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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The 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, QUIET ENJOYMENT 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 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 __P((struct mbuf *m, bpf_u_int32 k, int *err));
static u_int32_t	m_xword __P((struct mbuf *m, bpf_u_int32 k, int *err));

static u_int32_t
m_xword(m, k, err)
	register struct mbuf *m;
	register bpf_u_int32 k;
	register 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(m, k, err)
	register struct mbuf *m;
	register bpf_u_int32 k;
	register 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(pc, p, wirelen, buflen)
	register const struct bpf_insn *pc;
	register u_char *p;
	u_int wirelen;
	register 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(f, len)
	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 >= 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 A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
43866e37	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
1c79356b	7	*
43866e37 A	8	* This file contains Original Code and/or Modifications of Original Code
	9	* as defined in and that are subject to the Apple Public Source License
	10	* Version 2.0 (the 'License'). You may not use this file except in
	11	* compliance with the License. Please obtain a copy of the License at
	12	* http://www.opensource.apple.com/apsl/ and read it before using this
	13	* file.
	14	*
	15	* The Original Code and all software distributed under the License are
	16	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
1c79356b A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
1c79356b A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
43866e37 A	19	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	20	* Please see the License for the specific language governing rights and
	21	* limitations under the License.
1c79356b A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
	25	/*
	26	* Copyright (c) 1990, 1991, 1993
	27	* The Regents of the University of California. All rights reserved.
	28	*
	29	* This code is derived from the Stanford/CMU enet packet filter,
	30	* (net/enet.c) distributed as part of 4.3BSD, and code contributed
	31	* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
	32	* Berkeley Laboratory.
	33	*
	34	* Redistribution and use in source and binary forms, with or without
	35	* modification, are permitted provided that the following conditions
	36	* are met:
	37	* 1. Redistributions of source code must retain the above copyright
	38	* notice, this list of conditions and the following disclaimer.
	39	* 2. Redistributions in binary form must reproduce the above copyright
	40	* notice, this list of conditions and the following disclaimer in the
	41	* documentation and/or other materials provided with the distribution.
	42	* 3. All advertising materials mentioning features or use of this software
	43	* must display the following acknowledgement:
	44	* This product includes software developed by the University of
	45	* California, Berkeley and its contributors.
	46	* 4. Neither the name of the University nor the names of its contributors
	47	* may be used to endorse or promote products derived from this software
	48	* without specific prior written permission.
	49	*
	50	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	51	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	52	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	53	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	54	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	55	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	56	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	57	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	58	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	59	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	60	* SUCH DAMAGE.
