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 struct hid_ll_driver uhid_hid_driver = {
 248         .start = uhid_hid_start,
 249         .stop = uhid_hid_stop,
 250         .open = uhid_hid_open,
 251         .close = uhid_hid_close,
 252         .parse = uhid_hid_parse,
 253 };
 254
 255 #ifdef CONFIG_COMPAT
 256
 257 /* Apparently we haven't stepped on these rakes enough times yet. */
 258 struct uhid_create_req_compat {
 259         __u8 name[128];
 260         __u8 phys[64];
 261         __u8 uniq[64];
 262
 263         compat_uptr_t rd_data;
 264         __u16 rd_size;
 265
 266         __u16 bus;
 267         __u32 vendor;
 268         __u32 product;
 269         __u32 version;
 270         __u32 country;
 271 } __attribute__((__packed__));
 272
 273 static int uhid_event_from_user(const char __user *buffer, size_t len,
 274                                 struct uhid_event *event)
 275 {
 276         if (is_compat_task()) {
 277                 u32 type;
 278
 279                 if (get_user(type, buffer))
 280                         return -EFAULT;
 281
 282                 if (type == UHID_CREATE) {
 283                         /*
 284                          * This is our messed up request with compat pointer.
 285                          * It is largish (more than 256 bytes) so we better
 286                          * allocate it from the heap.
 287                          */
 288                         struct uhid_create_req_compat *compat;
 289
 290                         compat = kzalloc(sizeof(*compat), GFP_KERNEL);
 291                         if (!compat)
 292                                 return -ENOMEM;
 293
 294                         buffer += sizeof(type);
 295                         len -= sizeof(type);
 296                         if (copy_from_user(compat, buffer,
 297                                            min(len, sizeof(*compat)))) {
 298                                 kfree(compat);
 299                                 return -EFAULT;
 300                         }
 301
 302                         /* Shuffle the data over to proper structure */
 303                         event->type = type;
 304
 305                         memcpy(event->u.create.name, compat->name,
 306                                 sizeof(compat->name));
 307                         memcpy(event->u.create.phys, compat->phys,
 308                                 sizeof(compat->phys));
 309                         memcpy(event->u.create.uniq, compat->uniq,
 310                                 sizeof(compat->uniq));
 311
 312                         event->u.create.rd_data = compat_ptr(compat->rd_data);
 313                         event->u.create.rd_size = compat->rd_size;
 314
 315                         event->u.create.bus = compat->bus;
 316                         event->u.create.vendor = compat->vendor;
 317                         event->u.create.product = compat->product;
 318                         event->u.create.version = compat->version;
 319                         event->u.create.country = compat->country;
 320
 321                         kfree(compat);
 322                         return 0;
 323                 }
 324                 /* All others can be copied directly */
 325         }
 326
 327         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 328                 return -EFAULT;
 329
 330         return 0;
 331 }
 332 #else
 333 static int uhid_event_from_user(const char __user *buffer, size_t len,
 334                                 struct uhid_event *event)
 335 {
 336         if (copy_from_user(event, buffer, min(len, sizeof(*event))))
 337                 return -EFAULT;
 338
 339         return 0;
 340 }
 341 #endif
 342
 343 static int uhid_dev_create(struct uhid_device *uhid,
 344                            const struct uhid_event *ev)
 345 {
 346         struct hid_device *hid;
 347         int ret;
 348
 349         if (uhid->running)
 350                 return -EALREADY;
 351
 352         uhid->rd_size = ev->u.create.rd_size;
 353         if (uhid->rd_size <= 0 || uhid->rd_size > HID_MAX_DESCRIPTOR_SIZE)
 354                 return -EINVAL;
 355
 356         uhid->rd_data = kmalloc(uhid->rd_size, GFP_KERNEL);
 357         if (!uhid->rd_data)
 358                 return -ENOMEM;
 359
 360         if (copy_from_user(uhid->rd_data, ev->u.create.rd_data,
 361                            uhid->rd_size)) {
 362                 ret = -EFAULT;
 363                 goto err_free;
