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

/*
 * Copyright (c) 2000-2011 Apple 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>
#include <string.h>

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

#if !defined(__i386__) && !defined(__x86_64__)
#define BPF_ALIGN 1
#else /* defined(__i386__) || defined(__x86_64__) */
#define BPF_ALIGN 0
#endif /* defined(__i386__) || defined(__x86_64__) */

#if !BPF_ALIGN
#define EXTRACT_SHORT(p)	((u_int16_t)ntohs(*(u_int16_t *)(void *)p))
#define EXTRACT_LONG(p)		(ntohl(*(u_int32_t *)(void *)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) \
{ \
	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)
{
	size_t len;
	u_char *cp, *np;
	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)
{
	size_t len;
	u_char *cp;
	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)
{
	u_int32_t A = 0, X = 0;
	bpf_u_int32 k;
	int32_t mem[BPF_MEMWORDS];

	bzero(mem, sizeof(mem));

	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 *)(void *)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 *)(void *)(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 *)(void *)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
				struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)(void *)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 *)(void *)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 *)(void *)(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 *)(void *)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
				struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)(void *)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
				struct mbuf *m;

				if (buflen != 0)
					return 0;
				m = (struct mbuf *)(void *)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:
			if (pc->k >= BPF_MEMWORDS)
				return 0;
			mem[pc->k] = A;
			continue;

