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slip.c
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slip.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* slip.c This module implements the SLIP protocol for kernel-based
* devices like TTY. It interfaces between a raw TTY, and the
* kernel's INET protocol layers.
*
* Version: @(#)slip.c 0.8.3 12/24/94
*
* Authors: Laurence Culhane, <loz@holmes.demon.co.uk>
* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
*
* Fixes:
* Alan Cox : Sanity checks and avoid tx overruns.
* Has a new sl->mtu field.
* Alan Cox : Found cause of overrun. ifconfig sl0
* mtu upwards. Driver now spots this
* and grows/shrinks its buffers(hack!).
* Memory leak if you run out of memory
* setting up a slip driver fixed.
* Matt Dillon : Printable slip (borrowed from NET2E)
* Pauline Middelink : Slip driver fixes.
* Alan Cox : Honours the old SL_COMPRESSED flag
* Alan Cox : KISS AX.25 and AXUI IP support
* Michael Riepe : Automatic CSLIP recognition added
* Charles Hedrick : CSLIP header length problem fix.
* Alan Cox : Corrected non-IP cases of the above.
* Alan Cox : Now uses hardware type as per FvK.
* Alan Cox : Default to 192.168.0.0 (RFC 1597)
* A.N.Kuznetsov : dev_tint() recursion fix.
* Dmitry Gorodchanin : SLIP memory leaks
* Dmitry Gorodchanin : Code cleanup. Reduce tty driver
* buffering from 4096 to 256 bytes.
* Improving SLIP response time.
* CONFIG_SLIP_MODE_SLIP6.
* ifconfig sl? up & down now works
* correctly.
* Modularization.
* Alan Cox : Oops - fix AX.25 buffer lengths
* Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP
* statistics. Include CSLIP code only
* if it really needed.
* Alan Cox : Free slhc buffers in the right place.
* Alan Cox : Allow for digipeated IP over AX.25
* Matti Aarnio : Dynamic SLIP devices, with ideas taken
* from Jim Freeman's <jfree@caldera.com>
* dynamic PPP devices. We do NOT kfree()
* device entries, just reg./unreg. them
* as they are needed. We kfree() them
* at module cleanup.
* With MODULE-loading ``insmod'', user
* can issue parameter: slip_maxdev=1024
* (Or how much he/she wants.. Default
* is 256)
* Stanislav Voronyi : Slip line checking, with ideas taken
* from multislip BSDI driver which was
* written by Igor Chechik, RELCOM Corp.
* Only algorithms have been ported to
* Linux SLIP driver.
* Vitaly E. Lavrov : Sane behaviour on tty hangup.
* Alexey Kuznetsov : Cleanup interfaces to tty & netdevice
* modules.
*/
#define SL_CHECK_TRANSMIT
#include <linux/compat.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/sched/signal.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/if_arp.h>
#include <linux/if_slip.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/workqueue.h>
#include "slip.h"
#ifdef CONFIG_INET
#include <linux/ip.h>
#include <linux/tcp.h>
#include <net/slhc_vj.h>
#endif
#define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
static struct net_device **slip_devs;
static int slip_maxdev = SL_NRUNIT;
module_param(slip_maxdev, int, 0);
MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
static int slip_esc(unsigned char *p, unsigned char *d, int len);
static void slip_unesc(struct slip *sl, unsigned char c);
#ifdef CONFIG_SLIP_MODE_SLIP6
static int slip_esc6(unsigned char *p, unsigned char *d, int len);
static void slip_unesc6(struct slip *sl, unsigned char c);
#endif
#ifdef CONFIG_SLIP_SMART
static void sl_keepalive(struct timer_list *t);
static void sl_outfill(struct timer_list *t);
static int sl_siocdevprivate(struct net_device *dev, struct ifreq *rq, void __user *data, int cmd);
#endif
/********************************
* Buffer administration routines:
* sl_alloc_bufs()
* sl_free_bufs()
* sl_realloc_bufs()
*
* NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
* sl_realloc_bufs provides strong atomicity and reallocation
* on actively running device.
*********************************/
/*
Allocate channel buffers.
