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 int nf_conntrack_eventmask_report(unsigned int eventmask, struct nf_conn *ct, 117 u32 portid, int report) 118 { 119 int ret = 0; 120 struct net *net = nf_ct_net(ct); 121 struct nf_ct_event_notifier *notify; 122 struct nf_conntrack_ecache *e; 123 124 rcu_read_lock(); 125 notify = rcu_dereference(net->ct.nf_conntrack_event_cb); 126 if (!notify) 127 goto out_unlock; 128 129 e = nf_ct_ecache_find(ct); 130 if (!e) 131 goto out_unlock; 132 133 if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) { 134 struct nf_ct_event item = { 135 .ct = ct, 136 .portid = e->portid ? e->portid : portid, 137 .report = report 138 }; 139 /* This is a resent of a destroy event? If so, skip missed */ 140 unsigned long missed = e->portid ? 0 : e->missed; 141 142 if (!((eventmask | missed) & e->ctmask)) 143 goto out_unlock; 144 145 ret = notify->fcn(eventmask | missed, &item); 146 if (unlikely(ret < 0 || missed)) { 147 spin_lock_bh(&ct->lock); 148 if (ret < 0) { 149 /* This is a destroy event that has been 150 * triggered by a process, we store the PORTID 151 * to include it in the retransmission. 152 */ 153 if (eventmask & (1 << IPCT_DESTROY) && 154 e->portid == 0 && portid != 0) 155 e->portid = portid; 156 else 157 e->missed |= eventmask; 158 } else { 159 e->missed &= ~missed; 160 } 161 spin_unlock_bh(&ct->lock); 162 } 163 } 164 out_unlock: 165 rcu_read_unlock(); 166 return ret; 167 } 168 EXPORT_SYMBOL_GPL(nf_conntrack_eventmask_report); 169 170 /* deliver cached events and clear cache entry - must be called with locally 171 * disabled softirqs */ 172 void nf_ct_deliver_cached_events(struct nf_conn *ct) 173 { 174 struct net *net = nf_ct_net(ct); 175 unsigned long events, missed; 176 struct nf_ct_event_notifier *notify; 177 struct nf_conntrack_ecache *e; 178 struct nf_ct_event item; 179 int ret; 180 181 rcu_read_lock(); 182 notify = rcu_dereference(net->ct.nf_conntrack_event_cb); 183 if (notify == NULL) 184 goto out_unlock; 185 186 e = nf_ct_ecache_find(ct); 187 if (e == NULL) 188 goto out_unlock; 189 190 events = xchg(&e->cache, 0); 191 192 if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events) 193 goto out_unlock; 194 195 /* We make a copy of the missed event cache without taking 196 * the lock, thus we may send missed events twice. However, 197 * this does not harm and it happens very rarely. */ 198 missed = e->missed; 199 200 if (!((events | missed) & e->ctmask)) 201 goto out_unlock; 202 203 item.ct = ct; 204 item.portid = 0; 205 item.report = 0; 206 207 ret = notify->fcn(events | missed, &item); 208 209 if (likely(ret >= 0 && !missed)) 210 goto out_unlock; 211 212 spin_lock_bh(&ct->lock); 213 if (ret < 0) 214 e->missed |= events; 215 else 216 e->missed &= ~missed; 217 spin_unlock_bh(&ct->lock); 218 219 out_unlock: 220 rcu_read_unlock(); 221 } 222 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events); 223 224 int nf_conntrack_register_notifier(struct net *net, 225 struct nf_ct_event_notifier *new) 226 { 227 int ret; 228 struct nf_ct_event_notifier *notify; 229 230 mutex_lock(&nf_ct_ecache_mutex); 231 notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb, 232 lockdep_is_held(&nf_ct_ecache_mutex)); 233 if (notify != NULL) { 234 ret = -EBUSY; 235 goto out_unlock; 236 } 237 rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new); 238 ret = 0; 239 240 out_unlock: 241 mutex_unlock(&nf_ct_ecache_mutex); 242 return ret; 243 } 244 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier); 245 246 void nf_conntrack_unregister_notifier(struct net *net, 247 struct nf_ct_event_notifier *new) 248 { 249 struct nf_ct_event_notifier *notify; 250 251 mutex_lock(&nf_ct_ecache_mutex); 252 notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb, 253 lockdep_is_held(&nf_ct_ecache_mutex)); 