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->packet = 0; 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->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 int pty_write_room(struct tty_struct *tty) 140 { 141 if (tty->stopped) 142 return 0; 143 return tty_buffer_space_avail(tty->link->port); 144 } 145 146 /** 147 * pty_chars_in_buffer - characters currently in our tx queue 148 * @tty: our tty 149 * 150 * Report how much we have in the transmit queue. As everything is 151 * instantly at the other end this is easy to implement. 152 */ 153 154 static int pty_chars_in_buffer(struct tty_struct *tty) 155 { 156 return 0; 157 } 158 159 /* Set the lock flag on a pty */ 160 static int pty_set_lock(struct tty_struct *tty, int __user *arg) 161 { 162 int val; 163 164 if (get_user(val, arg)) 165 return -EFAULT; 166 if (val) 167 set_bit(TTY_PTY_LOCK, &tty->flags); 168 else 169 clear_bit(TTY_PTY_LOCK, &tty->flags); 170 return 0; 171 } 172 173 static int pty_get_lock(struct tty_struct *tty, int __user *arg) 174 { 175 int locked = test_bit(TTY_PTY_LOCK, &tty->flags); 176 177 return put_user(locked, arg); 178 } 179 180 /* Set the packet mode on a pty */ 181 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg) 182 { 183 int pktmode; 184 185 if (get_user(pktmode, arg)) 186 return -EFAULT; 187 188 spin_lock_irq(&tty->ctrl_lock); 189 if (pktmode) { 190 if (!tty->packet) { 191 tty->link->ctrl_status = 0; 192 smp_mb(); 193 tty->packet = 1; 194 } 195 } else 196 tty->packet = 0; 197 spin_unlock_irq(&tty->ctrl_lock); 198 199 return 0; 200 } 201 202 /* Get the packet mode of a pty */ 203 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) 204 { 205 int pktmode = tty->packet; 206 207 return put_user(pktmode, arg); 208 } 209 210 /* Send a signal to the slave */ 211 static int pty_signal(struct tty_struct *tty, int sig) 212 { 213 struct pid *pgrp; 214 215 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) 216 return -EINVAL; 217 218 if (tty->link) { 219 pgrp = tty_get_pgrp(tty->link); 220 if (pgrp) 221 kill_pgrp(pgrp, sig, 1); 222 put_pid(pgrp); 223 } 224 return 0; 225 } 226 227 static void pty_flush_buffer(struct tty_struct *tty) 228 { 229 struct tty_struct *to = tty->link; 230 231 if (!to) 232 return; 233 234 tty_buffer_flush(to, NULL); 235 if (to->packet) { 236 spin_lock_irq(&tty->ctrl_lock); 237 tty->ctrl_status |= TIOCPKT_FLUSHWRITE; 238 wake_up_interruptible(&to->read_wait); 239 spin_unlock_irq(&tty->ctrl_lock); 240 } 241 } 242 243 static int pty_open(struct tty_struct *tty, struct file *filp) 244 { 245 if (!tty || !tty->link) 246 return -ENODEV; 247 248 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 249 goto out; 250 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 251 goto out; 252 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1) 253 goto out; 254 255 clear_bit(TTY_IO_ERROR, &tty->flags); 256 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 257 set_bit(TTY_THROTTLED, &tty->flags); 258 return 0; 259 260 out: 261 set_bit(TTY_IO_ERROR, &tty->flags); 262 return -EIO; 263 } 264 265 static void pty_set_termios(struct tty_struct *tty, 266 struct ktermios *old_termios) 267 { 268 /* See if packet mode change of state. */ 269 if (tty->link && tty->link->packet) { 270 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty); 271 int old_flow = ((old_termios->c_iflag & IXON) && 272 (old_termios->c_cc[VSTOP] == '\023') && 273 (old_termios->c_cc[VSTART] == '\021')); 274 int new_flow = (I_IXON(tty) && 275 STOP_CHAR(tty) == '\023' && 276 START_CHAR(tty) == '\021'); 277 if ((old_flow != new_flow) || extproc) { 278 spin_lock_irq(&tty->ctrl_lock); 279 if (old_flow != new_flow) { 280 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 281 if (new_flow) 282 tty->ctrl_status |= TIOCPKT_DOSTOP; 283 else 284 tty->ctrl_status |= TIOCPKT_NOSTOP; 285 } 286 if (extproc) 287 tty->ctrl_status |= TIOCPKT_IOCTL; 288 spin_unlock_irq(&tty->ctrl_lock); 289 wake_up_interruptible(&tty->link->read_wait); 290 } 291 } 292 293 tty->termios.c_cflag &= ~(CSIZE | PARENB); 294 tty->termios.c_cflag |= (CS8 | CREAD); 295 } 296 297 /** 298 * pty_do_resize - resize event 299 * @tty: tty being resized 300 * @ws: window size being set. 301 * 302 * Update the termios variables and send the necessary signals to 303 * peform a terminal resize correctly 304 */ 305 306 static int pty_resize(struct tty_struct *tty, struct winsize *ws) 307 { 308 struct pid *pgrp, *rpgrp; 309 struct tty_struct *pty = tty->link; 310 311 /* For a PTY we need to lock the tty side */ 312 mutex_lock(&tty->winsize_mutex); 313 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 314 goto done; 315 316 /* Signal the foreground process group of both ptys */ 317 pgrp = tty_get_pgrp(tty); 318 rpgrp = tty_get_pgrp(pty); 319 320 if (pgrp) 321 kill_pgrp(pgrp, SIGWINCH, 1); 322 if (rpgrp != pgrp && rpgrp) 323 kill_pgrp(rpgrp, SIGWINCH, 1); 324 325 put_pid(pgrp); 326 put_pid(rpgrp); 327 328 tty->winsize = *ws; 329 pty->winsize = *ws; /* Never used so will go away soon */ 330 done: 331 mutex_unlock(&tty->winsize_mutex); 332 return 0; 333 } 334 335 /** 336 * pty_start - start() handler 337 * pty_stop - stop() handler 338 * @tty: tty being flow-controlled 339 * 340 * Propagates the TIOCPKT status to the master pty. 341 * 342 * NB: only the master pty can be in packet mode so only the slave 343 * needs start()/stop() handlers 344 */ 345 static void pty_start(struct tty_struct *tty) 346 { 347 unsigned long flags; 348 349 if (tty->link && tty->link->packet) { 350 spin_lock_irqsave(&tty->ctrl_lock, flags); 351 tty->ctrl_status &= ~TIOCPKT_STOP; 352 tty->ctrl_status |= TIOCPKT_START; 353 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 354 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN); 355 } 356 } 357 358 static void pty_stop(struct tty_struct *tty) 359 { 360 unsigned long flags; 361 362 if (tty->link && tty->link->packet) { 363 spin_lock_irqsave(&tty->ctrl_lock, flags); 364 tty->ctrl_status &= ~TIOCPKT_START; 365 tty->ctrl_status |= TIOCPKT_STOP; 366 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 367 wake_up_interruptible_poll(&tty->link->read_wait, EPOLLIN); 368 } 369 } 370 371 /** 372 * pty_common_install - set up the pty pair 373 * @driver: the pty driver 374 * @tty: the tty being instantiated 375 * @legacy: true if this is BSD style 376 * 377 * Perform the initial set up for the tty/pty pair. Called from the 378 * tty layer when the port is first opened. 