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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * PPP synchronous tty channel driver for Linux.
3 *
4 * This is a ppp channel driver that can be used with tty device drivers
5 * that are frame oriented, such as synchronous HDLC devices.
6 *
7 * Complete PPP frames without encoding/decoding are exchanged between
8 * the channel driver and the device driver.
Jeff Garzik6aa20a22006-09-13 13:24:59 -04009 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * The async map IOCTL codes are implemented to keep the user mode
11 * applications happy if they call them. Synchronous PPP does not use
12 * the async maps.
13 *
14 * Copyright 1999 Paul Mackerras.
15 *
16 * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
17 *
18 * This program is free software; you can redistribute it and/or
19 * modify it under the terms of the GNU General Public License
20 * as published by the Free Software Foundation; either version
21 * 2 of the License, or (at your option) any later version.
22 *
23 * This driver provides the encapsulation and framing for sending
24 * and receiving PPP frames over sync serial lines. It relies on
25 * the generic PPP layer to give it frames to send and to process
26 * received frames. It implements the PPP line discipline.
27 *
28 * Part of the code in this driver was inspired by the old async-only
29 * PPP driver, written by Michael Callahan and Al Longyear, and
30 * subsequently hacked by Paul Mackerras.
31 *
32 * ==FILEVERSION 20040616==
33 */
34
35#include <linux/module.h>
36#include <linux/kernel.h>
37#include <linux/skbuff.h>
38#include <linux/tty.h>
39#include <linux/netdevice.h>
40#include <linux/poll.h>
41#include <linux/ppp_defs.h>
Paul Mackerras4b32da2b2012-03-04 12:56:55 +000042#include <linux/ppp-ioctl.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070043#include <linux/ppp_channel.h>
44#include <linux/spinlock.h>
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -080045#include <linux/completion.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070046#include <linux/init.h>
Alexey Dobriyana6b7a402011-06-06 10:43:46 +000047#include <linux/interrupt.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090048#include <linux/slab.h>
Changli Gao96545ae2011-01-06 13:37:36 +000049#include <asm/unaligned.h>
Linus Torvalds7c0f6ba2016-12-24 11:46:01 -080050#include <linux/uaccess.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52#define PPP_VERSION "2.4.2"
53
54/* Structure for storing local state. */
55struct syncppp {
56 struct tty_struct *tty;
57 unsigned int flags;
58 unsigned int rbits;
59 int mru;
60 spinlock_t xmit_lock;
61 spinlock_t recv_lock;
62 unsigned long xmit_flags;
63 u32 xaccm[8];
64 u32 raccm;
65 unsigned int bytes_sent;
66 unsigned int bytes_rcvd;
67
68 struct sk_buff *tpkt;
69 unsigned long last_xmit;
70
71 struct sk_buff_head rqueue;
72
73 struct tasklet_struct tsk;
74
75 atomic_t refcnt;
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -080076 struct completion dead_cmp;
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 struct ppp_channel chan; /* interface to generic ppp layer */
78};
79
80/* Bit numbers in xmit_flags */
81#define XMIT_WAKEUP 0
82#define XMIT_FULL 1
83
84/* Bits in rbits */
85#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
86
87#define PPPSYNC_MAX_RQLEN 32 /* arbitrary */
88
89/*
90 * Prototypes.
91 */
92static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
93static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
94static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
95 unsigned long arg);
96static void ppp_sync_process(unsigned long arg);
97static int ppp_sync_push(struct syncppp *ap);
98static void ppp_sync_flush_output(struct syncppp *ap);
99static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
100 char *flags, int count);
101
stephen hemmingerd7100da2010-08-04 07:34:36 +0000102static const struct ppp_channel_ops sync_ops = {
103 .start_xmit = ppp_sync_send,
104 .ioctl = ppp_sync_ioctl,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105};
106
107/*
Andy Shevchenko167bfa72013-03-27 05:54:14 +0000108 * Utility procedure to print a buffer in hex/ascii
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 */
110static void
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111ppp_print_buffer (const char *name, const __u8 *buf, int count)
112{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113 if (name != NULL)
114 printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
115
Andy Shevchenko167bfa72013-03-27 05:54:14 +0000116 print_hex_dump_bytes("", DUMP_PREFIX_NONE, buf, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117}
118
119
120/*
121 * Routines implementing the synchronous PPP line discipline.
