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 static 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
  46 static 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
  52 static 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
  65 static 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
  87 static 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
 109 static 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
 120 static 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