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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * PPP async serial channel driver for Linux.
3 *
4 * Copyright 1999 Paul Mackerras.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 *
11 * This driver provides the encapsulation and framing for sending
12 * and receiving PPP frames over async serial lines. It relies on
13 * the generic PPP layer to give it frames to send and to process
14 * received frames. It implements the PPP line discipline.
15 *
16 * Part of the code in this driver was inspired by the old async-only
17 * PPP driver, written by Michael Callahan and Al Longyear, and
18 * subsequently hacked by Paul Mackerras.
19 */
20
21#include <linux/module.h>
22#include <linux/kernel.h>
23#include <linux/skbuff.h>
24#include <linux/tty.h>
25#include <linux/netdevice.h>
26#include <linux/poll.h>
27#include <linux/crc-ccitt.h>
28#include <linux/ppp_defs.h>
29#include <linux/if_ppp.h>
30#include <linux/ppp_channel.h>
31#include <linux/spinlock.h>
32#include <linux/init.h>
Marcelo Feitoza Parisiff5688a2006-01-09 18:37:15 -080033#include <linux/jiffies.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <asm/uaccess.h>
Philippe De Muyter6722e782005-11-08 09:40:26 -080035#include <asm/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37#define PPP_VERSION "2.4.2"
38
39#define OBUFSIZE 256
40
41/* Structure for storing local state. */
42struct asyncppp {
43 struct tty_struct *tty;
44 unsigned int flags;
45 unsigned int state;
46 unsigned int rbits;
47 int mru;
48 spinlock_t xmit_lock;
49 spinlock_t recv_lock;
50 unsigned long xmit_flags;
51 u32 xaccm[8];
52 u32 raccm;
53 unsigned int bytes_sent;
54 unsigned int bytes_rcvd;
55
56 struct sk_buff *tpkt;
57 int tpkt_pos;
58 u16 tfcs;
59 unsigned char *optr;
60 unsigned char *olim;
61 unsigned long last_xmit;
62
63 struct sk_buff *rpkt;
64 int lcp_fcs;
65 struct sk_buff_head rqueue;
66
67 struct tasklet_struct tsk;
68
69 atomic_t refcnt;
70 struct semaphore dead_sem;
71 struct ppp_channel chan; /* interface to generic ppp layer */
72 unsigned char obuf[OBUFSIZE];
73};
74
75/* Bit numbers in xmit_flags */
76#define XMIT_WAKEUP 0
77#define XMIT_FULL 1
78#define XMIT_BUSY 2
79
80/* State bits */
81#define SC_TOSS 1
82#define SC_ESCAPE 2
83#define SC_PREV_ERROR 4
84
85/* Bits in rbits */
86#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
87
88static int flag_time = HZ;
89module_param(flag_time, int, 0);
90MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");
91MODULE_LICENSE("GPL");
92MODULE_ALIAS_LDISC(N_PPP);
93
94/*
95 * Prototypes.
96 */
97static int ppp_async_encode(struct asyncppp *ap);
98static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);
99static int ppp_async_push(struct asyncppp *ap);
100static void ppp_async_flush_output(struct asyncppp *ap);
101static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
102 char *flags, int count);
103static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd,
104 unsigned long arg);
105static void ppp_async_process(unsigned long arg);
106
107static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
108 int len, int inbound);
109
110static struct ppp_channel_ops async_ops = {
111 ppp_async_send,
112 ppp_async_ioctl
113};
114
115/*
116 * Routines implementing the PPP line discipline.
117 */
118
119/*
120 * We have a potential race on dereferencing tty->disc_data,
121 * because the tty layer provides no locking at all - thus one
122 * cpu could be running ppp_asynctty_receive while another
123 * calls ppp_asynctty_close, which zeroes tty->disc_data and
124 * frees the memory that ppp_asynctty_receive is using. The best
125 * way to fix this is to use a rwlock in the tty struct, but for now
126 * we use a single global rwlock for all ttys in ppp line discipline.
