drivers/tty/tty_ioctl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   4  *
   5  * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
   6  * which can be dynamically activated and de-activated by the line
   7  * discipline handling modules (like SLIP).
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/termios.h>
  12 #include <linux/errno.h>
  13 #include <linux/sched/signal.h>
  14 #include <linux/kernel.h>
  15 #include <linux/major.h>
  16 #include <linux/tty.h>
  17 #include <linux/fcntl.h>
  18 #include <linux/string.h>
  19 #include <linux/mm.h>
  20 #include <linux/module.h>
  21 #include <linux/bitops.h>
  22 #include <linux/mutex.h>
  23 #include <linux/compat.h>
  24 #include "tty.h"
  25
  26 #include <asm/io.h>
  27 #include <linux/uaccess.h>
  28
  29 #undef TTY_DEBUG_WAIT_UNTIL_SENT
  30
  31 #ifdef TTY_DEBUG_WAIT_UNTIL_SENT
  32 # define tty_debug_wait_until_sent(tty, f, args...)    tty_debug(tty, f, ##args)
  33 #else
  34 # define tty_debug_wait_until_sent(tty, f, args...)    do {} while (0)
  35 #endif
  36
  37 #undef  DEBUG
  38
  39 /*
  40  * Internal flag options for termios setting behavior
  41  */
  42 #define TERMIOS_FLUSH   1
  43 #define TERMIOS_WAIT    2
  44 #define TERMIOS_TERMIO  4
  45 #define TERMIOS_OLD     8
  46
  47
  48 /**
  49  *      tty_chars_in_buffer     -       characters pending
  50  *      @tty: terminal
  51  *
  52  *      Return the number of bytes of data in the device private
  53  *      output queue. If no private method is supplied there is assumed
  54  *      to be no queue on the device.
  55  */
  56
  57 int tty_chars_in_buffer(struct tty_struct *tty)
  58 {
  59         if (tty->ops->chars_in_buffer)
  60                 return tty->ops->chars_in_buffer(tty);
  61         else
  62                 return 0;
  63 }
  64 EXPORT_SYMBOL(tty_chars_in_buffer);
  65
  66 /**
  67  *      tty_write_room          -       write queue space
  68  *      @tty: terminal
  69  *
  70  *      Return the number of bytes that can be queued to this device
  71  *      at the present time. The result should be treated as a guarantee
  72  *      and the driver cannot offer a value it later shrinks by more than
  73  *      the number of bytes written. If no method is provided 2K is always
  74  *      returned and data may be lost as there will be no flow control.
  75  */
  76
  77 int tty_write_room(struct tty_struct *tty)
  78 {
  79         if (tty->ops->write_room)
  80                 return tty->ops->write_room(tty);
  81         return 2048;
  82 }
  83 EXPORT_SYMBOL(tty_write_room);
  84
  85 /**
  86  *      tty_driver_flush_buffer -       discard internal buffer
  87  *      @tty: terminal
  88  *
  89  *      Discard the internal output buffer for this device. If no method
  90  *      is provided then either the buffer cannot be hardware flushed or
  91  *      there is no buffer driver side.
  92  */
  93 void tty_driver_flush_buffer(struct tty_struct *tty)
  94 {
  95         if (tty->ops->flush_buffer)
  96                 tty->ops->flush_buffer(tty);
  97 }
  98 EXPORT_SYMBOL(tty_driver_flush_buffer);
  99
 100 /**
 101  *      tty_throttle            -       flow control
 102  *      @tty: terminal
 103  *
 104  *      Indicate that a tty should stop transmitting data down the stack.
 105  *      Takes the termios rwsem to protect against parallel throttle/unthrottle
 106  *      and also to ensure the driver can consistently reference its own
 107  *      termios data at this point when implementing software flow control.
 108  */
 109
 110 void tty_throttle(struct tty_struct *tty)
 111 {
 112         down_write(&tty->termios_rwsem);
 113         /* check TTY_THROTTLED first so it indicates our state */
 114         if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
 115             tty->ops->throttle)
 116                 tty->ops->throttle(tty);
 117         tty->flow_change = 0;
 118         up_write(&tty->termios_rwsem);
 119 }
 120 EXPORT_SYMBOL(tty_throttle);
 121
 122 /**
 123  *      tty_unthrottle          -       flow control
 124  *      @tty: terminal
 125  *
 126  *      Indicate that a tty may continue transmitting data down the stack.
