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[] __counted_by(bufsize);
  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 unsigned int evdev_events(struct input_handle *handle,
 292                                  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         return count;
 311 }
 312
 313 static int evdev_fasync(int fd, struct file *file, int on)
 314 {
 315         struct evdev_client *client = file->private_data;
 316
 317         return fasync_helper(fd, file, on, &client->fasync);
 318 }
 319
 320 static void evdev_free(struct device *dev)
 321 {
 322         struct evdev *evdev = container_of(dev, struct evdev, dev);
 323
 324         input_put_device(evdev->handle.dev);
 325         kfree(evdev);
 326 }
 327
 328 /*
 329  * Grabs an event device (along with underlying input device).
 330  * This function is called with evdev->mutex taken.
 331  */
 332 static int evdev_grab(struct evdev *evdev, struct evdev_client *client)
 333 {
 334         int error;
 335
 336         if (evdev->grab)
 337                 return -EBUSY;
 338
 339         error = input_grab_device(&evdev->handle);
 340         if (error)
 341                 return error;
 342
 343         rcu_assign_pointer(evdev->grab, client);
 344
 345         return 0;
 346 }
 347
 348 static int evdev_ungrab(struct evdev *evdev, struct evdev_client *client)
 349 {
 350         struct evdev_client *grab = rcu_dereference_protected(evdev->grab,
 351                                         lockdep_is_held(&evdev->mutex));
 352
 353         if (grab != client)
 354                 return  -EINVAL;
 355
 356         rcu_assign_pointer(evdev->grab, NULL);
 357         synchronize_rcu();
 358         input_release_device(&evdev->handle);
 359
 360         return 0;
 361 }
 362
 363 static void evdev_attach_client(struct evdev *evdev,
 364                                 struct evdev_client *client)
 365 {
 366         spin_lock(&evdev->client_lock);
 367         list_add_tail_rcu(&client->node, &evdev->client_list);
 368         spin_unlock(&evdev->client_lock);
 369 }
 370
 371 static void evdev_detach_client(struct evdev *evdev,
 372                                 struct evdev_client *client)
 373 {
 374         spin_lock(&evdev->client_lock);
 375         list_del_rcu(&client->node);
 376         spin_unlock(&evdev->client_lock);
 377         synchronize_rcu();
 378 }
 379
 380 static int evdev_open_device(struct evdev *evdev)
 381 {
 382         int retval;
 383
 384         retval = mutex_lock_interruptible(&evdev->mutex);
 385         if (retval)
 386                 return retval;
 387
 388         if (!evdev->exist)
 389                 retval = -ENODEV;
 390         else if (!evdev->open++) {
 391                 retval = input_open_device(&evdev->handle);
 392                 if (retval)
 393                         evdev->open--;
 394         }
 395
 396         mutex_unlock(&evdev->mutex);
 397         return retval;
 398 }
 399
 400 static void evdev_close_device(struct evdev *evdev)
 401 {
 402         mutex_lock(&evdev->mutex);
 403
 404         if (evdev->exist && !--evdev->open)
 405                 input_close_device(&evdev->handle);
 406
 407         mutex_unlock(&evdev->mutex);
 408 }
 409
 410 /*
 411  * Wake up users waiting for IO so they can disconnect from
 412  * dead device.
 413  */
 414 static void evdev_hangup(struct evdev *evdev)
 415 {
 416         struct evdev_client *client;
 417
 418         spin_lock(&evdev->client_lock);
 419         list_for_each_entry(client, &evdev->client_list, node) {
 420                 kill_fasync(&client->fasync, SIGIO, POLL_HUP);
 421                 wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
 422         }
 423         spin_unlock(&evdev->client_lock);
 424 }
 425
 426 static int evdev_release(struct inode *inode, struct file *file)
 427 {
 428         struct evdev_client *client = file->private_data;
 429         struct evdev *evdev = client->evdev;
 430         unsigned int i;
 431
 432         mutex_lock(&evdev->mutex);
 433
 434         if (evdev->exist && !client->revoked)
 435                 input_flush_device(&evdev->handle, file);
 436
 437         evdev_ungrab(evdev, client);
 438         mutex_unlock(&evdev->mutex);
 439
 440         evdev_detach_client(evdev, client);
 441
 442         for (i = 0; i < EV_CNT; ++i)
 443                 bitmap_free(client->evmasks[i]);
 444
 445         kvfree(client);
 446
