GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / tty / pty.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  Copyright (C) 1991, 1992  Linus Torvalds
4  *
5  *  Added support for a Unix98-style ptmx device.
6  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
7  *
8  */
9
10 #include <linux/module.h>
11 #include <linux/errno.h>
12 #include <linux/interrupt.h>
13 #include <linux/tty.h>
14 #include <linux/tty_flip.h>
15 #include <linux/fcntl.h>
16 #include <linux/sched/signal.h>
17 #include <linux/string.h>
18 #include <linux/major.h>
19 #include <linux/mm.h>
20 #include <linux/init.h>
21 #include <linux/device.h>
22 #include <linux/uaccess.h>
23 #include <linux/bitops.h>
24 #include <linux/devpts_fs.h>
25 #include <linux/slab.h>
26 #include <linux/mutex.h>
27 #include <linux/poll.h>
28 #include <linux/mount.h>
29 #include <linux/file.h>
30 #include <linux/ioctl.h>
31 #include <linux/compat.h>
32 #include "tty.h"
33
34 #undef TTY_DEBUG_HANGUP
35 #ifdef TTY_DEBUG_HANGUP
36 # define tty_debug_hangup(tty, f, args...)      tty_debug(tty, f, ##args)
37 #else
38 # define tty_debug_hangup(tty, f, args...)      do {} while (0)
39 #endif
40
41 #ifdef CONFIG_UNIX98_PTYS
42 static struct tty_driver *ptm_driver;
43 static struct tty_driver *pts_driver;
44 static DEFINE_MUTEX(devpts_mutex);
45 #endif
46
47 static void pty_close(struct tty_struct *tty, struct file *filp)
48 {
49         if (tty->driver->subtype == PTY_TYPE_MASTER)
50                 WARN_ON(tty->count > 1);
51         else {
52                 if (tty_io_error(tty))
53                         return;
54                 if (tty->count > 2)
55                         return;
56         }
57         set_bit(TTY_IO_ERROR, &tty->flags);
58         wake_up_interruptible(&tty->read_wait);
59         wake_up_interruptible(&tty->write_wait);
60         spin_lock_irq(&tty->ctrl.lock);
61         tty->ctrl.packet = false;
62         spin_unlock_irq(&tty->ctrl.lock);
63         /* Review - krefs on tty_link ?? */
64         if (!tty->link)
65                 return;
66         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
67         wake_up_interruptible(&tty->link->read_wait);
68         wake_up_interruptible(&tty->link->write_wait);
69         if (tty->driver->subtype == PTY_TYPE_MASTER) {
70                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
71 #ifdef CONFIG_UNIX98_PTYS
72                 if (tty->driver == ptm_driver) {
73                         mutex_lock(&devpts_mutex);
74                         if (tty->link->driver_data)
75                                 devpts_pty_kill(tty->link->driver_data);
76                         mutex_unlock(&devpts_mutex);
77                 }
78 #endif
79                 tty_vhangup(tty->link);
80         }
81 }
82
83 /*
84  * The unthrottle routine is called by the line discipline to signal
85  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
86  * flag is always set, to force the line discipline to always call the
87  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
88  * characters in the queue.  This is necessary since each time this
89  * happens, we need to wake up any sleeping processes that could be
90  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
91  * for the pty buffer to be drained.
92  */
93 static void pty_unthrottle(struct tty_struct *tty)
94 {
95         tty_wakeup(tty->link);
96         set_bit(TTY_THROTTLED, &tty->flags);
97 }
98
99 /**
100  *      pty_write               -       write to a pty
101  *      @tty: the tty we write from
102  *      @buf: kernel buffer of data
103  *      @c: bytes to write
104  *
105  *      Our "hardware" write method. Data is coming from the ldisc which
106  *      may be in a non sleeping state. We simply throw this at the other
107  *      end of the link as if we were an IRQ handler receiving stuff for
108  *      the other side of the pty/tty pair.
