[apple/xnu.git] / bsd / net / bpf_filter.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1990, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
 *
 *      @(#)bpf_filter.c	8.1 (Berkeley) 6/10/93
 *
 * $FreeBSD: src/sys/net/bpf_filter.c,v 1.17 1999/12/29 04:38:31 peter Exp $
 */

#include <sys/param.h>

#ifdef sun
#include <netinet/in.h>
#endif

#if defined(sparc) || defined(mips) || defined(ibm032) || defined(__alpha__)
#define BPF_ALIGN
#endif

#ifndef BPF_ALIGN
#define EXTRACT_SHORT(p)	((u_int16_t)ntohs(*(u_int16_t *)p))
#define EXTRACT_LONG(p)		(ntohl(*(u_int32_t *)p))
#else
#define EXTRACT_SHORT(p)\
	((u_int16_t)\
		((u_int16_t)*((u_char *)p+0)<<8|\
		 (u_int16_t)*((u_char *)p+1)<<0))
#define EXTRACT_LONG(p)\
		((u_int32_t)*((u_char *)p+0)<<24|\
		 (u_int32_t)*((u_char *)p+1)<<16|\
		 (u_int32_t)*((u_char *)p+2)<<8|\
		 (u_int32_t)*((u_char *)p+3)<<0)
#endif

#ifdef KERNEL
#include <sys/mbuf.h>
#endif
#include <net/bpf.h>
#ifdef KERNEL
#define MINDEX(m, k) \
{ \
	register unsigned int len = m->m_len; \
 \
	while (k >= len) { \
		k -= len; \
		m = m->m_next; \
		if (m == 0) \
			return 0; \
		len = m->m_len; \
	} \
}

static u_int16_t	m_xhalf(struct mbuf *m, bpf_u_int32 k, int *err);
static u_int32_t	m_xword(struct mbuf *m, bpf_u_int32 k, int *err);

static u_int32_t
m_xword(struct mbuf *m, bpf_u_int32 k, int *err)
{
	register size_t len;
	register u_char *cp, *np;
	register struct mbuf *m0;

	len = m->m_len;
	while (k >= len) {
		k -= len;
		m = m->m_next;
		if (m == 0)
			goto bad;
		len = m->m_len;
	}
	cp = mtod(m, u_char *) + k;
	if (len - k >= 4) {
		*err = 0;
		return EXTRACT_LONG(cp);
	}
	m0 = m->m_next;
	if (m0 == 0 || m0->m_len + len - k < 4)
		goto bad;
	*err = 0;
	np = mtod(m0, u_char *);
	switch (len - k) {

	case 1:
		return
		    ((u_int32_t)cp[0] << 24) |
		    ((u_int32_t)np[0] << 16) |
		    ((u_int32_t)np[1] << 8)  |
		    (u_int32_t)np[2];

	case 2:
		return
		    ((u_int32_t)cp[0] << 24) |
		    ((u_int32_t)cp[1] << 16) |
		    ((u_int32_t)np[0] << 8) |
		    (u_int32_t)np[1];

	default:
		return
		    ((u_int32_t)cp[0] << 24) |
		    ((u_int32_t)cp[1] << 16) |
		    ((u_int32_t)cp[2] << 8) |
		    (u_int32_t)np[0];
	}
    bad:
	*err = 1;
	return 0;
}

static u_int16_t
m_xhalf(struct mbuf *m, bpf_u_int32 k, int *err)
{
	register size_t len;
	register u_char *cp;
	register struct mbuf *m0;

	len = m->m_len;
	while (k >= len) {
		k -= len;
		m = m->m_next;
		if (m == 0)
			goto bad;
		len = m->m_len;
	}
	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
 */
u_int
bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
{
	register u_int32_t A = 0, X = 0;
	register bpf_u_int32 k;
	int32_t mem[BPF_MEMWORDS];

	if (pc == 0)
		/*
		 * No filter means accept all.
		 */
		return (u_int)-1;

