xref: /openbmc/linux/drivers/char/tpm/tpm-chip.c (revision a2818ee4)
1 /*
2  * Copyright (C) 2004 IBM Corporation
3  * Copyright (C) 2014 Intel Corporation
4  *
5  * Authors:
6  * Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
7  * Leendert van Doorn <leendert@watson.ibm.com>
8  * Dave Safford <safford@watson.ibm.com>
9  * Reiner Sailer <sailer@watson.ibm.com>
10  * Kylene Hall <kjhall@us.ibm.com>
11  *
12  * Maintained by: <tpmdd-devel@lists.sourceforge.net>
13  *
14  * TPM chip management routines.
15  *
16  * This program is free software; you can redistribute it and/or
17  * modify it under the terms of the GNU General Public License as
18  * published by the Free Software Foundation, version 2 of the
19  * License.
20  *
21  */
22 
23 #include <linux/poll.h>
24 #include <linux/slab.h>
25 #include <linux/mutex.h>
26 #include <linux/spinlock.h>
27 #include <linux/freezer.h>
28 #include <linux/major.h>
29 #include <linux/tpm_eventlog.h>
30 #include <linux/hw_random.h>
31 #include "tpm.h"
32 
33 DEFINE_IDR(dev_nums_idr);
34 static DEFINE_MUTEX(idr_lock);
35 
36 struct class *tpm_class;
37 struct class *tpmrm_class;
38 dev_t tpm_devt;
39 
40 /**
41  * tpm_try_get_ops() - Get a ref to the tpm_chip
42  * @chip: Chip to ref
43  *
44  * The caller must already have some kind of locking to ensure that chip is
45  * valid. This function will lock the chip so that the ops member can be
46  * accessed safely. The locking prevents tpm_chip_unregister from
47  * completing, so it should not be held for long periods.
48  *
49  * Returns -ERRNO if the chip could not be got.
50  */
51 int tpm_try_get_ops(struct tpm_chip *chip)
52 {
53 	int rc = -EIO;
54 
55 	get_device(&chip->dev);
56 
57 	down_read(&chip->ops_sem);
58 	if (!chip->ops)
59 		goto out_lock;
60 
61 	return 0;
62 out_lock:
63 	up_read(&chip->ops_sem);
64 	put_device(&chip->dev);
65 	return rc;
66 }
67 EXPORT_SYMBOL_GPL(tpm_try_get_ops);
68 
69 /**
70  * tpm_put_ops() - Release a ref to the tpm_chip
71  * @chip: Chip to put
72  *
73  * This is the opposite pair to tpm_try_get_ops(). After this returns chip may
74  * be kfree'd.
75  */
76 void tpm_put_ops(struct tpm_chip *chip)
77 {
78 	up_read(&chip->ops_sem);
79 	put_device(&chip->dev);
80 }
81 EXPORT_SYMBOL_GPL(tpm_put_ops);
82 
83 /**
84  * tpm_default_chip() - find a TPM chip and get a reference to it
85  */
86 struct tpm_chip *tpm_default_chip(void)
87 {
88 	struct tpm_chip *chip, *res = NULL;
89 	int chip_num = 0;
90 	int chip_prev;
91 
92 	mutex_lock(&idr_lock);
93 
94 	do {
95 		chip_prev = chip_num;
96 		chip = idr_get_next(&dev_nums_idr, &chip_num);
97 		if (chip) {
98 			get_device(&chip->dev);
99 			res = chip;
100 			break;
101 		}
102 	} while (chip_prev != chip_num);
103 
104 	mutex_unlock(&idr_lock);
105 
106 	return res;
107 }
108 EXPORT_SYMBOL_GPL(tpm_default_chip);
109 
110 /**
111  * tpm_find_get_ops() - find and reserve a TPM chip
112  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
113  *
114  * Finds a TPM chip and reserves its class device and operations. The chip must
115  * be released with tpm_put_ops() after use.
116  * This function is for internal use only. It supports existing TPM callers
117  * by accepting NULL, but those callers should be converted to pass in a chip
118  * directly.
119  *
120  * Return:
121  * A reserved &struct tpm_chip instance.
122  * %NULL if a chip is not found.
123  * %NULL if the chip is not available.
