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![Florian Westphal](/assets/img/avatar_default.png)
For historical reasons x_tables still register tables by default in the initial namespace. Only newly created net namespaces add the hook on demand. This means that the init_net always pays hook cost, even if no filtering rules are added (e.g. only used inside a single netns). Note that the hooks are added even when 'iptables -L' is called. This is because there is no way to tell 'iptables -A' and 'iptables -L' apart at kernel level. The only solution would be to register the table, but delay hook registration until the first rule gets added (or policy gets changed). That however means that counters are not hooked either, so 'iptables -L' would always show 0-counters even when traffic is flowing which might be unexpected. This keeps table and hook registration consistent with what is already done in non-init netns: first iptables(-save) invocation registers both table and hooks. This applies the same solution adopted for ebtables. All tables register a template that contains the l3 family, the name and a constructor function that is called when the initial table has to be added. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
179 lines
3.8 KiB
C
179 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
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*
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* Based on Rusty Russell's IPv4 NAT code. Development of IPv6 NAT
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* funded by Astaro.
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*/
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/netfilter_ipv6.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/ipv6.h>
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#include <net/ipv6.h>
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#include <net/netfilter/nf_nat.h>
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struct ip6table_nat_pernet {
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struct nf_hook_ops *nf_nat_ops;
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};
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static unsigned int ip6table_nat_net_id __read_mostly;
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static const struct xt_table nf_nat_ipv6_table = {
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.name = "nat",
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.valid_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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.me = THIS_MODULE,
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.af = NFPROTO_IPV6,
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};
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static unsigned int ip6table_nat_do_chain(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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return ip6t_do_table(skb, state, priv);
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}
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static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
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{
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.hook = ip6table_nat_do_chain,
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.pf = NFPROTO_IPV6,
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.hooknum = NF_INET_PRE_ROUTING,
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.priority = NF_IP6_PRI_NAT_DST,
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},
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{
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.hook = ip6table_nat_do_chain,
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.pf = NFPROTO_IPV6,
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.hooknum = NF_INET_POST_ROUTING,
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.priority = NF_IP6_PRI_NAT_SRC,
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},
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{
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.hook = ip6table_nat_do_chain,
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.pf = NFPROTO_IPV6,
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.hooknum = NF_INET_LOCAL_OUT,
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.priority = NF_IP6_PRI_NAT_DST,
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},
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{
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.hook = ip6table_nat_do_chain,
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.pf = NFPROTO_IPV6,
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.hooknum = NF_INET_LOCAL_IN,
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.priority = NF_IP6_PRI_NAT_SRC,
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},
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};
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static int ip6t_nat_register_lookups(struct net *net)
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{
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struct ip6table_nat_pernet *xt_nat_net;
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struct nf_hook_ops *ops;
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struct xt_table *table;
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int i, ret;
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table = xt_find_table(net, NFPROTO_IPV6, "nat");
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if (WARN_ON_ONCE(!table))
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return -ENOENT;
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xt_nat_net = net_generic(net, ip6table_nat_net_id);
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ops = kmemdup(nf_nat_ipv6_ops, sizeof(nf_nat_ipv6_ops), GFP_KERNEL);
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if (!ops)
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return -ENOMEM;
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for (i = 0; i < ARRAY_SIZE(nf_nat_ipv6_ops); i++) {
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ops[i].priv = table;
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ret = nf_nat_ipv6_register_fn(net, &ops[i]);
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if (ret) {
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while (i)
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nf_nat_ipv6_unregister_fn(net, &ops[--i]);
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kfree(ops);
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return ret;
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}
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}
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xt_nat_net->nf_nat_ops = ops;
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return 0;
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}
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static void ip6t_nat_unregister_lookups(struct net *net)
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{
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struct ip6table_nat_pernet *xt_nat_net = net_generic(net, ip6table_nat_net_id);
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struct nf_hook_ops *ops = xt_nat_net->nf_nat_ops;
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int i;
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if (!ops)
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return;
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for (i = 0; i < ARRAY_SIZE(nf_nat_ipv6_ops); i++)
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nf_nat_ipv6_unregister_fn(net, &ops[i]);
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kfree(ops);
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}
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static int ip6table_nat_table_init(struct net *net)
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{
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struct ip6t_replace *repl;
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int ret;
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repl = ip6t_alloc_initial_table(&nf_nat_ipv6_table);
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if (repl == NULL)
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return -ENOMEM;
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ret = ip6t_register_table(net, &nf_nat_ipv6_table, repl,
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NULL);
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if (ret < 0) {
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kfree(repl);
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return ret;
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}
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ret = ip6t_nat_register_lookups(net);
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if (ret < 0)
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ip6t_unregister_table_exit(net, "nat");
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kfree(repl);
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return ret;
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}
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static void __net_exit ip6table_nat_net_pre_exit(struct net *net)
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{
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ip6t_nat_unregister_lookups(net);
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}
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static void __net_exit ip6table_nat_net_exit(struct net *net)
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{
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ip6t_unregister_table_exit(net, "nat");
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}
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static struct pernet_operations ip6table_nat_net_ops = {
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.pre_exit = ip6table_nat_net_pre_exit,
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.exit = ip6table_nat_net_exit,
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.id = &ip6table_nat_net_id,
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.size = sizeof(struct ip6table_nat_pernet),
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};
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static int __init ip6table_nat_init(void)
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{
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int ret = xt_register_template(&nf_nat_ipv6_table,
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ip6table_nat_table_init);
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if (ret < 0)
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return ret;
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ret = register_pernet_subsys(&ip6table_nat_net_ops);
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if (ret)
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xt_unregister_template(&nf_nat_ipv6_table);
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return ret;
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}
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static void __exit ip6table_nat_exit(void)
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{
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unregister_pernet_subsys(&ip6table_nat_net_ops);
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xt_unregister_template(&nf_nat_ipv6_table);
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}
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module_init(ip6table_nat_init);
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module_exit(ip6table_nat_exit);
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MODULE_LICENSE("GPL");
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