Resguardo inicial

linux-7.2.3/drivers/virt/coco/guest/Kconfig

@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Confidential computing shared guest collateral
+#
+config TSM_GUEST
+	bool
+
+config TSM_REPORTS
+	select TSM_GUEST
+	select CONFIGFS_FS
+	tristate
+
+config TSM_MEASUREMENTS
+	select TSM_GUEST
+	select CRYPTO_HASH_INFO
+	bool

linux-7.2.3/drivers/virt/coco/guest/Makefile

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_TSM_REPORTS)	+= tsm_report.o
+tsm_report-y := report.o
+obj-$(CONFIG_TSM_MEASUREMENTS)	+= tsm-mr.o

linux-7.2.3/drivers/virt/coco/guest/report.c

@@ -0,0 +1,539 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2023 Intel Corporation. All rights reserved. */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/tsm.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/rwsem.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/cleanup.h>
+#include <linux/configfs.h>
+
+static struct tsm_provider {
+	const struct tsm_report_ops *ops;
+	void *data;
+	atomic_t count;
+} provider;
+static DECLARE_RWSEM(tsm_rwsem);
+
+/**
+ * DOC: Trusted Security Module (TSM) Attestation Report Interface
+ *
+ * The TSM report interface is a common provider of blobs that facilitate
+ * attestation of a TVM (confidential computing guest) by an attestation
+ * service. A TSM report combines a user-defined blob (likely a public-key with
+ * a nonce for a key-exchange protocol) with a signed attestation report. That
+ * combined blob is then used to obtain secrets provided by an agent that can
+ * validate the attestation report. The expectation is that this interface is
+ * invoked infrequently, however configfs allows for multiple agents to
+ * own their own report generation instances to generate reports as
+ * often as needed.
+ *
+ * The attestation report format is TSM provider specific, when / if a standard
+ * materializes that can be published instead of the vendor layout. Until then
+ * the 'provider' attribute indicates the format of 'outblob', and optionally
+ * 'auxblob' and 'manifestblob'.
+ */
+
+struct tsm_report_state {
+	struct tsm_report report;
+	unsigned long write_generation;
+	unsigned long read_generation;
+	struct config_item cfg;
+};
+
+enum tsm_data_select {
+	TSM_REPORT,
+	TSM_CERTS,
+	TSM_MANIFEST,
+};
+
+static struct tsm_report *to_tsm_report(struct config_item *cfg)
+{
+	struct tsm_report_state *state =
+		container_of(cfg, struct tsm_report_state, cfg);
+
+	return &state->report;
+}
+
+static struct tsm_report_state *to_state(struct tsm_report *report)
+{
+	return container_of(report, struct tsm_report_state, report);
+}
+
+static int try_advance_write_generation(struct tsm_report *report)
+{
+	struct tsm_report_state *state = to_state(report);
+
+	lockdep_assert_held_write(&tsm_rwsem);
+
+	/*
+	 * Malicious or broken userspace has written enough times for
+	 * read_generation == write_generation by modular arithmetic without an
+	 * interim read. Stop accepting updates until the current report
+	 * configuration is read.
+	 */
+	if (state->write_generation == state->read_generation - 1)
+		return -EBUSY;
+	state->write_generation++;
+	return 0;
+}
+
+static ssize_t tsm_report_privlevel_store(struct config_item *cfg,
+					  const char *buf, size_t len)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	unsigned int val;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	if (!provider.ops)
+		return -ENXIO;
+
+	/*
+	 * The valid privilege levels that a TSM might accept, if it accepts a
+	 * privilege level setting at all, are a max of TSM_PRIVLEVEL_MAX (see
+	 * SEV-SNP GHCB) and a minimum of a TSM selected floor value no less
+	 * than 0.
