include/linux/netfilter.h - arm/linux-arm64-legacy - Git at Google

 #ifndef __LINUX_NETFILTER_H
 #define __LINUX_NETFILTER_H

 #ifdef __KERNEL__
 #include <linux/init.h>
 #include <linux/skbuff.h>
 #include <linux/net.h>
 #include <linux/if.h>
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/wait.h>
 #include <linux/list.h>
 #endif
 #include <linux/types.h>
 #include <linux/compiler.h>
 #include <linux/sysctl.h>

 /* Responses from hook functions. */
 #define NF_DROP 0
 #define NF_ACCEPT 1
 #define NF_STOLEN 2
 #define NF_QUEUE 3
 #define NF_REPEAT 4
 #define NF_STOP 5
 #define NF_MAX_VERDICT NF_STOP

 /* we overload the higher bits for encoding auxiliary data such as the queue
  * number or errno values. Not nice, but better than additional function
  * arguments. */
 #define NF_VERDICT_MASK 0x000000ff

 /* extra verdict flags have mask 0x0000ff00 */
 #define NF_VERDICT_FLAG_QUEUE_BYPASS	0x00008000

 /* queue number (NF_QUEUE) or errno (NF_DROP) */
 #define NF_VERDICT_QMASK 0xffff0000
 #define NF_VERDICT_QBITS 16

 #define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) | NF_QUEUE)

 #define NF_DROP_ERR(x) (((-x) << 16) | NF_DROP)

 /* only for userspace compatibility */
 #ifndef __KERNEL__
 /* Generic cache responses from hook functions.
    <= 0x2000 is used for protocol-flags. */
 #define NFC_UNKNOWN 0x4000
 #define NFC_ALTERED 0x8000

 /* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
 #define NF_VERDICT_BITS 16
 #endif

 enum nf_inet_hooks {
 	NF_INET_PRE_ROUTING,
 	NF_INET_LOCAL_IN,
 	NF_INET_FORWARD,
 	NF_INET_LOCAL_OUT,
 	NF_INET_POST_ROUTING,
 	NF_INET_NUMHOOKS
 };

 enum {
 	NFPROTO_UNSPEC =  0,
 	NFPROTO_IPV4   =  2,
 	NFPROTO_ARP    =  3,
 	NFPROTO_BRIDGE =  7,
 	NFPROTO_IPV6   = 10,
 	NFPROTO_DECNET = 12,
 	NFPROTO_NUMPROTO,
 };

 union nf_inet_addr {
 	__u32		all[4];
 	__be32		ip;
 	__be32		ip6[4];
 	struct in_addr	in;
 	struct in6_addr	in6;
 };

 #ifdef __KERNEL__
 #ifdef CONFIG_NETFILTER
 static inline int NF_DROP_GETERR(int verdict)
 {
 	return -(verdict >> NF_VERDICT_QBITS);
 }

 static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
 				   const union nf_inet_addr *a2)
 {
 	return a1->all[0] == a2->all[0] &&
 	       a1->all[1] == a2->all[1] &&
 	       a1->all[2] == a2->all[2] &&
 	       a1->all[3] == a2->all[3];
 }

 static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
 				     union nf_inet_addr *result,
 				     const union nf_inet_addr *mask)
 {
 	result->all[0] = a1->all[0] & mask->all[0];
 	result->all[1] = a1->all[1] & mask->all[1];
 	result->all[2] = a1->all[2] & mask->all[2];
 	result->all[3] = a1->all[3] & mask->all[3];
 }

 extern void netfilter_init(void);

 /* Largest hook number + 1 */
 #define NF_MAX_HOOKS 8

 struct sk_buff;

 typedef unsigned int nf_hookfn(unsigned int hooknum,
 			       struct sk_buff *skb,
 			       const struct net_device *in,
 			       const struct net_device *out,
 			       int (*okfn)(struct sk_buff *));

 struct nf_hook_ops {
 	struct list_head list;

 	/* User fills in from here down. */
 	nf_hookfn *hook;
 	struct module *owner;
 	u_int8_t pf;
 	unsigned int hooknum;
 	/* Hooks are ordered in ascending priority. */
 	int priority;
 };

 struct nf_sockopt_ops {
 	struct list_head list;

 	u_int8_t pf;