127 *
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400128 * FIXME: this is no longer true. The _close path for the ldisc is
129 * now guaranteed to be sane.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 */
131static DEFINE_RWLOCK(disc_data_lock);
132
133static struct asyncppp *ap_get(struct tty_struct *tty)
134{
135 struct asyncppp *ap;
136
137 read_lock(&disc_data_lock);
138 ap = tty->disc_data;
139 if (ap != NULL)
140 atomic_inc(&ap->refcnt);
141 read_unlock(&disc_data_lock);
142 return ap;
143}
144
145static void ap_put(struct asyncppp *ap)
146{
147 if (atomic_dec_and_test(&ap->refcnt))
148 up(&ap->dead_sem);
149}
150
151/*
152 * Called when a tty is put into PPP line discipline. Called in process
153 * context.
154 */
155static int
156ppp_asynctty_open(struct tty_struct *tty)
157{
158 struct asyncppp *ap;
159 int err;
160
161 err = -ENOMEM;
Yoann Padioleaudd00cc42007-07-19 01:49:03 -0700162 ap = kzalloc(sizeof(*ap), GFP_KERNEL);
Joe Perchescd228d52007-11-12 18:07:31 -0800163 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 goto out;
165
166 /* initialize the asyncppp structure */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 ap->tty = tty;
168 ap->mru = PPP_MRU;
169 spin_lock_init(&ap->xmit_lock);
170 spin_lock_init(&ap->recv_lock);
171 ap->xaccm[0] = ~0U;
172 ap->xaccm[3] = 0x60000000U;
173 ap->raccm = ~0U;
174 ap->optr = ap->obuf;
175 ap->olim = ap->obuf;
176 ap->lcp_fcs = -1;
177
178 skb_queue_head_init(&ap->rqueue);
179 tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap);
180
181 atomic_set(&ap->refcnt, 1);
182 init_MUTEX_LOCKED(&ap->dead_sem);
183
184 ap->chan.private = ap;
185 ap->chan.ops = &async_ops;
186 ap->chan.mtu = PPP_MRU;
187 err = ppp_register_channel(&ap->chan);
188 if (err)
189 goto out_free;
190
191 tty->disc_data = ap;
Alan Cox33f0f882006-01-09 20:54:13 -0800192 tty->receive_room = 65536;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 return 0;
194
195 out_free:
196 kfree(ap);
197 out:
198 return err;
199}
200
201/*
202 * Called when the tty is put into another line discipline
203 * or it hangs up. We have to wait for any cpu currently
204 * executing in any of the other ppp_asynctty_* routines to
205 * finish before we can call ppp_unregister_channel and free
206 * the asyncppp struct. This routine must be called from
207 * process context, not interrupt or softirq context.
208 */
209static void
210ppp_asynctty_close(struct tty_struct *tty)
211{
212 struct asyncppp *ap;
213
214 write_lock_irq(&disc_data_lock);
215 ap = tty->disc_data;
216 tty->disc_data = NULL;
217 write_unlock_irq(&disc_data_lock);
Joe Perchescd228d52007-11-12 18:07:31 -0800218 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219 return;
220
221 /*
222 * We have now ensured that nobody can start using ap from now
223 * on, but we have to wait for all existing users to finish.
224 * Note that ppp_unregister_channel ensures that no calls to
225 * our channel ops (i.e. ppp_async_send/ioctl) are in progress
226 * by the time it returns.
227 */
228 if (!atomic_dec_and_test(&ap->refcnt))
229 down(&ap->dead_sem);
230 tasklet_kill(&ap->tsk);
231
232 ppp_unregister_channel(&ap->chan);
Joe Perchescd228d52007-11-12 18:07:31 -0800233 if (ap->rpkt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700234 kfree_skb(ap->rpkt);
235 skb_queue_purge(&ap->rqueue);
Joe Perchescd228d52007-11-12 18:07:31 -0800236 if (ap->tpkt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700237 kfree_skb(ap->tpkt);
238 kfree(ap);
239}
240
241/*
242 * Called on tty hangup in process context.
243 *
244 * Wait for I/O to driver to complete and unregister PPP channel.
245 * This is already done by the close routine, so just call that.
246 */
247static int ppp_asynctty_hangup(struct tty_struct *tty)
248{
249 ppp_asynctty_close(tty);
250 return 0;
251}
252
253/*
254 * Read does nothing - no data is ever available this way.