+	 */
+	if (provider.ops->privlevel_floor > val || val > TSM_REPORT_PRIVLEVEL_MAX)
+		return -EINVAL;
+
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+	report->desc.privlevel = val;
+
+	return len;
+}
+CONFIGFS_ATTR_WO(tsm_report_, privlevel);
+
+static ssize_t tsm_report_privlevel_floor_show(struct config_item *cfg,
+					       char *buf)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+
+	if (!provider.ops)
+		return -ENXIO;
+
+	return sysfs_emit(buf, "%u\n", provider.ops->privlevel_floor);
+}
+CONFIGFS_ATTR_RO(tsm_report_, privlevel_floor);
+
+static ssize_t tsm_report_service_provider_store(struct config_item *cfg,
+						 const char *buf, size_t len)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	size_t sp_len;
+	char *sp;
+	int rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+
+	sp_len = (buf[len - 1] != '\n') ? len : len - 1;
+
+	sp = kstrndup(buf, sp_len, GFP_KERNEL);
+	if (!sp)
+		return -ENOMEM;
+	kfree(report->desc.service_provider);
+
+	report->desc.service_provider = sp;
+
+	return len;
+}
+CONFIGFS_ATTR_WO(tsm_report_, service_provider);
+
+static ssize_t tsm_report_service_guid_store(struct config_item *cfg,
+					     const char *buf, size_t len)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	int rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+
+	report->desc.service_guid = guid_null;
+
+	rc = guid_parse(buf, &report->desc.service_guid);
+	if (rc)
+		return rc;
+
+	return len;
+}
+CONFIGFS_ATTR_WO(tsm_report_, service_guid);
+
+static ssize_t tsm_report_service_manifest_version_store(struct config_item *cfg,
+							 const char *buf, size_t len)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	unsigned int val;
+	int rc;
+
+	rc = kstrtouint(buf, 0, &val);
+	if (rc)
+		return rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+	report->desc.service_manifest_version = val;
+
+	return len;
+}
+CONFIGFS_ATTR_WO(tsm_report_, service_manifest_version);
+
+static ssize_t tsm_report_inblob_write(struct config_item *cfg,
+				       const void *buf, size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	int rc;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	rc = try_advance_write_generation(report);
+	if (rc)
+		return rc;
+
+	report->desc.inblob_len = count;
+	memcpy(report->desc.inblob, buf, count);
+	return count;
+}
+CONFIGFS_BIN_ATTR_WO(tsm_report_, inblob, NULL, TSM_REPORT_INBLOB_MAX);
+
+static ssize_t tsm_report_generation_show(struct config_item *cfg, char *buf)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	struct tsm_report_state *state = to_state(report);
+
+	guard(rwsem_read)(&tsm_rwsem);
+	return sysfs_emit(buf, "%lu\n", state->write_generation);
+}
+CONFIGFS_ATTR_RO(tsm_report_, generation);
+
+static ssize_t tsm_report_provider_show(struct config_item *cfg, char *buf)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!provider.ops)
+		return -ENXIO;
+
+	return sysfs_emit(buf, "%s\n", provider.ops->name);
+}
+CONFIGFS_ATTR_RO(tsm_report_, provider);
+
+static ssize_t __read_report(struct tsm_report *report, void *buf, size_t count,
+			     enum tsm_data_select select)
+{
+	loff_t offset = 0;
+	ssize_t len;
+	u8 *out;
+
+	if (select == TSM_REPORT) {
+		out = report->outblob;
+		len = report->outblob_len;
+	} else if (select == TSM_MANIFEST) {
+		out = report->manifestblob;
+		len = report->manifestblob_len;
+	} else {
+		out = report->auxblob;
+		len = report->auxblob_len;
+	}
+
+	/*
+	 * Recall that a NULL @buf is configfs requesting the size of
+	 * the buffer.
+	 */
+	if (!buf)
+		return len;
+	return memory_read_from_buffer(buf, count, &offset, out, len);
+}
+
+static ssize_t read_cached_report(struct tsm_report *report, void *buf,
+				  size_t count, enum tsm_data_select select)
+{
+	struct tsm_report_state *state = to_state(report);
+
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!report->desc.inblob_len)
+		return -EINVAL;
+
+	/*
+	 * A given TSM backend always fills in ->outblob regardless of
+	 * whether the report includes an auxblob/manifestblob or not.