122 */
123
124/*
125 * We have a potential race on dereferencing tty->disc_data,
126 * because the tty layer provides no locking at all - thus one
127 * cpu could be running ppp_synctty_receive while another
128 * calls ppp_synctty_close, which zeroes tty->disc_data and
129 * frees the memory that ppp_synctty_receive is using. The best
130 * way to fix this is to use a rwlock in the tty struct, but for now
131 * we use a single global rwlock for all ttys in ppp line discipline.
132 *
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300133 * FIXME: Fixed in tty_io nowadays.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 */
135static DEFINE_RWLOCK(disc_data_lock);
136
137static struct syncppp *sp_get(struct tty_struct *tty)
138{
139 struct syncppp *ap;
140
141 read_lock(&disc_data_lock);
142 ap = tty->disc_data;
143 if (ap != NULL)
144 atomic_inc(&ap->refcnt);
145 read_unlock(&disc_data_lock);
146 return ap;
147}
148
149static void sp_put(struct syncppp *ap)
150{
151 if (atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800152 complete(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700153}
154
155/*
156 * Called when a tty is put into sync-PPP line discipline.
157 */
158static int
159ppp_sync_open(struct tty_struct *tty)
160{
161 struct syncppp *ap;
162 int err;
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700163 int speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164
Alan Coxf34d7a52008-04-30 00:54:13 -0700165 if (tty->ops->write == NULL)
166 return -EOPNOTSUPP;
167
Yoann Padioleaudd00cc42007-07-19 01:49:03 -0700168 ap = kzalloc(sizeof(*ap), GFP_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 err = -ENOMEM;
Joe Perchescd228d52007-11-12 18:07:31 -0800170 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171 goto out;
172
173 /* initialize the syncppp structure */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 ap->tty = tty;
175 ap->mru = PPP_MRU;
176 spin_lock_init(&ap->xmit_lock);
177 spin_lock_init(&ap->recv_lock);
178 ap->xaccm[0] = ~0U;
179 ap->xaccm[3] = 0x60000000U;
180 ap->raccm = ~0U;
181
182 skb_queue_head_init(&ap->rqueue);
183 tasklet_init(&ap->tsk, ppp_sync_process, (unsigned long) ap);
184
185 atomic_set(&ap->refcnt, 1);
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800186 init_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187
188 ap->chan.private = ap;
189 ap->chan.ops = &sync_ops;
190 ap->chan.mtu = PPP_MRU;
191 ap->chan.hdrlen = 2; /* for A/C bytes */
Gabriele Paoloni9c705262009-03-13 16:09:12 -0700192 speed = tty_get_baud_rate(tty);
193 ap->chan.speed = speed;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 err = ppp_register_channel(&ap->chan);
195 if (err)
196 goto out_free;
197
198 tty->disc_data = ap;
Alan Cox33f0f882006-01-09 20:54:13 -0800199 tty->receive_room = 65536;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 return 0;
201
202 out_free:
203 kfree(ap);
204 out:
205 return err;
206}
207
208/*
209 * Called when the tty is put into another line discipline
210 * or it hangs up. We have to wait for any cpu currently
211 * executing in any of the other ppp_synctty_* routines to
212 * finish before we can call ppp_unregister_channel and free
213 * the syncppp struct. This routine must be called from
214 * process context, not interrupt or softirq context.
215 */
216static void
217ppp_sync_close(struct tty_struct *tty)
218{
219 struct syncppp *ap;
220
221 write_lock_irq(&disc_data_lock);
222 ap = tty->disc_data;
223 tty->disc_data = NULL;
224 write_unlock_irq(&disc_data_lock);
Joe Perchescd228d52007-11-12 18:07:31 -0800225 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 return;
227
228 /*
229 * We have now ensured that nobody can start using ap from now
230 * on, but we have to wait for all existing users to finish.
