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/signal.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 (tty_io_error(tty)) 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 wake_up_interruptible(&tty->link->read_wait); 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 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 251 set_bit(TTY_THROTTLED, &tty->flags); 252 return 0; 253 254 out: 255 set_bit(TTY_IO_ERROR, &tty->flags); 256 return -EIO; 257 } 258 259 static void pty_set_termios(struct tty_struct *tty, 260 struct ktermios *old_termios) 261 { 262 /* See if packet mode change of state. */ 263 if (tty->link && tty->link->packet) { 264 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty); 265 int old_flow = ((old_termios->c_iflag & IXON) && 266 (old_termios->c_cc[VSTOP] == '\023') && 267 (old_termios->c_cc[VSTART] == '\021')); 268 int new_flow = (I_IXON(tty) && 269 STOP_CHAR(tty) == '\023' && 270 START_CHAR(tty) == '\021'); 271 if ((old_flow != new_flow) || extproc) { 272 spin_lock_irq(&tty->ctrl_lock); 273 if (old_flow != new_flow) { 274 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 275 if (new_flow) 276 tty->ctrl_status |= TIOCPKT_DOSTOP; 277 else 278 tty->ctrl_status |= TIOCPKT_NOSTOP; 279 } 280 if (extproc) 281 tty->ctrl_status |= TIOCPKT_IOCTL; 282 spin_unlock_irq(&tty->ctrl_lock); 283 wake_up_interruptible(&tty->link->read_wait); 284 } 285 } 286 287 tty->termios.c_cflag &= ~(CSIZE | PARENB); 288 tty->termios.c_cflag |= (CS8 | CREAD); 289 } 290 291 /** 292 * pty_do_resize - resize event 293 * @tty: tty being resized 294 * @ws: window size being set. 295 * 296 * Update the termios variables and send the necessary signals to 297 * peform a terminal resize correctly 298 */ 299 300 static int pty_resize(struct tty_struct *tty, struct winsize *ws) 301 { 302 struct pid *pgrp, *rpgrp; 303 struct tty_struct *pty = tty->link; 304 305 /* For a PTY we need to lock the tty side */ 306 mutex_lock(&tty->winsize_mutex); 307 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 308 goto done; 309 310 /* Signal the foreground process group of both ptys */ 311 pgrp = tty_get_pgrp(tty); 312 rpgrp = tty_get_pgrp(pty); 313 314 if (pgrp) 315 kill_pgrp(pgrp, SIGWINCH, 1); 316 if (rpgrp != pgrp && rpgrp) 317 kill_pgrp(rpgrp, SIGWINCH, 1); 318 319 put_pid(pgrp); 320 put_pid(rpgrp); 321 322 tty->winsize = *ws; 323 pty->winsize = *ws; /* Never used so will go away soon */ 324 done: 325 mutex_unlock(&tty->winsize_mutex); 326 return 0; 327 } 328 329 /** 330 * pty_start - start() handler 331 * pty_stop - stop() handler 332 * @tty: tty being flow-controlled 333 * 334 * Propagates the TIOCPKT status to the master pty. 335 * 336 * NB: only the master pty can be in packet mode so only the slave 337 * needs start()/stop() handlers 338 */ 339 static void pty_start(struct tty_struct *tty) 340 { 341 unsigned long flags; 342 343 if (tty->link && tty->link->packet) { 344 spin_lock_irqsave(&tty->ctrl_lock, flags); 345 tty->ctrl_status &= ~TIOCPKT_STOP; 346 tty->ctrl_status |= TIOCPKT_START; 347 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 348 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 349 } 350 } 351 352 static void pty_stop(struct tty_struct *tty) 353 { 354 unsigned long flags; 355 356 if (tty->link && tty->link->packet) { 357 spin_lock_irqsave(&tty->ctrl_lock, flags); 358 tty->ctrl_status &= ~TIOCPKT_START; 359 tty->ctrl_status |= TIOCPKT_STOP; 360 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 361 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 362 } 363 } 364 365 /** 366 * pty_common_install - set up the pty pair 367 * @driver: the pty driver 368 * @tty: the tty being instantiated 369 * @legacy: true if this is BSD style 370 * 371 * Perform the initial set up for the tty/pty pair. Called from the 372 * tty layer when the port is first opened. 