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 |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 8 | * |
| 9 | * based on ... |
| 10 | * |
| 11 | * Kernel module to match connection tracking information. |
| 12 | * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au). |
| 13 | */ |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame^] | 14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 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> |
Patrick McHardy | 5d0aa2c | 2010-02-15 18:13:33 +0100 | [diff] [blame] | 31 | #include <net/netfilter/nf_conntrack_zones.h> |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 32 | |
| 33 | /* we will save the tuples of all connections we care about */ |
| 34 | struct xt_connlimit_conn { |
| 35 | struct list_head list; |
| 36 | struct nf_conntrack_tuple tuple; |
| 37 | }; |
| 38 | |
| 39 | struct xt_connlimit_data { |
| 40 | struct list_head iphash[256]; |
| 41 | spinlock_t lock; |
| 42 | }; |
| 43 | |
Jan Engelhardt | 294188a | 2010-01-04 16:28:38 +0100 | [diff] [blame] | 44 | static u_int32_t connlimit_rnd __read_mostly; |
| 45 | static bool connlimit_rnd_inited __read_mostly; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 46 | |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 47 | static inline unsigned int connlimit_iphash(__be32 addr) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 48 | { |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 49 | return jhash_1word((__force __u32)addr, connlimit_rnd) & 0xFF; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 50 | } |
| 51 | |
| 52 | static inline unsigned int |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 53 | connlimit_iphash6(const union nf_inet_addr *addr, |
| 54 | const union nf_inet_addr *mask) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 55 | { |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 56 | union nf_inet_addr res; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 57 | unsigned int i; |
| 58 | |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 59 | for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) |
| 60 | res.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| 61 | |
Al Viro | a34c458 | 2007-07-26 17:33:19 +0100 | [diff] [blame] | 62 | return jhash2((u32 *)res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 63 | } |
| 64 | |
| 65 | static inline bool already_closed(const struct nf_conn *conn) |
| 66 | { |
Patrick McHardy | 5e8fbe2 | 2008-04-14 11:15:52 +0200 | [diff] [blame] | 67 | if (nf_ct_protonum(conn) == IPPROTO_TCP) |
Dong Wei | d2ee3f2 | 2008-06-04 09:57:51 -0700 | [diff] [blame] | 68 | return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT || |
| 69 | conn->proto.tcp.state == TCP_CONNTRACK_CLOSE; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 70 | else |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | static inline unsigned int |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 75 | same_source_net(const union nf_inet_addr *addr, |
| 76 | const union nf_inet_addr *mask, |
Jan Engelhardt | 76108ce | 2008-10-08 11:35:00 +0200 | [diff] [blame] | 77 | const union nf_inet_addr *u3, u_int8_t family) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 78 | { |
Jan Engelhardt | ee999d8 | 2008-10-08 11:35:01 +0200 | [diff] [blame] | 79 | if (family == NFPROTO_IPV4) { |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 80 | return (addr->ip & mask->ip) == (u3->ip & mask->ip); |
| 81 | } else { |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 82 | union nf_inet_addr lh, rh; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 83 | unsigned int i; |
| 84 | |
| 85 | for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i) { |
| 86 | lh.ip6[i] = addr->ip6[i] & mask->ip6[i]; |
| 87 | rh.ip6[i] = u3->ip6[i] & mask->ip6[i]; |
| 88 | } |
| 89 | |
| 90 | return memcmp(&lh.ip6, &rh.ip6, sizeof(lh.ip6)) == 0; |
| 91 | } |
| 92 | } |
| 93 | |
Alexey Dobriyan | 83fc810 | 2010-01-18 08:07:50 +0100 | [diff] [blame] | 94 | static int count_them(struct net *net, |
| 95 | struct xt_connlimit_data *data, |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 96 | const struct nf_conntrack_tuple *tuple, |
Jan Engelhardt | 643a2c1 | 2007-12-17 22:43:50 -0800 | [diff] [blame] | 97 | const union nf_inet_addr *addr, |
| 98 | const union nf_inet_addr *mask, |
Jan Engelhardt | 539054a | 2009-11-06 18:08:32 -0800 | [diff] [blame] | 99 | u_int8_t family) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 100 | { |
Jan Engelhardt | 3cf93c9 | 2008-04-14 09:56:05 +0200 | [diff] [blame] | 101 | const struct nf_conntrack_tuple_hash *found; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 102 | struct xt_connlimit_conn *conn; |
| 103 | struct xt_connlimit_conn *tmp; |
Eric Dumazet | ea781f1 | 2009-03-25 21:05:46 +0100 | [diff] [blame] | 104 | struct nf_conn *found_ct; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 105 | struct list_head *hash; |
