summaryrefslogtreecommitdiffstats
path: root/drivers/char/tpm/tpm_vtpm_proxy.c
blob: 9a940332c15758ae3f818301eea526a79d4dff9d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
/*
 * Copyright (C) 2015, 2016 IBM Corporation
 *
 * Author: Stefan Berger <stefanb@us.ibm.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * Device driver for vTPM (vTPM proxy driver)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, version 2 of the
 * License.
 *
 */

#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <linux/miscdevice.h>
#include <linux/vtpm_proxy.h>
#include <linux/file.h>
#include <linux/anon_inodes.h>
#include <linux/poll.h>
#include <linux/compat.h>

#include "tpm.h"

#define VTPM_PROXY_REQ_COMPLETE_FLAG  BIT(0)

struct proxy_dev {
	struct tpm_chip *chip;

	u32 flags;                   /* public API flags */

	wait_queue_head_t wq;

	struct mutex buf_lock;       /* protect buffer and flags */

	long state;                  /* internal state */
#define STATE_OPENED_FLAG        BIT(0)
#define STATE_WAIT_RESPONSE_FLAG BIT(1)  /* waiting for emulator response */

	size_t req_len;              /* length of queued TPM request */
	size_t resp_len;             /* length of queued TPM response */
	u8 buffer[TPM_BUFSIZE];      /* request/response buffer */

	struct work_struct work;     /* task that retrieves TPM timeouts */
};

/* all supported flags */
#define VTPM_PROXY_FLAGS_ALL  (VTPM_PROXY_FLAG_TPM2)

static struct workqueue_struct *workqueue;

static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev);

/*
 * Functions related to 'server side'
 */

/**
 * vtpm_proxy_fops_read - Read TPM commands on 'server side'
 *
 * Return value:
 *	Number of bytes read or negative error code
 */
static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
				    size_t count, loff_t *off)
{
	struct proxy_dev *proxy_dev = filp->private_data;
	size_t len;
	int sig, rc;

	sig = wait_event_interruptible(proxy_dev->wq,
		proxy_dev->req_len != 0 ||
		!(proxy_dev->state & STATE_OPENED_FLAG));
	if (sig)
		return -EINTR;

	mutex_lock(&proxy_dev->buf_lock);

	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EPIPE;
	}

	len = proxy_dev->req_len;

	if (count < len) {
		mutex_unlock(&proxy_dev->buf_lock);
		pr_debug("Invalid size in recv: count=%zd, req_len=%zd\n",
			 count, len);
		return -EIO;
	}

	rc = copy_to_user(buf, proxy_dev->buffer, len);
	memset(proxy_dev->buffer, 0, len);
	proxy_dev->req_len = 0;

	if (!rc)
		proxy_dev->state |= STATE_WAIT_RESPONSE_FLAG;

	mutex_unlock(&proxy_dev->buf_lock);

	if (rc)
		return -EFAULT;

	return len;
}

/**
 * vtpm_proxy_fops_write - Write TPM responses on 'server side'
 *
 * Return value:
 *	Number of bytes read or negative error value
 */
static ssize_t vtpm_proxy_fops_write(struct file *filp, const char __user *buf,
				     size_t count, loff_t *off)
{
	struct proxy_dev *proxy_dev = filp->private_data;

	mutex_lock(&proxy_dev->buf_lock);

	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EPIPE;
	}

	if (count > sizeof(proxy_dev->buffer) ||
	    !(proxy_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EIO;
	}

	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;

	proxy_dev->req_len = 0;

	if (copy_from_user(proxy_dev->buffer, buf, count)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EFAULT;
	}

	proxy_dev->resp_len = count;

	mutex_unlock(&proxy_dev->buf_lock);

	wake_up_interruptible(&proxy_dev->wq);

	return count;
}

/*
 * vtpm_proxy_fops_poll: Poll status on 'server side'
 *
 * Return value:
 *      Poll flags
 */
static unsigned int vtpm_proxy_fops_poll(struct file *filp, poll_table *wait)
{
	struct proxy_dev *proxy_dev = filp->private_data;
	unsigned ret;

	poll_wait(filp, &proxy_dev->wq, wait);

	ret = POLLOUT;

	mutex_lock(&proxy_dev->buf_lock);

	if (proxy_dev->req_len)
		ret |= POLLIN | POLLRDNORM;

