[PATCH 2/2] platform/x86: think-lmi: Certificate authentication support

[Mark Pearson <markpearson@lenovo.com>]

Implementation of certificate authentication feature for Lenovo
platforms. This allows for signed updates of BIOS settings.

Functionality supported:
 - Cert support available check. At initialisation check if BIOS
   supports certification authentication and if a certificate is
   installed. Enable the sysfs nodes appropriately
 - certificate and signature authentication attributes to enable
   a user to install, update and delete a certificate using signed
   signatures
 - certificate_thumbprint to confirm installed certificate details
 - support to go from certificate to password based authentication
 - set_signature and save_signature attributes needed for setting
   BIOS attributes using certificate authentication

Tested on X1 Carbon 10 with special trial BIOS. This feature is not
generally available yet but will be released later this year.

Note, I also cleaned up the formating of the GUIDs when I was adding
the new defines. Hope that's OK to combine in this commit.

Signed-off-by: Mark Pearson <markpearson@lenovo.com>
---
 drivers/platform/x86/think-lmi.c | 560 ++++++++++++++++++++++++++-----
 drivers/platform/x86/think-lmi.h |   7 +
 2 files changed, 475 insertions(+), 92 deletions(-)

diff --git a/drivers/platform/x86/think-lmi.c b/drivers/platform/x86/think-lmi.c
index 0b73e16cccea..54ce71f97c37 100644
--- a/drivers/platform/x86/think-lmi.c
+++ b/drivers/platform/x86/think-lmi.c
@@ -16,6 +16,7 @@
 #include <linux/fs.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <linux/dmi.h>
 #include <linux/wmi.h>
 #include "firmware_attributes_class.h"
 #include "think-lmi.h"
@@ -25,95 +26,66 @@ module_param(debug_support, bool, 0444);
 MODULE_PARM_DESC(debug_support, "Enable debug command support");
 
 /*
- * Name:
- *  Lenovo_BiosSetting
- * Description:
- *  Get item name and settings for current LMI instance.
- * Type:
- *  Query
- * Returns:
- *  "Item,Value"
- * Example:
- *  "WakeOnLAN,Enable"
+ * Name: BiosSetting
+ * Description: Get item name and settings for current LMI instance.
+ * Type: Query
+ * Returns: "Item,Value"
+ * Example: "WakeOnLAN,Enable"
  */
 #define LENOVO_BIOS_SETTING_GUID "51F5230E-9677-46CD-A1CF-C0B23EE34DB7"
 
 /*
- * Name:
- *  Lenovo_SetBiosSetting
- * Description:
- *  Change the BIOS setting to the desired value using the Lenovo_SetBiosSetting
- *  class. To save the settings, use the Lenovo_SaveBiosSetting class.
+ * Name: SetBiosSetting
+ * Description: Change the BIOS setting to the desired value using the SetBiosSetting
+ *  class. To save the settings, use the SaveBiosSetting class.
  *  BIOS settings and values are case sensitive.
  *  After making changes to the BIOS settings, you must reboot the computer
  *  before the changes will take effect.
- * Type:
- *  Method
- * Arguments:
- *  "Item,Value,Password,Encoding,KbdLang;"
- * Example:
- *  "WakeOnLAN,Disable,pa55w0rd,ascii,us;"
+ * Type: Method
+ * Arguments: "Item,Value,Password,Encoding,KbdLang;"
+ * Example: "WakeOnLAN,Disable,pa55w0rd,ascii,us;"
  */
 #define LENOVO_SET_BIOS_SETTINGS_GUID "98479A64-33F5-4E33-A707-8E251EBBC3A1"
 
 /*
- * Name:
- *  Lenovo_SaveBiosSettings
- * Description:
- *  Save any pending changes in settings.
- * Type:
- *  Method
- * Arguments:
- *  "Password,Encoding,KbdLang;"
- * Example:
- * "pa55w0rd,ascii,us;"
+ * Name: SaveBiosSettings
+ * Description: Save any pending changes in settings.
+ * Type: Method
+ * Arguments: "Password,Encoding,KbdLang;"
+ * Example: "pa55w0rd,ascii,us;"
  */
 #define LENOVO_SAVE_BIOS_SETTINGS_GUID "6A4B54EF-A5ED-4D33-9455-B0D9B48DF4B3"
 