379 * 380 * Locking: the caller must hold the tty_mutex 381 */ 382 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 383 bool legacy) 384 { 385 struct tty_struct *o_tty; 386 struct tty_port *ports[2]; 387 int idx = tty->index; 388 int retval = -ENOMEM; 389 390 /* Opening the slave first has always returned -EIO */ 391 if (driver->subtype != PTY_TYPE_MASTER) 392 return -EIO; 393 394 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 395 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 396 if (!ports[0] || !ports[1]) 397 goto err; 398 if (!try_module_get(driver->other->owner)) { 399 /* This cannot in fact currently happen */ 400 goto err; 401 } 402 o_tty = alloc_tty_struct(driver->other, idx); 403 if (!o_tty) 404 goto err_put_module; 405 406 tty_set_lock_subclass(o_tty); 407 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 408 409 if (legacy) { 410 /* We always use new tty termios data so we can do this 411 the easy way .. */ 412 tty_init_termios(tty); 413 tty_init_termios(o_tty); 414 415 driver->other->ttys[idx] = o_tty; 416 driver->ttys[idx] = tty; 417 } else { 418 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 419 tty->termios = driver->init_termios; 420 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 421 o_tty->termios = driver->other->init_termios; 422 } 423 424 /* 425 * Everything allocated ... set up the o_tty structure. 426 */ 427 tty_driver_kref_get(driver->other); 428 /* Establish the links in both directions */ 429 tty->link = o_tty; 430 o_tty->link = tty; 431 tty_port_init(ports[0]); 432 tty_port_init(ports[1]); 433 tty_buffer_set_limit(ports[0], 8192); 434 tty_buffer_set_limit(ports[1], 8192); 435 o_tty->port = ports[0]; 436 tty->port = ports[1]; 437 o_tty->port->itty = o_tty; 438 439 tty_buffer_set_lock_subclass(o_tty->port); 440 441 tty_driver_kref_get(driver); 442 tty->count++; 443 o_tty->count++; 444 return 0; 445 446 err_put_module: 447 module_put(driver->other->owner); 448 err: 449 kfree(ports[0]); 450 kfree(ports[1]); 451 return retval; 452 } 453 454 static 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 461 462 static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 463 { 464 return pty_common_install(driver, tty, true); 465 } 466 467 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 468 { 469 struct tty_struct *pair = tty->link; 470 471 driver->ttys[tty->index] = NULL; 472 if (pair) 473 pair->driver->ttys[pair->index] = NULL; 474 } 475 476 static int pty_bsd_ioctl(struct tty_struct *tty, 477 unsigned int cmd, unsigned long arg) 478 { 479 switch (cmd) { 480 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 481 return pty_set_lock(tty, (int __user *) arg); 482 case TIOCGPTLCK: /* Get PT Lock status */ 483 return pty_get_lock(tty, (int __user *)arg); 484 case TIOCPKT: /* Set PT packet mode */ 485 return pty_set_pktmode(tty, (int __user *)arg); 486 case TIOCGPKT: /* Get PT packet mode */ 487 return pty_get_pktmode(tty, (int __user *)arg); 488 case TIOCSIG: /* Send signal to other side of pty */ 489 return pty_signal(tty, (int) arg); 490 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 491 return -EINVAL; 492 } 493 return -ENOIOCTLCMD; 494 } 495 496 #ifdef CONFIG_COMPAT 497 static long pty_bsd_compat_ioctl(struct tty_struct *tty, 498 unsigned int cmd, unsigned long arg) 499 { 500 /* 501 * PTY ioctls don't require any special translation between 32-bit and 502 * 64-bit userspace, they are already compatible. 503 */ 504 return pty_bsd_ioctl(tty, cmd, (unsigned long)compat_ptr(arg)); 505 } 506 #else 507 #define pty_bsd_compat_ioctl NULL 508 #endif 509 510 static int legacy_count = CONFIG_LEGACY_PTY_COUNT; 511 /* 512 * not really modular, but the easiest way to keep compat with existing 513 * bootargs behaviour is to continue using module_param here. 514 */ 515 module_param(legacy_count, int, 0); 516 517 /* 518 * The master side of a pty can do TIOCSPTLCK and thus 519 * has pty_bsd_ioctl. 