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Merge tag 'mm-hotfixes-stable-2025-07-11-16-16' of git://git.kernel.org/pub/scm/linux...
[linux-2.6-block.git] / drivers / net / slip / slip.c
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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/compat.h>
66#include <linux/module.h>
67#include <linux/moduleparam.h>
68
69#include <linux/uaccess.h>
70#include <linux/bitops.h>
71#include <linux/sched/signal.h>
72#include <linux/string.h>
73#include <linux/mm.h>
74#include <linux/interrupt.h>
75#include <linux/in.h>
76#include <linux/tty.h>
77#include <linux/errno.h>
78#include <linux/netdevice.h>
79#include <linux/etherdevice.h>
80#include <linux/skbuff.h>
81#include <linux/rtnetlink.h>
82#include <linux/if_arp.h>
83#include <linux/if_slip.h>
84#include <linux/delay.h>
85#include <linux/init.h>
86#include <linux/slab.h>
87#include <linux/workqueue.h>
88#include "slip.h"
89#ifdef CONFIG_INET
90#include <linux/ip.h>
91#include <linux/tcp.h>
92#include <net/slhc_vj.h>
93#endif
94
95#define SLIP_VERSION "0.8.4-NET3.019-NEWTTY"
96
97static struct net_device **slip_devs;
98
99static int slip_maxdev = SL_NRUNIT;
100module_param(slip_maxdev, int, 0);
101MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices");
102
103static int slip_esc(unsigned char *p, unsigned char *d, int len);
104static void slip_unesc(struct slip *sl, unsigned char c);
105#ifdef CONFIG_SLIP_MODE_SLIP6
106static int slip_esc6(unsigned char *p, unsigned char *d, int len);
107static void slip_unesc6(struct slip *sl, unsigned char c);
108#endif
109#ifdef CONFIG_SLIP_SMART
110static void sl_keepalive(struct timer_list *t);
111static void sl_outfill(struct timer_list *t);
112static int sl_siocdevprivate(struct net_device *dev, struct ifreq *rq, void __user *data, int cmd);
113#endif
114
115/********************************
116* Buffer administration routines:
117* sl_alloc_bufs()
118* sl_free_bufs()
119* sl_realloc_bufs()
120*
121* NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because
122* sl_realloc_bufs provides strong atomicity and reallocation
123* on actively running device.
124*********************************/
125
126/*
127 Allocate channel buffers.
128 */
129
130static int sl_alloc_bufs(struct slip *sl, int mtu)
131{
132 int err = -ENOBUFS;
133 unsigned long len;
134 char *rbuff = NULL;
135 char *xbuff = NULL;
136#ifdef SL_INCLUDE_CSLIP
137 char *cbuff = NULL;
138 struct slcompress *slcomp = NULL;
139#endif
140
141 /*
142 * Allocate the SLIP frame buffers:
143 *
144 * rbuff Receive buffer.
145 * xbuff Transmit buffer.
146 * cbuff Temporary compression buffer.
147 */
148 len = mtu * 2;
149
150 /*
151 * allow for arrival of larger UDP packets, even if we say not to
152 * also fixes a bug in which SunOS sends 512-byte packets even with
153 * an MSS of 128
154 */
155 if (len < 576 * 2)
156 len = 576 * 2;
157 rbuff = kmalloc(len + 4, GFP_KERNEL);
158 if (rbuff == NULL)
159 goto err_exit;
160 xbuff = kmalloc(len + 4, GFP_KERNEL);
161 if (xbuff == NULL)
162 goto err_exit;
163#ifdef SL_INCLUDE_CSLIP
164 cbuff = kmalloc(len + 4, GFP_KERNEL);
165 if (cbuff == NULL)
166 goto err_exit;
167 slcomp = slhc_init(16, 16);
168 if (IS_ERR(slcomp))
169 goto err_exit;
170#endif
171 spin_lock_bh(&sl->lock);
172 if (sl->tty == NULL) {
173 spin_unlock_bh(&sl->lock);
174 err = -ENODEV;
175 goto err_exit;
176 }
177 sl->mtu = mtu;
178 sl->buffsize = len;
179 sl->rcount = 0;
180 sl->xleft = 0;
181 rbuff = xchg(&sl->rbuff, rbuff);
182 xbuff = xchg(&sl->xbuff, xbuff);
183#ifdef SL_INCLUDE_CSLIP
184 cbuff = xchg(&sl->cbuff, cbuff);
185 slcomp = xchg(&sl->slcomp, slcomp);
186#endif
187#ifdef CONFIG_SLIP_MODE_SLIP6
188 sl->xdata = 0;
189 sl->xbits = 0;
190#endif
191 spin_unlock_bh(&sl->lock);
192 err = 0;
193
194 /* Cleanup */
195err_exit:
196#ifdef SL_INCLUDE_CSLIP
197 kfree(cbuff);
198 slhc_free(slcomp);
199#endif
200 kfree(xbuff);
201 kfree(rbuff);
202 return err;
203}
204
205/* Free a SLIP channel buffers. */
206static void sl_free_bufs(struct slip *sl)
207{
208 /* Free all SLIP frame buffers. */
209 kfree(xchg(&sl->rbuff, NULL));
210 kfree(xchg(&sl->xbuff, NULL));
211#ifdef SL_INCLUDE_CSLIP
212 kfree(xchg(&sl->cbuff, NULL));
213 slhc_free(xchg(&sl->slcomp, NULL));
