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 struct evdev {
  32         int open;
  33         struct input_handle handle;
  34         wait_queue_head_t wait;
  35         struct evdev_client __rcu *grab;
  36         struct list_head client_list;
  37         spinlock_t client_lock; /* protects client_list */
  38         struct mutex mutex;
  39         struct device dev;
  40         struct cdev cdev;
  41         bool exist;
  42 };
  43
  44 struct evdev_client {
  45         unsigned int head;
  46         unsigned int tail;
  47         unsigned int packet_head; /* [future] position of the first element of next packet */
  48         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  49         struct fasync_struct *fasync;
  50         struct evdev *evdev;
  51         struct list_head node;
  52         int clkid;
  53         bool revoked;
  54         unsigned int bufsize;
  55         struct input_event buffer[];
  56 };
  57
  58 /* flush queued events of type @type, caller must hold client->buffer_lock */
  59 static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
  60 {
  61         unsigned int i, head, num;
  62         unsigned int mask = client->bufsize - 1;
  63         bool is_report;
  64         struct input_event *ev;
  65
  66         BUG_ON(type == EV_SYN);
  67
  68         head = client->tail;
  69         client->packet_head = client->tail;
  70
  71         /* init to 1 so a leading SYN_REPORT will not be dropped */
  72         num = 1;
  73
  74         for (i = client->tail; i != client->head; i = (i + 1) & mask) {
  75                 ev = &client->buffer[i];
  76                 is_report = ev->type == EV_SYN && ev->code == SYN_REPORT;
  77
  78                 if (ev->type == type) {
  79                         /* drop matched entry */
  80                         continue;
  81                 } else if (is_report && !num) {
  82                         /* drop empty SYN_REPORT groups */
  83                         continue;
  84                 } else if (head != i) {
  85                         /* move entry to fill the gap */
  86                         client->buffer[head].time = ev->time;
  87                         client->buffer[head].type = ev->type;
  88                         client->buffer[head].code = ev->code;
  89                         client->buffer[head].value = ev->value;
  90                 }
  91
  92                 num++;
  93                 head = (head + 1) & mask;
  94
  95                 if (is_report) {
  96                         num = 0;
  97                         client->packet_head = head;
  98                 }
  99         }
 100
 101         client->head = head;
 102 }
 103
 104 /* queue SYN_DROPPED event */
 105 static void evdev_queue_syn_dropped(struct evdev_client *client)
 106 {
 107         unsigned long flags;
 108         struct input_event ev;
 109         ktime_t time;
 110
 111         time = ktime_get();
 112         if (client->clkid != CLOCK_MONOTONIC)
 113                 time = ktime_sub(time, ktime_get_monotonic_offset());
 114
 115         ev.time = ktime_to_timeval(time);
 116         ev.type = EV_SYN;
 117         ev.code = SYN_DROPPED;
 118         ev.value = 0;
 119
 120         spin_lock_irqsave(&client->buffer_lock, flags);
 121
 122         client->buffer[client->head++] = ev;
 123         client->head &= client->bufsize - 1;
 124
 125         if (unlikely(client->head == client->tail)) {
 126                 /* drop queue but keep our SYN_DROPPED event */
 127                 client->tail = (client->head - 1) & (client->bufsize - 1);
 128                 client->packet_head = client->tail;
 129         }
 130
 131         spin_unlock_irqrestore(&client->buffer_lock, flags);
 132 }
 133
 134 static void __pass_event(struct evdev_client *client,
 135                          const struct input_event *event)
 136 {
 137         client->buffer[client->head++] = *event;
 138         client->head &= client->bufsize - 1;
 139
 140         if (unlikely(client->head == client->tail)) {
 141                 /*
 142                  * This effectively "drops" all unconsumed events, leaving
 143                  * EV_SYN/SYN_DROPPED plus the newest event in the queue.
 144                  */
 145                 client->tail = (client->head - 2) & (client->bufsize - 1);
 146
 147                 client->buffer[client->tail].time = event->time;
 148                 client->buffer[client->tail].type = EV_SYN;
 149                 client->buffer[client->tail].code = SYN_DROPPED;
 150                 client->buffer[client->tail].value = 0;
 151
 152                 client->packet_head = client->tail;
 153         }
 154
 155         if (event->type == EV_SYN && event->code == SYN_REPORT) {
 156                 client->packet_head = client->head;
 157                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
 158         }
 159 }
 160
 161 static void evdev_pass_values(struct evdev_client *client,
 162                         const struct input_value *vals, unsigned int count,
 163                         ktime_t mono, ktime_t real)
 164 {
 165         struct evdev *evdev = client->evdev;
 166         const struct input_value *v;
 167         struct input_event event;
 168         bool wakeup = false;
 169
 170         if (client->revoked)
 171                 return;
 172
 173         event.time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
 174                                       mono : real);
 175
 176         /* Interrupts are disabled, just acquire the lock. */
 177         spin_lock(&client->buffer_lock);
 178
 179         for (v = vals; v != vals + count; v++) {
 180                 event.type = v->type;
 181                 event.code = v->code;
 182                 event.value = v->value;
 183                 __pass_event(client, &event);
 184                 if (v->type == EV_SYN && v->code == SYN_REPORT)
 185                         wakeup = true;
 186         }
 187
 188         spin_unlock(&client->buffer_lock);
 189
 190         if (wakeup)
 191                 wake_up_interruptible(&evdev->wait);
 192 }
 193
 194 /*
 195  * Pass incoming events to all connected clients.