124  */
125 struct tpm_chip *tpm_find_get_ops(struct tpm_chip *chip)
126 {
127 	int rc;
128 
129 	if (chip) {
130 		if (!tpm_try_get_ops(chip))
131 			return chip;
132 		return NULL;
133 	}
134 
135 	chip = tpm_default_chip();
136 	if (!chip)
137 		return NULL;
138 	rc = tpm_try_get_ops(chip);
139 	/* release additional reference we got from tpm_default_chip() */
140 	put_device(&chip->dev);
141 	if (rc)
142 		return NULL;
143 	return chip;
144 }
145 
146 /**
147  * tpm_dev_release() - free chip memory and the device number
148  * @dev: the character device for the TPM chip
149  *
150  * This is used as the release function for the character device.
151  */
152 static void tpm_dev_release(struct device *dev)
153 {
154 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
155 
156 	mutex_lock(&idr_lock);
157 	idr_remove(&dev_nums_idr, chip->dev_num);
158 	mutex_unlock(&idr_lock);
159 
160 	kfree(chip->log.bios_event_log);
161 	kfree(chip->work_space.context_buf);
162 	kfree(chip->work_space.session_buf);
163 	kfree(chip);
164 }
165 
166 static void tpm_devs_release(struct device *dev)
167 {
168 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, devs);
169 
170 	/* release the master device reference */
171 	put_device(&chip->dev);
172 }
173 
174 /**
175  * tpm_class_shutdown() - prepare the TPM device for loss of power.
176  * @dev: device to which the chip is associated.
177  *
178  * Issues a TPM2_Shutdown command prior to loss of power, as required by the
179  * TPM 2.0 spec.
180  * Then, calls bus- and device- specific shutdown code.
181  *
182  * XXX: This codepath relies on the fact that sysfs is not enabled for
183  * TPM2: sysfs uses an implicit lock on chip->ops, so this could race if TPM2
184  * has sysfs support enabled before TPM sysfs's implicit locking is fixed.
185  */
186 static int tpm_class_shutdown(struct device *dev)
187 {
188 	struct tpm_chip *chip = container_of(dev, struct tpm_chip, dev);
189 
190 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
191 		down_write(&chip->ops_sem);
192 		tpm2_shutdown(chip, TPM2_SU_CLEAR);
193 		chip->ops = NULL;
194 		up_write(&chip->ops_sem);
195 	}
196 
197 	return 0;
198 }
199 
200 /**
201  * tpm_chip_alloc() - allocate a new struct tpm_chip instance
202  * @pdev: device to which the chip is associated
203  *        At this point pdev mst be initialized, but does not have to
204  *        be registered
205  * @ops: struct tpm_class_ops instance
206  *
207  * Allocates a new struct tpm_chip instance and assigns a free
208  * device number for it. Must be paired with put_device(&chip->dev).
209  */
210 struct tpm_chip *tpm_chip_alloc(struct device *pdev,
211 				const struct tpm_class_ops *ops)
212 {
213 	struct tpm_chip *chip;
214 	int rc;
215 
216 	chip = kzalloc(sizeof(*chip), GFP_KERNEL);
217 	if (chip == NULL)
218 		return ERR_PTR(-ENOMEM);
219 
220 	mutex_init(&chip->tpm_mutex);
221 	init_rwsem(&chip->ops_sem);
222 
223 	chip->ops = ops;
224 
225 	mutex_lock(&idr_lock);
226 	rc = idr_alloc(&dev_nums_idr, NULL, 0, TPM_NUM_DEVICES, GFP_KERNEL);
227 	mutex_unlock(&idr_lock);
228 	if (rc < 0) {
229 		dev_err(pdev, "No available tpm device numbers\n");
230 		kfree(chip);
231 		return ERR_PTR(rc);
232 	}
233 	chip->dev_num = rc;
234 
235 	device_initialize(&chip->dev);
236 	device_initialize(&chip->devs);
237 
238 	chip->dev.class = tpm_class;
239 	chip->dev.class->shutdown_pre = tpm_class_shutdown;
240 	chip->dev.release = tpm_dev_release;
241 	chip->dev.parent = pdev;
242 	chip->dev.groups = chip->groups;
243 
244 	chip->devs.parent = pdev;
245 	chip->devs.class = tpmrm_class;
246 	chip->devs.release = tpm_devs_release;
247 	/* get extra reference on main device to hold on
248 	 * behalf of devs.  This holds the chip structure
249 	 * while cdevs is in use.  The corresponding put
250 	 * is in the tpm_devs_release (TPM2 only)
251 	 */
252 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
253 		get_device(&chip->dev);
254 
