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 #include <linux/mount.h> 28 #include <linux/file.h> 29 #include <linux/ioctl.h> 30 31 #undef TTY_DEBUG_HANGUP 32 #ifdef TTY_DEBUG_HANGUP 33 # define tty_debug_hangup(tty, f, args...) tty_debug(tty, f, ##args) 34 #else 35 # define tty_debug_hangup(tty, f, args...) do {} while (0) 36 #endif 37 38 #ifdef CONFIG_UNIX98_PTYS 39 static struct tty_driver *ptm_driver; 40 static struct tty_driver *pts_driver; 41 static DEFINE_MUTEX(devpts_mutex); 42 #endif 43 44 static void pty_close(struct tty_struct *tty, struct file *filp) 45 { 46 BUG_ON(!tty); 47 if (tty->driver->subtype == PTY_TYPE_MASTER) 48 WARN_ON(tty->count > 1); 49 else { 50 if (tty_io_error(tty)) 51 return; 52 if (tty->count > 2) 53 return; 54 } 55 set_bit(TTY_IO_ERROR, &tty->flags); 56 wake_up_interruptible(&tty->read_wait); 57 wake_up_interruptible(&tty->write_wait); 58 spin_lock_irq(&tty->ctrl_lock); 59 tty->packet = 0; 60 spin_unlock_irq(&tty->ctrl_lock); 61 /* Review - krefs on tty_link ?? */ 62 if (!tty->link) 63 return; 64 set_bit(TTY_OTHER_CLOSED, &tty->link->flags); 65 wake_up_interruptible(&tty->link->read_wait); 66 wake_up_interruptible(&tty->link->write_wait); 67 if (tty->driver->subtype == PTY_TYPE_MASTER) { 68 set_bit(TTY_OTHER_CLOSED, &tty->flags); 69 #ifdef CONFIG_UNIX98_PTYS 70 if (tty->driver == ptm_driver) { 71 mutex_lock(&devpts_mutex); 72 if (tty->link->driver_data) 73 devpts_pty_kill(tty->link->driver_data); 74 mutex_unlock(&devpts_mutex); 75 } 76 #endif 77 tty_vhangup(tty->link); 78 } 79 } 80 81 /* 82 * The unthrottle routine is called by the line discipline to signal 83 * that it can receive more characters. For PTY's, the TTY_THROTTLED 84 * flag is always set, to force the line discipline to always call the 85 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 86 * characters in the queue. This is necessary since each time this 87 * happens, we need to wake up any sleeping processes that could be 88 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() 89 * for the pty buffer to be drained. 90 */ 91 static void pty_unthrottle(struct tty_struct *tty) 92 { 93 tty_wakeup(tty->link); 94 set_bit(TTY_THROTTLED, &tty->flags); 95 } 96 97 /** 98 * pty_write - write to a pty 99 * @tty: the tty we write from 100 * @buf: kernel buffer of data 101 * @count: bytes to write 102 * 103 * Our "hardware" write method. Data is coming from the ldisc which 104 * may be in a non sleeping state. We simply throw this at the other 105 * end of the link as if we were an IRQ handler receiving stuff for 106 * the other side of the pty/tty pair. 107 */ 108 109 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c) 110 { 111 struct tty_struct *to = tty->link; 112 113 if (tty->stopped) 114 return 0; 115 116 if (c > 0) { 117 /* Stuff the data into the input queue of the other end */ 118 c = tty_insert_flip_string(to->port, buf, c); 119 /* And shovel */ 120 if (c) 121 tty_flip_buffer_push(to->port); 122 } 123 return c; 124 } 125 126 /** 127 * pty_write_room - write space 128 * @tty: tty we are writing from 129 * 130 * Report how many bytes the ldisc can send into the queue for 131 * the other device. 