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_helper.c (2382B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* iptables module to match on related connections */
      3/*
      4 * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se>
      5 */
      6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      7#include <linux/module.h>
      8#include <linux/skbuff.h>
      9#include <linux/netfilter.h>
     10#include <net/netfilter/nf_conntrack.h>
     11#include <net/netfilter/nf_conntrack_core.h>
     12#include <net/netfilter/nf_conntrack_helper.h>
     13#include <linux/netfilter/x_tables.h>
     14#include <linux/netfilter/xt_helper.h>
     15
     16MODULE_LICENSE("GPL");
     17MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>");
     18MODULE_DESCRIPTION("Xtables: Related connection matching");
     19MODULE_ALIAS("ipt_helper");
     20MODULE_ALIAS("ip6t_helper");
     21
     22
     23static bool
     24helper_mt(const struct sk_buff *skb, struct xt_action_param *par)
     25{
     26	const struct xt_helper_info *info = par->matchinfo;
     27	const struct nf_conn *ct;
     28	const struct nf_conn_help *master_help;
     29	const struct nf_conntrack_helper *helper;
     30	enum ip_conntrack_info ctinfo;
     31	bool ret = info->invert;
     32
     33	ct = nf_ct_get(skb, &ctinfo);
     34	if (!ct || !ct->master)
     35		return ret;
     36
     37	master_help = nfct_help(ct->master);
     38	if (!master_help)
     39		return ret;
     40
     41	/* rcu_read_lock()ed by nf_hook_thresh */
     42	helper = rcu_dereference(master_help->helper);
     43	if (!helper)
     44		return ret;
     45
     46	if (info->name[0] == '\0')
     47		ret = !ret;
     48	else
     49		ret ^= !strncmp(helper->name, info->name,
     50				strlen(helper->name));
     51	return ret;
     52}
     53
     54static int helper_mt_check(const struct xt_mtchk_param *par)
     55{
     56	struct xt_helper_info *info = par->matchinfo;
     57	int ret;
     58
     59	ret = nf_ct_netns_get(par->net, par->family);
     60	if (ret < 0) {
     61		pr_info_ratelimited("cannot load conntrack support for proto=%u\n",
     62				    par->family);
     63		return ret;
     64	}
     65	info->name[sizeof(info->name) - 1] = '\0';
     66	return 0;
     67}
     68
     69static void helper_mt_destroy(const struct xt_mtdtor_param *par)
     70{
     71	nf_ct_netns_put(par->net, par->family);
     72}
     73
     74static struct xt_match helper_mt_reg __read_mostly = {
     75	.name       = "helper",
     76	.revision   = 0,
     77	.family     = NFPROTO_UNSPEC,
     78	.checkentry = helper_mt_check,
     79	.match      = helper_mt,
     80	.destroy    = helper_mt_destroy,
     81	.matchsize  = sizeof(struct xt_helper_info),
     82	.me         = THIS_MODULE,
     83};
     84
     85static int __init helper_mt_init(void)
     86{
     87	return xt_register_match(&helper_mt_reg);
     88}
     89
     90static void __exit helper_mt_exit(void)
     91{
     92	xt_unregister_match(&helper_mt_reg);
     93}
     94
     95module_init(helper_mt_init);
     96module_exit(helper_mt_exit);