drivers/input/evdev.c

   1 /*
   2  * Event char devices, giving access to raw input device events.
   3  *
   4  * Copyright (c) 1999-2002 Vojtech Pavlik
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #define EVDEV_MINOR_BASE        64
  14 #define EVDEV_MINORS            32
  15 #define EVDEV_MIN_BUFFER_SIZE   64U
  16 #define EVDEV_BUF_PACKETS       8
  17
  18 #include <linux/poll.h>
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <linux/vmalloc.h>
  22 #include <linux/mm.h>
  23 #include <linux/module.h>
  24 #include <linux/init.h>
  25 #include <linux/input/mt.h>
  26 #include <linux/major.h>
  27 #include <linux/device.h>
  28 #include <linux/cdev.h>
  29 #include "input-compat.h"
  30
  31 enum evdev_clock_type {
  32         EV_CLK_REAL = 0,
  33         EV_CLK_MONO,
  34         EV_CLK_BOOT,
  35         EV_CLK_MAX
  36 };
  37
  38 struct evdev {
  39         int open;
  40         struct input_handle handle;
  41         wait_queue_head_t wait;
  42         struct evdev_client __rcu *grab;
  43         struct list_head client_list;
  44         spinlock_t client_lock; /* protects client_list */
  45         struct mutex mutex;
  46         struct device dev;
  47         struct cdev cdev;
  48         bool exist;
  49 };
  50
  51 struct evdev_client {
  52         unsigned int head;
  53         unsigned int tail;
  54         unsigned int packet_head; /* [future] position of the first element of next packet */
  55         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  56         struct fasync_struct *fasync;
  57         struct evdev *evdev;
  58         struct list_head node;
  59         int clk_type;
  60         bool revoked;
  61         unsigned int bufsize;
  62         struct input_event buffer[];
  63 };
  64
  65 static int evdev_set_clk_type(struct evdev_client *client, unsigned int clkid)
  66 {
  67         switch (clkid) {
  68
  69         case CLOCK_REALTIME:
  70                 client->clk_type = EV_CLK_REAL;
  71                 break;
  72         case CLOCK_MONOTONIC:
  73                 client->clk_type = EV_CLK_MONO;
  74                 break;
  75         case CLOCK_BOOTTIME:
  76                 client->clk_type = EV_CLK_BOOT;
  77                 break;
  78         default:
  79                 return -EINVAL;
  80         }
  81
  82         return 0;
  83 }
  84
  85 /* flush queued events of type @type, caller must hold client->buffer_lock */
  86 static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
  87 {
  88         unsigned int i, head, num;
  89         unsigned int mask = client->bufsize - 1;
  90         bool is_report;
  91         struct input_event *ev;
  92
  93         BUG_ON(type == EV_SYN);
  94
  95         head = client->tail;
  96         client->packet_head = client->tail;
  97
  98         /* init to 1 so a leading SYN_REPORT will not be dropped */
  99         num = 1;
 100
 101         for (i = client->tail; i != client->head; i = (i + 1) & mask) {
 102                 ev = &client->buffer[i];
 103                 is_report = ev->type == EV_SYN && ev->code == SYN_REPORT;
 104
 105                 if (ev->type == type) {
 106                         /* drop matched entry */
 107                         continue;
 108                 } else if (is_report && !num) {
 109                         /* drop empty SYN_REPORT groups */
 110                         continue;
 111                 } else if (head != i) {
 112                         /* move entry to fill the gap */
 113                         client->buffer[head].time = ev->time;
 114                         client->buffer[head].type = ev->type;
 115                         client->buffer[head].code = ev->code;
 116                         client->buffer[head].value = ev->value;
 117                 }
 118
 119                 num++;
 120                 head = (head + 1) & mask;
 121
 122                 if (is_report) {
 123                         num = 0;
 124                         client->packet_head = head;
 125                 }
 126         }
 127
 128         client->head = head;
 129 }
 130
 131 /* queue SYN_DROPPED event */
 132 static void evdev_queue_syn_dropped(struct evdev_client *client)
 133 {
 134         unsigned long flags;
 135         struct input_event ev;
 136         ktime_t time;
 137
 138         time = client->clk_type == EV_CLK_REAL ?
 139                         ktime_get_real() :
 140                         client->clk_type == EV_CLK_MONO ?
