1/* 2 * Copyright (C) 1991, 1992 Linus Torvalds 3 * 4 * Added support for a Unix98-style ptmx device. 5 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 6 * 7 */ 8 9#include <linux/module.h> 10 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.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 29 30#ifdef CONFIG_UNIX98_PTYS 31static struct tty_driver *ptm_driver; 32static struct tty_driver *pts_driver; 33static DEFINE_MUTEX(devpts_mutex); 34#endif 35 36static void pty_close(struct tty_struct *tty, struct file *filp) 37{ 38 BUG_ON(!tty); 39 if (tty->driver->subtype == PTY_TYPE_MASTER) 40 WARN_ON(tty->count > 1); 41 else { 42 if (test_bit(TTY_IO_ERROR, &tty->flags)) 43 return; 44 if (tty->count > 2) 45 return; 46 } 47 set_bit(TTY_IO_ERROR, &tty->flags); 48 wake_up_interruptible(&tty->read_wait); 49 wake_up_interruptible(&tty->write_wait); 50 spin_lock_irq(&tty->ctrl_lock); 51 tty->packet = 0; 52 spin_unlock_irq(&tty->ctrl_lock); 53 /* Review - krefs on tty_link ?? */ 54 if (!tty->link) 55 return; 56 set_bit(TTY_OTHER_CLOSED, &tty->link->flags); 57 wake_up_interruptible(&tty->link->read_wait); 58 wake_up_interruptible(&tty->link->write_wait); 59 if (tty->driver->subtype == PTY_TYPE_MASTER) { 60 set_bit(TTY_OTHER_CLOSED, &tty->flags); 61#ifdef CONFIG_UNIX98_PTYS 62 if (tty->driver == ptm_driver) { 63 mutex_lock(&devpts_mutex); 64 if (tty->link->driver_data) 65 devpts_pty_kill(tty->link->driver_data); 66 mutex_unlock(&devpts_mutex); 67 } 68#endif 69 tty_vhangup(tty->link); 70 } 71} 72 73/* 74 * The unthrottle routine is called by the line discipline to signal 75 * that it can receive more characters. For PTY's, the TTY_THROTTLED 76 * flag is always set, to force the line discipline to always call the 77 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 78 * characters in the queue. This is necessary since each time this 79 * happens, we need to wake up any sleeping processes that could be 80 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() 81 * for the pty buffer to be drained. 82 */ 83static void pty_unthrottle(struct tty_struct *tty) 84{ 85 tty_wakeup(tty->link); 86 set_bit(TTY_THROTTLED, &tty->flags); 87} 88 89/** 90 * pty_write - write to a pty 91 * @tty: the tty we write from 92 * @buf: kernel buffer of data 93 * @count: bytes to write 94 * 95 * Our "hardware" write method. Data is coming from the ldisc which 96 * may be in a non sleeping state. We simply throw this at the other 97 * end of the link as if we were an IRQ handler receiving stuff for 98 * the other side of the pty/tty pair. 99 */ 100 101static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 102{ 103 struct tty_struct *to = tty->link; 104 105 if (tty->stopped) 106 return 0; 107 108 if (c > 0) { 109 /* Stuff the data into the input queue of the other end */ 110 c = tty_insert_flip_string(to->port, buf, c); 111 /* And shovel */ 112 if (c) 113 tty_flip_buffer_push(to->port); 114 } 115 return c; 116} 117 118/** 119 * pty_write_room - write space 120 * @tty: tty we are writing from 121 * 122 * Report how many bytes the ldisc can send into the queue for 123 * the other device. 124 */ 125 126static int pty_write_room(struct tty_struct *tty) 127{ 128 if (tty->stopped) 129 return 0; 130 return tty_buffer_space_avail(tty->link->port); 131} 132 133/** 134 * pty_chars_in_buffer - characters currently in our tx queue 135 * @tty: our tty 136 * 137 * Report how much we have in the transmit queue. As everything is 138 * instantly at the other end this is easy to implement. 