Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 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 |
Jan Engelhardt | ba5dc27 | 2007-11-05 20:35:56 -0800 | [diff] [blame] | 7 | * (C) CC Computer Consultants GmbH, 2007 |
| 8 | * Contact: <jengelh@computergmbh.de> |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 9 | * |
| 10 | * based on ... |
| 11 | * |
| 12 | * Kernel module to match connection tracking information. |
| 13 | * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au). |
| 14 | */ |
| 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/list.h> |
| 21 | #include <linux/module.h> |
| 22 | #include <linux/random.h> |
| 23 | #include <linux/skbuff.h> |
| 24 | #include <linux/spinlock.h> |
| 25 | #include <linux/netfilter/nf_conntrack_tcp.h> |
| 26 | #include <linux/netfilter/x_tables.h> |
| 27 | #include <linux/netfilter/xt_connlimit.h> |
| 28 | #include <net/netfilter/nf_conntrack.h> |
| 29 | #include <net/netfilter/nf_conntrack_core.h> |
| 30 | #include <net/netfilter/nf_conntrack_tuple.h> |
| 31 | |
| 32 | /* we will save the tuples of all connections we care about */ |
| 33 | struct xt_connlimit_conn { |
| 34 | struct list_head list; |
| 35 | struct nf_conntrack_tuple tuple; |
| 36 | }; |
| 37 | |
| 38 | struct xt_connlimit_data { |
| 39 | struct list_head iphash[256]; |
| 40 | spinlock_t lock; |
| 41 | }; |
| 42 | |
| 43 | static u_int32_t connlimit_rnd; |
| 44 | static bool connlimit_rnd_inited; |
| 45 | |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 46 | static inline unsigned int connlimit_iphash(__be32 addr) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 47 | { |
| 48 | if (unlikely(!connlimit_rnd_inited)) { |
| 49 | get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd)); |
| 50 | connlimit_rnd_inited = true; |
| 51 | } |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 52 | return jhash_1word((__force __u32)addr, connlimit_rnd) & 0xFF; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 53 | } |
| 54 | |
| 55 | static inline unsigned int |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 56 | connlimit_iphash6(const union nf_inet_addr *addr, |
| 57 | const union nf_inet_addr *mask) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 58 | { |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 59 | union nf_inet_addr res; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 60 | unsigned int i; |
| 61 | |
| 62 | if (unlikely(!connlimit_rnd_inited)) { |
| 63 | get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd)); |
| 64 | connlimit_rnd_inited = true; |
| 65 | } |
| 66 | |
| 67 | for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) |
| 68 | res.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| 69 | |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 70 | return jhash2((u32 *)res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 71 | } |
| 72 | |
| 73 | static inline bool already_closed(const struct nf_conn *conn) |
| 74 | { |
Patrick McHardy | 5e8fbe2 | 2008-04-14 11:15:52 +0200 | [diff] [blame] | 75 | if (nf_ct_protonum(conn) == IPPROTO_TCP) |
Dong Wei | d2ee3f2 | 2008-06-04 09:57:51 -0700 | [diff] [blame] | 76 | return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT || |
| 77 | conn->proto.tcp.state == TCP_CONNTRACK_CLOSE; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 78 | else |
| 79 | return 0; |
| 80 | } |
| 81 | |
| 82 | static inline unsigned int |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 83 | same_source_net(const union nf_inet_addr *addr, |
| 84 | const union nf_inet_addr *mask, |
Jan Engelhardt | 76108ce | 2008-10-08 11:35:00 +0200 | [diff] [blame] | 85 | const union nf_inet_addr *u3, u_int8_t family) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 86 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 87 | if (family == NFPROTO_IPV4) { |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 88 | return (addr->ip & mask->ip) == (u3->ip & mask->ip); |
| 89 | } else { |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 90 | union nf_inet_addr lh, rh; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 91 | unsigned int i; |
| 92 | |
| 93 | for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) { |
| 94 | lh.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| 95 | rh.ip6[i] = u3->ip6[i] & mask->ip6[i]; |
| 96 | } |
| 97 | |
| 98 | return memcmp(&lh.ip6, &rh.ip6, sizeof(lh.ip6)) == 0; |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | static int count_them(struct xt_connlimit_data *data, |
| 103 | const struct nf_conntrack_tuple *tuple, |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 104 | const union nf_inet_addr *addr, |
| 105 | const union nf_inet_addr *mask, |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 106 | const struct xt_match *match) |