231 * Note that ppp_unregister_channel ensures that no calls to
232 * our channel ops (i.e. ppp_sync_send/ioctl) are in progress
233 * by the time it returns.
234 */
235 if (!atomic_dec_and_test(&ap->refcnt))
Matthias Kaehlcke5e41fb82007-12-14 11:32:48 -0800236 wait_for_completion(&ap->dead_cmp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 tasklet_kill(&ap->tsk);
238
239 ppp_unregister_channel(&ap->chan);
240 skb_queue_purge(&ap->rqueue);
Wei Yongjun1d2f8c92009-02-25 00:16:08 +0000241 kfree_skb(ap->tpkt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 kfree(ap);
243}
244
245/*
246 * Called on tty hangup in process context.
247 *
248 * Wait for I/O to driver to complete and unregister PPP channel.
249 * This is already done by the close routine, so just call that.
250 */
251static int ppp_sync_hangup(struct tty_struct *tty)
252{
253 ppp_sync_close(tty);
254 return 0;
255}
256
257/*
258 * Read does nothing - no data is ever available this way.
259 * Pppd reads and writes packets via /dev/ppp instead.
260 */
261static ssize_t
262ppp_sync_read(struct tty_struct *tty, struct file *file,
263 unsigned char __user *buf, size_t count)
264{
265 return -EAGAIN;
266}
267
268/*
269 * Write on the tty does nothing, the packets all come in
270 * from the ppp generic stuff.
271 */
272static ssize_t
273ppp_sync_write(struct tty_struct *tty, struct file *file,
274 const unsigned char *buf, size_t count)
275{
276 return -EAGAIN;
277}
278
279static int
280ppp_synctty_ioctl(struct tty_struct *tty, struct file *file,
281 unsigned int cmd, unsigned long arg)
282{
283 struct syncppp *ap = sp_get(tty);
284 int __user *p = (int __user *)arg;
285 int err, val;
286
Joe Perchescd228d52007-11-12 18:07:31 -0800287 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 return -ENXIO;
289 err = -EFAULT;
290 switch (cmd) {
291 case PPPIOCGCHAN:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700292 err = -EFAULT;
293 if (put_user(ppp_channel_index(&ap->chan), p))
294 break;
295 err = 0;
296 break;
297
298 case PPPIOCGUNIT:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 err = -EFAULT;
300 if (put_user(ppp_unit_number(&ap->chan), p))
301 break;
302 err = 0;
303 break;
304
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 case TCFLSH:
306 /* flush our buffers and the serial port's buffer */
307 if (arg == TCIOFLUSH || arg == TCOFLUSH)
308 ppp_sync_flush_output(ap);
Peter Hurleye7f38802013-03-11 16:44:45 -0400309 err = n_tty_ioctl_helper(tty, file, cmd, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 break;
311
312 case FIONREAD:
313 val = 0;
314 if (put_user(val, p))
315 break;
316 err = 0;
317 break;
318
319 default:
Alan Coxd0127532007-11-07 01:27:34 -0800320 err = tty_mode_ioctl(tty, file, cmd, arg);
321 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 }
323
324 sp_put(ap);
325 return err;
326}
327
328/* No kernel lock - fine */
329static unsigned int
330ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
331{
332 return 0;
333}
334
Tilman Schmidt92d326f2009-10-01 04:28:44 +0000335/* May sleep, don't call from interrupt level or with interrupts disabled */
Linus Torvalds55db4c62011-06-04 06:33:24 +0900336static void
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
338 char *cflags, int count)
339{
340 struct syncppp *ap = sp_get(tty);
341 unsigned long flags;
342
Joe Perchescd228d52007-11-12 18:07:31 -0800343 if (!ap)
Linus Torvalds55db4c62011-06-04 06:33:24 +0900344 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700345 spin_lock_irqsave(&ap->recv_lock, flags);
346 ppp_sync_input(ap, buf, cflags, count);
347 spin_unlock_irqrestore(&ap->recv_lock, flags);
