1996-08-19 20:36:34 +00:00
|
|
|
/*-
|
1998-09-15 19:28:10 +00:00
|
|
|
* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
|
1996-08-19 20:36:34 +00:00
|
|
|
* 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,
|
|
|
|
* (net/enet.c) distributed as part of 4.3BSD, and code contributed
|
|
|
|
* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
|
|
|
|
* 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
|
|
|
|
* documentation and/or other materials provided with the distribution.
|
|
|
|
* 3. All advertising materials mentioning features or use of this software
|
|
|
|
* must display the following acknowledgement:
|
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|
|
* This product includes software developed by the University of
|
|
|
|
* 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
|
|
|
|
* 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
|
|
|
|
*/
|
1997-05-27 00:01:12 +00:00
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
#if !(defined(lint) || defined(KERNEL) || defined(_KERNEL))
|
1997-05-27 00:01:12 +00:00
|
|
|
static const char rcsid[] =
|
2001-04-03 04:18:09 +00:00
|
|
|
"@(#) $Header: /tcpdump/master/libpcap/bpf/net/bpf_filter.c,v 1.35 2000/10/23 19:32:21 fenner Exp $ (LBL)";
|
1996-08-19 20:36:34 +00:00
|
|
|
#endif
|
|
|
|
|
|
|
|
#include <sys/param.h>
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <sys/time.h>
|
2001-04-03 04:18:09 +00:00
|
|
|
|
|
|
|
#define SOLARIS (defined(sun) && (defined(__SVR4) || defined(__svr4__)))
|
|
|
|
#if defined(__hpux) || SOLARIS
|
|
|
|
# include <sys/sysmacros.h>
|
|
|
|
# include <sys/stream.h>
|
|
|
|
# define mbuf msgb
|
|
|
|
# define m_next b_cont
|
|
|
|
# define MLEN(m) ((m)->b_wptr - (m)->b_rptr)
|
|
|
|
# define mtod(m,t) ((t)(m)->b_rptr)
|
|
|
|
#else
|
|
|
|
# define MLEN(m) ((m)->m_len)
|
|
|
|
#endif
|
|
|
|
|
1996-08-19 20:36:34 +00:00
|
|
|
#include <net/bpf.h>
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
#if !defined(KERNEL) && !defined(_KERNEL)
|
1996-08-19 20:36:34 +00:00
|
|
|
#include <stdlib.h>
|
|
|
|
#endif
|
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|
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|
|
|
|
#define int32 bpf_int32
|
|
|
|
#define u_int32 bpf_u_int32
|
|
|
|
|
|
|
|
#ifndef LBL_ALIGN
|
|
|
|
#if defined(sparc) || defined(mips) || defined(ibm032) || \
|
|
|
|
defined(__alpha) || defined(__hpux)
|
|
|
|
#define LBL_ALIGN
|
|
|
|
#endif
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#ifndef LBL_ALIGN
|
|
|
|
#include <netinet/in.h>
|
|
|
|
|
|
|
|
#define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
|
|
|
|
#define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p))
|
|
|
|
#else
|
|
|
|
#define EXTRACT_SHORT(p)\
|
|
|
|
((u_short)\
|
|
|
|
((u_short)*((u_char *)p+0)<<8|\
|
|
|
|
(u_short)*((u_char *)p+1)<<0))
|
|
|
|
#define EXTRACT_LONG(p)\
|
|
|
|
((u_int32)*((u_char *)p+0)<<24|\
|
|
|
|
(u_int32)*((u_char *)p+1)<<16|\
|
|
|
|
(u_int32)*((u_char *)p+2)<<8|\
|
|
|
|
(u_int32)*((u_char *)p+3)<<0)
|
|
|
|
#endif
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
# if !defined(__hpux) && !SOLARIS
|
1996-08-19 20:36:34 +00:00
|
|
|
#include <sys/mbuf.h>
|
2001-04-03 04:18:09 +00:00
|
|
|
# endif
|
|
|
|