| 107 | { |
Jan Engelhardt | 3cf93c9 | 2008-04-14 09:56:05 +0200 | [diff] [blame] | 108 | const struct nf_conntrack_tuple_hash *found; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 109 | struct xt_connlimit_conn *conn; |
| 110 | struct xt_connlimit_conn *tmp; |
Jan Engelhardt | 3cf93c9 | 2008-04-14 09:56:05 +0200 | [diff] [blame] | 111 | const struct nf_conn *found_ct; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 112 | struct list_head *hash; |
| 113 | bool addit = true; |
| 114 | int matches = 0; |
| 115 | |
| 116 | |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 117 | if (match->family == NFPROTO_IPV6) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 118 | hash = &data->iphash[connlimit_iphash6(addr, mask)]; |
| 119 | else |
| 120 | hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)]; |
| 121 | |
Patrick McHardy | 76507f6 | 2008-01-31 04:38:38 -0800 | [diff] [blame] | 122 | rcu_read_lock(); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 123 | |
| 124 | /* check the saved connections */ |
| 125 | list_for_each_entry_safe(conn, tmp, hash, list) { |
Alexey Dobriyan | 400dad3 | 2008-10-08 11:35:03 +0200 | [diff] [blame] | 126 | found = __nf_conntrack_find(&init_net, &conn->tuple); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 127 | found_ct = NULL; |
| 128 | |
| 129 | if (found != NULL) |
| 130 | found_ct = nf_ct_tuplehash_to_ctrack(found); |
| 131 | |
| 132 | if (found_ct != NULL && |
| 133 | nf_ct_tuple_equal(&conn->tuple, tuple) && |
| 134 | !already_closed(found_ct)) |
| 135 | /* |
| 136 | * Just to be sure we have it only once in the list. |
| 137 | * We should not see tuples twice unless someone hooks |
| 138 | * this into a table without "-p tcp --syn". |
| 139 | */ |
| 140 | addit = false; |
| 141 | |
| 142 | if (found == NULL) { |
| 143 | /* this one is gone */ |
| 144 | list_del(&conn->list); |
| 145 | kfree(conn); |
| 146 | continue; |
| 147 | } |
| 148 | |
| 149 | if (already_closed(found_ct)) { |
| 150 | /* |
| 151 | * we do not care about connections which are |
| 152 | * closed already -> ditch it |
| 153 | */ |
| 154 | list_del(&conn->list); |
| 155 | kfree(conn); |
| 156 | continue; |
| 157 | } |
| 158 | |
| 159 | if (same_source_net(addr, mask, &conn->tuple.src.u3, |
| 160 | match->family)) |
| 161 | /* same source network -> be counted! */ |
| 162 | ++matches; |
| 163 | } |
| 164 | |
Patrick McHardy | 76507f6 | 2008-01-31 04:38:38 -0800 | [diff] [blame] | 165 | rcu_read_unlock(); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 166 | |
| 167 | if (addit) { |
| 168 | /* save the new connection in our list */ |
| 169 | conn = kzalloc(sizeof(*conn), GFP_ATOMIC); |
| 170 | if (conn == NULL) |
| 171 | return -ENOMEM; |
| 172 | conn->tuple = *tuple; |
| 173 | list_add(&conn->list, hash); |
| 174 | ++matches; |
| 175 | } |
| 176 | |
| 177 | return matches; |
| 178 | } |
| 179 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 180 | static bool |
Jan Engelhardt | f7108a2 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 181 | connlimit_mt(const struct sk_buff *skb, const struct xt_match_param *par) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 182 | { |
Jan Engelhardt | f7108a2 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 183 | const struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 22c2d8b | 2007-12-17 22:44:47 -0800 | [diff] [blame] | 184 | union nf_inet_addr addr; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 185 | struct nf_conntrack_tuple tuple; |
| 186 | const struct nf_conntrack_tuple *tuple_ptr = &tuple; |
| 187 | enum ip_conntrack_info ctinfo; |
| 188 | const struct nf_conn *ct; |
| 189 | int connections; |
| 190 | |
| 191 | ct = nf_ct_get(skb, &ctinfo); |
| 192 | if (ct != NULL) |
| 193 | tuple_ptr = &ct->tuplehash[0].tuple; |
| 194 | else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 195 | par->family, &tuple)) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 196 | goto hotdrop; |
| 197 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 198 | if (par->family == NFPROTO_IPV6) { |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 199 | const struct ipv6hdr *iph = ipv6_hdr(skb); |
| 200 | memcpy(&addr.ip6, &iph->saddr, sizeof(iph->saddr)); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 201 | } else { |
| 202 | const struct iphdr *iph = ip_hdr(skb); |
| 203 | addr.ip = iph->saddr; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 204 | } |
| 205 | |
| 206 | spin_lock_bh(&info->data->lock); |
Jan Engelhardt | 22c2d8b | 2007-12-17 22:44:47 -0800 | [diff] [blame] | 207 | connections = count_them(info->data, tuple_ptr, &addr, |
