drivers/hid/hidraw.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * HID raw devices, giving access to raw HID events.
   4  *
   5  * In comparison to hiddev, this device does not process the
   6  * hid events at all (no parsing, no lookups). This lets applications
   7  * to work on raw hid events as they want to, and avoids a need to
   8  * use a transport-specific userspace libhid/libusb libraries.
   9  *
  10  *  Copyright (c) 2007-2014 Jiri Kosina
  11  */
  12
  13
  14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/fs.h>
  17 #include <linux/module.h>
  18 #include <linux/errno.h>
  19 #include <linux/kernel.h>
  20 #include <linux/init.h>
  21 #include <linux/cdev.h>
  22 #include <linux/poll.h>
  23 #include <linux/device.h>
  24 #include <linux/major.h>
  25 #include <linux/slab.h>
  26 #include <linux/hid.h>
  27 #include <linux/mutex.h>
  28 #include <linux/sched/signal.h>
  29 #include <linux/string.h>
  30
  31 #include <linux/hidraw.h>
  32
  33 static int hidraw_major;
  34 static struct cdev hidraw_cdev;
  35 static const struct class hidraw_class = {
  36         .name = "hidraw",
  37 };
  38 static struct hidraw *hidraw_table[HIDRAW_MAX_DEVICES];
  39 static DECLARE_RWSEM(minors_rwsem);
  40
  41 static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
  42 {
  43         struct hidraw_list *list = file->private_data;
  44         int ret = 0, len;
  45         DECLARE_WAITQUEUE(wait, current);
  46
  47         mutex_lock(&list->read_mutex);
  48
  49         while (ret == 0) {
  50                 if (list->head == list->tail) {
  51                         add_wait_queue(&list->hidraw->wait, &wait);
  52                         set_current_state(TASK_INTERRUPTIBLE);
  53
  54                         while (list->head == list->tail) {
  55                                 if (signal_pending(current)) {
  56                                         ret = -ERESTARTSYS;
  57                                         break;
  58                                 }
  59                                 if (!list->hidraw->exist) {
  60                                         ret = -EIO;
  61                                         break;
  62                                 }
  63                                 if (file->f_flags & O_NONBLOCK) {
  64                                         ret = -EAGAIN;
  65                                         break;
  66                                 }
  67
  68                                 /* allow O_NONBLOCK to work well from other threads */
  69                                 mutex_unlock(&list->read_mutex);
  70                                 schedule();
  71                                 mutex_lock(&list->read_mutex);
  72                                 set_current_state(TASK_INTERRUPTIBLE);
  73                         }
  74
  75                         set_current_state(TASK_RUNNING);
  76                         remove_wait_queue(&list->hidraw->wait, &wait);
  77                 }
  78
  79                 if (ret)
  80                         goto out;
  81
  82                 len = list->buffer[list->tail].len > count ?
  83                         count : list->buffer[list->tail].len;
  84
  85                 if (list->buffer[list->tail].value) {
  86                         if (copy_to_user(buffer, list->buffer[list->tail].value, len)) {
  87                                 ret = -EFAULT;
  88                                 goto out;
  89                         }
  90                         ret = len;
  91                 }
  92
  93                 kfree(list->buffer[list->tail].value);
  94                 list->buffer[list->tail].value = NULL;
  95                 list->tail = (list->tail + 1) & (HIDRAW_BUFFER_SIZE - 1);
  96         }
  97 out:
  98         mutex_unlock(&list->read_mutex);
  99         return ret;
 100 }
 101
 102 /*
 103  * The first byte of the report buffer is expected to be a report number.
 104  */
 105 static ssize_t hidraw_send_report(struct file *file, const char __user *buffer, size_t count, unsigned char report_type)
 106 {
 107         unsigned int minor = iminor(file_inode(file));
 108         struct hid_device *dev;
 109         __u8 *buf;
 110         int ret = 0;
 111
 112         lockdep_assert_held(&minors_rwsem);
 113
 114         if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
 115                 ret = -ENODEV;
 116                 goto out;
 117         }
 118
 119         dev = hidraw_table[minor]->hid;
 120
 121         if (count > HID_MAX_BUFFER_SIZE) {
 122                 hid_warn(dev, "pid %d passed too large report\n",
 123                          task_pid_nr(current));
 124                 ret = -EINVAL;
 125                 goto out;
 126         }
 127
 128         if (count < 2) {
 129                 hid_warn(dev, "pid %d passed too short report\n",
 130                          task_pid_nr(current));
 131                 ret = -EINVAL;
 132                 goto out;
 133         }
 134
 135         buf = memdup_user(buffer, count);
 136         if (IS_ERR(buf)) {
 137                 ret = PTR_ERR(buf);
 138                 goto out;
 139         }
 140
 141         if ((report_type == HID_OUTPUT_REPORT) &&
 142             !(dev->quirks & HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP)) {
 143                 ret = hid_hw_output_report(dev, buf, count);
 144                 /*
 145                  * compatibility with old implementation of USB-HID and I2C-HID:
 146                  * if the device does not support receiving output reports,
 147                  * on an interrupt endpoint, fallback to SET_REPORT HID command.
