X-Git-Url: https://gerrit.fd.io/r/gitweb?a=blobdiff_plain;f=src%2Fvnet%2Fipsec%2Fesp_decrypt.c;h=cddda1f8e544b4fc219b4f9bc6d43882c1166f0f;hb=12989b538881f9681f078cf1485c51df1251877a;hp=48f08f42e337ed9acc51e6751eedc0791868260b;hpb=c87b66c86201458c0475d50c6e93f1497f9eec2e;p=vpp.git

diff --git a/src/vnet/ipsec/esp_decrypt.c b/src/vnet/ipsec/esp_decrypt.c
index 48f08f42e33..cddda1f8e54 100644
--- a/src/vnet/ipsec/esp_decrypt.c
+++ b/src/vnet/ipsec/esp_decrypt.c
@@ -47,7 +47,8 @@ typedef enum
  _(RUNT, "undersized packet")                                   \
  _(CHAINED_BUFFER, "chained buffers (packet dropped)")          \
  _(OVERSIZED_HEADER, "buffer with oversized header (dropped)")  \
- _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)")
+ _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)")      \
+ _(TUN_NO_PROTO, "no tunnel protocol")                          \
 
 
 typedef enum
@@ -67,6 +68,8 @@ static char *esp_decrypt_error_strings[] = {
 typedef struct
 {
   u32 seq;
+  u32 sa_seq;
+  u32 sa_seq_hi;
   ipsec_crypto_alg_t crypto_alg;
   ipsec_integ_alg_t integ_alg;
 } esp_decrypt_trace_t;
@@ -79,9 +82,11 @@ format_esp_decrypt_trace (u8 * s, va_list * args)
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   esp_decrypt_trace_t *t = va_arg (*args, esp_decrypt_trace_t *);
 
-  s = format (s, "esp: crypto %U integrity %U seq %u",
-	      format_ipsec_crypto_alg, t->crypto_alg,
-	      format_ipsec_integ_alg, t->integ_alg, t->seq);
+  s =
+    format (s,
+	    "esp: crypto %U integrity %U pkt-seq %d sa-seq %u sa-seq-hi %u",
+	    format_ipsec_crypto_alg, t->crypto_alg, format_ipsec_integ_alg,
+	    t->integ_alg, t->seq, t->sa_seq, t->sa_seq_hi);
   return s;
 }
 
@@ -99,12 +104,13 @@ typedef struct
     u64 sa_data;
   };
 
+  u32 seq;
   i16 current_data;
   i16 current_length;
   u16 hdr_sz;
 } esp_decrypt_packet_data_t;
 
-STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 2 * sizeof (u64));
+STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 3 * sizeof (u64));
 
 #define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2)
 
@@ -177,6 +183,7 @@ esp_decrypt_inline (vlib_main_t * vm,
       pd->current_length = b[0]->current_length;
       pd->hdr_sz = pd->current_data - vnet_buffer (b[0])->l3_hdr_offset;
       payload = b[0]->data + pd->current_data;
+      pd->seq = clib_host_to_net_u32 (((esp_header_t *) payload)->seq);
 
       /* we need 4 extra bytes for HMAC calculation when ESN are used */
       if (ipsec_sa_is_set_USE_ESN (sa0) && pd->icv_sz &&
@@ -188,7 +195,7 @@ esp_decrypt_inline (vlib_main_t * vm,
 	}
 
       /* anti-reply check */
-      if (ipsec_sa_anti_replay_check (sa0, &((esp_header_t *) payload)->seq))
+      if (ipsec_sa_anti_replay_check (sa0, pd->seq))
 	{
 	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
 	  next[0] = ESP_DECRYPT_NEXT_DROP;
@@ -221,10 +228,11 @@ esp_decrypt_inline (vlib_main_t * vm,
 	  op->len = len;
 	  if (ipsec_sa_is_set_USE_ESN (sa0))
 	    {
-	      /* shift ICV for 4 bytes to insert ESN */
+	      /* shift ICV by 4 bytes to insert ESN */
+	      u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
 	      u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi);
 	      clib_memcpy_fast (tmp, payload + len, ESP_MAX_ICV_SIZE);
-	      clib_memcpy_fast (payload + len, &sa0->seq_hi, sz);
+	      clib_memcpy_fast (payload + len, &seq_hi, sz);
 	      clib_memcpy_fast (payload + len + sz, tmp, ESP_MAX_ICV_SIZE);
 	      op->len += sz;
 	      op->digest += sz;
@@ -368,9 +376,37 @@ esp_decrypt_inline (vlib_main_t * vm,
 	goto trace;
 
       sa0 = vec_elt_at_index (im->sad, pd->sa_index);
-      u8 *payload = b[0]->data + pd->current_data;
 
