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Commit | Line | Data |
---|---|---|
370786f9 JE |
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 | |
ba5dc275 | 7 | * (C) CC Computer Consultants GmbH, 2007 |
370786f9 JE |
8 | * |
9 | * based on ... | |
10 | * | |
11 | * Kernel module to match connection tracking information. | |
12 | * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au). | |
13 | */ | |
8bee4bad | 14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
370786f9 JE |
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> | |
5a0e3ad6 | 20 | #include <linux/slab.h> |
370786f9 | 21 | #include <linux/list.h> |
7d084877 | 22 | #include <linux/rbtree.h> |
370786f9 JE |
23 | #include <linux/module.h> |
24 | #include <linux/random.h> | |
25 | #include <linux/skbuff.h> | |
26 | #include <linux/spinlock.h> | |
27 | #include <linux/netfilter/nf_conntrack_tcp.h> | |
28 | #include <linux/netfilter/x_tables.h> | |
29 | #include <linux/netfilter/xt_connlimit.h> | |
30 | #include <net/netfilter/nf_conntrack.h> | |
31 | #include <net/netfilter/nf_conntrack_core.h> | |
32 | #include <net/netfilter/nf_conntrack_tuple.h> | |
5d0aa2cc | 33 | #include <net/netfilter/nf_conntrack_zones.h> |
370786f9 | 34 | |
e00b437b FW |
35 | #define CONNLIMIT_SLOTS 256U |
36 | ||
37 | #ifdef CONFIG_LOCKDEP | |
38 | #define CONNLIMIT_LOCK_SLOTS 8U | |
39 | #else | |
40 | #define CONNLIMIT_LOCK_SLOTS 256U | |
41 | #endif | |
42 | ||
7d084877 | 43 | #define CONNLIMIT_GC_MAX_NODES 8 |
1442e750 | 44 | |
370786f9 JE |
45 | /* we will save the tuples of all connections we care about */ |
46 | struct xt_connlimit_conn { | |
3e0d5149 | 47 | struct hlist_node node; |
8183e3a8 | 48 | struct nf_conntrack_tuple tuple; |
370786f9 JE |
49 | }; |
50 | ||
7d084877 FW |
51 | struct xt_connlimit_rb { |
52 | struct rb_node node; | |
53 | struct hlist_head hhead; /* connections/hosts in same subnet */ | |
54 | union nf_inet_addr addr; /* search key */ | |
55 | }; | |
56 | ||
e00b437b FW |
57 | static spinlock_t xt_connlimit_locks[CONNLIMIT_LOCK_SLOTS] __cacheline_aligned_in_smp; |
58 | ||
370786f9 | 59 | struct xt_connlimit_data { |
a2acc543 | 60 | struct rb_root climit_root[CONNLIMIT_SLOTS]; |
370786f9 JE |
61 | }; |
62 | ||
294188ae | 63 | static u_int32_t connlimit_rnd __read_mostly; |
7d084877 | 64 | static struct kmem_cache *connlimit_rb_cachep __read_mostly; |
14e1a977 | 65 | static struct kmem_cache *connlimit_conn_cachep __read_mostly; |
370786f9 | 66 | |
a34c4589 | 67 | static inline unsigned int connlimit_iphash(__be32 addr) |
370786f9 | 68 | { |
1442e750 FW |
69 | return jhash_1word((__force __u32)addr, |
70 | connlimit_rnd) % CONNLIMIT_SLOTS; | |
370786f9 JE |
71 | } |
72 | ||
73 | static inline unsigned int | |
b1fc1372 | 74 | connlimit_iphash6(const union nf_inet_addr *addr) |
370786f9 | 75 | { |
b1fc1372 | 76 | return jhash2((u32 *)addr->ip6, ARRAY_SIZE(addr->ip6), |
