1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * 5 * Added support for a Unix98-style ptmx device. 6 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 7 * 8 */ 9 10 #include <linux/module.h> 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/signal.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 #include <linux/mount.h> 29 #include <linux/file.h> 30 #include <linux/ioctl.h> 31 #include <linux/compat.h> 32 #include "tty.h" 33 34 #undef TTY_DEBUG_HANGUP 35 #ifdef TTY_DEBUG_HANGUP 36 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args) 37 #else 38 # define tty_debug_hangup(tty, f, args...) do {} while (0) 39 #endif 40 41 #ifdef CONFIG_UNIX98_PTYS 42 static struct tty_driver *ptm_driver; 43 static struct tty_driver *pts_driver; 44 static DEFINE_MUTEX(devpts_mutex); 45 #endif 46 47 static void pty_close(struct tty_struct *tty, struct file *filp) 48 { 49 if (tty->driver->subtype == PTY_TYPE_MASTER) 50 WARN_ON(tty->count > 1); 51 else { 52 if (tty_io_error(tty)) 53 return; 54 if (tty->count > 2) 55 return; 56 } 57 set_bit(TTY_IO_ERROR, &tty->flags); 58 wake_up_interruptible(&tty->read_wait); 59 wake_up_interruptible(&tty->write_wait); 60 spin_lock_irq(&tty->ctrl.lock); 61 tty->ctrl.packet = false; 62 spin_unlock_irq(&tty->ctrl.lock); 63 /* Review - krefs on tty_link ?? */ 64 if (!tty->link) 65 return; 66 set_bit(TTY_OTHER_CLOSED, &tty->link->flags); 67 wake_up_interruptible(&tty->link->read_wait); 68 wake_up_interruptible(&tty->link->write_wait); 69 if (tty->driver->subtype == PTY_TYPE_MASTER) { 70 set_bit(TTY_OTHER_CLOSED, &tty->flags); 71 #ifdef CONFIG_UNIX98_PTYS 72 if (tty->driver == ptm_driver) { 73 mutex_lock(&devpts_mutex); 74 if (tty->link->driver_data) 75 devpts_pty_kill(tty->link->driver_data); 76 mutex_unlock(&devpts_mutex); 77 } 78 #endif 79 tty_vhangup(tty->link); 80 } 81 } 82 83 /* 84 * The unthrottle routine is called by the line discipline to signal 85 * that it can receive more characters. For PTY's, the TTY_THROTTLED 86 * flag is always set, to force the line discipline to always call the 87 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 88 * characters in the queue. This is necessary since each time this 89 * happens, we need to wake up any sleeping processes that could be 90 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() 91 * for the pty buffer to be drained. 92 */ 93 static void pty_unthrottle(struct tty_struct *tty) 94 { 95 tty_wakeup(tty->link); 96 set_bit(TTY_THROTTLED, &tty->flags); 97 } 98 99 /** 100 * pty_write - write to a pty 101 * @tty: the tty we write from 102 * @buf: kernel buffer of data 103 * @c: bytes to write 104 * 105 * Our "hardware" write method. Data is coming from the ldisc which 106 * may be in a non sleeping state. We simply throw this at the other 107 * end of the link as if we were an IRQ handler receiving stuff for 108 * the other side of the pty/tty pair. 109 */ 110 111 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 112 { 113 struct tty_struct *to = tty->link; 114 unsigned long flags; 115 116 if (tty->flow.stopped) 117 return 0; 118 119 if (c > 0) { 120 spin_lock_irqsave(&to->port->lock, flags); 121 /* Stuff the data into the input queue of the other end */ 122 c = tty_insert_flip_string(to->port, buf, c); 123 spin_unlock_irqrestore(&to->port->lock, flags); 124 /* And shovel */ 125 if (c) 126 tty_flip_buffer_push(to->port); 127 } 128 return c; 129 } 130 131 /** 132 * pty_write_room - write space 133 * @tty: tty we are writing from 134 * 135 * Report how many bytes the ldisc can send into the queue for 136 * the other device. 