	61	*
	62	* @(#)bpf_filter.c 8.1 (Berkeley) 6/10/93
	63	*
9bccf70c	64	* $FreeBSD: src/sys/net/bpf_filter.c,v 1.17 1999/12/29 04:38:31 peter Exp $
1c79356b A	65	*/
	66
	67	#include <sys/param.h>
	68
	69	#ifdef sun
	70	#include <netinet/in.h>
	71	#endif
	72
	73	#if defined(sparc) \|\| defined(mips) \|\| defined(ibm032) \|\| defined(__alpha__)
	74	#define BPF_ALIGN
	75	#endif
	76
	77	#ifndef BPF_ALIGN
	78	#define EXTRACT_SHORT(p) ((u_int16_t)ntohs((u_int16_t )p))
	79	#define EXTRACT_LONG(p) (ntohl((u_int32_t )p))
	80	#else
	81	#define EXTRACT_SHORT(p)\
	82	((u_int16_t)\
	83	((u_int16_t)((u_char )p+0)<<8\|\
	84	(u_int16_t)((u_char )p+1)<<0))
	85	#define EXTRACT_LONG(p)\
	86	((u_int32_t)((u_char )p+0)<<24\|\
	87	(u_int32_t)((u_char )p+1)<<16\|\
	88	(u_int32_t)((u_char )p+2)<<8\|\
	89	(u_int32_t)((u_char )p+3)<<0)
	90	#endif
	91
	92	#ifdef KERNEL
	93	#include <sys/mbuf.h>
	94	#endif
	95	#include <net/bpf.h>
	96	#ifdef KERNEL
	97	#define MINDEX(m, k) \
	98	{ \
	99	register int len = m->m_len; \
	100	\
	101	while (k >= len) { \
	102	k -= len; \
	103	m = m->m_next; \
	104	if (m == 0) \
	105	return 0; \
	106	len = m->m_len; \
	107	} \
	108	}
	109
	110	static u_int16_t m_xhalf __P((struct mbuf m, bpf_u_int32 k, int err));
	111	static u_int32_t m_xword __P((struct mbuf m, bpf_u_int32 k, int err));
	112
	113	static u_int32_t
	114	m_xword(m, k, err)
	115	register struct mbuf *m;
	116	register bpf_u_int32 k;
	117	register int *err;
	118	{
	119	register size_t len;
	120	register u_char cp, np;
	121	register struct mbuf *m0;
	122
	123	len = m->m_len;
	124	while (k >= len) {
	125	k -= len;
	126	m = m->m_next;
	127	if (m == 0)
	128	goto bad;
129	len = m->m_len;
130	}
131	cp = mtod(m, u_char *) + k;
132	if (len - k >= 4) {
133	*err = 0;
134	return EXTRACT_LONG(cp);
135	}
136	m0 = m->m_next;
137	if (m0 == 0 \|\| m0->m_len + len - k < 4)
138	goto bad;
139	*err = 0;
140	np = mtod(m0, u_char *);
141	switch (len - k) {
142
143	case 1:
144	return
145	((u_int32_t)cp[0] << 24) \|
146	((u_int32_t)np[0] << 16) \|
147	((u_int32_t)np[1] << 8) \|
148	(u_int32_t)np[2];
149
150	case 2:
151	return
152	((u_int32_t)cp[0] << 24) \|
153	((u_int32_t)cp[1] << 16) \|
154	((u_int32_t)np[0] << 8) \|
155	(u_int32_t)np[1];
156
157	default:
158	return
159	((u_int32_t)cp[0] << 24) \|
160	((u_int32_t)cp[1] << 16) \|
161	((u_int32_t)cp[2] << 8) \|
162	(u_int32_t)np[0];
163	}
164	bad:
165	*err = 1;
166	return 0;
167	}
168
169	static u_int16_t
170	m_xhalf(m, k, err)
171	register struct mbuf *m;
172	register bpf_u_int32 k;
173	register int *err;
174	{
175	register size_t len;
176	register u_char *cp;
177	register struct mbuf *m0;
178
179	len = m->m_len;
180	while (k >= len) {
181	k -= len;
182	m = m->m_next;
183	if (m == 0)
184	goto bad;
185	len = m->m_len;
186	}
187	cp = mtod(m, u_char *) + k;
188	if (len - k >= 2) {
189	*err = 0;
190	return EXTRACT_SHORT(cp);
191	}
192	m0 = m->m_next;
193	if (m0 == 0)
194	goto bad;
195	*err = 0;
196	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
197	bad:
198	*err = 1;
199	return 0;
200	}
201	#endif
202
203	/*
204	* Execute the filter program starting at pc on the packet p
205	* wirelen is the length of the original packet
206	* buflen is the amount of data present
207	*/
208	u_int
209	bpf_filter(pc, p, wirelen, buflen)
9bccf70c	210	register const struct bpf_insn *pc;
1c79356b A	211	register u_char *p;
	212	u_int wirelen;
	213	register u_int buflen;
	214	{
	215	register u_int32_t A = 0, X = 0;
	216	register bpf_u_int32 k;