	--pc;
	while (1) {
		++pc;
		switch (pc->code) {

		default:
#ifdef KERNEL
			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 > buflen || sizeof(int32_t) > buflen - k) {
#ifdef KERNEL
				int merr;

				if (buflen != 0)
					return 0;
				A = m_xword((struct mbuf *)p, k, &merr);
				if (merr != 0)
					return 0;
				continue;
#else
				return 0;
#endif
			}
#if BPF_ALIGN
			if (((intptr_t)(p + k) & 3) != 0)
				A = EXTRACT_LONG(&p[k]);
			else
#endif
				A = ntohl(*(int32_t *)(p + k));
			continue;

		case BPF_LD|BPF_H|BPF_ABS:
			k = pc->k;
			if (k > buflen || sizeof(int16_t) > buflen - k) {
#ifdef KERNEL
				int merr;

				if (buflen != 0)
					return 0;
				A = m_xhalf((struct mbuf *)p, k, &merr);
				continue;
#else
				return 0;
#endif
			}
			A = EXTRACT_SHORT(&p[k]);
			continue;

		case BPF_LD|BPF_B|BPF_ABS:
			k = pc->k;
			if (k >= buflen) {
#ifdef KERNEL
				register struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)p;
				MINDEX(m, k);
				A = mtod(m, u_char *)[k];
				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 (pc->k > buflen || X > buflen - pc->k ||
			    sizeof(int32_t) > buflen - k) {
#ifdef KERNEL
				int merr;

				if (buflen != 0)
					return 0;
				A = m_xword((struct mbuf *)p, k, &merr);
				if (merr != 0)
					return 0;
				continue;
#else
				return 0;
#endif
			}
#if BPF_ALIGN
			if (((intptr_t)(p + k) & 3) != 0)
				A = EXTRACT_LONG(&p[k]);
			else
#endif
				A = ntohl(*(int32_t *)(p + k));
			continue;

		case BPF_LD|BPF_H|BPF_IND:
			k = X + pc->k;
			if (X > buflen || pc->k > buflen - X ||
			    sizeof(int16_t) > buflen - k) {
#ifdef KERNEL
				int merr;

				if (buflen != 0)
					return 0;
				A = m_xhalf((struct mbuf *)p, k, &merr);
				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 (pc->k >= buflen || X >= buflen - pc->k) {
#ifdef KERNEL
				register struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)p;
				MINDEX(m, k);
				A = mtod(m, char *)[k];
				continue;
#else
				return 0;
#endif
			}
			A = p[k];
			continue;

		case BPF_LDX|BPF_MSH|BPF_B:
			k = pc->k;
			if (k >= buflen) {
#ifdef KERNEL
				register struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)p;
				MINDEX(m, k);
				X = (mtod(m, char *)[k] & 0xf) << 2;
				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;
		}
	}
}

