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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * 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. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * 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_OSREFERENCE_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, u_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, u_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	*
2d21ac55	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
1c79356b	5	*
2d21ac55 A	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
8f6c56a5	14	*
2d21ac55 A	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
8f6c56a5 A	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
8f6c56a5 A	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
2d21ac55 A	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
8f6c56a5	25	*
2d21ac55	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
1c79356b A	27	*/
	28	/*
	29	* Copyright (c) 1990, 1991, 1993
	30	* The Regents of the University of California. All rights reserved.
	31	*
	32	* This code is derived from the Stanford/CMU enet packet filter,
	33	* (net/enet.c) distributed as part of 4.3BSD, and code contributed
	34	* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
	35	* Berkeley Laboratory.
	36	*
	37	* Redistribution and use in source and binary forms, with or without
	38	* modification, are permitted provided that the following conditions
	39	* are met:
	40	* 1. Redistributions of source code must retain the above copyright
	41	* notice, this list of conditions and the following disclaimer.
	42	* 2. Redistributions in binary form must reproduce the above copyright
	43	* notice, this list of conditions and the following disclaimer in the
	44	* documentation and/or other materials provided with the distribution.
	45	* 3. All advertising materials mentioning features or use of this software
	46	* must display the following acknowledgement:
	47	* This product includes software developed by the University of
	48	* California, Berkeley and its contributors.
	49	* 4. Neither the name of the University nor the names of its contributors
	50	* may be used to endorse or promote products derived from this software
	51	* without specific prior written permission.
	52	*
	53	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	54	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	55	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	56	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	57	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	58	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	59	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	60	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	61	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	62	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	63	* SUCH DAMAGE.
	64	*
	65	* @(#)bpf_filter.c 8.1 (Berkeley) 6/10/93
	66	*
9bccf70c	67	* $FreeBSD: src/sys/net/bpf_filter.c,v 1.17 1999/12/29 04:38:31 peter Exp $
1c79356b A	68	*/
	69
	70	#include <sys/param.h>
	71
	72	#ifdef sun
	73	#include <netinet/in.h>
	74	#endif
	75
	76	#if defined(sparc) \|\| defined(mips) \|\| defined(ibm032) \|\| defined(__alpha__)
	77	#define BPF_ALIGN
	78	#endif
	79
	80	#ifndef BPF_ALIGN
	81	#define EXTRACT_SHORT(p) ((u_int16_t)ntohs((u_int16_t )p))
	82	#define EXTRACT_LONG(p) (ntohl((u_int32_t )p))
	83	#else
	84	#define EXTRACT_SHORT(p)\
	85	((u_int16_t)\
	86	((u_int16_t)((u_char )p+0)<<8\|\
	87	(u_int16_t)((u_char )p+1)<<0))
	88	#define EXTRACT_LONG(p)\
	89	((u_int32_t)((u_char )p+0)<<24\|\
	90	(u_int32_t)((u_char )p+1)<<16\|\
	91	(u_int32_t)((u_char )p+2)<<8\|\
	92	(u_int32_t)((u_char )p+3)<<0)
	93	#endif
	94
	95	#ifdef KERNEL
	96	#include <sys/mbuf.h>
	97	#endif
	98	#include <net/bpf.h>
	99	#ifdef KERNEL
	100	#define MINDEX(m, k) \
	101	{ \
91447636	102	register unsigned int len = m->m_len; \
1c79356b A	103	\
	104	while (k >= len) { \
	105	k -= len; \
	106	m = m->m_next; \
	107	if (m == 0) \
	108	return 0; \
	109	len = m->m_len; \
	110	} \
	111	}
	112
91447636 A	113	static u_int16_t m_xhalf(struct mbuf m, bpf_u_int32 k, int err);
91447636 A	114	static u_int32_t m_xword(struct mbuf m, bpf_u_int32 k, int err);
1c79356b A	115
1c79356b A	116	static u_int32_t
91447636	117	m_xword(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	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
91447636	170	m_xhalf(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	171	{
	172	register size_t len;
	173	register u_char *cp;
	174	register struct mbuf *m0;
	175
	176	len = m->m_len;
	177	while (k >= len) {
	178	k -= len;
	179	m = m->m_next;
	180	if (m == 0)
	181	goto bad;
	182	len = m->m_len;
	183	}
	184	cp = mtod(m, u_char *) + k;
	185	if (len - k >= 2) {
	186	*err = 0;
	187	return EXTRACT_SHORT(cp);
	188	}
	189	m0 = m->m_next;
	190	if (m0 == 0)
	191	goto bad;
	192	*err = 0;
	193	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
	194	bad:
	195	*err = 1;
	196	return 0;
	197	}
	198	#endif
	199
	200	/*
	201	* Execute the filter program starting at pc on the packet p
	202	* wirelen is the length of the original packet
	203	* buflen is the amount of data present
	204	*/
	205	u_int
91447636	206	bpf_filter(const struct bpf_insn pc, u_char p, u_int wirelen, u_int buflen)
1c79356b A	207	{
	208	register u_int32_t A = 0, X = 0;
	209	register bpf_u_int32 k;
	210	int32_t mem[BPF_MEMWORDS];
	211
	212	if (pc == 0)
	213	/*
	214	* No filter means accept all.
