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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_GRE_H
#define __LINUX_GRE_H
#include <linux/skbuff.h>
#include <net/ip_tunnels.h>
struct gre_base_hdr {
__be16 flags;
__be16 protocol;
} __packed;
struct gre_full_hdr {
struct gre_base_hdr fixed_header;
__be16 csum;
__be16 reserved1;
__be32 key;
__be32 seq;
} __packed;
#define GRE_HEADER_SECTION 4
#define GREPROTO_CISCO 0
#define GREPROTO_PPTP 1
#define GREPROTO_MAX 2
#define GRE_IP_PROTO_MAX 2
struct gre_protocol {
int (*handler)(struct sk_buff *skb);
void (*err_handler)(struct sk_buff *skb, u32 info);
};
int gre_add_protocol(const struct gre_protocol *proto, u8 version);
int gre_del_protocol(const struct gre_protocol *proto, u8 version);
struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
u8 name_assign_type);
int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
bool *csum_err, __be16 proto, int nhs);
static inline bool netif_is_gretap(const struct net_device *dev)
{
return dev->rtnl_link_ops &&
!strcmp(dev->rtnl_link_ops->kind, "gretap");
}
static inline bool netif_is_ip6gretap(const struct net_device *dev)
{
return dev->rtnl_link_ops &&
!strcmp(dev->rtnl_link_ops->kind, "ip6gretap");
}
static inline int gre_calc_hlen(const unsigned long *o_flags)
{
int addend = 4;
if (test_bit(IP_TUNNEL_CSUM_BIT, o_flags))
addend += 4;
if (test_bit(IP_TUNNEL_KEY_BIT, o_flags))
addend += 4;
if (test_bit(IP_TUNNEL_SEQ_BIT, o_flags))
addend += 4;
return addend;
}
static inline void gre_flags_to_tnl_flags(unsigned long *dst, __be16 flags)
{
IP_TUNNEL_DECLARE_FLAGS(res) = { };
__assign_bit(IP_TUNNEL_CSUM_BIT, res, flags & GRE_CSUM);
__assign_bit(IP_TUNNEL_ROUTING_BIT, res, flags & GRE_ROUTING);
__assign_bit(IP_TUNNEL_KEY_BIT, res, flags & GRE_KEY);
__assign_bit(IP_TUNNEL_SEQ_BIT, res, flags & GRE_SEQ);
__assign_bit(IP_TUNNEL_STRICT_BIT, res, flags & GRE_STRICT);
__assign_bit(IP_TUNNEL_REC_BIT, res, flags & GRE_REC);
__assign_bit(IP_TUNNEL_VERSION_BIT, res, flags & GRE_VERSION);
ip_tunnel_flags_copy(dst, res);
}
static inline __be16 gre_tnl_flags_to_gre_flags(const unsigned long *tflags)
{
__be16 flags = 0;
if (test_bit(IP_TUNNEL_CSUM_BIT, tflags))
flags |= GRE_CSUM;
if (test_bit(IP_TUNNEL_ROUTING_BIT, tflags))
flags |= GRE_ROUTING;
if (test_bit(IP_TUNNEL_KEY_BIT, tflags))
flags |= GRE_KEY;
if (test_bit(IP_TUNNEL_SEQ_BIT, tflags))
flags |= GRE_SEQ;
if (test_bit(IP_TUNNEL_STRICT_BIT, tflags))
flags |= GRE_STRICT;
if (test_bit(IP_TUNNEL_REC_BIT, tflags))
flags |= GRE_REC;
if (test_bit(IP_TUNNEL_VERSION_BIT, tflags))
flags |= GRE_VERSION;
return flags;
}
static inline void gre_build_header(struct sk_buff *skb, int hdr_len,
const unsigned long *flags, __be16 proto,
__be32 key, __be32 seq)
{
IP_TUNNEL_DECLARE_FLAGS(cond) = { };
struct gre_base_hdr *greh;
skb_push(skb, hdr_len);
skb_set_inner_protocol(skb, proto);
skb_reset_transport_header(skb);
greh = (struct gre_base_hdr *)skb->data;
greh->flags = gre_tnl_flags_to_gre_flags(flags);
greh->protocol = proto;
__set_bit(IP_TUNNEL_KEY_BIT, cond);
__set_bit(IP_TUNNEL_CSUM_BIT, cond);
__set_bit(IP_TUNNEL_SEQ_BIT, cond);
if (ip_tunnel_flags_intersect(flags, cond)) {
__be32 *ptr = (__be32 *)(((u8 *)greh) + hdr_len - 4);
if (test_bit(IP_TUNNEL_SEQ_BIT, flags)) {
*ptr = seq;
ptr--;
}
if (test_bit(IP_TUNNEL_KEY_BIT, flags)) {
*ptr = key;
ptr--;
}
if (test_bit(IP_TUNNEL_CSUM_BIT, flags) &&
!(skb_shinfo(skb)->gso_type &
(SKB_GSO_GRE | SKB_GSO_GRE_CSUM))) {
*ptr = 0;
if (skb->ip_summed == CHECKSUM_PARTIAL) {
*(__sum16 *)ptr = csum_fold(lco_csum(skb));
} else {
skb->ip_summed = CHECKSUM_PARTIAL;
skb->csum_start = skb_transport_header(skb) - skb->head;
skb->csum_offset = sizeof(*greh);
}
}
}
}
#endif
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