/*	$FreeBSD: releng/12.0/sys/net/pfil.h 331436 2018-03-23 16:56:44Z kp $ */
/*	$NetBSD: pfil.h,v 1.22 2003/06/23 12:57:08 martin Exp $	*/

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1996 Matthew R. Green
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef _NET_PFIL_H_
#define _NET_PFIL_H_

#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/_lock.h>
#include <sys/_mutex.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <net/vnet.h>

struct mbuf;
struct ifnet;
struct inpcb;

typedef	int	(*pfil_func_t)(void *, struct mbuf **, struct ifnet *, int,
		    struct inpcb *);
typedef	int	(*pfil_func_flags_t)(void *, struct mbuf **, struct ifnet *,
		    int, int, struct inpcb *);

/*
 * The packet filter hooks are designed for anything to call them to
 * possibly intercept the packet.  Multiple filter hooks are chained
 * together and after each other in the specified order.
 */
struct packet_filter_hook {
	TAILQ_ENTRY(packet_filter_hook) pfil_chain;
	pfil_func_t		 pfil_func;
	pfil_func_flags_t	 pfil_func_flags;
	void			*pfil_arg;
};

#define PFIL_IN		0x00000001
#define PFIL_OUT	0x00000002
#define PFIL_WAITOK	0x00000004
#define PFIL_FWD	0x00000008
#define PFIL_ALL	(PFIL_IN|PFIL_OUT)

typedef	TAILQ_HEAD(pfil_chain, packet_filter_hook) pfil_chain_t;

#define	PFIL_TYPE_AF		1	/* key is AF_* type */
#define	PFIL_TYPE_IFNET		2	/* key is ifnet pointer */

#define	PFIL_FLAG_PRIVATE_LOCK	0x01	/* Personal lock instead of global */

/*
 * A pfil head is created by each protocol or packet intercept point.
 * For packet is then run through the hook chain for inspection.
 */
struct pfil_head {
	pfil_chain_t	 ph_in;
	pfil_chain_t	 ph_out;
	int		 ph_type;
	int		 ph_nhooks;
#if defined( __linux__ ) || defined( _WIN32 )
	rwlock_t	 ph_mtx;
#else
	struct rmlock	*ph_plock;	/* Pointer to the used lock */
	struct rmlock	 ph_lock;	/* Private lock storage */
	int		 flags;
#endif
	union {
		u_long	 phu_val;
		void	*phu_ptr;
	} ph_un;
#define	ph_af		 ph_un.phu_val
#define	ph_ifnet	 ph_un.phu_ptr
	LIST_ENTRY(pfil_head) ph_list;
};

VNET_DECLARE(struct rmlock, pfil_lock);
#define	V_pfil_lock	VNET(pfil_lock)

/* Public functions for pfil hook management by packet filters. */
struct pfil_head *pfil_head_get(int, u_long);
int	pfil_add_hook_flags(pfil_func_flags_t, void *, int, struct pfil_head *);
int	pfil_add_hook(pfil_func_t, void *, int, struct pfil_head *);
int	pfil_remove_hook_flags(pfil_func_flags_t, void *, int, struct pfil_head *);
int	pfil_remove_hook(pfil_func_t, void *, int, struct pfil_head *);
#define	PFIL_HOOKED(p) ((p)->ph_nhooks > 0)

/* Public functions to run the packet inspection by protocols. */
int	pfil_run_hooks(struct pfil_head *, struct mbuf **, struct ifnet *, int,
    int, struct inpcb *inp);

/* Public functions for pfil head management by protocols. */
int	pfil_head_register(struct pfil_head *);
int	pfil_head_unregister(struct pfil_head *);

/* Public pfil locking functions for self managed locks by packet filters. */
int	pfil_try_rlock(struct pfil_head *, struct rm_priotracker *);
void	pfil_rlock(struct pfil_head *, struct rm_priotracker *);
void	pfil_runlock(struct pfil_head *, struct rm_priotracker *);
void	pfil_wlock(struct pfil_head *);
void	pfil_wunlock(struct pfil_head *);
int	pfil_wowned(struct pfil_head *ph);

#endif /* _NET_PFIL_H_ */