132 */ 133 134 static int pty_write_room(struct tty_struct *tty) 135 { 136 if (tty->stopped) 137 return 0; 138 return tty_buffer_space_avail(tty->link->port); 139 } 140 141 /** 142 * pty_chars_in_buffer - characters currently in our tx queue 143 * @tty: our tty 144 * 145 * Report how much we have in the transmit queue. As everything is 146 * instantly at the other end this is easy to implement. 147 */ 148 149 static int pty_chars_in_buffer(struct tty_struct *tty) 150 { 151 return 0; 152 } 153 154 /* Set the lock flag on a pty */ 155 static int pty_set_lock(struct tty_struct *tty, int __user *arg) 156 { 157 int val; 158 if (get_user(val, arg)) 159 return -EFAULT; 160 if (val) 161 set_bit(TTY_PTY_LOCK, &tty->flags); 162 else 163 clear_bit(TTY_PTY_LOCK, &tty->flags); 164 return 0; 165 } 166 167 static int pty_get_lock(struct tty_struct *tty, int __user *arg) 168 { 169 int locked = test_bit(TTY_PTY_LOCK, &tty->flags); 170 return put_user(locked, arg); 171 } 172 173 /* Set the packet mode on a pty */ 174 static int pty_set_pktmode(struct tty_struct *tty, int __user *arg) 175 { 176 int pktmode; 177 178 if (get_user(pktmode, arg)) 179 return -EFAULT; 180 181 spin_lock_irq(&tty->ctrl_lock); 182 if (pktmode) { 183 if (!tty->packet) { 184 tty->link->ctrl_status = 0; 185 smp_mb(); 186 tty->packet = 1; 187 } 188 } else 189 tty->packet = 0; 190 spin_unlock_irq(&tty->ctrl_lock); 191 192 return 0; 193 } 194 195 /* Get the packet mode of a pty */ 196 static int pty_get_pktmode(struct tty_struct *tty, int __user *arg) 197 { 198 int pktmode = tty->packet; 199 return put_user(pktmode, arg); 200 } 201 202 /* Send a signal to the slave */ 203 static int pty_signal(struct tty_struct *tty, int sig) 204 { 205 struct pid *pgrp; 206 207 if (sig != SIGINT && sig != SIGQUIT && sig != SIGTSTP) 208 return -EINVAL; 209 210 if (tty->link) { 211 pgrp = tty_get_pgrp(tty->link); 212 if (pgrp) 213 kill_pgrp(pgrp, sig, 1); 214 put_pid(pgrp); 215 } 216 return 0; 217 } 218 219 static void pty_flush_buffer(struct tty_struct *tty) 220 { 221 struct tty_struct *to = tty->link; 222 223 if (!to) 224 return; 225 226 tty_buffer_flush(to, NULL); 227 if (to->packet) { 228 spin_lock_irq(&tty->ctrl_lock); 229 tty->ctrl_status |= TIOCPKT_FLUSHWRITE; 230 wake_up_interruptible(&to->read_wait); 231 spin_unlock_irq(&tty->ctrl_lock); 232 } 233 } 234 235 static int pty_open(struct tty_struct *tty, struct file *filp) 236 { 237 if (!tty || !tty->link) 238 return -ENODEV; 239 240 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 241 goto out; 242 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 243 goto out; 244 if (tty->driver->subtype == PTY_TYPE_SLAVE && tty->link->count != 1) 245 goto out; 246 247 clear_bit(TTY_IO_ERROR, &tty->flags); 248 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 249 set_bit(TTY_THROTTLED, &tty->flags); 250 return 0; 251 252 out: 253 set_bit(TTY_IO_ERROR, &tty->flags); 254 return -EIO; 255 } 256 257 static void pty_set_termios(struct tty_struct *tty, 258 struct ktermios *old_termios) 259 { 260 /* See if packet mode change of state. */ 261 if (tty->link && tty->link->packet) { 262 int extproc = (old_termios->c_lflag & EXTPROC) | L_EXTPROC(tty); 263 int old_flow = ((old_termios->c_iflag & IXON) && 264 (old_termios->c_cc[VSTOP] == '\023') && 265 (old_termios->c_cc[VSTART] == '\021')); 266 int