[unix-history] / sys / net / bpf_filter.c

/*-
 * Copyright (c) 1990-1991 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.
 *
 *	from: @(#)bpf.c	7.5 (Berkeley) 7/15/91
 *	$Id: bpf_filter.c,v 1.2 1993/10/16 17:43:07 rgrimes Exp $
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/time.h>
#include <net/bpf.h>

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

#if defined(sparc) || defined(mips) || defined(ibm032)
#define BPF_ALIGN
#endif

#ifndef BPF_ALIGN
#define EXTRACT_SHORT(p)	((u_short)ntohs(*(u_short *)p))
#define EXTRACT_LONG(p)		(ntohl(*(u_long *)p))
#else
#define EXTRACT_SHORT(p)\
	((u_short)\
		((u_short)*((u_char *)p+0)<<8|\
		 (u_short)*((u_char *)p+1)<<0))
#define EXTRACT_LONG(p)\
		((u_long)*((u_char *)p+0)<<24|\
		 (u_long)*((u_char *)p+1)<<16|\
		 (u_long)*((u_char *)p+2)<<8|\
		 (u_long)*((u_char *)p+3)<<0)
#endif

#ifdef KERNEL
#include <sys/mbuf.h>
#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 int
m_xword(m, k, err)
	register struct mbuf *m;
	register int k, *err;
{
	register int 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 (cp[k] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];

	case 2:
		return (cp[k] << 24) | (cp[k + 1] << 16) | (np[0] << 8) | 
			np[1];

	default:
		return (cp[k] << 24) | (cp[k + 1] << 16) | (cp[k + 2] << 8) |
			np[0];
	}
    bad:
	*err = 1;
	return 0;
}

static int
m_xhalf(m, k, err)
	register struct mbuf *m;
	register int k, *err;
{
	register int 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[k] << 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_long A = 0, X = 0;
	register int k;
	long mem[BPF_MEMWORDS];

	if (pc == 0)
		/*
		 * No filter means accept all.
		 */
		return (u_int)-1;
#ifdef lint
	A = 0;
	X = 0;
#endif
	--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 + sizeof(long) > buflen) {
#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
			}
#ifdef BPF_ALIGN
			if (((int)(p + k) & 3) != 0)
				A = EXTRACT_LONG(&p[k]);
			else
#endif
				A = ntohl(*(long *)(p + k));
			continue;

		case BPF_LD|BPF_H|BPF_ABS:
			k = pc->k;
			if (k + sizeof(short) > buflen) {
#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 (k + sizeof(long) > buflen) {
#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
			}
#ifdef BPF_ALIGN
			if (((int)(p + k) & 3) != 0)
				A = EXTRACT_LONG(&p[k]);
			else
#endif
				A = ntohl(*(long *)(p + k));
			continue;