#ifdef KERNEL
/*
 * 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(const struct bpf_insn *f, int len)
{
	register int i;
	const 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) {
				if (from >= len || p->k >= (bpf_u_int32)(len - from))
					return 0;
			}
			else if (from >= len || p->jt >= len - from ||
				 p->jf >= len - from)
				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)
			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;
}
#endif
Commit	Line	Data
1c79356b	1	/*
5d5c5d0d A	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
5d5c5d0d A	3	*
6601e61a	4	* @APPLE_LICENSE_HEADER_START@
1c79356b	5	*
6601e61a A	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
8f6c56a5	11	*
6601e61a A	12	* This Original Code and all software distributed under the License are
6601e61a A	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
6601e61a A	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
8f6c56a5	19	*
6601e61a	20	* @APPLE_LICENSE_HEADER_END@
1c79356b A	21	*/
	22	/*
	23	* Copyright (c) 1990, 1991, 1993
	24	* The Regents of the University of California. All rights reserved.
	25	*
	26	* This code is derived from the Stanford/CMU enet packet filter,
	27	* (net/enet.c) distributed as part of 4.3BSD, and code contributed
	28	* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
	29	* Berkeley Laboratory.
	30	*
	31	* Redistribution and use in source and binary forms, with or without
	32	* modification, are permitted provided that the following conditions
	33	* are met:
	34	* 1. Redistributions of source code must retain the above copyright
	35	* notice, this list of conditions and the following disclaimer.
	36	* 2. Redistributions in binary form must reproduce the above copyright
	37	* notice, this list of conditions and the following disclaimer in the
	38	* documentation and/or other materials provided with the distribution.
	39	* 3. All advertising materials mentioning features or use of this software
	40	* must display the following acknowledgement:
	41	* This product includes software developed by the University of
	42	* California, Berkeley and its contributors.
	43	* 4. Neither the name of the University nor the names of its contributors
	44	* may be used to endorse or promote products derived from this software
	45	* without specific prior written permission.
	46	*
	47	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	48	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	49	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	50	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	51	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	52	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	53	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	54	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	55	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	56	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	57	* SUCH DAMAGE.
	58	*
	59	* @(#)bpf_filter.c 8.1 (Berkeley) 6/10/93
	60	*
9bccf70c	61	* $FreeBSD: src/sys/net/bpf_filter.c,v 1.17 1999/12/29 04:38:31 peter Exp $
1c79356b A	62	*/
	63
	64	#include <sys/param.h>
	65
	66	#ifdef sun
	67	#include <netinet/in.h>
	68	#endif
	69
	70	#if defined(sparc) \|\| defined(mips) \|\| defined(ibm032) \|\| defined(__alpha__)
	71	#define BPF_ALIGN
	72	#endif
	73
	74	#ifndef BPF_ALIGN
	75	#define EXTRACT_SHORT(p) ((u_int16_t)ntohs((u_int16_t )p))
	76	#define EXTRACT_LONG(p) (ntohl((u_int32_t )p))
	77	#else
