1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | |
3 | #ifndef _NET_GSO_H |
4 | #define _NET_GSO_H |
5 | |
6 | #include <linux/skbuff.h> |
7 | |
8 | /* Keeps track of mac header offset relative to skb->head. |
9 | * It is useful for TSO of Tunneling protocol. e.g. GRE. |
10 | * For non-tunnel skb it points to skb_mac_header() and for |
11 | * tunnel skb it points to outer mac header. |
12 | * Keeps track of level of encapsulation of network headers. |
13 | */ |
14 | struct skb_gso_cb { |
15 | union { |
16 | int mac_offset; |
17 | int data_offset; |
18 | }; |
19 | int encap_level; |
20 | __wsum csum; |
21 | __u16 csum_start; |
22 | }; |
23 | #define SKB_GSO_CB_OFFSET 32 |
24 | #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET)) |
25 | |
26 | static inline int (const struct sk_buff *inner_skb) |
27 | { |
28 | return (skb_mac_header(skb: inner_skb) - inner_skb->head) - |
29 | SKB_GSO_CB(inner_skb)->mac_offset; |
30 | } |
31 | |
32 | static inline int gso_pskb_expand_head(struct sk_buff *skb, int ) |
33 | { |
34 | int new_headroom, headroom; |
35 | int ret; |
36 | |
37 | headroom = skb_headroom(skb); |
38 | ret = pskb_expand_head(skb, nhead: extra, ntail: 0, GFP_ATOMIC); |
39 | if (ret) |
40 | return ret; |
41 | |
42 | new_headroom = skb_headroom(skb); |
43 | SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom); |
44 | return 0; |
45 | } |
46 | |
47 | static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res) |
48 | { |
49 | /* Do not update partial checksums if remote checksum is enabled. */ |
50 | if (skb->remcsum_offload) |
51 | return; |
52 | |
53 | SKB_GSO_CB(skb)->csum = res; |
54 | SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head; |
55 | } |
56 | |
57 | /* Compute the checksum for a gso segment. First compute the checksum value |
58 | * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and |
59 | * then add in skb->csum (checksum from csum_start to end of packet). |
60 | * skb->csum and csum_start are then updated to reflect the checksum of the |
61 | * resultant packet starting from the transport header-- the resultant checksum |
62 | * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo |
63 | * header. |
64 | */ |
65 | static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res) |
66 | { |
67 | unsigned char *csum_start = skb_transport_header(skb); |
68 | int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start; |
69 | __wsum partial = SKB_GSO_CB(skb)->csum; |
70 | |
71 | SKB_GSO_CB(skb)->csum = res; |
72 | SKB_GSO_CB(skb)->csum_start = csum_start - skb->head; |
73 | |
74 | return csum_fold(sum: csum_partial(buff: csum_start, len: plen, sum: partial)); |
75 | } |
76 | |
77 | struct sk_buff *__skb_gso_segment(struct sk_buff *skb, |
78 | netdev_features_t features, bool tx_path); |
79 | |
80 | static inline struct sk_buff *skb_gso_segment(struct sk_buff *skb, |
81 | netdev_features_t features) |
82 | { |
83 | return __skb_gso_segment(skb, features, tx_path: true); |
84 | } |
85 | |
86 | struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb, |
87 | netdev_features_t features, __be16 type); |
88 | |
89 | struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb, |
90 | netdev_features_t features); |
91 | |
92 | bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu); |
93 | |
94 | bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len); |
95 | |
96 | static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol, |
97 | int pulled_hlen, u16 mac_offset, |
98 | int mac_len) |
99 | { |
100 | skb->protocol = protocol; |
101 | skb->encapsulation = 1; |
102 | skb_push(skb, len: pulled_hlen); |
103 | skb_reset_transport_header(skb); |
104 | skb->mac_header = mac_offset; |
105 | skb->network_header = skb->mac_header + mac_len; |
106 | skb->mac_len = mac_len; |
107 | } |
108 | |
109 | #endif /* _NET_GSO_H */ |
110 | |