527 lines
12 KiB
C
527 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* "LAPB via ethernet" driver release 001
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*
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* This code REQUIRES 2.1.15 or higher/ NET3.038
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*
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* This is a "pseudo" network driver to allow LAPB over Ethernet.
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*
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* This driver can use any ethernet destination address, and can be
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* limited to accept frames from one dedicated ethernet card only.
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*
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* History
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* LAPBETH 001 Jonathan Naylor Cloned from bpqether.c
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* 2000-10-29 Henner Eisen lapb_data_indication() return status.
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* 2000-11-14 Henner Eisen dev_hold/put, NETDEV_GOING_DOWN support
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/errno.h>
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#include <linux/types.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/net.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/if_arp.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/uaccess.h>
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#include <linux/mm.h>
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#include <linux/interrupt.h>
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#include <linux/notifier.h>
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#include <linux/stat.h>
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#include <linux/module.h>
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#include <linux/lapb.h>
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#include <linux/init.h>
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#include <net/x25device.h>
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static const u8 bcast_addr[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
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/* If this number is made larger, check that the temporary string buffer
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* in lapbeth_new_device is large enough to store the probe device name.
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*/
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#define MAXLAPBDEV 100
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struct lapbethdev {
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struct list_head node;
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struct net_device *ethdev; /* link to ethernet device */
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struct net_device *axdev; /* lapbeth device (lapb#) */
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bool up;
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spinlock_t up_lock; /* Protects "up" */
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struct sk_buff_head rx_queue;
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struct napi_struct napi;
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};
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static LIST_HEAD(lapbeth_devices);
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static void lapbeth_connected(struct net_device *dev, int reason);
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static void lapbeth_disconnected(struct net_device *dev, int reason);
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/* ------------------------------------------------------------------------ */
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/* Get the LAPB device for the ethernet device
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*/
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static struct lapbethdev *lapbeth_get_x25_dev(struct net_device *dev)
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{
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struct lapbethdev *lapbeth;
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list_for_each_entry_rcu(lapbeth, &lapbeth_devices, node, lockdep_rtnl_is_held()) {
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if (lapbeth->ethdev == dev)
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return lapbeth;
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}
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return NULL;
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}
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static __inline__ int dev_is_ethdev(struct net_device *dev)
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{
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return dev->type == ARPHRD_ETHER && strncmp(dev->name, "dummy", 5);
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}
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/* ------------------------------------------------------------------------ */
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static int lapbeth_napi_poll(struct napi_struct *napi, int budget)
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{
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struct lapbethdev *lapbeth = container_of(napi, struct lapbethdev,
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napi);
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struct sk_buff *skb;
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int processed = 0;
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for (; processed < budget; ++processed) {
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skb = skb_dequeue(&lapbeth->rx_queue);
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if (!skb)
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break;
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netif_receive_skb_core(skb);
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}
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if (processed < budget)
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napi_complete(napi);
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return processed;
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}
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/* Receive a LAPB frame via an ethernet interface.
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*/
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static int lapbeth_rcv(struct sk_buff *skb, struct net_device *dev,
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struct packet_type *ptype, struct net_device *orig_dev)
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{
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int len, err;
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struct lapbethdev *lapbeth;
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if (dev_net(dev) != &init_net)
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goto drop;
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skb = skb_share_check(skb, GFP_ATOMIC);
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if (!skb)
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return NET_RX_DROP;
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if (!pskb_may_pull(skb, 2))
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goto drop;
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rcu_read_lock();
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lapbeth = lapbeth_get_x25_dev(dev);
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if (!lapbeth)
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goto drop_unlock_rcu;
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spin_lock_bh(&lapbeth->up_lock);
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if (!lapbeth->up)
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goto drop_unlock;
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len = skb->data[0] + skb->data[1] * 256;
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dev->stats.rx_packets++;
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dev->stats.rx_bytes += len;
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skb_pull(skb, 2); /* Remove the length bytes */
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skb_trim(skb, len); /* Set the length of the data */
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err = lapb_data_received(lapbeth->axdev, skb);
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if (err != LAPB_OK) {
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printk(KERN_DEBUG "lapbether: lapb_data_received err - %d\n", err);
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goto drop_unlock;
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}
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out:
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spin_unlock_bh(&lapbeth->up_lock);
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rcu_read_unlock();
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return 0;
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drop_unlock:
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kfree_skb(skb);
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goto out;
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drop_unlock_rcu:
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rcu_read_unlock();
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drop:
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kfree_skb(skb);
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return 0;
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}
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static int lapbeth_data_indication(struct net_device *dev, struct sk_buff *skb)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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unsigned char *ptr;
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if (skb_cow(skb, 1)) {
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kfree_skb(skb);
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return NET_RX_DROP;
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}
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skb_push(skb, 1);
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ptr = skb->data;
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*ptr = X25_IFACE_DATA;
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skb->protocol = x25_type_trans(skb, dev);
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skb_queue_tail(&lapbeth->rx_queue, skb);
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napi_schedule(&lapbeth->napi);
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return NET_RX_SUCCESS;
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}
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/* Send a LAPB frame via an ethernet interface
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*/
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static netdev_tx_t lapbeth_xmit(struct sk_buff *skb,
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struct net_device *dev)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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int err;
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spin_lock_bh(&lapbeth->up_lock);
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if (!lapbeth->up)
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goto drop;
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/* There should be a pseudo header of 1 byte added by upper layers.
