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git://git.code.sf.net/p/xtables-addons/xtables-addons
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a51b16097b
This revision 1 of ipv4options makes it possible to match the presence or absence of any of the 32 possible IP options, either all or any of the options the user specified.
73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/*
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* xt_ipv4opts - Netfilter module to match IPv4 options
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* Copyright © Jan Engelhardt, 2009
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License; either
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* version 2 of the License, or any later version, as published by the
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* Free Software Foundation.
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*/
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#include <linux/ip.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/ip.h>
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#include "xt_ipv4options.h"
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#include "compat_xtables.h"
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static uint32_t ipv4options_rd(const uint8_t *data, int len)
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{
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uint32_t opts = 0;
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while (len >= 2) {
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opts |= 1 << (data[0] & 0x1F);
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len -= data[1];
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data += data[1];
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}
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return opts;
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}
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static bool ipv4options_mt(const struct sk_buff *skb,
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const struct xt_match_param *par)
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{
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const struct xt_ipv4options_mtinfo1 *info = par->matchinfo;
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const struct iphdr *iph = ip_hdr(skb);
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uint32_t opts = 0;
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uint16_t len = ip_hdrlen(skb) - sizeof(struct iphdr);
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if (len > 0)
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opts = ipv4options_rd((const void *)iph +
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sizeof(struct iphdr), len);
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opts ^= info->invert;
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opts &= info->map;
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return (info->flags & XT_V4OPTS_ANY) ? opts : opts == info->map;
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}
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static struct xt_match ipv4options_mt_reg __read_mostly = {
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.name = "ipv4options",
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.revision = 1,
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.family = NFPROTO_IPV4,
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.match = ipv4options_mt,
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.matchsize = XT_ALIGN(sizeof(struct xt_ipv4options_mtinfo1)),
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.me = THIS_MODULE,
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};
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static int __init ipv4options_mt_init(void)
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{
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return xt_register_match(&ipv4options_mt_reg);
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}
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static void __exit ipv4options_mt_exit(void)
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{
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xt_unregister_match(&ipv4options_mt_reg);
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}
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MODULE_DESCRIPTION("Xatblse: IPv4 option match");
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MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_ipv4options");
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module_init(ipv4options_mt_init);
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module_exit(ipv4options_mt_exit);
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