+	 */
+	if (!report->outblob ||
+	    state->read_generation != state->write_generation)
+		return -EWOULDBLOCK;
+
+	return __read_report(report, buf, count, select);
+}
+
+static ssize_t tsm_report_read(struct tsm_report *report, void *buf,
+			       size_t count, enum tsm_data_select select)
+{
+	struct tsm_report_state *state = to_state(report);
+	const struct tsm_report_ops *ops;
+	ssize_t rc;
+
+	/* try to read from the existing report if present and valid... */
+	rc = read_cached_report(report, buf, count, select);
+	if (rc >= 0 || rc != -EWOULDBLOCK)
+		return rc;
+
+	/* slow path, report may need to be regenerated... */
+	guard(rwsem_write)(&tsm_rwsem);
+	ops = provider.ops;
+	if (!ops)
+		return -ENXIO;
+	if (!report->desc.inblob_len)
+		return -EINVAL;
+
+	/* did another thread already generate this report? */
+	if (report->outblob &&
+	    state->read_generation == state->write_generation)
+		goto out;
+
+	kvfree(report->outblob);
+	kvfree(report->auxblob);
+	kvfree(report->manifestblob);
+	report->outblob = NULL;
+	report->auxblob = NULL;
+	report->manifestblob = NULL;
+	rc = ops->report_new(report, provider.data);
+	if (rc < 0)
+		return rc;
+	state->read_generation = state->write_generation;
+out:
+	return __read_report(report, buf, count, select);
+}
+
+static ssize_t tsm_report_outblob_read(struct config_item *cfg, void *buf,
+				       size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+
+	return tsm_report_read(report, buf, count, TSM_REPORT);
+}
+CONFIGFS_BIN_ATTR_RO(tsm_report_, outblob, NULL, TSM_REPORT_OUTBLOB_MAX);
+
+static ssize_t tsm_report_auxblob_read(struct config_item *cfg, void *buf,
+				       size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+
+	return tsm_report_read(report, buf, count, TSM_CERTS);
+}
+CONFIGFS_BIN_ATTR_RO(tsm_report_, auxblob, NULL, TSM_REPORT_OUTBLOB_MAX);
+
+static ssize_t tsm_report_manifestblob_read(struct config_item *cfg, void *buf,
+					    size_t count)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+
+	return tsm_report_read(report, buf, count, TSM_MANIFEST);
+}
+CONFIGFS_BIN_ATTR_RO(tsm_report_, manifestblob, NULL, TSM_REPORT_OUTBLOB_MAX);
+
+static struct configfs_attribute *tsm_report_attrs[] = {
+	[TSM_REPORT_GENERATION] = &tsm_report_attr_generation,
+	[TSM_REPORT_PROVIDER] = &tsm_report_attr_provider,
+	[TSM_REPORT_PRIVLEVEL] = &tsm_report_attr_privlevel,
+	[TSM_REPORT_PRIVLEVEL_FLOOR] = &tsm_report_attr_privlevel_floor,
+	[TSM_REPORT_SERVICE_PROVIDER] = &tsm_report_attr_service_provider,
+	[TSM_REPORT_SERVICE_GUID] = &tsm_report_attr_service_guid,
+	[TSM_REPORT_SERVICE_MANIFEST_VER] = &tsm_report_attr_service_manifest_version,
+	NULL,
+};
+
+static struct configfs_bin_attribute *tsm_report_bin_attrs[] = {
+	[TSM_REPORT_INBLOB] = &tsm_report_attr_inblob,
+	[TSM_REPORT_OUTBLOB] = &tsm_report_attr_outblob,
+	[TSM_REPORT_AUXBLOB] = &tsm_report_attr_auxblob,
+	[TSM_REPORT_MANIFESTBLOB] = &tsm_report_attr_manifestblob,
+	NULL,
+};
+
+static void tsm_report_item_release(struct config_item *cfg)
+{
+	struct tsm_report *report = to_tsm_report(cfg);
+	struct tsm_report_state *state = to_state(report);
+
+	kvfree(report->manifestblob);
+	kvfree(report->auxblob);
+	kvfree(report->outblob);
+	kfree(report->desc.service_provider);
+	kfree(state);
+}
+
+static struct configfs_item_operations tsm_report_item_ops = {
+	.release = tsm_report_item_release,
+};
+
+static bool tsm_report_is_visible(struct config_item *item,
+				  struct configfs_attribute *attr, int n)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!provider.ops)
+		return false;
+
+	if (!provider.ops->report_attr_visible)
+		return true;
+
+	return provider.ops->report_attr_visible(n);
+}
+
+static bool tsm_report_is_bin_visible(struct config_item *item,
+				      struct configfs_bin_attribute *attr, int n)
+{
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!provider.ops)
+		return false;
+
+	if (!provider.ops->report_bin_attr_visible)
+		return true;
+
+	return provider.ops->report_bin_attr_visible(n);
+}
+
+static struct configfs_group_operations tsm_report_attr_group_ops = {
