drivers/input/evdev.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Event char devices, giving access to raw input device events.
   4  *
   5  * Copyright (c) 1999-2002 Vojtech Pavlik
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #define EVDEV_MINOR_BASE        64
  11 #define EVDEV_MINORS            32
  12 #define EVDEV_MIN_BUFFER_SIZE   64U
  13 #define EVDEV_BUF_PACKETS       8
  14
  15 #include <linux/poll.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/mm.h>
  20 #include <linux/module.h>
  21 #include <linux/init.h>
  22 #include <linux/input/mt.h>
  23 #include <linux/major.h>
  24 #include <linux/device.h>
  25 #include <linux/cdev.h>
  26 #include "input-compat.h"
  27
  28 struct evdev {
  29         int open;
  30         struct input_handle handle;
  31         struct evdev_client __rcu *grab;
  32         struct list_head client_list;
  33         spinlock_t client_lock; /* protects client_list */
  34         struct mutex mutex;
  35         struct device dev;
  36         struct cdev cdev;
  37         bool exist;
  38 };
  39
  40 struct evdev_client {
  41         unsigned int head;
  42         unsigned int tail;
  43         unsigned int packet_head; /* [future] position of the first element of next packet */
  44         spinlock_t buffer_lock; /* protects access to buffer, head and tail */
  45         wait_queue_head_t wait;
  46         struct fasync_struct *fasync;
  47         struct evdev *evdev;
  48         struct list_head node;
  49         enum input_clock_type clk_type;
  50         bool revoked;
  51         unsigned long *evmasks[EV_CNT];
  52         unsigned int bufsize;
  53         struct input_event buffer[];
  54 };
  55
  56 static size_t evdev_get_mask_cnt(unsigned int type)
  57 {
  58         static const size_t counts[EV_CNT] = {
  59                 /* EV_SYN==0 is EV_CNT, _not_ SYN_CNT, see EVIOCGBIT */
  60                 [EV_SYN]        = EV_CNT,
  61                 [EV_KEY]        = KEY_CNT,
  62                 [EV_REL]        = REL_CNT,
  63                 [EV_ABS]        = ABS_CNT,
  64                 [EV_MSC]        = MSC_CNT,
  65                 [EV_SW]         = SW_CNT,
  66                 [EV_LED]        = LED_CNT,
  67                 [EV_SND]        = SND_CNT,
  68                 [EV_FF]         = FF_CNT,
  69         };
  70
  71         return (type < EV_CNT) ? counts[type] : 0;
  72 }
  73
  74 /* requires the buffer lock to be held */
  75 static bool __evdev_is_filtered(struct evdev_client *client,
  76                                 unsigned int type,
  77                                 unsigned int code)
  78 {
  79         unsigned long *mask;
  80         size_t cnt;
  81
  82         /* EV_SYN and unknown codes are never filtered */
  83         if (type == EV_SYN || type >= EV_CNT)
  84                 return false;
  85
  86         /* first test whether the type is filtered */
  87         mask = client->evmasks[0];
  88         if (mask && !test_bit(type, mask))
  89                 return true;
  90
  91         /* unknown values are never filtered */
  92         cnt = evdev_get_mask_cnt(type);
  93         if (!cnt || code >= cnt)
  94                 return false;
  95
  96         mask = client->evmasks[type];
  97         return mask && !test_bit(code, mask);
  98 }
  99
 100 /* flush queued events of type @type, caller must hold client->buffer_lock */
 101 static void __evdev_flush_queue(struct evdev_client *client, unsigned int type)
 102 {
 103         unsigned int i, head, num;
 104         unsigned int mask = client->bufsize - 1;
 105         bool is_report;
 106         struct input_event *ev;
 107
 108         BUG_ON(type == EV_SYN);
 109
 110         head = client->tail;
 111         client->packet_head = client->tail;
 112
 113         /* init to 1 so a leading SYN_REPORT will not be dropped */
 114         num = 1;
 115
 116         for (i = client->tail; i != client->head; i = (i + 1) & mask) {
 117                 ev = &client->buffer[i];
 118                 is_report = ev->type == EV_SYN && ev->code == SYN_REPORT;
 119
 120                 if (ev->type == type) {
 121                         /* drop matched entry */
 122                         continue;
 123                 } else if (is_report && !num) {
 124                         /* drop empty SYN_REPORT groups */
 125                         continue;
 126                 } else if (head != i) {
 127                         /* move entry to fill the gap */
 128                         client->buffer[head] = *ev;
 129                 }
 130
 131                 num++;
 132                 head = (head + 1) & mask;
 133
 134                 if (is_report) {
 135                         num = 0;
 136                         client->packet_head = head;
 137                 }
 138         }
 139
 140         client->head = head;
 141 }
 142
 143 static void __evdev_queue_syn_dropped(struct evdev_client *client)
 144 {
 145         ktime_t *ev_time = input_get_timestamp(client->evdev->handle.dev);
 146         struct timespec64 ts = ktime_to_timespec64(ev_time[client->clk_type]);
 147         struct input_event ev;
 148
 149         ev.input_event_sec = ts.tv_sec;
 150         ev.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
 151         ev.type = EV_SYN;
 152         ev.code = SYN_DROPPED;
 153         ev.value = 0;
 154
 155         client->buffer[client->head++] = ev;
 156         client->head &= client->bufsize - 1;
 157
 158         if (unlikely(client->head == client->tail)) {
 159                 /* drop queue but keep our SYN_DROPPED event */
 160                 client->tail = (client->head - 1) & (client->bufsize - 1);
 161                 client->packet_head = client->tail;
 162         }
 163 }
 164
 165 static void evdev_queue_syn_dropped(struct evdev_client *client)
 166 {
 167         unsigned long flags;
 168
 169         spin_lock_irqsave(&client->buffer_lock, flags);
 170         __evdev_queue_syn_dropped(client);
 171         spin_unlock_irqrestore(&client->buffer_lock, flags);
 172 }
 173
 174 static int evdev_set_clk_type(struct evdev_client *client, unsigned int clkid)
 175 {
 176         unsigned long flags;
 177         enum input_clock_type clk_type;
 178
 179         switch (clkid) {
 180
 181         case CLOCK_REALTIME:
 182                 clk_type = INPUT_CLK_REAL;
 183                 break;
 184         case CLOCK_MONOTONIC:
 185                 clk_type = INPUT_CLK_MONO;
 186                 break;
 187         case CLOCK_BOOTTIME:
 188                 clk_type = INPUT_CLK_BOOT;
 189                 break;
 190         default:
 191                 return -EINVAL;
 192         }
 193
 194         if (client->clk_type != clk_type) {
 195                 client->clk_type = clk_type;
 196
 197                 /*
 198                  * Flush pending events and queue SYN_DROPPED event,
 199                  * but only if the queue is not empty.
