Re: [PATCH v12 03/13] HP BIOSCFG driver - bioscfg

[Ilpo Järvinen]

On Fri, 5 May 2023, Jorge Lopez wrote:

> HP BIOS Configuration driver purpose is to provide a driver supporting
> the latest sysfs class firmware attributes framework allowing the user
> to change BIOS settings and security solutions on HP Inc.ʼs commercial
> notebooks.
> 
> Many features of HP Commercial notebooks can be managed using Windows
> Management Instrumentation (WMI). WMI is an implementation of Web-Based
> Enterprise Management (WBEM) that provides a standards-based interface
> for changing and monitoring system settings. HP BIOSCFG driver provides
> a native Linux solution and the exposed features facilitates the
> migration to Linux environments.
> 
> The Linux security features to be provided in hp-bioscfg driver enables
> managing the BIOS settings and security solutions via sysfs, a virtual
> filesystem that can be used by user-mode applications. The new
> documentation cover HP-specific firmware sysfs attributes such Secure
> Platform Management and Sure Start. Each section provides security
> feature description and identifies sysfs directories and files exposed
> by the driver.
> 
> Many HP Commercial notebooks include a feature called Secure Platform
> Management (SPM), which replaces older password-based BIOS settings
> management with public key cryptography. PC secure product management
> begins when a target system is provisioned with cryptographic keys
> that are used to ensure the integrity of communications between system
> management utilities and the BIOS.
> 
> HP Commercial notebooks have several BIOS settings that control its
> behaviour and capabilities, many of which are related to security.
> To prevent unauthorized changes to these settings, the system can
> be configured to use a cryptographic signature-based authorization
> string that the BIOS will use to verify authorization to modify the
> setting.
> 
> Linux Security components are under development and not published yet.
> The only linux component is the driver (hp bioscfg) at this time.
> Other published security components are under Windows.
> 
> Signed-off-by: Jorge Lopez <jorge.lopez2@xxxxxx>
> 
> ---
> Based on the latest platform-drivers-x86.git/for-next
> ---
>  drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 982 +++++++++++++++++++
>  1 file changed, 982 insertions(+)
>  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> 
> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> new file mode 100644
> index 000000000000..0079aedaded5
> --- /dev/null
> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
> @@ -0,0 +1,982 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Common methods for use with hp-bioscfg driver
> + *
> + *  Copyright (c) 2022 HP Development Company, L.P.
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/fs.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/wmi.h>
> +#include "bioscfg.h"
> +#include "../../firmware_attributes_class.h"
> +#include <linux/nls.h>
> +#include <linux/errno.h>
> +
> +MODULE_AUTHOR("Jorge Lopez <jorge.lopez2@xxxxxx>");
> +MODULE_DESCRIPTION("HP BIOS Configuration Driver");
> +MODULE_LICENSE("GPL");
> +
> +struct bioscfg_priv bioscfg_drv = {
> +	.mutex = __MUTEX_INITIALIZER(bioscfg_drv.mutex),
> +};
> +
> +static struct class *fw_attr_class;
> +
> +int get_integer_from_buffer(u8 **buffer, u32 *buffer_size, u32 *integer)
> +{
> +	int *ptr = PTR_ALIGN((int *)*buffer, 4);
> +
> +	/* Ensure there is enough space remaining to read the integer */
> +	if (*buffer_size < sizeof(int))
> +		return -EINVAL;
> +
> +	*integer = *(ptr++);
> +	*buffer = (u8 *)ptr;
> +	*buffer_size -= sizeof(int);
> +
> +	return 0;
> +}
> +
> +int get_string_from_buffer(u8 **buffer, u32 *buffer_size, char *dst, u32 dst_size)
> +{
> +	u16 *src = (u16 *)*buffer;
> +	u16 src_size;
> +
> +	u16 size;
> +	int i;
> +	int conv_dst_size;
> +
> +	if (*buffer_size < sizeof(u16))
> +		return -EINVAL;
> +
> +	src_size = *(src++);
> +	/* size value in u16 chars */
> +	size = src_size / sizeof(u16);
> +
> +	/* Ensure there is enough space remaining to read and convert
> +	 * the string
> +	 */
> +	if (*buffer_size < src_size)
> +		return -EINVAL;
> +
> +	for (i = 0; i < size; i++)
> +		if (src[i] == '\\' ||
> +		    src[i] == '\r' ||
> +		    src[i] == '\n' ||
> +		    src[i] == '\t')
> +			size++;
> +
> +	/*
> +	 * Conversion is limited to destination string max number of
> +	 * bytes.
> +	 */
> +	conv_dst_size = size;
> +	if (size > dst_size)
> +		conv_dst_size = dst_size - 1;
> +
> +	/*
> +	 * convert from UTF-16 unicode to ASCII
> +	 */
> +	utf16s_to_utf8s(src, src_size, UTF16_HOST_ENDIAN, dst, conv_dst_size);
> +	dst[conv_dst_size] = 0;
> +
> +	for (i = 0; i < size && i < conv_dst_size; i++) {
> +		if (*src == '\\' ||
> +		    *src == '\r' ||
> +		    *src == '\n' ||
> +		    *src == '\t')
> +			dst[i++] = '\\';
> +
> +		if (*src == '\r')
> +			dst[i] = 'r';
> +		else if (*src == '\n')
> +			dst[i] = 'n';
> +		else if (*src == '\t')
> +			dst[i] = 't';
> +		else if (*src == '"')
> +			dst[i] = '\'';
> +		else
> +			dst[i] = *src;
> +		src++;
> +	}