 127  *      Takes the termios rwsem to protect against parallel throttle/unthrottle
 128  *      and also to ensure the driver can consistently reference its own
 129  *      termios data at this point when implementing software flow control.
 130  *
 131  *      Drivers should however remember that the stack can issue a throttle,
 132  *      then change flow control method, then unthrottle.
 133  */
 134
 135 void tty_unthrottle(struct tty_struct *tty)
 136 {
 137         down_write(&tty->termios_rwsem);
 138         if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
 139             tty->ops->unthrottle)
 140                 tty->ops->unthrottle(tty);
 141         tty->flow_change = 0;
 142         up_write(&tty->termios_rwsem);
 143 }
 144 EXPORT_SYMBOL(tty_unthrottle);
 145
 146 /**
 147  *      tty_throttle_safe       -       flow control
 148  *      @tty: terminal
 149  *
 150  *      Similar to tty_throttle() but will only attempt throttle
 151  *      if tty->flow_change is TTY_THROTTLE_SAFE. Prevents an accidental
 152  *      throttle due to race conditions when throttling is conditional
 153  *      on factors evaluated prior to throttling.
 154  *
 155  *      Returns 0 if tty is throttled (or was already throttled)
 156  */
 157
 158 int tty_throttle_safe(struct tty_struct *tty)
 159 {
 160         int ret = 0;
 161
 162         mutex_lock(&tty->throttle_mutex);
 163         if (!tty_throttled(tty)) {
 164                 if (tty->flow_change != TTY_THROTTLE_SAFE)
 165                         ret = 1;
 166                 else {
 167                         set_bit(TTY_THROTTLED, &tty->flags);
 168                         if (tty->ops->throttle)
 169                                 tty->ops->throttle(tty);
 170                 }
 171         }
 172         mutex_unlock(&tty->throttle_mutex);
 173
 174         return ret;
 175 }
 176
 177 /**
 178  *      tty_unthrottle_safe     -       flow control
 179  *      @tty: terminal
 180  *
 181  *      Similar to tty_unthrottle() but will only attempt unthrottle
 182  *      if tty->flow_change is TTY_UNTHROTTLE_SAFE. Prevents an accidental
 183  *      unthrottle due to race conditions when unthrottling is conditional
 184  *      on factors evaluated prior to unthrottling.
 185  *
 186  *      Returns 0 if tty is unthrottled (or was already unthrottled)
 187  */
 188
 189 int tty_unthrottle_safe(struct tty_struct *tty)
 190 {
 191         int ret = 0;
 192
 193         mutex_lock(&tty->throttle_mutex);
 194         if (tty_throttled(tty)) {
 195                 if (tty->flow_change != TTY_UNTHROTTLE_SAFE)
 196                         ret = 1;
 197                 else {
 198                         clear_bit(TTY_THROTTLED, &tty->flags);
 199                         if (tty->ops->unthrottle)
 200                                 tty->ops->unthrottle(tty);
 201                 }
 202         }
 203         mutex_unlock(&tty->throttle_mutex);
 204
 205         return ret;
 206 }
 207
 208 /**
 209  *      tty_wait_until_sent     -       wait for I/O to finish
 210  *      @tty: tty we are waiting for
 211  *      @timeout: how long we will wait
 212  *
 213  *      Wait for characters pending in a tty driver to hit the wire, or
 214  *      for a timeout to occur (eg due to flow control)
 215  *
 216  *      Locking: none
 217  */
 218
 219 void tty_wait_until_sent(struct tty_struct *tty, long timeout)
 220 {
 221         tty_debug_wait_until_sent(tty, "wait until sent, timeout=%ld\n", timeout);
 222
 223         if (!timeout)
 224                 timeout = MAX_SCHEDULE_TIMEOUT;
 225
 226         timeout = wait_event_interruptible_timeout(tty->write_wait,
 227                         !tty_chars_in_buffer(tty), timeout);
 228         if (timeout <= 0)
 229                 return;
 230
 231         if (timeout == MAX_SCHEDULE_TIMEOUT)
 232                 timeout = 0;
 233
 234         if (tty->ops->wait_until_sent)
 235                 tty->ops->wait_until_sent(tty, timeout);
 236 }
 237 EXPORT_SYMBOL(tty_wait_until_sent);
 238
 239
 240 /*
 241  *              Termios Helper Methods
 242  */
 243
 244 static void unset_locked_termios(struct tty_struct *tty, struct ktermios *old)
 245 {
 246         struct ktermios *termios = &tty->termios;
 247         struct ktermios *locked  = &tty->termios_locked;
 248         int     i;
 249
 250 #define NOSET_MASK(x, y, z) (x = ((x) & ~(z)) | ((y) & (z)))
 251
 252         NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
 253         NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
 254         NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
 255         NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
 256         termios->c_line = locked->c_line ? old->c_line : termios->c_line;
 257         for (i = 0; i < NCCS; i++)
 258                 termios->c_cc[i] = locked->c_cc[i] ?