109  */
110
111 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
112 {
113         struct tty_struct *to = tty->link;
114         unsigned long flags;
115
116         if (tty->flow.stopped)
117                 return 0;
118
119         if (c > 0) {
120                 spin_lock_irqsave(&to->port->lock, flags);
121                 /* Stuff the data into the input queue of the other end */
122                 c = tty_insert_flip_string(to->port, buf, c);
123                 spin_unlock_irqrestore(&to->port->lock, flags);
124                 /* And shovel */
125                 if (c)
126                         tty_flip_buffer_push(to->port);
127         }
128         return c;
129 }
130
131 /**
132  *      pty_write_room  -       write space
133  *      @tty: tty we are writing from
134  *
135  *      Report how many bytes the ldisc can send into the queue for
136  *      the other device.
137  */
138
139 static unsigned int pty_write_room(struct tty_struct *tty)
140 {
141         if (tty->flow.stopped)
142                 return 0;
143         return tty_buffer_space_avail(tty->link->port);
144 }
145
146 /* Set the lock flag on a pty */
147 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
148 {
149         int val;
150
151         if (get_user(val, arg))
152                 return -EFAULT;
153         if (val)
154                 set_bit(TTY_PTY_LOCK, &tty->flags);
155         else
156                 clear_bit(TTY_PTY_LOCK, &tty->flags);
157         return 0;
158 }
159
160 static int pty_get_lock(struct tty_struct *tty, int __user *arg)
161 {
162         int locked = test_bit(TTY_PTY_LOCK, &tty->flags);
163
164         return put_user(locked, arg);
165 }
166
167 /* Set the packet mode on a pty */
168 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg)
169 {
170         int pktmode;
171
172         if (get_user(pktmode, arg))
173                 return -EFAULT;
174
175         spin_lock_irq(&tty->ctrl.lock);
176         if (pktmode) {
177                 if (!tty->ctrl.packet) {
178                         tty->link->ctrl.pktstatus = 0;
179                         smp_mb();
180                         tty->ctrl.packet = true;
181                 }
182         } else
183                 tty->ctrl.packet = false;
184         spin_unlock_irq(&tty->ctrl.lock);
185
186         return 0;
187 }
188
189 /* Get the packet mode of a pty */
190 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg)
191 {
192         int pktmode = tty->ctrl.packet;
193
194         return put_user(pktmode, arg);
195 }
196
197 /* Send a signal to the slave */
198 static int pty_signal(struct tty_struct *tty, int sig)
199 {
200         struct pid *pgrp;
201
202         if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP)
203                 return -EINVAL;
204
205         if (tty->link) {
206                 pgrp = tty_get_pgrp(tty->link);
207                 if (pgrp)
208                         kill_pgrp(pgrp, sig, 1);
209                 put_pid(pgrp);
210         }
211         return 0;
212 }
213
214 static void pty_flush_buffer(struct tty_struct *tty)
215 {
216         struct tty_struct *to = tty->link;
217
218         if (!to)
219                 return;
220
221         tty_buffer_flush(to, NULL);
222         if (to->ctrl.packet) {
223                 spin_lock_irq(&tty->ctrl.lock);
224                 tty->ctrl.pktstatus |= TIOCPKT_FLUSHWRITE;
225                 wake_up_interruptible(&to->read_wait);
226                 spin_unlock_irq(&tty->ctrl.lock);
227         }
228 }
229
230 static int pty_open(struct tty_struct *tty, struct file *filp)
231 {
232         if (!tty || !tty->link)
233                 return -ENODEV;
234
235         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
236                 goto out;
237         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
238                 goto out;
239         if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1)
240                 goto out;
241
242         clear_bit(TTY_IO_ERROR, &tty->flags);
243         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
244         set_bit(TTY_THROTTLED, &tty->flags);
245         return 0;
246
247 out:
248         set_bit(TTY_IO_ERROR, &tty->flags);
249         return -EIO;
250 }
251
252 static void pty_set_termios(struct tty_struct *tty,
253                                         struct ktermios *old_termios)
254 {
255         /* See if packet mode change of state. */