 447         evdev_close_device(evdev);
 448
 449         return 0;
 450 }
 451
 452 static unsigned int evdev_compute_buffer_size(struct input_dev *dev)
 453 {
 454         unsigned int n_events =
 455                 max(dev->hint_events_per_packet * EVDEV_BUF_PACKETS,
 456                     EVDEV_MIN_BUFFER_SIZE);
 457
 458         return roundup_pow_of_two(n_events);
 459 }
 460
 461 static int evdev_open(struct inode *inode, struct file *file)
 462 {
 463         struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
 464         unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
 465         struct evdev_client *client;
 466         int error;
 467
 468         client = kvzalloc(struct_size(client, buffer, bufsize), GFP_KERNEL);
 469         if (!client)
 470                 return -ENOMEM;
 471
 472         init_waitqueue_head(&client->wait);
 473         client->bufsize = bufsize;
 474         spin_lock_init(&client->buffer_lock);
 475         client->evdev = evdev;
 476         evdev_attach_client(evdev, client);
 477
 478         error = evdev_open_device(evdev);
 479         if (error)
 480                 goto err_free_client;
 481
 482         file->private_data = client;
 483         stream_open(inode, file);
 484
 485         return 0;
 486
 487  err_free_client:
 488         evdev_detach_client(evdev, client);
 489         kvfree(client);
 490         return error;
 491 }
 492
 493 static ssize_t evdev_write(struct file *file, const char __user *buffer,
 494                            size_t count, loff_t *ppos)
 495 {
 496         struct evdev_client *client = file->private_data;
 497         struct evdev *evdev = client->evdev;
 498         struct input_event event;
 499         int retval = 0;
 500
 501         /*
 502          * Limit amount of data we inject into the input subsystem so that
 503          * we do not hold evdev->mutex for too long. 4096 bytes corresponds
 504          * to 170 input events.
 505          */
 506         count = min(count, 4096);
 507
 508         if (count != 0 && count < input_event_size())
 509                 return -EINVAL;
 510
 511         retval = mutex_lock_interruptible(&evdev->mutex);
 512         if (retval)
 513                 return retval;
 514
 515         if (!evdev->exist || client->revoked) {
 516                 retval = -ENODEV;
 517                 goto out;
 518         }
 519
 520         while (retval + input_event_size() <= count) {
 521
 522                 if (input_event_from_user(buffer + retval, &event)) {
 523                         retval = -EFAULT;
 524                         goto out;
 525                 }
 526                 retval += input_event_size();
 527
 528                 input_inject_event(&evdev->handle,
 529                                    event.type, event.code, event.value);
 530                 cond_resched();
 531         }
 532
 533  out:
 534         mutex_unlock(&evdev->mutex);
 535         return retval;
 536 }
 537
 538 static int evdev_fetch_next_event(struct evdev_client *client,
 539                                   struct input_event *event)
 540 {
 541         int have_event;
 542
 543         spin_lock_irq(&client->buffer_lock);
 544
 545         have_event = client->packet_head != client->tail;
 546         if (have_event) {
 547                 *event = client->buffer[client->tail++];
 548                 client->tail &= client->bufsize - 1;
 549         }
 550
 551         spin_unlock_irq(&client->buffer_lock);
 552
 553         return have_event;
 554 }
 555
 556 static ssize_t evdev_read(struct file *file, char __user *buffer,
 557                           size_t count, loff_t *ppos)
 558 {
 559         struct evdev_client *client = file->private_data;
 560         struct evdev *evdev = client->evdev;
 561         struct input_event event;
 562         size_t read = 0;
 563         int error;
 564
 565         if (count != 0 && count < input_event_size())
 566                 return -EINVAL;
 567
 568         for (;;) {
 569                 if (!evdev->exist || client->revoked)
 570                         return -ENODEV;
 571
 572                 if (client->packet_head == client->tail &&
 573                     (file->f_flags & O_NONBLOCK))
 574                         return -EAGAIN;
 575
 576                 /*
 577                  * count == 0 is special - no IO is done but we check
 578                  * for error conditions (see above).