 259                         old->c_cc[i] : termios->c_cc[i];
 260         /* FIXME: What should we do for i/ospeed */
 261 }
 262
 263 /**
 264  *      tty_termios_copy_hw     -       copy hardware settings
 265  *      @new: New termios
 266  *      @old: Old termios
 267  *
 268  *      Propagate the hardware specific terminal setting bits from
 269  *      the old termios structure to the new one. This is used in cases
 270  *      where the hardware does not support reconfiguration or as a helper
 271  *      in some cases where only minimal reconfiguration is supported
 272  */
 273
 274 void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old)
 275 {
 276         /* The bits a dumb device handles in software. Smart devices need
 277            to always provide a set_termios method */
 278         new->c_cflag &= HUPCL | CREAD | CLOCAL;
 279         new->c_cflag |= old->c_cflag & ~(HUPCL | CREAD | CLOCAL);
 280         new->c_ispeed = old->c_ispeed;
 281         new->c_ospeed = old->c_ospeed;
 282 }
 283 EXPORT_SYMBOL(tty_termios_copy_hw);
 284
 285 /**
 286  *      tty_termios_hw_change   -       check for setting change
 287  *      @a: termios
 288  *      @b: termios to compare
 289  *
 290  *      Check if any of the bits that affect a dumb device have changed
 291  *      between the two termios structures, or a speed change is needed.
 292  */
 293
 294 int tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b)
 295 {
 296         if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
 297                 return 1;
 298         if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL))
 299                 return 1;
 300         return 0;
 301 }
 302 EXPORT_SYMBOL(tty_termios_hw_change);
 303
 304 /**
 305  *      tty_set_termios         -       update termios values
 306  *      @tty: tty to update
 307  *      @new_termios: desired new value
 308  *
 309  *      Perform updates to the termios values set on this terminal.
 310  *      A master pty's termios should never be set.
 311  *
 312  *      Locking: termios_rwsem
 313  */
 314
 315 int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
 316 {
 317         struct ktermios old_termios;
 318         struct tty_ldisc *ld;
 319
 320         WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
 321                 tty->driver->subtype == PTY_TYPE_MASTER);
 322         /*
 323          *      Perform the actual termios internal changes under lock.
 324          */
 325
 326
 327         /* FIXME: we need to decide on some locking/ordering semantics
 328            for the set_termios notification eventually */
 329         down_write(&tty->termios_rwsem);
 330         old_termios = tty->termios;
 331         tty->termios = *new_termios;
 332         unset_locked_termios(tty, &old_termios);
 333
 334         if (tty->ops->set_termios)
 335                 tty->ops->set_termios(tty, &old_termios);
 336         else
 337                 tty_termios_copy_hw(&tty->termios, &old_termios);
 338
 339         ld = tty_ldisc_ref(tty);
 340         if (ld != NULL) {
 341                 if (ld->ops->set_termios)
 342                         ld->ops->set_termios(tty, &old_termios);
 343                 tty_ldisc_deref(ld);
 344         }
 345         up_write(&tty->termios_rwsem);
 346         return 0;
 347 }
 348 EXPORT_SYMBOL_GPL(tty_set_termios);
 349
 350 /**
 351  *      set_termios             -       set termios values for a tty
 352  *      @tty: terminal device
 353  *      @arg: user data
 354  *      @opt: option information
 355  *
 356  *      Helper function to prepare termios data and run necessary other
 357  *      functions before using tty_set_termios to do the actual changes.