139 */ 140 141static int pty_chars_in_buffer(struct tty_struct *tty) 142{ 143 return 0; 144} 145 146/* Set the lock flag on a pty */ 147static int pty_set_lock(struct tty_struct *tty, int __user *arg) 148{ 149 int val; 150 if (get_user(val, arg)) 151 return -EFAULT; 152 if (val) 153 set_bit(TTY_PTY_LOCK, &tty->flags); 154 else 155 clear_bit(TTY_PTY_LOCK, &tty->flags); 156 return 0; 157} 158 159static int pty_get_lock(struct tty_struct *tty, int __user *arg) 160{ 161 int locked = test_bit(TTY_PTY_LOCK, &tty->flags); 162 return put_user(locked, arg); 163} 164 165/* Set the packet mode on a pty */ 166static int pty_set_pktmode(struct tty_struct *tty, int __user *arg) 167{ 168 int pktmode; 169 170 if (get_user(pktmode, arg)) 171 return -EFAULT; 172 173 spin_lock_irq(&tty->ctrl_lock); 174 if (pktmode) { 175 if (!tty->packet) { 176 tty->link->ctrl_status = 0; 177 smp_mb(); 178 tty->packet = 1; 179 } 180 } else 181 tty->packet = 0; 182 spin_unlock_irq(&tty->ctrl_lock); 183 184 return 0; 185} 186 187/* Get the packet mode of a pty */ 188static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) 189{ 190 int pktmode = tty->packet; 191 return put_user(pktmode, arg); 192} 193 194/* Send a signal to the slave */ 195static int pty_signal(struct tty_struct *tty, int sig) 196{ 197 struct pid *pgrp; 198 199 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) 200 return -EINVAL; 201 202 if (tty->link) { 203 pgrp = tty_get_pgrp(tty->link); 204 if (pgrp) 205 kill_pgrp(pgrp, sig, 1); 206 put_pid(pgrp); 207 } 208 return 0; 209} 210 211static void pty_flush_buffer(struct tty_struct *tty) 212{ 213 struct tty_struct *to = tty->link; 214 struct tty_ldisc *ld; 215 216 if (!to) 217 return; 218 219 ld = tty_ldisc_ref(to); 220 tty_buffer_flush(to, ld); 221 if (ld) 222 tty_ldisc_deref(ld); 223 224 if (to->packet) { 225 spin_lock_irq(&tty->ctrl_lock); 226 tty->ctrl_status |= TIOCPKT_FLUSHWRITE; 227 wake_up_interruptible(&to->read_wait); 228 spin_unlock_irq(&tty->ctrl_lock); 229 } 230} 231 232static int pty_open(struct tty_struct *tty, struct file *filp) 233{ 234 if (!tty || !tty->link) 235 return -ENODEV; 236 237 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 238 goto out; 239 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 240 goto out; 241 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1) 242 goto out; 243 244 clear_bit(TTY_IO_ERROR, &tty->flags); 245 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 246 set_bit(TTY_THROTTLED, &tty->flags); 247 return 0; 248 249out: 250 set_bit(TTY_IO_ERROR, &tty->flags); 251 return -EIO; 252} 253 254static void pty_set_termios(struct tty_struct *tty, 255 struct ktermios *old_termios) 256{ 257 /* See if packet mode change of state. */ 258 if (tty->link && tty->link->packet) { 259 int extproc = (old_termios->c_lflag & EXTPROC) | 260 (tty->termios.c_lflag & EXTPROC); 261 int old_flow = ((old_termios->c_iflag & IXON) && 262 (old_termios->c_cc[VSTOP] == '\023') && 263 (old_termios->c_cc[VSTART] == '\021')); 264 int new_flow = (I_IXON(tty) && 265 STOP_CHAR(tty) == '\023' && 266 START_CHAR(tty) == '\021'); 267 if ((old_flow != new_flow) || extproc) { 268 spin_lock_irq(&tty->ctrl_lock); 269 if (old_flow != new_flow) { 270 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 271 if (new_flow) 272 tty->ctrl_status |= TIOCPKT_DOSTOP; 273 else 274 tty->ctrl_status |= TIOCPKT_NOSTOP; 275 } 276 if (extproc) 277 tty->ctrl_status |= TIOCPKT_IOCTL; 278 spin_unlock_irq(&tty->ctrl_lock); 279 wake_up_interruptible(&tty->link->read_wait); 280 } 281 } 282 283 tty->termios.c_cflag &= ~(CSIZE | PARENB); 284 tty->termios.c_cflag |= (CS8 | CREAD); 285} 286 287/** 288 * pty_do_resize - resize event 289 * @tty: tty being resized 290 * @ws: window size being set. 291 * 292 * Update the termios variables and send the necessary signals to 293 * peform a terminal resize correctly 294 */ 295 296static int pty_resize(struct tty_struct *tty, struct winsize *ws) 297{ 298 struct pid *pgrp, *rpgrp; 299 struct tty_struct *pty = tty->link; 300 301 /* For a PTY we need to lock the tty side */ 302 mutex_lock(&tty->winsize_mutex); 303 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 304 goto done; 305 306 /* Signal the foreground process group of both ptys */ 307 pgrp = tty_get_pgrp(tty); 308 rpgrp = tty_get_pgrp(pty); 309 310 if (pgrp) 311 kill_pgrp(pgrp, SIGWINCH, 1); 312 if (rpgrp != pgrp && rpgrp) 313 kill_pgrp(rpgrp, SIGWINCH, 1); 314 315 put_pid(pgrp); 316 put_pid(rpgrp); 317 318 tty->winsize = *ws; 319 pty->winsize = *ws; /* Never used so will go away soon */ 320done: 321 mutex_unlock(&tty->winsize_mutex); 322 return 0; 323} 324 325/** 326 * pty_start - start() handler 327 * pty_stop - stop() handler 328 * @tty: tty being flow-controlled 329 * 330 * Propagates the TIOCPKT status to the master pty. 331 * 332 * NB: only the master pty can be in packet mode so only the slave 333 * needs start()/stop() handlers 334 */ 335static void pty_start(struct tty_struct *tty) 336{ 337 unsigned long flags; 338 339 if (tty->link && tty->link->packet) { 340 spin_lock_irqsave(&tty->ctrl_lock, flags); 341 tty->ctrl_status &= ~TIOCPKT_STOP; 342 tty->ctrl_status |= TIOCPKT_START; 343 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 344 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 345 } 346} 347 348static void pty_stop(struct tty_struct *tty) 349{ 350 unsigned long flags; 351 352 if (tty->link && tty->link->packet) { 353 spin_lock_irqsave(&tty->ctrl_lock, flags); 354 tty->ctrl_status &= ~TIOCPKT_START; 355 tty->ctrl_status |= TIOCPKT_STOP; 356 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 357 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 358 } 359} 360 361/** 362 * pty_common_install - set up the pty pair 363 * @driver: the pty driver 364 * @tty: the tty being instantiated 365 * @legacy: true if this is BSD style 366 * 367 * Perform the initial set up for the tty/pty pair. Called from the 368 * tty layer when the port is first opened. 369 * 370 * Locking: the caller must hold the tty_mutex 371 */ 372static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 373 bool legacy) 374{ 375 struct tty_struct *o_tty; 376 struct tty_port *ports[2]; 377 int idx = tty->index; 378 int retval = -ENOMEM; 379 380 /* Opening the slave first has always returned -EIO */ 381 if (driver->subtype != PTY_TYPE_MASTER) 382 return -EIO; 383 384 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 385 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 386 if (!ports[0] || !ports[1]) 387 goto err; 388 if (!try_module_get(driver->other->owner)) { 389 /* This cannot in fact currently happen */ 390 goto err; 391 } 392 o_tty = alloc_tty_struct(driver->other, idx); 393 if (!o_tty) 394 goto err_put_module; 395 396 tty_set_lock_subclass(o_tty); 397 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 398 399 if (legacy) { 400 /* We always use new tty termios data so we can do this 401 the easy way .. */ 402 retval = tty_init_termios(tty); 403 if (retval) 404 goto err_deinit_tty; 405 406 retval = tty_init_termios(o_tty); 407 if (retval) 408 goto err_free_termios; 409 410 driver->other->ttys[idx] = o_tty; 411 driver->ttys[idx] = tty; 412 } else { 413 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 414 tty->termios = driver->init_termios; 415 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 416 o_tty->termios = driver->other->init_termios; 417 } 418 419 /* 420 * Everything allocated ... set up the o_tty structure. 