*/
static int sl_alloc_bufs(struct slip *sl, int mtu)
{
int err = -ENOBUFS;
unsigned long len;
char *rbuff = NULL;
char *xbuff = NULL;
#ifdef SL_INCLUDE_CSLIP
char *cbuff = NULL;
struct slcompress *slcomp = NULL;
#endif
/*
* Allocate the SLIP frame buffers:
*
* rbuff Receive buffer.
* xbuff Transmit buffer.
* cbuff Temporary compression buffer.
*/
len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
rbuff = kmalloc(len + 4, GFP_KERNEL);
if (rbuff == NULL)
goto err_exit;
xbuff = kmalloc(len + 4, GFP_KERNEL);
if (xbuff == NULL)
goto err_exit;
#ifdef SL_INCLUDE_CSLIP
cbuff = kmalloc(len + 4, GFP_KERNEL);
if (cbuff == NULL)
goto err_exit;
slcomp = slhc_init(16, 16);
if (IS_ERR(slcomp))
goto err_exit;
#endif
spin_lock_bh(&sl->lock);
if (sl->tty == NULL) {
spin_unlock_bh(&sl->lock);
err = -ENODEV;
goto err_exit;
}
sl->mtu = mtu;
sl->buffsize = len;
sl->rcount = 0;
sl->xleft = 0;
rbuff = xchg(&sl->rbuff, rbuff);
xbuff = xchg(&sl->xbuff, xbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
slcomp = xchg(&sl->slcomp, slcomp);
#endif
#ifdef CONFIG_SLIP_MODE_SLIP6
sl->xdata = 0;
sl->xbits = 0;
#endif
spin_unlock_bh(&sl->lock);
err = 0;
/* Cleanup */
err_exit:
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
slhc_free(slcomp);
#endif
kfree(xbuff);
kfree(rbuff);
return err;
}
/* Free a SLIP channel buffers. */
static void sl_free_bufs(struct slip *sl)
{
/* Free all SLIP frame buffers. */
kfree(xchg(&sl->rbuff, NULL));
kfree(xchg(&sl->xbuff, NULL));
#ifdef SL_INCLUDE_CSLIP
kfree(xchg(&sl->cbuff, NULL));
slhc_free(xchg(&sl->slcomp, NULL));
#endif
}
/*
Reallocate slip channel buffers.
*/
static int sl_realloc_bufs(struct slip *sl, int mtu)
{
int err = 0;
struct net_device *dev = sl->dev;
unsigned char *xbuff, *rbuff;
#ifdef SL_INCLUDE_CSLIP
unsigned char *cbuff;
#endif
int len = mtu * 2;
/*
* allow for arrival of larger UDP packets, even if we say not to
* also fixes a bug in which SunOS sends 512-byte packets even with
* an MSS of 128
*/
if (len < 576 * 2)
len = 576 * 2;
xbuff = kmalloc(len + 4, GFP_ATOMIC);
rbuff = kmalloc(len + 4, GFP_ATOMIC);
#ifdef SL_INCLUDE_CSLIP
cbuff = kmalloc(len + 4, GFP_ATOMIC);
#endif
#ifdef SL_INCLUDE_CSLIP
if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
#else
if (xbuff == NULL || rbuff == NULL) {
#endif
if (mtu > sl->mtu) {
printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
dev->name);
err = -ENOBUFS;
}
goto done;
}
spin_lock_bh(&sl->lock);
err = -ENODEV;
if (sl->tty == NULL)
goto done_on_bh;
xbuff = xchg(&sl->xbuff, xbuff);
rbuff = xchg(&sl->rbuff, rbuff);
#ifdef SL_INCLUDE_CSLIP
cbuff = xchg(&sl->cbuff, cbuff);
#endif
if (sl->xleft) {
if (sl->xleft <= len) {
memcpy(sl->xbuff, sl->xhead, sl->xleft);
} else {
sl->xleft = 0;
dev->stats.tx_dropped++;
}
}
sl->xhead = sl->xbuff;
if (sl->rcount) {
if (sl->rcount <= len) {
memcpy(sl->rbuff, rbuff, sl->rcount);
} else {
sl->rcount = 0;
dev->stats.rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
sl->mtu = mtu;
dev->mtu = mtu;
sl->buffsize = len;
err = 0;
done_on_bh:
spin_unlock_bh(&sl->lock);
done:
kfree(xbuff);
kfree(rbuff);
#ifdef SL_INCLUDE_CSLIP
kfree(cbuff);
#endif
return err;
}
/* Set the "sending" flag. This must be atomic hence the set_bit. */
static inline void sl_lock(struct slip *sl)
{
netif_stop_queue(sl->dev);
}
/* Clear the "sending" flag. This must be atomic, hence the ASM. */
static inline void sl_unlock(struct slip *sl)
{
netif_wake_queue(sl->dev);
}