 579                  */
 580                 if (count == 0)
 581                         break;
 582
 583                 while (read + input_event_size() <= count &&
 584                        evdev_fetch_next_event(client, &event)) {
 585
 586                         if (input_event_to_user(buffer + read, &event))
 587                                 return -EFAULT;
 588
 589                         read += input_event_size();
 590                 }
 591
 592                 if (read)
 593                         break;
 594
 595                 if (!(file->f_flags & O_NONBLOCK)) {
 596                         error = wait_event_interruptible(client->wait,
 597                                         client->packet_head != client->tail ||
 598                                         !evdev->exist || client->revoked);
 599                         if (error)
 600                                 return error;
 601                 }
 602         }
 603
 604         return read;
 605 }
 606
 607 /* No kernel lock - fine */
 608 static __poll_t evdev_poll(struct file *file, poll_table *wait)
 609 {
 610         struct evdev_client *client = file->private_data;
 611         struct evdev *evdev = client->evdev;
 612         __poll_t mask;
 613
 614         poll_wait(file, &client->wait, wait);
 615
 616         if (evdev->exist && !client->revoked)
 617                 mask = EPOLLOUT | EPOLLWRNORM;
 618         else
 619                 mask = EPOLLHUP | EPOLLERR;
 620
 621         if (client->packet_head != client->tail)
 622                 mask |= EPOLLIN | EPOLLRDNORM;
 623
 624         return mask;
 625 }
 626
 627 #ifdef CONFIG_COMPAT
 628
 629 #define BITS_PER_LONG_COMPAT (sizeof(compat_long_t) * 8)
 630 #define BITS_TO_LONGS_COMPAT(x) ((((x) - 1) / BITS_PER_LONG_COMPAT) + 1)
 631
 632 #ifdef __BIG_ENDIAN
 633 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 634                         unsigned int maxlen, void __user *p, int compat)
 635 {
 636         int len, i;
 637
 638         if (compat) {
 639                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 640                 if (len > maxlen)
 641                         len = maxlen;
 642
 643                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 644                         if (copy_to_user((compat_long_t __user *) p + i,
 645                                          (compat_long_t *) bits +
 646                                                 i + 1 - ((i % 2) << 1),
 647                                          sizeof(compat_long_t)))
 648                                 return -EFAULT;
 649         } else {
 650                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 651                 if (len > maxlen)
 652                         len = maxlen;
 653
 654                 if (copy_to_user(p, bits, len))
 655                         return -EFAULT;
 656         }
 657
 658         return len;
 659 }
 660
 661 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 662                           unsigned int maxlen, const void __user *p, int compat)
 663 {
 664         int len, i;
 665
 666         if (compat) {
 667                 if (maxlen % sizeof(compat_long_t))
 668                         return -EINVAL;
 669
 670                 len = BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t);
 671                 if (len > maxlen)
 672                         len = maxlen;
 673
 674                 for (i = 0; i < len / sizeof(compat_long_t); i++)
 675                         if (copy_from_user((compat_long_t *) bits +
 676                                                 i + 1 - ((i % 2) << 1),
 677                                            (compat_long_t __user *) p + i,
 678                                            sizeof(compat_long_t)))
 679                                 return -EFAULT;
 680                 if (i % 2)
 681                         *((compat_long_t *) bits + i - 1) = 0;
 682
 683         } else {
 684                 if (maxlen % sizeof(long))
 685                         return -EINVAL;
 686
 687                 len = BITS_TO_LONGS(maxbit) * sizeof(long);
 688                 if (len > maxlen)
 689                         len = maxlen;
 690
 691                 if (copy_from_user(bits, p, len))
 692                         return -EFAULT;
 693         }
 694
 695         return len;
 696 }
 697
 698 #else
 699
 700 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 701                         unsigned int maxlen, void __user *p, int compat)
 702 {
 703         int len = compat ?
 704                         BITS_TO_LONGS_COMPAT(maxbit) * sizeof(compat_long_t) :
 705                         BITS_TO_LONGS(maxbit) * sizeof(long);
 706
 707         if (len > maxlen)
 708                 len = maxlen;
 709
 710         return copy_to_user(p, bits, len) ? -EFAULT : len;
 711 }
 712
 713 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 714                           unsigned int maxlen, const void __user *p, int compat)
 715 {
 716         size_t chunk_size = compat ? sizeof(compat_long_t) : sizeof(long);
 717         int len;
 718
 719         if (maxlen % chunk_size)
 720                 return -EINVAL;
 721
 722         len = compat ? BITS_TO_LONGS_COMPAT(maxbit) : BITS_TO_LONGS(maxbit);