256         if (tty->link && tty->link->ctrl.packet) {
257                 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty);
258                 int old_flow = ((old_termios->c_iflag & IXON) &&
259                                 (old_termios->c_cc[VSTOP] == '\023') &&
260                                 (old_termios->c_cc[VSTART] == '\021'));
261                 int new_flow = (I_IXON(tty) &&
262                                 STOP_CHAR(tty) == '\023' &&
263                                 START_CHAR(tty) == '\021');
264                 if ((old_flow != new_flow) || extproc) {
265                         spin_lock_irq(&tty->ctrl.lock);
266                         if (old_flow != new_flow) {
267                                 tty->ctrl.pktstatus &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
268                                 if (new_flow)
269                                         tty->ctrl.pktstatus |= TIOCPKT_DOSTOP;
270                                 else
271                                         tty->ctrl.pktstatus |= TIOCPKT_NOSTOP;
272                         }
273                         if (extproc)
274                                 tty->ctrl.pktstatus |= TIOCPKT_IOCTL;
275                         spin_unlock_irq(&tty->ctrl.lock);
276                         wake_up_interruptible(&tty->link->read_wait);
277                 }
278         }
279
280         tty->termios.c_cflag &= ~(CSIZE | PARENB);
281         tty->termios.c_cflag |= (CS8 | CREAD);
282 }
283
284 /**
285  *      pty_resize              -       resize event
286  *      @tty: tty being resized
287  *      @ws: window size being set.
288  *
289  *      Update the termios variables and send the necessary signals to
290  *      peform a terminal resize correctly
291  */
292
293 static int pty_resize(struct tty_struct *tty,  struct winsize *ws)
294 {
295         struct pid *pgrp, *rpgrp;
296         struct tty_struct *pty = tty->link;
297
298         /* For a PTY we need to lock the tty side */
299         mutex_lock(&tty->winsize_mutex);
300         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
301                 goto done;
302
303         /* Signal the foreground process group of both ptys */
304         pgrp = tty_get_pgrp(tty);
305         rpgrp = tty_get_pgrp(pty);
306
307         if (pgrp)
308                 kill_pgrp(pgrp, SIGWINCH, 1);
309         if (rpgrp != pgrp && rpgrp)
310                 kill_pgrp(rpgrp, SIGWINCH, 1);
311
312         put_pid(pgrp);
313         put_pid(rpgrp);
314
315         tty->winsize = *ws;
316         pty->winsize = *ws;     /* Never used so will go away soon */
317 done:
318         mutex_unlock(&tty->winsize_mutex);
319         return 0;
320 }
321
322 /**
323  *      pty_start - start() handler
324  *      pty_stop  - stop() handler
325  *      @tty: tty being flow-controlled
326  *
327  *      Propagates the TIOCPKT status to the master pty.
328  *
329  *      NB: only the master pty can be in packet mode so only the slave
330  *          needs start()/stop() handlers
331  */
332 static void pty_start(struct tty_struct *tty)
333 {
334         unsigned long flags;
335
336         if (tty->link && tty->link->ctrl.packet) {
337                 spin_lock_irqsave(&tty->ctrl.lock, flags);
338                 tty->ctrl.pktstatus &= ~TIOCPKT_STOP;
339                 tty->ctrl.pktstatus |= TIOCPKT_START;
340                 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
341                 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
342         }
343 }
344
345 static void pty_stop(struct tty_struct *tty)
346 {
347         unsigned long flags;
348
349         if (tty->link && tty->link->ctrl.packet) {
350                 spin_lock_irqsave(&tty->ctrl.lock, flags);
351                 tty->ctrl.pktstatus &= ~TIOCPKT_START;
352                 tty->ctrl.pktstatus |= TIOCPKT_STOP;
353                 spin_unlock_irqrestore(&tty->ctrl.lock, flags);
354                 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN);
355         }
356 }
357
358 /**
359  *      pty_common_install              -       set up the pty pair
360  *      @driver: the pty driver
361  *      @tty: the tty being instantiated
362  *      @legacy: true if this is BSD style
363  *
364  *      Perform the initial set up for the tty/pty pair. Called from the
365  *      tty layer when the port is first opened.