	78	#define EXTRACT_SHORT(p)\
	79	((u_int16_t)\
	80	((u_int16_t)((u_char )p+0)<<8\|\
	81	(u_int16_t)((u_char )p+1)<<0))
	82	#define EXTRACT_LONG(p)\
	83	((u_int32_t)((u_char )p+0)<<24\|\
	84	(u_int32_t)((u_char )p+1)<<16\|\
	85	(u_int32_t)((u_char )p+2)<<8\|\
	86	(u_int32_t)((u_char )p+3)<<0)
	87	#endif
	88
	89	#ifdef KERNEL
	90	#include <sys/mbuf.h>
	91	#endif
	92	#include <net/bpf.h>
	93	#ifdef KERNEL
	94	#define MINDEX(m, k) \
	95	{ \
91447636	96	register unsigned int len = m->m_len; \
1c79356b A	97	\
	98	while (k >= len) { \
	99	k -= len; \
	100	m = m->m_next; \
	101	if (m == 0) \
	102	return 0; \
	103	len = m->m_len; \
	104	} \
	105	}
	106
91447636 A	107	static u_int16_t m_xhalf(struct mbuf m, bpf_u_int32 k, int err);
91447636 A	108	static u_int32_t m_xword(struct mbuf m, bpf_u_int32 k, int err);
1c79356b A	109
1c79356b A	110	static u_int32_t
91447636	111	m_xword(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	112	{
	113	register size_t len;
	114	register u_char cp, np;
	115	register struct mbuf *m0;
	116
	117	len = m->m_len;
	118	while (k >= len) {
	119	k -= len;
	120	m = m->m_next;
	121	if (m == 0)
	122	goto bad;
	123	len = m->m_len;
	124	}
	125	cp = mtod(m, u_char *) + k;
	126	if (len - k >= 4) {
	127	*err = 0;
	128	return EXTRACT_LONG(cp);
	129	}
	130	m0 = m->m_next;
	131	if (m0 == 0 \|\| m0->m_len + len - k < 4)
	132	goto bad;
	133	*err = 0;
	134	np = mtod(m0, u_char *);
	135	switch (len - k) {
	136
	137	case 1:
	138	return
	139	((u_int32_t)cp[0] << 24) \|
	140	((u_int32_t)np[0] << 16) \|
	141	((u_int32_t)np[1] << 8) \|
	142	(u_int32_t)np[2];
	143
	144	case 2:
	145	return
	146	((u_int32_t)cp[0] << 24) \|
	147	((u_int32_t)cp[1] << 16) \|
	148	((u_int32_t)np[0] << 8) \|
	149	(u_int32_t)np[1];
	150
	151	default:
	152	return
	153	((u_int32_t)cp[0] << 24) \|
	154	((u_int32_t)cp[1] << 16) \|
	155	((u_int32_t)cp[2] << 8) \|
	156	(u_int32_t)np[0];
	157	}
	158	bad:
	159	*err = 1;
	160	return 0;
	161	}
	162
	163	static u_int16_t
91447636	164	m_xhalf(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	165	{
	166	register size_t len;
	167	register u_char *cp;
	168	register struct mbuf *m0;
	169
	170	len = m->m_len;
	171	while (k >= len) {
	172	k -= len;
	173	m = m->m_next;
	174	if (m == 0)
	175	goto bad;
	176	len = m->m_len;
	177	}
	178	cp = mtod(m, u_char *) + k;
	179	if (len - k >= 2) {
	180	*err = 0;
	181	return EXTRACT_SHORT(cp);
	182	}
	183	m0 = m->m_next;
	184	if (m0 == 0)
	185	goto bad;
	186	*err = 0;
	187	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
	188	bad:
	189	*err = 1;
	190	return 0;
	191	}
	192	#endif
	193
	194	/*
	195	* Execute the filter program starting at pc on the packet p
	196	* wirelen is the length of the original packet
	197	* buflen is the amount of data present
	198	*/
	199	u_int
91447636	200	bpf_filter(const struct bpf_insn pc, u_char p, u_int wirelen, u_int buflen)
1c79356b A	201	{
	202	register u_int32_t A = 0, X = 0;
	203	register bpf_u_int32 k;
	204	int32_t mem[BPF_MEMWORDS];
	205
	206	if (pc == 0)
	207	/*
	208	* No filter means accept all.
	209	*/
	210	return (u_int)-1;
	211
	212	--pc;
	213	while (1) {
	214	++pc;
	215	switch (pc->code) {
	216
	217	default:
	218	#ifdef KERNEL
	219	return 0;
	220	#else
	221	abort();
	222	#endif
	223	case BPF_RET\|BPF_K:
	224	return (u_int)pc->k;
	225
	226	case BPF_RET\|BPF_A:
	227	return (u_int)A;
	228
	229	case BPF_LD\|BPF_W\|BPF_ABS:
	230	k = pc->k;
	231	if (k > buflen \|\| sizeof(int32_t) > buflen - k) {
	232	#ifdef KERNEL