 196  */
 197 static void evdev_events(struct input_handle *handle,
 198                          const struct input_value *vals, unsigned int count)
 199 {
 200         struct evdev *evdev = handle->private;
 201         struct evdev_client *client;
 202         ktime_t time_mono, time_real;
 203
 204         time_mono = ktime_get();
 205         time_real = ktime_sub(time_mono, ktime_get_monotonic_offset());
 206
 207         rcu_read_lock();
 208
 209         client = rcu_dereference(evdev->grab);
 210
 211         if (client)
 212                 evdev_pass_values(client, vals, count, time_mono, time_real);
 213         else
 214                 list_for_each_entry_rcu(client, &evdev->client_list, node)
 215                         evdev_pass_values(client, vals, count,
 216                                           time_mono, time_real);
 217
 218         rcu_read_unlock();
 219 }
 220
 221 /*
 222  * Pass incoming event to all connected clients.
 223  */
 224 static void evdev_event(struct input_handle *handle,
 225                         unsigned int type, unsigned int code, int value)
 226 {
 227         struct input_value vals[] = { { type, code, value } };
 228
 229         evdev_events(handle, vals, 1);
 230 }
 231
 232 static int evdev_fasync(int fd, struct file *file, int on)
 233 {
 234         struct evdev_client *client = file->private_data;
 235
 236         return fasync_helper(fd, file, on, &client->fasync);
 237 }
 238
 239 static int evdev_flush(struct file *file, fl_owner_t id)
 240 {
 241         struct evdev_client *client = file->private_data;
 242         struct evdev *evdev = client->evdev;
 243         int retval;
 244
 245         retval = mutex_lock_interruptible(&evdev->mutex);
 246         if (retval)
 247                 return retval;
 248
 249         if (!evdev->exist || client->revoked)
 250                 retval = -ENODEV;
 251         else
 252                 retval = input_flush_device(&evdev->handle, file);
 253
 254         mutex_unlock(&evdev->mutex);
 255         return retval;
 256 }
 257
 258 static void evdev_free(struct device *dev)
 259 {
 260         struct evdev *evdev = container_of(dev, struct evdev, dev);
 261
 262         input_put_device(evdev->handle.dev);
 263         kfree(evdev);
 264 }
 265
 266 /*
 267  * Grabs an event device (along with underlying input device).
 268  * This function is called with evdev->mutex taken.
 269  */
 270 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 271 {
 272         int error;
 273
 274         if (evdev->grab)
 275                 return -EBUSY;
 276
 277         error = input_grab_device(&evdev->handle);
 278         if (error)
 279                 return error;
 280
 281         rcu_assign_pointer(evdev->grab, client);
 282
 283         return 0;
 284 }
 285
 286 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 287 {
 288         struct evdev_client *grab = rcu_dereference_protected(evdev->grab,
 289                                         lockdep_is_held(&evdev->mutex));
 290
 291         if (grab != client)
 292                 return  -EINVAL;
 293
 294         rcu_assign_pointer(evdev->grab, NULL);
 295         synchronize_rcu();
 296         input_release_device(&evdev->handle);
 297
 298         return 0;
 299 }
 300
 301 static void evdev_attach_client(struct evdev *evdev,
 302                                 struct evdev_client *client)
 303 {
 304         spin_lock(&evdev->client_lock);
 305         list_add_tail_rcu(&client->node, &evdev->client_list);
 306         spin_unlock(&evdev->client_lock);
 307 }
 308
 309 static void evdev_detach_client(struct evdev *evdev,
 310                                 struct evdev_client *client)
 311 {
 312         spin_lock(&evdev->client_lock);
 313         list_del_rcu(&client->node);
 314         spin_unlock(&evdev->client_lock);
 315         synchronize_rcu();
 316 }
 317
 318 static int evdev_open_device(struct evdev *evdev)
 319 {
 320         int retval;
 321
 322         retval = mutex_lock_interruptible(&evdev->mutex);
 323         if (retval)
 324                 return retval;
 325
 326         if (!evdev->exist)
 327                 retval = -ENODEV;
 328         else if (!evdev->open++) {
 329                 retval = input_open_device(&evdev->handle);
 330                 if (retval)
 331                         evdev->open--;
 332         }
 333
 334         mutex_unlock(&evdev->mutex);
 335         return retval;
 336 }
 337
 338 static void evdev_close_device(struct evdev *evdev)
 339 {
 340         mutex_lock(&evdev->mutex);
 341
 342         if (evdev->exist && !--evdev->open)
 343                 input_close_device(&evdev->handle);
 344
 345         mutex_unlock(&evdev->mutex);
 346 }
 347
 348 /*
 349  * Wake up users waiting for IO so they can disconnect from
 350  * dead device.
