| /* |
| * 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/in.h> |
| #include <linux/in6.h> |
| #include <linux/ip.h> |
| #include <linux/ipv6.h> |
| #include <linux/jhash.h> |
| #include <linux/list.h> |
| #include <linux/module.h> |
| #include <linux/random.h> |
| #include <linux/skbuff.h> |
| #include <linux/spinlock.h> |
| #include <linux/netfilter/nf_conntrack_tcp.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> |
| |
| /* we will save the tuples of all connections we care about */ |
| struct xt_connlimit_conn { |
| struct list_head list; |
| struct nf_conntrack_tuple tuple; |
| }; |
| |
| struct xt_connlimit_data { |
| struct list_head iphash[256]; |
| spinlock_t lock; |
| }; |
| |
| static u_int32_t connlimit_rnd __read_mostly; |
| static bool connlimit_rnd_inited __read_mostly; |
| |
| static inline unsigned int connlimit_iphash(__be32 addr) |
| { |
| return jhash_1word((__force __u32)addr, connlimit_rnd) & 0xFF; |
| } |
| |
| static inline unsigned int |
| connlimit_iphash6(const union nf_inet_addr *addr, |
| const union nf_inet_addr *mask) |
| { |
| union nf_inet_addr res; |
| unsigned int i; |
| |
| for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) |
| res.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| |
| return jhash2((u32 *)res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF; |
| } |
| |
| static inline bool already_closed(const struct nf_conn *conn) |
| { |
| if (nf_ct_protonum(conn) == IPPROTO_TCP) |
| return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT || |
| conn->proto.tcp.state == TCP_CONNTRACK_CLOSE; |
| else |
| return 0; |
| } |
| |
| static inline unsigned int |
| same_source_net(const union nf_inet_addr *addr, |
| const union nf_inet_addr *mask, |
| const union nf_inet_addr *u3, u_int8_t family) |
| { |
| if (family == NFPROTO_IPV4) { |
| return (addr->ip & mask->ip) == (u3->ip & mask->ip); |
| } else { |
| union nf_inet_addr lh, rh; |
| unsigned int i; |
| |
| for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) { |
| lh.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| rh.ip6[i] = u3->ip6[i] & mask->ip6[i]; |
| } |
| |
| return memcmp(&lh.ip6, &rh.ip6, sizeof(lh.ip6)) == 0; |
| } |
| } |
| |
| static int count_them(struct net *net, |
| struct xt_connlimit_data *data, |
| const struct nf_conntrack_tuple *tuple, |
| const union nf_inet_addr *addr, |
| const union nf_inet_addr *mask, |
| u_int8_t family) |
| { |
| const struct nf_conntrack_tuple_hash *found; |
| struct xt_connlimit_conn *conn; |
| struct xt_connlimit_conn *tmp; |
| struct nf_conn *found_ct; |
| struct list_head *hash; |
| bool addit = true; |
| int matches = 0; |
| |
| if (family == NFPROTO_IPV6) |
| hash = &data->iphash[connlimit_iphash6(addr, mask)]; |
| else |
| hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)]; |
| |
| rcu_read_lock(); |
| |
| /* check the saved connections */ |
| list_for_each_entry_safe(conn, tmp, hash, list) { |
| found = nf_conntrack_find_get(net, NF_CT_DEFAULT_ZONE, |
| &conn->tuple); |
| found_ct = NULL; |
| |
| if (found != NULL) |
| found_ct = nf_ct_tuplehash_to_ctrack(found); |
| |
| if (found_ct != NULL && |
| nf_ct_tuple_equal(&conn->tuple, tuple) && |
| !already_closed(found_ct)) |
| /* |
| * Just to be sure we have it only once in the list. |
| * We should not see tuples twice unless someone hooks |
| * this into a table without "-p tcp --syn". |
| */ |
| addit = false; |
| |
| if (found == NULL) { |
| /* this one is gone */ |
| list_del(&conn->list); |
| kfree(conn); |
| continue; |