/* Send one completely decapsulated IP datagram to the IP layer. */
static void sl_bump(struct slip *sl)
{
struct net_device *dev = sl->dev;
struct sk_buff *skb;
int count;
count = sl->rcount;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
unsigned char c = sl->rbuff[0];
if (c & SL_TYPE_COMPRESSED_TCP) {
/* ignore compressed packets when CSLIP is off */
if (!(sl->mode & SL_MODE_CSLIP)) {
printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
return;
}
/* make sure we've reserved enough space for uncompress
to use */
if (count + 80 > sl->buffsize) {
dev->stats.rx_over_errors++;
return;
}
count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
if (count <= 0)
return;
} else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
if (!(sl->mode & SL_MODE_CSLIP)) {
/* turn on header compression */
sl->mode |= SL_MODE_CSLIP;
sl->mode &= ~SL_MODE_ADAPTIVE;
printk(KERN_INFO "%s: header compression turned on\n", dev->name);
}
sl->rbuff[0] &= 0x4f;
if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
return;
}
}
#endif /* SL_INCLUDE_CSLIP */
dev->stats.rx_bytes += count;
skb = dev_alloc_skb(count);
if (skb == NULL) {
printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
dev->stats.rx_dropped++;
return;
}
skb->dev = dev;
skb_put_data(skb, sl->rbuff, count);
skb_reset_mac_header(skb);
skb->protocol = htons(ETH_P_IP);
netif_rx(skb);
dev->stats.rx_packets++;
}
/* Encapsulate one IP datagram and stuff into a TTY queue. */
static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
{
unsigned char *p;
int actual, count;
if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */
printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
sl->dev->stats.tx_dropped++;
sl_unlock(sl);
return;
}
p = icp;
#ifdef SL_INCLUDE_CSLIP
if (sl->mode & SL_MODE_CSLIP)
len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
#endif
#ifdef CONFIG_SLIP_MODE_SLIP6
if (sl->mode & SL_MODE_SLIP6)
count = slip_esc6(p, sl->xbuff, len);
else
#endif
count = slip_esc(p, sl->xbuff, len);
/* Order of next two lines is *very* important.
* When we are sending a little amount of data,
* the transfer may be completed inside the ops->write()
* routine, because it's running with interrupts enabled.
* In this case we *never* got WRITE_WAKEUP event,
* if we did not request it before write operation.
* 14 Oct 1994 Dmitry Gorodchanin.
*/
set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
#ifdef SL_CHECK_TRANSMIT
netif_trans_update(sl->dev);
#endif
sl->xleft = count - actual;
sl->xhead = sl->xbuff + actual;
#ifdef CONFIG_SLIP_SMART
/* VSV */
clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
#endif
}
/* Write out any remaining transmit buffer. Scheduled when tty is writable */
static void slip_transmit(struct work_struct *work)
{
struct slip *sl = container_of(work, struct slip, tx_work);
int actual;
spin_lock_bh(&sl->lock);
/* First make sure we're connected. */
if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
spin_unlock_bh(&sl->lock);
return;
}
if (sl->xleft <= 0) {
/* Now serial buffer is almost free & we can start
* transmission of another packet */
sl->dev->stats.tx_packets++;
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
spin_unlock_bh(&sl->lock);
sl_unlock(sl);
return;
}
actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
sl->xleft -= actual;
sl->xhead += actual;
spin_unlock_bh(&sl->lock);
}
/*
* Called by the driver when there's room for more data.
* Schedule the transmit.