		case BPF_LD|BPF_H|BPF_IND:
			k = X + pc->k;
			if (k + sizeof(short) > buflen) {
#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 (k >= buflen) {
#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 + p->k >= len)
					return 0;
			}
			else if (from + p->jt >= len || from + p->jf >= len)
				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 || p->k < 0))
			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
15637ed4 RG	1	/*-
	2	* Copyright (c) 1990-1991 The Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* This code is derived from the Stanford/CMU enet packet filter,
	6	* (net/enet.c) distributed as part of 4.3BSD, and code contributed
	7	* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
	8	* Berkeley Laboratory.
	9	*
	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	* 1. Redistributions of source code must retain the above copyright
	14	* notice, this list of conditions and the following disclaimer.
	15	* 2. Redistributions in binary form must reproduce the above copyright
	16	* notice, this list of conditions and the following disclaimer in the
	17	* documentation and/or other materials provided with the distribution.
	18	* 3. All advertising materials mentioning features or use of this software
	19	* must display the following acknowledgement:
	20	* This product includes software developed by the University of
	21	* California, Berkeley and its contributors.
	22	* 4. Neither the name of the University nor the names of its contributors
	23	* may be used to endorse or promote products derived from this software
	24	* without specific prior written permission.
	25	*
	26	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	27	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	28	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	29	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	30	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	31	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	32	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	33	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	34	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	35	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	36	* SUCH DAMAGE.
	37	*
70c5ff60	38	* from: @(#)bpf.c 7.5 (Berkeley) 7/15/91
4c45483e	39	* $Id: bpf_filter.c,v 1.2 1993/10/16 17:43:07 rgrimes Exp $
15637ed4	40	*/
15637ed4 RG	41
	42	#include <sys/param.h>
	43	#include <sys/types.h>
	44	#include <sys/time.h>
	45	#include <net/bpf.h>
	46
	47	#ifdef sun
	48	#include <netinet/in.h>
	49	#endif
	50
	51	#if defined(sparc) \|\| defined(mips) \|\| defined(ibm032)
	52	#define BPF_ALIGN
	53	#endif
	54
	55	#ifndef BPF_ALIGN
	56	#define EXTRACT_SHORT(p) ((u_short)ntohs((u_short )p))
	57	#define EXTRACT_LONG(p) (ntohl((u_long )p))
	58	#else
	59	#define EXTRACT_SHORT(p)\
	60	((u_short)\
	61	((u_short)((u_char )p+0)<<8\|\
	62	(u_short)((u_char )p+1)<<0))
	63	#define EXTRACT_LONG(p)\
	64	((u_long)((u_char )p+0)<<24\|\
	65	(u_long)((u_char )p+1)<<16\|\
	66	(u_long)((u_char )p+2)<<8\|\
	67	(u_long)((u_char )p+3)<<0)
	68	#endif
	69
	70	#ifdef KERNEL
	71	#include <sys/mbuf.h>
	72	#define MINDEX(m, k) \
	73	{ \
	74	register int len = m->m_len; \
	75	\
	76	while (k >= len) { \
	77	k -= len; \
	78	m = m->m_next; \
	79	if (m == 0) \
	80	return 0; \
	81	len = m->m_len; \
	82	} \
	83	}
	84
	85	static int
	86	m_xword(m, k, err)
	87	register struct mbuf *m;
	88	register int k, *err;
	89	{
	90	register int len;
	91	register u_char cp, np;
	92	register struct mbuf *m0;
	93
	94	len = m->m_len;
	95	while (k >= len) {
	96	k -= len;
	97	m = m->m_next;
	98	if (m == 0)
	99	goto bad;
	100	len = m->m_len;
	101	}
	102	cp = mtod(m, u_char *) + k;
	103	if (len - k >= 4) {
	104	*err = 0;
105	return EXTRACT_LONG(cp);
106	}
107	m0 = m->m_next;
108	if (m0 == 0 \|\| m0->m_len + len - k < 4)
109	goto bad;
110	*err = 0;
111	np = mtod(m0, u_char *);
112	switch (len - k) {
113
114	case 1:
115	return (cp[k] << 24) \| (np[0] << 16) \| (np[1] << 8) \| np[2];
116
117	case 2:
118	return (cp[k] << 24) \| (cp[k + 1] << 16) \| (np[0] << 8) \|
