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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 | ||
afd46503 JP |
13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
14 | ||
00959ade | 15 | #include <linux/module.h> |
bda7bb46 PS |
16 | #include <linux/if.h> |
17 | #include <linux/icmp.h> | |
00959ade DK |
18 | #include <linux/kernel.h> |
19 | #include <linux/kmod.h> | |
20 | #include <linux/skbuff.h> | |
21 | #include <linux/in.h> | |
559fafb9 | 22 | #include <linux/ip.h> |
00959ade | 23 | #include <linux/netdevice.h> |
68c33163 | 24 | #include <linux/if_tunnel.h> |
00959ade DK |
25 | #include <linux/spinlock.h> |
26 | #include <net/protocol.h> | |
27 | #include <net/gre.h> | |
28 | ||
bda7bb46 PS |
29 | #include <net/icmp.h> |
30 | #include <net/route.h> | |
31 | #include <net/xfrm.h> | |
00959ade | 32 | |
6f0bcf15 | 33 | static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly; |
00959ade DK |
34 | |
35 | int gre_add_protocol(const struct gre_protocol *proto, u8 version) | |
36 | { | |
37 | if (version >= GREPROTO_MAX) | |
20fd4d1f | 38 | return -EINVAL; |
00959ade | 39 | |
20fd4d1f PS |
40 | return (cmpxchg((const struct gre_protocol **)&gre_proto[version], NULL, proto) == NULL) ? |
41 | 0 : -EBUSY; | |
00959ade DK |
42 | } |
43 | EXPORT_SYMBOL_GPL(gre_add_protocol); | |
44 | ||
45 | int gre_del_protocol(const struct gre_protocol *proto, u8 version) | |
46 | { | |
20fd4d1f PS |
47 | int ret; |
48 | ||
00959ade | 49 | if (version >= GREPROTO_MAX) |
20fd4d1f PS |
50 | return -EINVAL; |
51 | ||
52 | ret = (cmpxchg((const struct gre_protocol **)&gre_proto[version], proto, NULL) == proto) ? | |
53 | 0 : -EBUSY; | |
54 | ||
55 | if (ret) | |
56 | return ret; | |
57 | ||
00959ade DK |
58 | synchronize_rcu(); |
59 | return 0; | |
00959ade DK |
60 | } |
61 | EXPORT_SYMBOL_GPL(gre_del_protocol); | |
62 | ||
95f5c64c TH |
63 | int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, |
64 | bool *csum_err, int *ret_hdr_len) | |
65 | { | |
66 | const struct gre_base_hdr *greh; | |
67 | __be32 *options; | |
68 | int hdr_len; | |
69 | ||
70 | if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) | |
71 | return -EINVAL; | |
72 | ||
73 | greh = (struct gre_base_hdr *)skb_transport_header(skb); | |
74 | if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) | |
75 | return -EINVAL; | |
76 | ||
77 | tpi->flags = gre_flags_to_tnl_flags(greh->flags); | |
78 | hdr_len = gre_calc_hlen(tpi->flags); | |
79 | ||
80 | if (!pskb_may_pull(skb, hdr_len)) | |
81 | return -EINVAL; | |
82 | ||
83 | greh = (struct gre_base_hdr *)skb_transport_header(skb); | |
84 | tpi->proto = greh->protocol; | |
85 | ||
86 | options = (__be32 *)(greh + 1); | |
87 | if (greh->flags & GRE_CSUM) { | |
88 | if (skb_checksum_simple_validate(skb)) { | |
89 | *csum_err = true; | |
90 | return -EINVAL; | |
91 | } | |
92 | ||
93 | skb_checksum_try_convert(skb, IPPROTO_GRE, 0, | |
94 | null_compute_pseudo); | |
95 | options++; | |
96 | } | |
97 | ||
98 | if (greh->flags & GRE_KEY) { | |
99 | tpi->key = *options; | |
100 | options++; | |