 358  *
 359  *      Locking:
 360  *              Called functions take ldisc and termios_rwsem locks
 361  */
 362
 363 static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
 364 {
 365         struct ktermios tmp_termios;
 366         struct tty_ldisc *ld;
 367         int retval = tty_check_change(tty);
 368
 369         if (retval)
 370                 return retval;
 371
 372         down_read(&tty->termios_rwsem);
 373         tmp_termios = tty->termios;
 374         up_read(&tty->termios_rwsem);
 375
 376         if (opt & TERMIOS_TERMIO) {
 377                 if (user_termio_to_kernel_termios(&tmp_termios,
 378                                                 (struct termio __user *)arg))
 379                         return -EFAULT;
 380 #ifdef TCGETS2
 381         } else if (opt & TERMIOS_OLD) {
 382                 if (user_termios_to_kernel_termios_1(&tmp_termios,
 383                                                 (struct termios __user *)arg))
 384                         return -EFAULT;
 385         } else {
 386                 if (user_termios_to_kernel_termios(&tmp_termios,
 387                                                 (struct termios2 __user *)arg))
 388                         return -EFAULT;
 389         }
 390 #else
 391         } else if (user_termios_to_kernel_termios(&tmp_termios,
 392                                         (struct termios __user *)arg))
 393                 return -EFAULT;
 394 #endif
 395
 396         /* If old style Bfoo values are used then load c_ispeed/c_ospeed
 397          * with the real speed so its unconditionally usable */
 398         tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
 399         tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);
 400
 401         if (opt & (TERMIOS_FLUSH|TERMIOS_WAIT)) {
 402 retry_write_wait:
 403                 retval = wait_event_interruptible(tty->write_wait, !tty_chars_in_buffer(tty));
 404                 if (retval < 0)
 405                         return retval;
 406
 407                 if (tty_write_lock(tty, false) < 0)
 408                         goto retry_write_wait;
 409
 410                 /* Racing writer? */
 411                 if (tty_chars_in_buffer(tty)) {
 412                         tty_write_unlock(tty);
 413                         goto retry_write_wait;
 414                 }
 415
 416                 ld = tty_ldisc_ref(tty);
 417                 if (ld != NULL) {
 418                         if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
 419                                 ld->ops->flush_buffer(tty);
 420                         tty_ldisc_deref(ld);
 421                 }
 422
 423                 if ((opt & TERMIOS_WAIT) && tty->ops->wait_until_sent) {
 424                         tty->ops->wait_until_sent(tty, 0);
 425                         if (signal_pending(current)) {
 426                                 tty_write_unlock(tty);
 427                                 return -ERESTARTSYS;
 428                         }
 429                 }
 430
 431                 tty_set_termios(tty, &tmp_termios);
 432
 433                 tty_write_unlock(tty);
 434         } else {
 435                 tty_set_termios(tty, &tmp_termios);
 436         }
 437
 438         /* FIXME: Arguably if tmp_termios == tty->termios AND the
 439            actual requested termios was not tmp_termios then we may
 440            want to return an error as no user requested change has
 441            succeeded */
 442         return 0;
 443 }
 444
 445 static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
 446 {
 447         down_read(&tty->termios_rwsem);
 448         *kterm = tty->termios;
 449         up_read(&tty->termios_rwsem);
 450 }
 451
 452 static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
 453 {
 454         down_read(&tty->termios_rwsem);
 455         *kterm = tty->termios_locked;
 456         up_read(&tty->termios_rwsem);
 457 }
 458
 459 static int get_termio(struct tty_struct *tty, struct termio __user *termio)
 460 {
 461         struct ktermios kterm;
 462         copy_termios(tty, &kterm);
 463         if (kernel_termios_to_user_termio(termio, &kterm))
 464                 return -EFAULT;
 465         return 0;
 466 }
 467
 468 #ifdef TIOCGETP
 469 /*
 470  * These are deprecated, but there is limited support..