119	np[1];
120
121	default:
122	return (cp[k] << 24) \| (cp[k + 1] << 16) \| (cp[k + 2] << 8) \|
123	np[0];
124	}
125	bad:
126	*err = 1;
127	return 0;
128	}
129
130	static int
131	m_xhalf(m, k, err)
132	register struct mbuf *m;
133	register int k, *err;
134	{
135	register int len;
136	register u_char *cp;
137	register struct mbuf *m0;
138
139	len = m->m_len;
140	while (k >= len) {
141	k -= len;
142	m = m->m_next;
143	if (m == 0)
144	goto bad;
145	len = m->m_len;
146	}
147	cp = mtod(m, u_char *) + k;
148	if (len - k >= 2) {
149	*err = 0;
150	return EXTRACT_SHORT(cp);
151	}
152	m0 = m->m_next;
153	if (m0 == 0)
154	goto bad;
155	*err = 0;
156	return (cp[k] << 8) \| mtod(m0, u_char *)[0];
157	bad:
158	*err = 1;
159	return 0;
160	}
161	#endif
162
163	/*
164	* Execute the filter program starting at pc on the packet p
165	* wirelen is the length of the original packet
166	* buflen is the amount of data present
167	*/
168	u_int
169	bpf_filter(pc, p, wirelen, buflen)
170	register struct bpf_insn *pc;
171	register u_char *p;
172	u_int wirelen;
173	register u_int buflen;
174	{
4c45483e	175	register u_long A = 0, X = 0;
15637ed4 RG	176	register int k;
	177	long mem[BPF_MEMWORDS];
	178
	179	if (pc == 0)
	180	/*
	181	* No filter means accept all.
	182	*/
	183	return (u_int)-1;
	184	#ifdef lint
	185	A = 0;
	186	X = 0;
	187	#endif
	188	--pc;
	189	while (1) {
	190	++pc;
	191	switch (pc->code) {
	192
	193	default:
	194	#ifdef KERNEL
	195	return 0;
	196	#else
	197	abort();
	198	#endif
	199	case BPF_RET\|BPF_K:
	200	return (u_int)pc->k;
	201
	202	case BPF_RET\|BPF_A:
	203	return (u_int)A;
	204
	205	case BPF_LD\|BPF_W\|BPF_ABS:
	206	k = pc->k;
	207	if (k + sizeof(long) > buflen) {
	208	#ifdef KERNEL
	209	int merr;
	210
	211	if (buflen != 0)
	212	return 0;
	213	A = m_xword((struct mbuf *)p, k, &merr);
	214	if (merr != 0)
	215	return 0;
	216	continue;
	217	#else
	218	return 0;
	219	#endif
	220	}
	221	#ifdef BPF_ALIGN
	222	if (((int)(p + k) & 3) != 0)
	223	A = EXTRACT_LONG(&p[k]);
	224	else
	225	#endif
	226	A = ntohl((long )(p + k));
	227	continue;
	228
	229	case BPF_LD\|BPF_H\|BPF_ABS:
	230	k = pc->k;
	231	if (k + sizeof(short) > buflen) {
	232	#ifdef KERNEL
	233	int merr;
	234
	235	if (buflen != 0)
	236	return 0;
	237	A = m_xhalf((struct mbuf *)p, k, &merr);
	238	continue;
	239	#else
240	return 0;
241	#endif
242	}
243	A = EXTRACT_SHORT(&p[k]);
244	continue;
245
246	case BPF_LD\|BPF_B\|BPF_ABS:
247	k = pc->k;
248	if (k >= buflen) {
249	#ifdef KERNEL
250	register struct mbuf *m;
251
252	if (buflen != 0)
253	return 0;
254	m = (struct mbuf *)p;
255	MINDEX(m, k);
256	A = mtod(m, u_char *)[k];
257	continue;
258	#else
259	return 0;
260	#endif
261	}
262	A = p[k];
263	continue;
264
265	case BPF_LD\|BPF_W\|BPF_LEN:
266	A = wirelen;
267	continue;
268
269	case BPF_LDX\|BPF_W\|BPF_LEN:
270	X = wirelen;
271	continue;
272
273	case BPF_LD\|BPF_W\|BPF_IND:
274	k = X + pc->k;
275	if (k + sizeof(long) > buflen) {
276	#ifdef KERNEL
277	int merr;
278
279	if (buflen != 0)
280	return 0;
281	A = m_xword((struct mbuf *)p, k, &merr);
282	if (merr != 0)
283	return 0;
284	continue;
285	#else
286	return 0;
287	#endif
288	}
289	#ifdef BPF_ALIGN
290	if (((int)(p + k) & 3) != 0)
291	A = EXTRACT_LONG(&p[k]);
292	else
293	#endif
294	A = ntohl((long )(p + k));
295	continue;
296
297	case BPF_LD\|BPF_H\|BPF_IND:
298	k = X + pc->k;
299	if (k + sizeof(short) > buflen) {
300	#ifdef KERNEL
301	int merr;
302
303	if (buflen != 0)
304	return 0;
305	A = m_xhalf((struct mbuf *)p, k, &merr);
306	if (merr != 0)
307	return 0;
308	continue;
309	#else
310	return 0;
311	#endif
312	}
313	A = EXTRACT_SHORT(&p[k]);
314	continue;
315
316	case BPF_LD\|BPF_B\|BPF_IND:
317	k = X + pc->k;
318	if (k >= buflen) {
319	#ifdef KERNEL
320	register struct mbuf *m;
321
322	if (buflen != 0)
323	return 0;
324	m = (struct mbuf *)p;
325	MINDEX(m, k);
326	A = mtod(m, char *)[k];
327	continue;
328	#else
329	return 0;
330	#endif
331	}
332	A = p[k];
333	continue;
334
335	case BPF_LDX\|BPF_MSH\|BPF_B:
336	k = pc->k;
337	if (k >= buflen) {
338	#ifdef KERNEL
339	register struct mbuf *m;
340
