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/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _NET_GSO_H
#define _NET_GSO_H
#include <linux/skbuff.h>
/* Keeps track of mac header offset relative to skb->head.
* It is useful for TSO of Tunneling protocol. e.g. GRE.
* For non-tunnel skb it points to skb_mac_header() and for
* tunnel skb it points to outer mac header.
* Keeps track of level of encapsulation of network headers.
*/
struct skb_gso_cb {
union {
int mac_offset;
int data_offset;
};
int encap_level;
__wsum csum;
__u16 csum_start;
};
#define SKB_GSO_CB_OFFSET 32
#define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET))
static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
{
return (skb_mac_header(inner_skb) - inner_skb->head) -
SKB_GSO_CB(inner_skb)->mac_offset;
}
static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
{
int new_headroom, headroom;
int ret;
headroom = skb_headroom(skb);
ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
if (ret)
return ret;
new_headroom = skb_headroom(skb);
SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
return 0;
}
static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
{
/* Do not update partial checksums if remote checksum is enabled. */
if (skb->remcsum_offload)
return;
SKB_GSO_CB(skb)->csum = res;
SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
}
/* Compute the checksum for a gso segment. First compute the checksum value
* from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
* then add in skb->csum (checksum from csum_start to end of packet).
* skb->csum and csum_start are then updated to reflect the checksum of the
* resultant packet starting from the transport header-- the resultant checksum
* is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
* header.
*/
static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
{
unsigned char *csum_start = skb_transport_header(skb);
int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
__wsum partial = SKB_GSO_CB(skb)->csum;
SKB_GSO_CB(skb)->csum = res;
SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
return csum_fold(csum_partial(csum_start, plen, partial));
}
struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
netdev_features_t features, bool tx_path);
static inline struct sk_buff *skb_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
return __skb_gso_segment(skb, features, true);
}
struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
netdev_features_t features, __be16 type);
struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
netdev_features_t features);
bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu);
bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,
int pulled_hlen, u16 mac_offset,
int mac_len)
{
skb->protocol = protocol;
skb->encapsulation = 1;
skb_push(skb, pulled_hlen);
skb_reset_transport_header(skb);
skb->mac_header = mac_offset;
skb->network_header = skb->mac_header + mac_len;
skb->mac_len = mac_len;
}
#endif /* _NET_GSO_H */
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