[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; \
	} \
}

extern unsigned int bpf_maxbufsize;

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, that memory accesses are within valid ranges (to the 
 * extent that this can be checked statically; loads of packet data
 * have to be, and are, also checked at run time), and that
 * the code terminates with either an accept or reject.
 *
 * The kernel needs to be able to verify an application's filter code.
 * Otherwise, a bogus program could easily crash the system.
 */
int
bpf_validate(const struct bpf_insn *f, int len)
{
	u_int i, from;
	const struct bpf_insn *p;

	if (len < 1 || len > BPF_MAXINSNS)
		return 0;
	
	for (i = 0; i < ((u_int)len); ++i) {
		p = &f[i];
		switch (BPF_CLASS(p->code)) {
			/*
			 * Check that memory operations use valid addresses
			 */
			case BPF_LD:
			case BPF_LDX:
				switch (BPF_MODE(p->code)) {
					case BPF_IMM:
						break;
					case BPF_ABS:
					case BPF_IND:
					case BPF_MSH:
						/*
						 * More strict check with actual packet length
						 * is done runtime.
						 */
						if (p->k >= bpf_maxbufsize)
							return 0;
						break;
					case BPF_MEM:
						if (p->k >= BPF_MEMWORDS)
							return 0;
						break;
					case BPF_LEN:
						break;
					default:
						return 0;
				}
				break;
			case BPF_ST:
			case BPF_STX:
				if (p->k >= BPF_MEMWORDS)
					return 0;
				break;
			case BPF_ALU:
				switch (BPF_OP(p->code)) {
					case BPF_ADD:
					case BPF_SUB:
					case BPF_MUL:
					case BPF_OR:
					case BPF_AND:
					case BPF_LSH:
					case BPF_RSH:
					case BPF_NEG:
						break;
					case BPF_DIV:
						/* 
						 * Check for constant division by 0
						 */
						if(BPF_SRC(p->code) == BPF_K && p->k == 0)
							return 0;
						break;
					default:
						return 0;
				}
				break;
			case BPF_JMP:
				/*
				 * Check that jumps are within the code block,
				 * and that unconditional branches don't go 
				 * backwards as a result of an overflow.
				 * Unconditional branches have a 32-bit offset,
				 * so they could overflow; we check to make 
				 * sure they don't. Conditional branches have 
				 * an 8-bit offset, and the from address is 
				 * less than equal to BPF_MAXINSNS, and we assume that
				 * BPF_MAXINSNS is sufficiently small that adding 255 
				 * to it won't overlflow
				 *
				 * We know that len is <= BPF_MAXINSNS, and we 
				 * assume that BPF_MAXINSNS is less than the maximum 
				 * size of a u_int, so that i+1 doesn't overflow
				 */
				from = i+1;
				switch (BPF_OP(p->code)) {
					case BPF_JA:
						if (from + p->k < from || from + p->k >= ((u_int)len))
							return 0;
						break;
					case BPF_JEQ:
					case BPF_JGT:
					case BPF_JGE:
					case BPF_JSET:
						if (from + p->jt >= ((u_int)len) || from + p->jf >= ((u_int)len))
							return 0;
						break;
					default:
						return 0;
				}
				break;
			case BPF_RET:
				break;
			case BPF_MISC:
				break;
			default:
				return 0;
		}
	}
		return BPF_CLASS(f[len - 1].code) == BPF_RET;
}
#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
6d2010ae A	113	extern unsigned int bpf_maxbufsize;
6d2010ae A	114
91447636 A	115	static u_int16_t m_xhalf(struct mbuf m, bpf_u_int32 k, int err);
91447636 A	116	static u_int32_t m_xword(struct mbuf m, bpf_u_int32 k, int err);
1c79356b A	117
1c79356b A	118	static u_int32_t
91447636	119	m_xword(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	120	{
	121	register size_t len;
	122	register u_char cp, np;
	123	register struct mbuf *m0;
	124
	125	len = m->m_len;
	126	while (k >= len) {
	127	k -= len;
	128	m = m->m_next;
	129	if (m == 0)
	130	goto bad;
	131	len = m->m_len;
	132	}
	133	cp = mtod(m, u_char *) + k;
	134	if (len - k >= 4) {
	135	*err = 0;
	136	return EXTRACT_LONG(cp);
	137	}
	138	m0 = m->m_next;
	139	if (m0 == 0 \|\| m0->m_len + len - k < 4)
	140	goto bad;
	141	*err = 0;
	142	np = mtod(m0, u_char *);
	143	switch (len - k) {
	144
	145	case 1:
	146	return
	147	((u_int32_t)cp[0] << 24) \|
	148	((u_int32_t)np[0] << 16) \|
	149	((u_int32_t)np[1] << 8) \|
	150	(u_int32_t)np[2];
	151
	152	case 2:
	153	return
	154	((u_int32_t)cp[0] << 24) \|
	155	((u_int32_t)cp[1] << 16) \|
	156	((u_int32_t)np[0] << 8) \|
	157	(u_int32_t)np[1];
	158
	159	default:
	160	return
	161	((u_int32_t)cp[0] << 24) \|
	162	((u_int32_t)cp[1] << 16) \|
	163	((u_int32_t)cp[2] << 8) \|
	164	(u_int32_t)np[0];
	165	}
	166	bad:
	167	*err = 1;
	168	return 0;
	169	}
	170
	171	static u_int16_t
91447636	172	m_xhalf(struct mbuf m, bpf_u_int32 k, int err)
1c79356b A	173	{
	174	register size_t len;
	175	register u_char *cp;
	176	register struct mbuf *m0;
	177
	178	len = m->m_len;
	179	while (k >= len) {
	180	k -= len;
	181	m = m->m_next;
	182	if (m == 0)
	183	goto bad;
	184	len = m->m_len;
	185	}
	186	cp = mtod(m, u_char *) + k;
	187	if (len - k >= 2) {
	188	*err = 0;
	189	return EXTRACT_SHORT(cp);
	190	}
	191	m0 = m->m_next;
	192	if (m0 == 0)
	193	goto bad;
	194	*err = 0;
	195	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
	196	bad:
	197	*err = 1;
	198	return 0;
	199	}
	200	#endif
	201
	202	/*
	203	* Execute the filter program starting at pc on the packet p
	204	* wirelen is the length of the original packet
	205	* buflen is the amount of data present
	206	*/
	207	u_int
91447636	208	bpf_filter(const struct bpf_insn pc, u_char p, u_int wirelen, u_int buflen)
1c79356b A	209	{
	210	register u_int32_t A = 0, X = 0;
	211	register bpf_u_int32 k;
	212	int32_t mem[BPF_MEMWORDS];
	213
	214	if (pc == 0)
	215	/*
	216	* No filter means accept all.
	217	*/
	218	return (u_int)-1;
	219
	220	--pc;
	221	while (1) {
	222	++pc;
	223	switch (pc->code) {
	224
	225	default:
	226	#ifdef KERNEL
	227	return 0;
	228	#else
	229	abort();
	230	#endif