137 */ 138 139 static unsigned int pty_write_room(struct tty_struct *tty) 140 { 141 if (tty->flow.stopped) 142 return 0; 143 return tty_buffer_space_avail(tty->link->port); 144 } 145 146 /* Set the lock flag on a pty */ 147 static int pty_set_lock(struct tty_struct *tty, int __user *arg) 148 { 149 int val; 150 151 if (get_user(val, arg)) 152 return -EFAULT; 153 if (val) 154 set_bit(TTY_PTY_LOCK, &tty->flags); 155 else 156 clear_bit(TTY_PTY_LOCK, &tty->flags); 157 return 0; 158 } 159 160 static int pty_get_lock(struct tty_struct *tty, int __user *arg) 161 { 162 int locked = test_bit(TTY_PTY_LOCK, &tty->flags); 163 164 return put_user(locked, arg); 165 } 166 167 /* Set the packet mode on a pty */ 168 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg) 169 { 170 int pktmode; 171 172 if (get_user(pktmode, arg)) 173 return -EFAULT; 174 175 spin_lock_irq(&tty->ctrl.lock); 176 if (pktmode) { 177 if (!tty->ctrl.packet) { 178 tty->link->ctrl.pktstatus = 0; 179 smp_mb(); 180 tty->ctrl.packet = true; 181 } 182 } else 183 tty->ctrl.packet = false; 184 spin_unlock_irq(&tty->ctrl.lock); 185 186 return 0; 187 } 188 189 /* Get the packet mode of a pty */ 190 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) 191 { 192 int pktmode = tty->ctrl.packet; 193 194 return put_user(pktmode, arg); 195 } 196 197 /* Send a signal to the slave */ 198 static int pty_signal(struct tty_struct *tty, int sig) 199 { 200 struct pid *pgrp; 201 202 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) 203 return -EINVAL; 204 205 if (tty->link) { 206 pgrp = tty_get_pgrp(tty->link); 207 if (pgrp) 208 kill_pgrp(pgrp, sig, 1); 209 put_pid(pgrp); 210 } 211 return 0; 212 } 213 214 static void pty_flush_buffer(struct tty_struct *tty) 215 { 216 struct tty_struct *to = tty->link; 217 218 if (!to) 219 return; 220 221 tty_buffer_flush(to, NULL); 222 if (to->ctrl.packet) { 223 spin_lock_irq(&tty->ctrl.lock); 224 tty->ctrl.pktstatus |= TIOCPKT_FLUSHWRITE; 225 wake_up_interruptible(&to->read_wait); 226 spin_unlock_irq(&tty->ctrl.lock); 227 } 228 } 229 230 static int pty_open(struct tty_struct *tty, struct file *filp) 231 { 232 if (!tty || !tty->link) 233 return -ENODEV; 234 235 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 236 goto out; 237 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 238 goto out; 239 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1) 240 goto out; 241 242 clear_bit(TTY_IO_ERROR, &tty->flags); 243 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 244 set_bit(TTY_THROTTLED, &tty->flags); 245 return 0; 246 247 out: 248 set_bit(TTY_IO_ERROR, &tty->flags); 249 return -EIO; 250 } 251 252 static void pty_set_termios(struct tty_struct *tty, 253 struct ktermios *old_termios) 254 { 255 /* See if packet mode change of state. */ 256 if (tty->link && tty->link->ctrl.packet) { 257 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty); 258 int old_flow = ((old_termios->c_iflag & IXON) && 259 (old_termios->c_cc[VSTOP] == '\023') && 260 (old_termios->c_cc[VSTART] == '\021')); 261 int new_flow = (I_IXON(tty) && 262 STOP_CHAR(tty) == '\023' && 