520 */ 521 static const struct tty_operations master_pty_ops_bsd = { 522 .install = pty_install, 523 .open = pty_open, 524 .close = pty_close, 525 .write = pty_write, 526 .write_room = pty_write_room, 527 .flush_buffer = pty_flush_buffer, 528 .chars_in_buffer = pty_chars_in_buffer, 529 .unthrottle = pty_unthrottle, 530 .ioctl = pty_bsd_ioctl, 531 .compat_ioctl = pty_bsd_compat_ioctl, 532 .cleanup = pty_cleanup, 533 .resize = pty_resize, 534 .remove = pty_remove 535 }; 536 537 static const struct tty_operations slave_pty_ops_bsd = { 538 .install = pty_install, 539 .open = pty_open, 540 .close = pty_close, 541 .write = pty_write, 542 .write_room = pty_write_room, 543 .flush_buffer = pty_flush_buffer, 544 .chars_in_buffer = pty_chars_in_buffer, 545 .unthrottle = pty_unthrottle, 546 .set_termios = pty_set_termios, 547 .cleanup = pty_cleanup, 548 .resize = pty_resize, 549 .start = pty_start, 550 .stop = pty_stop, 551 .remove = pty_remove 552 }; 553 554 static void __init legacy_pty_init(void) 555 { 556 struct tty_driver *pty_driver, *pty_slave_driver; 557 558 if (legacy_count <= 0) 559 return; 560 561 pty_driver = tty_alloc_driver(legacy_count, 562 TTY_DRIVER_RESET_TERMIOS | 563 TTY_DRIVER_REAL_RAW | 564 TTY_DRIVER_DYNAMIC_ALLOC); 565 if (IS_ERR(pty_driver)) 566 panic("Couldn't allocate pty driver"); 567 568 pty_slave_driver = tty_alloc_driver(legacy_count, 569 TTY_DRIVER_RESET_TERMIOS | 570 TTY_DRIVER_REAL_RAW | 571 TTY_DRIVER_DYNAMIC_ALLOC); 572 if (IS_ERR(pty_slave_driver)) 573 panic("Couldn't allocate pty slave driver"); 574 575 pty_driver->driver_name = "pty_master"; 576 pty_driver->name = "pty"; 577 pty_driver->major = PTY_MASTER_MAJOR; 578 pty_driver->minor_start = 0; 579 pty_driver->type = TTY_DRIVER_TYPE_PTY; 580 pty_driver->subtype = PTY_TYPE_MASTER; 581 pty_driver->init_termios = tty_std_termios; 582 pty_driver->init_termios.c_iflag = 0; 583 pty_driver->init_termios.c_oflag = 0; 584 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 585 pty_driver->init_termios.c_lflag = 0; 586 pty_driver->init_termios.c_ispeed = 38400; 587 pty_driver->init_termios.c_ospeed = 38400; 588 pty_driver->other = pty_slave_driver; 589 tty_set_operations(pty_driver, &master_pty_ops_bsd); 590 591 pty_slave_driver->driver_name = "pty_slave"; 592 pty_slave_driver->name = "ttyp"; 593 pty_slave_driver->major = PTY_SLAVE_MAJOR; 594 pty_slave_driver->minor_start = 0; 595 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; 596 pty_slave_driver->subtype = PTY_TYPE_SLAVE; 597 pty_slave_driver->init_termios = tty_std_termios; 598 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 599 pty_slave_driver->init_termios.c_ispeed = 38400; 600 pty_slave_driver->init_termios.c_ospeed = 38400; 601 pty_slave_driver->other = pty_driver; 602 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd); 603 604 if (tty_register_driver(pty_driver)) 605 panic("Couldn't register pty driver"); 606 if (tty_register_driver(pty_slave_driver)) 607 panic("Couldn't register pty slave driver"); 608 } 609 #else 610 static inline void legacy_pty_init(void) { } 611 #endif 612 613 /* Unix98 devices */ 614 #ifdef CONFIG_UNIX98_PTYS 615 static struct cdev ptmx_cdev; 616 617 /** 618 * ptm_open_peer - open the peer of a pty 619 * @master: the open struct file of the ptmx device node 620 * @tty: the master of the pty being opened 621 * @flags: the flags for open 622 * 623 * Provide a race free way for userspace to open the slave end of a pty 624 * (where they have the master fd and cannot access or trust the mount 625 * namespace /dev/pts was mounted inside). 