214#endif
215}
216
217/*
218 Reallocate slip channel buffers.
219 */
220
221static int sl_realloc_bufs(struct slip *sl, int mtu)
222{
223 int err = 0;
224 struct net_device *dev = sl->dev;
225 unsigned char *xbuff, *rbuff;
226#ifdef SL_INCLUDE_CSLIP
227 unsigned char *cbuff;
228#endif
229 int len = mtu * 2;
230
231/*
232 * allow for arrival of larger UDP packets, even if we say not to
233 * also fixes a bug in which SunOS sends 512-byte packets even with
234 * an MSS of 128
235 */
236 if (len < 576 * 2)
237 len = 576 * 2;
238
239 xbuff = kmalloc(len + 4, GFP_ATOMIC);
240 rbuff = kmalloc(len + 4, GFP_ATOMIC);
241#ifdef SL_INCLUDE_CSLIP
242 cbuff = kmalloc(len + 4, GFP_ATOMIC);
243#endif
244
245
246#ifdef SL_INCLUDE_CSLIP
247 if (xbuff == NULL || rbuff == NULL || cbuff == NULL) {
248#else
249 if (xbuff == NULL || rbuff == NULL) {
250#endif
251 if (mtu > sl->mtu) {
252 printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n",
253 dev->name);
254 err = -ENOBUFS;
255 }
256 goto done;
257 }
258 spin_lock_bh(&sl->lock);
259
260 err = -ENODEV;
261 if (sl->tty == NULL)
262 goto done_on_bh;
263
264 xbuff = xchg(&sl->xbuff, xbuff);
265 rbuff = xchg(&sl->rbuff, rbuff);
266#ifdef SL_INCLUDE_CSLIP
267 cbuff = xchg(&sl->cbuff, cbuff);
268#endif
269 if (sl->xleft) {
270 if (sl->xleft <= len) {
271 memcpy(sl->xbuff, sl->xhead, sl->xleft);
272 } else {
273 sl->xleft = 0;
274 dev->stats.tx_dropped++;
275 }
276 }
277 sl->xhead = sl->xbuff;
278
279 if (sl->rcount) {
280 if (sl->rcount <= len) {
281 memcpy(sl->rbuff, rbuff, sl->rcount);
282 } else {
283 sl->rcount = 0;
284 dev->stats.rx_over_errors++;
285 set_bit(SLF_ERROR, &sl->flags);
286 }
287 }
288 sl->mtu = mtu;
289 WRITE_ONCE(dev->mtu, mtu);
290 sl->buffsize = len;
291 err = 0;
292
293done_on_bh:
294 spin_unlock_bh(&sl->lock);
295
296done:
297 kfree(xbuff);
298 kfree(rbuff);
299#ifdef SL_INCLUDE_CSLIP
300 kfree(cbuff);
301#endif
302 return err;
303}
304
305
306/* Set the "sending" flag. This must be atomic hence the set_bit. */
307static inline void sl_lock(struct slip *sl)
308{
309 netif_stop_queue(sl->dev);
310}
311
312
313/* Clear the "sending" flag. This must be atomic, hence the ASM. */
314static inline void sl_unlock(struct slip *sl)
315{
316 netif_wake_queue(sl->dev);
317}
318
319/* Send one completely decapsulated IP datagram to the IP layer. */
320static void sl_bump(struct slip *sl)
321{
322 struct net_device *dev = sl->dev;
323 struct sk_buff *skb;
324 int count;
325
326 count = sl->rcount;
327#ifdef SL_INCLUDE_CSLIP
328 if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) {
329 unsigned char c = sl->rbuff[0];
330 if (c & SL_TYPE_COMPRESSED_TCP) {
331 /* ignore compressed packets when CSLIP is off */
332 if (!(sl->mode & SL_MODE_CSLIP)) {
333 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name);
334 return;
335 }
336 /* make sure we've reserved enough space for uncompress
337 to use */
338 if (count + 80 > sl->buffsize) {
339 dev->stats.rx_over_errors++;
340 return;
341 }
342 count = slhc_uncompress(sl->slcomp, sl->rbuff, count);
343 if (count <= 0)
344 return;
345 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) {
346 if (!(sl->mode & SL_MODE_CSLIP)) {
347 /* turn on header compression */
348 sl->mode |= SL_MODE_CSLIP;
349 sl->mode &= ~SL_MODE_ADAPTIVE;
350 printk(KERN_INFO "%s: header compression turned on\n", dev->name);
351 }
352 sl->rbuff[0] &= 0x4f;
353 if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0)
