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(const unsigned long *o_flags)
  53 {
  54         int addend = 4;
  55
  56         if (test_bit(IP_TUNNEL_CSUM_BIT, o_flags))
  57                 addend += 4;
  58         if (test_bit(IP_TUNNEL_KEY_BIT, o_flags))
  59                 addend += 4;
  60         if (test_bit(IP_TUNNEL_SEQ_BIT, o_flags))
  61                 addend += 4;
  62         return addend;
  63 }
  64
  65 static inline void gre_flags_to_tnl_flags(unsigned long *dst, __be16 flags)
  66 {
  67         IP_TUNNEL_DECLARE_FLAGS(res) = { };
  68
  69         __assign_bit(IP_TUNNEL_CSUM_BIT, res, flags & GRE_CSUM);
  70         __assign_bit(IP_TUNNEL_ROUTING_BIT, res, flags & GRE_ROUTING);
  71         __assign_bit(IP_TUNNEL_KEY_BIT, res, flags & GRE_KEY);
  72         __assign_bit(IP_TUNNEL_SEQ_BIT, res, flags & GRE_SEQ);
  73         __assign_bit(IP_TUNNEL_STRICT_BIT, res, flags & GRE_STRICT);
  74         __assign_bit(IP_TUNNEL_REC_BIT, res, flags & GRE_REC);
  75         __assign_bit(IP_TUNNEL_VERSION_BIT, res, flags & GRE_VERSION);
  76
  77         ip_tunnel_flags_copy(dst, res);
  78 }
  79
  80 static inline __be16 gre_tnl_flags_to_gre_flags(const unsigned long *tflags)
  81 {
  82         __be16 flags = 0;
  83
  84         if (test_bit(IP_TUNNEL_CSUM_BIT, tflags))
  85                 flags |= GRE_CSUM;
  86         if (test_bit(IP_TUNNEL_ROUTING_BIT, tflags))
  87                 flags |= GRE_ROUTING;
  88         if (test_bit(IP_TUNNEL_KEY_BIT, tflags))
  89                 flags |= GRE_KEY;
  90         if (test_bit(IP_TUNNEL_SEQ_BIT, tflags))
  91                 flags |= GRE_SEQ;
  92         if (test_bit(IP_TUNNEL_STRICT_BIT, tflags))
  93                 flags |= GRE_STRICT;
  94         if (test_bit(IP_TUNNEL_REC_BIT, tflags))
  95                 flags |= GRE_REC;
  96         if (test_bit(IP_TUNNEL_VERSION_BIT, tflags))
  97                 flags |= GRE_VERSION;
  98
  99         return flags;
 100 }
 101
 102 static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
 103                                     const unsigned long *flags, __be16 proto,
 104                                     __be32 key, __be32 seq)
 105 {
 106         IP_TUNNEL_DECLARE_FLAGS(cond) = { };
 107         struct gre_base_hdr *greh;
 108
 109         skb_push(skb, hdr_len);
 110
 111         skb_set_inner_protocol(skb, proto);
 112         skb_reset_transport_header(skb);
 113         greh = (struct gre_base_hdr *)skb->data;
 114         greh->flags = gre_tnl_flags_to_gre_flags(flags);
 115         greh->protocol = proto;
 116
 117         __set_bit(IP_TUNNEL_KEY_BIT, cond);
 118         __set_bit(IP_TUNNEL_CSUM_BIT, cond);
 119         __set_bit(IP_TUNNEL_SEQ_BIT, cond);
 120
 121         if (ip_tunnel_flags_intersect(flags, cond)) {
 122                 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
 123
 124                 if (test_bit(IP_TUNNEL_SEQ_BIT, flags)) {
 125                         *ptr = seq;
 126                         ptr--;
 127                 }
 128                 if (test_bit(IP_TUNNEL_KEY_BIT, flags)) {
 129                         *ptr = key;
 130                         ptr--;
 131                 }
 132                 if (test_bit(IP_TUNNEL_CSUM_BIT, flags) &&
 133                     !(skb_shinfo(skb)->gso_type &
 134                       (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
 135                         *ptr = 0;
 136                         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 137                                 *(__sum16 *)ptr = csum_fold(lco_csum(skb));
 138                         } else {
 139                                 skb->ip_summed = CHECKSUM_PARTIAL;
 140                                 skb->csum_start = skb_transport_header(skb) - skb->head;
 141                                 skb->csum_offset = sizeof(*greh);
 142                         }
 143                 }
 144         }
 145 }
 146
 147 #endif