new_flow = (I_IXON(tty) && 267 STOP_CHAR(tty) == '\023' && 268 START_CHAR(tty) == '\021'); 269 if ((old_flow != new_flow) || extproc) { 270 spin_lock_irq(&tty->ctrl_lock); 271 if (old_flow != new_flow) { 272 tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP); 273 if (new_flow) 274 tty->ctrl_status |= TIOCPKT_DOSTOP; 275 else 276 tty->ctrl_status |= TIOCPKT_NOSTOP; 277 } 278 if (extproc) 279 tty->ctrl_status |= TIOCPKT_IOCTL; 280 spin_unlock_irq(&tty->ctrl_lock); 281 wake_up_interruptible(&tty->link->read_wait); 282 } 283 } 284 285 tty->termios.c_cflag &= ~(CSIZE | PARENB); 286 tty->termios.c_cflag |= (CS8 | CREAD); 287 } 288 289 /** 290 * pty_do_resize - resize event 291 * @tty: tty being resized 292 * @ws: window size being set. 293 * 294 * Update the termios variables and send the necessary signals to 295 * peform a terminal resize correctly 296 */ 297 298 static int pty_resize(struct tty_struct *tty, struct winsize *ws) 299 { 300 struct pid *pgrp, *rpgrp; 301 struct tty_struct *pty = tty->link; 302 303 /* For a PTY we need to lock the tty side */ 304 mutex_lock(&tty->winsize_mutex); 305 if (!memcmp(ws, &tty->winsize, sizeof(*ws))) 306 goto done; 307 308 /* Signal the foreground process group of both ptys */ 309 pgrp = tty_get_pgrp(tty); 310 rpgrp = tty_get_pgrp(pty); 311 312 if (pgrp) 313 kill_pgrp(pgrp, SIGWINCH, 1); 314 if (rpgrp != pgrp && rpgrp) 315 kill_pgrp(rpgrp, SIGWINCH, 1); 316 317 put_pid(pgrp); 318 put_pid(rpgrp); 319 320 tty->winsize = *ws; 321 pty->winsize = *ws; /* Never used so will go away soon */ 322 done: 323 mutex_unlock(&tty->winsize_mutex); 324 return 0; 325 } 326 327 /** 328 * pty_start - start() handler 329 * pty_stop - stop() handler 330 * @tty: tty being flow-controlled 331 * 332 * Propagates the TIOCPKT status to the master pty. 333 * 334 * NB: only the master pty can be in packet mode so only the slave 335 * needs start()/stop() handlers 336 */ 337 static void pty_start(struct tty_struct *tty) 338 { 339 unsigned long flags; 340 341 if (tty->link && tty->link->packet) { 342 spin_lock_irqsave(&tty->ctrl_lock, flags); 343 tty->ctrl_status &= ~TIOCPKT_STOP; 344 tty->ctrl_status |= TIOCPKT_START; 345 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 346 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 347 } 348 } 349 350 static void pty_stop(struct tty_struct *tty) 351 { 352 unsigned long flags; 353 354 if (tty->link && tty->link->packet) { 355 spin_lock_irqsave(&tty->ctrl_lock, flags); 356 tty->ctrl_status &= ~TIOCPKT_START; 357 tty->ctrl_status |= TIOCPKT_STOP; 358 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 359 wake_up_interruptible_poll(&tty->link->read_wait, POLLIN); 360 } 361 } 362 363 /** 364 * pty_common_install - set up the pty pair 365 * @driver: the pty driver 366 * @tty: the tty being instantiated 367 * @legacy: true if this is BSD style 368 * 369 * Perform the initial set up for the tty/pty pair. Called from the 370 * tty layer when the port is first opened. 