diff options
Diffstat (limited to 'net/ipv6/netfilter/ip6t_rpfilter.c')
-rw-r--r-- | net/ipv6/netfilter/ip6t_rpfilter.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c b/net/ipv6/netfilter/ip6t_rpfilter.c new file mode 100644 index 000000000..790e0c6b1 --- /dev/null +++ b/net/ipv6/netfilter/ip6t_rpfilter.c @@ -0,0 +1,140 @@ +/* + * 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 = { + .flowi6_iif = LOOPBACK_IFINDEX, + .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); |