[PATCH v2 0/2] s390/uv: Provide host-key hashes in sysfs

[PATCH v2 0/2] s390/uv: Provide host-key hashes in sysfs

[Steffen Eiden]

List the installed host-keys in the sysfs if the machine supports the
Query Ultravisor Keys UVC.

As of now, two types of host-keys are available:
The used/primary host key, and the backup host-key both hastes are
available in a sysfs file.
For forwards compatibility an `all` file is also available that displays
the whole payload (15*32 bytes) and therefore future key hashes.

Since v1:
	* added r-b's from Janoch & Christoph
	* fixed minor issues (Janosch)
	* removed an unnecessary UVC availability-check in uv_query_keys
		-> removed Christoph's r-b from patch 2

Steffen Eiden (2):
  s390/uv: Refactor uv-sysfs creation
  s390/uv: Provide host-key hashes in sysfs

 arch/s390/include/asm/uv.h |  16 ++++++
 arch/s390/kernel/uv.c      | 105 +++++++++++++++++++++++++++++++++----
 2 files changed, 111 insertions(+), 10 deletions(-)

-- 
2.43.0

[PATCH v2 1/2] s390/uv: Refactor uv-sysfs creation

[Steffen Eiden]

Streamline the sysfs generation to make it more extensible.
Add a function to create a sysfs entry in the uv-sysfs dir.
Use this function for the query directory.

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/kernel/uv.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 9646f773208a..901e852f858b 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -753,7 +753,26 @@ static const struct attribute *uv_prot_virt_attrs[] = {
 static struct kset *uv_query_kset;
 static struct kobject *uv_kobj;
 
-static int __init uv_info_init(void)
+static int __init uv_sysfs_dir_init(const struct attribute_group *grp,
+				    struct kset **uv_dir_kset, const char *name)
+{
+	struct kset *kset;
+	int rc = -ENOMEM;
+
+	kset = kset_create_and_add(name, NULL, uv_kobj);
+	if (!kset)
+		return -ENOMEM;
+	*uv_dir_kset = kset;
+
+	rc = sysfs_create_group(&kset->kobj, grp);
+	if (!rc)
+		return 0;
+
+	kset_unregister(kset);
+	return rc;
+}
+
+static int __init uv_sysfs_init(void)
 {
 	int rc = -ENOMEM;
 
@@ -768,17 +787,12 @@ static int __init uv_info_init(void)
 	if (rc)
 		goto out_kobj;
 
-	uv_query_kset = kset_create_and_add("query", NULL, uv_kobj);
-	if (!uv_query_kset) {
-		rc = -ENOMEM;
+	rc = uv_sysfs_dir_init(&uv_query_attr_group, &uv_query_kset, "query");
+	if (rc)
 		goto out_ind_files;
-	}
 
-	rc = sysfs_create_group(&uv_query_kset->kobj, &uv_query_attr_group);
-	if (!rc)
-		return 0;
+	return 0;
 
-	kset_unregister(uv_query_kset);
 out_ind_files:
 	sysfs_remove_files(uv_kobj, uv_prot_virt_attrs);
 out_kobj:
@@ -786,4 +800,4 @@ static int __init uv_info_init(void)
 	kobject_put(uv_kobj);
 	return rc;
 }
-device_initcall(uv_info_init);
+device_initcall(uv_sysfs_init);
-- 
2.43.0

[PATCH v2 2/2] s390/uv: Provide host-key hashes in sysfs

[Steffen Eiden]

Utilize the new Query Ultravisor Keys UVC to give user space the
information which host-keys are installed on the system.