354 return;
355 }
356 }
357#endif /* SL_INCLUDE_CSLIP */
358
359 dev->stats.rx_bytes += count;
360
361 skb = dev_alloc_skb(count);
362 if (skb == NULL) {
363 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name);
364 dev->stats.rx_dropped++;
365 return;
366 }
367 skb->dev = dev;
368 skb_put_data(skb, sl->rbuff, count);
369 skb_reset_mac_header(skb);
370 skb->protocol = htons(ETH_P_IP);
371 netif_rx(skb);
372 dev->stats.rx_packets++;
373}
374
375/* Encapsulate one IP datagram and stuff into a TTY queue. */
376static void sl_encaps(struct slip *sl, unsigned char *icp, int len)
377{
378 unsigned char *p;
379 int actual, count;
380
381 if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */
382 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name);
383 sl->dev->stats.tx_dropped++;
384 sl_unlock(sl);
385 return;
386 }
387
388 p = icp;
389#ifdef SL_INCLUDE_CSLIP
390 if (sl->mode & SL_MODE_CSLIP)
391 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1);
392#endif
393#ifdef CONFIG_SLIP_MODE_SLIP6
394 if (sl->mode & SL_MODE_SLIP6)
395 count = slip_esc6(p, sl->xbuff, len);
396 else
397#endif
398 count = slip_esc(p, sl->xbuff, len);
399
400 /* Order of next two lines is *very* important.
401 * When we are sending a little amount of data,
402 * the transfer may be completed inside the ops->write()
403 * routine, because it's running with interrupts enabled.
404 * In this case we *never* got WRITE_WAKEUP event,
405 * if we did not request it before write operation.
406 * 14 Oct 1994 Dmitry Gorodchanin.
407 */
408 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
409 actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
410#ifdef SL_CHECK_TRANSMIT
411 netif_trans_update(sl->dev);
412#endif
413 sl->xleft = count - actual;
414 sl->xhead = sl->xbuff + actual;
415#ifdef CONFIG_SLIP_SMART
416 /* VSV */
417 clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */
418#endif
419}
420
421/* Write out any remaining transmit buffer. Scheduled when tty is writable */
422static void slip_transmit(struct work_struct *work)
423{
424 struct slip *sl = container_of(work, struct slip, tx_work);
425 int actual;
426
427 spin_lock_bh(&sl->lock);
428 /* First make sure we're connected. */
429 if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) {
430 spin_unlock_bh(&sl->lock);
431 return;
432 }
433
434 if (sl->xleft <= 0) {
435 /* Now serial buffer is almost free & we can start
436 * transmission of another packet */
437 sl->dev->stats.tx_packets++;
438 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
439 spin_unlock_bh(&sl->lock);
440 sl_unlock(sl);
441 return;
442 }
443
444 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft);
445 sl->xleft -= actual;
446 sl->xhead += actual;
447 spin_unlock_bh(&sl->lock);
448}
449
450/*
451 * Called by the driver when there's room for more data.
452 * Schedule the transmit.
453 */
454static void slip_write_wakeup(struct tty_struct *tty)
455{
456 struct slip *sl;
457
458 rcu_read_lock();
459 sl = rcu_dereference(tty->disc_data);
460 if (sl)
461 schedule_work(&sl->tx_work);
462 rcu_read_unlock();
463}
464
465static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue)
466{
467 struct slip *sl = netdev_priv(dev);
468
469 spin_lock(&sl->lock);
470
471 if (netif_queue_stopped(dev)) {
472 if (!netif_running(dev) || !sl->tty)
473 goto out;
474
475 /* May be we must check transmitter timeout here ?