366  *
367  *      Locking: the caller must hold the tty_mutex
368  */
369 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
370                 bool legacy)
371 {
372         struct tty_struct *o_tty;
373         struct tty_port *ports[2];
374         int idx = tty->index;
375         int retval = -ENOMEM;
376
377         /* Opening the slave first has always returned -EIO */
378         if (driver->subtype != PTY_TYPE_MASTER)
379                 return -EIO;
380
381         ports[0] = kmalloc(sizeof **ports, GFP_KERNEL);
382         ports[1] = kmalloc(sizeof **ports, GFP_KERNEL);
383         if (!ports[0] || !ports[1])
384                 goto err;
385         if (!try_module_get(driver->other->owner)) {
386                 /* This cannot in fact currently happen */
387                 goto err;
388         }
389         o_tty = alloc_tty_struct(driver->other, idx);
390         if (!o_tty)
391                 goto err_put_module;
392
393         tty_set_lock_subclass(o_tty);
394         lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE);
395
396         if (legacy) {
397                 /* We always use new tty termios data so we can do this
398                    the easy way .. */
399                 tty_init_termios(tty);
400                 tty_init_termios(o_tty);
401
402                 driver->other->ttys[idx] = o_tty;
403                 driver->ttys[idx] = tty;
404         } else {
405                 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked));
406                 tty->termios = driver->init_termios;
407                 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked));
408                 o_tty->termios = driver->other->init_termios;
409         }
410
411         /*
412          * Everything allocated ... set up the o_tty structure.
413          */
414         tty_driver_kref_get(driver->other);
415         /* Establish the links in both directions */
416         tty->link   = o_tty;
417         o_tty->link = tty;
418         tty_port_init(ports[0]);
419         tty_port_init(ports[1]);
420         tty_buffer_set_limit(ports[0], 8192);
421         tty_buffer_set_limit(ports[1], 8192);
422         o_tty->port = ports[0];
423         tty->port = ports[1];
424         o_tty->port->itty = o_tty;
425
426         tty_buffer_set_lock_subclass(o_tty->port);
427
428         tty_driver_kref_get(driver);
429         tty->count++;
430         o_tty->count++;
431         return 0;
432
433 err_put_module:
434         module_put(driver->other->owner);
435 err:
436         kfree(ports[0]);
437         kfree(ports[1]);
438         return retval;
439 }
440
441 static void pty_cleanup(struct tty_struct *tty)
442 {
443         tty_port_put(tty->port);
444 }
445
446 /* Traditional BSD devices */
447 #ifdef CONFIG_LEGACY_PTYS
448
449 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
450 {
451         return pty_common_install(driver, tty, true);
452 }
453
454 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty)
455 {
456         struct tty_struct *pair = tty->link;
457
458         driver->ttys[tty->index] = NULL;
459         if (pair)
460                 pair->driver->ttys[pair->index] = NULL;
461 }
462
463 static int pty_bsd_ioctl(struct tty_struct *tty,
464                          unsigned int cmd, unsigned long arg)
465 {
466         switch (cmd) {
467         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
468                 return pty_set_lock(tty, (int __user *) arg);
469         case TIOCGPTLCK: /* Get PT Lock status */
470                 return pty_get_lock(tty, (int __user *)arg);
471         case TIOCPKT: /* Set PT packet mode */
472                 return pty_set_pktmode(tty, (int __user *)arg);
473         case TIOCGPKT: /* Get PT packet mode */
474                 return pty_get_pktmode(tty, (int __user *)arg);
475         case TIOCSIG:    /* Send signal to other side of pty */
476                 return pty_signal(tty, (int) arg);
477         case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */
478                 return -EINVAL;
479         }
480         return -ENOIOCTLCMD;
481 }
482
483 #ifdef CONFIG_COMPAT
484 static long pty_bsd_compat_ioctl(struct tty_struct *tty,
485                                  unsigned int cmd, unsigned long arg)
486 {
487         /*
488          * PTY ioctls don't require any special translation between 32-bit and
489          * 64-bit userspace, they are already compatible.
