Lost on import
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darrenr
parent
56581d9c24
commit
3646154e14
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@ -0,0 +1,595 @@
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/* $NetBSD: bpf_filter.c,v 1.4 2012/01/30 19:38:45 darrenr Exp $ */
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/*-
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* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from the Stanford/CMU enet packet filter,
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* (net/enet.c) distributed as part of 4.3BSD, and code contributed
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* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
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* Berkeley Laboratory.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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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* @(#)bpf.c 7.5 (Berkeley) 7/15/91
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*/
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#if !(defined(lint) || defined(KERNEL) || defined(_KERNEL))
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static const char rcsid[] =
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"@(#) Header: /devel/CVS/IP-Filter/bpf_filter.c,v 2.2.2.3 2006/10/03 11:25:56 darrenr Exp (LBL)";
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#endif
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <net/if.h>
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#include "netinet/ip_compat.h"
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#include "bpf-ipf.h"
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#if (defined(__hpux) || SOLARIS) && (defined(_KERNEL) || defined(KERNEL))
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# include <sys/sysmacros.h>
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# include <sys/stream.h>
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#endif
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#include "pcap-ipf.h"
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#if !defined(KERNEL) && !defined(_KERNEL)
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#include <stdlib.h>
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#endif
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#define int32 bpf_int32
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#define u_int32 bpf_u_int32
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static int m_xword __P((mb_t *, int, int *));
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static int m_xhalf __P((mb_t *, int, int *));
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#ifndef LBL_ALIGN
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/*
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* XXX - IA-64? If not, this probably won't work on Win64 IA-64
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* systems, unless LBL_ALIGN is defined elsewhere for them.
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* XXX - SuperH? If not, this probably won't work on WinCE SuperH
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* systems, unless LBL_ALIGN is defined elsewhere for them.
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*/
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#if defined(sparc) || defined(__sparc__) || defined(mips) || \
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defined(ibm032) || defined(__alpha) || defined(__hpux) || \
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defined(__arm__)
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#define LBL_ALIGN
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#endif
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#endif
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#ifndef LBL_ALIGN
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#define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
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#define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p))
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#else
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#define EXTRACT_SHORT(p)\
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((u_short)\
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((u_short)*((u_char *)p+0)<<8|\
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(u_short)*((u_char *)p+1)<<0))
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#define EXTRACT_LONG(p)\
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((u_int32)*((u_char *)p+0)<<24|\
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(u_int32)*((u_char *)p+1)<<16|\
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(u_int32)*((u_char *)p+2)<<8|\
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(u_int32)*((u_char *)p+3)<<0)
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#endif
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#define MINDEX(len, _m, _k) \
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{ \
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len = M_LEN(m); \
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while ((_k) >= len) { \
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(_k) -= len; \
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(_m) = (_m)->m_next; \
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if ((_m) == 0) \
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return 0; \
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len = M_LEN(m); \
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} \
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}
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static int
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m_xword(m, k, err)
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register mb_t *m;
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register int k, *err;
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{
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register int len;
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register u_char *cp, *np;
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register mb_t *m0;
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MINDEX(len, m, k);
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cp = MTOD(m, u_char *) + k;
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if (len - k >= 4) {
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*err = 0;
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return EXTRACT_LONG(cp);
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}
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m0 = m->m_next;
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if (m0 == 0 || M_LEN(m0) + len - k < 4)
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goto bad;
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*err = 0;
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np = MTOD(m0, u_char *);
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switch (len - k) {
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case 1:
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return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];
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case 2:
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return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];
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default:
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return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | np[0];
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}
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bad:
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*err = 1;
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return 0;
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}
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static int
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m_xhalf(m, k, err)
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register mb_t *m;
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register int k, *err;
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{
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register int len;
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register u_char *cp;
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register mb_t *m0;
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MINDEX(len, m, k);
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cp = MTOD(m, u_char *) + k;
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if (len - k >= 2) {
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*err = 0;
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return EXTRACT_SHORT(cp);
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}
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m0 = m->m_next;
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if (m0 == 0)
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goto bad;
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*err = 0;
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return (cp[0] << 8) | MTOD(m0, u_char *)[0];
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bad:
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*err = 1;
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return 0;
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}
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/*
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* Execute the filter program starting at pc on the packet p
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* wirelen is the length of the original packet
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* buflen is the amount of data present
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* For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0,
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* in all other cases, p is a pointer to a buffer and buflen is its size.
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*/
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u_int
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bpf_filter(pc, p, wirelen, buflen)
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register struct bpf_insn *pc;
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register u_char *p;
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u_int wirelen;
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register u_int buflen;
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{
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register u_int32 A, X;
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register int k;
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int32 mem[BPF_MEMWORDS];
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mb_t *m, *n;
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int merr = 0; /* XXX: GCC */
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int len;
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if (buflen == 0) {
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m = (mb_t *)p;
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p = MTOD(m, u_char *);
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buflen = M_LEN(m);
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} else
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m = NULL;
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if (pc == 0)
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/*
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* No filter means accept all.