1442e750 | 77 | connlimit_rnd) % CONNLIMIT_SLOTS; |
370786f9 JE |
78 | } |
79 | ||
80 | static inline bool already_closed(const struct nf_conn *conn) | |
81 | { | |
5e8fbe2a | 82 | if (nf_ct_protonum(conn) == IPPROTO_TCP) |
d2ee3f2c DW |
83 | return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT || |
84 | conn->proto.tcp.state == TCP_CONNTRACK_CLOSE; | |
370786f9 JE |
85 | else |
86 | return 0; | |
87 | } | |
88 | ||
50e0e9b1 | 89 | static int |
b1fc1372 FW |
90 | same_source(const union nf_inet_addr *addr, |
91 | const union nf_inet_addr *u3, u_int8_t family) | |
370786f9 | 92 | { |
b1fc1372 FW |
93 | if (family == NFPROTO_IPV4) |
94 | return ntohl(addr->ip) - ntohl(u3->ip); | |
370786f9 | 95 | |
b1fc1372 | 96 | return memcmp(addr->ip6, u3->ip6, sizeof(addr->ip6)); |
370786f9 JE |
97 | } |
98 | ||
7d084877 FW |
99 | static bool add_hlist(struct hlist_head *head, |
100 | const struct nf_conntrack_tuple *tuple, | |
101 | const union nf_inet_addr *addr) | |
102 | { | |
103 | struct xt_connlimit_conn *conn; | |
104 | ||
105 | conn = kmem_cache_alloc(connlimit_conn_cachep, GFP_ATOMIC); | |
106 | if (conn == NULL) | |
107 | return false; | |
108 | conn->tuple = *tuple; | |
7d084877 FW |
109 | hlist_add_head(&conn->node, head); |
110 | return true; | |
111 | } | |
112 | ||
113 | static unsigned int check_hlist(struct net *net, | |
114 | struct hlist_head *head, | |
115 | const struct nf_conntrack_tuple *tuple, | |
308ac914 | 116 | const struct nf_conntrack_zone *zone, |
7d084877 | 117 | bool *addit) |
370786f9 | 118 | { |
3cf93c96 | 119 | const struct nf_conntrack_tuple_hash *found; |
370786f9 | 120 | struct xt_connlimit_conn *conn; |
b67bfe0d | 121 | struct hlist_node *n; |
ea781f19 | 122 | struct nf_conn *found_ct; |
7d084877 | 123 | unsigned int length = 0; |
370786f9 | 124 | |
7d084877 | 125 | *addit = true; |
370786f9 JE |
126 | |
127 | /* check the saved connections */ | |
15cfd528 | 128 | hlist_for_each_entry_safe(conn, n, head, node) { |
e59ea3df | 129 | found = nf_conntrack_find_get(net, zone, &conn->tuple); |
d9ec4f1e FW |
130 | if (found == NULL) { |
131 | hlist_del(&conn->node); | |
14e1a977 | 132 | kmem_cache_free(connlimit_conn_cachep, conn); |
d9ec4f1e FW |
133 | continue; |
134 | } | |
370786f9 | 135 | |
d9ec4f1e | 136 | found_ct = nf_ct_tuplehash_to_ctrack(found); |
370786f9 | 137 | |
d9ec4f1e | 138 | if (nf_ct_tuple_equal(&conn->tuple, tuple)) { |
370786f9 JE |
139 | /* |
140 | * Just to be sure we have it only once in the list. | |
141 | * We should not see tuples twice unless someone hooks | |
142 | * this into a table without "-p tcp --syn". | |
143 | */ | |
3bcc5fdf | 144 | *addit = false; |
d9ec4f1e | 145 | } else if (already_closed(found_ct)) { |
370786f9 JE |
146 | /* |
147 | * we do not care about connections which are | |
148 | * closed already -> ditch it | |
149 | */ | |
ea781f19 | 150 | nf_ct_put(found_ct); |
3e0d5149 | 151 | hlist_del(&conn->node); |