 200                  */
 201                 spin_lock_irqsave(&client->buffer_lock, flags);
 202
 203                 if (client->head != client->tail) {
 204                         client->packet_head = client->head = client->tail;
 205                         __evdev_queue_syn_dropped(client);
 206                 }
 207
 208                 spin_unlock_irqrestore(&client->buffer_lock, flags);
 209         }
 210
 211         return 0;
 212 }
 213
 214 static void __pass_event(struct evdev_client *client,
 215                          const struct input_event *event)
 216 {
 217         client->buffer[client->head++] = *event;
 218         client->head &= client->bufsize - 1;
 219
 220         if (unlikely(client->head == client->tail)) {
 221                 /*
 222                  * This effectively "drops" all unconsumed events, leaving
 223                  * EV_SYN/SYN_DROPPED plus the newest event in the queue.
 224                  */
 225                 client->tail = (client->head - 2) & (client->bufsize - 1);
 226
 227                 client->buffer[client->tail] = (struct input_event) {
 228                         .input_event_sec = event->input_event_sec,
 229                         .input_event_usec = event->input_event_usec,
 230                         .type = EV_SYN,
 231                         .code = SYN_DROPPED,
 232                         .value = 0,
 233                 };
 234
 235                 client->packet_head = client->tail;
 236         }
 237
 238         if (event->type == EV_SYN && event->code == SYN_REPORT) {
 239                 client->packet_head = client->head;
 240                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
 241         }
 242 }
 243
 244 static void evdev_pass_values(struct evdev_client *client,
 245                         const struct input_value *vals, unsigned int count,
 246                         ktime_t *ev_time)
 247 {
 248         const struct input_value *v;
 249         struct input_event event;
 250         struct timespec64 ts;
 251         bool wakeup = false;
 252
 253         if (client->revoked)
 254                 return;
 255
 256         ts = ktime_to_timespec64(ev_time[client->clk_type]);
 257         event.input_event_sec = ts.tv_sec;
 258         event.input_event_usec = ts.tv_nsec / NSEC_PER_USEC;
 259
 260         /* Interrupts are disabled, just acquire the lock. */
 261         spin_lock(&client->buffer_lock);
 262
 263         for (v = vals; v != vals + count; v++) {
 264                 if (__evdev_is_filtered(client, v->type, v->code))
 265                         continue;
 266
 267                 if (v->type == EV_SYN && v->code == SYN_REPORT) {
 268                         /* drop empty SYN_REPORT */
 269                         if (client->packet_head == client->head)
 270                                 continue;
 271
 272                         wakeup = true;
 273                 }
 274
 275                 event.type = v->type;
 276                 event.code = v->code;
 277                 event.value = v->value;
 278                 __pass_event(client, &event);
 279         }
 280
 281         spin_unlock(&client->buffer_lock);
 282
 283         if (wakeup)
 284                 wake_up_interruptible_poll(&client->wait,
 285                         EPOLLIN | EPOLLOUT | EPOLLRDNORM | EPOLLWRNORM);
 286 }
 287
 288 /*
 289  * Pass incoming events to all connected clients.
 290  */
 291 static void evdev_events(struct input_handle *handle,
 292                          const struct input_value *vals, unsigned int count)
 293 {
 294         struct evdev *evdev = handle->private;
 295         struct evdev_client *client;
 296         ktime_t *ev_time = input_get_timestamp(handle->dev);
 297
 298         rcu_read_lock();
 299
 300         client = rcu_dereference(evdev->grab);
 301
 302         if (client)
 303                 evdev_pass_values(client, vals, count, ev_time);
 304         else
 305                 list_for_each_entry_rcu(client, &evdev->client_list, node)
 306                         evdev_pass_values(client, vals, count, ev_time);
 307
 308         rcu_read_unlock();
 309 }
 310
 311 /*
 312  * Pass incoming event to all connected clients.
 313  */
 314 static void evdev_event(struct input_handle *handle,
 315                         unsigned int type, unsigned int code, int value)
 316 {
 317         struct input_value vals[] = { { type, code, value } };
 318
 319         evdev_events(handle, vals, 1);
 320 }
 321
 322 static int evdev_fasync(int fd, struct file *file, int on)
 323 {
 324         struct evdev_client *client = file->private_data;
 325
 326         return fasync_helper(fd, file, on, &client->fasync);
 327 }
 328
 329 static void evdev_free(struct device *dev)
 330 {
 331         struct evdev *evdev = container_of(dev, struct evdev, dev);
 332
 333         input_put_device(evdev->handle.dev);
 334         kfree(evdev);
 335 }
 336
 337 /*
 338  * Grabs an event device (along with underlying input device).