 /*
- * Name:
- *  Lenovo_BiosPasswordSettings
- * Description:
- *  Return BIOS Password settings
- * Type:
- *  Query
- * Returns:
- *  PasswordMode, PasswordState, MinLength, MaxLength,
+ * Name: BiosPasswordSettings
+ * Description: Return BIOS Password settings
+ * Type: Query
+ * Returns: PasswordMode, PasswordState, MinLength, MaxLength,
  *  SupportedEncoding, SupportedKeyboard
  */
 #define LENOVO_BIOS_PASSWORD_SETTINGS_GUID "8ADB159E-1E32-455C-BC93-308A7ED98246"
 
 /*
- * Name:
- *  Lenovo_SetBiosPassword
- * Description:
- *  Change a specific password.
+ * Name: SetBiosPassword
+ * Description: Change a specific password.
  *  - BIOS settings cannot be changed at the same boot as power-on
  *    passwords (POP) and hard disk passwords (HDP). If you want to change
  *    BIOS settings and POP or HDP, you must reboot the system after changing
  *    one of them.
  *  - A password cannot be set using this method when one does not already
  *    exist. Passwords can only be updated or cleared.
- * Type:
- *  Method
- * Arguments:
- *  "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;"
- * Example:
- *  "pop,pa55w0rd,newpa55w0rd,ascii,us;”
+ * Type: Method
+ * Arguments: "PasswordType,CurrentPassword,NewPassword,Encoding,KbdLang;"
+ * Example: "pop,pa55w0rd,newpa55w0rd,ascii,us;”
  */
 #define LENOVO_SET_BIOS_PASSWORD_GUID "2651D9FD-911C-4B69-B94E-D0DED5963BD7"
 
 /*
- * Name:
- *  Lenovo_GetBiosSelections
- * Description:
- *  Return a list of valid settings for a given item.
- * Type:
- *  Method
- * Arguments:
- *  "Item"
- * Returns:
- *  "Value1,Value2,Value3,..."
+ * Name: GetBiosSelections
+ * Description: Return a list of valid settings for a given item.
+ * Type: Method
+ * Arguments: "Item"
+ * Returns: "Value1,Value2,Value3,..."
  * Example:
  *  -> "FlashOverLAN"
  *  <- "Enabled,Disabled"
@@ -121,18 +93,14 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support");
 #define LENOVO_GET_BIOS_SELECTIONS_GUID	"7364651A-132F-4FE7-ADAA-40C6C7EE2E3B"
 
 /*
- * Name:
- *  Lenovo_DebugCmdGUID
- * Description
- *  Debug entry GUID method for entering debug commands to the BIOS
+ * Name: DebugCmd
+ * Description: Debug entry method for entering debug commands to the BIOS
  */
 #define LENOVO_DEBUG_CMD_GUID "7FF47003-3B6C-4E5E-A227-E979824A85D1"
 
 /*
- * Name:
- *  Lenovo_OpcodeIF
- * Description:
- *  Opcode interface which provides the ability to set multiple
+ * Name: OpcodeIF
+ * Description: Opcode interface which provides the ability to set multiple
  *  parameters and then trigger an action with a final command.
  *  This is particularly useful for simplifying setting passwords.
  *  With this support comes the ability to set System, HDD and NVMe
@@ -141,10 +109,71 @@ MODULE_PARM_DESC(debug_support, "Enable debug command support");
  */
 #define LENOVO_OPCODE_IF_GUID "DFDDEF2C-57D4-48ce-B196-0FB787D90836"
 
