Staging: hv: remove OnChildDeviceRemove vmbus_driver callback
[zen-stable.git] / net / netfilter / xt_connlimit.c
blob5c5b6b921b845b2fe1ba438ef9c13a2161e5b0ea
1 /*
2 * netfilter module to limit the number of parallel tcp
3 * connections per IP address.
4 * (c) 2000 Gerd Knorr <kraxel@bytesex.org>
5 * Nov 2002: Martin Bene <martin.bene@icomedias.com>:
6 * only ignore TIME_WAIT or gone connections
7 * (C) CC Computer Consultants GmbH, 2007
9 * based on ...
11 * Kernel module to match connection tracking information.
12 * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/in.h>
16 #include <linux/in6.h>
17 #include <linux/ip.h>
18 #include <linux/ipv6.h>
19 #include <linux/jhash.h>
20 #include <linux/slab.h>
21 #include <linux/list.h>
22 #include <linux/module.h>
23 #include <linux/random.h>
24 #include <linux/skbuff.h>
25 #include <linux/spinlock.h>
26 #include <linux/netfilter/nf_conntrack_tcp.h>
27 #include <linux/netfilter/x_tables.h>
28 #include <linux/netfilter/xt_connlimit.h>
29 #include <net/netfilter/nf_conntrack.h>
30 #include <net/netfilter/nf_conntrack_core.h>
31 #include <net/netfilter/nf_conntrack_tuple.h>
32 #include <net/netfilter/nf_conntrack_zones.h>
34 /* we will save the tuples of all connections we care about */
35 struct xt_connlimit_conn {
36 struct list_head list;
37 struct nf_conntrack_tuple tuple;
40 struct xt_connlimit_data {
41 struct list_head iphash[256];
42 spinlock_t lock;
45 static u_int32_t connlimit_rnd __read_mostly;
46 static bool connlimit_rnd_inited __read_mostly;
48 static inline unsigned int connlimit_iphash(__be32 addr)
50 return jhash_1word((__force __u32)addr, connlimit_rnd) & 0xFF;
53 static inline unsigned int
54 connlimit_iphash6(const union nf_inet_addr *addr,
55 const union nf_inet_addr *mask)
57 union nf_inet_addr res;
58 unsigned int i;
60 for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i)
61 res.ip6[i] = addr->ip6[i] & mask->ip6[i];
63 return jhash2((u32 *)res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF;
66 static inline bool already_closed(const struct nf_conn *conn)
68 if (nf_ct_protonum(conn) == IPPROTO_TCP)
69 return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT ||
70 conn->proto.tcp.state == TCP_CONNTRACK_CLOSE;
71 else
72 return 0;
75 static inline unsigned int
76 same_source_net(const union nf_inet_addr *addr,
77 const union nf_inet_addr *mask,
78 const union nf_inet_addr *u3, u_int8_t family)
80 if (family == NFPROTO_IPV4) {
81 return (addr->ip & mask->ip) == (u3->ip & mask->ip);
82 } else {
83 union nf_inet_addr lh, rh;
84 unsigned int i;
86 for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) {
87 lh.ip6[i] = addr->ip6[i] & mask->ip6[i];
88 rh.ip6[i] = u3->ip6[i] & mask->ip6[i];
91 return memcmp(&lh.ip6, &rh.ip6, sizeof(lh.ip6)) == 0;
95 static int count_them(struct net *net,
96 struct xt_connlimit_data *data,
97 const struct nf_conntrack_tuple *tuple,
98 const union nf_inet_addr *addr,
99 const union nf_inet_addr *mask,
100 u_int8_t family)
102 const struct nf_conntrack_tuple_hash *found;
103 struct xt_connlimit_conn *conn;
104 struct xt_connlimit_conn *tmp;
105 struct nf_conn *found_ct;
106 struct list_head *hash;
107 bool addit = true;
108 int matches = 0;
110 if (family == NFPROTO_IPV6)
111 hash = &data->iphash[connlimit_iphash6(addr, mask)];
112 else
113 hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)];
115 rcu_read_lock();
117 /* check the saved connections */
118 list_for_each_entry_safe(conn, tmp, hash, list) {
119 found = nf_conntrack_find_get(net, NF_CT_DEFAULT_ZONE,
120 &conn->tuple);
121 found_ct = NULL;
123 if (found != NULL)
124 found_ct = nf_ct_tuplehash_to_ctrack(found);
126 if (found_ct != NULL &&
127 nf_ct_tuple_equal(&conn->tuple, tuple) &&
128 !already_closed(found_ct))
130 * Just to be sure we have it only once in the list.
131 * We should not see tuples twice unless someone hooks
132 * this into a table without "-p tcp --syn".