476 * 14 Oct 1994 Dmitry Gorodchanin.
477 */
478#ifdef SL_CHECK_TRANSMIT
479 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) {
480 /* 20 sec timeout not reached */
481 goto out;
482 }
483 printk(KERN_WARNING "%s: transmit timed out, %s?\n",
484 dev->name,
485 (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
486 "bad line quality" : "driver error");
487 sl->xleft = 0;
488 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
489 sl_unlock(sl);
490#endif
491 }
492out:
493 spin_unlock(&sl->lock);
494}
495
496
497/* Encapsulate an IP datagram and kick it into a TTY queue. */
498static netdev_tx_t
499sl_xmit(struct sk_buff *skb, struct net_device *dev)
500{
501 struct slip *sl = netdev_priv(dev);
502
503 spin_lock(&sl->lock);
504 if (!netif_running(dev)) {
505 spin_unlock(&sl->lock);
506 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name);
507 dev_kfree_skb(skb);
508 return NETDEV_TX_OK;
509 }
510 if (sl->tty == NULL) {
511 spin_unlock(&sl->lock);
512 dev_kfree_skb(skb);
513 return NETDEV_TX_OK;
514 }
515
516 sl_lock(sl);
517 dev->stats.tx_bytes += skb->len;
518 sl_encaps(sl, skb->data, skb->len);
519 spin_unlock(&sl->lock);
520
521 dev_kfree_skb(skb);
522 return NETDEV_TX_OK;
523}
524
525
526/******************************************
527 * Routines looking at netdevice side.
528 ******************************************/
529
530/* Netdevice UP -> DOWN routine */
531
532static int
533sl_close(struct net_device *dev)
534{
535 struct slip *sl = netdev_priv(dev);
536
537 spin_lock_bh(&sl->lock);
538 if (sl->tty)
539 /* TTY discipline is running. */
540 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
541 netif_stop_queue(dev);
542 sl->rcount = 0;
543 sl->xleft = 0;
544 spin_unlock_bh(&sl->lock);
545
546 return 0;
547}
548
549/* Netdevice DOWN -> UP routine */
550
551static int sl_open(struct net_device *dev)
552{
553 struct slip *sl = netdev_priv(dev);
554
555 if (sl->tty == NULL)
556 return -ENODEV;
557
558 sl->flags &= (1 << SLF_INUSE);
559 netif_start_queue(dev);
560 return 0;
561}
562
563/* Netdevice change MTU request */
564
565static int sl_change_mtu(struct net_device *dev, int new_mtu)
566{
567 struct slip *sl = netdev_priv(dev);
568
569 return sl_realloc_bufs(sl, new_mtu);
570}
571
572/* Netdevice get statistics request */
573
574static void
575sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)
576{
577 struct net_device_stats *devstats = &dev->stats;
578#ifdef SL_INCLUDE_CSLIP
579 struct slip *sl = netdev_priv(dev);
580 struct slcompress *comp = sl->slcomp;
581#endif
582 stats->rx_packets = devstats->rx_packets;
583 stats->tx_packets = devstats->tx_packets;
584 stats->rx_bytes = devstats->rx_bytes;
585 stats->tx_bytes = devstats->tx_bytes;
586 stats->rx_dropped = devstats->rx_dropped;
587 stats->tx_dropped = devstats->tx_dropped;
588 stats->tx_errors = devstats->tx_errors;
589 stats->rx_errors = devstats->rx_errors;
590 stats->rx_over_errors = devstats->rx_over_errors;
591
592#ifdef SL_INCLUDE_CSLIP
593 if (comp) {
594 /* Generic compressed statistics */
595 stats->rx_compressed = comp->sls_i_compressed;
596 stats->tx_compressed = comp->sls_o_compressed;
597
598 /* Are we really still needs this? */
599 stats->rx_fifo_errors += comp->sls_i_compressed;
600 stats->rx_dropped += comp->sls_i_tossed;
601 stats->tx_fifo_errors += comp->sls_o_compressed;
602 stats->collisions += comp->sls_o_misses;
603 }
604#endif
605}
606
607/* Netdevice register callback */
608
609static int sl_init(struct net_device *dev)
610{
611 struct slip *sl = netdev_priv(dev);
612
613 /*
614 * Finish setting up the DEVICE info.
