1// SPDX-License-Identifier: GPL-2.0-only
2/* Event cache for netfilter. */
3
4/*
5 * (C) 2005 Harald Welte <laforge@gnumonks.org>
6 * (C) 2005 Patrick McHardy <kaber@trash.net>
7 * (C) 2005-2006 Netfilter Core Team <coreteam@netfilter.org>
8 * (C) 2005 USAGI/WIDE Project <http://www.linux-ipv6.org>
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/types.h>
14#include <linux/netfilter.h>
15#include <linux/skbuff.h>
16#include <linux/vmalloc.h>
17#include <linux/stddef.h>
18#include <linux/err.h>
19#include <linux/kernel.h>
20#include <linux/netdevice.h>
21#include <linux/slab.h>
22#include <linux/export.h>
23
24#include <net/netfilter/nf_conntrack.h>
25#include <net/netfilter/nf_conntrack_core.h>
26#include <net/netfilter/nf_conntrack_ecache.h>
27#include <net/netfilter/nf_conntrack_extend.h>
28
29static DEFINE_MUTEX(nf_ct_ecache_mutex);
30
31#define DYING_NULLS_VAL ((1 << 30) + 1)
32#define ECACHE_MAX_JIFFIES msecs_to_jiffies(10)
33#define ECACHE_RETRY_JIFFIES msecs_to_jiffies(10)
34
35enum retry_state {
36 STATE_CONGESTED,
37 STATE_RESTART,
38 STATE_DONE,
39};
40
41struct nf_conntrack_net_ecache *nf_conn_pernet_ecache(const struct net *net)
42{
43 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
44
45 return &cnet->ecache;
46}
47#if IS_MODULE(CONFIG_NF_CT_NETLINK)
48EXPORT_SYMBOL_GPL(nf_conn_pernet_ecache);
49#endif
50
51static enum retry_state ecache_work_evict_list(struct nf_conntrack_net *cnet)
52{
53 unsigned long stop = jiffies + ECACHE_MAX_JIFFIES;
54 struct hlist_nulls_head evicted_list;
55 enum retry_state ret = STATE_DONE;
56 struct nf_conntrack_tuple_hash *h;
57 struct hlist_nulls_node *n;
58 unsigned int sent;
59
60 INIT_HLIST_NULLS_HEAD(&evicted_list, DYING_NULLS_VAL);
61
62next:
63 sent = 0;
64 spin_lock_bh(lock: &cnet->ecache.dying_lock);
65
66 hlist_nulls_for_each_entry_safe(h, n, &cnet->ecache.dying_list, hnnode) {
67 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(hash: h);
68
69 /* The worker owns all entries, ct remains valid until nf_ct_put
70 * in the loop below.
71 */
72 if (nf_conntrack_event(event: IPCT_DESTROY, ct)) {
73 ret = STATE_CONGESTED;
74 break;
75 }
76
77 hlist_nulls_del_rcu(n: &ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
78 hlist_nulls_add_head(n: &ct->tuplehash[IP_CT_DIR_REPLY].hnnode, h: &evicted_list);
79
80 if (time_after(stop, jiffies)) {
81 ret = STATE_RESTART;
82 break;
83 }
84
85 if (sent++ > 16) {
86 spin_unlock_bh(lock: &cnet->ecache.dying_lock);
87 cond_resched();
88 goto next;
89 }
90 }
91
92 spin_unlock_bh(lock: &cnet->ecache.dying_lock);
93
94 hlist_nulls_for_each_entry_safe(h, n, &evicted_list, hnnode) {
95 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(hash: h);
96
97 hlist_nulls_del_rcu(n: &ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
98 nf_ct_put(ct);
99
100 cond_resched();
101 }
102
103 return ret;
104}
105
106static void ecache_work(struct work_struct *work)
107{
108 struct nf_conntrack_net *cnet = container_of(work, struct nf_conntrack_net, ecache.dwork.work);
109 int ret, delay = -1;
110
111 ret = ecache_work_evict_list(cnet);