 351  */
 352 static void evdev_hangup(struct evdev *evdev)
 353 {
 354         struct evdev_client *client;
 355
 356         spin_lock(&evdev->client_lock);
 357         list_for_each_entry(client, &evdev->client_list, node)
 358                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 359         spin_unlock(&evdev->client_lock);
 360
 361         wake_up_interruptible(&evdev->wait);
 362 }
 363
 364 static int evdev_release(struct inode *inode, struct file *file)
 365 {
 366         struct evdev_client *client = file->private_data;
 367         struct evdev *evdev = client->evdev;
 368
 369         mutex_lock(&evdev->mutex);
 370         evdev_ungrab(evdev, client);
 371         mutex_unlock(&evdev->mutex);
 372
 373         evdev_detach_client(evdev, client);
 374
 375         if (is_vmalloc_addr(client))
 376                 vfree(client);
 377         else
 378                 kfree(client);
 379
 380         evdev_close_device(evdev);
 381
 382         return 0;
 383 }
 384
 385 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 386 {
 387         unsigned int n_events =
 388                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 389                     EVDEV_MIN_BUFFER_SIZE);
 390
 391         return roundup_pow_of_two(n_events);
 392 }
 393
 394 static int evdev_open(struct inode *inode, struct file *file)
 395 {
 396         struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
 397         unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 398         unsigned int size = sizeof(struct evdev_client) +
 399                                         bufsize * sizeof(struct input_event);
 400         struct evdev_client *client;
 401         int error;
 402
 403         client = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
 404         if (!client)
 405                 client = vzalloc(size);
 406         if (!client)
 407                 return -ENOMEM;
 408
 409         client->bufsize = bufsize;
 410         spin_lock_init(&client->buffer_lock);
 411         client->evdev = evdev;
 412         evdev_attach_client(evdev, client);
 413
 414         error = evdev_open_device(evdev);
 415         if (error)
 416                 goto err_free_client;
 417
 418         file->private_data = client;
 419         nonseekable_open(inode, file);
 420
 421         return 0;
 422
 423  err_free_client:
 424         evdev_detach_client(evdev, client);
 425         kfree(client);
 426         return error;
 427 }
 428
 429 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 430                            size_t count, loff_t *ppos)
 431 {
 432         struct evdev_client *client = file->private_data;
 433         struct evdev *evdev = client->evdev;
 434         struct input_event event;
 435         int retval = 0;
 436
 437         if (count != 0 && count < input_event_size())
 438                 return -EINVAL;
 439
 440         retval = mutex_lock_interruptible(&evdev->mutex);
 441         if (retval)
 442                 return retval;
 443
 444         if (!evdev->exist || client->revoked) {
 445                 retval = -ENODEV;
 446                 goto out;
 447         }
 448
 449         while (retval + input_event_size() <= count) {
 450
 451                 if (input_event_from_user(buffer + retval, &event)) {
 452                         retval = -EFAULT;
 453                         goto out;
 454                 }
 455                 retval += input_event_size();
 456
 457                 input_inject_event(&evdev->handle,
 458                                    event.type, event.code, event.value);
 459         }
 460
 461  out:
 462         mutex_unlock(&evdev->mutex);
 463         return retval;
 464 }
 465
 466 static int evdev_fetch_next_event(struct evdev_client *client,
 467                                   struct input_event *event)
 468 {
 469         int have_event;
 470
 471         spin_lock_irq(&client->buffer_lock);
 472
 473         have_event = client->packet_head != client->tail;
 474         if (have_event) {
 475                 *event = client->buffer[client->tail++];
 476                 client->tail &= client->bufsize - 1;
 477         }
 478
 479         spin_unlock_irq(&client->buffer_lock);
 480
 481         return have_event;
 482 }
 483
 484 static ssize_t evdev_read(struct file *file, char __user *buffer,
 485                           size_t count, loff_t *ppos)
 486 {
 487         struct evdev_client *client = file->private_data;
 488         struct evdev *evdev = client->evdev;
 489         struct input_event event;
 490         size_t read = 0;
 491         int error;
 492
 493         if (count != 0 && count < input_event_size())
 494                 return -EINVAL;
 495
 496         for (;;) {
 497                 if (!evdev->exist || client->revoked)
 498                         return -ENODEV;
 499
 500                 if (client->packet_head == client->tail &&
 501                     (file->f_flags & O_NONBLOCK))
 502                         return -EAGAIN;
 503
 504                 /*
 505                  * count == 0 is special - no IO is done but we check
 506                  * for error conditions (see above).
