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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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/jhash.h>
12#include <linux/ip.h>
13#include <net/ipv6.h>
14
15#include <linux/netfilter/x_tables.h>
16#include <net/netfilter/nf_conntrack.h>
17#include <linux/netfilter/xt_cluster.h>
18
19static inline u32 nf_ct_orig_ipv4_src(const struct nf_conn *ct)
20{
21 return (__force u32)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
22}
23
24static inline const u32 *nf_ct_orig_ipv6_src(const struct nf_conn *ct)
25{
26 return (__force u32 *)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6;
27}
28
29static inline u_int32_t
30xt_cluster_hash_ipv4(u_int32_t ip, const struct xt_cluster_match_info *info)
31{
32 return jhash_1word(ip, info->hash_seed);
33}
34
35static inline u_int32_t
36xt_cluster_hash_ipv6(const void *ip, const struct xt_cluster_match_info *info)
37{
38 return jhash2(ip, NF_CT_TUPLE_L3SIZE / sizeof(__u32), info->hash_seed);
39}
40
41static inline u_int32_t
42xt_cluster_hash(const struct nf_conn *ct,
43 const struct xt_cluster_match_info *info)
44{
45 u_int32_t hash = 0;
46
47 switch(nf_ct_l3num(ct)) {
48 case AF_INET:
49 hash = xt_cluster_hash_ipv4(nf_ct_orig_ipv4_src(ct), info);
50 break;
51 case AF_INET6:
52 hash = xt_cluster_hash_ipv6(nf_ct_orig_ipv6_src(ct), info);
53 break;
54 default:
55 WARN_ON(1);
56 break;
57 }
58
59 return reciprocal_scale(hash, info->total_nodes);
60}
61
62static inline bool
63xt_cluster_ipv6_is_multicast(const struct in6_addr *addr)
64{
65 __be32 st = addr->s6_addr32[0];
66 return ((st & htonl(0xFF000000)) == htonl(0xFF000000));
67}
68
69static inline bool
70xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family)
71{
72 bool is_multicast = false;
73
74 switch(family) {
75 case NFPROTO_IPV4:
76 is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr);
77 break;
78 case NFPROTO_IPV6:
79 is_multicast =
80 xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr);
81 break;
82 default:
83 WARN_ON(1);
84 break;
85 }
86 return is_multicast;
87}
88
89static bool
90xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par)
91{
92 struct sk_buff *pskb = (struct sk_buff *)skb;
93 const struct xt_cluster_match_info *info = par->matchinfo;
94 const struct nf_conn *ct;
95 enum ip_conntrack_info ctinfo;
96 unsigned long hash;
97
98 /* This match assumes that all nodes see the same packets. This can be
99 * achieved if the switch that connects the cluster nodes support some
100 * sort of 'port mirroring'. However, if your switch does not support
101 * this, your cluster nodes can reply ARP request using a multicast MAC
102 * address. Thus, your switch will flood the same packets to the
103 * cluster nodes with the same multicast MAC address. Using a multicast
104 * link address is a RFC 1812 (section 3.3.2) violation, but this works
105 * fine in practise.
106 *
107 * Unfortunately, if you use the multicast MAC address, the link layer
108 * sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted
109 * by TCP and others for packets coming to this node. For that reason,
110 * this match mangles skbuff's pkt_type if it detects a packet
111 * addressed to a unicast address but using PACKET_MULTICAST. Yes, I
112 * know, matches should not alter packets, but we are doing this here
113 * because we would need to add a PKTTYPE target for this sole purpose.
