190 lines
4 KiB
C
190 lines
4 KiB
C
#include <linux/rtnetlink.h>
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#include <linux/notifier.h>
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#include <linux/rcupdate.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <net/net_namespace.h>
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#include <net/fib_notifier.h>
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static ATOMIC_NOTIFIER_HEAD(fib_chain);
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int call_fib_notifier(struct notifier_block *nb, struct net *net,
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enum fib_event_type event_type,
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struct fib_notifier_info *info)
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{
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int err;
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info->net = net;
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err = nb->notifier_call(nb, event_type, info);
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return notifier_to_errno(err);
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}
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EXPORT_SYMBOL(call_fib_notifier);
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int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
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struct fib_notifier_info *info)
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{
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int err;
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info->net = net;
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err = atomic_notifier_call_chain(&fib_chain, event_type, info);
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return notifier_to_errno(err);
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}
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EXPORT_SYMBOL(call_fib_notifiers);
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static unsigned int fib_seq_sum(void)
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{
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struct fib_notifier_ops *ops;
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unsigned int fib_seq = 0;
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struct net *net;
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rtnl_lock();
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down_read(&net_rwsem);
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for_each_net(net) {
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rcu_read_lock();
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list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
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if (!try_module_get(ops->owner))
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continue;
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fib_seq += ops->fib_seq_read(net);
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module_put(ops->owner);
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}
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rcu_read_unlock();
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}
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up_read(&net_rwsem);
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rtnl_unlock();
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return fib_seq;
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}
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static int fib_net_dump(struct net *net, struct notifier_block *nb)
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{
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struct fib_notifier_ops *ops;
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list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
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int err;
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if (!try_module_get(ops->owner))
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continue;
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err = ops->fib_dump(net, nb);
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module_put(ops->owner);
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if (err)
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return err;
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}
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return 0;
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}
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static bool fib_dump_is_consistent(struct notifier_block *nb,
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void (*cb)(struct notifier_block *nb),
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unsigned int fib_seq)
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{
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atomic_notifier_chain_register(&fib_chain, nb);
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if (fib_seq == fib_seq_sum())
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return true;
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atomic_notifier_chain_unregister(&fib_chain, nb);
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if (cb)
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cb(nb);
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return false;
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}
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#define FIB_DUMP_MAX_RETRIES 5
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int register_fib_notifier(struct notifier_block *nb,
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void (*cb)(struct notifier_block *nb))
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{
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int retries = 0;
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int err;
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do {
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unsigned int fib_seq = fib_seq_sum();
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struct net *net;
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rcu_read_lock();
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for_each_net_rcu(net) {
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err = fib_net_dump(net, nb);
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if (err)
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goto err_fib_net_dump;
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}
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rcu_read_unlock();
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if (fib_dump_is_consistent(nb, cb, fib_seq))
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return 0;
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} while (++retries < FIB_DUMP_MAX_RETRIES);
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return -EBUSY;
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err_fib_net_dump:
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rcu_read_unlock();
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return err;
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}
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EXPORT_SYMBOL(register_fib_notifier);
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int unregister_fib_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_unregister(&fib_chain, nb);
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}
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EXPORT_SYMBOL(unregister_fib_notifier);
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static int __fib_notifier_ops_register(struct fib_notifier_ops *ops,
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struct net *net)
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{
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struct fib_notifier_ops *o;
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list_for_each_entry(o, &net->fib_notifier_ops, list)
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if (ops->family == o->family)
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return -EEXIST;
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list_add_tail_rcu(&ops->list, &net->fib_notifier_ops);
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return 0;
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}
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struct fib_notifier_ops *
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fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net)
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{
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struct fib_notifier_ops *ops;
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int err;
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ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
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if (!ops)
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return ERR_PTR(-ENOMEM);
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err = __fib_notifier_ops_register(ops, net);
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if (err)
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goto err_register;
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return ops;
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err_register:
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kfree(ops);
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL(fib_notifier_ops_register);
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void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
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{
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list_del_rcu(&ops->list);
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kfree_rcu(ops, rcu);
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}
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EXPORT_SYMBOL(fib_notifier_ops_unregister);
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static int __net_init fib_notifier_net_init(struct net *net)
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{
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INIT_LIST_HEAD(&net->fib_notifier_ops);
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return 0;
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}
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static void __net_exit fib_notifier_net_exit(struct net *net)
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{
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WARN_ON_ONCE(!list_empty(&net->fib_notifier_ops));
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}
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static struct pernet_operations fib_notifier_net_ops = {
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.init = fib_notifier_net_init,
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.exit = fib_notifier_net_exit,
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};
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static int __init fib_notifier_init(void)
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{
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return register_pernet_subsys(&fib_notifier_net_ops);
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}
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subsys_initcall(fib_notifier_init);
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