	if (!(proxy_dev->state & STATE_OPENED_FLAG))
		ret |= POLLHUP;

	mutex_unlock(&proxy_dev->buf_lock);

	return ret;
}

/*
 * vtpm_proxy_fops_open - Open vTPM device on 'server side'
 *
 * Called when setting up the anonymous file descriptor
 */
static void vtpm_proxy_fops_open(struct file *filp)
{
	struct proxy_dev *proxy_dev = filp->private_data;

	proxy_dev->state |= STATE_OPENED_FLAG;
}

/**
 * vtpm_proxy_fops_undo_open - counter-part to vtpm_fops_open
 *
 * Call to undo vtpm_proxy_fops_open
 */
static void vtpm_proxy_fops_undo_open(struct proxy_dev *proxy_dev)
{
	mutex_lock(&proxy_dev->buf_lock);

	proxy_dev->state &= ~STATE_OPENED_FLAG;

	mutex_unlock(&proxy_dev->buf_lock);

	/* no more TPM responses -- wake up anyone waiting for them */
	wake_up_interruptible(&proxy_dev->wq);
}

/*
 * vtpm_proxy_fops_release: Close 'server side'
 *
 * Return value:
 *      Always returns 0.
 */
static int vtpm_proxy_fops_release(struct inode *inode, struct file *filp)
{
	struct proxy_dev *proxy_dev = filp->private_data;

	filp->private_data = NULL;

	vtpm_proxy_delete_device(proxy_dev);

	return 0;
}

static const struct file_operations vtpm_proxy_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.read = vtpm_proxy_fops_read,
	.write = vtpm_proxy_fops_write,
	.poll = vtpm_proxy_fops_poll,
	.release = vtpm_proxy_fops_release,
};

/*
 * Functions invoked by the core TPM driver to send TPM commands to
 * 'server side' and receive responses from there.
 */

/*
 * Called when core TPM driver reads TPM responses from 'server side'
 *
 * Return value:
 *      Number of TPM response bytes read, negative error value otherwise
 */
static int vtpm_proxy_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
	size_t len;

	/* process gone ? */
	mutex_lock(&proxy_dev->buf_lock);

	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EPIPE;
	}

	len = proxy_dev->resp_len;
	if (count < len) {
		dev_err(&chip->dev,
			"Invalid size in recv: count=%zd, resp_len=%zd\n",
			count, len);
		len = -EIO;
		goto out;
	}

	memcpy(buf, proxy_dev->buffer, len);
	proxy_dev->resp_len = 0;

out:
	mutex_unlock(&proxy_dev->buf_lock);

	return len;
}

/*
 * Called when core TPM driver forwards TPM requests to 'server side'.
 *
 * Return value:
 *      0 in case of success, negative error value otherwise.
 */
static int vtpm_proxy_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
	int rc = 0;

	if (count > sizeof(proxy_dev->buffer)) {
		dev_err(&chip->dev,
			"Invalid size in send: count=%zd, buffer size=%zd\n",
			count, sizeof(proxy_dev->buffer));
		return -EIO;
	}

	mutex_lock(&proxy_dev->buf_lock);

	if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
		mutex_unlock(&proxy_dev->buf_lock);
		return -EPIPE;
	}

	proxy_dev->resp_len = 0;

	proxy_dev->req_len = count;
	memcpy(proxy_dev->buffer, buf, count);

	proxy_dev->state &= ~STATE_WAIT_RESPONSE_FLAG;

	mutex_unlock(&proxy_dev->buf_lock);

	wake_up_interruptible(&proxy_dev->wq);

	return rc;
}

static void vtpm_proxy_tpm_op_cancel(struct tpm_chip *chip)
{
	/* not supported */
}

static u8 vtpm_proxy_tpm_op_status(struct tpm_chip *chip)
{
	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);

	if (proxy_dev->resp_len)
		return VTPM_PROXY_REQ_COMPLETE_FLAG;

	return 0;
}

static bool vtpm_proxy_tpm_req_canceled(struct tpm_chip  *chip, u8 status)
{
	struct proxy_dev *proxy_dev = dev_get_drvdata(&chip->dev);
	bool ret;

	mutex_lock(&proxy_dev->buf_lock);

	ret = !(proxy_dev->state & STATE_OPENED_FLAG);

