384 lines
9.1 KiB
C
384 lines
9.1 KiB
C
/* $FreeBSD$ */
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/* $NetBSD: pfil.c,v 1.20 2001/11/12 23:49:46 lukem Exp $ */
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/*-
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* Copyright (c) 1996 Matthew R. Green
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/errno.h>
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#include <sys/malloc.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/systm.h>
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#include <sys/condvar.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/queue.h>
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#include <net/if.h>
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#include <net/pfil.h>
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static struct mtx pfil_global_lock;
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MTX_SYSINIT(pfil_heads_lock, &pfil_global_lock, "pfil_head_list lock", MTX_DEF);
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static int pfil_list_add(pfil_list_t *, struct packet_filter_hook *, int);
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static int pfil_list_remove(pfil_list_t *,
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int (*)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *);
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LIST_HEAD(, pfil_head) pfil_head_list =
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LIST_HEAD_INITIALIZER(&pfil_head_list);
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static __inline void
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PFIL_RLOCK(struct pfil_head *ph)
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{
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mtx_lock(&ph->ph_mtx);
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ph->ph_busy_count++;
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mtx_unlock(&ph->ph_mtx);
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}
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static __inline void
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PFIL_RUNLOCK(struct pfil_head *ph)
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{
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mtx_lock(&ph->ph_mtx);
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ph->ph_busy_count--;
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if (ph->ph_busy_count == 0 && ph->ph_want_write)
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cv_signal(&ph->ph_cv);
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mtx_unlock(&ph->ph_mtx);
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}
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static __inline void
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PFIL_WLOCK(struct pfil_head *ph)
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{
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mtx_lock(&ph->ph_mtx);
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ph->ph_want_write = 1;
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while (ph->ph_busy_count > 0)
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cv_wait(&ph->ph_cv, &ph->ph_mtx);
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}
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static __inline int
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PFIL_TRY_WLOCK(struct pfil_head *ph)
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{
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mtx_lock(&ph->ph_mtx);
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ph->ph_want_write = 1;
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if (ph->ph_busy_count > 0) {
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ph->ph_want_write = 0;
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mtx_unlock(&ph->ph_mtx);
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return EBUSY;
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}
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return 0;
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}
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static __inline void
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PFIL_WUNLOCK(struct pfil_head *ph)
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{
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ph->ph_want_write = 0;
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cv_signal(&ph->ph_cv);
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mtx_unlock(&ph->ph_mtx);
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}
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#define PFIL_LIST_LOCK() mtx_lock(&pfil_global_lock)
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#define PFIL_LIST_UNLOCK() mtx_unlock(&pfil_global_lock)
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/*
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* pfil_run_hooks() runs the specified packet filter hooks.
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*/
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int
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pfil_run_hooks(struct pfil_head *ph, struct mbuf **mp, struct ifnet *ifp,
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int dir, struct inpcb *inp)
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{
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struct packet_filter_hook *pfh;
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struct mbuf *m = *mp;
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int rv = 0;
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/*
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* Prevent packet filtering from starving the modification of
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* the packet filters. We would prefer a reader/writer locking
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* mechanism with guaranteed ordering, though.
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*/
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if (ph->ph_busy_count == -1 || ph->ph_want_write) {
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m_freem(*mp);
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*mp = NULL;
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return (ENOBUFS);
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}
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PFIL_RLOCK(ph);
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for (pfh = pfil_hook_get(dir, ph); pfh != NULL;
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pfh = TAILQ_NEXT(pfh, pfil_link)) {
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if (pfh->pfil_func != NULL) {
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rv = (*pfh->pfil_func)(pfh->pfil_arg, &m, ifp, dir, inp);
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if (rv != 0 || m == NULL)
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break;
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}
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}
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PFIL_RUNLOCK(ph);
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*mp = m;
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return (rv);
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}
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/*
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* pfil_head_register() registers a pfil_head with the packet filter
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* hook mechanism.
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*/
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int
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pfil_head_register(struct pfil_head *ph)
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{
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struct pfil_head *lph;
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PFIL_LIST_LOCK();
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LIST_FOREACH(lph, &pfil_head_list, ph_list)
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if (ph->ph_type == lph->ph_type &&
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ph->ph_un.phu_val == lph->ph_un.phu_val) {
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PFIL_LIST_UNLOCK();
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return EEXIST;
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}
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PFIL_LIST_UNLOCK();
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if (mtx_initialized(&ph->ph_mtx)) { /* should not happen */
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KASSERT((0), ("%s: allready initialized!", __func__));
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return EBUSY;
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} else {
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ph->ph_busy_count = -1;
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ph->ph_want_write = 1;
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mtx_init(&ph->ph_mtx, "pfil_head_mtx", NULL, MTX_DEF);
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cv_init(&ph->ph_cv, "pfil_head_cv");
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mtx_lock(&ph->ph_mtx); /* XXX: race? */
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}
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TAILQ_INIT(&ph->ph_in);
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TAILQ_INIT(&ph->ph_out);
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PFIL_LIST_LOCK();
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LIST_INSERT_HEAD(&pfil_head_list, ph, ph_list);
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PFIL_LIST_UNLOCK();
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PFIL_WUNLOCK(ph);
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return (0);
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}
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/*
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* pfil_head_unregister() removes a pfil_head from the packet filter
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* hook mechanism.
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*/
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int
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pfil_head_unregister(struct pfil_head *ph)
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{
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struct packet_filter_hook *pfh, *pfnext;
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PFIL_LIST_LOCK();
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/*
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* LIST_REMOVE is safe for unlocked pfil_heads in ph_list.
