summaryrefslogtreecommitdiff
path: root/drivers/char/tpm/tpm_ftpm_tee.c
blob: 6e3235565a4d8ee86cd79aea7d034d03a2d6938a (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) Microsoft Corporation
 *
 * Implements a firmware TPM as described here:
 * https://www.microsoft.com/en-us/research/publication/ftpm-software-implementation-tpm-chip/
 *
 * A reference implementation is available here:
 * https://github.com/microsoft/ms-tpm-20-ref/tree/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM
 */

#include <linux/acpi.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/tee_drv.h>
#include <linux/tpm.h>
#include <linux/uuid.h>

#include "tpm.h"
#include "tpm_ftpm_tee.h"

/*
 * TA_FTPM_UUID: BC50D971-D4C9-42C4-82CB-343FB7F37896
 *
 * Randomly generated, and must correspond to the GUID on the TA side.
 * Defined here in the reference implementation:
 * https://github.com/microsoft/ms-tpm-20-ref/blob/master/Samples/ARM32-FirmwareTPM/optee_ta/fTPM/include/fTPM.h#L42
 */
static const uuid_t ftpm_ta_uuid =
	UUID_INIT(0xBC50D971, 0xD4C9, 0x42C4,
		  0x82, 0xCB, 0x34, 0x3F, 0xB7, 0xF3, 0x78, 0x96);

/**
 * ftpm_tee_tpm_op_recv() - retrieve fTPM response.
 * @chip:	the tpm_chip description as specified in driver/char/tpm/tpm.h.
 * @buf:	the buffer to store data.
 * @count:	the number of bytes to read.
 *
 * Return:
 *	In case of success the number of bytes received.
 *	On failure, -errno.
 */
static int ftpm_tee_tpm_op_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
	size_t len;

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

	memcpy(buf, pvt_data->resp_buf, len);
	pvt_data->resp_len = 0;

	return len;
}

/**
 * ftpm_tee_tpm_op_send() - send TPM commands through the TEE shared memory.
 * @chip:	the tpm_chip description as specified in driver/char/tpm/tpm.h
 * @buf:	the buffer to send.
 * @len:	the number of bytes to send.
 *
 * Return:
 *	In case of success, returns 0.
 *	On failure, -errno
 */
static int ftpm_tee_tpm_op_send(struct tpm_chip *chip, u8 *buf, size_t len)
{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(chip->dev.parent);
	size_t resp_len;
	int rc;
	u8 *temp_buf;
	struct tpm_header *resp_header;
	struct tee_ioctl_invoke_arg transceive_args;
	struct tee_param command_params[4];
	struct tee_shm *shm = pvt_data->shm;

	if (len > MAX_COMMAND_SIZE) {
		dev_err(&chip->dev,
			"%s: len=%zd exceeds MAX_COMMAND_SIZE supported by fTPM TA\n",
			__func__, len);
		return -EIO;
	}

	memset(&transceive_args, 0, sizeof(transceive_args));
	memset(command_params, 0, sizeof(command_params));
	pvt_data->resp_len = 0;

	/* Invoke FTPM_OPTEE_TA_SUBMIT_COMMAND function of fTPM TA */
	transceive_args = (struct tee_ioctl_invoke_arg) {
		.func = FTPM_OPTEE_TA_SUBMIT_COMMAND,
		.session = pvt_data->session,
		.num_params = 4,
	};

	/* Fill FTPM_OPTEE_TA_SUBMIT_COMMAND parameters */
	command_params[0] = (struct tee_param) {
		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INPUT,
		.u.memref = {
			.shm = shm,
			.size = len,
			.shm_offs = 0,
		},
	};

	temp_buf = tee_shm_get_va(shm, 0);
	if (IS_ERR(temp_buf)) {
		dev_err(&chip->dev, "%s: tee_shm_get_va failed for transmit\n",
			__func__);
		return PTR_ERR(temp_buf);
	}
	memset(temp_buf, 0, (MAX_COMMAND_SIZE + MAX_RESPONSE_SIZE));
	memcpy(temp_buf, buf, len);

	command_params[1] = (struct tee_param) {
		.attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT,
		.u.memref = {
			.shm = shm,
			.size = MAX_RESPONSE_SIZE,
			.shm_offs = MAX_COMMAND_SIZE,
		},
	};

	rc = tee_client_invoke_func(pvt_data->ctx, &transceive_args,
				    command_params);
	if ((rc < 0) || (transceive_args.ret != 0)) {
		dev_err(&chip->dev, "%s: SUBMIT_COMMAND invoke error: 0x%x\n",
			__func__, transceive_args.ret);
		return (rc < 0) ? rc : transceive_args.ret;
	}

	temp_buf = tee_shm_get_va(shm, command_params[1].u.memref.shm_offs);
	if (IS_ERR(temp_buf)) {
		dev_err(&chip->dev, "%s: tee_shm_get_va failed for receive\n",
			__func__);
		return PTR_ERR(temp_buf);
	}

	resp_header = (struct tpm_header *)temp_buf;
	resp_len = be32_to_cpu(resp_header->length);