 723         len *= chunk_size;
 724         if (len > maxlen)
 725                 len = maxlen;
 726
 727         return copy_from_user(bits, p, len) ? -EFAULT : len;
 728 }
 729
 730 #endif /* __BIG_ENDIAN */
 731
 732 #else
 733
 734 static int bits_to_user(unsigned long *bits, unsigned int maxbit,
 735                         unsigned int maxlen, void __user *p, int compat)
 736 {
 737         int len = BITS_TO_LONGS(maxbit) * sizeof(long);
 738
 739         if (len > maxlen)
 740                 len = maxlen;
 741
 742         return copy_to_user(p, bits, len) ? -EFAULT : len;
 743 }
 744
 745 static int bits_from_user(unsigned long *bits, unsigned int maxbit,
 746                           unsigned int maxlen, const void __user *p, int compat)
 747 {
 748         int len;
 749
 750         if (maxlen % sizeof(long))
 751                 return -EINVAL;
 752
 753         len = BITS_TO_LONGS(maxbit) * sizeof(long);
 754         if (len > maxlen)
 755                 len = maxlen;
 756
 757         return copy_from_user(bits, p, len) ? -EFAULT : len;
 758 }
 759
 760 #endif /* CONFIG_COMPAT */
 761
 762 static int str_to_user(const char *str, unsigned int maxlen, void __user *p)
 763 {
 764         int len;
 765
 766         if (!str)
 767                 return -ENOENT;
 768
 769         len = strlen(str) + 1;
 770         if (len > maxlen)
 771                 len = maxlen;
 772
 773         return copy_to_user(p, str, len) ? -EFAULT : len;
 774 }
 775
 776 static int handle_eviocgbit(struct input_dev *dev,
 777                             unsigned int type, unsigned int size,
 778                             void __user *p, int compat_mode)
 779 {
 780         unsigned long *bits;
 781         int len;
 782
 783         switch (type) {
 784
 785         case      0: bits = dev->evbit;  len = EV_MAX;  break;
 786         case EV_KEY: bits = dev->keybit; len = KEY_MAX; break;
 787         case EV_REL: bits = dev->relbit; len = REL_MAX; break;
 788         case EV_ABS: bits = dev->absbit; len = ABS_MAX; break;
 789         case EV_MSC: bits = dev->mscbit; len = MSC_MAX; break;
 790         case EV_LED: bits = dev->ledbit; len = LED_MAX; break;
 791         case EV_SND: bits = dev->sndbit; len = SND_MAX; break;
 792         case EV_FF:  bits = dev->ffbit;  len = FF_MAX;  break;
 793         case EV_SW:  bits = dev->swbit;  len = SW_MAX;  break;
 794         default: return -EINVAL;
 795         }
 796
 797         return bits_to_user(bits, len, size, p, compat_mode);
 798 }
 799
 800 static int evdev_handle_get_keycode(struct input_dev *dev, void __user *p)
 801 {
 802         struct input_keymap_entry ke = {
 803                 .len    = sizeof(unsigned int),
 804                 .flags  = 0,
 805         };
 806         int __user *ip = (int __user *)p;
 807         int error;
 808
 809         /* legacy case */
 810         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 811                 return -EFAULT;
 812
 813         error = input_get_keycode(dev, &ke);
 814         if (error)
 815                 return error;
 816
 817         if (put_user(ke.keycode, ip + 1))
 818                 return -EFAULT;
 819
 820         return 0;
 821 }
 822
 823 static int evdev_handle_get_keycode_v2(struct input_dev *dev, void __user *p)
 824 {
 825         struct input_keymap_entry ke;
 826         int error;
 827
 828         if (copy_from_user(&ke, p, sizeof(ke)))
 829                 return -EFAULT;
 830
 831         error = input_get_keycode(dev, &ke);
 832         if (error)
 833                 return error;
 834
 835         if (copy_to_user(p, &ke, sizeof(ke)))
 836                 return -EFAULT;
 837
 838         return 0;
 839 }
 840
 841 static int evdev_handle_set_keycode(struct input_dev *dev, void __user *p)
 842 {
 843         struct input_keymap_entry ke = {
 844                 .len    = sizeof(unsigned int),
 845                 .flags  = 0,
 846         };
 847         int __user *ip = (int __user *)p;
 848
 849         if (copy_from_user(ke.scancode, p, sizeof(unsigned int)))
 850                 return -EFAULT;
 851
 852         if (get_user(ke.keycode, ip + 1))
 853                 return -EFAULT;
 854
 855         return input_set_keycode(dev, &ke);
 856 }
 857
 858 static int evdev_handle_set_keycode_v2(struct input_dev *dev, void __user *p)
 859 {
 860         struct input_keymap_entry ke;
 861
 862         if (copy_from_user(&ke, p, sizeof(ke)))
 863                 return -EFAULT;
 864
 865         if (ke.len > sizeof(ke.scancode))
 866                 return -EINVAL;
 867
 868         return input_set_keycode(dev, &ke);
 869 }
 870
 871 /*
 872  * If we transfer state to the user, we should flush all pending events
 873  * of the same type from the client's queue. Otherwise, they might end up
 874  * with duplicate events, which can screw up client's state tracking.
 875  * If bits_to_user fails after flushing the queue, we queue a SYN_DROPPED
 876  * event so user-space will notice missing events.
 877  *
 878  * LOCKING:
 879  * We need to take event_lock before buffer_lock to avoid dead-locks. But we
 880  * need the even_lock only to guarantee consistent state. We can safely release
 881  * it while flushing the queue. This allows input-core to handle filters while
 882  * we flush the queue.
