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authorJan Engelhardt <jengelh@gmx.de>2007-07-14 23:47:26 -0400
committerDavid S. Miller <davem@davemloft.net>2007-07-14 23:47:26 -0400
commit370786f9cfd430cb424f00ce4110e75bb1b95a19 (patch)
treedf0e51882850f8db8da8f6e4ab746179b1993b9c /net
parenta887c1c148ffb3eb1c193e9869ca5297c6e22078 (diff)
[NETFILTER]: x_tables: add connlimit match
ipt_connlimit has been sitting in POM-NG for a long time. Here is a new shiny xt_connlimit with: * xtables'ified * will request the layer3 module (previously it hotdropped every packet when it was not loaded) * fixed: there was a deadlock in case of an OOM condition * support for any layer4 protocol (e.g. UDP/SCTP) * using jhash, as suggested by Eric Dumazet * ipv6 support Signed-off-by: Jan Engelhardt <jengelh@gmx.de> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/Kconfig7
-rw-r--r--net/netfilter/Makefile1
-rw-r--r--net/netfilter/xt_connlimit.c313
3 files changed, 321 insertions, 0 deletions
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index df5e8dab871d..9415b9a5dba6 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -423,6 +423,13 @@ config NETFILTER_XT_MATCH_CONNBYTES
423 If you want to compile it as a module, say M here and read 423 If you want to compile it as a module, say M here and read
424 <file:Documentation/kbuild/modules.txt>. If unsure, say `N'. 424 <file:Documentation/kbuild/modules.txt>. If unsure, say `N'.
425 425
426config NETFILTER_XT_MATCH_CONNLIMIT
427 tristate '"connlimit" match support"'
428 depends on NETFILTER_XTABLES
429 ---help---
430 This match allows you to match against the number of parallel
431 connections to a server per client IP address (or address block).
432
426config NETFILTER_XT_MATCH_CONNMARK 433config NETFILTER_XT_MATCH_CONNMARK
427 tristate '"connmark" connection mark match support' 434 tristate '"connmark" connection mark match support'
428 depends on NETFILTER_XTABLES 435 depends on NETFILTER_XTABLES
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 58b4245a1723..3e4a16aeb04e 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_NETFILTER_XT_TARGET_CONNSECMARK) += xt_CONNSECMARK.o
52# matches 52# matches
53obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o 53obj-$(CONFIG_NETFILTER_XT_MATCH_COMMENT) += xt_comment.o
54obj-$(CONFIG_NETFILTER_XT_MATCH_CONNBYTES) += xt_connbytes.o 54obj-$(CONFIG_NETFILTER_XT_MATCH_CONNBYTES) += xt_connbytes.o
55obj-$(CONFIG_NETFILTER_XT_MATCH_CONNLIMIT) += xt_connlimit.o
55obj-$(CONFIG_NETFILTER_XT_MATCH_CONNMARK) += xt_connmark.o 56obj-$(CONFIG_NETFILTER_XT_MATCH_CONNMARK) += xt_connmark.o
56obj-$(CONFIG_NETFILTER_XT_MATCH_CONNTRACK) += xt_conntrack.o 57obj-$(CONFIG_NETFILTER_XT_MATCH_CONNTRACK) += xt_conntrack.o
57obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o 58obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o
diff --git a/net/netfilter/xt_connlimit.c b/net/netfilter/xt_connlimit.c
new file mode 100644
index 000000000000..3335dd5be962
--- /dev/null
+++ b/net/netfilter/xt_connlimit.c
@@ -0,0 +1,313 @@
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 * Copyright © Jan Engelhardt <jengelh@gmx.de>, 2007
8 *
9 * based on ...
10 *
11 * Kernel module to match connection tracking information.
12 * GPL (C) 1999 Rusty Russell (rusty@rustcorp.com.au).