 141                                 ktime_get() :
 142                                 ktime_get_boottime();
 143
 144         ev.time = ktime_to_timeval(time);
 145         ev.type = EV_SYN;
 146         ev.code = SYN_DROPPED;
 147         ev.value = 0;
 148
 149         spin_lock_irqsave(&client->buffer_lock, flags);
 150
 151         client->buffer[client->head++] = ev;
 152         client->head &= client->bufsize - 1;
 153
 154         if (unlikely(client->head == client->tail)) {
 155                 /* drop queue but keep our SYN_DROPPED event */
 156                 client->tail = (client->head - 1) & (client->bufsize - 1);
 157                 client->packet_head = client->tail;
 158         }
 159
 160         spin_unlock_irqrestore(&client->buffer_lock, flags);
 161 }
 162
 163 static void __pass_event(struct evdev_client *client,
 164                          const struct input_event *event)
 165 {
 166         client->buffer[client->head++] = *event;
 167         client->head &= client->bufsize - 1;
 168
 169         if (unlikely(client->head == client->tail)) {
 170                 /*
 171                  * This effectively "drops" all unconsumed events, leaving
 172                  * EV_SYN/SYN_DROPPED plus the newest event in the queue.
 173                  */
 174                 client->tail = (client->head - 2) & (client->bufsize - 1);
 175
 176                 client->buffer[client->tail].time = event->time;
 177                 client->buffer[client->tail].type = EV_SYN;
 178                 client->buffer[client->tail].code = SYN_DROPPED;
 179                 client->buffer[client->tail].value = 0;
 180
 181                 client->packet_head = client->tail;
 182         }
 183
 184         if (event->type == EV_SYN && event->code == SYN_REPORT) {
 185                 client->packet_head = client->head;
 186                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
 187         }
 188 }
 189
 190 static void evdev_pass_values(struct evdev_client *client,
 191                         const struct input_value *vals, unsigned int count,
 192                         ktime_t *ev_time)
 193 {
 194         struct evdev *evdev = client->evdev;
 195         const struct input_value *v;
 196         struct input_event event;
 197         bool wakeup = false;
 198
 199         if (client->revoked)
 200                 return;
 201
 202         event.time = ktime_to_timeval(ev_time[client->clk_type]);
 203
 204         /* Interrupts are disabled, just acquire the lock. */
 205         spin_lock(&client->buffer_lock);
 206
 207         for (v = vals; v != vals + count; v++) {
 208                 event.type = v->type;
 209                 event.code = v->code;
 210                 event.value = v->value;
 211                 __pass_event(client, &event);
 212                 if (v->type == EV_SYN && v->code == SYN_REPORT)
 213                         wakeup = true;
 214         }
 215
 216         spin_unlock(&client->buffer_lock);
 217
 218         if (wakeup)
 219                 wake_up_interruptible(&evdev->wait);
 220 }
 221
 222 /*
 223  * Pass incoming events to all connected clients.
 224  */
 225 static void evdev_events(struct input_handle *handle,
 226                          const struct input_value *vals, unsigned int count)
 227 {
 228         struct evdev *evdev = handle->private;
 229         struct evdev_client *client;
 230         ktime_t ev_time[EV_CLK_MAX];
 231
 232         ev_time[EV_CLK_MONO] = ktime_get();
 233         ev_time[EV_CLK_REAL] = ktime_mono_to_real(ev_time[EV_CLK_MONO]);
 234         ev_time[EV_CLK_BOOT] = ktime_mono_to_any(ev_time[EV_CLK_MONO],
 235                                                  TK_OFFS_BOOT);
 236
 237         rcu_read_lock();
 238
 239         client = rcu_dereference(evdev->grab);
 240
 241         if (client)
 242                 evdev_pass_values(client, vals, count, ev_time);
 243         else
 244                 list_for_each_entry_rcu(client, &evdev->client_list, node)
 245                         evdev_pass_values(client, vals, count, ev_time);
 246
 247         rcu_read_unlock();
 248 }
 249
 250 /*
 251  * Pass incoming event to all connected clients.
 252  */
 253 static void evdev_event(struct input_handle *handle,
 254                         unsigned int type, unsigned int code, int value)
 255 {
 256         struct input_value vals[] = { { type, code, value } };
 257
 258         evdev_events(handle, vals, 1);
 259 }
 260
 261 static int evdev_fasync(int fd, struct file *file, int on)
 262 {
 263         struct evdev_client *client = file->private_data;
 264
 265         return fasync_helper(fd, file, on, &client->fasync);
 266 }
 267
 268 static int evdev_flush(struct file *file, fl_owner_t id)
 269 {
 270         struct evdev_client *client = file->private_data;
 271         struct evdev *evdev = client->evdev;
 272         int retval;
 273
 274         retval = mutex_lock_interruptible(&evdev->mutex);
 275         if (retval)
 276                 return retval;
 277
 278         if (!evdev->exist || client->revoked)
 279                 retval = -ENODEV;
 280         else
 281                 retval = input_flush_device(&evdev->handle, file);
 282
 283         mutex_unlock(&evdev->mutex);
 284         return retval;
 285 }
 286
 287 static void evdev_free(struct device *dev)
 288 {
 289         struct evdev *evdev = container_of(dev, struct evdev, dev);
 290
 291         input_put_device(evdev->handle.dev);
 292         kfree(evdev);
 293 }
 294
 295 /*
 296  * Grabs an event device (along with underlying input device).
