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

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1990, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
 * Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)bpf_filter.c	8.1 (Berkeley) 6/10/93
 *
 */

#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 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 - pc->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)
	struct bpf_insn *f;
	int len;
{
	register int i;
	register 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	*
	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
	11	*
	12	* This Original Code and all software distributed under the License are
	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/*
	23	* Copyright (c) 1990, 1991, 1993
	24	* The Regents of the University of California. All rights reserved.
	25	*
	26	* This code is derived from the Stanford/CMU enet packet filter,
	27	* (net/enet.c) distributed as part of 4.3BSD, and code contributed
	28	* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
	29	* Berkeley Laboratory.
	30	*
	31	* Redistribution and use in source and binary forms, with or without
	32	* modification, are permitted provided that the following conditions
	33	* are met:
	34	* 1. Redistributions of source code must retain the above copyright
	35	* notice, this list of conditions and the following disclaimer.
	36	* 2. Redistributions in binary form must reproduce the above copyright
	37	* notice, this list of conditions and the following disclaimer in the
	38	* documentation and/or other materials provided with the distribution.
	39	* 3. All advertising materials mentioning features or use of this software
	40	* must display the following acknowledgement:
	41	* This product includes software developed by the University of
	42	* California, Berkeley and its contributors.
	43	* 4. Neither the name of the University nor the names of its contributors
	44	* may be used to endorse or promote products derived from this software
	45	* without specific prior written permission.
	46	*
	47	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	48	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	49	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	50	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	51	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	52	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	53	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	54	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	55	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	56	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	57	* SUCH DAMAGE.
	58	*
	59	* @(#)bpf_filter.c 8.1 (Berkeley) 6/10/93
	60	*
	61	*/
	62
	63	#include <sys/param.h>
	64
65	#ifdef sun
66	#include <netinet/in.h>
67	#endif
68
69	#if defined(sparc) \|\| defined(mips) \|\| defined(ibm032) \|\| defined(__alpha__)
70	#define BPF_ALIGN
71	#endif
72
73	#ifndef BPF_ALIGN
74	#define EXTRACT_SHORT(p) ((u_int16_t)ntohs((u_int16_t )p))
75	#define EXTRACT_LONG(p) (ntohl((u_int32_t )p))
76	#else
77	#define EXTRACT_SHORT(p)\
78	((u_int16_t)\
79	((u_int16_t)((u_char )p+0)<<8\|\