David S. Millerb03efcf2005-07-08 14:57:23 -0700348 if (!skb_queue_empty(&ap->rqueue))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 tasklet_schedule(&ap->tsk);
350 sp_put(ap);
Linus Torvalds4a21b8c2009-07-16 09:14:23 -0700351 tty_unthrottle(tty);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700352}
353
354static void
355ppp_sync_wakeup(struct tty_struct *tty)
356{
357 struct syncppp *ap = sp_get(tty);
358
359 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Joe Perchescd228d52007-11-12 18:07:31 -0800360 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 return;
362 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
363 tasklet_schedule(&ap->tsk);
364 sp_put(ap);
365}
366
367
Alan Coxa352def2008-07-16 21:53:12 +0100368static struct tty_ldisc_ops ppp_sync_ldisc = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 .owner = THIS_MODULE,
370 .magic = TTY_LDISC_MAGIC,
371 .name = "pppsync",
372 .open = ppp_sync_open,
373 .close = ppp_sync_close,
374 .hangup = ppp_sync_hangup,
375 .read = ppp_sync_read,
376 .write = ppp_sync_write,
377 .ioctl = ppp_synctty_ioctl,
378 .poll = ppp_sync_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379 .receive_buf = ppp_sync_receive,
380 .write_wakeup = ppp_sync_wakeup,
381};
382
383static int __init
384ppp_sync_init(void)
385{
386 int err;
387
388 err = tty_register_ldisc(N_SYNC_PPP, &ppp_sync_ldisc);
389 if (err != 0)
390 printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
391 err);
392 return err;
393}
394
395/*
396 * The following routines provide the PPP channel interface.
397 */
398static int
399ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
400{
401 struct syncppp *ap = chan->private;
402 int err, val;
403 u32 accm[8];
404 void __user *argp = (void __user *)arg;
405 u32 __user *p = argp;
406
407 err = -EFAULT;
408 switch (cmd) {
409 case PPPIOCGFLAGS:
410 val = ap->flags | ap->rbits;
411 if (put_user(val, (int __user *) argp))
412 break;
413 err = 0;
414 break;
415 case PPPIOCSFLAGS:
416 if (get_user(val, (int __user *) argp))
417 break;
418 ap->flags = val & ~SC_RCV_BITS;
419 spin_lock_irq(&ap->recv_lock);
420 ap->rbits = val & SC_RCV_BITS;
421 spin_unlock_irq(&ap->recv_lock);
422 err = 0;
423 break;
424
425 case PPPIOCGASYNCMAP:
426 if (put_user(ap->xaccm[0], p))
427 break;
428 err = 0;
429 break;
430 case PPPIOCSASYNCMAP:
431 if (get_user(ap->xaccm[0], p))
432 break;
433 err = 0;
434 break;
435
436 case PPPIOCGRASYNCMAP:
437 if (put_user(ap->raccm, p))
438 break;
439 err = 0;
440 break;
441 case PPPIOCSRASYNCMAP:
442 if (get_user(ap->raccm, p))
443 break;
444 err = 0;
445 break;
446
447 case PPPIOCGXASYNCMAP:
448 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
449 break;
450 err = 0;
451 break;
452 case PPPIOCSXASYNCMAP:
453 if (copy_from_user(accm, argp, sizeof(accm)))
454 break;
455 accm[2] &= ~0x40000000U; /* can't escape 0x5e */
456 accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
457 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
458 err = 0;
459 break;
460
461 case PPPIOCGMRU:
462 if (put_user(ap->mru, (int __user *) argp))
463 break;
464 err = 0;
465 break;
466 case PPPIOCSMRU:
467 if (get_user(val, (int __user *) argp))
468 break;
Willem de Bruijn3dc60162024-04-17 12:23:47 -0400469 if (val > U16_MAX) {
470 err = -EINVAL;
471 break;
472 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473 if (val < PPP_MRU)
474 val = PPP_MRU;
475 ap->mru = val;
476 err = 0;
477 break;
478
479 default:
480 err = -ENOTTY;
481 }
482 return err;
483}
484
485/*
486 * This is called at softirq level to deliver received packets
487 * to the ppp_generic code, and to tell the ppp_generic code
488 * if we can accept more output now.
