diff options
Diffstat (limited to 'net/netfilter/xt_cluster.c')
| -rw-r--r-- | net/netfilter/xt_cluster.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/net/netfilter/xt_cluster.c b/net/netfilter/xt_cluster.c new file mode 100644 index 000000000000..6c4847662b85 --- /dev/null +++ b/net/netfilter/xt_cluster.c @@ -0,0 +1,171 @@ +/* + * (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_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->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); |