615 */
616
617 dev->mtu = sl->mtu;
618 dev->type = ARPHRD_SLIP + sl->mode;
619#ifdef SL_CHECK_TRANSMIT
620 dev->watchdog_timeo = 20*HZ;
621#endif
622 return 0;
623}
624
625
626static void sl_uninit(struct net_device *dev)
627{
628 struct slip *sl = netdev_priv(dev);
629
630 sl_free_bufs(sl);
631}
632
633/* Hook the destructor so we can free slip devices at the right point in time */
634static void sl_free_netdev(struct net_device *dev)
635{
636 int i = dev->base_addr;
637
638 slip_devs[i] = NULL;
639}
640
641static const struct net_device_ops sl_netdev_ops = {
642 .ndo_init = sl_init,
643 .ndo_uninit = sl_uninit,
644 .ndo_open = sl_open,
645 .ndo_stop = sl_close,
646 .ndo_start_xmit = sl_xmit,
647 .ndo_get_stats64 = sl_get_stats64,
648 .ndo_change_mtu = sl_change_mtu,
649 .ndo_tx_timeout = sl_tx_timeout,
650#ifdef CONFIG_SLIP_SMART
651 .ndo_siocdevprivate = sl_siocdevprivate,
652#endif
653};
654
655
656static void sl_setup(struct net_device *dev)
657{
658 dev->netdev_ops = &sl_netdev_ops;
659 dev->needs_free_netdev = true;
660 dev->priv_destructor = sl_free_netdev;
661
662 dev->hard_header_len = 0;
663 dev->addr_len = 0;
664 dev->tx_queue_len = 10;
665
666 /* MTU range: 68 - 65534 */
667 dev->min_mtu = 68;
668 dev->max_mtu = 65534;
669
670 /* New-style flags. */
671 dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST;
672}
673
674/******************************************
675 Routines looking at TTY side.
676 ******************************************/
677
678
679/*
680 * Handle the 'receiver data ready' interrupt.
681 * This function is called by the 'tty_io' module in the kernel when
682 * a block of SLIP data has been received, which can now be decapsulated
683 * and sent on to some IP layer for further processing. This will not
684 * be re-entered while running but other ldisc functions may be called
685 * in parallel
686 */
687
688static void slip_receive_buf(struct tty_struct *tty, const u8 *cp, const u8 *fp,
689 size_t count)
690{
691 struct slip *sl = tty->disc_data;
692
693 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev))
694 return;
695
696 /* Read the characters out of the buffer */
697 while (count--) {
698 if (fp && *fp++) {
699 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
700 sl->dev->stats.rx_errors++;
701 cp++;
702 continue;
703 }
704#ifdef CONFIG_SLIP_MODE_SLIP6
705 if (sl->mode & SL_MODE_SLIP6)
706 slip_unesc6(sl, *cp++);
707 else
708#endif
709 slip_unesc(sl, *cp++);
710 }
711}
712
713/************************************
714 * slip_open helper routines.
715 ************************************/
716
717/* Collect hanged up channels */
718static void sl_sync(void)
719{
720 int i;
721 struct net_device *dev;
722 struct slip *sl;
723
724 for (i = 0; i < slip_maxdev; i++) {
725 dev = slip_devs[i];
726 if (dev == NULL)
727 break;
728
729 sl = netdev_priv(dev);
730 if (sl->tty || sl->leased)
731 continue;
732 if (dev->flags & IFF_UP)
733 dev_close(dev);
734 }
735}
736
737
738/* Find a free SLIP channel, and link in this `tty' line. */
739static struct slip *sl_alloc(void)
740{
741 int i;
742 char name[IFNAMSIZ];
743 struct net_device *dev = NULL;
744 struct slip *sl;
745
746 for (i = 0; i < slip_maxdev; i++) {
747 dev = slip_devs[i];
748 if (dev == NULL)
749 break;
750 }
751 /* Sorry, too many, all slots in use */
752 if (i >= slip_maxdev)
753 return NULL;
754
755 sprintf(name, "sl%d", i);
756 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup);
757 if (!dev)
758 return NULL;
759
760 dev->base_addr = i;
761 sl = netdev_priv(dev);
762
763 /* Initialize channel control data */
764 sl->magic = SLIP_MAGIC;
765 sl->dev = dev;
766 spin_lock_init(&sl->lock);
767 INIT_WORK(&sl->tx_work, slip_transmit);
768 sl->mode = SL_MODE_DEFAULT;
769#ifdef CONFIG_SLIP_SMART
770 /* initialize timer_list struct */
771 timer_setup(&sl->keepalive_timer, sl_keepalive, 0);
772 timer_setup(&sl->outfill_timer, sl_outfill, 0);
773#endif
774 slip_devs[i] = dev;
775 return sl;
776}
777
778/*
779 * Open the high-level part of the SLIP channel.