+	.is_visible = tsm_report_is_visible,
+	.is_bin_visible = tsm_report_is_bin_visible,
+};
+
+static const struct config_item_type tsm_report_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_bin_attrs = tsm_report_bin_attrs,
+	.ct_attrs = tsm_report_attrs,
+	.ct_item_ops = &tsm_report_item_ops,
+	.ct_group_ops = &tsm_report_attr_group_ops,
+};
+
+static struct config_item *tsm_report_make_item(struct config_group *group,
+						const char *name)
+{
+	struct tsm_report_state *state;
+
+	guard(rwsem_read)(&tsm_rwsem);
+	if (!provider.ops)
+		return ERR_PTR(-ENXIO);
+
+	state = kzalloc_obj(*state);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+
+	atomic_inc(&provider.count);
+	config_item_init_type_name(&state->cfg, name, &tsm_report_type);
+	return &state->cfg;
+}
+
+static void tsm_report_drop_item(struct config_group *group, struct config_item *item)
+{
+	config_item_put(item);
+	atomic_dec(&provider.count);
+}
+
+static struct configfs_group_operations tsm_report_group_ops = {
+	.make_item = tsm_report_make_item,
+	.drop_item = tsm_report_drop_item,
+};
+
+static const struct config_item_type tsm_reports_type = {
+	.ct_owner = THIS_MODULE,
+	.ct_group_ops = &tsm_report_group_ops,
+};
+
+static const struct config_item_type tsm_root_group_type = {
+	.ct_owner = THIS_MODULE,
+};
+
+static struct configfs_subsystem tsm_configfs = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "tsm",
+			.ci_type = &tsm_root_group_type,
+		},
+	},
+	.su_mutex = __MUTEX_INITIALIZER(tsm_configfs.su_mutex),
+};
+
+int tsm_report_register(const struct tsm_report_ops *ops, void *priv)
+{
+	const struct tsm_report_ops *conflict;
+
+	guard(rwsem_write)(&tsm_rwsem);
+	conflict = provider.ops;
+	if (conflict) {
+		pr_err("\"%s\" ops already registered\n", conflict->name);
+		return -EBUSY;
+	}
+
+	if (atomic_read(&provider.count)) {
+		pr_err("configfs/tsm/report not empty\n");
+		return -EBUSY;
+	}
+
+	provider.ops = ops;
+	provider.data = priv;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_report_register);
+
+int tsm_report_unregister(const struct tsm_report_ops *ops)
+{
+	guard(rwsem_write)(&tsm_rwsem);
+	if (ops != provider.ops)
+		return -EBUSY;
+	if (atomic_read(&provider.count))
+		pr_warn("\"%s\" unregistered with items present in configfs/tsm/report\n",
+			provider.ops->name);
+	provider.ops = NULL;
+	provider.data = NULL;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tsm_report_unregister);
+
+static struct config_group *tsm_report_group;
+
+static int __init tsm_report_init(void)
+{
+	struct config_group *root = &tsm_configfs.su_group;
+	struct config_group *tsm;
+	int rc;
+
+	config_group_init(root);
+	rc = configfs_register_subsystem(&tsm_configfs);
+	if (rc)
+		return rc;
+
+	tsm = configfs_register_default_group(root, "report",
+					      &tsm_reports_type);
+	if (IS_ERR(tsm)) {
+		configfs_unregister_subsystem(&tsm_configfs);
+		return PTR_ERR(tsm);
+	}
+	tsm_report_group = tsm;
+
+	return 0;
+}
+module_init(tsm_report_init);
+
+static void __exit tsm_report_exit(void)
+{
+	configfs_unregister_default_group(tsm_report_group);
+	configfs_unregister_subsystem(&tsm_configfs);
+}
+module_exit(tsm_report_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Provide Trusted Security Module attestation reports via configfs");

linux-7.2.3/drivers/virt/coco/guest/tsm-mr.c

@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2024-2025 Intel Corporation. All rights reserved. */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/tsm_mr.h>
+
+/*
+ * struct tm_context - contains everything necessary to implement sysfs
+ * attributes for MRs.
+ * @rwsem: protects the MR cache from concurrent access.
+ * @agrp: contains all MR attributes created by tsm_mr_create_attribute_group().
+ * @tm: input to tsm_mr_create_attribute_group() containing MR definitions/ops.
+ * @in_sync: %true if MR cache is up-to-date.
+ * @mrs: array of &struct bin_attribute, one for each MR.
+ *
+ * This internal structure contains everything needed to implement
+ * tm_digest_read() and tm_digest_write().
