[NETFILTER]: split net/core/netfilter.c into net/netfilter/*.c

This patch doesn't introduce any code changes, but merely splits the
core netfilter code into four separate files.  It also moves it from
it's old location in net/core/ to the recently-created net/netfilter/
directory.

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 829 insertions, 0 deletions

diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index c41caebc4a7..b3b44f8b415 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -1,3 +1,7 @@
+netfilter-objs := core.o nf_log.o nf_queue.o nf_sockopt.o
+
+obj-$(CONFIG_NETFILTER) = netfilter.o
+
 obj-$(CONFIG_NETFILTER_NETLINK) += nfnetlink.o
 obj-$(CONFIG_NETFILTER_NETLINK_QUEUE) += nfnetlink_queue.o
 obj-$(CONFIG_NETFILTER_NETLINK_LOG) += nfnetlink_log.o
diff --git a/net/netfilter/core.c b/net/netfilter/core.c
new file mode 100644
index 00000000000..1ceb1a6c254
--- /dev/null
+++ b/net/netfilter/core.c
@@ -0,0 +1,216 @@
+/* netfilter.c: look after the filters for various protocols. 
+ * Heavily influenced by the old firewall.c by David Bonn and Alan Cox.
+ *
+ * Thanks to Rob `CmdrTaco' Malda for not influencing this code in any
+ * way.
+ *
+ * Rusty Russell (C)2000 -- This code is GPL.
+ *
+ * February 2000: Modified by James Morris to have 1 queue per protocol.
+ * 15-Mar-2000:   Added NF_REPEAT --RR.
+ * 08-May-2003:	  Internal logging interface added by Jozsef Kadlecsik.
+ */
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/netfilter.h>
+#include <net/protocol.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/wait.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/if.h>
+#include <linux/netdevice.h>
+#include <linux/inetdevice.h>
+#include <linux/proc_fs.h>
+#include <net/sock.h>
+
+#include "nf_internals.h"
+
+/* In this code, we can be waiting indefinitely for userspace to
+ * service a packet if a hook returns NF_QUEUE.  We could keep a count
+ * of skbuffs queued for userspace, and not deregister a hook unless
+ * this is zero, but that sucks.  Now, we simply check when the
+ * packets come back: if the hook is gone, the packet is discarded. */
+struct list_head nf_hooks[NPROTO][NF_MAX_HOOKS];
+EXPORT_SYMBOL(nf_hooks);
+static DEFINE_SPINLOCK(nf_hook_lock);
+
+int nf_register_hook(struct nf_hook_ops *reg)
+{
+	struct list_head *i;
+
+	spin_lock_bh(&nf_hook_lock);
+	list_for_each(i, &nf_hooks[reg->pf][reg->hooknum]) {
+		if (reg->priority < ((struct nf_hook_ops *)i)->priority)
+			break;
+	}
+	list_add_rcu(&reg->list, i->prev);
+	spin_unlock_bh(&nf_hook_lock);
+
+	synchronize_net();
+	return 0;
+}
+EXPORT_SYMBOL(nf_register_hook);
+
+void nf_unregister_hook(struct nf_hook_ops *reg)
+{
+	spin_lock_bh(&nf_hook_lock);
+	list_del_rcu(&reg->list);
+	spin_unlock_bh(&nf_hook_lock);
+
+	synchronize_net();
+}
+EXPORT_SYMBOL(nf_unregister_hook);
+
+unsigned int nf_iterate(struct list_head *head,
+			struct sk_buff **skb,
+			int hook,
+			const struct net_device *indev,
+			const struct net_device *outdev,
+			struct list_head **i,
+			int (*okfn)(struct sk_buff *),
+			int hook_thresh)
+{
+	unsigned int verdict;
+
+	/*
+	 * The caller must not block between calls to this
+	 * function because of risk of continuing from deleted element.
