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fdacd57c79
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>
117 lines
2.8 KiB
C
117 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x.
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*
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* Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
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* Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org>
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*/
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/slab.h>
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#include <net/ip.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("iptables filter table");
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#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \
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(1 << NF_INET_FORWARD) | \
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(1 << NF_INET_LOCAL_OUT))
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static const struct xt_table packet_filter = {
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.name = "filter",
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.valid_hooks = FILTER_VALID_HOOKS,
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.me = THIS_MODULE,
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.af = NFPROTO_IPV4,
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.priority = NF_IP_PRI_FILTER,
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};
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static unsigned int
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iptable_filter_hook(void *priv, struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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return ipt_do_table(skb, state, priv);
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}
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static struct nf_hook_ops *filter_ops __read_mostly;
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/* Default to forward because I got too much mail already. */
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static bool forward __read_mostly = true;
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module_param(forward, bool, 0000);
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static int iptable_filter_table_init(struct net *net)
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{
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struct ipt_replace *repl;
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int err;
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repl = ipt_alloc_initial_table(&packet_filter);
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if (repl == NULL)
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return -ENOMEM;
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/* Entry 1 is the FORWARD hook */
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((struct ipt_standard *)repl->entries)[1].target.verdict =
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forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
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err = ipt_register_table(net, &packet_filter, repl, filter_ops);
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kfree(repl);
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return err;
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}
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static int __net_init iptable_filter_net_init(struct net *net)
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{
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if (!forward)
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return iptable_filter_table_init(net);
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return 0;
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}
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static void __net_exit iptable_filter_net_pre_exit(struct net *net)
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{
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ipt_unregister_table_pre_exit(net, "filter");
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}
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static void __net_exit iptable_filter_net_exit(struct net *net)
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{
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ipt_unregister_table_exit(net, "filter");
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}
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static struct pernet_operations iptable_filter_net_ops = {
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.init = iptable_filter_net_init,
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.pre_exit = iptable_filter_net_pre_exit,
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.exit = iptable_filter_net_exit,
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};
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static int __init iptable_filter_init(void)
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{
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int ret = xt_register_template(&packet_filter,
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iptable_filter_table_init);
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if (ret < 0)
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return ret;
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filter_ops = xt_hook_ops_alloc(&packet_filter, iptable_filter_hook);
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if (IS_ERR(filter_ops)) {
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xt_unregister_template(&packet_filter);
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return PTR_ERR(filter_ops);
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}
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ret = register_pernet_subsys(&iptable_filter_net_ops);
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if (ret < 0) {
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xt_unregister_template(&packet_filter);
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kfree(filter_ops);
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return ret;
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}
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return 0;
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}
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static void __exit iptable_filter_fini(void)
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{
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unregister_pernet_subsys(&iptable_filter_net_ops);
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xt_unregister_template(&packet_filter);
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kfree(filter_ops);
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}
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module_init(iptable_filter_init);
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module_exit(iptable_filter_fini);
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