*/
static void slip_write_wakeup(struct tty_struct *tty)
{
struct slip *sl;
rcu_read_lock();
sl = rcu_dereference(tty->disc_data);
if (sl)
schedule_work(&sl->tx_work);
rcu_read_unlock();
}
static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (netif_queue_stopped(dev)) {
if (!netif_running(dev) || !sl->tty)
goto out;
/* May be we must check transmitter timeout here ?
* 14 Oct 1994 Dmitry Gorodchanin.
*/
#ifdef SL_CHECK_TRANSMIT
if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) {
/* 20 sec timeout not reached */
goto out;
}
printk(KERN_WARNING "%s: transmit timed out, %s?\n",
dev->name,
(tty_chars_in_buffer(sl->tty) || sl->xleft) ?
"bad line quality" : "driver error");
sl->xleft = 0;
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
sl_unlock(sl);
#endif
}
out:
spin_unlock(&sl->lock);
}
/* Encapsulate an IP datagram and kick it into a TTY queue. */
static netdev_tx_t
sl_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock(&sl->lock);
if (!netif_running(dev)) {
spin_unlock(&sl->lock);
printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
if (sl->tty == NULL) {
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
sl_lock(sl);
dev->stats.tx_bytes += skb->len;
sl_encaps(sl, skb->data, skb->len);
spin_unlock(&sl->lock);
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
/******************************************
* Routines looking at netdevice side.
******************************************/
/* Netdevice UP -> DOWN routine */
static int
sl_close(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
spin_lock_bh(&sl->lock);
if (sl->tty)
/* TTY discipline is running. */
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
netif_stop_queue(dev);
sl->rcount = 0;
sl->xleft = 0;
spin_unlock_bh(&sl->lock);
return 0;
}
/* Netdevice DOWN -> UP routine */
static int sl_open(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
if (sl->tty == NULL)
return -ENODEV;
sl->flags &= (1 << SLF_INUSE);
netif_start_queue(dev);
return 0;
}
/* Netdevice change MTU request */
static int sl_change_mtu(struct net_device *dev, int new_mtu)
{
struct slip *sl = netdev_priv(dev);
return sl_realloc_bufs(sl, new_mtu);
}
/* Netdevice get statistics request */
static void
sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
{
struct net_device_stats *devstats = &dev->stats;
#ifdef SL_INCLUDE_CSLIP
struct slip *sl = netdev_priv(dev);
struct slcompress *comp = sl->slcomp;
#endif
stats->rx_packets = devstats->rx_packets;
stats->tx_packets = devstats->tx_packets;
stats->rx_bytes = devstats->rx_bytes;
stats->tx_bytes = devstats->tx_bytes;
stats->rx_dropped = devstats->rx_dropped;
stats->tx_dropped = devstats->tx_dropped;
stats->tx_errors = devstats->tx_errors;
stats->rx_errors = devstats->rx_errors;
stats->rx_over_errors = devstats->rx_over_errors;
#ifdef SL_INCLUDE_CSLIP
if (comp) {
/* Generic compressed statistics */
stats->rx_compressed = comp->sls_i_compressed;
stats->tx_compressed = comp->sls_o_compressed;
/* Are we really still needs this? */
stats->rx_fifo_errors += comp->sls_i_compressed;
stats->rx_dropped += comp->sls_i_tossed;
stats->tx_fifo_errors += comp->sls_o_compressed;
stats->collisions += comp->sls_o_misses;
}
#endif
}
/* Netdevice register callback */
static int sl_init(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
/*
* Finish setting up the DEVICE info.