+	 */
+	list_for_each_continue_rcu(*i, head) {
+		struct nf_hook_ops *elem = (struct nf_hook_ops *)*i;
+
+		if (hook_thresh > elem->priority)
+			continue;
+
+		/* Optimization: we don't need to hold module
+                   reference here, since function can't sleep. --RR */
+		verdict = elem->hook(hook, skb, indev, outdev, okfn);
+		if (verdict != NF_ACCEPT) {
+#ifdef CONFIG_NETFILTER_DEBUG
+			if (unlikely((verdict & NF_VERDICT_MASK)
+							> NF_MAX_VERDICT)) {
+				NFDEBUG("Evil return from %p(%u).\n",
+				        elem->hook, hook);
+				continue;
+			}
+#endif
+			if (verdict != NF_REPEAT)
+				return verdict;
+			*i = (*i)->prev;
+		}
+	}
+	return NF_ACCEPT;
+}
+
+
+/* Returns 1 if okfn() needs to be executed by the caller,
+ * -EPERM for NF_DROP, 0 otherwise. */
+int nf_hook_slow(int pf, unsigned int hook, struct sk_buff **pskb,
+		 struct net_device *indev,
+		 struct net_device *outdev,
+		 int (*okfn)(struct sk_buff *),
+		 int hook_thresh)
+{
+	struct list_head *elem;
+	unsigned int verdict;
+	int ret = 0;
+
+	/* We may already have this, but read-locks nest anyway */
+	rcu_read_lock();
+
+	elem = &nf_hooks[pf][hook];
+next_hook:
+	verdict = nf_iterate(&nf_hooks[pf][hook], pskb, hook, indev,
+			     outdev, &elem, okfn, hook_thresh);
+	if (verdict == NF_ACCEPT || verdict == NF_STOP) {
+		ret = 1;
+		goto unlock;
+	} else if (verdict == NF_DROP) {
+		kfree_skb(*pskb);
+		ret = -EPERM;
+	} else if ((verdict & NF_VERDICT_MASK)  == NF_QUEUE) {
+		NFDEBUG("nf_hook: Verdict = QUEUE.\n");
+		if (!nf_queue(pskb, elem, pf, hook, indev, outdev, okfn,
+			      verdict >> NF_VERDICT_BITS))
+			goto next_hook;
+	}
+unlock:
+	rcu_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL(nf_hook_slow);
+
+
+int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len)
+{
+	struct sk_buff *nskb;
+
+	if (writable_len > (*pskb)->len)
+		return 0;
+
+	/* Not exclusive use of packet?  Must copy. */
+	if (skb_shared(*pskb) || skb_cloned(*pskb))
+		goto copy_skb;
+
+	return pskb_may_pull(*pskb, writable_len);
+
+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;
+}
+EXPORT_SYMBOL(skb_make_writable);
+
+
+/* This does not belong here, but locally generated errors need 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 with it. */
+void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *);
+EXPORT_SYMBOL(ip_ct_attach);
+
+void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb)
+{
+	void (*attach)(struct sk_buff *, struct sk_buff *);
+
+	if (skb->nfct && (attach = ip_ct_attach) != NULL) {
+		mb(); /* Just to be sure: must be read before executing this */
+		attach(new, skb);
+	}
+}
+EXPORT_SYMBOL(nf_ct_attach);
+
+#ifdef CONFIG_PROC_FS
+struct proc_dir_entry *proc_net_netfilter;
+EXPORT_SYMBOL(proc_net_netfilter);
+#endif
+
+void __init netfilter_init(void)
+{
+	int i, h;
+	for (i = 0; i < NPROTO; i++) {
+		for (h = 0; h < NF_MAX_HOOKS; h++)
+			INIT_LIST_HEAD(&nf_hooks[i][h]);
+	}
+
+#ifdef CONFIG_PROC_FS
+	proc_net_netfilter = proc_mkdir("netfilter", proc_net);
+	if (!proc_net_netfilter)
+		panic("cannot create netfilter proc entry");
+#endif
+
+	if (netfilter_queue_init() < 0)
+		panic("cannot initialize nf_queue");
+	if (netfilter_log_init() < 0)
+		panic("cannot initialize nf_log");
+}
diff --git a/net/netfilter/nf_internals.h b/net/netfilter/nf_internals.h
new file mode 100644
index 00000000000..6bdee291061
--- /dev/null
+++ b/net/netfilter/nf_internals.h
@@ -0,0 +1,39 @@
+#ifndef _NF_INTERNALS_H
+#define _NF_INTERNALS_H
+
+#include <linux/config.h>
+#include <linux/list.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+
+#ifdef CONFIG_NETFILTER_DEBUG
+#define NFDEBUG(format, args...)  printk(format , ## args)
+#else
+#define NFDEBUG(format, args...)
