// SPDX-License-Identifier: GPL-2.0-or-later
/*
* "LAPB via ethernet" driver release 001
*
* This code REQUIRES 2.1.15 or higher/ NET3.038
*
* This is a "pseudo" network driver to allow LAPB over Ethernet.
*
* This driver can use any ethernet destination address, and can be
* limited to accept frames from one dedicated ethernet card only.
*
* History
* LAPBETH 001 Jonathan Naylor Cloned from bpqether.c
* 2000-10-29 Henner Eisen lapb_data_indication() return status.
* 2000-11-14 Henner Eisen dev_hold/put, NETDEV_GOING_DOWN support
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/net.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/stat.h>
#include <linux/module.h>
#include <linux/lapb.h>
#include <linux/init.h>
#include <net/x25device.h>
static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
/* If this number is made larger, check that the temporary string buffer
* in lapbeth_new_device is large enough to store the probe device name.
*/
#define MAXLAPBDEV 100
struct lapbethdev {
struct list_head node;
struct net_device *ethdev; /* link to ethernet device */
struct net_device *axdev; /* lapbeth device (lapb#) */
bool up;
spinlock_t up_lock; /* Protects "up" */
struct sk_buff_head rx_queue;
struct napi_struct napi;
};
static LIST_HEAD(lapbeth_devices);
static void lapbeth_connected(struct net_device *dev, int reason);
static void lapbeth_disconnected(struct net_device *dev, int reason);
/* ------------------------------------------------------------------------ */
/* Get the LAPB device for the ethernet device
*/
static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
{
struct lapbethdev *lapbeth;
list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
if (lapbeth->ethdev == dev)
return lapbeth;
}
return NULL;
}
static __inline__ int dev_is_ethdev(struct net_device *dev)
{
return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
}
/* ------------------------------------------------------------------------ */
static int lapbeth_napi_poll(struct napi_struct *napi, int budget)
{
struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev,
napi);
struct sk_buff *skb;
int processed = 0;
for (; processed < budget; ++processed) {
skb = skb_dequeue(&lapbeth->rx_queue);
if (!skb)
break;
netif_receive_skb_core(skb);
}
if (processed < budget)
napi_complete(napi);
return processed;
}
/* Receive a LAPB frame via an ethernet interface.
*/
static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *ptype, struct net_device *orig_dev)
{
int len, err;
struct lapbethdev *lapbeth;
if (dev_net(dev) != &init_net)
goto drop;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
return NET_RX_DROP;
if (!pskb_may_pull(skb, 2))
goto drop;
rcu_read_lock();
lapbeth = lapbeth_get_x25_dev(dev);
if (!lapbeth)
goto drop_unlock_rcu;
spin_lock_bh(&lapbeth->up_lock);
if (!lapbeth->up)
goto drop_unlock;
len = skb->data[0] + skb->data[1] * 256;
dev->stats.rx_packets++;
dev->stats.rx_bytes += len;
skb_pull(skb, 2); /* Remove the length bytes */
skb_trim(skb, len); /* Set the length of the data */
err = lapb_data_received(lapbeth->axdev, skb);
if (err != LAPB_OK) {
printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
goto drop_unlock;
}
out:
spin_unlock_bh(&lapbeth->up_lock);
rcu_read_unlock();
return 0;
drop_unlock:
kfree_skb(skb);
goto out;
drop_unlock_rcu:
rcu_read_unlock();
drop:
kfree_skb(skb);
return 0;
}
static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
unsigned char *ptr;
if (skb_cow(skb, 1)) {
kfree_skb(skb);
return NET_RX_DROP;
}
skb_push(skb, 1);
ptr = skb->data;
*ptr = X25_IFACE_DATA;
skb->protocol = x25_type_trans(skb, dev);
skb_queue_tail(&lapbeth->rx_queue, skb);
napi_schedule(&lapbeth->napi);
return NET_RX_SUCCESS;
}
/* Send a LAPB frame via an ethernet interface
*/
static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
struct net_device *dev)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
int err;
spin_lock_bh(&lapbeth->up_lock);
if (!lapbeth->up)
goto drop;
/* There should be a pseudo header of 1 byte added by upper layers.
