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- // SPDX-License-Identifier: GPL-2.0-only
- /*
- * 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>
- */
- #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 = xt_hooknum(par);
- 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(xt_net(par), 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_ratelimited("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_ratelimited("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);
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