+ *
+ * Given tm->refresh() is potentially expensive, tm_digest_read() caches MR
+ * values and calls tm->refresh() only when necessary. Only live MRs (i.e., with
+ * %TSM_MR_F_LIVE set) can trigger tm->refresh(), while others are assumed to
+ * retain their values from the last tm->write(). @in_sync tracks if there have
+ * been tm->write() calls since the last tm->refresh(). That is, tm->refresh()
+ * will be called only when a live MR is being read and the cache is stale
+ * (@in_sync is %false).
+ *
+ * tm_digest_write() sets @in_sync to %false and calls tm->write(), whose
+ * semantics is arch and MR specific. Most (if not all) writable MRs support the
+ * extension semantics (i.e., tm->write() extends the input buffer into the MR).
+ */
+struct tm_context {
+	struct rw_semaphore rwsem;
+	struct attribute_group agrp;
+	const struct tsm_measurements *tm;
+	bool in_sync;
+	struct bin_attribute mrs[];
+};
+
+static ssize_t tm_digest_read(struct file *filp, struct kobject *kobj,
+			      const struct bin_attribute *attr, char *buffer,
+			      loff_t off, size_t count)
+{
+	struct tm_context *ctx;
+	const struct tsm_measurement_register *mr;
+	int rc;
+
+	ctx = attr->private;
+	rc = down_read_interruptible(&ctx->rwsem);
+	if (rc)
+		return rc;
+
+	mr = &ctx->tm->mrs[attr - ctx->mrs];
+
+	/*
+	 * @ctx->in_sync indicates if the MR cache is stale. It is a global
+	 * instead of a per-MR flag for simplicity, as most (if not all) archs
+	 * allow reading all MRs in oneshot.
+	 *
+	 * ctx->refresh() is necessary only for LIVE MRs, while others retain
+	 * their values from their respective last ctx->write().
+	 */
+	if ((mr->mr_flags & TSM_MR_F_LIVE) && !ctx->in_sync) {
+		up_read(&ctx->rwsem);
+
+		rc = down_write_killable(&ctx->rwsem);
+		if (rc)
+			return rc;
+
+		if (!ctx->in_sync) {
+			rc = ctx->tm->refresh(ctx->tm);
+			ctx->in_sync = !rc;
+			trace_tsm_mr_refresh(mr, rc);
+		}
+
+		downgrade_write(&ctx->rwsem);
+	}
+
+	memcpy(buffer, mr->mr_value + off, count);
+	trace_tsm_mr_read(mr);
+
+	up_read(&ctx->rwsem);
+	return rc ?: count;
+}
+
+static ssize_t tm_digest_write(struct file *filp, struct kobject *kobj,
+			       const struct bin_attribute *attr, char *buffer,
+			       loff_t off, size_t count)
+{
+	struct tm_context *ctx;
+	const struct tsm_measurement_register *mr;
+	ssize_t rc;
+
+	/* partial writes are not supported */
+	if (off != 0 || count != attr->size)
+		return -EINVAL;
+
+	ctx = attr->private;
+	mr = &ctx->tm->mrs[attr - ctx->mrs];
+
+	rc = down_write_killable(&ctx->rwsem);
+	if (rc)
+		return rc;
+
+	rc = ctx->tm->write(ctx->tm, mr, buffer);
+
+	/* mark MR cache stale */
+	if (!rc) {
+		ctx->in_sync = false;
+		trace_tsm_mr_write(mr, buffer);
+	}
+
+	up_write(&ctx->rwsem);
+	return rc ?: count;
+}
+
+/**
+ * tsm_mr_create_attribute_group() - creates an attribute group for measurement
+ * registers (MRs)
+ * @tm: pointer to &struct tsm_measurements containing the MR definitions.
+ *
+ * This function creates attributes corresponding to the MR definitions
+ * provided by @tm->mrs.
+ *
+ * The created attributes will reference @tm and its members. The caller must
+ * not free @tm until after tsm_mr_free_attribute_group() is called.
+ *
+ * Context: Process context. May sleep due to memory allocation.
+ *
+ * Return:
+ * * On success, the pointer to a an attribute group is returned; otherwise
+ * * %-EINVAL - Invalid MR definitions.
+ * * %-ENOMEM - Out of memory.