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* No need to WLOCK all of them.
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*/
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LIST_REMOVE(ph, ph_list);
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PFIL_LIST_UNLOCK();
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PFIL_WLOCK(ph); /* XXX: may sleep (cv_wait)! */
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TAILQ_FOREACH_SAFE(pfh, &ph->ph_in, pfil_link, pfnext)
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free(pfh, M_IFADDR);
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TAILQ_FOREACH_SAFE(pfh, &ph->ph_out, pfil_link, pfnext)
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free(pfh, M_IFADDR);
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cv_destroy(&ph->ph_cv);
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mtx_destroy(&ph->ph_mtx);
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return (0);
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}
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/*
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* pfil_head_get() returns the pfil_head for a given key/dlt.
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*/
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struct pfil_head *
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pfil_head_get(int type, u_long val)
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{
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struct pfil_head *ph;
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PFIL_LIST_LOCK();
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LIST_FOREACH(ph, &pfil_head_list, ph_list)
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if (ph->ph_type == type && ph->ph_un.phu_val == val)
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break;
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PFIL_LIST_UNLOCK();
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return (ph);
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}
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/*
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* pfil_add_hook() adds a function to the packet filter hook. the
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* flags are:
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* PFIL_IN call me on incoming packets
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* PFIL_OUT call me on outgoing packets
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* PFIL_ALL call me on all of the above
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* PFIL_WAITOK OK to call malloc with M_WAITOK.
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*/
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int
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pfil_add_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
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void *arg, int flags, struct pfil_head *ph)
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{
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struct packet_filter_hook *pfh1 = NULL;
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struct packet_filter_hook *pfh2 = NULL;
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int err;
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/* Get memory */
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if (flags & PFIL_IN) {
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pfh1 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
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M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
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if (pfh1 == NULL) {
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err = ENOMEM;
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goto error;
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}
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}
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if (flags & PFIL_OUT) {
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pfh2 = (struct packet_filter_hook *)malloc(sizeof(*pfh1),
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M_IFADDR, (flags & PFIL_WAITOK) ? M_WAITOK : M_NOWAIT);
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if (pfh2 == NULL) {
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err = ENOMEM;
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goto error;
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}
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}
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/* Lock */
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if (flags & PFIL_WAITOK)
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PFIL_WLOCK(ph);
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else {
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err = PFIL_TRY_WLOCK(ph);
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if (err)
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goto error;
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}
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/* Add */
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if (flags & PFIL_IN) {
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pfh1->pfil_func = func;
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pfh1->pfil_arg = arg;
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err = pfil_list_add(&ph->ph_in, pfh1, flags & ~PFIL_OUT);
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if (err)
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goto done;
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}
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if (flags & PFIL_OUT) {
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pfh2->pfil_func = func;
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pfh2->pfil_arg = arg;
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err = pfil_list_add(&ph->ph_out, pfh2, flags & ~PFIL_IN);
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if (err) {
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if (flags & PFIL_IN)
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pfil_list_remove(&ph->ph_in, func, arg);
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goto done;
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}
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}
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ph->ph_busy_count = 0;
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PFIL_WUNLOCK(ph);
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return 0;
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done:
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PFIL_WUNLOCK(ph);
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error:
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if (pfh1 != NULL)
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free(pfh1, M_IFADDR);
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if (pfh2 != NULL)
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free(pfh2, M_IFADDR);
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return err;
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}
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/*
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* pfil_remove_hook removes a specific function from the packet filter
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* hook list.
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*/
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int
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pfil_remove_hook(int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *),
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void *arg, int flags, struct pfil_head *ph)
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{
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int err = 0;
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if (flags & PFIL_WAITOK)
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PFIL_WLOCK(ph);
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else {
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err = PFIL_TRY_WLOCK(ph);
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if (err)
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return err;
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}
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if (flags & PFIL_IN)
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err = pfil_list_remove(&ph->ph_in, func, arg);
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if ((err == 0) && (flags & PFIL_OUT))
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err = pfil_list_remove(&ph->ph_out, func, arg);
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if (TAILQ_EMPTY(&ph->ph_in) && TAILQ_EMPTY(&ph->ph_out))
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ph->ph_busy_count = -1;
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PFIL_WUNLOCK(ph);
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return err;
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}
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static int
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pfil_list_add(pfil_list_t *list, struct packet_filter_hook *pfh1, int flags)
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{
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struct packet_filter_hook *pfh;
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/*
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* First make sure the hook is not already there.
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*/
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TAILQ_FOREACH(pfh, list, pfil_link)
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if (pfh->pfil_func == pfh1->pfil_func &&
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pfh->pfil_arg == pfh1->pfil_arg)
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return EEXIST;
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/*
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* insert the input list in reverse order of the output list
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* so that the same path is followed in or out of the kernel.
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*/
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if (flags & PFIL_IN)
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TAILQ_INSERT_HEAD(list, pfh1, pfil_link);
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else
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TAILQ_INSERT_TAIL(list, pfh1, pfil_link);
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return 0;
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}
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/*
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* pfil_list_remove is an internal function that takes a function off the
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* specified list.
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*/
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static int
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pfil_list_remove(pfil_list_t *list,
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int (*func)(void *, struct mbuf **, struct ifnet *, int, struct inpcb *), void *arg)
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{
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struct packet_filter_hook *pfh;
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TAILQ_FOREACH(pfh, list, pfil_link)
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if (pfh->pfil_func == func && pfh->pfil_arg == arg) {
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TAILQ_REMOVE(list, pfh, pfil_link);
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free(pfh, M_IFADDR);
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return 0;
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}
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return ENOENT;
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}
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