255 * Pppd reads and writes packets via /dev/ppp instead.
256 */
257static ssize_t
258ppp_asynctty_read(struct tty_struct *tty, struct file *file,
259 unsigned char __user *buf, size_t count)
260{
261 return -EAGAIN;
262}
263
264/*
265 * Write on the tty does nothing, the packets all come in
266 * from the ppp generic stuff.
267 */
268static ssize_t
269ppp_asynctty_write(struct tty_struct *tty, struct file *file,
270 const unsigned char *buf, size_t count)
271{
272 return -EAGAIN;
273}
274
275/*
276 * Called in process context only. May be re-entered by multiple
277 * ioctl calling threads.
278 */
Jeff Garzik6aa20a22006-09-13 13:24:59 -0400279
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280static int
281ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file,
282 unsigned int cmd, unsigned long arg)
283{
284 struct asyncppp *ap = ap_get(tty);
285 int err, val;
286 int __user *p = (int __user *)arg;
287
Joe Perchescd228d52007-11-12 18:07:31 -0800288 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 return -ENXIO;
290 err = -EFAULT;
291 switch (cmd) {
292 case PPPIOCGCHAN:
293 err = -ENXIO;
Joe Perchescd228d52007-11-12 18:07:31 -0800294 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700295 break;
296 err = -EFAULT;
297 if (put_user(ppp_channel_index(&ap->chan), p))
298 break;
299 err = 0;
300 break;
301
302 case PPPIOCGUNIT:
303 err = -ENXIO;
Joe Perchescd228d52007-11-12 18:07:31 -0800304 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305 break;
306 err = -EFAULT;
307 if (put_user(ppp_unit_number(&ap->chan), p))
308 break;
309 err = 0;
310 break;
311
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312 case TCFLSH:
313 /* flush our buffers and the serial port's buffer */
314 if (arg == TCIOFLUSH || arg == TCOFLUSH)
315 ppp_async_flush_output(ap);
Alan Coxd0127532007-11-07 01:27:34 -0800316 err = tty_perform_flush(tty, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 break;
318
319 case FIONREAD:
320 val = 0;
321 if (put_user(val, p))
322 break;
323 err = 0;
324 break;
325
326 default:
Alan Coxd0127532007-11-07 01:27:34 -0800327 /* Try the various mode ioctls */
328 err = tty_mode_ioctl(tty, file, cmd, arg);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 }
330
331 ap_put(ap);
332 return err;
333}
334
335/* No kernel lock - fine */
336static unsigned int
337ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
338{
339 return 0;
340}
341
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342/*
343 * This can now be called from hard interrupt level as well
344 * as soft interrupt level or mainline.
345 */
346static void
347ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf,
348 char *cflags, int count)
349{
350 struct asyncppp *ap = ap_get(tty);
351 unsigned long flags;
352
Joe Perchescd228d52007-11-12 18:07:31 -0800353 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700354 return;
355 spin_lock_irqsave(&ap->recv_lock, flags);
356 ppp_async_input(ap, buf, cflags, count);
357 spin_unlock_irqrestore(&ap->recv_lock, flags);
David S. Millerb03efcf2005-07-08 14:57:23 -0700358 if (!skb_queue_empty(&ap->rqueue))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 tasklet_schedule(&ap->tsk);
360 ap_put(ap);
361 if (test_and_clear_bit(TTY_THROTTLED, &tty->flags)
362 && tty->driver->unthrottle)
363 tty->driver->unthrottle(tty);
364}
365
366static void
367ppp_asynctty_wakeup(struct tty_struct *tty)
368{
369 struct asyncppp *ap = ap_get(tty);
370
371 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
Joe Perchescd228d52007-11-12 18:07:31 -0800372 if (!ap)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 return;
374 set_bit(XMIT_WAKEUP, &ap->xmit_flags);
375 tasklet_schedule(&ap->tsk);
376 ap_put(ap);
377}
378
379
380static struct tty_ldisc ppp_ldisc = {
381 .owner = THIS_MODULE,
382 .magic = TTY_LDISC_MAGIC,
383 .name = "ppp",
384 .open = ppp_asynctty_open,
385 .close = ppp_asynctty_close,
386 .hangup = ppp_asynctty_hangup,
387 .read = ppp_asynctty_read,
388 .write = ppp_asynctty_write,
389 .ioctl = ppp_asynctty_ioctl,
390 .poll = ppp_asynctty_poll,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391 .receive_buf = ppp_asynctty_receive,
392 .write_wakeup = ppp_asynctty_wakeup,
393};
394
395static int __init
396ppp_async_init(void)
397{
398 int err;
399
400 err = tty_register_ldisc(N_PPP, &ppp_ldisc);
401 if (err != 0)
402 printk(KERN_ERR "PPP_async: error %d registering line disc.\n",
403 err);
404 return err;
405}
406
407/*
408 * The following routines provide the PPP channel interface.