 364         }
 365
 366         hid = hid_allocate_device();
 367         if (IS_ERR(hid)) {
 368                 ret = PTR_ERR(hid);
 369                 goto err_free;
 370         }
 371
 372         strncpy(hid->name, ev->u.create.name, 127);
 373         hid->name[127] = 0;
 374         strncpy(hid->phys, ev->u.create.phys, 63);
 375         hid->phys[63] = 0;
 376         strncpy(hid->uniq, ev->u.create.uniq, 63);
 377         hid->uniq[63] = 0;
 378
 379         hid->ll_driver = &uhid_hid_driver;
 380         hid->hid_get_raw_report = uhid_hid_get_raw;
 381         hid->hid_output_raw_report = uhid_hid_output_raw;
 382         hid->bus = ev->u.create.bus;
 383         hid->vendor = ev->u.create.vendor;
 384         hid->product = ev->u.create.product;
 385         hid->version = ev->u.create.version;
 386         hid->country = ev->u.create.country;
 387         hid->driver_data = uhid;
 388         hid->dev.parent = uhid_misc.this_device;
 389
 390         uhid->hid = hid;
 391         uhid->running = true;
 392
 393         ret = hid_add_device(hid);
 394         if (ret) {
 395                 hid_err(hid, "Cannot register HID device\n");
 396                 goto err_hid;
 397         }
 398
 399         return 0;
 400
 401 err_hid:
 402         hid_destroy_device(hid);
 403         uhid->hid = NULL;
 404         uhid->running = false;
 405 err_free:
 406         kfree(uhid->rd_data);
 407         return ret;
 408 }
 409
 410 static int uhid_dev_destroy(struct uhid_device *uhid)
 411 {
 412         if (!uhid->running)
 413                 return -EINVAL;
 414
 415         /* clear "running" before setting "report_done" */
 416         uhid->running = false;
 417         smp_wmb();
 418         atomic_set(&uhid->report_done, 1);
 419         wake_up_interruptible(&uhid->report_wait);
 420
 421         hid_destroy_device(uhid->hid);
 422         kfree(uhid->rd_data);
 423
 424         return 0;
 425 }
 426
 427 static int uhid_dev_input(struct uhid_device *uhid, struct uhid_event *ev)
 428 {
 429         if (!uhid->running)
 430                 return -EINVAL;
 431
 432         hid_input_report(uhid->hid, HID_INPUT_REPORT, ev->u.input.data,
 433                          min_t(size_t, ev->u.input.size, UHID_DATA_MAX), 0);
 434
 435         return 0;
 436 }
 437
 438 static int uhid_dev_feature_answer(struct uhid_device *uhid,
 439                                    struct uhid_event *ev)
 440 {
 441         unsigned long flags;
 442
 443         if (!uhid->running)
 444                 return -EINVAL;
 445
 446         spin_lock_irqsave(&uhid->qlock, flags);
 447
 448         /* id for old report; drop it silently */
 449         if (atomic_read(&uhid->report_id) != ev->u.feature_answer.id)
 450                 goto unlock;
 451         if (atomic_read(&uhid->report_done))
 452                 goto unlock;
 453
 454         memcpy(&uhid->report_buf, ev, sizeof(*ev));
 455         atomic_set(&uhid->report_done, 1);
 456         wake_up_interruptible(&uhid->report_wait);
 457
 458 unlock:
 459         spin_unlock_irqrestore(&uhid->qlock, flags);
 460         return 0;
 461 }
 462
 463 static int uhid_char_open(struct inode *inode, struct file *file)
 464 {
 465         struct uhid_device *uhid;
 466
 467         uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
 468         if (!uhid)
 469                 return -ENOMEM;
 470
 471         mutex_init(&uhid->devlock);
 472         mutex_init(&uhid->report_lock);
 473         spin_lock_init(&uhid->qlock);
 474         init_waitqueue_head(&uhid->waitq);
 475         init_waitqueue_head(&uhid->report_wait);
 476         uhid->running = false;
 477         atomic_set(&uhid->report_done, 1);
 478
 479         file->private_data = uhid;
 480         nonseekable_open(inode, file);
 481
 482         return 0;
 483 }
 484
 485 static int uhid_char_release(struct inode *inode, struct file *file)
 486 {
 487         struct uhid_device *uhid = file->private_data;
 488         unsigned int i;
 489
 490         uhid_dev_destroy(uhid);
 491
 492         for (i = 0; i < UHID_BUFSIZE; ++i)
 493                 kfree(uhid->outq[i]);
 494
 495         kfree(uhid);
 496
 497         return 0;
 498 }
 499
 500 static ssize_t uhid_char_read(struct file *file, char __user *buffer,
 501                                 size_t count, loff_t *ppos)
 502 {
 503         struct uhid_device *uhid = file->private_data;
 504         int ret;
 505         unsigned long flags;
 506         size_t len;
 507