		case BPF_STX:
			if (pc->k >= BPF_MEMWORDS)
				return 0;
			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	/*
316670eb	2	* Copyright (c) 2000-2011 Apple Inc. All rights reserved.
5d5c5d0d	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>
316670eb	71	#include <string.h>
1c79356b A	72
	73	#ifdef sun
	74	#include <netinet/in.h>
	75	#endif
	76
316670eb A	77	#if !defined(__i386__) && !defined(__x86_64__)
	78	#define BPF_ALIGN 1
	79	#else /* defined(__i386__) \|\| defined(__x86_64__) */
	80	#define BPF_ALIGN 0
	81	#endif /* defined(__i386__) \|\| defined(__x86_64__) */
1c79356b	82
316670eb A	83	#if !BPF_ALIGN
	84	#define EXTRACT_SHORT(p) ((u_int16_t)ntohs((u_int16_t )(void *)p))
	85	#define EXTRACT_LONG(p) (ntohl((u_int32_t )(void *)p))
1c79356b A	86	#else
	87	#define EXTRACT_SHORT(p)\
	88	((u_int16_t)\
	89	((u_int16_t)((u_char )p+0)<<8\|\
	90	(u_int16_t)((u_char )p+1)<<0))
	91	#define EXTRACT_LONG(p)\
	92	((u_int32_t)((u_char )p+0)<<24\|\
	93	(u_int32_t)((u_char )p+1)<<16\|\
	94	(u_int32_t)((u_char )p+2)<<8\|\
	95	(u_int32_t)((u_char )p+3)<<0)
	96	#endif
	97
	98	#ifdef KERNEL
	99	#include <sys/mbuf.h>
	100	#endif
	101	#include <net/bpf.h>
	102	#ifdef KERNEL
	103	#define MINDEX(m, k) \
	104	{ \
39037602	105	unsigned int len = m->m_len; \
1c79356b A	106	\
	107	while (k >= len) { \
	108	k -= len; \
	109	m = m->m_next; \
	110	if (m == 0) \
	111	return 0; \
	112	len = m->m_len; \
	113	} \
	114	}
	115
6d2010ae A	116	extern unsigned int bpf_maxbufsize;
6d2010ae A	117
91447636 A	118	static u_int16_t m_xhalf(struct mbuf m, bpf_u_int32 k, int err);
91447636 A	119	static u_int32_t m_xword(struct mbuf m, bpf_u_int32 k, int err);
1c79356b A	120
1c79356b A	121	static u_int32_t
91447636	122	m_xword(struct mbuf m, bpf_u_int32 k, int err)
1c79356b	123	{
39037602 A	124	size_t len;
	125	u_char cp, np;
	126	struct mbuf *m0;
1c79356b A	127
	128	len = m->m_len;
	129	while (k >= len) {
	130	k -= len;
	131	m = m->m_next;
	132	if (m == 0)
	133	goto bad;
	134	len = m->m_len;
	135	}
	136	cp = mtod(m, u_char *) + k;
	137	if (len - k >= 4) {
	138	*err = 0;
	139	return EXTRACT_LONG(cp);
	140	}
	141	m0 = m->m_next;
	142	if (m0 == 0 \|\| m0->m_len + len - k < 4)
	143	goto bad;
	144	*err = 0;
	145	np = mtod(m0, u_char *);
	146	switch (len - k) {
	147
	148	case 1:
	149	return
	150	((u_int32_t)cp[0] << 24) \|
	151	((u_int32_t)np[0] << 16) \|
	152	((u_int32_t)np[1] << 8) \|
	153	(u_int32_t)np[2];
	154
	155	case 2:
	156	return
	157	((u_int32_t)cp[0] << 24) \|
	158	((u_int32_t)cp[1] << 16) \|
	159	((u_int32_t)np[0] << 8) \|
	160	(u_int32_t)np[1];
	161
	162	default:
	163	return
	164	((u_int32_t)cp[0] << 24) \|
	165	((u_int32_t)cp[1] << 16) \|
	166	((u_int32_t)cp[2] << 8) \|
	167	(u_int32_t)np[0];
	168	}
	169	bad:
	170	*err = 1;
	171	return 0;
	172	}
	173
	174	static u_int16_t
91447636	175	m_xhalf(struct mbuf m, bpf_u_int32 k, int err)
1c79356b	176	{
39037602 A	177	size_t len;
	178	u_char *cp;
	179	struct mbuf *m0;
1c79356b A	180
	181	len = m->m_len;
	182	while (k >= len) {
	183	k -= len;
	184	m = m->m_next;
	185	if (m == 0)
	186	goto bad;
	187	len = m->m_len;
	188	}
	189	cp = mtod(m, u_char *) + k;
	190	if (len - k >= 2) {
	191	*err = 0;
	192	return EXTRACT_SHORT(cp);
	193	}
	194	m0 = m->m_next;
	195	if (m0 == 0)
	196	goto bad;
	197	*err = 0;
	198	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
	199	bad:
	200	*err = 1;
	201	return 0;
	202	}
	203	#endif
	204
	205	/*
	206	* Execute the filter program starting at pc on the packet p
	207	* wirelen is the length of the original packet
	208	* buflen is the amount of data present
	209	*/
	210	u_int
91447636	211	bpf_filter(const struct bpf_insn pc, u_char p, u_int wirelen, u_int buflen)
1c79356b	212	{