409 */
410static int
411ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
412{
413 struct asyncppp *ap = chan->private;
414 void __user *argp = (void __user *)arg;
415 int __user *p = argp;
416 int err, val;
417 u32 accm[8];
418
419 err = -EFAULT;
420 switch (cmd) {
421 case PPPIOCGFLAGS:
422 val = ap->flags | ap->rbits;
423 if (put_user(val, p))
424 break;
425 err = 0;
426 break;
427 case PPPIOCSFLAGS:
428 if (get_user(val, p))
429 break;
430 ap->flags = val & ~SC_RCV_BITS;
431 spin_lock_irq(&ap->recv_lock);
432 ap->rbits = val & SC_RCV_BITS;
433 spin_unlock_irq(&ap->recv_lock);
434 err = 0;
435 break;
436
437 case PPPIOCGASYNCMAP:
438 if (put_user(ap->xaccm[0], (u32 __user *)argp))
439 break;
440 err = 0;
441 break;
442 case PPPIOCSASYNCMAP:
443 if (get_user(ap->xaccm[0], (u32 __user *)argp))
444 break;
445 err = 0;
446 break;
447
448 case PPPIOCGRASYNCMAP:
449 if (put_user(ap->raccm, (u32 __user *)argp))
450 break;
451 err = 0;
452 break;
453 case PPPIOCSRASYNCMAP:
454 if (get_user(ap->raccm, (u32 __user *)argp))
455 break;
456 err = 0;
457 break;
458
459 case PPPIOCGXASYNCMAP:
460 if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
461 break;
462 err = 0;
463 break;
464 case PPPIOCSXASYNCMAP:
465 if (copy_from_user(accm, argp, sizeof(accm)))
466 break;
467 accm[2] &= ~0x40000000U; /* can't escape 0x5e */
468 accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */
469 memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
470 err = 0;
471 break;
472
473 case PPPIOCGMRU:
474 if (put_user(ap->mru, p))
475 break;
476 err = 0;
477 break;
478 case PPPIOCSMRU:
479 if (get_user(val, p))
480 break;
481 if (val < PPP_MRU)
482 val = PPP_MRU;
483 ap->mru = val;
484 err = 0;
485 break;
486
487 default:
488 err = -ENOTTY;
489 }
490
491 return err;
492}
493
494/*
495 * This is called at softirq level to deliver received packets
496 * to the ppp_generic code, and to tell the ppp_generic code
497 * if we can accept more output now.
498 */
499static void ppp_async_process(unsigned long arg)
500{
501 struct asyncppp *ap = (struct asyncppp *) arg;
502 struct sk_buff *skb;
503
504 /* process received packets */
505 while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
506 if (skb->cb[0])
507 ppp_input_error(&ap->chan, 0);
508 ppp_input(&ap->chan, skb);
509 }
510
511 /* try to push more stuff out */
512 if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap))
513 ppp_output_wakeup(&ap->chan);
514}
515
516/*
517 * Procedures for encapsulation and framing.
518 */
519
520/*
521 * Procedure to encode the data for async serial transmission.
522 * Does octet stuffing (escaping), puts the address/control bytes
523 * on if A/C compression is disabled, and does protocol compression.
524 * Assumes ap->tpkt != 0 on entry.
525 * Returns 1 if we finished the current frame, 0 otherwise.
