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