14e1a977 | 152 | kmem_cache_free(connlimit_conn_cachep, conn); |
370786f9 JE |
153 | continue; |
154 | } | |
155 | ||
ea781f19 | 156 | nf_ct_put(found_ct); |
7d084877 | 157 | length++; |
370786f9 JE |
158 | } |
159 | ||
7d084877 | 160 | return length; |
370786f9 JE |
161 | } |
162 | ||
7d084877 FW |
163 | static void tree_nodes_free(struct rb_root *root, |
164 | struct xt_connlimit_rb *gc_nodes[], | |
165 | unsigned int gc_count) | |
166 | { | |
167 | struct xt_connlimit_rb *rbconn; | |
168 | ||
169 | while (gc_count) { | |
170 | rbconn = gc_nodes[--gc_count]; | |
171 | rb_erase(&rbconn->node, root); | |
172 | kmem_cache_free(connlimit_rb_cachep, rbconn); | |
173 | } | |
174 | } | |
175 | ||
176 | static unsigned int | |
177 | count_tree(struct net *net, struct rb_root *root, | |
178 | const struct nf_conntrack_tuple *tuple, | |
b1fc1372 | 179 | const union nf_inet_addr *addr, |
308ac914 | 180 | u8 family, const struct nf_conntrack_zone *zone) |
3bcc5fdf | 181 | { |
7d084877 FW |
182 | struct xt_connlimit_rb *gc_nodes[CONNLIMIT_GC_MAX_NODES]; |
183 | struct rb_node **rbnode, *parent; | |
184 | struct xt_connlimit_rb *rbconn; | |
14e1a977 | 185 | struct xt_connlimit_conn *conn; |
7d084877 FW |
186 | unsigned int gc_count; |
187 | bool no_gc = false; | |
188 | ||
189 | restart: | |
190 | gc_count = 0; | |
191 | parent = NULL; | |
192 | rbnode = &(root->rb_node); | |
193 | while (*rbnode) { | |
194 | int diff; | |
195 | bool addit; | |
196 | ||
4cc4b72c | 197 | rbconn = rb_entry(*rbnode, struct xt_connlimit_rb, node); |
7d084877 FW |
198 | |
199 | parent = *rbnode; | |
b1fc1372 | 200 | diff = same_source(addr, &rbconn->addr, family); |
7d084877 FW |
201 | if (diff < 0) { |
202 | rbnode = &((*rbnode)->rb_left); | |
203 | } else if (diff > 0) { | |
204 | rbnode = &((*rbnode)->rb_right); | |
205 | } else { | |
206 | /* same source network -> be counted! */ | |
207 | unsigned int count; | |
e59ea3df | 208 | count = check_hlist(net, &rbconn->hhead, tuple, zone, &addit); |
7d084877 FW |
209 | |
210 | tree_nodes_free(root, gc_nodes, gc_count); | |
211 | if (!addit) | |
212 | return count; | |
213 | ||
214 | if (!add_hlist(&rbconn->hhead, tuple, addr)) | |
215 | return 0; /* hotdrop */ | |
216 | ||
217 | return count + 1; | |
218 | } | |
219 | ||
220 | if (no_gc || gc_count >= ARRAY_SIZE(gc_nodes)) | |
221 | continue; | |
222 | ||
223 | /* only used for GC on hhead, retval and 'addit' ignored */ | |
e59ea3df | 224 | check_hlist(net, &rbconn->hhead, tuple, zone, &addit); |
7d084877 FW |
225 | if (hlist_empty(&rbconn->hhead)) |
226 | gc_nodes[gc_count++] = rbconn; | |
227 | } | |
228 | ||
229 | if (gc_count) { | |
230 | no_gc = true; | |
231 | tree_nodes_free(root, gc_nodes, gc_count); | |
232 | /* tree_node_free before new allocation permits | |
233 | * allocator to re-use newly free'd object. | |
234 | * | |
235 | * This is a rare event; in most cases we will find | |
236 | * existing node to re-use. (or gc_count is 0). | |
