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/* SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause) */
/*
* linux/can/skb.h
*
* Definitions for the CAN network socket buffer
*
* Copyright (C) 2012 Oliver Hartkopp <socketcan@hartkopp.net>
*
*/
#ifndef _CAN_SKB_H
#define _CAN_SKB_H
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/can.h>
#include <net/sock.h>
void can_flush_echo_skb(struct net_device *dev);
int can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
unsigned int idx, unsigned int frame_len);
struct sk_buff *__can_get_echo_skb(struct net_device *dev, unsigned int idx,
u8 *len_ptr, unsigned int *frame_len_ptr);
unsigned int __must_check can_get_echo_skb(struct net_device *dev,
unsigned int idx,
unsigned int *frame_len_ptr);
void can_free_echo_skb(struct net_device *dev, unsigned int idx,
unsigned int *frame_len_ptr);
struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
struct sk_buff *alloc_canfd_skb(struct net_device *dev,
struct canfd_frame **cfd);
struct sk_buff *alloc_can_err_skb(struct net_device *dev,
struct can_frame **cf);
/*
* The struct can_skb_priv is used to transport additional information along
* with the stored struct can(fd)_frame that can not be contained in existing
* struct sk_buff elements.
* N.B. that this information must not be modified in cloned CAN sk_buffs.
* To modify the CAN frame content or the struct can_skb_priv content
* skb_copy() needs to be used instead of skb_clone().
*/
/**
* struct can_skb_priv - private additional data inside CAN sk_buffs
* @ifindex: ifindex of the first interface the CAN frame appeared on
* @skbcnt: atomic counter to have an unique id together with skb pointer
* @frame_len: length of CAN frame in data link layer
* @cf: align to the following CAN frame at skb->data
*/
struct can_skb_priv {
int ifindex;
int skbcnt;
unsigned int frame_len;
struct can_frame cf[];
};
static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
{
return (struct can_skb_priv *)(skb->head);
}
static inline void can_skb_reserve(struct sk_buff *skb)
{
skb_reserve(skb, sizeof(struct can_skb_priv));
}
static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
{
/* If the socket has already been closed by user space, the
* refcount may already be 0 (and the socket will be freed
* after the last TX skb has been freed). So only increase
* socket refcount if the refcount is > 0.
*/
if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
skb->destructor = sock_efree;
skb->sk = sk;
}
}
/*
* returns an unshared skb owned by the original sock to be echo'ed back
*/
static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
{
struct sk_buff *nskb;
nskb = skb_clone(skb, GFP_ATOMIC);
if (unlikely(!nskb)) {
kfree_skb(skb);
return NULL;
}
can_skb_set_owner(nskb, skb->sk);
consume_skb(skb);
return nskb;
}
/* Check for outgoing skbs that have not been created by the CAN subsystem */
static inline bool can_skb_headroom_valid(struct net_device *dev,
struct sk_buff *skb)
{
/* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
return false;
/* af_packet does not apply CAN skb specific settings */
if (skb->ip_summed == CHECKSUM_NONE) {
/* init headroom */
can_skb_prv(skb)->ifindex = dev->ifindex;
can_skb_prv(skb)->skbcnt = 0;
skb->ip_summed = CHECKSUM_UNNECESSARY;
/* perform proper loopback on capable devices */
if (dev->flags & IFF_ECHO)
skb->pkt_type = PACKET_LOOPBACK;
else
skb->pkt_type = PACKET_HOST;
skb_reset_mac_header(skb);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
}
return true;
}
/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
static inline bool can_dropped_invalid_skb(struct net_device *dev,
struct sk_buff *skb)
{
const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
if (skb->protocol == htons(ETH_P_CAN)) {
if (unlikely(skb->len != CAN_MTU ||
cfd->len > CAN_MAX_DLEN))
goto inval_skb;
} else if (skb->protocol == htons(ETH_P_CANFD)) {
if (unlikely(skb->len != CANFD_MTU ||
cfd->len > CANFD_MAX_DLEN))
goto inval_skb;
} else
goto inval_skb;
if (!can_skb_headroom_valid(dev, skb))
goto inval_skb;
return false;
inval_skb:
kfree_skb(skb);
dev->stats.tx_dropped++;
return true;
}
static inline bool can_is_canfd_skb(const struct sk_buff *skb)
{
/* the CAN specific type of skb is identified by its data length */
return skb->len == CANFD_MTU;
}
#endif /* !_CAN_SKB_H */
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