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 int gre_calc_hlen(__be16 o_flags) 41 { 42 int addend = 4; 43 44 if (o_flags & TUNNEL_CSUM) 45 addend += 4; 46 if (o_flags & TUNNEL_KEY) 47 addend += 4; 48 if (o_flags & TUNNEL_SEQ) 49 addend += 4; 50 return addend; 51 } 52 53 static inline __be16 gre_flags_to_tnl_flags(__be16 flags) 54 { 55 __be16 tflags = 0; 56 57 if (flags & GRE_CSUM) 58 tflags |= TUNNEL_CSUM; 59 if (flags & GRE_ROUTING) 60 tflags |= TUNNEL_ROUTING; 61 if (flags & GRE_KEY) 62 tflags |= TUNNEL_KEY; 63 if (flags & GRE_SEQ) 64 tflags |= TUNNEL_SEQ; 65 if (flags & GRE_STRICT) 66 tflags |= TUNNEL_STRICT; 67 if (flags & GRE_REC) 68 tflags |= TUNNEL_REC; 69 if (flags & GRE_VERSION) 70 tflags |= TUNNEL_VERSION; 71 72 return tflags; 73 } 74 75 static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags) 76 { 77 __be16 flags = 0; 78 79 if (tflags & TUNNEL_CSUM) 80 flags |= GRE_CSUM; 81 if (tflags & TUNNEL_ROUTING) 82 flags |= GRE_ROUTING; 83 if (tflags & TUNNEL_KEY) 84 flags |= GRE_KEY; 85 if (tflags & TUNNEL_SEQ) 86 flags |= GRE_SEQ; 87 if (tflags & TUNNEL_STRICT) 88 flags |= GRE_STRICT; 89 if (tflags & TUNNEL_REC) 90 flags |= GRE_REC; 91 if (tflags & TUNNEL_VERSION) 92 flags |= GRE_VERSION; 93 94 return flags; 95 } 96 97 static inline __sum16 gre_checksum(struct sk_buff *skb) 98 { 99 __wsum csum; 100 101 if (skb->ip_summed == CHECKSUM_PARTIAL) 102 csum = lco_csum(skb); 103 else 104 csum = skb_checksum(skb, 0, skb->len, 0); 105 return csum_fold(csum); 106 } 107 108 static inline void gre_build_header(struct sk_buff *skb, int hdr_len, 109 __be16 flags, __be16 proto, 110 __be32 key, __be32 seq) 111 { 112 struct gre_base_hdr *greh; 113 114 skb_push(skb, hdr_len); 115 116 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; 121 122 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) { 123 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); 124 125 if (flags & TUNNEL_SEQ) { 126 *ptr = seq; 127 ptr--; 128 } 129 if (flags & TUNNEL_KEY) { 130 *ptr = key; 131 ptr--; 132 } 133 if (flags & TUNNEL_CSUM && 134 !(skb_shinfo(skb)->gso_type & 135 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) { 136 *ptr = 0; 137 *(__sum16 *)ptr = gre_checksum(skb); 138 } 139 } 140 } 141 142 #endif 143