 148                  */
 149                 if (ret != -ENOSYS)
 150                         goto out_free;
 151         }
 152
 153         ret = hid_hw_raw_request(dev, buf[0], buf, count, report_type,
 154                                 HID_REQ_SET_REPORT);
 155
 156 out_free:
 157         kfree(buf);
 158 out:
 159         return ret;
 160 }
 161
 162 static ssize_t hidraw_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 163 {
 164         ssize_t ret;
 165         down_read(&minors_rwsem);
 166         ret = hidraw_send_report(file, buffer, count, HID_OUTPUT_REPORT);
 167         up_read(&minors_rwsem);
 168         return ret;
 169 }
 170
 171
 172 /*
 173  * This function performs a Get_Report transfer over the control endpoint
 174  * per section 7.2.1 of the HID specification, version 1.1.  The first byte
 175  * of buffer is the report number to request, or 0x0 if the device does not
 176  * use numbered reports. The report_type parameter can be HID_FEATURE_REPORT
 177  * or HID_INPUT_REPORT.
 178  */
 179 static ssize_t hidraw_get_report(struct file *file, char __user *buffer, size_t count, unsigned char report_type)
 180 {
 181         unsigned int minor = iminor(file_inode(file));
 182         struct hid_device *dev;
 183         __u8 *buf;
 184         int ret = 0, len;
 185         unsigned char report_number;
 186
 187         lockdep_assert_held(&minors_rwsem);
 188
 189         if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
 190                 ret = -ENODEV;
 191                 goto out;
 192         }
 193
 194         dev = hidraw_table[minor]->hid;
 195
 196         if (!dev->ll_driver->raw_request) {
 197                 ret = -ENODEV;
 198                 goto out;
 199         }
 200
 201         if (count > HID_MAX_BUFFER_SIZE) {
 202                 hid_warn(dev, "pid %d passed too large report\n",
 203                         task_pid_nr(current));
 204                 ret = -EINVAL;
 205                 goto out;
 206         }
 207
 208         if (count < 2) {
 209                 hid_warn(dev, "pid %d passed too short report\n",
 210                         task_pid_nr(current));
 211                 ret = -EINVAL;
 212                 goto out;
 213         }
 214
 215         buf = kmalloc(count, GFP_KERNEL);
 216         if (!buf) {
 217                 ret = -ENOMEM;
 218                 goto out;
 219         }
 220
 221         /*
 222          * Read the first byte from the user. This is the report number,
 223          * which is passed to hid_hw_raw_request().
 224          */
 225         if (copy_from_user(&report_number, buffer, 1)) {
 226                 ret = -EFAULT;
 227                 goto out_free;
 228         }
 229
 230         ret = hid_hw_raw_request(dev, report_number, buf, count, report_type,
 231                                  HID_REQ_GET_REPORT);
 232
 233         if (ret < 0)
 234                 goto out_free;
 235
 236         len = (ret < count) ? ret : count;
 237
 238         if (copy_to_user(buffer, buf, len)) {
 239                 ret = -EFAULT;
 240                 goto out_free;
 241         }
 242
 243         ret = len;
 244
 245 out_free:
 246         kfree(buf);
 247 out:
 248         return ret;
 249 }
 250
 251 static __poll_t hidraw_poll(struct file *file, poll_table *wait)
 252 {
 253         struct hidraw_list *list = file->private_data;
 254         __poll_t mask = EPOLLOUT | EPOLLWRNORM; /* hidraw is always writable */
 255
 256         poll_wait(file, &list->hidraw->wait, wait);
 257         if (list->head != list->tail)
 258                 mask |= EPOLLIN | EPOLLRDNORM;
 259         if (!list->hidraw->exist)
 260                 mask |= EPOLLERR | EPOLLHUP;
 261         return mask;
 262 }
 263
 264 static int hidraw_open(struct inode *inode, struct file *file)
 265 {
 266         unsigned int minor = iminor(inode);
 267         struct hidraw *dev;
 268         struct hidraw_list *list;
 269         unsigned long flags;
 270         int err = 0;
 271
 272         if (!(list = kzalloc(sizeof(struct hidraw_list), GFP_KERNEL))) {
 273                 err = -ENOMEM;
 274                 goto out;
 275         }
 276
 277         /*
 278          * Technically not writing to the hidraw_table but a write lock is
 279          * required to protect the device refcount. This is symmetrical to
 280          * hidraw_release().