 507                  */
 508                 if (count == 0)
 509                         break;
 510
 511                 while (read + input_event_size() <= count &&
 512                        evdev_fetch_next_event(client, &event)) {
 513
 514                         if (input_event_to_user(buffer + read, &event))
 515                                 return -EFAULT;
 516
 517                         read += input_event_size();
 518                 }
 519
 520                 if (read)
 521                         break;
 522
 523                 if (!(file->f_flags & O_NONBLOCK)) {
 524                         error = wait_event_interruptible(evdev->wait,
 525                                         client->packet_head != client->tail ||
 526                                         !evdev->exist || client->revoked);
 527                         if (error)
 528                                 return error;
 529                 }
 530         }
 531
 532         return read;
 533 }
 534
 535 /* No kernel lock - fine */
 536 static unsigned int evdev_poll(struct file *file, poll_table *wait)
 537 {
 538         struct evdev_client *client = file->private_data;
 539         struct evdev *evdev = client->evdev;
 540         unsigned int mask;
 541
 542         poll_wait(file, &evdev->wait, wait);
 543
 544         if (evdev->exist && !client->revoked)
 545                 mask = POLLOUT | POLLWRNORM;
 546         else
 547                 mask = POLLHUP | POLLERR;
 548
 549         if (client->packet_head != client->tail)
 550                 mask |= POLLIN | POLLRDNORM;
 551
 552         return mask;
 553 }
 554
 555 #ifdef CONFIG_COMPAT
 556
 557 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 558 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 559
 560 #ifdef __BIG_ENDIAN
 561 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 562                         unsigned int maxlen, void __user *p, int compat)
 563 {
 564         int len, i;
 565
 566         if (compat) {
 567                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 568                 if (len > maxlen)
 569                         len = maxlen;
 570
 571                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 572                         if (copy_to_user((compat_long_t __user *) p + i,
 573                                          (compat_long_t *) bits +
 574                                                 i + 1 - ((i % 2) << 1),
 575                                          sizeof(compat_long_t)))
 576                                 return -EFAULT;
 577         } else {
 578                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 579                 if (len > maxlen)
 580                         len = maxlen;
 581
 582                 if (copy_to_user(p, bits, len))
 583                         return -EFAULT;
 584         }
 585
 586         return len;
 587 }
 588 #else
 589 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 590                         unsigned int maxlen, void __user *p, int compat)
 591 {
 592         int len = compat ?
 593                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 594                         BITS_TO_LONGS(maxbit) * sizeof(long);
 595
 596         if (len > maxlen)
 597                 len = maxlen;
 598
 599         return copy_to_user(p, bits, len) ? -EFAULT : len;
 600 }
 601 #endif /* __BIG_ENDIAN */
 602
 603 #else
 604
 605 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 606                         unsigned int maxlen, void __user *p, int compat)
 607 {
 608         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 609
 610         if (len > maxlen)
 611                 len = maxlen;
 612
 613         return copy_to_user(p, bits, len) ? -EFAULT : len;
 614 }
 615
 616 #endif /* CONFIG_COMPAT */
 617
 618 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 619 {
 620         int len;
 621
 622         if (!str)
 623                 return -ENOENT;
 624
 625         len = strlen(str) + 1;
 626         if (len > maxlen)
 627                 len = maxlen;
 628
 629         return copy_to_user(p, str, len) ? -EFAULT : len;
 630 }
 631
 632 #define OLD_KEY_MAX     0x1ff
 633 static int handle_eviocgbit(struct input_dev *dev,
 634                             unsigned int type, unsigned int size,
 635                             void __user *p, int compat_mode)
 636 {
 637         static unsigned long keymax_warn_time;
 638         unsigned long *bits;
 639         int len;
 640
 641         switch (type) {
 642
 643         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 644         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 645         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 646         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 647         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 648         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 649         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 650         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 651         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 652         default: return -EINVAL;
 653         }
 654
 655         /*
 656          * Work around bugs in userspace programs that like to do
 657          * EVIOCGBIT(EV_KEY, KEY_MAX) and not realize that 'len'
 658          * should be in bytes, not in bits.
