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, 6 insertions, 9 deletions

diff --git a/net/ipv6/netfilter/ip6t_mh.c b/net/ipv6/netfilter/ip6t_mh.c
index dd876274ff6e..2803258b6d07 100644
--- a/net/ipv6/netfilter/ip6t_mh.c
+++ b/net/ipv6/netfilter/ip6t_mh.c
@@ -37,32 +37,29 @@ type_match(u_int8_t min, u_int8_t max, u_int8_t type, bool invert)
 	return (type >= min && type <= max) ^ invert;
 }
 
-static bool
-mh_mt6(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 mh_mt6(const struct sk_buff *skb, const struct xt_match_param *par)
 {
 	struct ip6_mh _mh;
 	const struct ip6_mh *mh;
-	const struct ip6t_mh *mhinfo = matchinfo;
+	const struct ip6t_mh *mhinfo = par->matchinfo;
 
 	/* Must not be a fragment. */
-	if (offset)
+	if (par->fragoff != 0)
 		return false;
 
-	mh = skb_header_pointer(skb, protoff, sizeof(_mh), &_mh);
+	mh = skb_header_pointer(skb, par->thoff, sizeof(_mh), &_mh);
 	if (mh == NULL) {
 		/* We've been asked to examine this packet, and we
 		   can't.  Hence, no choice but to drop. */
 		duprintf("Dropping evil MH tinygram.\n");
-		*hotdrop = true;
+		*par->hotdrop = true;
 		return false;
 	}
 
 	if (mh->ip6mh_proto != IPPROTO_NONE) {
 		duprintf("Dropping invalid MH Payload Proto: %u\n",
 			 mh->ip6mh_proto);
-		*hotdrop = true;
+		*par->hotdrop = true;
 		return false;
 	}