371 * 372 * Locking: the caller must hold the tty_mutex 373 */ 374 static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty, 375 bool legacy) 376 { 377 struct tty_struct *o_tty; 378 struct tty_port *ports[2]; 379 int idx = tty->index; 380 int retval = -ENOMEM; 381 382 /* Opening the slave first has always returned -EIO */ 383 if (driver->subtype != PTY_TYPE_MASTER) 384 return -EIO; 385 386 ports[0] = kmalloc(sizeof **ports, GFP_KERNEL); 387 ports[1] = kmalloc(sizeof **ports, GFP_KERNEL); 388 if (!ports[0] || !ports[1]) 389 goto err; 390 if (!try_module_get(driver->other->owner)) { 391 /* This cannot in fact currently happen */ 392 goto err; 393 } 394 o_tty = alloc_tty_struct(driver->other, idx); 395 if (!o_tty) 396 goto err_put_module; 397 398 tty_set_lock_subclass(o_tty); 399 lockdep_set_subclass(&o_tty->termios_rwsem, TTY_LOCK_SLAVE); 400 401 if (legacy) { 402 /* We always use new tty termios data so we can do this 403 the easy way .. */ 404 tty_init_termios(tty); 405 tty_init_termios(o_tty); 406 407 driver->other->ttys[idx] = o_tty; 408 driver->ttys[idx] = tty; 409 } else { 410 memset(&tty->termios_locked, 0, sizeof(tty->termios_locked)); 411 tty->termios = driver->init_termios; 412 memset(&o_tty->termios_locked, 0, sizeof(tty->termios_locked)); 413 o_tty->termios = driver->other->init_termios; 414 } 415 416 /* 417 * Everything allocated ... set up the o_tty structure. 418 */ 419 tty_driver_kref_get(driver->other); 420 /* Establish the links in both directions */ 421 tty->link = o_tty; 422 o_tty->link = tty; 423 tty_port_init(ports[0]); 424 tty_port_init(ports[1]); 425 tty_buffer_set_limit(ports[0], 8192); 426 tty_buffer_set_limit(ports[1], 8192); 427 o_tty->port = ports[0]; 428 tty->port = ports[1]; 429 o_tty->port->itty = o_tty; 430 431 tty_buffer_set_lock_subclass(o_tty->port); 432 433 tty_driver_kref_get(driver); 434 tty->count++; 435 o_tty->count++; 436 return 0; 437 438 err_put_module: 439 module_put(driver->other->owner); 440 err: 441 kfree(ports[0]); 442 kfree(ports[1]); 443 return retval; 444 } 445 446 static void pty_cleanup(struct tty_struct *tty) 447 { 448 tty_port_put(tty->port); 449 } 450 451 /* Traditional BSD devices */ 452 #ifdef CONFIG_LEGACY_PTYS 453 454 static int pty_install(struct tty_driver *driver, struct tty_struct *tty) 455 { 456 return pty_common_install(driver, tty, true); 457 } 458 459 static void pty_remove(struct tty_driver *driver, struct tty_struct *tty) 460 { 461 struct tty_struct *pair = tty->link; 462 driver->ttys[tty->index] = NULL; 463 if (pair) 464 pair->driver->ttys[pair->index] = NULL; 465 } 466 467 static int pty_bsd_ioctl(struct tty_struct *tty, 468 unsigned int cmd, unsigned long arg) 469 { 470 switch (cmd) { 471 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 472 return pty_set_lock(tty, (int __user *) arg); 473 case TIOCGPTLCK: /* Get PT Lock status */ 474 return pty_get_lock(tty, (int __user *)arg); 475 case TIOCPKT: /* Set PT packet mode */ 476 return pty_set_pktmode(tty, (int __user *)arg); 477 case TIOCGPKT: /* Get PT packet mode */ 478 return pty_get_pktmode(tty, (int __user *)arg); 479 case TIOCSIG: /* Send signal to other side of pty */ 480 return pty_signal(tty, (int) arg); 481 case TIOCGPTN: /* TTY returns ENOTTY, but glibc expects EINVAL here */ 482 return -EINVAL; 483 } 484 return -ENOIOCTLCMD; 485 } 486 487 static long pty_bsd_compat_ioctl(struct tty_struct *tty, 488 unsigned int cmd, unsigned long arg) 489 { 490 /* 491 * PTY ioctls don't require any special translation between 32-bit and 492 * 64-bit userspace, they are already compatible. 