237 | */ | |
238 | goto restart; | |
239 | } | |
240 | ||
241 | /* no match, need to insert new node */ | |
242 | rbconn = kmem_cache_alloc(connlimit_rb_cachep, GFP_ATOMIC); | |
243 | if (rbconn == NULL) | |
244 | return 0; | |
14e1a977 FW |
245 | |
246 | conn = kmem_cache_alloc(connlimit_conn_cachep, GFP_ATOMIC); | |
7d084877 FW |
247 | if (conn == NULL) { |
248 | kmem_cache_free(connlimit_rb_cachep, rbconn); | |
249 | return 0; | |
250 | } | |
251 | ||
3bcc5fdf | 252 | conn->tuple = *tuple; |
7d084877 FW |
253 | rbconn->addr = *addr; |
254 | ||
255 | INIT_HLIST_HEAD(&rbconn->hhead); | |
256 | hlist_add_head(&conn->node, &rbconn->hhead); | |
257 | ||
258 | rb_link_node(&rbconn->node, parent, rbnode); | |
259 | rb_insert_color(&rbconn->node, root); | |
260 | return 1; | |
3bcc5fdf FW |
261 | } |
262 | ||
15cfd528 FW |
263 | static int count_them(struct net *net, |
264 | struct xt_connlimit_data *data, | |
265 | const struct nf_conntrack_tuple *tuple, | |
266 | const union nf_inet_addr *addr, | |
308ac914 DB |
267 | u_int8_t family, |
268 | const struct nf_conntrack_zone *zone) | |
15cfd528 | 269 | { |
7d084877 | 270 | struct rb_root *root; |
15cfd528 FW |
271 | int count; |
272 | u32 hash; | |
273 | ||
a2acc543 | 274 | if (family == NFPROTO_IPV6) |
b1fc1372 | 275 | hash = connlimit_iphash6(addr); |
a2acc543 | 276 | else |
b1fc1372 | 277 | hash = connlimit_iphash(addr->ip); |
a2acc543 | 278 | root = &data->climit_root[hash]; |
15cfd528 | 279 | |
e00b437b | 280 | spin_lock_bh(&xt_connlimit_locks[hash % CONNLIMIT_LOCK_SLOTS]); |
7d084877 | 281 | |
b1fc1372 | 282 | count = count_tree(net, root, tuple, addr, family, zone); |
7d084877 | 283 | |
e00b437b | 284 | spin_unlock_bh(&xt_connlimit_locks[hash % CONNLIMIT_LOCK_SLOTS]); |
15cfd528 FW |
285 | |
286 | return count; | |
287 | } | |
288 | ||
d3c5ee6d | 289 | static bool |
62fc8051 | 290 | connlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) |
370786f9 | 291 | { |
613dbd95 | 292 | struct net *net = xt_net(par); |
f7108a20 | 293 | const struct xt_connlimit_info *info = par->matchinfo; |
22c2d8bc | 294 | union nf_inet_addr addr; |
370786f9 JE |
295 | struct nf_conntrack_tuple tuple; |
296 | const struct nf_conntrack_tuple *tuple_ptr = &tuple; | |
308ac914 | 297 | const struct nf_conntrack_zone *zone = &nf_ct_zone_dflt; |
370786f9 JE |
298 | enum ip_conntrack_info ctinfo; |
299 | const struct nf_conn *ct; | |
7d084877 | 300 | unsigned int connections; |
370786f9 JE |
301 | |
302 | ct = nf_ct_get(skb, &ctinfo); | |
e59ea3df | 303 | if (ct != NULL) { |
8183e3a8 | 304 | tuple_ptr = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
e59ea3df FW |
305 | zone = nf_ct_zone(ct); |
306 | } else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), | |
613dbd95 | 307 | xt_family(par), net, &tuple)) { |
370786f9 | 308 | goto hotdrop; |
e59ea3df | 309 | } |
370786f9 | 310 | |
613dbd95 | 311 | if (xt_family(par) == NFPROTO_IPV6) { |
