cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

xt_HL.c (3464B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * TTL modification target for IP tables
      4 * (C) 2000,2005 by Harald Welte <laforge@netfilter.org>
      5 *
      6 * Hop Limit modification target for ip6tables
      7 * Maciej Soltysiak <solt@dns.toxicfilms.tv>
      8 */
      9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
     10#include <linux/module.h>
     11#include <linux/skbuff.h>
     12#include <linux/ip.h>
     13#include <linux/ipv6.h>
     14#include <net/checksum.h>
     15
     16#include <linux/netfilter/x_tables.h>
     17#include <linux/netfilter_ipv4/ipt_TTL.h>
     18#include <linux/netfilter_ipv6/ip6t_HL.h>
     19
     20MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
     21MODULE_AUTHOR("Maciej Soltysiak <solt@dns.toxicfilms.tv>");
     22MODULE_DESCRIPTION("Xtables: Hoplimit/TTL Limit field modification target");
     23MODULE_LICENSE("GPL");
     24
     25static unsigned int
     26ttl_tg(struct sk_buff *skb, const struct xt_action_param *par)
     27{
     28	struct iphdr *iph;
     29	const struct ipt_TTL_info *info = par->targinfo;
     30	int new_ttl;
     31
     32	if (skb_ensure_writable(skb, sizeof(*iph)))
     33		return NF_DROP;
     34
     35	iph = ip_hdr(skb);
     36
     37	switch (info->mode) {
     38	case IPT_TTL_SET:
     39		new_ttl = info->ttl;
     40		break;
     41	case IPT_TTL_INC:
     42		new_ttl = iph->ttl + info->ttl;
     43		if (new_ttl > 255)
     44			new_ttl = 255;
     45		break;
     46	case IPT_TTL_DEC:
     47		new_ttl = iph->ttl - info->ttl;
     48		if (new_ttl < 0)
     49			new_ttl = 0;
     50		break;
     51	default:
     52		new_ttl = iph->ttl;
     53		break;
     54	}
     55
     56	if (new_ttl != iph->ttl) {
     57		csum_replace2(&iph->check, htons(iph->ttl << 8),
     58					   htons(new_ttl << 8));
     59		iph->ttl = new_ttl;
     60	}
     61
     62	return XT_CONTINUE;
     63}
     64
     65static unsigned int
     66hl_tg6(struct sk_buff *skb, const struct xt_action_param *par)
     67{
     68	struct ipv6hdr *ip6h;
     69	const struct ip6t_HL_info *info = par->targinfo;
     70	int new_hl;
     71
     72	if (skb_ensure_writable(skb, sizeof(*ip6h)))
     73		return NF_DROP;
     74
     75	ip6h = ipv6_hdr(skb);
     76
     77	switch (info->mode) {
     78	case IP6T_HL_SET:
     79		new_hl = info->hop_limit;
     80		break;
     81	case IP6T_HL_INC:
     82		new_hl = ip6h->hop_limit + info->hop_limit;
     83		if (new_hl > 255)
     84			new_hl = 255;
     85		break;
     86	case IP6T_HL_DEC:
     87		new_hl = ip6h->hop_limit - info->hop_limit;
     88		if (new_hl < 0)
     89			new_hl = 0;
     90		break;
     91	default:
     92		new_hl = ip6h->hop_limit;
     93		break;
     94	}
     95
     96	ip6h->hop_limit = new_hl;
     97
     98	return XT_CONTINUE;
     99}
    100
    101static int ttl_tg_check(const struct xt_tgchk_param *par)
    102{
    103	const struct ipt_TTL_info *info = par->targinfo;
    104
    105	if (info->mode > IPT_TTL_MAXMODE)
    106		return -EINVAL;
    107	if (info->mode != IPT_TTL_SET && info->ttl == 0)
    108		return -EINVAL;
    109	return 0;
    110}
    111
    112static int hl_tg6_check(const struct xt_tgchk_param *par)
    113{
    114	const struct ip6t_HL_info *info = par->targinfo;
    115
    116	if (info->mode > IP6T_HL_MAXMODE)
    117		return -EINVAL;
    118	if (info->mode != IP6T_HL_SET && info->hop_limit == 0)
    119		return -EINVAL;
    120	return 0;
    121}
    122
    123static struct xt_target hl_tg_reg[] __read_mostly = {
    124	{
    125		.name       = "TTL",
    126		.revision   = 0,
    127		.family     = NFPROTO_IPV4,
    128		.target     = ttl_tg,
    129		.targetsize = sizeof(struct ipt_TTL_info),
    130		.table      = "mangle",
    131		.checkentry = ttl_tg_check,
    132		.me         = THIS_MODULE,
    133	},
    134	{
    135		.name       = "HL",
    136		.revision   = 0,
    137		.family     = NFPROTO_IPV6,
    138		.target     = hl_tg6,
    139		.targetsize = sizeof(struct ip6t_HL_info),
    140		.table      = "mangle",
    141		.checkentry = hl_tg6_check,
    142		.me         = THIS_MODULE,
    143	},
    144};
    145
    146static int __init hl_tg_init(void)
    147{
    148	return xt_register_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
    149}
    150
    151static void __exit hl_tg_exit(void)
    152{
    153	xt_unregister_targets(hl_tg_reg, ARRAY_SIZE(hl_tg_reg));
    154}
    155
    156module_init(hl_tg_init);
    157module_exit(hl_tg_exit);
    158MODULE_ALIAS("ipt_TTL");
    159MODULE_ALIAS("ip6t_HL");