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 /* Number of IPv4/IPv6 GSO handler entries for this packet. */
23 u8 recursion_counter;
24 };
25 #define SKB_GSO_CB_OFFSET 32
26 #define SKB_GSO_CB(skb) ((struct skb_gso_cb *)((skb)->cb + SKB_GSO_CB_OFFSET))
27
gso_recursion_inc_test(struct sk_buff * skb,unsigned int limit)28 static inline bool gso_recursion_inc_test(struct sk_buff *skb,
29 unsigned int limit)
30 {
31 return ++SKB_GSO_CB(skb)->recursion_counter > limit;
32 }
33
skb_tnl_header_len(const struct sk_buff * inner_skb)34 static inline int skb_tnl_header_len(const struct sk_buff *inner_skb)
35 {
36 return (skb_mac_header(inner_skb) - inner_skb->head) -
37 SKB_GSO_CB(inner_skb)->mac_offset;
38 }
39
gso_pskb_expand_head(struct sk_buff * skb,int extra)40 static inline int gso_pskb_expand_head(struct sk_buff *skb, int extra)
41 {
42 int new_headroom, headroom;
43 int ret;
44
45 headroom = skb_headroom(skb);
46 ret = pskb_expand_head(skb, extra, 0, GFP_ATOMIC);
47 if (ret)
48 return ret;
49
50 new_headroom = skb_headroom(skb);
51 SKB_GSO_CB(skb)->mac_offset += (new_headroom - headroom);
52 return 0;
53 }
54
gso_reset_checksum(struct sk_buff * skb,__wsum res)55 static inline void gso_reset_checksum(struct sk_buff *skb, __wsum res)
56 {
57 /* Do not update partial checksums if remote checksum is enabled. */
58 if (skb->remcsum_offload)
59 return;
60
61 SKB_GSO_CB(skb)->csum = res;
62 SKB_GSO_CB(skb)->csum_start = skb_checksum_start(skb) - skb->head;
63 }
64
65 /* Compute the checksum for a gso segment. First compute the checksum value
66 * from the start of transport header to SKB_GSO_CB(skb)->csum_start, and
67 * then add in skb->csum (checksum from csum_start to end of packet).
68 * skb->csum and csum_start are then updated to reflect the checksum of the
69 * resultant packet starting from the transport header-- the resultant checksum
70 * is in the res argument (i.e. normally zero or ~ of checksum of a pseudo
71 * header.
72 */
gso_make_checksum(struct sk_buff * skb,__wsum res)73 static inline __sum16 gso_make_checksum(struct sk_buff *skb, __wsum res)
74 {
75 unsigned char *csum_start = skb_transport_header(skb);
76 int plen = (skb->head + SKB_GSO_CB(skb)->csum_start) - csum_start;
77 __wsum partial = SKB_GSO_CB(skb)->csum;
78
79 SKB_GSO_CB(skb)->csum = res;
80 SKB_GSO_CB(skb)->csum_start = csum_start - skb->head;
81
82 return csum_fold(csum_partial(csum_start, plen, partial));
83 }
84
85 struct sk_buff *__skb_gso_segment(struct sk_buff *skb,
86 netdev_features_t features, bool tx_path);
87
skb_gso_segment(struct sk_buff * skb,netdev_features_t features)88 static inline struct sk_buff *skb_gso_segment(struct sk_buff *skb,
89 netdev_features_t features)
90 {
91 return __skb_gso_segment(skb, features, true);
92 }
93
94 struct sk_buff *skb_eth_gso_segment(struct sk_buff *skb,
95 netdev_features_t features, __be16 type);
96
97 struct sk_buff *skb_mac_gso_segment(struct sk_buff *skb,
98 netdev_features_t features);
99
100 bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu);
101
102 bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
103
skb_gso_error_unwind(struct sk_buff * skb,__be16 protocol,int pulled_hlen,u16 mac_offset,int mac_len)104 static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,
105 int pulled_hlen, u16 mac_offset,
106 int mac_len)
107 {
108 skb->protocol = protocol;
109 skb->encapsulation = 1;
110 skb_push(skb, pulled_hlen);
111 skb_reset_transport_header(skb);
112 skb->mac_header = mac_offset;
113 skb->network_header = skb->mac_header + mac_len;
114 skb->mac_len = mac_len;
115 }
116
117 #endif /* _NET_GSO_H */
118