1370786f9SJan Engelhardt /*
2370786f9SJan Engelhardt * netfilter module to limit the number of parallel tcp
3370786f9SJan Engelhardt * connections per IP address.
4370786f9SJan Engelhardt * (c) 2000 Gerd Knorr <kraxel@bytesex.org>
5370786f9SJan Engelhardt * Nov 2002: Martin Bene <martin.bene@icomedias.com>:
6370786f9SJan Engelhardt * only ignore TIME_WAIT or gone connections
7ba5dc275SJan Engelhardt * (C) CC Computer Consultants GmbH, 2007
8370786f9SJan Engelhardt *
9370786f9SJan Engelhardt * based on ...
10370786f9SJan Engelhardt *
11370786f9SJan Engelhardt * Kernel module to match connection tracking information.
12370786f9SJan Engelhardt * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
13370786f9SJan Engelhardt */
148bee4badSJan Engelhardt #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15625c5561SFlorian Westphal
1640d102cdSJeremy Sowden #include <linux/ip.h>
1740d102cdSJeremy Sowden #include <linux/ipv6.h>
18370786f9SJan Engelhardt #include <linux/module.h>
19370786f9SJan Engelhardt #include <linux/skbuff.h>
20370786f9SJan Engelhardt #include <linux/netfilter/x_tables.h>
21370786f9SJan Engelhardt #include <linux/netfilter/xt_connlimit.h>
22625c5561SFlorian Westphal
23370786f9SJan Engelhardt #include <net/netfilter/nf_conntrack.h>
24370786f9SJan Engelhardt #include <net/netfilter/nf_conntrack_core.h>
25370786f9SJan Engelhardt #include <net/netfilter/nf_conntrack_tuple.h>
265d0aa2ccSPatrick McHardy #include <net/netfilter/nf_conntrack_zones.h>
27625c5561SFlorian Westphal #include <net/netfilter/nf_conntrack_count.h>
2815cfd528SFlorian Westphal
29d3c5ee6dSJan Engelhardt static bool
connlimit_mt(const struct sk_buff * skb,struct xt_action_param * par)3062fc8051SJan Engelhardt connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
31370786f9SJan Engelhardt {
32613dbd95SPablo Neira Ayuso struct net *net = xt_net(par);
33f7108a20SJan Engelhardt const struct xt_connlimit_info *info = par->matchinfo;
34370786f9SJan Engelhardt struct nf_conntrack_tuple tuple;
35370786f9SJan Engelhardt const struct nf_conntrack_tuple *tuple_ptr = &tuple;
36308ac914SDaniel Borkmann const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
37370786f9SJan Engelhardt enum ip_conntrack_info ctinfo;
38370786f9SJan Engelhardt const struct nf_conn *ct;
397d084877SFlorian Westphal unsigned int connections;
40625c5561SFlorian Westphal u32 key[5];
41370786f9SJan Engelhardt
42370786f9SJan Engelhardt ct = nf_ct_get(skb, &ctinfo);
43e59ea3dfSFlorian Westphal if (ct != NULL) {
44ad86e1f2SJan Engelhardt tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
45e59ea3dfSFlorian Westphal zone = nf_ct_zone(ct);
46e59ea3dfSFlorian Westphal } else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
47613dbd95SPablo Neira Ayuso xt_family(par), net, &tuple)) {
48370786f9SJan Engelhardt goto hotdrop;
49e59ea3dfSFlorian Westphal }
50370786f9SJan Engelhardt
51613dbd95SPablo Neira Ayuso if (xt_family(par) == NFPROTO_IPV6) {
52370786f9SJan Engelhardt const struct ipv6hdr *iph = ipv6_hdr(skb);
53625c5561SFlorian Westphal union nf_inet_addr addr;
54b1fc1372SFlorian Westphal unsigned int i;
55b1fc1372SFlorian Westphal
56cc4fc022SJan Engelhardt memcpy(&addr.ip6, (info->flags & XT_CONNLIMIT_DADDR) ?
57cc4fc022SJan Engelhardt &iph->daddr : &iph->saddr, sizeof(addr.ip6));
58b1fc1372SFlorian Westphal
59b1fc1372SFlorian Westphal for (i = 0; i < ARRAY_SIZE(addr.ip6); ++i)
60b1fc1372SFlorian Westphal addr.ip6[i] &= info->mask.ip6[i];
61625c5561SFlorian Westphal memcpy(key, &addr, sizeof(addr.ip6));
62625c5561SFlorian Westphal key[4] = zone->id;
63370786f9SJan Engelhardt } else {
64370786f9SJan Engelhardt const struct iphdr *iph = ip_hdr(skb);
65b1fc1372SFlorian Westphal
66*168141f7SFlorian Westphal key[0] = (info->flags & XT_CONNLIMIT_DADDR) ?