*/
dev->mtu = sl->mtu;
dev->type = ARPHRD_SLIP + sl->mode;
#ifdef SL_CHECK_TRANSMIT
dev->watchdog_timeo = 20*HZ;
#endif
return 0;
}
static void sl_uninit(struct net_device *dev)
{
struct slip *sl = netdev_priv(dev);
sl_free_bufs(sl);
}
/* Hook the destructor so we can free slip devices at the right point in time */
static void sl_free_netdev(struct net_device *dev)
{
int i = dev->base_addr;
slip_devs[i] = NULL;
}
static const struct net_device_ops sl_netdev_ops = {
.ndo_init = sl_init,
.ndo_uninit = sl_uninit,
.ndo_open = sl_open,
.ndo_stop = sl_close,
.ndo_start_xmit = sl_xmit,
.ndo_get_stats64 = sl_get_stats64,
.ndo_change_mtu = sl_change_mtu,
.ndo_tx_timeout = sl_tx_timeout,
#ifdef CONFIG_SLIP_SMART
.ndo_siocdevprivate = sl_siocdevprivate,
#endif
};
static void sl_setup(struct net_device *dev)
{
dev->netdev_ops = &sl_netdev_ops;
dev->needs_free_netdev = true;
dev->priv_destructor = sl_free_netdev;
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->tx_queue_len = 10;
/* MTU range: 68 - 65534 */
dev->min_mtu = 68;
dev->max_mtu = 65534;
/* New-style flags. */
dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
}
/******************************************
Routines looking at TTY side.
******************************************/
/*
* Handle the 'receiver data ready' interrupt.
* This function is called by the 'tty_io' module in the kernel when
* a block of SLIP data has been received, which can now be decapsulated
* and sent on to some IP layer for further processing. This will not
* be re-entered while running but other ldisc functions may be called
* in parallel
*/
static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
const char *fp, int count)
{
struct slip *sl = tty->disc_data;
if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
return;
/* Read the characters out of the buffer */
while (count--) {
if (fp && *fp++) {
if (!test_and_set_bit(SLF_ERROR, &sl->flags))
sl->dev->stats.rx_errors++;
cp++;
continue;
}
#ifdef CONFIG_SLIP_MODE_SLIP6
if (sl->mode & SL_MODE_SLIP6)
slip_unesc6(sl, *cp++);
else
#endif
slip_unesc(sl, *cp++);
}
}
/************************************
* slip_open helper routines.
************************************/
/* Collect hanged up channels */
static void sl_sync(void)
{
int i;
struct net_device *dev;
struct slip *sl;
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (dev == NULL)
break;
sl = netdev_priv(dev);
if (sl->tty || sl->leased)
continue;
if (dev->flags & IFF_UP)
dev_close(dev);
}
}
/* Find a free SLIP channel, and link in this `tty' line. */
static struct slip *sl_alloc(void)
{
int i;
char name[IFNAMSIZ];
struct net_device *dev = NULL;
struct slip *sl;
for (i = 0; i < slip_maxdev; i++) {
dev = slip_devs[i];
if (dev == NULL)
break;
}
/* Sorry, too many, all slots in use */
if (i >= slip_maxdev)
return NULL;
sprintf(name, "sl%d", i);
dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
if (!dev)
return NULL;
dev->base_addr = i;
sl = netdev_priv(dev);
/* Initialize channel control data */
sl->magic = SLIP_MAGIC;
sl->dev = dev;
spin_lock_init(&sl->lock);
INIT_WORK(&sl->tx_work, slip_transmit);
sl->mode = SL_MODE_DEFAULT;
#ifdef CONFIG_SLIP_SMART
/* initialize timer_list struct */
timer_setup(&sl->keepalive_timer, sl_keepalive, 0);
timer_setup(&sl->outfill_timer, sl_outfill, 0);
#endif
slip_devs[i] = dev;
return sl;
}
/*
* Open the high-level part of the SLIP channel.
* This function is called by the TTY module when the
* SLIP line discipline is called for. Because we are
* sure the tty line exists, we only have to link it to
* a free SLIP channel...
*
* Called in process context serialized from other ldisc calls.
*/
static int slip_open(struct tty_struct *tty)
{
struct slip *sl;
int err;
if (!capable(CAP_NET_ADMIN))
return -EPERM;
if (tty->ops->write == NULL)
return -EOPNOTSUPP;
/* RTnetlink lock is misused here to serialize concurrent
opens of slip channels. There are better ways, but it is
the simplest one.
