xref: /openbmc/linux/drivers/char/tpm/tpm-interface.c (revision d2e8071b)
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/suspend.h>
27 #include <linux/freezer.h>
28 #include <linux/tpm_eventlog.h>
29 
30 #include "tpm.h"
31 
32 /*
33  * Bug workaround - some TPM's don't flush the most
34  * recently changed pcr on suspend, so force the flush
35  * with an extend to the selected _unused_ non-volatile pcr.
36  */
37 static u32 tpm_suspend_pcr;
38 module_param_named(suspend_pcr, tpm_suspend_pcr, uint, 0644);
39 MODULE_PARM_DESC(suspend_pcr,
40 		 "PCR to use for dummy writes to facilitate flush on suspend.");
41 
42 /**
43  * tpm_calc_ordinal_duration() - calculate the maximum command duration
44  * @chip:    TPM chip to use.
45  * @ordinal: TPM command ordinal.
46  *
47  * The function returns the maximum amount of time the chip could take
48  * to return the result for a particular ordinal in jiffies.
49  *
50  * Return: A maximal duration time for an ordinal in jiffies.
51  */
tpm_calc_ordinal_duration(struct tpm_chip * chip,u32 ordinal)52 unsigned long tpm_calc_ordinal_duration(struct tpm_chip *chip, u32 ordinal)
53 {
54 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
55 		return tpm2_calc_ordinal_duration(chip, ordinal);
56 	else
57 		return tpm1_calc_ordinal_duration(chip, ordinal);
58 }
59 EXPORT_SYMBOL_GPL(tpm_calc_ordinal_duration);
60 
tpm_try_transmit(struct tpm_chip * chip,void * buf,size_t bufsiz)61 static ssize_t tpm_try_transmit(struct tpm_chip *chip, void *buf, size_t bufsiz)
62 {
63 	struct tpm_header *header = buf;
64 	int rc;
65 	ssize_t len = 0;
66 	u32 count, ordinal;
67 	unsigned long stop;
68 
69 	if (bufsiz < TPM_HEADER_SIZE)
70 		return -EINVAL;
71 
72 	if (bufsiz > TPM_BUFSIZE)
73 		bufsiz = TPM_BUFSIZE;
74 
75 	count = be32_to_cpu(header->length);
76 	ordinal = be32_to_cpu(header->ordinal);
77 	if (count == 0)
78 		return -ENODATA;
79 	if (count > bufsiz) {
80 		dev_err(&chip->dev,
81 			"invalid count value %x %zx\n", count, bufsiz);
82 		return -E2BIG;
83 	}
84 
85 	rc = chip->ops->send(chip, buf, count);
86 	if (rc < 0) {
87 		if (rc != -EPIPE)
88 			dev_err(&chip->dev,
89 				"%s: send(): error %d\n", __func__, rc);
90 		return rc;
91 	}
92 
93 	/* A sanity check. send() should just return zero on success e.g.
94 	 * not the command length.
95 	 */
96 	if (rc > 0) {
97 		dev_warn(&chip->dev,
98 			 "%s: send(): invalid value %d\n", __func__, rc);
99 		rc = 0;
100 	}
101 
102 	if (chip->flags & TPM_CHIP_FLAG_IRQ)
103 		goto out_recv;
104 
105 	stop = jiffies + tpm_calc_ordinal_duration(chip, ordinal);
106 	do {
107 		u8 status = chip->ops->status(chip);
108 		if ((status & chip->ops->req_complete_mask) ==
109 		    chip->ops->req_complete_val)
110 			goto out_recv;
111 
112 		if (chip->ops->req_canceled(chip, status)) {
113 			dev_err(&chip->dev, "Operation Canceled\n");
114 			return -ECANCELED;
115 		}
116 
117 		tpm_msleep(TPM_TIMEOUT_POLL);
118 		rmb();
119 	} while (time_before(jiffies, stop));
120 
121 	chip->ops->cancel(chip);
122 	dev_err(&chip->dev, "Operation Timed out\n");
123 	return -ETIME;
124 
125 out_recv:
126 	len = chip->ops->recv(chip, buf, bufsiz);
127 	if (len < 0) {
128 		rc = len;
129 		dev_err(&chip->dev, "tpm_transmit: tpm_recv: error %d\n", rc);
130 	} else if (len < TPM_HEADER_SIZE || len != be32_to_cpu(header->length))
131 		rc = -EFAULT;
132 
133 	return rc ? rc : len;
134 }
135 
136 /**
137  * tpm_transmit - Internal kernel interface to transmit TPM commands.
