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>
101 lines
2.3 KiB
C
101 lines
2.3 KiB
C
/*
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* 'raw' table, which is the very first hooked in at PRE_ROUTING and LOCAL_OUT .
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*
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* Copyright (C) 2003 Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
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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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#define RAW_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | (1 << NF_INET_LOCAL_OUT))
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static int __net_init iptable_raw_table_init(struct net *net);
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static const struct xt_table packet_raw = {
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.name = "raw",
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.valid_hooks = RAW_VALID_HOOKS,
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.me = THIS_MODULE,
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.af = NFPROTO_IPV4,
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.priority = NF_IP_PRI_RAW,
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.table_init = iptable_raw_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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iptable_raw_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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/* root 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_raw);
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}
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static struct nf_hook_ops *rawtable_ops __read_mostly;
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static int __net_init iptable_raw_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_raw)
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return 0;
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repl = ipt_alloc_initial_table(&packet_raw);
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if (repl == NULL)
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return -ENOMEM;
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ret = ipt_register_table(net, &packet_raw, repl, rawtable_ops,
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&net->ipv4.iptable_raw);
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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_raw_net_exit(struct net *net)
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{
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if (!net->ipv4.iptable_raw)
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return;
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ipt_unregister_table(net, net->ipv4.iptable_raw, rawtable_ops);
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net->ipv4.iptable_raw = NULL;
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}
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static struct pernet_operations iptable_raw_net_ops = {
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.exit = iptable_raw_net_exit,
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};
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static int __init iptable_raw_init(void)
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{
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int ret;
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rawtable_ops = xt_hook_ops_alloc(&packet_raw, iptable_raw_hook);
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if (IS_ERR(rawtable_ops))
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return PTR_ERR(rawtable_ops);
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ret = register_pernet_subsys(&iptable_raw_net_ops);
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if (ret < 0) {
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kfree(rawtable_ops);
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return ret;
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}
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ret = iptable_raw_table_init(&init_net);
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if (ret) {
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unregister_pernet_subsys(&iptable_raw_net_ops);
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kfree(rawtable_ops);
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}
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return ret;
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}
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static void __exit iptable_raw_fini(void)
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{
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unregister_pernet_subsys(&iptable_raw_net_ops);
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kfree(rawtable_ops);
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}
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module_init(iptable_raw_init);
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module_exit(iptable_raw_fini);
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MODULE_LICENSE("GPL");
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