[NETFILTER]: Move skb_ip_make_writable to netfilter.c.

include/linux/netfilter_ipv4.h

@@ -75,6 +75,12 @@ void nf_debug_ip_finish_output2(struct sk_buff *skb);
 #endif /*CONFIG_NETFILTER_DEBUG*/
 
 extern int ip_route_me_harder(struct sk_buff **pskb);
+
+/* Call this before modifying an existing IP packet: ensures it is
+   modifiable and linear to the point you care about (writable_len).
+   Returns true or false. */
+extern int skb_ip_make_writable(struct sk_buff **pskb,
+				unsigned int writable_len);
 #endif /*__KERNEL__*/
 
 #endif /*__LINUX_IP_NETFILTER_H*/

include/linux/netfilter_ipv4/ip_nat_core.h

@@ -30,10 +30,4 @@ extern void place_in_hashes(struct ip_conntrack *conntrack,
 extern struct ip_nat_protocol ip_nat_protocol_tcp;
 extern struct ip_nat_protocol ip_nat_protocol_udp;
 extern struct ip_nat_protocol ip_nat_protocol_icmp;
-
-/* Call this before modifying an existing IP packet: ensures it is
-   modifiable and linear to the point you care about (writable_len).
-   Returns true or false. */
-extern int skb_ip_make_writable(struct sk_buff **pskb,
-				unsigned int writable_len);
 #endif /* _IP_NAT_CORE_H */

net/core/netfilter.c

@@ -20,6 +20,9 @@
 #include <linux/if.h>
 #include <linux/netdevice.h>
 #include <linux/inetdevice.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/icmp.h>
 #include <net/sock.h>
 #include <net/route.h>
 #include <linux/ip.h>
@@ -683,8 +686,68 @@ int ip_route_me_harder(struct sk_buff **pskb)
 
 	return err;
 }
+
+int skb_ip_make_writable(struct sk_buff **pskb, unsigned int writable_len)
+{
+	struct sk_buff *nskb;
+	unsigned int iplen;
+
+	if (writable_len > (*pskb)->len)
+		return 0;
+
+	/* Not exclusive use of packet?  Must copy. */
+	if (skb_shared(*pskb) || skb_cloned(*pskb))
+		goto copy_skb;
+
+	/* Alexey says IP hdr is always modifiable and linear, so ok. */
+	if (writable_len <= (*pskb)->nh.iph->ihl*4)
+		return 1;
+
+	iplen = writable_len - (*pskb)->nh.iph->ihl*4;
+
+	/* DaveM says protocol headers are also modifiable. */
+	switch ((*pskb)->nh.iph->protocol) {
+	case IPPROTO_TCP: {
+		struct tcphdr hdr;
+		if (skb_copy_bits(*pskb, (*pskb)->nh.iph->ihl*4,
+				  &hdr, sizeof(hdr)) != 0)
+			goto copy_skb;
+		if (writable_len <= (*pskb)->nh.iph->ihl*4 + hdr.doff*4)
+			goto pull_skb;
+		goto copy_skb;
+	}
+	case IPPROTO_UDP:
+		if (writable_len<=(*pskb)->nh.iph->ihl*4+sizeof(struct udphdr))
+			goto pull_skb;
+		goto copy_skb;
+	case IPPROTO_ICMP:
+		if (writable_len
+		    <= (*pskb)->nh.iph->ihl*4 + sizeof(struct icmphdr))
+			goto pull_skb;
+		goto copy_skb;
+	/* Insert other cases here as desired */
+	}
+
+copy_skb:
+	nskb = skb_copy(*pskb, GFP_ATOMIC);
+	if (!nskb)
+		return 0;
+	BUG_ON(skb_is_nonlinear(nskb));
+
+	/* Rest of kernel will get very unhappy if we pass it a
+	   suddenly-orphaned skbuff */
+	if ((*pskb)->sk)
+		skb_set_owner_w(nskb, (*pskb)->sk);
+	kfree_skb(*pskb);
+	*pskb = nskb;
+	return 1;
+
+pull_skb:
+	return pskb_may_pull(*pskb, writable_len);
+}
 #endif /*CONFIG_INET*/
 
+
 /* This does not belong here, but ipt_REJECT needs it if connection
    tracking in use: without this, connection may not be in hash table,
    and hence manufactured ICMP or RST packets will not be associated

net/ipv4/netfilter/ip_nat_core.c

@@ -969,65 +969,6 @@ icmp_reply_translation(struct sk_buff **pskb,
 	return 0;
 }
 
-int skb_ip_make_writable(struct sk_buff **pskb, unsigned int writable_len)
-{
-	struct sk_buff *nskb;
-	unsigned int iplen;
-
-	if (writable_len > (*pskb)->len)
-		return 0;
-
-	/* Not exclusive use of packet?  Must copy. */
-	if (skb_shared(*pskb) || skb_cloned(*pskb))
-		goto copy_skb;
-
-	/* Alexey says IP hdr is always modifiable and linear, so ok. */
-	if (writable_len <= (*pskb)->nh.iph->ihl*4)
-		return 1;
-
-	iplen = writable_len - (*pskb)->nh.iph->ihl*4;
-
-	/* DaveM says protocol headers are also modifiable. */
-	switch ((*pskb)->nh.iph->protocol) {
-	case IPPROTO_TCP: {
-		struct tcphdr hdr;
-		if (skb_copy_bits(*pskb, (*pskb)->nh.iph->ihl*4,
-				  &hdr, sizeof(hdr)) != 0)
-			goto copy_skb;
-		if (writable_len <= (*pskb)->nh.iph->ihl*4 + hdr.doff*4)
-			goto pull_skb;
-		goto copy_skb;
-	}
-	case IPPROTO_UDP:
-		if (writable_len<=(*pskb)->nh.iph->ihl*4+sizeof(struct udphdr))
-			goto pull_skb;
-		goto copy_skb;
-	case IPPROTO_ICMP:
-		if (writable_len
-		    <= (*pskb)->nh.iph->ihl*4 + sizeof(struct icmphdr))
-			goto pull_skb;
-		goto copy_skb;
-	/* Insert other cases here as desired */
-	}
-
-copy_skb:
-	nskb = skb_copy(*pskb, GFP_ATOMIC);
-	if (!nskb)
-		return 0;
-	BUG_ON(skb_is_nonlinear(nskb));
-
-	/* Rest of kernel will get very unhappy if we pass it a
-	   suddenly-orphaned skbuff */
-	if ((*pskb)->sk)
-		skb_set_owner_w(nskb, (*pskb)->sk);
-	kfree_skb(*pskb);
-	*pskb = nskb;
-	return 1;
-
-pull_skb:
-	return pskb_may_pull(*pskb, writable_len);
-}
-
 int __init ip_nat_init(void)
 {
 	size_t i;