 281          */
 282         down_write(&minors_rwsem);
 283         if (!hidraw_table[minor] || !hidraw_table[minor]->exist) {
 284                 err = -ENODEV;
 285                 goto out_unlock;
 286         }
 287
 288         dev = hidraw_table[minor];
 289         if (!dev->open++) {
 290                 err = hid_hw_power(dev->hid, PM_HINT_FULLON);
 291                 if (err < 0) {
 292                         dev->open--;
 293                         goto out_unlock;
 294                 }
 295
 296                 err = hid_hw_open(dev->hid);
 297                 if (err < 0) {
 298                         hid_hw_power(dev->hid, PM_HINT_NORMAL);
 299                         dev->open--;
 300                         goto out_unlock;
 301                 }
 302         }
 303
 304         list->hidraw = hidraw_table[minor];
 305         mutex_init(&list->read_mutex);
 306         spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
 307         list_add_tail(&list->node, &hidraw_table[minor]->list);
 308         spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
 309         file->private_data = list;
 310 out_unlock:
 311         up_write(&minors_rwsem);
 312 out:
 313         if (err < 0)
 314                 kfree(list);
 315         return err;
 316
 317 }
 318
 319 static int hidraw_fasync(int fd, struct file *file, int on)
 320 {
 321         struct hidraw_list *list = file->private_data;
 322
 323         return fasync_helper(fd, file, on, &list->fasync);
 324 }
 325
 326 static void drop_ref(struct hidraw *hidraw, int exists_bit)
 327 {
 328         if (exists_bit) {
 329                 hidraw->exist = 0;
 330                 if (hidraw->open) {
 331                         hid_hw_close(hidraw->hid);
 332                         wake_up_interruptible(&hidraw->wait);
 333                 }
 334                 device_destroy(&hidraw_class,
 335                                MKDEV(hidraw_major, hidraw->minor));
 336         } else {
 337                 --hidraw->open;
 338         }
 339         if (!hidraw->open) {
 340                 if (!hidraw->exist) {
 341                         hidraw_table[hidraw->minor] = NULL;
 342                         kfree(hidraw);
 343                 } else {
 344                         /* close device for last reader */
 345                         hid_hw_close(hidraw->hid);
 346                         hid_hw_power(hidraw->hid, PM_HINT_NORMAL);
 347                 }
 348         }
 349 }
 350
 351 static int hidraw_release(struct inode * inode, struct file * file)
 352 {
 353         unsigned int minor = iminor(inode);
 354         struct hidraw_list *list = file->private_data;
 355         unsigned long flags;
 356
 357         down_write(&minors_rwsem);
 358
 359         spin_lock_irqsave(&hidraw_table[minor]->list_lock, flags);
 360         for (int i = list->tail; i < list->head; i++)
 361                 kfree(list->buffer[i].value);
 362         list_del(&list->node);
 363         spin_unlock_irqrestore(&hidraw_table[minor]->list_lock, flags);
 364         kfree(list);
 365
 366         drop_ref(hidraw_table[minor], 0);
 367
 368         up_write(&minors_rwsem);
 369         return 0;
 370 }
 371
 372 static long hidraw_ioctl(struct file *file, unsigned int cmd,
 373                                                         unsigned long arg)
 374 {
 375         struct inode *inode = file_inode(file);
 376         unsigned int minor = iminor(inode);
 377         long ret = 0;
 378         struct hidraw *dev;
 379         void __user *user_arg = (void __user*) arg;
 380
 381         down_read(&minors_rwsem);
 382         dev = hidraw_table[minor];
 383         if (!dev || !dev->exist) {
 384                 ret = -ENODEV;
 385                 goto out;
 386         }
 387
 388         switch (cmd) {
 389                 case HIDIOCGRDESCSIZE:
 390                         if (put_user(dev->hid->rsize, (int __user *)arg))
 391                                 ret = -EFAULT;
 392                         break;
 393
 394                 case HIDIOCGRDESC:
 395                         {
 396                                 __u32 len;
 397
 398                                 if (get_user(len, (int __user *)arg))
 399                                         ret = -EFAULT;
 400                                 else if (len > HID_MAX_DESCRIPTOR_SIZE - 1)
 401                                         ret = -EINVAL;
 402                                 else if (copy_to_user(user_arg + offsetof(
 403                                         struct hidraw_report_descriptor,
 404                                         value[0]),
 405                                         dev->hid->rdesc,
 406                                         min(dev->hid->rsize, len)))
 407                                         ret = -EFAULT;
 408                                 break;
 409                         }
