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