526 */
527
528#define PUT_BYTE(ap, buf, c, islcp) do { \
529 if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\
530 *buf++ = PPP_ESCAPE; \
531 *buf++ = c ^ 0x20; \
532 } else \
533 *buf++ = c; \
534} while (0)
535
536static int
537ppp_async_encode(struct asyncppp *ap)
538{
539 int fcs, i, count, c, proto;
540 unsigned char *buf, *buflim;
541 unsigned char *data;
542 int islcp;
543
544 buf = ap->obuf;
545 ap->olim = buf;
546 ap->optr = buf;
547 i = ap->tpkt_pos;
548 data = ap->tpkt->data;
549 count = ap->tpkt->len;
550 fcs = ap->tfcs;
551 proto = (data[0] << 8) + data[1];
552
553 /*
554 * LCP packets with code values between 1 (configure-reqest)
555 * and 7 (code-reject) must be sent as though no options
556 * had been negotiated.
557 */
558 islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
559
560 if (i == 0) {
561 if (islcp)
562 async_lcp_peek(ap, data, count, 0);
563
564 /*
565 * Start of a new packet - insert the leading FLAG
566 * character if necessary.
567 */
568 if (islcp || flag_time == 0
Marcelo Feitoza Parisiff5688a2006-01-09 18:37:15 -0800569 || time_after_eq(jiffies, ap->last_xmit + flag_time))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700570 *buf++ = PPP_FLAG;
571 ap->last_xmit = jiffies;
572 fcs = PPP_INITFCS;
573
574 /*
575 * Put in the address/control bytes if necessary
576 */
577 if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
578 PUT_BYTE(ap, buf, 0xff, islcp);
579 fcs = PPP_FCS(fcs, 0xff);
580 PUT_BYTE(ap, buf, 0x03, islcp);
581 fcs = PPP_FCS(fcs, 0x03);
582 }
583 }
584
585 /*
586 * Once we put in the last byte, we need to put in the FCS
587 * and closing flag, so make sure there is at least 7 bytes
588 * of free space in the output buffer.
589 */
590 buflim = ap->obuf + OBUFSIZE - 6;
591 while (i < count && buf < buflim) {
592 c = data[i++];
593 if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT))
594 continue; /* compress protocol field */
595 fcs = PPP_FCS(fcs, c);
596 PUT_BYTE(ap, buf, c, islcp);
597 }
598
599 if (i < count) {
600 /*
601 * Remember where we are up to in this packet.
602 */
603 ap->olim = buf;
604 ap->tpkt_pos = i;
605 ap->tfcs = fcs;
606 return 0;
607 }
608
609 /*
610 * We have finished the packet. Add the FCS and flag.
611 */
612 fcs = ~fcs;
613 c = fcs & 0xff;
614 PUT_BYTE(ap, buf, c, islcp);
615 c = (fcs >> 8) & 0xff;
616 PUT_BYTE(ap, buf, c, islcp);
617 *buf++ = PPP_FLAG;
618 ap->olim = buf;
619
620 kfree_skb(ap->tpkt);
621 ap->tpkt = NULL;
622 return 1;
623}
624
625/*
626 * Transmit-side routines.
627 */
628
629/*
630 * Send a packet to the peer over an async tty line.
631 * Returns 1 iff the packet was accepted.
632 * If the packet was not accepted, we will call ppp_output_wakeup
633 * at some later time.
634 */
635static int
636ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb)
637{
638 struct asyncppp *ap = chan->private;
639
640 ppp_async_push(ap);
641
642 if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
643 return 0; /* already full */
644 ap->tpkt = skb;
645 ap->tpkt_pos = 0;
646
647 ppp_async_push(ap);
648 return 1;
649}
650
651/*
652 * Push as much data as possible out to the tty.
653 */
654static int
655ppp_async_push(struct asyncppp *ap)
656{
657 int avail, sent, done = 0;
658 struct tty_struct *tty = ap->tty;
659 int tty_stuffed = 0;
660
661 /*
662 * We can get called recursively here if the tty write
663 * function calls our wakeup function. This can happen
664 * for example on a pty with both the master and slave
665 * set to PPP line discipline.
666 * We use the XMIT_BUSY bit to detect this and get out,
667 * leaving the XMIT_WAKEUP bit set to tell the other
668 * instance that it may now be able to write more now.
