net/netfilter/nf_conntrack_ecache.c

   1 /* Event cache for netfilter. */
   2
   3 /* (C) 1999-2001 Paul `Rusty' Russell
   4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
   5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/netfilter.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/stddef.h>
  17 #include <linux/err.h>
  18 #include <linux/percpu.h>
  19 #include <linux/kernel.h>
  20 #include <linux/netdevice.h>
  21
  22 #include <net/netfilter/nf_conntrack.h>
  23 #include <net/netfilter/nf_conntrack_core.h>
  24 #include <net/netfilter/nf_conntrack_extend.h>
  25
  26 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  27
  28 struct nf_ct_event_notifier *nf_conntrack_event_cb __read_mostly;
  29 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
  30
  31 struct nf_exp_event_notifier *nf_expect_event_cb __read_mostly;
  32 EXPORT_SYMBOL_GPL(nf_expect_event_cb);
  33
  34 /* deliver cached events and clear cache entry - must be called with locally
  35  * disabled softirqs */
  36 void nf_ct_deliver_cached_events(struct nf_conn *ct)
  37 {
  38         unsigned long events;
  39         struct nf_ct_event_notifier *notify;
  40         struct nf_conntrack_ecache *e;
  41
  42         rcu_read_lock();
  43         notify = rcu_dereference(nf_conntrack_event_cb);
  44         if (notify == NULL)
  45                 goto out_unlock;
  46
  47         e = nf_ct_ecache_find(ct);
  48         if (e == NULL)
  49                 goto out_unlock;
  50
  51         events = xchg(&e->cache, 0);
  52
  53         if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct) && events) {
  54                 struct nf_ct_event item = {
  55                         .ct     = ct,
  56                         .pid    = 0,
  57                         .report = 0
  58                 };
  59                 int ret;
  60                 /* We make a copy of the missed event cache without taking
  61                  * the lock, thus we may send missed events twice. However,
  62                  * this does not harm and it happens very rarely. */
  63                 unsigned long missed = e->missed;
  64
  65                 ret = notify->fcn(events | missed, &item);
  66                 if (unlikely(ret < 0 || missed)) {
  67                         spin_lock_bh(&ct->lock);
  68                         if (ret < 0)
  69                                 e->missed |= events;
  70                         else
  71                                 e->missed &= ~missed;
  72                         spin_unlock_bh(&ct->lock);
  73                 }
  74         }
  75
  76 out_unlock:
  77         rcu_read_unlock();
  78 }
  79 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  80
  81 int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
  82 {
  83         int ret = 0;
  84         struct nf_ct_event_notifier *notify;
  85
  86         mutex_lock(&nf_ct_ecache_mutex);
  87         notify = rcu_dereference(nf_conntrack_event_cb);
  88         if (notify != NULL) {
  89                 ret = -EBUSY;
  90                 goto out_unlock;
  91         }
  92         rcu_assign_pointer(nf_conntrack_event_cb, new);
  93         mutex_unlock(&nf_ct_ecache_mutex);
  94         return ret;
  95
  96 out_unlock:
  97         mutex_unlock(&nf_ct_ecache_mutex);
  98         return ret;
  99 }
 100 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 101
 102 void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
 103 {
 104         struct nf_ct_event_notifier *notify;
 105
 106         mutex_lock(&nf_ct_ecache_mutex);
 107         notify = rcu_dereference(nf_conntrack_event_cb);
 108         BUG_ON(notify != new);
 109         rcu_assign_pointer(nf_conntrack_event_cb, NULL);
 110         mutex_unlock(&nf_ct_ecache_mutex);
 111 }
 112 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 113
 114 int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
 115 {
 116         int ret = 0;
 117         struct nf_exp_event_notifier *notify;
 118
 119         mutex_lock(&nf_ct_ecache_mutex);
 120         notify = rcu_dereference(nf_expect_event_cb);
 121         if (notify != NULL) {
 122                 ret = -EBUSY;
 123                 goto out_unlock;
 124         }
 125         rcu_assign_pointer(nf_expect_event_cb, new);
 126         mutex_unlock(&nf_ct_ecache_mutex);
 127         return ret;
 128
 129 out_unlock:
 130         mutex_unlock(&nf_ct_ecache_mutex);