 297  * This function is called with evdev->mutex taken.
 298  */
 299 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 300 {
 301         int error;
 302
 303         if (evdev->grab)
 304                 return -EBUSY;
 305
 306         error = input_grab_device(&evdev->handle);
 307         if (error)
 308                 return error;
 309
 310         rcu_assign_pointer(evdev->grab, client);
 311
 312         return 0;
 313 }
 314
 315 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 316 {
 317         struct evdev_client *grab = rcu_dereference_protected(evdev->grab,
 318                                         lockdep_is_held(&evdev->mutex));
 319
 320         if (grab != client)
 321                 return  -EINVAL;
 322
 323         rcu_assign_pointer(evdev->grab, NULL);
 324         synchronize_rcu();
 325         input_release_device(&evdev->handle);
 326
 327         return 0;
 328 }
 329
 330 static void evdev_attach_client(struct evdev *evdev,
 331                                 struct evdev_client *client)
 332 {
 333         spin_lock(&evdev->client_lock);
 334         list_add_tail_rcu(&client->node, &evdev->client_list);
 335         spin_unlock(&evdev->client_lock);
 336 }
 337
 338 static void evdev_detach_client(struct evdev *evdev,
 339                                 struct evdev_client *client)
 340 {
 341         spin_lock(&evdev->client_lock);
 342         list_del_rcu(&client->node);
 343         spin_unlock(&evdev->client_lock);
 344         synchronize_rcu();
 345 }
 346
 347 static int evdev_open_device(struct evdev *evdev)
 348 {
 349         int retval;
 350
 351         retval = mutex_lock_interruptible(&evdev->mutex);
 352         if (retval)
 353                 return retval;
 354
 355         if (!evdev->exist)
 356                 retval = -ENODEV;
 357         else if (!evdev->open++) {
 358                 retval = input_open_device(&evdev->handle);
 359                 if (retval)
 360                         evdev->open--;
 361         }
 362
 363         mutex_unlock(&evdev->mutex);
 364         return retval;
 365 }
 366
 367 static void evdev_close_device(struct evdev *evdev)
 368 {
 369         mutex_lock(&evdev->mutex);
 370
 371         if (evdev->exist && !--evdev->open)
 372                 input_close_device(&evdev->handle);
 373
 374         mutex_unlock(&evdev->mutex);
 375 }
 376
 377 /*
 378  * Wake up users waiting for IO so they can disconnect from
 379  * dead device.
 380  */
 381 static void evdev_hangup(struct evdev *evdev)
 382 {
 383         struct evdev_client *client;
 384
 385         spin_lock(&evdev->client_lock);
 386         list_for_each_entry(client, &evdev->client_list, node)
 387                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 388         spin_unlock(&evdev->client_lock);
 389
 390         wake_up_interruptible(&evdev->wait);
 391 }
 392
 393 static int evdev_release(struct inode *inode, struct file *file)
 394 {
 395         struct evdev_client *client = file->private_data;
 396         struct evdev *evdev = client->evdev;
 397
 398         mutex_lock(&evdev->mutex);
 399         evdev_ungrab(evdev, client);
 400         mutex_unlock(&evdev->mutex);
 401
 402         evdev_detach_client(evdev, client);
 403
 404         if (is_vmalloc_addr(client))
 405                 vfree(client);
 406         else
 407                 kfree(client);
 408
 409         evdev_close_device(evdev);
 410
 411         return 0;
 412 }
 413
 414 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 415 {
 416         unsigned int n_events =
 417                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 418                     EVDEV_MIN_BUFFER_SIZE);
 419
 420         return roundup_pow_of_two(n_events);
 421 }
 422
 423 static int evdev_open(struct inode *inode, struct file *file)
 424 {
 425         struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
 426         unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 427         unsigned int size = sizeof(struct evdev_client) +
 428                                         bufsize * sizeof(struct input_event);
 429         struct evdev_client *client;
 430         int error;
 431
 432         client = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
 433         if (!client)
 434                 client = vzalloc(size);
 435         if (!client)
 436                 return -ENOMEM;
 437
 438         client->bufsize = bufsize;
 439         spin_lock_init(&client->buffer_lock);
 440         client->evdev = evdev;
 441         evdev_attach_client(evdev, client);
 442
 443         error = evdev_open_device(evdev);
 444         if (error)
 445                 goto err_free_client;
 446
 447         file->private_data = client;
 448         nonseekable_open(inode, file);
 449
 450         return 0;
 451
 452  err_free_client:
 453         evdev_detach_client(evdev, client);
 454         kvfree(client);
 455         return error;
 456 }
 457
 458 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 459                            size_t count, loff_t *ppos)
 460 {
 461         struct evdev_client *client = file->private_data;
 462         struct evdev *evdev = client->evdev;
 463         struct input_event event;
 464         int retval = 0;
 465
 466         if (count != 0 && count < input_event_size())
 467                 return -EINVAL;
 468
