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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ip6t_rpfilter.c (3955B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (c) 2011 Florian Westphal <fw@strlen.de>
      4 */
      5#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      6#include <linux/module.h>
      7#include <linux/skbuff.h>
      8#include <linux/netdevice.h>
      9#include <linux/route.h>
     10#include <net/ip6_fib.h>
     11#include <net/ip6_route.h>
     12
     13#include <linux/netfilter/xt_rpfilter.h>
     14#include <linux/netfilter/x_tables.h>
     15
     16MODULE_LICENSE("GPL");
     17MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
     18MODULE_DESCRIPTION("Xtables: IPv6 reverse path filter match");
     19
     20static bool rpfilter_addr_unicast(const struct in6_addr *addr)
     21{
     22	int addr_type = ipv6_addr_type(addr);
     23	return addr_type & IPV6_ADDR_UNICAST;
     24}
     25
     26static bool rpfilter_addr_linklocal(const struct in6_addr *addr)
     27{
     28	int addr_type = ipv6_addr_type(addr);
     29	return addr_type & IPV6_ADDR_LINKLOCAL;
     30}
     31
     32static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
     33				     const struct net_device *dev, u8 flags)
     34{
     35	struct rt6_info *rt;
     36	struct ipv6hdr *iph = ipv6_hdr(skb);
     37	bool ret = false;
     38	struct flowi6 fl6 = {
     39		.flowi6_iif = LOOPBACK_IFINDEX,
     40		.flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK,
     41		.flowi6_proto = iph->nexthdr,
     42		.daddr = iph->saddr,
     43	};
     44	int lookup_flags;
     45
     46	if (rpfilter_addr_unicast(&iph->daddr)) {
     47		memcpy(&fl6.saddr, &iph->daddr, sizeof(struct in6_addr));
     48		lookup_flags = RT6_LOOKUP_F_HAS_SADDR;
     49	} else {
     50		lookup_flags = 0;
     51	}
     52
     53	fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
     54
     55	if (rpfilter_addr_linklocal(&iph->saddr)) {
     56		lookup_flags |= RT6_LOOKUP_F_IFACE;
     57		fl6.flowi6_oif = dev->ifindex;
     58	/* Set flowi6_oif for vrf devices to lookup route in l3mdev domain. */
     59	} else if (netif_is_l3_master(dev) || netif_is_l3_slave(dev) ||
     60		  (flags & XT_RPFILTER_LOOSE) == 0)
     61		fl6.flowi6_oif = dev->ifindex;
     62
     63	rt = (void *)ip6_route_lookup(net, &fl6, skb, lookup_flags);
     64	if (rt->dst.error)
     65		goto out;
     66
     67	if (rt->rt6i_flags & (RTF_REJECT|RTF_ANYCAST))
     68		goto out;
     69
     70	if (rt->rt6i_flags & RTF_LOCAL) {
     71		ret = flags & XT_RPFILTER_ACCEPT_LOCAL;
     72		goto out;
     73	}
     74
     75	if (rt->rt6i_idev->dev == dev ||
     76	    l3mdev_master_ifindex_rcu(rt->rt6i_idev->dev) == dev->ifindex ||
     77	    (flags & XT_RPFILTER_LOOSE))
     78		ret = true;
     79 out:
     80	ip6_rt_put(rt);
     81	return ret;
     82}
     83
     84static bool
     85rpfilter_is_loopback(const struct sk_buff *skb, const struct net_device *in)
     86{
     87	return skb->pkt_type == PACKET_LOOPBACK || in->flags & IFF_LOOPBACK;
     88}
     89
     90static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
     91{
     92	const struct xt_rpfilter_info *info = par->matchinfo;
     93	int saddrtype;
     94	struct ipv6hdr *iph;
     95	bool invert = info->flags & XT_RPFILTER_INVERT;
     96
     97	if (rpfilter_is_loopback(skb, xt_in(par)))
     98		return true ^ invert;
     99
    100	iph = ipv6_hdr(skb);
    101	saddrtype = ipv6_addr_type(&iph->saddr);
    102	if (unlikely(saddrtype == IPV6_ADDR_ANY))
    103		return true ^ invert; /* not routable: forward path will drop it */
    104
    105	return rpfilter_lookup_reverse6(xt_net(par), skb, xt_in(par),
    106					info->flags) ^ invert;
    107}
    108
    109static int rpfilter_check(const struct xt_mtchk_param *par)
    110{
    111	const struct xt_rpfilter_info *info = par->matchinfo;
    112	unsigned int options = ~XT_RPFILTER_OPTION_MASK;
    113
    114	if (info->flags & options) {
    115		pr_info_ratelimited("unknown options\n");
    116		return -EINVAL;
    117	}
    118
    119	if (strcmp(par->table, "mangle") != 0 &&
    120	    strcmp(par->table, "raw") != 0) {
    121		pr_info_ratelimited("only valid in \'raw\' or \'mangle\' table, not \'%s\'\n",
    122				    par->table);
    123		return -EINVAL;
    124	}
    125
    126	return 0;
    127}
    128
    129static struct xt_match rpfilter_mt_reg __read_mostly = {
    130	.name		= "rpfilter",
    131	.family		= NFPROTO_IPV6,
    132	.checkentry	= rpfilter_check,
    133	.match		= rpfilter_mt,
    134	.matchsize	= sizeof(struct xt_rpfilter_info),
    135	.hooks		= (1 << NF_INET_PRE_ROUTING),
    136	.me		= THIS_MODULE
    137};
    138
    139static int __init rpfilter_mt_init(void)
    140{
    141	return xt_register_match(&rpfilter_mt_reg);
    142}
    143
    144static void __exit rpfilter_mt_exit(void)
    145{
    146	xt_unregister_match(&rpfilter_mt_reg);
    147}
    148
    149module_init(rpfilter_mt_init);
    150module_exit(rpfilter_mt_exit);