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Add pfil(9) subroutines and manpage from NetBSD.

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Darren Reed 2000-05-10 13:37:51 +00:00
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.\" $FreeBSD$
.\"
.\" 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.
.\"
.Dd August 4, 1996
.Dt PFIL 9
.Os
.Sh NAME
.Nm pfil ,
.Nm pfil_hook_get ,
.Nm pfil_add_hook ,
.Nm pfil_remove_hook
.Nd packet filter interface
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/mbuf.h>
.Fd #include <net/if.h>
.Fd #include <net/pfil.h>
.Ft struct packet_filter_hook *
.Fn pfil_hook_get "int" "struct pfil_head *"
.Ft void
.Fn pfil_add_hook "int (*func)()" "int flags" "struct pfil_head *"
.Ft void
.Fn pfil_remove_hook "int (*func)()" "int flags" "struct pfil_head *"
.\"(void *, int, struct ifnet *, int, struct mbuf **)
.Sh DESCRIPTION
The
.Nm
interface allows a function to be called on every incoming or outgoing
packets. The hooks for these are embedded in the
.Fn ip_input
and
.Fn ip_output
routines. The
.Fn pfil_hook_get
function returns the first member of a particular hook, either the in or out
list. The
.Fn pfil_add_hook
function takes a function of the form below as it's first argument, and the
flags for which lists to add the function to. The possible values for these
flags are some combination of PFIL_IN and PFIL_OUT. The
.Fn pfil_remove_hook
removes a hook from the specified lists.
.Pp
The
.Va func
argument is a function with the following prototype.
.Pp
.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
.Pp
The
.Va data
describes the packet. Currently, this may only be a pointer to a ip structure. The
.Va net
and
.Va m
arguments describe the network interface and the mbuf holding data for this
packet. The
.Va dir
is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
returns non-zero, this signals an error and no further processing of this packet is
performed. The function should set errno to indicate the nature of the error.
It is the hook's responsibiliy to free the chain if the packet is being dropped.
.Pp
The
.Nm
interface is enabled in the kernel via the
.Sy PFIL_HOOKS
option.
.Sh RETURN VALUES
If successful
.Fn pfil_hook_get
returns the first member of the packet filter list,
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
are expected to always succeed.
.Sh HISTORY
The
.Nm
interface first appeared in
.Nx 1.3 .
The
.Nm
input and output lists were originally implemented as
.Fd <sys/queue.h>
.Dv LIST
structures;
however this was changed in
.Nx 1.4
to
.Dv TAILQ
structures. This change was to allow the input and output filters to be
processed in reverse order, to allow the same path to be taken, in or out
of the kernel.
.Pp
The
.Nm
interface was changed in 1.4T to accept a 3rd parameter to both
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
, introducing the capability of per-protocol filtering. This was done
primarily in order to support filtering of IPv6.
.Sh BUGS
The current
.Nm
implementation will need changes to suit a threaded kernel model.
.Sh SEE ALSO
.Xr bpf 4

134
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.\" $FreeBSD$
.\"
.\" 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.
.\"
.Dd August 4, 1996
.Dt PFIL 9
.Os
.Sh NAME
.Nm pfil ,
.Nm pfil_hook_get ,
.Nm pfil_add_hook ,
.Nm pfil_remove_hook
.Nd packet filter interface
.Sh SYNOPSIS
.Fd #include <sys/param.h>
.Fd #include <sys/mbuf.h>
.Fd #include <net/if.h>
.Fd #include <net/pfil.h>
.Ft struct packet_filter_hook *
.Fn pfil_hook_get "int" "struct pfil_head *"
.Ft void
.Fn pfil_add_hook "int (*func)()" "int flags" "struct pfil_head *"
.Ft void
.Fn pfil_remove_hook "int (*func)()" "int flags" "struct pfil_head *"
.\"(void *, int, struct ifnet *, int, struct mbuf **)
.Sh DESCRIPTION
The
.Nm
interface allows a function to be called on every incoming or outgoing
packets. The hooks for these are embedded in the
.Fn ip_input
and
.Fn ip_output
routines. The
.Fn pfil_hook_get
function returns the first member of a particular hook, either the in or out
list. The
.Fn pfil_add_hook
function takes a function of the form below as it's first argument, and the
flags for which lists to add the function to. The possible values for these
flags are some combination of PFIL_IN and PFIL_OUT. The
.Fn pfil_remove_hook
removes a hook from the specified lists.
.Pp
The
.Va func
argument is a function with the following prototype.
.Pp
.Fn func "void *data" "int hlen" "struct ifnet *net" "int dir" "struct mbuf **m"
.Pp
The
.Va data
describes the packet. Currently, this may only be a pointer to a ip structure. The
.Va net
and
.Va m
arguments describe the network interface and the mbuf holding data for this
packet. The
.Va dir
is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
returns non-zero, this signals an error and no further processing of this packet is
performed. The function should set errno to indicate the nature of the error.
It is the hook's responsibiliy to free the chain if the packet is being dropped.
.Pp
The
.Nm
interface is enabled in the kernel via the
.Sy PFIL_HOOKS
option.
.Sh RETURN VALUES
If successful
.Fn pfil_hook_get
returns the first member of the packet filter list,
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
are expected to always succeed.
.Sh HISTORY
The
.Nm
interface first appeared in
.Nx 1.3 .
The
.Nm
input and output lists were originally implemented as
.Fd <sys/queue.h>
.Dv LIST
structures;
however this was changed in
.Nx 1.4
to
.Dv TAILQ
structures. This change was to allow the input and output filters to be
processed in reverse order, to allow the same path to be taken, in or out
of the kernel.
.Pp
The
.Nm
interface was changed in 1.4T to accept a 3rd parameter to both
.Fn pfil_add_hook
and
.Fn pfil_remove_hook
, introducing the capability of per-protocol filtering. This was done
primarily in order to support filtering of IPv6.
.Sh BUGS
The current
.Nm
implementation will need changes to suit a threaded kernel model.
.Sh SEE ALSO
.Xr bpf 4

