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Linux/net/netfilter/nf_conntrack_ecache.c

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  1 /* Event cache for netfilter. */
  2 
  3 /*
  4  * (C) 2005 Harald Welte <laforge@gnumonks.org>
  5  * (C) 2005 Patrick McHardy <kaber@trash.net>
  6  * (C) 2005-2006 Netfilter Core Team <coreteam@netfilter.org>
  7  * (C) 2005 USAGI/WIDE Project <http://www.linux-ipv6.org>
  8  *
  9  * This program is free software; you can redistribute it and/or modify
 10  * it under the terms of the GNU General Public License version 2 as
 11  * published by the Free Software Foundation.
 12  */
 13 
 14 #include <linux/types.h>
 15 #include <linux/netfilter.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/vmalloc.h>
 18 #include <linux/stddef.h>
 19 #include <linux/err.h>
 20 #include <linux/percpu.h>
 21 #include <linux/kernel.h>
 22 #include <linux/netdevice.h>
 23 #include <linux/slab.h>
 24 #include <linux/export.h>
 25 
 26 #include <net/netfilter/nf_conntrack.h>
 27 #include <net/netfilter/nf_conntrack_core.h>
 28 #include <net/netfilter/nf_conntrack_extend.h>
 29 
 30 static DEFINE_MUTEX(nf_ct_ecache_mutex);
 31 
 32 #define ECACHE_RETRY_WAIT (HZ/10)
 33 
 34 enum retry_state {
 35         STATE_CONGESTED,
 36         STATE_RESTART,
 37         STATE_DONE,
 38 };
 39 
 40 static enum retry_state ecache_work_evict_list(struct ct_pcpu *pcpu)
 41 {
 42         struct nf_conn *refs[16];
 43         struct nf_conntrack_tuple_hash *h;
 44         struct hlist_nulls_node *n;
 45         unsigned int evicted = 0;
 46         enum retry_state ret = STATE_DONE;
 47 
 48         spin_lock(&pcpu->lock);
 49 
 50         hlist_nulls_for_each_entry(h, n, &pcpu->dying, hnnode) {
 51                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
 52 
 53                 if (nf_ct_is_dying(ct))
 54                         continue;
 55 
 56                 if (nf_conntrack_event(IPCT_DESTROY, ct)) {
 57                         ret = STATE_CONGESTED;
 58                         break;
 59                 }
 60 
 61                 /* we've got the event delivered, now it's dying */
 62                 set_bit(IPS_DYING_BIT, &ct->status);
 63                 refs[evicted] = ct;
 64 
 65                 if (++evicted >= ARRAY_SIZE(refs)) {
 66                         ret = STATE_RESTART;
 67                         break;
 68                 }
 69         }
 70 
 71         spin_unlock(&pcpu->lock);
 72 
 73         /* can't _put while holding lock */
 74         while (evicted)
 75                 nf_ct_put(refs[--evicted]);
 76 
 77         return ret;
 78 }
 79 
 80 static void ecache_work(struct work_struct *work)
 81 {
 82         struct netns_ct *ctnet =
 83                 container_of(work, struct netns_ct, ecache_dwork.work);
 84         int cpu, delay = -1;
 85         struct ct_pcpu *pcpu;
 86 
 87         local_bh_disable();
 88 
 89         for_each_possible_cpu(cpu) {
 90                 enum retry_state ret;
 91 
 92                 pcpu = per_cpu_ptr(ctnet->pcpu_lists, cpu);
 93 
 94                 ret = ecache_work_evict_list(pcpu);
 95 
 96                 switch (ret) {
 97                 case STATE_CONGESTED:
 98                         delay = ECACHE_RETRY_WAIT;
 99                         goto out;
100                 case STATE_RESTART:
101                         delay = 0;
102                         break;
103                 case STATE_DONE:
104                         break;
105                 }
106         }
107 
108  out:
109         local_bh_enable();
110 
111         ctnet->ecache_dwork_pending = delay > 0;
112         if (delay >= 0)
113                 schedule_delayed_work(&ctnet->ecache_dwork, delay);
114 }
115 
116 /* deliver cached events and clear cache entry - must be called with locally
117  * disabled softirqs */
118 void nf_ct_deliver_cached_events(struct nf_conn *ct)
119 {
120         struct net *net = nf_ct_net(ct);
121         unsigned long events, missed;
122         struct nf_ct_event_notifier *notify;
123         struct nf_conntrack_ecache *e;
124         struct nf_ct_event item;
125         int ret;
126 
127         rcu_read_lock();
128         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
129         if (notify == NULL)
130                 goto out_unlock;
131 
132         e = nf_ct_ecache_find(ct);
133         if (e == NULL)
134                 goto out_unlock;
135 
136         events = xchg(&e->cache, 0);
137 
138         if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events)
139                 goto out_unlock;
140 
141         /* We make a copy of the missed event cache without taking
142          * the lock, thus we may send missed events twice. However,
143          * this does not harm and it happens very rarely. */
144         missed = e->missed;
145 
146         if (!((events | missed) & e->ctmask))
147                 goto out_unlock;
148 
149         item.ct = ct;
150         item.portid = 0;
151         item.report = 0;
152 
153         ret = notify->fcn(events | missed, &item);
154 
155         if (likely(ret >= 0 && !missed))
156                 goto out_unlock;
157 
158         spin_lock_bh(&ct->lock);
159         if (ret < 0)
160                 e->missed |= events;
161         else
162                 e->missed &= ~missed;
163         spin_unlock_bh(&ct->lock);
164 
165 out_unlock:
166         rcu_read_unlock();
167 }
168 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
169 
170 int nf_conntrack_register_notifier(struct net *net,
171                                    struct nf_ct_event_notifier *new)
172 {
173         int ret;
