skb.h

  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
 19void can_flush_echo_skb(struct net_device *dev);
 20int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
 21		     unsigned int idx, unsigned int frame_len);
 22struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
 23				   unsigned int *len_ptr,
 24				   unsigned int *frame_len_ptr);
 25unsigned int __must_check can_get_echo_skb(struct net_device *dev,
 26					   unsigned int idx,
 27					   unsigned int *frame_len_ptr);
 28void can_free_echo_skb(struct net_device *dev, unsigned int idx,
 29		       unsigned int *frame_len_ptr);
 30struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
 31struct sk_buff *alloc_canfd_skb(struct net_device *dev,
 32				struct canfd_frame **cfd);
 33struct sk_buff *alloc_canxl_skb(struct net_device *dev,
 34				struct canxl_frame **cxl,
 35				unsigned int data_len);
 36struct sk_buff *alloc_can_err_skb(struct net_device *dev,
 37				  struct can_frame **cf);
 38bool 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 */
 56struct can_skb_priv {
 57	int ifindex;
 58	int skbcnt;
 59	unsigned int frame_len;
 60	struct can_frame cf[];
 61};
 62
 63static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
 64{
 65	return (struct can_skb_priv *)(skb->head);
 66}
 67
 68static inline void can_skb_reserve(struct sk_buff *skb)
 69{
 70	skb_reserve(skb, sizeof(struct can_skb_priv));
 71}
 72
 73static 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 */
 89static 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
104static 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
112static 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
120static 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 */
135static 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) */
147static 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 */