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0269ea49 PNA |
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 | */ | |
8bee4bad | 8 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
0269ea49 PNA |
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 | ||
f9ffc312 | 19 | static inline u32 nf_ct_orig_ipv4_src(const struct nf_conn *ct) |
0269ea49 | 20 | { |
f9ffc312 | 21 | return (__force u32)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; |
0269ea49 PNA |
22 | } |
23 | ||
f9ffc312 | 24 | static inline const u32 *nf_ct_orig_ipv6_src(const struct nf_conn *ct) |
0269ea49 | 25 | { |
f9ffc312 | 26 | return (__force u32 *)ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip6; |
0269ea49 PNA |
27 | } |
28 | ||
29 | static inline u_int32_t | |
30 | xt_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 | ||
35 | static inline u_int32_t | |
36 | xt_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 | ||
41 | static inline u_int32_t | |
42 | xt_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 | ||
424b86a6 PNA |
61 | static inline bool |
62 | xt_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 | ||
0269ea49 PNA |
68 | static inline bool |
69 | xt_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: | |
424b86a6 PNA |
78 | is_multicast = |
79 | xt_cluster_ipv6_is_multicast(&ipv6_hdr(skb)->daddr); | |
0269ea49 PNA |
80 | break; |
81 | default: | |
82 | WARN_ON(1); | |
83 | break; | |
84 | } | |
85 | return is_multicast; | |
86 | } | |
87 | ||
88 | static bool | |
62fc8051 | 89 | xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par) |
0269ea49 PNA |
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 (ct == &nf_conntrack_untracked) | |
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 | ||
b0f38452 | 135 | static int xt_cluster_mt_checkentry(const struct xt_mtchk_param *par) |
0269ea49 PNA |
136 | { |
137 | struct xt_cluster_match_info *info = par->matchinfo; | |
138 | ||
280f37af | 139 | if (info->total_nodes > XT_CLUSTER_NODES_MAX) { |
8bee4bad JE |
140 | pr_info("you have exceeded the maximum " |
141 | "number of cluster nodes (%u > %u)\n", | |
142 | info->total_nodes, XT_CLUSTER_NODES_MAX); | |
bd414ee6 | 143 | return -EINVAL; |
280f37af PNA |
144 | } |
145 | if (info->node_mask >= (1ULL << info->total_nodes)) { | |
8bee4bad JE |
146 | pr_info("this node mask cannot be " |
147 | "higher than the total number of nodes\n"); | |
4a5a5c73 | 148 | return -EDOM; |
0269ea49 | 149 | } |
bd414ee6 | 150 | return 0; |
0269ea49 PNA |
151 | } |
152 | ||
153 | static 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 | ||
162 | static int __init xt_cluster_mt_init(void) | |
163 | { | |
164 | return xt_register_match(&xt_cluster_match); | |
165 | } | |
166 | ||
167 | static void __exit xt_cluster_mt_fini(void) | |
168 | { | |
169 | xt_unregister_match(&xt_cluster_match); | |
170 | } | |
171 | ||
172 | MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>"); | |
173 | MODULE_LICENSE("GPL"); | |
174 | MODULE_DESCRIPTION("Xtables: hash-based cluster match"); | |
175 | MODULE_ALIAS("ipt_cluster"); | |
176 | MODULE_ALIAS("ip6t_cluster"); | |
177 | module_init(xt_cluster_mt_init); | |
178 | module_exit(xt_cluster_mt_fini); |