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* Check to make sure it is there before reading it.
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*/
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if (skb->len < 1)
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goto drop;
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switch (skb->data[0]) {
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case X25_IFACE_DATA:
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break;
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case X25_IFACE_CONNECT:
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err = lapb_connect_request(dev);
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if (err == LAPB_CONNECTED)
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lapbeth_connected(dev, LAPB_OK);
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else if (err != LAPB_OK)
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pr_err("lapb_connect_request error: %d\n", err);
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goto drop;
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case X25_IFACE_DISCONNECT:
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err = lapb_disconnect_request(dev);
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if (err == LAPB_NOTCONNECTED)
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lapbeth_disconnected(dev, LAPB_OK);
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else if (err != LAPB_OK)
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pr_err("lapb_disconnect_request err: %d\n", err);
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fallthrough;
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default:
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goto drop;
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}
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skb_pull(skb, 1);
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err = lapb_data_request(dev, skb);
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if (err != LAPB_OK) {
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pr_err("lapb_data_request error - %d\n", err);
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goto drop;
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}
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out:
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spin_unlock_bh(&lapbeth->up_lock);
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return NETDEV_TX_OK;
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drop:
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kfree_skb(skb);
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goto out;
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}
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static void lapbeth_data_transmit(struct net_device *ndev, struct sk_buff *skb)
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{
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struct lapbethdev *lapbeth = netdev_priv(ndev);
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unsigned char *ptr;
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struct net_device *dev;
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int size = skb->len;
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ptr = skb_push(skb, 2);
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*ptr++ = size % 256;
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*ptr++ = size / 256;
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ndev->stats.tx_packets++;
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ndev->stats.tx_bytes += size;
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skb->dev = dev = lapbeth->ethdev;
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skb->protocol = htons(ETH_P_DEC);
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skb_reset_network_header(skb);
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dev_hard_header(skb, dev, ETH_P_DEC, bcast_addr, NULL, 0);
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dev_queue_xmit(skb);
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}
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static void lapbeth_connected(struct net_device *dev, int reason)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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unsigned char *ptr;
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struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
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if (!skb)
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return;
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ptr = skb_put(skb, 1);
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*ptr = X25_IFACE_CONNECT;
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skb->protocol = x25_type_trans(skb, dev);
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skb_queue_tail(&lapbeth->rx_queue, skb);
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napi_schedule(&lapbeth->napi);
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}
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static void lapbeth_disconnected(struct net_device *dev, int reason)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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unsigned char *ptr;
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struct sk_buff *skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
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if (!skb)
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return;
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ptr = skb_put(skb, 1);
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*ptr = X25_IFACE_DISCONNECT;
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skb->protocol = x25_type_trans(skb, dev);
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skb_queue_tail(&lapbeth->rx_queue, skb);
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napi_schedule(&lapbeth->napi);
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}
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/* Set AX.25 callsign
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*/
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static int lapbeth_set_mac_address(struct net_device *dev, void *addr)
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{
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struct sockaddr *sa = addr;
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dev_addr_set(dev, sa->sa_data);
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return 0;
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}
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static const struct lapb_register_struct lapbeth_callbacks = {
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.connect_confirmation = lapbeth_connected,
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.connect_indication = lapbeth_connected,
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.disconnect_confirmation = lapbeth_disconnected,
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.disconnect_indication = lapbeth_disconnected,
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.data_indication = lapbeth_data_indication,
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.data_transmit = lapbeth_data_transmit,
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};
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/* open/close a device
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*/
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static int lapbeth_open(struct net_device *dev)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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int err;
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napi_enable(&lapbeth->napi);
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err = lapb_register(dev, &lapbeth_callbacks);
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if (err != LAPB_OK) {
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napi_disable(&lapbeth->napi);
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pr_err("lapb_register error: %d\n", err);
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return -ENODEV;
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}
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spin_lock_bh(&lapbeth->up_lock);
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lapbeth->up = true;
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spin_unlock_bh(&lapbeth->up_lock);
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return 0;
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}
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static int lapbeth_close(struct net_device *dev)
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{
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struct lapbethdev *lapbeth = netdev_priv(dev);
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int err;
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spin_lock_bh(&lapbeth->up_lock);
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lapbeth->up = false;
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spin_unlock_bh(&lapbeth->up_lock);
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err = lapb_unregister(dev);
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if (err != LAPB_OK)
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pr_err("lapb_unregister error: %d\n", err);
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napi_disable(&lapbeth->napi);
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return 0;
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}
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/* ------------------------------------------------------------------------ */
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static const struct net_device_ops lapbeth_netdev_ops = {
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.ndo_open = lapbeth_open,
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.ndo_stop = lapbeth_close,
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.ndo_start_xmit = lapbeth_xmit,
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.ndo_set_mac_address = lapbeth_set_mac_address,
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};
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static void lapbeth_setup(struct net_device *dev)
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{
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dev->netdev_ops = &lapbeth_netdev_ops;
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dev->needs_free_netdev = true;
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dev->type = ARPHRD_X25;
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dev->hard_header_len = 0;
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dev->mtu = 1000;
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dev->addr_len = 0;
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}
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/* Setup a new device.