* Check to make sure it is there before reading it.
*/
if (skb->len < 1)
goto drop;
switch (skb->data[0]) {
case X25_IFACE_DATA:
break;
case X25_IFACE_CONNECT:
err = lapb_connect_request(dev);
if (err == LAPB_CONNECTED)
lapbeth_connected(dev, LAPB_OK);
else if (err != LAPB_OK)
pr_err("lapb_connect_request error: %d\n", err);
goto drop;
case X25_IFACE_DISCONNECT:
err = lapb_disconnect_request(dev);
if (err == LAPB_NOTCONNECTED)
lapbeth_disconnected(dev, LAPB_OK);
else if (err != LAPB_OK)
pr_err("lapb_disconnect_request err: %d\n", err);
fallthrough;
default:
goto drop;
}
skb_pull(skb, 1);
err = lapb_data_request(dev, skb);
if (err != LAPB_OK) {
pr_err("lapb_data_request error - %d\n", err);
goto drop;
}
out:
spin_unlock_bh(&lapbeth->up_lock);
return NETDEV_TX_OK;
drop:
kfree_skb(skb);
goto out;
}
static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
{
struct lapbethdev *lapbeth = netdev_priv(ndev);
unsigned char *ptr;
struct net_device *dev;
int size = skb->len;
ptr = skb_push(skb, 2);
*ptr++ = size % 256;
*ptr++ = size / 256;
ndev->stats.tx_packets++;
ndev->stats.tx_bytes += size;
skb->dev = dev = lapbeth->ethdev;
skb->protocol = htons(ETH_P_DEC);
skb_reset_network_header(skb);
dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
dev_queue_xmit(skb);
}
static void lapbeth_connected(struct net_device *dev, int reason)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
unsigned char *ptr;
struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
if (!skb)
return;
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_CONNECT;
skb->protocol = x25_type_trans(skb, dev);
skb_queue_tail(&lapbeth->rx_queue, skb);
napi_schedule(&lapbeth->napi);
}
static void lapbeth_disconnected(struct net_device *dev, int reason)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
unsigned char *ptr;
struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
if (!skb)
return;
ptr = skb_put(skb, 1);
*ptr = X25_IFACE_DISCONNECT;
skb->protocol = x25_type_trans(skb, dev);
skb_queue_tail(&lapbeth->rx_queue, skb);
napi_schedule(&lapbeth->napi);
}
/* Set AX.25 callsign
*/
static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
{
struct sockaddr *sa = addr;
dev_addr_set(dev, sa->sa_data);
return 0;
}
static const struct lapb_register_struct lapbeth_callbacks = {
.connect_confirmation = lapbeth_connected,
.connect_indication = lapbeth_connected,
.disconnect_confirmation = lapbeth_disconnected,
.disconnect_indication = lapbeth_disconnected,
.data_indication = lapbeth_data_indication,
.data_transmit = lapbeth_data_transmit,
};
/* open/close a device
*/
static int lapbeth_open(struct net_device *dev)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
int err;
napi_enable(&lapbeth->napi);
err = lapb_register(dev, &lapbeth_callbacks);
if (err != LAPB_OK) {
napi_disable(&lapbeth->napi);
pr_err("lapb_register error: %d\n", err);
return -ENODEV;
}
spin_lock_bh(&lapbeth->up_lock);
lapbeth->up = true;
spin_unlock_bh(&lapbeth->up_lock);
return 0;
}
static int lapbeth_close(struct net_device *dev)
{
struct lapbethdev *lapbeth = netdev_priv(dev);
int err;
spin_lock_bh(&lapbeth->up_lock);
lapbeth->up = false;
spin_unlock_bh(&lapbeth->up_lock);
err = lapb_unregister(dev);
if (err != LAPB_OK)
pr_err("lapb_unregister error: %d\n", err);
napi_disable(&lapbeth->napi);
return 0;
}
/* ------------------------------------------------------------------------ */
static const struct net_device_ops lapbeth_netdev_ops = {
.ndo_open = lapbeth_open,
.ndo_stop = lapbeth_close,
.ndo_start_xmit = lapbeth_xmit,
.ndo_set_mac_address = lapbeth_set_mac_address,
};
static void lapbeth_setup(struct net_device *dev)
{
dev->netdev_ops = &lapbeth_netdev_ops;
dev->needs_free_netdev = true;
dev->type = ARPHRD_X25;
dev->hard_header_len = 0;
dev->mtu = 1000;
dev->addr_len = 0;
}
/* Setup a new device.
