1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * slip.c This module implements the SLIP protocol for kernel-based
4 * devices like TTY. It interfaces between a raw TTY, and the
5 * kernel's INET protocol layers.
6 *
7 * Version: @(#)slip.c 0.8.3 12/24/94
8 *
9 * Authors: Laurence Culhane, <loz@holmes.demon.co.uk>
10 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
11 *
12 * Fixes:
13 * Alan Cox : Sanity checks and avoid tx overruns.
14 * Has a new sl->mtu field.
15 * Alan Cox : Found cause of overrun. ifconfig sl0
16 * mtu upwards. Driver now spots this
17 * and grows/shrinks its buffers(hack!).
18 * Memory leak if you run out of memory
19 * setting up a slip driver fixed.
20 * Matt Dillon : Printable slip (borrowed from NET2E)
21 * Pauline Middelink : Slip driver fixes.
22 * Alan Cox : Honours the old SL_COMPRESSED flag
23 * Alan Cox : KISS AX.25 and AXUI IP support
24 * Michael Riepe : Automatic CSLIP recognition added
25 * Charles Hedrick : CSLIP header length problem fix.
26 * Alan Cox : Corrected non-IP cases of the above.
27 * Alan Cox : Now uses hardware type as per FvK.
28 * Alan Cox : Default to 192.168.0.0 (RFC 1597)
29 * A.N.Kuznetsov : dev_tint() recursion fix.
30 * Dmitry Gorodchanin : SLIP memory leaks
31 * Dmitry Gorodchanin : Code cleanup. Reduce tty driver
32 * buffering from 4096 to 256 bytes.
33 * Improving SLIP response time.
34 * CONFIG_SLIP_MODE_SLIP6.
35 * ifconfig sl? up & down now works
36 * correctly.
37 * Modularization.
38 * Alan Cox : Oops - fix AX.25 buffer lengths
39 * Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP
40 * statistics. Include CSLIP code only
41 * if it really needed.
42 * Alan Cox : Free slhc buffers in the right place.
43 * Alan Cox : Allow for digipeated IP over AX.25
44 * Matti Aarnio : Dynamic SLIP devices, with ideas taken
45 * from Jim Freeman's <jfree@caldera.com>
46 * dynamic PPP devices. We do NOT kfree()
47 * device entries, just reg./unreg. them
48 * as they are needed. We kfree() them
49 * at module cleanup.
50 * With MODULE-loading ``insmod'', user
51 * can issue parameter: slip_maxdev=1024
52 * (Or how much he/she wants.. Default
53 * is 256)
54 * Stanislav Voronyi : Slip line checking, with ideas taken
55 * from multislip BSDI driver which was
56 * written by Igor Chechik, RELCOM Corp.
57 * Only algorithms have been ported to
58 * Linux SLIP driver.
59 * Vitaly E. Lavrov : Sane behaviour on tty hangup.
60 * Alexey Kuznetsov : Cleanup interfaces to tty & netdevice
61 * modules.
62 */
63
64 #define SL_CHECK_TRANSMIT
65 #include <linux/module.h>
66 #include <linux/moduleparam.h>
67
68 #include <linux/uaccess.h>
69 #include <linux/bitops.h>
70 #include <linux/sched/signal.h>
71 #include <linux/string.h>
72 #include <linux/mm.h>
73 #include <linux/interrupt.h>
74 #include <linux/in.h>
75 #include <linux/tty.h>
76 #include <linux/errno.h>
77 #include <linux/netdevice.h>
78 #include <linux/etherdevice.h>
79 #include <linux/skbuff.h>
80 #include <linux/rtnetlink.h>
81 #include <linux/if_arp.h>
82 #include <linux/if_slip.h>
83 #include <linux/delay.h>
84 #include <linux/init.h>
85 #include <linux/slab.h>
86 #include <linux/workqueue.h>
87 #include "slip.h"
88 #ifdef CONFIG_INET
89 #include <linux/ip.h>
90 #include <linux/tcp.h>
91 #include <net/slhc_vj.h>
92 #endif
93
94 #define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
95
96 static struct net_device **slip_devs;
97
98 static int slip_maxdev = SL_NRUNIT;
99 module_param(slip_maxdev, int, 0);
100 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
101
102 static int slip_esc(unsigned char *p, unsigned char *d, int len);
103 static void slip_unesc(struct slip *sl, unsigned char c);
104 #ifdef CONFIG_SLIP_MODE_SLIP6
105 static int slip_esc6(unsigned char *p, unsigned char *d, int len);
106 static void slip_unesc6(struct slip *sl, unsigned char c);
107 #endif
108 #ifdef CONFIG_SLIP_SMART
109 static void sl_keepalive(struct timer_list *t);
110 static void sl_outfill(struct timer_list *t);
111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
112 #endif
113
114 /********************************
115 * Buffer administration routines:
116 * sl_alloc_bufs()
117 * sl_free_bufs()
118 * sl_realloc_bufs()
119 *
120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
121 * sl_realloc_bufs provides strong atomicity and reallocation
122 * on actively running device.
123 *********************************/
124
125 /*
126 Allocate channel buffers.
127 */
128
sl_alloc_bufs(struct slip * sl,int mtu)129 static int sl_alloc_bufs(struct slip *sl, int mtu)
130 {
131 int err = -ENOBUFS;
132 unsigned long len;
133 char *rbuff = NULL;
134 char *xbuff = NULL;
135 #ifdef SL_INCLUDE_CSLIP
136 char *cbuff = NULL;
137 struct slcompress *slcomp = NULL;
138 #endif
139
140 /*
141 * Allocate the SLIP frame buffers:
142 *
143 * rbuff Receive buffer.
144 * xbuff Transmit buffer.
145 * cbuff Temporary compression buffer.