490          */
491         return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg));
492 }
493 #else
494 #define pty_bsd_compat_ioctl NULL
495 #endif
496
497 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
498 /*
499  * not really modular, but the easiest way to keep compat with existing
500  * bootargs behaviour is to continue using module_param here.
501  */
502 module_param(legacy_count, int, 0);
503
504 /*
505  * The master side of a pty can do TIOCSPTLCK and thus
506  * has pty_bsd_ioctl.
507  */
508 static const struct tty_operations master_pty_ops_bsd = {
509         .install = pty_install,
510         .open = pty_open,
511         .close = pty_close,
512         .write = pty_write,
513         .write_room = pty_write_room,
514         .flush_buffer = pty_flush_buffer,
515         .unthrottle = pty_unthrottle,
516         .ioctl = pty_bsd_ioctl,
517         .compat_ioctl = pty_bsd_compat_ioctl,
518         .cleanup = pty_cleanup,
519         .resize = pty_resize,
520         .remove = pty_remove
521 };
522
523 static const struct tty_operations slave_pty_ops_bsd = {
524         .install = pty_install,
525         .open = pty_open,
526         .close = pty_close,
527         .write = pty_write,
528         .write_room = pty_write_room,
529         .flush_buffer = pty_flush_buffer,
530         .unthrottle = pty_unthrottle,
531         .set_termios = pty_set_termios,
532         .cleanup = pty_cleanup,
533         .resize = pty_resize,
534         .start = pty_start,
535         .stop = pty_stop,
536         .remove = pty_remove
537 };
538
539 static void __init legacy_pty_init(void)
540 {
541         struct tty_driver *pty_driver, *pty_slave_driver;
542
543         if (legacy_count <= 0)
544                 return;
545
546         pty_driver = tty_alloc_driver(legacy_count,
547                         TTY_DRIVER_RESET_TERMIOS |
548                         TTY_DRIVER_REAL_RAW |
549                         TTY_DRIVER_DYNAMIC_ALLOC);
550         if (IS_ERR(pty_driver))
551                 panic("Couldn't allocate pty driver");
552
553         pty_slave_driver = tty_alloc_driver(legacy_count,
554                         TTY_DRIVER_RESET_TERMIOS |
555                         TTY_DRIVER_REAL_RAW |
556                         TTY_DRIVER_DYNAMIC_ALLOC);
557         if (IS_ERR(pty_slave_driver))
558                 panic("Couldn't allocate pty slave driver");
559
560         pty_driver->driver_name = "pty_master";
561         pty_driver->name = "pty";
562         pty_driver->major = PTY_MASTER_MAJOR;
563         pty_driver->minor_start = 0;
564         pty_driver->type = TTY_DRIVER_TYPE_PTY;
565         pty_driver->subtype = PTY_TYPE_MASTER;
566         pty_driver->init_termios = tty_std_termios;
567         pty_driver->init_termios.c_iflag = 0;
568         pty_driver->init_termios.c_oflag = 0;
569         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
570         pty_driver->init_termios.c_lflag = 0;
571         pty_driver->init_termios.c_ispeed = 38400;
572         pty_driver->init_termios.c_ospeed = 38400;
573         pty_driver->other = pty_slave_driver;
574         tty_set_operations(pty_driver, &master_pty_ops_bsd);
575
576         pty_slave_driver->driver_name = "pty_slave";
577         pty_slave_driver->name = "ttyp";
578         pty_slave_driver->major = PTY_SLAVE_MAJOR;
579         pty_slave_driver->minor_start = 0;
580         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
581         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
582         pty_slave_driver->init_termios = tty_std_termios;
583         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
584         pty_slave_driver->init_termios.c_ispeed = 38400;
585         pty_slave_driver->init_termios.c_ospeed = 38400;
586         pty_slave_driver->other = pty_driver;
587         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
588
589         if (tty_register_driver(pty_driver))
590                 panic("Couldn't register pty driver");
591         if (tty_register_driver(pty_slave_driver))
592                 panic("Couldn't register pty slave driver");
593 }
594 #else
595 static inline void legacy_pty_init(void) { }
596 #endif
597
598 /* Unix98 devices */
599 #ifdef CONFIG_UNIX98_PTYS
600 static struct cdev ptmx_cdev;
601
602 /**
603  *      ptm_open_peer - open the peer of a pty
604  *      @master: the open struct file of the ptmx device node
605  *      @tty: the master of the pty being opened
606  *      @flags: the flags for open
607  *
608  *      Provide a race free way for userspace to open the slave end of a pty
609  *      (where they have the master fd and cannot access or trust the mount
610  *      namespace /dev/pts was mounted inside).