421 */ 422 tty_driver_kref_get(driver->other); 423 /* Establish the links in both directions */ 424 tty->link = o_tty; 425 o_tty->link = tty; 426 tty_port_init(ports[0]); 427 tty_port_init(ports[1]); 428 tty_buffer_set_limit(ports[0], 8192); 429 tty_buffer_set_limit(ports[1], 8192); 430 o_tty->port = ports[0]; 431 tty->port = ports[1]; 432 o_tty->port->itty = o_tty; 433 434 tty_buffer_set_lock_subclass(o_tty->port); 435 436 tty_driver_kref_get(driver); 437 tty->count++; 438 o_tty->count++; 439 return 0; 440err_free_termios: 441 if (legacy) 442 tty_free_termios(tty); 443err_deinit_tty: 444 deinitialize_tty_struct(o_tty); 445 free_tty_struct(o_tty); 446err_put_module: 447 module_put(driver->other->owner); 448err: 449 kfree(ports[0]); 450 kfree(ports[1]); 451 return retval; 452} 453 454static void pty_cleanup(struct tty_struct *tty) 455{ 456 tty_port_put(tty->port); 457} 458 459/* Traditional BSD devices */ 460#ifdef CONFIG_LEGACY_PTYS 461 462static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 463{ 464 return pty_common_install(driver, tty, true); 465} 466 467static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 468{ 469 struct tty_struct *pair = tty->link; 470 driver->ttys[tty->index] = NULL; 471 if (pair) 472 pair->driver->ttys[pair->index] = NULL; 473} 474 475static int pty_bsd_ioctl(struct tty_struct *tty, 476 unsigned int cmd, unsigned long arg) 477{ 478 switch (cmd) { 479 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 480 return pty_set_lock(tty, (int __user *) arg); 481 case TIOCGPTLCK: /* Get PT Lock status */ 482 return pty_get_lock(tty, (int __user *)arg); 483 case TIOCPKT: /* Set PT packet mode */ 484 return pty_set_pktmode(tty, (int __user *)arg); 485 case TIOCGPKT: /* Get PT packet mode */ 486 return pty_get_pktmode(tty, (int __user *)arg); 487 case TIOCSIG: /* Send signal to other side of pty */ 488 return pty_signal(tty, (int) arg); 489 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 490 return -EINVAL; 491 } 492 return -ENOIOCTLCMD; 493} 494 495static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 496module_param(legacy_count, int, 0); 497 498/* 499 * The master side of a pty can do TIOCSPTLCK and thus 500 * has pty_bsd_ioctl. 501 */ 502static const struct tty_operations master_pty_ops_bsd = { 503 .install = pty_install, 504 .open = pty_open, 505 .close = pty_close, 506 .write = pty_write, 507 .write_room = pty_write_room, 508 .flush_buffer = pty_flush_buffer, 509 .chars_in_buffer = pty_chars_in_buffer, 510 .unthrottle = pty_unthrottle, 511 .ioctl = pty_bsd_ioctl, 512 .cleanup = pty_cleanup, 513 .resize = pty_resize, 514 .remove = pty_remove 515}; 516 517static const struct tty_operations slave_pty_ops_bsd = { 518 .install = pty_install, 519 .open = pty_open, 520 .close = pty_close, 521 .write = pty_write, 522 .write_room = pty_write_room, 523 .flush_buffer = pty_flush_buffer, 524 .chars_in_buffer = pty_chars_in_buffer, 525 .unthrottle = pty_unthrottle, 526 .set_termios = pty_set_termios, 527 .cleanup = pty_cleanup, 528 .resize = pty_resize, 529 .start = pty_start, 530 .stop = pty_stop, 531 .remove = pty_remove 532}; 533 534static void __init legacy_pty_init(void) 535{ 536 struct tty_driver *pty_driver, *pty_slave_driver; 537 538 if (legacy_count <= 0) 539 return; 540 541 pty_driver = tty_alloc_driver(legacy_count, 542 TTY_DRIVER_RESET_TERMIOS | 543 