138  * @chip:	a TPM chip to use
139  * @buf:	a TPM command buffer
140  * @bufsiz:	length of the TPM command buffer
141  *
142  * A wrapper around tpm_try_transmit() that handles TPM2_RC_RETRY returns from
143  * the TPM and retransmits the command after a delay up to a maximum wait of
144  * TPM2_DURATION_LONG.
145  *
146  * Note that TPM 1.x never returns TPM2_RC_RETRY so the retry logic is TPM 2.0
147  * only.
148  *
149  * Return:
150  * * The response length	- OK
151  * * -errno			- A system error
152  */
tpm_transmit(struct tpm_chip * chip,u8 * buf,size_t bufsiz)153 ssize_t tpm_transmit(struct tpm_chip *chip, u8 *buf, size_t bufsiz)
154 {
155 	struct tpm_header *header = (struct tpm_header *)buf;
156 	/* space for header and handles */
157 	u8 save[TPM_HEADER_SIZE + 3*sizeof(u32)];
158 	unsigned int delay_msec = TPM2_DURATION_SHORT;
159 	u32 rc = 0;
160 	ssize_t ret;
161 	const size_t save_size = min(sizeof(save), bufsiz);
162 	/* the command code is where the return code will be */
163 	u32 cc = be32_to_cpu(header->return_code);
164 
165 	/*
166 	 * Subtlety here: if we have a space, the handles will be
167 	 * transformed, so when we restore the header we also have to
168 	 * restore the handles.
169 	 */
170 	memcpy(save, buf, save_size);
171 
172 	for (;;) {
173 		ret = tpm_try_transmit(chip, buf, bufsiz);
174 		if (ret < 0)
175 			break;
176 		rc = be32_to_cpu(header->return_code);
177 		if (rc != TPM2_RC_RETRY && rc != TPM2_RC_TESTING)
178 			break;
179 		/*
180 		 * return immediately if self test returns test
181 		 * still running to shorten boot time.
182 		 */
183 		if (rc == TPM2_RC_TESTING && cc == TPM2_CC_SELF_TEST)
184 			break;
185 
186 		if (delay_msec > TPM2_DURATION_LONG) {
187 			if (rc == TPM2_RC_RETRY)
188 				dev_err(&chip->dev, "in retry loop\n");
189 			else
190 				dev_err(&chip->dev,
191 					"self test is still running\n");
192 			break;
193 		}
194 		tpm_msleep(delay_msec);
195 		delay_msec *= 2;
196 		memcpy(buf, save, save_size);
197 	}
198 	return ret;
199 }
200 
201 /**
202  * tpm_transmit_cmd - send a tpm command to the device
203  * @chip:			a TPM chip to use
204  * @buf:			a TPM command buffer
205  * @min_rsp_body_length:	minimum expected length of response body
206  * @desc:			command description used in the error message
207  *
208  * Return:
209  * * 0		- OK
210  * * -errno	- A system error
211  * * TPM_RC	- A TPM error
212  */
tpm_transmit_cmd(struct tpm_chip * chip,struct tpm_buf * buf,size_t min_rsp_body_length,const char * desc)213 ssize_t tpm_transmit_cmd(struct tpm_chip *chip, struct tpm_buf *buf,
214 			 size_t min_rsp_body_length, const char *desc)
215 {
216 	const struct tpm_header *header = (struct tpm_header *)buf->data;
217 	int err;
218 	ssize_t len;
219 
220 	len = tpm_transmit(chip, buf->data, PAGE_SIZE);
221 	if (len <  0)
222 		return len;
223 
224 	err = be32_to_cpu(header->return_code);
225 	if (err != 0 && err != TPM_ERR_DISABLED && err != TPM_ERR_DEACTIVATED
226 	    && err != TPM2_RC_TESTING && desc)
227 		dev_err(&chip->dev, "A TPM error (%d) occurred %s\n", err,
228 			desc);
229 	if (err)
230 		return err;
231 
232 	if (len < min_rsp_body_length + TPM_HEADER_SIZE)
233 		return -EFAULT;
234 
235 	return 0;
236 }
237 EXPORT_SYMBOL_GPL(tpm_transmit_cmd);
238 
tpm_get_timeouts(struct tpm_chip * chip)239 int tpm_get_timeouts(struct tpm_chip *chip)
240 {
241 	if (chip->flags & TPM_CHIP_FLAG_HAVE_TIMEOUTS)
242 		return 0;
243 
244 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
245 		return tpm2_get_timeouts(chip);
246 	else
247 		return tpm1_get_timeouts(chip);
248 }
249 EXPORT_SYMBOL_GPL(tpm_get_timeouts);
250 
251 /**
252  * tpm_is_tpm2 - do we a have a TPM2 chip?
253  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
254  *
255  * Return:
256  * 1 if we have a TPM2 chip.
257  * 0 if we don't have a TPM2 chip.