626 */ 627 int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags) 628 { 629 int fd = -1; 630 struct file *filp; 631 int retval = -EINVAL; 632 struct path path; 633 634 if (tty->driver != ptm_driver) 635 return -EIO; 636 637 fd = get_unused_fd_flags(flags); 638 if (fd < 0) { 639 retval = fd; 640 goto err; 641 } 642 643 /* Compute the slave's path */ 644 path.mnt = devpts_mntget(master, tty->driver_data); 645 if (IS_ERR(path.mnt)) { 646 retval = PTR_ERR(path.mnt); 647 goto err_put; 648 } 649 path.dentry = tty->link->driver_data; 650 651 filp = dentry_open(&path, flags, current_cred()); 652 mntput(path.mnt); 653 if (IS_ERR(filp)) { 654 retval = PTR_ERR(filp); 655 goto err_put; 656 } 657 658 fd_install(fd, filp); 659 return fd; 660 661 err_put: 662 put_unused_fd(fd); 663 err: 664 return retval; 665 } 666 667 static int pty_unix98_ioctl(struct tty_struct *tty, 668 unsigned int cmd, unsigned long arg) 669 { 670 switch (cmd) { 671 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 672 return pty_set_lock(tty, (int __user *)arg); 673 case TIOCGPTLCK: /* Get PT Lock status */ 674 return pty_get_lock(tty, (int __user *)arg); 675 case TIOCPKT: /* Set PT packet mode */ 676 return pty_set_pktmode(tty, (int __user *)arg); 677 case TIOCGPKT: /* Get PT packet mode */ 678 return pty_get_pktmode(tty, (int __user *)arg); 679 case TIOCGPTN: /* Get PT Number */ 680 return put_user(tty->index, (unsigned int __user *)arg); 681 case TIOCSIG: /* Send signal to other side of pty */ 682 return pty_signal(tty, (int) arg); 683 } 684 685 return -ENOIOCTLCMD; 686 } 687 688 #ifdef CONFIG_COMPAT 689 static long pty_unix98_compat_ioctl(struct tty_struct *tty, 690 unsigned int cmd, unsigned long arg) 691 { 692 /* 693 * PTY ioctls don't require any special translation between 32-bit and 694 * 64-bit userspace, they are already compatible. 695 */ 696 return pty_unix98_ioctl(tty, cmd, 697 cmd == TIOCSIG ? arg : (unsigned long)compat_ptr(arg)); 698 } 699 #else 700 #define pty_unix98_compat_ioctl NULL 701 #endif 702 703 /** 704 * ptm_unix98_lookup - find a pty master 705 * @driver: ptm driver 706 * @file: unused 707 * @idx: tty index 708 * 709 * Look up a pty master device. Called under the tty_mutex for now. 710 * This provides our locking. 711 */ 712 713 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, 714 struct file *file, int idx) 715 { 716 /* Master must be open via /dev/ptmx */ 717 return ERR_PTR(-EIO); 718 } 719 720 /** 721 * pts_unix98_lookup - find a pty slave 722 * @driver: pts driver 723 * @file: file pointer to tty 724 * @idx: tty index 725 * 726 * Look up a pty master device. Called under the tty_mutex for now. 727 * This provides our locking for the tty pointer. 