 339  * This function is called with evdev->mutex taken.
 340  */
 341 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 342 {
 343         int error;
 344
 345         if (evdev->grab)
 346                 return -EBUSY;
 347
 348         error = input_grab_device(&evdev->handle);
 349         if (error)
 350                 return error;
 351
 352         rcu_assign_pointer(evdev->grab, client);
 353
 354         return 0;
 355 }
 356
 357 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 358 {
 359         struct evdev_client *grab = rcu_dereference_protected(evdev->grab,
 360                                         lockdep_is_held(&evdev->mutex));
 361
 362         if (grab != client)
 363                 return  -EINVAL;
 364
 365         rcu_assign_pointer(evdev->grab, NULL);
 366         synchronize_rcu();
 367         input_release_device(&evdev->handle);
 368
 369         return 0;
 370 }
 371
 372 static void evdev_attach_client(struct evdev *evdev,
 373                                 struct evdev_client *client)
 374 {
 375         spin_lock(&evdev->client_lock);
 376         list_add_tail_rcu(&client->node, &evdev->client_list);
 377         spin_unlock(&evdev->client_lock);
 378 }
 379
 380 static void evdev_detach_client(struct evdev *evdev,
 381                                 struct evdev_client *client)
 382 {
 383         spin_lock(&evdev->client_lock);
 384         list_del_rcu(&client->node);
 385         spin_unlock(&evdev->client_lock);
 386         synchronize_rcu();
 387 }
 388
 389 static int evdev_open_device(struct evdev *evdev)
 390 {
 391         int retval;
 392
 393         retval = mutex_lock_interruptible(&evdev->mutex);
 394         if (retval)
 395                 return retval;
 396
 397         if (!evdev->exist)
 398                 retval = -ENODEV;
 399         else if (!evdev->open++) {
 400                 retval = input_open_device(&evdev->handle);
 401                 if (retval)
 402                         evdev->open--;
 403         }
 404
 405         mutex_unlock(&evdev->mutex);
 406         return retval;
 407 }
 408
 409 static void evdev_close_device(struct evdev *evdev)
 410 {
 411         mutex_lock(&evdev->mutex);
 412
 413         if (evdev->exist && !--evdev->open)
 414                 input_close_device(&evdev->handle);
 415
 416         mutex_unlock(&evdev->mutex);
 417 }
 418
 419 /*
 420  * Wake up users waiting for IO so they can disconnect from
 421  * dead device.
 422  */
 423 static void evdev_hangup(struct evdev *evdev)
 424 {
 425         struct evdev_client *client;
 426
 427         spin_lock(&evdev->client_lock);
 428         list_for_each_entry(client, &evdev->client_list, node) {
 429                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 430                 wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
 431         }
 432         spin_unlock(&evdev->client_lock);
 433 }
 434
 435 static int evdev_release(struct inode *inode, struct file *file)
 436 {
 437         struct evdev_client *client = file->private_data;
 438         struct evdev *evdev = client->evdev;
 439         unsigned int i;
 440
 441         mutex_lock(&evdev->mutex);
 442
 443         if (evdev->exist && !client->revoked)
 444                 input_flush_device(&evdev->handle, file);
 445
 446         evdev_ungrab(evdev, client);
 447         mutex_unlock(&evdev->mutex);
 448
 449         evdev_detach_client(evdev, client);
 450
 451         for (i = 0; i < EV_CNT; ++i)
 452                 bitmap_free(client->evmasks[i]);
 453
 454         kvfree(client);
 455
 456         evdev_close_device(evdev);
 457
 458         return 0;
 459 }
 460
 461 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 462 {
 463         unsigned int n_events =
 464                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 465                     EVDEV_MIN_BUFFER_SIZE);
 466
 467         return roundup_pow_of_two(n_events);
 468 }
 469
 470 static int evdev_open(struct inode *inode, struct file *file)
 471 {
 472         struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
 473         unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 474         struct evdev_client *client;
 475         int error;
 476
 477         client = kvzalloc(struct_size(client, buffer, bufsize), GFP_KERNEL);
 478         if (!client)
 479                 return -ENOMEM;
 480
 481         init_waitqueue_head(&client->wait);
 482         client->bufsize = bufsize;
 483         spin_lock_init(&client->buffer_lock);
 484         client->evdev = evdev;
 485         evdev_attach_client(evdev, client);
 486
 487         error = evdev_open_device(evdev);
 488         if (error)
 489                 goto err_free_client;
 490
 491         file->private_data = client;
 492         stream_open(inode, file);
 493
 494         return 0;
 495
 496  err_free_client:
 497         evdev_detach_client(evdev, client);
 498         kvfree(client);
 499         return error;
 500 }
 501
 502 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 503                            size_t count, loff_t *ppos)
 504 {
 505         struct evdev_client *client = file->private_data;
 506         struct evdev *evdev = client->evdev;
 507         struct input_event event;
 508         int retval = 0;
 509
 510         if (count != 0 && count < input_event_size())
 511                 return -EINVAL;
 512
 513         retval = mutex_lock_interruptible(&evdev->mutex);
 514         if (retval)
 515                 return retval;
 516
 517         if (!evdev->exist || client->revoked) {
 518                 retval = -ENODEV;
 519                 goto out;
 520         }
 521
 522         while (retval + input_event_size() <= count) {
 523
 524                 if (input_event_from_user(buffer + retval, &event)) {
 525                         retval = -EFAULT;
 526                         goto out;
 527                 }
 528                 retval += input_event_size();
 529
 530                 input_inject_event(&evdev->handle,
 531                                    event.type, event.code, event.value);
 532                 cond_resched();
 533         }
 534
 535  out:
 536         mutex_unlock(&evdev->mutex);
 537         return retval;
 538 }
 539
 540 static int evdev_fetch_next_event(struct evdev_client *client,
 541                                   struct input_event *event)
 542 {
 543         int have_event;
 544
 545         spin_lock_irq(&client->buffer_lock);
 546
 547         have_event = client->packet_head != client->tail;
 548         if (have_event) {
 549                 *event = client->buffer[client->tail++];
 550                 client->tail &= client->bufsize - 1;
 551         }
 552
 553         spin_unlock_irq(&client->buffer_lock);
 554
 555         return have_event;
 556 }
 557
 558 static ssize_t evdev_read(struct file *file, char __user *buffer,
 559                           size_t count, loff_t *ppos)
 560 {
 561         struct evdev_client *client = file->private_data;
 562         struct evdev *evdev = client->evdev;
 563         struct input_event event;
 564         size_t read = 0;
 565         int error;
 566
 567         if (count != 0 && count < input_event_size())
 568                 return -EINVAL;
 569
 570         for (;;) {
 571                 if (!evdev->exist || client->revoked)
 572                         return -ENODEV;
 573
 574                 if (client->packet_head == client->tail &&
 575                     (file->f_flags & O_NONBLOCK))
 576                         return -EAGAIN;
 577
 578                 /*
 579                  * count == 0 is special - no IO is done but we check
 580                  * for error conditions (see above).