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*/
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return (u_int)-1;
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A = 0;
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X = 0;
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--pc;
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while (1) {
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++pc;
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switch (pc->code) {
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default:
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return 0;
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case BPF_RET|BPF_K:
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return (u_int)pc->k;
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case BPF_RET|BPF_A:
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return (u_int)A;
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case BPF_LD|BPF_W|BPF_ABS:
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k = pc->k;
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if (k + sizeof(int32) > buflen) {
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if (m == NULL)
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return 0;
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A = m_xword(m, k, &merr);
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if (merr != 0)
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return 0;
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continue;
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}
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A = EXTRACT_LONG(&p[k]);
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continue;
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case BPF_LD|BPF_H|BPF_ABS:
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k = pc->k;
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if (k + sizeof(short) > buflen) {
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if (m == NULL)
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return 0;
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A = m_xhalf(m, k, &merr);
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if (merr != 0)
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return 0;
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continue;
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}
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A = EXTRACT_SHORT(&p[k]);
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continue;
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case BPF_LD|BPF_B|BPF_ABS:
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k = pc->k;
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if (k >= buflen) {
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if (m == NULL)
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return 0;
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n = m;
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MINDEX(len, n, k);
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A = MTOD(n, u_char *)[k];
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continue;
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}
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A = p[k];
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continue;
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case BPF_LD|BPF_W|BPF_LEN:
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A = wirelen;
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continue;
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case BPF_LDX|BPF_W|BPF_LEN:
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X = wirelen;
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continue;
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case BPF_LD|BPF_W|BPF_IND:
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k = X + pc->k;
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if (k + sizeof(int32) > buflen) {
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if (m == NULL)
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return 0;
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A = m_xword(m, k, &merr);
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if (merr != 0)
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return 0;
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continue;
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}
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A = EXTRACT_LONG(&p[k]);
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continue;
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case BPF_LD|BPF_H|BPF_IND:
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k = X + pc->k;
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if (k + sizeof(short) > buflen) {
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if (m == NULL)
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return 0;
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A = m_xhalf(m, k, &merr);
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if (merr != 0)
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return 0;
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continue;
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||||
}
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A = EXTRACT_SHORT(&p[k]);
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continue;
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case BPF_LD|BPF_B|BPF_IND:
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k = X + pc->k;
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if (k >= buflen) {
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if (m == NULL)
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return 0;
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n = m;
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MINDEX(len, n, k);
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A = MTOD(n, u_char *)[k];
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||||
continue;
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||||
}
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A = p[k];
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||||
continue;
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||||
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||||
case BPF_LDX|BPF_MSH|BPF_B:
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||||
k = pc->k;
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||||
if (k >= buflen) {
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||||
if (m == NULL)
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return 0;
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||||
n = m;
|
||||
MINDEX(len, n, k);
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||||
X = (MTOD(n, char *)[k] & 0xf) << 2;
|
||||
continue;
|
||||
}
|
||||
X = (p[pc->k] & 0xf) << 2;
|
||||
continue;
|
||||
|
||||
case BPF_LD|BPF_IMM:
|
||||
A = pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_LDX|BPF_IMM:
|
||||
X = pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_LD|BPF_MEM:
|
||||
A = mem[pc->k];
|
||||
continue;
|
||||
|
||||
case BPF_LDX|BPF_MEM:
|
||||
X = mem[pc->k];
|
||||
continue;
|
||||
|
||||
case BPF_ST:
|
||||
mem[pc->k] = A;
|
||||
continue;
|
||||
|
||||
case BPF_STX:
|
||||
mem[pc->k] = X;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JA:
|
||||
pc += pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JGT|BPF_K:
|
||||
pc += (A > pc->k) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JGE|BPF_K:
|
||||
pc += (A >= pc->k) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JEQ|BPF_K:
|
||||
pc += (A == pc->k) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JSET|BPF_K:
|
||||
pc += (A & pc->k) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JGT|BPF_X:
|
||||
pc += (A > X) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JGE|BPF_X:
|
||||
pc += (A >= X) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JEQ|BPF_X:
|
||||
pc += (A == X) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_JMP|BPF_JSET|BPF_X:
|
||||
pc += (A & X) ? pc->jt : pc->jf;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_ADD|BPF_X:
|
||||
A += X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_SUB|BPF_X:
|
||||
A -= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_MUL|BPF_X:
|
||||
A *= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_DIV|BPF_X:
|
||||
if (X == 0)
|
||||
return 0;
|
||||
A /= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_AND|BPF_X:
|
||||
A &= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_OR|BPF_X:
|
||||
A |= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_LSH|BPF_X:
|
||||
A <<= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_RSH|BPF_X:
|
||||
A >>= X;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_ADD|BPF_K:
|
||||
A += pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_SUB|BPF_K:
|
||||
A -= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_MUL|BPF_K:
|
||||
A *= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_DIV|BPF_K:
|
||||
A /= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_AND|BPF_K:
|
||||
A &= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_OR|BPF_K:
|
||||
A |= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_LSH|BPF_K:
|
||||
A <<= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_RSH|BPF_K:
|
||||
A >>= pc->k;
|
||||
continue;
|
||||
|
||||
case BPF_ALU|BPF_NEG:
|
||||
A = -A;
|
||||
continue;
|
||||
|
||||
case BPF_MISC|BPF_TAX:
|
||||
X = A;
|
||||
continue;
|
||||
|
||||
case BPF_MISC|BPF_TXA:
|
||||
A = X;
|
||||
continue;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Return true if the 'fcode' is a valid filter program.