493 */ 494 return pty_bsd_ioctl(tty, cmd, arg); 495 } 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 .chars_in_buffer = pty_chars_in_buffer, 516 .unthrottle = pty_unthrottle, 517 .ioctl = pty_bsd_ioctl, 518 .compat_ioctl = pty_bsd_compat_ioctl, 519 .cleanup = pty_cleanup, 520 .resize = pty_resize, 521 .remove = pty_remove 522 }; 523 524 static const struct tty_operations slave_pty_ops_bsd = { 525 .install = pty_install, 526 .open = pty_open, 527 .close = pty_close, 528 .write = pty_write, 529 .write_room = pty_write_room, 530 .flush_buffer = pty_flush_buffer, 531 .chars_in_buffer = pty_chars_in_buffer, 532 .unthrottle = pty_unthrottle, 533 .set_termios = pty_set_termios, 534 .cleanup = pty_cleanup, 535 .resize = pty_resize, 536 .start = pty_start, 537 .stop = pty_stop, 538 .remove = pty_remove 539 }; 540 541 static void __init legacy_pty_init(void) 542 { 543 struct tty_driver *pty_driver, *pty_slave_driver; 544 545 if (legacy_count <= 0) 546 return; 547 548 pty_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_driver)) 553 panic("Couldn't allocate pty driver"); 554 555 pty_slave_driver = tty_alloc_driver(legacy_count, 556 TTY_DRIVER_RESET_TERMIOS | 557 TTY_DRIVER_REAL_RAW | 558 TTY_DRIVER_DYNAMIC_ALLOC); 559 if (IS_ERR(pty_slave_driver)) 560 panic("Couldn't allocate pty slave driver"); 561 562 pty_driver->driver_name = "pty_master"; 563 pty_driver->name = "pty"; 564 pty_driver->major = PTY_MASTER_MAJOR; 565 pty_driver->minor_start = 0; 566 pty_driver->type = TTY_DRIVER_TYPE_PTY; 567 pty_driver->subtype = PTY_TYPE_MASTER; 568 pty_driver->init_termios = tty_std_termios; 569 pty_driver->init_termios.c_iflag = 0; 570 pty_driver->init_termios.c_oflag = 0; 571 pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 572 pty_driver->init_termios.c_lflag = 0; 573 pty_driver->init_termios.c_ispeed = 38400; 574 pty_driver->init_termios.c_ospeed = 38400; 575 pty_driver->other = pty_slave_driver; 576 tty_set_operations(pty_driver, &master_pty_ops_bsd); 577 578 pty_slave_driver->driver_name = "pty_slave"; 579 pty_slave_driver->name = "ttyp"; 580 pty_slave_driver->major = PTY_SLAVE_MAJOR; 581 pty_slave_driver->minor_start = 0; 582 pty_slave_driver->type = TTY_DRIVER_TYPE_PTY; 583 pty_slave_driver->subtype = PTY_TYPE_SLAVE; 584 pty_slave_driver->init_termios = tty_std_termios; 585 pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 586 pty_slave_driver->init_termios.c_ispeed = 38400; 587 pty_slave_driver->init_termios.c_ospeed = 38400; 588 pty_slave_driver->other = pty_driver; 589 tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd); 590 591 if (tty_register_driver(pty_driver)) 592 panic("Couldn't register pty driver"); 593 if (tty_register_driver(pty_slave_driver)) 594 panic("Couldn't register pty slave driver"); 595 } 596 #else 597 static inline void legacy_pty_init(void) { } 598 #endif 599 600 /* Unix98 devices */ 601 #ifdef CONFIG_UNIX98_PTYS 602 static struct cdev ptmx_cdev; 603 604 /** 605 * ptm_open_peer - open the peer of a pty 606 * @master: the open struct file of the ptmx device node 607 * @tty: the master of the pty being opened 608 * @flags: the flags for open 609 * 610 * Provide a race free way for userspace to open the slave end of a pty 611 * (where they have the master fd and cannot access or trust the mount 612 * namespace /dev/pts was mounted inside). 