669 */
670 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
671 return 0;
672 spin_lock_bh(&ap->xmit_lock);
673 for (;;) {
674 if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
675 tty_stuffed = 0;
676 if (!tty_stuffed && ap->optr < ap->olim) {
677 avail = ap->olim - ap->optr;
678 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
679 sent = tty->driver->write(tty, ap->optr, avail);
680 if (sent < 0)
681 goto flush; /* error, e.g. loss of CD */
682 ap->optr += sent;
683 if (sent < avail)
684 tty_stuffed = 1;
685 continue;
686 }
Joe Perchescd228d52007-11-12 18:07:31 -0800687 if (ap->optr >= ap->olim && ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688 if (ppp_async_encode(ap)) {
689 /* finished processing ap->tpkt */
690 clear_bit(XMIT_FULL, &ap->xmit_flags);
691 done = 1;
692 }
693 continue;
694 }
695 /*
696 * We haven't made any progress this time around.
697 * Clear XMIT_BUSY to let other callers in, but
698 * after doing so we have to check if anyone set
699 * XMIT_WAKEUP since we last checked it. If they
700 * did, we should try again to set XMIT_BUSY and go
701 * around again in case XMIT_BUSY was still set when
702 * the other caller tried.
703 */
704 clear_bit(XMIT_BUSY, &ap->xmit_flags);
705 /* any more work to do? if not, exit the loop */
706 if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags)
Joe Perchescd228d52007-11-12 18:07:31 -0800707 || (!tty_stuffed && ap->tpkt)))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700708 break;
709 /* more work to do, see if we can do it now */
710 if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags))
711 break;
712 }
713 spin_unlock_bh(&ap->xmit_lock);
714 return done;
715
716flush:
717 clear_bit(XMIT_BUSY, &ap->xmit_flags);
Joe Perchescd228d52007-11-12 18:07:31 -0800718 if (ap->tpkt) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719 kfree_skb(ap->tpkt);
720 ap->tpkt = NULL;
721 clear_bit(XMIT_FULL, &ap->xmit_flags);
722 done = 1;
723 }
724 ap->optr = ap->olim;
725 spin_unlock_bh(&ap->xmit_lock);
726 return done;
727}
728
729/*
730 * Flush output from our internal buffers.
731 * Called for the TCFLSH ioctl. Can be entered in parallel
732 * but this is covered by the xmit_lock.
733 */
734static void
735ppp_async_flush_output(struct asyncppp *ap)
736{
737 int done = 0;
738
739 spin_lock_bh(&ap->xmit_lock);
740 ap->optr = ap->olim;
741 if (ap->tpkt != NULL) {
742 kfree_skb(ap->tpkt);
743 ap->tpkt = NULL;
744 clear_bit(XMIT_FULL, &ap->xmit_flags);
745 done = 1;
746 }
747 spin_unlock_bh(&ap->xmit_lock);
748 if (done)
749 ppp_output_wakeup(&ap->chan);
750}
751
752/*
753 * Receive-side routines.
