mirror of
git://git.code.sf.net/p/xtables-addons/xtables-addons
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84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/*
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* xt_ipv4opts - Xtables 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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switch (data[0]) {
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case IPOPT_END:
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return opts;
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case IPOPT_NOOP:
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--len;
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++data;
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continue;
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}
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if (data[1] < 2 || data[1] > len)
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return opts;
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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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struct xt_action_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 = 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 ");
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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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