780 * This function is called by the TTY module when the
781 * SLIP line discipline is called for. Because we are
782 * sure the tty line exists, we only have to link it to
783 * a free SLIP channel...
784 *
785 * Called in process context serialized from other ldisc calls.
786 */
787
788static int slip_open(struct tty_struct *tty)
789{
790 struct slip *sl;
791 int err;
792
793 if (!capable(CAP_NET_ADMIN))
794 return -EPERM;
795
796 if (tty->ops->write == NULL)
797 return -EOPNOTSUPP;
798
799 /* RTnetlink lock is misused here to serialize concurrent
800 opens of slip channels. There are better ways, but it is
801 the simplest one.
802 */
803 rtnl_lock();
804
805 /* Collect hanged up channels. */
806 sl_sync();
807
808 sl = tty->disc_data;
809
810 err = -EEXIST;
811 /* First make sure we're not already connected. */
812 if (sl && sl->magic == SLIP_MAGIC)
813 goto err_exit;
814
815 /* OK. Find a free SLIP channel to use. */
816 err = -ENFILE;
817 sl = sl_alloc();
818 if (sl == NULL)
819 goto err_exit;
820
821 sl->tty = tty;
822 tty->disc_data = sl;
823 sl->pid = current->pid;
824
825 if (!test_bit(SLF_INUSE, &sl->flags)) {
826 /* Perform the low-level SLIP initialization. */
827 err = sl_alloc_bufs(sl, SL_MTU);
828 if (err)
829 goto err_free_chan;
830
831 set_bit(SLF_INUSE, &sl->flags);
832
833 err = register_netdevice(sl->dev);
834 if (err)
835 goto err_free_bufs;
836 }
837
838#ifdef CONFIG_SLIP_SMART
839 if (sl->keepalive) {
840 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ;
841 add_timer(&sl->keepalive_timer);
842 }
843 if (sl->outfill) {
844 sl->outfill_timer.expires = jiffies + sl->outfill * HZ;
845 add_timer(&sl->outfill_timer);
846 }
847#endif
848
849 /* Done. We have linked the TTY line to a channel. */
850 rtnl_unlock();
851 tty->receive_room = 65536; /* We don't flow control */
852
853 /* TTY layer expects 0 on success */
854 return 0;
855
856err_free_bufs:
857 sl_free_bufs(sl);
858
859err_free_chan:
860 sl->tty = NULL;
861 tty->disc_data = NULL;
862 clear_bit(SLF_INUSE, &sl->flags);
863 sl_free_netdev(sl->dev);
864 /* do not call free_netdev before rtnl_unlock */
865 rtnl_unlock();
866 free_netdev(sl->dev);
867 return err;
868
869err_exit:
870 rtnl_unlock();
871
872 /* Count references from TTY module */
873 return err;
874}
875
876/*
877 * Close down a SLIP channel.
878 * This means flushing out any pending queues, and then returning. This
879 * call is serialized against other ldisc functions.