+ */
+const struct attribute_group *
+tsm_mr_create_attribute_group(const struct tsm_measurements *tm)
+{
+	size_t nlen;
+
+	if (!tm || !tm->mrs)
+		return ERR_PTR(-EINVAL);
+
+	/* aggregated length of all MR names */
+	nlen = 0;
+	for (size_t i = 0; i < tm->nr_mrs; ++i) {
+		if ((tm->mrs[i].mr_flags & TSM_MR_F_LIVE) && !tm->refresh)
+			return ERR_PTR(-EINVAL);
+
+		if ((tm->mrs[i].mr_flags & TSM_MR_F_WRITABLE) && !tm->write)
+			return ERR_PTR(-EINVAL);
+
+		if (!tm->mrs[i].mr_name)
+			return ERR_PTR(-EINVAL);
+
+		if (tm->mrs[i].mr_flags & TSM_MR_F_NOHASH)
+			continue;
+
+		if (tm->mrs[i].mr_hash >= HASH_ALGO__LAST)
+			return ERR_PTR(-EINVAL);
+
+		/* MR sysfs attribute names have the form of MRNAME:HASH */
+		nlen += strlen(tm->mrs[i].mr_name) + 1 +
+			strlen(hash_algo_name[tm->mrs[i].mr_hash]) + 1;
+	}
+
+	/*
+	 * @attrs and the MR name strings are combined into a single allocation
+	 * so that we don't have to free MR names one-by-one in
+	 * tsm_mr_free_attribute_group()
+	 */
+	const struct bin_attribute **attrs __free(kfree) =
+		kzalloc(sizeof(*attrs) * (tm->nr_mrs + 1) + nlen, GFP_KERNEL);
+	struct tm_context *ctx __free(kfree) =
+		kzalloc_flex(*ctx, mrs, tm->nr_mrs);
+	char *name, *end;
+
+	if (!ctx || !attrs)
+		return ERR_PTR(-ENOMEM);
+
+	/* @attrs is followed immediately by MR name strings */
+	name = (char *)&attrs[tm->nr_mrs + 1];
+	end = name + nlen;
+
+	for (size_t i = 0; i < tm->nr_mrs; ++i) {
+		struct bin_attribute *bap = &ctx->mrs[i];
+
+		sysfs_bin_attr_init(bap);
+
+		if (tm->mrs[i].mr_flags & TSM_MR_F_NOHASH)
+			bap->attr.name = tm->mrs[i].mr_name;
+		else if (name < end) {
+			bap->attr.name = name;
+			name += snprintf(name, end - name, "%s:%s",
+					 tm->mrs[i].mr_name,
+					 hash_algo_name[tm->mrs[i].mr_hash]);
+			++name;
+		} else
+			return ERR_PTR(-EINVAL);
+
+		/* check for duplicated MR definitions */
+		for (size_t j = 0; j < i; ++j)
+			if (!strcmp(bap->attr.name, attrs[j]->attr.name))
+				return ERR_PTR(-EINVAL);
+
+		if (tm->mrs[i].mr_flags & TSM_MR_F_READABLE) {
+			bap->attr.mode |= 0444;
+			bap->read = tm_digest_read;
+		}
+
+		if (tm->mrs[i].mr_flags & TSM_MR_F_WRITABLE) {
+			bap->attr.mode |= 0200;
+			bap->write = tm_digest_write;
+		}
+
+		bap->size = tm->mrs[i].mr_size;
+		bap->private = ctx;
+
+		attrs[i] = bap;
+	}
+
+	if (name != end)
+		return ERR_PTR(-EINVAL);
+
+	init_rwsem(&ctx->rwsem);
+	ctx->agrp.name = "measurements";
+	ctx->agrp.bin_attrs = no_free_ptr(attrs);
+	ctx->tm = tm;
+	return &no_free_ptr(ctx)->agrp;
+}
+EXPORT_SYMBOL_GPL(tsm_mr_create_attribute_group);
+
+/**
+ * tsm_mr_free_attribute_group() - frees the attribute group returned by
+ * tsm_mr_create_attribute_group()
+ * @attr_grp: attribute group returned by tsm_mr_create_attribute_group()
+ *
+ * Context: Process context.
+ */
+void tsm_mr_free_attribute_group(const struct attribute_group *attr_grp)
+{
+	if (!IS_ERR_OR_NULL(attr_grp)) {
+		kfree(attr_grp->bin_attrs);
+		kfree(container_of(attr_grp, struct tm_context, agrp));
+	}
+}
+EXPORT_SYMBOL_GPL(tsm_mr_free_attribute_group);