	231	case BPF_RET\|BPF_K:
	232	return (u_int)pc->k;
	233
	234	case BPF_RET\|BPF_A:
	235	return (u_int)A;
	236
	237	case BPF_LD\|BPF_W\|BPF_ABS:
	238	k = pc->k;
	239	if (k > buflen \|\| sizeof(int32_t) > buflen - k) {
	240	#ifdef KERNEL
	241	int merr;
	242
	243	if (buflen != 0)
	244	return 0;
	245	A = m_xword((struct mbuf *)p, k, &merr);
	246	if (merr != 0)
	247	return 0;
	248	continue;
	249	#else
	250	return 0;
	251	#endif
	252	}
	253	#if BPF_ALIGN
	254	if (((intptr_t)(p + k) & 3) != 0)
	255	A = EXTRACT_LONG(&p[k]);
	256	else
	257	#endif
	258	A = ntohl((int32_t )(p + k));
	259	continue;
	260
	261	case BPF_LD\|BPF_H\|BPF_ABS:
	262	k = pc->k;
	263	if (k > buflen \|\| sizeof(int16_t) > buflen - k) {
	264	#ifdef KERNEL
	265	int merr;
	266
	267	if (buflen != 0)
	268	return 0;
	269	A = m_xhalf((struct mbuf *)p, k, &merr);
	270	continue;
	271	#else
	272	return 0;
273	#endif
274	}
275	A = EXTRACT_SHORT(&p[k]);
276	continue;
277
278	case BPF_LD\|BPF_B\|BPF_ABS:
279	k = pc->k;
280	if (k >= buflen) {
281	#ifdef KERNEL
282	register struct mbuf *m;
283
284	if (buflen != 0)
285	return 0;
286	m = (struct mbuf *)p;
287	MINDEX(m, k);
288	A = mtod(m, u_char *)[k];
289	continue;
290	#else
291	return 0;
292	#endif
293	}
294	A = p[k];
295	continue;
296
297	case BPF_LD\|BPF_W\|BPF_LEN:
298	A = wirelen;
299	continue;
300
301	case BPF_LDX\|BPF_W\|BPF_LEN:
302	X = wirelen;
303	continue;
304
305	case BPF_LD\|BPF_W\|BPF_IND:
306	k = X + pc->k;
9bccf70c A	307	if (pc->k > buflen \|\| X > buflen - pc->k \|\|
9bccf70c A	308	sizeof(int32_t) > buflen - k) {
1c79356b A	309	#ifdef KERNEL
	310	int merr;
	311
	312	if (buflen != 0)
	313	return 0;
	314	A = m_xword((struct mbuf *)p, k, &merr);
	315	if (merr != 0)
	316	return 0;
	317	continue;
	318	#else
	319	return 0;
	320	#endif
	321	}
	322	#if BPF_ALIGN
	323	if (((intptr_t)(p + k) & 3) != 0)
	324	A = EXTRACT_LONG(&p[k]);
	325	else
	326	#endif
	327	A = ntohl((int32_t )(p + k));
	328	continue;
	329
	330	case BPF_LD\|BPF_H\|BPF_IND:
	331	k = X + pc->k;
9bccf70c A	332	if (X > buflen \|\| pc->k > buflen - X \|\|
9bccf70c A	333	sizeof(int16_t) > buflen - k) {
1c79356b A	334	#ifdef KERNEL
	335	int merr;
	336
	337	if (buflen != 0)
	338	return 0;
	339	A = m_xhalf((struct mbuf *)p, k, &merr);
	340	if (merr != 0)
	341	return 0;
	342	continue;
	343	#else
	344	return 0;
	345	#endif
	346	}
	347	A = EXTRACT_SHORT(&p[k]);
	348	continue;
	349
	350	case BPF_LD\|BPF_B\|BPF_IND:
	351	k = X + pc->k;
	352	if (pc->k >= buflen \|\| X >= buflen - pc->k) {
	353	#ifdef KERNEL
	354	register struct mbuf *m;
	355
	356	if (buflen != 0)
	357	return 0;
	358	m = (struct mbuf *)p;
	359	MINDEX(m, k);
2d21ac55	360	A = mtod(m, u_char *)[k];
1c79356b A	361	continue;
	362	#else
	363	return 0;
	364	#endif
	365	}
	366	A = p[k];
	367	continue;
	368
	369	case BPF_LDX\|BPF_MSH\|BPF_B:
	370	k = pc->k;
	371	if (k >= buflen) {
	372	#ifdef KERNEL