373 * 374 * Locking: the caller must hold the tty_mutex 375 */ 376 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 377 bool legacy) 378 { 379 struct tty_struct *o_tty; 380 struct tty_port *ports[2]; 381 int idx = tty->index; 382 int retval = -ENOMEM; 383 384 /* Opening the slave first has always returned -EIO */ 385 if (driver->subtype != PTY_TYPE_MASTER) 386 return -EIO; 387 388 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 389 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 390 if (!ports[0] || !ports[1]) 391 goto err; 392 if (!try_module_get(driver->other->owner)) { 393 /* This cannot in fact currently happen */ 394 goto err; 395 } 396 o_tty = alloc_tty_struct(driver->other, idx); 397 if (!o_tty) 398 goto err_put_module; 399 400 tty_set_lock_subclass(o_tty); 401 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 402 403 if (legacy) { 404 /* We always use new tty termios data so we can do this 405 the easy way .. */ 406 tty_init_termios(tty); 407 tty_init_termios(o_tty); 408 409 driver->other->ttys[idx] = o_tty; 410 driver->ttys[idx] = tty; 411 } else { 412 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 413 tty->termios = driver->init_termios; 414 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 415 o_tty->termios = driver->other->init_termios; 416 } 417 418 /* 419 * Everything allocated ... set up the o_tty structure. 420 */ 421 tty_driver_kref_get(driver->other); 422 /* Establish the links in both directions */ 423 tty->link = o_tty; 424 o_tty->link = tty; 425 tty_port_init(ports[0]); 426 tty_port_init(ports[1]); 427 tty_buffer_set_limit(ports[0], 8192); 428 tty_buffer_set_limit(ports[1], 8192); 429 o_tty->port = ports[0]; 430 tty->port = ports[1]; 431 o_tty->port->itty = o_tty; 432 433 tty_buffer_set_lock_subclass(o_tty->port); 434 435 tty_driver_kref_get(driver); 436 tty->count++; 437 o_tty->count++; 438 return 0; 439 440 err_put_module: 441 module_put(driver->other->owner); 442 err: 443 kfree(ports[0]); 444 kfree(ports[1]); 445 return retval; 446 } 447 448 static void pty_cleanup(struct tty_struct *tty) 449 { 450 tty_port_put(tty->port); 451 } 452 453 /* Traditional BSD devices */ 454 #ifdef CONFIG_LEGACY_PTYS 455 456 static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 457 { 458 return pty_common_install(driver, tty, true); 459 } 460 461 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 462 { 463 struct tty_struct *pair = tty->link; 464 driver->ttys[tty->index] = NULL; 465 if (pair) 466 pair->driver->ttys[pair->index] = NULL; 467 } 468 469 static int pty_bsd_ioctl(struct tty_struct *tty, 470 unsigned int cmd, unsigned long arg) 471 { 472 switch (cmd) { 473 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 474 return pty_set_lock(tty, (int __user *) arg); 475 case TIOCGPTLCK: /* Get PT Lock status */ 476 return pty_get_lock(tty, (int __user *)arg); 477 case TIOCPKT: /* Set PT packet mode */ 478 return pty_set_pktmode(tty, (int __user *)arg); 479 case TIOCGPKT: /* Get PT packet mode */ 480 return pty_get_pktmode(tty, (int __user *)arg); 481 case TIOCSIG: /* Send signal to other side of pty */ 482 return pty_signal(tty, (int) arg); 483 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 484 return -EINVAL; 485 } 486 return -ENOIOCTLCMD; 487 } 488 489 static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 490 /* 491 * not really modular, but the easiest way to keep compat with existing 492 * bootargs behaviour is to continue using module_param here. 493 */ 494 module_param(legacy_count, int, 0); 495 496 /* 497 * The master side of a pty can do TIOCSPTLCK and thus 498 * has pty_bsd_ioctl. 