263 START_CHAR(tty) == '\021'); 264 if ((old_flow != new_flow) || extproc) { 265 spin_lock_irq(&tty->ctrl.lock); 266 if (old_flow != new_flow) { 267 tty->ctrl.pktstatus &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 268 if (new_flow) 269 tty->ctrl.pktstatus |= TIOCPKT_DOSTOP; 270 else 271 tty->ctrl.pktstatus |= TIOCPKT_NOSTOP; 272 } 273 if (extproc) 274 tty->ctrl.pktstatus |= TIOCPKT_IOCTL; 275 spin_unlock_irq(&tty->ctrl.lock); 276 wake_up_interruptible(&tty->link->read_wait); 277 } 278 } 279 280 tty->termios.c_cflag &= ~(CSIZE | PARENB); 281 tty->termios.c_cflag |= (CS8 | CREAD); 282 } 283 284 /** 285 * pty_resize - resize event 286 * @tty: tty being resized 287 * @ws: window size being set. 288 * 289 * Update the termios variables and send the necessary signals to 290 * peform a terminal resize correctly 291 */ 292 293 static int pty_resize(struct tty_struct *tty, struct winsize *ws) 294 { 295 struct pid *pgrp, *rpgrp; 296 struct tty_struct *pty = tty->link; 297 298 /* For a PTY we need to lock the tty side */ 299 mutex_lock(&tty->winsize_mutex); 300 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 301 goto done; 302 303 /* Signal the foreground process group of both ptys */ 304 pgrp = tty_get_pgrp(tty); 305 rpgrp = tty_get_pgrp(pty); 306 307 if (pgrp) 308 kill_pgrp(pgrp, SIGWINCH, 1); 309 if (rpgrp != pgrp && rpgrp) 310 kill_pgrp(rpgrp, SIGWINCH, 1); 311 312 put_pid(pgrp); 313 put_pid(rpgrp); 314 315 tty->winsize = *ws; 316 pty->winsize = *ws; /* Never used so will go away soon */ 317 done: 318 mutex_unlock(&tty->winsize_mutex); 319 return 0; 320 } 321 322 /** 323 * pty_start - start() handler 324 * pty_stop - stop() handler 325 * @tty: tty being flow-controlled 326 * 327 * Propagates the TIOCPKT status to the master pty. 328 * 329 * NB: only the master pty can be in packet mode so only the slave 330 * needs start()/stop() handlers 331 */ 332 static void pty_start(struct tty_struct *tty) 333 { 334 unsigned long flags; 335 336 if (tty->link && tty->link->ctrl.packet) { 337 spin_lock_irqsave(&tty->ctrl.lock, flags); 338 tty->ctrl.pktstatus &= ~TIOCPKT_STOP; 339 tty->ctrl.pktstatus |= TIOCPKT_START; 340 spin_unlock_irqrestore(&tty->ctrl.lock, flags); 341 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN); 342 } 343 } 344 345 static void pty_stop(struct tty_struct *tty) 346 { 347 unsigned long flags; 348 349 if (tty->link && tty->link->ctrl.packet) { 350 spin_lock_irqsave(&tty->ctrl.lock, flags); 351 tty->ctrl.pktstatus &= ~TIOCPKT_START; 352 tty->ctrl.pktstatus |= TIOCPKT_STOP; 353 spin_unlock_irqrestore(&tty->ctrl.lock, flags); 354 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN); 355 } 356 } 357 358 /** 359 * pty_common_install - set up the pty pair 360 * @driver: the pty driver 361 * @tty: the tty being instantiated 362 * @legacy: true if this is BSD style 363 * 364 * Perform the initial set up for the tty/pty pair. Called from the 365 * tty layer when the port is first opened. 