TTY_DRIVER_REAL_RAW | 544 TTY_DRIVER_DYNAMIC_ALLOC); 545 if (IS_ERR(pty_driver)) 546 panic("Couldn't allocate pty driver"); 547 548 pty_slave_driver = tty_alloc_driver(legacy_count, 549 TTY_DRIVER_RESET_TERMIOS | 550 TTY_DRIVER_REAL_RAW | 551 TTY_DRIVER_DYNAMIC_ALLOC); 552 if (IS_ERR(pty_slave_driver)) 553 panic("Couldn't allocate pty slave driver"); 554 555 pty_driver->driver_name = "pty_master"; 556 pty_driver->name = "pty"; 557 pty_driver->major = PTY_MASTER_MAJOR; 558 pty_driver->minor_start = 0; 559 pty_driver->type = TTY_DRIVER_TYPE_PTY; 560 pty_driver->subtype = PTY_TYPE_MASTER; 561 pty_driver->init_termios = tty_std_termios; 562 pty_driver->init_termios.c_iflag = 0; 563 pty_driver->init_termios.c_oflag = 0; 564 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 565 pty_driver->init_termios.c_lflag = 0; 566 pty_driver->init_termios.c_ispeed = 38400; 567 pty_driver->init_termios.c_ospeed = 38400; 568 pty_driver->other = pty_slave_driver; 569 tty_set_operations(pty_driver, &master_pty_ops_bsd); 570 571 pty_slave_driver->driver_name = "pty_slave"; 572 pty_slave_driver->name = "ttyp"; 573 pty_slave_driver->major = PTY_SLAVE_MAJOR; 574 pty_slave_driver->minor_start = 0; 575 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; 576 pty_slave_driver->subtype = PTY_TYPE_SLAVE; 577 pty_slave_driver->init_termios = tty_std_termios; 578 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 579 pty_slave_driver->init_termios.c_ispeed = 38400; 580 pty_slave_driver->init_termios.c_ospeed = 38400; 581 pty_slave_driver->other = pty_driver; 582 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd); 583 584 if (tty_register_driver(pty_driver)) 585 panic("Couldn't register pty driver"); 586 if (tty_register_driver(pty_slave_driver)) 587 panic("Couldn't register pty slave driver"); 588} 589#else 590static inline void legacy_pty_init(void) { } 591#endif 592 593/* Unix98 devices */ 594#ifdef CONFIG_UNIX98_PTYS 595 596static struct cdev ptmx_cdev; 597 598static int pty_unix98_ioctl(struct tty_struct *tty, 599 unsigned int cmd, unsigned long arg) 600{ 601 switch (cmd) { 602 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 603 return pty_set_lock(tty, (int __user *)arg); 604 case TIOCGPTLCK: /* Get PT Lock status */ 605 return pty_get_lock(tty, (int __user *)arg); 606 case TIOCPKT: /* Set PT packet mode */ 607 return pty_set_pktmode(tty, (int __user *)arg); 608 case TIOCGPKT: /* Get PT packet mode */ 609 return pty_get_pktmode(tty, (int __user *)arg); 610 case TIOCGPTN: /* Get PT Number */ 611 return put_user(tty->index, (unsigned int __user *)arg); 612 case TIOCSIG: /* Send signal to other side of pty */ 613 return pty_signal(tty, (int) arg); 614 } 615 616 return -ENOIOCTLCMD; 617} 618 619/** 620 * ptm_unix98_lookup - find a pty master 621 * @driver: ptm driver 622 * @idx: tty index 623 * 624 * Look up a pty master device. Called under the tty_mutex for now. 625 * This provides our locking. 626 */ 627 628static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, 629 struct inode *ptm_inode, int idx) 630{ 631 /* Master must be open via /dev/ptmx */ 632 return ERR_PTR(-EIO); 633} 634 635/** 636 * pts_unix98_lookup - find a pty slave 637 * @driver: pts driver 638 * @idx: tty index 639 * 640 * Look up a pty master device. Called under the tty_mutex for now. 641 * This provides our locking for the tty pointer. 