Florian Westphal | e26f9a4 | 2011-08-19 13:52:40 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2011 Florian Westphal <fw@strlen.de> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/skbuff.h> |
| 11 | #include <linux/netdevice.h> |
| 12 | #include <linux/route.h> |
| 13 | #include <net/ip6_fib.h> |
| 14 | #include <net/ip6_route.h> |
| 15 | |
| 16 | #include <linux/netfilter/xt_rpfilter.h> |
| 17 | #include <linux/netfilter/x_tables.h> |
| 18 | |
| 19 | MODULE_LICENSE("GPL"); |
| 20 | MODULE_AUTHOR("Florian Westphal <fw@strlen.de>"); |
| 21 | MODULE_DESCRIPTION("Xtables: IPv6 reverse path filter match"); |
| 22 | |
| 23 | static bool rpfilter_addr_unicast(const struct in6_addr *addr) |
| 24 | { |
| 25 | int addr_type = ipv6_addr_type(addr); |
| 26 | return addr_type & IPV6_ADDR_UNICAST; |
| 27 | } |
| 28 | |
| 29 | static bool rpfilter_lookup_reverse6(const struct sk_buff *skb, |
| 30 | const struct net_device *dev, u8 flags) |
| 31 | { |
| 32 | struct rt6_info *rt; |
| 33 | struct ipv6hdr *iph = ipv6_hdr(skb); |
| 34 | bool ret = false; |
| 35 | struct flowi6 fl6 = { |
Julian Anastasov | e374c61 | 2014-04-28 10:51:56 +0300 | [diff] [blame^] | 36 | .flowi6_iif = LOOPBACK_IFINDEX, |
Florian Westphal | e26f9a4 | 2011-08-19 13:52:40 +0200 | [diff] [blame] | 37 | .flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK, |
| 38 | .flowi6_proto = iph->nexthdr, |
| 39 | .daddr = iph->saddr, |
| 40 | }; |
| 41 | int lookup_flags; |
| 42 | |
| 43 | if (rpfilter_addr_unicast(&iph->daddr)) { |
| 44 | memcpy(&fl6.saddr, &iph->daddr, sizeof(struct in6_addr)); |
| 45 | lookup_flags = RT6_LOOKUP_F_HAS_SADDR; |
| 46 | } else { |
| 47 | lookup_flags = 0; |
| 48 | } |
| 49 | |
| 50 | fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0; |
| 51 | if ((flags & XT_RPFILTER_LOOSE) == 0) { |
| 52 | fl6.flowi6_oif = dev->ifindex; |
| 53 | lookup_flags |= RT6_LOOKUP_F_IFACE; |
| 54 | } |
| 55 | |
| 56 | rt = (void *) ip6_route_lookup(dev_net(dev), &fl6, lookup_flags); |
| 57 | if (rt->dst.error) |
| 58 | goto out; |
| 59 | |
| 60 | if (rt->rt6i_flags & (RTF_REJECT|RTF_ANYCAST)) |
| 61 | goto out; |
| 62 | |
| 63 | if (rt->rt6i_flags & RTF_LOCAL) { |
| 64 | ret = flags & XT_RPFILTER_ACCEPT_LOCAL; |
| 65 | goto out; |
| 66 | } |
| 67 | |
| 68 | if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE)) |
| 69 | ret = true; |
| 70 | out: |
Amerigo Wang | 94e187c | 2012-10-29 00:13:19 +0000 | [diff] [blame] | 71 | ip6_rt_put(rt); |
Florian Westphal | e26f9a4 | 2011-08-19 13:52:40 +0200 | [diff] [blame] | 72 | return ret; |
| 73 | } |
| 74 | |
Florian Westphal | f83a7ea | 2013-04-17 22:45:24 +0000 | [diff] [blame] | 75 | static bool rpfilter_is_local(const struct sk_buff *skb) |
| 76 | { |
| 77 | const struct rt6_info *rt = (const void *) skb_dst(skb); |
| 78 | return rt && (rt->rt6i_flags & RTF_LOCAL); |
| 79 | } |
| 80 | |
Florian Westphal | e26f9a4 | 2011-08-19 13:52:40 +0200 | [diff] [blame] | 81 | static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) |
| 82 | { |
| 83 | const struct xt_rpfilter_info *info = par->matchinfo; |
| 84 | int saddrtype; |
| 85 | struct ipv6hdr *iph; |
| 86 | bool invert = info->flags & XT_RPFILTER_INVERT; |
| 87 | |
Florian Westphal | f83a7ea | 2013-04-17 22:45:24 +0000 | [diff] [blame] | 88 | if (rpfilter_is_local(skb)) |
Florian Westphal | e26f9a4 | 2011-08-19 13:52:40 +0200 | [diff] [blame] | 89 | return true ^ invert; |
| 90 | |
| 91 | iph = ipv6_hdr(skb); |
| 92 | saddrtype = ipv6_addr_type(&iph->saddr); |
| 93 | if (unlikely(saddrtype == IPV6_ADDR_ANY)) |
| 94 | return true ^ invert; /* not routable: forward path will drop it */ |
| 95 | |
| 96 | return rpfilter_lookup_reverse6(skb, par->in, info->flags) ^ invert; |
| 97 | } |
| 98 | |
| 99 | static int rpfilter_check(const struct xt_mtchk_param *par) |
| 100 | { |
| 101 | const struct xt_rpfilter_info *info = par->matchinfo; |
| 102 | unsigned int options = ~XT_RPFILTER_OPTION_MASK; |
| 103 | |
| 104 | if (info->flags & options) { |
| 105 | pr_info("unknown options encountered"); |
| 106 | return -EINVAL; |
| 107 | } |
| 108 | |
| 109 | if (strcmp(par->table, "mangle") != 0 && |
| 110 | strcmp(par->table, "raw") != 0) { |
| 111 | pr_info("match only valid in the \'raw\' " |
| 112 | "or \'mangle\' tables, not \'%s\'.\n", par->table); |
| 113 | return -EINVAL; |
| 114 | } |
| 115 | |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | static struct xt_match rpfilter_mt_reg __read_mostly = { |
| 120 | .name = "rpfilter", |
| 121 | .family = NFPROTO_IPV6, |
| 122 | .checkentry = rpfilter_check, |
| 123 | .match = rpfilter_mt, |
| 124 | .matchsize = sizeof(struct xt_rpfilter_info), |
| 125 | .hooks = (1 << NF_INET_PRE_ROUTING), |
| 126 | .me = THIS_MODULE |
| 127 | }; |
| 128 | |
| 129 | static int __init rpfilter_mt_init(void) |
| 130 | { |
| 131 | return xt_register_match(&rpfilter_mt_reg); |
| 132 | } |
| 133 | |
| 134 | static void __exit rpfilter_mt_exit(void) |
| 135 | { |
| 136 | xt_unregister_match(&rpfilter_mt_reg); |
| 137 | } |
| 138 | |
| 139 | module_init(rpfilter_mt_init); |
| 140 | module_exit(rpfilter_mt_exit); |