39037602 A	213	u_int32_t A = 0, X = 0;
39037602 A	214	bpf_u_int32 k;
1c79356b A	215	int32_t mem[BPF_MEMWORDS];
1c79356b A	216
316670eb A	217	bzero(mem, sizeof(mem));
316670eb A	218
1c79356b A	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;
316670eb	250	A = m_xword((struct mbuf )(void )p, k, &merr);
1c79356b A	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
316670eb	263	A = ntohl((int32_t )(void *)(p + k));
1c79356b A	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;
316670eb	274	A = m_xhalf((struct mbuf )(void )p, k, &merr);
1c79356b A	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
39037602	287	struct mbuf *m;
1c79356b A	288
	289	if (buflen != 0)
	290	return 0;
316670eb	291	m = (struct mbuf )(void )p;
1c79356b A	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;
316670eb	319	A = m_xword((struct mbuf )(void )p, k, &merr);
1c79356b A	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
316670eb	332	A = ntohl((int32_t )(void *)(p + k));
1c79356b A	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;
316670eb	344	A = m_xhalf((struct mbuf )(void )p, k, &merr);
1c79356b A	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
39037602	359	struct mbuf *m;
1c79356b A	360
	361	if (buflen != 0)
	362	return 0;
316670eb	363	m = (struct mbuf )(void )p;
1c79356b	364	MINDEX(m, k);
2d21ac55	365	A = mtod(m, u_char *)[k];
1c79356b A	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
39037602	378	struct mbuf *m;
1c79356b A	379
	380	if (buflen != 0)
	381	return 0;
316670eb	382	m = (struct mbuf )(void )p;
1c79356b	383	MINDEX(m, k);
2d21ac55	384	X = (mtod(m, u_char *)[k] & 0xf) << 2;
1c79356b A	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:
39236c6e A	410	if (pc->k >= BPF_MEMWORDS)
39236c6e A	411	return 0;
1c79356b A	412	mem[pc->k] = A;
	413	continue;
	414
	415	case BPF_STX:
39236c6e A	416	if (pc->k >= BPF_MEMWORDS)
39236c6e A	417	return 0;
1c79356b A	418	mem[pc->k] = X;
	419	continue;
	420
	421	case BPF_JMP\|BPF_JA:
	422	pc += pc->k;
	423	continue;
	424
	425	case BPF_JMP\|BPF_JGT\|BPF_K:
	426	pc += (A > pc->k) ? pc->jt : pc->jf;
	427	continue;
	428
	429	case BPF_JMP\|BPF_JGE\|BPF_K:
	430	pc += (A >= pc->k) ? pc->jt : pc->jf;
	431	continue;
	432
	433	case BPF_JMP\|BPF_JEQ\|BPF_K:
	434	pc += (A == pc->k) ? pc->jt : pc->jf;
	435	continue;
	436
	437	case BPF_JMP\|BPF_JSET\|BPF_K:
	438	pc += (A & pc->k) ? pc->jt : pc->jf;
	439	continue;
	440
	441	case BPF_JMP\|BPF_JGT\|BPF_X:
	442	pc += (A > X) ? pc->jt : pc->jf;
	443	continue;
	444
	445	case BPF_JMP\|BPF_JGE\|BPF_X:
	446	pc += (A >= X) ? pc->jt : pc->jf;
	447	continue;
	448
	449	case BPF_JMP\|BPF_JEQ\|BPF_X:
	450	pc += (A == X) ? pc->jt : pc->jf;
	451	continue;
	452
	453	case BPF_JMP\|BPF_JSET\|BPF_X:
	454	pc += (A & X) ? pc->jt : pc->jf;
	455	continue;
	456
	457	case BPF_ALU\|BPF_ADD\|BPF_X:
	458	A += X;
	459	continue;
	460
	461	case BPF_ALU\|BPF_SUB\|BPF_X:
	462	A -= X;
	463	continue;
	464
	465	case BPF_ALU\|BPF_MUL\|BPF_X:
	466	A *= X;
	467	continue;
	468
	469	case BPF_ALU\|BPF_DIV\|BPF_X:
	470	if (X == 0)
	471	return 0;
	472	A /= X;
	473	continue;
	474
	475	case BPF_ALU\|BPF_AND\|BPF_X:
	476	A &= X;
	477	continue;
	478
	479	case BPF_ALU\|BPF_OR\|BPF_X:
	480	A \|= X;
	481	continue;
482
483	case BPF_ALU\|BPF_LSH\|BPF_X:
484	A <<= X;
485	continue;
486
487	case BPF_ALU\|BPF_RSH\|BPF_X:
488	A >>= X;
489	continue;
490
491	case BPF_ALU\|BPF_ADD\|BPF_K:
492	A += pc->k;
493	continue;
494
495	case BPF_ALU\|BPF_SUB\|BPF_K:
496	A -= pc->k;
497	continue;
498
499	case BPF_ALU\|BPF_MUL\|BPF_K:
500	A *= pc->k;
501	continue;
502
503	case BPF_ALU\|BPF_DIV\|BPF_K:
504	A /= pc->k;
505	continue;
506
507	case BPF_ALU\|BPF_AND\|BPF_K:
508	A &= pc->k;
509	continue;
510
