Release 4.11 net/netfilter/xt_HL.c

/*
 * TTL modification target for IP tables
 * (C) 2000,2005 by Harald Welte <laforge@netfilter.org>
 *
 * Hop Limit modification target for ip6tables
 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <net/checksum.h>

#include <linux/netfilter/x_tables.h>
#include <linux/netfilter_ipv4/ipt_TTL.h>
#include <linux/netfilter_ipv6/ip6t_HL.h>

MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
MODULE_DESCRIPTION("Xtables: Hoplimit/TTL Limit field modification target");
MODULE_LICENSE("GPL");


static unsigned int

ttl_tg(struct sk_buff *skb, const struct xt_action_param *par)
{
	struct iphdr *iph;
	const struct ipt_TTL_info *info = par->targinfo;
	int new_ttl;

	if (!skb_make_writable(skb, skb->len))
		return NF_DROP;

	iph = ip_hdr(skb);

	switch (info->mode) {
	case IPT_TTL_SET:
		new_ttl = info->ttl;
		break;
	case IPT_TTL_INC:
		new_ttl = iph->ttl + info->ttl;
		if (new_ttl > 255)
			new_ttl = 255;
		break;
	case IPT_TTL_DEC:
		new_ttl = iph->ttl - info->ttl;
		if (new_ttl < 0)
			new_ttl = 0;
		break;
	default:
		new_ttl = iph->ttl;
		break;
	}

	if (new_ttl != iph->ttl) {
		csum_replace2(&iph->check, htons(iph->ttl << 8),
					   htons(new_ttl << 8));
		iph->ttl = new_ttl;
	}

	return XT_CONTINUE;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Harald Welte
144
82.29%
1
8.33%
Patrick McHardy
12
6.86%
3
25.00%
Jan Engelhardt
6
3.43%
4
33.33%
Al Viro
6
3.43%
2
16.67%
Herbert Xu
4
2.29%
1
8.33%
Arnaldo Carvalho de Melo
3
1.71%
1
8.33%
Total
175
100.00%
12
100.00%


static unsigned int

hl_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
	struct ipv6hdr *ip6h;
	const struct ip6t_HL_info *info = par->targinfo;
	int new_hl;

	if (!skb_make_writable(skb, skb->len))
		return NF_DROP;

	ip6h = ipv6_hdr(skb);

	switch (info->mode) {
	case IP6T_HL_SET:
		new_hl = info->hop_limit;
		break;
	case IP6T_HL_INC:
		new_hl = ip6h->hop_limit + info->hop_limit;
		if (new_hl > 255)
			new_hl = 255;
		break;
	case IP6T_HL_DEC:
		new_hl = ip6h->hop_limit - info->hop_limit;
		if (new_hl < 0)
			new_hl = 0;
		break;
	default:
		new_hl = ip6h->hop_limit;
		break;
	}

	ip6h->hop_limit = new_hl;

	return XT_CONTINUE;
}

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2
100.00%



static int ttl_tg_check(const struct xt_tgchk_param *par)
{
	const struct ipt_TTL_info *info = par->targinfo;

	if (info->mode > IPT_TTL_MAXMODE) {
		pr_info("TTL: invalid or unknown mode %u\n", info->mode);
		return -EINVAL;
	}
	if (info->mode != IPT_TTL_SET && info->ttl == 0)
		return -EINVAL;
	return 0;
}

Contributors
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CommitProp
Harald Welte
50
75.76%
1
11.11%
Jan Engelhardt
14
21.21%
7
77.78%
Patrick McHardy
2
3.03%
1
11.11%
Total
66
100.00%
9
100.00%



static int hl_tg6_check(const struct xt_tgchk_param *par)
{
	const struct ip6t_HL_info *info = par->targinfo;

	if (info->mode > IP6T_HL_MAXMODE) {
		pr_info("invalid or unknown mode %u\n", info->mode);
		return -EINVAL;
	}
	if (info->mode != IP6T_HL_SET && info->hop_limit == 0) {
		pr_info("increment/decrement does not "
			"make sense with value 0\n");
		return -EINVAL;
	}
	return 0;
}

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74
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4
100.00%


static struct xt_target hl_tg_reg[] __read_mostly = {
	{
		.name       = "TTL",
		.revision   = 0,
		.family     = NFPROTO_IPV4,
		.target     = ttl_tg,
		.targetsize = sizeof(struct ipt_TTL_info),
		.table      = "mangle",
		.checkentry = ttl_tg_check,
		.me         = THIS_MODULE,
        },
	{
		.name       = "HL",
		.revision   = 0,
		.family     = NFPROTO_IPV6,
		.target     = hl_tg6,
		.targetsize = sizeof(struct ip6t_HL_info),
		.table      = "mangle",
		.checkentry = hl_tg6_check,
		.me         = THIS_MODULE,
        },
};



static int __init hl_tg_init(void)
{
	return xt_register_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
}

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CommitProp
Harald Welte
12
60.00%
1
50.00%
Jan Engelhardt
8
40.00%
1
50.00%
Total
20
100.00%
2
100.00%



static void __exit hl_tg_exit(void)
{
	xt_unregister_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
}

Contributors
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CommitProp
Harald Welte
11
57.89%
1
50.00%
Jan Engelhardt
8
42.11%
1
50.00%
Total
19
100.00%
2
100.00%


module_init(hl_tg_init);

module_exit(hl_tg_exit);
MODULE_ALIAS("ipt_TTL");
MODULE_ALIAS("ip6t_HL");
Overall Contributors
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CommitProp
Jan Engelhardt
347
51.95%
12
52.17%
Harald Welte
279
41.77%
1
4.35%
Patrick McHardy
29
4.34%
6
26.09%
Al Viro
6
0.90%
2
8.70%
Herbert Xu
4
0.60%
1
4.35%
Arnaldo Carvalho de Melo
3
0.45%
1
4.35%
Total
668
100.00%
23
100.00%
Directory: net/netfilter

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