611  */
612 int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags)
613 {
614         int fd;
615         struct file *filp;
616         int retval = -EINVAL;
617         struct path path;
618
619         if (tty->driver != ptm_driver)
620                 return -EIO;
621
622         fd = get_unused_fd_flags(flags);
623         if (fd < 0) {
624                 retval = fd;
625                 goto err;
626         }
627
628         /* Compute the slave's path */
629         path.mnt = devpts_mntget(master, tty->driver_data);
630         if (IS_ERR(path.mnt)) {
631                 retval = PTR_ERR(path.mnt);
632                 goto err_put;
633         }
634         path.dentry = tty->link->driver_data;
635
636         filp = dentry_open(&path, flags, current_cred());
637         mntput(path.mnt);
638         if (IS_ERR(filp)) {
639                 retval = PTR_ERR(filp);
640                 goto err_put;
641         }
642
643         fd_install(fd, filp);
644         return fd;
645
646 err_put:
647         put_unused_fd(fd);
648 err:
649         return retval;
650 }
651
652 static int pty_unix98_ioctl(struct tty_struct *tty,
653                             unsigned int cmd, unsigned long arg)
654 {
655         switch (cmd) {
656         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
657                 return pty_set_lock(tty, (int __user *)arg);
658         case TIOCGPTLCK: /* Get PT Lock status */
659                 return pty_get_lock(tty, (int __user *)arg);
660         case TIOCPKT: /* Set PT packet mode */
661                 return pty_set_pktmode(tty, (int __user *)arg);
662         case TIOCGPKT: /* Get PT packet mode */
663                 return pty_get_pktmode(tty, (int __user *)arg);
664         case TIOCGPTN: /* Get PT Number */
665                 return put_user(tty->index, (unsigned int __user *)arg);
666         case TIOCSIG:    /* Send signal to other side of pty */
667                 return pty_signal(tty, (int) arg);
668         }
669
670         return -ENOIOCTLCMD;
671 }
672
673 #ifdef CONFIG_COMPAT
674 static long pty_unix98_compat_ioctl(struct tty_struct *tty,
675                                  unsigned int cmd, unsigned long arg)
676 {
677         /*
678          * PTY ioctls don't require any special translation between 32-bit and
679          * 64-bit userspace, they are already compatible.
680          */
681         return pty_unix98_ioctl(tty, cmd,
682                 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg));
683 }
684 #else
685 #define pty_unix98_compat_ioctl NULL
686 #endif
687
688 /**
689  *      ptm_unix98_lookup       -       find a pty master
690  *      @driver: ptm driver
691  *      @file: unused
692  *      @idx: tty index
693  *
694  *      Look up a pty master device. Called under the tty_mutex for now.
695  *      This provides our locking.
696  */
697
698 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
699                 struct file *file, int idx)
700 {
701         /* Master must be open via /dev/ptmx */
702         return ERR_PTR(-EIO);
703 }
704
705 /**
706  *      pts_unix98_lookup       -       find a pty slave
707  *      @driver: pts driver
708  *      @file: file pointer to tty
709  *      @idx: tty index
710  *
711  *      Look up a pty master device. Called under the tty_mutex for now.
712  *      This provides our locking for the tty pointer.