366 * 367 * Locking: the caller must hold the tty_mutex 368 */ 369 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 370 bool legacy) 371 { 372 struct tty_struct *o_tty; 373 struct tty_port *ports[2]; 374 int idx = tty->index; 375 int retval = -ENOMEM; 376 377 /* Opening the slave first has always returned -EIO */ 378 if (driver->subtype != PTY_TYPE_MASTER) 379 return -EIO; 380 381 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 382 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 383 if (!ports[0] || !ports[1]) 384 goto err; 385 if (!try_module_get(driver->other->owner)) { 386 /* This cannot in fact currently happen */ 387 goto err; 388 } 389 o_tty = alloc_tty_struct(driver->other, idx); 390 if (!o_tty) 391 goto err_put_module; 392 393 tty_set_lock_subclass(o_tty); 394 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 395 396 if (legacy) { 397 /* We always use new tty termios data so we can do this 398 the easy way .. */ 399 tty_init_termios(tty); 400 tty_init_termios(o_tty); 401 402 driver->other->ttys[idx] = o_tty; 403 driver->ttys[idx] = tty; 404 } else { 405 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 406 tty->termios = driver->init_termios; 407 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 408 o_tty->termios = driver->other->init_termios; 409 } 410 411 /* 412 * Everything allocated ... set up the o_tty structure. 413 */ 414 tty_driver_kref_get(driver->other); 415 /* Establish the links in both directions */ 416 tty->link = o_tty; 417 o_tty->link = tty; 418 tty_port_init(ports[0]); 419 tty_port_init(ports[1]); 420 tty_buffer_set_limit(ports[0], 8192); 421 tty_buffer_set_limit(ports[1], 8192); 422 o_tty->port = ports[0]; 423 tty->port = ports[1]; 424 o_tty->port->itty = o_tty; 425 426 tty_buffer_set_lock_subclass(o_tty->port); 427 428 tty_driver_kref_get(driver); 429 tty->count++; 430 o_tty->count++; 431 return 0; 432 433 err_put_module: 434 module_put(driver->other->owner); 435 err: 436 kfree(ports[0]); 437 kfree(ports[1]); 438 return retval; 439 } 440 441 static void pty_cleanup(struct tty_struct *tty) 442 { 443 tty_port_put(tty->port); 444 } 445 446 /* Traditional BSD devices */ 447 #ifdef CONFIG_LEGACY_PTYS 448 449 static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 450 { 451 return pty_common_install(driver, tty, true); 452 } 453 454 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 455 { 456 struct tty_struct *pair = tty->link; 457 458 driver->ttys[tty->index] = NULL; 459 if (pair) 460 pair->driver->ttys[pair->index] = NULL; 461 } 462 463 static int pty_bsd_ioctl(struct tty_struct *tty, 464 unsigned int cmd, unsigned long arg) 465 { 466 switch (cmd) { 467 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 468 return pty_set_lock(tty, (int __user *) arg); 469 case TIOCGPTLCK: /* Get PT Lock status */ 470 return pty_get_lock(tty, (int __user *)arg); 471 case TIOCPKT: /* Set PT packet mode */ 472 return pty_set_pktmode(tty, (int __user *)arg); 473 case TIOCGPKT: /* Get PT packet mode */ 474 return pty_get_pktmode(tty, (int __user *)arg); 475 case TIOCSIG: /* Send signal to other side of pty */ 476 return pty_signal(tty, (int) arg); 477 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 478 return -EINVAL; 479 } 480 return -ENOIOCTLCMD; 481 } 482 483 #ifdef CONFIG_COMPAT 484 static long pty_bsd_compat_ioctl(struct tty_struct *tty, 485 unsigned int cmd, unsigned long arg) 486 { 487 /* 488 * PTY ioctls don't require any special translation between 32-bit and 489 * 64-bit userspace, they are already compatible. 