Jan Engelhardt | f7108a2 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 208 | &info->mask, par->match); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 209 | spin_unlock_bh(&info->data->lock); |
| 210 | |
| 211 | if (connections < 0) { |
| 212 | /* kmalloc failed, drop it entirely */ |
Jan Engelhardt | f7108a2 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 213 | *par->hotdrop = true; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 214 | return false; |
| 215 | } |
| 216 | |
| 217 | return (connections > info->limit) ^ info->inverse; |
| 218 | |
| 219 | hotdrop: |
Jan Engelhardt | f7108a2 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 220 | *par->hotdrop = true; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 221 | return false; |
| 222 | } |
| 223 | |
Jan Engelhardt | 9b4fce7 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 224 | static bool connlimit_mt_check(const struct xt_mtchk_param *par) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 225 | { |
Jan Engelhardt | 9b4fce7 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 226 | struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 227 | unsigned int i; |
| 228 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 229 | if (nf_ct_l3proto_try_module_get(par->family) < 0) { |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 230 | printk(KERN_WARNING "cannot load conntrack support for " |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 231 | "address family %u\n", par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 232 | return false; |
| 233 | } |
| 234 | |
| 235 | /* init private data */ |
| 236 | info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL); |
| 237 | if (info->data == NULL) { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 238 | nf_ct_l3proto_module_put(par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 239 | return false; |
| 240 | } |
| 241 | |
| 242 | spin_lock_init(&info->data->lock); |
| 243 | for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) |
| 244 | INIT_LIST_HEAD(&info->data->iphash[i]); |
| 245 | |
| 246 | return true; |
| 247 | } |
| 248 | |
Jan Engelhardt | 6be3d85 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 249 | static void connlimit_mt_destroy(const struct xt_mtdtor_param *par) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 250 | { |
Jan Engelhardt | 6be3d85 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 251 | const struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 252 | struct xt_connlimit_conn *conn; |
| 253 | struct xt_connlimit_conn *tmp; |
| 254 | struct list_head *hash = info->data->iphash; |
| 255 | unsigned int i; |
| 256 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 257 | nf_ct_l3proto_module_put(par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 258 | |
| 259 | for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) { |
| 260 | list_for_each_entry_safe(conn, tmp, &hash[i], list) { |
| 261 | list_del(&conn->list); |
| 262 | kfree(conn); |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | kfree(info->data); |
| 267 | } |
| 268 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 269 | static struct xt_match connlimit_mt_reg __read_mostly = { |
| 270 | .name = "connlimit", |
| 271 | .revision = 0, |
| 272 | .family = NFPROTO_UNSPEC, |
| 273 | .checkentry = connlimit_mt_check, |
| 274 | .match = connlimit_mt, |
| 275 | .matchsize = sizeof(struct xt_connlimit_info), |
| 276 | .destroy = connlimit_mt_destroy, |
| 277 | .me = THIS_MODULE, |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 278 | }; |
| 279 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 280 | static int __init connlimit_mt_init(void) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 281 | { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 282 | return xt_register_match(&connlimit_mt_reg); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 283 | } |
| 284 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 285 | static void __exit connlimit_mt_exit(void) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 286 | { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 287 | xt_unregister_match(&connlimit_mt_reg); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 288 | } |
| 289 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 290 | module_init(connlimit_mt_init); |
| 291 | module_exit(connlimit_mt_exit); |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 292 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); |
Jan Engelhardt | 2ae15b6 | 2008-01-14 23:42:28 -0800 | [diff] [blame] | 293 | MODULE_DESCRIPTION("Xtables: Number of connections matching"); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 294 | MODULE_LICENSE("GPL"); |
| 295 | MODULE_ALIAS("ipt_connlimit"); |
| 296 | MODULE_ALIAS("ip6t_connlimit"); |