880 *
881 * We also use this method fo a hangup event
882 */
883
884static void slip_close(struct tty_struct *tty)
885{
886 struct slip *sl = tty->disc_data;
887
888 /* First make sure we're connected. */
889 if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty)
890 return;
891
892 spin_lock_bh(&sl->lock);
893 rcu_assign_pointer(tty->disc_data, NULL);
894 sl->tty = NULL;
895 spin_unlock_bh(&sl->lock);
896
897 synchronize_rcu();
898 flush_work(&sl->tx_work);
899
900 /* VSV = very important to remove timers */
901#ifdef CONFIG_SLIP_SMART
902 timer_delete_sync(&sl->keepalive_timer);
903 timer_delete_sync(&sl->outfill_timer);
904#endif
905 /* Flush network side */
906 unregister_netdev(sl->dev);
907 /* This will complete via sl_free_netdev */
908}
909
910static void slip_hangup(struct tty_struct *tty)
911{
912 slip_close(tty);
913}
914 /************************************************************************
915 * STANDARD SLIP ENCAPSULATION *
916 ************************************************************************/
917
918static 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
955static 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
1001static 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
1038static 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. */
1075static int slip_ioctl(struct tty_struct *tty, unsigned int cmd,
1076 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 timer_delete(&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 timer_delete(&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, cmd, arg);
1177 }
1178}
1179
1180/* VSV changes start here */
1181#ifdef CONFIG_SLIP_SMART
1182/* function sl_siocdevprivate called from net/core/dev.c
1183 to allow get/set outfill/keepalive parameter
1184 by ifconfig */
1185
1186static int sl_siocdevprivate(struct net_device *dev, struct ifreq *rq,
1187 void __user *data, int cmd)
1188{
1189 struct slip *sl = netdev_priv(dev);
1190 unsigned long *p = (unsigned long *)&rq->ifr_ifru;
1191
1192 if (sl == NULL) /* Allocation failed ?? */
1193 return -ENODEV;
1194
1195 if (in_compat_syscall())
1196 return -EOPNOTSUPP;
1197
1198 spin_lock_bh(&sl->lock);
1199
1200 if (!sl->tty) {
1201 spin_unlock_bh(&sl->lock);
1202 return -ENODEV;
1203 }
1204
1205 switch (cmd) {
1206 case SIOCSKEEPALIVE:
1207 /* max for unchar */
1208 if ((unsigned)*p > 255) {
1209 spin_unlock_bh(&sl->lock);
1210 return -EINVAL;
1211 }
1212 sl->keepalive = (u8)*p;
1213 if (sl->keepalive != 0) {
1214 sl->keepalive_timer.expires =
1215 jiffies + sl->keepalive * HZ;
1216 mod_timer(&sl->keepalive_timer,
1217 jiffies + sl->keepalive * HZ);
1218 set_bit(SLF_KEEPTEST, &sl->flags);
1219 } else
1220 timer_delete(&sl->keepalive_timer);
1221 break;
1222
1223 case SIOCGKEEPALIVE:
1224 *p = sl->keepalive;
1225 break;
1226
1227 case SIOCSOUTFILL:
1228 if ((unsigned)*p > 255) { /* max for unchar */
1229 spin_unlock_bh(&sl->lock);
1230 return -EINVAL;
1231 }
1232 sl->outfill = (u8)*p;
1233 if (sl->outfill != 0) {
1234 mod_timer(&sl->outfill_timer,
1235 jiffies + sl->outfill * HZ);
1236 set_bit(SLF_OUTWAIT, &sl->flags);
1237 } else
1238 timer_delete(&sl->outfill_timer);
1239 break;
1240
1241 case SIOCGOUTFILL:
1242 *p = sl->outfill;
1243 break;
1244
1245 case SIOCSLEASE:
1246 /* Resolve race condition, when ioctl'ing hanged up
1247 and opened by another process device.
1248 */
1249 if (sl->tty != current->signal->tty &&
1250 sl->pid != current->pid) {
1251 spin_unlock_bh(&sl->lock);
1252 return -EPERM;
1253 }
1254 sl->leased = 0;
1255 if (*p)
1256 sl->leased = 1;
1257 break;
1258
1259 case SIOCGLEASE:
1260 *p = sl->leased;
1261 }
1262 spin_unlock_bh(&sl->lock);
1263 return 0;
1264}
1265#endif
1266/* VSV changes end */
1267
1268static struct tty_ldisc_ops sl_ldisc = {
1269 .owner = THIS_MODULE,
1270 .num = N_SLIP,
1271 .name = "slip",
1272 .open = slip_open,
1273 .close = slip_close,
1274 .hangup = slip_hangup,
1275 .ioctl = slip_ioctl,
1276 .receive_buf = slip_receive_buf,
1277 .write_wakeup = slip_write_wakeup,
1278};
1279
1280static int __init slip_init(void)
1281{
1282 int status;
1283
1284 if (slip_maxdev < 4)
1285 slip_maxdev = 4; /* Sanity */
1286
1287 printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)"
1288#ifdef CONFIG_SLIP_MODE_SLIP6
1289 " (6 bit encapsulation enabled)"
1290#endif
1291 ".\n",
1292 SLIP_VERSION, slip_maxdev);
1293#if defined(SL_INCLUDE_CSLIP)
1294 printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n");
1295#endif
1296#ifdef CONFIG_SLIP_SMART
1297 printk(KERN_INFO "SLIP linefill/keepalive option.\n");
1298#endif
1299
1300 slip_devs = kcalloc(slip_maxdev, sizeof(struct net_device *),
1301 GFP_KERNEL);
1302 if (!slip_devs)
1303 return -ENOMEM;
1304
1305 /* Fill in our line protocol discipline, and register it */
1306 status = tty_register_ldisc(&sl_ldisc);
1307 if (status != 0) {
1308 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status);
1309 kfree(slip_devs);
1310 }
1311 return status;
1312}
1313
1314static void __exit slip_exit(void)
1315{
1316 int i;
1317 struct net_device *dev;
1318 struct slip *sl;
1319 unsigned long timeout = jiffies + HZ;
1320 int busy = 0;
1321
1322 if (slip_devs == NULL)
1323 return;
1324
1325 /* First of all: check for active disciplines and hangup them.
