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 #include <linux/errno.h> 11 #include <linux/interrupt.h> 12 #include <linux/tty.h> 13 #include <linux/tty_flip.h> 14 #include <linux/fcntl.h> 15 #include <linux/sched.h> 16 #include <linux/string.h> 17 #include <linux/major.h> 18 #include <linux/mm.h> 19 #include <linux/init.h> 20 #include <linux/device.h> 21 #include <linux/uaccess.h> 22 #include <linux/bitops.h> 23 #include <linux/devpts_fs.h> 24 #include <linux/slab.h> 25 #include <linux/mutex.h> 26 #include <linux/poll.h> 27 28 #undef TTY_DEBUG_HANGUP 29 #ifdef TTY_DEBUG_HANGUP 30 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args) 31 #else 32 # define tty_debug_hangup(tty, f, args...) do {} while (0) 33 #endif 34 35 #ifdef CONFIG_UNIX98_PTYS 36 static struct tty_driver *ptm_driver; 37 static struct tty_driver *pts_driver; 38 static DEFINE_MUTEX(devpts_mutex); 39 #endif 40 41 static void pty_close(struct tty_struct *tty, struct file *filp) 42 { 43 BUG_ON(!tty); 44 if (tty->driver->subtype == PTY_TYPE_MASTER) 45 WARN_ON(tty->count > 1); 46 else { 47 if (test_bit(TTY_IO_ERROR, &tty->flags)) 48 return; 49 if (tty->count > 2) 50 return; 51 } 52 set_bit(TTY_IO_ERROR, &tty->flags); 53 wake_up_interruptible(&tty->read_wait); 54 wake_up_interruptible(&tty->write_wait); 55 spin_lock_irq(&tty->ctrl_lock); 56 tty->packet = 0; 57 spin_unlock_irq(&tty->ctrl_lock); 58 /* Review - krefs on tty_link ?? */ 59 if (!tty->link) 60 return; 61 set_bit(TTY_OTHER_CLOSED, &tty->link->flags); 62 tty_flip_buffer_push(tty->link->port); 63 wake_up_interruptible(&tty->link->write_wait); 64 if (tty->driver->subtype == PTY_TYPE_MASTER) { 65 set_bit(TTY_OTHER_CLOSED, &tty->flags); 66 #ifdef CONFIG_UNIX98_PTYS 67 if (tty->driver == ptm_driver) { 68 mutex_lock(&devpts_mutex); 69 if (tty->link->driver_data) 70 devpts_pty_kill(tty->link->driver_data); 71 mutex_unlock(&devpts_mutex); 72 } 73 #endif 74 tty_vhangup(tty->link); 75 } 76 } 77 78 /* 79 * The unthrottle routine is called by the line discipline to signal 80 * that it can receive more characters. For PTY's, the TTY_THROTTLED 81 * flag is always set, to force the line discipline to always call the 82 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 83 * characters in the queue. This is necessary since each time this 84 * happens, we need to wake up any sleeping processes that could be 85 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() 86 * for the pty buffer to be drained. 87 */ 88 static void pty_unthrottle(struct tty_struct *tty) 89 { 90 tty_wakeup(tty->link); 91 set_bit(TTY_THROTTLED, &tty->flags); 92 } 93 94 /** 95 * pty_write - write to a pty 96 * @tty: the tty we write from 97 * @buf: kernel buffer of data 98 * @count: bytes to write 99 * 100 * Our "hardware" write method. Data is coming from the ldisc which 101 * may be in a non sleeping state. We simply throw this at the other 102 * end of the link as if we were an IRQ handler receiving stuff for 103 * the other side of the pty/tty pair. 104 */ 105 106 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 107 { 108 struct tty_struct *to = tty->link; 109 110 if (tty->stopped) 111 return 0; 112 113 if (c > 0) { 114 /* Stuff the data into the input queue of the other end */ 115 c = tty_insert_flip_string(to->port, buf, c); 116 /* And shovel */ 117 if (c) 118 tty_flip_buffer_push(to->port); 119 } 120 return c; 121 } 122 123 /** 124 * pty_write_room - write space 125 * @tty: tty we are writing from 126 * 127 * Report how many bytes the ldisc can send into the queue for 128 * the other device. 