146 */
147 len = mtu * 2;
148
149 /*
150 * allow for arrival of larger UDP packets, even if we say not to
151 * also fixes a bug in which SunOS sends 512-byte packets even with
152 * an MSS of 128
153 */
154 if (len < 576 * 2)
155 len = 576 * 2;
156 rbuff = kmalloc(len + 4, GFP_KERNEL);
157 if (rbuff == NULL)
158 goto err_exit;
159 xbuff = kmalloc(len + 4, GFP_KERNEL);
160 if (xbuff == NULL)
161 goto err_exit;
162 #ifdef SL_INCLUDE_CSLIP
163 cbuff = kmalloc(len + 4, GFP_KERNEL);
164 if (cbuff == NULL)
165 goto err_exit;
166 slcomp = slhc_init(16, 16);
167 if (IS_ERR(slcomp))
168 goto err_exit;
169 #endif
170 spin_lock_bh(&sl->lock);
171 if (sl->tty == NULL) {
172 spin_unlock_bh(&sl->lock);
173 err = -ENODEV;
174 goto err_exit;
175 }
176 sl->mtu = mtu;
177 sl->buffsize = len;
178 sl->rcount = 0;
179 sl->xleft = 0;
180 rbuff = xchg(&sl->rbuff, rbuff);
181 xbuff = xchg(&sl->xbuff, xbuff);
182 #ifdef SL_INCLUDE_CSLIP
183 cbuff = xchg(&sl->cbuff, cbuff);
184 slcomp = xchg(&sl->slcomp, slcomp);
185 #endif
186 #ifdef CONFIG_SLIP_MODE_SLIP6
187 sl->xdata = 0;
188 sl->xbits = 0;
189 #endif
190 spin_unlock_bh(&sl->lock);
191 err = 0;
192
193 /* Cleanup */
194 err_exit:
195 #ifdef SL_INCLUDE_CSLIP
196 kfree(cbuff);
197 slhc_free(slcomp);
198 #endif
199 kfree(xbuff);
200 kfree(rbuff);
201 return err;
202 }
203
204 /* Free a SLIP channel buffers. */
sl_free_bufs(struct slip * sl)205 static void sl_free_bufs(struct slip *sl)
206 {
207 /* Free all SLIP frame buffers. */
208 kfree(xchg(&sl->rbuff, NULL));
209 kfree(xchg(&sl->xbuff, NULL));
210 #ifdef SL_INCLUDE_CSLIP
211 kfree(xchg(&sl->cbuff, NULL));
212 slhc_free(xchg(&sl->slcomp, NULL));
213 #endif
214 }
215
216 /*
217 Reallocate slip channel buffers.
218 */
219
sl_realloc_bufs(struct slip * sl,int mtu)220 static int sl_realloc_bufs(struct slip *sl, int mtu)
221 {
222 int err = 0;
223 struct net_device *dev = sl->dev;
224 unsigned char *xbuff, *rbuff;
225 #ifdef SL_INCLUDE_CSLIP
226 unsigned char *cbuff;
227 #endif
228 int len = mtu * 2;
229
230 /*
231 * allow for arrival of larger UDP packets, even if we say not to
232 * also fixes a bug in which SunOS sends 512-byte packets even with
233 * an MSS of 128
234 */
235 if (len < 576 * 2)
236 len = 576 * 2;
237
238 xbuff = kmalloc(len + 4, GFP_ATOMIC);
239 rbuff = kmalloc(len + 4, GFP_ATOMIC);
240 #ifdef SL_INCLUDE_CSLIP
241 cbuff = kmalloc(len + 4, GFP_ATOMIC);
242 #endif
243
244
245 #ifdef SL_INCLUDE_CSLIP
246 if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
247 #else
248 if (xbuff == NULL || rbuff == NULL) {
249 #endif
250 if (mtu > sl->mtu) {
251 printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
252 dev->name);
253 err = -ENOBUFS;
254 }
255 goto done;
256 }
257 spin_lock_bh(&sl->lock);
258
259 err = -ENODEV;
260 if (sl->tty == NULL)
261 goto done_on_bh;
262
263 xbuff = xchg(&sl->xbuff, xbuff);
264 rbuff = xchg(&sl->rbuff, rbuff);
265 #ifdef SL_INCLUDE_CSLIP
266 cbuff = xchg(&sl->cbuff, cbuff);
267 #endif
268 if (sl->xleft) {
269 if (sl->xleft <= len) {
270 memcpy(sl->xbuff, sl->xhead, sl->xleft);
271 } else {
272 sl->xleft = 0;
273 dev->stats.tx_dropped++;
274 }
275 }
276 sl->xhead = sl->xbuff;
277
278 if (sl->rcount) {
279 if (sl->rcount <= len) {
280 memcpy(sl->rbuff, rbuff, sl->rcount);
281 } else {
282 sl->rcount = 0;
283 dev->stats.rx_over_errors++;
284 set_bit(SLF_ERROR, &sl->flags);
285 }
286 }
287 sl->mtu = mtu;
288 dev->mtu = mtu;
289 sl->buffsize = len;
290 err = 0;
291
292 done_on_bh:
293 spin_unlock_bh(&sl->lock);
294
295 done:
296 kfree(xbuff);
297 kfree(rbuff);
298 #ifdef SL_INCLUDE_CSLIP
299 kfree(cbuff);
300 #endif
301 return err;
302 }
303
304
305 /* Set the "sending" flag. This must be atomic hence the set_bit. */
306 static inline void sl_lock(struct slip *sl)
307 {
308 netif_stop_queue(sl->dev);
309 }
310
311
312 /* Clear the "sending" flag. This must be atomic, hence the ASM. */
313 static inline void sl_unlock(struct slip *sl)
314 {
315 netif_wake_queue(sl->dev);
316 }
317
318 /* Send one completely decapsulated IP datagram to the IP layer. */
319 static void sl_bump(struct slip *sl)
320 {
321 struct net_device *dev = sl->dev;
322 struct sk_buff *skb;
323 int count;
324
325 count = sl->rcount;
326 #ifdef SL_INCLUDE_CSLIP
327 if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
328 unsigned char c = sl->rbuff[0];
329 if (c & SL_TYPE_COMPRESSED_TCP) {
330 /* ignore compressed packets when CSLIP is off */
331 if (!(sl->mode & SL_MODE_CSLIP)) {
332 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
333 return;
334 }
335 /* make sure we've reserved enough space for uncompress
336 to use */
337 if (count + 80 > sl->buffsize) {
338 dev->stats.rx_over_errors++;
339 return;
340 }
341 count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
342 if (count <= 0)
343 return;
344 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
345 if (!(sl->mode & SL_MODE_CSLIP)) {
346 /* turn on header compression */
