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
netif_is_gretap(const struct net_device * dev)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
netif_is_ip6gretap(const struct net_device * dev)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
gre_calc_hlen(const unsigned long * o_flags)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
gre_flags_to_tnl_flags(unsigned long * dst,__be16 flags)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
gre_tnl_flags_to_gre_flags(const unsigned long * tflags)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
gre_build_header(struct sk_buff * skb,int hdr_len,const unsigned long * flags,__be16 proto,__be32 key,__be32 seq)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