1/* SPDX-License-Identifier: GPL-2.0 */
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 bool netif_is_gretap(const struct net_device *dev)
41{
42 return dev->rtnl_link_ops &&
43 !strcmp(dev->rtnl_link_ops->kind, "gretap");
44}
45
46static inline bool netif_is_ip6gretap(const struct net_device *dev)
47{
48 return dev->rtnl_link_ops &&
49 !strcmp(dev->rtnl_link_ops->kind, "ip6gretap");
50}
51
52static inline int gre_calc_hlen(__be16 o_flags)
53{
54 int addend = 4;
55
56 if (o_flags & TUNNEL_CSUM)
57 addend += 4;
58 if (o_flags & TUNNEL_KEY)
59 addend += 4;
60 if (o_flags & TUNNEL_SEQ)
61 addend += 4;
62 return addend;
63}
64
65static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
66{
67 __be16 tflags = 0;
68
69 if (flags & GRE_CSUM)
70 tflags |= TUNNEL_CSUM;
71 if (flags & GRE_ROUTING)
72 tflags |= TUNNEL_ROUTING;
73 if (flags & GRE_KEY)
74 tflags |= TUNNEL_KEY;
75 if (flags & GRE_SEQ)
76 tflags |= TUNNEL_SEQ;
77 if (flags & GRE_STRICT)
78 tflags |= TUNNEL_STRICT;
79 if (flags & GRE_REC)
80 tflags |= TUNNEL_REC;
81 if (flags & GRE_VERSION)
82 tflags |= TUNNEL_VERSION;
83
84 return tflags;
85}
86
87static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
88{
89 __be16 flags = 0;
90
91 if (tflags & TUNNEL_CSUM)
92 flags |= GRE_CSUM;
93 if (tflags & TUNNEL_ROUTING)
94 flags |= GRE_ROUTING;
95 if (tflags & TUNNEL_KEY)
96 flags |= GRE_KEY;
97 if (tflags & TUNNEL_SEQ)
98 flags |= GRE_SEQ;
99 if (tflags & TUNNEL_STRICT)
100 flags |= GRE_STRICT;
101 if (tflags & TUNNEL_REC)
102 flags |= GRE_REC;
103 if (tflags & TUNNEL_VERSION)
104 flags |= GRE_VERSION;
105
106 return flags;
107}
108
109static inline __sum16 gre_checksum(struct sk_buff *skb)
110{
111 __wsum csum;
112
113 if (skb->ip_summed == CHECKSUM_PARTIAL)
114 csum = lco_csum(skb);
115 else
116 csum = skb_checksum(skb, 0, skb->len, 0);
117 return csum_fold(csum);
118}
119
120static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
121 __be16 flags, __be16 proto,
122 __be32 key, __be32 seq)
123{
124 struct gre_base_hdr *greh;
125
126 skb_push(skb, hdr_len);
127
128 skb_set_inner_protocol(skb, proto);
129 skb_reset_transport_header(skb);
130 greh = (struct gre_base_hdr *)skb->data;
131 greh->flags = gre_tnl_flags_to_gre_flags(flags);
132 greh->protocol = proto;
133
134 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
135 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
136
137 if (flags & TUNNEL_SEQ) {
138 *ptr = seq;
139 ptr--;
140 }
141 if (flags & TUNNEL_KEY) {
142 *ptr = key;
143 ptr--;
144 }
145 if (flags & TUNNEL_CSUM &&
146 !(skb_shinfo(skb)->gso_type &
147 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
148 *ptr = 0;
149 *(__sum16 *)ptr = gre_checksum(skb);
150 }
151 }
152}
153
154#endif
155