Please check e.g., string_escape_mem(). This looks pretty similar to it 
(but I guess types make it hard to reuse). At minimum, escape_space() 
might be useful if exported?

> +	*buffer = (u8 *)src;
> +	*buffer_size -= size * sizeof(u16);
> +
> +	return size;
> +}
> +
> +int enforce_single_line_input(char *buf, size_t count)
> +{
> +	char *p;
> +
> +	p = memchr(buf, '\n', count);
> +
> +	if (p == buf + count - 1)
> +		*p = '\0'; /* strip trailing newline */
> +	else if (p)
> +		return -EINVAL;  /* enforce single line input */
> +
> +	return 0;
> +}
> +
> +/* Set pending reboot value and generate KOBJ_NAME event */
> +void set_reboot_and_signal_event(void)
> +{
> +	bioscfg_drv.pending_reboot = true;
> +	kobject_uevent(&bioscfg_drv.class_dev->kobj, KOBJ_CHANGE);
> +}
> +
> +/*
> + * calculate_string_buffer() - determines size of string buffer for
> + * use with BIOS communication
> + *
> + * @str: the string to calculate based upon
> + */
> +size_t hp_calculate_string_buffer(const char *str)
> +{
> +	int length = strlen(str);
> +
> +	/* BIOS expects 4 bytes when an empty string is found */
> +	if (length == 0)
> +		return 4;
> +
> +	/* u16 length field + one UTF16 char for each input char */
> +	return sizeof(u16) + strlen(str) * sizeof(u16);
> +}
> +
> +int hp_wmi_error_and_message(int error_code)
> +{
> +	char *error_msg = NULL;
> +	int ret;
> +
> +	switch (error_code) {
> +	case SUCCESS:
> +		error_msg = "Success";
> +		ret = 0;
> +		break;
> +	case CMD_FAILED:
> +		error_msg = "Command failed";
> +		ret = -EINVAL;
> +		break;
> +	case INVALID_SIGN:
> +		error_msg = "Invalid signature";
> +		ret = -EINVAL;
> +		break;
> +	case INVALID_CMD_VALUE:
> +		error_msg = "Invalid command value/Feature not supported";
> +		ret = -EOPNOTSUPP;
> +		break;
> +	case INVALID_CMD_TYPE:
> +		error_msg = "Invalid command type";
> +		ret = -EINVAL;
> +		break;
> +	case INVALID_DATA_SIZE:
> +		error_msg = "Invalid data size";
> +		ret = -EINVAL;
> +		break;
> +	case INVALID_CMD_PARAM:
> +		error_msg = "Invalid command parameter";
> +		ret = -EINVAL;
> +		break;
> +	case ENCRYP_CMD_REQUIRED:
> +		error_msg = "Secure/encrypted command required";
> +		ret = -EACCES;
> +		break;
> +	case NO_SECURE_SESSION:
> +		error_msg = "No secure session established";
> +		ret = -EACCES;
> +		break;
> +	case SECURE_SESSION_FOUND:
> +		error_msg = "Secure session already established";
> +		ret = -EACCES;
> +		break;
> +	case SECURE_SESSION_FAILED:
> +		error_msg = "Secure session failed";
> +		ret = -EIO;
> +		break;
> +	case AUTH_FAILED:
> +		error_msg = "Other permission/Authentication failed";
> +		ret = -EACCES;
> +		break;
> +	case INVALID_BIOS_AUTH:
> +		error_msg = "Invalid BIOS administrator password";
> +		ret = -EINVAL;
> +		break;
> +	case NONCE_DID_NOT_MATCH:
> +		error_msg = "Nonce did not match";
> +		ret = -EINVAL;
> +		break;
> +	case GENERIC_ERROR:
> +		error_msg = "Generic/Other error";
> +		ret = -EIO;
> +		break;
> +	case BIOS_ADMIN_POLICY_NOT_MET:
> +		error_msg = "BIOS Admin password does not meet password policy requirements";
> +		ret = -EINVAL;
> +		break;
> +	case BIOS_ADMIN_NOT_SET:
> +		error_msg = "BIOS Setup password is not set.";

Why this has . and other do not?