13 */
14#include <linux/in.h>
15#include <linux/in6.h>
16#include <linux/ip.h>
17#include <linux/ipv6.h>
18#include <linux/jhash.h>
19#include <linux/list.h>
20#include <linux/module.h>
21#include <linux/random.h>
22#include <linux/skbuff.h>
23#include <linux/spinlock.h>
24#include <linux/netfilter/nf_conntrack_tcp.h>
25#include <linux/netfilter/x_tables.h>
26#include <linux/netfilter/xt_connlimit.h>
27#include <net/netfilter/nf_conntrack.h>
28#include <net/netfilter/nf_conntrack_core.h>
29#include <net/netfilter/nf_conntrack_tuple.h>
30
31/* we will save the tuples of all connections we care about */
32struct xt_connlimit_conn {
33 struct list_head list;
34 struct nf_conntrack_tuple tuple;
35};
36
37struct xt_connlimit_data {
38 struct list_head iphash[256];
39 spinlock_t lock;
40};
41
42static u_int32_t connlimit_rnd;
43static bool connlimit_rnd_inited;
44
45static inline unsigned int connlimit_iphash(u_int32_t addr)
46{
47 if (unlikely(!connlimit_rnd_inited)) {
48 get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd));
49 connlimit_rnd_inited = true;
50 }
51 return jhash_1word(addr, connlimit_rnd) & 0xFF;
52}
53
54static inline unsigned int
55connlimit_iphash6(const union nf_conntrack_address *addr,
56 const union nf_conntrack_address *mask)
57{
58 union nf_conntrack_address res;
59 unsigned int i;
60
61 if (unlikely(!connlimit_rnd_inited)) {
62 get_random_bytes(&connlimit_rnd, sizeof(connlimit_rnd));
63 connlimit_rnd_inited = true;
64 }
65
66 for (i = 0; i < ARRAY_SIZE(addr->ip6); ++i)
67 res.ip6[i] = addr->ip6[i] & mask->ip6[i];
68
69 return jhash2(res.ip6, ARRAY_SIZE(res.ip6), connlimit_rnd) & 0xFF;
70}
71
72static inline bool already_closed(const struct nf_conn *conn)
73{
74 u_int16_t proto = conn->tuplehash[0].tuple.dst.protonum;
75
76 if (proto == IPPROTO_TCP)
77 return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT;
78 else
79 return 0;
80}
81
82static inline unsigned int
83same_source_net(const union nf_conntrack_address *addr,
84 const union nf_conntrack_address *mask,
85 const union nf_conntrack_address *u3, unsigned int family)
86{
87 if (family == AF_INET) {
88 return (addr->ip & mask->ip) == (u3->ip & mask->ip);
89 } else {
90 union nf_conntrack_address lh, rh;
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
102static int count_them(struct xt_connlimit_data *data,
103 const struct nf_conntrack_tuple *tuple,
104 const union nf_conntrack_address *addr,
105 const union nf_conntrack_address *mask,
106 const struct xt_match *match)
107{
108 struct nf_conntrack_tuple_hash *found;
109 struct xt_connlimit_conn *conn;
110 struct xt_connlimit_conn *tmp;
111 struct nf_conn *found_ct;
112 struct list_head *hash;
113 bool addit = true;
114 int matches = 0;
115
116
117 if (match->family == AF_INET6)
118 hash = &data->iphash[connlimit_iphash6(addr, mask)];
119 else
120 hash = &data->iphash[connlimit_iphash(addr->ip & mask->ip)];
121
122 read_lock_bh(&nf_conntrack_lock);
123
124 /* check the saved connections */
125 list_for_each_entry_safe(conn, tmp, hash, list) {
126 found = __nf_conntrack_find(&conn->tuple, NULL);
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
165 read_unlock_bh(&nf_conntrack_lock);
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
180static bool connlimit_match(const struct sk_buff *skb,
181 const struct net_device *in,
182 const struct net_device *out,
183 const struct xt_match *match,
184 const void *matchinfo, int offset,
185 unsigned int protoff, bool *hotdrop)
186{
187 const struct xt_connlimit_info *info = matchinfo;