174         struct nf_ct_event_notifier *notify;
175 
176         mutex_lock(&nf_ct_ecache_mutex);
177         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
178                                            lockdep_is_held(&nf_ct_ecache_mutex));
179         if (notify != NULL) {
180                 ret = -EBUSY;
181                 goto out_unlock;
182         }
183         rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
184         ret = 0;
185 
186 out_unlock:
187         mutex_unlock(&nf_ct_ecache_mutex);
188         return ret;
189 }
190 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
191 
192 void nf_conntrack_unregister_notifier(struct net *net,
193                                       struct nf_ct_event_notifier *new)
194 {
195         struct nf_ct_event_notifier *notify;
196 
197         mutex_lock(&nf_ct_ecache_mutex);
198         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
199                                            lockdep_is_held(&nf_ct_ecache_mutex));
200         BUG_ON(notify != new);
201         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
202         mutex_unlock(&nf_ct_ecache_mutex);
203 }
204 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
205 
206 int nf_ct_expect_register_notifier(struct net *net,
207                                    struct nf_exp_event_notifier *new)
208 {
209         int ret;
210         struct nf_exp_event_notifier *notify;
211 
212         mutex_lock(&nf_ct_ecache_mutex);
213         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
214                                            lockdep_is_held(&nf_ct_ecache_mutex));
215         if (notify != NULL) {
216                 ret = -EBUSY;
217                 goto out_unlock;
218         }
219         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
220         ret = 0;
221 
222 out_unlock:
223         mutex_unlock(&nf_ct_ecache_mutex);
224         return ret;
225 }
226 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
227 
228 void nf_ct_expect_unregister_notifier(struct net *net,
229                                       struct nf_exp_event_notifier *new)
230 {
231         struct nf_exp_event_notifier *notify;
232 
233         mutex_lock(&nf_ct_ecache_mutex);
234         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
235                                            lockdep_is_held(&nf_ct_ecache_mutex));
236         BUG_ON(notify != new);
237         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
238         mutex_unlock(&nf_ct_ecache_mutex);
239 }
240 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
241 
242 #define NF_CT_EVENTS_DEFAULT 1
243 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
244 
245 #ifdef CONFIG_SYSCTL
246 static struct ctl_table event_sysctl_table[] = {
247         {
248                 .procname       = "nf_conntrack_events",
249                 .data           = &init_net.ct.sysctl_events,
250                 .maxlen         = sizeof(unsigned int),
251                 .mode           = 0644,
252                 .proc_handler   = proc_dointvec,
253         },
254         {}
255 };
256 #endif /* CONFIG_SYSCTL */
257 
258 static struct nf_ct_ext_type event_extend __read_mostly = {
259         .len    = sizeof(struct nf_conntrack_ecache),
260         .align  = __alignof__(struct nf_conntrack_ecache),
261         .id     = NF_CT_EXT_ECACHE,
262 };
263 
264 #ifdef CONFIG_SYSCTL
265 static int nf_conntrack_event_init_sysctl(struct net *net)
266 {
267         struct ctl_table *table;
268 
269         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
270                         GFP_KERNEL);
271         if (!table)
272                 goto out;
273 
274         table[0].data = &net->ct.sysctl_events;
275 
276         /* Don't export sysctls to unprivileged users */
277         if (net->user_ns != &init_user_ns)
278                 table[0].procname = NULL;
279 
280         net->ct.event_sysctl_header =
281                 register_net_sysctl(net, "net/netfilter", table);
282         if (!net->ct.event_sysctl_header) {
283                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
284                 goto out_register;
285         }
286         return 0;
287 
288 out_register:
289         kfree(table);
290 out:
291         return -ENOMEM;
292 }
293 
294 static void nf_conntrack_event_fini_sysctl(struct net *net)
295 {
296         struct ctl_table *table;
297 
298         table = net->ct.event_sysctl_header->ctl_table_arg;
299         unregister_net_sysctl_table(net->ct.event_sysctl_header);
300         kfree(table);
301 }
302 #else
303 static int nf_conntrack_event_init_sysctl(struct net *net)
304 {
305         return 0;
306 }
307 
308 static void nf_conntrack_event_fini_sysctl(struct net *net)
309 {
310 }
311 #endif /* CONFIG_SYSCTL */
312 
313 int nf_conntrack_ecache_pernet_init(struct net *net)
314 {
315         net->ct.sysctl_events = nf_ct_events;
316         INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work);
317         return nf_conntrack_event_init_sysctl(net);
318 }
319 
320 void nf_conntrack_ecache_pernet_fini(struct net *net)
321 {
322         cancel_delayed_work_sync(&net->ct.ecache_dwork);
323         nf_conntrack_event_fini_sysctl(net);
324 }
325 
326 int nf_conntrack_ecache_init(void)
327 {
328         int ret = nf_ct_extend_register(&event_extend);
329         if (ret < 0)
330                 pr_err("nf_ct_event: Unable to register event extension.\n");
331         return ret;
332 }
333 
334 void nf_conntrack_ecache_fini(void)
335 {
336         nf_ct_extend_unregister(&event_extend);
337 }
338 

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