> +		ret = -EPERM;
> +		break;
> +	case P21_NO_PROVISIONED:
> +		error_msg = "P21 is not provisioned";
> +		ret = -EPERM;
> +		break;
> +	case P21_PROVISION_IN_PROGRESS:
> +		error_msg = "P21 is already provisioned or provisioning is in progress and a signing key has already been sent.";

Dot also here at end?

> +		ret = -EINPROGRESS;
> +		break;
> +	case P21_IN_USE:
> +		error_msg = "P21 in use (cannot deprovision)";
> +		ret = -EPERM;
> +		break;
> +	case HEP_NOT_ACTIVE:
> +		error_msg = "HEP not activated";
> +		ret = -EPERM;
> +		break;
> +	case HEP_ALREADY_SET:
> +		error_msg = "HEP Transport already set";

Is it okay to capitalize Transport (could be, I don't know)?

> +		ret = -EINVAL;
> +		break;
> +	case HEP_CHECK_STATE:
> +		error_msg = "Check the current HEP state";
> +		ret = -EINVAL;
> +		break;
> +	default:
> +		error_msg = "Generic/Other error";
> +		ret = -EIO;
> +		break;
> +	}
> +
> +	if (error_code)
> +		pr_warn_ratelimited("Returned error 0x%x, \"%s\"\n", error_code, error_msg);
> +
> +	return ret;
> +}
> +
> +static ssize_t pending_reboot_show(struct kobject *kobj,
> +				   struct kobj_attribute *attr,
> +				   char *buf)
> +{
> +	return sysfs_emit(buf, "%d\n", bioscfg_drv.pending_reboot);
> +}
> +
> +static struct kobj_attribute pending_reboot = __ATTR_RO(pending_reboot);
> +
> +/*
> + * create_attributes_level_sysfs_files() - Creates pending_reboot attributes
> + */
> +static int create_attributes_level_sysfs_files(void)
> +{
> +	return  sysfs_create_file(&bioscfg_drv.main_dir_kset->kobj,
> +				&pending_reboot.attr);
> +}
> +
> +static void attr_name_release(struct kobject *kobj)
> +{
> +	kfree(kobj);
> +}
> +
> +static const struct kobj_type attr_name_ktype = {
> +	.release	= attr_name_release,
> +	.sysfs_ops	= &kobj_sysfs_ops,
> +};
> +
> +/*
> + * get_wmiobj_pointer() - Get Content of WMI block for particular instance
> + *
> + * @instance_id: WMI instance ID
> + * @guid_string: WMI GUID (in str form)
> + *
> + * Fetches the content for WMI block (instance_id) under GUID (guid_string)
> + * Caller must kfree the return
> + */
> +union acpi_object *get_wmiobj_pointer(int instance_id, const char *guid_string)
> +{
> +	struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
> +	acpi_status status;
> +
> +	status = wmi_query_block(guid_string, instance_id, &out);
> +	return ACPI_SUCCESS(status) ? (union acpi_object *)out.pointer : NULL;
> +}
> +
> +/*
> + * get_instance_count() - Compute total number of instances under guid_string
> + *
> + * @guid_string: WMI GUID (in string form)
> + */
> +int get_instance_count(const char *guid_string)
> +{
> +	union acpi_object *wmi_obj = NULL;
> +	int i = 0;
> +
> +	do {
> +		kfree(wmi_obj);
> +		wmi_obj = get_wmiobj_pointer(i, guid_string);
> +		i++;
> +	} while (wmi_obj);
> +
> +	return i - 1;

To me this would look easier to understand:

	while (1) {
		wmi_obj = get_wmiobj_pointer(i, guid_string);
		if (!wmi_obj)
			return i;
		i++;
		kfree(wmi_obj);
	}