258  * A negative number for system errors (errno).
259  */
tpm_is_tpm2(struct tpm_chip * chip)260 int tpm_is_tpm2(struct tpm_chip *chip)
261 {
262 	int rc;
263 
264 	chip = tpm_find_get_ops(chip);
265 	if (!chip)
266 		return -ENODEV;
267 
268 	rc = (chip->flags & TPM_CHIP_FLAG_TPM2) != 0;
269 
270 	tpm_put_ops(chip);
271 
272 	return rc;
273 }
274 EXPORT_SYMBOL_GPL(tpm_is_tpm2);
275 
276 /**
277  * tpm_pcr_read - read a PCR value from SHA1 bank
278  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
279  * @pcr_idx:	the PCR to be retrieved
280  * @digest:	the PCR bank and buffer current PCR value is written to
281  *
282  * Return: same as with tpm_transmit_cmd()
283  */
tpm_pcr_read(struct tpm_chip * chip,u32 pcr_idx,struct tpm_digest * digest)284 int tpm_pcr_read(struct tpm_chip *chip, u32 pcr_idx,
285 		 struct tpm_digest *digest)
286 {
287 	int rc;
288 
289 	chip = tpm_find_get_ops(chip);
290 	if (!chip)
291 		return -ENODEV;
292 
293 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
294 		rc = tpm2_pcr_read(chip, pcr_idx, digest, NULL);
295 	else
296 		rc = tpm1_pcr_read(chip, pcr_idx, digest->digest);
297 
298 	tpm_put_ops(chip);
299 	return rc;
300 }
301 EXPORT_SYMBOL_GPL(tpm_pcr_read);
302 
303 /**
304  * tpm_pcr_extend - extend a PCR value in SHA1 bank.
305  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
306  * @pcr_idx:	the PCR to be retrieved
307  * @digests:	array of tpm_digest structures used to extend PCRs
308  *
309  * Note: callers must pass a digest for every allocated PCR bank, in the same
310  * order of the banks in chip->allocated_banks.
311  *
312  * Return: same as with tpm_transmit_cmd()
313  */
tpm_pcr_extend(struct tpm_chip * chip,u32 pcr_idx,struct tpm_digest * digests)314 int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
315 		   struct tpm_digest *digests)
316 {
317 	int rc;
318 	int i;
319 
320 	chip = tpm_find_get_ops(chip);
321 	if (!chip)
322 		return -ENODEV;
323 
324 	for (i = 0; i < chip->nr_allocated_banks; i++) {
325 		if (digests[i].alg_id != chip->allocated_banks[i].alg_id) {
326 			rc = -EINVAL;
327 			goto out;
328 		}
329 	}
330 
331 	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
332 		rc = tpm2_pcr_extend(chip, pcr_idx, digests);
333 		goto out;
334 	}
335 
336 	rc = tpm1_pcr_extend(chip, pcr_idx, digests[0].digest,
337 			     "attempting extend a PCR value");
338 
339 out:
340 	tpm_put_ops(chip);
341 	return rc;
342 }
343 EXPORT_SYMBOL_GPL(tpm_pcr_extend);
344 
345 /**
346  * tpm_send - send a TPM command
347  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
348  * @cmd:	a TPM command buffer
349  * @buflen:	the length of the TPM command buffer
350  *
351  * Return: same as with tpm_transmit_cmd()
352  */
tpm_send(struct tpm_chip * chip,void * cmd,size_t buflen)353 int tpm_send(struct tpm_chip *chip, void *cmd, size_t buflen)
354 {
355 	struct tpm_buf buf;
356 	int rc;
357 
358 	chip = tpm_find_get_ops(chip);
359 	if (!chip)
360 		return -ENODEV;
361 
362 	buf.data = cmd;
363 	rc = tpm_transmit_cmd(chip, &buf, 0, "attempting to a send a command");
364 
365 	tpm_put_ops(chip);
366 	return rc;
367 }
368 EXPORT_SYMBOL_GPL(tpm_send);
369 
tpm_auto_startup(struct tpm_chip * chip)370 int tpm_auto_startup(struct tpm_chip *chip)
371 {
372 	int rc;
373 
374 	if (!(chip->ops->flags & TPM_OPS_AUTO_STARTUP))
375 		return 0;
376 
377 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
378 		rc = tpm2_auto_startup(chip);
379 	else
380 		rc = tpm1_auto_startup(chip);
381 
382 	return rc;
383 }
384 
385 /*
386  * We are about to suspend. Save the TPM state
387  * so that it can be restored.
