| /* |
| * This is a module which is used for rejecting packets. |
| */ |
| |
| /* (C) 1999-2001 Paul `Rusty' Russell |
| * (C) 2002-2004 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. |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/slab.h> |
| #include <linux/ip.h> |
| #include <linux/udp.h> |
| #include <linux/icmp.h> |
| #include <net/icmp.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter_ipv4/ipt_REJECT.h> |
| #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER) |
| #include <linux/netfilter_bridge.h> |
| #endif |
| |
| #include <net/netfilter/ipv4/nf_reject.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); |
| MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4"); |
| |
| static unsigned int |
| reject_tg(struct sk_buff *skb, const struct xt_action_param *par) |
| { |
| const struct ipt_reject_info *reject = par->targinfo; |
| int hook = par->hooknum; |
| |
| switch (reject->with) { |
| case IPT_ICMP_NET_UNREACHABLE: |
| nf_send_unreach(skb, ICMP_NET_UNREACH, hook); |
| break; |
| case IPT_ICMP_HOST_UNREACHABLE: |
| nf_send_unreach(skb, ICMP_HOST_UNREACH, hook); |
| break; |
| case IPT_ICMP_PROT_UNREACHABLE: |
| nf_send_unreach(skb, ICMP_PROT_UNREACH, hook); |
| break; |
| case IPT_ICMP_PORT_UNREACHABLE: |
| nf_send_unreach(skb, ICMP_PORT_UNREACH, hook); |
| break; |
| case IPT_ICMP_NET_PROHIBITED: |
| nf_send_unreach(skb, ICMP_NET_ANO, hook); |
| break; |
| case IPT_ICMP_HOST_PROHIBITED: |
| nf_send_unreach(skb, ICMP_HOST_ANO, hook); |
| break; |
| case IPT_ICMP_ADMIN_PROHIBITED: |
| nf_send_unreach(skb, ICMP_PKT_FILTERED, hook); |
| break; |
| case IPT_TCP_RESET: |
| nf_send_reset(par->net, skb, hook); |
| case IPT_ICMP_ECHOREPLY: |
| /* Doesn't happen. */ |
| break; |
| } |
| |
| return NF_DROP; |
| } |
| |
| static int reject_tg_check(const struct xt_tgchk_param *par) |
| { |
| const struct ipt_reject_info *rejinfo = par->targinfo; |
| const struct ipt_entry *e = par->entryinfo; |
| |
| if (rejinfo->with == IPT_ICMP_ECHOREPLY) { |
| pr_info("ECHOREPLY no longer supported.\n"); |
| return -EINVAL; |
| } else if (rejinfo->with == IPT_TCP_RESET) { |
| /* Must specify that it's a TCP packet */ |
| if (e->ip.proto != IPPROTO_TCP || |
| (e->ip.invflags & XT_INV_PROTO)) { |
| pr_info("TCP_RESET invalid for non-tcp\n"); |
| return -EINVAL; |
| } |
| } |
| return 0; |
| } |
| |
| static struct xt_target reject_tg_reg __read_mostly = { |
| .name = "REJECT", |
| .family = NFPROTO_IPV4, |
| .target = reject_tg, |
| .targetsize = sizeof(struct ipt_reject_info), |
| .table = "filter", |
| .hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) | |
| (1 << NF_INET_LOCAL_OUT), |
| .checkentry = reject_tg_check, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init reject_tg_init(void) |
| { |
| return xt_register_target(&reject_tg_reg); |
| } |
| |
| static void __exit reject_tg_exit(void) |
| { |
| xt_unregister_target(&reject_tg_reg); |
| } |
| |
| module_init(reject_tg_init); |
| module_exit(reject_tg_exit); |