> +}
> +
> +/*
> + * alloc_attributes_data() - Allocate attributes data for a particular type
> + *
> + * @attr_type: Attribute type to allocate
> + */
> +static int alloc_attributes_data(int attr_type)
> +{
> +	switch (attr_type) {
> +	case HPWMI_STRING_TYPE:
> +		return alloc_string_data();
> +
> +	case HPWMI_INTEGER_TYPE:
> +		return alloc_integer_data();
> +
> +	case HPWMI_ENUMERATION_TYPE:
> +		return alloc_enumeration_data();
> +
> +	case HPWMI_ORDERED_LIST_TYPE:
> +		return alloc_ordered_list_data();
> +
> +	case HPWMI_PASSWORD_TYPE:
> +		return alloc_password_data();
> +
> +	default:
> +		return 0;
> +	}
> +}
> +
> +int convert_hexstr_to_str(const char *input, u32 input_len, char **str, int *len)
> +{
> +	int ret = 0;
> +	int new_len = 0;
> +	char tmp[] = "0x00";
> +	char *new_str = NULL;
> +	long  ch;
> +	int i;
> +
> +	if (input_len <= 0 || !input || !str || !len)
> +		return -EINVAL;
> +
> +	*len = 0;
> +	*str = NULL;
> +
> +	new_str = kmalloc(input_len, GFP_KERNEL);
> +	if (!new_str)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < input_len; i += 5) {
> +		strncpy(tmp, input + i, strlen(tmp));
> +		if (kstrtol(tmp, 16, &ch) == 0) {
> +			// escape char
> +			if (ch == '\\' ||
> +			    ch == '\r' ||
> +			    ch == '\n' || ch == '\t') {
> +				if (ch == '\r')
> +					ch = 'r';
> +				else if (ch == '\n')
> +					ch = 'n';
> +				else if (ch == '\t')
> +					ch = 't';
> +				new_str[new_len++] = '\\';
> +			}

Looks the same as in the other place. escape_space() or perhaps a common 
helper in this file if escape_space() handles too many chars.

> +			new_str[new_len++] = ch;
> +			if (ch == '\0')
> +				break;
> +		}
> +	}
> +
> +	if (new_len) {
> +		new_str[new_len] = '\0';
> +		*str = krealloc(new_str, (new_len + 1) * sizeof(char),
> +				GFP_KERNEL);
> +		if (*str)
> +			*len = new_len;
> +		else
> +			ret = -ENOMEM;
> +	} else {
> +		ret = -EFAULT;
> +	}
> +
> +	if (ret)
> +		kfree(new_str);
> +	return ret;
> +}
> +
> +/* map output size to the corresponding WMI method id */
> +int encode_outsize_for_pvsz(int outsize)
> +{
> +	if (outsize > 4096)
> +		return -EINVAL;
> +	if (outsize > 1024)
> +		return 5;
> +	if (outsize > 128)
> +		return 4;
> +	if (outsize > 4)
> +		return 3;
> +	if (outsize > 0)
> +		return 2;

There would be SZ_xx in include/linux/sizes.h

> +	return 1;
> +}
> +
> +/*
> + * Update friendly display name for several attributes associated to
> + * 'Schedule Power-On'
> + */
> +void friendly_user_name_update(char *path, const char *attr_name,
> +			       char *attr_display, int attr_size)
> +{
> +	if (strstr(path, SCHEDULE_POWER_ON))
> +		snprintf(attr_display,
> +			 attr_size,
> +			 "%s - %s",
> +			 SCHEDULE_POWER_ON,
> +			 attr_name);

Use less lines.

> +	else
> +		strscpy(attr_display, attr_name, attr_size);
> +}
> +
> +/*
> + * update_attribute_permissions() - Update attributes permissions when
> + * isReadOnly value is 1
> + *
> + * @isReadOnly:  ReadOnly value
> + * @current_val: kobj_attribute corresponding to attribute.
> + *
> + */
> +void update_attribute_permissions(u32 is_readonly, struct kobj_attribute *current_val)
> +{
> +	if (is_readonly)
> +		current_val->attr.mode = 0444;
> +	else
> +		current_val->attr.mode = 0644;

I'd use ? : operator here.