	217	int32_t mem[BPF_MEMWORDS];
	218
	219	if (pc == 0)
	220	/*
	221	* No filter means accept all.
	222	*/
	223	return (u_int)-1;
	224
	225	--pc;
	226	while (1) {
	227	++pc;
	228	switch (pc->code) {
	229
	230	default:
	231	#ifdef KERNEL
	232	return 0;
	233	#else
	234	abort();
	235	#endif
	236	case BPF_RET\|BPF_K:
	237	return (u_int)pc->k;
	238
	239	case BPF_RET\|BPF_A:
	240	return (u_int)A;
	241
	242	case BPF_LD\|BPF_W\|BPF_ABS:
	243	k = pc->k;
	244	if (k > buflen \|\| sizeof(int32_t) > buflen - k) {
	245	#ifdef KERNEL
	246	int merr;
	247
	248	if (buflen != 0)
	249	return 0;
	250	A = m_xword((struct mbuf *)p, k, &merr);
	251	if (merr != 0)
	252	return 0;
	253	continue;
	254	#else
	255	return 0;
	256	#endif
	257	}
	258	#if BPF_ALIGN
	259	if (((intptr_t)(p + k) & 3) != 0)
	260	A = EXTRACT_LONG(&p[k]);
	261	else
	262	#endif
	263	A = ntohl((int32_t )(p + k));
	264	continue;
	265
	266	case BPF_LD\|BPF_H\|BPF_ABS:
	267	k = pc->k;
	268	if (k > buflen \|\| sizeof(int16_t) > buflen - k) {
	269	#ifdef KERNEL
	270	int merr;
	271
	272	if (buflen != 0)
	273	return 0;
	274	A = m_xhalf((struct mbuf *)p, k, &merr);
275	continue;
276	#else
277	return 0;
278	#endif
279	}
280	A = EXTRACT_SHORT(&p[k]);
281	continue;
282
283	case BPF_LD\|BPF_B\|BPF_ABS:
284	k = pc->k;
285	if (k >= buflen) {
286	#ifdef KERNEL
287	register struct mbuf *m;
288
289	if (buflen != 0)
290	return 0;
291	m = (struct mbuf *)p;
292	MINDEX(m, k);
293	A = mtod(m, u_char *)[k];
294	continue;
295	#else
296	return 0;
297	#endif
298	}
299	A = p[k];
300	continue;
301
302	case BPF_LD\|BPF_W\|BPF_LEN:
303	A = wirelen;
304	continue;
305
306	case BPF_LDX\|BPF_W\|BPF_LEN:
307	X = wirelen;
308	continue;
309
310	case BPF_LD\|BPF_W\|BPF_IND:
311	k = X + pc->k;
9bccf70c A	312	if (pc->k > buflen \|\| X > buflen - pc->k \|\|
9bccf70c A	313	sizeof(int32_t) > buflen - k) {
1c79356b A	314	#ifdef KERNEL
	315	int merr;
	316
	317	if (buflen != 0)
	318	return 0;
	319	A = m_xword((struct mbuf *)p, k, &merr);
	320	if (merr != 0)
	321	return 0;
	322	continue;
	323	#else
	324	return 0;
	325	#endif
	326	}
	327	#if BPF_ALIGN
	328	if (((intptr_t)(p + k) & 3) != 0)
	329	A = EXTRACT_LONG(&p[k]);
	330	else
	331	#endif
	332	A = ntohl((int32_t )(p + k));
	333	continue;
	334
	335	case BPF_LD\|BPF_H\|BPF_IND:
	336	k = X + pc->k;
9bccf70c A	337	if (X > buflen \|\| pc->k > buflen - X \|\|
9bccf70c A	338	sizeof(int16_t) > buflen - k) {
1c79356b A	339	#ifdef KERNEL
	340	int merr;
	341
	342	if (buflen != 0)
	343	return 0;
	344	A = m_xhalf((struct mbuf *)p, k, &merr);
	345	if (merr != 0)
	346	return 0;
	347	continue;
	348	#else
	349	return 0;
	350	#endif
	351	}
	352	A = EXTRACT_SHORT(&p[k]);
	353	continue;
	354
	355	case BPF_LD\|BPF_B\|BPF_IND:
	356	k = X + pc->k;
	357	if (pc->k >= buflen \|\| X >= buflen - pc->k) {
	358	#ifdef KERNEL
	359	register struct mbuf *m;
	360
	361	if (buflen != 0)
	362	return 0;
	363	m = (struct mbuf *)p;
	364	MINDEX(m, k);
	365	A = mtod(m, char *)[k];
	366	continue;
	367	#else
	368	return 0;
	369	#endif
	370	}
	371	A = p[k];
	372	continue;
	373
	374	case BPF_LDX\|BPF_MSH\|BPF_B:
	375	k = pc->k;
	376	if (k >= buflen) {
	377	#ifdef KERNEL
	378	register struct mbuf *m;
	379
	380	if (buflen != 0)
	381	return 0;
	382	m = (struct mbuf *)p;
	383	MINDEX(m, k);
	384	X = (mtod(m, char *)[k] & 0xf) << 2;
	385	continue;
	386	#else
	387	return 0;
	388	#endif
	389	}
	390	X = (p[pc->k] & 0xf) << 2;
	391	continue;
	392
	393	case BPF_LD\|BPF_IMM:
	394	A = pc->k;
	395	continue;
	396
	397	case BPF_LDX\|BPF_IMM:
	398	X = pc->k;
	399	continue;
	400
	401	case BPF_LD\|BPF_MEM:
	402	A = mem[pc->k];
403	continue;
404
405	case BPF_LDX\|BPF_MEM:
406	X = mem[pc->k];
407	continue;
408
409	case BPF_ST:
410	mem[pc->k] = A;
