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![Florian Westphal](/assets/img/avatar_default.png)
Quoting https://bugzilla.netfilter.org/show_bug.cgi?id=812: [ ip6tables -m addrtype ] When I tried to use in the nat/PREROUTING it messes up the routing cache even if the rule didn't matched at all. [..] If I remove the --limit-iface-in from the non-working scenario, so just use the -m addrtype --dst-type LOCAL it works! This happens when LOCAL type matching is requested with --limit-iface-in, and the default ipv6 route is via the interface the packet we test arrived on. Because xt_addrtype uses ip6_route_output, the ipv6 routing implementation creates an unwanted cached entry, and the packet won't make it to the real/expected destination. Silently ignoring --limit-iface-in makes the routing work but it breaks rule matching (--dst-type LOCAL with limit-iface-in is supposed to only match if the dst address is configured on the incoming interface; without --limit-iface-in it will match if the address is reachable via lo). The test should call ipv6_chk_addr() instead. However, this would add a link-time dependency on ipv6. There are two possible solutions: 1) Revert the commit that moved ipt_addrtype to xt_addrtype, and put ipv6 specific code into ip6t_addrtype. 2) add new "nf_ipv6_ops" struct to register pointers to ipv6 functions. While the former might seem preferable, Pablo pointed out that there are more xt modules with link-time dependeny issues regarding ipv6, so lets go for 2). Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
248 lines
6.6 KiB
C
248 lines
6.6 KiB
C
/*
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* iptables module to match inet_addr_type() of an ip.
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*
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* Copyright (c) 2004 Patrick McHardy <kaber@trash.net>
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* (C) 2007 Laszlo Attila Toth <panther@balabit.hu>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netdevice.h>
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#include <linux/ip.h>
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#include <net/route.h>
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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#include <net/ipv6.h>
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#include <net/ip6_route.h>
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#include <net/ip6_fib.h>
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#endif
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter/xt_addrtype.h>
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#include <linux/netfilter/x_tables.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_DESCRIPTION("Xtables: address type match");
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MODULE_ALIAS("ipt_addrtype");
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MODULE_ALIAS("ip6t_addrtype");
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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static u32 match_lookup_rt6(struct net *net, const struct net_device *dev,
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const struct in6_addr *addr, u16 mask)
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{
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const struct nf_afinfo *afinfo;
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struct flowi6 flow;
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struct rt6_info *rt;
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u32 ret = 0;
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int route_err;
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memset(&flow, 0, sizeof(flow));
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flow.daddr = *addr;
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if (dev)
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flow.flowi6_oif = dev->ifindex;
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rcu_read_lock();
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afinfo = nf_get_afinfo(NFPROTO_IPV6);
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if (afinfo != NULL) {
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const struct nf_ipv6_ops *v6ops;
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if (dev && (mask & XT_ADDRTYPE_LOCAL)) {
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v6ops = nf_get_ipv6_ops();
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if (v6ops && v6ops->chk_addr(net, addr, dev, true))
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ret = XT_ADDRTYPE_LOCAL;
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}
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route_err = afinfo->route(net, (struct dst_entry **)&rt,
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flowi6_to_flowi(&flow), false);
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} else {
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route_err = 1;
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}
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rcu_read_unlock();
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if (route_err)
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return XT_ADDRTYPE_UNREACHABLE;
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if (rt->rt6i_flags & RTF_REJECT)
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ret = XT_ADDRTYPE_UNREACHABLE;
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if (dev == NULL && rt->rt6i_flags & RTF_LOCAL)
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ret |= XT_ADDRTYPE_LOCAL;
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if (rt->rt6i_flags & RTF_ANYCAST)
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ret |= XT_ADDRTYPE_ANYCAST;
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dst_release(&rt->dst);
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return ret;
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}
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static bool match_type6(struct net *net, const struct net_device *dev,
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const struct in6_addr *addr, u16 mask)
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{
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int addr_type = ipv6_addr_type(addr);
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if ((mask & XT_ADDRTYPE_MULTICAST) &&
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!(addr_type & IPV6_ADDR_MULTICAST))
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return false;
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if ((mask & XT_ADDRTYPE_UNICAST) && !(addr_type & IPV6_ADDR_UNICAST))
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return false;
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if ((mask & XT_ADDRTYPE_UNSPEC) && addr_type != IPV6_ADDR_ANY)
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return false;
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if ((XT_ADDRTYPE_LOCAL | XT_ADDRTYPE_ANYCAST |
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XT_ADDRTYPE_UNREACHABLE) & mask)
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return !!(mask & match_lookup_rt6(net, dev, addr, mask));
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return true;
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}
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static bool
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addrtype_mt6(struct net *net, const struct net_device *dev,
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const struct sk_buff *skb, const struct xt_addrtype_info_v1 *info)
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{
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const struct ipv6hdr *iph = ipv6_hdr(skb);
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bool ret = true;
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if (info->source)
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ret &= match_type6(net, dev, &iph->saddr, info->source) ^
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(info->flags & XT_ADDRTYPE_INVERT_SOURCE);
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if (ret && info->dest)
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ret &= match_type6(net, dev, &iph->daddr, info->dest) ^
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!!(info->flags & XT_ADDRTYPE_INVERT_DEST);
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return ret;
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}
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#endif
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static inline bool match_type(struct net *net, const struct net_device *dev,
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__be32 addr, u_int16_t mask)
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{