 	/* Non-inclusive ranges: use 0/0/NULL to never get called. */
 	int set_optmin;
 	int set_optmax;
 	int (*set)(struct sock *sk, int optval, void __user *user, unsigned int len);
 #ifdef CONFIG_COMPAT
 	int (*compat_set)(struct sock *sk, int optval,
 			void __user *user, unsigned int len);
 #endif
 	int get_optmin;
 	int get_optmax;
 	int (*get)(struct sock *sk, int optval, void __user *user, int *len);
 #ifdef CONFIG_COMPAT
 	int (*compat_get)(struct sock *sk, int optval,
 			void __user *user, int *len);
 #endif
 	/* Use the module struct to lock set/get code in place */
 	struct module *owner;
 };

 /* Function to register/unregister hook points. */
 int nf_register_hook(struct nf_hook_ops *reg);
 void nf_unregister_hook(struct nf_hook_ops *reg);
 int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
 void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);

 /* Functions to register get/setsockopt ranges (non-inclusive).  You
    need to check permissions yourself! */
 int nf_register_sockopt(struct nf_sockopt_ops *reg);
 void nf_unregister_sockopt(struct nf_sockopt_ops *reg);

 extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];

 #if defined(CONFIG_JUMP_LABEL)
 #include <linux/static_key.h>
 extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 {
 	if (__builtin_constant_p(pf) &&
 	    __builtin_constant_p(hook))
 		return static_key_false(&nf_hooks_needed[pf][hook]);

 	return !list_empty(&nf_hooks[pf][hook]);
 }
 #else
 static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
 {
 	return !list_empty(&nf_hooks[pf][hook]);
 }
 #endif

 int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 		 struct net_device *indev, struct net_device *outdev,
 		 int (*okfn)(struct sk_buff *), int thresh);

 /**
  *	nf_hook_thresh - call a netfilter hook
  *
  *	Returns 1 if the hook has allowed the packet to pass.  The function
  *	okfn must be invoked by the caller in this case.  Any other return
  *	value indicates the packet has been consumed by the hook.
  */
 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 				 struct sk_buff *skb,
 				 struct net_device *indev,
 				 struct net_device *outdev,
 				 int (*okfn)(struct sk_buff *), int thresh)
 {
 	if (nf_hooks_active(pf, hook))
 		return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
 	return 1;
 }

 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 			  struct net_device *indev, struct net_device *outdev,
 			  int (*okfn)(struct sk_buff *))
 {
 	return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
 }

 /* Activate hook; either okfn or kfree_skb called, unless a hook
    returns NF_STOLEN (in which case, it's up to the hook to deal with
    the consequences).

    Returns -ERRNO if packet dropped.  Zero means queued, stolen or
    accepted.
 */

 /* RR:
    > I don't want nf_hook to return anything because people might forget
    > about async and trust the return value to mean "packet was ok".

    AK:
    Just document it clearly, then you can expect some sense from kernel
    coders :)
 */

 static inline int
 NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 	       struct net_device *in, struct net_device *out,
 	       int (*okfn)(struct sk_buff *), int thresh)
 {
 	int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
 	if (ret == 1)
 		ret = okfn(skb);
 	return ret;
 }

 static inline int
 NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 	     struct net_device *in, struct net_device *out,
 	     int (*okfn)(struct sk_buff *), bool cond)
 {
 	int ret;

 	if (!cond ||
 	    ((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
 		ret = okfn(skb);
 	return ret;
 }

 static inline int
 NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
 	struct net_device *in, struct net_device *out,
 	int (*okfn)(struct sk_buff *))
 {
 	return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
 }

 /* Call setsockopt() */
 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 		  unsigned int len);
 int nf_getsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 		  int *len);
 #ifdef CONFIG_COMPAT
 int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
 		char __user *opt, unsigned int len);
 int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
 		char __user *opt, int *len);
 #endif

 /* Call this before modifying an existing packet: ensures it is
    modifiable and linear to the point you care about (writable_len).
    Returns true or false. */
 extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);

 struct flowi;
 struct nf_queue_entry;

 struct nf_afinfo {
 	unsigned short	family;
 	__sum16		(*checksum)(struct sk_buff *skb, unsigned int hook,
 				    unsigned int dataoff, u_int8_t protocol);
 	__sum16		(*checksum_partial)(struct sk_buff *skb,
 					    unsigned int hook,
 					    unsigned int dataoff,
 					    unsigned int len,
 					    u_int8_t protocol);
 	int		(*route)(struct net *net, struct dst_entry **dst,
 				 struct flowi *fl, bool strict);
 	void		(*saveroute)(const struct sk_buff *skb,
 				     struct nf_queue_entry *entry);
 	int		(*reroute)(struct sk_buff *skb,
 				   const struct nf_queue_entry *entry);
 	int		route_key_size;
 };

 extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
 static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
 {
 	return rcu_dereference(nf_afinfo[family]);
 }

 static inline __sum16
 nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
 	    u_int8_t protocol, unsigned short family)
 {
 	const struct nf_afinfo *afinfo;
 	__sum16 csum = 0;

 	rcu_read_lock();
 	afinfo = nf_get_afinfo(family);
 	if (afinfo)
 		csum = afinfo->checksum(skb, hook, dataoff, protocol);
 	rcu_read_unlock();
 	return csum;
 }

 static inline __sum16
 nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
 		    unsigned int dataoff, unsigned int len,
 		    u_int8_t protocol, unsigned short family)
 {
 	const struct nf_afinfo *afinfo;
 	__sum16 csum = 0;

 	rcu_read_lock();
 	afinfo = nf_get_afinfo(family);
 	if (afinfo)
 		csum = afinfo->checksum_partial(skb, hook, dataoff, len,
 						protocol);
 	rcu_read_unlock();
 	return csum;
 }

 extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
 extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);

 #include <net/flow.h>
 extern void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);

 static inline void
 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 {
 #ifdef CONFIG_NF_NAT_NEEDED
 	void (*decodefn)(struct sk_buff *, struct flowi *);

 	if (family == AF_INET) {
 		rcu_read_lock();
 		decodefn = rcu_dereference(ip_nat_decode_session);
 		if (decodefn)
 			decodefn(skb, fl);
 		rcu_read_unlock();
 	}
 #endif
 }

 #ifdef CONFIG_PROC_FS
 #include <linux/proc_fs.h>
 extern struct proc_dir_entry *proc_net_netfilter;
 #endif

 #else /* !CONFIG_NETFILTER */
 #define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
 #define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
 static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
 				 struct sk_buff *skb,
 				 struct net_device *indev,
 				 struct net_device *outdev,
 				 int (*okfn)(struct sk_buff *), int thresh)
 {
 	return okfn(skb);
 }
 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
 			  struct net_device *indev, struct net_device *outdev,
 			  int (*okfn)(struct sk_buff *))
 {
 	return 1;
 }
 struct flowi;
 static inline void
 nf_nat_decode_session(struct sk_buff *skb, struct flowi *fl, u_int8_t family)
 {
 }
 #endif /*CONFIG_NETFILTER*/

 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 extern void (*ip_ct_attach)(struct sk_buff *, struct sk_buff *) __rcu;
 extern void nf_ct_attach(struct sk_buff *, struct sk_buff *);
 extern void (*nf_ct_destroy)(struct nf_conntrack *) __rcu;

 struct nf_conn;
 struct nlattr;

 struct nfq_ct_hook {
 	size_t (*build_size)(const struct nf_conn *ct);
 	int (*build)(struct sk_buff *skb, struct nf_conn *ct);
 	int (*parse)(const struct nlattr *attr, struct nf_conn *ct);
 };
 extern struct nfq_ct_hook __rcu *nfq_ct_hook;

 struct nfq_ct_nat_hook {
 	void (*seq_adjust)(struct sk_buff *skb, struct nf_conn *ct,
 			   u32 ctinfo, int off);
 };
 extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
 #else
 static inline void nf_ct_attach(struct sk_buff *new, struct sk_buff *skb) {}
 #endif

 #endif /*__KERNEL__*/
 #endif /*__LINUX_NETFILTER_H*/
	#ifndef __LINUX_NETFILTER_H
	#define __LINUX_NETFILTER_H

	#ifdef __KERNEL__
	#include <linux/init.h>
	#include <linux/skbuff.h>
	#include <linux/net.h>
	#include <linux/if.h>
	#include <linux/in.h>
	#include <linux/in6.h>
	#include <linux/wait.h>
	#include <linux/list.h>
	#endif
	#include <linux/types.h>
	#include <linux/compiler.h>
	#include <linux/sysctl.h>

	/* Responses from hook functions. */
	#define NF_DROP 0
	#define NF_ACCEPT 1
	#define NF_STOLEN 2
	#define NF_QUEUE 3
	#define NF_REPEAT 4
	#define NF_STOP 5
	#define NF_MAX_VERDICT NF_STOP

	/* we overload the higher bits for encoding auxiliary data such as the queue
	* number or errno values. Not nice, but better than additional function
	* arguments. */
	#define NF_VERDICT_MASK 0x000000ff