| } |
| |
| if (already_closed(found_ct)) { |
| /* |
| * we do not care about connections which are |
| * closed already -> ditch it |
| */ |
| nf_ct_put(found_ct); |
| list_del(&conn->list); |
| kfree(conn); |
| continue; |
| } |
| |
| if (same_source_net(addr, mask, &conn->tuple.src.u3, family)) |
| /* same source network -> be counted! */ |
| ++matches; |
| nf_ct_put(found_ct); |
| } |
| |
| rcu_read_unlock(); |
| |
| if (addit) { |
| /* save the new connection in our list */ |
| conn = kzalloc(sizeof(*conn), GFP_ATOMIC); |
| if (conn == NULL) |
| return -ENOMEM; |
| conn->tuple = *tuple; |
| list_add(&conn->list, hash); |
| ++matches; |
| } |
| |
| return matches; |
| } |
| |
| static bool |
| connlimit_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
| { |
| struct net *net = dev_net(par->in ? par->in : par->out); |
| const struct xt_connlimit_info *info = par->matchinfo; |
| union nf_inet_addr addr; |
| struct nf_conntrack_tuple tuple; |
| const struct nf_conntrack_tuple *tuple_ptr = &tuple; |
| enum ip_conntrack_info ctinfo; |
| const struct nf_conn *ct; |
| int connections; |
| |
| ct = nf_ct_get(skb, &ctinfo); |
| if (ct != NULL) |
| tuple_ptr = &ct->tuplehash[0].tuple; |
| else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), |
| par->family, &tuple)) |
| goto hotdrop; |
| |
| if (par->family == NFPROTO_IPV6) { |
| const struct ipv6hdr *iph = ipv6_hdr(skb); |
| memcpy(&addr.ip6, &iph->saddr, sizeof(iph->saddr)); |
| } else { |
| const struct iphdr *iph = ip_hdr(skb); |
| addr.ip = iph->saddr; |
| } |
| |
| spin_lock_bh(&info->data->lock); |
| connections = count_them(net, info->data, tuple_ptr, &addr, |
| &info->mask, par->family); |
| spin_unlock_bh(&info->data->lock); |
| |
| if (connections < 0) { |
| /* kmalloc failed, drop it entirely */ |
| *par->hotdrop = true; |
| return false; |
| } |
| |
| return (connections > info->limit) ^ info->inverse; |
| |
| 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 i; |
| |
| if (unlikely(!connlimit_rnd_inited)) { |
| get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd)); |
| connlimit_rnd_inited = true; |
| } |
| if (nf_ct_l3proto_try_module_get(par->family) < 0) { |
| pr_info("cannot load conntrack support for " |
| "address family %u\n", par->family); |
| return -EINVAL; |
| } |
| |
| /* init private data */ |
| info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL); |
| if (info->data == NULL) { |
| nf_ct_l3proto_module_put(par->family); |
| return -EINVAL; |
| } |
| |
| spin_lock_init(&info->data->lock); |
| for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) |
| INIT_LIST_HEAD(&info->data->iphash[i]); |
| |
| return 0; |
| } |
| |
| static void connlimit_mt_destroy(const struct xt_mtdtor_param *par) |
| { |
| const struct xt_connlimit_info *info = par->matchinfo; |
| struct xt_connlimit_conn *conn; |
| struct xt_connlimit_conn *tmp; |
| struct list_head *hash = info->data->iphash; |
| unsigned int i; |
| |
| nf_ct_l3proto_module_put(par->family); |
| |
| for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) { |
| list_for_each_entry_safe(conn, tmp, &hash[i], list) { |
| list_del(&conn->list); |
| kfree(conn); |
| } |
| } |
| |
| kfree(info->data); |
| } |
| |
| static struct xt_match connlimit_mt_reg __read_mostly = { |
| .name = "connlimit", |
| .revision = 0, |
| .family = NFPROTO_UNSPEC, |
| .checkentry = connlimit_mt_check, |
| .match = connlimit_mt, |
| .matchsize = sizeof(struct xt_connlimit_info), |
| .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"); |