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
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