255 	if (chip->dev_num == 0)
256 		chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
257 	else
258 		chip->dev.devt = MKDEV(MAJOR(tpm_devt), chip->dev_num);
259 
260 	chip->devs.devt =
261 		MKDEV(MAJOR(tpm_devt), chip->dev_num + TPM_NUM_DEVICES);
262 
263 	rc = dev_set_name(&chip->dev, "tpm%d", chip->dev_num);
264 	if (rc)
265 		goto out;
266 	rc = dev_set_name(&chip->devs, "tpmrm%d", chip->dev_num);
267 	if (rc)
268 		goto out;
269 
270 	if (!pdev)
271 		chip->flags |= TPM_CHIP_FLAG_VIRTUAL;
272 
273 	cdev_init(&chip->cdev, &tpm_fops);
274 	cdev_init(&chip->cdevs, &tpmrm_fops);
275 	chip->cdev.owner = THIS_MODULE;
276 	chip->cdevs.owner = THIS_MODULE;
277 
278 	chip->work_space.context_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
279 	if (!chip->work_space.context_buf) {
280 		rc = -ENOMEM;
281 		goto out;
282 	}
283 	chip->work_space.session_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
284 	if (!chip->work_space.session_buf) {
285 		rc = -ENOMEM;
286 		goto out;
287 	}
288 
289 	chip->locality = -1;
290 	return chip;
291 
292 out:
293 	put_device(&chip->devs);
294 	put_device(&chip->dev);
295 	return ERR_PTR(rc);
296 }
297 EXPORT_SYMBOL_GPL(tpm_chip_alloc);
298 
299 /**
300  * tpmm_chip_alloc() - allocate a new struct tpm_chip instance
301  * @pdev: parent device to which the chip is associated
302  * @ops: struct tpm_class_ops instance
303  *
304  * Same as tpm_chip_alloc except devm is used to do the put_device
305  */
306 struct tpm_chip *tpmm_chip_alloc(struct device *pdev,
307 				 const struct tpm_class_ops *ops)
308 {
309 	struct tpm_chip *chip;
310 	int rc;
311 
312 	chip = tpm_chip_alloc(pdev, ops);
313 	if (IS_ERR(chip))
314 		return chip;
315 
316 	rc = devm_add_action_or_reset(pdev,
317 				      (void (*)(void *)) put_device,
318 				      &chip->dev);
319 	if (rc)
320 		return ERR_PTR(rc);
321 
322 	dev_set_drvdata(pdev, chip);
323 
324 	return chip;
325 }
326 EXPORT_SYMBOL_GPL(tpmm_chip_alloc);
327 
328 static int tpm_add_char_device(struct tpm_chip *chip)
329 {
330 	int rc;
331 
332 	rc = cdev_device_add(&chip->cdev, &chip->dev);
333 	if (rc) {
334 		dev_err(&chip->dev,
335 			"unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
336 			dev_name(&chip->dev), MAJOR(chip->dev.devt),
337 			MINOR(chip->dev.devt), rc);
338 		return rc;
339 	}
340 
341 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
342 		rc = cdev_device_add(&chip->cdevs, &chip->devs);
343 		if (rc) {
344 			dev_err(&chip->devs,
345 				"unable to cdev_device_add() %s, major %d, minor %d, err=%d\n",
346 				dev_name(&chip->devs), MAJOR(chip->devs.devt),
347 				MINOR(chip->devs.devt), rc);
348 			return rc;
349 		}
350 	}
351 
352 	/* Make the chip available. */
353 	mutex_lock(&idr_lock);
354 	idr_replace(&dev_nums_idr, chip, chip->dev_num);
355 	mutex_unlock(&idr_lock);
356 
357 	return rc;
358 }
359 
360 static void tpm_del_char_device(struct tpm_chip *chip)
361 {
362 	cdev_device_del(&chip->cdev, &chip->dev);
363 
364 	/* Make the chip unavailable. */
365 	mutex_lock(&idr_lock);
366 	idr_replace(&dev_nums_idr, NULL, chip->dev_num);
367 	mutex_unlock(&idr_lock);
368 
369 	/* Make the driver uncallable. */
370 	down_write(&chip->ops_sem);
371 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
372 		tpm2_shutdown(chip, TPM2_SU_CLEAR);
373 	chip->ops = NULL;
374 	up_write(&chip->ops_sem);
375 }
376 
377 static void tpm_del_legacy_sysfs(struct tpm_chip *chip)
378 {
379 	struct attribute **i;
380 
381 	if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
382 		return;
383 
384 	sysfs_remove_link(&chip->dev.parent->kobj, "ppi");
385 
386 	for (i = chip->groups[0]->attrs; *i != NULL; ++i)
387 		sysfs_remove_link(&chip->dev.parent->kobj, (*i)->name);
388 }
389 
390 /* For compatibility with legacy sysfs paths we provide symlinks from the
391  * parent dev directory to selected names within the tpm chip directory. Old
392  * kernel versions created these files directly under the parent.