642 */ 643 644static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, 645 struct inode *pts_inode, int idx) 646{ 647 struct tty_struct *tty; 648 649 mutex_lock(&devpts_mutex); 650 tty = devpts_get_priv(pts_inode); 651 mutex_unlock(&devpts_mutex); 652 /* Master must be open before slave */ 653 if (!tty) 654 return ERR_PTR(-EIO); 655 return tty; 656} 657 658/* We have no need to install and remove our tty objects as devpts does all 659 the work for us */ 660 661static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 662{ 663 return pty_common_install(driver, tty, false); 664} 665 666static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 667{ 668} 669 670/* this is called once with whichever end is closed last */ 671static void pty_unix98_shutdown(struct tty_struct *tty) 672{ 673 struct inode *ptmx_inode; 674 675 if (tty->driver->subtype == PTY_TYPE_MASTER) 676 ptmx_inode = tty->driver_data; 677 else 678 ptmx_inode = tty->link->driver_data; 679 devpts_kill_index(ptmx_inode, tty->index); 680 devpts_del_ref(ptmx_inode); 681} 682 683static const struct tty_operations ptm_unix98_ops = { 684 .lookup = ptm_unix98_lookup, 685 .install = pty_unix98_install, 686 .remove = pty_unix98_remove, 687 .open = pty_open, 688 .close = pty_close, 689 .write = pty_write, 690 .write_room = pty_write_room, 691 .flush_buffer = pty_flush_buffer, 692 .chars_in_buffer = pty_chars_in_buffer, 693 .unthrottle = pty_unthrottle, 694 .ioctl = pty_unix98_ioctl, 695 .resize = pty_resize, 696 .shutdown = pty_unix98_shutdown, 697 .cleanup = pty_cleanup 698}; 699 700static const struct tty_operations pty_unix98_ops = { 701 .lookup = pts_unix98_lookup, 702 .install = pty_unix98_install, 703 .remove = pty_unix98_remove, 704 .open = pty_open, 705 .close = pty_close, 706 .write = pty_write, 707 .write_room = pty_write_room, 708 .flush_buffer = pty_flush_buffer, 709 .chars_in_buffer = pty_chars_in_buffer, 710 .unthrottle = pty_unthrottle, 711 .set_termios = pty_set_termios, 712 .start = pty_start, 713 .stop = pty_stop, 714 .shutdown = pty_unix98_shutdown, 715 .cleanup = pty_cleanup, 716}; 717 718/** 719 * ptmx_open - open a unix 98 pty master 720 * @inode: inode of device file 721 * @filp: file pointer to tty 722 * 723 * Allocate a unix98 pty master device from the ptmx driver. 724 * 725 * Locking: tty_mutex protects the init_dev work. tty->count should 726 * protect the rest. 727 * allocated_ptys_lock handles the list of free pty numbers 728 */ 729 730static int ptmx_open(struct inode *inode, struct file *filp) 731{ 732 struct tty_struct *tty; 733 struct inode *slave_inode; 734 int retval; 735 int index; 736 737 nonseekable_open(inode, filp); 738 739 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 740 filp->f_mode |= FMODE_NONOTIFY; 741 742 retval = tty_alloc_file(filp); 743 if (retval) 744 return retval; 745 746 /* find a device that is not in use. */ 747 mutex_lock(&devpts_mutex); 748 index = devpts_new_index(inode); 749 if (index < 0) { 750 retval = index; 751 mutex_unlock(&devpts_mutex); 752 goto err_file; 753 } 754 755 mutex_unlock(&devpts_mutex); 756 757 mutex_lock(&tty_mutex); 758 tty = tty_init_dev(ptm_driver, index); 759 760 if (IS_ERR(tty)) { 761 retval = PTR_ERR(tty); 762 goto out; 763 } 764 765 /* The tty returned here is locked so we can safely 766 drop the mutex */ 767 mutex_unlock(&tty_mutex); 768 769 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 770 tty->driver_data = inode; 771 772 /* 773 * In the case where all references to ptmx inode are dropped and we 774 * still have /dev/tty opened pointing to the master/slave pair (ptmx 775 * is closed/released before /dev/tty), we must make sure that the inode 776 * is still valid when we call the final pty_unix98_shutdown, thus we 777 * hold an additional reference to the ptmx inode. For the same /dev/tty 778 * last close case, we also need to make sure the super_block isn't 779 * destroyed (devpts instance unmounted), before /dev/tty is closed and 780 * on its release devpts_kill_index is called. 