 659          */
 660         if (type == EV_KEY && size == OLD_KEY_MAX) {
 661                 len = OLD_KEY_MAX;
 662                 if (printk_timed_ratelimit(&keymax_warn_time, 10 * 1000))
 663                         pr_warning("(EVIOCGBIT): Suspicious buffer size %u, "
 664                                    "limiting output to %zu bytes. See "
 665                                    "http://userweb.kernel.org/~dtor/eviocgbit-bug.html\n",
 666                                    OLD_KEY_MAX,
 667                                    BITS_TO_LONGS(OLD_KEY_MAX) * sizeof(long));
 668         }
 669
 670         return bits_to_user(bits, len, size, p, compat_mode);
 671 }
 672 #undef OLD_KEY_MAX
 673
 674 static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)
 675 {
 676         struct input_keymap_entry ke = {
 677                 .len    = sizeof(unsigned int),
 678                 .flags  = 0,
 679         };
 680         int __user *ip = (int __user *)p;
 681         int error;
 682
 683         /* legacy case */
 684         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 685                 return -EFAULT;
 686
 687         error = input_get_keycode(dev, &ke);
 688         if (error)
 689                 return error;
 690
 691         if (put_user(ke.keycode, ip + 1))
 692                 return -EFAULT;
 693
 694         return 0;
 695 }
 696
 697 static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
 698 {
 699         struct input_keymap_entry ke;
 700         int error;
 701
 702         if (copy_from_user(&ke, p, sizeof(ke)))
 703                 return -EFAULT;
 704
 705         error = input_get_keycode(dev, &ke);
 706         if (error)
 707                 return error;
 708
 709         if (copy_to_user(p, &ke, sizeof(ke)))
 710                 return -EFAULT;
 711
 712         return 0;
 713 }
 714
 715 static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)
 716 {
 717         struct input_keymap_entry ke = {
 718                 .len    = sizeof(unsigned int),
 719                 .flags  = 0,
 720         };
 721         int __user *ip = (int __user *)p;
 722
 723         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 724                 return -EFAULT;
 725
 726         if (get_user(ke.keycode, ip + 1))
 727                 return -EFAULT;
 728
 729         return input_set_keycode(dev, &ke);
 730 }
 731
 732 static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 733 {
 734         struct input_keymap_entry ke;
 735
 736         if (copy_from_user(&ke, p, sizeof(ke)))
 737                 return -EFAULT;
 738
 739         if (ke.len > sizeof(ke.scancode))
 740                 return -EINVAL;
 741
 742         return input_set_keycode(dev, &ke);
 743 }
 744
 745 /*
 746  * If we transfer state to the user, we should flush all pending events
 747  * of the same type from the client's queue. Otherwise, they might end up
 748  * with duplicate events, which can screw up client's state tracking.
 749  * If bits_to_user fails after flushing the queue, we queue a SYN_DROPPED
 750  * event so user-space will notice missing events.
 751  *
 752  * LOCKING:
 753  * We need to take event_lock before buffer_lock to avoid dead-locks. But we
 754  * need the even_lock only to guarantee consistent state. We can safely release
 755  * it while flushing the queue. This allows input-core to handle filters while
 756  * we flush the queue.
 757  */
 758 static int evdev_handle_get_val(struct evdev_client *client,
 759                                 struct input_dev *dev, unsigned int type,
 760                                 unsigned long *bits, unsigned int max,
 761                                 unsigned int size, void __user *p, int compat)
 762 {
 763         int ret;
 764         unsigned long *mem;
 765
 766         mem = kmalloc(sizeof(unsigned long) * max, GFP_KERNEL);
 767         if (!mem)
 768                 return -ENOMEM;
 769
 770         spin_lock_irq(&dev->event_lock);
 771         spin_lock(&client->buffer_lock);
 772
 773         memcpy(mem, bits, sizeof(unsigned long) * max);
 774
 775         spin_unlock(&dev->event_lock);
 776
 777         __evdev_flush_queue(client, type);
 778
 779         spin_unlock_irq(&client->buffer_lock);
 780
 781         ret = bits_to_user(mem, max, size, p, compat);
 782         if (ret < 0)
 783                 evdev_queue_syn_dropped(client);
 784
 785         kfree(mem);
 786
 787         return ret;
 788 }
 789
 790 static int evdev_handle_mt_request(struct input_dev *dev,
 791                                    unsigned int size,
 792                                    int __user *ip)
 793 {
 794         const struct input_mt *mt = dev->mt;
 795         unsigned int code;
 796         int max_slots;
 797         int i;
 798
 799         if (get_user(code, &ip[0]))
 800                 return -EFAULT;
 801         if (!mt || !input_is_mt_value(code))
 802                 return -EINVAL;
 803
 804         max_slots = (size - sizeof(__u32)) / sizeof(__s32);
 805         for (i = 0; i < mt->num_slots && i < max_slots; i++) {