+/*
+ * Name: SetBiosCert
+ * Description: Install BIOS certificate.
+ * Type: Method
+ * Arguments: "Certificate,Password"
+ * You must reboot the computer before the changes will take effect.
+ */
+#define LENOVO_SET_BIOS_CERT_GUID    "26861C9F-47E9-44C4-BD8B-DFE7FA2610FE"
+
+/*
+ * Name: UpdateBiosCert
+ * Description: Update BIOS certificate.
+ * Type: Method
+ * Format: "Certificate,Signature"
+ * You must reboot the computer before the changes will take effect.
+ */
+#define LENOVO_UPDATE_BIOS_CERT_GUID "9AA3180A-9750-41F7-B9F7-D5D3B1BAC3CE"
+
+/*
+ * Name: ClearBiosCert
+ * Description: Uninstall BIOS certificate.
+ * Type: Method
+ * Format: "Serial,Signature"
+ * You must reboot the computer before the changes will take effect.
+ */
+#define LENOVO_CLEAR_BIOS_CERT_GUID  "B2BC39A7-78DD-4D71-B059-A510DEC44890"
+/*
+ * Name: CertToPassword
+ * Description: Switch from certificate to password authentication.
+ * Type: Method
+ * Format: "Password,Signature"
+ * You must reboot the computer before the changes will take effect.
+ */
+#define LENOVO_CERT_TO_PASSWORD_GUID "0DE8590D-5510-4044-9621-77C227F5A70D"
+
+/*
+ * Name: SetBiosSettingCert
+ * Description: Set attribute using certificate authentication.
+ * Type: Method
+ * Format: "Item,Value,Signature"
+ */
+#define LENOVO_SET_BIOS_SETTING_CERT_GUID  "34A008CC-D205-4B62-9E67-31DFA8B90003"
+
+/*
+ * Name: SaveBiosSettingCert
+ * Description: Save any pending changes in settings.
+ * Type: Method
+ * Format: "Signature"
+ */
+#define LENOVO_SAVE_BIOS_SETTING_CERT_GUID "C050FB9D-DF5F-4606-B066-9EFC401B2551"
+
+/*
+ * Name: CertThumbprint
+ * Description: Display Certificate thumbprints
+ * Type: Query
+ * Returns: MD5, SHA1 & SHA256 thumbprints
+ */
+#define LENOVO_CERT_THUMBPRINT_GUID "C59119ED-1C0D-4806-A8E9-59AA318176C4"
+
 #define TLMI_POP_PWD (1 << 0)
 #define TLMI_PAP_PWD (1 << 1)
 #define TLMI_HDD_PWD (1 << 2)
 #define TLMI_SYS_PWD (1 << 3)
+#define TLMI_CERT    (1 << 7)
+
 #define to_tlmi_pwd_setting(kobj)  container_of(kobj, struct tlmi_pwd_setting, kobj)
 #define to_tlmi_attr_setting(kobj)  container_of(kobj, struct tlmi_attr_setting, kobj)
 
@@ -608,18 +637,249 @@ static ssize_t level_store(struct kobject *kobj,
 
 static struct kobj_attribute auth_level = __ATTR_RW(level);
 
