1 /* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
2 /*
3 * linux/can/skb.h
4 *
5 * Definitions for the CAN network socket buffer
6 *
7 * Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
8 *
9 */
10
11 #ifndef _CAN_SKB_H
12 #define _CAN_SKB_H
13
14 #include <linux/types.h>
15 #include <linux/skbuff.h>
16 #include <linux/can.h>
17 #include <net/sock.h>
18
19 void can_flush_echo_skb(struct net_device *dev);
20 int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
21 unsigned int idx, unsigned int frame_len);
22 struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
23 unsigned int *len_ptr,
24 unsigned int *frame_len_ptr);
25 unsigned int __must_check can_get_echo_skb(struct net_device *dev,
26 unsigned int idx,
27 unsigned int *frame_len_ptr);
28 void can_free_echo_skb(struct net_device *dev, unsigned int idx,
29 unsigned int *frame_len_ptr);
30 struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
31 struct sk_buff *alloc_canfd_skb(struct net_device *dev,
32 struct canfd_frame **cfd);
33 struct sk_buff *alloc_canxl_skb(struct net_device *dev,
34 struct canxl_frame **cxl,
35 unsigned int data_len);
36 struct sk_buff *alloc_can_err_skb(struct net_device *dev,
37 struct can_frame **cf);
38 bool can_dropped_invalid_skb(struct net_device *dev, struct sk_buff *skb);
39
40 /*
41 * The struct can_skb_priv is used to transport additional information along
42 * with the stored struct can(fd)_frame that can not be contained in existing
43 * struct sk_buff elements.
44 * N.B. that this information must not be modified in cloned CAN sk_buffs.
45 * To modify the CAN frame content or the struct can_skb_priv content
46 * skb_copy() needs to be used instead of skb_clone().
47 */
48
49 /**
50 * struct can_skb_priv - private additional data inside CAN sk_buffs
51 * @ifindex: ifindex of the first interface the CAN frame appeared on
52 * @skbcnt: atomic counter to have an unique id together with skb pointer
53 * @frame_len: length of CAN frame in data link layer
54 * @cf: align to the following CAN frame at skb->data
55 */
56 struct can_skb_priv {
57 int ifindex;
58 int skbcnt;
59 unsigned int frame_len;
60 struct can_frame cf[];
61 };
62
63 static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
64 {
65 return (struct can_skb_priv *)(skb->head);
66 }
67
68 static inline void can_skb_reserve(struct sk_buff *skb)
69 {
70 skb_reserve(skb, sizeof(struct can_skb_priv));
71 }
72
73 static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
74 {
75 /* If the socket has already been closed by user space, the
76 * refcount may already be 0 (and the socket will be freed
77 * after the last TX skb has been freed). So only increase
78 * socket refcount if the refcount is > 0.
79 */
80 if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
81 skb->destructor = sock_efree;
82 skb->sk = sk;
83 }
84 }
85
86 /*
87 * returns an unshared skb owned by the original sock to be echo'ed back
88 */
89 static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
90 {
91 struct sk_buff *nskb;
92
93 nskb = skb_clone(skb, GFP_ATOMIC);
94 if (unlikely(!nskb)) {
95 kfree_skb(skb);
96 return NULL;
97 }
98
99 can_skb_set_owner(nskb, skb->sk);
100 consume_skb(skb);
101 return nskb;
102 }
103
104 static inline bool can_is_can_skb(const struct sk_buff *skb)
105 {
106 struct can_frame *cf = (struct can_frame *)skb->data;
107
108 /* the CAN specific type of skb is identified by its data length */
109 return (skb->len == CAN_MTU && cf->len <= CAN_MAX_DLEN);
110 }
111
112 static inline bool can_is_canfd_skb(const struct sk_buff *skb)
113 {
114 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
115
116 /* the CAN specific type of skb is identified by its data length */
117 return (skb->len == CANFD_MTU && cfd->len <= CANFD_MAX_DLEN);
118 }
119
120 static inline bool can_is_canxl_skb(const struct sk_buff *skb)
121 {
122 const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
123
124 if (skb->len < CANXL_HDR_SIZE + CANXL_MIN_DLEN || skb->len > CANXL_MTU)
125 return false;
126
127 /* this also checks valid CAN XL data length boundaries */
128 if (skb->len != CANXL_HDR_SIZE + cxl->len)
129 return false;
130
131 return cxl->flags & CANXL_XLF;
132 }
133
134 /* get length element value from can[|fd|xl]_frame structure */
135 static inline unsigned int can_skb_get_len_val(struct sk_buff *skb)
136 {
137 const struct canxl_frame *cxl = (struct canxl_frame *)skb->data;
138 const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
139
140 if (can_is_canxl_skb(skb))
141 return cxl->len;
142
143 return cfd->len;
144 }
145
146 /* get needed data length inside CAN frame for all frame types (RTR aware) */
147 static inline unsigned int can_skb_get_data_len(struct sk_buff *skb)
148 {
149 unsigned int len = can_skb_get_len_val(skb);
150 const struct can_frame *cf = (struct can_frame *)skb->data;
151
152 /* RTR frames have an actual length of zero */
153 if (can_is_can_skb(skb) && cf->can_id & CAN_RTR_FLAG)
154 return 0;
155
156 return len;
157 }
158
159 #endif /* !_CAN_SKB_H */
160
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