112 switch (ret) {
113 case STATE_CONGESTED:
114 delay = ECACHE_RETRY_JIFFIES;
115 break;
116 case STATE_RESTART:
117 delay = 0;
118 break;
119 case STATE_DONE:
120 break;
121 }
122
123 if (delay >= 0)
124 schedule_delayed_work(dwork: &cnet->ecache.dwork, delay);
125}
126
127static int __nf_conntrack_eventmask_report(struct nf_conntrack_ecache *e,
128 const u32 events,
129 const u32 missed,
130 const struct nf_ct_event *item)
131{
132 struct net *net = nf_ct_net(ct: item->ct);
133 struct nf_ct_event_notifier *notify;
134 u32 old, want;
135 int ret;
136
137 if (!((events | missed) & e->ctmask))
138 return 0;
139
140 rcu_read_lock();
141
142 notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
143 if (!notify) {
144 rcu_read_unlock();
145 return 0;
146 }
147
148 ret = notify->ct_event(events | missed, item);
149 rcu_read_unlock();
150
151 if (likely(ret >= 0 && missed == 0))
152 return 0;
153
154 do {
155 old = READ_ONCE(e->missed);
156 if (ret < 0)
157 want = old | events;
158 else
159 want = old & ~missed;
160 } while (cmpxchg(&e->missed, old, want) != old);
161
162 return ret;
163}
164
165static void nf_ct_ecache_tstamp_refresh(struct nf_conntrack_ecache *e)
166{
167#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
168 if (local64_read(&e->timestamp))
169 local64_set(&e->timestamp, ktime_get_real_ns());
170#endif
171}
172
173int nf_conntrack_eventmask_report(unsigned int events, struct nf_conn *ct,
174 u32 portid, int report)
175{
176 struct nf_conntrack_ecache *e;
177 struct nf_ct_event item;
178 unsigned int missed;
179 int ret;
180
181 if (!nf_ct_is_confirmed(ct))
182 return 0;
183
184 e = nf_ct_ecache_find(ct);
185 if (!e)
186 return 0;
187
188 memset(&item, 0, sizeof(item));
189
190 item.ct = ct;
191 item.portid = e->portid ? e->portid : portid;
192 item.report = report;
193
194 /* This is a resent of a destroy event? If so, skip missed */
195 missed = e->portid ? 0 : e->missed;
196
197 nf_ct_ecache_tstamp_refresh(e);
198
199 ret = __nf_conntrack_eventmask_report(e, events, missed, item: &item);
200 if (unlikely(ret < 0 && (events & (1 << IPCT_DESTROY)))) {
201 /* This is a destroy event that has been triggered by a process,
202 * we store the PORTID to include it in the retransmission.
203 */
204 if (e->portid == 0 && portid != 0)
205 e->portid = portid;
206 }
207
208 return ret;
209}
210EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
211
212/* deliver cached events and clear cache entry - must be called with locally
213 * disabled softirqs */
214void nf_ct_deliver_cached_events(struct nf_conn *ct)
215{
216 struct nf_conntrack_ecache *e;
217 struct nf_ct_event item;
218 unsigned int events;
219
220 if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct))
221 return;
222
223 e = nf_ct_ecache_find(ct);
224 if (e == NULL)
225 return;
226
227 events = xchg(&e->cache, 0);
228
229 item.ct = ct;
230 item.portid = 0;
231 item.report = 0;
232
233 /* We make a copy of the missed event cache without taking
234 * the lock, thus we may send missed events twice. However,
235 * this does not harm and it happens very rarely.
