123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126 |
- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * Copyright (c) 2011 Florian Westphal <fw@strlen.de>
- *
- * based on fib_frontend.c; Author: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/module.h>
- #include <linux/skbuff.h>
- #include <linux/netdevice.h>
- #include <linux/ip.h>
- #include <net/ip.h>
- #include <net/ip_fib.h>
- #include <net/route.h>
- #include <linux/netfilter/xt_rpfilter.h>
- #include <linux/netfilter/x_tables.h>
- MODULE_LICENSE("GPL");
- MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
- MODULE_DESCRIPTION("iptables: ipv4 reverse path filter match");
- /* don't try to find route from mcast/bcast/zeronet */
- static __be32 rpfilter_get_saddr(__be32 addr)
- {
- if (ipv4_is_multicast(addr) || ipv4_is_lbcast(addr) ||
- ipv4_is_zeronet(addr))
- return 0;
- return addr;
- }
- static bool rpfilter_lookup_reverse(struct net *net, struct flowi4 *fl4,
- const struct net_device *dev, u8 flags)
- {
- struct fib_result res;
- int ret __maybe_unused;
- if (fib_lookup(net, fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
- return false;
- if (res.type != RTN_UNICAST) {
- if (res.type != RTN_LOCAL || !(flags & XT_RPFILTER_ACCEPT_LOCAL))
- return false;
- }
- return fib_info_nh_uses_dev(res.fi, dev) || flags & XT_RPFILTER_LOOSE;
- }
- static bool
- rpfilter_is_loopback(const struct sk_buff *skb, const struct net_device *in)
- {
- return skb->pkt_type == PACKET_LOOPBACK || in->flags & IFF_LOOPBACK;
- }
- static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
- {
- const struct xt_rpfilter_info *info;
- const struct iphdr *iph;
- struct flowi4 flow;
- bool invert;
- info = par->matchinfo;
- invert = info->flags & XT_RPFILTER_INVERT;
- if (rpfilter_is_loopback(skb, xt_in(par)))
- return true ^ invert;
- iph = ip_hdr(skb);
- if (ipv4_is_zeronet(iph->saddr)) {
- if (ipv4_is_lbcast(iph->daddr) ||
- ipv4_is_local_multicast(iph->daddr))
- return true ^ invert;
- }
- memset(&flow, 0, sizeof(flow));
- flow.flowi4_iif = LOOPBACK_IFINDEX;
- flow.daddr = iph->saddr;
- flow.saddr = rpfilter_get_saddr(iph->daddr);
- flow.flowi4_mark = info->flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
- flow.flowi4_tos = iph->tos & IPTOS_RT_MASK;
- flow.flowi4_scope = RT_SCOPE_UNIVERSE;
- flow.flowi4_oif = l3mdev_master_ifindex_rcu(xt_in(par));
- return rpfilter_lookup_reverse(xt_net(par), &flow, xt_in(par), info->flags) ^ invert;
- }
- static int rpfilter_check(const struct xt_mtchk_param *par)
- {
- const struct xt_rpfilter_info *info = par->matchinfo;
- unsigned int options = ~XT_RPFILTER_OPTION_MASK;
- if (info->flags & options) {
- pr_info_ratelimited("unknown options\n");
- return -EINVAL;
- }
- if (strcmp(par->table, "mangle") != 0 &&
- strcmp(par->table, "raw") != 0) {
- pr_info_ratelimited("only valid in \'raw\' or \'mangle\' table, not \'%s\'\n",
- par->table);
- return -EINVAL;
- }
- return 0;
- }
- static struct xt_match rpfilter_mt_reg __read_mostly = {
- .name = "rpfilter",
- .family = NFPROTO_IPV4,
- .checkentry = rpfilter_check,
- .match = rpfilter_mt,
- .matchsize = sizeof(struct xt_rpfilter_info),
- .hooks = (1 << NF_INET_PRE_ROUTING),
- .me = THIS_MODULE
- };
- static int __init rpfilter_mt_init(void)
- {
- return xt_register_match(&rpfilter_mt_reg);
- }
- static void __exit rpfilter_mt_exit(void)
- {
- xt_unregister_match(&rpfilter_mt_reg);
- }
- module_init(rpfilter_mt_init);
- module_exit(rpfilter_mt_exit);
|