drivers/hid/uhid.c

   1 /*
   2  * User-space I/O driver support for HID subsystem
   3  * Copyright (c) 2012 David Herrmann
   4  */
   5
   6 /*
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  */
  12
  13 #include <linux/atomic.h>
  14 #include <linux/compat.h>
  15 #include <linux/device.h>
  16 #include <linux/fs.h>
  17 #include <linux/hid.h>
  18 #include <linux/input.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/poll.h>
  23 #include <linux/sched.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/uhid.h>
  26 #include <linux/wait.h>
  27
  28 #define UHID_NAME       "uhid"
  29 #define UHID_BUFSIZE    32
  30
  31 struct uhid_device {
  32         struct mutex devlock;
  33         bool running;
  34
  35         __u8 *rd_data;
  36         uint rd_size;
  37
  38         struct hid_device *hid;
  39         struct uhid_event input_buf;
  40
  41         wait_queue_head_t waitq;
  42         spinlock_t qlock;
  43         __u8 head;
  44         __u8 tail;
  45         struct uhid_event *outq[UHID_BUFSIZE];
  46
  47         struct mutex report_lock;
  48         wait_queue_head_t report_wait;
  49         atomic_t report_done;
  50         atomic_t report_id;
  51         struct uhid_event report_buf;
  52 };
  53
  54 static struct miscdevice uhid_misc;
  55
  56 static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
  57 {
  58         __u8 newhead;
  59
  60         newhead = (uhid->head + 1) % UHID_BUFSIZE;
  61
  62         if (newhead != uhid->tail) {
  63                 uhid->outq[uhid->head] = ev;
  64                 uhid->head = newhead;
  65                 wake_up_interruptible(&uhid->waitq);
  66         } else {
  67                 hid_warn(uhid->hid, "Output queue is full\n");
  68                 kfree(ev);
  69         }
  70 }
  71
  72 static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
  73 {
  74         unsigned long flags;
  75         struct uhid_event *ev;
  76
  77         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
  78         if (!ev)
  79                 return -ENOMEM;
  80
  81         ev->type = event;
  82
  83         spin_lock_irqsave(&uhid->qlock, flags);
  84         uhid_queue(uhid, ev);
  85         spin_unlock_irqrestore(&uhid->qlock, flags);
  86
  87         return 0;
  88 }
  89
  90 static int uhid_hid_start(struct hid_device *hid)
  91 {
  92         struct uhid_device *uhid = hid->driver_data;
  93
  94         return uhid_queue_event(uhid, UHID_START);
  95 }
  96
  97 static void uhid_hid_stop(struct hid_device *hid)
  98 {
  99         struct uhid_device *uhid = hid->driver_data;
 100
 101         hid->claimed = 0;
 102         uhid_queue_event(uhid, UHID_STOP);
 103 }
 104
 105 static int uhid_hid_open(struct hid_device *hid)
 106 {
 107         struct uhid_device *uhid = hid->driver_data;
 108
 109         return uhid_queue_event(uhid, UHID_OPEN);
 110 }
 111
 112 static void uhid_hid_close(struct hid_device *hid)
 113 {
 114         struct uhid_device *uhid = hid->driver_data;
 115
 116         uhid_queue_event(uhid, UHID_CLOSE);
 117 }
 118
 119 static int uhid_hid_parse(struct hid_device *hid)
 120 {
 121         struct uhid_device *uhid = hid->driver_data;
 122
 123         return hid_parse_report(hid, uhid->rd_data, uhid->rd_size);
 124 }
 125
 126 static int uhid_hid_get_raw(struct hid_device *hid, unsigned char rnum,
 127                             __u8 *buf, size_t count, unsigned char rtype)
 128 {
 129         struct uhid_device *uhid = hid->driver_data;
 130         __u8 report_type;
 131         struct uhid_event *ev;
 132         unsigned long flags;
 133         int ret;
 134         size_t uninitialized_var(len);
 135         struct uhid_feature_answer_req *req;
 136
 137         if (!uhid->running)
 138                 return -EIO;
 139
 140         switch (rtype) {
 141         case HID_FEATURE_REPORT:
 142                 report_type = UHID_FEATURE_REPORT;
 143                 break;
 144         case HID_OUTPUT_REPORT:
 145                 report_type = UHID_OUTPUT_REPORT;
 146                 break;
 147         case HID_INPUT_REPORT:
 148                 report_type = UHID_INPUT_REPORT;
 149                 break;
 150         default:
 151                 return -EINVAL;
 152         }
 153
 154         ret = mutex_lock_interruptible(&uhid->report_lock);