489 */
490static void ppp_sync_process(unsigned long arg)
491{
492 struct syncppp *ap = (struct syncppp *) arg;
493 struct sk_buff *skb;
494
495 /* process received packets */
496 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
497 if (skb->len == 0) {
498 /* zero length buffers indicate error */
499 ppp_input_error(&ap->chan, 0);
500 kfree_skb(skb);
501 }
502 else
503 ppp_input(&ap->chan, skb);
504 }
505
506 /* try to push more stuff out */
507 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap))
508 ppp_output_wakeup(&ap->chan);
509}
510
511/*
512 * Procedures for encapsulation and framing.
513 */
514
Stephen Hemminger3c582b32008-01-23 20:54:07 -0800515static struct sk_buff*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
517{
518 int proto;
519 unsigned char *data;
520 int islcp;
521
522 data = skb->data;
Changli Gao96545ae2011-01-06 13:37:36 +0000523 proto = get_unaligned_be16(data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700524
525 /* LCP packets with codes between 1 (configure-request)
526 * and 7 (code-reject) must be sent as though no options
527 * have been negotiated.
528 */
529 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
530
531 /* compress protocol field if option enabled */
532 if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp)
533 skb_pull(skb,1);
534
535 /* prepend address/control fields if necessary */
536 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
537 if (skb_headroom(skb) < 2) {
538 struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
539 if (npkt == NULL) {
540 kfree_skb(skb);
541 return NULL;
542 }
543 skb_reserve(npkt,2);
Arnaldo Carvalho de Melod626f622007-03-27 18:55:52 -0300544 skb_copy_from_linear_data(skb,
545 skb_put(npkt, skb->len), skb->len);
Eric Dumazet968d7012012-05-18 20:23:00 +0000546 consume_skb(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700547 skb = npkt;
548 }
549 skb_push(skb,2);
550 skb->data[0] = PPP_ALLSTATIONS;
551 skb->data[1] = PPP_UI;
552 }
553
554 ap->last_xmit = jiffies;
555
556 if (skb && ap->flags & SC_LOG_OUTPKT)
557 ppp_print_buffer ("send buffer", skb->data, skb->len);
558
559 return skb;
560}
561
562/*
563 * Transmit-side routines.
564 */
565
566/*
567 * Send a packet to the peer over an sync tty line.
568 * Returns 1 iff the packet was accepted.
569 * If the packet was not accepted, we will call ppp_output_wakeup
570 * at some later time.
571 */
572static int
573ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
574{
575 struct syncppp *ap = chan->private;
576
577 ppp_sync_push(ap);
578
579 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
580 return 0; /* already full */
581 skb = ppp_sync_txmunge(ap, skb);
582 if (skb != NULL)
583 ap->tpkt = skb;
584 else
585 clear_bit(XMIT_FULL, &ap->xmit_flags);
586
587 ppp_sync_push(ap);
588 return 1;
589}
590
591/*
592 * Push as much data as possible out to the tty.
593 */
594static int
595ppp_sync_push(struct syncppp *ap)
596{
597 int sent, done = 0;
598 struct tty_struct *tty = ap->tty;
599 int tty_stuffed = 0;
600
601 if (!spin_trylock_bh(&ap->xmit_lock))
602 return 0;
603 for (;;) {
604 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
605 tty_stuffed = 0;
Joe Perchescd228d52007-11-12 18:07:31 -0800606 if (!tty_stuffed && ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Alan Coxf34d7a52008-04-30 00:54:13 -0700608 sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700609 if (sent < 0)
610 goto flush; /* error, e.g. loss of CD */
611 if (sent < ap->tpkt->len) {
612 tty_stuffed = 1;
613 } else {
Eric Dumazet968d7012012-05-18 20:23:00 +0000614 consume_skb(ap->tpkt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700615 ap->tpkt = NULL;
616 clear_bit(XMIT_FULL, &ap->xmit_flags);
617 done = 1;
618 }
619 continue;
620 }
621 /* haven't made any progress */
622 spin_unlock_bh(&ap->xmit_lock);
Joe Perches8e95a202009-12-03 07:58:21 +0000623 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
624 (!tty_stuffed && ap->tpkt)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700625 break;
626 if (!spin_trylock_bh(&ap->xmit_lock))
627 break;
628 }
629 return done;
630
631flush:
Joe Perchescd228d52007-11-12 18:07:31 -0800632 if (ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700633 kfree_skb(ap->tpkt);
634 ap->tpkt = NULL;
635 clear_bit(XMIT_FULL, &ap->xmit_flags);
636 done = 1;
637 }
638 spin_unlock_bh(&ap->xmit_lock);
639 return done;
640}
641
642/*
643 * Flush output from our internal buffers.