 508         /* they need at least the "type" member of uhid_event */
 509         if (count < sizeof(__u32))
 510                 return -EINVAL;
 511
 512 try_again:
 513         if (file->f_flags & O_NONBLOCK) {
 514                 if (uhid->head == uhid->tail)
 515                         return -EAGAIN;
 516         } else {
 517                 ret = wait_event_interruptible(uhid->waitq,
 518                                                 uhid->head != uhid->tail);
 519                 if (ret)
 520                         return ret;
 521         }
 522
 523         ret = mutex_lock_interruptible(&uhid->devlock);
 524         if (ret)
 525                 return ret;
 526
 527         if (uhid->head == uhid->tail) {
 528                 mutex_unlock(&uhid->devlock);
 529                 goto try_again;
 530         } else {
 531                 len = min(count, sizeof(**uhid->outq));
 532                 if (copy_to_user(buffer, uhid->outq[uhid->tail], len)) {
 533                         ret = -EFAULT;
 534                 } else {
 535                         kfree(uhid->outq[uhid->tail]);
 536                         uhid->outq[uhid->tail] = NULL;
 537
 538                         spin_lock_irqsave(&uhid->qlock, flags);
 539                         uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
 540                         spin_unlock_irqrestore(&uhid->qlock, flags);
 541                 }
 542         }
 543
 544         mutex_unlock(&uhid->devlock);
 545         return ret ? ret : len;
 546 }
 547
 548 static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
 549                                 size_t count, loff_t *ppos)
 550 {
 551         struct uhid_device *uhid = file->private_data;
 552         int ret;
 553         size_t len;
 554
 555         /* we need at least the "type" member of uhid_event */
 556         if (count < sizeof(__u32))
 557                 return -EINVAL;
 558
 559         ret = mutex_lock_interruptible(&uhid->devlock);
 560         if (ret)
 561                 return ret;
 562
 563         memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
 564         len = min(count, sizeof(uhid->input_buf));
 565
 566         ret = uhid_event_from_user(buffer, len, &uhid->input_buf);
 567         if (ret)
 568                 goto unlock;
 569
 570         switch (uhid->input_buf.type) {
 571         case UHID_CREATE:
 572                 ret = uhid_dev_create(uhid, &uhid->input_buf);
 573                 break;
 574         case UHID_DESTROY:
 575                 ret = uhid_dev_destroy(uhid);
 576                 break;
 577         case UHID_INPUT:
 578                 ret = uhid_dev_input(uhid, &uhid->input_buf);
 579                 break;
 580         case UHID_FEATURE_ANSWER:
 581                 ret = uhid_dev_feature_answer(uhid, &uhid->input_buf);
 582                 break;
 583         default:
 584                 ret = -EOPNOTSUPP;
 585         }
 586
 587 unlock:
 588         mutex_unlock(&uhid->devlock);
 589
 590         /* return "count" not "len" to not confuse the caller */
 591         return ret ? ret : count;
 592 }
 593
 594 static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
 595 {
 596         struct uhid_device *uhid = file->private_data;
 597
 598         poll_wait(file, &uhid->waitq, wait);
 599
 600         if (uhid->head != uhid->tail)
 601                 return POLLIN | POLLRDNORM;
 602
 603         return 0;
 604 }
 605
 606 static const struct file_operations uhid_fops = {
 607         .owner          = THIS_MODULE,
 608         .open           = uhid_char_open,
 609         .release        = uhid_char_release,
 610         .read           = uhid_char_read,
 611         .write          = uhid_char_write,
 612         .poll           = uhid_char_poll,
 613         .llseek         = no_llseek,
 614 };
 615
 616 static struct miscdevice uhid_misc = {
 617         .fops           = &uhid_fops,
 618         .minor          = UHID_MINOR,
 619         .name           = UHID_NAME,
 620 };
 621
 622 static int __init uhid_init(void)
 623 {
 624         return misc_register(&uhid_misc);
 625 }
 626
 627 static void __exit uhid_exit(void)
 628 {
 629         misc_deregister(&uhid_misc);
 630 }
 631
 632 module_init(uhid_init);
 633 module_exit(uhid_exit);
 634 MODULE_LICENSE("GPL");
 635 MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
 636 MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
 637 MODULE_ALIAS_MISCDEV(UHID_MINOR);
 638 MODULE_ALIAS("devname:" UHID_NAME);