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
 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