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
29 static 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
35 enum retry_state {
36 STATE_CONGESTED,
37 STATE_RESTART,
38 STATE_DONE,
39 };
40
nf_conn_pernet_ecache(const struct net * net)41 struct 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)
48 EXPORT_SYMBOL_GPL(nf_conn_pernet_ecache);
49 #endif
50
ecache_work_evict_list(struct nf_conntrack_net * cnet)51 static 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
62 next:
63 sent = 0;
64 spin_lock_bh(&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(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(IPCT_DESTROY, ct)) {
73 ret = STATE_CONGESTED;
74 break;
75 }
76
77 hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode);
78 hlist_nulls_add_head(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode, &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(&cnet->ecache.dying_lock);
87 cond_resched();
88 goto next;
89 }
90 }
91
92 spin_unlock_bh(&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(h);
96
97 hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode);
98 nf_ct_put(ct);
99
100 cond_resched();
101 }
102
103 return ret;
104 }
105
ecache_work(struct work_struct * work)106 static 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(&cnet->ecache.dwork, delay);
125 }
126
__nf_conntrack_eventmask_report(struct nf_conntrack_ecache * e,const u32 events,const u32 missed,const struct nf_ct_event * item)127 static 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(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
nf_conntrack_eventmask_report(unsigned int events,struct nf_conn * ct,u32 portid,int report)165 int nf_conntrack_eventmask_report(unsigned int events, struct nf_conn *ct,
166 u32 portid, int report)
167 {
168 struct nf_conntrack_ecache *e;
169 struct nf_ct_event item;
170 unsigned int missed;
171 int ret;
172
173 if (!nf_ct_is_confirmed(ct))
174 return 0;
175
176 e = nf_ct_ecache_find(ct);
177 if (!e)
178 return 0;
179
180 memset(&item, 0, sizeof(item));
181
182 item.ct = ct;
183 item.portid = e->portid ? e->portid : portid;
184 item.report = report;
185
186 /* This is a resent of a destroy event? If so, skip missed */
187 missed = e->portid ? 0 : e->missed;
188
189 ret = __nf_conntrack_eventmask_report(e, events, missed, &item);
190 if (unlikely(ret < 0 && (events & (1 << IPCT_DESTROY)))) {
191 /* This is a destroy event that has been triggered by a process,
192 * we store the PORTID to include it in the retransmission.
193 */
194 if (e->portid == 0 && portid != 0)
195 e->portid = portid;
196 }
197
198 return ret;
199 }
200 EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report);
201
202 /* deliver cached events and clear cache entry - must be called with locally
203 * disabled softirqs */
nf_ct_deliver_cached_events(struct nf_conn * ct)204 void nf_ct_deliver_cached_events(struct nf_conn *ct)
205 {
206 struct nf_conntrack_ecache *e;
207 struct nf_ct_event item;
208 unsigned int events;
209
210 if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct))
211 return;
212
213 e = nf_ct_ecache_find(ct);
214 if (e == NULL)
215 return;
216
217 events = xchg(&e->cache, 0);
218
219 item.ct = ct;
220 item.portid = 0;
221 item.report = 0;
222
223 /* We make a copy of the missed event cache without taking
224 * the lock, thus we may send missed events twice. However,
225 * this does not harm and it happens very rarely.
