![Florian Westphal](/assets/img/avatar_default.png)
delay hook registration until the table is being requested inside a namespace. Historically, a particular table (iptables mangle, ip6tables filter, etc) was registered on module load. When netns support was added to iptables only the ip/ip6tables ruleset was made namespace aware, not the actual hook points. This means f.e. that when ipt_filter table/module is loaded on a system, then each namespace on that system has an (empty) iptables filter ruleset. In other words, if a namespace sends a packet, such skb is 'caught' by netfilter machinery and fed to hooking points for that table (i.e. INPUT, FORWARD, etc). Thanks to Eric Biederman, hooks are no longer global, but per namespace. This means that we can avoid allocation of empty ruleset in a namespace and defer hook registration until we need the functionality. We register a tables hook entry points ONLY in the initial namespace. When an iptables get/setockopt is issued inside a given namespace, we check if the table is found in the per-namespace list. If not, we attempt to find it in the initial namespace, and, if found, create an empty default table in the requesting namespace and register the needed hooks. Hook points are destroyed only once namespace is deleted, there is no 'usage count' (it makes no sense since there is no 'remove table' operation in xtables api). Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
115 lines
2.9 KiB
C
115 lines
2.9 KiB
C
/*
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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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* 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/module.h>
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#include <linux/moduleparam.h>
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#include <linux/netfilter_ipv6/ip6_tables.h>
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#include <linux/slab.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("ip6tables 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 int __net_init ip6table_filter_table_init(struct net *net);
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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_IPV6,
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.priority = NF_IP6_PRI_FILTER,
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.table_init = ip6table_filter_table_init,
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};
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/* The work comes in here from netfilter.c. */
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static unsigned int
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ip6table_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 ip6t_do_table(skb, state, state->net->ipv6.ip6table_filter);
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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 = true;
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module_param(forward, bool, 0000);
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static int __net_init ip6table_filter_table_init(struct net *net)
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{
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struct ip6t_replace *repl;
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int err;
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if (net->ipv6.ip6table_filter)
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return 0;
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repl = ip6t_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 ip6t_standard *)repl->entries)[1].target.verdict =
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forward ? -NF_ACCEPT - 1 : -NF_DROP - 1;
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err = ip6t_register_table(net, &packet_filter, repl, filter_ops,
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&net->ipv6.ip6table_filter);
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kfree(repl);
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return err;
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}
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static int __net_init ip6table_filter_net_init(struct net *net)
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{
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if (net == &init_net || !forward)
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return ip6table_filter_table_init(net);
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return 0;
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}
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static void __net_exit ip6table_filter_net_exit(struct net *net)
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{
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if (!net->ipv6.ip6table_filter)
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return;
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ip6t_unregister_table(net, net->ipv6.ip6table_filter, filter_ops);
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net->ipv6.ip6table_filter = NULL;
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}
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static struct pernet_operations ip6table_filter_net_ops = {
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.init = ip6table_filter_net_init,
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.exit = ip6table_filter_net_exit,
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};
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static int __init ip6table_filter_init(void)
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{
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int ret;
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filter_ops = xt_hook_ops_alloc(&packet_filter, ip6table_filter_hook);
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if (IS_ERR(filter_ops))
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return PTR_ERR(filter_ops);
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ret = register_pernet_subsys(&ip6table_filter_net_ops);
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if (ret < 0)
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kfree(filter_ops);
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return ret;
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}
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static void __exit ip6table_filter_fini(void)
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{
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unregister_pernet_subsys(&ip6table_filter_net_ops);
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kfree(filter_ops);
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}
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module_init(ip6table_filter_init);
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module_exit(ip6table_filter_fini);
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