 581                  */
 582                 if (count == 0)
 583                         break;
 584
 585                 while (read + input_event_size() <= count &&
 586                        evdev_fetch_next_event(client, &event)) {
 587
 588                         if (input_event_to_user(buffer + read, &event))
 589                                 return -EFAULT;
 590
 591                         read += input_event_size();
 592                 }
 593
 594                 if (read)
 595                         break;
 596
 597                 if (!(file->f_flags & O_NONBLOCK)) {
 598                         error = wait_event_interruptible(client->wait,
 599                                         client->packet_head != client->tail ||
 600                                         !evdev->exist || client->revoked);
 601                         if (error)
 602                                 return error;
 603                 }
 604         }
 605
 606         return read;
 607 }
 608
 609 /* No kernel lock - fine */
 610 static __poll_t evdev_poll(struct file *file, poll_table *wait)
 611 {
 612         struct evdev_client *client = file->private_data;
 613         struct evdev *evdev = client->evdev;
 614         __poll_t mask;
 615
 616         poll_wait(file, &client->wait, wait);
 617
 618         if (evdev->exist && !client->revoked)
 619                 mask = EPOLLOUT | EPOLLWRNORM;
 620         else
 621                 mask = EPOLLHUP | EPOLLERR;
 622
 623         if (client->packet_head != client->tail)
 624                 mask |= EPOLLIN | EPOLLRDNORM;
 625
 626         return mask;
 627 }
 628
 629 #ifdef CONFIG_COMPAT
 630
 631 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 632 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 633
 634 #ifdef __BIG_ENDIAN
 635 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 636                         unsigned int maxlen, void __user *p, int compat)
 637 {
 638         int len, i;
 639
 640         if (compat) {
 641                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 642                 if (len > maxlen)
 643                         len = maxlen;
 644
 645                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 646                         if (copy_to_user((compat_long_t __user *) p + i,
 647                                          (compat_long_t *) bits +
 648                                                 i + 1 - ((i % 2) << 1),
 649                                          sizeof(compat_long_t)))
 650                                 return -EFAULT;
 651         } else {
 652                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 653                 if (len > maxlen)
 654                         len = maxlen;
 655
 656                 if (copy_to_user(p, bits, len))
 657                         return -EFAULT;
 658         }
 659
 660         return len;
 661 }
 662
 663 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 664                           unsigned int maxlen, const void __user *p, int compat)
 665 {
 666         int len, i;
 667
 668         if (compat) {
 669                 if (maxlen % sizeof(compat_long_t))
 670                         return -EINVAL;
 671
 672                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 673                 if (len > maxlen)
 674                         len = maxlen;
 675
 676                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 677                         if (copy_from_user((compat_long_t *) bits +
 678                                                 i + 1 - ((i % 2) << 1),
 679                                            (compat_long_t __user *) p + i,
 680                                            sizeof(compat_long_t)))
 681                                 return -EFAULT;
 682                 if (i % 2)
 683                         *((compat_long_t *) bits + i - 1) = 0;
 684
 685         } else {
 686                 if (maxlen % sizeof(long))
 687                         return -EINVAL;
 688
 689                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 690                 if (len > maxlen)
 691                         len = maxlen;
 692
 693                 if (copy_from_user(bits, p, len))
 694                         return -EFAULT;
 695         }
 696
 697         return len;
 698 }
 699
 700 #else
 701
 702 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 703                         unsigned int maxlen, void __user *p, int compat)
 704 {
 705         int len = compat ?
