// SPDX-License-Identifier: GPL-2.0-only/* * (C) 2008-2009 Pablo Neira Ayuso <pablo@netfilter.org> */#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt#include <linux/module.h>#include <linux/skbuff.h>#include <linux/jhash.h>#include <linux/ip.h>#include <net/ipv6.h> #include <linux/netfilter/x_tables.h>#include <net/netfilter/nf_conntrack.h>#include <linux/netfilter/xt_cluster.h> static inline u32 nf_ct_orig_ipv4_src(const struct nf_conn *ct){	return (__force u32)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;} static inline const u32 *nf_ct_orig_ipv6_src(const struct nf_conn *ct){	return (__force u32 *)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6;} static inline u_int32_txt_cluster_hash_ipv4(u_int32_t ip, const struct xt_cluster_match_info *info){	return jhash_1word(ip, info->hash_seed);} static inline u_int32_txt_cluster_hash_ipv6(const void *ip, const struct xt_cluster_match_info *info){	return jhash2(ip, NF_CT_TUPLE_L3SIZE / sizeof(__u32), info->hash_seed);} static inline u_int32_txt_cluster_hash(const struct nf_conn *ct,		const struct xt_cluster_match_info *info){	u_int32_t hash = 0; 	switch(nf_ct_l3num(ct)) {	case AF_INET:		hash = xt_cluster_hash_ipv4(nf_ct_orig_ipv4_src(ct), info);		break;	case AF_INET6:		hash = xt_cluster_hash_ipv6(nf_ct_orig_ipv6_src(ct), info);		break;	default:		WARN_ON(1);		break;	} 	return reciprocal_scale(hash, info->total_nodes);} static inline boolxt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family){	bool is_multicast = false; 	switch(family) {	case NFPROTO_IPV4:		is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr);		break;	case NFPROTO_IPV6:		is_multicast = ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr);		break;	default:		WARN_ON(1);		break;	}	return is_multicast;} static boolxt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par){	struct sk_buff *pskb = (struct sk_buff *)skb;	const struct xt_cluster_match_info *info = par->matchinfo;	const struct nf_conn *ct;	enum ip_conntrack_info ctinfo;	unsigned long hash; 	/* This match assumes that all nodes see the same packets. This can be	 * achieved if the switch that connects the cluster nodes support some	 * sort of 'port mirroring'. However, if your switch does not support	 * this, your cluster nodes can reply ARP request using a multicast MAC	 * address. Thus, your switch will flood the same packets to the	 * cluster nodes with the same multicast MAC address. Using a multicast	 * link address is a RFC 1812 (section 3.3.2) violation, but this works	 * fine in practise.	 *	 * Unfortunately, if you use the multicast MAC address, the link layer	 * sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted	 * by TCP and others for packets coming to this node. For that reason,	 * this match mangles skbuff's pkt_type if it detects a packet	 * addressed to a unicast address but using PACKET_MULTICAST. Yes, I	 * know, matches should not alter packets, but we are doing this here	 * because we would need to add a PKTTYPE target for this sole purpose.	 */	if (!xt_cluster_is_multicast_addr(skb, xt_family(par)) &&	    skb->pkt_type == PACKET_MULTICAST) {	    	pskb->pkt_type = PACKET_HOST;	} 	ct = nf_ct_get(skb, &ctinfo);	if (!ct || nf_ct_is_template(ct))		return false; 	if (ct->master)		hash = xt_cluster_hash(ct->master, info);	else		hash = xt_cluster_hash(ct, info); 	return !!((1 << hash) & info->node_mask) ^	       !!(info->flags & XT_CLUSTER_F_INV);} static int xt_cluster_mt_checkentry(const struct xt_mtchk_param *par){	struct xt_cluster_match_info *info = par->matchinfo;	int ret; 	if (info->total_nodes > XT_CLUSTER_NODES_MAX) {		pr_info_ratelimited("you have exceeded the maximum number of cluster nodes (%u > %u)\n",				    info->total_nodes, XT_CLUSTER_NODES_MAX);		return -EINVAL;	}	if (info->node_mask >= (1ULL << info->total_nodes)) {		pr_info_ratelimited("node mask cannot exceed total number of nodes\n");		return -EDOM;	} 	ret = nf_ct_netns_get(par->net, par->family);	if (ret < 0)		pr_info_ratelimited("cannot load conntrack support for proto=%u\n",				    par->family);	return ret;} static void xt_cluster_mt_destroy(const struct xt_mtdtor_param *par){	nf_ct_netns_put(par->net, par->family);} static struct xt_match xt_cluster_match[] __read_mostly = {	{		.name		= "cluster",		.family		= NFPROTO_IPV4,		.match		= xt_cluster_mt,		.checkentry	= xt_cluster_mt_checkentry,		.matchsize	= sizeof(struct xt_cluster_match_info),		.destroy	= xt_cluster_mt_destroy,		.me		= THIS_MODULE,	},#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)	{		.name		= "cluster",		.family		= NFPROTO_IPV6,		.match		= xt_cluster_mt,		.checkentry	= xt_cluster_mt_checkentry,		.matchsize	= sizeof(struct xt_cluster_match_info),		.destroy	= xt_cluster_mt_destroy,		.me		= THIS_MODULE,	},#endif}; static int __init xt_cluster_mt_init(void){	return xt_register_matches(xt_cluster_match, ARRAY_SIZE(xt_cluster_match));} static void __exit xt_cluster_mt_fini(void){	xt_unregister_matches(xt_cluster_match, ARRAY_SIZE(xt_cluster_match));} MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");MODULE_LICENSE("GPL");MODULE_DESCRIPTION("Xtables: hash-based cluster match");MODULE_ALIAS("ipt_cluster");MODULE_ALIAS("ip6t_cluster");module_init(xt_cluster_mt_init);module_exit(xt_cluster_mt_fini);