cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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xt_ecn.c (4400B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Xtables module for matching the value of the IPv4/IPv6 and TCP ECN bits
      4 *
      5 * (C) 2002 by Harald Welte <laforge@gnumonks.org>
      6 * (C) 2011 Patrick McHardy <kaber@trash.net>
      7 */
      8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      9#include <linux/in.h>
     10#include <linux/ip.h>
     11#include <net/ip.h>
     12#include <linux/module.h>
     13#include <linux/skbuff.h>
     14#include <linux/tcp.h>
     15
     16#include <linux/netfilter/x_tables.h>
     17#include <linux/netfilter/xt_ecn.h>
     18#include <linux/netfilter_ipv4/ip_tables.h>
     19#include <linux/netfilter_ipv6/ip6_tables.h>
     20
     21MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
     22MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match");
     23MODULE_LICENSE("GPL");
     24MODULE_ALIAS("ipt_ecn");
     25MODULE_ALIAS("ip6t_ecn");
     26
     27static bool match_tcp(const struct sk_buff *skb, struct xt_action_param *par)
     28{
     29	const struct xt_ecn_info *einfo = par->matchinfo;
     30	struct tcphdr _tcph;
     31	const struct tcphdr *th;
     32
     33	/* In practice, TCP match does this, so can't fail.  But let's
     34	 * be good citizens.
     35	 */
     36	th = skb_header_pointer(skb, par->thoff, sizeof(_tcph), &_tcph);
     37	if (th == NULL)
     38		return false;
     39
     40	if (einfo->operation & XT_ECN_OP_MATCH_ECE) {
     41		if (einfo->invert & XT_ECN_OP_MATCH_ECE) {
     42			if (th->ece == 1)
     43				return false;
     44		} else {
     45			if (th->ece == 0)
     46				return false;
     47		}
     48	}
     49
     50	if (einfo->operation & XT_ECN_OP_MATCH_CWR) {
     51		if (einfo->invert & XT_ECN_OP_MATCH_CWR) {
     52			if (th->cwr == 1)
     53				return false;
     54		} else {
     55			if (th->cwr == 0)
     56				return false;
     57		}
     58	}
     59
     60	return true;
     61}
     62
     63static inline bool match_ip(const struct sk_buff *skb,
     64			    const struct xt_ecn_info *einfo)
     65{
     66	return ((ip_hdr(skb)->tos & XT_ECN_IP_MASK) == einfo->ip_ect) ^
     67	       !!(einfo->invert & XT_ECN_OP_MATCH_IP);
     68}
     69
     70static bool ecn_mt4(const struct sk_buff *skb, struct xt_action_param *par)
     71{
     72	const struct xt_ecn_info *info = par->matchinfo;
     73
     74	if (info->operation & XT_ECN_OP_MATCH_IP && !match_ip(skb, info))
     75		return false;
     76
     77	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&
     78	    !match_tcp(skb, par))
     79		return false;
     80
     81	return true;
     82}
     83
     84static int ecn_mt_check4(const struct xt_mtchk_param *par)
     85{
     86	const struct xt_ecn_info *info = par->matchinfo;
     87	const struct ipt_ip *ip = par->entryinfo;
     88
     89	if (info->operation & XT_ECN_OP_MATCH_MASK)
     90		return -EINVAL;
     91
     92	if (info->invert & XT_ECN_OP_MATCH_MASK)
     93		return -EINVAL;
     94
     95	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&
     96	    (ip->proto != IPPROTO_TCP || ip->invflags & IPT_INV_PROTO)) {
     97		pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n");
     98		return -EINVAL;
     99	}
    100
    101	return 0;
    102}
    103
    104static inline bool match_ipv6(const struct sk_buff *skb,
    105			      const struct xt_ecn_info *einfo)
    106{
    107	return (((ipv6_hdr(skb)->flow_lbl[0] >> 4) & XT_ECN_IP_MASK) ==
    108	        einfo->ip_ect) ^
    109	       !!(einfo->invert & XT_ECN_OP_MATCH_IP);
    110}
    111
    112static bool ecn_mt6(const struct sk_buff *skb, struct xt_action_param *par)
    113{
    114	const struct xt_ecn_info *info = par->matchinfo;
    115
    116	if (info->operation & XT_ECN_OP_MATCH_IP && !match_ipv6(skb, info))
    117		return false;
    118
    119	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&
    120	    !match_tcp(skb, par))
    121		return false;
    122
    123	return true;
    124}
    125
    126static int ecn_mt_check6(const struct xt_mtchk_param *par)
    127{
    128	const struct xt_ecn_info *info = par->matchinfo;
    129	const struct ip6t_ip6 *ip = par->entryinfo;
    130
    131	if (info->operation & XT_ECN_OP_MATCH_MASK)
    132		return -EINVAL;
    133
    134	if (info->invert & XT_ECN_OP_MATCH_MASK)
    135		return -EINVAL;
    136
    137	if (info->operation & (XT_ECN_OP_MATCH_ECE | XT_ECN_OP_MATCH_CWR) &&
    138	    (ip->proto != IPPROTO_TCP || ip->invflags & IP6T_INV_PROTO)) {
    139		pr_info_ratelimited("cannot match TCP bits for non-tcp packets\n");
    140		return -EINVAL;
    141	}
    142
    143	return 0;
    144}
    145
    146static struct xt_match ecn_mt_reg[] __read_mostly = {
    147	{
    148		.name		= "ecn",
    149		.family		= NFPROTO_IPV4,
    150		.match		= ecn_mt4,
    151		.matchsize	= sizeof(struct xt_ecn_info),
    152		.checkentry	= ecn_mt_check4,
    153		.me		= THIS_MODULE,
    154	},
    155	{
    156		.name		= "ecn",
    157		.family		= NFPROTO_IPV6,
    158		.match		= ecn_mt6,
    159		.matchsize	= sizeof(struct xt_ecn_info),
    160		.checkentry	= ecn_mt_check6,
    161		.me		= THIS_MODULE,
    162	},
    163};
    164
    165static int __init ecn_mt_init(void)
    166{
    167	return xt_register_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg));
    168}
    169
    170static void __exit ecn_mt_exit(void)
    171{
    172	xt_unregister_matches(ecn_mt_reg, ARRAY_SIZE(ecn_mt_reg));
    173}
    174
    175module_init(ecn_mt_init);
    176module_exit(ecn_mt_exit);