	/* extra verdict flags have mask 0x0000ff00 */
	#define NF_VERDICT_FLAG_QUEUE_BYPASS 0x00008000

	/* queue number (NF_QUEUE) or errno (NF_DROP) */
	#define NF_VERDICT_QMASK 0xffff0000
	#define NF_VERDICT_QBITS 16

	#define NF_QUEUE_NR(x) ((((x) << 16) & NF_VERDICT_QMASK) \| NF_QUEUE)

	#define NF_DROP_ERR(x) (((-x) << 16) \| NF_DROP)

	/* only for userspace compatibility */
	#ifndef __KERNEL__
	/* Generic cache responses from hook functions.
	<= 0x2000 is used for protocol-flags. */
	#define NFC_UNKNOWN 0x4000
	#define NFC_ALTERED 0x8000

	/* NF_VERDICT_BITS should be 8 now, but userspace might break if this changes */
	#define NF_VERDICT_BITS 16
	#endif

	enum nf_inet_hooks {
	NF_INET_PRE_ROUTING,
	NF_INET_LOCAL_IN,
	NF_INET_FORWARD,
	NF_INET_LOCAL_OUT,
	NF_INET_POST_ROUTING,
	NF_INET_NUMHOOKS
	};

	enum {
	NFPROTO_UNSPEC = 0,
	NFPROTO_IPV4 = 2,
	NFPROTO_ARP = 3,
	NFPROTO_BRIDGE = 7,
	NFPROTO_IPV6 = 10,
	NFPROTO_DECNET = 12,
	NFPROTO_NUMPROTO,
	};

	union nf_inet_addr {
	__u32 all[4];
	__be32 ip;
	__be32 ip6[4];
	struct in_addr in;
	struct in6_addr in6;
	};

	#ifdef __KERNEL__
	#ifdef CONFIG_NETFILTER
	static inline int NF_DROP_GETERR(int verdict)
	{
	return -(verdict >> NF_VERDICT_QBITS);
	}

	static inline int nf_inet_addr_cmp(const union nf_inet_addr *a1,
	const union nf_inet_addr *a2)
	{
	return a1->all[0] == a2->all[0] &&
	a1->all[1] == a2->all[1] &&
	a1->all[2] == a2->all[2] &&
	a1->all[3] == a2->all[3];
	}

	static inline void nf_inet_addr_mask(const union nf_inet_addr *a1,
	union nf_inet_addr *result,
	const union nf_inet_addr *mask)
	{
	result->all[0] = a1->all[0] & mask->all[0];
	result->all[1] = a1->all[1] & mask->all[1];
	result->all[2] = a1->all[2] & mask->all[2];
	result->all[3] = a1->all[3] & mask->all[3];
	}

	extern void netfilter_init(void);

	/* Largest hook number + 1 */
	#define NF_MAX_HOOKS 8

	struct sk_buff;

	typedef unsigned int nf_hookfn(unsigned int hooknum,
	struct sk_buff *skb,
	const struct net_device *in,
	const struct net_device *out,
	int (okfn)(struct sk_buff ));

	struct nf_hook_ops {
	struct list_head list;

	/* User fills in from here down. */
	nf_hookfn *hook;
	struct module *owner;
	u_int8_t pf;
	unsigned int hooknum;
	/* Hooks are ordered in ascending priority. */
	int priority;
	};

	struct nf_sockopt_ops {
	struct list_head list;

	u_int8_t pf;

	/* Non-inclusive ranges: use 0/0/NULL to never get called. */
	int set_optmin;
	int set_optmax;
	int (set)(struct sock sk, int optval, void __user *user, unsigned int len);
	#ifdef CONFIG_COMPAT
	int (compat_set)(struct sock sk, int optval,
	void __user *user, unsigned int len);
	#endif
	int get_optmin;
	int get_optmax;
	int (get)(struct sock sk, int optval, void __user user, int len);
	#ifdef CONFIG_COMPAT
	int (compat_get)(struct sock sk, int optval,
	void __user user, int len);
	#endif
	/* Use the module struct to lock set/get code in place */
	struct module *owner;
	};

	/* Function to register/unregister hook points. */
	int nf_register_hook(struct nf_hook_ops *reg);
	void nf_unregister_hook(struct nf_hook_ops *reg);
	int nf_register_hooks(struct nf_hook_ops *reg, unsigned int n);
	void nf_unregister_hooks(struct nf_hook_ops *reg, unsigned int n);

