/* * (C) 2008-2009 Pablo Neira Ayuso <pablo@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. */ #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_t xt_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_t xt_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_t xt_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 (((u64)hash * info->total_nodes) >> 32); } static inline bool xt_cluster_ipv6_is_multicast(const struct in6_addr *addr) { __be32 st = addr->s6_addr32[0]; return ((st & htonl(0xFF000000)) == htonl(0xFF000000)); } static inline bool xt_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 = xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr); break; default: WARN_ON(1); break; } return is_multicast; } static bool xt_cluster_mt(const struct sk_buff *skb, const struct xt_match_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, par->family) && skb->pkt_type == PACKET_MULTICAST) { pskb->pkt_type = PACKET_HOST; } ct = nf_ct_get(skb, &ctinfo); if (ct == NULL) return false; if (ct == &nf_conntrack_untracked) 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 bool xt_cluster_mt_checkentry(const struct xt_mtchk_param *par) { struct xt_cluster_match_info *info = par->matchinfo; if (info->total_nodes > XT_CLUSTER_NODES_MAX) { printk(KERN_ERR "xt_cluster: you have exceeded the maximum " "number of cluster nodes (%u > %u)\n", info->total_nodes, XT_CLUSTER_NODES_MAX); return false; } if (info->node_mask >= (1ULL << info->total_nodes)) { printk(KERN_ERR "xt_cluster: this node mask cannot be " "higher than the total number of nodes\n"); return false; } return true; } static struct xt_match xt_cluster_match __read_mostly = { .name = "cluster", .family = NFPROTO_UNSPEC, .match = xt_cluster_mt, .checkentry = xt_cluster_mt_checkentry, .matchsize = sizeof(struct xt_cluster_match_info), .me = THIS_MODULE, }; static int __init xt_cluster_mt_init(void) { return xt_register_match(&xt_cluster_match); } static void __exit xt_cluster_mt_fini(void) { xt_unregister_match(&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);