| 106 | bool addit = true; |
| 107 | int matches = 0; |
| 108 | |
Jan Engelhardt | 539054a | 2009-11-06 18:08:32 -0800 | [diff] [blame] | 109 | if (family == NFPROTO_IPV6) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 110 | hash = &data->iphash[connlimit_iphash6(addr, mask)]; |
| 111 | else |
| 112 | hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)]; |
| 113 | |
Patrick McHardy | 76507f6 | 2008-01-31 04:38:38 -0800 | [diff] [blame] | 114 | rcu_read_lock(); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 115 | |
| 116 | /* check the saved connections */ |
| 117 | list_for_each_entry_safe(conn, tmp, hash, list) { |
Patrick McHardy | 5d0aa2c | 2010-02-15 18:13:33 +0100 | [diff] [blame] | 118 | found = nf_conntrack_find_get(net, NF_CT_DEFAULT_ZONE, |
| 119 | &conn->tuple); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 120 | found_ct = NULL; |
| 121 | |
| 122 | if (found != NULL) |
| 123 | found_ct = nf_ct_tuplehash_to_ctrack(found); |
| 124 | |
| 125 | if (found_ct != NULL && |
| 126 | nf_ct_tuple_equal(&conn->tuple, tuple) && |
| 127 | !already_closed(found_ct)) |
| 128 | /* |
| 129 | * Just to be sure we have it only once in the list. |
| 130 | * We should not see tuples twice unless someone hooks |
| 131 | * this into a table without "-p tcp --syn". |
| 132 | */ |
| 133 | addit = false; |
| 134 | |
| 135 | if (found == NULL) { |
| 136 | /* this one is gone */ |
| 137 | list_del(&conn->list); |
| 138 | kfree(conn); |
| 139 | continue; |
| 140 | } |
| 141 | |
| 142 | if (already_closed(found_ct)) { |
| 143 | /* |
| 144 | * we do not care about connections which are |
| 145 | * closed already -> ditch it |
| 146 | */ |
Eric Dumazet | ea781f1 | 2009-03-25 21:05:46 +0100 | [diff] [blame] | 147 | nf_ct_put(found_ct); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 148 | list_del(&conn->list); |
| 149 | kfree(conn); |
| 150 | continue; |
| 151 | } |
| 152 | |
Jan Engelhardt | 539054a | 2009-11-06 18:08:32 -0800 | [diff] [blame] | 153 | if (same_source_net(addr, mask, &conn->tuple.src.u3, family)) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 154 | /* same source network -> be counted! */ |
| 155 | ++matches; |
Eric Dumazet | ea781f1 | 2009-03-25 21:05:46 +0100 | [diff] [blame] | 156 | nf_ct_put(found_ct); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 157 | } |
| 158 | |
Patrick McHardy | 76507f6 | 2008-01-31 04:38:38 -0800 | [diff] [blame] | 159 | rcu_read_unlock(); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 160 | |
| 161 | if (addit) { |
| 162 | /* save the new connection in our list */ |
| 163 | conn = kzalloc(sizeof(*conn), GFP_ATOMIC); |
| 164 | if (conn == NULL) |
| 165 | return -ENOMEM; |
| 166 | conn->tuple = *tuple; |
| 167 | list_add(&conn->list, hash); |
| 168 | ++matches; |
| 169 | } |
| 170 | |
| 171 | return matches; |
| 172 | } |
| 173 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 174 | static bool |
Jan Engelhardt | f7108a20 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 175 | 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] | 176 | { |
Alexey Dobriyan | 83fc810 | 2010-01-18 08:07:50 +0100 | [diff] [blame] | 177 | struct net *net = dev_net(par->in ? par->in : par->out); |
Jan Engelhardt | f7108a20 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 178 | const struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 22c2d8b | 2007-12-17 22:44:47 -0800 | [diff] [blame] | 179 | union nf_inet_addr addr; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 180 | struct nf_conntrack_tuple tuple; |
| 181 | const struct nf_conntrack_tuple *tuple_ptr = &tuple; |
| 182 | enum ip_conntrack_info ctinfo; |
| 183 | const struct nf_conn *ct; |
| 184 | int connections; |
| 185 | |
| 186 | ct = nf_ct_get(skb, &ctinfo); |
| 187 | if (ct != NULL) |
| 188 | tuple_ptr = &ct->tuplehash[0].tuple; |
| 189 | else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 190 | par->family, &tuple)) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 191 | goto hotdrop; |
| 192 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 193 | if (par->family == NFPROTO_IPV6) { |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 194 | const struct ipv6hdr *iph = ipv6_hdr(skb); |
| 195 | memcpy(&addr.ip6, &iph->saddr, sizeof(iph->saddr)); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 196 | } else { |
| 197 | const struct iphdr *iph = ip_hdr(skb); |
| 198 | addr.ip = iph->saddr; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 199 | } |
| 200 | |
| 201 | spin_lock_bh(&info->data->lock); |
Alexey Dobriyan | 83fc810 | 2010-01-18 08:07:50 +0100 | [diff] [blame] | 202 | connections = count_them(net, info->data, tuple_ptr, &addr, |
Jan Engelhardt | 539054a | 2009-11-06 18:08:32 -0800 | [diff] [blame] | 203 | &info->mask, par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 204 | spin_unlock_bh(&info->data->lock); |
| 205 | |