	/* Functions to register get/setsockopt ranges (non-inclusive). You
	need to check permissions yourself! */
	int nf_register_sockopt(struct nf_sockopt_ops *reg);
	void nf_unregister_sockopt(struct nf_sockopt_ops *reg);

	extern struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS];

	#if defined(CONFIG_JUMP_LABEL)
	#include <linux/static_key.h>
	extern struct static_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
	static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
	{
	if (__builtin_constant_p(pf) &&
	__builtin_constant_p(hook))
	return static_key_false(&nf_hooks_needed[pf][hook]);

	return !list_empty(&nf_hooks[pf][hook]);
	}
	#else
	static inline bool nf_hooks_active(u_int8_t pf, unsigned int hook)
	{
	return !list_empty(&nf_hooks[pf][hook]);
	}
	#endif

	int nf_hook_slow(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device indev, struct net_device outdev,
	int (okfn)(struct sk_buff ), int thresh);

	/**
	* nf_hook_thresh - call a netfilter hook
	*
	* Returns 1 if the hook has allowed the packet to pass. The function
	* okfn must be invoked by the caller in this case. Any other return
	* value indicates the packet has been consumed by the hook.
	*/
	static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
	struct sk_buff *skb,
	struct net_device *indev,
	struct net_device *outdev,
	int (okfn)(struct sk_buff ), int thresh)
	{
	if (nf_hooks_active(pf, hook))
	return nf_hook_slow(pf, hook, skb, indev, outdev, okfn, thresh);
	return 1;
	}

	static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device indev, struct net_device outdev,
	int (okfn)(struct sk_buff ))
	{
	return nf_hook_thresh(pf, hook, skb, indev, outdev, okfn, INT_MIN);
	}

	/* Activate hook; either okfn or kfree_skb called, unless a hook
	returns NF_STOLEN (in which case, it's up to the hook to deal with
	the consequences).

	Returns -ERRNO if packet dropped. Zero means queued, stolen or
	accepted.
	*/

	/* RR:
	> I don't want nf_hook to return anything because people might forget
	> about async and trust the return value to mean "packet was ok".

	AK:
	Just document it clearly, then you can expect some sense from kernel
	coders :)
	*/

	static inline int
	NF_HOOK_THRESH(uint8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device in, struct net_device out,
	int (okfn)(struct sk_buff ), int thresh)
	{
	int ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, thresh);
	if (ret == 1)
	ret = okfn(skb);
	return ret;
	}

	static inline int
	NF_HOOK_COND(uint8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device in, struct net_device out,
	int (okfn)(struct sk_buff ), bool cond)
	{
	int ret;

	if (!cond \|\|
	((ret = nf_hook_thresh(pf, hook, skb, in, out, okfn, INT_MIN)) == 1))
	ret = okfn(skb);
	return ret;
	}

	static inline int
	NF_HOOK(uint8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device in, struct net_device out,
	int (okfn)(struct sk_buff ))
	{
	return NF_HOOK_THRESH(pf, hook, skb, in, out, okfn, INT_MIN);
	}

	/* Call setsockopt() */
	int nf_setsockopt(struct sock sk, u_int8_t pf, int optval, char __user opt,
	unsigned int len);
	int nf_getsockopt(struct sock sk, u_int8_t pf, int optval, char __user opt,
	int *len);
	#ifdef CONFIG_COMPAT
	int compat_nf_setsockopt(struct sock *sk, u_int8_t pf, int optval,
	char __user *opt, unsigned int len);
	int compat_nf_getsockopt(struct sock *sk, u_int8_t pf, int optval,
	char __user opt, int len);
	#endif

	/* Call this before modifying an existing packet: ensures it is
	modifiable and linear to the point you care about (writable_len).
	Returns true or false. */
	extern int skb_make_writable(struct sk_buff *skb, unsigned int writable_len);

	struct flowi;
	struct nf_queue_entry;

	struct nf_afinfo {
	unsigned short family;
	__sum16 (checksum)(struct sk_buff skb, unsigned int hook,
	unsigned int dataoff, u_int8_t protocol);
	__sum16 (checksum_partial)(struct sk_buff skb,
	unsigned int hook,
	unsigned int dataoff,
	unsigned int len,
	u_int8_t protocol);
	int (route)(struct net net, struct dst_entry **dst,
	struct flowi *fl, bool strict);
	void (saveroute)(const struct sk_buff skb,
	struct nf_queue_entry *entry);
	int (reroute)(struct sk_buff skb,
	const struct nf_queue_entry *entry);
	int route_key_size;
	};