754 */
755
756/* see how many ordinary chars there are at the start of buf */
757static inline int
758scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count)
759{
760 int i, c;
761
762 for (i = 0; i < count; ++i) {
763 c = buf[i];
764 if (c == PPP_ESCAPE || c == PPP_FLAG
765 || (c < 0x20 && (ap->raccm & (1 << c)) != 0))
766 break;
767 }
768 return i;
769}
770
771/* called when a flag is seen - do end-of-packet processing */
772static void
773process_input_packet(struct asyncppp *ap)
774{
775 struct sk_buff *skb;
776 unsigned char *p;
777 unsigned int len, fcs, proto;
778
779 skb = ap->rpkt;
780 if (ap->state & (SC_TOSS | SC_ESCAPE))
781 goto err;
782
783 if (skb == NULL)
784 return; /* 0-length packet */
785
786 /* check the FCS */
787 p = skb->data;
788 len = skb->len;
789 if (len < 3)
790 goto err; /* too short */
791 fcs = PPP_INITFCS;
792 for (; len > 0; --len)
793 fcs = PPP_FCS(fcs, *p++);
794 if (fcs != PPP_GOODFCS)
795 goto err; /* bad FCS */
796 skb_trim(skb, skb->len - 2);
797
798 /* check for address/control and protocol compression */
799 p = skb->data;
Paul Mackerras7c5050e2007-04-19 13:05:52 -0700800 if (p[0] == PPP_ALLSTATIONS) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700801 /* chop off address/control */
Paul Mackerras7c5050e2007-04-19 13:05:52 -0700802 if (p[1] != PPP_UI || skb->len < 3)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 goto err;
804 p = skb_pull(skb, 2);
805 }
806 proto = p[0];
807 if (proto & 1) {
808 /* protocol is compressed */
809 skb_push(skb, 1)[0] = 0;
810 } else {
811 if (skb->len < 2)
812 goto err;
813 proto = (proto << 8) + p[1];
814 if (proto == PPP_LCP)
815 async_lcp_peek(ap, p, skb->len, 1);
816 }
817
818 /* queue the frame to be processed */
819 skb->cb[0] = ap->state;
820 skb_queue_tail(&ap->rqueue, skb);
821 ap->rpkt = NULL;
822 ap->state = 0;
823 return;
824
825 err:
826 /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */
827 ap->state = SC_PREV_ERROR;
Philippe De Muyter6722e782005-11-08 09:40:26 -0800828 if (skb) {
829 /* make skb appear as freshly allocated */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 skb_trim(skb, 0);
Philippe De Muyter6722e782005-11-08 09:40:26 -0800831 skb_reserve(skb, - skb_headroom(skb));
832 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700833}
834
835/* Called when the tty driver has data for us. Runs parallel with the
836 other ldisc functions but will not be re-entered */
837
838static void
839ppp_async_input(struct asyncppp *ap, const unsigned char *buf,
840 char *flags, int count)
841{
842 struct sk_buff *skb;
843 int c, i, j, n, s, f;
844 unsigned char *sp;
845
846 /* update bits used for 8-bit cleanness detection */
847 if (~ap->rbits & SC_RCV_BITS) {
848 s = 0;
849 for (i = 0; i < count; ++i) {
850 c = buf[i];
Joe Perchescd228d52007-11-12 18:07:31 -0800851 if (flags && flags[i] != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852 continue;
853 s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0;
854 c = ((c >> 4) ^ c) & 0xf;
855 s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP;
856 }
857 ap->rbits |= s;
858 }
859
860 while (count > 0) {
861 /* scan through and see how many chars we can do in bulk */
862 if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE)
863 n = 1;
864 else
865 n = scan_ordinary(ap, buf, count);
866
867 f = 0;
Joe Perchescd228d52007-11-12 18:07:31 -0800868 if (flags && (ap->state & SC_TOSS) == 0) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 /* check the flags to see if any char had an error */
870 for (j = 0; j < n; ++j)
871 if ((f = flags[j]) != 0)
872 break;
873 }
874 if (f != 0) {
875 /* start tossing */
876 ap->state |= SC_TOSS;
877
878 } else if (n > 0 && (ap->state & SC_TOSS) == 0) {
879 /* stuff the chars in the skb */
880 skb = ap->rpkt;
Joe Perchescd228d52007-11-12 18:07:31 -0800881 if (!skb) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
Joe Perchescd228d52007-11-12 18:07:31 -0800883 if (!skb)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884 goto nomem;
Philippe De Muyter6722e782005-11-08 09:40:26 -0800885 ap->rpkt = skb;
886 }
887 if (skb->len == 0) {
888 /* Try to get the payload 4-byte aligned.
889 * This should match the
890 * PPP_ALLSTATIONS/PPP_UI/compressed tests in
891 * process_input_packet, but we do not have
892 * enough chars here to test buf[1] and buf[2].