 706                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 707                         BITS_TO_LONGS(maxbit) * sizeof(long);
 708
 709         if (len > maxlen)
 710                 len = maxlen;
 711
 712         return copy_to_user(p, bits, len) ? -EFAULT : len;
 713 }
 714
 715 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 716                           unsigned int maxlen, const void __user *p, int compat)
 717 {
 718         size_t chunk_size = compat ? sizeof(compat_long_t) : sizeof(long);
 719         int len;
 720
 721         if (maxlen % chunk_size)
 722                 return -EINVAL;
 723
 724         len = compat ? BITS_TO_LONGS_COMPAT(maxbit) : BITS_TO_LONGS(maxbit);
 725         len *= chunk_size;
 726         if (len > maxlen)
 727                 len = maxlen;
 728
 729         return copy_from_user(bits, p, len) ? -EFAULT : len;
 730 }
 731
 732 #endif /* __BIG_ENDIAN */
 733
 734 #else
 735
 736 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 737                         unsigned int maxlen, void __user *p, int compat)
 738 {
 739         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 740
 741         if (len > maxlen)
 742                 len = maxlen;
 743
 744         return copy_to_user(p, bits, len) ? -EFAULT : len;
 745 }
 746
 747 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 748                           unsigned int maxlen, const void __user *p, int compat)
 749 {
 750         int len;
 751
 752         if (maxlen % sizeof(long))
 753                 return -EINVAL;
 754
 755         len = BITS_TO_LONGS(maxbit) * sizeof(long);
 756         if (len > maxlen)
 757                 len = maxlen;
 758
 759         return copy_from_user(bits, p, len) ? -EFAULT : len;
 760 }
 761
 762 #endif /* CONFIG_COMPAT */
 763
 764 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 765 {
 766         int len;
 767
 768         if (!str)
 769                 return -ENOENT;
 770
 771         len = strlen(str) + 1;
 772         if (len > maxlen)
 773                 len = maxlen;
 774
 775         return copy_to_user(p, str, len) ? -EFAULT : len;
 776 }
 777
 778 static int handle_eviocgbit(struct input_dev *dev,
 779                             unsigned int type, unsigned int size,
 780                             void __user *p, int compat_mode)
 781 {
 782         unsigned long *bits;
 783         int len;
 784
 785         switch (type) {
 786
 787         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 788         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 789         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 790         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 791         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 792         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 793         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 794         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 795         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 796         default: return -EINVAL;
 797         }
 798
 799         return bits_to_user(bits, len, size, p, compat_mode);
 800 }
 801
 802 static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)
 803 {
 804         struct input_keymap_entry ke = {
 805                 .len    = sizeof(unsigned int),
 806                 .flags  = 0,
 807         };
 808         int __user *ip = (int __user *)p;
 809         int error;
 810
 811         /* legacy case */
 812         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 813                 return -EFAULT;
 814
 815         error = input_get_keycode(dev, &ke);
 816         if (error)
 817                 return error;
 818
 819         if (put_user(ke.keycode, ip + 1))
 820                 return -EFAULT;
 821
 822         return 0;
 823 }
 824
 825 static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
 826 {
 827         struct input_keymap_entry ke;
 828         int error;
 829
 830         if (copy_from_user(&ke, p, sizeof(ke)))
 831                 return -EFAULT;
 832
 833         error = input_get_keycode(dev, &ke);
 834         if (error)
 835                 return error;
 836
 837         if (copy_to_user(p, &ke, sizeof(ke)))
 838                 return -EFAULT;
 839
 840         return 0;
 841 }
 842
 843 static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)
 844 {
 845         struct input_keymap_entry ke = {
 846                 .len    = sizeof(unsigned int),
 847                 .flags  = 0,
 848         };
 849         int __user *ip = (int __user *)p;
 850
 851         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 852                 return -EFAULT;
 853
 854         if (get_user(ke.keycode, ip + 1))
 855                 return -EFAULT;
 856
 857         return input_set_keycode(dev, &ke);
 858 }
 859
 860 static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 861 {
 862         struct input_keymap_entry ke;
 863
 864         if (copy_from_user(&ke, p, sizeof(ke)))
 865                 return -EFAULT;
 866
 867         if (ke.len > sizeof(ke.scancode))
 868                 return -EINVAL;
 869
 870         return input_set_keycode(dev, &ke);
 871 }
 872
 873 /*
 874  * If we transfer state to the user, we should flush all pending events
 875  * of the same type from the client's queue. Otherwise, they might end up
 876  * with duplicate events, which can screw up client's state tracking.
 877  * If bits_to_user fails after flushing the queue, we queue a SYN_DROPPED
 878  * event so user-space will notice missing events.
 879  *
 880  * LOCKING:
 881  * We need to take event_lock before buffer_lock to avoid dead-locks. But we
 882  * need the even_lock only to guarantee consistent state. We can safely release
 883  * it while flushing the queue. This allows input-core to handle filters while
 884  * we flush the queue.