	233	int merr;
	234
	235	if (buflen != 0)
	236	return 0;
	237	A = m_xword((struct mbuf *)p, k, &merr);
	238	if (merr != 0)
	239	return 0;
	240	continue;
	241	#else
	242	return 0;
	243	#endif
	244	}
	245	#if BPF_ALIGN
	246	if (((intptr_t)(p + k) & 3) != 0)
	247	A = EXTRACT_LONG(&p[k]);
	248	else
	249	#endif
	250	A = ntohl((int32_t )(p + k));
	251	continue;
	252
	253	case BPF_LD\|BPF_H\|BPF_ABS:
	254	k = pc->k;
	255	if (k > buflen \|\| sizeof(int16_t) > buflen - k) {
	256	#ifdef KERNEL
	257	int merr;
	258
	259	if (buflen != 0)
	260	return 0;
	261	A = m_xhalf((struct mbuf *)p, k, &merr);
	262	continue;
	263	#else
	264	return 0;
265	#endif
266	}
267	A = EXTRACT_SHORT(&p[k]);
268	continue;
269
270	case BPF_LD\|BPF_B\|BPF_ABS:
271	k = pc->k;
272	if (k >= buflen) {
273	#ifdef KERNEL
274	register struct mbuf *m;
275
276	if (buflen != 0)
277	return 0;
278	m = (struct mbuf *)p;
279	MINDEX(m, k);
280	A = mtod(m, u_char *)[k];
281	continue;
282	#else
283	return 0;
284	#endif
285	}
286	A = p[k];
287	continue;
288
289	case BPF_LD\|BPF_W\|BPF_LEN:
290	A = wirelen;
291	continue;
292
293	case BPF_LDX\|BPF_W\|BPF_LEN:
294	X = wirelen;
295	continue;
296
297	case BPF_LD\|BPF_W\|BPF_IND:
298	k = X + pc->k;
9bccf70c A	299	if (pc->k > buflen \|\| X > buflen - pc->k \|\|
9bccf70c A	300	sizeof(int32_t) > buflen - k) {
1c79356b A	301	#ifdef KERNEL
	302	int merr;
	303
	304	if (buflen != 0)
	305	return 0;
	306	A = m_xword((struct mbuf *)p, k, &merr);
	307	if (merr != 0)
	308	return 0;
	309	continue;
	310	#else
	311	return 0;
	312	#endif
	313	}
	314	#if BPF_ALIGN
	315	if (((intptr_t)(p + k) & 3) != 0)
	316	A = EXTRACT_LONG(&p[k]);
	317	else
	318	#endif
	319	A = ntohl((int32_t )(p + k));
	320	continue;
	321
	322	case BPF_LD\|BPF_H\|BPF_IND:
	323	k = X + pc->k;
9bccf70c A	324	if (X > buflen \|\| pc->k > buflen - X \|\|
9bccf70c A	325	sizeof(int16_t) > buflen - k) {
1c79356b A	326	#ifdef KERNEL
	327	int merr;
	328
	329	if (buflen != 0)
	330	return 0;
	331	A = m_xhalf((struct mbuf *)p, k, &merr);
	332	if (merr != 0)
	333	return 0;
	334	continue;
	335	#else
	336	return 0;
	337	#endif
	338	}
	339	A = EXTRACT_SHORT(&p[k]);
	340	continue;
	341
	342	case BPF_LD\|BPF_B\|BPF_IND:
	343	k = X + pc->k;
	344	if (pc->k >= buflen \|\| X >= buflen - pc->k) {
	345	#ifdef KERNEL
	346	register struct mbuf *m;
	347
	348	if (buflen != 0)
	349	return 0;
	350	m = (struct mbuf *)p;
	351	MINDEX(m, k);
	352	A = mtod(m, char *)[k];
	353	continue;
	354	#else
	355	return 0;
	356	#endif
	357	}
	358	A = p[k];
	359	continue;
	360
	361	case BPF_LDX\|BPF_MSH\|BPF_B:
	362	k = pc->k;
	363	if (k >= buflen) {
	364	#ifdef KERNEL
	365	register struct mbuf *m;
	366
	367	if (buflen != 0)
	368	return 0;
	369	m = (struct mbuf *)p;
	370	MINDEX(m, k);
	371	X = (mtod(m, char *)[k] & 0xf) << 2;
	372	continue;
	373	#else
	374	return 0;
	375	#endif
	376	}
	377	X = (p[pc->k] & 0xf) << 2;
	378	continue;
	379
	380	case BPF_LD\|BPF_IMM:
	381	A = pc->k;
	382	continue;
	383
	384	case BPF_LDX\|BPF_IMM:
	385	X = pc->k;
	386	continue;
	387
	388	case BPF_LD\|BPF_MEM:
	389	A = mem[pc->k];
390	continue;
391
392	case BPF_LDX\|BPF_MEM:
393	X = mem[pc->k];
394	continue;
395
396	case BPF_ST:
397	mem[pc->k] = A;
398	continue;
399
400	case BPF_STX:
401	mem[pc->k] = X;
402	continue;
403
404	case BPF_JMP\|BPF_JA:
405	pc += pc->k;
406	continue;
407
408	case BPF_JMP\|BPF_JGT\|BPF_K:
409	pc += (A > pc->k) ? pc->jt : pc->jf;
410	continue;
411
412	case BPF_JMP\|BPF_JGE\|BPF_K:
413	pc += (A >= pc->k) ? pc->jt : pc->jf;
414	continue;
415
416	case BPF_JMP\|BPF_JEQ\|BPF_K:
417	pc += (A == pc->k) ? pc->jt : pc->jf;
418	continue;
419
420	case BPF_JMP\|BPF_JSET\|BPF_K:
421	pc += (A & pc->k) ? pc->jt : pc->jf;
422	continue;
423
424	case BPF_JMP\|BPF_JGT\|BPF_X:
425	pc += (A > X) ? pc->jt : pc->jf;
426	continue;
427
428	case BPF_JMP\|BPF_JGE\|BPF_X:
429	pc += (A >= X) ? pc->jt : pc->jf;
430	continue;
431
432	case BPF_JMP\|BPF_JEQ\|BPF_X:
433	pc += (A == X) ? pc->jt : pc->jf;
434	continue;
435
436	case BPF_JMP\|BPF_JSET\|BPF_X:
437	pc += (A & X) ? pc->jt : pc->jf;
438	continue;
439
440	case BPF_ALU\|BPF_ADD\|BPF_X:
441	A += X;
442	continue;
443
444	case BPF_ALU\|BPF_SUB\|BPF_X:
445	A -= X;
446	continue;
447
448	case BPF_ALU\|BPF_MUL\|BPF_X:
449	A *= X;
450	continue;
451
452	case BPF_ALU\|BPF_DIV\|BPF_X:
453	if (X == 0)
454	return 0;
455	A /= X;
456	continue;
457
458	case BPF_ALU\|BPF_AND\|BPF_X:
459	A &= X;
460	continue;
461
462	case BPF_ALU\|BPF_OR\|BPF_X:
463	A \|= X;
464	continue;
465
466	case BPF_ALU\|BPF_LSH\|BPF_X:
467	A <<= X;
468	continue;
469
470	case BPF_ALU\|BPF_RSH\|BPF_X:
471	A >>= X;
472	continue;
473
474	case BPF_ALU\|BPF_ADD\|BPF_K:
475	A += pc->k;
476	continue;
477
478	case BPF_ALU\|BPF_SUB\|BPF_K:
479	A -= pc->k;
480	continue;
481
482	case BPF_ALU\|BPF_MUL\|BPF_K:
483	A *= pc->k;
484	continue;
485
486	case BPF_ALU\|BPF_DIV\|BPF_K:
487	A /= pc->k;
488	continue;
489
490	case BPF_ALU\|BPF_AND\|BPF_K:
491	A &= pc->k;
492	continue;
493
494	case BPF_ALU\|BPF_OR\|BPF_K:
495	A \|= pc->k;
496	continue;
497
498	case BPF_ALU\|BPF_LSH\|BPF_K:
499	A <<= pc->k;
500	continue;
501
502	case BPF_ALU\|BPF_RSH\|BPF_K:
503	A >>= pc->k;
504	continue;
505
506	case BPF_ALU\|BPF_NEG:
507	A = -A;
508	continue;
509
510	case BPF_MISC\|BPF_TAX:
511	X = A;
512	continue;
513
514	case BPF_MISC\|BPF_TXA:
515	A = X;
516	continue;
517	}
518	}
519	}
520
521	#ifdef KERNEL
522	/*
523	* Return true if the 'fcode' is a valid filter program.
524	* The constraints are that each jump be forward and to a valid
525	* code. The code must terminate with either an accept or reject.
526	* 'valid' is an array for use by the routine (it must be at least
527	* 'len' bytes long).
528	*
529	* The kernel needs to be able to verify an application's filter code.
530	* Otherwise, a bogus program could easily crash the system.
531	*/
532	int
91447636	533	bpf_validate(const struct bpf_insn *f, int len)
1c79356b A	534	{
1c79356b A	535	register int i;
9bccf70c	536	const struct bpf_insn *p;
1c79356b A	537
	538	for (i = 0; i < len; ++i) {
	539	/*
	540	* Check that that jumps are forward, and within
	541	* the code block.
	542	*/
	543	p = &f[i];
	544	if (BPF_CLASS(p->code) == BPF_JMP) {
	545	register int from = i + 1;
	546
	547	if (BPF_OP(p->code) == BPF_JA) {
91447636	548	if (from >= len \|\| p->k >= (bpf_u_int32)(len - from))
1c79356b A	549	return 0;
1c79356b A	550	}
9bccf70c A	551	else if (from >= len \|\| p->jt >= len - from \|\|
9bccf70c A	552	p->jf >= len - from)
1c79356b A	553	return 0;
	554	}
	555	/*
	556	* Check that memory operations use valid addresses.
	557	*/
	558	if ((BPF_CLASS(p->code) == BPF_ST \|\|
	559	(BPF_CLASS(p->code) == BPF_LD &&
	560	(p->code & 0xe0) == BPF_MEM)) &&
	561	p->k >= BPF_MEMWORDS)
	562	return 0;
	563	/*
	564	* Check for constant division by 0.
	565	*/
	566	if (p->code == (BPF_ALU\|BPF_DIV\|BPF_K) && p->k == 0)
	567	return 0;
	568	}
	569	return BPF_CLASS(f[len - 1].code) == BPF_RET;
	570	}
	571	#endif