490 */ 491 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg)); 492 } 493 #else 494 #define pty_bsd_compat_ioctl NULL 495 #endif 496 497 static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 498 /* 499 * not really modular, but the easiest way to keep compat with existing 500 * bootargs behaviour is to continue using module_param here. 501 */ 502 module_param(legacy_count, int, 0); 503 504 /* 505 * The master side of a pty can do TIOCSPTLCK and thus 506 * has pty_bsd_ioctl. 507 */ 508 static const struct tty_operations master_pty_ops_bsd = { 509 .install = pty_install, 510 .open = pty_open, 511 .close = pty_close, 512 .write = pty_write, 513 .write_room = pty_write_room, 514 .flush_buffer = pty_flush_buffer, 515 .unthrottle = pty_unthrottle, 516 .ioctl = pty_bsd_ioctl, 517 .compat_ioctl = pty_bsd_compat_ioctl, 518 .cleanup = pty_cleanup, 519 .resize = pty_resize, 520 .remove = pty_remove 521 }; 522 523 static const struct tty_operations slave_pty_ops_bsd = { 524 .install = pty_install, 525 .open = pty_open, 526 .close = pty_close, 527 .write = pty_write, 528 .write_room = pty_write_room, 529 .flush_buffer = pty_flush_buffer, 530 .unthrottle = pty_unthrottle, 531 .set_termios = pty_set_termios, 532 .cleanup = pty_cleanup, 533 .resize = pty_resize, 534 .start = pty_start, 535 .stop = pty_stop, 536 .remove = pty_remove 537 }; 538 539 static void __init legacy_pty_init(void) 540 { 541 struct tty_driver *pty_driver, *pty_slave_driver; 542 543 if (legacy_count <= 0) 544 return; 545 546 pty_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_driver)) 551 panic("Couldn't allocate pty driver"); 552 553 pty_slave_driver = tty_alloc_driver(legacy_count, 554 TTY_DRIVER_RESET_TERMIOS | 555 TTY_DRIVER_REAL_RAW | 556 TTY_DRIVER_DYNAMIC_ALLOC); 557 if (IS_ERR(pty_slave_driver)) 558 panic("Couldn't allocate pty slave driver"); 559 560 pty_driver->driver_name = "pty_master"; 561 pty_driver->name = "pty"; 562 pty_driver->major = PTY_MASTER_MAJOR; 563 pty_driver->minor_start = 0; 564 pty_driver->type = TTY_DRIVER_TYPE_PTY; 565 pty_driver->subtype = PTY_TYPE_MASTER; 566 pty_driver->init_termios = tty_std_termios; 567 pty_driver->init_termios.c_iflag = 0; 568 pty_driver->init_termios.c_oflag = 0; 569 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 570 pty_driver->init_termios.c_lflag = 0; 571 pty_driver->init_termios.c_ispeed = 38400; 572 pty_driver->init_termios.c_ospeed = 38400; 573 pty_driver->other = pty_slave_driver; 574 tty_set_operations(pty_driver, &master_pty_ops_bsd); 575 576 pty_slave_driver->driver_name = "pty_slave"; 577 pty_slave_driver->name = "ttyp"; 578 pty_slave_driver->major = PTY_SLAVE_MAJOR; 579 pty_slave_driver->minor_start = 0; 580 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; 581 pty_slave_driver->subtype = PTY_TYPE_SLAVE; 582 pty_slave_driver->init_termios = tty_std_termios; 583 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 584 pty_slave_driver->init_termios.c_ispeed = 38400; 585 pty_slave_driver->init_termios.c_ospeed = 38400; 586 pty_slave_driver->other = pty_driver; 587 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd); 588 589 if (tty_register_driver(pty_driver)) 590 panic("Couldn't register pty driver"); 591 if (tty_register_driver(pty_slave_driver)) 592 panic("Couldn't register pty slave driver"); 593 } 594 #else 595 static inline void legacy_pty_init(void) { } 596 #endif 597 598 /* Unix98 devices */ 599 #ifdef CONFIG_UNIX98_PTYS 600 static struct cdev ptmx_cdev; 601 602 /** 603 * ptm_open_peer - open the peer of a pty 604 * @master: the open struct file of the ptmx device node 605 * @tty: the master of the pty being opened 606 * @flags: the flags for open 607 * 608 * Provide a race free way for userspace to open the slave end of a pty 609 * (where they have the master fd and cannot access or trust the mount 610 * namespace /dev/pts was mounted inside). 