 883  */
 884 static int evdev_handle_get_val(struct evdev_client *client,
 885                                 struct input_dev *dev, unsigned int type,
 886                                 unsigned long *bits, unsigned int maxbit,
 887                                 unsigned int maxlen, void __user *p,
 888                                 int compat)
 889 {
 890         int ret;
 891         unsigned long *mem;
 892
 893         mem = bitmap_alloc(maxbit, GFP_KERNEL);
 894         if (!mem)
 895                 return -ENOMEM;
 896
 897         spin_lock_irq(&dev->event_lock);
 898         spin_lock(&client->buffer_lock);
 899
 900         bitmap_copy(mem, bits, maxbit);
 901
 902         spin_unlock(&dev->event_lock);
 903
 904         __evdev_flush_queue(client, type);
 905
 906         spin_unlock_irq(&client->buffer_lock);
 907
 908         ret = bits_to_user(mem, maxbit, maxlen, p, compat);
 909         if (ret < 0)
 910                 evdev_queue_syn_dropped(client);
 911
 912         bitmap_free(mem);
 913
 914         return ret;
 915 }
 916
 917 static int evdev_handle_mt_request(struct input_dev *dev,
 918                                    unsigned int size,
 919                                    int __user *ip)
 920 {
 921         const struct input_mt *mt = dev->mt;
 922         unsigned int code;
 923         int max_slots;
 924         int i;
 925
 926         if (get_user(code, &ip[0]))
 927                 return -EFAULT;
 928         if (!mt || !input_is_mt_value(code))
 929                 return -EINVAL;
 930
 931         max_slots = (size - sizeof(__u32)) / sizeof(__s32);
 932         for (i = 0; i < mt->num_slots && i < max_slots; i++) {
 933                 int value = input_mt_get_value(&mt->slots[i], code);
 934                 if (put_user(value, &ip[1 + i]))
 935                         return -EFAULT;
 936         }
 937
 938         return 0;
 939 }
 940
 941 static int evdev_revoke(struct evdev *evdev, struct evdev_client *client,
 942                         struct file *file)
 943 {
 944         client->revoked = true;
 945         evdev_ungrab(evdev, client);
 946         input_flush_device(&evdev->handle, file);
 947         wake_up_interruptible_poll(&client->wait, EPOLLHUP | EPOLLERR);
 948
 949         return 0;
 950 }
 951
 952 /* must be called with evdev-mutex held */
 953 static int evdev_set_mask(struct evdev_client *client,
 954                           unsigned int type,
 955                           const void __user *codes,
 956                           u32 codes_size,
 957                           int compat)
 958 {
 959         unsigned long flags, *mask, *oldmask;
 960         size_t cnt;
 961         int error;
 962
 963         /* we allow unknown types and 'codes_size > size' for forward-compat */
 964         cnt = evdev_get_mask_cnt(type);
 965         if (!cnt)
 966                 return 0;
 967
 968         mask = bitmap_zalloc(cnt, GFP_KERNEL);
 969         if (!mask)
 970                 return -ENOMEM;
 971
 972         error = bits_from_user(mask, cnt - 1, codes_size, codes, compat);
 973         if (error < 0) {
 974                 bitmap_free(mask);
 975                 return error;
 976         }
 977
 978         spin_lock_irqsave(&client->buffer_lock, flags);
 979         oldmask = client->evmasks[type];
 980         client->evmasks[type] = mask;
 981         spin_unlock_irqrestore(&client->buffer_lock, flags);
 982
 983         bitmap_free(oldmask);
 984
 985         return 0;
 986 }
 987
 988 /* must be called with evdev-mutex held */
 989 static int evdev_get_mask(struct evdev_client *client,
 990                           unsigned int type,
 991                           void __user *codes,
 992                           u32 codes_size,
 993                           int compat)
 994 {
 995         unsigned long *mask;
 996         size_t cnt, size, xfer_size;
 997         int i;
 998         int error;
 999
1000         /* we allow unknown types and 'codes_size > size' for forward-compat */
1001         cnt = evdev_get_mask_cnt(type);
1002         size = sizeof(unsigned long) * BITS_TO_LONGS(cnt);
1003         xfer_size = min_t(size_t, codes_size, size);
1004
1005         if (cnt > 0) {
1006                 mask = client->evmasks[type];
1007                 if (mask) {
1008                         error = bits_to_user(mask, cnt - 1,
1009                                              xfer_size, codes, compat);
1010                         if (error < 0)
1011                                 return error;
1012                 } else {
1013                         /* fake mask with all bits set */
1014                         for (i = 0; i < xfer_size; i++)
1015                                 if (put_user(0xffU, (u8 __user *)codes + i))
1016                                         return -EFAULT;
1017                 }
1018         }
1019
1020         if (xfer_size < codes_size)
1021                 if (clear_user(codes + xfer_size, codes_size - xfer_size))
1022                         return -EFAULT;
1023
1024         return 0;
1025 }
1026
1027 static long evdev_do_ioctl(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         struct input_dev *dev = evdev->handle.dev;