347 sl->mode |= SL_MODE_CSLIP;
348 sl->mode &= ~SL_MODE_ADAPTIVE;
349 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
350 }
351 sl->rbuff[0] &= 0x4f;
352 if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
353 return;
354 }
355 }
356 #endif /* SL_INCLUDE_CSLIP */
357
358 dev->stats.rx_bytes += count;
359
360 skb = dev_alloc_skb(count);
361 if (skb == NULL) {
362 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
363 dev->stats.rx_dropped++;
364 return;
365 }
366 skb->dev = dev;
367 skb_put_data(skb, sl->rbuff, count);
368 skb_reset_mac_header(skb);
369 skb->protocol = htons(ETH_P_IP);
370 netif_rx_ni(skb);
371 dev->stats.rx_packets++;
372 }
373
374 /* Encapsulate one IP datagram and stuff into a TTY queue. */
375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
376 {
377 unsigned char *p;
378 int actual, count;
379
380 if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */
381 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
382 sl->dev->stats.tx_dropped++;
383 sl_unlock(sl);
384 return;
385 }
386
387 p = icp;
388 #ifdef SL_INCLUDE_CSLIP
389 if (sl->mode & SL_MODE_CSLIP)
390 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
391 #endif
392 #ifdef CONFIG_SLIP_MODE_SLIP6
393 if (sl->mode & SL_MODE_SLIP6)
394 count = slip_esc6(p, sl->xbuff, len);
395 else
396 #endif
397 count = slip_esc(p, sl->xbuff, len);
398
399 /* Order of next two lines is *very* important.
400 * When we are sending a little amount of data,
401 * the transfer may be completed inside the ops->write()
402 * routine, because it's running with interrupts enabled.
403 * In this case we *never* got WRITE_WAKEUP event,
404 * if we did not request it before write operation.
405 * 14 Oct 1994 Dmitry Gorodchanin.
406 */
407 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
408 actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
409 #ifdef SL_CHECK_TRANSMIT
410 netif_trans_update(sl->dev);
411 #endif
412 sl->xleft = count - actual;
413 sl->xhead = sl->xbuff + actual;
414 #ifdef CONFIG_SLIP_SMART
415 /* VSV */
416 clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
417 #endif
418 }
419
420 /* Write out any remaining transmit buffer. Scheduled when tty is writable */
421 static void slip_transmit(struct work_struct *work)
422 {
423 struct slip *sl = container_of(work, struct slip, tx_work);
424 int actual;
425
426 spin_lock_bh(&sl->lock);
427 /* First make sure we're connected. */
428 if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
429 spin_unlock_bh(&sl->lock);
430 return;
431 }
432
433 if (sl->xleft <= 0) {
434 /* Now serial buffer is almost free & we can start
435 * transmission of another packet */
436 sl->dev->stats.tx_packets++;
437 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
438 spin_unlock_bh(&sl->lock);
439 sl_unlock(sl);
440 return;
441 }
442
443 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
444 sl->xleft -= actual;
445 sl->xhead += actual;
446 spin_unlock_bh(&sl->lock);
447 }
448
449 /*
450 * Called by the driver when there's room for more data.
451 * Schedule the transmit.
452 */
453 static void slip_write_wakeup(struct tty_struct *tty)
454 {
455 struct slip *sl;
456
457 rcu_read_lock();
458 sl = rcu_dereference(tty->disc_data);
459 if (sl)
460 schedule_work(&sl->tx_work);
461 rcu_read_unlock();
462 }
463
464 static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue)
465 {
466 struct slip *sl = netdev_priv(dev);
467
468 spin_lock(&sl->lock);
469
470 if (netif_queue_stopped(dev)) {
471 if (!netif_running(dev))
472 goto out;
473
474 /* May be we must check transmitter timeout here ?
475 * 14 Oct 1994 Dmitry Gorodchanin.
476 */
477 #ifdef SL_CHECK_TRANSMIT
478 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) {
479 /* 20 sec timeout not reached */
480 goto out;
481 }
482 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
483 dev->name,
484 (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
485 "bad line quality" : "driver error");
486 sl->xleft = 0;
487 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
488 sl_unlock(sl);
489 #endif
490 }
491 out:
492 spin_unlock(&sl->lock);
493 }
494
495
496 /* Encapsulate an IP datagram and kick it into a TTY queue. */
497 static netdev_tx_t
498 sl_xmit(struct sk_buff *skb, struct net_device *dev)
499 {
500 struct slip *sl = netdev_priv(dev);
501
502 spin_lock(&sl->lock);
503 if (!netif_running(dev)) {
504 spin_unlock(&sl->lock);
505 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
506 dev_kfree_skb(skb);
507 return NETDEV_TX_OK;
508 }
509 if (sl->tty == NULL) {
510 spin_unlock(&sl->lock);
511 dev_kfree_skb(skb);
512 return NETDEV_TX_OK;
513 }
514
515 sl_lock(sl);
516 dev->stats.tx_bytes += skb->len;
517 sl_encaps(sl, skb->data, skb->len);
518 spin_unlock(&sl->lock);
519
520 dev_kfree_skb(skb);
521 return NETDEV_TX_OK;
522 }
523
524
525 /******************************************
526 * Routines looking at netdevice side.