611 */ 612 int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags) 613 { 614 int fd; 615 struct file *filp; 616 int retval = -EINVAL; 617 struct path path; 618 619 if (tty->driver != ptm_driver) 620 return -EIO; 621 622 fd = get_unused_fd_flags(flags); 623 if (fd < 0) { 624 retval = fd; 625 goto err; 626 } 627 628 /* Compute the slave's path */ 629 path.mnt = devpts_mntget(master, tty->driver_data); 630 if (IS_ERR(path.mnt)) { 631 retval = PTR_ERR(path.mnt); 632 goto err_put; 633 } 634 path.dentry = tty->link->driver_data; 635 636 filp = dentry_open(&path, flags, current_cred()); 637 mntput(path.mnt); 638 if (IS_ERR(filp)) { 639 retval = PTR_ERR(filp); 640 goto err_put; 641 } 642 643 fd_install(fd, filp); 644 return fd; 645 646 err_put: 647 put_unused_fd(fd); 648 err: 649 return retval; 650 } 651 652 static int pty_unix98_ioctl(struct tty_struct *tty, 653 unsigned int cmd, unsigned long arg) 654 { 655 switch (cmd) { 656 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 657 return pty_set_lock(tty, (int __user *)arg); 658 case TIOCGPTLCK: /* Get PT Lock status */ 659 return pty_get_lock(tty, (int __user *)arg); 660 case TIOCPKT: /* Set PT packet mode */ 661 return pty_set_pktmode(tty, (int __user *)arg); 662 case TIOCGPKT: /* Get PT packet mode */ 663 return pty_get_pktmode(tty, (int __user *)arg); 664 case TIOCGPTN: /* Get PT Number */ 665 return put_user(tty->index, (unsigned int __user *)arg); 666 case TIOCSIG: /* Send signal to other side of pty */ 667 return pty_signal(tty, (int) arg); 668 } 669 670 return -ENOIOCTLCMD; 671 } 672 673 #ifdef CONFIG_COMPAT 674 static long pty_unix98_compat_ioctl(struct tty_struct *tty, 675 unsigned int cmd, unsigned long arg) 676 { 677 /* 678 * PTY ioctls don't require any special translation between 32-bit and 679 * 64-bit userspace, they are already compatible. 680 */ 681 return pty_unix98_ioctl(tty, cmd, 682 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg)); 683 } 684 #else 685 #define pty_unix98_compat_ioctl NULL 686 #endif 687 688 /** 689 * ptm_unix98_lookup - find a pty master 690 * @driver: ptm driver 691 * @file: unused 692 * @idx: tty index 693 * 694 * Look up a pty master device. Called under the tty_mutex for now. 695 * This provides our locking. 696 */ 697 698 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, 699 struct file *file, int idx) 700 { 701 /* Master must be open via /dev/ptmx */ 702 return ERR_PTR(-EIO); 703 } 704 705 /** 706 * pts_unix98_lookup - find a pty slave 707 * @driver: pts driver 708 * @file: file pointer to tty 709 * @idx: tty index 710 * 711 * Look up a pty master device. Called under the tty_mutex for now. 712 * This provides our locking for the tty pointer. 