Add pfil(9) subroutines and manpage from NetBSD.

3 files changed, 391 insertions, 0 deletions

diff --git a/sys/net/pfil.9 b/sys/net/pfil.9
new file mode 100644
index 0000000..a7eb36f
--- /dev/null
+++ b/sys/net/pfil.9
@@ -0,0 +1,134 @@
+.\"	$FreeBSD$
+.\"
+.\" 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
diff --git a/sys/net/pfil.c b/sys/net/pfil.c
new file mode 100644
index 0000000..67501ee
--- /dev/null
+++ b/sys/net/pfil.c
@@ -0,0 +1,176 @@
+/*	$FreeBSD$	*/
+
+/*
+ * 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;
+}
diff --git a/sys/net/pfil.h b/sys/net/pfil.h
new file mode 100644
index 0000000..7831328
--- /dev/null
+++ b/sys/net/pfil.h
@@ -0,0 +1,81 @@
+/*	$FreeBSD$	*/
+
+/*
+ * 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_ */