393  */
394 static int tpm_add_legacy_sysfs(struct tpm_chip *chip)
395 {
396 	struct attribute **i;
397 	int rc;
398 
399 	if (chip->flags & (TPM_CHIP_FLAG_TPM2 | TPM_CHIP_FLAG_VIRTUAL))
400 		return 0;
401 
402 	rc = __compat_only_sysfs_link_entry_to_kobj(
403 		    &chip->dev.parent->kobj, &chip->dev.kobj, "ppi");
404 	if (rc && rc != -ENOENT)
405 		return rc;
406 
407 	/* All the names from tpm-sysfs */
408 	for (i = chip->groups[0]->attrs; *i != NULL; ++i) {
409 		rc = __compat_only_sysfs_link_entry_to_kobj(
410 		    &chip->dev.parent->kobj, &chip->dev.kobj, (*i)->name);
411 		if (rc) {
412 			tpm_del_legacy_sysfs(chip);
413 			return rc;
414 		}
415 	}
416 
417 	return 0;
418 }
419 
420 static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
421 {
422 	struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng);
423 
424 	return tpm_get_random(chip, data, max);
425 }
426 
427 static int tpm_add_hwrng(struct tpm_chip *chip)
428 {
429 	if (!IS_ENABLED(CONFIG_HW_RANDOM_TPM))
430 		return 0;
431 
432 	snprintf(chip->hwrng_name, sizeof(chip->hwrng_name),
433 		 "tpm-rng-%d", chip->dev_num);
434 	chip->hwrng.name = chip->hwrng_name;
435 	chip->hwrng.read = tpm_hwrng_read;
436 	return hwrng_register(&chip->hwrng);
437 }
438 
439 /*
440  * tpm_chip_register() - create a character device for the TPM chip
441  * @chip: TPM chip to use.
442  *
443  * Creates a character device for the TPM chip and adds sysfs attributes for
444  * the device. As the last step this function adds the chip to the list of TPM
445  * chips available for in-kernel use.
446  *
447  * This function should be only called after the chip initialization is
448  * complete.
449  */
450 int tpm_chip_register(struct tpm_chip *chip)
451 {
452 	int rc;
453 
454 	rc = tpm_auto_startup(chip);
455 	if (rc)
456 		return rc;
457 
458 	tpm_sysfs_add_device(chip);
459 
460 	rc = tpm_bios_log_setup(chip);
461 	if (rc != 0 && rc != -ENODEV)
462 		return rc;
463 
464 	tpm_add_ppi(chip);
465 
466 	rc = tpm_add_hwrng(chip);
467 	if (rc)
468 		goto out_ppi;
469 
470 	rc = tpm_add_char_device(chip);
471 	if (rc)
472 		goto out_hwrng;
473 
474 	rc = tpm_add_legacy_sysfs(chip);
475 	if (rc) {
476 		tpm_chip_unregister(chip);
477 		return rc;
478 	}
479 
480 	return 0;
481 
482 out_hwrng:
483 	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
484 		hwrng_unregister(&chip->hwrng);
485 out_ppi:
486 	tpm_bios_log_teardown(chip);
487 
488 	return rc;
489 }
490 EXPORT_SYMBOL_GPL(tpm_chip_register);
491 
492 /*
493  * tpm_chip_unregister() - release the TPM driver
494  * @chip: TPM chip to use.
495  *
496  * Takes the chip first away from the list of available TPM chips and then
497  * cleans up all the resources reserved by tpm_chip_register().
498  *
499  * Once this function returns the driver call backs in 'op's will not be
500  * running and will no longer start.
501  *
502  * NOTE: This function should be only called before deinitializing chip
503  * resources.
504  */
505 void tpm_chip_unregister(struct tpm_chip *chip)
506 {
507 	tpm_del_legacy_sysfs(chip);
508 	if (IS_ENABLED(CONFIG_HW_RANDOM_TPM))
509 		hwrng_unregister(&chip->hwrng);
510 	tpm_bios_log_teardown(chip);
511 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
512 		cdev_device_del(&chip->cdevs, &chip->devs);
513 	tpm_del_char_device(chip);
514 }
515 EXPORT_SYMBOL_GPL(tpm_chip_unregister);
516