 471  *
 472  * The "sg_flags" translation is a joke..
 473  */
 474 static int get_sgflags(struct tty_struct *tty)
 475 {
 476         int flags = 0;
 477
 478         if (!L_ICANON(tty)) {
 479                 if (L_ISIG(tty))
 480                         flags |= 0x02;          /* cbreak */
 481                 else
 482                         flags |= 0x20;          /* raw */
 483         }
 484         if (L_ECHO(tty))
 485                 flags |= 0x08;                  /* echo */
 486         if (O_OPOST(tty))
 487                 if (O_ONLCR(tty))
 488                         flags |= 0x10;          /* crmod */
 489         return flags;
 490 }
 491
 492 static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
 493 {
 494         struct sgttyb tmp;
 495
 496         down_read(&tty->termios_rwsem);
 497         tmp.sg_ispeed = tty->termios.c_ispeed;
 498         tmp.sg_ospeed = tty->termios.c_ospeed;
 499         tmp.sg_erase = tty->termios.c_cc[VERASE];
 500         tmp.sg_kill = tty->termios.c_cc[VKILL];
 501         tmp.sg_flags = get_sgflags(tty);
 502         up_read(&tty->termios_rwsem);
 503
 504         return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 505 }
 506
 507 static void set_sgflags(struct ktermios *termios, int flags)
 508 {
 509         termios->c_iflag = ICRNL | IXON;
 510         termios->c_oflag = 0;
 511         termios->c_lflag = ISIG | ICANON;
 512         if (flags & 0x02) {     /* cbreak */
 513                 termios->c_iflag = 0;
 514                 termios->c_lflag &= ~ICANON;
 515         }
 516         if (flags & 0x08) {             /* echo */
 517                 termios->c_lflag |= ECHO | ECHOE | ECHOK |
 518                                     ECHOCTL | ECHOKE | IEXTEN;
 519         }
 520         if (flags & 0x10) {             /* crmod */
 521                 termios->c_oflag |= OPOST | ONLCR;
 522         }
 523         if (flags & 0x20) {     /* raw */
 524                 termios->c_iflag = 0;
 525                 termios->c_lflag &= ~(ISIG | ICANON);
 526         }
 527         if (!(termios->c_lflag & ICANON)) {
 528                 termios->c_cc[VMIN] = 1;
 529                 termios->c_cc[VTIME] = 0;
 530         }
 531 }
 532
 533 /**
 534  *      set_sgttyb              -       set legacy terminal values
 535  *      @tty: tty structure
 536  *      @sgttyb: pointer to old style terminal structure
 537  *
 538  *      Updates a terminal from the legacy BSD style terminal information
 539  *      structure.
 540  *
 541  *      Locking: termios_rwsem
 542  */
 543
 544 static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
 545 {
 546         int retval;
 547         struct sgttyb tmp;
 548         struct ktermios termios;
 549
 550         retval = tty_check_change(tty);
 551         if (retval)
 552                 return retval;
 553
 554         if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
 555                 return -EFAULT;
 556
 557         down_write(&tty->termios_rwsem);
 558         termios = tty->termios;
 559         termios.c_cc[VERASE] = tmp.sg_erase;
 560         termios.c_cc[VKILL] = tmp.sg_kill;
 561         set_sgflags(&termios, tmp.sg_flags);
 562         /* Try and encode into Bfoo format */
 563 #ifdef BOTHER
 564         tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
 565                                                 termios.c_ospeed);
 566 #endif
 567         up_write(&tty->termios_rwsem);
 568         tty_set_termios(tty, &termios);
 569         return 0;
 570 }
 571 #endif
 572
 573 #ifdef TIOCGETC
 574 static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 575 {
 576         struct tchars tmp;
 577
 578         down_read(&tty->termios_rwsem);
 579         tmp.t_intrc = tty->termios.c_cc[VINTR];
 580         tmp.t_quitc = tty->termios.c_cc[VQUIT];