1033         struct input_absinfo abs;
1034         struct input_mask mask;
1035         struct ff_effect effect;
1036         int __user *ip = (int __user *)p;
1037         unsigned int i, t, u, v;
1038         unsigned int size;
1039         int error;
1040
1041         /* First we check for fixed-length commands */
1042         switch (cmd) {
1043
1044         case EVIOCGVERSION:
1045                 return put_user(EV_VERSION, ip);
1046
1047         case EVIOCGID:
1048                 if (copy_to_user(p, &dev->id, sizeof(struct input_id)))
1049                         return -EFAULT;
1050                 return 0;
1051
1052         case EVIOCGREP:
1053                 if (!test_bit(EV_REP, dev->evbit))
1054                         return -ENOSYS;
1055                 if (put_user(dev->rep[REP_DELAY], ip))
1056                         return -EFAULT;
1057                 if (put_user(dev->rep[REP_PERIOD], ip + 1))
1058                         return -EFAULT;
1059                 return 0;
1060
1061         case EVIOCSREP:
1062                 if (!test_bit(EV_REP, dev->evbit))
1063                         return -ENOSYS;
1064                 if (get_user(u, ip))
1065                         return -EFAULT;
1066                 if (get_user(v, ip + 1))
1067                         return -EFAULT;
1068
1069                 input_inject_event(&evdev->handle, EV_REP, REP_DELAY, u);
1070                 input_inject_event(&evdev->handle, EV_REP, REP_PERIOD, v);
1071
1072                 return 0;
1073
1074         case EVIOCRMFF:
1075                 return input_ff_erase(dev, (int)(unsigned long) p, file);
1076
1077         case EVIOCGEFFECTS:
1078                 i = test_bit(EV_FF, dev->evbit) ?
1079                                 dev->ff->max_effects : 0;
1080                 if (put_user(i, ip))
1081                         return -EFAULT;
1082                 return 0;
1083
1084         case EVIOCGRAB:
1085                 if (p)
1086                         return evdev_grab(evdev, client);
1087                 else
1088                         return evdev_ungrab(evdev, client);
1089
1090         case EVIOCREVOKE:
1091                 if (p)
1092                         return -EINVAL;
1093                 else
1094                         return evdev_revoke(evdev, client, file);
1095
1096         case EVIOCGMASK: {
1097                 void __user *codes_ptr;
1098
1099                 if (copy_from_user(&mask, p, sizeof(mask)))
1100                         return -EFAULT;
1101
1102                 codes_ptr = (void __user *)(unsigned long)mask.codes_ptr;
1103                 return evdev_get_mask(client,
1104                                       mask.type, codes_ptr, mask.codes_size,
1105                                       compat_mode);
1106         }
1107
1108         case EVIOCSMASK: {
1109                 const void __user *codes_ptr;
1110
1111                 if (copy_from_user(&mask, p, sizeof(mask)))
1112                         return -EFAULT;
1113
1114                 codes_ptr = (const void __user *)(unsigned long)mask.codes_ptr;
1115                 return evdev_set_mask(client,
1116                                       mask.type, codes_ptr, mask.codes_size,
1117                                       compat_mode);
1118         }
1119
1120         case EVIOCSCLOCKID:
1121                 if (copy_from_user(&i, p, sizeof(unsigned int)))
1122                         return -EFAULT;
1123
1124                 return evdev_set_clk_type(client, i);
1125
1126         case EVIOCGKEYCODE:
1127                 return evdev_handle_get_keycode(dev, p);
1128
1129         case EVIOCSKEYCODE:
1130                 return evdev_handle_set_keycode(dev, p);
1131
1132         case EVIOCGKEYCODE_V2:
1133                 return evdev_handle_get_keycode_v2(dev, p);
1134
1135         case EVIOCSKEYCODE_V2:
1136                 return evdev_handle_set_keycode_v2(dev, p);
1137         }
1138
1139         size = _IOC_SIZE(cmd);
1140
1141         /* Now check variable-length commands */
1142 #define EVIOC_MASK_SIZE(nr)     ((nr) & ~(_IOC_SIZEMASK << _IOC_SIZESHIFT))
1143         switch (EVIOC_MASK_SIZE(cmd)) {
1144
1145         case EVIOCGPROP(0):
1146                 return bits_to_user(dev->propbit, INPUT_PROP_MAX,
1147                                     size, p, compat_mode);
1148
1149         case EVIOCGMTSLOTS(0):
1150                 return evdev_handle_mt_request(dev, size, ip);
1151
1152         case EVIOCGKEY(0):
1153                 return evdev_handle_get_val(client, dev, EV_KEY, dev->key,
1154                                             KEY_MAX, size, p, compat_mode);
1155
1156         case EVIOCGLED(0):
1157                 return evdev_handle_get_val(client, dev, EV_LED, dev->led,
1158                                             LED_MAX, size, p, compat_mode);
1159
1160         case EVIOCGSND(0):
1161                 return evdev_handle_get_val(client, dev, EV_SND, dev->snd,
1162                                             SND_MAX, size, p, compat_mode);
1163
1164         case EVIOCGSW(0):
1165                 return evdev_handle_get_val(client, dev, EV_SW, dev->sw,