129 */ 130 131 static int pty_write_room(struct tty_struct *tty) 132 { 133 if (tty->stopped) 134 return 0; 135 return tty_buffer_space_avail(tty->link->port); 136 } 137 138 /** 139 * pty_chars_in_buffer - characters currently in our tx queue 140 * @tty: our tty 141 * 142 * Report how much we have in the transmit queue. As everything is 143 * instantly at the other end this is easy to implement. 144 */ 145 146 static int pty_chars_in_buffer(struct tty_struct *tty) 147 { 148 return 0; 149 } 150 151 /* Set the lock flag on a pty */ 152 static int pty_set_lock(struct tty_struct *tty, int __user *arg) 153 { 154 int val; 155 if (get_user(val, arg)) 156 return -EFAULT; 157 if (val) 158 set_bit(TTY_PTY_LOCK, &tty->flags); 159 else 160 clear_bit(TTY_PTY_LOCK, &tty->flags); 161 return 0; 162 } 163 164 static int pty_get_lock(struct tty_struct *tty, int __user *arg) 165 { 166 int locked = test_bit(TTY_PTY_LOCK, &tty->flags); 167 return put_user(locked, arg); 168 } 169 170 /* Set the packet mode on a pty */ 171 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg) 172 { 173 int pktmode; 174 175 if (get_user(pktmode, arg)) 176 return -EFAULT; 177 178 spin_lock_irq(&tty->ctrl_lock); 179 if (pktmode) { 180 if (!tty->packet) { 181 tty->link->ctrl_status = 0; 182 smp_mb(); 183 tty->packet = 1; 184 } 185 } else 186 tty->packet = 0; 187 spin_unlock_irq(&tty->ctrl_lock); 188 189 return 0; 190 } 191 192 /* Get the packet mode of a pty */ 193 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) 194 { 195 int pktmode = tty->packet; 196 return put_user(pktmode, arg); 197 } 198 199 /* Send a signal to the slave */ 200 static int pty_signal(struct tty_struct *tty, int sig) 201 { 202 struct pid *pgrp; 203 204 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) 205 return -EINVAL; 206 207 if (tty->link) { 208 pgrp = tty_get_pgrp(tty->link); 209 if (pgrp) 210 kill_pgrp(pgrp, sig, 1); 211 put_pid(pgrp); 212 } 213 return 0; 214 } 215 216 static void pty_flush_buffer(struct tty_struct *tty) 217 { 218 struct tty_struct *to = tty->link; 219 struct tty_ldisc *ld; 220 221 if (!to) 222 return; 223 224 ld = tty_ldisc_ref(to); 225 tty_buffer_flush(to, ld); 226 if (ld) 227 tty_ldisc_deref(ld); 228 229 if (to->packet) { 230 spin_lock_irq(&tty->ctrl_lock); 231 tty->ctrl_status |= TIOCPKT_FLUSHWRITE; 232 wake_up_interruptible(&to->read_wait); 233 spin_unlock_irq(&tty->ctrl_lock); 234 } 235 } 236 237 static int pty_open(struct tty_struct *tty, struct file *filp) 238 { 239 if (!tty || !tty->link) 240 return -ENODEV; 241 242 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 243 goto out; 244 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 245 goto out; 246 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1) 247 goto out; 248 249 clear_bit(TTY_IO_ERROR, &tty->flags); 250 /* TTY_OTHER_CLOSED must be cleared before TTY_OTHER_DONE */ 251 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 252 clear_bit(TTY_OTHER_DONE, &tty->link->flags); 253 set_bit(TTY_THROTTLED, &tty->flags); 254 return 0; 255 256 out: 257 set_bit(TTY_IO_ERROR, &tty->flags); 258 return -EIO; 259 } 260 261 static void pty_set_termios(struct tty_struct *tty, 262 struct ktermios *old_termios) 263 { 264 /* See if packet mode change of state. */ 265 if (tty->link && tty->link->packet) { 266 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty); 267 int old_flow = ((old_termios->c_iflag & IXON) && 268 (old_termios->c_cc[VSTOP] == '\023') && 