527 ******************************************/
528
529 /* Netdevice UP -> DOWN routine */
530
531 static int
532 sl_close(struct net_device *dev)
533 {
534 struct slip *sl = netdev_priv(dev);
535
536 spin_lock_bh(&sl->lock);
537 if (sl->tty)
538 /* TTY discipline is running. */
539 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
540 netif_stop_queue(dev);
541 sl->rcount = 0;
542 sl->xleft = 0;
543 spin_unlock_bh(&sl->lock);
544
545 return 0;
546 }
547
548 /* Netdevice DOWN -> UP routine */
549
550 static int sl_open(struct net_device *dev)
551 {
552 struct slip *sl = netdev_priv(dev);
553
554 if (sl->tty == NULL)
555 return -ENODEV;
556
557 sl->flags &= (1 << SLF_INUSE);
558 netif_start_queue(dev);
559 return 0;
560 }
561
562 /* Netdevice change MTU request */
563
564 static int sl_change_mtu(struct net_device *dev, int new_mtu)
565 {
566 struct slip *sl = netdev_priv(dev);
567
568 return sl_realloc_bufs(sl, new_mtu);
569 }
570
571 /* Netdevice get statistics request */
572
573 static void
574 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
575 {
576 struct net_device_stats *devstats = &dev->stats;
577 #ifdef SL_INCLUDE_CSLIP
578 struct slip *sl = netdev_priv(dev);
579 struct slcompress *comp = sl->slcomp;
580 #endif
581 stats->rx_packets = devstats->rx_packets;
582 stats->tx_packets = devstats->tx_packets;
583 stats->rx_bytes = devstats->rx_bytes;
584 stats->tx_bytes = devstats->tx_bytes;
585 stats->rx_dropped = devstats->rx_dropped;
586 stats->tx_dropped = devstats->tx_dropped;
587 stats->tx_errors = devstats->tx_errors;
588 stats->rx_errors = devstats->rx_errors;
589 stats->rx_over_errors = devstats->rx_over_errors;
590
591 #ifdef SL_INCLUDE_CSLIP
592 if (comp) {
593 /* Generic compressed statistics */
594 stats->rx_compressed = comp->sls_i_compressed;
595 stats->tx_compressed = comp->sls_o_compressed;
596
597 /* Are we really still needs this? */
598 stats->rx_fifo_errors += comp->sls_i_compressed;
599 stats->rx_dropped += comp->sls_i_tossed;
600 stats->tx_fifo_errors += comp->sls_o_compressed;
601 stats->collisions += comp->sls_o_misses;
602 }
603 #endif
604 }
605
606 /* Netdevice register callback */
607
608 static int sl_init(struct net_device *dev)
609 {
610 struct slip *sl = netdev_priv(dev);
611
612 /*
613 * Finish setting up the DEVICE info.
614 */
615
616 dev->mtu = sl->mtu;
617 dev->type = ARPHRD_SLIP + sl->mode;
618 #ifdef SL_CHECK_TRANSMIT
619 dev->watchdog_timeo = 20*HZ;
620 #endif
621 return 0;
622 }
623
624
625 static void sl_uninit(struct net_device *dev)
626 {
627 struct slip *sl = netdev_priv(dev);
628
629 sl_free_bufs(sl);
630 }
631
632 /* Hook the destructor so we can free slip devices at the right point in time */
633 static void sl_free_netdev(struct net_device *dev)
634 {
635 int i = dev->base_addr;
636
637 slip_devs[i] = NULL;
638 }
639
640 static const struct net_device_ops sl_netdev_ops = {
641 .ndo_init = sl_init,
642 .ndo_uninit = sl_uninit,
643 .ndo_open = sl_open,
644 .ndo_stop = sl_close,
645 .ndo_start_xmit = sl_xmit,
646 .ndo_get_stats64 = sl_get_stats64,
647 .ndo_change_mtu = sl_change_mtu,
648 .ndo_tx_timeout = sl_tx_timeout,
649 #ifdef CONFIG_SLIP_SMART
650 .ndo_do_ioctl = sl_ioctl,
651 #endif
652 };
653
654
655 static void sl_setup(struct net_device *dev)
656 {
657 dev->netdev_ops = &sl_netdev_ops;
658 dev->needs_free_netdev = true;
659 dev->priv_destructor = sl_free_netdev;
660
661 dev->hard_header_len = 0;
662 dev->addr_len = 0;
663 dev->tx_queue_len = 10;
664
665 /* MTU range: 68 - 65534 */
666 dev->min_mtu = 68;
667 dev->max_mtu = 65534;
668
669 /* New-style flags. */
670 dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
671 }
672
673 /******************************************
674 Routines looking at TTY side.
675 ******************************************/
676
677
678 /*
679 * Handle the 'receiver data ready' interrupt.
680 * This function is called by the 'tty_io' module in the kernel when
681 * a block of SLIP data has been received, which can now be decapsulated
682 * and sent on to some IP layer for further processing. This will not
683 * be re-entered while running but other ldisc functions may be called
684 * in parallel
685 */
686
687 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp,
688 char *fp, int count)
689 {
690 struct slip *sl = tty->disc_data;
691
692 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
693 return;
694
695 /* Read the characters out of the buffer */
696 while (count--) {
697 if (fp && *fp++) {
698 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
699 sl->dev->stats.rx_errors++;
700 cp++;
701 continue;
702 }
703 #ifdef CONFIG_SLIP_MODE_SLIP6
704 if (sl->mode & SL_MODE_SLIP6)
705 slip_unesc6(sl, *cp++);
706 else
707 #endif
708 slip_unesc(sl, *cp++);
709 }
710 }
711
712 /************************************
713 * slip_open helper routines.
