xref: /linux/drivers/char/tpm/tpm-interface.c (revision 17cfcb68af3bc7d5e8ae08779b1853310a2949f3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2004 IBM Corporation
4  * Copyright (C) 2014 Intel Corporation
5  *
6  * Authors:
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  * Device driver for TCG/TCPA TPM (trusted platform module).
15  * Specifications at www.trustedcomputinggroup.org
16  *
17  * Note, the TPM chip is not interrupt driven (only polling)
18  * and can have very long timeouts (minutes!). Hence the unusual
19  * calls to msleep.
20  */
21 
22 #include <linux/poll.h>
23 #include <linux/slab.h>
24 #include <linux/mutex.h>
25 #include <linux/spinlock.h>
26 #include <linux/freezer.h>
27 #include <linux/tpm_eventlog.h>
28 
29 #include "tpm.h"
30 
31 /*
32  * Bug workaround - some TPM's don't flush the most
33  * recently changed pcr on suspend, so force the flush
34  * with an extend to the selected _unused_ non-volatile pcr.
35  */
36 static u32 tpm_suspend_pcr;
37 module_param_named(suspend_pcr, tpm_suspend_pcr, uint, 0644);
38 MODULE_PARM_DESC(suspend_pcr,
39 		 "PCR to use for dummy writes to facilitate flush on suspend.");
40 
41 /**
42  * tpm_calc_ordinal_duration() - calculate the maximum command duration
43  * @chip:    TPM chip to use.
44  * @ordinal: TPM command ordinal.
45  *
46  * The function returns the maximum amount of time the chip could take
47  * to return the result for a particular ordinal in jiffies.
48  *
49  * Return: A maximal duration time for an ordinal in jiffies.
50  */
51 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
52 {
53 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
54 		return tpm2_calc_ordinal_duration(chip, ordinal);
55 	else
56 		return tpm1_calc_ordinal_duration(chip, ordinal);
57 }
58 EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
59 
60 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
61 {
62 	struct tpm_header *header = buf;
63 	int rc;
64 	ssize_t len = 0;
65 	u32 count, ordinal;
66 	unsigned long stop;
67 
68 	if (bufsiz < TPM_HEADER_SIZE)
69 		return -EINVAL;
70 
71 	if (bufsiz > TPM_BUFSIZE)
72 		bufsiz = TPM_BUFSIZE;
73 
74 	count = be32_to_cpu(header->length);
75 	ordinal = be32_to_cpu(header->ordinal);
76 	if (count == 0)
77 		return -ENODATA;
78 	if (count > bufsiz) {
79 		dev_err(&chip->dev,
80 			"invalid count value %x %zx\n", count, bufsiz);
81 		return -E2BIG;
82 	}
83 
84 	rc = chip->ops->send(chip, buf, count);
85 	if (rc < 0) {
86 		if (rc != -EPIPE)
87 			dev_err(&chip->dev,
88 				"%s: send(): error %d\n", __func__, rc);
89 		return rc;
90 	}
91 
92 	/* A sanity check. send() should just return zero on success e.g.
93 	 * not the command length.
94 	 */
95 	if (rc > 0) {
96 		dev_warn(&chip->dev,
97 			 "%s: send(): invalid value %d\n", __func__, rc);
98 		rc = 0;
99 	}
100 
101 	if (chip->flags & TPM_CHIP_FLAG_IRQ)
102 		goto out_recv;
103 
104 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
105 	do {
106 		u8 status = chip->ops->status(chip);
107 		if ((status & chip->ops->req_complete_mask) ==
108 		    chip->ops->req_complete_val)
109 			goto out_recv;
110 
111 		if (chip->ops->req_canceled(chip, status)) {
112 			dev_err(&chip->dev, "Operation Canceled\n");
113 			return -ECANCELED;
114 		}
115 
116 		tpm_msleep(TPM_TIMEOUT_POLL);
117 		rmb();
118 	} while (time_before(jiffies, stop));
119 
120 	chip->ops->cancel(chip);
121 	dev_err(&chip->dev, "Operation Timed out\n");
122 	return -ETIME;
123 
124 out_recv:
125 	len = chip->ops->recv(chip, buf, bufsiz);
126 	if (len < 0) {
127 		rc = len;
128 		dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
129 	} else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
130 		rc = -EFAULT;
131 
132 	return rc ? rc : len;
133 }
134 
135 /**
136  * tpm_transmit - Internal kernel interface to transmit TPM commands.
137  * @chip:	a TPM chip to use
138  * @buf:	a TPM command buffer
139  * @bufsiz:	length of the TPM command buffer
140  *
141  * A wrapper around tpm_try_transmit() that handles TPM2_RC_RETRY returns from
142  * the TPM and retransmits the command after a delay up to a maximum wait of
143  * TPM2_DURATION_LONG.