 131         return ret;
 132 }
 133 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 134
 135 void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
 136 {
 137         struct nf_exp_event_notifier *notify;
 138
 139         mutex_lock(&nf_ct_ecache_mutex);
 140         notify = rcu_dereference(nf_expect_event_cb);
 141         BUG_ON(notify != new);
 142         rcu_assign_pointer(nf_expect_event_cb, NULL);
 143         mutex_unlock(&nf_ct_ecache_mutex);
 144 }
 145 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 146
 147 #define NF_CT_EVENTS_DEFAULT 1
 148 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 149 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 150
 151 #ifdef CONFIG_SYSCTL
 152 static struct ctl_table event_sysctl_table[] = {
 153         {
 154                 .ctl_name       = CTL_UNNUMBERED,
 155                 .procname       = "nf_conntrack_events",
 156                 .data           = &init_net.ct.sysctl_events,
 157                 .maxlen         = sizeof(unsigned int),
 158                 .mode           = 0644,
 159                 .proc_handler   = proc_dointvec,
 160         },
 161         {
 162                 .ctl_name       = CTL_UNNUMBERED,
 163                 .procname       = "nf_conntrack_events_retry_timeout",
 164                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 165                 .maxlen         = sizeof(unsigned int),
 166                 .mode           = 0644,
 167                 .proc_handler   = proc_dointvec_jiffies,
 168         },
 169         {}
 170 };
 171 #endif /* CONFIG_SYSCTL */
 172
 173 static struct nf_ct_ext_type event_extend __read_mostly = {
 174         .len    = sizeof(struct nf_conntrack_ecache),
 175         .align  = __alignof__(struct nf_conntrack_ecache),
 176         .id     = NF_CT_EXT_ECACHE,
 177 };
 178
 179 #ifdef CONFIG_SYSCTL
 180 static int nf_conntrack_event_init_sysctl(struct net *net)
 181 {
 182         struct ctl_table *table;
 183
 184         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 185                         GFP_KERNEL);
 186         if (!table)
 187                 goto out;
 188
 189         table[0].data = &net->ct.sysctl_events;
 190         table[1].data = &net->ct.sysctl_events_retry_timeout;
 191
 192         net->ct.event_sysctl_header =
 193                 register_net_sysctl_table(net,
 194                                           nf_net_netfilter_sysctl_path, table);
 195         if (!net->ct.event_sysctl_header) {
 196                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 197                 goto out_register;
 198         }
 199         return 0;
 200
 201 out_register:
 202         kfree(table);
 203 out:
 204         return -ENOMEM;
 205 }
 206
 207 static void nf_conntrack_event_fini_sysctl(struct net *net)
 208 {
 209         struct ctl_table *table;
 210
 211         table = net->ct.event_sysctl_header->ctl_table_arg;
 212         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 213         kfree(table);
 214 }
 215 #else
 216 static int nf_conntrack_event_init_sysctl(struct net *net)
 217 {
 218         return 0;
 219 }
 220
 221 static void nf_conntrack_event_fini_sysctl(struct net *net)
 222 {
 223 }
 224 #endif /* CONFIG_SYSCTL */
 225
 226 int nf_conntrack_ecache_init(struct net *net)
 227 {
 228         int ret;
 229
 230         net->ct.sysctl_events = nf_ct_events;
 231         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 232
 233         if (net_eq(net, &init_net)) {
 234                 ret = nf_ct_extend_register(&event_extend);
 235                 if (ret < 0) {
 236                         printk(KERN_ERR "nf_ct_event: Unable to register "
 237                                         "event extension.\n");
 238                         goto out_extend_register;
 239                 }
 240         }
 241
 242         ret = nf_conntrack_event_init_sysctl(net);
 243         if (ret < 0)
 244                 goto out_sysctl;
 245
 246         return 0;
 247
 248 out_sysctl:
 249         if (net_eq(net, &init_net))
 250                 nf_ct_extend_unregister(&event_extend);
 251 out_extend_register:
 252         return ret;
 253 }
 254
 255 void nf_conntrack_ecache_fini(struct net *net)
 256 {
 257         nf_conntrack_event_fini_sysctl(net);
 258         if (net_eq(net, &init_net))
 259                 nf_ct_extend_unregister(&event_extend);
 260 }