388  */
tpm_pm_suspend(struct device * dev)389 int tpm_pm_suspend(struct device *dev)
390 {
391 	struct tpm_chip *chip = dev_get_drvdata(dev);
392 	int rc = 0;
393 
394 	if (!chip)
395 		return -ENODEV;
396 
397 	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
398 		goto suspended;
399 
400 	if ((chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED) &&
401 	    !pm_suspend_via_firmware())
402 		goto suspended;
403 
404 	rc = tpm_try_get_ops(chip);
405 	if (!rc) {
406 		if (chip->flags & TPM_CHIP_FLAG_TPM2)
407 			tpm2_shutdown(chip, TPM2_SU_STATE);
408 		else
409 			rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);
410 
411 		tpm_put_ops(chip);
412 	}
413 
414 suspended:
415 	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
416 
417 	if (rc)
418 		dev_err(dev, "Ignoring error %d while suspending\n", rc);
419 	return 0;
420 }
421 EXPORT_SYMBOL_GPL(tpm_pm_suspend);
422 
423 /*
424  * Resume from a power safe. The BIOS already restored
425  * the TPM state.
426  */
tpm_pm_resume(struct device * dev)427 int tpm_pm_resume(struct device *dev)
428 {
429 	struct tpm_chip *chip = dev_get_drvdata(dev);
430 
431 	if (chip == NULL)
432 		return -ENODEV;
433 
434 	chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED;
435 
436 	/*
437 	 * Guarantee that SUSPENDED is written last, so that hwrng does not
438 	 * activate before the chip has been fully resumed.
439 	 */
440 	wmb();
441 
442 	return 0;
443 }
444 EXPORT_SYMBOL_GPL(tpm_pm_resume);
445 
446 /**
447  * tpm_get_random() - get random bytes from the TPM's RNG
448  * @chip:	a &struct tpm_chip instance, %NULL for the default chip
449  * @out:	destination buffer for the random bytes
450  * @max:	the max number of bytes to write to @out
451  *
452  * Return: number of random bytes read or a negative error value.
453  */
tpm_get_random(struct tpm_chip * chip,u8 * out,size_t max)454 int tpm_get_random(struct tpm_chip *chip, u8 *out, size_t max)
455 {
456 	int rc;
457 
458 	if (!out || max > TPM_MAX_RNG_DATA)
459 		return -EINVAL;
460 
461 	chip = tpm_find_get_ops(chip);
462 	if (!chip)
463 		return -ENODEV;
464 
465 	if (chip->flags & TPM_CHIP_FLAG_TPM2)
466 		rc = tpm2_get_random(chip, out, max);
467 	else
468 		rc = tpm1_get_random(chip, out, max);
469 
470 	tpm_put_ops(chip);
471 	return rc;
472 }
473 EXPORT_SYMBOL_GPL(tpm_get_random);
474 
tpm_init(void)475 static int __init tpm_init(void)
476 {
477 	int rc;
478 
479 	rc = class_register(&tpm_class);
480 	if (rc) {
481 		pr_err("couldn't create tpm class\n");
482 		return rc;
483 	}
484 
485 	rc = class_register(&tpmrm_class);
486 	if (rc) {
487 		pr_err("couldn't create tpmrm class\n");
488 		goto out_destroy_tpm_class;
489 	}
490 
491 	rc = alloc_chrdev_region(&tpm_devt, 0, 2*TPM_NUM_DEVICES, "tpm");
492 	if (rc < 0) {
493 		pr_err("tpm: failed to allocate char dev region\n");
494 		goto out_destroy_tpmrm_class;
495 	}
496 
497 	rc = tpm_dev_common_init();
498 	if (rc) {
499 		pr_err("tpm: failed to allocate char dev region\n");
500 		goto out_unreg_chrdev;
501 	}
502 
503 	return 0;
504 
505 out_unreg_chrdev:
506 	unregister_chrdev_region(tpm_devt, 2 * TPM_NUM_DEVICES);
507 out_destroy_tpmrm_class:
508 	class_unregister(&tpmrm_class);
509 out_destroy_tpm_class:
510 	class_unregister(&tpm_class);
511 
512 	return rc;
513 }
514 
tpm_exit(void)515 static void __exit tpm_exit(void)
516 {
517 	idr_destroy(&dev_nums_idr);
518 	class_unregister(&tpm_class);
519 	class_unregister(&tpmrm_class);
520 	unregister_chrdev_region(tpm_devt, 2*TPM_NUM_DEVICES);
521 	tpm_dev_common_exit();
522 }
523 
524 subsys_initcall(tpm_init);
525 module_exit(tpm_exit);
526 
527 MODULE_AUTHOR("Leendert van Doorn (leendert@watson.ibm.com)");
528 MODULE_DESCRIPTION("TPM Driver");
529 MODULE_VERSION("2.0");
530 MODULE_LICENSE("GPL");
531