diff options
Diffstat (limited to 'net/ipv4/netfilter/iptable_mangle.c')
| -rw-r--r-- | net/ipv4/netfilter/iptable_mangle.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c new file mode 100644 index 00000000..aef5d1fb --- /dev/null +++ b/net/ipv4/netfilter/iptable_mangle.c @@ -0,0 +1,151 @@ +/* + * 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/netfilter_ipv4/ip_tables.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/slab.h> +#include <net/sock.h> +#include <net/route.h> +#include <linux/ip.h> +#include <net/ip.h> + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); +MODULE_DESCRIPTION("iptables mangle table"); + +#define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ + (1 << NF_INET_LOCAL_IN) | \ + (1 << NF_INET_FORWARD) | \ + (1 << NF_INET_LOCAL_OUT) | \ + (1 << NF_INET_POST_ROUTING)) + +static const struct xt_table packet_mangler = { + .name = "mangle", + .valid_hooks = MANGLE_VALID_HOOKS, + .me = THIS_MODULE, + .af = NFPROTO_IPV4, + .priority = NF_IP_PRI_MANGLE, +}; + +static unsigned int +ipt_mangle_out(struct sk_buff *skb, const struct net_device *out) +{ + unsigned int ret; + const struct iphdr *iph; + u_int8_t tos; + __be32 saddr, daddr; + u_int32_t mark; + + /* root is playing with raw sockets. */ + if (skb->len < sizeof(struct iphdr) || + ip_hdrlen(skb) < sizeof(struct iphdr)) + return NF_ACCEPT; + + /* Save things which could affect route */ + mark = skb->mark; + iph = ip_hdr(skb); + saddr = iph->saddr; + daddr = iph->daddr; + tos = iph->tos; + + ret = ipt_do_table(skb, NF_INET_LOCAL_OUT, NULL, out, + dev_net(out)->ipv4.iptable_mangle); + /* Reroute for ANY change. */ + if (ret != NF_DROP && ret != NF_STOLEN) { + iph = ip_hdr(skb); + + if (iph->saddr != saddr || + iph->daddr != daddr || + skb->mark != mark || + iph->tos != tos) + if (ip_route_me_harder(skb, RTN_UNSPEC)) + ret = NF_DROP; + } + + return ret; +} + +/* The work comes in here from netfilter.c. */ +static unsigned int +iptable_mangle_hook(unsigned int hook, + struct sk_buff *skb, + const struct net_device *in, + const struct net_device *out, + int (*okfn)(struct sk_buff *)) +{ + if (hook == NF_INET_LOCAL_OUT) + return ipt_mangle_out(skb, out); + if (hook == NF_INET_POST_ROUTING) + return ipt_do_table(skb, hook, in, out, + dev_net(out)->ipv4.iptable_mangle); + /* PREROUTING/INPUT/FORWARD: */ + return ipt_do_table(skb, hook, in, out, + dev_net(in)->ipv4.iptable_mangle); +} + +static struct nf_hook_ops *mangle_ops __read_mostly; + +static int __net_init iptable_mangle_net_init(struct net *net) +{ + struct ipt_replace *repl; + + repl = ipt_alloc_initial_table(&packet_mangler); + if (repl == NULL) + return -ENOMEM; + net->ipv4.iptable_mangle = + ipt_register_table(net, &packet_mangler, repl); + kfree(repl); + if (IS_ERR(net->ipv4.iptable_mangle)) + return PTR_ERR(net->ipv4.iptable_mangle); + return 0; +} + +static void __net_exit iptable_mangle_net_exit(struct net *net) +{ + ipt_unregister_table(net, net->ipv4.iptable_mangle); +} + +static struct pernet_operations iptable_mangle_net_ops = { + .init = iptable_mangle_net_init, + .exit = iptable_mangle_net_exit, +}; + +static int __init iptable_mangle_init(void) +{ + int ret; + + ret = register_pernet_subsys(&iptable_mangle_net_ops); + if (ret < 0) + return ret; + + /* Register hooks */ + mangle_ops = xt_hook_link(&packet_mangler, iptable_mangle_hook); + if (IS_ERR(mangle_ops)) { + ret = PTR_ERR(mangle_ops); + goto cleanup_table; + } + + return ret; + + cleanup_table: + unregister_pernet_subsys(&iptable_mangle_net_ops); + return ret; +} + +static void __exit iptable_mangle_fini(void) +{ + xt_hook_unlink(&packet_mangler, mangle_ops); + unregister_pernet_subsys(&iptable_mangle_net_ops); +} + +module_init(iptable_mangle_init); +module_exit(iptable_mangle_fini); |