X-Git-Url: https://git.ozlabs.org/?a=blobdiff_plain;f=modules%2Fbpf_filter.c;fp=modules%2Fbpf_filter.c;h=f47ed2cf269b52f932632f08b6535e51ff5030ac;hb=ce773fec27f115f665ac7d9630eeb5f5484d5eb7;hp=0000000000000000000000000000000000000000;hpb=31785621fd2fac92f48b0f826bac6d2c97a536c7;p=ppp.git

diff --git a/modules/bpf_filter.c b/modules/bpf_filter.c
new file mode 100644
index 0000000..f47ed2c
--- /dev/null
+++ b/modules/bpf_filter.c
@@ -0,0 +1,542 @@
+/*	From NetBSD: bpf_filter.c,v 1.12 1996/02/13 22:00:00 christos Exp */
+
+/*
+ * Copyright (c) 1990, 1991, 1992, 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.
+ *
+ *	From: @(#)bpf_filter.c	8.1 (Berkeley) 6/10/93
+ *	$Id: bpf_filter.c,v 1.1 1996/04/04 02:45:45 paulus Exp $
+ */
+
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stream.h>
+#include <net/ppp_defs.h>
+#include "ppp_mod.h"
+
+#ifdef SVR4
+#ifndef __GNUC__
+#include <sys/byteorder.h>	/* for ntohl, etc. */
+#else
+/* make sure we don't get the gnu "fixed" one! */
+#include "/usr/include/sys/byteorder.h"
+#endif
+#endif
+
+#ifdef OSF1
+#include <net/net_globals.h>
+#endif
+#include <netinet/in.h>
+
+#ifdef AIX4
+#define _NETINET_IN_SYSTM_H_
+typedef u_long  n_long;
+#else
+#include <netinet/in_systm.h>
+#endif
+
+#if !(defined(__i386__) || defined(__m68k__))	/* any others? */
+#define BPF_ALIGN
+#endif
+
+#ifndef BPF_ALIGN
+#define EXTRACT_SHORT(p)	((ushort)ntohs(*(ushort *)p))
+#define EXTRACT_LONG(p)		(ntohl(*(uint *)p))
+#else
+#define EXTRACT_SHORT(p)\
+	((ushort)\
+		((ushort)*((u_char *)p+0)<<8|\
+		 (ushort)*((u_char *)p+1)<<0))
+#define EXTRACT_LONG(p)\
+		((uint)*((u_char *)p+0)<<24|\
+		 (uint)*((u_char *)p+1)<<16|\
+		 (uint)*((u_char *)p+2)<<8|\
+		 (uint)*((u_char *)p+3)<<0)
+#endif
+
+#ifdef _KERNEL
+#define MINDEX(len, m, k) \
+{ \
+	len = m->b_wptr - m->b_rptr; \
+	while (k >= len) { \
+		k -= len; \
+		m = m->b_cont; \
+		if (m == 0) \
+			return 0; \
+		len = m->b_wptr - m->b_rptr; \
+	} \
+}
+
+static int m_xword __P((mblk_t *, int, int *));
+static int m_xhalf __P((mblk_t *, int, int *));
+
+static int
+m_xword(m, k, err)
+	register mblk_t *m;
+	register int k, *err;
+{
+	register int len;
+	register uchar_t *cp, *np;
+	register mblk_t *m0;
+
+	MINDEX(len, m, k);
+	cp = m->b_rptr + k;
+	if (len - k >= 4) {
+		*err = 0;
+		return EXTRACT_LONG(cp);
+	}
+	m0 = m->b_cont;
+	if (m0 == 0 || m0->b_wptr - m0->b_rptr + len - k < 4)
+		goto bad;
+	*err = 0;
+	np = m0->b_rptr;
+	switch (len - k) {
+
+	case 1:
+		return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];
+
+	case 2:
+		return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];
+
+	default:
+		return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | np[0];
+	}
+    bad:
+	*err = 1;
+	return 0;
+}
+
+static int
+m_xhalf(m, k, err)
+	register mblk_t *m;
+	register int k, *err;
+{
+	register int len;
+	register uchar_t *cp;
+	register mblk_t *m0;
+
+	MINDEX(len, m, k);
+	cp = m->b_rptr + k;
+	if (len - k >= 2) {
+		*err = 0;
+		return EXTRACT_SHORT(cp);
+	}
+	m0 = m->b_cont;
+	if (m0 == 0)
+		goto bad;
+	*err = 0;
+	return (cp[0] << 8) | m0->b_rptr[0];
+ bad:
+	*err = 1;
+	return 0;
+}
+#endif
+
+#include <net/bpf.h>
+
+/*
+ * 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
+ */
+uint
+bpf_filter(pc, p, wirelen, buflen)
+	register struct bpf_insn *pc;
+	register uchar_t *p;
+	uint wirelen;
+	register uint buflen;
+{
+	register uint A = 0, X = 0;
+	register int k;
+	int mem[BPF_MEMWORDS];
+
+	if (pc == 0)
+		/*
+		 * No filter means accept all.
+		 */
+		return (uint)-1;
+	--pc;
+	while (1) {
+		++pc;
+		switch (pc->code) {
+
+		default:
+#ifdef _KERNEL
+			return 0;
+#else
+			abort();
+#endif			
+		case BPF_RET|BPF_K:
+			return (uint)pc->k;
+
+		case BPF_RET|BPF_A:
+			return (uint)A;
+
+		case BPF_LD|BPF_W|BPF_ABS:
+			k = pc->k;
+			if (k + sizeof(int) > buflen) {
+#ifdef _KERNEL
+				int merr;
+
+				if (buflen != 0)
+					return 0;
+				A = m_xword((mblk_t *)p, k, &merr);
+				if (merr != 0)
+					return 0;
+				continue;
+#else
+				return 0;
+#endif
+			}
+			A = EXTRACT_LONG(&p[k]);
+			continue;
+
+		case BPF_LD|BPF_H|BPF_ABS:
+			k = pc->k;
+			if (k + sizeof(short int) > buflen) {
+#ifdef _KERNEL
+				int merr;
+
+				if (buflen != 0)
+					return 0;
+				A = m_xhalf((mblk_t *)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 mblk_t *m;
+				register int len;
+
+				if (buflen != 0)
+					return 0;
+				m = (mblk_t *)p;
+				MINDEX(len, m, k);
+				A = m->b_rptr[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(int) > buflen) {
+#ifdef _KERNEL
+				int merr;
+
+				if (buflen != 0)
+					return 0;
+				A = m_xword((mblk_t *)p, k, &merr);
+				if (merr != 0)
+					return 0;
+				continue;
+#else
+				return 0;
+#endif
+			}
+			A = EXTRACT_LONG(&p[k]);
+			continue;
+
+		case BPF_LD|BPF_H|BPF_IND:
+			k = X + pc->k;
+			if (k + sizeof(short int) > buflen) {
+#ifdef _KERNEL
+				int merr;
+
+				if (buflen != 0)
+					return 0;
+				A = m_xhalf((mblk_t *)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 mblk_t *m;
+				register int len;
+
+				if (buflen != 0)
+					return 0;
+				m = (mblk_t *)p;
+				MINDEX(len, m, k);
+				A = m->b_rptr[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 mblk_t *m;
+				register int len;
+
+				if (buflen != 0)
+					return 0;
+				m = (mblk_t *)p;
+				MINDEX(len, m, k);
+				X = (m->b_rptr[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