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 #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_extend.h>
  27
  28 static DEFINE_MUTEX(nf_ct_ecache_mutex);
  29
  30 /* deliver cached events and clear cache entry - must be called with locally
  31  * disabled softirqs */
  32 void nf_ct_deliver_cached_events(struct nf_conn *ct)
  33 {
  34         struct net *net = nf_ct_net(ct);
  35         unsigned long events, missed;
  36         struct nf_ct_event_notifier *notify;
  37         struct nf_conntrack_ecache *e;
  38         struct nf_ct_event item;
  39         int ret;
  40
  41         rcu_read_lock();
  42         notify = rcu_dereference(net->ct.nf_conntrack_event_cb);
  43         if (notify == NULL)
  44                 goto out_unlock;
  45
  46         e = nf_ct_ecache_find(ct);
  47         if (e == NULL)
  48                 goto out_unlock;
  49
  50         events = xchg(&e->cache, 0);
  51
  52         if (!nf_ct_is_confirmed(ct) || nf_ct_is_dying(ct) || !events)
  53                 goto out_unlock;
  54
  55         /* We make a copy of the missed event cache without taking
  56          * the lock, thus we may send missed events twice. However,
  57          * this does not harm and it happens very rarely. */
  58         missed = e->missed;
  59
  60         if (!((events | missed) & e->ctmask))
  61                 goto out_unlock;
  62
  63         item.ct = ct;
  64         item.pid = 0;
  65         item.report = 0;
  66
  67         ret = notify->fcn(events | missed, &item);
  68
  69         if (likely(ret >= 0 && !missed))
  70                 goto out_unlock;
  71
  72         spin_lock_bh(&ct->lock);
  73         if (ret < 0)
  74                 e->missed |= events;
  75         else
  76                 e->missed &= ~missed;
  77         spin_unlock_bh(&ct->lock);
  78
  79 out_unlock:
  80         rcu_read_unlock();
  81 }
  82 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events);
  83
  84 int nf_conntrack_register_notifier(struct net *net,
  85                                    struct nf_ct_event_notifier *new)
  86 {
  87         int ret = 0;
  88         struct nf_ct_event_notifier *notify;
  89
  90         mutex_lock(&nf_ct_ecache_mutex);
  91         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
  92                                            lockdep_is_held(&nf_ct_ecache_mutex));
  93         if (notify != NULL) {
  94                 ret = -EBUSY;
  95                 goto out_unlock;
  96         }
  97         rcu_assign_pointer(net->ct.nf_conntrack_event_cb, new);
  98         mutex_unlock(&nf_ct_ecache_mutex);
  99         return ret;
 100
 101 out_unlock:
 102         mutex_unlock(&nf_ct_ecache_mutex);
 103         return ret;
 104 }
 105 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 106
 107 void nf_conntrack_unregister_notifier(struct net *net,
 108                                       struct nf_ct_event_notifier *new)
 109 {
 110         struct nf_ct_event_notifier *notify;
 111
 112         mutex_lock(&nf_ct_ecache_mutex);
 113         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 114                                            lockdep_is_held(&nf_ct_ecache_mutex));
 115         BUG_ON(notify != new);
 116         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 117         mutex_unlock(&nf_ct_ecache_mutex);
 118 }
 119 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 120
 121 int nf_ct_expect_register_notifier(struct net *net,
 122                                    struct nf_exp_event_notifier *new)
 123 {
 124         int ret = 0;
 125         struct nf_exp_event_notifier *notify;
 126
 127         mutex_lock(&nf_ct_ecache_mutex);
 128         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 129                                            lockdep_is_held(&nf_ct_ecache_mutex));
 130         if (notify != NULL) {
 131                 ret = -EBUSY;
 132                 goto out_unlock;
 133         }
 134         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
 135         mutex_unlock(&nf_ct_ecache_mutex);
 136         return ret;
 137
 138 out_unlock:
 139         mutex_unlock(&nf_ct_ecache_mutex);
 140         return ret;
 141 }
 142 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 143
 144 void nf_ct_expect_unregister_notifier(struct net *net,