 806                 int value = input_mt_get_value(&mt->slots[i], code);
 807                 if (put_user(value, &ip[1 + i]))
 808                         return -EFAULT;
 809         }
 810
 811         return 0;
 812 }
 813
 814 static int evdev_revoke(struct evdev *evdev, struct evdev_client *client,
 815                         struct file *file)
 816 {
 817         client->revoked = true;
 818         evdev_ungrab(evdev, client);
 819         input_flush_device(&evdev->handle, file);
 820         wake_up_interruptible(&evdev->wait);
 821
 822         return 0;
 823 }
 824
 825 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
 826                            void __user *p, int compat_mode)
 827 {
 828         struct evdev_client *client = file->private_data;
 829         struct evdev *evdev = client->evdev;
 830         struct input_dev *dev = evdev->handle.dev;
 831         struct input_absinfo abs;
 832         struct ff_effect effect;
 833         int __user *ip = (int __user *)p;
 834         unsigned int i, t, u, v;
 835         unsigned int size;
 836         int error;
 837
 838         /* First we check for fixed-length commands */
 839         switch (cmd) {
 840
 841         case EVIOCGVERSION:
 842                 return put_user(EV_VERSION, ip);
 843
 844         case EVIOCGID:
 845                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
 846                         return -EFAULT;
 847                 return 0;
 848
 849         case EVIOCGREP:
 850                 if (!test_bit(EV_REP, dev->evbit))
 851                         return -ENOSYS;
 852                 if (put_user(dev->rep[REP_DELAY], ip))
 853                         return -EFAULT;
 854                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
 855                         return -EFAULT;
 856                 return 0;
 857
 858         case EVIOCSREP:
 859                 if (!test_bit(EV_REP, dev->evbit))
 860                         return -ENOSYS;
 861                 if (get_user(u, ip))
 862                         return -EFAULT;
 863                 if (get_user(v, ip + 1))
 864                         return -EFAULT;
 865
 866                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
 867                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
 868
 869                 return 0;
 870
 871         case EVIOCRMFF:
 872                 return input_ff_erase(dev, (int)(unsigned long) p, file);
 873
 874         case EVIOCGEFFECTS:
 875                 i = test_bit(EV_FF, dev->evbit) ?
 876                                 dev->ff->max_effects : 0;
 877                 if (put_user(i, ip))
 878                         return -EFAULT;
 879                 return 0;
 880
 881         case EVIOCGRAB:
 882                 if (p)
 883                         return evdev_grab(evdev, client);
 884                 else
 885                         return evdev_ungrab(evdev, client);
 886
 887         case EVIOCREVOKE:
 888                 if (p)
 889                         return -EINVAL;
 890                 else
 891                         return evdev_revoke(evdev, client, file);
 892
 893         case EVIOCSCLOCKID:
 894                 if (copy_from_user(&i, p, sizeof(unsigned int)))
 895                         return -EFAULT;
 896                 if (i != CLOCK_MONOTONIC && i != CLOCK_REALTIME)
 897                         return -EINVAL;
 898                 client->clkid = i;
 899                 return 0;
 900
 901         case EVIOCGKEYCODE:
 902                 return evdev_handle_get_keycode(dev, p);
 903
 904         case EVIOCSKEYCODE:
 905                 return evdev_handle_set_keycode(dev, p);
 906
 907         case EVIOCGKEYCODE_V2:
 908                 return evdev_handle_get_keycode_v2(dev, p);
 909
 910         case EVIOCSKEYCODE_V2:
 911                 return evdev_handle_set_keycode_v2(dev, p);
 912         }
 913
 914         size = _IOC_SIZE(cmd);
 915
 916         /* Now check variable-length commands */
 917 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
 918         switch (EVIOC_MASK_SIZE(cmd)) {
 919
 920         case EVIOCGPROP(0):
 921                 return bits_to_user(dev->propbit, INPUT_PROP_MAX,
 922                                     size, p, compat_mode);
 923
 924         case EVIOCGMTSLOTS(0):
 925                 return evdev_handle_mt_request(dev, size, ip);
 926
 927         case EVIOCGKEY(0):
 928                 return evdev_handle_get_val(client, dev, EV_KEY, dev->key,
 929                                             KEY_MAX, size, p, compat_mode);
 930
 931         case EVIOCGLED(0):
 932                 return evdev_handle_get_val(client, dev, EV_LED, dev->led,
 933                                             LED_MAX, size, p, compat_mode);
 934
 935         case EVIOCGSND(0):
 936                 return evdev_handle_get_val(client, dev, EV_SND, dev->snd,
 937                                             SND_MAX, size, p, compat_mode);
 938
 939         case EVIOCGSW(0):
 940                 return evdev_handle_get_val(client, dev, EV_SW, dev->sw,
