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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 | /* * Copyright (c) 2011 Florian Westphal <fw@strlen.de> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/skbuff.h> #include <linux/netdevice.h> #include <linux/route.h> #include <net/ip6_fib.h> #include <net/ip6_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("Xtables: IPv6 reverse path filter match"); static bool rpfilter_addr_unicast(const struct in6_addr *addr) { int addr_type = ipv6_addr_type(addr); return addr_type & IPV6_ADDR_UNICAST; } static bool rpfilter_lookup_reverse6(const struct sk_buff *skb, const struct net_device *dev, u8 flags) { struct rt6_info *rt; struct ipv6hdr *iph = ipv6_hdr(skb); bool ret = false; struct flowi6 fl6 = { .flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK, .flowi6_proto = iph->nexthdr, .daddr = iph->saddr, }; int lookup_flags; if (rpfilter_addr_unicast(&iph->daddr)) { memcpy(&fl6.saddr, &iph->daddr, sizeof(struct in6_addr)); lookup_flags = RT6_LOOKUP_F_HAS_SADDR; } else { lookup_flags = 0; } fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0; if ((flags & XT_RPFILTER_LOOSE) == 0) { fl6.flowi6_oif = dev->ifindex; lookup_flags |= RT6_LOOKUP_F_IFACE; } rt = (void *) ip6_route_lookup(dev_net(dev), &fl6, lookup_flags); if (rt->dst.error) goto out; if (rt->rt6i_flags & (RTF_REJECT|RTF_ANYCAST)) goto out; if (rt->rt6i_flags & RTF_LOCAL) { ret = flags & XT_RPFILTER_ACCEPT_LOCAL; goto out; } if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE)) ret = true; out: ip6_rt_put(rt); return ret; } static bool rpfilter_is_local(const struct sk_buff *skb) { const struct rt6_info *rt = (const void *) skb_dst(skb); return rt && (rt->rt6i_flags & RTF_LOCAL); } static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par) { const struct xt_rpfilter_info *info = par->matchinfo; int saddrtype; struct ipv6hdr *iph; bool invert = info->flags & XT_RPFILTER_INVERT; if (rpfilter_is_local(skb)) return true ^ invert; iph = ipv6_hdr(skb); saddrtype = ipv6_addr_type(&iph->saddr); if (unlikely(saddrtype == IPV6_ADDR_ANY)) return true ^ invert; /* not routable: forward path will drop it */ return rpfilter_lookup_reverse6(skb, par->in, 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("unknown options encountered"); return -EINVAL; } if (strcmp(par->table, "mangle") != 0 && strcmp(par->table, "raw") != 0) { pr_info("match only valid in the \'raw\' " "or \'mangle\' tables, not \'%s\'.\n", par->table); return -EINVAL; } return 0; } static struct xt_match rpfilter_mt_reg __read_mostly = { .name = "rpfilter", .family = NFPROTO_IPV6, .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); |