499 */ 500 static const struct tty_operations master_pty_ops_bsd = { 501 .install = pty_install, 502 .open = pty_open, 503 .close = pty_close, 504 .write = pty_write, 505 .write_room = pty_write_room, 506 .flush_buffer = pty_flush_buffer, 507 .chars_in_buffer = pty_chars_in_buffer, 508 .unthrottle = pty_unthrottle, 509 .ioctl = pty_bsd_ioctl, 510 .cleanup = pty_cleanup, 511 .resize = pty_resize, 512 .remove = pty_remove 513 }; 514 515 static const struct tty_operations slave_pty_ops_bsd = { 516 .install = pty_install, 517 .open = pty_open, 518 .close = pty_close, 519 .write = pty_write, 520 .write_room = pty_write_room, 521 .flush_buffer = pty_flush_buffer, 522 .chars_in_buffer = pty_chars_in_buffer, 523 .unthrottle = pty_unthrottle, 524 .set_termios = pty_set_termios, 525 .cleanup = pty_cleanup, 526 .resize = pty_resize, 527 .start = pty_start, 528 .stop = pty_stop, 529 .remove = pty_remove 530 }; 531 532 static void __init legacy_pty_init(void) 533 { 534 struct tty_driver *pty_driver, *pty_slave_driver; 535 536 if (legacy_count <= 0) 537 return; 538 539 pty_driver = tty_alloc_driver(legacy_count, 540 TTY_DRIVER_RESET_TERMIOS | 541 TTY_DRIVER_REAL_RAW | 542 TTY_DRIVER_DYNAMIC_ALLOC); 543 if (IS_ERR(pty_driver)) 544 panic("Couldn't allocate pty driver"); 545 546 pty_slave_driver = tty_alloc_driver(legacy_count, 547 TTY_DRIVER_RESET_TERMIOS | 548 TTY_DRIVER_REAL_RAW | 549 TTY_DRIVER_DYNAMIC_ALLOC); 550 if (IS_ERR(pty_slave_driver)) 551 panic("Couldn't allocate pty slave driver"); 552 553 pty_driver->driver_name = "pty_master"; 554 pty_driver->name = "pty"; 555 pty_driver->major = PTY_MASTER_MAJOR; 556 pty_driver->minor_start = 0; 557 pty_driver->type = TTY_DRIVER_TYPE_PTY; 558 pty_driver->subtype = PTY_TYPE_MASTER; 559 pty_driver->init_termios = tty_std_termios; 560 pty_driver->init_termios.c_iflag = 0; 561 pty_driver->init_termios.c_oflag = 0; 562 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 563 pty_driver->init_termios.c_lflag = 0; 564 pty_driver->init_termios.c_ispeed = 38400; 565 pty_driver->init_termios.c_ospeed = 38400; 566 pty_driver->other = pty_slave_driver; 567 tty_set_operations(pty_driver, &master_pty_ops_bsd); 568 569 pty_slave_driver->driver_name = "pty_slave"; 570 pty_slave_driver->name = "ttyp"; 571 pty_slave_driver->major = PTY_SLAVE_MAJOR; 572 pty_slave_driver->minor_start = 0; 573 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; 574 pty_slave_driver->subtype = PTY_TYPE_SLAVE; 575 pty_slave_driver->init_termios = tty_std_termios; 576 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 577 pty_slave_driver->init_termios.c_ispeed = 38400; 578 pty_slave_driver->init_termios.c_ospeed = 38400; 579 pty_slave_driver->other = pty_driver; 580 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd); 581 582 if (tty_register_driver(pty_driver)) 583 panic("Couldn't register pty driver"); 584 if (tty_register_driver(pty_slave_driver)) 585 panic("Couldn't register pty slave driver"); 586 } 587 #else 588 static inline void legacy_pty_init(void) { } 589 #endif 590 591 /* Unix98 devices */ 592 #ifdef CONFIG_UNIX98_PTYS 593 594 static struct cdev ptmx_cdev; 595 596 static int pty_unix98_ioctl(struct tty_struct *tty, 597 unsigned int cmd, unsigned long arg) 598 { 599 switch (cmd) { 600 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 601 return pty_set_lock(tty, (int __user *)arg); 602 case TIOCGPTLCK: /* Get PT Lock status */ 603 return pty_get_lock(tty, (int __user *)arg); 604 case TIOCPKT: /* Set PT packet mode */ 605 return pty_set_pktmode(tty, (int __user *)arg); 606 case TIOCGPKT: /* Get PT packet mode */ 607 return pty_get_pktmode(tty, (int __user *)arg); 608 case TIOCGPTN: /* Get PT Number */ 609 return put_user(tty->index, (unsigned int __user *)arg); 610 case TIOCSIG: /* Send signal to other side of pty */ 611 return pty_signal(tty, (int) arg); 612 } 613 614 return -ENOIOCTLCMD; 615 } 616 617 /** 618 * ptm_unix98_lookup - find a pty master 619 * @driver: ptm driver 620 * @idx: tty index 621 * 622 * Look up a pty master device. Called under the tty_mutex for now. 623 * This provides our locking. 