80	(u_int16_t)((u_char )p+1)<<0))
81	#define EXTRACT_LONG(p)\
82	((u_int32_t)((u_char )p+0)<<24\|\
83	(u_int32_t)((u_char )p+1)<<16\|\
84	(u_int32_t)((u_char )p+2)<<8\|\
85	(u_int32_t)((u_char )p+3)<<0)
86	#endif
87
88	#ifdef KERNEL
89	#include <sys/mbuf.h>
90	#endif
91	#include <net/bpf.h>
92	#ifdef KERNEL
93	#define MINDEX(m, k) \
94	{ \
95	register int len = m->m_len; \
96	\
97	while (k >= len) { \
98	k -= len; \
99	m = m->m_next; \
100	if (m == 0) \
101	return 0; \
102	len = m->m_len; \
103	} \
104	}
105
106	static u_int16_t m_xhalf __P((struct mbuf m, bpf_u_int32 k, int err));
107	static u_int32_t m_xword __P((struct mbuf m, bpf_u_int32 k, int err));
108
109	static u_int32_t
110	m_xword(m, k, err)
111	register struct mbuf *m;
112	register bpf_u_int32 k;
113	register int *err;
114	{
115	register size_t len;
116	register u_char cp, np;
117	register struct mbuf *m0;
118
119	len = m->m_len;
120	while (k >= len) {
121	k -= len;
122	m = m->m_next;
123	if (m == 0)
124	goto bad;
125	len = m->m_len;
126	}
127	cp = mtod(m, u_char *) + k;
128	if (len - k >= 4) {
129	*err = 0;
130	return EXTRACT_LONG(cp);
131	}
132	m0 = m->m_next;
133	if (m0 == 0 \|\| m0->m_len + len - k < 4)
134	goto bad;
135	*err = 0;
136	np = mtod(m0, u_char *);
137	switch (len - k) {
138
139	case 1:
140	return
141	((u_int32_t)cp[0] << 24) \|
142	((u_int32_t)np[0] << 16) \|
143	((u_int32_t)np[1] << 8) \|
144	(u_int32_t)np[2];
145
146	case 2:
147	return
148	((u_int32_t)cp[0] << 24) \|
149	((u_int32_t)cp[1] << 16) \|
150	((u_int32_t)np[0] << 8) \|
151	(u_int32_t)np[1];
152
153	default:
154	return
155	((u_int32_t)cp[0] << 24) \|
156	((u_int32_t)cp[1] << 16) \|
157	((u_int32_t)cp[2] << 8) \|
158	(u_int32_t)np[0];
159	}
160	bad:
161	*err = 1;
162	return 0;
163	}
164
165	static u_int16_t
166	m_xhalf(m, k, err)
167	register struct mbuf *m;
168	register bpf_u_int32 k;
169	register int *err;
170	{
171	register size_t len;
172	register u_char *cp;
173	register struct mbuf *m0;
174
175	len = m->m_len;
176	while (k >= len) {
177	k -= len;
178	m = m->m_next;
179	if (m == 0)
180	goto bad;
181	len = m->m_len;
182	}
183	cp = mtod(m, u_char *) + k;
184	if (len - k >= 2) {
185	*err = 0;
186	return EXTRACT_SHORT(cp);
187	}
188	m0 = m->m_next;
189	if (m0 == 0)
190	goto bad;
191	*err = 0;
192	return (cp[0] << 8) \| mtod(m0, u_char *)[0];
193	bad:
194	*err = 1;
195	return 0;
196	}
197	#endif
198
199	/*
200	* Execute the filter program starting at pc on the packet p
201	* wirelen is the length of the original packet
202	* buflen is the amount of data present
203	*/
204	u_int
205	bpf_filter(pc, p, wirelen, buflen)
206	register struct bpf_insn *pc;
207	register u_char *p;
208	u_int wirelen;
209	register u_int buflen;
210	{
211	register u_int32_t A = 0, X = 0;
212	register bpf_u_int32 k;
213	int32_t mem[BPF_MEMWORDS];
214
215	if (pc == 0)
216	/*
217	* No filter means accept all.
218	*/
219	return (u_int)-1;
220
221	--pc;
222	while (1) {
223	++pc;
224	switch (pc->code) {
225
226	default:
227	#ifdef KERNEL
228	return 0;
229	#else
230	abort();
231	#endif
232	case BPF_RET\|BPF_K:
233	return (u_int)pc->k;
234
235	case BPF_RET\|BPF_A:
236	return (u_int)A;
237
