xfrm: Move IPsec replay detection functions to a separate file

To support multiple versions of replay detection, we move the replay
detection functions to a separate file and make them accessible
via function pointers contained in the struct xfrm_replay.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c
index 4b63776..1aba03f 100644
--- a/net/xfrm/xfrm_output.c
+++ b/net/xfrm/xfrm_output.c
@@ -67,17 +67,10 @@
 			goto error;
 		}
 
-		if (x->type->flags & XFRM_TYPE_REPLAY_PROT) {
-			XFRM_SKB_CB(skb)->seq.output.low = ++x->replay.oseq;
-			if (unlikely(x->replay.oseq == 0)) {
-				XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
-				x->replay.oseq--;
-				xfrm_audit_state_replay_overflow(x, skb);
-				err = -EOVERFLOW;
-				goto error;
-			}
-			if (xfrm_aevent_is_on(net))
-				xfrm_replay_notify(x, XFRM_REPLAY_UPDATE);
+		err = x->repl->overflow(x, skb);
+		if (err) {
+			XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTSTATESEQERROR);
+			goto error;
 		}
 
 		x->curlft.bytes += skb->len;