/*
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* netfilter module to limit the number of parallel tcp
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* connections per IP address.
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* (c) 2000 Gerd Knorr <kraxel@bytesex.org>
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* Nov 2002: Martin Bene <martin.bene@icomedias.com>:
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* only ignore TIME_WAIT or gone connections
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* (C) CC Computer Consultants GmbH, 2007
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*
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* based on ...
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*
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* Kernel module to match connection tracking information.
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* GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter/xt_connlimit.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_tuple.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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#include <net/netfilter/nf_conntrack_count.h>
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static bool
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connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
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{
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struct net *net = xt_net(par);
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const struct xt_connlimit_info *info = par->matchinfo;
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struct nf_conntrack_tuple tuple;
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const struct nf_conntrack_tuple *tuple_ptr = &tuple;
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const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt;
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enum ip_conntrack_info ctinfo;
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const struct nf_conn *ct;
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unsigned int connections;
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u32 key[5];
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ct = nf_ct_get(skb, &ctinfo);
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if (ct != NULL) {
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tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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zone = nf_ct_zone(ct);
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} else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
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xt_family(par), net, &tuple)) {
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goto hotdrop;
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}
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if (xt_family(par) == NFPROTO_IPV6) {
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const struct ipv6hdr *iph = ipv6_hdr(skb);
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union nf_inet_addr addr;
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unsigned int i;
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memcpy(&addr.ip6, (info->flags & XT_CONNLIMIT_DADDR) ?
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&iph->daddr : &iph->saddr, sizeof(addr.ip6));
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for (i = 0; i < ARRAY_SIZE(addr.ip6); ++i)
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addr.ip6[i] &= info->mask.ip6[i];
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memcpy(key, &addr, sizeof(addr.ip6));
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key[4] = zone->id;
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} else {
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const struct iphdr *iph = ip_hdr(skb);
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key[0] = (info->flags & XT_CONNLIMIT_DADDR) ?
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iph->daddr : iph->saddr;
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key[0] &= info->mask.ip;
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key[1] = zone->id;
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}
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connections = nf_conncount_count(net, info->data, key, tuple_ptr,
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zone);
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if (connections == 0)
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/* kmalloc failed, drop it entirely */
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goto hotdrop;
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return (connections > info->limit) ^ !!(info->flags & XT_CONNLIMIT_INVERT);
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hotdrop:
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par->hotdrop = true;
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return false;
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}
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static int connlimit_mt_check(const struct xt_mtchk_param *par)
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{
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struct xt_connlimit_info *info = par->matchinfo;
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unsigned int keylen;
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keylen = sizeof(u32);
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if (par->family == NFPROTO_IPV6)
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keylen += sizeof(struct in6_addr);
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else
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keylen += sizeof(struct in_addr);
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/* init private data */
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info->data = nf_conncount_init(par->net, par->family, keylen);
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return PTR_ERR_OR_ZERO(info->data);
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}
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static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)
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{
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const struct xt_connlimit_info *info = par->matchinfo;
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nf_conncount_destroy(par->net, par->family, info->data);
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}
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static struct xt_match connlimit_mt_reg __read_mostly = {
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.name = "connlimit",
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.revision = 1,
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.family = NFPROTO_UNSPEC,
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.checkentry = connlimit_mt_check,
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.match = connlimit_mt,
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.matchsize = sizeof(struct xt_connlimit_info),
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.usersize = offsetof(struct xt_connlimit_info, data),
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.destroy = connlimit_mt_destroy,
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.me = THIS_MODULE,
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};
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static int __init connlimit_mt_init(void)
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{
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return xt_register_match(&connlimit_mt_reg);
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}
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static void __exit connlimit_mt_exit(void)
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{
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xt_unregister_match(&connlimit_mt_reg);
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}
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module_init(connlimit_mt_init);
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module_exit(connlimit_mt_exit);
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MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
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MODULE_DESCRIPTION("Xtables: Number of connections matching");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("ipt_connlimit");
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MODULE_ALIAS("ip6t_connlimit");
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