 145                                       struct nf_exp_event_notifier *new)
 146 {
 147         struct nf_exp_event_notifier *notify;
 148
 149         mutex_lock(&nf_ct_ecache_mutex);
 150         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 151                                            lockdep_is_held(&nf_ct_ecache_mutex));
 152         BUG_ON(notify != new);
 153         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
 154         mutex_unlock(&nf_ct_ecache_mutex);
 155 }
 156 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 157
 158 #define NF_CT_EVENTS_DEFAULT 1
 159 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 160 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 161
 162 #ifdef CONFIG_SYSCTL
 163 static struct ctl_table event_sysctl_table[] = {
 164         {
 165                 .procname       = "nf_conntrack_events",
 166                 .data           = &init_net.ct.sysctl_events,
 167                 .maxlen         = sizeof(unsigned int),
 168                 .mode           = 0644,
 169                 .proc_handler   = proc_dointvec,
 170         },
 171         {
 172                 .procname       = "nf_conntrack_events_retry_timeout",
 173                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 174                 .maxlen         = sizeof(unsigned int),
 175                 .mode           = 0644,
 176                 .proc_handler   = proc_dointvec_jiffies,
 177         },
 178         {}
 179 };
 180 #endif /* CONFIG_SYSCTL */
 181
 182 static struct nf_ct_ext_type event_extend __read_mostly = {
 183         .len    = sizeof(struct nf_conntrack_ecache),
 184         .align  = __alignof__(struct nf_conntrack_ecache),
 185         .id     = NF_CT_EXT_ECACHE,
 186 };
 187
 188 #ifdef CONFIG_SYSCTL
 189 static int nf_conntrack_event_init_sysctl(struct net *net)
 190 {
 191         struct ctl_table *table;
 192
 193         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 194                         GFP_KERNEL);
 195         if (!table)
 196                 goto out;
 197
 198         table[0].data = &net->ct.sysctl_events;
 199         table[1].data = &net->ct.sysctl_events_retry_timeout;
 200
 201         net->ct.event_sysctl_header =
 202                 register_net_sysctl_table(net,
 203                                           nf_net_netfilter_sysctl_path, table);
 204         if (!net->ct.event_sysctl_header) {
 205                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 206                 goto out_register;
 207         }
 208         return 0;
 209
 210 out_register:
 211         kfree(table);
 212 out:
 213         return -ENOMEM;
 214 }
 215
 216 static void nf_conntrack_event_fini_sysctl(struct net *net)
 217 {
 218         struct ctl_table *table;
 219
 220         table = net->ct.event_sysctl_header->ctl_table_arg;
 221         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 222         kfree(table);
 223 }
 224 #else
 225 static int nf_conntrack_event_init_sysctl(struct net *net)
 226 {
 227         return 0;
 228 }
 229
 230 static void nf_conntrack_event_fini_sysctl(struct net *net)
 231 {
 232 }
 233 #endif /* CONFIG_SYSCTL */
 234
 235 int nf_conntrack_ecache_init(struct net *net)
 236 {
 237         int ret;
 238
 239         net->ct.sysctl_events = nf_ct_events;
 240         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 241
 242         if (net_eq(net, &init_net)) {
 243                 ret = nf_ct_extend_register(&event_extend);
 244                 if (ret < 0) {
 245                         printk(KERN_ERR "nf_ct_event: Unable to register "
 246                                         "event extension.\n");
 247                         goto out_extend_register;
 248                 }
 249         }
 250
 251         ret = nf_conntrack_event_init_sysctl(net);
 252         if (ret < 0)
 253                 goto out_sysctl;
 254
 255         return 0;
 256
 257 out_sysctl:
 258         if (net_eq(net, &init_net))
 259                 nf_ct_extend_unregister(&event_extend);
 260 out_extend_register:
 261         return ret;
 262 }
 263
 264 void nf_conntrack_ecache_fini(struct net *net)
 265 {
 266         nf_conntrack_event_fini_sysctl(net);
 267         if (net_eq(net, &init_net))
 268                 nf_ct_extend_unregister(&event_extend);
 269 }