144  *
145  * Note that TPM 1.x never returns TPM2_RC_RETRY so the retry logic is TPM 2.0
146  * only.
147  *
148  * Return:
149  * * The response length	- OK
150  * * -errno			- A system error
151  */
152 ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz)
153 {
154 	struct tpm_header *header = (struct tpm_header *)buf;
155 	/* space for header and handles */
156 	u8 save[TPM_HEADER_SIZE + 3*sizeof(u32)];
157 	unsigned int delay_msec = TPM2_DURATION_SHORT;
158 	u32 rc = 0;
159 	ssize_t ret;
160 	const size_t save_size = min(sizeof(save), bufsiz);
161 	/* the command code is where the return code will be */
162 	u32 cc = be32_to_cpu(header->return_code);
163 
164 	/*
165 	 * Subtlety here: if we have a space, the handles will be
166 	 * transformed, so when we restore the header we also have to
167 	 * restore the handles.
168 	 */
169 	memcpy(save, buf, save_size);
170 
171 	for (;;) {
172 		ret = tpm_try_transmit(chip, buf, bufsiz);
173 		if (ret < 0)
174 			break;
175 		rc = be32_to_cpu(header->return_code);
176 		if (rc != TPM2_RC_RETRY && rc != TPM2_RC_TESTING)
177 			break;
178 		/*
179 		 * return immediately if self test returns test
180 		 * still running to shorten boot time.
181 		 */
182 		if (rc == TPM2_RC_TESTING && cc == TPM2_CC_SELF_TEST)
183 			break;
184 
185 		if (delay_msec > TPM2_DURATION_LONG) {
186 			if (rc == TPM2_RC_RETRY)
187 				dev_err(&chip->dev, "in retry loop\n");
188 			else
189 				dev_err(&chip->dev,
190 					"self test is still running\n");
191 			break;
192 		}
193 		tpm_msleep(delay_msec);
194 		delay_msec *= 2;
195 		memcpy(buf, save, save_size);
196 	}
197 	return ret;
198 }
199 
200 /**
201  * tpm_transmit_cmd - send a tpm command to the device
202  * @chip:			a TPM chip to use
203  * @buf:			a TPM command buffer
204  * @min_rsp_body_length:	minimum expected length of response body
205  * @desc:			command description used in the error message
206  *
207  * Return:
208  * * 0		- OK
209  * * -errno	- A system error
210  * * TPM_RC	- A TPM error
211  */
212 ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
213 			 size_t min_rsp_body_length, const char *desc)
214 {
215 	const struct tpm_header *header = (struct tpm_header *)buf->data;
216 	int err;
217 	ssize_t len;
218 
219 	len = tpm_transmit(chip, buf->data, PAGE_SIZE);
220 	if (len <  0)
221 		return len;
222 
223 	err = be32_to_cpu(header->return_code);
224 	if (err != 0 && err != TPM_ERR_DISABLED && err != TPM_ERR_DEACTIVATED
225 	    && err != TPM2_RC_TESTING && desc)
226 		dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
227 			desc);
228 	if (err)
229 		return err;
230 
231 	if (len < min_rsp_body_length + TPM_HEADER_SIZE)
232 		return -EFAULT;
233 
234 	return 0;
235 }
236 EXPORT_SYMBOL_GPL(tpm_transmit_cmd);
237 
238 int tpm_get_timeouts(struct tpm_chip *chip)
239 {
240 	if (chip->flags & TPM_CHIP_FLAG_HAVE_TIMEOUTS)
241 		return 0;
242 
243 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
244 		return tpm2_get_timeouts(chip);
245 	else
246 		return tpm1_get_timeouts(chip);
247 }
248 EXPORT_SYMBOL_GPL(tpm_get_timeouts);
249 
250 /**
251  * tpm_is_tpm2 - do we a have a TPM2 chip?
252  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
253  *
254  * Return:
255  * 1 if we have a TPM2 chip.
256  * 0 if we don't have a TPM2 chip.
257  * A negative number for system errors (errno).
