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, 20 insertions, 26 deletions

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index b4c74a7a807c56..99fdb59454fdd3 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -186,16 +186,14 @@ ipt_error(struct sk_buff *skb,
 
 /* Performance critical - called for every packet */
 static inline bool
-do_match(struct ipt_entry_match *m,
-	      const struct sk_buff *skb,
-	      const struct net_device *in,
-	      const struct net_device *out,
-	      int offset,
-	      bool *hotdrop)
+do_match(struct ipt_entry_match *m, const struct sk_buff *skb,
+	 struct xt_match_param *par)
 {
+	par->match     = m->u.kernel.match;
+	par->matchinfo = m->data;
+
 	/* Stop iteration if it doesn't match */
-	if (!m->u.kernel.match->match(skb, in, out, m->u.kernel.match, m->data,
-				      offset, ip_hdrlen(skb), hotdrop))
+	if (!m->u.kernel.match->match(skb, par))
 		return true;
 	else
 		return false;
@@ -326,7 +324,6 @@ ipt_do_table(struct sk_buff *skb,
 	     struct xt_table *table)
 {
 	static const char nulldevname[IFNAMSIZ] __attribute__((aligned(sizeof(long))));
-	u_int16_t offset;
 	const struct iphdr *ip;
 	u_int16_t datalen;
 	bool hotdrop = false;
@@ -336,6 +333,7 @@ ipt_do_table(struct sk_buff *skb,
 	void *table_base;
 	struct ipt_entry *e, *back;
 	struct xt_table_info *private;
+	struct xt_match_param mtpar;
 
 	/* Initialization */
 	ip = ip_hdr(skb);
@@ -348,7 +346,11 @@ ipt_do_table(struct sk_buff *skb,
 	 * things we don't know, ie. tcp syn flag or ports).  If the
 	 * rule is also a fragment-specific rule, non-fragments won't
 	 * match it. */
-	offset = ntohs(ip->frag_off) & IP_OFFSET;
+	mtpar.fragoff = ntohs(ip->frag_off) & IP_OFFSET;
+	mtpar.thoff   = ip_hdrlen(skb);
+	mtpar.hotdrop = &hotdrop;
+	mtpar.in      = in;
+	mtpar.out     = out;
 
 	read_lock_bh(&table->lock);
 	IP_NF_ASSERT(table->valid_hooks & (1 << hook));
@@ -362,12 +364,11 @@ ipt_do_table(struct sk_buff *skb,
 	do {
 		IP_NF_ASSERT(e);
 		IP_NF_ASSERT(back);
-		if (ip_packet_match(ip, indev, outdev, &e->ip, offset)) {
+		if (ip_packet_match(ip, indev, outdev,
+		    &e->ip, mtpar.fragoff)) {
 			struct ipt_entry_target *t;
 
-			if (IPT_MATCH_ITERATE(e, do_match,
-					      skb, in, out,
-					      offset, &hotdrop) != 0)
+			if (IPT_MATCH_ITERATE(e, do_match, skb, &mtpar) != 0)
 				goto no_match;
 
 			ADD_COUNTER(e->counters, ntohs(ip->tot_len), 1);
@@ -2116,30 +2117,23 @@ icmp_type_code_match(u_int8_t test_type, u_int8_t min_code, u_int8_t max_code,
 }
 
 static bool
-icmp_match(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)
+icmp_match(const struct sk_buff *skb, const struct xt_match_param *par)
 {
 	const struct icmphdr *ic;
 	struct icmphdr _icmph;
-	const struct ipt_icmp *icmpinfo = matchinfo;
+	const struct ipt_icmp *icmpinfo = par->matchinfo;
 
 	/* Must not be a fragment. */
-	if (offset)
+	if (par->fragoff != 0)
 		return false;
 
-	ic = skb_header_pointer(skb, protoff, sizeof(_icmph), &_icmph);
+	ic = skb_header_pointer(skb, par->thoff, sizeof(_icmph), &_icmph);
 	if (ic == NULL) {
 		/* We've been asked to examine this packet, and we
 		 * can't.  Hence, no choice but to drop.
 		 */
 		duprintf("Dropping evil ICMP tinygram.\n");
-		*hotdrop = true;
+		*par->hotdrop = true;
 		return false;
 	}