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d087080c1f
accept filters and prevent read-modify-write races.
163 lines
4.5 KiB
C
163 lines
4.5 KiB
C
/*
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* Copyright (c) 2000 Paycounter, Inc.
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* Author: Alfred Perlstein <alfred@paycounter.com>, <alfred@FreeBSD.org>
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, 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/cdefs.h>
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__FBSDID("$FreeBSD$");
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#define ACCEPT_FILTER_MOD
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#include "opt_param.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/domain.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/module.h>
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#include <sys/mutex.h>
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#include <sys/protosw.h>
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#include <sys/sysctl.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <sys/queue.h>
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static struct mtx accept_filter_mtx;
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MTX_SYSINIT(accept_filter, &accept_filter_mtx, "accept_filter_mtx",
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MTX_DEF);
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#define ACCEPT_FILTER_LOCK() mtx_lock(&accept_filter_mtx)
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#define ACCEPT_FILTER_UNLOCK() mtx_unlock(&accept_filter_mtx)
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static SLIST_HEAD(, accept_filter) accept_filtlsthd =
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SLIST_HEAD_INITIALIZER(&accept_filtlsthd);
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MALLOC_DEFINE(M_ACCF, "accf", "accept filter data");
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static int unloadable = 0;
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SYSCTL_DECL(_net_inet); /* XXX: some header should do this for me */
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SYSCTL_NODE(_net_inet, OID_AUTO, accf, CTLFLAG_RW, 0, "Accept filters");
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SYSCTL_INT(_net_inet_accf, OID_AUTO, unloadable, CTLFLAG_RW, &unloadable, 0,
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"Allow unload of accept filters (not recommended)");
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/*
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* must be passed a malloc'd structure so we don't explode if the kld
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* is unloaded, we leak the struct on deallocation to deal with this,
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* but if a filter is loaded with the same name as a leaked one we re-use
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* the entry.
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*/
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int
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accept_filt_add(struct accept_filter *filt)
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{
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struct accept_filter *p;
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ACCEPT_FILTER_LOCK();
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SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
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if (strcmp(p->accf_name, filt->accf_name) == 0) {
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if (p->accf_callback != NULL) {
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ACCEPT_FILTER_UNLOCK();
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return (EEXIST);
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} else {
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p->accf_callback = filt->accf_callback;
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ACCEPT_FILTER_UNLOCK();
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FREE(filt, M_ACCF);
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return (0);
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}
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}
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if (p == NULL)
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SLIST_INSERT_HEAD(&accept_filtlsthd, filt, accf_next);
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ACCEPT_FILTER_UNLOCK();
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return (0);
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}
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int
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accept_filt_del(char *name)
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{
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struct accept_filter *p;
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p = accept_filt_get(name);
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if (p == NULL)
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return (ENOENT);
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p->accf_callback = NULL;
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return (0);
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}
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struct accept_filter *
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accept_filt_get(char *name)
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{
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struct accept_filter *p;
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ACCEPT_FILTER_LOCK();
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SLIST_FOREACH(p, &accept_filtlsthd, accf_next)
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if (strcmp(p->accf_name, name) == 0)
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break;
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ACCEPT_FILTER_UNLOCK();
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return (p);
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}
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int
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accept_filt_generic_mod_event(module_t mod, int event, void *data)
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{
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struct accept_filter *p;
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struct accept_filter *accfp = (struct accept_filter *) data;
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int error;
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switch (event) {
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case MOD_LOAD:
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MALLOC(p, struct accept_filter *, sizeof(*p), M_ACCF, M_WAITOK);
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bcopy(accfp, p, sizeof(*p));
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error = accept_filt_add(p);
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break;
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case MOD_UNLOAD:
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/*
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* Do not support unloading yet. we don't keep track of refcounts
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* and unloading an accept filter callback and then having it called
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* is a bad thing. A simple fix would be to track the refcount
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* in the struct accept_filter.
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*/
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if (unloadable != 0) {
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error = accept_filt_del(accfp->accf_name);
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} else
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error = EOPNOTSUPP;
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break;
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case MOD_SHUTDOWN:
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error = 0;
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break;
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default:
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error = EOPNOTSUPP;
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break;
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}
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return (error);
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}
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