1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Generic HDLC support routines for Linux
4 * HDLC Ethernet emulation support
5 *
6 * Copyright (C) 2002-2006 Krzysztof Halasa <khc@pm.waw.pl>
7 */
8
9#include <linux/errno.h>
10#include <linux/etherdevice.h>
11#include <linux/gfp.h>
12#include <linux/hdlc.h>
13#include <linux/if_arp.h>
14#include <linux/inetdevice.h>
15#include <linux/init.h>
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/pkt_sched.h>
19#include <linux/poll.h>
20#include <linux/rtnetlink.h>
21#include <linux/skbuff.h>
22
23static int raw_eth_ioctl(struct net_device *dev, struct if_settings *ifs);
24
25static netdev_tx_t eth_tx(struct sk_buff *skb, struct net_device *dev)
26{
27	int pad = ETH_ZLEN - skb->len;
28	if (pad > 0) {		/* Pad the frame with zeros */
29		int len = skb->len;
30		if (skb_tailroom(skb) < pad)
31			if (pskb_expand_head(skb, 0, pad, GFP_ATOMIC)) {
32				dev->stats.tx_dropped++;
33				dev_kfree_skb(skb);
34				return 0;
35			}
36		skb_put(skb, pad);
37		memset(skb->data + len, 0, pad);
38	}
39	return dev_to_hdlc(dev)->xmit(skb, dev);
40}
41
42
43static struct hdlc_proto proto = {
44	.type_trans	= eth_type_trans,
45	.xmit		= eth_tx,
46	.ioctl		= raw_eth_ioctl,
47	.module		= THIS_MODULE,
48};
49
50
51static int raw_eth_ioctl(struct net_device *dev, struct if_settings *ifs)
52{
53	raw_hdlc_proto __user *raw_s = ifs->ifs_ifsu.raw_hdlc;
54	const size_t size = sizeof(raw_hdlc_proto);
55	raw_hdlc_proto new_settings;
56	hdlc_device *hdlc = dev_to_hdlc(dev);
57	unsigned int old_qlen;
58	int result;
59
60	switch (ifs->type) {
61	case IF_GET_PROTO:
62		if (dev_to_hdlc(dev)->proto != &proto)
63			return -EINVAL;
64		ifs->type = IF_PROTO_HDLC_ETH;
65		if (ifs->size < size) {
66			ifs->size = size; /* data size wanted */
67			return -ENOBUFS;
68		}
69		if (copy_to_user(raw_s, hdlc->state, size))
70			return -EFAULT;
71		return 0;
72
73	case IF_PROTO_HDLC_ETH:
74		if (!capable(CAP_NET_ADMIN))
75			return -EPERM;
76
77		if (dev->flags & IFF_UP)
78			return -EBUSY;
79
80		if (copy_from_user(&new_settings, raw_s, size))
81			return -EFAULT;
82
83		if (new_settings.encoding == ENCODING_DEFAULT)
84			new_settings.encoding = ENCODING_NRZ;
85
86		if (new_settings.parity == PARITY_DEFAULT)
87			new_settings.parity = PARITY_CRC16_PR1_CCITT;
88
89		result = hdlc->attach(dev, new_settings.encoding,
90				      new_settings.parity);
91		if (result)
92			return result;
93
94		result = attach_hdlc_protocol(dev, &proto,
95					      sizeof(raw_hdlc_proto));
96		if (result)
97			return result;
98		memcpy(hdlc->state, &new_settings, size);
99		old_qlen = dev->tx_queue_len;
100		ether_setup(dev);
101		dev->tx_queue_len = old_qlen;
102		dev->priv_flags &= ~IFF_TX_SKB_SHARING;
103		eth_hw_addr_random(dev);
104		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
105		netif_dormant_off(dev);
106		return 0;
107	}
108
109	return -EINVAL;
110}
111
112
113static int __init hdlc_eth_init(void)
114{
115	register_hdlc_protocol(&proto);
116	return 0;
117}
118
119
120
121static void __exit hdlc_eth_exit(void)
122{
123	unregister_hdlc_protocol(&proto);
124}
125
126
127module_init(hdlc_eth_init);
128module_exit(hdlc_eth_exit);
129
130MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
131MODULE_DESCRIPTION("Ethernet encapsulation support for generic HDLC");
132MODULE_LICENSE("GPL v2");
133