	extern const struct nf_afinfo __rcu *nf_afinfo[NFPROTO_NUMPROTO];
	static inline const struct nf_afinfo *nf_get_afinfo(unsigned short family)
	{
	return rcu_dereference(nf_afinfo[family]);
	}

	static inline __sum16
	nf_checksum(struct sk_buff *skb, unsigned int hook, unsigned int dataoff,
	u_int8_t protocol, unsigned short family)
	{
	const struct nf_afinfo *afinfo;
	__sum16 csum = 0;

	rcu_read_lock();
	afinfo = nf_get_afinfo(family);
	if (afinfo)
	csum = afinfo->checksum(skb, hook, dataoff, protocol);
	rcu_read_unlock();
	return csum;
	}

	static inline __sum16
	nf_checksum_partial(struct sk_buff *skb, unsigned int hook,
	unsigned int dataoff, unsigned int len,
	u_int8_t protocol, unsigned short family)
	{
	const struct nf_afinfo *afinfo;
	__sum16 csum = 0;

	rcu_read_lock();
	afinfo = nf_get_afinfo(family);
	if (afinfo)
	csum = afinfo->checksum_partial(skb, hook, dataoff, len,
	protocol);
	rcu_read_unlock();
	return csum;
	}

	extern int nf_register_afinfo(const struct nf_afinfo *afinfo);
	extern void nf_unregister_afinfo(const struct nf_afinfo *afinfo);

	#include <net/flow.h>
	extern void (ip_nat_decode_session)(struct sk_buff , struct flowi *);

	static inline void
	nf_nat_decode_session(struct sk_buff skb, struct flowi fl, u_int8_t family)
	{
	#ifdef CONFIG_NF_NAT_NEEDED
	void (decodefn)(struct sk_buff , struct flowi *);

	if (family == AF_INET) {
	rcu_read_lock();
	decodefn = rcu_dereference(ip_nat_decode_session);
	if (decodefn)
	decodefn(skb, fl);
	rcu_read_unlock();
	}
	#endif
	}

	#ifdef CONFIG_PROC_FS
	#include <linux/proc_fs.h>
	extern struct proc_dir_entry *proc_net_netfilter;
	#endif

	#else /* !CONFIG_NETFILTER */
	#define NF_HOOK(pf, hook, skb, indev, outdev, okfn) (okfn)(skb)
	#define NF_HOOK_COND(pf, hook, skb, indev, outdev, okfn, cond) (okfn)(skb)
	static inline int nf_hook_thresh(u_int8_t pf, unsigned int hook,
	struct sk_buff *skb,
	struct net_device *indev,
	struct net_device *outdev,
	int (okfn)(struct sk_buff ), int thresh)
	{
	return okfn(skb);
	}
	static inline int nf_hook(u_int8_t pf, unsigned int hook, struct sk_buff *skb,
	struct net_device indev, struct net_device outdev,
	int (okfn)(struct sk_buff ))
	{
	return 1;
	}
	struct flowi;
	static inline void
	nf_nat_decode_session(struct sk_buff skb, struct flowi fl, u_int8_t family)
	{
	}
	#endif /CONFIG_NETFILTER/

	#if defined(CONFIG_NF_CONNTRACK) \|\| defined(CONFIG_NF_CONNTRACK_MODULE)
	extern void (ip_ct_attach)(struct sk_buff , struct sk_buff *) __rcu;
	extern void nf_ct_attach(struct sk_buff , struct sk_buff );
	extern void (nf_ct_destroy)(struct nf_conntrack ) __rcu;

	struct nf_conn;
	struct nlattr;

	struct nfq_ct_hook {
	size_t (build_size)(const struct nf_conn ct);
	int (build)(struct sk_buff skb, struct nf_conn *ct);
	int (parse)(const struct nlattr attr, struct nf_conn *ct);
	};
	extern struct nfq_ct_hook __rcu *nfq_ct_hook;

	struct nfq_ct_nat_hook {
	void (seq_adjust)(struct sk_buff skb, struct nf_conn *ct,
	u32 ctinfo, int off);
	};
	extern struct nfq_ct_nat_hook __rcu *nfq_ct_nat_hook;
	#else
	static inline void nf_ct_attach(struct sk_buff new, struct sk_buff skb) {}
	#endif

	#endif /__KERNEL__/
	#endif /__LINUX_NETFILTER_H/