728 */ 729 730 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, 731 struct file *file, int idx) 732 { 733 struct tty_struct *tty; 734 735 mutex_lock(&devpts_mutex); 736 tty = devpts_get_priv(file->f_path.dentry); 737 mutex_unlock(&devpts_mutex); 738 /* Master must be open before slave */ 739 if (!tty) 740 return ERR_PTR(-EIO); 741 return tty; 742 } 743 744 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 745 { 746 return pty_common_install(driver, tty, false); 747 } 748 749 /* this is called once with whichever end is closed last */ 750 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 751 { 752 struct pts_fs_info *fsi; 753 754 if (tty->driver->subtype == PTY_TYPE_MASTER) 755 fsi = tty->driver_data; 756 else 757 fsi = tty->link->driver_data; 758 759 if (fsi) { 760 devpts_kill_index(fsi, tty->index); 761 devpts_release(fsi); 762 } 763 } 764 765 static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m) 766 { 767 seq_printf(m, "tty-index:\t%d\n", tty->index); 768 } 769 770 static const struct tty_operations ptm_unix98_ops = { 771 .lookup = ptm_unix98_lookup, 772 .install = pty_unix98_install, 773 .remove = pty_unix98_remove, 774 .open = pty_open, 775 .close = pty_close, 776 .write = pty_write, 777 .write_room = pty_write_room, 778 .flush_buffer = pty_flush_buffer, 779 .chars_in_buffer = pty_chars_in_buffer, 780 .unthrottle = pty_unthrottle, 781 .ioctl = pty_unix98_ioctl, 782 .compat_ioctl = pty_unix98_compat_ioctl, 783 .resize = pty_resize, 784 .cleanup = pty_cleanup, 785 .show_fdinfo = pty_show_fdinfo, 786 }; 787 788 static const struct tty_operations pty_unix98_ops = { 789 .lookup = pts_unix98_lookup, 790 .install = pty_unix98_install, 791 .remove = pty_unix98_remove, 792 .open = pty_open, 793 .close = pty_close, 794 .write = pty_write, 795 .write_room = pty_write_room, 796 .flush_buffer = pty_flush_buffer, 797 .chars_in_buffer = pty_chars_in_buffer, 798 .unthrottle = pty_unthrottle, 799 .set_termios = pty_set_termios, 800 .start = pty_start, 801 .stop = pty_stop, 802 .cleanup = pty_cleanup, 803 }; 804 805 /** 806 * ptmx_open - open a unix 98 pty master 807 * @inode: inode of device file 808 * @filp: file pointer to tty 809 * 810 * Allocate a unix98 pty master device from the ptmx driver. 811 * 812 * Locking: tty_mutex protects the init_dev work. tty->count should 813 * protect the rest. 814 * allocated_ptys_lock handles the list of free pty numbers 815 */ 816 817 static int ptmx_open(struct inode *inode, struct file *filp) 818 { 819 struct pts_fs_info *fsi; 820 struct tty_struct *tty; 821 struct dentry *dentry; 822 int retval; 823 int index; 824 825 nonseekable_open(inode, filp); 826 827 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 828 filp->f_mode |= FMODE_NONOTIFY; 829 830 retval = tty_alloc_file(filp); 831 if (retval) 832 return retval; 833 834 fsi = devpts_acquire(filp); 835 if (IS_ERR(fsi)) { 836 retval = PTR_ERR(fsi); 837 goto out_free_file; 838 } 839 840 /* find a device that is not in use. */ 841 mutex_lock(&devpts_mutex); 842 index = devpts_new_index(fsi); 843 mutex_unlock(&devpts_mutex); 844 845 retval = index; 846 if (index < 0) 847 goto out_put_fsi; 848 849 850 mutex_lock(&tty_mutex); 851 tty = tty_init_dev(ptm_driver, index); 852 /* The tty returned here is locked so we can safely 853 drop the mutex */ 854 mutex_unlock(&tty_mutex); 855 856 retval = PTR_ERR(tty); 857 if (IS_ERR(tty)) 858 goto out; 859 860 /* 861 * From here on out, the tty is "live", and the index and 862 * fsi will be killed/put by the tty_release() 863 */ 864 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 865 tty->driver_data = fsi; 866 867 