-      ipsec_sa_anti_replay_advance (sa0, ((esp_header_t *) payload)->seq);
+      /*
+       * redo the anti-reply check
+       * in this frame say we have sequence numbers, s, s+1, s+1, s+1
+       * and s and s+1 are in the window. When we did the anti-replay
+       * check above we did so against the state of the window (W),
+       * after packet s-1. So each of the packets in the sequence will be
+       * accepted.
+       * This time s will be cheked against Ws-1, s+1 chceked against Ws
+       * (i.e. the window state is updated/advnaced)
+       * so this time the successive s+! packet will be dropped.
+       * This is a consequence of batching the decrypts. If the
+       * check-dcrypt-advance process was done for each packet it would
+       * be fine. But we batch the decrypts because it's much more efficient
+       * to do so in SW and if we offload to HW and the process is async.
+       *
+       * You're probably thinking, but this means an attacker can send the
+       * above sequence and cause VPP to perform decrpyts that will fail,
+       * and that's true. But if the attacker can determine s (a valid
+       * sequence number in the window) which is non-trivial, it can generate
+       * a sequence s, s+1, s+2, s+3, ... s+n and nothing will prevent any
+       * implementation, sequential or batching, from decrypting these.
+       */
+      if (ipsec_sa_anti_replay_check (sa0, pd->seq))
+	{
+	  b[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY];
+	  next[0] = ESP_DECRYPT_NEXT_DROP;
+	  goto trace;
+	}
+
+      ipsec_sa_anti_replay_advance (sa0, pd->seq);
 
       esp_footer_t *f = (esp_footer_t *) (b[0]->data + pd->current_data +
 					  pd->current_length - sizeof (*f) -
@@ -462,8 +498,11 @@ esp_decrypt_inline (vlib_main_t * vm,
 						     &ip4->dst_address) ||
 			  !ip46_address_is_equal_v4 (&itp->itp_tun.dst,
 						     &ip4->src_address))
-			next[0] = ESP_DECRYPT_NEXT_DROP;
-
+			{
+			  next[0] = ESP_DECRYPT_NEXT_DROP;
+			  b[0]->error =
+			    node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
+			}
 		    }
 		  else if (f->next_header == IP_PROTOCOL_IPV6)
 		    {
@@ -475,7 +514,11 @@ esp_decrypt_inline (vlib_main_t * vm,
 						     &ip6->dst_address) ||
 			  !ip46_address_is_equal_v6 (&itp->itp_tun.dst,
 						     &ip6->src_address))
-			next[0] = ESP_DECRYPT_NEXT_DROP;
+			{
+			  next[0] = ESP_DECRYPT_NEXT_DROP;
+			  b[0]->error =
+			    node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO];
+			}
 		    }
 		}
 	    }
@@ -485,13 +528,14 @@ esp_decrypt_inline (vlib_main_t * vm,
       if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED))
 	{
 	  esp_decrypt_trace_t *tr;
-	  u8 *payload = b[0]->data + pd->current_data;
 	  tr = vlib_add_trace (vm, node, b[0], sizeof (*tr));
 	  sa0 = pool_elt_at_index (im->sad,
 				   vnet_buffer (b[0])->ipsec.sad_index);
 	  tr->crypto_alg = sa0->crypto_alg;
 	  tr->integ_alg = sa0->integ_alg;
-	  tr->seq = clib_host_to_net_u32 (((esp_header_t *) payload)->seq);
+	  tr->seq = pd->seq;
+	  tr->sa_seq = sa0->last_seq;
+	  tr->sa_seq_hi = sa0->seq_hi;
 	}
 
       /* next */
@@ -579,16 +623,9 @@ VLIB_REGISTER_NODE (esp4_decrypt_tun_node) = {
   .vector_size = sizeof (u32),
   .format_trace = format_esp_decrypt_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
-
   .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
   .error_strings = esp_decrypt_error_strings,
-
-  .n_next_nodes = ESP_DECRYPT_N_NEXT,
-  .next_nodes = {
-#define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
-    foreach_esp_decrypt_next
-#undef _
-  },
+  .sibling_of = "esp4-decrypt",
 };
 
 VLIB_REGISTER_NODE (esp6_decrypt_tun_node) = {
@@ -596,16 +633,9 @@ VLIB_REGISTER_NODE (esp6_decrypt_tun_node) = {
   .vector_size = sizeof (u32),
   .format_trace = format_esp_decrypt_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,
-
   .n_errors = ARRAY_LEN(esp_decrypt_error_strings),
   .error_strings = esp_decrypt_error_strings,
-
-  .n_next_nodes = ESP_DECRYPT_N_NEXT,
-  .next_nodes = {
-#define _(s,n) [ESP_DECRYPT_NEXT_##s] = n,
-    foreach_esp_decrypt_next
-#undef _
-  },
+  .sibling_of = "esp6-decrypt",
 };
 /* *INDENT-ON* */