 885  */
 886 static int evdev_handle_get_val(struct evdev_client *client,
 887                                 struct input_dev *dev, unsigned int type,
 888                                 unsigned long *bits, unsigned int maxbit,
 889                                 unsigned int maxlen, void __user *p,
 890                                 int compat)
 891 {
 892         int ret;
 893         unsigned long *mem;
 894
 895         mem = bitmap_alloc(maxbit, GFP_KERNEL);
 896         if (!mem)
 897                 return -ENOMEM;
 898
 899         spin_lock_irq(&dev->event_lock);
 900         spin_lock(&client->buffer_lock);
 901
 902         bitmap_copy(mem, bits, maxbit);
 903
 904         spin_unlock(&dev->event_lock);
 905
 906         __evdev_flush_queue(client, type);
 907
 908         spin_unlock_irq(&client->buffer_lock);
 909
 910         ret = bits_to_user(mem, maxbit, maxlen, p, compat);
 911         if (ret < 0)
 912                 evdev_queue_syn_dropped(client);
 913
 914         bitmap_free(mem);
 915
 916         return ret;
 917 }
 918
 919 static int evdev_handle_mt_request(struct input_dev *dev,
 920                                    unsigned int size,
 921                                    int __user *ip)
 922 {
 923         const struct input_mt *mt = dev->mt;
 924         unsigned int code;
 925         int max_slots;
 926         int i;
 927
 928         if (get_user(code, &ip[0]))
 929                 return -EFAULT;
 930         if (!mt || !input_is_mt_value(code))
 931                 return -EINVAL;
 932
 933         max_slots = (size - sizeof(__u32)) / sizeof(__s32);
 934         for (i = 0; i < mt->num_slots && i < max_slots; i++) {
 935                 int value = input_mt_get_value(&mt->slots[i], code);
 936                 if (put_user(value, &ip[1 + i]))
 937                         return -EFAULT;
 938         }
 939
 940         return 0;
 941 }
 942
 943 static int evdev_revoke(struct evdev *evdev, struct evdev_client *client,
 944                         struct file *file)
 945 {
 946         client->revoked = true;
 947         evdev_ungrab(evdev, client);
 948         input_flush_device(&evdev->handle, file);
 949         wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
 950
 951         return 0;
 952 }
 953
 954 /* must be called with evdev-mutex held */
 955 static int evdev_set_mask(struct evdev_client *client,
 956                           unsigned int type,
 957                           const void __user *codes,
 958                           u32 codes_size,
 959                           int compat)
 960 {
 961         unsigned long flags, *mask, *oldmask;
 962         size_t cnt;
 963         int error;
 964
 965         /* we allow unknown types and 'codes_size > size' for forward-compat */
 966         cnt = evdev_get_mask_cnt(type);
 967         if (!cnt)
 968                 return 0;
 969
 970         mask = bitmap_zalloc(cnt, GFP_KERNEL);
 971         if (!mask)
 972                 return -ENOMEM;
 973
 974         error = bits_from_user(mask, cnt - 1, codes_size, codes, compat);
 975         if (error < 0) {
 976                 bitmap_free(mask);
 977                 return error;
 978         }
 979
 980         spin_lock_irqsave(&client->buffer_lock, flags);
 981         oldmask = client->evmasks[type];
 982         client->evmasks[type] = mask;
 983         spin_unlock_irqrestore(&client->buffer_lock, flags);
 984
 985         bitmap_free(oldmask);
 986
 987         return 0;
 988 }
 989
 990 /* must be called with evdev-mutex held */
 991 static int evdev_get_mask(struct evdev_client *client,
 992                           unsigned int type,
 993                           void __user *codes,
 994                           u32 codes_size,
 995                           int compat)
 996 {
 997         unsigned long *mask;
 998         size_t cnt, size, xfer_size;
 999         int i;
1000         int error;
1001
1002         /* we allow unknown types and 'codes_size > size' for forward-compat */
1003         cnt = evdev_get_mask_cnt(type);
1004         size = sizeof(unsigned long) * BITS_TO_LONGS(cnt);
1005         xfer_size = min_t(size_t, codes_size, size);
1006
1007         if (cnt > 0) {
1008                 mask = client->evmasks[type];
1009                 if (mask) {
1010                         error = bits_to_user(mask, cnt - 1,
1011                                              xfer_size, codes, compat);
1012                         if (error < 0)
1013                                 return error;
1014                 } else {
1015                         /* fake mask with all bits set */
1016                         for (i = 0; i < xfer_size; i++)
1017                                 if (put_user(0xffU, (u8 __user *)codes + i))
1018                                         return -EFAULT;
1019                 }
1020         }
1021
1022         if (xfer_size < codes_size)
1023                 if (clear_user(codes + xfer_size, codes_size - xfer_size))
1024                         return -EFAULT;
1025
1026         return 0;
1027 }
1028
1029 static long evdev_do_ioctl(struct file *file, unsigned int cmd,
1030                            void __user *p, int compat_mode)
1031 {
1032         struct evdev_client *client = file->private_data;
1033         struct evdev *evdev = client->evdev;
1034         struct input_dev *dev = evdev->handle.dev;
1035         struct input_absinfo abs;
1036         struct input_mask mask;
1037         struct ff_effect effect;
1038         int __user *ip = (int __user *)p;
1039         unsigned int i, t, u, v;
1040         unsigned int size;
1041         int error;
1042
1043         /* First we check for fixed-length commands */
1044         switch (cmd) {
1045
1046         case EVIOCGVERSION:
1047                 return put_user(EV_VERSION, ip);
1048
1049         case EVIOCGID:
1050                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
1051                         return -EFAULT;
1052                 return 0;
1053
1054         case EVIOCGREP:
1055                 if (!test_bit(EV_REP, dev->evbit))
1056                         return -ENOSYS;
1057                 if (put_user(dev->rep[REP_DELAY], ip))
1058                         return -EFAULT;
1059                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
1060                         return -EFAULT;
1061                 return 0;
1062
1063         case EVIOCSREP:
1064                 if (!test_bit(EV_REP, dev->evbit))
1065                         return -ENOSYS;
1066                 if (get_user(u, ip))
1067                         return -EFAULT;
1068                 if (get_user(v, ip + 1))
1069                         return -EFAULT;
1070
1071                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
1072                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
1073
1074                 return 0;
1075
1076         case EVIOCRMFF:
1077                 return input_ff_erase(dev, (int)(unsigned long) p, file);
1078
1079         case EVIOCGEFFECTS:
1080                 i = test_bit(EV_FF, dev->evbit) ?