 581         tmp.t_startc = tty->termios.c_cc[VSTART];
 582         tmp.t_stopc = tty->termios.c_cc[VSTOP];
 583         tmp.t_eofc = tty->termios.c_cc[VEOF];
 584         tmp.t_brkc = tty->termios.c_cc[VEOL2];  /* what is brkc anyway? */
 585         up_read(&tty->termios_rwsem);
 586         return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 587 }
 588
 589 static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)
 590 {
 591         struct tchars tmp;
 592
 593         if (copy_from_user(&tmp, tchars, sizeof(tmp)))
 594                 return -EFAULT;
 595         down_write(&tty->termios_rwsem);
 596         tty->termios.c_cc[VINTR] = tmp.t_intrc;
 597         tty->termios.c_cc[VQUIT] = tmp.t_quitc;
 598         tty->termios.c_cc[VSTART] = tmp.t_startc;
 599         tty->termios.c_cc[VSTOP] = tmp.t_stopc;
 600         tty->termios.c_cc[VEOF] = tmp.t_eofc;
 601         tty->termios.c_cc[VEOL2] = tmp.t_brkc;  /* what is brkc anyway? */
 602         up_write(&tty->termios_rwsem);
 603         return 0;
 604 }
 605 #endif
 606
 607 #ifdef TIOCGLTC
 608 static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 609 {
 610         struct ltchars tmp;
 611
 612         down_read(&tty->termios_rwsem);
 613         tmp.t_suspc = tty->termios.c_cc[VSUSP];
 614         /* what is dsuspc anyway? */
 615         tmp.t_dsuspc = tty->termios.c_cc[VSUSP];
 616         tmp.t_rprntc = tty->termios.c_cc[VREPRINT];
 617         /* what is flushc anyway? */
 618         tmp.t_flushc = tty->termios.c_cc[VEOL2];
 619         tmp.t_werasc = tty->termios.c_cc[VWERASE];
 620         tmp.t_lnextc = tty->termios.c_cc[VLNEXT];
 621         up_read(&tty->termios_rwsem);
 622         return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 623 }
 624
 625 static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)
 626 {
 627         struct ltchars tmp;
 628
 629         if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
 630                 return -EFAULT;
 631
 632         down_write(&tty->termios_rwsem);
 633         tty->termios.c_cc[VSUSP] = tmp.t_suspc;
 634         /* what is dsuspc anyway? */
 635         tty->termios.c_cc[VEOL2] = tmp.t_dsuspc;
 636         tty->termios.c_cc[VREPRINT] = tmp.t_rprntc;
 637         /* what is flushc anyway? */
 638         tty->termios.c_cc[VEOL2] = tmp.t_flushc;
 639         tty->termios.c_cc[VWERASE] = tmp.t_werasc;
 640         tty->termios.c_cc[VLNEXT] = tmp.t_lnextc;
 641         up_write(&tty->termios_rwsem);
 642         return 0;
 643 }
 644 #endif
 645
 646 /**
 647  *      tty_change_softcar      -       carrier change ioctl helper
 648  *      @tty: tty to update
 649  *      @arg: enable/disable CLOCAL
 650  *
 651  *      Perform a change to the CLOCAL state and call into the driver
 652  *      layer to make it visible. All done with the termios rwsem
 653  */
 654
 655 static int tty_change_softcar(struct tty_struct *tty, int arg)
 656 {
 657         int ret = 0;
 658         int bit = arg ? CLOCAL : 0;
 659         struct ktermios old;
 660
 661         down_write(&tty->termios_rwsem);
 662         old = tty->termios;
 663         tty->termios.c_cflag &= ~CLOCAL;
 664         tty->termios.c_cflag |= bit;
 665         if (tty->ops->set_termios)
 666                 tty->ops->set_termios(tty, &old);
 667         if (C_CLOCAL(tty) != bit)
 668                 ret = -EINVAL;
 669         up_write(&tty->termios_rwsem);
 670         return ret;
 671 }
 672
 673 /**
 674  *      tty_mode_ioctl          -       mode related ioctls
 675  *      @tty: tty for the ioctl
 676  *      @file: file pointer for the tty
 677  *      @cmd: command
 678  *      @arg: ioctl argument
 679  *
 680  *      Perform non line discipline specific mode control ioctls. This
 681  *      is designed to be called by line disciplines to ensure they provide
 682  *      consistent mode setting.
