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.portid = 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;
  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         ret = 0;
  99
 100 out_unlock:
 101         mutex_unlock(&nf_ct_ecache_mutex);
 102         return ret;
 103 }
 104 EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
 105
 106 void nf_conntrack_unregister_notifier(struct net *net,
 107                                       struct nf_ct_event_notifier *new)
 108 {
 109         struct nf_ct_event_notifier *notify;
 110
 111         mutex_lock(&nf_ct_ecache_mutex);
 112         notify = rcu_dereference_protected(net->ct.nf_conntrack_event_cb,
 113                                            lockdep_is_held(&nf_ct_ecache_mutex));
 114         BUG_ON(notify != new);
 115         RCU_INIT_POINTER(net->ct.nf_conntrack_event_cb, NULL);
 116         mutex_unlock(&nf_ct_ecache_mutex);
 117 }
 118 EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
 119
 120 int nf_ct_expect_register_notifier(struct net *net,
 121                                    struct nf_exp_event_notifier *new)
 122 {
 123         int ret;
 124         struct nf_exp_event_notifier *notify;
 125
 126         mutex_lock(&nf_ct_ecache_mutex);
 127         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 128                                            lockdep_is_held(&nf_ct_ecache_mutex));
 129         if (notify != NULL) {
 130                 ret = -EBUSY;
 131                 goto out_unlock;
 132         }
 133         rcu_assign_pointer(net->ct.nf_expect_event_cb, new);
 134         ret = 0;
 135
 136 out_unlock:
 137         mutex_unlock(&nf_ct_ecache_mutex);
 138         return ret;
 139 }
 140 EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
 141
 142 void nf_ct_expect_unregister_notifier(struct net *net,
 143                                       struct nf_exp_event_notifier *new)
 144 {
 145         struct nf_exp_event_notifier *notify;
 146
 147         mutex_lock(&nf_ct_ecache_mutex);
 148         notify = rcu_dereference_protected(net->ct.nf_expect_event_cb,
 149                                            lockdep_is_held(&nf_ct_ecache_mutex));
 150         BUG_ON(notify != new);
 151         RCU_INIT_POINTER(net->ct.nf_expect_event_cb, NULL);
 152         mutex_unlock(&nf_ct_ecache_mutex);
 153 }
 154 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
 155
 156 #define NF_CT_EVENTS_DEFAULT 1
 157 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT;
 158 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ;
 159
 160 #ifdef CONFIG_SYSCTL
 161 static struct ctl_table event_sysctl_table[] = {
 162         {
 163                 .procname       = "nf_conntrack_events",
 164                 .data           = &init_net.ct.sysctl_events,
 165                 .maxlen         = sizeof(unsigned int),
 166                 .mode           = 0644,
 167                 .proc_handler   = proc_dointvec,
 168         },
 169         {
 170                 .procname       = "nf_conntrack_events_retry_timeout",
 171                 .data           = &init_net.ct.sysctl_events_retry_timeout,
 172                 .maxlen         = sizeof(unsigned int),
 173                 .mode           = 0644,
 174                 .proc_handler   = proc_dointvec_jiffies,
 175         },
 176         {}
 177 };
 178 #endif /* CONFIG_SYSCTL */
 179
 180 static struct nf_ct_ext_type event_extend __read_mostly = {
 181         .len    = sizeof(struct nf_conntrack_ecache),
 182         .align  = __alignof__(struct nf_conntrack_ecache),
 183         .id     = NF_CT_EXT_ECACHE,
 184 };
 185
 186 #ifdef CONFIG_SYSCTL
 187 static int nf_conntrack_event_init_sysctl(struct net *net)
 188 {
 189         struct ctl_table *table;
 190
 191         table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table),
 192                         GFP_KERNEL);
 193         if (!table)
 194                 goto out;
 195
 196         table[0].data = &net->ct.sysctl_events;
 197         table[1].data = &net->ct.sysctl_events_retry_timeout;
 198
 199         net->ct.event_sysctl_header =
 200                 register_net_sysctl(net, "net/netfilter", table);
 201         if (!net->ct.event_sysctl_header) {
 202                 printk(KERN_ERR "nf_ct_event: can't register to sysctl.\n");
 203                 goto out_register;
 204         }
 205         return 0;
 206
 207 out_register:
 208         kfree(table);
 209 out:
 210         return -ENOMEM;
 211 }
 212
 213 static void nf_conntrack_event_fini_sysctl(struct net *net)
 214 {
 215         struct ctl_table *table;
 216
 217         table = net->ct.event_sysctl_header->ctl_table_arg;
 218         unregister_net_sysctl_table(net->ct.event_sysctl_header);
 219         kfree(table);
 220 }
 221 #else
 222 static int nf_conntrack_event_init_sysctl(struct net *net)
 223 {
 224         return 0;
 225 }
 226
 227 static void nf_conntrack_event_fini_sysctl(struct net *net)
 228 {
 229 }
 230 #endif /* CONFIG_SYSCTL */
 231
 232 int nf_conntrack_ecache_init(struct net *net)
 233 {
 234         int ret;
 235
 236         net->ct.sysctl_events = nf_ct_events;
 237         net->ct.sysctl_events_retry_timeout = nf_ct_events_retry_timeout;
 238
 239         if (net_eq(net, &init_net)) {
 240                 ret = nf_ct_extend_register(&event_extend);
 241                 if (ret < 0) {
 242                         printk(KERN_ERR "nf_ct_event: Unable to register "
 243                                         "event extension.\n");
 244                         goto out_extend_register;
 245                 }
 246         }
 247
 248         ret = nf_conntrack_event_init_sysctl(net);
 249         if (ret < 0)
 250                 goto out_sysctl;
 251
 252         return 0;
 253
 254 out_sysctl:
 255         if (net_eq(net, &init_net))
 256                 nf_ct_extend_unregister(&event_extend);
 257 out_extend_register:
 258         return ret;
 259 }
 260
 261 void nf_conntrack_ecache_fini(struct net *net)
 262 {
 263         nf_conntrack_event_fini_sysctl(net);
 264         if (net_eq(net, &init_net))
 265                 nf_ct_extend_unregister(&event_extend);
 266 }