714 ************************************/
715
716 /* Collect hanged up channels */
717 static void sl_sync(void)
718 {
719 int i;
720 struct net_device *dev;
721 struct slip *sl;
722
723 for (i = 0; i < slip_maxdev; i++) {
724 dev = slip_devs[i];
725 if (dev == NULL)
726 break;
727
728 sl = netdev_priv(dev);
729 if (sl->tty || sl->leased)
730 continue;
731 if (dev->flags & IFF_UP)
732 dev_close(dev);
733 }
734 }
735
736
737 /* Find a free SLIP channel, and link in this `tty' line. */
738 static struct slip *sl_alloc(void)
739 {
740 int i;
741 char name[IFNAMSIZ];
742 struct net_device *dev = NULL;
743 struct slip *sl;
744
745 for (i = 0; i < slip_maxdev; i++) {
746 dev = slip_devs[i];
747 if (dev == NULL)
748 break;
749 }
750 /* Sorry, too many, all slots in use */
751 if (i >= slip_maxdev)
752 return NULL;
753
754 sprintf(name, "sl%d", i);
755 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
756 if (!dev)
757 return NULL;
758
759 dev->base_addr = i;
760 sl = netdev_priv(dev);
761
762 /* Initialize channel control data */
763 sl->magic = SLIP_MAGIC;
764 sl->dev = dev;
765 spin_lock_init(&sl->lock);
766 INIT_WORK(&sl->tx_work, slip_transmit);
767 sl->mode = SL_MODE_DEFAULT;
768 #ifdef CONFIG_SLIP_SMART
769 /* initialize timer_list struct */
770 timer_setup(&sl->keepalive_timer, sl_keepalive, 0);
771 timer_setup(&sl->outfill_timer, sl_outfill, 0);
772 #endif
773 slip_devs[i] = dev;
774 return sl;
775 }
776
777 /*
778 * Open the high-level part of the SLIP channel.
779 * This function is called by the TTY module when the
780 * SLIP line discipline is called for. Because we are
781 * sure the tty line exists, we only have to link it to
782 * a free SLIP channel...
783 *
784 * Called in process context serialized from other ldisc calls.
785 */
786
787 static int slip_open(struct tty_struct *tty)
788 {
789 struct slip *sl;
790 int err;
791
792 if (!capable(CAP_NET_ADMIN))
793 return -EPERM;
794
795 if (tty->ops->write == NULL)
796 return -EOPNOTSUPP;
797
798 /* RTnetlink lock is misused here to serialize concurrent
799 opens of slip channels. There are better ways, but it is
800 the simplest one.
801 */
802 rtnl_lock();
803
804 /* Collect hanged up channels. */
805 sl_sync();
806
807 sl = tty->disc_data;
808
809 err = -EEXIST;
810 /* First make sure we're not already connected. */
811 if (sl && sl->magic == SLIP_MAGIC)
812 goto err_exit;
813
814 /* OK. Find a free SLIP channel to use. */
815 err = -ENFILE;
816 sl = sl_alloc();
817 if (sl == NULL)
818 goto err_exit;
819
820 sl->tty = tty;
821 tty->disc_data = sl;
822 sl->pid = current->pid;
823
824 if (!test_bit(SLF_INUSE, &sl->flags)) {
825 /* Perform the low-level SLIP initialization. */
826 err = sl_alloc_bufs(sl, SL_MTU);
827 if (err)
828 goto err_free_chan;
829
830 set_bit(SLF_INUSE, &sl->flags);
831
832 err = register_netdevice(sl->dev);
833 if (err)
834 goto err_free_bufs;
835 }
836
837 #ifdef CONFIG_SLIP_SMART
838 if (sl->keepalive) {
839 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
840 add_timer(&sl->keepalive_timer);
841 }
842 if (sl->outfill) {
843 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
844 add_timer(&sl->outfill_timer);
845 }
846 #endif
847
848 /* Done. We have linked the TTY line to a channel. */
849 rtnl_unlock();
850 tty->receive_room = 65536; /* We don't flow control */
851
852 /* TTY layer expects 0 on success */
853 return 0;
854
855 err_free_bufs:
856 sl_free_bufs(sl);
857
858 err_free_chan:
859 sl->tty = NULL;
860 tty->disc_data = NULL;
861 clear_bit(SLF_INUSE, &sl->flags);
862 sl_free_netdev(sl->dev);
863 /* do not call free_netdev before rtnl_unlock */
864 rtnl_unlock();
865 free_netdev(sl->dev);
866 return err;
867
868 err_exit:
869 rtnl_unlock();
870
871 /* Count references from TTY module */
872 return err;
873 }
874
875 /*
876 * Close down a SLIP channel.
877 * This means flushing out any pending queues, and then returning. This
878 * call is serialized against other ldisc functions.
