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