 469         retval = mutex_lock_interruptible(&evdev->mutex);
 470         if (retval)
 471                 return retval;
 472
 473         if (!evdev->exist || client->revoked) {
 474                 retval = -ENODEV;
 475                 goto out;
 476         }
 477
 478         while (retval + input_event_size() <= count) {
 479
 480                 if (input_event_from_user(buffer + retval, &event)) {
 481                         retval = -EFAULT;
 482                         goto out;
 483                 }
 484                 retval += input_event_size();
 485
 486                 input_inject_event(&evdev->handle,
 487                                    event.type, event.code, event.value);
 488         }
 489
 490  out:
 491         mutex_unlock(&evdev->mutex);
 492         return retval;
 493 }
 494
 495 static int evdev_fetch_next_event(struct evdev_client *client,
 496                                   struct input_event *event)
 497 {
 498         int have_event;
 499
 500         spin_lock_irq(&client->buffer_lock);
 501
 502         have_event = client->packet_head != client->tail;
 503         if (have_event) {
 504                 *event = client->buffer[client->tail++];
 505                 client->tail &= client->bufsize - 1;
 506         }
 507
 508         spin_unlock_irq(&client->buffer_lock);
 509
 510         return have_event;
 511 }
 512
 513 static ssize_t evdev_read(struct file *file, char __user *buffer,
 514                           size_t count, loff_t *ppos)
 515 {
 516         struct evdev_client *client = file->private_data;
 517         struct evdev *evdev = client->evdev;
 518         struct input_event event;
 519         size_t read = 0;
 520         int error;
 521
 522         if (count != 0 && count < input_event_size())
 523                 return -EINVAL;
 524
 525         for (;;) {
 526                 if (!evdev->exist || client->revoked)
 527                         return -ENODEV;
 528
 529                 if (client->packet_head == client->tail &&
 530                     (file->f_flags & O_NONBLOCK))
 531                         return -EAGAIN;
 532
 533                 /*
 534                  * count == 0 is special - no IO is done but we check
 535                  * for error conditions (see above).
 536                  */
 537                 if (count == 0)
 538                         break;
 539
 540                 while (read + input_event_size() <= count &&
 541                        evdev_fetch_next_event(client, &event)) {
 542
 543                         if (input_event_to_user(buffer + read, &event))
 544                                 return -EFAULT;
 545
 546                         read += input_event_size();
 547                 }
 548
 549                 if (read)
 550                         break;
 551
 552                 if (!(file->f_flags & O_NONBLOCK)) {
 553                         error = wait_event_interruptible(evdev->wait,
 554                                         client->packet_head != client->tail ||
 555                                         !evdev->exist || client->revoked);
 556                         if (error)
 557                                 return error;
 558                 }
 559         }
 560
 561         return read;
 562 }
 563
 564 /* No kernel lock - fine */
 565 static unsigned int evdev_poll(struct file *file, poll_table *wait)
 566 {
 567         struct evdev_client *client = file->private_data;
 568         struct evdev *evdev = client->evdev;
 569         unsigned int mask;
 570
 571         poll_wait(file, &evdev->wait, wait);
 572
 573         if (evdev->exist && !client->revoked)
 574                 mask = POLLOUT | POLLWRNORM;
 575         else
 576                 mask = POLLHUP | POLLERR;
 577
 578         if (client->packet_head != client->tail)
 579                 mask |= POLLIN | POLLRDNORM;
 580
 581         return mask;
 582 }
 583
 584 #ifdef CONFIG_COMPAT
 585
 586 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 587 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 588
 589 #ifdef __BIG_ENDIAN
 590 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 591                         unsigned int maxlen, void __user *p, int compat)
 592 {
 593         int len, i;
 594
 595         if (compat) {
 596                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 597                 if (len > maxlen)
 598                         len = maxlen;
 599
 600                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 601                         if (copy_to_user((compat_long_t __user *) p + i,
 602                                          (compat_long_t *) bits +
 603                                                 i + 1 - ((i % 2) << 1),
 604                                          sizeof(compat_long_t)))
 605                                 return -EFAULT;
 606         } else {
 607                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 608                 if (len > maxlen)
 609                         len = maxlen;
 610
 611                 if (copy_to_user(p, bits, len))
 612                         return -EFAULT;
 613         }
 614
 615         return len;
 616 }
 617 #else
 618 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 619                         unsigned int maxlen, void __user *p, int compat)
 620 {
 621         int len = compat ?
