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
40bool is_gretap_dev(const struct net_device *dev);
41bool is_ip6gretap_dev(const struct net_device *dev);
42
43static inline int gre_calc_hlen(__be16 o_flags)
44{
45 int addend = 4;
46
47 if (o_flags & TUNNEL_CSUM)
48 addend += 4;
49 if (o_flags & TUNNEL_KEY)
50 addend += 4;
51 if (o_flags & TUNNEL_SEQ)
52 addend += 4;
53 return addend;
54}
55
56static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
57{
58 __be16 tflags = 0;
59
60 if (flags & GRE_CSUM)
61 tflags |= TUNNEL_CSUM;
62 if (flags & GRE_ROUTING)
63 tflags |= TUNNEL_ROUTING;
64 if (flags & GRE_KEY)
65 tflags |= TUNNEL_KEY;
66 if (flags & GRE_SEQ)
67 tflags |= TUNNEL_SEQ;
68 if (flags & GRE_STRICT)
69 tflags |= TUNNEL_STRICT;
70 if (flags & GRE_REC)
71 tflags |= TUNNEL_REC;
72 if (flags & GRE_VERSION)
73 tflags |= TUNNEL_VERSION;
74
75 return tflags;
76}
77
78static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
79{
80 __be16 flags = 0;
81
82 if (tflags & TUNNEL_CSUM)
83 flags |= GRE_CSUM;
84 if (tflags & TUNNEL_ROUTING)
85 flags |= GRE_ROUTING;
86 if (tflags & TUNNEL_KEY)
87 flags |= GRE_KEY;
88 if (tflags & TUNNEL_SEQ)
89 flags |= GRE_SEQ;
90 if (tflags & TUNNEL_STRICT)
91 flags |= GRE_STRICT;
92 if (tflags & TUNNEL_REC)
93 flags |= GRE_REC;
94 if (tflags & TUNNEL_VERSION)
95 flags |= GRE_VERSION;
96
97 return flags;
98}
99
100static inline __sum16 gre_checksum(struct sk_buff *skb)
101{
102 __wsum csum;
103
104 if (skb->ip_summed == CHECKSUM_PARTIAL)
105 csum = lco_csum(skb);
106 else
107 csum = skb_checksum(skb, 0, skb->len, 0);
108 return csum_fold(csum);
109}
110
111static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
112 __be16 flags, __be16 proto,
113 __be32 key, __be32 seq)
114{
115 struct gre_base_hdr *greh;
116
117 skb_push(skb, hdr_len);
118
119 skb_set_inner_protocol(skb, proto);
120 skb_reset_transport_header(skb);
121 greh = (struct gre_base_hdr *)skb->data;
122 greh->flags = gre_tnl_flags_to_gre_flags(flags);
123 greh->protocol = proto;
124
125 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
126 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
127
128 if (flags & TUNNEL_SEQ) {
129 *ptr = seq;
130 ptr--;
131 }
132 if (flags & TUNNEL_KEY) {
133 *ptr = key;
134 ptr--;
135 }
136 if (flags & TUNNEL_CSUM &&
137 !(skb_shinfo(skb)->gso_type &
138 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
139 *ptr = 0;
140 *(__sum16 *)ptr = gre_checksum(skb);
141 }
142 }
143}
144
145#endif
146