258  */
259 int tpm_is_tpm2(struct tpm_chip *chip)
260 {
261 	int rc;
262 
263 	chip = tpm_find_get_ops(chip);
264 	if (!chip)
265 		return -ENODEV;
266 
267 	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) != 0;
268 
269 	tpm_put_ops(chip);
270 
271 	return rc;
272 }
273 EXPORT_SYMBOL_GPL(tpm_is_tpm2);
274 
275 /**
276  * tpm_pcr_read - read a PCR value from SHA1 bank
277  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
278  * @pcr_idx:	the PCR to be retrieved
279  * @digest:	the PCR bank and buffer current PCR value is written to
280  *
281  * Return: same as with tpm_transmit_cmd()
282  */
283 int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
284 		 struct tpm_digest *digest)
285 {
286 	int rc;
287 
288 	chip = tpm_find_get_ops(chip);
289 	if (!chip)
290 		return -ENODEV;
291 
292 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
293 		rc = tpm2_pcr_read(chip, pcr_idx, digest, NULL);
294 	else
295 		rc = tpm1_pcr_read(chip, pcr_idx, digest->digest);
296 
297 	tpm_put_ops(chip);
298 	return rc;
299 }
300 EXPORT_SYMBOL_GPL(tpm_pcr_read);
301 
302 /**
303  * tpm_pcr_extend - extend a PCR value in SHA1 bank.
304  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
305  * @pcr_idx:	the PCR to be retrieved
306  * @digests:	array of tpm_digest structures used to extend PCRs
307  *
308  * Note: callers must pass a digest for every allocated PCR bank, in the same
309  * order of the banks in chip->allocated_banks.
310  *
311  * Return: same as with tpm_transmit_cmd()
312  */
313 int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
314 		   struct tpm_digest *digests)
315 {
316 	int rc;
317 	int i;
318 
319 	chip = tpm_find_get_ops(chip);
320 	if (!chip)
321 		return -ENODEV;
322 
323 	for (i = 0; i < chip->nr_allocated_banks; i++) {
324 		if (digests[i].alg_id != chip->allocated_banks[i].alg_id) {
325 			rc = EINVAL;
326 			goto out;
327 		}
328 	}
329 
330 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
331 		rc = tpm2_pcr_extend(chip, pcr_idx, digests);
332 		goto out;
333 	}
334 
335 	rc = tpm1_pcr_extend(chip, pcr_idx, digests[0].digest,
336 			     "attempting extend a PCR value");
337 
338 out:
339 	tpm_put_ops(chip);
340 	return rc;
341 }
342 EXPORT_SYMBOL_GPL(tpm_pcr_extend);
343 
344 /**
345  * tpm_send - send a TPM command
346  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
347  * @cmd:	a TPM command buffer
348  * @buflen:	the length of the TPM command buffer
349  *
350  * Return: same as with tpm_transmit_cmd()
351  */
352 int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
353 {
354 	struct tpm_buf buf;
355 	int rc;
356 
357 	chip = tpm_find_get_ops(chip);
358 	if (!chip)
359 		return -ENODEV;
360 
361 	buf.data = cmd;
362 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
363 
364 	tpm_put_ops(chip);
365 	return rc;
366 }
367 EXPORT_SYMBOL_GPL(tpm_send);
368 
369 int tpm_auto_startup(struct tpm_chip *chip)
370 {
371 	int rc;
372 
373 	if (!(chip->ops->flags & TPM_OPS_AUTO_STARTUP))
374 		return 0;
375 
376 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
377 		rc = tpm2_auto_startup(chip);
378 	else
379 		rc = tpm1_auto_startup(chip);
380 
381 	return rc;
382 }
383 
384 /*
385  * We are about to suspend. Save the TPM state
386  * so that it can be restored.
387  */
388 int tpm_pm_suspend(struct device *dev)
389 {
390 	struct tpm_chip *chip = dev_get_drvdata(dev);
391 	int rc = 0;
392 
393 	if (!chip)
394 		return -ENODEV;
395 
396 	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
397 		return 0;
398 
399 	if (!tpm_chip_start(chip)) {
400 		if (chip->flags & TPM_CHIP_FLAG_TPM2)
401 			tpm2_shutdown(chip, TPM2_SU_STATE);
402 		else
403 			rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);
404 
405 		tpm_chip_stop(chip);
406 	}
407 
408 	return rc;
409 }
410 EXPORT_SYMBOL_GPL(tpm_pm_suspend);
411 
412 /*
413  * Resume from a power safe. The BIOS already restored
414  * the TPM state.
415  */
416 int tpm_pm_resume(struct device *dev)
417 {
418 	struct tpm_chip *chip = dev_get_drvdata(dev);
419 
420 	if (chip == NULL)
421 		return -ENODEV;
422 
423 	return 0;
424 }
425 EXPORT_SYMBOL_GPL(tpm_pm_resume);
426 
427 /**
428  * tpm_get_random() - get random bytes from the TPM's RNG
429  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
430  * @out:	destination buffer for the random bytes
431  * @max:	the max number of bytes to write to @out
432  *
433  * Return: number of random bytes read or a negative error value.