644 * Called for the TCFLSH ioctl.
645 */
646static void
647ppp_sync_flush_output(struct syncppp *ap)
648{
649 int done = 0;
650
651 spin_lock_bh(&ap->xmit_lock);
652 if (ap->tpkt != NULL) {
653 kfree_skb(ap->tpkt);
654 ap->tpkt = NULL;
655 clear_bit(XMIT_FULL, &ap->xmit_flags);
656 done = 1;
657 }
658 spin_unlock_bh(&ap->xmit_lock);
659 if (done)
660 ppp_output_wakeup(&ap->chan);
661}
662
663/*
664 * Receive-side routines.
665 */
666
667/* called when the tty driver has data for us.
668 *
669 * Data is frame oriented: each call to ppp_sync_input is considered
670 * a whole frame. If the 1st flag byte is non-zero then the whole
671 * frame is considered to be in error and is tossed.
672 */
673static void
674ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
675 char *flags, int count)
676{
677 struct sk_buff *skb;
678 unsigned char *p;
679
680 if (count == 0)
681 return;
682
683 if (ap->flags & SC_LOG_INPKT)
684 ppp_print_buffer ("receive buffer", buf, count);
685
686 /* stuff the chars in the skb */
Joe Perchescd228d52007-11-12 18:07:31 -0800687 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
688 if (!skb) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
690 goto err;
691 }
692 /* Try to get the payload 4-byte aligned */
693 if (buf[0] != PPP_ALLSTATIONS)
694 skb_reserve(skb, 2 + (buf[0] & 1));
695
Joe Perchescd228d52007-11-12 18:07:31 -0800696 if (flags && *flags) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 /* error flag set, ignore frame */
698 goto err;
699 } else if (count > skb_tailroom(skb)) {
700 /* packet overflowed MRU */
701 goto err;
702 }
703
yuan linyub952f4d2017-06-18 22:52:04 +0800704 skb_put_data(skb, buf, count);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700705
706 /* strip address/control field if present */
707 p = skb->data;
Shigeru Yoshida1fc95522024-04-17 12:23:43 -0400708 if (skb->len >= 2 && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 /* chop off address/control */
710 if (skb->len < 3)
711 goto err;
712 p = skb_pull(skb, 2);
713 }
714
Sam Protsenko7bb4bd32018-12-20 20:29:20 +0200715 /* PPP packet length should be >= 2 bytes when protocol field is not
716 * compressed.
717 */
718 if (!(p[0] & 0x01) && skb->len < 2)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 goto err;
720
721 /* queue the frame to be processed */
722 skb_queue_tail(&ap->rqueue, skb);
723 return;
724
725err:
726 /* queue zero length packet as error indication */
727 if (skb || (skb = dev_alloc_skb(0))) {
728 skb_trim(skb, 0);
729 skb_queue_tail(&ap->rqueue, skb);
730 }
731}
732
733static void __exit
734ppp_sync_cleanup(void)
735{
Alexey Dobriyan64ccd712005-06-23 00:10:33 -0700736 if (tty_unregister_ldisc(N_SYNC_PPP) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737 printk(KERN_ERR "failed to unregister Sync PPP line discipline\n");
738}
739
740module_init(ppp_sync_init);
741module_exit(ppp_sync_cleanup);
742MODULE_LICENSE("GPL");
743MODULE_ALIAS_LDISC(N_SYNC_PPP);