1 #include <linux/rtnetlink.h> 2 #include <linux/notifier.h> 3 #include <linux/rcupdate.h> 4 #include <linux/kernel.h> 5 #include <linux/module.h> 6 #include <linux/init.h> 7 #include <net/net_namespace.h> 8 #include <net/fib_notifier.h> 9 10 static ATOMIC_NOTIFIER_HEAD(fib_chain); 11 12 int call_fib_notifier(struct notifier_block *nb, struct net *net, 13 enum fib_event_type event_type, 14 struct fib_notifier_info *info) 15 { 16 info->net = net; 17 return nb->notifier_call(nb, event_type, info); 18 } 19 EXPORT_SYMBOL(call_fib_notifier); 20 21 int call_fib_notifiers(struct net *net, enum fib_event_type event_type, 22 struct fib_notifier_info *info) 23 { 24 info->net = net; 25 return atomic_notifier_call_chain(&fib_chain, event_type, info); 26 } 27 EXPORT_SYMBOL(call_fib_notifiers); 28 29 static unsigned int fib_seq_sum(void) 30 { 31 struct fib_notifier_ops *ops; 32 unsigned int fib_seq = 0; 33 struct net *net; 34 35 rtnl_lock(); 36 for_each_net(net) { 37 list_for_each_entry(ops, &net->fib_notifier_ops, list) { 38 if (!try_module_get(ops->owner)) 39 continue; 40 fib_seq += ops->fib_seq_read(net); 41 module_put(ops->owner); 42 } 43 } 44 rtnl_unlock(); 45 46 return fib_seq; 47 } 48 49 static int fib_net_dump(struct net *net, struct notifier_block *nb) 50 { 51 struct fib_notifier_ops *ops; 52 53 list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) { 54 int err; 55 56 if (!try_module_get(ops->owner)) 57 continue; 58 err = ops->fib_dump(net, nb); 59 module_put(ops->owner); 60 if (err) 61 return err; 62 } 63 64 return 0; 65 } 66 67 static bool fib_dump_is_consistent(struct notifier_block *nb, 68 void (*cb)(struct notifier_block *nb), 69 unsigned int fib_seq) 70 { 71 atomic_notifier_chain_register(&fib_chain, nb); 72 if (fib_seq == fib_seq_sum()) 73 return true; 74 atomic_notifier_chain_unregister(&fib_chain, nb); 75 if (cb) 76 cb(nb); 77 return false; 78 } 79 80 #define FIB_DUMP_MAX_RETRIES 5 81 int register_fib_notifier(struct notifier_block *nb, 82 void (*cb)(struct notifier_block *nb)) 83 { 84 int retries = 0; 85 int err; 86 87 do { 88 unsigned int fib_seq = fib_seq_sum(); 89 struct net *net; 90 91 rcu_read_lock(); 92 for_each_net_rcu(net) { 93 err = fib_net_dump(net, nb); 94 if (err) 95 goto err_fib_net_dump; 96 } 97 rcu_read_unlock(); 98 99 if (fib_dump_is_consistent(nb, cb, fib_seq)) 100 return 0; 101 } while (++retries < FIB_DUMP_MAX_RETRIES); 102 103 return -EBUSY; 104 105 err_fib_net_dump: 106 rcu_read_unlock(); 107 return err; 108 } 109 EXPORT_SYMBOL(register_fib_notifier); 110 111 int unregister_fib_notifier(struct notifier_block *nb) 112 { 113 return atomic_notifier_chain_unregister(&fib_chain, nb); 114 } 115 EXPORT_SYMBOL(unregister_fib_notifier); 116 117 static int __fib_notifier_ops_register(struct fib_notifier_ops *ops, 118 struct net *net) 119 { 120 struct fib_notifier_ops *o; 121 122 list_for_each_entry(o, &net->fib_notifier_ops, list) 123 if (ops->family == o->family) 124 return -EEXIST; 125 list_add_tail_rcu(&ops->list, &net->fib_notifier_ops); 126 return 0; 127 } 128 129 struct fib_notifier_ops * 130 fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net) 131 { 132 struct fib_notifier_ops *ops; 133 int err; 134 135 ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL); 136 if (!ops) 137 return ERR_PTR(-ENOMEM); 138 139 err = __fib_notifier_ops_register(ops, net); 140 if (err) 141 goto err_register; 142 143 return ops; 144 145 err_register: 146 kfree(ops); 147 return ERR_PTR(err); 148 } 149 EXPORT_SYMBOL(fib_notifier_ops_register); 150 151 void fib_notifier_ops_unregister(struct fib_notifier_ops *ops) 152 { 153 list_del_rcu(&ops->list); 154 kfree_rcu(ops, rcu); 155 } 156 EXPORT_SYMBOL(fib_notifier_ops_unregister); 157 158 static int __net_init fib_notifier_net_init(struct net *net) 159 { 160 INIT_LIST_HEAD(&net->fib_notifier_ops); 161 return 0; 162 } 163 164 static struct pernet_operations fib_notifier_net_ops = { 165 .init = fib_notifier_net_init, 166 }; 167 168 static int __init fib_notifier_init(void) 169 { 170 return register_pernet_subsys(&fib_notifier_net_ops); 171 } 172 173 subsys_initcall(fib_notifier_init); 174