57e22627f9
Update libpcap from 1.9.0 to 1.9.1. MFC after: 2 weeks
549 lines
12 KiB
C
549 lines
12 KiB
C
/*-
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* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from the Stanford/CMU enet packet filter,
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* (net/enet.c) distributed as part of 4.3BSD, and code contributed
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* to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
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* Berkeley Laboratory.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)bpf.c 7.5 (Berkeley) 7/15/91
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <pcap/pcap-inttypes.h>
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#include "pcap-types.h"
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#ifndef _WIN32
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#endif /* _WIN32 */
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#include <pcap-int.h>
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#include <stdlib.h>
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#define int32 bpf_int32
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#define u_int32 bpf_u_int32
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#ifndef LBL_ALIGN
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/*
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* XXX - IA-64? If not, this probably won't work on Win64 IA-64
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* systems, unless LBL_ALIGN is defined elsewhere for them.
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* XXX - SuperH? If not, this probably won't work on WinCE SuperH
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* systems, unless LBL_ALIGN is defined elsewhere for them.
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*/
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#if defined(sparc) || defined(__sparc__) || defined(mips) || \
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defined(ibm032) || defined(__alpha) || defined(__hpux) || \
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defined(__arm__)
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#define LBL_ALIGN
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#endif
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#endif
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#ifndef LBL_ALIGN
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#ifndef _WIN32
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#include <netinet/in.h>
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#endif
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#define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
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#define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p))
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#else
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#define EXTRACT_SHORT(p)\
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((u_short)\
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((u_short)*((u_char *)p+0)<<8|\
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(u_short)*((u_char *)p+1)<<0))
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#define EXTRACT_LONG(p)\
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((u_int32)*((u_char *)p+0)<<24|\
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(u_int32)*((u_char *)p+1)<<16|\
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(u_int32)*((u_char *)p+2)<<8|\
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(u_int32)*((u_char *)p+3)<<0)
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#endif
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#ifdef __linux__
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#include <linux/types.h>
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#include <linux/if_packet.h>
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#include <linux/filter.h>
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#endif
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enum {
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BPF_S_ANC_NONE,
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BPF_S_ANC_VLAN_TAG,
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BPF_S_ANC_VLAN_TAG_PRESENT,
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};
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/*
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* Execute the filter program starting at pc on the packet p
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* wirelen is the length of the original packet
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* buflen is the amount of data present
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* aux_data is auxiliary data, currently used only when interpreting
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* filters intended for the Linux kernel in cases where the kernel
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* rejects the filter; it contains VLAN tag information
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* For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0,
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* in all other cases, p is a pointer to a buffer and buflen is its size.
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*
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* Thanks to Ani Sinha <ani@arista.com> for providing initial implementation
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*/
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u_int
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bpf_filter_with_aux_data(const struct bpf_insn *pc, const u_char *p,
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u_int wirelen, u_int buflen, const struct bpf_aux_data *aux_data)
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{
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register u_int32 A, X;
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register bpf_u_int32 k;
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u_int32 mem[BPF_MEMWORDS];
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if (pc == 0)
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/*
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* No filter means accept all.
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*/
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return (u_int)-1;
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A = 0;
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X = 0;
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--pc;
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for (;;) {
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++pc;
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switch (pc->code) {
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default:
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abort();
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case BPF_RET|BPF_K:
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return (u_int)pc->k;
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case BPF_RET|BPF_A:
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return (u_int)A;
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case BPF_LD|BPF_W|BPF_ABS:
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k = pc->k;
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if (k > buflen || sizeof(int32_t) > buflen - k) {
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return 0;
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}
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A = EXTRACT_LONG(&p[k]);
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continue;
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case BPF_LD|BPF_H|BPF_ABS:
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k = pc->k;
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if (k > buflen || sizeof(int16_t) > buflen - k) {
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return 0;
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}
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A = EXTRACT_SHORT(&p[k]);
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continue;
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case BPF_LD|BPF_B|BPF_ABS:
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switch (pc->k) {
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#if defined(SKF_AD_VLAN_TAG_PRESENT)
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case SKF_AD_OFF + SKF_AD_VLAN_TAG:
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if (!aux_data)
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return 0;
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A = aux_data->vlan_tag;
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break;
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case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
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if (!aux_data)
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return 0;
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A = aux_data->vlan_tag_present;
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break;
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#endif
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default:
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k = pc->k;
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if (k >= buflen) {
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return 0;
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}
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A = p[k];
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break;
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}
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continue;
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case BPF_LD|BPF_W|BPF_LEN:
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A = wirelen;
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continue;
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case BPF_LDX|BPF_W|BPF_LEN:
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X = wirelen;
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continue;
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case BPF_LD|BPF_W|BPF_IND:
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k = X + pc->k;