1166                                             SW_MAX, size, p, compat_mode);
1167
1168         case EVIOCGNAME(0):
1169                 return str_to_user(dev->name, size, p);
1170
1171         case EVIOCGPHYS(0):
1172                 return str_to_user(dev->phys, size, p);
1173
1174         case EVIOCGUNIQ(0):
1175                 return str_to_user(dev->uniq, size, p);
1176
1177         case EVIOC_MASK_SIZE(EVIOCSFF):
1178                 if (input_ff_effect_from_user(p, size, &effect))
1179                         return -EFAULT;
1180
1181                 error = input_ff_upload(dev, &effect, file);
1182                 if (error)
1183                         return error;
1184
1185                 if (put_user(effect.id, &(((struct ff_effect __user *)p)->id)))
1186                         return -EFAULT;
1187
1188                 return 0;
1189         }
1190
1191         /* Multi-number variable-length handlers */
1192         if (_IOC_TYPE(cmd) != 'E')
1193                 return -EINVAL;
1194
1195         if (_IOC_DIR(cmd) == _IOC_READ) {
1196
1197                 if ((_IOC_NR(cmd) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
1198                         return handle_eviocgbit(dev,
1199                                                 _IOC_NR(cmd) & EV_MAX, size,
1200                                                 p, compat_mode);
1201
1202                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0))) {
1203
1204                         if (!dev->absinfo)
1205                                 return -EINVAL;
1206
1207                         t = _IOC_NR(cmd) & ABS_MAX;
1208                         abs = dev->absinfo[t];
1209
1210                         if (copy_to_user(p, &abs, min_t(size_t,
1211                                         size, sizeof(struct input_absinfo))))
1212                                 return -EFAULT;
1213
1214                         return 0;
1215                 }
1216         }
1217
1218         if (_IOC_DIR(cmd) == _IOC_WRITE) {
1219
1220                 if ((_IOC_NR(cmd) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0))) {
1221
1222                         if (!dev->absinfo)
1223                                 return -EINVAL;
1224
1225                         t = _IOC_NR(cmd) & ABS_MAX;
1226
1227                         if (copy_from_user(&abs, p, min_t(size_t,
1228                                         size, sizeof(struct input_absinfo))))
1229                                 return -EFAULT;
1230
1231                         if (size < sizeof(struct input_absinfo))
1232                                 abs.resolution = 0;
1233
1234                         /* We can't change number of reserved MT slots */
1235                         if (t == ABS_MT_SLOT)
1236                                 return -EINVAL;
1237
1238                         /*
1239                          * Take event lock to ensure that we are not
1240                          * changing device parameters in the middle
1241                          * of event.
1242                          */
1243                         spin_lock_irq(&dev->event_lock);
1244                         dev->absinfo[t] = abs;
1245                         spin_unlock_irq(&dev->event_lock);
1246
1247                         return 0;
1248                 }
1249         }
1250
1251         return -EINVAL;
1252 }
1253
1254 static long evdev_ioctl_handler(struct file *file, unsigned int cmd,
1255                                 void __user *p, int compat_mode)
1256 {
1257         struct evdev_client *client = file->private_data;
1258         struct evdev *evdev = client->evdev;
1259         int retval;
1260
1261         retval = mutex_lock_interruptible(&evdev->mutex);
1262         if (retval)
1263                 return retval;
1264
1265         if (!evdev->exist || client->revoked) {
1266                 retval = -ENODEV;
1267                 goto out;
1268         }
1269
1270         retval = evdev_do_ioctl(file, cmd, p, compat_mode);
1271
1272  out:
1273         mutex_unlock(&evdev->mutex);
1274         return retval;
1275 }
1276
1277 static long evdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1278 {
1279         return evdev_ioctl_handler(file, cmd, (void __user *)arg, 0);
1280 }
1281
1282 #ifdef CONFIG_COMPAT
1283 static long evdev_ioctl_compat(struct file *file,
1284                                 unsigned int cmd, unsigned long arg)
1285 {
1286         return evdev_ioctl_handler(file, cmd, compat_ptr(arg), 1);
1287 }
1288 #endif
1289
1290 static const struct file_operations evdev_fops = {
1291         .owner          = THIS_MODULE,
1292         .read           = evdev_read,
1293         .write          = evdev_write,
1294         .poll           = evdev_poll,
1295         .open           = evdev_open,
1296         .release        = evdev_release,
1297         .unlocked_ioctl = evdev_ioctl,
1298 #ifdef CONFIG_COMPAT
1299         .compat_ioctl   = evdev_ioctl_compat,
1300 #endif
1301         .fasync         = evdev_fasync,
1302 };
1303
1304 /*
1305  * Mark device non-existent. This disables writes, ioctls and
1306  * prevents new users from opening the device. Already posted
1307  * blocking reads will stay, however new ones will fail.