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return !!(mask & (1 << inet_dev_addr_type(net, dev, addr)));
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}
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static bool
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addrtype_mt_v0(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct net *net = dev_net(par->in ? par->in : par->out);
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const struct xt_addrtype_info *info = par->matchinfo;
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const struct iphdr *iph = ip_hdr(skb);
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bool ret = true;
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if (info->source)
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ret &= match_type(net, NULL, iph->saddr, info->source) ^
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info->invert_source;
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if (info->dest)
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ret &= match_type(net, NULL, iph->daddr, info->dest) ^
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info->invert_dest;
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return ret;
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}
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static bool
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addrtype_mt_v1(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct net *net = dev_net(par->in ? par->in : par->out);
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const struct xt_addrtype_info_v1 *info = par->matchinfo;
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const struct iphdr *iph;
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const struct net_device *dev = NULL;
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bool ret = true;
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if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN)
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dev = par->in;
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else if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT)
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dev = par->out;
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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if (par->family == NFPROTO_IPV6)
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return addrtype_mt6(net, dev, skb, info);
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#endif
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iph = ip_hdr(skb);
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if (info->source)
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ret &= match_type(net, dev, iph->saddr, info->source) ^
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(info->flags & XT_ADDRTYPE_INVERT_SOURCE);
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if (ret && info->dest)
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ret &= match_type(net, dev, iph->daddr, info->dest) ^
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!!(info->flags & XT_ADDRTYPE_INVERT_DEST);
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return ret;
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}
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static int addrtype_mt_checkentry_v1(const struct xt_mtchk_param *par)
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{
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struct xt_addrtype_info_v1 *info = par->matchinfo;
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if (info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN &&
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info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
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pr_info("both incoming and outgoing "
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"interface limitation cannot be selected\n");
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return -EINVAL;
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}
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if (par->hook_mask & ((1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_LOCAL_IN)) &&
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info->flags & XT_ADDRTYPE_LIMIT_IFACE_OUT) {
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pr_info("output interface limitation "
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"not valid in PREROUTING and INPUT\n");
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return -EINVAL;
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}
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if (par->hook_mask & ((1 << NF_INET_POST_ROUTING) |
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(1 << NF_INET_LOCAL_OUT)) &&
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info->flags & XT_ADDRTYPE_LIMIT_IFACE_IN) {
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pr_info("input interface limitation "
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"not valid in POSTROUTING and OUTPUT\n");
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return -EINVAL;
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}
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#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
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if (par->family == NFPROTO_IPV6) {
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if ((info->source | info->dest) & XT_ADDRTYPE_BLACKHOLE) {
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pr_err("ipv6 BLACKHOLE matching not supported\n");
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return -EINVAL;
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}
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if ((info->source | info->dest) >= XT_ADDRTYPE_PROHIBIT) {
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pr_err("ipv6 PROHIBT (THROW, NAT ..) matching not supported\n");
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return -EINVAL;
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}
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if ((info->source | info->dest) & XT_ADDRTYPE_BROADCAST) {
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pr_err("ipv6 does not support BROADCAST matching\n");
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return -EINVAL;
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}
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}
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#endif
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return 0;
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}
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static struct xt_match addrtype_mt_reg[] __read_mostly = {
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{
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.name = "addrtype",
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.family = NFPROTO_IPV4,
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.match = addrtype_mt_v0,
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.matchsize = sizeof(struct xt_addrtype_info),
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.me = THIS_MODULE
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},
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{
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.name = "addrtype",
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.family = NFPROTO_UNSPEC,
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.revision = 1,
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.match = addrtype_mt_v1,
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.checkentry = addrtype_mt_checkentry_v1,
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.matchsize = sizeof(struct xt_addrtype_info_v1),
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.me = THIS_MODULE
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}
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};
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static int __init addrtype_mt_init(void)
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{
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return xt_register_matches(addrtype_mt_reg,
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ARRAY_SIZE(addrtype_mt_reg));
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}
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static void __exit addrtype_mt_exit(void)
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{
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xt_unregister_matches(addrtype_mt_reg, ARRAY_SIZE(addrtype_mt_reg));
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}
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module_init(addrtype_mt_init);
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module_exit(addrtype_mt_exit);
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