+#endif
+
+
+/* core.c */
+extern unsigned int nf_iterate(struct list_head *head,
+				struct sk_buff **skb,
+				int hook,
+				const struct net_device *indev,
+				const struct net_device *outdev,
+				struct list_head **i,
+				int (*okfn)(struct sk_buff *),
+				int hook_thresh);
+
+/* nf_queue.c */
+extern int nf_queue(struct sk_buff **skb, 
+		    struct list_head *elem, 
+		    int pf, unsigned int hook,
+		    struct net_device *indev,
+		    struct net_device *outdev,
+		    int (*okfn)(struct sk_buff *),
+		    unsigned int queuenum);
+extern int __init netfilter_queue_init(void);
+
+/* nf_log.c */
+extern int __init netfilter_log_init(void);
+
+#endif
diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
new file mode 100644
index 00000000000..ec58c4d2c66
--- /dev/null
+++ b/net/netfilter/nf_log.c
@@ -0,0 +1,165 @@
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <net/protocol.h>
+
+#include "nf_internals.h"
+
+/* Internal logging interface, which relies on the real 
+   LOG target modules */
+
+#define NF_LOG_PREFIXLEN		128
+
+static struct nf_logger *nf_logging[NPROTO]; /* = NULL */
+static DEFINE_SPINLOCK(nf_log_lock);
+
+int nf_log_register(int pf, struct nf_logger *logger)
+{
+	int ret = -EBUSY;
+
+	/* Any setup of logging members must be done before
+	 * substituting pointer. */
+	spin_lock(&nf_log_lock);
+	if (!nf_logging[pf]) {
+		rcu_assign_pointer(nf_logging[pf], logger);
+		ret = 0;
+	}
+	spin_unlock(&nf_log_lock);
+	return ret;
+}		
+EXPORT_SYMBOL(nf_log_register);
+
+void nf_log_unregister_pf(int pf)
+{
+	spin_lock(&nf_log_lock);
+	nf_logging[pf] = NULL;
+	spin_unlock(&nf_log_lock);
+
+	/* Give time to concurrent readers. */
+	synchronize_net();
+}
+EXPORT_SYMBOL(nf_log_unregister_pf);
+
+void nf_log_unregister_logger(struct nf_logger *logger)
+{
+	int i;
+
+	spin_lock(&nf_log_lock);
+	for (i = 0; i < NPROTO; i++) {
+		if (nf_logging[i] == logger)
+			nf_logging[i] = NULL;
+	}
+	spin_unlock(&nf_log_lock);
+
+	synchronize_net();
+}
+EXPORT_SYMBOL(nf_log_unregister_logger);
+
+void nf_log_packet(int pf,
+		   unsigned int hooknum,
+		   const struct sk_buff *skb,
+		   const struct net_device *in,
+		   const struct net_device *out,
+		   struct nf_loginfo *loginfo,
+		   const char *fmt, ...)