	373	register struct mbuf *m;
	374
	375	if (buflen != 0)
	376	return 0;
	377	m = (struct mbuf *)p;
	378	MINDEX(m, k);
2d21ac55	379	X = (mtod(m, u_char *)[k] & 0xf) << 2;
1c79356b A	380	continue;
	381	#else
	382	return 0;
	383	#endif
	384	}
	385	X = (p[pc->k] & 0xf) << 2;
	386	continue;
	387
	388	case BPF_LD\|BPF_IMM:
	389	A = pc->k;
	390	continue;
	391
	392	case BPF_LDX\|BPF_IMM:
	393	X = pc->k;
	394	continue;
	395
	396	case BPF_LD\|BPF_MEM:
	397	A = mem[pc->k];
	398	continue;
	399
	400	case BPF_LDX\|BPF_MEM:
	401	X = mem[pc->k];
	402	continue;
	403
	404	case BPF_ST:
	405	mem[pc->k] = A;
	406	continue;
	407
	408	case BPF_STX:
	409	mem[pc->k] = X;
	410	continue;
	411
	412	case BPF_JMP\|BPF_JA:
	413	pc += pc->k;
	414	continue;
	415
	416	case BPF_JMP\|BPF_JGT\|BPF_K:
	417	pc += (A > pc->k) ? pc->jt : pc->jf;
	418	continue;
	419
	420	case BPF_JMP\|BPF_JGE\|BPF_K:
	421	pc += (A >= pc->k) ? pc->jt : pc->jf;
	422	continue;
	423
	424	case BPF_JMP\|BPF_JEQ\|BPF_K:
	425	pc += (A == pc->k) ? pc->jt : pc->jf;
	426	continue;
	427
	428	case BPF_JMP\|BPF_JSET\|BPF_K:
	429	pc += (A & pc->k) ? pc->jt : pc->jf;
	430	continue;
	431
	432	case BPF_JMP\|BPF_JGT\|BPF_X:
	433	pc += (A > X) ? pc->jt : pc->jf;
	434	continue;
	435
	436	case BPF_JMP\|BPF_JGE\|BPF_X:
	437	pc += (A >= X) ? pc->jt : pc->jf;
	438	continue;
	439
	440	case BPF_JMP\|BPF_JEQ\|BPF_X:
	441	pc += (A == X) ? pc->jt : pc->jf;
	442	continue;
	443
444	case BPF_JMP\|BPF_JSET\|BPF_X:
445	pc += (A & X) ? pc->jt : pc->jf;
446	continue;
447
448	case BPF_ALU\|BPF_ADD\|BPF_X:
449	A += X;
450	continue;
451
452	case BPF_ALU\|BPF_SUB\|BPF_X:
453	A -= X;
454	continue;
455
456	case BPF_ALU\|BPF_MUL\|BPF_X:
457	A *= X;
458	continue;
459
460	case BPF_ALU\|BPF_DIV\|BPF_X:
461	if (X == 0)
462	return 0;
463	A /= X;
464	continue;
465
466	case BPF_ALU\|BPF_AND\|BPF_X:
467	A &= X;
468	continue;
469
470	case BPF_ALU\|BPF_OR\|BPF_X:
471	A \|= X;
472	continue;
473
474	case BPF_ALU\|BPF_LSH\|BPF_X:
475	A <<= X;
476	continue;
477
478	case BPF_ALU\|BPF_RSH\|BPF_X:
479	A >>= X;
480	continue;
481
482	case BPF_ALU\|BPF_ADD\|BPF_K:
483	A += pc->k;
484	continue;
485
486	case BPF_ALU\|BPF_SUB\|BPF_K:
487	A -= pc->k;
488	continue;
489
490	case BPF_ALU\|BPF_MUL\|BPF_K:
491	A *= pc->k;
492	continue;
493
494	case BPF_ALU\|BPF_DIV\|BPF_K:
495	A /= pc->k;
496	continue;
497
498	case BPF_ALU\|BPF_AND\|BPF_K:
499	A &= pc->k;
500	continue;
501
502	case BPF_ALU\|BPF_OR\|BPF_K:
503	A \|= pc->k;
504	continue;
505
506	case BPF_ALU\|BPF_LSH\|BPF_K:
507	A <<= pc->k;
508	continue;
509
510	case BPF_ALU\|BPF_RSH\|BPF_K:
511	A >>= pc->k;
512	continue;
513
514	case BPF_ALU\|BPF_NEG:
515	A = -A;
516	continue;
517
518	case BPF_MISC\|BPF_TAX:
519	X = A;
520	continue;
521
522	case BPF_MISC\|BPF_TXA:
523	A = X;
524	continue;
525	}
526	}
527	}
528
529	#ifdef KERNEL
530	/*
531	* Return true if the 'fcode' is a valid filter program.