238	case BPF_LD\|BPF_W\|BPF_ABS:
239	k = pc->k;
240	if (k > buflen \|\| sizeof(int32_t) > buflen - k) {
241	#ifdef KERNEL
242	int merr;
243
244	if (buflen != 0)
245	return 0;
246	A = m_xword((struct mbuf *)p, k, &merr);
247	if (merr != 0)
248	return 0;
249	continue;
250	#else
251	return 0;
252	#endif
253	}
254	#if BPF_ALIGN
255	if (((intptr_t)(p + k) & 3) != 0)
256	A = EXTRACT_LONG(&p[k]);
257	else
258	#endif
259	A = ntohl((int32_t )(p + k));
260	continue;
261
262	case BPF_LD\|BPF_H\|BPF_ABS:
263	k = pc->k;
264	if (k > buflen \|\| sizeof(int16_t) > buflen - k) {
265	#ifdef KERNEL
266	int merr;
267
268	if (buflen != 0)
269	return 0;
270	A = m_xhalf((struct mbuf *)p, k, &merr);
271	continue;
272	#else
273	return 0;
274	#endif
275	}
276	A = EXTRACT_SHORT(&p[k]);
277	continue;
278
279	case BPF_LD\|BPF_B\|BPF_ABS:
280	k = pc->k;
281	if (k >= buflen) {
282	#ifdef KERNEL
283	register struct mbuf *m;
284
285	if (buflen != 0)
286	return 0;
287	m = (struct mbuf *)p;
288	MINDEX(m, k);
289	A = mtod(m, u_char *)[k];
290	continue;
291	#else
292	return 0;
293	#endif
294	}
295	A = p[k];
296	continue;
297
298	case BPF_LD\|BPF_W\|BPF_LEN:
299	A = wirelen;
300	continue;
301
302	case BPF_LDX\|BPF_W\|BPF_LEN:
303	X = wirelen;
304	continue;
305
306	case BPF_LD\|BPF_W\|BPF_IND:
307	k = X + pc->k;
308	if (pc->k > buflen \|\| X > buflen - pc->k \|\| sizeof(int32_t) > buflen - k) {
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;
332	if (X > buflen \|\| pc->k > buflen - X \|\| sizeof(int16_t) > buflen - pc->k) {
333	#ifdef KERNEL
334	int merr;
335
336	if (buflen != 0)
337	return 0;
338	A = m_xhalf((struct mbuf *)p, k, &merr);
339	if (merr != 0)
340	return 0;
341	continue;
342	#else
343	return 0;
344	#endif
345	}
346	A = EXTRACT_SHORT(&p[k]);
347	continue;
348
349	case BPF_LD\|BPF_B\|BPF_IND:
350	k = X + pc->k;
351	if (pc->k >= buflen \|\| X >= buflen - pc->k) {
352	#ifdef KERNEL
353	register struct mbuf *m;
354
355	if (buflen != 0)
356	return 0;
357	m = (struct mbuf *)p;
358	MINDEX(m, k);
359	A = mtod(m, char *)[k];
360	continue;
361	#else
362	return 0;
363	#endif
364	}
365	A = p[k];
366	continue;
367
368	case BPF_LDX\|BPF_MSH\|BPF_B:
369	k = pc->k;
370	if (k >= buflen) {
371	#ifdef KERNEL
372	register struct mbuf *m;
373
374	if (buflen != 0)
375	return 0;
376	m = (struct mbuf *)p;
377	MINDEX(m, k);
378	X = (mtod(m, char *)[k] & 0xf) << 2;
379	continue;
380	#else
381	return 0;
382	#endif
383	}
384	X = (p[pc->k] & 0xf) << 2;
385	continue;
386
387	case BPF_LD\|BPF_IMM:
388	A = pc->k;
389	continue;
390
391	case BPF_LDX\|BPF_IMM:
392	X = pc->k;
393	continue;
394
395	case BPF_LD\|BPF_MEM:
396	A = mem[pc->k];
397	continue;
398
399	case BPF_LDX\|BPF_MEM:
400	X = mem[pc->k];
401	continue;
402
403	case BPF_ST:
404	mem[pc->k] = A;
405	continue;
406
407	case BPF_STX:
408	mem[pc->k] = X;
409	continue;
410
411	case BPF_JMP\|BPF_JA:
412	pc += pc->k;
413	continue;
414
415	case BPF_JMP\|BPF_JGT\|BPF_K:
416	pc += (A > pc->k) ? pc->jt : pc->jf;
417	continue;
418
419	case BPF_JMP\|BPF_JGE\|BPF_K:
420	pc += (A >= pc->k) ? pc->jt : pc->jf;
421	continue;
422
423	case BPF_JMP\|BPF_JEQ\|BPF_K:
424	pc += (A == pc->k) ? pc->jt : pc->jf;
425	continue;
426
