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 };
16
17 static ATOMIC_NOTIFIER_HEAD(fib_chain);
18
call_fib_notifier(struct notifier_block * nb,struct net * net,enum fib_event_type event_type,struct fib_notifier_info * info)19 int call_fib_notifier(struct notifier_block *nb, struct net *net,
20 enum fib_event_type event_type,
21 struct fib_notifier_info *info)
22 {
23 int err;
24
25 info->net = net;
26 err = nb->notifier_call(nb, event_type, info);
27 return notifier_to_errno(err);
28 }
29 EXPORT_SYMBOL(call_fib_notifier);
30
call_fib_notifiers(struct net * net,enum fib_event_type event_type,struct fib_notifier_info * info)31 int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
32 struct fib_notifier_info *info)
33 {
34 int err;
35
36 info->net = net;
37 err = atomic_notifier_call_chain(&fib_chain, event_type, info);
38 return notifier_to_errno(err);
39 }
40 EXPORT_SYMBOL(call_fib_notifiers);
41
fib_seq_sum(void)42 static unsigned int fib_seq_sum(void)
43 {
44 struct fib_notifier_net *fn_net;
45 struct fib_notifier_ops *ops;
46 unsigned int fib_seq = 0;
47 struct net *net;
48
49 rtnl_lock();
50 down_read(&net_rwsem);
51 for_each_net(net) {
52 fn_net = net_generic(net, fib_notifier_net_id);
53 rcu_read_lock();
54 list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
55 if (!try_module_get(ops->owner))
56 continue;
57 fib_seq += ops->fib_seq_read(net);
58 module_put(ops->owner);
59 }
60 rcu_read_unlock();
61 }
62 up_read(&net_rwsem);
63 rtnl_unlock();
64
65 return fib_seq;
66 }
67
fib_net_dump(struct net * net,struct notifier_block * nb)68 static int fib_net_dump(struct net *net, struct notifier_block *nb)
69 {
70 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
71 struct fib_notifier_ops *ops;
72
73 list_for_each_entry_rcu(ops, &fn_net->fib_notifier_ops, list) {
74 int err;
75
76 if (!try_module_get(ops->owner))
77 continue;
78 err = ops->fib_dump(net, nb);
79 module_put(ops->owner);
80 if (err)
81 return err;
82 }
83
84 return 0;
85 }
86
fib_dump_is_consistent(struct notifier_block * nb,void (* cb)(struct notifier_block * nb),unsigned int fib_seq)87 static bool fib_dump_is_consistent(struct notifier_block *nb,
88 void (*cb)(struct notifier_block *nb),
89 unsigned int fib_seq)
90 {
91 atomic_notifier_chain_register(&fib_chain, nb);
92 if (fib_seq == fib_seq_sum())
93 return true;
94 atomic_notifier_chain_unregister(&fib_chain, nb);
95 if (cb)
96 cb(nb);
97 return false;
98 }
99
100 #define FIB_DUMP_MAX_RETRIES 5
register_fib_notifier(struct notifier_block * nb,void (* cb)(struct notifier_block * nb))101 int register_fib_notifier(struct notifier_block *nb,
102 void (*cb)(struct notifier_block *nb))
103 {
104 int retries = 0;
105 int err;
106
107 do {
108 unsigned int fib_seq = fib_seq_sum();
109 struct net *net;
110
111 rcu_read_lock();
112 for_each_net_rcu(net) {
113 err = fib_net_dump(net, nb);
114 if (err)
115 goto err_fib_net_dump;
116 }
117 rcu_read_unlock();
118
119 if (fib_dump_is_consistent(nb, cb, fib_seq))
120 return 0;
121 } while (++retries < FIB_DUMP_MAX_RETRIES);
122
123 return -EBUSY;
124
125 err_fib_net_dump:
126 rcu_read_unlock();
127 return err;
128 }
129 EXPORT_SYMBOL(register_fib_notifier);
130
unregister_fib_notifier(struct notifier_block * nb)131 int unregister_fib_notifier(struct notifier_block *nb)
132 {
133 return atomic_notifier_chain_unregister(&fib_chain, nb);
134 }
135 EXPORT_SYMBOL(unregister_fib_notifier);
136
__fib_notifier_ops_register(struct fib_notifier_ops * ops,struct net * net)137 static int __fib_notifier_ops_register(struct fib_notifier_ops *ops,
138 struct net *net)
139 {
140 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
141 struct fib_notifier_ops *o;
142
143 list_for_each_entry(o, &fn_net->fib_notifier_ops, list)
144 if (ops->family == o->family)
145 return -EEXIST;
146 list_add_tail_rcu(&ops->list, &fn_net->fib_notifier_ops);
147 return 0;
148 }
149
150 struct fib_notifier_ops *
fib_notifier_ops_register(const struct fib_notifier_ops * tmpl,struct net * net)151 fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net)
152 {
153 struct fib_notifier_ops *ops;
154 int err;
155
156 ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
157 if (!ops)
158 return ERR_PTR(-ENOMEM);
159
160 err = __fib_notifier_ops_register(ops, net);
161 if (err)
162 goto err_register;
163
164 return ops;
165
166 err_register:
167 kfree(ops);
168 return ERR_PTR(err);
169 }
170 EXPORT_SYMBOL(fib_notifier_ops_register);
171
fib_notifier_ops_unregister(struct fib_notifier_ops * ops)172 void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
173 {
174 list_del_rcu(&ops->list);
175 kfree_rcu(ops, rcu);
176 }
177 EXPORT_SYMBOL(fib_notifier_ops_unregister);
178
fib_notifier_net_init(struct net * net)179 static int __net_init fib_notifier_net_init(struct net *net)
180 {
181 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
182
183 INIT_LIST_HEAD(&fn_net->fib_notifier_ops);
184 return 0;
185 }
186
fib_notifier_net_exit(struct net * net)187 static void __net_exit fib_notifier_net_exit(struct net *net)
188 {
189 struct fib_notifier_net *fn_net = net_generic(net, fib_notifier_net_id);
190
191 WARN_ON_ONCE(!list_empty(&fn_net->fib_notifier_ops));
192 }
193
194 static struct pernet_operations fib_notifier_net_ops = {
195 .init = fib_notifier_net_init,
196 .exit = fib_notifier_net_exit,
197 .id = &fib_notifier_net_id,
198 .size = sizeof(struct fib_notifier_net),
199 };
200
fib_notifier_init(void)201 static int __init fib_notifier_init(void)
202 {
203 return register_pernet_subsys(&fib_notifier_net_ops);
204 }
205
206 subsys_initcall(fib_notifier_init);
207