Create a new sysfs directory 'firmware/uv/keys' that contains the hash
of the host-key and the backup host-key of that system. Additionally,
the file 'all' contains the response from the UVC possibly containing
more key-hashes than currently known.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 16 +++++++++
 arch/s390/kernel/uv.c      | 71 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 153d93468b77..c69ac06a31f9 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -31,6 +31,7 @@
 #define UVC_RC_NEED_DESTROY	0x8000
 
 #define UVC_CMD_QUI			0x0001
+#define UVC_CMD_QUERY_KEYS		0x0002
 #define UVC_CMD_INIT_UV			0x000f
 #define UVC_CMD_CREATE_SEC_CONF		0x0100
 #define UVC_CMD_DESTROY_SEC_CONF	0x0101
@@ -94,6 +95,7 @@ enum uv_cmds_inst {
 	BIT_UVC_CMD_ADD_SECRET = 29,
 	BIT_UVC_CMD_LIST_SECRETS = 30,
 	BIT_UVC_CMD_LOCK_SECRETS = 31,
+	BIT_UVC_CMD_QUERY_KEYS = 34,
 };
 
 enum uv_feat_ind {
@@ -145,6 +147,20 @@ struct uv_cb_qui {
 	u8 reserved112[0x120 - 0x112];		/* 0x0112 */
 } __packed __aligned(8);
 
+struct uv_key_hash {
+	u64 dword[4];
+} __packed __aligned(8);
+
+#define UVC_QUERY_KEYS_IDX_HK		0
+#define UVC_QUERY_KEYS_IDX_BACK_HK		1
+
+/* Query Ultravisor Keys */
+struct uv_cb_query_keys {
+	struct uv_cb_header header;	/* 0x0000 */
+	u64 reserved08[3];		/* 0x0008 */
+	struct uv_key_hash keys[15];	/* 0x0020 */
+} __packed __aligned(8);
+
 /* Initialize Ultravisor */
 struct uv_cb_init {
 	struct uv_cb_header header;
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index 901e852f858b..6333e3346d88 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -722,10 +722,76 @@ static struct attribute *uv_query_attrs[] = {
 	NULL,
 };
 
+static inline struct uv_cb_query_keys uv_query_keys(void)
+{
+	struct uv_cb_query_keys uvcb = {
+		.header.cmd = UVC_CMD_QUERY_KEYS,
+		.header.len = sizeof(uvcb)
+	};
+
+	uv_call(0, (uint64_t)&uvcb);
+	return uvcb;
+}
+
+static inline ssize_t emit_hash(struct uv_key_hash *hash, char *buf, int at)
+{
+	return sysfs_emit_at(buf, at, "%016llx%016llx%016llx%016llx\n",
+			    hash->dword[0], hash->dword[1], hash->dword[2], hash->dword[3]);
+}
+
+static ssize_t uv_keys_host_key(struct kobject *kobj,
+				struct kobj_attribute *attr, char *buf)
+{
+	struct uv_cb_query_keys uvcb = uv_query_keys();
+
+	return emit_hash(&uvcb.keys[UVC_QUERY_KEYS_IDX_HK], buf, 0);
+}
+
+static struct kobj_attribute uv_keys_host_key_attr =
+	__ATTR(host_key, 0444, uv_keys_host_key, NULL);
+
+static ssize_t uv_keys_backup_host_key(struct kobject *kobj,
+				       struct kobj_attribute *attr, char *buf)
+{
+	struct uv_cb_query_keys uvcb = uv_query_keys();
+
+	return emit_hash(&uvcb.keys[UVC_QUERY_KEYS_IDX_BACK_HK], buf, 0);
+}
+
+static struct kobj_attribute uv_keys_backup_host_key_attr =
+	__ATTR(backup_host_key, 0444, uv_keys_backup_host_key, NULL);
+
+static ssize_t uv_keys_all(struct kobject *kobj,
+			   struct kobj_attribute *attr, char *buf)
+{
+	struct uv_cb_query_keys uvcb = uv_query_keys();
+	ssize_t len = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(uvcb.keys); i++)
+		len += emit_hash(uvcb.keys + i, buf, len);
+
+	return len;
+}
+
+static struct kobj_attribute uv_keys_all_attr =
+	__ATTR(all, 0444, uv_keys_all, NULL);
+
 static struct attribute_group uv_query_attr_group = {
 	.attrs = uv_query_attrs,
 };
 