+static ssize_t cert_thumbprint(char *buf, const char *arg, int count)
+{
+	const struct acpi_buffer input = { strlen(arg), (char *)arg };
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	const union acpi_object *obj;
+	acpi_status status;
+
+	output.length = ACPI_ALLOCATE_BUFFER;
+	output.pointer = NULL;
+
+	status = wmi_evaluate_method(LENOVO_CERT_THUMBPRINT_GUID, 0, 0, &input, &output);
+	if (ACPI_FAILURE(status)) {
+		kfree(output.pointer);
+		return -EIO;
+	}
+	obj = output.pointer;
+	if (!obj)
+		return -ENOMEM;
+	if (obj->type != ACPI_TYPE_STRING || !obj->string.pointer) {
+		kfree(output.pointer);
+		return -EIO;
+	}
+	count += sysfs_emit_at(buf, count, "%s : %s\n", arg, (char *)obj->string.pointer);
+	kfree(output.pointer);
+
+	return count;
+}
+
+static ssize_t certificate_thumbprint_show(struct kobject *kobj, struct kobj_attribute *attr,
+			 char *buf)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+	int count = 0;
+
+	if (!tlmi_priv.certificate_support || !setting->cert_installed)
+		return -EOPNOTSUPP;
+
+	count += cert_thumbprint(buf, "Md5", count);
+	count += cert_thumbprint(buf, "Sha1", count);
+	count += cert_thumbprint(buf, "Sha256", count);
+	return count;
+}
+
+static struct kobj_attribute auth_cert_thumb = __ATTR_RO(certificate_thumbprint);
+
+static ssize_t cert_to_password_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+	char *auth_str, *passwd, *p;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!tlmi_priv.certificate_support)
+		return -EOPNOTSUPP;
+
+	if (!setting->cert_installed)
+		return -EINVAL;
+
+	if (!setting->signature || !setting->signature[0])
+		return -EACCES;
+
+	passwd = kstrdup(buf, GFP_KERNEL);
+	if (!passwd)
+		return -ENOMEM;
+
+	/* Strip out CR if one is present */
+	p = strchrnul(passwd, '\n');
+	*p = '\0';
+
+	/* Format: 'Password,Signature' */
+	auth_str = kasprintf(GFP_KERNEL, "%s,%s", passwd, setting->signature);
+	if (!auth_str) {
+		kfree(passwd);
+		return -ENOMEM;
+	}
+	ret = tlmi_simple_call(LENOVO_CERT_TO_PASSWORD_GUID, auth_str);
+	kfree(auth_str);
+	kfree(passwd);
+
+	return ret ?: count;
+}
+
+static struct kobj_attribute auth_cert_to_password = __ATTR_WO(cert_to_password);
+
+static ssize_t certificate_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+	char *auth_str, *new_cert, *p;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!tlmi_priv.certificate_support)
+		return -EOPNOTSUPP;
+
+	new_cert = kstrdup(buf, GFP_KERNEL);
+	if (!new_cert)
+		return -ENOMEM;
+	/* Strip out CR if one is present */
+	p = strchrnul(new_cert, '\n');
+	*p = '\0';
+
+	/* If empty then clear installed certificate */
+	if (new_cert[0] == '\0') { /* Clear installed certificate */
+		/* Check that signature is set */
+		if (!setting->signature || !setting->signature[0]) {
+			kfree(new_cert);
+			return -EACCES;
+		}
+		/* Format: 'serial#, signature' */
+		auth_str = kasprintf(GFP_KERNEL, "%s,%s",
+				dmi_get_system_info(DMI_PRODUCT_SERIAL),
+				setting->signature);
+		if (!auth_str) {
+			kfree(new_cert);
+			return -ENOMEM;
+		}
+		ret = tlmi_simple_call(LENOVO_CLEAR_BIOS_CERT_GUID, auth_str);
+		kfree(auth_str);
+		return ret ?: count;
+	}
+
+	if (setting->cert_installed) {
+		/* Certificate is installed so this is an update */
+		if (!setting->signature || !setting->signature[0]) {
+			kfree(new_cert);
+			return -EACCES;
+		}
+		/* Format: 'Certificate,Signature' */
+		auth_str = kasprintf(GFP_KERNEL, "%s,%s",
+				new_cert, setting->signature);
+		if (!auth_str) {
+			kfree(new_cert);
+			return -ENOMEM;
+		}
+		ret = tlmi_simple_call(LENOVO_UPDATE_BIOS_CERT_GUID, auth_str);
+		kfree(auth_str);
+	} else {
+		/* This is a fresh install */
+		if (!setting->valid || !setting->password[0]) {
+			kfree(new_cert);
+			return -EACCES;
+		}
+		/* Format: 'Certificate,Admin-password' */
+		auth_str = kasprintf(GFP_KERNEL, "%s,%s",
+				new_cert, setting->password);
+		if (!auth_str) {
+			kfree(new_cert);
+			return -ENOMEM;
+		}
+		ret = tlmi_simple_call(LENOVO_SET_BIOS_CERT_GUID, auth_str);
+		kfree(auth_str);
+	}
+
+	/* If successful update stored certificate */
+	if (!ret) {
+		kfree(setting->certificate);
+		setting->certificate = new_cert;
+	} else
+		kfree(new_cert);
+
+	return ret ?: count;
+}
+
+static ssize_t certificate_show(struct kobject *kobj, struct kobj_attribute *attr,
+			 char *buf)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+
+	return sysfs_emit(buf, "%s\n", setting->certificate);
+}
+
+static struct kobj_attribute auth_certificate = __ATTR_RW(certificate);
+
+static ssize_t signature_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+	char *new_signature, *p;
+	int ret;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!tlmi_priv.certificate_support)
+		return -EOPNOTSUPP;
+
+	new_signature = kstrdup(buf, GFP_KERNEL);
+	if (!new_signature)
+		return -ENOMEM;
+
+	/* Strip out CR if one is present */
+	p = strchrnul(new_signature, '\n');
+	*p = '\0';
+
+	/* Free any previous signature */
+	kfree(setting->signature);
+	setting->signature = new_signature;
+
+	return ret ?: count;
+}
+
+static ssize_t signature_show(struct kobject *kobj, struct kobj_attribute *attr,
+			 char *buf)
+{
+	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
+
+	return sysfs_emit(buf, "%s\n", setting->signature);
+}
+
+static struct kobj_attribute auth_signature = __ATTR_RW(signature);
+
 static umode_t auth_attr_is_visible(struct kobject *kobj,
 					     struct attribute *attr, int n)
 {
 	struct tlmi_pwd_setting *setting = to_tlmi_pwd_setting(kobj);
 