879 *
880 * We also use this method fo a hangup event
881 */
882
883 static void slip_close(struct tty_struct *tty)
884 {
885 struct slip *sl = tty->disc_data;
886
887 /* First make sure we're connected. */
888 if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
889 return;
890
891 spin_lock_bh(&sl->lock);
892 rcu_assign_pointer(tty->disc_data, NULL);
893 sl->tty = NULL;
894 spin_unlock_bh(&sl->lock);
895
896 synchronize_rcu();
897 flush_work(&sl->tx_work);
898
899 /* VSV = very important to remove timers */
900 #ifdef CONFIG_SLIP_SMART
901 del_timer_sync(&sl->keepalive_timer);
902 del_timer_sync(&sl->outfill_timer);
903 #endif
904 /* Flush network side */
905 unregister_netdev(sl->dev);
906 /* This will complete via sl_free_netdev */
907 }
908
909 static int slip_hangup(struct tty_struct *tty)
910 {
911 slip_close(tty);
912 return 0;
913 }
914 /************************************************************************
915 * STANDARD SLIP ENCAPSULATION *
916 ************************************************************************/
917
918 static int slip_esc(unsigned char *s, unsigned char *d, int len)
919 {
920 unsigned char *ptr = d;
921 unsigned char c;
922
923 /*
924 * Send an initial END character to flush out any
925 * data that may have accumulated in the receiver
926 * due to line noise.
927 */
928
929 *ptr++ = END;
930
931 /*
932 * For each byte in the packet, send the appropriate
933 * character sequence, according to the SLIP protocol.
934 */
935
936 while (len-- > 0) {
937 switch (c = *s++) {
938 case END:
939 *ptr++ = ESC;
940 *ptr++ = ESC_END;
941 break;
942 case ESC:
943 *ptr++ = ESC;
944 *ptr++ = ESC_ESC;
945 break;
946 default:
947 *ptr++ = c;
948 break;
949 }
950 }
951 *ptr++ = END;
952 return ptr - d;
953 }
954
955 static void slip_unesc(struct slip *sl, unsigned char s)
956 {
957
958 switch (s) {
959 case END:
960 #ifdef CONFIG_SLIP_SMART
961 /* drop keeptest bit = VSV */
962 if (test_bit(SLF_KEEPTEST, &sl->flags))
963 clear_bit(SLF_KEEPTEST, &sl->flags);
964 #endif
965
966 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
967 (sl->rcount > 2))
968 sl_bump(sl);
969 clear_bit(SLF_ESCAPE, &sl->flags);
970 sl->rcount = 0;
971 return;
972
973 case ESC:
974 set_bit(SLF_ESCAPE, &sl->flags);
975 return;
976 case ESC_ESC:
977 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
978 s = ESC;
979 break;
980 case ESC_END:
981 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
982 s = END;
983 break;
984 }
985 if (!test_bit(SLF_ERROR, &sl->flags)) {
986 if (sl->rcount < sl->buffsize) {
987 sl->rbuff[sl->rcount++] = s;
988 return;
989 }
990 sl->dev->stats.rx_over_errors++;
991 set_bit(SLF_ERROR, &sl->flags);
992 }
993 }
994
995
996 #ifdef CONFIG_SLIP_MODE_SLIP6
997 /************************************************************************
998 * 6 BIT SLIP ENCAPSULATION *
999 ************************************************************************/
1000
1001 static int slip_esc6(unsigned char *s, unsigned char *d, int len)
1002 {
1003 unsigned char *ptr = d;
1004 unsigned char c;
1005 int i;
1006 unsigned short v = 0;
1007 short bits = 0;
1008
1009 /*
1010 * Send an initial END character to flush out any
1011 * data that may have accumulated in the receiver
1012 * due to line noise.
1013 */
1014
1015 *ptr++ = 0x70;
1016
1017 /*
1018 * Encode the packet into printable ascii characters
1019 */
1020
1021 for (i = 0; i < len; ++i) {
1022 v = (v << 8) | s[i];
1023 bits += 8;
1024 while (bits >= 6) {
1025 bits -= 6;
1026 c = 0x30 + ((v >> bits) & 0x3F);
1027 *ptr++ = c;
1028 }
1029 }
1030 if (bits) {
1031 c = 0x30 + ((v << (6 - bits)) & 0x3F);
1032 *ptr++ = c;
1033 }
1034 *ptr++ = 0x70;
1035 return ptr - d;
1036 }
1037
1038 static void slip_unesc6(struct slip *sl, unsigned char s)
1039 {
1040 unsigned char c;
1041
1042 if (s == 0x70) {
1043 #ifdef CONFIG_SLIP_SMART
1044 /* drop keeptest bit = VSV */
1045 if (test_bit(SLF_KEEPTEST, &sl->flags))
1046 clear_bit(SLF_KEEPTEST, &sl->flags);
1047 #endif
1048
1049 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
1050 (sl->rcount > 2))
1051 sl_bump(sl);
1052 sl->rcount = 0;
1053 sl->xbits = 0;
1054 sl->xdata = 0;
1055 } else if (s >= 0x30 && s < 0x70) {
1056 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F);
1057 sl->xbits += 6;
1058 if (sl->xbits >= 8) {
1059 sl->xbits -= 8;
1060 c = (unsigned char)(sl->xdata >> sl->xbits);
1061 if (!test_bit(SLF_ERROR, &sl->flags)) {
1062 if (sl->rcount < sl->buffsize) {
1063 sl->rbuff[sl->rcount++] = c;
1064 return;
1065 }