781 */ 782 devpts_add_ref(inode); 783 784 tty_add_file(tty, filp); 785 786 slave_inode = devpts_pty_new(inode, 787 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index, 788 tty->link); 789 if (IS_ERR(slave_inode)) { 790 retval = PTR_ERR(slave_inode); 791 goto err_release; 792 } 793 tty->link->driver_data = slave_inode; 794 795 retval = ptm_driver->ops->open(tty, filp); 796 if (retval) 797 goto err_release; 798 799 tty_unlock(tty); 800 return 0; 801err_release: 802 tty_unlock(tty); 803 tty_release(inode, filp); 804 return retval; 805out: 806 mutex_unlock(&tty_mutex); 807 devpts_kill_index(inode, index); 808err_file: 809 tty_free_file(filp); 810 return retval; 811} 812 813static struct file_operations ptmx_fops; 814 815static void __init unix98_pty_init(void) 816{ 817 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 818 TTY_DRIVER_RESET_TERMIOS | 819 TTY_DRIVER_REAL_RAW | 820 TTY_DRIVER_DYNAMIC_DEV | 821 TTY_DRIVER_DEVPTS_MEM | 822 TTY_DRIVER_DYNAMIC_ALLOC); 823 if (IS_ERR(ptm_driver)) 824 panic("Couldn't allocate Unix98 ptm driver"); 825 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 826 TTY_DRIVER_RESET_TERMIOS | 827 TTY_DRIVER_REAL_RAW | 828 TTY_DRIVER_DYNAMIC_DEV | 829 TTY_DRIVER_DEVPTS_MEM | 830 TTY_DRIVER_DYNAMIC_ALLOC); 831 if (IS_ERR(pts_driver)) 832 panic("Couldn't allocate Unix98 pts driver"); 833 834 ptm_driver->driver_name = "pty_master"; 835 ptm_driver->name = "ptm"; 836 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 837 ptm_driver->minor_start = 0; 838 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 839 ptm_driver->subtype = PTY_TYPE_MASTER; 840 ptm_driver->init_termios = tty_std_termios; 841 ptm_driver->init_termios.c_iflag = 0; 842 ptm_driver->init_termios.c_oflag = 0; 843 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 844 ptm_driver->init_termios.c_lflag = 0; 845 ptm_driver->init_termios.c_ispeed = 38400; 846 ptm_driver->init_termios.c_ospeed = 38400; 847 ptm_driver->other = pts_driver; 848 tty_set_operations(ptm_driver, &ptm_unix98_ops); 849 850 pts_driver->driver_name = "pty_slave"; 851 pts_driver->name = "pts"; 852 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 853 pts_driver->minor_start = 0; 854 pts_driver->type = TTY_DRIVER_TYPE_PTY; 855 pts_driver->subtype = PTY_TYPE_SLAVE; 856 pts_driver->init_termios = tty_std_termios; 857 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 858 pts_driver->init_termios.c_ispeed = 38400; 859 pts_driver->init_termios.c_ospeed = 38400; 860 pts_driver->other = ptm_driver; 861 tty_set_operations(pts_driver, &pty_unix98_ops); 862 863 if (tty_register_driver(ptm_driver)) 864 panic("Couldn't register Unix98 ptm driver"); 865 if (tty_register_driver(pts_driver)) 866 panic("Couldn't register Unix98 pts driver"); 867 868 /* Now create the /dev/ptmx special device */ 869 tty_default_fops(&ptmx_fops); 870 ptmx_fops.open = ptmx_open; 871 872 cdev_init(&ptmx_cdev, &ptmx_fops); 873 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 874 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 875 panic("Couldn't register /dev/ptmx driver"); 876 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 877} 878 879#else 880static inline void unix98_pty_init(void) { } 881#endif 882 883static int __init pty_init(void) 884{ 885 legacy_pty_init(); 886 unix98_pty_init(); 887 return 0; 888} 889module_init(pty_init); 890