 155         if (ret)
 156                 return ret;
 157
 158         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 159         if (!ev) {
 160                 ret = -ENOMEM;
 161                 goto unlock;
 162         }
 163
 164         spin_lock_irqsave(&uhid->qlock, flags);
 165         ev->type = UHID_FEATURE;
 166         ev->u.feature.id = atomic_inc_return(&uhid->report_id);
 167         ev->u.feature.rnum = rnum;
 168         ev->u.feature.rtype = report_type;
 169
 170         atomic_set(&uhid->report_done, 0);
 171         uhid_queue(uhid, ev);
 172         spin_unlock_irqrestore(&uhid->qlock, flags);
 173
 174         ret = wait_event_interruptible_timeout(uhid->report_wait,
 175                                 atomic_read(&uhid->report_done), 5 * HZ);
 176
 177         /*
 178          * Make sure "uhid->running" is cleared on shutdown before
 179          * "uhid->report_done" is set.
 180          */
 181         smp_rmb();
 182         if (!ret || !uhid->running) {
 183                 ret = -EIO;
 184         } else if (ret < 0) {
 185                 ret = -ERESTARTSYS;
 186         } else {
 187                 spin_lock_irqsave(&uhid->qlock, flags);
 188                 req = &uhid->report_buf.u.feature_answer;
 189
 190                 if (req->err) {
 191                         ret = -EIO;
 192                 } else {
 193                         ret = 0;
 194                         len = min(count,
 195                                 min_t(size_t, req->size, UHID_DATA_MAX));
 196                         memcpy(buf, req->data, len);
 197                 }
 198
 199                 spin_unlock_irqrestore(&uhid->qlock, flags);
 200         }
 201
 202         atomic_set(&uhid->report_done, 1);
 203
 204 unlock:
 205         mutex_unlock(&uhid->report_lock);
 206         return ret ? ret : len;
 207 }
 208
 209 static int uhid_hid_output_raw(struct hid_device *hid, __u8 *buf, size_t count,
 210                                unsigned char report_type)
 211 {
 212         struct uhid_device *uhid = hid->driver_data;
 213         __u8 rtype;
 214         unsigned long flags;
 215         struct uhid_event *ev;
 216
 217         switch (report_type) {
 218         case HID_FEATURE_REPORT:
 219                 rtype = UHID_FEATURE_REPORT;
 220                 break;
 221         case HID_OUTPUT_REPORT:
 222                 rtype = UHID_OUTPUT_REPORT;
 223                 break;
 224         default:
 225                 return -EINVAL;
 226         }
 227
 228         if (count < 1 || count > UHID_DATA_MAX)
 229                 return -EINVAL;
 230
 231         ev = kzalloc(sizeof(*ev), GFP_KERNEL);
 232         if (!ev)
 233                 return -ENOMEM;
 234
 235         ev->type = UHID_OUTPUT;
 236         ev->u.output.size = count;
 237         ev->u.output.rtype = rtype;
 238         memcpy(ev->u.output.data, buf, count);
 239
 240         spin_lock_irqsave(&uhid->qlock, flags);
 241         uhid_queue(uhid, ev);
 242         spin_unlock_irqrestore(&uhid->qlock, flags);
 243
 244         return count;
 245 }
 246
 247 static int uhid_hid_output_report(struct hid_device *hid, __u8 *buf,
 248                                   size_t count)
 249 {
 250         return uhid_hid_output_raw(hid, buf, count, HID_OUTPUT_REPORT);
 251 }
 252
 253 static int uhid_raw_request(struct hid_device *hid, unsigned char reportnum,
 254                             __u8 *buf, size_t len, unsigned char rtype,
 255                             int reqtype)
 256 {
 257         switch (reqtype) {
 258         case HID_REQ_GET_REPORT:
 259                 return uhid_hid_get_raw(hid, reportnum, buf, len, rtype);
 260         case HID_REQ_SET_REPORT:
 261                 /* TODO: implement proper SET_REPORT functionality */
 262                 return -ENOSYS;
 263         default:
 264                 return -EIO;
 265         }
 266 }
 267
 268 static struct hid_ll_driver uhid_hid_driver = {
 269         .start = uhid_hid_start,
 270         .stop = uhid_hid_stop,
 271         .open = uhid_hid_open,
 272         .close = uhid_hid_close,
 273         .parse = uhid_hid_parse,
 274         .output_report = uhid_hid_output_report,
 275         .raw_request = uhid_raw_request,
 276 };
 277
 278 #ifdef CONFIG_COMPAT
 279