1308  */
1309 static void evdev_mark_dead(struct evdev *evdev)
1310 {
1311         mutex_lock(&evdev->mutex);
1312         evdev->exist = false;
1313         mutex_unlock(&evdev->mutex);
1314 }
1315
1316 static void evdev_cleanup(struct evdev *evdev)
1317 {
1318         struct input_handle *handle = &evdev->handle;
1319
1320         evdev_mark_dead(evdev);
1321         evdev_hangup(evdev);
1322
1323         /* evdev is marked dead so no one else accesses evdev->open */
1324         if (evdev->open) {
1325                 input_flush_device(handle, NULL);
1326                 input_close_device(handle);
1327         }
1328 }
1329
1330 /*
1331  * Create new evdev device. Note that input core serializes calls
1332  * to connect and disconnect.
1333  */
1334 static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
1335                          const struct input_device_id *id)
1336 {
1337         struct evdev *evdev;
1338         int minor;
1339         int dev_no;
1340         int error;
1341
1342         minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
1343         if (minor < 0) {
1344                 error = minor;
1345                 pr_err("failed to reserve new minor: %d\n", error);
1346                 return error;
1347         }
1348
1349         evdev = kzalloc(sizeof(struct evdev), GFP_KERNEL);
1350         if (!evdev) {
1351                 error = -ENOMEM;
1352                 goto err_free_minor;
1353         }
1354
1355         INIT_LIST_HEAD(&evdev->client_list);
1356         spin_lock_init(&evdev->client_lock);
1357         mutex_init(&evdev->mutex);
1358         evdev->exist = true;
1359
1360         dev_no = minor;
1361         /* Normalize device number if it falls into legacy range */
1362         if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
1363                 dev_no -= EVDEV_MINOR_BASE;
1364         dev_set_name(&evdev->dev, "event%d", dev_no);
1365
1366         evdev->handle.dev = input_get_device(dev);
1367         evdev->handle.name = dev_name(&evdev->dev);
1368         evdev->handle.handler = handler;
1369         evdev->handle.private = evdev;
1370
1371         evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
1372         evdev->dev.class = &input_class;
1373         evdev->dev.parent = &dev->dev;
1374         evdev->dev.release = evdev_free;
1375         device_initialize(&evdev->dev);
1376
1377         error = input_register_handle(&evdev->handle);
1378         if (error)
1379                 goto err_free_evdev;
1380
1381         cdev_init(&evdev->cdev, &evdev_fops);
1382
1383         error = cdev_device_add(&evdev->cdev, &evdev->dev);
1384         if (error)
1385                 goto err_cleanup_evdev;
1386
1387         return 0;
1388
1389  err_cleanup_evdev:
1390         evdev_cleanup(evdev);
1391         input_unregister_handle(&evdev->handle);
1392  err_free_evdev:
1393         put_device(&evdev->dev);
1394  err_free_minor:
1395         input_free_minor(minor);
1396         return error;
1397 }
1398
1399 static void evdev_disconnect(struct input_handle *handle)
1400 {
1401         struct evdev *evdev = handle->private;
1402
1403         cdev_device_del(&evdev->cdev, &evdev->dev);
1404         evdev_cleanup(evdev);
1405         input_free_minor(MINOR(evdev->dev.devt));
1406         input_unregister_handle(handle);
1407         put_device(&evdev->dev);
1408 }
1409
1410 static const struct input_device_id evdev_ids[] = {
1411         { .driver_info = 1 },   /* Matches all devices */
1412         { },                    /* Terminating zero entry */
1413 };
1414
1415 MODULE_DEVICE_TABLE(input, evdev_ids);
1416
1417 static struct input_handler evdev_handler = {
1418         .events         = evdev_events,
1419         .connect        = evdev_connect,
1420         .disconnect     = evdev_disconnect,
1421         .legacy_minors  = true,
1422         .minor          = EVDEV_MINOR_BASE,
1423         .name           = "evdev",
1424         .id_table       = evdev_ids,
1425 };
1426
1427 static int __init evdev_init(void)
1428 {
1429         return input_register_handler(&evdev_handler);
1430 }
1431
1432 static void __exit evdev_exit(void)
1433 {
1434         input_unregister_handler(&evdev_handler);
1435 }
1436
1437 module_init(evdev_init);
1438 module_exit(evdev_exit);
1439
1440 MODULE_AUTHOR("Vojtech Pavlik <[email protected]>");
1441 MODULE_DESCRIPTION("Input driver event char devices");
1442 MODULE_LICENSE("GPL");