254 BUG_ON(notify != new); 255 RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL); 256 mutex_unlock(&nf_ct_ecache_mutex); 257 } 258 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier); 259 260 int nf_ct_expect_register_notifier(struct net *net, 261 struct nf_exp_event_notifier *new) 262 { 263 int ret; 264 struct nf_exp_event_notifier *notify; 265 266 mutex_lock(&nf_ct_ecache_mutex); 267 notify = rcu_dereference_protected(net->ct.nf_expect_event_cb, 268 lockdep_is_held(&nf_ct_ecache_mutex)); 269 if (notify != NULL) { 270 ret = -EBUSY; 271 goto out_unlock; 272 } 273 rcu_assign_pointer(net->ct.nf_expect_event_cb, new); 274 ret = 0; 275 276 out_unlock: 277 mutex_unlock(&nf_ct_ecache_mutex); 278 return ret; 279 } 280 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier); 281 282 void nf_ct_expect_unregister_notifier(struct net *net, 283 struct nf_exp_event_notifier *new) 284 { 285 struct nf_exp_event_notifier *notify; 286 287 mutex_lock(&nf_ct_ecache_mutex); 288 notify = rcu_dereference_protected(net->ct.nf_expect_event_cb, 289 lockdep_is_held(&nf_ct_ecache_mutex)); 290 BUG_ON(notify != new); 291 RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL); 292 mutex_unlock(&nf_ct_ecache_mutex); 293 } 294 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier); 295 296 #define NF_CT_EVENTS_DEFAULT 1 297 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT; 298 299 #ifdef CONFIG_SYSCTL 300 static struct ctl_table event_sysctl_table[] = { 301 { 302 .procname = "nf_conntrack_events", 303 .data = &init_net.ct.sysctl_events, 304 .maxlen = sizeof(unsigned int), 305 .mode = 0644, 306 .proc_handler = proc_dointvec, 307 }, 308 {} 309 }; 310 #endif /* CONFIG_SYSCTL */ 311 312 static struct nf_ct_ext_type event_extend __read_mostly = { 313 .len = sizeof(struct nf_conntrack_ecache), 314 .align = __alignof__(struct nf_conntrack_ecache), 315 .id = NF_CT_EXT_ECACHE, 316 }; 317 318 #ifdef CONFIG_SYSCTL 319 static int nf_conntrack_event_init_sysctl(struct net *net) 320 { 321 struct ctl_table *table; 322 323 table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table), 324 GFP_KERNEL); 325 if (!table) 326 goto out; 327 328 table[0].data = &net->ct.sysctl_events; 329 330 /* Don't export sysctls to unprivileged users */ 331 if (net->user_ns != &init_user_ns) 332 table[0].procname = NULL; 333 334 net->ct.event_sysctl_header = 335 register_net_sysctl(net, "net/netfilter", table); 336 if (!net->ct.event_sysctl_header) { 337 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n"); 338 goto out_register; 339 } 340 return 0; 341 342 out_register: 343 kfree(table); 344 out: 345 return -ENOMEM; 346 } 347 348 static void nf_conntrack_event_fini_sysctl(struct net *net) 349 { 350 struct ctl_table *table; 351 352 table = net->ct.event_sysctl_header->ctl_table_arg; 353 unregister_net_sysctl_table(net->ct.event_sysctl_header); 354 kfree(table); 355 } 356 #else 357 static int nf_conntrack_event_init_sysctl(struct net *net) 358 { 359 return 0; 360 } 361 362 static void nf_conntrack_event_fini_sysctl(struct net *net) 363 { 364 } 365 #endif /* CONFIG_SYSCTL */ 366 367 int nf_conntrack_ecache_pernet_init(struct net *net) 368 { 369 net->ct.sysctl_events = nf_ct_events; 370 INIT_DELAYED_WORK(&net->ct.ecache_dwork, ecache_work); 371 return nf_conntrack_event_init_sysctl(net); 372 } 373 374 void nf_conntrack_ecache_pernet_fini(struct net *net) 375 { 376 cancel_delayed_work_sync(&net->ct.ecache_dwork); 377 nf_conntrack_event_fini_sysctl(net); 378 } 379 380 int nf_conntrack_ecache_init(void) 381 { 382 int ret = nf_ct_extend_register(&event_extend); 383 if (ret < 0) 384 pr_err("nf_ct_event: Unable to register event extension.\n"); 385 return ret; 386 } 387 388 void nf_conntrack_ecache_fini(void) 389 { 390 nf_ct_extend_unregister(&event_extend); 391 } 392