ipsec: Fix setting the hi-sequence number for decrypt

Type: fix

two problems;
 1 - just because anti-reply is not enabled doesn't mean the high sequence
number should not be used.
   - fix, there needs to be some means to detect a wrapped packet, so we
use a window size of 2^30.
 2 - The SA object was used as a scratch pad for the high-sequence
number used during decryption. That means that once the batch has been
processed the high-sequence number used is lost. This means it is not
possible to distinguish this case:
      if (seq < IPSEC_SA_ANTI_REPLAY_WINDOW_LOWER_BOUND (tl))
	{
	  ...
	  if (post_decrypt)
	    {
	      if (hi_seq_used == sa->seq_hi)
		/* the high sequence number used to succesfully decrypt this
		 * packet is the same as the last-sequnence number of the SA.
		 * that means this packet did not cause a wrap.
		 * this packet is thus out of window and should be dropped */
		return 1;
	      else
		/* The packet decrypted with a different high sequence number
		 * to the SA, that means it is the wrap packet and should be
		 * accepted */
		return 0;
	    }
  - fix: don't use the SA as a scratch pad, use the 'packet_data' - the
same place that is used as the scratch pad for the low sequence number.

other consequences:
 - An SA doesn't have seq and last_seq, it has only seq; the sequence
numnber of the last packet tx'd or rx'd.
 - there's 64bits of space available on the SA's first cache line. move
the AES CTR mode IV there.
 - test the ESN/AR combinations to catch the bugs this fixes. This
doubles the amount of tests, but without AR on they only run for 2
seconds. In the AR tests, the time taken to wait for packets that won't
arrive is dropped from 1 to 0.2 seconds thus reducing the runtime of
these tests from 10-15 to about 5 sceonds.

Signed-off-by: Neale Ranns <neale@graphiant.com>
Change-Id: Iaac78905289a272dc01930d70decd8109cf5e7a5

1 files changed, 7 insertions, 4 deletions

diff --git a/src/vnet/ipsec/ah_decrypt.c b/src/vnet/ipsec/ah_decrypt.c
index d192fb6b80a..182ed3d231c 100644
--- a/src/vnet/ipsec/ah_decrypt.c
+++ b/src/vnet/ipsec/ah_decrypt.c
@@ -98,6 +98,7 @@ typedef struct
   };
   u32 sa_index;
   u32 seq;
+  u32 seq_hi;
   u8 icv_padding_len;
   u8 icv_size;
   u8 ip_hdr_size;
@@ -221,7 +222,8 @@ ah_decrypt_inline (vlib_main_t * vm,
       pd->seq = clib_host_to_net_u32 (ah0->seq_no);
 
       /* anti-replay check */
-      if (ipsec_sa_anti_replay_check (sa0, pd->seq))
+      if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, ~0, false,
+					       &pd->seq_hi))
 	{
 	  b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 	  next[0] = AH_DECRYPT_NEXT_DROP;
@@ -257,7 +259,7 @@ ah_decrypt_inline (vlib_main_t * vm,
 	  op->user_data = b - bufs;
 	  if (ipsec_sa_is_set_USE_ESN (sa0))
 	    {
-	      u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi);
+	      u32 seq_hi = clib_host_to_net_u32 (pd->seq_hi);
 
 	      op->len += sizeof (seq_hi);
 	      clib_memcpy (op->src + b[0]->current_length, &seq_hi,
@@ -322,13 +324,14 @@ ah_decrypt_inline (vlib_main_t * vm,
       if (PREDICT_TRUE (sa0->integ_alg != IPSEC_INTEG_ALG_NONE))
 	{
 	  /* redo the anit-reply check. see esp_decrypt for details */
-	  if (ipsec_sa_anti_replay_check (sa0, pd->seq))
+	  if (ipsec_sa_anti_replay_and_sn_advance (sa0, pd->seq, pd->seq_hi,
+						   true, NULL))
 	    {
 	      b[0]->error = node->errors[AH_DECRYPT_ERROR_REPLAY];
 	      next[0] = AH_DECRYPT_NEXT_DROP;
 	      goto trace;
 	    }
-	  ipsec_sa_anti_replay_advance (sa0, pd->seq);
+	  ipsec_sa_anti_replay_advance (sa0, pd->seq, pd->seq_hi);
 	}
 
       u16 ah_hdr_len = sizeof (ah_header_t) + pd->icv_size