diff options
Diffstat (limited to 'net/ipv4/netfilter/iptable_filter.c')
-rw-r--r-- | net/ipv4/netfilter/iptable_filter.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/iptable_filter.c b/net/ipv4/netfilter/iptable_filter.c new file mode 100644 index 00000000..c37641e8 --- /dev/null +++ b/net/ipv4/netfilter/iptable_filter.c @@ -0,0 +1,121 @@ +/* + * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x. + * + * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling + * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + */ + +#include <linux/module.h> +#include <linux/moduleparam.h> +#include <linux/netfilter_ipv4/ip_tables.h> +#include <linux/slab.h> +#include <net/ip.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); +MODULE_DESCRIPTION("iptables filter table"); + +#define FILTER_VALID_HOOKS ((1 << NF_INET_LOCAL_IN) | \ + (1 << NF_INET_FORWARD) | \ + (1 << NF_INET_LOCAL_OUT)) + +static const struct xt_table packet_filter = { + .name = "filter", + .valid_hooks = FILTER_VALID_HOOKS, + .me = THIS_MODULE, + .af = NFPROTO_IPV4, + .priority = NF_IP_PRI_FILTER, +}; + +static unsigned int +iptable_filter_hook(unsigned int hook, struct sk_buff *skb, + const struct net_device *in, const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + const struct net *net; + + if (hook == NF_INET_LOCAL_OUT && + (skb->len < sizeof(struct iphdr) || + ip_hdrlen(skb) < sizeof(struct iphdr))) + /* root is playing with raw sockets. */ + return NF_ACCEPT; + + net = dev_net((in != NULL) ? in : out); + return ipt_do_table(skb, hook, in, out, net->ipv4.iptable_filter); +} + +static struct nf_hook_ops *filter_ops __read_mostly; + +/* Default to forward because I got too much mail already. */ +static int forward = NF_ACCEPT; +module_param(forward, bool, 0000); + +static int __net_init iptable_filter_net_init(struct net *net) +{ + struct ipt_replace *repl; + + repl = ipt_alloc_initial_table(&packet_filter); + if (repl == NULL) + return -ENOMEM; + /* Entry 1 is the FORWARD hook */ + ((struct ipt_standard *)repl->entries)[1].target.verdict = + -forward - 1; + + net->ipv4.iptable_filter = + ipt_register_table(net, &packet_filter, repl); + kfree(repl); + if (IS_ERR(net->ipv4.iptable_filter)) + return PTR_ERR(net->ipv4.iptable_filter); + return 0; +} + +static void __net_exit iptable_filter_net_exit(struct net *net) +{ + ipt_unregister_table(net, net->ipv4.iptable_filter); +} + +static struct pernet_operations iptable_filter_net_ops = { + .init = iptable_filter_net_init, + .exit = iptable_filter_net_exit, +}; + +static int __init iptable_filter_init(void) +{ + int ret; + + if (forward < 0 || forward > NF_MAX_VERDICT) { + pr_err("iptables forward must be 0 or 1\n"); + return -EINVAL; + } + + ret = register_pernet_subsys(&iptable_filter_net_ops); + if (ret < 0) + return ret; + + /* Register hooks */ + filter_ops = xt_hook_link(&packet_filter, iptable_filter_hook); + if (IS_ERR(filter_ops)) { + ret = PTR_ERR(filter_ops); + goto cleanup_table; + } + + return ret; + + cleanup_table: + unregister_pernet_subsys(&iptable_filter_net_ops); + return ret; +} + +static void __exit iptable_filter_fini(void) +{ + xt_hook_unlink(&packet_filter, filter_ops); + unregister_pernet_subsys(&iptable_filter_net_ops); +} + +module_init(iptable_filter_init); +module_exit(iptable_filter_fini); |