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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ipt_rpfilter.c (3364B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (c) 2011 Florian Westphal <fw@strlen.de>
      4 *
      5 * based on fib_frontend.c; Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
      6 */
      7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      8#include <linux/module.h>
      9#include <linux/skbuff.h>
     10#include <linux/netdevice.h>
     11#include <linux/ip.h>
     12#include <net/ip.h>
     13#include <net/ip_fib.h>
     14#include <net/route.h>
     15
     16#include <linux/netfilter/xt_rpfilter.h>
     17#include <linux/netfilter/x_tables.h>
     18
     19MODULE_LICENSE("GPL");
     20MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
     21MODULE_DESCRIPTION("iptables: ipv4 reverse path filter match");
     22
     23/* don't try to find route from mcast/bcast/zeronet */
     24static __be32 rpfilter_get_saddr(__be32 addr)
     25{
     26	if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
     27	    ipv4_is_zeronet(addr))
     28		return 0;
     29	return addr;
     30}
     31
     32static bool rpfilter_lookup_reverse(struct net *net, struct flowi4 *fl4,
     33				const struct net_device *dev, u8 flags)
     34{
     35	struct fib_result res;
     36	int ret __maybe_unused;
     37
     38	if (fib_lookup(net, fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
     39		return false;
     40
     41	if (res.type != RTN_UNICAST) {
     42		if (res.type != RTN_LOCAL || !(flags & XT_RPFILTER_ACCEPT_LOCAL))
     43			return false;
     44	}
     45	return fib_info_nh_uses_dev(res.fi, dev) || flags & XT_RPFILTER_LOOSE;
     46}
     47
     48static bool
     49rpfilter_is_loopback(const struct sk_buff *skb, const struct net_device *in)
     50{
     51	return skb->pkt_type == PACKET_LOOPBACK || in->flags & IFF_LOOPBACK;
     52}
     53
     54static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
     55{
     56	const struct xt_rpfilter_info *info;
     57	const struct iphdr *iph;
     58	struct flowi4 flow;
     59	bool invert;
     60
     61	info = par->matchinfo;
     62	invert = info->flags & XT_RPFILTER_INVERT;
     63
     64	if (rpfilter_is_loopback(skb, xt_in(par)))
     65		return true ^ invert;
     66
     67	iph = ip_hdr(skb);
     68	if (ipv4_is_zeronet(iph->saddr)) {
     69		if (ipv4_is_lbcast(iph->daddr) ||
     70		    ipv4_is_local_multicast(iph->daddr))
     71			return true ^ invert;
     72	}
     73
     74	memset(&flow, 0, sizeof(flow));
     75	flow.flowi4_iif = LOOPBACK_IFINDEX;
     76	flow.daddr = iph->saddr;
     77	flow.saddr = rpfilter_get_saddr(iph->daddr);
     78	flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
     79	flow.flowi4_tos = iph->tos & IPTOS_RT_MASK;
     80	flow.flowi4_scope = RT_SCOPE_UNIVERSE;
     81	flow.flowi4_oif = l3mdev_master_ifindex_rcu(xt_in(par));
     82
     83	return rpfilter_lookup_reverse(xt_net(par), &flow, xt_in(par), info->flags) ^ invert;
     84}
     85
     86static int rpfilter_check(const struct xt_mtchk_param *par)
     87{
     88	const struct xt_rpfilter_info *info = par->matchinfo;
     89	unsigned int options = ~XT_RPFILTER_OPTION_MASK;
     90	if (info->flags & options) {
     91		pr_info_ratelimited("unknown options\n");
     92		return -EINVAL;
     93	}
     94
     95	if (strcmp(par->table, "mangle") != 0 &&
     96	    strcmp(par->table, "raw") != 0) {
     97		pr_info_ratelimited("only valid in \'raw\' or \'mangle\' table, not \'%s\'\n",
     98				    par->table);
     99		return -EINVAL;
    100	}
    101
    102	return 0;
    103}
    104
    105static struct xt_match rpfilter_mt_reg __read_mostly = {
    106	.name		= "rpfilter",
    107	.family		= NFPROTO_IPV4,
    108	.checkentry	= rpfilter_check,
    109	.match		= rpfilter_mt,
    110	.matchsize	= sizeof(struct xt_rpfilter_info),
    111	.hooks		= (1 << NF_INET_PRE_ROUTING),
    112	.me		= THIS_MODULE
    113};
    114
    115static int __init rpfilter_mt_init(void)
    116{
    117	return xt_register_match(&rpfilter_mt_reg);
    118}
    119
    120static void __exit rpfilter_mt_exit(void)
    121{
    122	xt_unregister_match(&rpfilter_mt_reg);
    123}
    124
    125module_init(rpfilter_mt_init);
    126module_exit(rpfilter_mt_exit);