*/
rtnl_lock();
/* Collect hanged up channels. */
sl_sync();
sl = tty->disc_data;
err = -EEXIST;
/* First make sure we're not already connected. */
if (sl && sl->magic == SLIP_MAGIC)
goto err_exit;
/* OK. Find a free SLIP channel to use. */
err = -ENFILE;
sl = sl_alloc();
if (sl == NULL)
goto err_exit;
sl->tty = tty;
tty->disc_data = sl;
sl->pid = current->pid;
if (!test_bit(SLF_INUSE, &sl->flags)) {
/* Perform the low-level SLIP initialization. */
err = sl_alloc_bufs(sl, SL_MTU);
if (err)
goto err_free_chan;
set_bit(SLF_INUSE, &sl->flags);
err = register_netdevice(sl->dev);
if (err)
goto err_free_bufs;
}
#ifdef CONFIG_SLIP_SMART
if (sl->keepalive) {
sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
add_timer(&sl->keepalive_timer);
}
if (sl->outfill) {
sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
add_timer(&sl->outfill_timer);
}
#endif
/* Done. We have linked the TTY line to a channel. */
rtnl_unlock();
tty->receive_room = 65536; /* We don't flow control */
/* TTY layer expects 0 on success */
return 0;
err_free_bufs:
sl_free_bufs(sl);
err_free_chan:
sl->tty = NULL;
tty->disc_data = NULL;
clear_bit(SLF_INUSE, &sl->flags);
sl_free_netdev(sl->dev);
/* do not call free_netdev before rtnl_unlock */
rtnl_unlock();
free_netdev(sl->dev);
return err;
err_exit:
rtnl_unlock();
/* Count references from TTY module */
return err;
}
/*
* Close down a SLIP channel.
* This means flushing out any pending queues, and then returning. This
* call is serialized against other ldisc functions.
*
* We also use this method fo a hangup event
*/
static void slip_close(struct tty_struct *tty)
{
struct slip *sl = tty->disc_data;
/* First make sure we're connected. */
if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
return;
spin_lock_bh(&sl->lock);
rcu_assign_pointer(tty->disc_data, NULL);
sl->tty = NULL;
spin_unlock_bh(&sl->lock);
synchronize_rcu();
flush_work(&sl->tx_work);
/* VSV = very important to remove timers */
#ifdef CONFIG_SLIP_SMART
del_timer_sync(&sl->keepalive_timer);
del_timer_sync(&sl->outfill_timer);
#endif
/* Flush network side */
unregister_netdev(sl->dev);
/* This will complete via sl_free_netdev */
}
static void slip_hangup(struct tty_struct *tty)
{
slip_close(tty);
}
/************************************************************************
* STANDARD SLIP ENCAPSULATION *
************************************************************************/
static int slip_esc(unsigned char *s, unsigned char *d, int len)
{
unsigned char *ptr = d;
unsigned char c;
/*
* Send an initial END character to flush out any
* data that may have accumulated in the receiver
* due to line noise.
*/
*ptr++ = END;
/*
* For each byte in the packet, send the appropriate
* character sequence, according to the SLIP protocol.
*/
while (len-- > 0) {
switch (c = *s++) {
case END:
*ptr++ = ESC;
*ptr++ = ESC_END;
break;
case ESC:
*ptr++ = ESC;
*ptr++ = ESC_ESC;
break;
default:
*ptr++ = c;
break;
}
}
*ptr++ = END;
return ptr - d;
}
static void slip_unesc(struct slip *sl, unsigned char s)
{
switch (s) {
case END:
#ifdef CONFIG_SLIP_SMART
/* drop keeptest bit = VSV */
if (test_bit(SLF_KEEPTEST, &sl->flags))
clear_bit(SLF_KEEPTEST, &sl->flags);
#endif
if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
(sl->rcount > 2))
sl_bump(sl);
clear_bit(SLF_ESCAPE, &sl->flags);
sl->rcount = 0;
return;
case ESC:
set_bit(SLF_ESCAPE, &sl->flags);
return;
case ESC_ESC:
if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
s = ESC;
break;
case ESC_END:
if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
s = END;
break;
}
if (!test_bit(SLF_ERROR, &sl->flags)) {
if (sl->rcount < sl->buffsize) {
sl->rbuff[sl->rcount++] = s;
return;
}
sl->dev->stats.rx_over_errors++;
set_bit(SLF_ERROR, &sl->flags);
}
}
#ifdef CONFIG_SLIP_MODE_SLIP6
/************************************************************************
* 6 BIT SLIP ENCAPSULATION *
************************************************************************/