	/* sanity check resp_len */
	if (resp_len < TPM_HEADER_SIZE) {
		dev_err(&chip->dev, "%s: tpm response header too small\n",
			__func__);
		return -EIO;
	}
	if (resp_len > MAX_RESPONSE_SIZE) {
		dev_err(&chip->dev,
			"%s: resp_len=%zd exceeds MAX_RESPONSE_SIZE\n",
			__func__, resp_len);
		return -EIO;
	}

	/* sanity checks look good, cache the response */
	memcpy(pvt_data->resp_buf, temp_buf, resp_len);
	pvt_data->resp_len = resp_len;

	return 0;
}

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

static u8 ftpm_tee_tpm_op_status(struct tpm_chip *chip)
{
	return 0;
}

static bool ftpm_tee_tpm_req_canceled(struct tpm_chip *chip, u8 status)
{
	return 0;
}

static const struct tpm_class_ops ftpm_tee_tpm_ops = {
	.flags = TPM_OPS_AUTO_STARTUP,
	.recv = ftpm_tee_tpm_op_recv,
	.send = ftpm_tee_tpm_op_send,
	.cancel = ftpm_tee_tpm_op_cancel,
	.status = ftpm_tee_tpm_op_status,
	.req_complete_mask = 0,
	.req_complete_val = 0,
	.req_canceled = ftpm_tee_tpm_req_canceled,
};

/*
 * Check whether this driver supports the fTPM TA in the TEE instance
 * represented by the params (ver/data) to this function.
 */
static int ftpm_tee_match(struct tee_ioctl_version_data *ver, const void *data)
{
	/*
	 * Currently this driver only support GP Complaint OPTEE based fTPM TA
	 */
	if ((ver->impl_id == TEE_IMPL_ID_OPTEE) &&
		(ver->gen_caps & TEE_GEN_CAP_GP))
		return 1;
	else
		return 0;
}

/**
 * ftpm_tee_probe() - initialize the fTPM
 * @pdev: the platform_device description.
 *
 * Return:
 *	On success, 0. On failure, -errno.
 */
static int ftpm_tee_probe(struct device *dev)
{
	int rc;
	struct tpm_chip *chip;
	struct ftpm_tee_private *pvt_data = NULL;
	struct tee_ioctl_open_session_arg sess_arg;

	pvt_data = devm_kzalloc(dev, sizeof(struct ftpm_tee_private),
				GFP_KERNEL);
	if (!pvt_data)
		return -ENOMEM;

	dev_set_drvdata(dev, pvt_data);

	/* Open context with TEE driver */
	pvt_data->ctx = tee_client_open_context(NULL, ftpm_tee_match, NULL,
						NULL);
	if (IS_ERR(pvt_data->ctx)) {
		if (PTR_ERR(pvt_data->ctx) == -ENOENT)
			return -EPROBE_DEFER;
		dev_err(dev, "%s: tee_client_open_context failed\n", __func__);
		return PTR_ERR(pvt_data->ctx);
	}

	/* Open a session with fTPM TA */
	memset(&sess_arg, 0, sizeof(sess_arg));
	export_uuid(sess_arg.uuid, &ftpm_ta_uuid);
	sess_arg.clnt_login = TEE_IOCTL_LOGIN_PUBLIC;
	sess_arg.num_params = 0;

	rc = tee_client_open_session(pvt_data->ctx, &sess_arg, NULL);
	if ((rc < 0) || (sess_arg.ret != 0)) {
		dev_err(dev, "%s: tee_client_open_session failed, err=%x\n",
			__func__, sess_arg.ret);
		rc = -EINVAL;
		goto out_tee_session;
	}
	pvt_data->session = sess_arg.session;

	/* Allocate dynamic shared memory with fTPM TA */
	pvt_data->shm = tee_shm_alloc_kernel_buf(pvt_data->ctx,
						 MAX_COMMAND_SIZE +
						 MAX_RESPONSE_SIZE);
	if (IS_ERR(pvt_data->shm)) {
		dev_err(dev, "%s: tee_shm_alloc_kernel_buf failed\n", __func__);
		rc = -ENOMEM;
		goto out_shm_alloc;
	}

