include/linux/can/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
  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 */