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*/
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static int lapbeth_new_device(struct net_device *dev)
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{
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struct net_device *ndev;
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struct lapbethdev *lapbeth;
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int rc = -ENOMEM;
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ASSERT_RTNL();
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if (dev->type != ARPHRD_ETHER)
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return -EINVAL;
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ndev = alloc_netdev(sizeof(*lapbeth), "lapb%d", NET_NAME_UNKNOWN,
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lapbeth_setup);
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if (!ndev)
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goto out;
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/* When transmitting data:
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* first this driver removes a pseudo header of 1 byte,
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* then the lapb module prepends an LAPB header of at most 3 bytes,
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* then this driver prepends a length field of 2 bytes,
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* then the underlying Ethernet device prepends its own header.
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*/
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ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
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+ dev->needed_headroom;
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ndev->needed_tailroom = dev->needed_tailroom;
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lapbeth = netdev_priv(ndev);
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lapbeth->axdev = ndev;
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dev_hold(dev);
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lapbeth->ethdev = dev;
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lapbeth->up = false;
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spin_lock_init(&lapbeth->up_lock);
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skb_queue_head_init(&lapbeth->rx_queue);
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netif_napi_add_weight(ndev, &lapbeth->napi, lapbeth_napi_poll, 16);
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rc = -EIO;
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if (register_netdevice(ndev))
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goto fail;
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list_add_rcu(&lapbeth->node, &lapbeth_devices);
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rc = 0;
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out:
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return rc;
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fail:
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dev_put(dev);
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free_netdev(ndev);
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goto out;
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}
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/* Free a lapb network device.
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*/
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static void lapbeth_free_device(struct lapbethdev *lapbeth)
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{
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dev_put(lapbeth->ethdev);
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list_del_rcu(&lapbeth->node);
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unregister_netdevice(lapbeth->axdev);
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}
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/* Handle device status changes.
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*
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* Called from notifier with RTNL held.
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*/
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static int lapbeth_device_event(struct notifier_block *this,
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unsigned long event, void *ptr)
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{
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struct lapbethdev *lapbeth;
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struct net_device *dev = netdev_notifier_info_to_dev(ptr);
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if (dev_net(dev) != &init_net)
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return NOTIFY_DONE;
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if (!dev_is_ethdev(dev) && !lapbeth_get_x25_dev(dev))
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return NOTIFY_DONE;
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switch (event) {
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case NETDEV_UP:
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/* New ethernet device -> new LAPB interface */
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if (!lapbeth_get_x25_dev(dev))
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lapbeth_new_device(dev);
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break;
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case NETDEV_GOING_DOWN:
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/* ethernet device closes -> close LAPB interface */
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lapbeth = lapbeth_get_x25_dev(dev);
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if (lapbeth)
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dev_close(lapbeth->axdev);
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break;
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case NETDEV_UNREGISTER:
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/* ethernet device disappears -> remove LAPB interface */
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lapbeth = lapbeth_get_x25_dev(dev);
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if (lapbeth)
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lapbeth_free_device(lapbeth);
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break;
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}
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return NOTIFY_DONE;
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}
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/* ------------------------------------------------------------------------ */
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static struct packet_type lapbeth_packet_type __read_mostly = {
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.type = cpu_to_be16(ETH_P_DEC),
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.func = lapbeth_rcv,
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};
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static struct notifier_block lapbeth_dev_notifier = {
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.notifier_call = lapbeth_device_event,
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};
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static const char banner[] __initconst =
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KERN_INFO "LAPB Ethernet driver version 0.02\n";
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static int __init lapbeth_init_driver(void)
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{
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dev_add_pack(&lapbeth_packet_type);
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register_netdevice_notifier(&lapbeth_dev_notifier);
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printk(banner);
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return 0;
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}
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module_init(lapbeth_init_driver);
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static void __exit lapbeth_cleanup_driver(void)
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{
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struct lapbethdev *lapbeth;
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struct list_head *entry, *tmp;
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dev_remove_pack(&lapbeth_packet_type);
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unregister_netdevice_notifier(&lapbeth_dev_notifier);
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rtnl_lock();
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list_for_each_safe(entry, tmp, &lapbeth_devices) {
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lapbeth = list_entry(entry, struct lapbethdev, node);
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dev_put(lapbeth->ethdev);
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unregister_netdevice(lapbeth->axdev);
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}
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rtnl_unlock();
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}
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module_exit(lapbeth_cleanup_driver);
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MODULE_AUTHOR("Jonathan Naylor <g4klx@g4klx.demon.co.uk>");
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MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver");
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MODULE_LICENSE("GPL");
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