	/* Allocate new struct tpm_chip instance */
	chip = tpm_chip_alloc(dev, &ftpm_tee_tpm_ops);
	if (IS_ERR(chip)) {
		dev_err(dev, "%s: tpm_chip_alloc failed\n", __func__);
		rc = PTR_ERR(chip);
		goto out_chip_alloc;
	}

	pvt_data->chip = chip;
	pvt_data->chip->flags |= TPM_CHIP_FLAG_TPM2;

	/* Create a character device for the fTPM */
	rc = tpm_chip_register(pvt_data->chip);
	if (rc) {
		dev_err(dev, "%s: tpm_chip_register failed with rc=%d\n",
			__func__, rc);
		goto out_chip;
	}

	return 0;

out_chip:
	put_device(&pvt_data->chip->dev);
out_chip_alloc:
	tee_shm_free(pvt_data->shm);
out_shm_alloc:
	tee_client_close_session(pvt_data->ctx, pvt_data->session);
out_tee_session:
	tee_client_close_context(pvt_data->ctx);

	return rc;
}

static int ftpm_plat_tee_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;

	return ftpm_tee_probe(dev);
}

/**
 * ftpm_tee_remove() - remove the TPM device
 * @pdev: the platform_device description.
 *
 * Return:
 *	0 always.
 */
static int ftpm_tee_remove(struct device *dev)
{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(dev);

	/* Release the chip */
	tpm_chip_unregister(pvt_data->chip);

	/* frees chip */
	put_device(&pvt_data->chip->dev);

	/* Free the shared memory pool */
	tee_shm_free(pvt_data->shm);

	/* close the existing session with fTPM TA*/
	tee_client_close_session(pvt_data->ctx, pvt_data->session);

	/* close the context with TEE driver */
	tee_client_close_context(pvt_data->ctx);

	/* memory allocated with devm_kzalloc() is freed automatically */

	return 0;
}

static int ftpm_plat_tee_remove(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;

	return ftpm_tee_remove(dev);
}

/**
 * ftpm_tee_shutdown() - shutdown the TPM device
 * @pdev: the platform_device description.
 */
static void ftpm_plat_tee_shutdown(struct platform_device *pdev)
{
	struct ftpm_tee_private *pvt_data = dev_get_drvdata(&pdev->dev);

	tee_shm_free(pvt_data->shm);
	tee_client_close_session(pvt_data->ctx, pvt_data->session);
	tee_client_close_context(pvt_data->ctx);
}

static const struct of_device_id of_ftpm_tee_ids[] = {
	{ .compatible = "microsoft,ftpm" },
	{ }
};
MODULE_DEVICE_TABLE(of, of_ftpm_tee_ids);

static struct platform_driver ftpm_tee_plat_driver = {
	.driver = {
		.name = "ftpm-tee",
		.of_match_table = of_match_ptr(of_ftpm_tee_ids),
	},
	.shutdown = ftpm_plat_tee_shutdown,
	.probe = ftpm_plat_tee_probe,
	.remove = ftpm_plat_tee_remove,
};

/* UUID of the fTPM TA */
static const struct tee_client_device_id optee_ftpm_id_table[] = {
	{UUID_INIT(0xbc50d971, 0xd4c9, 0x42c4,
		   0x82, 0xcb, 0x34, 0x3f, 0xb7, 0xf3, 0x78, 0x96)},
	{}
};

MODULE_DEVICE_TABLE(tee, optee_ftpm_id_table);

static struct tee_client_driver ftpm_tee_driver = {
	.id_table	= optee_ftpm_id_table,
	.driver		= {
		.name		= "optee-ftpm",
		.bus		= &tee_bus_type,
		.probe		= ftpm_tee_probe,
		.remove		= ftpm_tee_remove,
	},
};

static int __init ftpm_mod_init(void)
{
	int rc;

	rc = platform_driver_register(&ftpm_tee_plat_driver);
	if (rc)
		return rc;

	return driver_register(&ftpm_tee_driver.driver);
}

static void __exit ftpm_mod_exit(void)
{
	platform_driver_unregister(&ftpm_tee_plat_driver);
	driver_unregister(&ftpm_tee_driver.driver);
}

module_init(ftpm_mod_init);
module_exit(ftpm_mod_exit);

MODULE_AUTHOR("Thirupathaiah Annapureddy <thiruan@microsoft.com>");
MODULE_DESCRIPTION("TPM Driver for fTPM TA in TEE");
MODULE_LICENSE("GPL v2");