#define MINDEX(len, _m, _k) \
|
1996-08-19 20:36:34 +00:00
|
|
|
{ \
|
2001-04-03 04:18:09 +00:00
|
|
|
len = MLEN(m); \
|
|
|
|
while ((_k) >= len) { \
|
|
|
|
(_k) -= len; \
|
|
|
|
(_m) = (_m)->m_next; \
|
|
|
|
if ((_m) == 0) \
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0; \
|
2001-04-03 04:18:09 +00:00
|
|
|
len = MLEN(m); \
|
1996-08-19 20:36:34 +00:00
|
|
|
} \
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
m_xword(m, k, err)
|
|
|
|
register struct mbuf *m;
|
|
|
|
register int k, *err;
|
|
|
|
{
|
|
|
|
register int len;
|
|
|
|
register u_char *cp, *np;
|
|
|
|
register struct mbuf *m0;
|
|
|
|
|
|
|
|
MINDEX(len, m, k);
|
|
|
|
cp = mtod(m, u_char *) + k;
|
|
|
|
if (len - k >= 4) {
|
|
|
|
*err = 0;
|
|
|
|
return EXTRACT_LONG(cp);
|
|
|
|
}
|
|
|
|
m0 = m->m_next;
|
2001-04-03 04:18:09 +00:00
|
|
|
if (m0 == 0 || MLEN(m0) + len - k < 4)
|
1996-08-19 20:36:34 +00:00
|
|
|
goto bad;
|
|
|
|
*err = 0;
|
|
|
|
np = mtod(m0, u_char *);
|
|
|
|
switch (len - k) {
|
|
|
|
|
|
|
|
case 1:
|
|
|
|
return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];
|
|
|
|
|
|
|
|
case 2:
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|
|
|
return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];
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|
|
|
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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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|
|
|
bad:
|
|
|
|
*err = 1;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int
|
|
|
|
m_xhalf(m, k, err)
|
|
|
|
register struct mbuf *m;
|
|
|
|
register int k, *err;
|
|
|
|
{
|
|
|
|
register int len;
|
|
|
|
register u_char *cp;
|
|
|
|
register struct mbuf *m0;
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|
|
|
|
|
|
|
MINDEX(len, m, k);
|
|
|
|
cp = mtod(m, u_char *) + k;
|
|
|
|
if (len - k >= 2) {
|
|
|
|
*err = 0;
|
|
|
|
return EXTRACT_SHORT(cp);
|
|
|
|
}
|
|
|
|
m0 = m->m_next;
|
|
|
|
if (m0 == 0)
|
|
|
|
goto bad;
|
|
|
|
*err = 0;
|
|
|
|
return (cp[0] << 8) | mtod(m0, u_char *)[0];
|
|
|
|
bad:
|
|
|
|
*err = 1;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
#endif
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Execute the filter program starting at pc on the packet p
|
|
|
|
* wirelen is the length of the original packet
|
|
|
|
* buflen is the amount of data present
|
2001-04-03 04:18:09 +00:00
|
|
|
* For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0,
|
|
|
|
* in all other cases, p is a pointer to a buffer and buflen is its size.
|
1996-08-19 20:36:34 +00:00
|
|
|
*/
|
|
|
|
u_int
|
|
|
|
bpf_filter(pc, p, wirelen, buflen)
|
|
|
|
register struct bpf_insn *pc;
|
|
|
|
register u_char *p;
|
|
|
|
u_int wirelen;
|
|
|
|
register u_int buflen;
|
|
|
|
{
|
|
|
|
register u_int32 A, X;
|
|
|
|
register int k;
|
|
|
|
int32 mem[BPF_MEMWORDS];
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
struct mbuf *m, *n;
|
|
|
|
int merr, len;
|
|
|
|
|
|
|
|
if (buflen == 0) {
|
|
|
|
m = (struct mbuf *)p;
|
|
|
|
p = mtod(m, u_char *);
|
|
|
|
buflen = MLEN(m);
|
|
|
|
} else
|
|
|
|
m = NULL;
|
|
|
|
#endif
|
1996-08-19 20:36:34 +00:00
|
|
|
|
|
|
|
if (pc == 0)
|
|
|
|
/*
|
|
|
|
* No filter means accept all.