*/
static int lapbeth_new_device(struct net_device *dev)
{
struct net_device *ndev;
struct lapbethdev *lapbeth;
int rc = -ENOMEM;
ASSERT_RTNL();
if (dev->type != ARPHRD_ETHER)
return -EINVAL;
ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
lapbeth_setup);
if (!ndev)
goto out;
/* When transmitting data:
* first this driver removes a pseudo header of 1 byte,
* then the lapb module prepends an LAPB header of at most 3 bytes,
* then this driver prepends a length field of 2 bytes,
* then the underlying Ethernet device prepends its own header.
*/
ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
+ dev->needed_headroom;
ndev->needed_tailroom = dev->needed_tailroom;
lapbeth = netdev_priv(ndev);
lapbeth->axdev = ndev;
dev_hold(dev);
lapbeth->ethdev = dev;
lapbeth->up = false;
spin_lock_init(&lapbeth->up_lock);
skb_queue_head_init(&lapbeth->rx_queue);
netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
rc = -EIO;
if (register_netdevice(ndev))
goto fail;
list_add_rcu(&lapbeth->node, &lapbeth_devices);
rc = 0;
out:
return rc;
fail:
dev_put(dev);
free_netdev(ndev);
goto out;
}
/* Free a lapb network device.
*/
static void lapbeth_free_device(struct lapbethdev *lapbeth)
{
dev_put(lapbeth->ethdev);
list_del_rcu(&lapbeth->node);
unregister_netdevice(lapbeth->axdev);
}
/* Handle device status changes.
*
* Called from notifier with RTNL held.
*/
static int lapbeth_device_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
struct lapbethdev *lapbeth;
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
if (dev_net(dev) != &init_net)
return NOTIFY_DONE;
if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev))
return NOTIFY_DONE;
switch (event) {
case NETDEV_UP:
/* New ethernet device -> new LAPB interface */
if (!lapbeth_get_x25_dev(dev))
lapbeth_new_device(dev);
break;
case NETDEV_GOING_DOWN:
/* ethernet device closes -> close LAPB interface */
lapbeth = lapbeth_get_x25_dev(dev);
if (lapbeth)
dev_close(lapbeth->axdev);
break;
case NETDEV_UNREGISTER:
/* ethernet device disappears -> remove LAPB interface */
lapbeth = lapbeth_get_x25_dev(dev);
if (lapbeth)
lapbeth_free_device(lapbeth);
break;
}
return NOTIFY_DONE;
}
/* ------------------------------------------------------------------------ */
static struct packet_type lapbeth_packet_type __read_mostly = {
.type = cpu_to_be16(ETH_P_DEC),
.func = lapbeth_rcv,
};
static struct notifier_block lapbeth_dev_notifier = {
.notifier_call = lapbeth_device_event,
};
static const char banner[] __initconst =
KERN_INFO "LAPB Ethernet driver version 0.02\n";
static int __init lapbeth_init_driver(void)
{
dev_add_pack(&lapbeth_packet_type);
register_netdevice_notifier(&lapbeth_dev_notifier);
printk(banner);
return 0;
}
module_init(lapbeth_init_driver);
static void __exit lapbeth_cleanup_driver(void)
{
struct lapbethdev *lapbeth;
struct list_head *entry, *tmp;
dev_remove_pack(&lapbeth_packet_type);
unregister_netdevice_notifier(&lapbeth_dev_notifier);
rtnl_lock();
list_for_each_safe(entry, tmp, &lapbeth_devices) {
lapbeth = list_entry(entry, struct lapbethdev, node);
dev_put(lapbeth->ethdev);
unregister_netdevice(lapbeth->axdev);
}
rtnl_unlock();
}
module_exit(lapbeth_cleanup_driver);
MODULE_AUTHOR("Jonathan Naylor <[email protected]>");
MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
MODULE_LICENSE("GPL");
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