|
||||
* The constraints are that each jump be forward and to a valid
|
||||
* code, that memory accesses are within valid ranges (to the
|
||||
* extent that this can be checked statically; loads of packet
|
||||
* data have to be, and are, also checked at run time), and that
|
||||
* the code terminates with either an accept or reject.
|
||||
*
|
||||
* The kernel needs to be able to verify an application's filter code.
|
||||
* Otherwise, a bogus program could easily crash the system.
|
||||
*/
|
||||
int
|
||||
bpf_validate(f, len)
|
||||
struct bpf_insn *f;
|
||||
int len;
|
||||
{
|
||||
u_int i, from;
|
||||
const struct bpf_insn *p;
|
||||
|
||||
if (len == 0)
|
||||
return 1;
|
||||
|
||||
if (len < 1 || len > BPF_MAXINSNS)
|
||||
return 0;
|
||||
|
||||
for (i = 0; i < len; ++i) {
|
||||
p = &f[i];
|
||||
switch (BPF_CLASS(p->code)) {
|
||||
/*
|
||||
* Check that memory operations use valid addresses.
|
||||
*/
|
||||
case BPF_LD:
|
||||
case BPF_LDX:
|
||||
switch (BPF_MODE(p->code)) {
|
||||
case BPF_IMM:
|
||||
break;
|
||||
case BPF_ABS:
|
||||
case BPF_IND:
|
||||
case BPF_MSH:
|
||||
/*
|
||||
* More strict check with actual packet length
|
||||
* is done runtime.
|
||||
*/
|
||||
#if 0
|
||||
if (p->k >= bpf_maxbufsize)
|
||||
return 0;
|
||||
#endif
|
||||
break;
|
||||
case BPF_MEM:
|
||||
if (p->k >= BPF_MEMWORDS)
|
||||
return 0;
|
||||
break;
|
||||
case BPF_LEN:
|
||||
break;
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
break;
|
||||
case BPF_ST:
|
||||
case BPF_STX:
|
||||
if (p->k >= BPF_MEMWORDS)
|
||||
return 0;
|
||||
break;
|
||||
case BPF_ALU:
|
||||
switch (BPF_OP(p->code)) {
|
||||
case BPF_ADD:
|
||||
case BPF_SUB:
|
||||
case BPF_OR:
|
||||
case BPF_AND:
|
||||
case BPF_LSH:
|
||||
case BPF_RSH:
|
||||
case BPF_NEG:
|
||||
break;
|
||||
case BPF_DIV:
|
||||
/*
|
||||
* Check for constant division by 0.
|
||||
*/
|
||||
if (BPF_RVAL(p->code) == BPF_K && p->k == 0)
|
||||
return 0;
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
break;
|
||||
case BPF_JMP:
|
||||
/*
|
||||
* Check that jumps are within the code block,
|
||||
* and that unconditional branches don't go
|
||||
* backwards as a result of an overflow.
|
||||
* Unconditional branches have a 32-bit offset,
|
||||
* so they could overflow; we check to make
|
||||
* sure they don't. Conditional branches have
|
||||
* an 8-bit offset, and the from address is <=
|
||||
* BPF_MAXINSNS, and we assume that BPF_MAXINSNS
|
||||
* is sufficiently small that adding 255 to it
|
||||
* won't overflow.
|
||||
*
|
||||
* We know that len is <= BPF_MAXINSNS, and we
|
||||
* assume that BPF_MAXINSNS is < the maximum size
|
||||
* of a u_int, so that i + 1 doesn't overflow.
|
||||
*/
|
||||
from = i + 1;
|
||||
switch (BPF_OP(p->code)) {
|
||||
case BPF_JA:
|
||||
if (from + p->k < from || from + p->k >= len)
|
||||
return 0;
|
||||
break;
|
||||
case BPF_JEQ:
|
||||
case BPF_JGT:
|
||||
case BPF_JGE:
|
||||
case BPF_JSET:
|
||||
if (from + p->jt >= len || from + p->jf >= len)
|
||||
return 0;
|
||||
break;
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
break;
|
||||
case BPF_RET:
|
||||
break;
|
||||
case BPF_MISC:
|
||||
break;
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
}
|
||||
return BPF_CLASS(f[len - 1].code) == BPF_RET;
|
||||
}
|
||||
Loading…
Reference in New Issue