+static struct attribute *uv_keys_attrs[] = {
+	&uv_keys_host_key_attr.attr,
+	&uv_keys_backup_host_key_attr.attr,
+	&uv_keys_all_attr.attr,
+	NULL,
+};
+
+static struct attribute_group uv_keys_attr_group = {
+	.attrs = uv_keys_attrs,
+};
+
 static ssize_t uv_is_prot_virt_guest(struct kobject *kobj,
 				     struct kobj_attribute *attr, char *buf)
 {
@@ -751,6 +817,7 @@ static const struct attribute *uv_prot_virt_attrs[] = {
 };
 
 static struct kset *uv_query_kset;
+static struct kset *uv_keys_kset;
 static struct kobject *uv_kobj;
 
 static int __init uv_sysfs_dir_init(const struct attribute_group *grp,
@@ -791,6 +858,10 @@ static int __init uv_sysfs_init(void)
 	if (rc)
 		goto out_ind_files;
 
+	/* Get installed key hashes if available, ignore any errors */
+	if (test_bit_inv(BIT_UVC_CMD_QUERY_KEYS, uv_info.inst_calls_list))
+		uv_sysfs_dir_init(&uv_keys_attr_group, &uv_keys_kset, "keys");
+
 	return 0;
 
 out_ind_files:
-- 
2.43.0

Re: [PATCH v2 2/2] s390/uv: Provide host-key hashes in sysfs

[Janosch Frank]

On 10/2/24 6:04 PM, Steffen Eiden wrote:
> Utilize the new Query Ultravisor Keys UVC to give user space the
> information which host-keys are installed on the system.
> 
> Create a new sysfs directory 'firmware/uv/keys' that contains the hash
> of the host-key and the backup host-key of that system. Additionally,
> the file 'all' contains the response from the UVC possibly containing
> more key-hashes than currently known.
> 
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>

Two nits below.

> ---
>   arch/s390/include/asm/uv.h | 16 +++++++++
>   arch/s390/kernel/uv.c      | 71 ++++++++++++++++++++++++++++++++++++++
>   2 files changed, 87 insertions(+)
> 

[...]

> +struct uv_key_hash {
> +	u64 dword[4];
> +} __packed __aligned(8);
> +
> +#define UVC_QUERY_KEYS_IDX_HK		0
> +#define UVC_QUERY_KEYS_IDX_BACK_HK		1
> +
> +/* Query Ultravisor Keys */
> +struct uv_cb_query_keys {
> +	struct uv_cb_header header;	/* 0x0000 */
> +	u64 reserved08[3];		/* 0x0008 */
> +	struct uv_key_hash keys[15];	/* 0x0020 */

s/keys/key_hash/ or something similar?

> +} __packed __aligned(8);
>

We could add a static size assert here.

Re: [PATCH v2 1/2] s390/uv: Refactor uv-sysfs creation

[Heiko Carstens]

On Wed, Oct 02, 2024 at 06:04:17PM +0200, Steffen Eiden wrote:
> Streamline the sysfs generation to make it more extensible.
> Add a function to create a sysfs entry in the uv-sysfs dir.
> Use this function for the query directory.
> 
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> Reviewed-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
> Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
> ---
>  arch/s390/kernel/uv.c | 34 ++++++++++++++++++++++++----------
>  1 file changed, 24 insertions(+), 10 deletions(-)
...
> -static int __init uv_info_init(void)
> +static int __init uv_sysfs_dir_init(const struct attribute_group *grp,
> +				    struct kset **uv_dir_kset, const char *name)
> +{
> +	struct kset *kset;
> +	int rc = -ENOMEM;

rc is unnecessarily preinitialized, so you can wait for a cleanup
patch from some bot.

> +	kset = kset_create_and_add(name, NULL, uv_kobj);
> +	if (!kset)
> +		return -ENOMEM;
> +	*uv_dir_kset = kset;
> +
> +	rc = sysfs_create_group(&kset->kobj, grp);
> +	if (!rc)
> +		return 0;
> +
> +	kset_unregister(kset);
> +	return rc;

doing it like

	rc = sysfs_create_group(&kset->kobj, grp);
	if (rc)
		kset_unregister(kset);
	return rc;

is shorter ;)