188 union nf_conntrack_address addr, mask;
189 struct nf_conntrack_tuple tuple;
190 const struct nf_conntrack_tuple *tuple_ptr = &tuple;
191 enum ip_conntrack_info ctinfo;
192 const struct nf_conn *ct;
193 int connections;
194
195 ct = nf_ct_get(skb, &ctinfo);
196 if (ct != NULL)
197 tuple_ptr = &ct->tuplehash[0].tuple;
198 else if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
199 match->family, &tuple))
200 goto hotdrop;
201
202 if (match->family == AF_INET6) {
203 const struct ipv6hdr *iph = ipv6_hdr(skb);
204 memcpy(&addr.ip6, &iph->saddr, sizeof(iph->saddr));
205 memcpy(&mask.ip6, info->v6_mask, sizeof(info->v6_mask));
206 } else {
207 const struct iphdr *iph = ip_hdr(skb);
208 addr.ip = iph->saddr;
209 mask.ip = info->v4_mask;
210 }
211
212 spin_lock_bh(&info->data->lock);
213 connections = count_them(info->data, tuple_ptr, &addr, &mask, match);
214 spin_unlock_bh(&info->data->lock);
215
216 if (connections < 0) {
217 /* kmalloc failed, drop it entirely */
218 *hotdrop = true;
219 return false;
220 }
221
222 return (connections > info->limit) ^ info->inverse;
223
224 hotdrop:
225 *hotdrop = true;
226 return false;
227}
228
229static bool connlimit_check(const char *tablename, const void *ip,
230 const struct xt_match *match, void *matchinfo,
231 unsigned int hook_mask)
232{
233 struct xt_connlimit_info *info = matchinfo;
234 unsigned int i;
235
236 if (nf_ct_l3proto_try_module_get(match->family) < 0) {
237 printk(KERN_WARNING "cannot load conntrack support for "
238 "address family %u\n", match->family);
239 return false;
240 }
241
242 /* init private data */
243 info->data = kmalloc(sizeof(struct xt_connlimit_data), GFP_KERNEL);
244 if (info->data == NULL) {
245 nf_ct_l3proto_module_put(match->family);
246 return false;
247 }
248
249 spin_lock_init(&info->data->lock);
250 for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i)
251 INIT_LIST_HEAD(&info->data->iphash[i]);
252
253 return true;
254}
255
256static void connlimit_destroy(const struct xt_match *match, void *matchinfo)
257{
258 struct xt_connlimit_info *info = matchinfo;
259 struct xt_connlimit_conn *conn;
260 struct xt_connlimit_conn *tmp;
261 struct list_head *hash = info->data->iphash;
262 unsigned int i;
263
264 nf_ct_l3proto_module_put(match->family);
265
266 for (i = 0; i < ARRAY_SIZE(info->data->iphash); ++i) {
267 list_for_each_entry_safe(conn, tmp, &hash[i], list) {
268 list_del(&conn->list);
269 kfree(conn);
270 }
271 }
272
273 kfree(info->data);
274}
275
276static struct xt_match connlimit_reg[] __read_mostly = {
277 {
278 .name = "connlimit",
279 .family = AF_INET,
280 .checkentry = connlimit_check,
281 .match = connlimit_match,
282 .matchsize = sizeof(struct xt_connlimit_info),
283 .destroy = connlimit_destroy,
284 .me = THIS_MODULE,
285 },
286 {
287 .name = "connlimit",
288 .family = AF_INET6,
289 .checkentry = connlimit_check,
290 .match = connlimit_match,
291 .matchsize = sizeof(struct xt_connlimit_info),
292 .destroy = connlimit_destroy,
293 .me = THIS_MODULE,
294 },
295};
296
297static int __init xt_connlimit_init(void)
298{
299 return xt_register_matches(connlimit_reg, ARRAY_SIZE(connlimit_reg));
300}
301
302static void __exit xt_connlimit_exit(void)
303{
304 xt_unregister_matches(connlimit_reg, ARRAY_SIZE(connlimit_reg));
305}
306
307module_init(xt_connlimit_init);
308module_exit(xt_connlimit_exit);
309MODULE_AUTHOR("Jan Engelhardt <jengelh@gmx.de>");
310MODULE_DESCRIPTION("netfilter xt_connlimit match module");
311MODULE_LICENSE("GPL");
312MODULE_ALIAS("ipt_connlimit");
313MODULE_ALIAS("ip6t_connlimit");