1 #ifndef __LINUX_GRE_H 2 #define __LINUX_GRE_H 3 4 #include <linux/skbuff.h> 5 #include <net/ip_tunnels.h> 6 7 struct gre_base_hdr { 8 __be16 flags; 9 __be16 protocol; 10 } __packed; 11 12 struct gre_full_hdr { 13 struct gre_base_hdr fixed_header; 14 __be16 csum; 15 __be16 reserved1; 16 __be32 key; 17 __be32 seq; 18 } __packed; 19 #define GRE_HEADER_SECTION 4 20 21 #define GREPROTO_CISCO 0 22 #define GREPROTO_PPTP 1 23 #define GREPROTO_MAX 2 24 #define GRE_IP_PROTO_MAX 2 25 26 struct gre_protocol { 27 int (*handler)(struct sk_buff *skb); 28 void (*err_handler)(struct sk_buff *skb, u32 info); 29 }; 30 31 int gre_add_protocol(const struct gre_protocol *proto, u8 version); 32 int gre_del_protocol(const struct gre_protocol *proto, u8 version); 33 34 struct net_device *gretap_fb_dev_create(struct net *net, const char *name, 35 u8 name_assign_type); 36 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, 37 bool *csum_err, __be16 proto, int nhs); 38 39 static inline int gre_calc_hlen(__be16 o_flags) 40 { 41 int addend = 4; 42 43 if (o_flags & TUNNEL_CSUM) 44 addend += 4; 45 if (o_flags & TUNNEL_KEY) 46 addend += 4; 47 if (o_flags & TUNNEL_SEQ) 48 addend += 4; 49 return addend; 50 } 51 52 static inline __be16 gre_flags_to_tnl_flags(__be16 flags) 53 { 54 __be16 tflags = 0; 55 56 if (flags & GRE_CSUM) 57 tflags |= TUNNEL_CSUM; 58 if (flags & GRE_ROUTING) 59 tflags |= TUNNEL_ROUTING; 60 if (flags & GRE_KEY) 61 tflags |= TUNNEL_KEY; 62 if (flags & GRE_SEQ) 63 tflags |= TUNNEL_SEQ; 64 if (flags & GRE_STRICT) 65 tflags |= TUNNEL_STRICT; 66 if (flags & GRE_REC) 67 tflags |= TUNNEL_REC; 68 if (flags & GRE_VERSION) 69 tflags |= TUNNEL_VERSION; 70 71 return tflags; 72 } 73 74 static inline __be16 gre_tnl_flags_to_gre_flags(__be16 tflags) 75 { 76 __be16 flags = 0; 77 78 if (tflags & TUNNEL_CSUM) 79 flags |= GRE_CSUM; 80 if (tflags & TUNNEL_ROUTING) 81 flags |= GRE_ROUTING; 82 if (tflags & TUNNEL_KEY) 83 flags |= GRE_KEY; 84 if (tflags & TUNNEL_SEQ) 85 flags |= GRE_SEQ; 86 if (tflags & TUNNEL_STRICT) 87 flags |= GRE_STRICT; 88 if (tflags & TUNNEL_REC) 89 flags |= GRE_REC; 90 if (tflags & TUNNEL_VERSION) 91 flags |= GRE_VERSION; 92 93 return flags; 94 } 95 96 static inline __sum16 gre_checksum(struct sk_buff *skb) 97 { 98 __wsum csum; 99 100 if (skb->ip_summed == CHECKSUM_PARTIAL) 101 csum = lco_csum(skb); 102 else 103 csum = skb_checksum(skb, 0, skb->len, 0); 104 return csum_fold(csum); 105 } 106 107 static inline void gre_build_header(struct sk_buff *skb, int hdr_len, 108 __be16 flags, __be16 proto, 109 __be32 key, __be32 seq) 110 { 111 struct gre_base_hdr *greh; 112 113 skb_push(skb, hdr_len); 114 115 skb_set_inner_protocol(skb, proto); 116 skb_reset_transport_header(skb); 117 greh = (struct gre_base_hdr *)skb->data; 118 greh->flags = gre_tnl_flags_to_gre_flags(flags); 119 greh->protocol = proto; 120 121 if (flags & (TUNNEL_KEY | TUNNEL_CSUM | TUNNEL_SEQ)) { 122 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); 123 124 if (flags & TUNNEL_SEQ) { 125 *ptr = seq; 126 ptr--; 127 } 128 if (flags & TUNNEL_KEY) { 129 *ptr = key; 130 ptr--; 131 } 132 if (flags & TUNNEL_CSUM && 133 !(skb_shinfo(skb)->gso_type & 134 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) { 135 *ptr = 0; 136 *(__sum16 *)ptr = gre_checksum(skb); 137 } 138 } 139 } 140 141 #endif 142