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