netfilter: xtables: compact table hook functions (1/2)

This patch combines all the per-hook functions in a given table into
a single function. Together with the 2nd patch, further
simplifications are possible up to the point of output code reduction.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

5 files changed, 75 insertions, 152 deletions

diff --git a/net/ipv4/netfilter/arptable_filter.c b/net/ipv4/netfilter/arptable_filter.c
index 9733760..e9d823b 100644
--- a/net/ipv4/netfilter/arptable_filter.c
+++ b/net/ipv4/netfilter/arptable_filter.c
@@ -53,43 +53,37 @@ static const struct xt_table packet_filter = {
 };
 
 /* The work comes in here from netfilter.c */
-static unsigned int arpt_in_hook(unsigned int hook,
-				 struct sk_buff *skb,
-				 const struct net_device *in,
-				 const struct net_device *out,
-				 int (*okfn)(struct sk_buff *))
+static unsigned int
+arptable_filter_hook(unsigned int hook, struct sk_buff *skb,
+		     const struct net_device *in, const struct net_device *out,
+		     int (*okfn)(struct sk_buff *))
 {
-	return arpt_do_table(skb, hook, in, out,
-			     dev_net(in)->ipv4.arptable_filter);
-}
+	if (hook == NF_ARP_OUT)
+		return arpt_do_table(skb, hook, in, out,
+				     dev_net(out)->ipv4.arptable_filter);
 
-static unsigned int arpt_out_hook(unsigned int hook,
-				  struct sk_buff *skb,
-				  const struct net_device *in,
-				  const struct net_device *out,
-				  int (*okfn)(struct sk_buff *))
-{
+	/* INPUT/FORWARD: */
 	return arpt_do_table(skb, hook, in, out,
-			     dev_net(out)->ipv4.arptable_filter);
+			     dev_net(in)->ipv4.arptable_filter);
 }
 
 static struct nf_hook_ops arpt_ops[] __read_mostly = {
 	{
-		.hook		= arpt_in_hook,
+		.hook		= arptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_ARP,
 		.hooknum	= NF_ARP_IN,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= arpt_out_hook,
+		.hook		= arptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_ARP,
 		.hooknum	= NF_ARP_OUT,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= arpt_in_hook,
+		.hook		= arptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_ARP,
 		.hooknum	= NF_ARP_FORWARD,
diff --git a/net/ipv4/netfilter/iptable_filter.c b/net/ipv4/netfilter/iptable_filter.c
index dee90eb..5369833 100644
--- a/net/ipv4/netfilter/iptable_filter.c
+++ b/net/ipv4/netfilter/iptable_filter.c
@@ -60,61 +60,43 @@ static const struct xt_table packet_filter = {
 	.af		= NFPROTO_IPV4,
 };
 
-/* The work comes in here from netfilter.c. */
 static unsigned int
-ipt_local_in_hook(unsigned int hook,
-		  struct sk_buff *skb,
-		  const struct net_device *in,
-		  const struct net_device *out,
-		  int (*okfn)(struct sk_buff *))
+iptable_filter_hook(unsigned int hook, struct sk_buff *skb,
+		    const struct net_device *in, const struct net_device *out,
+		    int (*okfn)(struct sk_buff *))
 {
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_filter);
-}
+	if (hook == NF_INET_LOCAL_OUT) {
+		if (skb->len < sizeof(struct iphdr) ||
+		    ip_hdrlen(skb) < sizeof(struct iphdr))
+			/* root is playing with raw sockets. */
+			return NF_ACCEPT;
+
+		return ipt_do_table(skb, hook, in, out,
+				    dev_net(out)->ipv4.iptable_filter);
+	}
 
-static unsigned int
-ipt_hook(unsigned int hook,
-	 struct sk_buff *skb,
-	 const struct net_device *in,
-	 const struct net_device *out,
-	 int (*okfn)(struct sk_buff *))
-{
+	/* LOCAL_IN/FORWARD: */
 	return ipt_do_table(skb, hook, in, out,
 			    dev_net(in)->ipv4.iptable_filter);
 }
 