|
|
|
|
*/
|
|
|
|
return (u_int)-1;
|
|
|
|
A = 0;
|
|
|
|
X = 0;
|
|
|
|
--pc;
|
|
|
|
while (1) {
|
|
|
|
++pc;
|
|
|
|
switch (pc->code) {
|
|
|
|
|
|
|
|
default:
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
|
|
|
#else
|
|
|
|
abort();
|
|
|
|
#endif
|
|
|
|
case BPF_RET|BPF_K:
|
|
|
|
return (u_int)pc->k;
|
|
|
|
|
|
|
|
case BPF_RET|BPF_A:
|
|
|
|
return (u_int)A;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_W|BPF_ABS:
|
|
|
|
k = pc->k;
|
|
|
|
if (k + sizeof(int32) > buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
A = m_xword(m, k, &merr);
|
1996-08-19 20:36:34 +00:00
|
|
|
if (merr != 0)
|
|
|
|
return 0;
|
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = EXTRACT_LONG(&p[k]);
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_H|BPF_ABS:
|
|
|
|
k = pc->k;
|
|
|
|
if (k + sizeof(short) > buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
|
|
|
return 0;
|
|
|
|
A = m_xhalf(m, k, &merr);
|
|
|
|
if (merr != 0)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = EXTRACT_SHORT(&p[k]);
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_B|BPF_ABS:
|
|
|
|
k = pc->k;
|
|
|
|
if (k >= buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
n = m;
|
|
|
|
MINDEX(len, n, k);
|
|
|
|
A = mtod(n, u_char *)[k];
|
1996-08-19 20:36:34 +00:00
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = p[k];
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_W|BPF_LEN:
|
|
|
|
A = wirelen;
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LDX|BPF_W|BPF_LEN:
|
|
|
|
X = wirelen;
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_W|BPF_IND:
|
|
|
|
k = X + pc->k;
|
|
|
|
if (k + sizeof(int32) > buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
A = m_xword(m, k, &merr);
|
1996-08-19 20:36:34 +00:00
|
|
|
if (merr != 0)
|
|
|
|
return 0;
|
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = EXTRACT_LONG(&p[k]);
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_H|BPF_IND:
|
|
|
|
k = X + pc->k;
|
|
|
|
if (k + sizeof(short) > buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
A = m_xhalf(m, k, &merr);
|
1996-08-19 20:36:34 +00:00
|
|
|
if (merr != 0)
|
|
|
|
return 0;
|
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = EXTRACT_SHORT(&p[k]);
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LD|BPF_B|BPF_IND:
|
|
|
|
k = X + pc->k;
|
|
|
|
if (k >= buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
n = m;
|
|
|
|
MINDEX(len, n, k);
|
|
|
|
A = mtod(n, u_char *)[k];
|
1996-08-19 20:36:34 +00:00
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
A = p[k];
|
|
|
|
continue;
|
|
|
|
|
|
|
|
case BPF_LDX|BPF_MSH|BPF_B:
|
|
|
|
k = pc->k;
|
|
|
|
if (k >= buflen) {
|
2001-04-03 04:18:09 +00:00
|
|
|
#if defined(KERNEL) || defined(_KERNEL)
|
|
|
|
if (m == NULL)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
2001-04-03 04:18:09 +00:00
|
|
|
n = m;
|
|
|
|
MINDEX(len, n, k);
|
|
|
|
X = (mtod(n, char *)[k] & 0xf) << 2;
|
1996-08-19 20:36:34 +00:00
|
|
|
continue;
|
|
|
|
#else
|
|
|
|
return 0;
|
|
|
|
#endif
|
|
|
|
}
|
|
|
|
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;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2001-04-03 04:18:09 +00:00
|
|
|
|
1996-08-19 20:36:34 +00:00
|
|
|
/*
|
|
|
|
* Return true if the 'fcode' is a valid filter program.
|
|
|
|
* The constraints are that each jump be forward and to a valid
|
|
|
|
* code. The code must terminate with either an accept or reject.
|
|
|
|
* 'valid' is an array for use by the routine (it must be at least
|
|
|
|
* 'len' bytes long).
|
|
|
|
*
|
|
|
|
* 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;
|
|
|
|
{
|
|
|
|
register int i;
|
|
|
|
register struct bpf_insn *p;
|
|
|
|
|
|
|
|
for (i = 0; i < len; ++i) {
|
|
|
|
/*
|
|
|
|
* Check that that jumps are forward, and within
|
|
|
|
* the code block.
|
|
|
|
*/
|
|
|
|
p = &f[i];
|
|
|
|
if (BPF_CLASS(p->code) == BPF_JMP) {
|
|
|
|
register int from = i + 1;
|
|
|
|
|
|
|
|
if (BPF_OP(p->code) == BPF_JA) {
|
1998-09-15 19:28:10 +00:00
|
|
|
if (from + p->k >= (unsigned)len)
|
1996-08-19 20:36:34 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
else if (from + p->jt >= len || from + p->jf >= len)
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
/*
|
|
|
|
* Check that memory operations use valid addresses.
|
|
|
|
*/
|
|
|
|
if ((BPF_CLASS(p->code) == BPF_ST ||
|
|
|
|
(BPF_CLASS(p->code) == BPF_LD &&
|
|
|
|
(p->code & 0xe0) == BPF_MEM)) &&
|
|
|
|
(p->k >= BPF_MEMWORDS || p->k < 0))
|
|
|
|
return 0;
|
|
|
|
/*
|
|
|
|
* Check for constant division by 0.
|
|
|
|
*/
|
|
|
|
if (p->code == (BPF_ALU|BPF_DIV|BPF_K) && p->k == 0)
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
return BPF_CLASS(f[len - 1].code) == BPF_RET;
|
|
|
|
}
|