624 */ 625 626 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, 627 struct file *file, int idx) 628 { 629 /* Master must be open via /dev/ptmx */ 630 return ERR_PTR(-EIO); 631 } 632 633 /** 634 * pts_unix98_lookup - find a pty slave 635 * @driver: pts driver 636 * @idx: tty index 637 * 638 * Look up a pty master device. Called under the tty_mutex for now. 639 * This provides our locking for the tty pointer. 640 */ 641 642 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, 643 struct file *file, int idx) 644 { 645 struct tty_struct *tty; 646 647 mutex_lock(&devpts_mutex); 648 tty = devpts_get_priv(file->f_path.dentry); 649 mutex_unlock(&devpts_mutex); 650 /* Master must be open before slave */ 651 if (!tty) 652 return ERR_PTR(-EIO); 653 return tty; 654 } 655 656 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 657 { 658 return pty_common_install(driver, tty, false); 659 } 660 661 /* this is called once with whichever end is closed last */ 662 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 663 { 664 struct pts_fs_info *fsi; 665 666 if (tty->driver->subtype == PTY_TYPE_MASTER) 667 fsi = tty->driver_data; 668 else 669 fsi = tty->link->driver_data; 670 671 if (fsi) { 672 devpts_kill_index(fsi, tty->index); 673 devpts_release(fsi); 674 } 675 } 676 677 static const struct tty_operations ptm_unix98_ops = { 678 .lookup = ptm_unix98_lookup, 679 .install = pty_unix98_install, 680 .remove = pty_unix98_remove, 681 .open = pty_open, 682 .close = pty_close, 683 .write = pty_write, 684 .write_room = pty_write_room, 685 .flush_buffer = pty_flush_buffer, 686 .chars_in_buffer = pty_chars_in_buffer, 687 .unthrottle = pty_unthrottle, 688 .ioctl = pty_unix98_ioctl, 689 .resize = pty_resize, 690 .cleanup = pty_cleanup 691 }; 692 693 static const struct tty_operations pty_unix98_ops = { 694 .lookup = pts_unix98_lookup, 695 .install = pty_unix98_install, 696 .remove = pty_unix98_remove, 697 .open = pty_open, 698 .close = pty_close, 699 .write = pty_write, 700 .write_room = pty_write_room, 701 .flush_buffer = pty_flush_buffer, 702 .chars_in_buffer = pty_chars_in_buffer, 703 .unthrottle = pty_unthrottle, 704 .set_termios = pty_set_termios, 705 .start = pty_start, 706 .stop = pty_stop, 707 .cleanup = pty_cleanup, 708 }; 709 710 /** 711 * ptmx_open - open a unix 98 pty master 712 * @inode: inode of device file 713 * @filp: file pointer to tty 714 * 715 * Allocate a unix98 pty master device from the ptmx driver. 716 * 717 * Locking: tty_mutex protects the init_dev work. tty->count should 718 * protect the rest. 719 * allocated_ptys_lock handles the list of free pty numbers 720 */ 721 722 static int ptmx_open(struct inode *inode, struct file *filp) 723 { 724 struct pts_fs_info *fsi; 725 struct tty_struct *tty; 726 struct dentry *dentry; 727 int retval; 728 int index; 729 730 nonseekable_open(inode, filp); 731 732 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 733 filp->f_mode |= FMODE_NONOTIFY; 734 735 retval = tty_alloc_file(filp); 736 if (retval) 737 return retval; 738 739 fsi = devpts_acquire(filp); 740 if (IS_ERR(fsi)) { 741 retval = PTR_ERR(fsi); 742 goto out_free_file; 743 } 744 745 /* find a device that is not in use. */ 746 mutex_lock(&devpts_mutex); 747 index = devpts_new_index(fsi); 748 mutex_unlock(&devpts_mutex); 749 750 retval = index; 751 if (index < 0) 752 goto out_put_fsi; 753 754 755 mutex_lock(&tty_mutex); 756 tty = tty_init_dev(ptm_driver, index); 757 /* The tty returned