269 (old_termios->c_cc[VSTART] == '\021')); 270 int new_flow = (I_IXON(tty) && 271 STOP_CHAR(tty) == '\023' && 272 START_CHAR(tty) == '\021'); 273 if ((old_flow != new_flow) || extproc) { 274 spin_lock_irq(&tty->ctrl_lock); 275 if (old_flow != new_flow) { 276 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 277 if (new_flow) 278 tty->ctrl_status |= TIOCPKT_DOSTOP; 279 else 280 tty->ctrl_status |= TIOCPKT_NOSTOP; 281 } 282 if (extproc) 283 tty->ctrl_status |= TIOCPKT_IOCTL; 284 spin_unlock_irq(&tty->ctrl_lock); 285 wake_up_interruptible(&tty->link->read_wait); 286 } 287 } 288 289 tty->termios.c_cflag &= ~(CSIZE | PARENB); 290 tty->termios.c_cflag |= (CS8 | CREAD); 291 } 292 293 /** 294 * pty_do_resize - resize event 295 * @tty: tty being resized 296 * @ws: window size being set. 297 * 298 * Update the termios variables and send the necessary signals to 299 * peform a terminal resize correctly 300 */ 301 302 static int pty_resize(struct tty_struct *tty, struct winsize *ws) 303 { 304 struct pid *pgrp, *rpgrp; 305 struct tty_struct *pty = tty->link; 306 307 /* For a PTY we need to lock the tty side */ 308 mutex_lock(&tty->winsize_mutex); 309 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 310 goto done; 311 312 /* Signal the foreground process group of both ptys */ 313 pgrp = tty_get_pgrp(tty); 314 rpgrp = tty_get_pgrp(pty); 315 316 if (pgrp) 317 kill_pgrp(pgrp, SIGWINCH, 1); 318 if (rpgrp != pgrp && rpgrp) 319 kill_pgrp(rpgrp, SIGWINCH, 1); 320 321 put_pid(pgrp); 322 put_pid(rpgrp); 323 324 tty->winsize = *ws; 325 pty->winsize = *ws; /* Never used so will go away soon */ 326 done: 327 mutex_unlock(&tty->winsize_mutex); 328 return 0; 329 } 330 331 /** 332 * pty_start - start() handler 333 * pty_stop - stop() handler 334 * @tty: tty being flow-controlled 335 * 336 * Propagates the TIOCPKT status to the master pty. 337 * 338 * NB: only the master pty can be in packet mode so only the slave 339 * needs start()/stop() handlers 340 */ 341 static void pty_start(struct tty_struct *tty) 342 { 343 unsigned long flags; 344 345 if (tty->link && tty->link->packet) { 346 spin_lock_irqsave(&tty->ctrl_lock, flags); 347 tty->ctrl_status &= ~TIOCPKT_STOP; 348 tty->ctrl_status |= TIOCPKT_START; 349 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 350 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 351 } 352 } 353 354 static void pty_stop(struct tty_struct *tty) 355 { 356 unsigned long flags; 357 358 if (tty->link && tty->link->packet) { 359 spin_lock_irqsave(&tty->ctrl_lock, flags); 360 tty->ctrl_status &= ~TIOCPKT_START; 361 tty->ctrl_status |= TIOCPKT_STOP; 362 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 363 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 364 } 365 } 366 367 /** 368 * pty_common_install - set up the pty pair 369 * @driver: the pty driver 370 * @tty: the tty being instantiated 371 * @legacy: true if this is BSD style 372 * 373 * Perform the initial set up for the tty/pty pair. Called from the 374 * tty layer when the port is first opened. 