	mutex_unlock(&proxy_dev->buf_lock);

	return ret;
}

static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
	.flags = TPM_OPS_AUTO_STARTUP,
	.recv = vtpm_proxy_tpm_op_recv,
	.send = vtpm_proxy_tpm_op_send,
	.cancel = vtpm_proxy_tpm_op_cancel,
	.status = vtpm_proxy_tpm_op_status,
	.req_complete_mask = VTPM_PROXY_REQ_COMPLETE_FLAG,
	.req_complete_val = VTPM_PROXY_REQ_COMPLETE_FLAG,
	.req_canceled = vtpm_proxy_tpm_req_canceled,
};

/*
 * Code related to the startup of the TPM 2 and startup of TPM 1.2 +
 * retrieval of timeouts and durations.
 */

static void vtpm_proxy_work(struct work_struct *work)
{
	struct proxy_dev *proxy_dev = container_of(work, struct proxy_dev,
						   work);
	int rc;

	rc = tpm_chip_register(proxy_dev->chip);
	if (rc)
		goto err;

	return;

err:
	vtpm_proxy_fops_undo_open(proxy_dev);
}

/*
 * vtpm_proxy_work_stop: make sure the work has finished
 *
 * This function is useful when user space closed the fd
 * while the driver still determines timeouts.
 */
static void vtpm_proxy_work_stop(struct proxy_dev *proxy_dev)
{
	vtpm_proxy_fops_undo_open(proxy_dev);
	flush_work(&proxy_dev->work);
}

/*
 * vtpm_proxy_work_start: Schedule the work for TPM 1.2 & 2 initialization
 */
static inline void vtpm_proxy_work_start(struct proxy_dev *proxy_dev)
{
	queue_work(workqueue, &proxy_dev->work);
}

/*
 * Code related to creation and deletion of device pairs
 */
static struct proxy_dev *vtpm_proxy_create_proxy_dev(void)
{
	struct proxy_dev *proxy_dev;
	struct tpm_chip *chip;
	int err;

	proxy_dev = kzalloc(sizeof(*proxy_dev), GFP_KERNEL);
	if (proxy_dev == NULL)
		return ERR_PTR(-ENOMEM);

	init_waitqueue_head(&proxy_dev->wq);
	mutex_init(&proxy_dev->buf_lock);
	INIT_WORK(&proxy_dev->work, vtpm_proxy_work);

	chip = tpm_chip_alloc(NULL, &vtpm_proxy_tpm_ops);
	if (IS_ERR(chip)) {
		err = PTR_ERR(chip);
		goto err_proxy_dev_free;
	}
	dev_set_drvdata(&chip->dev, proxy_dev);

	proxy_dev->chip = chip;

	return proxy_dev;

err_proxy_dev_free:
	kfree(proxy_dev);

	return ERR_PTR(err);
}

/*
 * Undo what has been done in vtpm_create_proxy_dev
 */
static inline void vtpm_proxy_delete_proxy_dev(struct proxy_dev *proxy_dev)
{
	put_device(&proxy_dev->chip->dev); /* frees chip */
	kfree(proxy_dev);
}

/*
 * Create a /dev/tpm%d and 'server side' file descriptor pair
 *
 * Return value:
 *      Returns file pointer on success, an error value otherwise
 */
static struct file *vtpm_proxy_create_device(
				 struct vtpm_proxy_new_dev *vtpm_new_dev)
{
	struct proxy_dev *proxy_dev;
	int rc, fd;
	struct file *file;

	if (vtpm_new_dev->flags & ~VTPM_PROXY_FLAGS_ALL)
		return ERR_PTR(-EOPNOTSUPP);

	proxy_dev = vtpm_proxy_create_proxy_dev();
	if (IS_ERR(proxy_dev))
		return ERR_CAST(proxy_dev);

	proxy_dev->flags = vtpm_new_dev->flags;

	/* setup an anonymous file for the server-side */
	fd = get_unused_fd_flags(O_RDWR);
	if (fd < 0) {
		rc = fd;
		goto err_delete_proxy_dev;
	}

	file = anon_inode_getfile("[vtpms]", &vtpm_proxy_fops, proxy_dev,
				  O_RDWR);
	if (IS_ERR(file)) {
		rc = PTR_ERR(file);
		goto err_put_unused_fd;
	}