+{
+	va_list args;
+	char prefix[NF_LOG_PREFIXLEN];
+	struct nf_logger *logger;
+	
+	rcu_read_lock();
+	logger = rcu_dereference(nf_logging[pf]);
+	if (logger) {
+		va_start(args, fmt);
+		vsnprintf(prefix, sizeof(prefix), fmt, args);
+		va_end(args);
+		/* We must read logging before nf_logfn[pf] */
+		logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);
+	} else if (net_ratelimit()) {
+		printk(KERN_WARNING "nf_log_packet: can\'t log since "
+		       "no backend logging module loaded in! Please either "
+		       "load one, or disable logging explicitly\n");
+	}
+	rcu_read_unlock();
+}
+EXPORT_SYMBOL(nf_log_packet);
+
+#ifdef CONFIG_PROC_FS
+static void *seq_start(struct seq_file *seq, loff_t *pos)
+{
+	rcu_read_lock();
+
+	if (*pos >= NPROTO)
+		return NULL;
+
+	return pos;
+}
+
+static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	(*pos)++;
+
+	if (*pos >= NPROTO)
+		return NULL;
+
+	return pos;
+}
+
+static void seq_stop(struct seq_file *s, void *v)
+{
+	rcu_read_unlock();
+}
+
+static int seq_show(struct seq_file *s, void *v)
+{
+	loff_t *pos = v;
+	const struct nf_logger *logger;
+
+	logger = rcu_dereference(nf_logging[*pos]);
+
+	if (!logger)
+		return seq_printf(s, "%2lld NONE\n", *pos);
+	
+	return seq_printf(s, "%2lld %s\n", *pos, logger->name);
+}
+
+static struct seq_operations nflog_seq_ops = {
+	.start	= seq_start,
+	.next	= seq_next,
+	.stop	= seq_stop,
+	.show	= seq_show,
+};
+
+static int nflog_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &nflog_seq_ops);
+}
+
+static struct file_operations nflog_file_ops = {
+	.owner	 = THIS_MODULE,
+	.open	 = nflog_open,
+	.read	 = seq_read,
+	.llseek	 = seq_lseek,
+	.release = seq_release,
+};
+
+#endif /* PROC_FS */
+
+
+int __init netfilter_log_init(void)
+{
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *pde;
+	pde = create_proc_entry("nf_log", S_IRUGO, proc_net_netfilter);
+#endif
+	if (!pde)
+		return -1;
+
+	pde->proc_fops = &nflog_file_ops;
+
+	return 0;
+}
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
new file mode 100644
index 00000000000..5586f843ed4
--- /dev/null
+++ b/net/netfilter/nf_queue.c
@@ -0,0 +1,273 @@
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <net/protocol.h>
+
+#include "nf_internals.h"
+
+/* 
+ * A queue handler may be registered for each protocol.  Each is protected by
+ * long term mutex.  The handler must provide an an outfn() to accept packets
+ * for queueing and must reinject all packets it receives, no matter what.
+ */
+static struct nf_queue_handler_t {
+	nf_queue_outfn_t outfn;
+	void *data;
+} queue_handler[NPROTO];
+
+static struct nf_queue_rerouter *queue_rerouter;
+
+static DEFINE_RWLOCK(queue_handler_lock);
+
+
+int nf_register_queue_handler(int pf, nf_queue_outfn_t outfn, void *data)
+{      
+	int ret;
+
+	if (pf >= NPROTO)
+		return -EINVAL;
+
+	write_lock_bh(&queue_handler_lock);
+	if (queue_handler[pf].outfn)
+		ret = -EBUSY;
+	else {
+		queue_handler[pf].outfn = outfn;
+		queue_handler[pf].data = data;
+		ret = 0;
+	}
