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![Florian Westphal](/assets/img/avatar_default.png)
MASQUERADE, S/DNAT and REDIRECT already call functions that depend on the conntrack module. However, since the conntrack hooks are now registered in a lazy fashion (i.e., only when needed) a symbol reference is not enough. Thus, when something is added to a nat table, make sure that it will see packets by calling nf_ct_netns_get() which will register the conntrack hooks in the current netns. An alternative would be to add these dependencies to the NAT table. However, that has problems when using non-modular builds -- we might register e.g. ipv6 conntrack before its initcall has run, leading to NULL deref crashes since its per-netns storage has not yet been allocated. Adding the dependency in the modules instead has the advantage that nat table also does not register its hooks until rules are added. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
172 lines
5 KiB
C
172 lines
5 KiB
C
/*
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* (C) 2000-2001 Svenning Soerensen <svenning@post5.tele.dk>
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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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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#include <linux/ip.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/netdevice.h>
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#include <linux/ipv6.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter/x_tables.h>
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#include <net/netfilter/nf_nat.h>
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static unsigned int
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netmap_tg6(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct nf_nat_range *range = par->targinfo;
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struct nf_nat_range newrange;
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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union nf_inet_addr new_addr, netmask;
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unsigned int i;
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ct = nf_ct_get(skb, &ctinfo);
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for (i = 0; i < ARRAY_SIZE(range->min_addr.ip6); i++)
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netmask.ip6[i] = ~(range->min_addr.ip6[i] ^
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range->max_addr.ip6[i]);
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if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
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xt_hooknum(par) == NF_INET_LOCAL_OUT)
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new_addr.in6 = ipv6_hdr(skb)->daddr;
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else
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new_addr.in6 = ipv6_hdr(skb)->saddr;
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for (i = 0; i < ARRAY_SIZE(new_addr.ip6); i++) {
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new_addr.ip6[i] &= ~netmask.ip6[i];
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new_addr.ip6[i] |= range->min_addr.ip6[i] &
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netmask.ip6[i];
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}
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newrange.flags = range->flags | NF_NAT_RANGE_MAP_IPS;
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newrange.min_addr = new_addr;
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newrange.max_addr = new_addr;
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newrange.min_proto = range->min_proto;
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newrange.max_proto = range->max_proto;
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return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
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}
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static int netmap_tg6_checkentry(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_range *range = par->targinfo;
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if (!(range->flags & NF_NAT_RANGE_MAP_IPS))
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return -EINVAL;
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return nf_ct_netns_get(par->net, par->family);
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}
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static void netmap_tg_destroy(const struct xt_tgdtor_param *par)
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{
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nf_ct_netns_put(par->net, par->family);
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}
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static unsigned int
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netmap_tg4(struct sk_buff *skb, const struct xt_action_param *par)
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{
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struct nf_conn *ct;
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enum ip_conntrack_info ctinfo;
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__be32 new_ip, netmask;
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const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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struct nf_nat_range newrange;
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NF_CT_ASSERT(xt_hooknum(par) == NF_INET_PRE_ROUTING ||
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xt_hooknum(par) == NF_INET_POST_ROUTING ||
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xt_hooknum(par) == NF_INET_LOCAL_OUT ||
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xt_hooknum(par) == NF_INET_LOCAL_IN);
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ct = nf_ct_get(skb, &ctinfo);
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netmask = ~(mr->range[0].min_ip ^ mr->range[0].max_ip);
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if (xt_hooknum(par) == NF_INET_PRE_ROUTING ||
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xt_hooknum(par) == NF_INET_LOCAL_OUT)
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new_ip = ip_hdr(skb)->daddr & ~netmask;
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else
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new_ip = ip_hdr(skb)->saddr & ~netmask;
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new_ip |= mr->range[0].min_ip & netmask;
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memset(&newrange.min_addr, 0, sizeof(newrange.min_addr));
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memset(&newrange.max_addr, 0, sizeof(newrange.max_addr));
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newrange.flags = mr->range[0].flags | NF_NAT_RANGE_MAP_IPS;
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newrange.min_addr.ip = new_ip;
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newrange.max_addr.ip = new_ip;
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newrange.min_proto = mr->range[0].min;
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newrange.max_proto = mr->range[0].max;
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/* Hand modified range to generic setup. */
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return nf_nat_setup_info(ct, &newrange, HOOK2MANIP(xt_hooknum(par)));
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}
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static int netmap_tg4_check(const struct xt_tgchk_param *par)
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{
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const struct nf_nat_ipv4_multi_range_compat *mr = par->targinfo;
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if (!(mr->range[0].flags & NF_NAT_RANGE_MAP_IPS)) {
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pr_debug("bad MAP_IPS.\n");
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return -EINVAL;
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}
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if (mr->rangesize != 1) {
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pr_debug("bad rangesize %u.\n", mr->rangesize);
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return -EINVAL;
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}
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return nf_ct_netns_get(par->net, par->family);
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}
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static struct xt_target netmap_tg_reg[] __read_mostly = {
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{
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.name = "NETMAP",
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.family = NFPROTO_IPV6,
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.revision = 0,
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.target = netmap_tg6,
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.targetsize = sizeof(struct nf_nat_range),
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.table = "nat",
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_POST_ROUTING) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_LOCAL_IN),
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.checkentry = netmap_tg6_checkentry,
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.destroy = netmap_tg_destroy,
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.me = THIS_MODULE,
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},
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{
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.name = "NETMAP",
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.family = NFPROTO_IPV4,
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.revision = 0,
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.target = netmap_tg4,
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.targetsize = sizeof(struct nf_nat_ipv4_multi_range_compat),
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.table = "nat",
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.hooks = (1 << NF_INET_PRE_ROUTING) |
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(1 << NF_INET_POST_ROUTING) |
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(1 << NF_INET_LOCAL_OUT) |
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(1 << NF_INET_LOCAL_IN),
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.checkentry = netmap_tg4_check,
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.destroy = netmap_tg_destroy,
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.me = THIS_MODULE,
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},
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};
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static int __init netmap_tg_init(void)
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{
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return xt_register_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
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}
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static void netmap_tg_exit(void)
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{
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xt_unregister_targets(netmap_tg_reg, ARRAY_SIZE(netmap_tg_reg));
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}
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module_init(netmap_tg_init);
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module_exit(netmap_tg_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Xtables: 1:1 NAT mapping of subnets");
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MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>");
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MODULE_ALIAS("ip6t_NETMAP");
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MODULE_ALIAS("ipt_NETMAP");
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