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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 | } | |
8fc54f68 DB |
58 | |
59 | return reciprocal_scale(hash, info->total_nodes); | |
0269ea49 PNA |
60 | } |
61 | ||
62 | static inline bool | |
63 | xt_cluster_is_multicast_addr(const struct sk_buff *skb, u_int8_t family) | |
64 | { | |
65 | bool is_multicast = false; | |
66 | ||
67 | switch(family) { | |
68 | case NFPROTO_IPV4: | |
69 | is_multicast = ipv4_is_multicast(ip_hdr(skb)->daddr); | |
70 | break; | |
71 | case NFPROTO_IPV6: | |
580c7d9e | 72 | is_multicast = ipv6_addr_is_multicast(&ipv6_hdr(skb)->daddr); |
0269ea49 PNA |
73 | break; |
74 | default: | |
75 | WARN_ON(1); | |
76 | break; | |
77 | } | |
78 | return is_multicast; | |
79 | } | |
80 | ||
81 | static bool | |
62fc8051 | 82 | xt_cluster_mt(const struct sk_buff *skb, struct xt_action_param *par) |
0269ea49 PNA |
83 | { |
84 | struct sk_buff *pskb = (struct sk_buff *)skb; | |
85 | const struct xt_cluster_match_info *info = par->matchinfo; | |
86 | const struct nf_conn *ct; | |
87 | enum ip_conntrack_info ctinfo; | |
88 | unsigned long hash; | |
89 | ||
90 | /* This match assumes that all nodes see the same packets. This can be | |
91 | * achieved if the switch that connects the cluster nodes support some | |
92 | * sort of 'port mirroring'. However, if your switch does not support | |
93 | * this, your cluster nodes can reply ARP request using a multicast MAC | |
94 | * address. Thus, your switch will flood the same packets to the | |
95 | * cluster nodes with the same multicast MAC address. Using a multicast | |
96 | * link address is a RFC 1812 (section 3.3.2) violation, but this works | |
97 | * fine in practise. | |
98 | * | |
99 | * Unfortunately, if you use the multicast MAC address, the link layer | |
100 | * sets skbuff's pkt_type to PACKET_MULTICAST, which is not accepted | |
101 | * by TCP and others for packets coming to this node. For that reason, | |
102 | * this match mangles skbuff's pkt_type if it detects a packet | |
103 | * addressed to a unicast address but using PACKET_MULTICAST. Yes, I | |
104 | * know, matches should not alter packets, but we are doing this here | |
105 | * because we would need to add a PKTTYPE target for this sole purpose. | |
106 | */ | |
613dbd95 | 107 | if (!xt_cluster_is_multicast_addr(skb, xt_family(par)) && |
0269ea49 PNA |
108 | skb->pkt_type == PACKET_MULTICAST) { |
109 | pskb->pkt_type = PACKET_HOST; | |
110 | } | |
111 | ||
112 | ct = nf_ct_get(skb, &ctinfo); | |
113 | if (ct == NULL) | |
114 | return false; | |
115 | ||
0269ea49 PNA |
116 | if (ct->master) |
117 | hash = xt_cluster_hash(ct->master, info); | |
118 | else | |
119 | hash = xt_cluster_hash(ct, info); | |
120 | ||
121 | return !!((1 << hash) & info->node_mask) ^ | |
122 | !!(info->flags & XT_CLUSTER_F_INV); | |
123 | } | |
124 | ||
b0f38452 | 125 | static int xt_cluster_mt_checkentry(const struct xt_mtchk_param *par) |
0269ea49 PNA |
126 | { |
127 | struct xt_cluster_match_info *info = par->matchinfo; | |
c1dc2912 | 128 | int ret; |
0269ea49 | 129 | |
280f37af | 130 | if (info->total_nodes > XT_CLUSTER_NODES_MAX) { |
b2606644 FW |
131 | pr_info_ratelimited("you have exceeded the maximum number of cluster nodes (%u > %u)\n", |
132 | info->total_nodes, XT_CLUSTER_NODES_MAX); | |
bd414ee6 | 133 | return -EINVAL; |
280f37af PNA |
134 | } |
135 | if (info->node_mask >= (1ULL << info->total_nodes)) { | |
b2606644 | 136 | pr_info_ratelimited("node mask cannot exceed total number of nodes\n"); |
4a5a5c73 | 137 | return -EDOM; |
0269ea49 | 138 | } |
c1dc2912 MW |
139 | |
140 | ret = nf_ct_netns_get(par->net, par->family); | |
141 | if (ret < 0) | |
142 | pr_info_ratelimited("cannot load conntrack support for proto=%u\n", | |
143 | par->family); | |
144 | return ret; | |
145 | } | |
146 | ||
147 | static void xt_cluster_mt_destroy(const struct xt_mtdtor_param *par) | |
148 | { | |
149 | nf_ct_netns_put(par->net, par->family); | |
0269ea49 PNA |
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), | |
c1dc2912 | 158 | .destroy = xt_cluster_mt_destroy, |
0269ea49 PNA |
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); |