+	write_unlock_bh(&queue_handler_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(nf_register_queue_handler);
+
+/* The caller must flush their queue before this */
+int nf_unregister_queue_handler(int pf)
+{
+	if (pf >= NPROTO)
+		return -EINVAL;
+
+	write_lock_bh(&queue_handler_lock);
+	queue_handler[pf].outfn = NULL;
+	queue_handler[pf].data = NULL;
+	write_unlock_bh(&queue_handler_lock);
+	
+	return 0;
+}
+EXPORT_SYMBOL(nf_unregister_queue_handler);
+
+int nf_register_queue_rerouter(int pf, struct nf_queue_rerouter *rer)
+{
+	if (pf >= NPROTO)
+		return -EINVAL;
+
+	write_lock_bh(&queue_handler_lock);
+	memcpy(&queue_rerouter[pf], rer, sizeof(queue_rerouter[pf]));
+	write_unlock_bh(&queue_handler_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_register_queue_rerouter);
+
+int nf_unregister_queue_rerouter(int pf)
+{
+	if (pf >= NPROTO)
+		return -EINVAL;
+
+	write_lock_bh(&queue_handler_lock);
+	memset(&queue_rerouter[pf], 0, sizeof(queue_rerouter[pf]));
+	write_unlock_bh(&queue_handler_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_unregister_queue_rerouter);
+
+void nf_unregister_queue_handlers(nf_queue_outfn_t outfn)
+{
+	int pf;
+
+	write_lock_bh(&queue_handler_lock);
+	for (pf = 0; pf < NPROTO; pf++)  {
+		if (queue_handler[pf].outfn == outfn) {
+			queue_handler[pf].outfn = NULL;
+			queue_handler[pf].data = NULL;
+		}
+	}
+	write_unlock_bh(&queue_handler_lock);
+}
+EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
+
+/* 
+ * Any packet that leaves via this function must come back 
+ * through nf_reinject().
+ */
+int nf_queue(struct sk_buff **skb, 
+	     struct list_head *elem, 
+	     int pf, unsigned int hook,
+	     struct net_device *indev,
+	     struct net_device *outdev,
+	     int (*okfn)(struct sk_buff *),
+	     unsigned int queuenum)
+{
+	int status;
+	struct nf_info *info;
+#ifdef CONFIG_BRIDGE_NETFILTER
+	struct net_device *physindev = NULL;
+	struct net_device *physoutdev = NULL;
+#endif
+
+	/* QUEUE == DROP if noone is waiting, to be safe. */
+	read_lock(&queue_handler_lock);
+	if (!queue_handler[pf].outfn) {
+		read_unlock(&queue_handler_lock);
+		kfree_skb(*skb);
+		return 1;
+	}
+
+	info = kmalloc(sizeof(*info)+queue_rerouter[pf].rer_size, GFP_ATOMIC);
+	if (!info) {
+		if (net_ratelimit())
+			printk(KERN_ERR "OOM queueing packet %p\n",
+			       *skb);
+		read_unlock(&queue_handler_lock);
+		kfree_skb(*skb);
+		return 1;
+	}
+
+	*info = (struct nf_info) { 
+		(struct nf_hook_ops *)elem, pf, hook, indev, outdev, okfn };
+
+	/* If it's going away, ignore hook. */
+	if (!try_module_get(info->elem->owner)) {
+		read_unlock(&queue_handler_lock);
+		kfree(info);
+		return 0;
+	}
+
+	/* Bump dev refs so they don't vanish while packet is out */
+	if (indev) dev_hold(indev);
+	if (outdev) dev_hold(outdev);
+
+#ifdef CONFIG_BRIDGE_NETFILTER
+	if ((*skb)->nf_bridge) {
+		physindev = (*skb)->nf_bridge->physindev;
+		if (physindev) dev_hold(physindev);
+		physoutdev = (*skb)->nf_bridge->physoutdev;
+		if (physoutdev) dev_hold(physoutdev);
+	}
+#endif