1066 sl->dev->stats.rx_over_errors++;
1067 set_bit(SLF_ERROR, &sl->flags);
1068 }
1069 }
1070 }
1071 }
1072 #endif /* CONFIG_SLIP_MODE_SLIP6 */
1073
1074 /* Perform I/O control on an active SLIP channel. */
1075 static int slip_ioctl(struct tty_struct *tty, struct file *file,
1076 unsigned int cmd, unsigned long arg)
1077 {
1078 struct slip *sl = tty->disc_data;
1079 unsigned int tmp;
1080 int __user *p = (int __user *)arg;
1081
1082 /* First make sure we're connected. */
1083 if (!sl || sl->magic != SLIP_MAGIC)
1084 return -EINVAL;
1085
1086 switch (cmd) {
1087 case SIOCGIFNAME:
1088 tmp = strlen(sl->dev->name) + 1;
1089 if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
1090 return -EFAULT;
1091 return 0;
1092
1093 case SIOCGIFENCAP:
1094 if (put_user(sl->mode, p))
1095 return -EFAULT;
1096 return 0;
1097
1098 case SIOCSIFENCAP:
1099 if (get_user(tmp, p))
1100 return -EFAULT;
1101 #ifndef SL_INCLUDE_CSLIP
1102 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE))
1103 return -EINVAL;
1104 #else
1105 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) ==
1106 (SL_MODE_ADAPTIVE | SL_MODE_CSLIP))
1107 /* return -EINVAL; */
1108 tmp &= ~SL_MODE_ADAPTIVE;
1109 #endif
1110 #ifndef CONFIG_SLIP_MODE_SLIP6
1111 if (tmp & SL_MODE_SLIP6)
1112 return -EINVAL;
1113 #endif
1114 sl->mode = tmp;
1115 sl->dev->type = ARPHRD_SLIP + sl->mode;
1116 return 0;
1117
1118 case SIOCSIFHWADDR:
1119 return -EINVAL;
1120
1121 #ifdef CONFIG_SLIP_SMART
1122 /* VSV changes start here */
1123 case SIOCSKEEPALIVE:
1124 if (get_user(tmp, p))
1125 return -EFAULT;
1126 if (tmp > 255) /* max for unchar */
1127 return -EINVAL;
1128
1129 spin_lock_bh(&sl->lock);
1130 if (!sl->tty) {
1131 spin_unlock_bh(&sl->lock);
1132 return -ENODEV;
1133 }
1134 sl->keepalive = (u8)tmp;
1135 if (sl->keepalive != 0) {
1136 mod_timer(&sl->keepalive_timer,
1137 jiffies + sl->keepalive * HZ);
1138 set_bit(SLF_KEEPTEST, &sl->flags);
1139 } else
1140 del_timer(&sl->keepalive_timer);
1141 spin_unlock_bh(&sl->lock);
1142 return 0;
1143
1144 case SIOCGKEEPALIVE:
1145 if (put_user(sl->keepalive, p))
1146 return -EFAULT;
1147 return 0;
1148
1149 case SIOCSOUTFILL:
1150 if (get_user(tmp, p))
1151 return -EFAULT;
1152 if (tmp > 255) /* max for unchar */
1153 return -EINVAL;
1154 spin_lock_bh(&sl->lock);
1155 if (!sl->tty) {
1156 spin_unlock_bh(&sl->lock);
1157 return -ENODEV;
1158 }
1159 sl->outfill = (u8)tmp;
1160 if (sl->outfill != 0) {
1161 mod_timer(&sl->outfill_timer,
1162 jiffies + sl->outfill * HZ);
1163 set_bit(SLF_OUTWAIT, &sl->flags);
1164 } else
1165 del_timer(&sl->outfill_timer);
1166 spin_unlock_bh(&sl->lock);
1167 return 0;
1168
1169 case SIOCGOUTFILL:
1170 if (put_user(sl->outfill, p))
1171 return -EFAULT;
1172 return 0;
1173 /* VSV changes end */
1174 #endif
1175 default:
1176 return tty_mode_ioctl(tty, file, cmd, arg);
1177 }
1178 }
1179
1180 /* VSV changes start here */
1181 #ifdef CONFIG_SLIP_SMART
1182 /* function do_ioctl called from net/core/dev.c
1183 to allow get/set outfill/keepalive parameter
1184 by ifconfig */
1185
1186 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
1187 {
1188 struct slip *sl = netdev_priv(dev);
1189 unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1190
1191 if (sl == NULL) /* Allocation failed ?? */
1192 return -ENODEV;
1193
1194 spin_lock_bh(&sl->lock);
1195
1196 if (!sl->tty) {
1197 spin_unlock_bh(&sl->lock);
1198 return -ENODEV;
1199 }
1200
1201 switch (cmd) {
1202 case SIOCSKEEPALIVE:
1203 /* max for unchar */
1204 if ((unsigned)*p > 255) {
1205 spin_unlock_bh(&sl->lock);
1206 return -EINVAL;
1207 }
1208 sl->keepalive = (u8)*p;
1209 if (sl->keepalive != 0) {
1210 sl->keepalive_timer.expires =
1211 jiffies + sl->keepalive * HZ;
1212 mod_timer(&sl->keepalive_timer,
1213 jiffies + sl->keepalive * HZ);
1214 set_bit(SLF_KEEPTEST, &sl->flags);
1215 } else
1216 del_timer(&sl->keepalive_timer);
1217 break;
1218
1219 case SIOCGKEEPALIVE:
1220 *p = sl->keepalive;
1221 break;
1222
1223 case SIOCSOUTFILL:
1224 if ((unsigned)*p > 255) { /* max for unchar */
1225 spin_unlock_bh(&sl->lock);
1226 return -EINVAL;
1227 }
1228 sl->outfill = (u8)*p;
1229 if (sl->outfill != 0) {
1230 mod_timer(&sl->outfill_timer,
1231 jiffies + sl->outfill * HZ);
1232 set_bit(SLF_OUTWAIT, &sl->flags);
1233 } else
1234 del_timer(&sl->outfill_timer);
1235 break;
1236
1237 case SIOCGOUTFILL:
1238 *p = sl->outfill;
1239 break;
1240
1241 case SIOCSLEASE:
1242 /* Resolve race condition, when ioctl'ing hanged up
1243 and opened by another process device.