375 * 376 * Locking: the caller must hold the tty_mutex 377 */ 378 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 379 bool legacy) 380 { 381 struct tty_struct *o_tty; 382 struct tty_port *ports[2]; 383 int idx = tty->index; 384 int retval = -ENOMEM; 385 386 /* Opening the slave first has always returned -EIO */ 387 if (driver->subtype != PTY_TYPE_MASTER) 388 return -EIO; 389 390 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 391 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 392 if (!ports[0] || !ports[1]) 393 goto err; 394 if (!try_module_get(driver->other->owner)) { 395 /* This cannot in fact currently happen */ 396 goto err; 397 } 398 o_tty = alloc_tty_struct(driver->other, idx); 399 if (!o_tty) 400 goto err_put_module; 401 402 tty_set_lock_subclass(o_tty); 403 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 404 405 if (legacy) { 406 /* We always use new tty termios data so we can do this 407 the easy way .. */ 408 tty_init_termios(tty); 409 tty_init_termios(o_tty); 410 411 driver->other->ttys[idx] = o_tty; 412 driver->ttys[idx] = tty; 413 } else { 414 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 415 tty->termios = driver->init_termios; 416 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 417 o_tty->termios = driver->other->init_termios; 418 } 419 420 /* 421 * Everything allocated ... set up the o_tty structure. 422 */ 423 tty_driver_kref_get(driver->other); 424 /* Establish the links in both directions */ 425 tty->link = o_tty; 426 o_tty->link = tty; 427 tty_port_init(ports[0]); 428 tty_port_init(ports[1]); 429 tty_buffer_set_limit(ports[0], 8192); 430 tty_buffer_set_limit(ports[1], 8192); 431 o_tty->port = ports[0]; 432 tty->port = ports[1]; 433 o_tty->port->itty = o_tty; 434 435 tty_buffer_set_lock_subclass(o_tty->port); 436 437 tty_driver_kref_get(driver); 438 tty->count++; 439 o_tty->count++; 440 return 0; 441 442 err_put_module: 443 module_put(driver->other->owner); 444 err: 445 kfree(ports[0]); 446 kfree(ports[1]); 447 return retval; 448 } 449 450 static void pty_cleanup(struct tty_struct *tty) 451 { 452 tty_port_put(tty->port); 453 } 454 455 /* Traditional BSD devices */ 456 #ifdef CONFIG_LEGACY_PTYS 457 458 static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 459 { 460 return pty_common_install(driver, tty, true); 461 } 462 463 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 464 { 465 struct tty_struct *pair = tty->link; 466 driver->ttys[tty->index] = NULL; 467 if (pair) 468 pair->driver->ttys[pair->index] = NULL; 469 } 470 471 static int pty_bsd_ioctl(struct tty_struct *tty, 472 unsigned int cmd, unsigned long arg) 473 { 474 switch (cmd) { 475 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 476 return pty_set_lock(tty, (int __user *) arg); 477 case TIOCGPTLCK: /* Get PT Lock status */ 478 return pty_get_lock(tty, (int __user *)arg); 479 case TIOCPKT: /* Set PT packet mode */ 480 return pty_set_pktmode(tty, (int __user *)arg); 481 case TIOCGPKT: /* Get PT packet mode */ 482 return pty_get_pktmode(tty, (int __user *)arg); 483 case TIOCSIG: /* Send signal to other side of pty */ 484 return pty_signal(tty, (int) arg); 485 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 486 return -EINVAL; 487 } 488 return -ENOIOCTLCMD; 489 } 490 491 static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 492 /* 493 * not really modular, but the easiest way to keep compat with existing 494 * bootargs behaviour is to continue using module_param here. 495 */ 496 module_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 */ 502 static 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 }; 516 517 static 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 }; 533 534 static 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 590 static inline void legacy_pty_init(void) { } 591 #endif 592 593 /* Unix98 devices */ 594 #ifdef CONFIG_UNIX98_PTYS 595 596 static struct cdev ptmx_cdev; 597 598 static 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 */ 627 628 static 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 */ 643 644 static 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 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 659 { 660 return pty_common_install(driver, tty, false); 661 } 662 663 /* this is called once with whichever end is closed last */ 664 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 665 { 666 struct inode *ptmx_inode; 667 668 if (tty->driver->subtype == PTY_TYPE_MASTER) 669 ptmx_inode = tty->driver_data; 670 else 671 ptmx_inode = tty->link->driver_data; 672 devpts_kill_index(ptmx_inode, tty->index); 673 devpts_del_ref(ptmx_inode); 674 } 675 676 static const struct tty_operations ptm_unix98_ops = { 677 .lookup = ptm_unix98_lookup, 678 .install = pty_unix98_install, 679 .remove = pty_unix98_remove, 680 .open = pty_open, 681 .close = pty_close, 682 .write = pty_write, 683 .write_room = pty_write_room, 684 .flush_buffer = pty_flush_buffer, 685 .chars_in_buffer = pty_chars_in_buffer, 686 .unthrottle = pty_unthrottle, 687 .ioctl = pty_unix98_ioctl, 688 .resize = pty_resize, 689 .cleanup = pty_cleanup 690 }; 691 692 static const struct tty_operations pty_unix98_ops = { 693 .lookup = pts_unix98_lookup, 694 .install = pty_unix98_install, 695 .remove = pty_unix98_remove, 696 .open = pty_open, 697 .close = pty_close, 698 .write = pty_write, 699 .write_room = pty_write_room, 700 .flush_buffer = pty_flush_buffer, 701 .chars_in_buffer = pty_chars_in_buffer, 702 .unthrottle = pty_unthrottle, 703 .set_termios = pty_set_termios, 704 .start = pty_start, 705 .stop = pty_stop, 706 .cleanup = pty_cleanup, 707 }; 708 709 /** 710 * ptmx_open - open a unix 98 pty master 711 * @inode: inode of device file 712 * @filp: file pointer to tty 713 * 714 * Allocate a unix98 pty master device from the ptmx driver. 715 * 716 * Locking: tty_mutex protects the init_dev work. tty->count should 717 * protect the rest. 718 * allocated_ptys_lock handles the list of free pty numbers 719 */ 720 721 static int ptmx_open(struct inode *inode, struct file *filp) 722 { 723 struct tty_struct *tty; 724 struct inode *slave_inode; 725 int retval; 726 int index; 727 728 nonseekable_open(inode, filp); 729 730 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 731 filp->f_mode |= FMODE_NONOTIFY; 732 733 retval = tty_alloc_file(filp); 734 if (retval) 735 return retval; 736 737 /* find a device that is not in use. */ 738 mutex_lock(&devpts_mutex); 739 index = devpts_new_index(inode); 740 if (index < 0) { 741 retval = index; 742 mutex_unlock(&devpts_mutex); 743 goto err_file; 744 } 745 746 mutex_unlock(&devpts_mutex); 747 748 mutex_lock(&tty_mutex); 749 tty = tty_init_dev(ptm_driver, index); 750 751 if (IS_ERR(tty)) { 752 retval = PTR_ERR(tty); 753 goto out; 754 } 755 756 /* The tty returned here is locked so we can safely 757 drop the mutex */ 758 mutex_unlock(&tty_mutex); 759 760 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 761 tty->driver_data = inode; 762 763 /* 764 * In the case where all references to ptmx inode are dropped and we 765 * still have /dev/tty opened pointing to the master/slave pair (ptmx 766 * is closed/released before /dev/tty), we must make sure that the inode 767 * is still valid when we call the final pty_unix98_shutdown, thus we 768 * hold an additional reference to the ptmx inode. For the same /dev/tty 769 * last close case, we also need to make sure the super_block isn't 770 * destroyed (devpts instance unmounted), before /dev/tty is closed and 771 * on its release devpts_kill_index is called. 