370786f9 | 312 | const struct ipv6hdr *iph = ipv6_hdr(skb); |
b1fc1372 FW |
313 | unsigned int i; |
314 | ||
cc4fc022 JE |
315 | memcpy(&addr.ip6, (info->flags & XT_CONNLIMIT_DADDR) ? |
316 | &iph->daddr : &iph->saddr, sizeof(addr.ip6)); | |
b1fc1372 FW |
317 | |
318 | for (i = 0; i < ARRAY_SIZE(addr.ip6); ++i) | |
319 | addr.ip6[i] &= info->mask.ip6[i]; | |
370786f9 JE |
320 | } else { |
321 | const struct iphdr *iph = ip_hdr(skb); | |
cc4fc022 JE |
322 | addr.ip = (info->flags & XT_CONNLIMIT_DADDR) ? |
323 | iph->daddr : iph->saddr; | |
b1fc1372 FW |
324 | |
325 | addr.ip &= info->mask.ip; | |
370786f9 JE |
326 | } |
327 | ||
83fc8102 | 328 | connections = count_them(net, info->data, tuple_ptr, &addr, |
b1fc1372 | 329 | xt_family(par), zone); |
7d084877 | 330 | if (connections == 0) |
370786f9 | 331 | /* kmalloc failed, drop it entirely */ |
1cc34c30 | 332 | goto hotdrop; |
370786f9 | 333 | |
cc4fc022 JE |
334 | return (connections > info->limit) ^ |
335 | !!(info->flags & XT_CONNLIMIT_INVERT); | |
370786f9 JE |
336 | |
337 | hotdrop: | |
b4ba2611 | 338 | par->hotdrop = true; |
370786f9 JE |
339 | return false; |
340 | } | |
341 | ||
b0f38452 | 342 | static int connlimit_mt_check(const struct xt_mtchk_param *par) |
370786f9 | 343 | { |
9b4fce7a | 344 | struct xt_connlimit_info *info = par->matchinfo; |
370786f9 | 345 | unsigned int i; |
4a5a5c73 | 346 | int ret; |
370786f9 | 347 | |
7bdc6624 | 348 | net_get_random_once(&connlimit_rnd, sizeof(connlimit_rnd)); |
4656c4d6 | 349 | |
ecb2421b | 350 | ret = nf_ct_netns_get(par->net, par->family); |
4a5a5c73 | 351 | if (ret < 0) { |
8bee4bad JE |
352 | pr_info("cannot load conntrack support for " |
353 | "address family %u\n", par->family); | |
4a5a5c73 | 354 | return ret; |
370786f9 JE |
355 | } |
356 | ||
357 | /* init private data */ | |
358 | info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL); | |
359 | if (info->data == NULL) { | |
ecb2421b | 360 | nf_ct_netns_put(par->net, par->family); |
4a5a5c73 | 361 | return -ENOMEM; |
370786f9 JE |
362 | } |
363 | ||
a2acc543 TY |
364 | for (i = 0; i < ARRAY_SIZE(info->data->climit_root); ++i) |
365 | info->data->climit_root[i] = RB_ROOT; | |
370786f9 | 366 | |
bd414ee6 | 367 | return 0; |
370786f9 JE |
368 | } |
369 | ||
7d084877 | 370 | static void destroy_tree(struct rb_root *r) |
370786f9 | 371 | { |
370786f9 | 372 | struct xt_connlimit_conn *conn; |
7d084877 | 373 | struct xt_connlimit_rb *rbconn; |
b67bfe0d | 374 | struct hlist_node *n; |
7d084877 | 375 | struct rb_node *node; |
370786f9 | 376 | |
7d084877 | 377 | while ((node = rb_first(r)) != NULL) { |
4cc4b72c | 378 | rbconn = rb_entry(node, struct xt_connlimit_rb, node); |
370786f9 | 379 | |
7d084877 FW |
380 | rb_erase(node, r); |
381 | ||
382 | hlist_for_each_entry_safe(conn, n, &rbconn->hhead, node) | |
14e1a977 | 383 | kmem_cache_free(connlimit_conn_cachep, conn); |
7d084877 FW |
384 | |
