b9e69e1273
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>
118 lines
3 KiB
C
118 lines
3 KiB
C
/*
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* "security" table
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*
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* This is for use by Mandatory Access Control (MAC) security models,
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* which need to be able to manage security policy in separate context
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* to DAC.
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*
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* Based on iptable_mangle.c
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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 <at> netfilter.org>
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* Copyright (C) 2008 Red Hat, Inc., James Morris <jmorris <at> redhat.com>
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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/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("James Morris <jmorris <at> redhat.com>");
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MODULE_DESCRIPTION("iptables security table, for MAC rules");
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#define SECURITY_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 iptable_security_table_init(struct net *net);
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static const struct xt_table security_table = {
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.name = "security",
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.valid_hooks = SECURITY_VALID_HOOKS,
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.me = THIS_MODULE,
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.af = NFPROTO_IPV4,
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.priority = NF_IP_PRI_SECURITY,
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.table_init = iptable_security_table_init,
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};
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static unsigned int
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iptable_security_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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if (state->hook == NF_INET_LOCAL_OUT &&
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(skb->len < sizeof(struct iphdr) ||
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ip_hdrlen(skb) < sizeof(struct iphdr)))
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/* Somebody is playing with raw sockets. */
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return NF_ACCEPT;
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return ipt_do_table(skb, state, state->net->ipv4.iptable_security);
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}
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static struct nf_hook_ops *sectbl_ops __read_mostly;
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static int __net_init iptable_security_table_init(struct net *net)
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{
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struct ipt_replace *repl;
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int ret;
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if (net->ipv4.iptable_security)
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return 0;
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repl = ipt_alloc_initial_table(&security_table);
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if (repl == NULL)
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return -ENOMEM;
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ret = ipt_register_table(net, &security_table, repl, sectbl_ops,
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&net->ipv4.iptable_security);
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kfree(repl);
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return ret;
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}
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static void __net_exit iptable_security_net_exit(struct net *net)
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{
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if (!net->ipv4.iptable_security)
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return;
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ipt_unregister_table(net, net->ipv4.iptable_security, sectbl_ops);
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net->ipv4.iptable_security = NULL;
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}
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static struct pernet_operations iptable_security_net_ops = {
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.exit = iptable_security_net_exit,
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};
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static int __init iptable_security_init(void)
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{
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int ret;
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sectbl_ops = xt_hook_ops_alloc(&security_table, iptable_security_hook);
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if (IS_ERR(sectbl_ops))
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return PTR_ERR(sectbl_ops);
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ret = register_pernet_subsys(&iptable_security_net_ops);
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if (ret < 0) {
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kfree(sectbl_ops);
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return ret;
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}
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ret = iptable_security_table_init(&init_net);
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if (ret) {
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unregister_pernet_subsys(&iptable_security_net_ops);
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kfree(sectbl_ops);
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}
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return ret;
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}
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static void __exit iptable_security_fini(void)
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{
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unregister_pernet_subsys(&iptable_security_net_ops);
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kfree(sectbl_ops);
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}
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module_init(iptable_security_init);
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module_exit(iptable_security_fini);
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