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 146