 941                                             SW_MAX, size, p, compat_mode);
 942
 943         case EVIOCGNAME(0):
 944                 return str_to_user(dev->name, size, p);
 945
 946         case EVIOCGPHYS(0):
 947                 return str_to_user(dev->phys, size, p);
 948
 949         case EVIOCGUNIQ(0):
 950                 return str_to_user(dev->uniq, size, p);
 951
 952         case EVIOC_MASK_SIZE(EVIOCSFF):
 953                 if (input_ff_effect_from_user(p, size, &effect))
 954                         return -EFAULT;
 955
 956                 error = input_ff_upload(dev, &effect, file);
 957
 958                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
 959                         return -EFAULT;
 960
 961                 return error;
 962         }
 963
 964         /* Multi-number variable-length handlers */
 965         if (_IOC_TYPE(cmd) != 'E')
 966                 return -EINVAL;
 967
 968         if (_IOC_DIR(cmd) == _IOC_READ) {
 969
 970                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
 971                         return handle_eviocgbit(dev,
 972                                                 _IOC_NR(cmd) & EV_MAX, size,
 973                                                 p, compat_mode);
 974
 975                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
 976
 977                         if (!dev->absinfo)
 978                                 return -EINVAL;
 979
 980                         t = _IOC_NR(cmd) & ABS_MAX;
 981                         abs = dev->absinfo[t];
 982
 983                         if (copy_to_user(p, &abs, min_t(size_t,
 984                                         size, sizeof(struct input_absinfo))))
 985                                 return -EFAULT;
 986
 987                         return 0;
 988                 }
 989         }
 990
 991         if (_IOC_DIR(cmd) == _IOC_WRITE) {
 992
 993                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
 994
 995                         if (!dev->absinfo)
 996                                 return -EINVAL;
 997
 998                         t = _IOC_NR(cmd) & ABS_MAX;
 999
1000                         if (copy_from_user(&abs, p, min_t(size_t,
1001                                         size, sizeof(struct input_absinfo))))
1002                                 return -EFAULT;
1003
1004                         if (size < sizeof(struct input_absinfo))
1005                                 abs.resolution = 0;
1006
1007                         /* We can't change number of reserved MT slots */
1008                         if (t == ABS_MT_SLOT)
1009                                 return -EINVAL;
1010
1011                         /*
1012                          * Take event lock to ensure that we are not
1013                          * changing device parameters in the middle
1014                          * of event.
1015                          */
1016                         spin_lock_irq(&dev->event_lock);
1017                         dev->absinfo[t] = abs;
1018                         spin_unlock_irq(&dev->event_lock);
1019
1020                         return 0;
1021                 }
1022         }
1023
1024         return -EINVAL;
1025 }
1026
1027 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
1028                                 void __user *p, int compat_mode)
1029 {
1030         struct evdev_client *client = file->private_data;
1031         struct evdev *evdev = client->evdev;
1032         int retval;
1033
1034         retval = mutex_lock_interruptible(&evdev->mutex);
1035         if (retval)
1036                 return retval;
1037
1038         if (!evdev->exist || client->revoked) {
1039                 retval = -ENODEV;
1040                 goto out;
1041         }
1042
1043         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
1044
1045  out:
1046         mutex_unlock(&evdev->mutex);
1047         return retval;
1048 }
1049
1050 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1051 {
1052         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
1053 }
1054
1055 #ifdef CONFIG_COMPAT
1056 static long evdev_ioctl_compat(struct file *file,
1057                                 unsigned int cmd, unsigned long arg)
1058 {
1059         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
1060 }
1061 #endif
1062
1063 static const struct file_operations evdev_fops = {
1064         .owner          = THIS_MODULE,
1065         .read           = evdev_read,
1066         .write          = evdev_write,
1067         .poll           = evdev_poll,
1068         .open           = evdev_open,
1069         .release        = evdev_release,
1070         .unlocked_ioctl = evdev_ioctl,
1071 #ifdef CONFIG_COMPAT
1072         .compat_ioctl   = evdev_ioctl_compat,
1073 #endif
1074         .fasync         = evdev_fasync,
1075         .flush          = evdev_flush,
1076         .llseek         = no_llseek,
1077 };
1078
1079 /*
1080  * Mark device non-existent. This disables writes, ioctls and
1081  * prevents new users from opening the device. Already posted
1082  * blocking reads will stay, however new ones will fail.