134 addit = false;
136 if (found == NULL) {
137 /* this one is gone */
138 list_del(&conn->list);
139 kfree(conn);
140 continue;
143 if (already_closed(found_ct)) {
145 * we do not care about connections which are
146 * closed already -> ditch it
148 nf_ct_put(found_ct);
149 list_del(&conn->list);
150 kfree(conn);
151 continue;
154 if (same_source_net(addr, mask, &conn->tuple.src.u3, family))
155 /* same source network -> be counted! */
156 ++matches;
157 nf_ct_put(found_ct);
160 rcu_read_unlock();
162 if (addit) {
163 /* save the new connection in our list */
164 conn = kzalloc(sizeof(*conn), GFP_ATOMIC);
165 if (conn == NULL)
166 return -ENOMEM;
167 conn->tuple = *tuple;
168 list_add(&conn->list, hash);
169 ++matches;
172 return matches;
175 static bool
176 connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par)
178 struct net *net = dev_net(par->in ? par->in : par->out);
179 const struct xt_connlimit_info *info = par->matchinfo;
180 union nf_inet_addr addr;
181 struct nf_conntrack_tuple tuple;
182 const struct nf_conntrack_tuple *tuple_ptr = &tuple;
183 enum ip_conntrack_info ctinfo;
184 const struct nf_conn *ct;
185 int connections;
187 ct = nf_ct_get(skb, &ctinfo);
188 if (ct != NULL)
189 tuple_ptr = &ct->tuplehash[0].tuple;
190 else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
191 par->family, &tuple))
192 goto hotdrop;
194 if (par->family == NFPROTO_IPV6) {
195 const struct ipv6hdr *iph = ipv6_hdr(skb);
196 memcpy(&addr.ip6, &iph->saddr, sizeof(iph->saddr));
197 } else {
198 const struct iphdr *iph = ip_hdr(skb);
199 addr.ip = iph->saddr;
202 spin_lock_bh(&info->data->lock);
203 connections = count_them(net, info->data, tuple_ptr, &addr,
204 &info->mask, par->family);
205 spin_unlock_bh(&info->data->lock);
207 if (connections < 0) {
208 /* kmalloc failed, drop it entirely */
209 par->hotdrop = true;
210 return false;
213 return (connections > info->limit) ^ info->inverse;
215 hotdrop:
216 par->hotdrop = true;
217 return false;
220 static int connlimit_mt_check(const struct xt_mtchk_param *par)
222 struct xt_connlimit_info *info = par->matchinfo;
223 unsigned int i;
224 int ret;
226 if (unlikely(!connlimit_rnd_inited)) {
227 get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd));
228 connlimit_rnd_inited = true;
230 ret = nf_ct_l3proto_try_module_get(par->family);
231 if (ret < 0) {
232 pr_info("cannot load conntrack support for "
233 "address family %u\n", par->family);
234 return ret;
237 /* init private data */
238 info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL);
239 if (info->data == NULL) {
240 nf_ct_l3proto_module_put(par->family);
241 return -ENOMEM;
244 spin_lock_init(&info->data->lock);
245 for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i)
246 INIT_LIST_HEAD(&info->data->iphash[i]);
248 return 0;
251 static void connlimit_mt_destroy(const struct xt_mtdtor_param *par)
253 const struct xt_connlimit_info *info = par->matchinfo;
254 struct xt_connlimit_conn *conn;
255 struct xt_connlimit_conn *tmp;
256 struct list_head *hash = info->data->iphash;
257 unsigned int i;
259 nf_ct_l3proto_module_put(par->family);
261 for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) {
262 list_for_each_entry_safe(conn, tmp, &hash[i], list) {
263 list_del(&conn->list);
264 kfree(conn);
268 kfree(info->data);
271 static struct xt_match connlimit_mt_reg __read_mostly = {
272 .name = "connlimit",
273 .revision = 0,
274 .family = NFPROTO_UNSPEC,
275 .checkentry = connlimit_mt_check,
276 .match = connlimit_mt,
277 .matchsize = sizeof(struct xt_connlimit_info),
278 .destroy = connlimit_mt_destroy,
279 .me = THIS_MODULE,
282 static int __init connlimit_mt_init(void)
284 return xt_register_match(&connlimit_mt_reg);
287 static void __exit connlimit_mt_exit(void)
289 xt_unregister_match(&connlimit_mt_reg);
292 module_init(connlimit_mt_init);
293 module_exit(connlimit_mt_exit);
294 MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
295 MODULE_DESCRIPTION("Xtables: Number of connections matching");
296 MODULE_LICENSE("GPL");
297 MODULE_ALIAS("ipt_connlimit");
298 MODULE_ALIAS("ip6t_connlimit");