 622                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 623                         BITS_TO_LONGS(maxbit) * sizeof(long);
 624
 625         if (len > maxlen)
 626                 len = maxlen;
 627
 628         return copy_to_user(p, bits, len) ? -EFAULT : len;
 629 }
 630 #endif /* __BIG_ENDIAN */
 631
 632 #else
 633
 634 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 635                         unsigned int maxlen, void __user *p, int compat)
 636 {
 637         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 638
 639         if (len > maxlen)
 640                 len = maxlen;
 641
 642         return copy_to_user(p, bits, len) ? -EFAULT : len;
 643 }
 644
 645 #endif /* CONFIG_COMPAT */
 646
 647 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 648 {
 649         int len;
 650
 651         if (!str)
 652                 return -ENOENT;
 653
 654         len = strlen(str) + 1;
 655         if (len > maxlen)
 656                 len = maxlen;
 657
 658         return copy_to_user(p, str, len) ? -EFAULT : len;
 659 }
 660
 661 static int handle_eviocgbit(struct input_dev *dev,
 662                             unsigned int type, unsigned int size,
 663                             void __user *p, int compat_mode)
 664 {
 665         unsigned long *bits;
 666         int len;
 667
 668         switch (type) {
 669
 670         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 671         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 672         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 673         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 674         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 675         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 676         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 677         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 678         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 679         default: return -EINVAL;
 680         }
 681
 682         return bits_to_user(bits, len, size, p, compat_mode);
 683 }
 684
 685 static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)
 686 {
 687         struct input_keymap_entry ke = {
 688                 .len    = sizeof(unsigned int),
 689                 .flags  = 0,
 690         };
 691         int __user *ip = (int __user *)p;
 692         int error;
 693
 694         /* legacy case */
 695         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 696                 return -EFAULT;
 697
 698         error = input_get_keycode(dev, &ke);
 699         if (error)
 700                 return error;
 701
 702         if (put_user(ke.keycode, ip + 1))
 703                 return -EFAULT;
 704
 705         return 0;
 706 }
 707
 708 static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
 709 {
 710         struct input_keymap_entry ke;
 711         int error;
 712
 713         if (copy_from_user(&ke, p, sizeof(ke)))
 714                 return -EFAULT;
 715
 716         error = input_get_keycode(dev, &ke);
 717         if (error)
 718                 return error;
 719
 720         if (copy_to_user(p, &ke, sizeof(ke)))
 721                 return -EFAULT;
 722
 723         return 0;
 724 }
 725
 726 static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)
 727 {
 728         struct input_keymap_entry ke = {
 729                 .len    = sizeof(unsigned int),
 730                 .flags  = 0,
 731         };
 732         int __user *ip = (int __user *)p;
 733
 734         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 735                 return -EFAULT;
 736
 737         if (get_user(ke.keycode, ip + 1))
 738                 return -EFAULT;
 739
 740         return input_set_keycode(dev, &ke);
 741 }
 742
 743 static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 744 {
 745         struct input_keymap_entry ke;
 746
 747         if (copy_from_user(&ke, p, sizeof(ke)))
 748                 return -EFAULT;
 749
 750         if (ke.len > sizeof(ke.scancode))
 751                 return -EINVAL;
 752
 753         return input_set_keycode(dev, &ke);
 754 }
 755
 756 /*
 757  * If we transfer state to the user, we should flush all pending events
 758  * of the same type from the client's queue. Otherwise, they might end up
 759  * with duplicate events, which can screw up client's state tracking.
 760  * If bits_to_user fails after flushing the queue, we queue a SYN_DROPPED
 761  * event so user-space will notice missing events.
 762  *
 763  * LOCKING:
 764  * We need to take event_lock before buffer_lock to avoid dead-locks. But we
 765  * need the even_lock only to guarantee consistent state. We can safely release
 766  * it while flushing the queue. This allows input-core to handle filters while
 767  * we flush the queue.