411	continue;
412
413	case BPF_STX:
414	mem[pc->k] = X;
415	continue;
416
417	case BPF_JMP\|BPF_JA:
418	pc += pc->k;
419	continue;
420
421	case BPF_JMP\|BPF_JGT\|BPF_K:
422	pc += (A > pc->k) ? pc->jt : pc->jf;
423	continue;
424
425	case BPF_JMP\|BPF_JGE\|BPF_K:
426	pc += (A >= pc->k) ? pc->jt : pc->jf;
427	continue;
428
429	case BPF_JMP\|BPF_JEQ\|BPF_K:
430	pc += (A == pc->k) ? pc->jt : pc->jf;
431	continue;
432
433	case BPF_JMP\|BPF_JSET\|BPF_K:
434	pc += (A & pc->k) ? pc->jt : pc->jf;
435	continue;
436
437	case BPF_JMP\|BPF_JGT\|BPF_X:
438	pc += (A > X) ? pc->jt : pc->jf;
439	continue;
440
441	case BPF_JMP\|BPF_JGE\|BPF_X:
442	pc += (A >= X) ? pc->jt : pc->jf;
443	continue;
444
445	case BPF_JMP\|BPF_JEQ\|BPF_X:
446	pc += (A == X) ? pc->jt : pc->jf;
447	continue;
448
449	case BPF_JMP\|BPF_JSET\|BPF_X:
450	pc += (A & X) ? pc->jt : pc->jf;
451	continue;
452
453	case BPF_ALU\|BPF_ADD\|BPF_X:
454	A += X;
455	continue;
456
457	case BPF_ALU\|BPF_SUB\|BPF_X:
458	A -= X;
459	continue;
460
461	case BPF_ALU\|BPF_MUL\|BPF_X:
462	A *= X;
463	continue;
464
465	case BPF_ALU\|BPF_DIV\|BPF_X:
466	if (X == 0)
467	return 0;
468	A /= X;
469	continue;
470
471	case BPF_ALU\|BPF_AND\|BPF_X:
472	A &= X;
473	continue;
474
475	case BPF_ALU\|BPF_OR\|BPF_X:
476	A \|= X;
477	continue;
478
479	case BPF_ALU\|BPF_LSH\|BPF_X:
480	A <<= X;
481	continue;
482
483	case BPF_ALU\|BPF_RSH\|BPF_X:
484	A >>= X;
485	continue;
486
487	case BPF_ALU\|BPF_ADD\|BPF_K:
488	A += pc->k;
489	continue;
490
491	case BPF_ALU\|BPF_SUB\|BPF_K:
492	A -= pc->k;
493	continue;
494
495	case BPF_ALU\|BPF_MUL\|BPF_K:
496	A *= pc->k;
497	continue;
498
499	case BPF_ALU\|BPF_DIV\|BPF_K:
500	A /= pc->k;
501	continue;
502
503	case BPF_ALU\|BPF_AND\|BPF_K:
504	A &= pc->k;
505	continue;
506
507	case BPF_ALU\|BPF_OR\|BPF_K:
508	A \|= pc->k;
509	continue;
510
511	case BPF_ALU\|BPF_LSH\|BPF_K:
512	A <<= pc->k;
513	continue;
514
515	case BPF_ALU\|BPF_RSH\|BPF_K:
516	A >>= pc->k;
517	continue;
518
519	case BPF_ALU\|BPF_NEG:
520	A = -A;
521	continue;
522
523	case BPF_MISC\|BPF_TAX:
524	X = A;
525	continue;
526
527	case BPF_MISC\|BPF_TXA:
528	A = X;
529	continue;
530	}
531	}
532	}
533
534	#ifdef KERNEL
535	/*
536	* Return true if the 'fcode' is a valid filter program.
537	* The constraints are that each jump be forward and to a valid
538	* code. The code must terminate with either an accept or reject.
539	* 'valid' is an array for use by the routine (it must be at least
540	* 'len' bytes long).
541	*
542	* The kernel needs to be able to verify an application's filter code.
543	* Otherwise, a bogus program could easily crash the system.
544	*/
545	int
546	bpf_validate(f, len)
9bccf70c	547	const struct bpf_insn *f;
1c79356b A	548	int len;
	549	{
	550	register int i;
9bccf70c	551	const struct bpf_insn *p;
1c79356b A	552
	553	for (i = 0; i < len; ++i) {
	554	/*
	555	* Check that that jumps are forward, and within
	556	* the code block.
	557	*/
	558	p = &f[i];
	559	if (BPF_CLASS(p->code) == BPF_JMP) {
	560	register int from = i + 1;
	561
	562	if (BPF_OP(p->code) == BPF_JA) {
	563	if (from >= len \|\| p->k >= len - from)
	564	return 0;
	565	}
9bccf70c A	566	else if (from >= len \|\| p->jt >= len - from \|\|
9bccf70c A	567	p->jf >= len - from)
1c79356b A	568	return 0;
	569	}
	570	/*
	571	* Check that memory operations use valid addresses.
	572	*/
	573	if ((BPF_CLASS(p->code) == BPF_ST \|\|
	574	(BPF_CLASS(p->code) == BPF_LD &&
	575	(p->code & 0xe0) == BPF_MEM)) &&
	576	p->k >= BPF_MEMWORDS)
	577	return 0;
	578	/*
	579	* Check for constant division by 0.
	580	*/
	581	if (p->code == (BPF_ALU\|BPF_DIV\|BPF_K) && p->k == 0)
	582	return 0;
	583	}
	584	return BPF_CLASS(f[len - 1].code) == BPF_RET;
	585	}
	586	#endif