1083  */
1084 static void evdev_mark_dead(struct evdev *evdev)
1085 {
1086         mutex_lock(&evdev->mutex);
1087         evdev->exist = false;
1088         mutex_unlock(&evdev->mutex);
1089 }
1090
1091 static void evdev_cleanup(struct evdev *evdev)
1092 {
1093         struct input_handle *handle = &evdev->handle;
1094
1095         evdev_mark_dead(evdev);
1096         evdev_hangup(evdev);
1097
1098         cdev_del(&evdev->cdev);
1099
1100         /* evdev is marked dead so no one else accesses evdev->open */
1101         if (evdev->open) {
1102                 input_flush_device(handle, NULL);
1103                 input_close_device(handle);
1104         }
1105 }
1106
1107 /*
1108  * Create new evdev device. Note that input core serializes calls
1109  * to connect and disconnect.
1110  */
1111 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
1112                          const struct input_device_id *id)
1113 {
1114         struct evdev *evdev;
1115         int minor;
1116         int dev_no;
1117         int error;
1118
1119         minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
1120         if (minor < 0) {
1121                 error = minor;
1122                 pr_err("failed to reserve new minor: %d\n", error);
1123                 return error;
1124         }
1125
1126         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
1127         if (!evdev) {
1128                 error = -ENOMEM;
1129                 goto err_free_minor;
1130         }
1131
1132         INIT_LIST_HEAD(&evdev->client_list);
1133         spin_lock_init(&evdev->client_lock);
1134         mutex_init(&evdev->mutex);
1135         init_waitqueue_head(&evdev->wait);
1136         evdev->exist = true;
1137
1138         dev_no = minor;
1139         /* Normalize device number if it falls into legacy range */
1140         if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
1141                 dev_no -= EVDEV_MINOR_BASE;
1142         dev_set_name(&evdev->dev, "event%d", dev_no);
1143
1144         evdev->handle.dev = input_get_device(dev);
1145         evdev->handle.name = dev_name(&evdev->dev);
1146         evdev->handle.handler = handler;
1147         evdev->handle.private = evdev;
1148
1149         evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
1150         evdev->dev.class = &input_class;
1151         evdev->dev.parent = &dev->dev;
1152         evdev->dev.release = evdev_free;
1153         device_initialize(&evdev->dev);
1154
1155         error = input_register_handle(&evdev->handle);
1156         if (error)
1157                 goto err_free_evdev;
1158
1159         cdev_init(&evdev->cdev, &evdev_fops);
1160         evdev->cdev.kobj.parent = &evdev->dev.kobj;
1161         error = cdev_add(&evdev->cdev, evdev->dev.devt, 1);
1162         if (error)
1163                 goto err_unregister_handle;
1164
1165         error = device_add(&evdev->dev);
1166         if (error)
1167                 goto err_cleanup_evdev;
1168
1169         return 0;
1170
1171  err_cleanup_evdev:
1172         evdev_cleanup(evdev);
1173  err_unregister_handle:
1174         input_unregister_handle(&evdev->handle);
1175  err_free_evdev:
1176         put_device(&evdev->dev);
1177  err_free_minor:
1178         input_free_minor(minor);
1179         return error;
1180 }
1181
1182 static void evdev_disconnect(struct input_handle *handle)
1183 {
1184         struct evdev *evdev = handle->private;
1185
1186         device_del(&evdev->dev);
1187         evdev_cleanup(evdev);
1188         input_free_minor(MINOR(evdev->dev.devt));
1189         input_unregister_handle(handle);
1190         put_device(&evdev->dev);
1191 }
1192
1193 static const struct input_device_id evdev_ids[] = {
1194         { .driver_info = 1 },   /* Matches all devices */
1195         { },                    /* Terminating zero entry */
1196 };
1197
1198 MODULE_DEVICE_TABLE(input, evdev_ids);
1199
1200 static struct input_handler evdev_handler = {
1201         .event          = evdev_event,
1202         .events         = evdev_events,
1203         .connect        = evdev_connect,
1204         .disconnect     = evdev_disconnect,
1205         .legacy_minors  = true,
1206         .minor          = EVDEV_MINOR_BASE,
1207         .name           = "evdev",
1208         .id_table       = evdev_ids,
1209 };
1210
1211 static int __init evdev_init(void)
1212 {
1213         return input_register_handler(&evdev_handler);
1214 }
1215
1216 static void __exit evdev_exit(void)
1217 {
1218         input_unregister_handler(&evdev_handler);
1219 }
1220
1221 module_init(evdev_init);
1222 module_exit(evdev_exit);
1223
1224 MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
1225 MODULE_DESCRIPTION("Input driver event char devices");
1226 MODULE_LICENSE("GPL");