1 /* SPDX-License-Identifier: GPL-2.0 */
5 #include <linux/skbuff.h>
6 #include <net/ip_tunnels.h>
14 struct gre_base_hdr fixed_header;
20 #define GRE_HEADER_SECTION 4
22 #define GREPROTO_CISCO 0
23 #define GREPROTO_PPTP 1
24 #define GREPROTO_MAX 2
25 #define GRE_IP_PROTO_MAX 2
28 int (*handler)(struct sk_buff *skb);
29 void (*err_handler)(struct sk_buff *skb, u32 info);
32 int gre_add_protocol(const struct gre_protocol *proto, u8 version);
33 int gre_del_protocol(const struct gre_protocol *proto, u8 version);
35 struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
37 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
38 bool *csum_err, __be16 proto, int nhs);
40 static inline int gre_calc_hlen(__be16 o_flags)
44 if (o_flags & TUNNEL_CSUM)
46 if (o_flags & TUNNEL_KEY)
48 if (o_flags & TUNNEL_SEQ)
53 static inline __be16 gre_flags_to_tnl_flags(__be16 flags)
58 tflags |= TUNNEL_CSUM;
59 if (flags & GRE_ROUTING)
60 tflags |= TUNNEL_ROUTING;
65 if (flags & GRE_STRICT)
66 tflags |= TUNNEL_STRICT;
69 if (flags & GRE_VERSION)
70 tflags |= TUNNEL_VERSION;
75 static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags)
79 if (tflags & TUNNEL_CSUM)
81 if (tflags & TUNNEL_ROUTING)
83 if (tflags & TUNNEL_KEY)
85 if (tflags & TUNNEL_SEQ)
87 if (tflags & TUNNEL_STRICT)
89 if (tflags & TUNNEL_REC)
91 if (tflags & TUNNEL_VERSION)
97 static inline __sum16 gre_checksum(struct sk_buff *skb)
101 if (skb->ip_summed == CHECKSUM_PARTIAL)
102 csum = lco_csum(skb);
104 csum = skb_checksum(skb, 0, skb->len, 0);
105 return csum_fold(csum);
108 static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
109 __be16 flags, __be16 proto,
110 __be32 key, __be32 seq)
112 struct gre_base_hdr *greh;
114 skb_push(skb, hdr_len);
116 skb_set_inner_protocol(skb, proto);
117 skb_reset_transport_header(skb);
118 greh = (struct gre_base_hdr *)skb->data;
119 greh->flags = gre_tnl_flags_to_gre_flags(flags);
120 greh->protocol = proto;
122 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) {
123 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
125 if (flags & TUNNEL_SEQ) {
129 if (flags & TUNNEL_KEY) {
133 if (flags & TUNNEL_CSUM &&
134 !(skb_shinfo(skb)->gso_type &
135 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
137 *(__sum16 *)ptr = gre_checksum(skb);