1326 */
1327 do {
1328 if (busy)
1329 msleep_interruptible(100);
1330
1331 busy = 0;
1332 for (i = 0; i < slip_maxdev; i++) {
1333 dev = slip_devs[i];
1334 if (!dev)
1335 continue;
1336 sl = netdev_priv(dev);
1337 spin_lock_bh(&sl->lock);
1338 if (sl->tty) {
1339 busy++;
1340 tty_hangup(sl->tty);
1341 }
1342 spin_unlock_bh(&sl->lock);
1343 }
1344 } while (busy && time_before(jiffies, timeout));
1345
1346 /* FIXME: hangup is async so we should wait when doing this second
1347 phase */
1348
1349 for (i = 0; i < slip_maxdev; i++) {
1350 dev = slip_devs[i];
1351 if (!dev)
1352 continue;
1353 slip_devs[i] = NULL;
1354
1355 sl = netdev_priv(dev);
1356 if (sl->tty) {
1357 printk(KERN_ERR "%s: tty discipline still running\n",
1358 dev->name);
1359 }
1360
1361 unregister_netdev(dev);
1362 }
1363
1364 kfree(slip_devs);
1365 slip_devs = NULL;
1366
1367 tty_unregister_ldisc(&sl_ldisc);
1368}
1369
1370module_init(slip_init);
1371module_exit(slip_exit);
1372
1373#ifdef CONFIG_SLIP_SMART
1374/*
1375 * This is start of the code for multislip style line checking
1376 * added by Stanislav Voronyi. All changes before marked VSV
1377 */
1378
1379static void sl_outfill(struct timer_list *t)
1380{
1381 struct slip *sl = timer_container_of(sl, t, outfill_timer);
1382
1383 spin_lock(&sl->lock);
1384
1385 if (sl->tty == NULL)
1386 goto out;
1387
1388 if (sl->outfill) {
1389 if (test_bit(SLF_OUTWAIT, &sl->flags)) {
1390 /* no packets were transmitted, do outfill */
1391#ifdef CONFIG_SLIP_MODE_SLIP6
1392 unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END;
1393#else
1394 unsigned char s = END;
1395#endif
1396 /* put END into tty queue. Is it right ??? */
1397 if (!netif_queue_stopped(sl->dev)) {
1398 /* if device busy no outfill */
1399 sl->tty->ops->write(sl->tty, &s, 1);
1400 }
1401 } else
1402 set_bit(SLF_OUTWAIT, &sl->flags);
1403
1404 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ);
1405 }
1406out:
1407 spin_unlock(&sl->lock);
1408}
1409
1410static void sl_keepalive(struct timer_list *t)
1411{
1412 struct slip *sl = timer_container_of(sl, t, keepalive_timer);
1413
1414 spin_lock(&sl->lock);
1415
1416 if (sl->tty == NULL)
1417 goto out;
1418
1419 if (sl->keepalive) {
1420 if (test_bit(SLF_KEEPTEST, &sl->flags)) {
1421 /* keepalive still high :(, we must hangup */
1422 if (sl->outfill)
1423 /* outfill timer must be deleted too */
1424 (void) timer_delete(&sl->outfill_timer);
1425 printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name);
1426 /* this must hangup tty & close slip */
1427 tty_hangup(sl->tty);
1428 /* I think we need not something else */
1429 goto out;
1430 } else
1431 set_bit(SLF_KEEPTEST, &sl->flags);
1432
1433 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ);
1434 }
1435out:
1436 spin_unlock(&sl->lock);
1437}
1438
1439#endif
1440MODULE_DESCRIPTION("SLIP (serial line) protocol module");
1441MODULE_LICENSE("GPL");
1442MODULE_ALIAS_LDISC(N_SLIP);
Linux 6.x block layer and io_uring tree(s)