 768  */
 769 static int evdev_handle_get_val(struct evdev_client *client,
 770                                 struct input_dev *dev, unsigned int type,
 771                                 unsigned long *bits, unsigned int maxbit,
 772                                 unsigned int maxlen, void __user *p,
 773                                 int compat)
 774 {
 775         int ret;
 776         unsigned long *mem;
 777         size_t len;
 778
 779         len = BITS_TO_LONGS(maxbit) * sizeof(unsigned long);
 780         mem = kmalloc(len, GFP_KERNEL);
 781         if (!mem)
 782                 return -ENOMEM;
 783
 784         spin_lock_irq(&dev->event_lock);
 785         spin_lock(&client->buffer_lock);
 786
 787         memcpy(mem, bits, len);
 788
 789         spin_unlock(&dev->event_lock);
 790
 791         __evdev_flush_queue(client, type);
 792
 793         spin_unlock_irq(&client->buffer_lock);
 794
 795         ret = bits_to_user(mem, maxbit, maxlen, p, compat);
 796         if (ret < 0)
 797                 evdev_queue_syn_dropped(client);
 798
 799         kfree(mem);
 800
 801         return ret;
 802 }
 803
 804 static int evdev_handle_mt_request(struct input_dev *dev,
 805                                    unsigned int size,
 806                                    int __user *ip)
 807 {
 808         const struct input_mt *mt = dev->mt;
 809         unsigned int code;
 810         int max_slots;
 811         int i;
 812
 813         if (get_user(code, &ip[0]))
 814                 return -EFAULT;
 815         if (!mt || !input_is_mt_value(code))
 816                 return -EINVAL;
 817
 818         max_slots = (size - sizeof(__u32)) / sizeof(__s32);
 819         for (i = 0; i < mt->num_slots && i < max_slots; i++) {
 820                 int value = input_mt_get_value(&mt->slots[i], code);
 821                 if (put_user(value, &ip[1 + i]))
 822                         return -EFAULT;
 823         }
 824
 825         return 0;
 826 }
 827
 828 static int evdev_revoke(struct evdev *evdev, struct evdev_client *client,
 829                         struct file *file)
 830 {
 831         client->revoked = true;
 832         evdev_ungrab(evdev, client);
 833         input_flush_device(&evdev->handle, file);
 834         wake_up_interruptible(&evdev->wait);
 835
 836         return 0;
 837 }
 838
 839 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 840                            void __user *p, int compat_mode)
 841 {
 842         struct evdev_client *client = file->private_data;
 843         struct evdev *evdev = client->evdev;
 844         struct input_dev *dev = evdev->handle.dev;
 845         struct input_absinfo abs;
 846         struct ff_effect effect;
 847         int __user *ip = (int __user *)p;
 848         unsigned int i, t, u, v;
 849         unsigned int size;
 850         int error;
 851
 852         /* First we check for fixed-length commands */
 853         switch (cmd) {
 854
 855         case EVIOCGVERSION:
 856                 return put_user(EV_VERSION, ip);
 857
 858         case EVIOCGID:
 859                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
 860                         return -EFAULT;
 861                 return 0;
 862
 863         case EVIOCGREP:
 864                 if (!test_bit(EV_REP, dev->evbit))
 865                         return -ENOSYS;
 866                 if (put_user(dev->rep[REP_DELAY], ip))
 867                         return -EFAULT;
 868                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
 869                         return -EFAULT;
 870                 return 0;
 871
 872         case EVIOCSREP:
 873                 if (!test_bit(EV_REP, dev->evbit))
 874                         return -ENOSYS;
 875                 if (get_user(u, ip))
 876                         return -EFAULT;
 877                 if (get_user(v, ip + 1))
 878                         return -EFAULT;
 879
 880                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
 881                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 882
 883                 return 0;
 884
 885         case EVIOCRMFF:
 886                 return input_ff_erase(dev, (int)(unsigned long) p, file);
 887
 888         case EVIOCGEFFECTS:
 889                 i = test_bit(EV_FF, dev->evbit) ?
 890                                 dev->ff->max_effects : 0;
 891                 if (put_user(i, ip))
 892                         return -EFAULT;
 893                 return 0;
 894
 895         case EVIOCGRAB:
 896                 if (p)
 897                         return evdev_grab(evdev, client);
 898                 else
 899                         return evdev_ungrab(evdev, client);
 900
 901         case EVIOCREVOKE:
 902                 if (p)
 903                         return -EINVAL;
 904                 else
 905                         return evdev_revoke(evdev, client, file);
 906
 907         case EVIOCSCLOCKID:
 908                 if (copy_from_user(&i, p, sizeof(unsigned int)))
 909                         return -EFAULT;
 910
 911                 return evdev_set_clk_type(client, i);
 912
 913         case EVIOCGKEYCODE:
 914                 return evdev_handle_get_keycode(dev, p);
 915
 916         case EVIOCSKEYCODE:
 917                 return evdev_handle_set_keycode(dev, p);
 918
 919         case EVIOCGKEYCODE_V2:
 920                 return evdev_handle_get_keycode_v2(dev, p);
 921
 922         case EVIOCSKEYCODE_V2:
 923                 return evdev_handle_set_keycode_v2(dev, p);
 924         }
 925
 926         size = _IOC_SIZE(cmd);
 927
 928         /* Now check variable-length commands */
 929 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 930         switch (EVIOC_MASK_SIZE(cmd)) {
 931
 932         case EVIOCGPROP(0):
 933                 return bits_to_user(dev->propbit, INPUT_PROP_MAX,
 934                                     size, p, compat_mode);
 935
 936         case EVIOCGMTSLOTS(0):