176
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/* $FreeBSD$ */
/*
* 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.
*/
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <net/if.h>
#include <net/pfil.h>
static void pfil_init __P((struct pfil_head *));
static int pfil_list_add(pfil_list_t *,
int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)), int);
static int pfil_list_remove(pfil_list_t *,
int (*) __P((void *, int, struct ifnet *, int, struct mbuf **)));
static void
pfil_init(ph)
struct pfil_head *ph;
{
TAILQ_INIT(&ph->ph_in);
TAILQ_INIT(&ph->ph_out);
ph->ph_init = 1;
}
/*
* pfil_add_hook() adds a function to the packet filter hook. the
* flags are:
* PFIL_IN call me on incoming packets
* PFIL_OUT call me on outgoing packets
* PFIL_ALL call me on all of the above
* PFIL_WAITOK OK to call malloc with M_WAITOK.
*/
int
pfil_add_hook(func, flags, ph)
int (*func) __P((void *, int, struct ifnet *, int,
struct mbuf **));
int flags;
struct pfil_head *ph;
{
int err = 0;
if (ph->ph_init == 0)
pfil_init(ph);
if (flags & PFIL_IN)
err = pfil_list_add(&ph->ph_in, func, flags & ~PFIL_OUT);
if (err)
return err;
if (flags & PFIL_OUT)
err = pfil_list_add(&ph->ph_out, func, flags & ~PFIL_IN);
if (err) {
if (flags & PFIL_IN)
pfil_list_remove(&ph->ph_in, func);
return err;
}
return 0;
}
static int
pfil_list_add(list, func, flags)
pfil_list_t *list;
int (*func) __P((void *, int, struct ifnet *, int,
struct mbuf **));
int flags;
{
struct packet_filter_hook *pfh;
pfh = (struct packet_filter_hook *)malloc(sizeof(*pfh), M_IFADDR,
flags & PFIL_WAITOK ? M_WAITOK : M_NOWAIT);
if (pfh == NULL)
return ENOMEM;
pfh->pfil_func = func;
/*
* insert the input list in reverse order of the output list
* so that the same path is followed in or out of the kernel.
*/
if (flags & PFIL_IN)
TAILQ_INSERT_HEAD(list, pfh, pfil_link);
else
TAILQ_INSERT_TAIL(list, pfh, pfil_link);
return 0;
}
/*
* pfil_remove_hook removes a specific function from the packet filter
* hook list.
*/
int
pfil_remove_hook(func, flags, ph)
int (*func) __P((void *, int, struct ifnet *, int,
struct mbuf **));
int flags;
struct pfil_head *ph;
{
int err = 0;
if (ph->ph_init == 0)
pfil_init(ph);
if (flags & PFIL_IN)
err = pfil_list_remove(&ph->ph_in, func);
if ((err == 0) && (flags & PFIL_OUT))
err = pfil_list_remove(&ph->ph_out, func);
return err;
}
/*
* pfil_list_remove is an internal function that takes a function off the
* specified list.
*/
static int
pfil_list_remove(list, func)
pfil_list_t *list;
int (*func) __P((void *, int, struct ifnet *, int,
struct mbuf **));
{
struct packet_filter_hook *pfh;
for (pfh = list->tqh_first; pfh; pfh = pfh->pfil_link.tqe_next)
if (pfh->pfil_func == func) {
TAILQ_REMOVE(list, pfh, pfil_link);
free(pfh, M_IFADDR);
return 0;
}
return ENOENT;
}
struct packet_filter_hook *
pfil_hook_get(flag, ph)
int flag;
struct pfil_head *ph;
{
if (ph->ph_init != 0)
switch (flag) {
case PFIL_IN:
return (ph->ph_in.tqh_first);
case PFIL_OUT:
return (ph->ph_out.tqh_first);
}
return NULL;
}

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sys/net/pfil.h Normal file
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/* $FreeBSD$ */
/*
* 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/queue.h>
struct mbuf;
struct ifnet;
/*
* The packet filter hooks are designed for anything to call them to
* possibly intercept the packet.
*/
struct packet_filter_hook {
TAILQ_ENTRY(packet_filter_hook) pfil_link;
int (*pfil_func) __P((void *, int, struct ifnet *, int,
struct mbuf **));
int pfil_flags;
};
#define PFIL_IN 0x00000001
#define PFIL_OUT 0x00000002
#define PFIL_WAITOK 0x00000004
#define PFIL_ALL (PFIL_IN|PFIL_OUT)
typedef TAILQ_HEAD(pfil_list, packet_filter_hook) pfil_list_t;
struct pfil_head {
pfil_list_t ph_in;
pfil_list_t ph_out;
int ph_init;
} pfil_head_t;
struct packet_filter_hook *pfil_hook_get __P((int, struct pfil_head *));
int pfil_add_hook __P((int (*func) __P((void *, int,
struct ifnet *, int, struct mbuf **)), int, struct pfil_head *));
int pfil_remove_hook __P((int (*func) __P((void *, int,
struct ifnet *, int, struct mbuf **)), int, struct pfil_head *));
/* XXX */
#if defined(_KERNEL) && !defined(_LKM)
#include "ipfilter.h"
#endif
#if NIPFILTER > 0
#ifdef PFIL_HOOKS
#undef PFIL_HOOKS
#endif
#define PFIL_HOOKS
#endif /* NIPFILTER */
#endif /* _NET_PFIL_H_ */