226 */
227 __nf_conntrack_eventmask_report(e, events, e->missed, &item);
228 }
229 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
230
nf_ct_expect_event_report(enum ip_conntrack_expect_events event,struct nf_conntrack_expect * exp,u32 portid,int report)231 void nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
232 struct nf_conntrack_expect *exp,
233 u32 portid, int report)
234
235 {
236 struct net *net = nf_ct_exp_net(exp);
237 struct nf_ct_event_notifier *notify;
238 struct nf_conntrack_ecache *e;
239
240 rcu_read_lock();
241 notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
242 if (!notify)
243 goto out_unlock;
244
245 e = nf_ct_ecache_find(exp->master);
246 if (!e)
247 goto out_unlock;
248
249 if (e->expmask & (1 << event)) {
250 struct nf_exp_event item = {
251 .exp = exp,
252 .portid = portid,
253 .report = report
254 };
255 notify->exp_event(1 << event, &item);
256 }
257 out_unlock:
258 rcu_read_unlock();
259 }
260
nf_conntrack_register_notifier(struct net * net,const struct nf_ct_event_notifier * new)261 void nf_conntrack_register_notifier(struct net *net,
262 const struct nf_ct_event_notifier *new)
263 {
264 struct nf_ct_event_notifier *notify;
265
266 mutex_lock(&nf_ct_ecache_mutex);
267 notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
268 lockdep_is_held(&nf_ct_ecache_mutex));
269 WARN_ON_ONCE(notify);
270 rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
271 mutex_unlock(&nf_ct_ecache_mutex);
272 }
273 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
274
nf_conntrack_unregister_notifier(struct net * net)275 void nf_conntrack_unregister_notifier(struct net *net)
276 {
277 mutex_lock(&nf_ct_ecache_mutex);
278 RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
279 mutex_unlock(&nf_ct_ecache_mutex);
280 /* synchronize_rcu() is called after netns pre_exit */
281 }
282 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
283
nf_conntrack_ecache_work(struct net * net,enum nf_ct_ecache_state state)284 void nf_conntrack_ecache_work(struct net *net, enum nf_ct_ecache_state state)
285 {
286 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
287
288 if (state == NFCT_ECACHE_DESTROY_FAIL &&
289 !delayed_work_pending(&cnet->ecache.dwork)) {
290 schedule_delayed_work(&cnet->ecache.dwork, HZ);
291 net->ct.ecache_dwork_pending = true;
292 } else if (state == NFCT_ECACHE_DESTROY_SENT) {
293 if (!hlist_nulls_empty(&cnet->ecache.dying_list))
294 mod_delayed_work(system_wq, &cnet->ecache.dwork, 0);
295 else
296 net->ct.ecache_dwork_pending = false;
297 }
298 }
299
nf_ct_ecache_ext_add(struct nf_conn * ct,u16 ctmask,u16 expmask,gfp_t gfp)300 bool nf_ct_ecache_ext_add(struct nf_conn *ct, u16 ctmask, u16 expmask, gfp_t gfp)
301 {
302 struct net *net = nf_ct_net(ct);
303 struct nf_conntrack_ecache *e;
304
305 switch (net->ct.sysctl_events) {
306 case 0:
307 /* assignment via template / ruleset? ignore sysctl. */
308 if (ctmask || expmask)
309 break;
310 return true;
311 case 2: /* autodetect: no event listener, don't allocate extension. */
312 if (!READ_ONCE(nf_ctnetlink_has_listener))
313 return true;
314 fallthrough;
315 case 1:
316 /* always allocate an extension. */
317 if (!ctmask && !expmask) {
318 ctmask = ~0;
319 expmask = ~0;
320 }
321 break;
322 default:
323 WARN_ON_ONCE(1);
324 return true;
325 }
326
327 e = nf_ct_ext_add(ct, NF_CT_EXT_ECACHE, gfp);
328 if (e) {
329 e->ctmask = ctmask;
330 e->expmask = expmask;
331 }
332
333 return e != NULL;
334 }
335 EXPORT_SYMBOL_GPL(nf_ct_ecache_ext_add);
336
337 #define NF_CT_EVENTS_DEFAULT 2
338 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
339
nf_conntrack_ecache_pernet_init(struct net * net)340 void nf_conntrack_ecache_pernet_init(struct net *net)
341 {
342 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
343
344 net->ct.sysctl_events = nf_ct_events;
345
346 INIT_DELAYED_WORK(&cnet->ecache.dwork, ecache_work);
347 INIT_HLIST_NULLS_HEAD(&cnet->ecache.dying_list, DYING_NULLS_VAL);
348 spin_lock_init(&cnet->ecache.dying_lock);
349
350 BUILD_BUG_ON(__IPCT_MAX >= 16); /* e->ctmask is u16 */
351 }
352
nf_conntrack_ecache_pernet_fini(struct net * net)353 void nf_conntrack_ecache_pernet_fini(struct net *net)
354 {
355 struct nf_conntrack_net *cnet = nf_ct_pernet(net);
356
357 cancel_delayed_work_sync(&cnet->ecache.dwork);
358 }
359