1244 */
1245 if (sl->tty != current->signal->tty &&
1246 sl->pid != current->pid) {
1247 spin_unlock_bh(&sl->lock);
1248 return -EPERM;
1249 }
1250 sl->leased = 0;
1251 if (*p)
1252 sl->leased = 1;
1253 break;
1254
1255 case SIOCGLEASE:
1256 *p = sl->leased;
1257 }
1258 spin_unlock_bh(&sl->lock);
1259 return 0;
1260 }
1261 #endif
1262 /* VSV changes end */
1263
1264 static struct tty_ldisc_ops sl_ldisc = {
1265 .owner = THIS_MODULE,
1266 .name = "slip",
1267 .open = slip_open,
1268 .close = slip_close,
1269 .hangup = slip_hangup,
1270 .ioctl = slip_ioctl,
1271 .receive_buf = slip_receive_buf,
1272 .write_wakeup = slip_write_wakeup,
1273 };
1274
1275 static int __init slip_init(void)
1276 {
1277 int status;
1278
1279 if (slip_maxdev < 4)
1280 slip_maxdev = 4; /* Sanity */
1281
1282 printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1283 #ifdef CONFIG_SLIP_MODE_SLIP6
1284 " (6 bit encapsulation enabled)"
1285 #endif
1286 ".\n",
1287 SLIP_VERSION, slip_maxdev);
1288 #if defined(SL_INCLUDE_CSLIP)
1289 printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1290 #endif
1291 #ifdef CONFIG_SLIP_SMART
1292 printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1293 #endif
1294
1295 slip_devs = kcalloc(slip_maxdev, sizeof(struct net_device *),
1296 GFP_KERNEL);
1297 if (!slip_devs)
1298 return -ENOMEM;
1299
1300 /* Fill in our line protocol discipline, and register it */
1301 status = tty_register_ldisc(N_SLIP, &sl_ldisc);
1302 if (status != 0) {
1303 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1304 kfree(slip_devs);
1305 }
1306 return status;
1307 }
1308
1309 static void __exit slip_exit(void)
1310 {
1311 int i;
1312 struct net_device *dev;
1313 struct slip *sl;
1314 unsigned long timeout = jiffies + HZ;
1315 int busy = 0;
1316
1317 if (slip_devs == NULL)
1318 return;
1319
1320 /* First of all: check for active disciplines and hangup them.
1321 */
1322 do {
1323 if (busy)
1324 msleep_interruptible(100);
1325
1326 busy = 0;
1327 for (i = 0; i < slip_maxdev; i++) {
1328 dev = slip_devs[i];
1329 if (!dev)
1330 continue;
1331 sl = netdev_priv(dev);
1332 spin_lock_bh(&sl->lock);
1333 if (sl->tty) {
1334 busy++;
1335 tty_hangup(sl->tty);
1336 }
1337 spin_unlock_bh(&sl->lock);
1338 }
1339 } while (busy && time_before(jiffies, timeout));
1340
1341 /* FIXME: hangup is async so we should wait when doing this second
1342 phase */
1343
1344 for (i = 0; i < slip_maxdev; i++) {
1345 dev = slip_devs[i];
1346 if (!dev)
1347 continue;
1348 slip_devs[i] = NULL;
1349
1350 sl = netdev_priv(dev);
1351 if (sl->tty) {
1352 printk(KERN_ERR "%s: tty discipline still running\n",
1353 dev->name);
1354 }
1355
1356 unregister_netdev(dev);
1357 }
1358
1359 kfree(slip_devs);
1360 slip_devs = NULL;
1361
1362 i = tty_unregister_ldisc(N_SLIP);
1363 if (i != 0)
1364 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i);
1365 }
1366
1367 module_init(slip_init);
1368 module_exit(slip_exit);
1369
1370 #ifdef CONFIG_SLIP_SMART
1371 /*
1372 * This is start of the code for multislip style line checking
1373 * added by Stanislav Voronyi. All changes before marked VSV
1374 */
1375
1376 static void sl_outfill(struct timer_list *t)
1377 {
1378 struct slip *sl = from_timer(sl, t, outfill_timer);
1379
1380 spin_lock(&sl->lock);
1381
1382 if (sl->tty == NULL)
1383 goto out;
1384
1385 if (sl->outfill) {
1386 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1387 /* no packets were transmitted, do outfill */
1388 #ifdef CONFIG_SLIP_MODE_SLIP6
1389 unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1390 #else
1391 unsigned char s = END;
1392 #endif
1393 /* put END into tty queue. Is it right ??? */
1394 if (!netif_queue_stopped(sl->dev)) {
1395 /* if device busy no outfill */
1396 sl->tty->ops->write(sl->tty, &s, 1);
1397 }
1398 } else
1399 set_bit(SLF_OUTWAIT, &sl->flags);
1400
1401 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1402 }
1403 out:
1404 spin_unlock(&sl->lock);
1405 }
1406
1407 static void sl_keepalive(struct timer_list *t)
1408 {
1409 struct slip *sl = from_timer(sl, t, keepalive_timer);
1410
1411 spin_lock(&sl->lock);
1412
1413 if (sl->tty == NULL)
1414 goto out;
1415
1416 if (sl->keepalive) {
1417 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1418 /* keepalive still high :(, we must hangup */
1419 if (sl->outfill)
1420 /* outfill timer must be deleted too */
1421 (void)del_timer(&sl->outfill_timer);
1422 printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1423 /* this must hangup tty & close slip */
1424 tty_hangup(sl->tty);
1425 /* I think we need not something else */
1426 goto out;
1427 } else
1428 set_bit(SLF_KEEPTEST, &sl->flags);
1429
1430 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1431 }
1432 out:
1433 spin_unlock(&sl->lock);
1434 }
1435
1436 #endif
1437 MODULE_LICENSE("GPL");
1438 MODULE_ALIAS_LDISC(N_SLIP);
1439