| 206 | if (connections < 0) { |
| 207 | /* kmalloc failed, drop it entirely */ |
Jan Engelhardt | f7108a20 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 208 | *par->hotdrop = true; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 209 | return false; |
| 210 | } |
| 211 | |
| 212 | return (connections > info->limit) ^ info->inverse; |
| 213 | |
| 214 | hotdrop: |
Jan Engelhardt | f7108a20 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 215 | *par->hotdrop = true; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 216 | return false; |
| 217 | } |
| 218 | |
Jan Engelhardt | 9b4fce7 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 219 | static bool connlimit_mt_check(const struct xt_mtchk_param *par) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 220 | { |
Jan Engelhardt | 9b4fce7 | 2008-10-08 11:35:18 +0200 | [diff] [blame] | 221 | struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 222 | unsigned int i; |
| 223 | |
Jan Engelhardt | 294188a | 2010-01-04 16:28:38 +0100 | [diff] [blame] | 224 | if (unlikely(!connlimit_rnd_inited)) { |
| 225 | get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd)); |
| 226 | connlimit_rnd_inited = true; |
| 227 | } |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 228 | if (nf_ct_l3proto_try_module_get(par->family) < 0) { |
Jan Engelhardt | 8bee4ba | 2010-03-17 16:04:40 +0100 | [diff] [blame^] | 229 | pr_info("cannot load conntrack support for " |
| 230 | "address family %u\n", par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 231 | return false; |
| 232 | } |
| 233 | |
| 234 | /* init private data */ |
| 235 | info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL); |
| 236 | if (info->data == NULL) { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 237 | nf_ct_l3proto_module_put(par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 238 | return false; |
| 239 | } |
| 240 | |
| 241 | spin_lock_init(&info->data->lock); |
| 242 | for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) |
| 243 | INIT_LIST_HEAD(&info->data->iphash[i]); |
| 244 | |
| 245 | return true; |
| 246 | } |
| 247 | |
Jan Engelhardt | 6be3d85 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 248 | static void connlimit_mt_destroy(const struct xt_mtdtor_param *par) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 249 | { |
Jan Engelhardt | 6be3d85 | 2008-10-08 11:35:19 +0200 | [diff] [blame] | 250 | const struct xt_connlimit_info *info = par->matchinfo; |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 251 | struct xt_connlimit_conn *conn; |
| 252 | struct xt_connlimit_conn *tmp; |
| 253 | struct list_head *hash = info->data->iphash; |
| 254 | unsigned int i; |
| 255 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 256 | nf_ct_l3proto_module_put(par->family); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 257 | |
| 258 | for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) { |
| 259 | list_for_each_entry_safe(conn, tmp, &hash[i], list) { |
| 260 | list_del(&conn->list); |
| 261 | kfree(conn); |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | kfree(info->data); |
| 266 | } |
| 267 | |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 268 | static struct xt_match connlimit_mt_reg __read_mostly = { |
| 269 | .name = "connlimit", |
| 270 | .revision = 0, |
| 271 | .family = NFPROTO_UNSPEC, |
| 272 | .checkentry = connlimit_mt_check, |
| 273 | .match = connlimit_mt, |
| 274 | .matchsize = sizeof(struct xt_connlimit_info), |
| 275 | .destroy = connlimit_mt_destroy, |
| 276 | .me = THIS_MODULE, |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 277 | }; |
| 278 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 279 | static int __init connlimit_mt_init(void) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 280 | { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 281 | return xt_register_match(&connlimit_mt_reg); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 282 | } |
| 283 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 284 | static void __exit connlimit_mt_exit(void) |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 285 | { |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 286 | xt_unregister_match(&connlimit_mt_reg); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 287 | } |
| 288 | |
Jan Engelhardt | d3c5ee6 | 2007-12-04 23:24:03 -0800 | [diff] [blame] | 289 | module_init(connlimit_mt_init); |
| 290 | module_exit(connlimit_mt_exit); |
Jan Engelhardt | 92f3b2b | 2008-10-08 11:35:20 +0200 | [diff] [blame] | 291 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); |
Jan Engelhardt | 2ae15b6 | 2008-01-14 23:42:28 -0800 | [diff] [blame] | 292 | MODULE_DESCRIPTION("Xtables: Number of connections matching"); |
Jan Engelhardt | 370786f | 2007-07-14 20:47:26 -0700 | [diff] [blame] | 293 | MODULE_LICENSE("GPL"); |
| 294 | MODULE_ALIAS("ipt_connlimit"); |
| 295 | MODULE_ALIAS("ip6t_connlimit"); |