diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/net/wan/lapbether.c | 482 |
1 files changed, 482 insertions, 0 deletions
diff --git a/drivers/net/wan/lapbether.c b/drivers/net/wan/lapbether.c new file mode 100644 index 000000000..24c53cc0c --- /dev/null +++ b/drivers/net/wan/lapbether.c @@ -0,0 +1,482 @@ +// 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" */ +}; + +static LIST_HEAD(lapbeth_devices); + +/* ------------------------------------------------------------------------ */ + +/* + * 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); +} + +/* ------------------------------------------------------------------------ */ + +/* + * 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; + + if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) + 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 */ + + if ((err = lapb_data_received(lapbeth->axdev, skb)) != 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) +{ + 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); + return netif_rx(skb); +} + +/* + * 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: + if ((err = lapb_connect_request(dev)) != LAPB_OK) + pr_err("lapb_connect_request error: %d\n", err); + goto drop; + case X25_IFACE_DISCONNECT: + if ((err = lapb_disconnect_request(dev)) != LAPB_OK) + pr_err("lapb_disconnect_request err: %d\n", err); + fallthrough; + default: + goto drop; + } + + skb_pull(skb, 1); + + if ((err = lapb_data_request(dev, skb)) != 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) +{ + unsigned char *ptr; + struct sk_buff *skb = dev_alloc_skb(1); + + if (!skb) { + pr_err("out of memory\n"); + return; + } + + ptr = skb_put(skb, 1); + *ptr = X25_IFACE_CONNECT; + + skb->protocol = x25_type_trans(skb, dev); + netif_rx(skb); +} + +static void lapbeth_disconnected(struct net_device *dev, int reason) +{ + unsigned char *ptr; + struct sk_buff *skb = dev_alloc_skb(1); + + if (!skb) { + pr_err("out of memory\n"); + return; + } + + ptr = skb_put(skb, 1); + *ptr = X25_IFACE_DISCONNECT; + + skb->protocol = x25_type_trans(skb, dev); + netif_rx(skb); +} + +/* + * Set AX.25 callsign + */ +static int lapbeth_set_mac_address(struct net_device *dev, void *addr) +{ + struct sockaddr *sa = addr; + memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); + 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; + + if ((err = lapb_register(dev, &lapbeth_callbacks)) != LAPB_OK) { + 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); + + if ((err = lapb_unregister(dev)) != LAPB_OK) + pr_err("lapb_unregister error: %d\n", err); + + 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); + + 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) == NULL) + lapbeth_new_device(dev); + break; + case NETDEV_DOWN: + /* ethernet device closed -> 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 <g4klx@g4klx.demon.co.uk>"); +MODULE_DESCRIPTION("The unofficial LAPB over Ethernet driver"); +MODULE_LICENSE("GPL"); |