include/net/gre.h

   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
   8 struct gre_base_hdr {
   9         __be16 flags;
  10         __be16 protocol;
  11 } __packed;
  12
  13 struct 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
  27 struct gre_protocol {
  28         int  (*handler)(struct sk_buff *skb);
  29         void (*err_handler)(struct sk_buff *skb, u32 info);
  30 };
  31
  32 int gre_add_protocol(const struct gre_protocol *proto, u8 version);
  33 int gre_del_protocol(const struct gre_protocol *proto, u8 version);
  34
  35 struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
  36                                        u8 name_assign_type);
  37 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
  38                      bool *csum_err, __be16 proto, int nhs);
  39
  40 bool is_gretap_dev(const struct net_device *dev);
  41 bool is_ip6gretap_dev(const struct net_device *dev);
  42
  43 static 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
  56 static 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
  78 static 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
 100 static 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
 111 static 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