893 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700894 if (buf[0] != PPP_ALLSTATIONS)
895 skb_reserve(skb, 2 + (buf[0] & 1));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896 }
897 if (n > skb_tailroom(skb)) {
898 /* packet overflowed MRU */
899 ap->state |= SC_TOSS;
900 } else {
901 sp = skb_put(skb, n);
902 memcpy(sp, buf, n);
903 if (ap->state & SC_ESCAPE) {
904 sp[0] ^= 0x20;
905 ap->state &= ~SC_ESCAPE;
906 }
907 }
908 }
909
910 if (n >= count)
911 break;
912
913 c = buf[n];
914 if (flags != NULL && flags[n] != 0) {
915 ap->state |= SC_TOSS;
916 } else if (c == PPP_FLAG) {
917 process_input_packet(ap);
918 } else if (c == PPP_ESCAPE) {
919 ap->state |= SC_ESCAPE;
920 } else if (I_IXON(ap->tty)) {
921 if (c == START_CHAR(ap->tty))
922 start_tty(ap->tty);
923 else if (c == STOP_CHAR(ap->tty))
924 stop_tty(ap->tty);
925 }
926 /* otherwise it's a char in the recv ACCM */
927 ++n;
928
929 buf += n;
Joe Perchescd228d52007-11-12 18:07:31 -0800930 if (flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700931 flags += n;
932 count -= n;
933 }
934 return;
935
936 nomem:
937 printk(KERN_ERR "PPPasync: no memory (input pkt)\n");
938 ap->state |= SC_TOSS;
939}
940
941/*
942 * We look at LCP frames going past so that we can notice
943 * and react to the LCP configure-ack from the peer.
944 * In the situation where the peer has been sent a configure-ack
945 * already, LCP is up once it has sent its configure-ack
946 * so the immediately following packet can be sent with the
947 * configured LCP options. This allows us to process the following
948 * packet correctly without pppd needing to respond quickly.
949 *
950 * We only respond to the received configure-ack if we have just
951 * sent a configure-request, and the configure-ack contains the
952 * same data (this is checked using a 16-bit crc of the data).
953 */
954#define CONFREQ 1 /* LCP code field values */
955#define CONFACK 2
956#define LCP_MRU 1 /* LCP option numbers */
957#define LCP_ASYNCMAP 2
958
959static void async_lcp_peek(struct asyncppp *ap, unsigned char *data,
960 int len, int inbound)
961{
962 int dlen, fcs, i, code;
963 u32 val;
964
965 data += 2; /* skip protocol bytes */
966 len -= 2;
967 if (len < 4) /* 4 = code, ID, length */
968 return;
969 code = data[0];
970 if (code != CONFACK && code != CONFREQ)
971 return;
972 dlen = (data[2] << 8) + data[3];
973 if (len < dlen)
974 return; /* packet got truncated or length is bogus */
975
976 if (code == (inbound? CONFACK: CONFREQ)) {
977 /*
978 * sent confreq or received confack:
979 * calculate the crc of the data from the ID field on.
980 */
981 fcs = PPP_INITFCS;
982 for (i = 1; i < dlen; ++i)
983 fcs = PPP_FCS(fcs, data[i]);
984
985 if (!inbound) {
986 /* outbound confreq - remember the crc for later */
987 ap->lcp_fcs = fcs;
988 return;
989 }
990
991 /* received confack, check the crc */
992 fcs ^= ap->lcp_fcs;
993 ap->lcp_fcs = -1;
994 if (fcs != 0)
995 return;
996 } else if (inbound)
997 return; /* not interested in received confreq */
998
999 /* process the options in the confack */
1000 data += 4;
1001 dlen -= 4;
1002 /* data[0] is code, data[1] is length */
1003 while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) {
1004 switch (data[0]) {
1005 case LCP_MRU:
1006 val = (data[2] << 8) + data[3];
1007 if (inbound)
1008 ap->mru = val;
1009 else
1010 ap->chan.mtu = val;
1011 break;
1012 case LCP_ASYNCMAP:
1013 val = (data[2] << 24) + (data[3] << 16)
1014 + (data[4] << 8) + data[5];
1015 if (inbound)
1016 ap->raccm = val;
1017 else
1018 ap->xaccm[0] = val;
1019 break;
1020 }
1021 dlen -= data[1];
1022 data += data[1];
1023 }
1024}
1025
1026static void __exit ppp_async_cleanup(void)
1027{
Alexey Dobriyan64ccd712005-06-23 00:10:33 -07001028 if (tty_unregister_ldisc(N_PPP) != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 printk(KERN_ERR "failed to unregister PPP line discipline\n");
1030}
1031
1032module_init(ppp_async_init);
1033module_exit(ppp_async_cleanup);