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/netns/generic.h> 9 #include <net/fib_notifier.h> 10 11 static unsigned int fib_notifier_net_id; 12 13 struct fib_notifier_net { 14 struct list_head fib_notifier_ops; 15 struct atomic_notifier_head fib_chain; 16 }; 17 18 int call_fib_notifier(struct notifier_block *nb, 19 enum fib_event_type event_type, 20 struct fib_notifier_info *info) 21 { 22 int err; 23 24 err = nb->notifier_call(nb, event_type, info); 25 return notifier_to_errno(err); 26 } 27 EXPORT_SYMBOL(call_fib_notifier); 28 29 int call_fib_notifiers(struct net *net, enum fib_event_type event_type, 30 struct fib_notifier_info *info) 31 { 32 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 33 int err; 34 35 err = atomic_notifier_call_chain(&fn_net->fib_chain, event_type, info); 36 return notifier_to_errno(err); 37 } 38 EXPORT_SYMBOL(call_fib_notifiers); 39 40 static unsigned int fib_seq_sum(struct net *net) 41 { 42 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 43 struct fib_notifier_ops *ops; 44 unsigned int fib_seq = 0; 45 46 rtnl_lock(); 47 rcu_read_lock(); 48 list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) { 49 if (!try_module_get(ops->owner)) 50 continue; 51 fib_seq += ops->fib_seq_read(net); 52 module_put(ops->owner); 53 } 54 rcu_read_unlock(); 55 rtnl_unlock(); 56 57 return fib_seq; 58 } 59 60 static int fib_net_dump(struct net *net, struct notifier_block *nb, 61 struct netlink_ext_ack *extack) 62 { 63 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 64 struct fib_notifier_ops *ops; 65 int err = 0; 66 67 rcu_read_lock(); 68 list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) { 69 if (!try_module_get(ops->owner)) 70 continue; 71 err = ops->fib_dump(net, nb, extack); 72 module_put(ops->owner); 73 if (err) 74 goto unlock; 75 } 76 77 unlock: 78 rcu_read_unlock(); 79 80 return err; 81 } 82 83 static bool fib_dump_is_consistent(struct net *net, struct notifier_block *nb, 84 void (*cb)(struct notifier_block *nb), 85 unsigned int fib_seq) 86 { 87 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 88 89 atomic_notifier_chain_register(&fn_net->fib_chain, nb); 90 if (fib_seq == fib_seq_sum(net)) 91 return true; 92 atomic_notifier_chain_unregister(&fn_net->fib_chain, nb); 93 if (cb) 94 cb(nb); 95 return false; 96 } 97 98 #define FIB_DUMP_MAX_RETRIES 5 99 int register_fib_notifier(struct net *net, struct notifier_block *nb, 100 void (*cb)(struct notifier_block *nb), 101 struct netlink_ext_ack *extack) 102 { 103 int retries = 0; 104 int err; 105 106 do { 107 unsigned int fib_seq = fib_seq_sum(net); 108 109 err = fib_net_dump(net, nb, extack); 110 if (err) 111 return err; 112 113 if (fib_dump_is_consistent(net, nb, cb, fib_seq)) 114 return 0; 115 } while (++retries < FIB_DUMP_MAX_RETRIES); 116 117 return -EBUSY; 118 } 119 EXPORT_SYMBOL(register_fib_notifier); 120 121 int unregister_fib_notifier(struct net *net, struct notifier_block *nb) 122 { 123 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 124 125 return atomic_notifier_chain_unregister(&fn_net->fib_chain, nb); 126 } 127 EXPORT_SYMBOL(unregister_fib_notifier); 128 129 static int __fib_notifier_ops_register(struct fib_notifier_ops *ops, 130 struct net *net) 131 { 132 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 133 struct fib_notifier_ops *o; 134 135 list_for_each_entry(o, &fn_net->fib_notifier_ops, list) 136 if (ops->family == o->family) 137 return -EEXIST; 138 list_add_tail_rcu(&ops->list, &fn_net->fib_notifier_ops); 139 return 0; 140 } 141 142 struct fib_notifier_ops * 143 fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net) 144 { 145 struct fib_notifier_ops *ops; 146 int err; 147 148 ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL); 149 if (!ops) 150 return ERR_PTR(-ENOMEM); 151 152 err = __fib_notifier_ops_register(ops, net); 153 if (err) 154 goto err_register; 155 156 return ops; 157 158 err_register: 159 kfree(ops); 160 return ERR_PTR(err); 161 } 162 EXPORT_SYMBOL(fib_notifier_ops_register); 163 164 void fib_notifier_ops_unregister(struct fib_notifier_ops *ops) 165 { 166 list_del_rcu(&ops->list); 167 kfree_rcu(ops, rcu); 168 } 169 EXPORT_SYMBOL(fib_notifier_ops_unregister); 170 171 static int __net_init fib_notifier_net_init(struct net *net) 172 { 173 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 174 175 INIT_LIST_HEAD(&fn_net->fib_notifier_ops); 176 ATOMIC_INIT_NOTIFIER_HEAD(&fn_net->fib_chain); 177 return 0; 178 } 179 180 static void __net_exit fib_notifier_net_exit(struct net *net) 181 { 182 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id); 183 184 WARN_ON_ONCE(!list_empty(&fn_net->fib_notifier_ops)); 185 } 186 187 static struct pernet_operations fib_notifier_net_ops = { 188 .init = fib_notifier_net_init, 189 .exit = fib_notifier_net_exit, 190 .id = &fib_notifier_net_id, 191 .size = sizeof(struct fib_notifier_net), 192 }; 193 194 static int __init fib_notifier_init(void) 195 { 196 return register_pernet_subsys(&fib_notifier_net_ops); 197 } 198 199 subsys_initcall(fib_notifier_init); 200