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Diffstat (limited to '')
-rw-r--r-- | net/ipv4/netfilter/iptable_mangle.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/iptable_mangle.c b/net/ipv4/netfilter/iptable_mangle.c new file mode 100644 index 000000000..3abb430af --- /dev/null +++ b/net/ipv4/netfilter/iptable_mangle.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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> + */ +#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(void *priv, struct sk_buff *skb, const struct nf_hook_state *state) +{ + unsigned int ret; + const struct iphdr *iph; + u_int8_t tos; + __be32 saddr, daddr; + u_int32_t mark; + int err; + + /* 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(priv, skb, state); + /* 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) { + err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC); + if (err < 0) + ret = NF_DROP_ERR(err); + } + } + + return ret; +} + +/* The work comes in here from netfilter.c. */ +static unsigned int +iptable_mangle_hook(void *priv, + struct sk_buff *skb, + const struct nf_hook_state *state) +{ + if (state->hook == NF_INET_LOCAL_OUT) + return ipt_mangle_out(priv, skb, state); + return ipt_do_table(priv, skb, state); +} + +static struct nf_hook_ops *mangle_ops __read_mostly; +static int iptable_mangle_table_init(struct net *net) +{ + struct ipt_replace *repl; + int ret; + + repl = ipt_alloc_initial_table(&packet_mangler); + if (repl == NULL) + return -ENOMEM; + ret = ipt_register_table(net, &packet_mangler, repl, mangle_ops); + kfree(repl); + return ret; +} + +static void __net_exit iptable_mangle_net_pre_exit(struct net *net) +{ + ipt_unregister_table_pre_exit(net, "mangle"); +} + +static void __net_exit iptable_mangle_net_exit(struct net *net) +{ + ipt_unregister_table_exit(net, "mangle"); +} + +static struct pernet_operations iptable_mangle_net_ops = { + .pre_exit = iptable_mangle_net_pre_exit, + .exit = iptable_mangle_net_exit, +}; + +static int __init iptable_mangle_init(void) +{ + int ret = xt_register_template(&packet_mangler, + iptable_mangle_table_init); + if (ret < 0) + return ret; + + mangle_ops = xt_hook_ops_alloc(&packet_mangler, iptable_mangle_hook); + if (IS_ERR(mangle_ops)) { + xt_unregister_template(&packet_mangler); + ret = PTR_ERR(mangle_ops); + return ret; + } + + ret = register_pernet_subsys(&iptable_mangle_net_ops); + if (ret < 0) { + xt_unregister_template(&packet_mangler); + kfree(mangle_ops); + return ret; + } + + return ret; +} + +static void __exit iptable_mangle_fini(void) +{ + unregister_pernet_subsys(&iptable_mangle_net_ops); + xt_unregister_template(&packet_mangler); + kfree(mangle_ops); +} + +module_init(iptable_mangle_init); +module_exit(iptable_mangle_fini); |