 683  */
 684
 685 int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
 686                         unsigned int cmd, unsigned long arg)
 687 {
 688         struct tty_struct *real_tty;
 689         void __user *p = (void __user *)arg;
 690         int ret = 0;
 691         struct ktermios kterm;
 692
 693         BUG_ON(file == NULL);
 694
 695         if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
 696             tty->driver->subtype == PTY_TYPE_MASTER)
 697                 real_tty = tty->link;
 698         else
 699                 real_tty = tty;
 700
 701         switch (cmd) {
 702 #ifdef TIOCGETP
 703         case TIOCGETP:
 704                 return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
 705         case TIOCSETP:
 706         case TIOCSETN:
 707                 return set_sgttyb(real_tty, (struct sgttyb __user *) arg);
 708 #endif
 709 #ifdef TIOCGETC
 710         case TIOCGETC:
 711                 return get_tchars(real_tty, p);
 712         case TIOCSETC:
 713                 return set_tchars(real_tty, p);
 714 #endif
 715 #ifdef TIOCGLTC
 716         case TIOCGLTC:
 717                 return get_ltchars(real_tty, p);
 718         case TIOCSLTC:
 719                 return set_ltchars(real_tty, p);
 720 #endif
 721         case TCSETSF:
 722                 return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_OLD);
 723         case TCSETSW:
 724                 return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_OLD);
 725         case TCSETS:
 726                 return set_termios(real_tty, p, TERMIOS_OLD);
 727 #ifndef TCGETS2
 728         case TCGETS:
 729                 copy_termios(real_tty, &kterm);
 730                 if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
 731                         ret = -EFAULT;
 732                 return ret;
 733 #else
 734         case TCGETS:
 735                 copy_termios(real_tty, &kterm);
 736                 if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
 737                         ret = -EFAULT;
 738                 return ret;
 739         case TCGETS2:
 740                 copy_termios(real_tty, &kterm);
 741                 if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))
 742                         ret = -EFAULT;
 743                 return ret;
 744         case TCSETSF2:
 745                 return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT);
 746         case TCSETSW2:
 747                 return set_termios(real_tty, p, TERMIOS_WAIT);
 748         case TCSETS2:
 749                 return set_termios(real_tty, p, 0);
 750 #endif
 751         case TCGETA:
 752                 return get_termio(real_tty, p);
 753         case TCSETAF:
 754                 return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
 755         case TCSETAW:
 756                 return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
 757         case TCSETA:
 758                 return set_termios(real_tty, p, TERMIOS_TERMIO);
 759 #ifndef TCGETS2
 760         case TIOCGLCKTRMIOS:
 761                 copy_termios_locked(real_tty, &kterm);
 762                 if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))
 763                         ret = -EFAULT;
 764                 return ret;
 765         case TIOCSLCKTRMIOS:
 766                 if (!checkpoint_restore_ns_capable(&init_user_ns))
 767                         return -EPERM;
 768                 copy_termios_locked(real_tty, &kterm);
 769                 if (user_termios_to_kernel_termios(&kterm,
 770                                                (struct termios __user *) arg))
 771                         return -EFAULT;
 772                 down_write(&real_tty->termios_rwsem);
 773                 real_tty->termios_locked = kterm;
 774                 up_write(&real_tty->termios_rwsem);
 775                 return 0;
 776 #else
 777         case TIOCGLCKTRMIOS:
 778                 copy_termios_locked(real_tty, &kterm);
 779                 if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))
 780                         ret = -EFAULT;
 781                 return ret;
 782         case TIOCSLCKTRMIOS:
 783                 if (!checkpoint_restore_ns_capable(&init_user_ns))
 784                         return -EPERM;
 785                 copy_termios_locked(real_tty, &kterm);
 786                 if (user_termios_to_kernel_termios_1(&kterm,
 787                                                (struct termios __user *) arg))
 788                         return -EFAULT;