427	case BPF_JMP\|BPF_JSET\|BPF_K:
428	pc += (A & pc->k) ? pc->jt : pc->jf;
429	continue;
430
431	case BPF_JMP\|BPF_JGT\|BPF_X:
432	pc += (A > X) ? pc->jt : pc->jf;
433	continue;
434
435	case BPF_JMP\|BPF_JGE\|BPF_X:
436	pc += (A >= X) ? pc->jt : pc->jf;
437	continue;
438
439	case BPF_JMP\|BPF_JEQ\|BPF_X:
440	pc += (A == X) ? pc->jt : pc->jf;
441	continue;
442
443	case BPF_JMP\|BPF_JSET\|BPF_X:
444	pc += (A & X) ? pc->jt : pc->jf;
445	continue;
446
447	case BPF_ALU\|BPF_ADD\|BPF_X:
448	A += X;
449	continue;
450
451	case BPF_ALU\|BPF_SUB\|BPF_X:
452	A -= X;
453	continue;
454
455	case BPF_ALU\|BPF_MUL\|BPF_X:
456	A *= X;
457	continue;
458
459	case BPF_ALU\|BPF_DIV\|BPF_X:
460	if (X == 0)
461	return 0;
462	A /= X;
463	continue;
464
465	case BPF_ALU\|BPF_AND\|BPF_X:
466	A &= X;
467	continue;
468
469	case BPF_ALU\|BPF_OR\|BPF_X:
470	A \|= X;
471	continue;
472
473	case BPF_ALU\|BPF_LSH\|BPF_X:
474	A <<= X;
475	continue;
476
477	case BPF_ALU\|BPF_RSH\|BPF_X:
478	A >>= X;
479	continue;
480
481	case BPF_ALU\|BPF_ADD\|BPF_K:
482	A += pc->k;
483	continue;
484
485	case BPF_ALU\|BPF_SUB\|BPF_K:
486	A -= pc->k;
487	continue;
488
489	case BPF_ALU\|BPF_MUL\|BPF_K:
490	A *= pc->k;
491	continue;
492
493	case BPF_ALU\|BPF_DIV\|BPF_K:
494	A /= pc->k;
495	continue;
496
497	case BPF_ALU\|BPF_AND\|BPF_K:
498	A &= pc->k;
499	continue;
500
501	case BPF_ALU\|BPF_OR\|BPF_K:
502	A \|= pc->k;
503	continue;
504
505	case BPF_ALU\|BPF_LSH\|BPF_K:
506	A <<= pc->k;
507	continue;
508
509	case BPF_ALU\|BPF_RSH\|BPF_K:
510	A >>= pc->k;
511	continue;
512
513	case BPF_ALU\|BPF_NEG:
514	A = -A;
515	continue;
516
517	case BPF_MISC\|BPF_TAX:
518	X = A;
519	continue;
520
521	case BPF_MISC\|BPF_TXA:
522	A = X;
523	continue;
524	}
525	}
526	}
527
528	#ifdef KERNEL
529	/*
530	* Return true if the 'fcode' is a valid filter program.
531	* The constraints are that each jump be forward and to a valid
532	* code. The code must terminate with either an accept or reject.
533	* 'valid' is an array for use by the routine (it must be at least
534	* 'len' bytes long).
535	*
536	* The kernel needs to be able to verify an application's filter code.
537	* Otherwise, a bogus program could easily crash the system.
538	*/
539	int
540	bpf_validate(f, len)
541	struct bpf_insn *f;
542	int len;
543	{
544	register int i;
545	register struct bpf_insn *p;
546
547	for (i = 0; i < len; ++i) {
548	/*
549	* Check that that jumps are forward, and within
550	* the code block.
551	*/
552	p = &f[i];
553	if (BPF_CLASS(p->code) == BPF_JMP) {
554	register int from = i + 1;
555
556	if (BPF_OP(p->code) == BPF_JA) {
557	if (from >= len \|\| p->k >= len - from)
558	return 0;
559	}
560	else if (from >= len \|\| p->jt >= len - from \|\| p->jf >= len - from)
561	return 0;
562	}
563	/*
564	* Check that memory operations use valid addresses.
565	*/
566	if ((BPF_CLASS(p->code) == BPF_ST \|\|
567	(BPF_CLASS(p->code) == BPF_LD &&
568	(p->code & 0xe0) == BPF_MEM)) &&
569	p->k >= BPF_MEMWORDS)
570	return 0;
571	/*
572	* Check for constant division by 0.
573	*/
574	if (p->code == (BPF_ALU\|BPF_DIV\|BPF_K) && p->k == 0)
575	return 0;
576	}
577	return BPF_CLASS(f[len - 1].code) == BPF_RET;
578	}
579	#endif