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 155