713  */
714
715 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
716                 struct file *file, int idx)
717 {
718         struct tty_struct *tty;
719
720         mutex_lock(&devpts_mutex);
721         tty = devpts_get_priv(file->f_path.dentry);
722         mutex_unlock(&devpts_mutex);
723         /* Master must be open before slave */
724         if (!tty)
725                 return ERR_PTR(-EIO);
726         return tty;
727 }
728
729 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
730 {
731         return pty_common_install(driver, tty, false);
732 }
733
734 /* this is called once with whichever end is closed last */
735 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
736 {
737         struct pts_fs_info *fsi;
738
739         if (tty->driver->subtype == PTY_TYPE_MASTER)
740                 fsi = tty->driver_data;
741         else
742                 fsi = tty->link->driver_data;
743
744         if (fsi) {
745                 devpts_kill_index(fsi, tty->index);
746                 devpts_release(fsi);
747         }
748 }
749
750 static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m)
751 {
752         seq_printf(m, "tty-index:\t%d\n", tty->index);
753 }
754
755 static const struct tty_operations ptm_unix98_ops = {
756         .lookup = ptm_unix98_lookup,
757         .install = pty_unix98_install,
758         .remove = pty_unix98_remove,
759         .open = pty_open,
760         .close = pty_close,
761         .write = pty_write,
762         .write_room = pty_write_room,
763         .flush_buffer = pty_flush_buffer,
764         .unthrottle = pty_unthrottle,
765         .ioctl = pty_unix98_ioctl,
766         .compat_ioctl = pty_unix98_compat_ioctl,
767         .resize = pty_resize,
768         .cleanup = pty_cleanup,
769         .show_fdinfo = pty_show_fdinfo,
770 };
771
772 static const struct tty_operations pty_unix98_ops = {
773         .lookup = pts_unix98_lookup,
774         .install = pty_unix98_install,
775         .remove = pty_unix98_remove,
776         .open = pty_open,
777         .close = pty_close,
778         .write = pty_write,
779         .write_room = pty_write_room,
780         .flush_buffer = pty_flush_buffer,
781         .unthrottle = pty_unthrottle,
782         .set_termios = pty_set_termios,
783         .start = pty_start,
784         .stop = pty_stop,
785         .cleanup = pty_cleanup,
786 };
787
788 /**
789  *      ptmx_open               -       open a unix 98 pty master
790  *      @inode: inode of device file
791  *      @filp: file pointer to tty
792  *
793  *      Allocate a unix98 pty master device from the ptmx driver.
794  *
795  *      Locking: tty_mutex protects the init_dev work. tty->count should
796  *              protect the rest.
797  *              allocated_ptys_lock handles the list of free pty numbers
798  */
799
800 static int ptmx_open(struct inode *inode, struct file *filp)
801 {
802         struct pts_fs_info *fsi;
803         struct tty_struct *tty;
804         struct dentry *dentry;
805         int retval;
806         int index;
807
808         nonseekable_open(inode, filp);
809
810         /* We refuse fsnotify events on ptmx, since it's a shared resource */
811         filp->f_mode |= FMODE_NONOTIFY;
812
813         retval = tty_alloc_file(filp);
814         if (retval)
815                 return retval;
816
817         fsi = devpts_acquire(filp);
818         if (IS_ERR(fsi)) {
819                 retval = PTR_ERR(fsi);
820                 goto out_free_file;
821         }
822
823         /* find a device that is not in use. */
824         mutex_lock(&devpts_mutex);
825         index = devpts_new_index(fsi);
826         mutex_unlock(&devpts_mutex);
827
828         retval = index;
829         if (index < 0)
830                 goto out_put_fsi;
831
832
833         mutex_lock(&tty_mutex);
834         tty = tty_init_dev(ptm_driver, index);
835         /* The tty returned here is locked so we can safely
836            drop the mutex */
837         mutex_unlock(&tty_mutex);
838
839         retval = PTR_ERR(tty);
840         if (IS_ERR(tty))
841                 goto out;
842
843         /*
844          * From here on out, the tty is "live", and the index and
845          * fsi will be killed/put by the tty_release()
846          */
847         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
