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