114 */
115 if (!xt_cluster_is_multicast_addr(skb, xt_family(par)) &&
116 skb->pkt_type == PACKET_MULTICAST) {
117 pskb->pkt_type = PACKET_HOST;
118 }
119
120 ct = nf_ct_get(skb, &ctinfo);
121 if (ct == NULL)
122 return false;
123
124 if (nf_ct_is_untracked(ct))
125 return false;
126
127 if (ct->master)
128 hash = xt_cluster_hash(ct->master, info);
129 else
130 hash = xt_cluster_hash(ct, info);
131
132 return !!((1 << hash) & info->node_mask) ^
133 !!(info->flags & XT_CLUSTER_F_INV);
134}
135
136static int xt_cluster_mt_checkentry(const struct xt_mtchk_param *par)
137{
138 struct xt_cluster_match_info *info = par->matchinfo;
139
140 if (info->total_nodes > XT_CLUSTER_NODES_MAX) {
141 pr_info("you have exceeded the maximum "
142 "number of cluster nodes (%u > %u)\n",
143 info->total_nodes, XT_CLUSTER_NODES_MAX);
144 return -EINVAL;
145 }
146 if (info->node_mask >= (1ULL << info->total_nodes)) {
147 pr_info("this node mask cannot be "
148 "higher than the total number of nodes\n");
149 return -EDOM;
150 }
151 return 0;
152}
153
154static struct xt_match xt_cluster_match __read_mostly = {
155 .name = "cluster",
156 .family = NFPROTO_UNSPEC,
157 .match = xt_cluster_mt,
158 .checkentry = xt_cluster_mt_checkentry,
159 .matchsize = sizeof(struct xt_cluster_match_info),
160 .me = THIS_MODULE,
161};
162
163static int __init xt_cluster_mt_init(void)
164{
165 return xt_register_match(&xt_cluster_match);
166}
167
168static void __exit xt_cluster_mt_fini(void)
169{
170 xt_unregister_match(&xt_cluster_match);
171}
172
173MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
174MODULE_LICENSE("GPL");
175MODULE_DESCRIPTION("Xtables: hash-based cluster match");
176MODULE_ALIAS("ipt_cluster");
177MODULE_ALIAS("ip6t_cluster");
178module_init(xt_cluster_mt_init);
179module_exit(xt_cluster_mt_fini);
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9#include <linux/module.h>
10#include <linux/skbuff.h>
11#include <linux/jhash.h>
12#include <linux/ip.h>
13#include <net/ipv6.h>
14
15#include <linux/netfilter/x_tables.h>
16#include <net/netfilter/nf_conntrack.h>
17#include <linux/netfilter/xt_cluster.h>
18
19static inline u32 nf_ct_orig_ipv4_src(const struct nf_conn *ct)
20{
21 return (__force u32)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
22}
23
24static inline const u32 *nf_ct_orig_ipv6_src(const struct nf_conn *ct)
25{
26 return (__force u32 *)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6;
27}
28
29static inline u_int32_t
30xt_cluster_hash_ipv4(u_int32_t ip, const struct xt_cluster_match_info *info)
31{
32 return jhash_1word(ip, info->hash_seed);
33}
34
35static inline u_int32_t
36xt_cluster_hash_ipv6(const void *ip, const struct xt_cluster_match_info *info)
37{
38 return jhash2(ip, NF_CT_TUPLE_L3SIZE / sizeof(__u32), info->hash_seed);
39}
40
41static inline u_int32_t
42xt_cluster_hash(const struct nf_conn *ct,
43 const struct xt_cluster_match_info *info)
44{
45 u_int32_t hash = 0;
46
47 switch(nf_ct_l3num(ct)) {
48 case AF_INET:
49 hash = xt_cluster_hash_ipv4(nf_ct_orig_ipv4_src(ct), info);
50 break;
51 case AF_INET6:
52 hash = xt_cluster_hash_ipv6(nf_ct_orig_ipv6_src(ct), info);
53 break;
54 default:
55 WARN_ON(1);
56 break;
57 }
58 return (((u64)hash * info->total_nodes) >> 32);
59}
60
61static inline bool
62xt_cluster_ipv6_is_multicast(const struct in6_addr *addr)
63{
64 __be32 st = addr->s6_addr32[0];
65 return ((st & htonl(0xFF000000)) == htonl(0xFF000000));
66}
67
68static inline bool
69xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family)