-	/*We only want to display level and index settings on HDD/NVMe */
+	/* We only want to display level and index settings on HDD/NVMe */
 	if ((attr == (struct attribute *)&auth_index) ||
 			(attr == (struct attribute *)&auth_level)) {
 		if ((setting == tlmi_priv.pwd_hdd) || (setting == tlmi_priv.pwd_nvme))
 			return attr->mode;
 		return 0;
 	}
+
+	/* We only display certificates on Admin account, if supported */
+	if ((attr == (struct attribute *)&auth_certificate) ||
+			(attr == (struct attribute *)&auth_signature) ||
+			(attr == (struct attribute *)&auth_cert_thumb) ||
+			(attr == (struct attribute *)&auth_cert_to_password)) {
+		if ((setting == tlmi_priv.pwd_admin) && tlmi_priv.certificate_support)
+			return attr->mode;
+		return 0;
+	}
+
 	return attr->mode;
 }
 
@@ -635,6 +895,10 @@ static struct attribute *auth_attrs[] = {
 	&auth_kbdlang.attr,
 	&auth_index.attr,
 	&auth_level.attr,
+	&auth_certificate.attr,
+	&auth_signature.attr,
+	&auth_cert_thumb.attr,
+	&auth_cert_to_password.attr,
 	NULL
 };
 
@@ -703,37 +967,58 @@ static ssize_t current_value_store(struct kobject *kobj,
 	p = strchrnul(new_setting, '\n');
 	*p = '\0';
 
-	if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
-		auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
-				tlmi_priv.pwd_admin->password,
-				encoding_options[tlmi_priv.pwd_admin->encoding],
-				tlmi_priv.pwd_admin->kbdlang);
-		if (!auth_str) {
+	/* Check if certificate authentication is enabled and active */
+	if (tlmi_priv.certificate_support && tlmi_priv.pwd_admin->cert_installed) {
+		if (!tlmi_priv.set_signature || !tlmi_priv.save_signature) {
+			ret = -EINVAL;
+			goto out;
+		}
+		set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name,
+					new_setting, tlmi_priv.set_signature);
+		if (!set_str) {
 			ret = -ENOMEM;
 			goto out;
 		}
-	}
 