	215	*/
	216	return (u_int)-1;
	217
	218	--pc;
	219	while (1) {
	220	++pc;
	221	switch (pc->code) {
	222
	223	default:
	224	#ifdef KERNEL
	225	return 0;
	226	#else
	227	abort();
	228	#endif
	229	case BPF_RET\|BPF_K:
	230	return (u_int)pc->k;
	231
	232	case BPF_RET\|BPF_A:
	233	return (u_int)A;
	234
	235	case BPF_LD\|BPF_W\|BPF_ABS:
	236	k = pc->k;
	237	if (k > buflen \|\| sizeof(int32_t) > buflen - k) {
	238	#ifdef KERNEL
	239	int merr;
	240
	241	if (buflen != 0)
	242	return 0;
	243	A = m_xword((struct mbuf *)p, k, &merr);
	244	if (merr != 0)
	245	return 0;
	246	continue;
	247	#else
	248	return 0;
	249	#endif
	250	}
	251	#if BPF_ALIGN
	252	if (((intptr_t)(p + k) & 3) != 0)
	253	A = EXTRACT_LONG(&p[k]);
	254	else
	255	#endif
	256	A = ntohl((int32_t )(p + k));
	257	continue;
	258
	259	case BPF_LD\|BPF_H\|BPF_ABS:
	260	k = pc->k;
	261	if (k > buflen \|\| sizeof(int16_t) > buflen - k) {
	262	#ifdef KERNEL
	263	int merr;
	264
	265	if (buflen != 0)
	266	return 0;
	267	A = m_xhalf((struct mbuf *)p, k, &merr);
	268	continue;
	269	#else
	270	return 0;
271	#endif
272	}
273	A = EXTRACT_SHORT(&p[k]);
274	continue;
275
276	case BPF_LD\|BPF_B\|BPF_ABS:
277	k = pc->k;
278	if (k >= buflen) {
279	#ifdef KERNEL
280	register struct mbuf *m;
281
282	if (buflen != 0)
283	return 0;
284	m = (struct mbuf *)p;
285	MINDEX(m, k);
286	A = mtod(m, u_char *)[k];
287	continue;
288	#else
289	return 0;
290	#endif
291	}
292	A = p[k];
293	continue;
294
295	case BPF_LD\|BPF_W\|BPF_LEN:
296	A = wirelen;
297	continue;
298
299	case BPF_LDX\|BPF_W\|BPF_LEN:
300	X = wirelen;
301	continue;
302
303	case BPF_LD\|BPF_W\|BPF_IND:
304	k = X + pc->k;
9bccf70c A	305	if (pc->k > buflen \|\| X > buflen - pc->k \|\|
9bccf70c A	306	sizeof(int32_t) > buflen - k) {
1c79356b A	307	#ifdef KERNEL
	308	int merr;
	309
	310	if (buflen != 0)
	311	return 0;
	312	A = m_xword((struct mbuf *)p, k, &merr);
	313	if (merr != 0)
	314	return 0;
	315	continue;
	316	#else
	317	return 0;
	318	#endif
	319	}
	320	#if BPF_ALIGN
	321	if (((intptr_t)(p + k) & 3) != 0)
	322	A = EXTRACT_LONG(&p[k]);
	323	else
	324	#endif
	325	A = ntohl((int32_t )(p + k));
	326	continue;
	327
	328	case BPF_LD\|BPF_H\|BPF_IND:
	329	k = X + pc->k;
9bccf70c A	330	if (X > buflen \|\| pc->k > buflen - X \|\|
9bccf70c A	331	sizeof(int16_t) > buflen - k) {
1c79356b A	332	#ifdef KERNEL
	333	int merr;
	334
	335	if (buflen != 0)
	336	return 0;
	337	A = m_xhalf((struct mbuf *)p, k, &merr);
	338	if (merr != 0)
	339	return 0;
	340	continue;
