tsm_mr_sample.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/* Copyright(c) 2024-2005 Intel Corporation. All rights reserved. */
  3
  4#define pr_fmt(x) KBUILD_MODNAME ": " x
  5
  6#include <linux/module.h>
  7#include <linux/tsm-mr.h>
  8#include <linux/miscdevice.h>
  9#include <crypto/hash.h>
 10
 11static struct {
 12	u8 static_mr[SHA384_DIGEST_SIZE];
 13	u8 config_mr[SHA512_DIGEST_SIZE];
 14	u8 rtmr0[SHA256_DIGEST_SIZE];
 15	u8 rtmr1[SHA384_DIGEST_SIZE];
 16	u8 report_digest[SHA512_DIGEST_SIZE];
 17} sample_report = {
 18	.static_mr = "static_mr",
 19	.config_mr = "config_mr",
 20	.rtmr0 = "rtmr0",
 21	.rtmr1 = "rtmr1",
 22};
 23
 24static int sample_report_refresh(const struct tsm_measurements *tm)
 25{
 26	struct crypto_shash *tfm;
 27	int rc;
 28
 29	tfm = crypto_alloc_shash(hash_algo_name[HASH_ALGO_SHA512], 0, 0);
 30	if (IS_ERR(tfm)) {
 31		pr_err("crypto_alloc_shash failed: %ld\n", PTR_ERR(tfm));
 32		return PTR_ERR(tfm);
 33	}
 34
 35	rc = crypto_shash_tfm_digest(tfm, (u8 *)&sample_report,
 36				     offsetof(typeof(sample_report),
 37					      report_digest),
 38				     sample_report.report_digest);
 39	crypto_free_shash(tfm);
 40	if (rc)
 41		pr_err("crypto_shash_tfm_digest failed: %d\n", rc);
 42	return rc;
 43}
 44
 45static int sample_report_extend_mr(const struct tsm_measurements *tm,
 46				   const struct tsm_measurement_register *mr,
 47				   const u8 *data)
 48{
 49	SHASH_DESC_ON_STACK(desc, 0);
 50	int rc;
 51
 52	desc->tfm = crypto_alloc_shash(hash_algo_name[mr->mr_hash], 0, 0);
 53	if (IS_ERR(desc->tfm)) {
 54		pr_err("crypto_alloc_shash failed: %ld\n", PTR_ERR(desc->tfm));
 55		return PTR_ERR(desc->tfm);
 56	}
 57
 58	rc = crypto_shash_init(desc);
 59	if (!rc)
 60		rc = crypto_shash_update(desc, mr->mr_value, mr->mr_size);
 61	if (!rc)
 62		rc = crypto_shash_finup(desc, data, mr->mr_size, mr->mr_value);
 63	crypto_free_shash(desc->tfm);
 64	if (rc)
 65		pr_err("SHA calculation failed: %d\n", rc);
 66	return rc;
 67}
 68
 69#define MR_(mr, hash) .mr_value = &sample_report.mr, TSM_MR_(mr, hash)
 70static const struct tsm_measurement_register sample_mrs[] = {
 71	/* static MR, read-only */
 72	{ MR_(static_mr, SHA384) },
 73	/* config MR, read-only */
 74	{ MR_(config_mr, SHA512) | TSM_MR_F_NOHASH },
 75	/* RTMR, direct extension prohibited */
 76	{ MR_(rtmr0, SHA256) | TSM_MR_F_LIVE },
 77	/* RTMR, direct extension allowed */
 78	{ MR_(rtmr1, SHA384) | TSM_MR_F_RTMR },
 79	/* RTMR, crypto agile, alaised to rtmr0 and rtmr1, respectively */
 80	{ .mr_value = &sample_report.rtmr0,
 81	  TSM_MR_(rtmr_crypto_agile, SHA256) | TSM_MR_F_RTMR },
 82	{ .mr_value = &sample_report.rtmr1,
 83	  TSM_MR_(rtmr_crypto_agile, SHA384) | TSM_MR_F_RTMR },
 84	/* sha512 digest of the whole structure */
 85	{ MR_(report_digest, SHA512) | TSM_MR_F_LIVE },
 86};
 87#undef MR_
 88
 89static struct tsm_measurements sample_tm = {
 90	.mrs = sample_mrs,
 91	.nr_mrs = ARRAY_SIZE(sample_mrs),
 92	.refresh = sample_report_refresh,
 93	.write = sample_report_extend_mr,
 94};
 95
 96static const struct attribute_group *sample_groups[] = {
 97	NULL,
 98	NULL,
 99};
100
101static struct miscdevice sample_misc_dev = {
102	.name = KBUILD_MODNAME,
103	.minor = MISC_DYNAMIC_MINOR,
104	.groups = sample_groups,
105};
106
107static int __init tsm_mr_sample_init(void)
108{
109	int rc;
110
111	sample_groups[0] = tsm_mr_create_attribute_group(&sample_tm);
112	if (IS_ERR(sample_groups[0]))
113		return PTR_ERR(sample_groups[0]);
114
115	rc = misc_register(&sample_misc_dev);
116	if (rc)
117		tsm_mr_free_attribute_group(sample_groups[0]);
118	return rc;
119}
120
121static void __exit tsm_mr_sample_exit(void)
122{
123	misc_deregister(&sample_misc_dev);
124	tsm_mr_free_attribute_group(sample_groups[0]);
125}
126
127module_init(tsm_mr_sample_init);
128module_exit(tsm_mr_sample_exit);
129
130MODULE_LICENSE("GPL");
131MODULE_DESCRIPTION("Sample module using tsm-mr to expose emulated MRs");