-static unsigned int
-ipt_local_out_hook(unsigned int hook,
-		   struct sk_buff *skb,
-		   const struct net_device *in,
-		   const struct net_device *out,
-		   int (*okfn)(struct sk_buff *))
-{
-	/* root is playing with raw sockets. */
-	if (skb->len < sizeof(struct iphdr) ||
-	    ip_hdrlen(skb) < sizeof(struct iphdr))
-		return NF_ACCEPT;
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(out)->ipv4.iptable_filter);
-}
-
 static struct nf_hook_ops ipt_ops[] __read_mostly = {
 	{
-		.hook		= ipt_local_in_hook,
+		.hook		= iptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_IN,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= ipt_hook,
+		.hook		= iptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= NF_IP_PRI_FILTER,
 	},
 	{
-		.hook		= ipt_local_out_hook,
+		.hook		= iptable_filter_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_OUT,
diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c
index e07bf24..4e699cd 100644
--- a/net/ipv4/netfilter/iptable_mangle.c
+++ b/net/ipv4/netfilter/iptable_mangle.c
@@ -71,51 +71,6 @@ static const struct xt_table packet_mangler = {
 	.af		= NFPROTO_IPV4,
 };
 
-/* The work comes in here from netfilter.c. */
-static unsigned int
-ipt_pre_routing_hook(unsigned int hook,
-		     struct sk_buff *skb,
-		     const struct net_device *in,
-		     const struct net_device *out,
-		     int (*okfn)(struct sk_buff *))
-{
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_mangle);
-}
-
-static unsigned int
-ipt_post_routing_hook(unsigned int hook,
-		      struct sk_buff *skb,
-		      const struct net_device *in,
-		      const struct net_device *out,
-		      int (*okfn)(struct sk_buff *))
-{
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(out)->ipv4.iptable_mangle);
-}
-
-static unsigned int
-ipt_local_in_hook(unsigned int hook,
-		  struct sk_buff *skb,
-		  const struct net_device *in,
-		  const struct net_device *out,
-		  int (*okfn)(struct sk_buff *))
-{
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_mangle);
-}
-
-static unsigned int
-ipt_forward_hook(unsigned int hook,
-	 struct sk_buff *skb,
-	 const struct net_device *in,
-	 const struct net_device *out,
-	 int (*okfn)(struct sk_buff *))
-{
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_mangle);
-}
-
 static unsigned int
 ipt_local_hook(unsigned int hook,
 		   struct sk_buff *skb,
@@ -158,37 +113,53 @@ ipt_local_hook(unsigned int hook,
 	return ret;
 }
 
+/* The work comes in here from netfilter.c. */
+static unsigned int
+iptable_mangle_hook(unsigned int hook,
+		     struct sk_buff *skb,
+		     const struct net_device *in,
+		     const struct net_device *out,
+		     int (*okfn)(struct sk_buff *))
+{
+	if (hook == NF_INET_LOCAL_OUT)
+		return ipt_local_hook(hook, skb, in, out, okfn);
+
+	/* PREROUTING/INPUT/FORWARD: */
+	return ipt_do_table(skb, hook, in, out,
+			    dev_net(in)->ipv4.iptable_mangle);
+}
+
 static struct nf_hook_ops ipt_ops[] __read_mostly = {
 	{
-		.hook		= ipt_pre_routing_hook,
+		.hook		= iptable_mangle_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_PRE_ROUTING,
 		.priority	= NF_IP_PRI_MANGLE,
 	},
 	{
-		.hook		= ipt_local_in_hook,
+		.hook		= iptable_mangle_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_IN,
 		.priority	= NF_IP_PRI_MANGLE,
 	},
 	{
-		.hook		= ipt_forward_hook,
+		.hook		= iptable_mangle_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= NF_IP_PRI_MANGLE,
 	},
 	{
-		.hook		= ipt_local_hook,
+		.hook		= iptable_mangle_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_OUT,
 		.priority	= NF_IP_PRI_MANGLE,
 	},
 	{
-		.hook		= ipt_post_routing_hook,
+		.hook		= iptable_mangle_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_POST_ROUTING,
diff --git a/net/ipv4/netfilter/iptable_raw.c b/net/ipv4/netfilter/iptable_raw.c
index 40f2b9f..2c55575 100644
--- a/net/ipv4/netfilter/iptable_raw.c
+++ b/net/ipv4/netfilter/iptable_raw.c
@@ -45,23 +45,15 @@ static const struct xt_table packet_raw = {
 
 /* The work comes in here from netfilter.c. */
 static unsigned int
-ipt_hook(unsigned int hook,
-	 struct sk_buff *skb,
-	 const struct net_device *in,
-	 const struct net_device *out,
-	 int (*okfn)(struct sk_buff *))
+iptable_raw_hook(unsigned int hook, struct sk_buff *skb,
+		 const struct net_device *in, const struct net_device *out,
+		 int (*okfn)(struct sk_buff *))
 {
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_raw);
-}
+	if (hook == NF_INET_PRE_ROUTING)
+		return ipt_do_table(skb, hook, in, out,
+				    dev_net(in)->ipv4.iptable_raw);
 