613 */ 614 int ptm_open_peer(struct file *master, struct tty_struct *tty, int flags) 615 { 616 int fd = -1; 617 struct file *filp; 618 int retval = -EINVAL; 619 struct path path; 620 621 if (tty->driver != ptm_driver) 622 return -EIO; 623 624 fd = get_unused_fd_flags(0); 625 if (fd < 0) { 626 retval = fd; 627 goto err; 628 } 629 630 /* Compute the slave's path */ 631 path.mnt = devpts_mntget(master, tty->driver_data); 632 if (IS_ERR(path.mnt)) { 633 retval = PTR_ERR(path.mnt); 634 goto err_put; 635 } 636 path.dentry = tty->link->driver_data; 637 638 filp = dentry_open(&path, flags, current_cred()); 639 mntput(path.mnt); 640 if (IS_ERR(filp)) { 641 retval = PTR_ERR(filp); 642 goto err_put; 643 } 644 645 fd_install(fd, filp); 646 return fd; 647 648 err_put: 649 put_unused_fd(fd); 650 err: 651 return retval; 652 } 653 654 static int pty_unix98_ioctl(struct tty_struct *tty, 655 unsigned int cmd, unsigned long arg) 656 { 657 switch (cmd) { 658 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 659 return pty_set_lock(tty, (int __user *)arg); 660 case TIOCGPTLCK: /* Get PT Lock status */ 661 return pty_get_lock(tty, (int __user *)arg); 662 case TIOCPKT: /* Set PT packet mode */ 663 return pty_set_pktmode(tty, (int __user *)arg); 664 case TIOCGPKT: /* Get PT packet mode */ 665 return pty_get_pktmode(tty, (int __user *)arg); 666 case TIOCGPTN: /* Get PT Number */ 667 return put_user(tty->index, (unsigned int __user *)arg); 668 case TIOCSIG: /* Send signal to other side of pty */ 669 return pty_signal(tty, (int) arg); 670 } 671 672 return -ENOIOCTLCMD; 673 } 674 675 static long pty_unix98_compat_ioctl(struct tty_struct *tty, 676 unsigned int cmd, unsigned long arg) 677 { 678 /* 679 * PTY ioctls don't require any special translation between 32-bit and 680 * 64-bit userspace, they are already compatible. 681 */ 682 return pty_unix98_ioctl(tty, cmd, arg); 683 } 684 685 /** 686 * ptm_unix98_lookup - find a pty master 687 * @driver: ptm driver 688 * @idx: tty index 689 * 690 * Look up a pty master device. Called under the tty_mutex for now. 691 * This provides our locking. 692 */ 693 694 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver, 695 struct file *file, int idx) 696 { 697 /* Master must be open via /dev/ptmx */ 698 return ERR_PTR(-EIO); 699 } 700 701 /** 702 * pts_unix98_lookup - find a pty slave 703 * @driver: pts driver 704 * @idx: tty index 705 * 706 * Look up a pty master device. Called under the tty_mutex for now. 707 * This provides our locking for the tty pointer. 708 */ 709 710 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver, 711 struct file *file, int idx) 712 { 713 struct tty_struct *tty; 714 715 mutex_lock(&devpts_mutex); 716 tty = devpts_get_priv(file->f_path.dentry); 717 mutex_unlock(&devpts_mutex); 718 /* Master must be open before slave */ 719 if (!tty) 720 return ERR_PTR(-EIO); 721 return tty; 722 } 723 724 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty) 725 { 726 return pty_common_install(driver, tty, false); 727 } 728 729 /* this is called once with whichever end is closed last */ 730 static void