+/* 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
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