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 23 #include <net/netfilter/nf_conntrack.h> 24 #include <net/netfilter/nf_conntrack_core.h> 25 #include <net/netfilter/nf_conntrack_extend.h> 26 27 static DEFINE_MUTEX(nf_ct_ecache_mutex); 28 29 struct nf_ct_event_notifier __rcu *nf_conntrack_event_cb __read_mostly; 30 EXPORT_SYMBOL_GPL(nf_conntrack_event_cb); 31 32 struct nf_exp_event_notifier __rcu *nf_expect_event_cb __read_mostly; 33 EXPORT_SYMBOL_GPL(nf_expect_event_cb); 34 35 /* deliver cached events and clear cache entry - must be called with locally 36 * disabled softirqs */ 37 void nf_ct_deliver_cached_events(struct nf_conn *ct) 38 { 39 unsigned long events; 40 struct nf_ct_event_notifier *notify; 41 struct nf_conntrack_ecache *e; 42 43 rcu_read_lock(); 44 notify = rcu_dereference(nf_conntrack_event_cb); 45 if (notify == NULL) 46 goto out_unlock; 47 48 e = nf_ct_ecache_find(ct); 49 if (e == NULL) 50 goto out_unlock; 51 52 events = xchg(&e->cache, 0); 53 54 if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct) && events) { 55 struct nf_ct_event item = { 56 .ct = ct, 57 .pid = 0, 58 .report = 0 59 }; 60 int ret; 61 /* We make a copy of the missed event cache without taking 62 * the lock, thus we may send missed events twice. However, 63 * this does not harm and it happens very rarely. */ 64 unsigned long missed = e->missed; 65 66 if (!((events | missed) & e->ctmask)) 67 goto out_unlock; 68 69 ret = notify->fcn(events | missed, &item); 70 if (unlikely(ret < 0 || missed)) { 71 spin_lock_bh(&ct->lock); 72 if (ret < 0) 73 e->missed |= events; 74 else 75 e->missed &= ~missed; 76 spin_unlock_bh(&ct->lock); 77 } 78 } 79 80 out_unlock: 81 rcu_read_unlock(); 82 } 83 EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events); 84 85 int nf_conntrack_register_notifier(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(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(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 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(nf_conntrack_event_cb, 113 lockdep_is_held(&nf_ct_ecache_mutex)); 114 BUG_ON(notify != new); 115 rcu_assign_pointer(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 nf_exp_event_notifier *new) 121 { 122 int ret = 0; 123 struct nf_exp_event_notifier *notify; 124 125 mutex_lock(&nf_ct_ecache_mutex); 126 notify = rcu_dereference_protected(nf_expect_event_cb, 127 lockdep_is_held(&nf_ct_ecache_mutex)); 128 if (notify != NULL) { 129 ret = -EBUSY; 130 goto out_unlock; 131 } 132 rcu_assign_pointer(nf_expect_event_cb, new); 133 mutex_unlock(&nf_ct_ecache_mutex); 134 return ret; 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 nf_exp_event_notifier *new) 143 { 144 struct nf_exp_event_notifier *notify; 145 146 mutex_lock(&nf_ct_ecache_mutex); 147 notify = rcu_dereference_protected(nf_expect_event_cb, 148 lockdep_is_held(&nf_ct_ecache_mutex)); 149 BUG_ON(notify != new); 150 rcu_assign_pointer(nf_expect_event_cb, NULL); 151 mutex_unlock(&nf_ct_ecache_mutex); 152 } 153 EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier); 154 155 #define NF_CT_EVENTS_DEFAULT 1 156 static int nf_ct_events __read_mostly = NF_CT_EVENTS_DEFAULT; 157 static int nf_ct_events_retry_timeout __read_mostly = 15*HZ; 158 159 #ifdef CONFIG_SYSCTL 160 static struct ctl_table event_sysctl_table[] = { 161 { 162 .procname = "nf_conntrack_events", 163 .data = &init_net.ct.sysctl_events, 164 .maxlen = sizeof(unsigned int), 165 .mode = 0644, 166 .proc_handler = proc_dointvec, 167 }, 168 { 169 .procname = "nf_conntrack_events_retry_timeout", 170 .data = &init_net.ct.sysctl_events_retry_timeout, 171 .maxlen = sizeof(unsigned int), 172 .mode = 0644, 173 .proc_handler = proc_dointvec_jiffies, 174 }, 175 {} 176 }; 177 #endif /* CONFIG_SYSCTL */ 178 179 static struct nf_ct_ext_type event_extend __read_mostly = { 180 .len = sizeof(struct nf_conntrack_ecache), 181 .align = __alignof__(struct nf_conntrack_ecache), 182 .id = NF_CT_EXT_ECACHE, 183 }; 184 185 #ifdef CONFIG_SYSCTL 186 static int nf_conntrack_event_init_sysctl(struct net *net) 187 { 188 struct ctl_table *table; 189 190 table = kmemdup(event_sysctl_table, sizeof(event_sysctl_table), 191 GFP_KERNEL); 192 if (!table) 193 goto out; 194 195 table[0].data = &net->ct.sysctl_events; 196 table[1].data = &net->ct.sysctl_events_retry_timeout; 197 198 net->ct.event_sysctl_header = 199 register_net_sysctl_table(net, 200 nf_net_netfilter_sysctl_path, 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 } 267