netfilter: xtables: move extension arguments into compound structure (1/6)

The function signatures for Xtables extensions have grown over time.
It involves a lot of typing/replication, and also a bit of stack space
even if they are not used. Realize an NFWS2008 idea and pack them into
structs. The skb remains outside of the struct so gcc can continue to
apply its optimizations.

This patch does this for match extensions' match functions.

A few ambiguities have also been addressed. The "offset" parameter for
example has been renamed to "fragoff" (there are so many different
offsets already) and "protoff" to "thoff" (there is more than just one
protocol here, so clarify).

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 5 insertions, 9 deletions

diff --git a/net/ipv4/netfilter/ipt_ah.c b/net/ipv4/netfilter/ipt_ah.c
index e2e993edd665..2fce19ef4f3f 100644
--- a/net/ipv4/netfilter/ipt_ah.c
+++ b/net/ipv4/netfilter/ipt_ah.c
@@ -36,27 +36,23 @@ spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, bool invert)
 	return r;
 }
 
-static bool
-ah_mt(const struct sk_buff *skb, const struct net_device *in,
-      const struct net_device *out, const struct xt_match *match,
-      const void *matchinfo, int offset, unsigned int protoff, bool *hotdrop)
+static bool ah_mt(const struct sk_buff *skb, const struct xt_match_param *par)
 {
 	struct ip_auth_hdr _ahdr;
 	const struct ip_auth_hdr *ah;
-	const struct ipt_ah *ahinfo = matchinfo;
+	const struct ipt_ah *ahinfo = par->matchinfo;
 
 	/* Must not be a fragment. */
-	if (offset)
+	if (par->fragoff != 0)
 		return false;
 
-	ah = skb_header_pointer(skb, protoff,
-				sizeof(_ahdr), &_ahdr);
+	ah = skb_header_pointer(skb, par->thoff, sizeof(_ahdr), &_ahdr);
 	if (ah == NULL) {
 		/* We've been asked to examine this packet, and we
 		 * can't.  Hence, no choice but to drop.
 		 */
 		duprintf("Dropping evil AH tinygram.\n");
-		*hotdrop = true;
+		*par->hotdrop = true;
 		return 0;
 	}