--- /dev/null
+/*
+ * (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.
+ */
+#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_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 reciprocal_scale(hash, info->total_nodes);
+}
+
+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, 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, par->family) &&
+ skb->pkt_type == PACKET_MULTICAST) {
+ pskb->pkt_type = PACKET_HOST;
+ }
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct == NULL)
+ return false;
+
+ if (nf_ct_is_untracked(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;
+
+ if (info->total_nodes > XT_CLUSTER_NODES_MAX) {
+ pr_info("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("this node mask cannot be "
+ "higher than the total number of nodes\n");
+ return -EDOM;
+ }
+ return 0;
+}
+
+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);
Code Review / kvmfornfv.git / blobdiff