 410                 case HIDIOCGRAWINFO:
 411                         {
 412                                 struct hidraw_devinfo dinfo;
 413
 414                                 dinfo.bustype = dev->hid->bus;
 415                                 dinfo.vendor = dev->hid->vendor;
 416                                 dinfo.product = dev->hid->product;
 417                                 if (copy_to_user(user_arg, &dinfo, sizeof(dinfo)))
 418                                         ret = -EFAULT;
 419                                 break;
 420                         }
 421                 default:
 422                         {
 423                                 struct hid_device *hid = dev->hid;
 424                                 if (_IOC_TYPE(cmd) != 'H') {
 425                                         ret = -EINVAL;
 426                                         break;
 427                                 }
 428
 429                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSFEATURE(0))) {
 430                                         int len = _IOC_SIZE(cmd);
 431                                         ret = hidraw_send_report(file, user_arg, len, HID_FEATURE_REPORT);
 432                                         break;
 433                                 }
 434                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGFEATURE(0))) {
 435                                         int len = _IOC_SIZE(cmd);
 436                                         ret = hidraw_get_report(file, user_arg, len, HID_FEATURE_REPORT);
 437                                         break;
 438                                 }
 439
 440                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSINPUT(0))) {
 441                                         int len = _IOC_SIZE(cmd);
 442                                         ret = hidraw_send_report(file, user_arg, len, HID_INPUT_REPORT);
 443                                         break;
 444                                 }
 445                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGINPUT(0))) {
 446                                         int len = _IOC_SIZE(cmd);
 447                                         ret = hidraw_get_report(file, user_arg, len, HID_INPUT_REPORT);
 448                                         break;
 449                                 }
 450
 451                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCSOUTPUT(0))) {
 452                                         int len = _IOC_SIZE(cmd);
 453                                         ret = hidraw_send_report(file, user_arg, len, HID_OUTPUT_REPORT);
 454                                         break;
 455                                 }
 456                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGOUTPUT(0))) {
 457                                         int len = _IOC_SIZE(cmd);
 458                                         ret = hidraw_get_report(file, user_arg, len, HID_OUTPUT_REPORT);
 459                                         break;
 460                                 }
 461
 462                                 /* Begin Read-only ioctls. */
 463                                 if (_IOC_DIR(cmd) != _IOC_READ) {
 464                                         ret = -EINVAL;
 465                                         break;
 466                                 }
 467
 468                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWNAME(0))) {
 469                                         int len = strlen(hid->name) + 1;
 470                                         if (len > _IOC_SIZE(cmd))
 471                                                 len = _IOC_SIZE(cmd);
 472                                         ret = copy_to_user(user_arg, hid->name, len) ?
 473                                                 -EFAULT : len;
 474                                         break;
 475                                 }
 476
 477                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWPHYS(0))) {
 478                                         int len = strlen(hid->phys) + 1;
 479                                         if (len > _IOC_SIZE(cmd))
 480                                                 len = _IOC_SIZE(cmd);
 481                                         ret = copy_to_user(user_arg, hid->phys, len) ?
 482                                                 -EFAULT : len;
 483                                         break;
 484                                 }
 485
 486                                 if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGRAWUNIQ(0))) {
 487                                         int len = strlen(hid->uniq) + 1;
 488                                         if (len > _IOC_SIZE(cmd))
 489                                                 len = _IOC_SIZE(cmd);
 490                                         ret = copy_to_user(user_arg, hid->uniq, len) ?