-	if (auth_str)
-		set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name,
-				new_setting, auth_str);
-	else
-		set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name,
-				new_setting);
-	if (!set_str) {
-		ret = -ENOMEM;
-		goto out;
-	}
+		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTING_CERT_GUID, set_str);
+		if (ret)
+			goto out;
+		ret = tlmi_simple_call(LENOVO_SAVE_BIOS_SETTING_CERT_GUID,
+				tlmi_priv.save_signature);
+		if (ret)
+			goto out;
+	} else { /* Non certiifcate based authentication */
+		if (tlmi_priv.pwd_admin->valid && tlmi_priv.pwd_admin->password[0]) {
+			auth_str = kasprintf(GFP_KERNEL, "%s,%s,%s;",
+					tlmi_priv.pwd_admin->password,
+					encoding_options[tlmi_priv.pwd_admin->encoding],
+					tlmi_priv.pwd_admin->kbdlang);
+			if (!auth_str) {
+				ret = -ENOMEM;
+				goto out;
+			}
+		}
 
-	ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str);
-	if (ret)
-		goto out;
+		if (auth_str)
+			set_str = kasprintf(GFP_KERNEL, "%s,%s,%s", setting->display_name,
+					new_setting, auth_str);
+		else
+			set_str = kasprintf(GFP_KERNEL, "%s,%s;", setting->display_name,
+					new_setting);
+		if (!set_str) {
+			ret = -ENOMEM;
+			goto out;
+		}
 
-	if (auth_str)
-		ret = tlmi_save_bios_settings(auth_str);
-	else
-		ret = tlmi_save_bios_settings("");
+		ret = tlmi_simple_call(LENOVO_SET_BIOS_SETTINGS_GUID, set_str);
+		if (ret)
+			goto out;
 
+		if (auth_str)
+			ret = tlmi_save_bios_settings(auth_str);
+		else
+			ret = tlmi_save_bios_settings("");
+	}
 	if (!ret && !tlmi_priv.pending_changes) {
 		tlmi_priv.pending_changes = true;
 		/* let userland know it may need to check reboot pending again */
@@ -823,6 +1108,63 @@ static ssize_t pending_reboot_show(struct kobject *kobj, struct kobj_attribute *
 
 static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
 
+static ssize_t attr_signature_store(bool set_sig, const char *buf)
+{
+	char *new_signature, *p;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	if (!tlmi_priv.certificate_support)
+		return -EOPNOTSUPP;
+
+	new_signature = kstrdup(buf, GFP_KERNEL);
+	if (!new_signature)
+		return -ENOMEM;
+
+	/* Strip out CR if one is present */
+	p = strchrnul(new_signature, '\n');
+	*p = '\0';
+
+	/* Free any previous signature */
+	kfree(set_sig ? tlmi_priv.set_signature : tlmi_priv.save_signature);
+	if (set_sig)
+		tlmi_priv.set_signature = new_signature;
+	else
+		tlmi_priv.save_signature = new_signature;
+
+	return 0;
+}
+
+static ssize_t set_signature_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	return attr_signature_store(true /*set_sig*/, buf) ?: count;
+}
+
+static ssize_t save_signature_store(struct kobject *kobj,
+				  struct kobj_attribute *attr,
+				  const char *buf, size_t count)
+{
+	return attr_signature_store(false /*set_sig*/, buf) ?: count;
+}
+
+static ssize_t set_signature_show(struct kobject *kobj, struct kobj_attribute *attr,
+			 char *buf)
+{
+	return sysfs_emit(buf, "%s\n", tlmi_priv.set_signature);
+}
+
+static ssize_t save_signature_show(struct kobject *kobj, struct kobj_attribute *attr,
+			 char *buf)
+{
+	return sysfs_emit(buf, "%s\n", tlmi_priv.save_signature);
+}
+
+static struct kobj_attribute attr_set_signature = __ATTR_RW(set_signature);
+static struct kobj_attribute attr_save_signature = __ATTR_RW(save_signature);
+
 /* ---- Debug interface--------------------------------------------------------- */
 static ssize_t debug_cmd_store(struct kobject *kobj, struct kobj_attribute *attr,
 				const char *buf, size_t count)
@@ -896,8 +1238,21 @@ static void tlmi_release_attr(void)
 	sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &pending_reboot.attr);
 	if (tlmi_priv.can_debug_cmd && debug_support)
 		sysfs_remove_file(&tlmi_priv.attribute_kset->kobj, &debug_cmd.attr);
+	if (tlmi_priv.certificate_support) {
+		sysfs_remove_file(&tlmi_priv.attribute_kset->kobj,
+				&attr_set_signature.attr);
+		sysfs_remove_file(&tlmi_priv.attribute_kset->kobj,
+				&attr_save_signature.attr);
+	}
 	kset_unregister(tlmi_priv.attribute_kset);
 