	341	#else
	342	return 0;
	343	#endif
	344	}
	345	A = EXTRACT_SHORT(&p[k]);
	346	continue;
	347
	348	case BPF_LD\|BPF_B\|BPF_IND:
	349	k = X + pc->k;
	350	if (pc->k >= buflen \|\| X >= buflen - pc->k) {
	351	#ifdef KERNEL
	352	register struct mbuf *m;
	353
	354	if (buflen != 0)
	355	return 0;
	356	m = (struct mbuf *)p;
	357	MINDEX(m, k);
2d21ac55	358	A = mtod(m, u_char *)[k];
1c79356b A	359	continue;
	360	#else
	361	return 0;
	362	#endif
	363	}
	364	A = p[k];
	365	continue;
	366
	367	case BPF_LDX\|BPF_MSH\|BPF_B:
	368	k = pc->k;
	369	if (k >= buflen) {
	370	#ifdef KERNEL
	371	register struct mbuf *m;
	372
	373	if (buflen != 0)
	374	return 0;
	375	m = (struct mbuf *)p;
	376	MINDEX(m, k);
2d21ac55	377	X = (mtod(m, u_char *)[k] & 0xf) << 2;
1c79356b A	378	continue;
	379	#else
	380	return 0;
	381	#endif
	382	}
	383	X = (p[pc->k] & 0xf) << 2;
	384	continue;
	385
	386	case BPF_LD\|BPF_IMM:
	387	A = pc->k;
	388	continue;
	389
	390	case BPF_LDX\|BPF_IMM:
	391	X = pc->k;
	392	continue;
	393
	394	case BPF_LD\|BPF_MEM:
	395	A = mem[pc->k];
	396	continue;
	397
	398	case BPF_LDX\|BPF_MEM:
	399	X = mem[pc->k];
	400	continue;
	401
	402	case BPF_ST:
	403	mem[pc->k] = A;
	404	continue;
	405
	406	case BPF_STX:
	407	mem[pc->k] = X;
	408	continue;
	409
	410	case BPF_JMP\|BPF_JA:
	411	pc += pc->k;
	412	continue;
	413
	414	case BPF_JMP\|BPF_JGT\|BPF_K:
	415	pc += (A > pc->k) ? pc->jt : pc->jf;
	416	continue;
	417
	418	case BPF_JMP\|BPF_JGE\|BPF_K:
	419	pc += (A >= pc->k) ? pc->jt : pc->jf;
	420	continue;
	421
	422	case BPF_JMP\|BPF_JEQ\|BPF_K:
	423	pc += (A == pc->k) ? pc->jt : pc->jf;
	424	continue;
	425
	426	case BPF_JMP\|BPF_JSET\|BPF_K:
	427	pc += (A & pc->k) ? pc->jt : pc->jf;
	428	continue;
	429
	430	case BPF_JMP\|BPF_JGT\|BPF_X:
	431	pc += (A > X) ? pc->jt : pc->jf;
	432	continue;
	433
	434	case BPF_JMP\|BPF_JGE\|BPF_X:
	435	pc += (A >= X) ? pc->jt : pc->jf;
	436	continue;
	437
	438	case BPF_JMP\|BPF_JEQ\|BPF_X:
	439	pc += (A == X) ? pc->jt : pc->jf;
	440	continue;
	441
442	case BPF_JMP\|BPF_JSET\|BPF_X:
443	pc += (A & X) ? pc->jt : pc->jf;
444	continue;
445
446	case BPF_ALU\|BPF_ADD\|BPF_X:
447	A += X;
448	continue;
449
450	case BPF_ALU\|BPF_SUB\|BPF_X:
451	A -= X;
452	continue;
453
454	case BPF_ALU\|BPF_MUL\|BPF_X:
455	A *= X;
456	continue;
457
458	case BPF_ALU\|BPF_DIV\|BPF_X:
459	if (X == 0)
460	return 0;
461	A /= X;
462	continue;
463
464	case BPF_ALU\|BPF_AND\|BPF_X:
465	A &= X;
466	continue;
467
468	case BPF_ALU\|BPF_OR\|BPF_X:
469	A \|= X;