pty_unix98_remove(struct tty_driver *driver, struct tty_struct *tty) 731 { 732 struct pts_fs_info *fsi; 733 734 if (tty->driver->subtype == PTY_TYPE_MASTER) 735 fsi = tty->driver_data; 736 else 737 fsi = tty->link->driver_data; 738 739 if (fsi) { 740 devpts_kill_index(fsi, tty->index); 741 devpts_release(fsi); 742 } 743 } 744 745 static void pty_show_fdinfo(struct tty_struct *tty, struct seq_file *m) 746 { 747 seq_printf(m, "tty-index:\t%d\n", tty->index); 748 } 749 750 static const struct tty_operations ptm_unix98_ops = { 751 .lookup = ptm_unix98_lookup, 752 .install = pty_unix98_install, 753 .remove = pty_unix98_remove, 754 .open = pty_open, 755 .close = pty_close, 756 .write = pty_write, 757 .write_room = pty_write_room, 758 .flush_buffer = pty_flush_buffer, 759 .chars_in_buffer = pty_chars_in_buffer, 760 .unthrottle = pty_unthrottle, 761 .ioctl = pty_unix98_ioctl, 762 .compat_ioctl = pty_unix98_compat_ioctl, 763 .resize = pty_resize, 764 .cleanup = pty_cleanup, 765 .show_fdinfo = pty_show_fdinfo, 766 }; 767 768 static const struct tty_operations pty_unix98_ops = { 769 .lookup = pts_unix98_lookup, 770 .install = pty_unix98_install, 771 .remove = pty_unix98_remove, 772 .open = pty_open, 773 .close = pty_close, 774 .write = pty_write, 775 .write_room = pty_write_room, 776 .flush_buffer = pty_flush_buffer, 777 .chars_in_buffer = pty_chars_in_buffer, 778 .unthrottle = pty_unthrottle, 779 .set_termios = pty_set_termios, 780 .start = pty_start, 781 .stop = pty_stop, 782 .cleanup = pty_cleanup, 783 }; 784 785 /** 786 * ptmx_open - open a unix 98 pty master 787 * @inode: inode of device file 788 * @filp: file pointer to tty 789 * 790 * Allocate a unix98 pty master device from the ptmx driver. 791 * 792 * Locking: tty_mutex protects the init_dev work. tty->count should 793 * protect the rest. 794 * allocated_ptys_lock handles the list of free pty numbers 795 */ 796 797 static int ptmx_open(struct inode *inode, struct file *filp) 798 { 799 struct pts_fs_info *fsi; 800 struct tty_struct *tty; 801 struct dentry *dentry; 802 int retval; 803 int index; 804 805 nonseekable_open(inode, filp); 806 807 /* We refuse fsnotify events on ptmx, since it's a shared resource */ 808 filp->f_mode |= FMODE_NONOTIFY; 809 810 retval = tty_alloc_file(filp); 811 if (retval) 812 return retval; 813 814 fsi = devpts_acquire(filp); 815 if (IS_ERR(fsi)) { 816 retval = PTR_ERR(fsi); 817 goto out_free_file; 818 } 819 820 /* find a device that is not in use. */ 821 mutex_lock(&devpts_mutex); 822 index = devpts_new_index(fsi); 823 mutex_unlock(&devpts_mutex); 824 825 retval = index; 826 if (index < 0) 827 goto out_put_fsi; 828 829 830 mutex_lock(&tty_mutex); 831 tty = tty_init_dev(ptm_driver, index); 832 /* The tty returned here is locked so we can safely 833 drop the mutex */ 834 mutex_unlock(&tty_mutex); 835 836 retval = PTR_ERR(tty); 837 if (IS_ERR(tty)) 838 goto out; 839 840 /* 841 * From here on out, the tty is "live", and the index and 842 * fsi will be killed/put by the tty_release() 843 */ 844 set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */ 845 tty->driver_data = fsi; 846 847 tty_add_file(tty, filp); 848 849 dentry = devpts_pty_new(fsi, index, tty->link); 850 if (IS_ERR(dentry)) { 851 retval = PTR_ERR(dentry); 