| /* |
| * (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 u_int32_t nf_ct_orig_ipv4_src(const struct nf_conn *ct) |
| { |
| return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; |
| } |
| |
| static inline const void *nf_ct_orig_ipv6_src(const struct nf_conn *ct) |
| { |
| return 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_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_type(&ipv6_hdr(skb)->daddr) & |
| IPV6_ADDR_MULTICAST; |
| 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->node_mask >= (1 << 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); |