+	if (queue_rerouter[pf].save)
+		queue_rerouter[pf].save(*skb, info);
+
+	status = queue_handler[pf].outfn(*skb, info, queuenum,
+					 queue_handler[pf].data);
+
+	if (status >= 0 && queue_rerouter[pf].reroute)
+		status = queue_rerouter[pf].reroute(skb, info);
+
+	read_unlock(&queue_handler_lock);
+
+	if (status < 0) {
+		/* James M doesn't say fuck enough. */
+		if (indev) dev_put(indev);
+		if (outdev) dev_put(outdev);
+#ifdef CONFIG_BRIDGE_NETFILTER
+		if (physindev) dev_put(physindev);
+		if (physoutdev) dev_put(physoutdev);
+#endif
+		module_put(info->elem->owner);
+		kfree(info);
+		kfree_skb(*skb);
+
+		return 1;
+	}
+
+	return 1;
+}
+
+void nf_reinject(struct sk_buff *skb, struct nf_info *info,
+		 unsigned int verdict)
+{
+	struct list_head *elem = &info->elem->list;
+	struct list_head *i;
+
+	rcu_read_lock();
+
+	/* Release those devices we held, or Alexey will kill me. */
+	if (info->indev) dev_put(info->indev);
+	if (info->outdev) dev_put(info->outdev);
+#ifdef CONFIG_BRIDGE_NETFILTER
+	if (skb->nf_bridge) {
+		if (skb->nf_bridge->physindev)
+			dev_put(skb->nf_bridge->physindev);
+		if (skb->nf_bridge->physoutdev)
+			dev_put(skb->nf_bridge->physoutdev);
+	}
+#endif
+
+	/* Drop reference to owner of hook which queued us. */
+	module_put(info->elem->owner);
+
+	list_for_each_rcu(i, &nf_hooks[info->pf][info->hook]) {
+		if (i == elem) 
+  			break;
+  	}
+  
+	if (elem == &nf_hooks[info->pf][info->hook]) {
+		/* The module which sent it to userspace is gone. */
+		NFDEBUG("%s: module disappeared, dropping packet.\n",
+			__FUNCTION__);
+		verdict = NF_DROP;
+	}
+
+	/* Continue traversal iff userspace said ok... */
+	if (verdict == NF_REPEAT) {
+		elem = elem->prev;
+		verdict = NF_ACCEPT;
+	}
+
+	if (verdict == NF_ACCEPT) {
+	next_hook:
+		verdict = nf_iterate(&nf_hooks[info->pf][info->hook],
+				     &skb, info->hook, 
+				     info->indev, info->outdev, &elem,
+				     info->okfn, INT_MIN);
+	}
+
+	switch (verdict & NF_VERDICT_MASK) {
+	case NF_ACCEPT:
+		info->okfn(skb);
+		break;
+
+	case NF_QUEUE:
+		if (!nf_queue(&skb, elem, info->pf, info->hook, 
+			      info->indev, info->outdev, info->okfn,
+			      verdict >> NF_VERDICT_BITS))
+			goto next_hook;
+		break;
+	}
+	rcu_read_unlock();
+
+	if (verdict == NF_DROP)
+		kfree_skb(skb);
+
+	kfree(info);
+	return;
+}
+EXPORT_SYMBOL(nf_reinject);
+
+int __init netfilter_queue_init(void)
+{
+	queue_rerouter = kmalloc(NPROTO * sizeof(struct nf_queue_rerouter),
+				 GFP_KERNEL);
+	if (!queue_rerouter)
+		return -ENOMEM;
+
+	memset(queue_rerouter, 0, NPROTO * sizeof(struct nf_queue_rerouter));
+
+	return 0;
+}
+
diff --git a/net/netfilter/nf_sockopt.c b/net/netfilter/nf_sockopt.c
new file mode 100644
index 00000000000..61a833a9caa
--- /dev/null
+++ b/net/netfilter/nf_sockopt.c
@@ -0,0 +1,132 @@
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/netfilter.h>
+#include <net/sock.h>
+
+#include "nf_internals.h"
+
+/* Sockopts only registered and called from user context, so
+   net locking would be overkill.  Also, [gs]etsockopt calls may