1081                                 dev->ff->max_effects : 0;
1082                 if (put_user(i, ip))
1083                         return -EFAULT;
1084                 return 0;
1085
1086         case EVIOCGRAB:
1087                 if (p)
1088                         return evdev_grab(evdev, client);
1089                 else
1090                         return evdev_ungrab(evdev, client);
1091
1092         case EVIOCREVOKE:
1093                 if (p)
1094                         return -EINVAL;
1095                 else
1096                         return evdev_revoke(evdev, client, file);
1097
1098         case EVIOCGMASK: {
1099                 void __user *codes_ptr;
1100
1101                 if (copy_from_user(&mask, p, sizeof(mask)))
1102                         return -EFAULT;
1103
1104                 codes_ptr = (void __user *)(unsigned long)mask.codes_ptr;
1105                 return evdev_get_mask(client,
1106                                       mask.type, codes_ptr, mask.codes_size,
1107                                       compat_mode);
1108         }
1109
1110         case EVIOCSMASK: {
1111                 const void __user *codes_ptr;
1112
1113                 if (copy_from_user(&mask, p, sizeof(mask)))
1114                         return -EFAULT;
1115
1116                 codes_ptr = (const void __user *)(unsigned long)mask.codes_ptr;
1117                 return evdev_set_mask(client,
1118                                       mask.type, codes_ptr, mask.codes_size,
1119                                       compat_mode);
1120         }
1121
1122         case EVIOCSCLOCKID:
1123                 if (copy_from_user(&i, p, sizeof(unsigned int)))
1124                         return -EFAULT;
1125
1126                 return evdev_set_clk_type(client, i);
1127
1128         case EVIOCGKEYCODE:
1129                 return evdev_handle_get_keycode(dev, p);
1130
1131         case EVIOCSKEYCODE:
1132                 return evdev_handle_set_keycode(dev, p);
1133
1134         case EVIOCGKEYCODE_V2:
1135                 return evdev_handle_get_keycode_v2(dev, p);
1136
1137         case EVIOCSKEYCODE_V2:
1138                 return evdev_handle_set_keycode_v2(dev, p);
1139         }
1140
1141         size = _IOC_SIZE(cmd);
1142
1143         /* Now check variable-length commands */
1144 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
1145         switch (EVIOC_MASK_SIZE(cmd)) {
1146
1147         case EVIOCGPROP(0):
1148                 return bits_to_user(dev->propbit, INPUT_PROP_MAX,
1149                                     size, p, compat_mode);
1150
1151         case EVIOCGMTSLOTS(0):
1152                 return evdev_handle_mt_request(dev, size, ip);
1153
1154         case EVIOCGKEY(0):
1155                 return evdev_handle_get_val(client, dev, EV_KEY, dev->key,
1156                                             KEY_MAX, size, p, compat_mode);
1157
1158         case EVIOCGLED(0):
1159                 return evdev_handle_get_val(client, dev, EV_LED, dev->led,
1160                                             LED_MAX, size, p, compat_mode);
1161
1162         case EVIOCGSND(0):
1163                 return evdev_handle_get_val(client, dev, EV_SND, dev->snd,
1164                                             SND_MAX, size, p, compat_mode);
1165
1166         case EVIOCGSW(0):
1167                 return evdev_handle_get_val(client, dev, EV_SW, dev->sw,
1168                                             SW_MAX, size, p, compat_mode);
1169
1170         case EVIOCGNAME(0):
1171                 return str_to_user(dev->name, size, p);
1172
1173         case EVIOCGPHYS(0):
1174                 return str_to_user(dev->phys, size, p);
1175
1176         case EVIOCGUNIQ(0):
1177                 return str_to_user(dev->uniq, size, p);
1178
1179         case EVIOC_MASK_SIZE(EVIOCSFF):
1180                 if (input_ff_effect_from_user(p, size, &effect))
1181                         return -EFAULT;
1182
1183                 error = input_ff_upload(dev, &effect, file);
1184                 if (error)
1185                         return error;
1186
1187                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
1188                         return -EFAULT;
1189
1190                 return 0;
1191         }
1192
1193         /* Multi-number variable-length handlers */
1194         if (_IOC_TYPE(cmd) != 'E')
1195                 return -EINVAL;
1196
1197         if (_IOC_DIR(cmd) == _IOC_READ) {
1198
1199                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
1200                         return handle_eviocgbit(dev,
1201                                                 _IOC_NR(cmd) & EV_MAX, size,
1202                                                 p, compat_mode);
1203
1204                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
1205
1206                         if (!dev->absinfo)
1207                                 return -EINVAL;
1208
1209                         t = _IOC_NR(cmd) & ABS_MAX;
1210                         abs = dev->absinfo[t];
1211
1212                         if (copy_to_user(p, &abs, min_t(size_t,
1213                                         size, sizeof(struct input_absinfo))))
1214                                 return -EFAULT;
1215
1216                         return 0;
1217                 }
1218         }
1219
1220         if (_IOC_DIR(cmd) == _IOC_WRITE) {
1221
1222                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
1223
1224                         if (!dev->absinfo)
1225                                 return -EINVAL;
1226
1227                         t = _IOC_NR(cmd) & ABS_MAX;
1228
1229                         if (copy_from_user(&abs, p, min_t(size_t,
1230                                         size, sizeof(struct input_absinfo))))
1231                                 return -EFAULT;
1232
1233                         if (size < sizeof(struct input_absinfo))
1234                                 abs.resolution = 0;
1235
1236                         /* We can't change number of reserved MT slots */
1237                         if (t == ABS_MT_SLOT)
1238                                 return -EINVAL;
1239
1240                         /*
1241                          * Take event lock to ensure that we are not
1242                          * changing device parameters in the middle
1243                          * of event.