848         tty->driver_data = fsi;
849
850         tty_add_file(tty, filp);
851
852         dentry = devpts_pty_new(fsi, index, tty->link);
853         if (IS_ERR(dentry)) {
854                 retval = PTR_ERR(dentry);
855                 goto err_release;
856         }
857         tty->link->driver_data = dentry;
858
859         retval = ptm_driver->ops->open(tty, filp);
860         if (retval)
861                 goto err_release;
862
863         tty_debug_hangup(tty, "opening (count=%d)\n", tty->count);
864
865         tty_unlock(tty);
866         return 0;
867 err_release:
868         tty_unlock(tty);
869         // This will also put-ref the fsi
870         tty_release(inode, filp);
871         return retval;
872 out:
873         devpts_kill_index(fsi, index);
874 out_put_fsi:
875         devpts_release(fsi);
876 out_free_file:
877         tty_free_file(filp);
878         return retval;
879 }
880
881 static struct file_operations ptmx_fops __ro_after_init;
882
883 static void __init unix98_pty_init(void)
884 {
885         ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
886                         TTY_DRIVER_RESET_TERMIOS |
887                         TTY_DRIVER_REAL_RAW |
888                         TTY_DRIVER_DYNAMIC_DEV |
889                         TTY_DRIVER_DEVPTS_MEM |
890                         TTY_DRIVER_DYNAMIC_ALLOC);
891         if (IS_ERR(ptm_driver))
892                 panic("Couldn't allocate Unix98 ptm driver");
893         pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX,
894                         TTY_DRIVER_RESET_TERMIOS |
895                         TTY_DRIVER_REAL_RAW |
896                         TTY_DRIVER_DYNAMIC_DEV |
897                         TTY_DRIVER_DEVPTS_MEM |
898                         TTY_DRIVER_DYNAMIC_ALLOC);
899         if (IS_ERR(pts_driver))
900                 panic("Couldn't allocate Unix98 pts driver");
901
902         ptm_driver->driver_name = "pty_master";
903         ptm_driver->name = "ptm";
904         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
905         ptm_driver->minor_start = 0;
906         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
907         ptm_driver->subtype = PTY_TYPE_MASTER;
908         ptm_driver->init_termios = tty_std_termios;
909         ptm_driver->init_termios.c_iflag = 0;
910         ptm_driver->init_termios.c_oflag = 0;
911         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
912         ptm_driver->init_termios.c_lflag = 0;
913         ptm_driver->init_termios.c_ispeed = 38400;
914         ptm_driver->init_termios.c_ospeed = 38400;
915         ptm_driver->other = pts_driver;
916         tty_set_operations(ptm_driver, &ptm_unix98_ops);
917
918         pts_driver->driver_name = "pty_slave";
919         pts_driver->name = "pts";
920         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
921         pts_driver->minor_start = 0;
922         pts_driver->type = TTY_DRIVER_TYPE_PTY;
923         pts_driver->subtype = PTY_TYPE_SLAVE;
924         pts_driver->init_termios = tty_std_termios;
925         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
926         pts_driver->init_termios.c_ispeed = 38400;
927         pts_driver->init_termios.c_ospeed = 38400;
928         pts_driver->other = ptm_driver;
929         tty_set_operations(pts_driver, &pty_unix98_ops);
930
931         if (tty_register_driver(ptm_driver))
932                 panic("Couldn't register Unix98 ptm driver");
933         if (tty_register_driver(pts_driver))
934                 panic("Couldn't register Unix98 pts driver");
935
936         /* Now create the /dev/ptmx special device */
937         tty_default_fops(&ptmx_fops);
938         ptmx_fops.open = ptmx_open;
939
940         cdev_init(&ptmx_cdev, &ptmx_fops);
941         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
942             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
943                 panic("Couldn't register /dev/ptmx driver");
944         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
945 }
946
947 #else
948 static inline void unix98_pty_init(void) { }
949 #endif
950
951 static int __init pty_init(void)
952 {
953         legacy_pty_init();
954         unix98_pty_init();
955         return 0;
956 }
957 device_initcall(pty_init);