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if (pc->k > buflen || X > buflen - pc->k ||
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sizeof(int32_t) > buflen - k) {
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return 0;
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}
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A = EXTRACT_LONG(&p[k]);
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continue;
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case BPF_LD|BPF_H|BPF_IND:
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k = X + pc->k;
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if (X > buflen || pc->k > buflen - X ||
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sizeof(int16_t) > buflen - k) {
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return 0;
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}
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A = EXTRACT_SHORT(&p[k]);
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continue;
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case BPF_LD|BPF_B|BPF_IND:
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k = X + pc->k;
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if (pc->k >= buflen || X >= buflen - pc->k) {
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return 0;
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}
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A = p[k];
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continue;
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case BPF_LDX|BPF_MSH|BPF_B:
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k = pc->k;
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if (k >= buflen) {
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return 0;
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}
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X = (p[pc->k] & 0xf) << 2;
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continue;
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case BPF_LD|BPF_IMM:
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A = pc->k;
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continue;
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case BPF_LDX|BPF_IMM:
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X = pc->k;
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continue;
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case BPF_LD|BPF_MEM:
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A = mem[pc->k];
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continue;
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case BPF_LDX|BPF_MEM:
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X = mem[pc->k];
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continue;
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case BPF_ST:
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mem[pc->k] = A;
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continue;
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case BPF_STX:
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mem[pc->k] = X;
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continue;
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case BPF_JMP|BPF_JA:
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/*
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* XXX - we currently implement "ip6 protochain"
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* with backward jumps, so sign-extend pc->k.
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*/
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pc += (bpf_int32)pc->k;
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continue;
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case BPF_JMP|BPF_JGT|BPF_K:
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pc += (A > pc->k) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JGE|BPF_K:
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pc += (A >= pc->k) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JEQ|BPF_K:
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pc += (A == pc->k) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JSET|BPF_K:
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pc += (A & pc->k) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JGT|BPF_X:
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pc += (A > X) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JGE|BPF_X:
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pc += (A >= X) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JEQ|BPF_X:
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pc += (A == X) ? pc->jt : pc->jf;
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continue;
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case BPF_JMP|BPF_JSET|BPF_X:
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pc += (A & X) ? pc->jt : pc->jf;
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continue;
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case BPF_ALU|BPF_ADD|BPF_X:
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A += X;
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continue;
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case BPF_ALU|BPF_SUB|BPF_X:
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A -= X;
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continue;
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case BPF_ALU|BPF_MUL|BPF_X:
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A *= X;
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continue;
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case BPF_ALU|BPF_DIV|BPF_X:
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if (X == 0)
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return 0;
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A /= X;
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continue;
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case BPF_ALU|BPF_MOD|BPF_X:
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if (X == 0)
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return 0;
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A %= X;
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continue;
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case BPF_ALU|BPF_AND|BPF_X:
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A &= X;
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continue;
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case BPF_ALU|BPF_OR|BPF_X:
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A |= X;
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continue;
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case BPF_ALU|BPF_XOR|BPF_X:
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A ^= X;
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continue;
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case BPF_ALU|BPF_LSH|BPF_X:
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if (X < 32)
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A <<= X;
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else
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A = 0;
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continue;
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case BPF_ALU|BPF_RSH|BPF_X:
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if (X < 32)
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A >>= X;
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else
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A = 0;
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continue;
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case BPF_ALU|BPF_ADD|BPF_K:
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A += pc->k;
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continue;
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case BPF_ALU|BPF_SUB|BPF_K:
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A -= pc->k;
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continue;
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case BPF_ALU|BPF_MUL|BPF_K:
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A *= pc->k;
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continue;
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case BPF_ALU|BPF_DIV|BPF_K:
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A /= pc->k;
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continue;
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case BPF_ALU|BPF_MOD|BPF_K:
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A %= pc->k;
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continue;
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case BPF_ALU|BPF_AND|BPF_K:
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A &= pc->k;
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continue;
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case BPF_ALU|BPF_OR|BPF_K:
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A |= pc->k;
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continue;
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case BPF_ALU|BPF_XOR|BPF_K:
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A ^= pc->k;
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continue;
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case BPF_ALU|BPF_LSH|BPF_K:
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A <<= pc->k;
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continue;
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case BPF_ALU|BPF_RSH|BPF_K:
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A >>= pc->k;
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continue;
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case BPF_ALU|BPF_NEG:
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/*
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* Most BPF arithmetic is unsigned, but negation
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* can't be unsigned; respecify it as subtracting
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* the accumulator from 0U, so that 1) we don't
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* get compiler warnings about negating an unsigned
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* value and 2) don't get UBSan warnings about
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* the result of negating 0x80000000 being undefined.