tty_add_file(tty, filp); 868 869 dentry = devpts_pty_new(fsi, index, tty->link); 870 if (IS_ERR(dentry)) { 871 retval = PTR_ERR(dentry); 872 goto err_release; 873 } 874 tty->link->driver_data = dentry; 875 876 retval = ptm_driver->ops->open(tty, filp); 877 if (retval) 878 goto err_release; 879 880 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); 881 882 tty_unlock(tty); 883 return 0; 884 err_release: 885 tty_unlock(tty); 886 // This will also put-ref the fsi 887 tty_release(inode, filp); 888 return retval; 889 out: 890 devpts_kill_index(fsi, index); 891 out_put_fsi: 892 devpts_release(fsi); 893 out_free_file: 894 tty_free_file(filp); 895 return retval; 896 } 897 898 static struct file_operations ptmx_fops __ro_after_init; 899 900 static void __init unix98_pty_init(void) 901 { 902 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 903 TTY_DRIVER_RESET_TERMIOS | 904 TTY_DRIVER_REAL_RAW | 905 TTY_DRIVER_DYNAMIC_DEV | 906 TTY_DRIVER_DEVPTS_MEM | 907 TTY_DRIVER_DYNAMIC_ALLOC); 908 if (IS_ERR(ptm_driver)) 909 panic("Couldn't allocate Unix98 ptm driver"); 910 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 911 TTY_DRIVER_RESET_TERMIOS | 912 TTY_DRIVER_REAL_RAW | 913 TTY_DRIVER_DYNAMIC_DEV | 914 TTY_DRIVER_DEVPTS_MEM | 915 TTY_DRIVER_DYNAMIC_ALLOC); 916 if (IS_ERR(pts_driver)) 917 panic("Couldn't allocate Unix98 pts driver"); 918 919 ptm_driver->driver_name = "pty_master"; 920 ptm_driver->name = "ptm"; 921 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 922 ptm_driver->minor_start = 0; 923 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 924 ptm_driver->subtype = PTY_TYPE_MASTER; 925 ptm_driver->init_termios = tty_std_termios; 926 ptm_driver->init_termios.c_iflag = 0; 927 ptm_driver->init_termios.c_oflag = 0; 928 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 929 ptm_driver->init_termios.c_lflag = 0; 930 ptm_driver->init_termios.c_ispeed = 38400; 931 ptm_driver->init_termios.c_ospeed = 38400; 932 ptm_driver->other = pts_driver; 933 tty_set_operations(ptm_driver, &ptm_unix98_ops); 934 935 pts_driver->driver_name = "pty_slave"; 936 pts_driver->name = "pts"; 937 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 938 pts_driver->minor_start = 0; 939 pts_driver->type = TTY_DRIVER_TYPE_PTY; 940 pts_driver->subtype = PTY_TYPE_SLAVE; 941 pts_driver->init_termios = tty_std_termios; 942 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 943 pts_driver->init_termios.c_ispeed = 38400; 944 pts_driver->init_termios.c_ospeed = 38400; 945 pts_driver->other = ptm_driver; 946 tty_set_operations(pts_driver, &pty_unix98_ops); 947 948 if (tty_register_driver(ptm_driver)) 949 panic("Couldn't register Unix98 ptm driver"); 950 if (tty_register_driver(pts_driver)) 951 panic("Couldn't register Unix98 pts driver"); 952 953 /* Now create the /dev/ptmx special device */ 954 tty_default_fops(&ptmx_fops); 955 ptmx_fops.open = ptmx_open; 956 957 cdev_init(&ptmx_cdev, &ptmx_fops); 958 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 959 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 960 panic("Couldn't register /dev/ptmx driver"); 961 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 962 } 963 964 #else 965 static inline void unix98_pty_init(void) { } 966 #endif 967 968 static int __init pty_init(void) 969 { 970 legacy_pty_init(); 971 unix98_pty_init(); 972 return 0; 973 } 974 device_initcall(pty_init); 975