// SPDX-License-Identifier: GPL-2.0-only
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/*
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* This is a module which is used for rejecting packets.
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*/
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/* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/ip.h>
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#include <linux/udp.h>
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#include <linux/icmp.h>
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#include <net/icmp.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_REJECT.h>
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#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
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#include <linux/netfilter_bridge.h>
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#endif
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#include <net/netfilter/ipv4/nf_reject.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>");
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MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv4");
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static unsigned int
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reject_tg(struct sk_buff *skb, const struct xt_action_param *par)
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{
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const struct ipt_reject_info *reject = par->targinfo;
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int hook = xt_hooknum(par);
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switch (reject->with) {
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case IPT_ICMP_NET_UNREACHABLE:
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nf_send_unreach(skb, ICMP_NET_UNREACH, hook);
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break;
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case IPT_ICMP_HOST_UNREACHABLE:
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nf_send_unreach(skb, ICMP_HOST_UNREACH, hook);
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break;
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case IPT_ICMP_PROT_UNREACHABLE:
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nf_send_unreach(skb, ICMP_PROT_UNREACH, hook);
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break;
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case IPT_ICMP_PORT_UNREACHABLE:
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nf_send_unreach(skb, ICMP_PORT_UNREACH, hook);
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break;
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case IPT_ICMP_NET_PROHIBITED:
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nf_send_unreach(skb, ICMP_NET_ANO, hook);
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break;
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case IPT_ICMP_HOST_PROHIBITED:
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nf_send_unreach(skb, ICMP_HOST_ANO, hook);
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break;
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case IPT_ICMP_ADMIN_PROHIBITED:
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nf_send_unreach(skb, ICMP_PKT_FILTERED, hook);
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break;
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case IPT_TCP_RESET:
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nf_send_reset(xt_net(par), skb, hook);
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case IPT_ICMP_ECHOREPLY:
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/* Doesn't happen. */
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break;
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}
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return NF_DROP;
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}
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static int reject_tg_check(const struct xt_tgchk_param *par)
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{
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const struct ipt_reject_info *rejinfo = par->targinfo;
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const struct ipt_entry *e = par->entryinfo;
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if (rejinfo->with == IPT_ICMP_ECHOREPLY) {
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pr_info_ratelimited("ECHOREPLY no longer supported.\n");
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return -EINVAL;
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} else if (rejinfo->with == IPT_TCP_RESET) {
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/* Must specify that it's a TCP packet */
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if (e->ip.proto != IPPROTO_TCP ||
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(e->ip.invflags & XT_INV_PROTO)) {
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pr_info_ratelimited("TCP_RESET invalid for non-tcp\n");
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return -EINVAL;
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}
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}
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return 0;
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}
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static struct xt_target reject_tg_reg __read_mostly = {
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.name = "REJECT",
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.family = NFPROTO_IPV4,
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.target = reject_tg,
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.targetsize = sizeof(struct ipt_reject_info),
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.table = "filter",
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.hooks = (1 << NF_INET_LOCAL_IN) | (1 << NF_INET_FORWARD) |
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(1 << NF_INET_LOCAL_OUT),
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.checkentry = reject_tg_check,
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.me = THIS_MODULE,
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};
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static int __init reject_tg_init(void)
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{
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return xt_register_target(&reject_tg_reg);
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}
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static void __exit reject_tg_exit(void)
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{
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xt_unregister_target(&reject_tg_reg);
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}
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module_init(reject_tg_init);
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module_exit(reject_tg_exit);
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