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*/
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A = (0U - A);
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continue;
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case BPF_MISC|BPF_TAX:
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X = A;
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continue;
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case BPF_MISC|BPF_TXA:
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A = X;
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continue;
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}
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}
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}
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u_int
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bpf_filter(const struct bpf_insn *pc, const u_char *p, u_int wirelen,
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u_int buflen)
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{
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return bpf_filter_with_aux_data(pc, p, wirelen, buflen, NULL);
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}
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/*
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* Return true if the 'fcode' is a valid filter program.
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* The constraints are that each jump be forward and to a valid
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* code, that memory accesses are within valid ranges (to the
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* extent that this can be checked statically; loads of packet
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* data have to be, and are, also checked at run time), and that
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* the code terminates with either an accept or reject.
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*
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* The kernel needs to be able to verify an application's filter code.
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* Otherwise, a bogus program could easily crash the system.
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*/
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int
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bpf_validate(const struct bpf_insn *f, int len)
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{
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u_int i, from;
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const struct bpf_insn *p;
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if (len < 1)
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return 0;
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for (i = 0; i < (u_int)len; ++i) {
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p = &f[i];
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switch (BPF_CLASS(p->code)) {
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/*
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* Check that memory operations use valid addresses.
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*/
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case BPF_LD:
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case BPF_LDX:
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switch (BPF_MODE(p->code)) {
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case BPF_IMM:
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break;
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case BPF_ABS:
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case BPF_IND:
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case BPF_MSH:
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/*
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* There's no maximum packet data size
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* in userland. The runtime packet length
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* check suffices.
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*/
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break;
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case BPF_MEM:
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if (p->k >= BPF_MEMWORDS)
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return 0;
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break;
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case BPF_LEN:
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break;
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default:
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return 0;
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}
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break;
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case BPF_ST:
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case BPF_STX:
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if (p->k >= BPF_MEMWORDS)
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return 0;
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break;
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case BPF_ALU:
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switch (BPF_OP(p->code)) {
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case BPF_ADD:
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case BPF_SUB:
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case BPF_MUL:
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case BPF_OR:
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case BPF_AND:
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case BPF_XOR:
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case BPF_LSH:
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case BPF_RSH:
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case BPF_NEG:
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break;
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case BPF_DIV:
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case BPF_MOD:
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/*
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* Check for constant division or modulus
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* by 0.
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*/
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if (BPF_SRC(p->code) == BPF_K && p->k == 0)
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return 0;
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break;
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default:
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return 0;
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}
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break;
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case BPF_JMP:
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/*
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* Check that jumps are within the code block,
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* and that unconditional branches don't go
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* backwards as a result of an overflow.
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* Unconditional branches have a 32-bit offset,
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* so they could overflow; we check to make
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* sure they don't. Conditional branches have
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* an 8-bit offset, and the from address is <=
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* BPF_MAXINSNS, and we assume that BPF_MAXINSNS
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* is sufficiently small that adding 255 to it
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* won't overflow.
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*
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* We know that len is <= BPF_MAXINSNS, and we
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* assume that BPF_MAXINSNS is < the maximum size
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* of a u_int, so that i + 1 doesn't overflow.
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*
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* For userland, we don't know that the from
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* or len are <= BPF_MAXINSNS, but we know that
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* from <= len, and, except on a 64-bit system,
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* it's unlikely that len, if it truly reflects
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* the size of the program we've been handed,
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* will be anywhere near the maximum size of
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* a u_int. We also don't check for backward
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* branches, as we currently support them in
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* userland for the protochain operation.
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*/
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from = i + 1;
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switch (BPF_OP(p->code)) {
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case BPF_JA:
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if (from + p->k >= (u_int)len)
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return 0;
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break;
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case BPF_JEQ:
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case BPF_JGT:
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case BPF_JGE:
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case BPF_JSET:
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if (from + p->jt >= (u_int)len || from + p->jf >= (u_int)len)
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return 0;
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break;
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default:
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return 0;
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}
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break;
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case BPF_RET:
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break;
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case BPF_MISC:
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break;
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default:
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return 0;
|
|
}
|
|
}
|
|
return BPF_CLASS(f[len - 1].code) == BPF_RET;
|
|
}
|