1
2#ifndef __LINUX_GRE_H
3#define __LINUX_GRE_H
4
5#include <linux/skbuff.h>
6#include <net/ip_tunnels.h>
7
8struct gre_base_hdr {
9 __be16 flags;
10 __be16 protocol;
11} __packed;
12
13struct gre_full_hdr {
14 struct gre_base_hdr fixed_header;
15 __be16 csum;
16 __be16 reserved1;
17 __be32 key;
18 __be32 seq;
19} __packed;
20#define GRE_HEADER_SECTION 4
21
22#define GREPROTO_CISCO 0
23#define GREPROTO_PPTP 1
24#define GREPROTO_MAX 2
25#define GRE_IP_PROTO_MAX 2
26
27struct gre_protocol {
28 int (*handler)(struct sk_buff *skb);
29 void (*err_handler)(struct sk_buff *skb, u32 info);
30};
31
32int gre_add_protocol(const struct gre_protocol *proto, u8 version);
33int gre_del_protocol(const struct gre_protocol *proto, u8 version);
34
35struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
36 u8 name_assign_type);
37int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
38 bool *csum_err, __be16 proto, int nhs);
39
40static inline int gre_calc_hlen(__be16 o_flags)
41{
42 int addend = 4;
43
44 if (o_flags & TUNNEL_CSUM)
45 addend += 4;
46 if (o_flags & TUNNEL_KEY)
47 addend += 4;
48 if (o_flags & TUNNEL_SEQ)
49 addend += 4;
50 return addend;
51}
52
53static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
54{
55 __be16 tflags = 0;
56
57 if (flags & GRE_CSUM)
58 tflags |= TUNNEL_CSUM;
59 if (flags & GRE_ROUTING)
60 tflags |= TUNNEL_ROUTING;
61 if (flags & GRE_KEY)
62 tflags |= TUNNEL_KEY;
63 if (flags & GRE_SEQ)
64 tflags |= TUNNEL_SEQ;
65 if (flags & GRE_STRICT)
66 tflags |= TUNNEL_STRICT;
67 if (flags & GRE_REC)
68 tflags |= TUNNEL_REC;
69 if (flags & GRE_VERSION)
70 tflags |= TUNNEL_VERSION;
71
72 return tflags;
73}
74
75static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
76{
77 __be16 flags = 0;
78
79 if (tflags & TUNNEL_CSUM)
80 flags |= GRE_CSUM;
81 if (tflags & TUNNEL_ROUTING)
82 flags |= GRE_ROUTING;
83 if (tflags & TUNNEL_KEY)
84 flags |= GRE_KEY;
85 if (tflags & TUNNEL_SEQ)
86 flags |= GRE_SEQ;
87 if (tflags & TUNNEL_STRICT)
88 flags |= GRE_STRICT;
89 if (tflags & TUNNEL_REC)
90 flags |= GRE_REC;
91 if (tflags & TUNNEL_VERSION)
92 flags |= GRE_VERSION;
93
94 return flags;
95}
96
97static inline __sum16 gre_checksum(struct sk_buff *skb)
98{
99 __wsum csum;
100
101 if (skb->ip_summed == CHECKSUM_PARTIAL)
102 csum = lco_csum(skb);
103 else
104 csum = skb_checksum(skb, 0, skb->len, 0);
105 return csum_fold(csum);
106}
107
108static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
109 __be16 flags, __be16 proto,
110 __be32 key, __be32 seq)
111{
112 struct gre_base_hdr *greh;
113
114 skb_push(skb, hdr_len);
115
116 skb_set_inner_protocol(skb, proto);
117 skb_reset_transport_header(skb);
118 greh = (struct gre_base_hdr *)skb->data;
119 greh->flags = gre_tnl_flags_to_gre_flags(flags);
120 greh->protocol = proto;
121
122 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
123 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
124
125 if (flags & TUNNEL_SEQ) {
126 *ptr = seq;
127 ptr--;
128 }
129 if (flags & TUNNEL_KEY) {
130 *ptr = key;
131 ptr--;
132 }
133 if (flags & TUNNEL_CSUM &&
134 !(skb_shinfo(skb)->gso_type &
135 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
136 *ptr = 0;
137 *(__sum16 *)ptr = gre_checksum(skb);
138 }
139 }
140}
141
142#endif
143
