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 } 261