67*168141f7SFlorian Westphal (__force __u32)iph->daddr : (__force __u32)iph->saddr;
68*168141f7SFlorian Westphal key[0] &= (__force __u32)info->mask.ip;
69625c5561SFlorian Westphal key[1] = zone->id;
70370786f9SJan Engelhardt }
71370786f9SJan Engelhardt
726aec2087SYi-Hung Wei connections = nf_conncount_count(net, info->data, key, tuple_ptr,
736aec2087SYi-Hung Wei zone);
747d084877SFlorian Westphal if (connections == 0)
75370786f9SJan Engelhardt /* kmalloc failed, drop it entirely */
761cc34c30SRichard Weinberger goto hotdrop;
77370786f9SJan Engelhardt
78625c5561SFlorian Westphal return (connections > info->limit) ^ !!(info->flags & XT_CONNLIMIT_INVERT);
79370786f9SJan Engelhardt
80370786f9SJan Engelhardt hotdrop:
81b4ba2611SJan Engelhardt par->hotdrop = true;
82370786f9SJan Engelhardt return false;
83370786f9SJan Engelhardt }
84370786f9SJan Engelhardt
connlimit_mt_check(const struct xt_mtchk_param * par)85b0f38452SJan Engelhardt static int connlimit_mt_check(const struct xt_mtchk_param *par)
86370786f9SJan Engelhardt {
879b4fce7aSJan Engelhardt struct xt_connlimit_info *info = par->matchinfo;
88625c5561SFlorian Westphal unsigned int keylen;
89370786f9SJan Engelhardt
90625c5561SFlorian Westphal keylen = sizeof(u32);
91625c5561SFlorian Westphal if (par->family == NFPROTO_IPV6)
92625c5561SFlorian Westphal keylen += sizeof(struct in6_addr);
93625c5561SFlorian Westphal else
94625c5561SFlorian Westphal keylen += sizeof(struct in_addr);
95370786f9SJan Engelhardt
96370786f9SJan Engelhardt /* init private data */
97625c5561SFlorian Westphal info->data = nf_conncount_init(par->net, par->family, keylen);
98370786f9SJan Engelhardt
9933b78aaaSYueHaibing return PTR_ERR_OR_ZERO(info->data);
100370786f9SJan Engelhardt }
101370786f9SJan Engelhardt
connlimit_mt_destroy(const struct xt_mtdtor_param * par)1026be3d859SJan Engelhardt static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)
103370786f9SJan Engelhardt {
1046be3d859SJan Engelhardt const struct xt_connlimit_info *info = par->matchinfo;
105370786f9SJan Engelhardt
106625c5561SFlorian Westphal nf_conncount_destroy(par->net, par->family, info->data);
107370786f9SJan Engelhardt }
108370786f9SJan Engelhardt
10968c07cb6SCong Wang static struct xt_match connlimit_mt_reg __read_mostly = {
110cc4fc022SJan Engelhardt .name = "connlimit",
111cc4fc022SJan Engelhardt .revision = 1,
112cc4fc022SJan Engelhardt .family = NFPROTO_UNSPEC,
113cc4fc022SJan Engelhardt .checkentry = connlimit_mt_check,
114cc4fc022SJan Engelhardt .match = connlimit_mt,
115cc4fc022SJan Engelhardt .matchsize = sizeof(struct xt_connlimit_info),
116ec231890SWillem de Bruijn .usersize = offsetof(struct xt_connlimit_info, data),
117cc4fc022SJan Engelhardt .destroy = connlimit_mt_destroy,
118cc4fc022SJan Engelhardt .me = THIS_MODULE,
119370786f9SJan Engelhardt };
120370786f9SJan Engelhardt
connlimit_mt_init(void)121d3c5ee6dSJan Engelhardt static int __init connlimit_mt_init(void)
122370786f9SJan Engelhardt {
123625c5561SFlorian Westphal return xt_register_match(&connlimit_mt_reg);
124370786f9SJan Engelhardt }
125370786f9SJan Engelhardt
connlimit_mt_exit(void)126d3c5ee6dSJan Engelhardt static void __exit connlimit_mt_exit(void)
127370786f9SJan Engelhardt {
12868c07cb6SCong Wang xt_unregister_match(&connlimit_mt_reg);
129370786f9SJan Engelhardt }
130370786f9SJan Engelhardt
131d3c5ee6dSJan Engelhardt module_init(connlimit_mt_init);
132d3c5ee6dSJan Engelhardt module_exit(connlimit_mt_exit);
13392f3b2b1SJan Engelhardt MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
1342ae15b64SJan Engelhardt MODULE_DESCRIPTION("Xtables: Number of connections matching");
135370786f9SJan Engelhardt MODULE_LICENSE("GPL");
136370786f9SJan Engelhardt MODULE_ALIAS("ipt_connlimit");
137370786f9SJan Engelhardt MODULE_ALIAS("ip6t_connlimit");
138