-static unsigned int
-ipt_local_hook(unsigned int hook,
-	       struct sk_buff *skb,
-	       const struct net_device *in,
-	       const struct net_device *out,
-	       int (*okfn)(struct sk_buff *))
-{
+	/* OUTPUT: */
 	/* root is playing with raw sockets. */
 	if (skb->len < sizeof(struct iphdr) ||
 	    ip_hdrlen(skb) < sizeof(struct iphdr))
@@ -73,14 +65,14 @@ ipt_local_hook(unsigned int hook,
 /* 'raw' is the very first table. */
 static struct nf_hook_ops ipt_ops[] __read_mostly = {
 	{
-		.hook = ipt_hook,
+		.hook = iptable_raw_hook,
 		.pf = NFPROTO_IPV4,
 		.hooknum = NF_INET_PRE_ROUTING,
 		.priority = NF_IP_PRI_RAW,
 		.owner = THIS_MODULE,
 	},
 	{
-		.hook = ipt_local_hook,
+		.hook = iptable_raw_hook,
 		.pf = NFPROTO_IPV4,
 		.hooknum = NF_INET_LOCAL_OUT,
 		.priority = NF_IP_PRI_RAW,
diff --git a/net/ipv4/netfilter/iptable_security.c b/net/ipv4/netfilter/iptable_security.c
index 7ce2366..1c666ba 100644
--- a/net/ipv4/netfilter/iptable_security.c
+++ b/net/ipv4/netfilter/iptable_security.c
@@ -65,59 +65,43 @@ static const struct xt_table security_table = {
 };
 
 static unsigned int
-ipt_local_in_hook(unsigned int hook,
-		  struct sk_buff *skb,
-		  const struct net_device *in,
-		  const struct net_device *out,
-		  int (*okfn)(struct sk_buff *))
+iptable_security_hook(unsigned int hook, struct sk_buff *skb,
+		      const struct net_device *in,
+		      const struct net_device *out,
+		      int (*okfn)(struct sk_buff *))
 {
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_security);
-}
+	if (hook == NF_INET_LOCAL_OUT) {
+		if (skb->len < sizeof(struct iphdr) ||
+		    ip_hdrlen(skb) < sizeof(struct iphdr))
+			/* Somebody is playing with raw sockets. */
+			return NF_ACCEPT;
 
-static unsigned int
-ipt_forward_hook(unsigned int hook,
-		 struct sk_buff *skb,
-		 const struct net_device *in,
-		 const struct net_device *out,
-		 int (*okfn)(struct sk_buff *))
-{
-	return ipt_do_table(skb, hook, in, out,
-			    dev_net(in)->ipv4.iptable_security);
-}
+		return ipt_do_table(skb, hook, in, out,
+				    dev_net(out)->ipv4.iptable_security);
+	}
 
-static unsigned int
-ipt_local_out_hook(unsigned int hook,
-		   struct sk_buff *skb,
-		   const struct net_device *in,
-		   const struct net_device *out,
-		   int (*okfn)(struct sk_buff *))
-{
-	/* Somebody is playing with raw sockets. */
-	if (skb->len < sizeof(struct iphdr) ||
-	    ip_hdrlen(skb) < sizeof(struct iphdr))
-		return NF_ACCEPT;
+	/* INPUT/FORWARD: */
 	return ipt_do_table(skb, hook, in, out,
-			    dev_net(out)->ipv4.iptable_security);
+			    dev_net(in)->ipv4.iptable_security);
 }
 
 static struct nf_hook_ops ipt_ops[] __read_mostly = {
 	{
-		.hook		= ipt_local_in_hook,
+		.hook		= iptable_security_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_IN,
 		.priority	= NF_IP_PRI_SECURITY,
 	},
 	{
-		.hook		= ipt_forward_hook,
+		.hook		= iptable_security_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_FORWARD,
 		.priority	= NF_IP_PRI_SECURITY,
 	},
 	{
-		.hook		= ipt_local_out_hook,
+		.hook		= iptable_security_hook,
 		.owner		= THIS_MODULE,
 		.pf		= NFPROTO_IPV4,
 		.hooknum	= NF_INET_LOCAL_OUT,