 280 /* Apparently we haven't stepped on these rakes enough times yet. */
 281 struct uhid_create_req_compat {
 282         __u8 name[128];
 283         __u8 phys[64];
 284         __u8 uniq[64];
 285
 286         compat_uptr_t rd_data;
 287         __u16 rd_size;
 288
 289         __u16 bus;
 290         __u32 vendor;
 291         __u32 product;
 292         __u32 version;
 293         __u32 country;
 294 } __attribute__((__packed__));
 295
 296 static int uhid_event_from_user(const char __user *buffer, size_t len,
 297                                 struct uhid_event *event)
 298 {
 299         if (is_compat_task()) {
 300                 u32 type;
 301
 302                 if (get_user(type, buffer))
 303                         return -EFAULT;
 304
 305                 if (type == UHID_CREATE) {
 306                         /*
 307                          * This is our messed up request with compat pointer.
 308                          * It is largish (more than 256 bytes) so we better
 309                          * allocate it from the heap.
 310                          */
 311                         struct uhid_create_req_compat *compat;
 312
 313                         compat = kzalloc(sizeof(*compat), GFP_KERNEL);
 314                         if (!compat)
 315                                 return -ENOMEM;
 316
 317                         buffer += sizeof(type);
 318                         len -= sizeof(type);
 319                         if (copy_from_user(compat, buffer,
 320                                            min(len, sizeof(*compat)))) {
 321                                 kfree(compat);
 322                                 return -EFAULT;
 323                         }
 324
 325                         /* Shuffle the data over to proper structure */
 326                         event->type = type;
 327
 328                         memcpy(event->u.create.name, compat->name,
 329                                 sizeof(compat->name));
 330                         memcpy(event->u.create.phys, compat->phys,
 331                                 sizeof(compat->phys));
 332                         memcpy(event->u.create.uniq, compat->uniq,
 333                                 sizeof(compat->uniq));
 334
 335                         event->u.create.rd_data = compat_ptr(compat->rd_data);
 336                         event->u.create.rd_size = compat->rd_size;
 337
 338                         event->u.create.bus = compat->bus;
 339                         event->u.create.vendor = compat->vendor;
 340                         event->u.create.product = compat->product;
 341                         event->u.create.version = compat->version;
 342                         event->u.create.country = compat->country;
 343
 344                         kfree(compat);
 345                         return 0;
 346                 }
 347                 /* All others can be copied directly */
 348         }
 349
 350         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 351                 return -EFAULT;
 352
 353         return 0;
 354 }
 355 #else
 356 static int uhid_event_from_user(const char __user *buffer, size_t len,
 357                                 struct uhid_event *event)
 358 {
 359         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 360                 return -EFAULT;
 361
 362         return 0;
 363 }
 364 #endif
 365
 366 static int uhid_dev_create(struct uhid_device *uhid,
 367                            const struct uhid_event *ev)
 368 {
 369         struct hid_device *hid;
 370         int ret;
 371
 372         if (uhid->running)
 373                 return -EALREADY;
 374
 375         uhid->rd_size = ev->u.create.rd_size;
 376         if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
 377                 return -EINVAL;
 378
 379         uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
 380         if (!uhid->rd_data)
 381                 return -ENOMEM;
 382
 383         if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
 384                            uhid->rd_size)) {
 385                 ret = -EFAULT;
 386                 goto err_free;
 387         }
 388
 389         hid = hid_allocate_device();
 390         if (IS_ERR(hid)) {
 391                 ret = PTR_ERR(hid);
 392                 goto err_free;
 393         }