772 */ 773 devpts_add_ref(inode); 774 775 tty_add_file(tty, filp); 776 777 slave_inode = devpts_pty_new(inode, 778 MKDEV(UNIX98_PTY_SLAVE_MAJOR, index), index, 779 tty->link); 780 if (IS_ERR(slave_inode)) { 781 retval = PTR_ERR(slave_inode); 782 goto err_release; 783 } 784 tty->link->driver_data = slave_inode; 785 786 retval = ptm_driver->ops->open(tty, filp); 787 if (retval) 788 goto err_release; 789 790 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); 791 792 tty_unlock(tty); 793 return 0; 794 err_release: 795 tty_unlock(tty); 796 tty_release(inode, filp); 797 return retval; 798 out: 799 mutex_unlock(&tty_mutex); 800 devpts_kill_index(inode, index); 801 err_file: 802 tty_free_file(filp); 803 return retval; 804 } 805 806 static struct file_operations ptmx_fops; 807 808 static void __init unix98_pty_init(void) 809 { 810 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 811 TTY_DRIVER_RESET_TERMIOS | 812 TTY_DRIVER_REAL_RAW | 813 TTY_DRIVER_DYNAMIC_DEV | 814 TTY_DRIVER_DEVPTS_MEM | 815 TTY_DRIVER_DYNAMIC_ALLOC); 816 if (IS_ERR(ptm_driver)) 817 panic("Couldn't allocate Unix98 ptm driver"); 818 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 819 TTY_DRIVER_RESET_TERMIOS | 820 TTY_DRIVER_REAL_RAW | 821 TTY_DRIVER_DYNAMIC_DEV | 822 TTY_DRIVER_DEVPTS_MEM | 823 TTY_DRIVER_DYNAMIC_ALLOC); 824 if (IS_ERR(pts_driver)) 825 panic("Couldn't allocate Unix98 pts driver"); 826 827 ptm_driver->driver_name = "pty_master"; 828 ptm_driver->name = "ptm"; 829 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 830 ptm_driver->minor_start = 0; 831 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 832 ptm_driver->subtype = PTY_TYPE_MASTER; 833 ptm_driver->init_termios = tty_std_termios; 834 ptm_driver->init_termios.c_iflag = 0; 835 ptm_driver->init_termios.c_oflag = 0; 836 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 837 ptm_driver->init_termios.c_lflag = 0; 838 ptm_driver->init_termios.c_ispeed = 38400; 839 ptm_driver->init_termios.c_ospeed = 38400; 840 ptm_driver->other = pts_driver; 841 tty_set_operations(ptm_driver, &ptm_unix98_ops); 842 843 pts_driver->driver_name = "pty_slave"; 844 pts_driver->name = "pts"; 845 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 846 pts_driver->minor_start = 0; 847 pts_driver->type = TTY_DRIVER_TYPE_PTY; 848 pts_driver->subtype = PTY_TYPE_SLAVE; 849 pts_driver->init_termios = tty_std_termios; 850 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 851 pts_driver->init_termios.c_ispeed = 38400; 852 pts_driver->init_termios.c_ospeed = 38400; 853 pts_driver->other = ptm_driver; 854 tty_set_operations(pts_driver, &pty_unix98_ops); 855 856 if (tty_register_driver(ptm_driver)) 857 panic("Couldn't register Unix98 ptm driver"); 858 if (tty_register_driver(pts_driver)) 859 panic("Couldn't register Unix98 pts driver"); 860 861 /* Now create the /dev/ptmx special device */ 862 tty_default_fops(&ptmx_fops); 863 ptmx_fops.open = ptmx_open; 864 865 cdev_init(&ptmx_cdev, &ptmx_fops); 866 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 867 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 868 panic("Couldn't register /dev/ptmx driver"); 869 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 870 } 871 872 #else 873 static inline void unix98_pty_init(void) { } 874 #endif 875 876 static int __init pty_init(void) 877 { 878 legacy_pty_init(); 879 unix98_pty_init(); 880 return 0; 881 } 882 device_initcall(pty_init); 883