434  */
435 int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
436 {
437 	int rc;
438 
439 	if (!out || max > TPM_MAX_RNG_DATA)
440 		return -EINVAL;
441 
442 	chip = tpm_find_get_ops(chip);
443 	if (!chip)
444 		return -ENODEV;
445 
446 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
447 		rc = tpm2_get_random(chip, out, max);
448 	else
449 		rc = tpm1_get_random(chip, out, max);
450 
451 	tpm_put_ops(chip);
452 	return rc;
453 }
454 EXPORT_SYMBOL_GPL(tpm_get_random);
455 
456 /**
457  * tpm_seal_trusted() - seal a trusted key payload
458  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
459  * @options:	authentication values and other options
460  * @payload:	the key data in clear and encrypted form
461  *
462  * Note: only TPM 2.0 chip are supported. TPM 1.x implementation is located in
463  * the keyring subsystem.
464  *
465  * Return: same as with tpm_transmit_cmd()
466  */
467 int tpm_seal_trusted(struct tpm_chip *chip, struct trusted_key_payload *payload,
468 		     struct trusted_key_options *options)
469 {
470 	int rc;
471 
472 	chip = tpm_find_get_ops(chip);
473 	if (!chip || !(chip->flags & TPM_CHIP_FLAG_TPM2))
474 		return -ENODEV;
475 
476 	rc = tpm2_seal_trusted(chip, payload, options);
477 
478 	tpm_put_ops(chip);
479 	return rc;
480 }
481 EXPORT_SYMBOL_GPL(tpm_seal_trusted);
482 
483 /**
484  * tpm_unseal_trusted() - unseal a trusted key
485  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
486  * @options:	authentication values and other options
487  * @payload:	the key data in clear and encrypted form
488  *
489  * Note: only TPM 2.0 chip are supported. TPM 1.x implementation is located in
490  * the keyring subsystem.
491  *
492  * Return: same as with tpm_transmit_cmd()
493  */
494 int tpm_unseal_trusted(struct tpm_chip *chip,
495 		       struct trusted_key_payload *payload,
496 		       struct trusted_key_options *options)
497 {
498 	int rc;
499 
500 	chip = tpm_find_get_ops(chip);
501 	if (!chip || !(chip->flags & TPM_CHIP_FLAG_TPM2))
502 		return -ENODEV;
503 
504 	rc = tpm2_unseal_trusted(chip, payload, options);
505 
506 	tpm_put_ops(chip);
507 
508 	return rc;
509 }
510 EXPORT_SYMBOL_GPL(tpm_unseal_trusted);
511 
512 static int __init tpm_init(void)
513 {
514 	int rc;
515 
516 	tpm_class = class_create(THIS_MODULE, "tpm");
517 	if (IS_ERR(tpm_class)) {
518 		pr_err("couldn't create tpm class\n");
519 		return PTR_ERR(tpm_class);
520 	}
521 
522 	tpmrm_class = class_create(THIS_MODULE, "tpmrm");
523 	if (IS_ERR(tpmrm_class)) {
524 		pr_err("couldn't create tpmrm class\n");
525 		rc = PTR_ERR(tpmrm_class);
526 		goto out_destroy_tpm_class;
527 	}
528 
529 	rc = alloc_chrdev_region(&tpm_devt, 0, 2*TPM_NUM_DEVICES, "tpm");
530 	if (rc < 0) {
531 		pr_err("tpm: failed to allocate char dev region\n");
532 		goto out_destroy_tpmrm_class;
533 	}
534 
535 	rc = tpm_dev_common_init();
536 	if (rc) {
537 		pr_err("tpm: failed to allocate char dev region\n");
538 		goto out_unreg_chrdev;
539 	}
540 
541 	return 0;
542 
543 out_unreg_chrdev:
544 	unregister_chrdev_region(tpm_devt, 2 * TPM_NUM_DEVICES);
545 out_destroy_tpmrm_class:
546 	class_destroy(tpmrm_class);
547 out_destroy_tpm_class:
548 	class_destroy(tpm_class);
549 
550 	return rc;
551 }
552 
553 static void __exit tpm_exit(void)
554 {
555 	idr_destroy(&dev_nums_idr);
556 	class_destroy(tpm_class);
557 	class_destroy(tpmrm_class);
558 	unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
559 	tpm_dev_common_exit();
560 }
561 
562 subsys_initcall(tpm_init);
563 module_exit(tpm_exit);
564 
565 MODULE_AUTHOR("Leendert van Doorn (leendert@watson.ibm.com)");
566 MODULE_DESCRIPTION("TPM Driver");
567 MODULE_VERSION("2.0");
568 MODULE_LICENSE("GPL");
569