70{
71 bool is_multicast = false;
72
73 switch(family) {
74 case NFPROTO_IPV4:
75 is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr);
76 break;
77 case NFPROTO_IPV6:
78 is_multicast =
79 xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr);
80 break;
81 default:
82 WARN_ON(1);
83 break;
84 }
85 return is_multicast;
86}
87
88static bool
89xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par)
90{
91 struct sk_buff *pskb = (struct sk_buff *)skb;
92 const struct xt_cluster_match_info *info = par->matchinfo;
93 const struct nf_conn *ct;
94 enum ip_conntrack_info ctinfo;
95 unsigned long hash;
96
97 /* This match assumes that all nodes see the same packets. This can be
98 * achieved if the switch that connects the cluster nodes support some
99 * sort of 'port mirroring'. However, if your switch does not support
100 * this, your cluster nodes can reply ARP request using a multicast MAC
101 * address. Thus, your switch will flood the same packets to the
102 * cluster nodes with the same multicast MAC address. Using a multicast
103 * link address is a RFC 1812 (section 3.3.2) violation, but this works
104 * fine in practise.
105 *
106 * Unfortunately, if you use the multicast MAC address, the link layer
107 * sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted
108 * by TCP and others for packets coming to this node. For that reason,
109 * this match mangles skbuff's pkt_type if it detects a packet
110 * addressed to a unicast address but using PACKET_MULTICAST. Yes, I
111 * know, matches should not alter packets, but we are doing this here
112 * because we would need to add a PKTTYPE target for this sole purpose.
113 */
114 if (!xt_cluster_is_multicast_addr(skb, par->family) &&
115 skb->pkt_type == PACKET_MULTICAST) {
116 pskb->pkt_type = PACKET_HOST;
117 }
118
119 ct = nf_ct_get(skb, &ctinfo);
120 if (ct == NULL)
121 return false;
122
123 if (nf_ct_is_untracked(ct))
124 return false;
125
126 if (ct->master)
127 hash = xt_cluster_hash(ct->master, info);
128 else
129 hash = xt_cluster_hash(ct, info);
130
131 return !!((1 << hash) & info->node_mask) ^
132 !!(info->flags & XT_CLUSTER_F_INV);
133}
134
135static int xt_cluster_mt_checkentry(const struct xt_mtchk_param *par)
136{
137 struct xt_cluster_match_info *info = par->matchinfo;
138
139 if (info->total_nodes > XT_CLUSTER_NODES_MAX) {
140 pr_info("you have exceeded the maximum "
141 "number of cluster nodes (%u > %u)\n",
142 info->total_nodes, XT_CLUSTER_NODES_MAX);
143 return -EINVAL;
144 }
145 if (info->node_mask >= (1ULL << info->total_nodes)) {
146 pr_info("this node mask cannot be "
147 "higher than the total number of nodes\n");
148 return -EDOM;
149 }
150 return 0;
151}
152
153static struct xt_match xt_cluster_match __read_mostly = {
154 .name = "cluster",
155 .family = NFPROTO_UNSPEC,
156 .match = xt_cluster_mt,
157 .checkentry = xt_cluster_mt_checkentry,
158 .matchsize = sizeof(struct xt_cluster_match_info),
159 .me = THIS_MODULE,
160};
161
162static int __init xt_cluster_mt_init(void)
163{
164 return xt_register_match(&xt_cluster_match);
165}
166
167static void __exit xt_cluster_mt_fini(void)
168{
169 xt_unregister_match(&xt_cluster_match);
170}
171
172MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
173MODULE_LICENSE("GPL");
174MODULE_DESCRIPTION("Xtables: hash-based cluster match");
175MODULE_ALIAS("ipt_cluster");
176MODULE_ALIAS("ip6t_cluster");
177module_init(xt_cluster_mt_init);
178module_exit(xt_cluster_mt_fini);