here is locked so we can safely 758 drop the mutex */ 759 mutex_unlock(&tty_mutex); 760 761 retval = PTR_ERR(tty); 762 if (IS_ERR(tty)) 763 goto out; 764 765 /* 766 * From here on out, the tty is "live", and the index and 767 * fsi will be killed/put by the tty_release() 768 */ 769 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 770 tty->driver_data = fsi; 771 772 tty_add_file(tty, filp); 773 774 dentry = devpts_pty_new(fsi, index, tty->link); 775 if (IS_ERR(dentry)) { 776 retval = PTR_ERR(dentry); 777 goto err_release; 778 } 779 tty->link->driver_data = dentry; 780 781 retval = ptm_driver->ops->open(tty, filp); 782 if (retval) 783 goto err_release; 784 785 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); 786 787 tty_unlock(tty); 788 return 0; 789 err_release: 790 tty_unlock(tty); 791 // This will also put-ref the fsi 792 tty_release(inode, filp); 793 return retval; 794 out: 795 devpts_kill_index(fsi, index); 796 out_put_fsi: 797 devpts_release(fsi); 798 out_free_file: 799 tty_free_file(filp); 800 return retval; 801 } 802 803 static struct file_operations ptmx_fops __ro_after_init; 804 805 static void __init unix98_pty_init(void) 806 { 807 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 808 TTY_DRIVER_RESET_TERMIOS | 809 TTY_DRIVER_REAL_RAW | 810 TTY_DRIVER_DYNAMIC_DEV | 811 TTY_DRIVER_DEVPTS_MEM | 812 TTY_DRIVER_DYNAMIC_ALLOC); 813 if (IS_ERR(ptm_driver)) 814 panic("Couldn't allocate Unix98 ptm driver"); 815 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 816 TTY_DRIVER_RESET_TERMIOS | 817 TTY_DRIVER_REAL_RAW | 818 TTY_DRIVER_DYNAMIC_DEV | 819 TTY_DRIVER_DEVPTS_MEM | 820 TTY_DRIVER_DYNAMIC_ALLOC); 821 if (IS_ERR(pts_driver)) 822 panic("Couldn't allocate Unix98 pts driver"); 823 824 ptm_driver->driver_name = "pty_master"; 825 ptm_driver->name = "ptm"; 826 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 827 ptm_driver->minor_start = 0; 828 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 829 ptm_driver->subtype = PTY_TYPE_MASTER; 830 ptm_driver->init_termios = tty_std_termios; 831 ptm_driver->init_termios.c_iflag = 0; 832 ptm_driver->init_termios.c_oflag = 0; 833 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 834 ptm_driver->init_termios.c_lflag = 0; 835 ptm_driver->init_termios.c_ispeed = 38400; 836 ptm_driver->init_termios.c_ospeed = 38400; 837 ptm_driver->other = pts_driver; 838 tty_set_operations(ptm_driver, &ptm_unix98_ops); 839 840 pts_driver->driver_name = "pty_slave"; 841 pts_driver->name = "pts"; 842 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 843 pts_driver->minor_start = 0; 844 pts_driver->type = TTY_DRIVER_TYPE_PTY; 845 pts_driver->subtype = PTY_TYPE_SLAVE; 846 pts_driver->init_termios = tty_std_termios; 847 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 848 pts_driver->init_termios.c_ispeed = 38400; 849 pts_driver->init_termios.c_ospeed = 38400; 850 pts_driver->other = ptm_driver; 851 tty_set_operations(pts_driver, &pty_unix98_ops); 852 853 if (tty_register_driver(ptm_driver)) 854 panic("Couldn't register Unix98 ptm driver"); 855 if (tty_register_driver(pts_driver)) 856 panic("Couldn't register Unix98 pts driver"); 857 858 /* Now create the /dev/ptmx special device */ 859 tty_default_fops(&ptmx_fops); 860 ptmx_fops.open = ptmx_open; 861 862 cdev_init(&ptmx_cdev, &ptmx_fops); 863 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 864 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 865 panic("Couldn't register /dev/ptmx driver"); 866 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 867 } 868 869 #else 870 static inline void unix98_pty_init(void) { } 871 #endif 872 873 static int __init pty_init(void) 874 { 875 legacy_pty_init(); 876 unix98_pty_init(); 877 return 0; 878 } 879 device_initcall(pty_init); 880