
+	      continue;
+	    }
+
 	  p0 = vlib_buffer_copy_no_chain (vm, org_p0, &pi0);
 	  if (!p0 || pi0 == ~0)	/* Out of buffers */
 	    continue;
@@ -300,9 +322,10 @@ ip4_icmp_error (vlib_main_t * vm,
 	  n_left_from -= 1;
 	  n_left_to_next -= 1;
 
-	  ip0 = vlib_buffer_get_current (p0);
 	  sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
 
+	  vlib_buffer_copy_trace_flag (vm, p0, pi0);
+
 	  /* Add IP header and ICMPv4 header including a 4 byte data field */
 	  vlib_buffer_advance (p0,
 			       -sizeof (ip4_header_t) -
@@ -570,6 +593,11 @@ icmp4_init (vlib_main_t * vm)
 	       ICMP_INPUT_NEXT_ERROR,
 	       sizeof (cm->ip4_input_next_index_by_type));
 
+  vlib_thread_main_t *tm = &vlib_thread_main;
+  u32 n_vlib_mains = tm->n_vlib_mains;
+
+  throttle_init (&icmp_throttle, n_vlib_mains, 1e-3);
+
   return 0;
 }