511	case BPF_ALU\|BPF_OR\|BPF_K:
512	A \|= pc->k;
513	continue;
514
515	case BPF_ALU\|BPF_LSH\|BPF_K:
516	A <<= pc->k;
517	continue;
518
519	case BPF_ALU\|BPF_RSH\|BPF_K:
520	A >>= pc->k;
521	continue;
522
523	case BPF_ALU\|BPF_NEG:
524	A = -A;
525	continue;
526
527	case BPF_MISC\|BPF_TAX:
528	X = A;
529	continue;
530
531	case BPF_MISC\|BPF_TXA:
532	A = X;
533	continue;
534	}
535	}
536	}
537
538	#ifdef KERNEL
539	/*
540	* Return true if the 'fcode' is a valid filter program.
541	* The constraints are that each jump be forward and to a valid
6d2010ae A	542	* code, that memory accesses are within valid ranges (to the
	543	* extent that this can be checked statically; loads of packet data
	544	* have to be, and are, also checked at run time), and that
	545	* the code terminates with either an accept or reject.
1c79356b A	546	*
	547	* The kernel needs to be able to verify an application's filter code.
	548	* Otherwise, a bogus program could easily crash the system.
	549	*/
	550	int
91447636	551	bpf_validate(const struct bpf_insn *f, int len)
1c79356b	552	{
6d2010ae	553	u_int i, from;
9bccf70c	554	const struct bpf_insn *p;
1c79356b	555
6d2010ae A	556	if (len < 1 \|\| len > BPF_MAXINSNS)
	557	return 0;
	558
	559	for (i = 0; i < ((u_int)len); ++i) {
1c79356b	560	p = &f[i];
6d2010ae A	561	switch (BPF_CLASS(p->code)) {
	562	/*
	563	* Check that memory operations use valid addresses
	564	*/
	565	case BPF_LD:
	566	case BPF_LDX:
	567	switch (BPF_MODE(p->code)) {
	568	case BPF_IMM:
	569	break;
	570	case BPF_ABS:
	571	case BPF_IND:
	572	case BPF_MSH:
	573	/*
	574	* More strict check with actual packet length
	575	* is done runtime.
	576	*/
	577	if (p->k >= bpf_maxbufsize)
	578	return 0;
	579	break;
	580	case BPF_MEM:
	581	if (p->k >= BPF_MEMWORDS)
	582	return 0;
	583	break;
	584	case BPF_LEN:
	585	break;
	586	default:
	587	return 0;
	588	}
	589	break;
	590	case BPF_ST:
	591	case BPF_STX:
	592	if (p->k >= BPF_MEMWORDS)
1c79356b	593	return 0;
6d2010ae A	594	break;
	595	case BPF_ALU:
	596	switch (BPF_OP(p->code)) {
	597	case BPF_ADD:
	598	case BPF_SUB:
	599	case BPF_MUL:
	600	case BPF_OR:
	601	case BPF_AND:
	602	case BPF_LSH:
	603	case BPF_RSH:
	604	case BPF_NEG:
	605	break;
	606	case BPF_DIV:
	607	/*
	608	* Check for constant division by 0
	609	*/
	610	if(BPF_SRC(p->code) == BPF_K && p->k == 0)
	611	return 0;
	612	break;
	613	default:
	614	return 0;
	615	}
	616	break;
	617	case BPF_JMP:
	618	/*
	619	* Check that jumps are within the code block,
	620	* and that unconditional branches don't go
	621	* backwards as a result of an overflow.
	622	* Unconditional branches have a 32-bit offset,
	623	* so they could overflow; we check to make
	624	* sure they don't. Conditional branches have
	625	* an 8-bit offset, and the from address is
	626	* less than equal to BPF_MAXINSNS, and we assume that
	627	* BPF_MAXINSNS is sufficiently small that adding 255
	628	* to it won't overlflow
	629	*
	630	* We know that len is <= BPF_MAXINSNS, and we
	631	* assume that BPF_MAXINSNS is less than the maximum
	632	* size of a u_int, so that i+1 doesn't overflow
	633	*/
	634	from = i+1;
	635	switch (BPF_OP(p->code)) {
	636	case BPF_JA:
	637	if (from + p->k < from \|\| from + p->k >= ((u_int)len))
	638	return 0;
	639	break;
	640	case BPF_JEQ:
	641	case BPF_JGT:
	642	case BPF_JGE:
	643	case BPF_JSET:
	644	if (from + p->jt >= ((u_int)len) \|\| from + p->jf >= ((u_int)len))
	645	return 0;
	646	break;
	647	default:
	648	return 0;
	649	}
	650	break;
	651	case BPF_RET:
	652	break;
	653	case BPF_MISC:
	654	break;
	655	default:
1c79356b A	656	return 0;
1c79356b A	657	}
1c79356b	658	}
6d2010ae	659	return BPF_CLASS(f[len - 1].code) == BPF_RET;
1c79356b A	660	}
1c79356b A	661	#endif