713 */ 714 715 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, 716 struct file *file, int idx) 717 { 718 struct tty_struct *tty; 719 720 mutex_lock(&devpts_mutex); 721 tty = devpts_get_priv(file->f_path.dentry); 722 mutex_unlock(&devpts_mutex); 723 /* Master must be open before slave */ 724 if (!tty) 725 return ERR_PTR(-EIO); 726 return tty; 727 } 728 729 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 730 { 731 return pty_common_install(driver, tty, false); 732 } 733 734 /* this is called once with whichever end is closed last */ 735 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 736 { 737 struct pts_fs_info *fsi; 738 739 if (tty->driver->subtype == PTY_TYPE_MASTER) 740 fsi = tty->driver_data; 741 else 742 fsi = tty->link->driver_data; 743 744 if (fsi) { 745 devpts_kill_index(fsi, tty->index); 746 devpts_release(fsi); 747 } 748 } 749 750 static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m) 751 { 752 seq_printf(m, "tty-index:\t%d\n", tty->index); 753 } 754 755 static const struct tty_operations ptm_unix98_ops = { 756 .lookup = ptm_unix98_lookup, 757 .install = pty_unix98_install, 758 .remove = pty_unix98_remove, 759 .open = pty_open, 760 .close = pty_close, 761 .write = pty_write, 762 .write_room = pty_write_room, 763 .flush_buffer = pty_flush_buffer, 764 .unthrottle = pty_unthrottle, 765 .ioctl = pty_unix98_ioctl, 766 .compat_ioctl = pty_unix98_compat_ioctl, 767 .resize = pty_resize, 768 .cleanup = pty_cleanup, 769 .show_fdinfo = pty_show_fdinfo, 770 }; 771 772 static const struct tty_operations pty_unix98_ops = { 773 .lookup = pts_unix98_lookup, 774 .install = pty_unix98_install, 775 .remove = pty_unix98_remove, 776 .open = pty_open, 777 .close = pty_close, 778 .write = pty_write, 779 .write_room = pty_write_room, 780 .flush_buffer = pty_flush_buffer, 781 .unthrottle = pty_unthrottle, 782 .set_termios = pty_set_termios, 783 .start = pty_start, 784 .stop = pty_stop, 785 .cleanup = pty_cleanup, 786 }; 787 788 /** 789 * ptmx_open - open a unix 98 pty master 790 * @inode: inode of device file 791 * @filp: file pointer to tty 792 * 793 * Allocate a unix98 pty master device from the ptmx driver. 794 * 795 * Locking: tty_mutex protects the init_dev work. tty->count should 796 * protect the rest. 797 * allocated_ptys_lock handles the list of free pty numbers 798 */ 799 800 static int ptmx_open(struct inode *inode, struct file *filp) 801 { 802 struct pts_fs_info *fsi; 803 struct tty_struct *tty; 804 struct dentry *dentry; 805 int retval; 806 int index; 807 808 nonseekable_open(inode, filp); 809 810 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 811 filp->f_mode |= FMODE_NONOTIFY; 812 813 retval = tty_alloc_file(filp); 814 if (retval) 815 return retval; 816 817 fsi = devpts_acquire(filp); 818 if (IS_ERR(fsi)) { 819 retval = PTR_ERR(fsi); 820 goto out_free_file; 821 } 822 823 /* find a device that is not in use. */ 824 mutex_lock(&devpts_mutex); 825 index = devpts_new_index(fsi); 826 mutex_unlock(&devpts_mutex); 827 828 retval = index; 829 if (index < 0) 830 goto out_put_fsi; 831 832 833 mutex_lock(&tty_mutex); 834 tty = tty_init_dev(ptm_driver, index); 835 /* The tty returned here is locked so we can safely 836 drop the mutex */ 837 mutex_unlock(&tty_mutex); 838 839 retval = PTR_ERR(tty); 840 if (IS_ERR(tty)) 841 goto out; 842 843 /* 844 * From here on out, the tty is "live", and the index and 845 * fsi will be killed/put by the tty_release() 846 */ 847 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 848 tty->driver_data = fsi; 849 850 tty_add_file(tty, filp); 851 852 dentry = devpts_pty_new(fsi, index, tty->link); 853 if (IS_ERR(dentry)) { 854 retval = PTR_ERR(dentry); 855 goto err_release; 856 } 857 tty->link->driver_data = dentry; 858 859 retval = ptm_driver->ops->open(tty, filp); 860 if (retval) 861 goto err_release; 862 863 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); 864 865 tty_unlock(tty); 866 return 0; 867 err_release: 868 tty_unlock(tty); 869 // This will also put-ref the fsi 870 tty_release(inode, filp); 871 return retval; 872 out: 873 devpts_kill_index(fsi, index); 874 out_put_fsi: 875 devpts_release(fsi); 876 out_free_file: 877 tty_free_file(filp); 878 return retval; 879 } 880 881 static struct file_operations ptmx_fops __ro_after_init; 882 883 static void __init unix98_pty_init(void) 884 { 885 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 886 TTY_DRIVER_RESET_TERMIOS | 887 TTY_DRIVER_REAL_RAW | 888 TTY_DRIVER_DYNAMIC_DEV | 889 TTY_DRIVER_DEVPTS_MEM | 890 TTY_DRIVER_DYNAMIC_ALLOC); 891 if (IS_ERR(ptm_driver)) 892 panic("Couldn't allocate Unix98 ptm driver"); 893 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 894 TTY_DRIVER_RESET_TERMIOS | 895 TTY_DRIVER_REAL_RAW | 896 TTY_DRIVER_DYNAMIC_DEV | 897 TTY_DRIVER_DEVPTS_MEM | 898 TTY_DRIVER_DYNAMIC_ALLOC); 899 if (IS_ERR(pts_driver)) 900 panic("Couldn't allocate Unix98 pts driver"); 901 902 ptm_driver->driver_name = "pty_master"; 903 ptm_driver->name = "ptm"; 904 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 905 ptm_driver->minor_start = 0; 906 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 907 ptm_driver->subtype = PTY_TYPE_MASTER; 908 ptm_driver->init_termios = tty_std_termios; 909 ptm_driver->init_termios.c_iflag = 0; 910 ptm_driver->init_termios.c_oflag = 0; 911 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 912 ptm_driver->init_termios.c_lflag = 0; 913 ptm_driver->init_termios.c_ispeed = 38400; 914 ptm_driver->init_termios.c_ospeed = 38400; 915 ptm_driver->other = pts_driver; 916 tty_set_operations(ptm_driver, &ptm_unix98_ops); 917 918 pts_driver->driver_name = "pty_slave"; 919 pts_driver->name = "pts"; 920 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 921 pts_driver->minor_start = 0; 922 pts_driver->type = TTY_DRIVER_TYPE_PTY; 923 pts_driver->subtype = PTY_TYPE_SLAVE; 924 pts_driver->init_termios = tty_std_termios; 925 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 926 pts_driver->init_termios.c_ispeed = 38400; 927 pts_driver->init_termios.c_ospeed = 38400; 928 pts_driver->other = ptm_driver; 929 tty_set_operations(pts_driver, &pty_unix98_ops); 930 931 if (tty_register_driver(ptm_driver)) 932 panic("Couldn't register Unix98 ptm driver"); 933 if (tty_register_driver(pts_driver)) 934 panic("Couldn't register Unix98 pts driver"); 935 936 /* Now create the /dev/ptmx special device */ 937 tty_default_fops(&ptmx_fops); 938 ptmx_fops.open = ptmx_open; 939 940 cdev_init(&ptmx_cdev, &ptmx_fops); 941 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 942 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 943 panic("Couldn't register /dev/ptmx driver"); 944 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 945 } 946 947 #else 948 static inline void unix98_pty_init(void) { } 949 #endif 950 951 static int __init pty_init(void) 952 { 953 legacy_pty_init(); 954 unix98_pty_init(); 955 return 0; 956 } 957 device_initcall(pty_init); 958