101 | } else { | |
102 | tpi->key = 0; | |
103 | } | |
104 | if (unlikely(greh->flags & GRE_SEQ)) { | |
105 | tpi->seq = *options; | |
106 | options++; | |
107 | } else { | |
108 | tpi->seq = 0; | |
109 | } | |
110 | /* WCCP version 1 and 2 protocol decoding. | |
111 | * - Change protocol to IP | |
112 | * - When dealing with WCCPv2, Skip extra 4 bytes in GRE header | |
113 | */ | |
114 | if (greh->flags == 0 && tpi->proto == htons(ETH_P_WCCP)) { | |
115 | tpi->proto = htons(ETH_P_IP); | |
116 | if ((*(u8 *)options & 0xF0) != 0x40) { | |
117 | hdr_len += 4; | |
118 | if (!pskb_may_pull(skb, hdr_len)) | |
119 | return -EINVAL; | |
120 | } | |
121 | } | |
122 | *ret_hdr_len = hdr_len; | |
123 | return 0; | |
124 | } | |
125 | EXPORT_SYMBOL(gre_parse_header); | |
126 | ||
00959ade DK |
127 | static int gre_rcv(struct sk_buff *skb) |
128 | { | |
129 | const struct gre_protocol *proto; | |
130 | u8 ver; | |
131 | int ret; | |
132 | ||
133 | if (!pskb_may_pull(skb, 12)) | |
134 | goto drop; | |
135 | ||
136 | ver = skb->data[1]&0x7f; | |
137 | if (ver >= GREPROTO_MAX) | |
138 | goto drop; | |
139 | ||
140 | rcu_read_lock(); | |
141 | proto = rcu_dereference(gre_proto[ver]); | |
142 | if (!proto || !proto->handler) | |
143 | goto drop_unlock; | |
144 | ret = proto->handler(skb); | |
145 | rcu_read_unlock(); | |
146 | return ret; | |
147 | ||
148 | drop_unlock: | |
149 | rcu_read_unlock(); | |
150 | drop: | |
151 | kfree_skb(skb); | |
152 | return NET_RX_DROP; | |
153 | } | |
154 | ||
155 | static void gre_err(struct sk_buff *skb, u32 info) | |
156 | { | |
157 | const struct gre_protocol *proto; | |
559fafb9 | 158 | const struct iphdr *iph = (const struct iphdr *)skb->data; |
159 | u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f; | |
00959ade | 160 | |
00959ade | 161 | if (ver >= GREPROTO_MAX) |
559fafb9 | 162 | return; |
00959ade DK |
163 | |
164 | rcu_read_lock(); | |
165 | proto = rcu_dereference(gre_proto[ver]); | |
559fafb9 | 166 | if (proto && proto->err_handler) |
167 | proto->err_handler(skb, info); | |
00959ade | 168 | rcu_read_unlock(); |
00959ade DK |
169 | } |
170 | ||
171 | static const struct net_protocol net_gre_protocol = { | |
172 | .handler = gre_rcv, | |
173 | .err_handler = gre_err, | |
174 | .netns_ok = 1, | |
175 | }; | |
176 | ||
177 | static int __init gre_init(void) | |
178 | { | |
afd46503 | 179 | pr_info("GRE over IPv4 demultiplexor driver\n"); |
00959ade DK |
180 | |
181 | if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) { | |
afd46503 | 182 | pr_err("can't add protocol\n"); |
9f57c67c | 183 | return -EAGAIN; |
bda7bb46 | 184 | } |
00959ade DK |
185 | return 0; |
186 | } | |
187 | ||
188 | static void __exit gre_exit(void) | |
189 | { | |
190 | inet_del_protocol(&net_gre_protocol, IPPROTO_GRE); | |
191 | } | |
192 | ||
193 | module_init(gre_init); | |
194 | module_exit(gre_exit); | |
195 | ||
196 | MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver"); | |
197 | MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)"); | |
198 | MODULE_LICENSE("GPL"); |