532	* The constraints are that each jump be forward and to a valid
6d2010ae A	533	* code, that memory accesses are within valid ranges (to the
	534	* extent that this can be checked statically; loads of packet data
	535	* have to be, and are, also checked at run time), and that
	536	* the code terminates with either an accept or reject.
1c79356b A	537	*
	538	* The kernel needs to be able to verify an application's filter code.
	539	* Otherwise, a bogus program could easily crash the system.
	540	*/
	541	int
91447636	542	bpf_validate(const struct bpf_insn *f, int len)
1c79356b	543	{
6d2010ae	544	u_int i, from;
9bccf70c	545	const struct bpf_insn *p;
1c79356b	546
6d2010ae A	547	if (len < 1 \|\| len > BPF_MAXINSNS)
	548	return 0;
	549
	550	for (i = 0; i < ((u_int)len); ++i) {
1c79356b	551	p = &f[i];
6d2010ae A	552	switch (BPF_CLASS(p->code)) {
	553	/*
	554	* Check that memory operations use valid addresses
	555	*/
	556	case BPF_LD:
	557	case BPF_LDX:
	558	switch (BPF_MODE(p->code)) {
	559	case BPF_IMM:
	560	break;
	561	case BPF_ABS:
	562	case BPF_IND:
	563	case BPF_MSH:
	564	/*
	565	* More strict check with actual packet length
	566	* is done runtime.
	567	*/
	568	if (p->k >= bpf_maxbufsize)
	569	return 0;
	570	break;
	571	case BPF_MEM:
	572	if (p->k >= BPF_MEMWORDS)
	573	return 0;
	574	break;
	575	case BPF_LEN:
	576	break;
	577	default:
	578	return 0;
	579	}
	580	break;
	581	case BPF_ST:
	582	case BPF_STX:
	583	if (p->k >= BPF_MEMWORDS)
1c79356b	584	return 0;
6d2010ae A	585	break;
	586	case BPF_ALU:
	587	switch (BPF_OP(p->code)) {
	588	case BPF_ADD:
	589	case BPF_SUB:
	590	case BPF_MUL:
	591	case BPF_OR:
	592	case BPF_AND:
	593	case BPF_LSH:
	594	case BPF_RSH:
	595	case BPF_NEG:
	596	break;
	597	case BPF_DIV:
	598	/*
	599	* Check for constant division by 0
	600	*/
	601	if(BPF_SRC(p->code) == BPF_K && p->k == 0)
	602	return 0;
	603	break;
	604	default:
	605	return 0;
	606	}
	607	break;
	608	case BPF_JMP:
	609	/*
	610	* Check that jumps are within the code block,
	611	* and that unconditional branches don't go
	612	* backwards as a result of an overflow.
	613	* Unconditional branches have a 32-bit offset,
	614	* so they could overflow; we check to make
	615	* sure they don't. Conditional branches have
	616	* an 8-bit offset, and the from address is
	617	* less than equal to BPF_MAXINSNS, and we assume that
	618	* BPF_MAXINSNS is sufficiently small that adding 255
	619	* to it won't overlflow
	620	*
	621	* We know that len is <= BPF_MAXINSNS, and we
	622	* assume that BPF_MAXINSNS is less than the maximum
	623	* size of a u_int, so that i+1 doesn't overflow
	624	*/
	625	from = i+1;
	626	switch (BPF_OP(p->code)) {
	627	case BPF_JA:
	628	if (from + p->k < from \|\| from + p->k >= ((u_int)len))
	629	return 0;
	630	break;
	631	case BPF_JEQ:
	632	case BPF_JGT:
	633	case BPF_JGE:
	634	case BPF_JSET:
	635	if (from + p->jt >= ((u_int)len) \|\| from + p->jf >= ((u_int)len))
	636	return 0;
	637	break;
	638	default:
	639	return 0;
	640	}
	641	break;
	642	case BPF_RET:
	643	break;
	644	case BPF_MISC:
	645	break;
	646	default:
1c79356b A	647	return 0;
1c79356b A	648	}
1c79356b	649	}
6d2010ae	650	return BPF_CLASS(f[len - 1].code) == BPF_RET;
1c79356b A	651	}
1c79356b A	652	#endif