	/* from now on we can unwind with put_unused_fd() + fput() */
	/* simulate an open() on the server side */
	vtpm_proxy_fops_open(file);

	if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
		proxy_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;

	vtpm_proxy_work_start(proxy_dev);

	vtpm_new_dev->fd = fd;
	vtpm_new_dev->major = MAJOR(proxy_dev->chip->dev.devt);
	vtpm_new_dev->minor = MINOR(proxy_dev->chip->dev.devt);
	vtpm_new_dev->tpm_num = proxy_dev->chip->dev_num;

	return file;

err_put_unused_fd:
	put_unused_fd(fd);

err_delete_proxy_dev:
	vtpm_proxy_delete_proxy_dev(proxy_dev);

	return ERR_PTR(rc);
}

/*
 * Counter part to vtpm_create_device.
 */
static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
{
	vtpm_proxy_work_stop(proxy_dev);

	/*
	 * A client may hold the 'ops' lock, so let it know that the server
	 * side shuts down before we try to grab the 'ops' lock when
	 * unregistering the chip.
	 */
	vtpm_proxy_fops_undo_open(proxy_dev);

	tpm_chip_unregister(proxy_dev->chip);

	vtpm_proxy_delete_proxy_dev(proxy_dev);
}

/*
 * Code related to the control device /dev/vtpmx
 */

/*
 * vtpmx_fops_ioctl: ioctl on /dev/vtpmx
 *
 * Return value:
 *      Returns 0 on success, a negative error code otherwise.
 */
static long vtpmx_fops_ioctl(struct file *f, unsigned int ioctl,
				   unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	struct vtpm_proxy_new_dev __user *vtpm_new_dev_p;
	struct vtpm_proxy_new_dev vtpm_new_dev;
	struct file *file;

	switch (ioctl) {
	case VTPM_PROXY_IOC_NEW_DEV:
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
		vtpm_new_dev_p = argp;
		if (copy_from_user(&vtpm_new_dev, vtpm_new_dev_p,
				   sizeof(vtpm_new_dev)))
			return -EFAULT;
		file = vtpm_proxy_create_device(&vtpm_new_dev);
		if (IS_ERR(file))
			return PTR_ERR(file);
		if (copy_to_user(vtpm_new_dev_p, &vtpm_new_dev,
				 sizeof(vtpm_new_dev))) {
			put_unused_fd(vtpm_new_dev.fd);
			fput(file);
			return -EFAULT;
		}

		fd_install(vtpm_new_dev.fd, file);
		return 0;

	default:
		return -ENOIOCTLCMD;
	}
}

#ifdef CONFIG_COMPAT
static long vtpmx_fops_compat_ioctl(struct file *f, unsigned int ioctl,
					  unsigned long arg)
{
	return vtpmx_fops_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
}
#endif

static const struct file_operations vtpmx_fops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = vtpmx_fops_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl = vtpmx_fops_compat_ioctl,
#endif
	.llseek = noop_llseek,
};

static struct miscdevice vtpmx_miscdev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "vtpmx",
	.fops = &vtpmx_fops,
};

static int vtpmx_init(void)
{
	return misc_register(&vtpmx_miscdev);
}

static void vtpmx_cleanup(void)
{
	misc_deregister(&vtpmx_miscdev);
}

static int __init vtpm_module_init(void)
{
	int rc;

	rc = vtpmx_init();
	if (rc) {
		pr_err("couldn't create vtpmx device\n");
		return rc;
	}

	workqueue = create_workqueue("tpm-vtpm");
	if (!workqueue) {
		pr_err("couldn't create workqueue\n");
		rc = -ENOMEM;
		goto err_vtpmx_cleanup;
	}

	return 0;

err_vtpmx_cleanup:
	vtpmx_cleanup();

	return rc;
}

static void __exit vtpm_module_exit(void)
{
	destroy_workqueue(workqueue);
	vtpmx_cleanup();
}

module_init(vtpm_module_init);
module_exit(vtpm_module_exit);

MODULE_AUTHOR("Stefan Berger (stefanb@us.ibm.com)");
MODULE_DESCRIPTION("vTPM Driver");
MODULE_VERSION("0.1");
MODULE_LICENSE("GPL");
OpenPOWER on IntegriCloud