 937                 return evdev_handle_mt_request(dev, size, ip);
 938
 939         case EVIOCGKEY(0):
 940                 return evdev_handle_get_val(client, dev, EV_KEY, dev->key,
 941                                             KEY_MAX, size, p, compat_mode);
 942
 943         case EVIOCGLED(0):
 944                 return evdev_handle_get_val(client, dev, EV_LED, dev->led,
 945                                             LED_MAX, size, p, compat_mode);
 946
 947         case EVIOCGSND(0):
 948                 return evdev_handle_get_val(client, dev, EV_SND, dev->snd,
 949                                             SND_MAX, size, p, compat_mode);
 950
 951         case EVIOCGSW(0):
 952                 return evdev_handle_get_val(client, dev, EV_SW, dev->sw,
 953                                             SW_MAX, size, p, compat_mode);
 954
 955         case EVIOCGNAME(0):
 956                 return str_to_user(dev->name, size, p);
 957
 958         case EVIOCGPHYS(0):
 959                 return str_to_user(dev->phys, size, p);
 960
 961         case EVIOCGUNIQ(0):
 962                 return str_to_user(dev->uniq, size, p);
 963
 964         case EVIOC_MASK_SIZE(EVIOCSFF):
 965                 if (input_ff_effect_from_user(p, size, &effect))
 966                         return -EFAULT;
 967
 968                 error = input_ff_upload(dev, &effect, file);
 969                 if (error)
 970                         return error;
 971
 972                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
 973                         return -EFAULT;
 974
 975                 return 0;
 976         }
 977
 978         /* Multi-number variable-length handlers */
 979         if (_IOC_TYPE(cmd) != 'E')
 980                 return -EINVAL;
 981
 982         if (_IOC_DIR(cmd) == _IOC_READ) {
 983
 984                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
 985                         return handle_eviocgbit(dev,
 986                                                 _IOC_NR(cmd) & EV_MAX, size,
 987                                                 p, compat_mode);
 988
 989                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 990
 991                         if (!dev->absinfo)
 992                                 return -EINVAL;
 993
 994                         t = _IOC_NR(cmd) & ABS_MAX;
 995                         abs = dev->absinfo[t];
 996
 997                         if (copy_to_user(p, &abs, min_t(size_t,
 998                                         size, sizeof(struct input_absinfo))))
 999                                 return -EFAULT;
1000
1001                         return 0;
1002                 }
1003         }
1004
1005         if (_IOC_DIR(cmd) == _IOC_WRITE) {
1006
1007                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
1008
1009                         if (!dev->absinfo)
1010                                 return -EINVAL;
1011
1012                         t = _IOC_NR(cmd) & ABS_MAX;
1013
1014                         if (copy_from_user(&abs, p, min_t(size_t,
1015                                         size, sizeof(struct input_absinfo))))
1016                                 return -EFAULT;
1017
1018                         if (size < sizeof(struct input_absinfo))
1019                                 abs.resolution = 0;
1020
1021                         /* We can't change number of reserved MT slots */
1022                         if (t == ABS_MT_SLOT)
1023                                 return -EINVAL;
1024
1025                         /*
1026                          * Take event lock to ensure that we are not
1027                          * changing device parameters in the middle
1028                          * of event.
1029                          */
1030                         spin_lock_irq(&dev->event_lock);
1031                         dev->absinfo[t] = abs;
1032                         spin_unlock_irq(&dev->event_lock);
1033
1034                         return 0;
1035                 }
1036         }
1037
1038         return -EINVAL;
1039 }
1040
1041 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
1042                                 void __user *p, int compat_mode)
1043 {
1044         struct evdev_client *client = file->private_data;
1045         struct evdev *evdev = client->evdev;
1046         int retval;
1047
1048         retval = mutex_lock_interruptible(&evdev->mutex);
1049         if (retval)
1050                 return retval;
1051
1052         if (!evdev->exist || client->revoked) {
1053                 retval = -ENODEV;
1054                 goto out;
1055         }
1056
1057         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
1058
1059  out:
1060         mutex_unlock(&evdev->mutex);
1061         return retval;
1062 }
1063
1064 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1065 {
1066         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
1067 }
1068
1069 #ifdef CONFIG_COMPAT
1070 static long evdev_ioctl_compat(struct file *file,
1071                                 unsigned int cmd, unsigned long arg)
1072 {
1073         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
1074 }
1075 #endif
1076
1077 static const struct file_operations evdev_fops = {
1078         .owner          = THIS_MODULE,
1079         .read           = evdev_read,
1080         .write          = evdev_write,
1081         .poll           = evdev_poll,
1082         .open           = evdev_open,
1083         .release        = evdev_release,
1084         .unlocked_ioctl = evdev_ioctl,
1085 #ifdef CONFIG_COMPAT
1086         .compat_ioctl   = evdev_ioctl_compat,
1087 #endif
1088         .fasync         = evdev_fasync,
1089         .flush          = evdev_flush,
1090         .llseek         = no_llseek,
1091 };
1092
1093 /*
1094  * Mark device non-existent. This disables writes, ioctls and
1095  * prevents new users from opening the device. Already posted
1096  * blocking reads will stay, however new ones will fail.