+	if (tlmi_priv.certificate_support) {
+		kfree(tlmi_priv.pwd_admin->certificate);
+		kfree(tlmi_priv.pwd_admin->signature);
+		kfree(tlmi_priv.set_signature);
+		kfree(tlmi_priv.save_signature);
+	}
+
 	/* Authentication structures */
 	sysfs_remove_group(&tlmi_priv.pwd_admin->kobj, &auth_attr_group);
 	kobject_put(&tlmi_priv.pwd_admin->kobj);
@@ -975,6 +1330,17 @@ static int tlmi_sysfs_init(void)
 		if (ret)
 			goto fail_create_attr;
 	}
+	if (tlmi_priv.certificate_support) {
+		ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj,
+				&attr_set_signature.attr);
+		if (ret)
+			goto fail_create_attr;
+		ret = sysfs_create_file(&tlmi_priv.attribute_kset->kobj,
+				&attr_save_signature.attr);
+		if (ret)
+			goto fail_create_attr;
+	}
+
 	/* Create authentication entries */
 	tlmi_priv.authentication_kset = kset_create_and_add("authentication", NULL,
 								&tlmi_priv.class_dev->kobj);
@@ -1087,6 +1453,11 @@ static int tlmi_analyze(void)
 	if (wmi_has_guid(LENOVO_OPCODE_IF_GUID))
 		tlmi_priv.opcode_support = true;
 
+	if (wmi_has_guid(LENOVO_SET_BIOS_CERT_GUID) &&
+		wmi_has_guid(LENOVO_SET_BIOS_SETTING_CERT_GUID) &&
+		wmi_has_guid(LENOVO_SAVE_BIOS_SETTING_CERT_GUID))
+		tlmi_priv.certificate_support = true;
+
 	/*
 	 * Try to find the number of valid settings of this machine
 	 * and use it to create sysfs attributes.
@@ -1198,6 +1569,11 @@ static int tlmi_analyze(void)
 			}
 		}
 	}
+
+	if (tlmi_priv.certificate_support &&
+		(tlmi_priv.pwdcfg.core.password_state & TLMI_CERT))
+		tlmi_priv.pwd_admin->cert_installed = true;
+
 	return 0;
 
 fail_clear_attr:
diff --git a/drivers/platform/x86/think-lmi.h b/drivers/platform/x86/think-lmi.h
index e46c7f383353..47c11b006f6c 100644
--- a/drivers/platform/x86/think-lmi.h
+++ b/drivers/platform/x86/think-lmi.h
@@ -62,6 +62,9 @@ struct tlmi_pwd_setting {
 	char kbdlang[TLMI_LANG_MAXLEN];
 	int index; /*Used for HDD and NVME auth */
 	enum level_option level;
+	bool cert_installed;
+	char *certificate;
+	char *signature;
 };
 
 /* Attribute setting details */
@@ -82,6 +85,7 @@ struct think_lmi {
 	bool pending_changes;
 	bool can_debug_cmd;
 	bool opcode_support;
+	bool certificate_support;
 
 	struct tlmi_attr_setting *setting[TLMI_SETTINGS_COUNT];
 	struct device *class_dev;
@@ -94,6 +98,9 @@ struct think_lmi {
 	struct tlmi_pwd_setting *pwd_system;
 	struct tlmi_pwd_setting *pwd_hdd;
 	struct tlmi_pwd_setting *pwd_nvme;
+
+	char *set_signature;
+	char *save_signature;
 };
 
 #endif /* !_THINK_LMI_H_ */
-- 
2.35.1