+   sleep. */
+static DECLARE_MUTEX(nf_sockopt_mutex);
+static LIST_HEAD(nf_sockopts);
+
+/* Do exclusive ranges overlap? */
+static inline int overlap(int min1, int max1, int min2, int max2)
+{
+	return max1 > min2 && min1 < max2;
+}
+
+/* Functions to register sockopt ranges (exclusive). */
+int nf_register_sockopt(struct nf_sockopt_ops *reg)
+{
+	struct list_head *i;
+	int ret = 0;
+
+	if (down_interruptible(&nf_sockopt_mutex) != 0)
+		return -EINTR;
+
+	list_for_each(i, &nf_sockopts) {
+		struct nf_sockopt_ops *ops = (struct nf_sockopt_ops *)i;
+		if (ops->pf == reg->pf
+		    && (overlap(ops->set_optmin, ops->set_optmax, 
+				reg->set_optmin, reg->set_optmax)
+			|| overlap(ops->get_optmin, ops->get_optmax, 
+				   reg->get_optmin, reg->get_optmax))) {
+			NFDEBUG("nf_sock overlap: %u-%u/%u-%u v %u-%u/%u-%u\n",
+				ops->set_optmin, ops->set_optmax, 
+				ops->get_optmin, ops->get_optmax, 
+				reg->set_optmin, reg->set_optmax,
+				reg->get_optmin, reg->get_optmax);
+			ret = -EBUSY;
+			goto out;
+		}
+	}
+
+	list_add(&reg->list, &nf_sockopts);
+out:
+	up(&nf_sockopt_mutex);
+	return ret;
+}
+EXPORT_SYMBOL(nf_register_sockopt);
+
+void nf_unregister_sockopt(struct nf_sockopt_ops *reg)
+{
+	/* No point being interruptible: we're probably in cleanup_module() */
+ restart:
+	down(&nf_sockopt_mutex);
+	if (reg->use != 0) {
+		/* To be woken by nf_sockopt call... */
+		/* FIXME: Stuart Young's name appears gratuitously. */
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		reg->cleanup_task = current;
+		up(&nf_sockopt_mutex);
+		schedule();
+		goto restart;
+	}
+	list_del(&reg->list);
+	up(&nf_sockopt_mutex);
+}
+EXPORT_SYMBOL(nf_unregister_sockopt);
+
+/* Call get/setsockopt() */
+static int nf_sockopt(struct sock *sk, int pf, int val, 
+		      char __user *opt, int *len, int get)
+{
+	struct list_head *i;
+	struct nf_sockopt_ops *ops;
+	int ret;
+
+	if (down_interruptible(&nf_sockopt_mutex) != 0)
+		return -EINTR;
+
+	list_for_each(i, &nf_sockopts) {
+		ops = (struct nf_sockopt_ops *)i;
+		if (ops->pf == pf) {
+			if (get) {
+				if (val >= ops->get_optmin
+				    && val < ops->get_optmax) {
+					ops->use++;
+					up(&nf_sockopt_mutex);
+					ret = ops->get(sk, val, opt, len);
+					goto out;
+				}
+			} else {
+				if (val >= ops->set_optmin
+				    && val < ops->set_optmax) {
+					ops->use++;
+					up(&nf_sockopt_mutex);
+					ret = ops->set(sk, val, opt, *len);
+					goto out;
+				}
+			}
+		}
+	}
+	up(&nf_sockopt_mutex);
+	return -ENOPROTOOPT;
+	
+ out:
+	down(&nf_sockopt_mutex);
+	ops->use--;
+	if (ops->cleanup_task)
+		wake_up_process(ops->cleanup_task);
+	up(&nf_sockopt_mutex);
+	return ret;
+}
+
+int nf_setsockopt(struct sock *sk, int pf, int val, char __user *opt,
+		  int len)
+{
+	return nf_sockopt(sk, pf, val, opt, &len, 0);
+}
+EXPORT_SYMBOL(nf_setsockopt);
+
+int nf_getsockopt(struct sock *sk, int pf, int val, char __user *opt, int *len)
+{
+	return nf_sockopt(sk, pf, val, opt, len, 1);
+}
+EXPORT_SYMBOL(nf_getsockopt);
+