385 | kmem_cache_free(connlimit_rb_cachep, rbconn); | |
370786f9 | 386 | } |
7d084877 FW |
387 | } |
388 | ||
389 | static void connlimit_mt_destroy(const struct xt_mtdtor_param *par) | |
390 | { | |
391 | const struct xt_connlimit_info *info = par->matchinfo; | |
392 | unsigned int i; | |
393 | ||
ecb2421b | 394 | nf_ct_netns_put(par->net, par->family); |
7d084877 | 395 | |
a2acc543 TY |
396 | for (i = 0; i < ARRAY_SIZE(info->data->climit_root); ++i) |
397 | destroy_tree(&info->data->climit_root[i]); | |
370786f9 JE |
398 | |
399 | kfree(info->data); | |
400 | } | |
401 | ||
68c07cb6 CW |
402 | static struct xt_match connlimit_mt_reg __read_mostly = { |
403 | .name = "connlimit", | |
404 | .revision = 1, | |
405 | .family = NFPROTO_UNSPEC, | |
406 | .checkentry = connlimit_mt_check, | |
407 | .match = connlimit_mt, | |
408 | .matchsize = sizeof(struct xt_connlimit_info), | |
ec231890 | 409 | .usersize = offsetof(struct xt_connlimit_info, data), |
68c07cb6 CW |
410 | .destroy = connlimit_mt_destroy, |
411 | .me = THIS_MODULE, | |
370786f9 JE |
412 | }; |
413 | ||
d3c5ee6d | 414 | static int __init connlimit_mt_init(void) |
370786f9 | 415 | { |
e00b437b | 416 | int ret, i; |
1442e750 FW |
417 | |
418 | BUILD_BUG_ON(CONNLIMIT_LOCK_SLOTS > CONNLIMIT_SLOTS); | |
419 | BUILD_BUG_ON((CONNLIMIT_SLOTS % CONNLIMIT_LOCK_SLOTS) != 0); | |
420 | ||
e00b437b FW |
421 | for (i = 0; i < CONNLIMIT_LOCK_SLOTS; ++i) |
422 | spin_lock_init(&xt_connlimit_locks[i]); | |
423 | ||
14e1a977 FW |
424 | connlimit_conn_cachep = kmem_cache_create("xt_connlimit_conn", |
425 | sizeof(struct xt_connlimit_conn), | |
426 | 0, 0, NULL); | |
427 | if (!connlimit_conn_cachep) | |
428 | return -ENOMEM; | |
429 | ||
7d084877 FW |
430 | connlimit_rb_cachep = kmem_cache_create("xt_connlimit_rb", |
431 | sizeof(struct xt_connlimit_rb), | |
432 | 0, 0, NULL); | |
433 | if (!connlimit_rb_cachep) { | |
434 | kmem_cache_destroy(connlimit_conn_cachep); | |
435 | return -ENOMEM; | |
436 | } | |
14e1a977 | 437 | ret = xt_register_match(&connlimit_mt_reg); |
7d084877 | 438 | if (ret != 0) { |
14e1a977 | 439 | kmem_cache_destroy(connlimit_conn_cachep); |
7d084877 FW |
440 | kmem_cache_destroy(connlimit_rb_cachep); |
441 | } | |
14e1a977 | 442 | return ret; |
370786f9 JE |
443 | } |
444 | ||
d3c5ee6d | 445 | static void __exit connlimit_mt_exit(void) |
370786f9 | 446 | { |
68c07cb6 | 447 | xt_unregister_match(&connlimit_mt_reg); |
14e1a977 | 448 | kmem_cache_destroy(connlimit_conn_cachep); |
7d084877 | 449 | kmem_cache_destroy(connlimit_rb_cachep); |
370786f9 JE |
450 | } |
451 | ||
d3c5ee6d JE |
452 | module_init(connlimit_mt_init); |
453 | module_exit(connlimit_mt_exit); | |
92f3b2b1 | 454 | MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>"); |
2ae15b64 | 455 | MODULE_DESCRIPTION("Xtables: Number of connections matching"); |
370786f9 JE |
456 | MODULE_LICENSE("GPL"); |
457 | MODULE_ALIAS("ipt_connlimit"); | |
458 | MODULE_ALIAS("ip6t_connlimit"); |