1244                          */
1245                         spin_lock_irq(&dev->event_lock);
1246                         dev->absinfo[t] = abs;
1247                         spin_unlock_irq(&dev->event_lock);
1248
1249                         return 0;
1250                 }
1251         }
1252
1253         return -EINVAL;
1254 }
1255
1256 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
1257                                 void __user *p, int compat_mode)
1258 {
1259         struct evdev_client *client = file->private_data;
1260         struct evdev *evdev = client->evdev;
1261         int retval;
1262
1263         retval = mutex_lock_interruptible(&evdev->mutex);
1264         if (retval)
1265                 return retval;
1266
1267         if (!evdev->exist || client->revoked) {
1268                 retval = -ENODEV;
1269                 goto out;
1270         }
1271
1272         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
1273
1274  out:
1275         mutex_unlock(&evdev->mutex);
1276         return retval;
1277 }
1278
1279 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1280 {
1281         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
1282 }
1283
1284 #ifdef CONFIG_COMPAT
1285 static long evdev_ioctl_compat(struct file *file,
1286                                 unsigned int cmd, unsigned long arg)
1287 {
1288         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
1289 }
1290 #endif
1291
1292 static const struct file_operations evdev_fops = {
1293         .owner          = THIS_MODULE,
1294         .read           = evdev_read,
1295         .write          = evdev_write,
1296         .poll           = evdev_poll,
1297         .open           = evdev_open,
1298         .release        = evdev_release,
1299         .unlocked_ioctl = evdev_ioctl,
1300 #ifdef CONFIG_COMPAT
1301         .compat_ioctl   = evdev_ioctl_compat,
1302 #endif
1303         .fasync         = evdev_fasync,
1304         .llseek         = no_llseek,
1305 };
1306
1307 /*
1308  * Mark device non-existent. This disables writes, ioctls and
1309  * prevents new users from opening the device. Already posted
1310  * blocking reads will stay, however new ones will fail.
1311  */
1312 static void evdev_mark_dead(struct evdev *evdev)
1313 {
1314         mutex_lock(&evdev->mutex);
1315         evdev->exist = false;
1316         mutex_unlock(&evdev->mutex);
1317 }
1318
1319 static void evdev_cleanup(struct evdev *evdev)
1320 {
1321         struct input_handle *handle = &evdev->handle;
1322
1323         evdev_mark_dead(evdev);
1324         evdev_hangup(evdev);
1325
1326         /* evdev is marked dead so no one else accesses evdev->open */
1327         if (evdev->open) {
1328                 input_flush_device(handle, NULL);
1329                 input_close_device(handle);
1330         }
1331 }
1332
1333 /*
1334  * Create new evdev device. Note that input core serializes calls
1335  * to connect and disconnect.
1336  */
1337 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
1338                          const struct input_device_id *id)
1339 {
1340         struct evdev *evdev;
1341         int minor;
1342         int dev_no;
1343         int error;
1344
1345         minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
1346         if (minor < 0) {
1347                 error = minor;
1348                 pr_err("failed to reserve new minor: %d\n", error);
1349                 return error;
1350         }
1351
1352         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
1353         if (!evdev) {
1354                 error = -ENOMEM;
1355                 goto err_free_minor;
1356         }
1357
1358         INIT_LIST_HEAD(&evdev->client_list);
1359         spin_lock_init(&evdev->client_lock);
1360         mutex_init(&evdev->mutex);
1361         evdev->exist = true;
1362
1363         dev_no = minor;
1364         /* Normalize device number if it falls into legacy range */
1365         if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
1366                 dev_no -= EVDEV_MINOR_BASE;
1367         dev_set_name(&evdev->dev, "event%d", dev_no);
1368
1369         evdev->handle.dev = input_get_device(dev);
1370         evdev->handle.name = dev_name(&evdev->dev);
1371         evdev->handle.handler = handler;
1372         evdev->handle.private = evdev;
1373
1374         evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
1375         evdev->dev.class = &input_class;
1376         evdev->dev.parent = &dev->dev;
1377         evdev->dev.release = evdev_free;
1378         device_initialize(&evdev->dev);
1379
1380         error = input_register_handle(&evdev->handle);
1381         if (error)
1382                 goto err_free_evdev;
1383
1384         cdev_init(&evdev->cdev, &evdev_fops);
1385
1386         error = cdev_device_add(&evdev->cdev, &evdev->dev);
1387         if (error)
1388                 goto err_cleanup_evdev;
1389
1390         return 0;
1391
1392  err_cleanup_evdev:
1393         evdev_cleanup(evdev);
1394         input_unregister_handle(&evdev->handle);
1395  err_free_evdev:
1396         put_device(&evdev->dev);
1397  err_free_minor:
1398         input_free_minor(minor);
1399         return error;
1400 }
1401
1402 static void evdev_disconnect(struct input_handle *handle)
1403 {
1404         struct evdev *evdev = handle->private;
1405
1406         cdev_device_del(&evdev->cdev, &evdev->dev);
1407         evdev_cleanup(evdev);
1408         input_free_minor(MINOR(evdev->dev.devt));
1409         input_unregister_handle(handle);
1410         put_device(&evdev->dev);
1411 }
1412
1413 static const struct input_device_id evdev_ids[] = {
1414         { .driver_info = 1 },   /* Matches all devices */
1415         { },                    /* Terminating zero entry */
1416 };
1417
1418 MODULE_DEVICE_TABLE(input, evdev_ids);
1419
1420 static struct input_handler evdev_handler = {
1421         .event          = evdev_event,
1422         .events         = evdev_events,
1423         .connect        = evdev_connect,
1424         .disconnect     = evdev_disconnect,
1425         .legacy_minors  = true,
1426         .minor          = EVDEV_MINOR_BASE,
1427         .name           = "evdev",
1428         .id_table       = evdev_ids,
1429 };
1430
1431 static int __init evdev_init(void)
1432 {
1433         return input_register_handler(&evdev_handler);
1434 }
1435
1436 static void __exit evdev_exit(void)
1437 {
1438         input_unregister_handler(&evdev_handler);
1439 }
1440
1441 module_init(evdev_init);
1442 module_exit(evdev_exit);
1443
1444 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
1445 MODULE_DESCRIPTION("Input driver event char devices");
1446 MODULE_LICENSE("GPL");