341	if (buflen != 0)
342	return 0;
343	m = (struct mbuf *)p;
344	MINDEX(m, k);
345	X = (mtod(m, char *)[k] & 0xf) << 2;
346	continue;
347	#else
348	return 0;
349	#endif
350	}
351	X = (p[pc->k] & 0xf) << 2;
352	continue;
353
354	case BPF_LD\|BPF_IMM:
355	A = pc->k;
356	continue;
357
358	case BPF_LDX\|BPF_IMM:
359	X = pc->k;
360	continue;
361
362	case BPF_LD\|BPF_MEM:
363	A = mem[pc->k];
364	continue;
365
366	case BPF_LDX\|BPF_MEM:
367	X = mem[pc->k];
368	continue;
369
370	case BPF_ST:
371	mem[pc->k] = A;
372	continue;
373
374	case BPF_STX:
375	mem[pc->k] = X;
376	continue;
377
378	case BPF_JMP\|BPF_JA:
379	pc += pc->k;
380	continue;
381
382	case BPF_JMP\|BPF_JGT\|BPF_K:
383	pc += (A > pc->k) ? pc->jt : pc->jf;
384	continue;
385
386	case BPF_JMP\|BPF_JGE\|BPF_K:
387	pc += (A >= pc->k) ? pc->jt : pc->jf;
388	continue;
389
390	case BPF_JMP\|BPF_JEQ\|BPF_K:
391	pc += (A == pc->k) ? pc->jt : pc->jf;
392	continue;
393
394	case BPF_JMP\|BPF_JSET\|BPF_K:
395	pc += (A & pc->k) ? pc->jt : pc->jf;
396	continue;
397
398	case BPF_JMP\|BPF_JGT\|BPF_X:
399	pc += (A > X) ? pc->jt : pc->jf;
400	continue;
401
402	case BPF_JMP\|BPF_JGE\|BPF_X:
403	pc += (A >= X) ? pc->jt : pc->jf;
404	continue;
405
406	case BPF_JMP\|BPF_JEQ\|BPF_X:
407	pc += (A == X) ? pc->jt : pc->jf;
408	continue;
409
410	case BPF_JMP\|BPF_JSET\|BPF_X:
411	pc += (A & X) ? pc->jt : pc->jf;
412	continue;
413
414	case BPF_ALU\|BPF_ADD\|BPF_X:
415	A += X;
416	continue;
417
418	case BPF_ALU\|BPF_SUB\|BPF_X:
419	A -= X;
420	continue;
421
422	case BPF_ALU\|BPF_MUL\|BPF_X:
423	A *= X;
424	continue;
425
426	case BPF_ALU\|BPF_DIV\|BPF_X:
427	if (X == 0)
428	return 0;
429	A /= X;
430	continue;
431
432	case BPF_ALU\|BPF_AND\|BPF_X:
433	A &= X;
434	continue;
435
436	case BPF_ALU\|BPF_OR\|BPF_X:
437	A \|= X;
438	continue;
439
440	case BPF_ALU\|BPF_LSH\|BPF_X:
441	A <<= X;
442	continue;
443
444	case BPF_ALU\|BPF_RSH\|BPF_X:
445	A >>= X;
446	continue;
447
448	case BPF_ALU\|BPF_ADD\|BPF_K:
449	A += pc->k;
450	continue;
451
452	case BPF_ALU\|BPF_SUB\|BPF_K:
453	A -= pc->k;
454	continue;
455
456	case BPF_ALU\|BPF_MUL\|BPF_K:
457	A *= pc->k;
458	continue;
459
460	case BPF_ALU\|BPF_DIV\|BPF_K:
461	A /= pc->k;
462	continue;
463
464	case BPF_ALU\|BPF_AND\|BPF_K:
465	A &= pc->k;
466	continue;
467
468	case BPF_ALU\|BPF_OR\|BPF_K:
469	A \|= pc->k;
470	continue;
471
472	case BPF_ALU\|BPF_LSH\|BPF_K:
473	A <<= pc->k;
474	continue;
475
476	case BPF_ALU\|BPF_RSH\|BPF_K:
477	A >>= pc->k;
478	continue;
479
480	case BPF_ALU\|BPF_NEG:
481	A = -A;
482	continue;
483
484	case BPF_MISC\|BPF_TAX:
485	X = A;
486	continue;
487
488	case BPF_MISC\|BPF_TXA:
489	A = X;
490	continue;
491	}
492	}
493	}
494
495	#ifdef KERNEL
496	/*
497	* Return true if the 'fcode' is a valid filter program.
498	* The constraints are that each jump be forward and to a valid
499	* code. The code must terminate with either an accept or reject.
500	* 'valid' is an array for use by the routine (it must be at least
501	* 'len' bytes long).
502	*
503	* The kernel needs to be able to verify an application's filter code.
504	* Otherwise, a bogus program could easily crash the system.
505	*/
506	int
507	bpf_validate(f, len)
508	struct bpf_insn *f;
509	int len;
510	{
511	register int i;
512	register struct bpf_insn *p;
513
514	for (i = 0; i < len; ++i) {
515	/*
516	* Check that that jumps are forward, and within
517	* the code block.
518	*/
519	p = &f[i];
520	if (BPF_CLASS(p->code) == BPF_JMP) {
521	register int from = i + 1;
522
523	if (BPF_OP(p->code) == BPF_JA) {
524	if (from + p->k >= len)
525	return 0;
526	}
527	else if (from + p->jt >= len \|\| from + p->jf >= len)
528	return 0;
529	}
530	/*
531	* Check that memory operations use valid addresses.
532	*/
533	if ((BPF_CLASS(p->code) == BPF_ST \|\|
534	(BPF_CLASS(p->code) == BPF_LD &&
535	(p->code & 0xe0) == BPF_MEM)) &&
536	(p->k >= BPF_MEMWORDS \|\| p->k < 0))
537	return 0;
538	/*
539	* Check for constant division by 0.
540	*/
541	if (p->code == (BPF_ALU\|BPF_DIV\|BPF_K) && p->k == 0)
542	return 0;
543	}
544	return BPF_CLASS(f[len - 1].code) == BPF_RET;
545	}
546	#endif