 789                 down_write(&real_tty->termios_rwsem);
 790                 real_tty->termios_locked = kterm;
 791                 up_write(&real_tty->termios_rwsem);
 792                 return ret;
 793 #endif
 794 #ifdef TCGETX
 795         case TCGETX:
 796         case TCSETX:
 797         case TCSETXW:
 798         case TCSETXF:
 799                 return -ENOTTY;
 800 #endif
 801         case TIOCGSOFTCAR:
 802                 copy_termios(real_tty, &kterm);
 803                 ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,
 804                                                 (int __user *)arg);
 805                 return ret;
 806         case TIOCSSOFTCAR:
 807                 if (get_user(arg, (unsigned int __user *) arg))
 808                         return -EFAULT;
 809                 return tty_change_softcar(real_tty, arg);
 810         default:
 811                 return -ENOIOCTLCMD;
 812         }
 813 }
 814 EXPORT_SYMBOL_GPL(tty_mode_ioctl);
 815
 816
 817 /* Caller guarantees ldisc reference is held */
 818 static int __tty_perform_flush(struct tty_struct *tty, unsigned long arg)
 819 {
 820         struct tty_ldisc *ld = tty->ldisc;
 821
 822         switch (arg) {
 823         case TCIFLUSH:
 824                 if (ld && ld->ops->flush_buffer) {
 825                         ld->ops->flush_buffer(tty);
 826                         tty_unthrottle(tty);
 827                 }
 828                 break;
 829         case TCIOFLUSH:
 830                 if (ld && ld->ops->flush_buffer) {
 831                         ld->ops->flush_buffer(tty);
 832                         tty_unthrottle(tty);
 833                 }
 834                 fallthrough;
 835         case TCOFLUSH:
 836                 tty_driver_flush_buffer(tty);
 837                 break;
 838         default:
 839                 return -EINVAL;
 840         }
 841         return 0;
 842 }
 843
 844 int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
 845 {
 846         struct tty_ldisc *ld;
 847         int retval = tty_check_change(tty);
 848         if (retval)
 849                 return retval;
 850
 851         ld = tty_ldisc_ref_wait(tty);
 852         retval = __tty_perform_flush(tty, arg);
 853         if (ld)
 854                 tty_ldisc_deref(ld);
 855         return retval;
 856 }
 857 EXPORT_SYMBOL_GPL(tty_perform_flush);
 858
 859 int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
 860                        unsigned int cmd, unsigned long arg)
 861 {
 862         int retval;
 863
 864         switch (cmd) {
 865         case TCXONC:
 866                 retval = tty_check_change(tty);
 867                 if (retval)
 868                         return retval;
 869                 switch (arg) {
 870                 case TCOOFF:
 871                         spin_lock_irq(&tty->flow_lock);
 872                         if (!tty->flow_stopped) {
 873                                 tty->flow_stopped = 1;
 874                                 __stop_tty(tty);
 875                         }
 876                         spin_unlock_irq(&tty->flow_lock);
 877                         break;
 878                 case TCOON:
 879                         spin_lock_irq(&tty->flow_lock);
 880                         if (tty->flow_stopped) {
 881                                 tty->flow_stopped = 0;
 882                                 __start_tty(tty);
 883                         }
 884                         spin_unlock_irq(&tty->flow_lock);
 885                         break;
 886                 case TCIOFF:
 887                         if (STOP_CHAR(tty) != __DISABLED_CHAR)
 888                                 retval = tty_send_xchar(tty, STOP_CHAR(tty));
 889                         break;
 890                 case TCION:
 891                         if (START_CHAR(tty) != __DISABLED_CHAR)
 892                                 retval = tty_send_xchar(tty, START_CHAR(tty));
 893                         break;
 894                 default:
 895                         return -EINVAL;
 896                 }
 897                 return retval;
 898         case TCFLSH:
 899                 retval = tty_check_change(tty);
 900                 if (retval)
 901                         return retval;
 902                 return __tty_perform_flush(tty, arg);
 903         default:
 904                 /* Try the mode commands */
 905                 return tty_mode_ioctl(tty, file, cmd, arg);
 906         }
 907 }
 908 EXPORT_SYMBOL(n_tty_ioctl_helper);