 491                                                 -EFAULT : len;
 492                                         break;
 493                                 }
 494                         }
 495
 496                 ret = -ENOTTY;
 497         }
 498 out:
 499         up_read(&minors_rwsem);
 500         return ret;
 501 }
 502
 503 static const struct file_operations hidraw_ops = {
 504         .owner =        THIS_MODULE,
 505         .read =         hidraw_read,
 506         .write =        hidraw_write,
 507         .poll =         hidraw_poll,
 508         .open =         hidraw_open,
 509         .release =      hidraw_release,
 510         .unlocked_ioctl = hidraw_ioctl,
 511         .fasync =       hidraw_fasync,
 512         .compat_ioctl   = compat_ptr_ioctl,
 513         .llseek =       noop_llseek,
 514 };
 515
 516 int hidraw_report_event(struct hid_device *hid, u8 *data, int len)
 517 {
 518         struct hidraw *dev = hid->hidraw;
 519         struct hidraw_list *list;
 520         int ret = 0;
 521         unsigned long flags;
 522
 523         spin_lock_irqsave(&dev->list_lock, flags);
 524         list_for_each_entry(list, &dev->list, node) {
 525                 int new_head = (list->head + 1) & (HIDRAW_BUFFER_SIZE - 1);
 526
 527                 if (new_head == list->tail)
 528                         continue;
 529
 530                 if (!(list->buffer[list->head].value = kmemdup(data, len, GFP_ATOMIC))) {
 531                         ret = -ENOMEM;
 532                         break;
 533                 }
 534                 list->buffer[list->head].len = len;
 535                 list->head = new_head;
 536                 kill_fasync(&list->fasync, SIGIO, POLL_IN);
 537         }
 538         spin_unlock_irqrestore(&dev->list_lock, flags);
 539
 540         wake_up_interruptible(&dev->wait);
 541         return ret;
 542 }
 543 EXPORT_SYMBOL_GPL(hidraw_report_event);
 544
 545 int hidraw_connect(struct hid_device *hid)
 546 {
 547         int minor, result;
 548         struct hidraw *dev;
 549
 550         /* we accept any HID device, all applications */
 551
 552         dev = kzalloc(sizeof(struct hidraw), GFP_KERNEL);
 553         if (!dev)
 554                 return -ENOMEM;
 555
 556         result = -EINVAL;
 557
 558         down_write(&minors_rwsem);
 559
 560         for (minor = 0; minor < HIDRAW_MAX_DEVICES; minor++) {
 561                 if (hidraw_table[minor])
 562                         continue;
 563                 hidraw_table[minor] = dev;
 564                 result = 0;
 565                 break;
 566         }
 567
 568         if (result) {
 569                 up_write(&minors_rwsem);
 570                 kfree(dev);
 571                 goto out;
 572         }
 573
 574         dev->dev = device_create(&hidraw_class, &hid->dev, MKDEV(hidraw_major, minor),
 575                                  NULL, "%s%d", "hidraw", minor);
 576
 577         if (IS_ERR(dev->dev)) {
 578                 hidraw_table[minor] = NULL;
 579                 up_write(&minors_rwsem);
 580                 result = PTR_ERR(dev->dev);
 581                 kfree(dev);
 582                 goto out;
 583         }
 584
 585         init_waitqueue_head(&dev->wait);
 586         spin_lock_init(&dev->list_lock);
 587         INIT_LIST_HEAD(&dev->list);
 588
 589         dev->hid = hid;
 590         dev->minor = minor;
 591
 592         dev->exist = 1;
 593         hid->hidraw = dev;
 594
 595         up_write(&minors_rwsem);
 596 out:
 597         return result;
 598
 599 }
 600 EXPORT_SYMBOL_GPL(hidraw_connect);
 601
 602 void hidraw_disconnect(struct hid_device *hid)
 603 {
 604         struct hidraw *hidraw = hid->hidraw;
 605
 606         down_write(&minors_rwsem);
 607
 608         drop_ref(hidraw, 1);
 609
 610         up_write(&minors_rwsem);
 611 }
 612 EXPORT_SYMBOL_GPL(hidraw_disconnect);
 613
 614 int __init hidraw_init(void)
 615 {
 616         int result;
 617         dev_t dev_id;
 618
 619         result = alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR,
 620                         HIDRAW_MAX_DEVICES, "hidraw");
 621         if (result < 0) {
 622                 pr_warn("can't get major number\n");
 623                 goto out;
 624         }
 625
 626         hidraw_major = MAJOR(dev_id);
 627
 628         result = class_register(&hidraw_class);
 629         if (result)
 630                 goto error_cdev;
 631
 632         cdev_init(&hidraw_cdev, &hidraw_ops);
 633         result = cdev_add(&hidraw_cdev, dev_id, HIDRAW_MAX_DEVICES);
 634         if (result < 0)
 635                 goto error_class;
 636
 637         pr_info("raw HID events driver (C) Jiri Kosina\n");
 638 out:
 639         return result;
 640
 641 error_class:
 642         class_unregister(&hidraw_class);
 643 error_cdev:
 644         unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
 645         goto out;
 646 }
 647
 648 void hidraw_exit(void)
 649 {
 650         dev_t dev_id = MKDEV(hidraw_major, 0);
 651
 652         cdev_del(&hidraw_cdev);
 653         class_unregister(&hidraw_class);
 654         unregister_chrdev_region(dev_id, HIDRAW_MAX_DEVICES);
 655
 656 }