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 int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, 36 bool *csum_err, __be16 proto, int nhs); 37 38 static inline bool netif_is_gretap(const struct net_device *dev) 39 { 40 return dev->rtnl_link_ops && 41 !strcmp(dev->rtnl_link_ops->kind, "gretap"); 42 } 43 44 static inline bool netif_is_ip6gretap(const struct net_device *dev) 45 { 46 return dev->rtnl_link_ops && 47 !strcmp(dev->rtnl_link_ops->kind, "ip6gretap"); 48 } 49 50 static inline int gre_calc_hlen(const unsigned long *o_flags) 51 { 52 int addend = 4; 53 54 if (test_bit(IP_TUNNEL_CSUM_BIT, o_flags)) 55 addend += 4; 56 if (test_bit(IP_TUNNEL_KEY_BIT, o_flags)) 57 addend += 4; 58 if (test_bit(IP_TUNNEL_SEQ_BIT, o_flags)) 59 addend += 4; 60 return addend; 61 } 62 63 static inline void gre_flags_to_tnl_flags(unsigned long *dst, __be16 flags) 64 { 65 IP_TUNNEL_DECLARE_FLAGS(res) = { }; 66 67 __assign_bit(IP_TUNNEL_CSUM_BIT, res, flags & GRE_CSUM); 68 __assign_bit(IP_TUNNEL_ROUTING_BIT, res, flags & GRE_ROUTING); 69 __assign_bit(IP_TUNNEL_KEY_BIT, res, flags & GRE_KEY); 70 __assign_bit(IP_TUNNEL_SEQ_BIT, res, flags & GRE_SEQ); 71 __assign_bit(IP_TUNNEL_STRICT_BIT, res, flags & GRE_STRICT); 72 __assign_bit(IP_TUNNEL_REC_BIT, res, flags & GRE_REC); 73 __assign_bit(IP_TUNNEL_VERSION_BIT, res, flags & GRE_VERSION); 74 75 ip_tunnel_flags_copy(dst, res); 76 } 77 78 static inline __be16 gre_tnl_flags_to_gre_flags(const unsigned long *tflags) 79 { 80 __be16 flags = 0; 81 82 if (test_bit(IP_TUNNEL_CSUM_BIT, tflags)) 83 flags |= GRE_CSUM; 84 if (test_bit(IP_TUNNEL_ROUTING_BIT, tflags)) 85 flags |= GRE_ROUTING; 86 if (test_bit(IP_TUNNEL_KEY_BIT, tflags)) 87 flags |= GRE_KEY; 88 if (test_bit(IP_TUNNEL_SEQ_BIT, tflags)) 89 flags |= GRE_SEQ; 90 if (test_bit(IP_TUNNEL_STRICT_BIT, tflags)) 91 flags |= GRE_STRICT; 92 if (test_bit(IP_TUNNEL_REC_BIT, tflags)) 93 flags |= GRE_REC; 94 if (test_bit(IP_TUNNEL_VERSION_BIT, tflags)) 95 flags |= GRE_VERSION; 96 97 return flags; 98 } 99 100 static inline void gre_build_header(struct sk_buff *skb, int hdr_len, 101 const unsigned long *flags, __be16 proto, 102 __be32 key, __be32 seq) 103 { 104 IP_TUNNEL_DECLARE_FLAGS(cond) = { }; 105 struct gre_base_hdr *greh; 106 107 skb_push(skb, hdr_len); 108 109 skb_set_inner_protocol(skb, proto); 110 skb_reset_transport_header(skb); 111 greh = (struct gre_base_hdr *)skb->data; 112 greh->flags = gre_tnl_flags_to_gre_flags(flags); 113 greh->protocol = proto; 114 115 __set_bit(IP_TUNNEL_KEY_BIT, cond); 116 __set_bit(IP_TUNNEL_CSUM_BIT, cond); 117 __set_bit(IP_TUNNEL_SEQ_BIT, cond); 118 119 if (ip_tunnel_flags_intersect(flags, cond)) { 120 __be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4); 121 122 if (test_bit(IP_TUNNEL_SEQ_BIT, flags)) { 123 *ptr = seq; 124 ptr--; 125 } 126 if (test_bit(IP_TUNNEL_KEY_BIT, flags)) { 127 *ptr = key; 128 ptr--; 129 } 130 if (test_bit(IP_TUNNEL_CSUM_BIT, flags) && 131 !(skb_shinfo(skb)->gso_type & 132 (SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) { 133 *ptr = 0; 134 if (skb->ip_summed == CHECKSUM_PARTIAL) { 135 *(__sum16 *)ptr = csum_fold(lco_csum(skb)); 136 } else { 137 skb->ip_summed = CHECKSUM_PARTIAL; 138 skb->csum_start = skb_transport_header(skb) - skb->head; 139 skb->csum_offset = sizeof(*greh); 140 } 141 } 142 } 143 } 144 145 #endif 146