1097  */
1098 static void evdev_mark_dead(struct evdev *evdev)
1099 {
1100         mutex_lock(&evdev->mutex);
1101         evdev->exist = false;
1102         mutex_unlock(&evdev->mutex);
1103 }
1104
1105 static void evdev_cleanup(struct evdev *evdev)
1106 {
1107         struct input_handle *handle = &evdev->handle;
1108
1109         evdev_mark_dead(evdev);
1110         evdev_hangup(evdev);
1111
1112         cdev_del(&evdev->cdev);
1113
1114         /* evdev is marked dead so no one else accesses evdev->open */
1115         if (evdev->open) {
1116                 input_flush_device(handle, NULL);
1117                 input_close_device(handle);
1118         }
1119 }
1120
1121 /*
1122  * Create new evdev device. Note that input core serializes calls
1123  * to connect and disconnect.
1124  */
1125 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
1126                          const struct input_device_id *id)
1127 {
1128         struct evdev *evdev;
1129         int minor;
1130         int dev_no;
1131         int error;
1132
1133         minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
1134         if (minor < 0) {
1135                 error = minor;
1136                 pr_err("failed to reserve new minor: %d\n", error);
1137                 return error;
1138         }
1139
1140         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
1141         if (!evdev) {
1142                 error = -ENOMEM;
1143                 goto err_free_minor;
1144         }
1145
1146         INIT_LIST_HEAD(&evdev->client_list);
1147         spin_lock_init(&evdev->client_lock);
1148         mutex_init(&evdev->mutex);
1149         init_waitqueue_head(&evdev->wait);
1150         evdev->exist = true;
1151
1152         dev_no = minor;
1153         /* Normalize device number if it falls into legacy range */
1154         if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
1155                 dev_no -= EVDEV_MINOR_BASE;
1156         dev_set_name(&evdev->dev, "event%d", dev_no);
1157
1158         evdev->handle.dev = input_get_device(dev);
1159         evdev->handle.name = dev_name(&evdev->dev);
1160         evdev->handle.handler = handler;
1161         evdev->handle.private = evdev;
1162
1163         evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
1164         evdev->dev.class = &input_class;
1165         evdev->dev.parent = &dev->dev;
1166         evdev->dev.release = evdev_free;
1167         device_initialize(&evdev->dev);
1168
1169         error = input_register_handle(&evdev->handle);
1170         if (error)
1171                 goto err_free_evdev;
1172
1173         cdev_init(&evdev->cdev, &evdev_fops);
1174         evdev->cdev.kobj.parent = &evdev->dev.kobj;
1175         error = cdev_add(&evdev->cdev, evdev->dev.devt, 1);
1176         if (error)
1177                 goto err_unregister_handle;
1178
1179         error = device_add(&evdev->dev);
1180         if (error)
1181                 goto err_cleanup_evdev;
1182
1183         return 0;
1184
1185  err_cleanup_evdev:
1186         evdev_cleanup(evdev);
1187  err_unregister_handle:
1188         input_unregister_handle(&evdev->handle);
1189  err_free_evdev:
1190         put_device(&evdev->dev);
1191  err_free_minor:
1192         input_free_minor(minor);
1193         return error;
1194 }
1195
1196 static void evdev_disconnect(struct input_handle *handle)
1197 {
1198         struct evdev *evdev = handle->private;
1199
1200         device_del(&evdev->dev);
1201         evdev_cleanup(evdev);
1202         input_free_minor(MINOR(evdev->dev.devt));
1203         input_unregister_handle(handle);
1204         put_device(&evdev->dev);
1205 }
1206
1207 static const struct input_device_id evdev_ids[] = {
1208         { .driver_info = 1 },   /* Matches all devices */
1209         { },                    /* Terminating zero entry */
1210 };
1211
1212 MODULE_DEVICE_TABLE(input, evdev_ids);
1213
1214 static struct input_handler evdev_handler = {
1215         .event          = evdev_event,
1216         .events         = evdev_events,
1217         .connect        = evdev_connect,
1218         .disconnect     = evdev_disconnect,
1219         .legacy_minors  = true,
1220         .minor          = EVDEV_MINOR_BASE,
1221         .name           = "evdev",
1222         .id_table       = evdev_ids,
1223 };
1224
1225 static int __init evdev_init(void)
1226 {
1227         return input_register_handler(&evdev_handler);
1228 }
1229
1230 static void __exit evdev_exit(void)
1231 {
1232         input_unregister_handler(&evdev_handler);
1233 }
1234
1235 module_init(evdev_init);
1236 module_exit(evdev_exit);
1237
1238 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
1239 MODULE_DESCRIPTION("Input driver event char devices");
1240 MODULE_LICENSE("GPL");