Pablo Neira Ayuso | 0269ea4 | 2009-03-16 17:10:36 +0100 | [diff] [blame] | 1 | /* |
| 2 | * (C) 2008-2009 Pablo Neira Ayuso <pablo@netfilter.org> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | #include <linux/module.h> |
| 9 | #include <linux/skbuff.h> |
| 10 | #include <linux/jhash.h> |
| 11 | #include <linux/ip.h> |
| 12 | #include <net/ipv6.h> |
| 13 | |
| 14 | #include <linux/netfilter/x_tables.h> |
| 15 | #include <net/netfilter/nf_conntrack.h> |
| 16 | #include <linux/netfilter/xt_cluster.h> |
| 17 | |
| 18 | static inline u_int32_t nf_ct_orig_ipv4_src(const struct nf_conn *ct) |
| 19 | { |
| 20 | return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; |
| 21 | } |
| 22 | |
| 23 | static inline const void *nf_ct_orig_ipv6_src(const struct nf_conn *ct) |
| 24 | { |
| 25 | return ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6; |
| 26 | } |
| 27 | |
| 28 | static inline u_int32_t |
| 29 | xt_cluster_hash_ipv4(u_int32_t ip, const struct xt_cluster_match_info *info) |
| 30 | { |
| 31 | return jhash_1word(ip, info->hash_seed); |
| 32 | } |
| 33 | |
| 34 | static inline u_int32_t |
| 35 | xt_cluster_hash_ipv6(const void *ip, const struct xt_cluster_match_info *info) |
| 36 | { |
| 37 | return jhash2(ip, NF_CT_TUPLE_L3SIZE / sizeof(__u32), info->hash_seed); |
| 38 | } |
| 39 | |
| 40 | static inline u_int32_t |
| 41 | xt_cluster_hash(const struct nf_conn *ct, |
| 42 | const struct xt_cluster_match_info *info) |
| 43 | { |
| 44 | u_int32_t hash = 0; |
| 45 | |
| 46 | switch(nf_ct_l3num(ct)) { |
| 47 | case AF_INET: |
| 48 | hash = xt_cluster_hash_ipv4(nf_ct_orig_ipv4_src(ct), info); |
| 49 | break; |
| 50 | case AF_INET6: |
| 51 | hash = xt_cluster_hash_ipv6(nf_ct_orig_ipv6_src(ct), info); |
| 52 | break; |
| 53 | default: |
| 54 | WARN_ON(1); |
| 55 | break; |
| 56 | } |
| 57 | return (((u64)hash * info->total_nodes) >> 32); |
| 58 | } |
| 59 | |
| 60 | static inline bool |
Pablo Neira Ayuso | 424b86a | 2009-03-29 13:46:01 -0700 | [diff] [blame] | 61 | xt_cluster_ipv6_is_multicast(const struct in6_addr *addr) |
| 62 | { |
| 63 | __be32 st = addr->s6_addr32[0]; |
| 64 | return ((st & htonl(0xFF000000)) == htonl(0xFF000000)); |
| 65 | } |
| 66 | |
| 67 | static inline bool |
Pablo Neira Ayuso | 0269ea4 | 2009-03-16 17:10:36 +0100 | [diff] [blame] | 68 | xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family) |
| 69 | { |
| 70 | bool is_multicast = false; |
| 71 | |
| 72 | switch(family) { |
| 73 | case NFPROTO_IPV4: |
| 74 | is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr); |
| 75 | break; |
| 76 | case NFPROTO_IPV6: |
Pablo Neira Ayuso | 424b86a | 2009-03-29 13:46:01 -0700 | [diff] [blame] | 77 | is_multicast = |
| 78 | xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr); |
Pablo Neira Ayuso | 0269ea4 | 2009-03-16 17:10:36 +0100 | [diff] [blame] | 79 | break; |
| 80 | default: |
| 81 | WARN_ON(1); |
| 82 | break; |
| 83 | } |
| 84 | return is_multicast; |
| 85 | } |
| 86 | |
| 87 | static bool |
| 88 | xt_cluster_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
| 89 | { |
| 90 | struct sk_buff *pskb = (struct sk_buff *)skb; |
| 91 | const struct xt_cluster_match_info *info = par->matchinfo; |
| 92 | const struct nf_conn *ct; |
| 93 | enum ip_conntrack_info ctinfo; |
| 94 | unsigned long hash; |
| 95 | |
| 96 | /* This match assumes that all nodes see the same packets. This can be |
| 97 | * achieved if the switch that connects the cluster nodes support some |
