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04b1d4e5 IS |
1 | #include <linux/rtnetlink.h> |
2 | #include <linux/notifier.h> | |
3 | #include <linux/rcupdate.h> | |
4 | #include <linux/kernel.h> | |
864150df | 5 | #include <linux/module.h> |
04b1d4e5 IS |
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 | ||
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 | { | |
c30d9356 DA |
16 | int err; |
17 | ||
04b1d4e5 | 18 | info->net = net; |
c30d9356 DA |
19 | err = nb->notifier_call(nb, event_type, info); |
20 | return notifier_to_errno(err); | |
04b1d4e5 IS |
21 | } |
22 | EXPORT_SYMBOL(call_fib_notifier); | |
23 | ||
24 | int call_fib_notifiers(struct net *net, enum fib_event_type event_type, | |
25 | struct fib_notifier_info *info) | |
26 | { | |
c30d9356 DA |
27 | int err; |
28 | ||
04b1d4e5 | 29 | info->net = net; |
c30d9356 DA |
30 | err = atomic_notifier_call_chain(&fib_chain, event_type, info); |
31 | return notifier_to_errno(err); | |
04b1d4e5 IS |
32 | } |
33 | EXPORT_SYMBOL(call_fib_notifiers); | |
34 | ||
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(); | |
f0b07bb1 | 42 | down_read(&net_rwsem); |
04b1d4e5 | 43 | for_each_net(net) { |
11bf284f KT |
44 | rcu_read_lock(); |
45 | list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) { | |
864150df IS |
46 | if (!try_module_get(ops->owner)) |
47 | continue; | |
04b1d4e5 | 48 | fib_seq += ops->fib_seq_read(net); |
864150df IS |
49 | module_put(ops->owner); |
50 | } | |
11bf284f | 51 | rcu_read_unlock(); |
04b1d4e5 | 52 | } |
f0b07bb1 | 53 | up_read(&net_rwsem); |
04b1d4e5 IS |
54 | rtnl_unlock(); |
55 | ||
56 | return fib_seq; | |
57 | } | |
58 | ||
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) { | |
864150df | 64 | int err; |
04b1d4e5 | 65 | |
864150df IS |
66 | if (!try_module_get(ops->owner)) |
67 | continue; | |
68 | err = ops->fib_dump(net, nb); | |
69 | module_put(ops->owner); | |
04b1d4e5 IS |
70 | if (err) |
71 | return err; | |
72 | } | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
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 | |
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 | ||
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 | ||
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 * | |
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 | ||
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 | ||
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 | ||
0b6f5955 VA |
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 | ||
04b1d4e5 IS |
179 | static struct pernet_operations fib_notifier_net_ops = { |
180 | .init = fib_notifier_net_init, | |
0b6f5955 | 181 | .exit = fib_notifier_net_exit, |
04b1d4e5 IS |
182 | }; |
183 | ||
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); |