tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 u8 *len_ptr, unsigned int *frame_len_ptr);
24unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx,
25 unsigned int *frame_len_ptr);
26void can_free_echo_skb(struct net_device *dev, unsigned int idx);
27struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
28struct sk_buff *alloc_canfd_skb(struct net_device *dev,
29 struct canfd_frame **cfd);
30struct sk_buff *alloc_can_err_skb(struct net_device *dev,
31 struct can_frame **cf);
32
33/*
34 * The struct can_skb_priv is used to transport additional information along
35 * with the stored struct can(fd)_frame that can not be contained in existing
36 * struct sk_buff elements.
37 * N.B. that this information must not be modified in cloned CAN sk_buffs.
38 * To modify the CAN frame content or the struct can_skb_priv content
39 * skb_copy() needs to be used instead of skb_clone().
40 */
41
42/**
43 * struct can_skb_priv - private additional data inside CAN sk_buffs
44 * @ifindex: ifindex of the first interface the CAN frame appeared on
45 * @skbcnt: atomic counter to have an unique id together with skb pointer
46 * @frame_len: length of CAN frame in data link layer
47 * @cf: align to the following CAN frame at skb->data
48 */
49struct can_skb_priv {
50 int ifindex;
51 int skbcnt;
52 unsigned int frame_len;
53 struct can_frame cf[];
54};
55
56static inline struct can_skb_priv *can_skb_prv(struct sk_buff *skb)
57{
58 return (struct can_skb_priv *)(skb->head);
59}
60
61static inline void can_skb_reserve(struct sk_buff *skb)
62{
63 skb_reserve(skb, sizeof(struct can_skb_priv));
64}
65
66static inline void can_skb_set_owner(struct sk_buff *skb, struct sock *sk)
67{
68 /* If the socket has already been closed by user space, the
69 * refcount may already be 0 (and the socket will be freed
70 * after the last TX skb has been freed). So only increase
71 * socket refcount if the refcount is > 0.
72 */
73 if (sk && refcount_inc_not_zero(&sk->sk_refcnt)) {
74 skb->destructor = sock_efree;
75 skb->sk = sk;
76 }
77}
78
79/*
80 * returns an unshared skb owned by the original sock to be echo'ed back
81 */
82static inline struct sk_buff *can_create_echo_skb(struct sk_buff *skb)
83{
84 struct sk_buff *nskb;
85
86 nskb = skb_clone(skb, GFP_ATOMIC);
87 if (unlikely(!nskb)) {
88 kfree_skb(skb);
89 return NULL;
90 }
91
92 can_skb_set_owner(nskb, skb->sk);
93 consume_skb(skb);
94 return nskb;
95}
96
97/* Check for outgoing skbs that have not been created by the CAN subsystem */
98static inline bool can_skb_headroom_valid(struct net_device *dev,
99 struct sk_buff *skb)
100{
101 /* af_packet creates a headroom of HH_DATA_MOD bytes which is fine */
102 if (WARN_ON_ONCE(skb_headroom(skb) < sizeof(struct can_skb_priv)))
103 return false;
104
105 /* af_packet does not apply CAN skb specific settings */
106 if (skb->ip_summed == CHECKSUM_NONE) {
107 /* init headroom */
108 can_skb_prv(skb)->ifindex = dev->ifindex;
109 can_skb_prv(skb)->skbcnt = 0;
110
111 skb->ip_summed = CHECKSUM_UNNECESSARY;
112
113 /* perform proper loopback on capable devices */
114 if (dev->flags & IFF_ECHO)
115 skb->pkt_type = PACKET_LOOPBACK;
116 else
117 skb->pkt_type = PACKET_HOST;
118
119 skb_reset_mac_header(skb);
120 skb_reset_network_header(skb);
121 skb_reset_transport_header(skb);
122 }
123
124 return true;
125}
126
127/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
128static inline bool can_dropped_invalid_skb(struct net_device *dev,
129 struct sk_buff *skb)
130{
131 const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
132
133 if (skb->protocol == htons(ETH_P_CAN)) {
134 if (unlikely(skb->len != CAN_MTU ||
135 cfd->len > CAN_MAX_DLEN))
136 goto inval_skb;
137 } else if (skb->protocol == htons(ETH_P_CANFD)) {
138 if (unlikely(skb->len != CANFD_MTU ||
139 cfd->len > CANFD_MAX_DLEN))
140 goto inval_skb;
141 } else
142 goto inval_skb;
143
144 if (!can_skb_headroom_valid(dev, skb))
145 goto inval_skb;
146
147 return false;
148
149inval_skb:
150 kfree_skb(skb);
151 dev->stats.tx_dropped++;
152 return true;
153}
154
155static inline bool can_is_canfd_skb(const struct sk_buff *skb)
156{
157 /* the CAN specific type of skb is identified by its data length */
158 return skb->len == CANFD_MTU;
159}
160
161#endif /* !_CAN_SKB_H */