852 goto err_release; 853 } 854 tty->link->driver_data = dentry; 855 856 retval = ptm_driver->ops->open(tty, filp); 857 if (retval) 858 goto err_release; 859 860 tty_debug_hangup(tty, "opening (count=%d)\n", tty->count); 861 862 tty_unlock(tty); 863 return 0; 864 err_release: 865 tty_unlock(tty); 866 // This will also put-ref the fsi 867 tty_release(inode, filp); 868 return retval; 869 out: 870 devpts_kill_index(fsi, index); 871 out_put_fsi: 872 devpts_release(fsi); 873 out_free_file: 874 tty_free_file(filp); 875 return retval; 876 } 877 878 static struct file_operations ptmx_fops __ro_after_init; 879 880 static void __init unix98_pty_init(void) 881 { 882 ptm_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 883 TTY_DRIVER_RESET_TERMIOS | 884 TTY_DRIVER_REAL_RAW | 885 TTY_DRIVER_DYNAMIC_DEV | 886 TTY_DRIVER_DEVPTS_MEM | 887 TTY_DRIVER_DYNAMIC_ALLOC); 888 if (IS_ERR(ptm_driver)) 889 panic("Couldn't allocate Unix98 ptm driver"); 890 pts_driver = tty_alloc_driver(NR_UNIX98_PTY_MAX, 891 TTY_DRIVER_RESET_TERMIOS | 892 TTY_DRIVER_REAL_RAW | 893 TTY_DRIVER_DYNAMIC_DEV | 894 TTY_DRIVER_DEVPTS_MEM | 895 TTY_DRIVER_DYNAMIC_ALLOC); 896 if (IS_ERR(pts_driver)) 897 panic("Couldn't allocate Unix98 pts driver"); 898 899 ptm_driver->driver_name = "pty_master"; 900 ptm_driver->name = "ptm"; 901 ptm_driver->major = UNIX98_PTY_MASTER_MAJOR; 902 ptm_driver->minor_start = 0; 903 ptm_driver->type = TTY_DRIVER_TYPE_PTY; 904 ptm_driver->subtype = PTY_TYPE_MASTER; 905 ptm_driver->init_termios = tty_std_termios; 906 ptm_driver->init_termios.c_iflag = 0; 907 ptm_driver->init_termios.c_oflag = 0; 908 ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 909 ptm_driver->init_termios.c_lflag = 0; 910 ptm_driver->init_termios.c_ispeed = 38400; 911 ptm_driver->init_termios.c_ospeed = 38400; 912 ptm_driver->other = pts_driver; 913 tty_set_operations(ptm_driver, &ptm_unix98_ops); 914 915 pts_driver->driver_name = "pty_slave"; 916 pts_driver->name = "pts"; 917 pts_driver->major = UNIX98_PTY_SLAVE_MAJOR; 918 pts_driver->minor_start = 0; 919 pts_driver->type = TTY_DRIVER_TYPE_PTY; 920 pts_driver->subtype = PTY_TYPE_SLAVE; 921 pts_driver->init_termios = tty_std_termios; 922 pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD; 923 pts_driver->init_termios.c_ispeed = 38400; 924 pts_driver->init_termios.c_ospeed = 38400; 925 pts_driver->other = ptm_driver; 926 tty_set_operations(pts_driver, &pty_unix98_ops); 927 928 if (tty_register_driver(ptm_driver)) 929 panic("Couldn't register Unix98 ptm driver"); 930 if (tty_register_driver(pts_driver)) 931 panic("Couldn't register Unix98 pts driver"); 932 933 /* Now create the /dev/ptmx special device */ 934 tty_default_fops(&ptmx_fops); 935 ptmx_fops.open = ptmx_open; 936 937 cdev_init(&ptmx_cdev, &ptmx_fops); 938 if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) || 939 register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0) 940 panic("Couldn't register /dev/ptmx driver"); 941 device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx"); 942 } 943 944 #else 945 static inline void unix98_pty_init(void) { } 946 #endif 947 948 static int __init pty_init(void) 949 { 950 legacy_pty_init(); 951 unix98_pty_init(); 952 return 0; 953 } 954 device_initcall(pty_init); 955