 394
 395         strncpy(hid->name, ev->u.create.name, 127);
 396         hid->name[127] = 0;
 397         strncpy(hid->phys, ev->u.create.phys, 63);
 398         hid->phys[63] = 0;
 399         strncpy(hid->uniq, ev->u.create.uniq, 63);
 400         hid->uniq[63] = 0;
 401
 402         hid->ll_driver = &uhid_hid_driver;
 403         hid->bus = ev->u.create.bus;
 404         hid->vendor = ev->u.create.vendor;
 405         hid->product = ev->u.create.product;
 406         hid->version = ev->u.create.version;
 407         hid->country = ev->u.create.country;
 408         hid->driver_data = uhid;
 409         hid->dev.parent = uhid_misc.this_device;
 410
 411         uhid->hid = hid;
 412         uhid->running = true;
 413
 414         ret = hid_add_device(hid);
 415         if (ret) {
 416                 hid_err(hid, "Cannot register HID device\n");
 417                 goto err_hid;
 418         }
 419
 420         return 0;
 421
 422 err_hid:
 423         hid_destroy_device(hid);
 424         uhid->hid = NULL;
 425         uhid->running = false;
 426 err_free:
 427         kfree(uhid->rd_data);
 428         return ret;
 429 }
 430
 431 static int uhid_dev_destroy(struct uhid_device *uhid)
 432 {
 433         if (!uhid->running)
 434                 return -EINVAL;
 435
 436         /* clear "running" before setting "report_done" */
 437         uhid->running = false;
 438         smp_wmb();
 439         atomic_set(&uhid->report_done, 1);
 440         wake_up_interruptible(&uhid->report_wait);
 441
 442         hid_destroy_device(uhid->hid);
 443         kfree(uhid->rd_data);
 444
 445         return 0;
 446 }
 447
 448 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
 449 {
 450         if (!uhid->running)
 451                 return -EINVAL;
 452
 453         hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
 454                          min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
 455
 456         return 0;
 457 }
 458
 459 static int uhid_dev_feature_answer(struct uhid_device *uhid,
 460                                    struct uhid_event *ev)
 461 {
 462         unsigned long flags;
 463
 464         if (!uhid->running)
 465                 return -EINVAL;
 466
 467         spin_lock_irqsave(&uhid->qlock, flags);
 468
 469         /* id for old report; drop it silently */
 470         if (atomic_read(&uhid->report_id) != ev->u.feature_answer.id)
 471                 goto unlock;
 472         if (atomic_read(&uhid->report_done))
 473                 goto unlock;
 474
 475         memcpy(&uhid->report_buf, ev, sizeof(*ev));
 476         atomic_set(&uhid->report_done, 1);
 477         wake_up_interruptible(&uhid->report_wait);
 478
 479 unlock:
 480         spin_unlock_irqrestore(&uhid->qlock, flags);
 481         return 0;
 482 }
 483
 484 static int uhid_char_open(struct inode *inode, struct file *file)
 485 {
 486         struct uhid_device *uhid;
 487
 488         uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
 489         if (!uhid)
 490                 return -ENOMEM;
 491
 492         mutex_init(&uhid->devlock);
 493         mutex_init(&uhid->report_lock);
 494         spin_lock_init(&uhid->qlock);
 495         init_waitqueue_head(&uhid->waitq);
 496         init_waitqueue_head(&uhid->report_wait);
 497         uhid->running = false;
 498         atomic_set(&uhid->report_done, 1);
 499
 500         file->private_data = uhid;
 501         nonseekable_open(inode, file);
 502
 503         return 0;
 504 }
 505
 506 static int uhid_char_release(struct inode *inode, struct file *file)
 507 {
 508         struct uhid_device *uhid = file->private_data;
 509         unsigned int i;
 510
 511         uhid_dev_destroy(uhid);
 512
 513         for (i = 0; i < UHID_BUFSIZE; ++i)
 514                 kfree(uhid->outq[i]);
 515
 516         kfree(uhid);
 517
 518         return 0;
 519 }
 520
 521 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
 522                                 size_t count, loff_t *ppos)
 523 {
 524         struct uhid_device *uhid = file->private_data;
 525         int ret;
 526         unsigned long flags;
 527         size_t len;
 528
 529         /* they need at least the "type" member of uhid_event */
 530         if (count < sizeof(__u32))
 531                 return -EINVAL;
 532
 533 try_again:
 534         if (file->f_flags & O_NONBLOCK) {
 535                 if (uhid->head == uhid->tail)
 536                         return -EAGAIN;
 537         } else {
 538                 ret = wait_event_interruptible(uhid->waitq,
 539                                                 uhid->head != uhid->tail);
 540                 if (ret)
 541                         return ret;
 542         }
 543
 544         ret = mutex_lock_interruptible(&uhid->devlock);
 545         if (ret)
 546                 return ret;
 547
 548         if (uhid->head == uhid->tail) {
 549                 mutex_unlock(&uhid->devlock);
 550                 goto try_again;
 551         } else {
 552                 len = min(count, sizeof(**uhid->outq));
 553                 if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
 554                         ret = -EFAULT;
 555                 } else {
 556                         kfree(uhid->outq[uhid->tail]);
 557                         uhid->outq[uhid->tail] = NULL;
 558
 559                         spin_lock_irqsave(&uhid->qlock, flags);
 560                         uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
 561                         spin_unlock_irqrestore(&uhid->qlock, flags);
 562                 }
 563         }
 564
 565         mutex_unlock(&uhid->devlock);
 566         return ret ? ret : len;
 567 }
 568
 569 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
 570                                 size_t count, loff_t *ppos)
 571 {
 572         struct uhid_device *uhid = file->private_data;
 573         int ret;
 574         size_t len;
 575
 576         /* we need at least the "type" member of uhid_event */
 577         if (count < sizeof(__u32))
 578                 return -EINVAL;
 579
 580         ret = mutex_lock_interruptible(&uhid->devlock);
 581         if (ret)
 582                 return ret;
 583
 584         memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
 585         len = min(count, sizeof(uhid->input_buf));
 586
 587         ret = uhid_event_from_user(buffer, len, &uhid->input_buf);
 588         if (ret)
 589                 goto unlock;
 590
 591         switch (uhid->input_buf.type) {
 592         case UHID_CREATE:
 593                 ret = uhid_dev_create(uhid, &uhid->input_buf);
 594                 break;
 595         case UHID_DESTROY:
 596                 ret = uhid_dev_destroy(uhid);
 597                 break;
 598         case UHID_INPUT:
 599                 ret = uhid_dev_input(uhid, &uhid->input_buf);
 600                 break;
 601         case UHID_FEATURE_ANSWER:
 602                 ret = uhid_dev_feature_answer(uhid, &uhid->input_buf);
 603                 break;
 604         default:
 605                 ret = -EOPNOTSUPP;
 606         }
 607
 608 unlock:
 609         mutex_unlock(&uhid->devlock);
 610
 611         /* return "count" not "len" to not confuse the caller */
 612         return ret ? ret : count;
 613 }
 614
 615 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 616 {
 617         struct uhid_device *uhid = file->private_data;
 618
 619         poll_wait(file, &uhid->waitq, wait);
 620
 621         if (uhid->head != uhid->tail)
 622                 return POLLIN | POLLRDNORM;
 623
 624         return 0;
 625 }
 626
 627 static const struct file_operations uhid_fops = {
 628         .owner          = THIS_MODULE,
 629         .open           = uhid_char_open,
 630         .release        = uhid_char_release,
 631         .read           = uhid_char_read,
 632         .write          = uhid_char_write,
 633         .poll           = uhid_char_poll,
 634         .llseek         = no_llseek,
 635 };
 636
 637 static struct miscdevice uhid_misc = {
 638         .fops           = &uhid_fops,
 639         .minor          = UHID_MINOR,
 640         .name           = UHID_NAME,
 641 };
 642
 643 static int __init uhid_init(void)
 644 {
 645         return misc_register(&uhid_misc);
 646 }
 647
 648 static void __exit uhid_exit(void)
 649 {
 650         misc_deregister(&uhid_misc);
 651 }
 652
 653 module_init(uhid_init);
 654 module_exit(uhid_exit);
 655 MODULE_LICENSE("GPL");
 656 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
 657 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
 658 MODULE_ALIAS_MISCDEV(UHID_MINOR);
 659 MODULE_ALIAS("devname:" UHID_NAME);