1#ifndef __LINUX_GRE_H
 2#define __LINUX_GRE_H
 3
 4#include <linux/skbuff.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 5
 6#define GREPROTO_CISCO		0
 7#define GREPROTO_PPTP		1
 8#define GREPROTO_MAX		2
 
 9
10struct gre_protocol {
11	int  (*handler)(struct sk_buff *skb);
12	void (*err_handler)(struct sk_buff *skb, u32 info);
13};
14
15int gre_add_protocol(const struct gre_protocol *proto, u8 version);
16int gre_del_protocol(const struct gre_protocol *proto, u8 version);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
17
18#endif

  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
 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