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(ret: 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, id: fib_notifier_net_id);
33 int err;
34
35 err = atomic_notifier_call_chain(nh: &fn_net->fib_chain, val: event_type, v: info);
36 return notifier_to_errno(ret: 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, id: 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(module: ops->owner))
49 continue;
50 fib_seq += ops->fib_seq_read(net);
51 module_put(module: 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, id: 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(module: ops->owner))
68 continue;
69 err = ops->fib_dump(net, nb, extack);
70 module_put(module: 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, id: fib_notifier_net_id);
86
87 atomic_notifier_chain_register(nh: &fn_net->fib_chain, nb);
88 if (fib_seq == fib_seq_sum(net))
89 return true;
90 atomic_notifier_chain_unregister(nh: &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, id: fib_notifier_net_id);
122
123 return atomic_notifier_chain_unregister(nh: &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, id: 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(new: &ops->list, head: &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(error: -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(objp: ops);
158 return ERR_PTR(error: err);
159}
160EXPORT_SYMBOL(fib_notifier_ops_register);
161
162void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
163{
164 list_del_rcu(entry: &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, id: fib_notifier_net_id);
172
173 INIT_LIST_HEAD(list: &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, id: 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);
198