470	continue;
471
472	case BPF_ALU\|BPF_LSH\|BPF_X:
473	A <<= X;
474	continue;
475
476	case BPF_ALU\|BPF_RSH\|BPF_X:
477	A >>= X;
478	continue;
479
480	case BPF_ALU\|BPF_ADD\|BPF_K:
481	A += pc->k;
482	continue;
483
484	case BPF_ALU\|BPF_SUB\|BPF_K:
485	A -= pc->k;
486	continue;
487
488	case BPF_ALU\|BPF_MUL\|BPF_K:
489	A *= pc->k;
490	continue;
491
492	case BPF_ALU\|BPF_DIV\|BPF_K:
493	A /= pc->k;
494	continue;
495
496	case BPF_ALU\|BPF_AND\|BPF_K:
497	A &= pc->k;
498	continue;
499
500	case BPF_ALU\|BPF_OR\|BPF_K:
501	A \|= pc->k;
502	continue;
503
504	case BPF_ALU\|BPF_LSH\|BPF_K:
505	A <<= pc->k;
506	continue;
507
508	case BPF_ALU\|BPF_RSH\|BPF_K:
509	A >>= pc->k;
510	continue;
511
512	case BPF_ALU\|BPF_NEG:
513	A = -A;
514	continue;
515
516	case BPF_MISC\|BPF_TAX:
517	X = A;
518	continue;
519
520	case BPF_MISC\|BPF_TXA:
521	A = X;
522	continue;
523	}
524	}
525	}
526
527	#ifdef KERNEL
528	/*
529	* Return true if the 'fcode' is a valid filter program.
530	* The constraints are that each jump be forward and to a valid
531	* code. The code must terminate with either an accept or reject.
532	* 'valid' is an array for use by the routine (it must be at least
533	* 'len' bytes long).
534	*
535	* The kernel needs to be able to verify an application's filter code.
536	* Otherwise, a bogus program could easily crash the system.
537	*/
538	int
91447636	539	bpf_validate(const struct bpf_insn *f, int len)
1c79356b A	540	{
1c79356b A	541	register int i;
9bccf70c	542	const struct bpf_insn *p;
1c79356b A	543
	544	for (i = 0; i < len; ++i) {
	545	/*
	546	* Check that that jumps are forward, and within
	547	* the code block.
	548	*/
	549	p = &f[i];
	550	if (BPF_CLASS(p->code) == BPF_JMP) {
	551	register int from = i + 1;
	552
	553	if (BPF_OP(p->code) == BPF_JA) {
91447636	554	if (from >= len \|\| p->k >= (bpf_u_int32)(len - from))
1c79356b A	555	return 0;
1c79356b A	556	}
9bccf70c A	557	else if (from >= len \|\| p->jt >= len - from \|\|
9bccf70c A	558	p->jf >= len - from)
1c79356b A	559	return 0;
	560	}
	561	/*
	562	* Check that memory operations use valid addresses.
	563	*/
	564	if ((BPF_CLASS(p->code) == BPF_ST \|\|
	565	(BPF_CLASS(p->code) == BPF_LD &&
	566	(p->code & 0xe0) == BPF_MEM)) &&
	567	p->k >= BPF_MEMWORDS)
	568	return 0;
	569	/*
	570	* Check for constant division by 0.
	571	*/
	572	if (p->code == (BPF_ALU\|BPF_DIV\|BPF_K) && p->k == 0)
	573	return 0;
	574	}
	575	return BPF_CLASS(f[len - 1].code) == BPF_RET;
	576	}
	577	#endif