236 */
237 __nf_conntrack_eventmask_report(e, events, missed: e->missed, item: &item);
238}
239EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
240
241void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
242 struct nf_conntrack_expect *exp,
243 u32 portid, int report)
244
245{
246 struct net *net = nf_ct_exp_net(exp);
247 struct nf_ct_event_notifier *notify;
248 struct nf_conntrack_ecache *e;
249
250 rcu_read_lock();
251 notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
252 if (!notify)
253 goto out_unlock;
254
255 e = nf_ct_ecache_find(ct: exp->master);
256 if (!e)
257 goto out_unlock;
258
259 if (e->expmask & (1 << event)) {
260 struct nf_exp_event item = {
261 .exp = exp,
262 .portid = portid,
263 .report = report
264 };
265 notify->exp_event(1 << event, &item);
266 }
267out_unlock:
268 rcu_read_unlock();
269}
270
271void nf_conntrack_register_notifier(struct net *net,
272 const struct nf_ct_event_notifier *new)
273{
274 struct nf_ct_event_notifier *notify;
275
276 mutex_lock(&nf_ct_ecache_mutex);
277 notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
278 lockdep_is_held(&nf_ct_ecache_mutex));
279 WARN_ON_ONCE(notify);
280 rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
281 mutex_unlock(lock: &nf_ct_ecache_mutex);
282}
283EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
284
285void nf_conntrack_unregister_notifier(struct net *net)
286{
287 mutex_lock(&nf_ct_ecache_mutex);
288 RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
289 mutex_unlock(lock: &nf_ct_ecache_mutex);
290 /* synchronize_rcu() is called after netns pre_exit */
291}
292EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
293
294void nf_conntrack_ecache_work(struct net *net, enum nf_ct_ecache_state state)
295{
296 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
297
298 if (state == NFCT_ECACHE_DESTROY_FAIL &&
299 !delayed_work_pending(&cnet->ecache.dwork)) {
300 schedule_delayed_work(dwork: &cnet->ecache.dwork, HZ);
301 net->ct.ecache_dwork_pending = true;
302 } else if (state == NFCT_ECACHE_DESTROY_SENT) {
303 if (!hlist_nulls_empty(h: &cnet->ecache.dying_list))
304 mod_delayed_work(wq: system_percpu_wq, dwork: &cnet->ecache.dwork, delay: 0);
305 else
306 net->ct.ecache_dwork_pending = false;
307 }
308}
309
310static void nf_ct_ecache_tstamp_new(const struct nf_conn *ct, struct nf_conntrack_ecache *e)
311{
312#ifdef CONFIG_NF_CONNTRACK_TIMESTAMP
313 u64 ts = 0;
314
315 if (nf_ct_ext_exist(ct, id: NF_CT_EXT_TSTAMP))
316 ts = ktime_get_real_ns();
317
318 local64_set(&e->timestamp, ts);
319#endif
320}
321
322bool nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp)
323{
324 struct net *net = nf_ct_net(ct);
325 struct nf_conntrack_ecache *e;
326
327 switch (net->ct.sysctl_events) {
328 case 0:
329 /* assignment via template / ruleset? ignore sysctl. */
330 if (ctmask || expmask)
331 break;
332 return true;
333 case 2: /* autodetect: no event listener, don't allocate extension. */
334 if (!READ_ONCE(nf_ctnetlink_has_listener))
335 return true;
336 fallthrough;
337 case 1:
338 /* always allocate an extension. */
339 if (!ctmask && !expmask) {
340 ctmask = ~0;
341 expmask = ~0;
342 }
343 break;
344 default:
345 WARN_ON_ONCE(1);
346 return true;
347 }
348
349 e = nf_ct_ext_add(ct, id: NF_CT_EXT_ECACHE, gfp);
350 if (e) {
351 nf_ct_ecache_tstamp_new(ct, e);
352 e->ctmask = ctmask;
353 e->expmask = expmask;
354 }
355
356 return e != NULL;
357}
358EXPORT_SYMBOL_GPL(nf_ct_ecache_ext_add);
359
360#define NF_CT_EVENTS_DEFAULT 2
361static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
362
363void nf_conntrack_ecache_pernet_init(struct net *net)
364{
365 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
366
367 net->ct.sysctl_events = nf_ct_events;
368
369 INIT_DELAYED_WORK(&cnet->ecache.dwork, ecache_work);
370 INIT_HLIST_NULLS_HEAD(&cnet->ecache.dying_list, DYING_NULLS_VAL);
371 spin_lock_init(&cnet->ecache.dying_lock);
372
373 BUILD_BUG_ON(__IPCT_MAX >= 16); /* e->ctmask is u16 */
374}
375
376void nf_conntrack_ecache_pernet_fini(struct net *net)
377{
378 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
379
380 cancel_delayed_work_sync(dwork: &cnet->ecache.dwork);
381}
382

source code of linux/net/netfilter/nf_conntrack_ecache.c