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00959ade DK |
1 | /* |
2 | * GRE over IPv4 demultiplexer driver | |
3 | * | |
4 | * Authors: Dmitry Kozlov (xeb@mail.ru) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | * | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/kmod.h> | |
16 | #include <linux/skbuff.h> | |
17 | #include <linux/in.h> | |
18 | #include <linux/netdevice.h> | |
19 | #include <linux/version.h> | |
20 | #include <linux/spinlock.h> | |
21 | #include <net/protocol.h> | |
22 | #include <net/gre.h> | |
23 | ||
24 | ||
25 | const struct gre_protocol *gre_proto[GREPROTO_MAX] __read_mostly; | |
26 | static DEFINE_SPINLOCK(gre_proto_lock); | |
27 | ||
28 | int gre_add_protocol(const struct gre_protocol *proto, u8 version) | |
29 | { | |
30 | if (version >= GREPROTO_MAX) | |
31 | goto err_out; | |
32 | ||
33 | spin_lock(&gre_proto_lock); | |
34 | if (gre_proto[version]) | |
35 | goto err_out_unlock; | |
36 | ||
37 | rcu_assign_pointer(gre_proto[version], proto); | |
38 | spin_unlock(&gre_proto_lock); | |
39 | return 0; | |
40 | ||
41 | err_out_unlock: | |
42 | spin_unlock(&gre_proto_lock); | |
43 | err_out: | |
44 | return -1; | |
45 | } | |
46 | EXPORT_SYMBOL_GPL(gre_add_protocol); | |
47 | ||
48 | int gre_del_protocol(const struct gre_protocol *proto, u8 version) | |
49 | { | |
50 | if (version >= GREPROTO_MAX) | |
51 | goto err_out; | |
52 | ||
53 | spin_lock(&gre_proto_lock); | |
54 | if (gre_proto[version] != proto) | |
55 | goto err_out_unlock; | |
56 | rcu_assign_pointer(gre_proto[version], NULL); | |
57 | spin_unlock(&gre_proto_lock); | |
58 | synchronize_rcu(); | |
59 | return 0; | |
60 | ||
61 | err_out_unlock: | |
62 | spin_unlock(&gre_proto_lock); | |
63 | err_out: | |
64 | return -1; | |
65 | } | |
66 | EXPORT_SYMBOL_GPL(gre_del_protocol); | |
67 | ||
68 | static int gre_rcv(struct sk_buff *skb) | |
69 | { | |
70 | const struct gre_protocol *proto; | |
71 | u8 ver; | |
72 | int ret; | |
73 | ||
74 | if (!pskb_may_pull(skb, 12)) | |
75 | goto drop; | |
76 | ||
77 | ver = skb->data[1]&0x7f; | |
78 | if (ver >= GREPROTO_MAX) | |
79 | goto drop; | |
80 | ||
81 | rcu_read_lock(); | |
82 | proto = rcu_dereference(gre_proto[ver]); | |
83 | if (!proto || !proto->handler) | |
84 | goto drop_unlock; | |
85 | ret = proto->handler(skb); | |
86 | rcu_read_unlock(); | |
87 | return ret; | |
88 | ||
89 | drop_unlock: | |
90 | rcu_read_unlock(); | |
91 | drop: | |
92 | kfree_skb(skb); | |
93 | return NET_RX_DROP; | |
94 | } | |
95 | ||
96 | static void gre_err(struct sk_buff *skb, u32 info) | |
97 | { | |
98 | const struct gre_protocol *proto; | |
99 | u8 ver; | |
100 | ||
101 | if (!pskb_may_pull(skb, 12)) | |
102 | goto drop; | |
103 | ||
104 | ver = skb->data[1]&0x7f; | |
105 | if (ver >= GREPROTO_MAX) | |
106 | goto drop; | |
107 | ||
108 | rcu_read_lock(); | |
109 | proto = rcu_dereference(gre_proto[ver]); | |
110 | if (!proto || !proto->err_handler) | |
111 | goto drop_unlock; | |
112 | proto->err_handler(skb, info); | |
113 | rcu_read_unlock(); | |
114 | return; | |
115 | ||
116 | drop_unlock: | |
117 | rcu_read_unlock(); | |
118 | drop: | |
119 | kfree_skb(skb); | |
120 | } | |
121 | ||
122 | static const struct net_protocol net_gre_protocol = { | |
123 | .handler = gre_rcv, | |
124 | .err_handler = gre_err, | |
125 | .netns_ok = 1, | |
126 | }; | |
127 | ||
128 | static int __init gre_init(void) | |
129 | { | |
130 | pr_info("GRE over IPv4 demultiplexor driver"); | |
131 | ||
132 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
133 | pr_err("gre: can't add protocol\n"); | |
134 | return -EAGAIN; | |
135 | } | |
136 | ||
137 | return 0; | |
138 | } | |
139 | ||
140 | static void __exit gre_exit(void) | |
141 | { | |
142 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
143 | } | |
144 | ||
145 | module_init(gre_init); | |
146 | module_exit(gre_exit); | |
147 | ||
148 | MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); | |
149 | MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); | |
150 | MODULE_LICENSE("GPL"); | |
151 |