| 98 | * sort of 'port mirroring'. However, if your switch does not support |
| 99 | * this, your cluster nodes can reply ARP request using a multicast MAC |
| 100 | * address. Thus, your switch will flood the same packets to the |
| 101 | * cluster nodes with the same multicast MAC address. Using a multicast |
| 102 | * link address is a RFC 1812 (section 3.3.2) violation, but this works |
| 103 | * fine in practise. |
| 104 | * |
| 105 | * Unfortunately, if you use the multicast MAC address, the link layer |
| 106 | * sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted |
| 107 | * by TCP and others for packets coming to this node. For that reason, |
| 108 | * this match mangles skbuff's pkt_type if it detects a packet |
| 109 | * addressed to a unicast address but using PACKET_MULTICAST. Yes, I |
| 110 | * know, matches should not alter packets, but we are doing this here |
| 111 | * because we would need to add a PKTTYPE target for this sole purpose. |
| 112 | */ |
| 113 | if (!xt_cluster_is_multicast_addr(skb, par->family) && |
| 114 | skb->pkt_type == PACKET_MULTICAST) { |
| 115 | pskb->pkt_type = PACKET_HOST; |
| 116 | } |
| 117 | |
| 118 | ct = nf_ct_get(skb, &ctinfo); |
| 119 | if (ct == NULL) |
| 120 | return false; |
| 121 | |
| 122 | if (ct == &nf_conntrack_untracked) |
| 123 | return false; |
| 124 | |
| 125 | if (ct->master) |
| 126 | hash = xt_cluster_hash(ct->master, info); |
| 127 | else |
| 128 | hash = xt_cluster_hash(ct, info); |
| 129 | |
| 130 | return !!((1 << hash) & info->node_mask) ^ |
| 131 | !!(info->flags & XT_CLUSTER_F_INV); |
| 132 | } |
| 133 | |
| 134 | static bool xt_cluster_mt_checkentry(const struct xt_mtchk_param *par) |
| 135 | { |
| 136 | struct xt_cluster_match_info *info = par->matchinfo; |
| 137 | |
Pablo Neira Ayuso | 280f37a | 2009-05-05 17:46:07 +0200 | [diff] [blame] | 138 | if (info->total_nodes > XT_CLUSTER_NODES_MAX) { |
| 139 | printk(KERN_ERR "xt_cluster: you have exceeded the maximum " |
| 140 | "number of cluster nodes (%u > %u)\n", |
| 141 | info->total_nodes, XT_CLUSTER_NODES_MAX); |
| 142 | return false; |
| 143 | } |
| 144 | if (info->node_mask >= (1ULL << info->total_nodes)) { |
Pablo Neira Ayuso | 0269ea4 | 2009-03-16 17:10:36 +0100 | [diff] [blame] | 145 | printk(KERN_ERR "xt_cluster: this node mask cannot be " |
| 146 | "higher than the total number of nodes\n"); |
| 147 | return false; |
| 148 | } |
| 149 | return true; |
| 150 | } |
| 151 | |
| 152 | static struct xt_match xt_cluster_match __read_mostly = { |
| 153 | .name = "cluster", |
| 154 | .family = NFPROTO_UNSPEC, |
| 155 | .match = xt_cluster_mt, |
| 156 | .checkentry = xt_cluster_mt_checkentry, |
| 157 | .matchsize = sizeof(struct xt_cluster_match_info), |
| 158 | .me = THIS_MODULE, |
| 159 | }; |
| 160 | |
| 161 | static int __init xt_cluster_mt_init(void) |
| 162 | { |
| 163 | return xt_register_match(&xt_cluster_match); |
| 164 | } |
| 165 | |
| 166 | static void __exit xt_cluster_mt_fini(void) |
| 167 | { |
| 168 | xt_unregister_match(&xt_cluster_match); |
| 169 | } |
| 170 | |
| 171 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); |
| 172 | MODULE_LICENSE("GPL"); |
| 173 | MODULE_DESCRIPTION("Xtables: hash-based cluster match"); |
| 174 | MODULE_ALIAS("ipt_cluster"); |
| 175 | MODULE_ALIAS("ip6t_cluster"); |
| 176 | module_init(xt_cluster_mt_init); |
| 177 | module_exit(xt_cluster_mt_fini); |