> +}
> +
> +/**
> + * destroy_attribute_objs() - Free a kset of kobjects
> + * @kset: The kset to destroy
> + *
> + * Fress kobjects created for each attribute_name under attribute type kset
> + */
> +static void destroy_attribute_objs(struct kset *kset)
> +{
> +	struct kobject *pos, *next;
> +
> +	list_for_each_entry_safe(pos, next, &kset->list, entry)
> +		kobject_put(pos);
> +}
> +
> +/**
> + * release_attributes_data() - Clean-up all sysfs directories and files created
> + */
> +static void release_attributes_data(void)
> +{
> +	mutex_lock(&bioscfg_drv.mutex);
> +
> +	exit_string_attributes();
> +	exit_integer_attributes();
> +	exit_enumeration_attributes();
> +	exit_ordered_list_attributes();
> +	exit_password_attributes();
> +	exit_sure_start_attributes();
> +	exit_secure_platform_attributes();
> +
> +	if (bioscfg_drv.authentication_dir_kset) {
> +		destroy_attribute_objs(bioscfg_drv.authentication_dir_kset);
> +		kset_unregister(bioscfg_drv.authentication_dir_kset);
> +		bioscfg_drv.authentication_dir_kset = NULL;
> +	}
> +	if (bioscfg_drv.main_dir_kset) {
> +		sysfs_remove_file(&bioscfg_drv.main_dir_kset->kobj, &pending_reboot.attr);
> +		destroy_attribute_objs(bioscfg_drv.main_dir_kset);
> +		kset_unregister(bioscfg_drv.main_dir_kset);
> +		bioscfg_drv.main_dir_kset = NULL;
> +	}
> +	mutex_unlock(&bioscfg_drv.mutex);
> +}
> +
> +/*
> + * hp_add_other_attributes - Initialize HP custom attributes not reported by
> + * BIOS and required to support Secure Platform, Sure Start, and Sure
> + * Admin.

Make summary shorter and put the rest into description.

> + * @attr_type: Custom HP attribute not reported by BIOS
> + *
> + * Initialize all 2 types of attributes: Platform and Sure Start
> + * object.  Populates each attribute types respective properties

Don't use double space in kernel comments.

> + * under sysfs files.
> + *
> + * Returns zero(0) if successful.  Otherwise, a negative value.

Why zero(0) ?
Otherwise, errno is returned.

> + */
> +static int hp_add_other_attributes(int attr_type)
> +{
> +	struct kobject *attr_name_kobj;
> +	union acpi_object *obj = NULL;
> +	int retval;
> +	char *attr_name;
> +
> +	mutex_lock(&bioscfg_drv.mutex);
> +
> +	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
> +	if (!attr_name_kobj) {
> +		retval = -ENOMEM;
> +		goto err_other_attr_init;
> +	}
> +
> +	/* Check if attribute type is supported */
> +	switch (attr_type) {
> +	case HPWMI_SECURE_PLATFORM_TYPE:
> +		attr_name_kobj->kset = bioscfg_drv.authentication_dir_kset;
> +		attr_name = SPM_STR;
> +		break;
> +
> +	case HPWMI_SURE_START_TYPE:
> +		attr_name_kobj->kset = bioscfg_drv.main_dir_kset;
> +		attr_name = SURE_START_STR;
> +		break;
> +
> +	default:
> +		pr_err("Error: Unknown attr_type: %d\n", attr_type);
> +		retval = -EINVAL;
> +		goto err_other_attr_init;
> +	}
> +
> +	retval = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
> +				      NULL, "%s", attr_name);
> +	if (retval) {
> +		pr_err("Error encountered [%d]\n", retval);
> +		kobject_put(attr_name_kobj);
> +		goto err_other_attr_init;
> +	}
> +
> +	/* Populate attribute data */
> +	switch (attr_type) {
> +	case HPWMI_SECURE_PLATFORM_TYPE:
> +		retval = populate_secure_platform_data(attr_name_kobj);
> +		break;
> +
> +	case HPWMI_SURE_START_TYPE:
> +		retval = populate_sure_start_data(attr_name_kobj);
> +		break;
> +
> +	default:
> +		goto err_other_attr_init;

Does this miss kobject_put() ? If that's the case it should be moved to 
error rollbacks.

It shuold also pick retval since it gotos to error path rather than 
leaving it to 0.

> +	}
> +
> +	mutex_unlock(&bioscfg_drv.mutex);
> +	return 0;
> +
> +err_other_attr_init:
> +	mutex_unlock(&bioscfg_drv.mutex);
> +	kfree(obj);
> +	return retval;
> +}
> +
> +static int hp_init_bios_package_attribute(enum hp_wmi_data_type attr_type,
> +					  union acpi_object *obj,
> +					  const char *guid, int min_elements,
> +					  int instance_id)
> +{
> +	struct kobject *attr_name_kobj;
> +	union acpi_object *elements;
> +	struct kset *temp_kset;
> +

Remove extra newline.

> +	char *str_value = NULL;
> +	int str_len;
> +	int retval = 0;
> +
> +	/* Take action appropriate to each ACPI TYPE */
> +	if (obj->package.count < min_elements) {
> +		pr_err("ACPI-package does not have enough elements: %d < %d\n",
> +		       obj->package.count, min_elements);
> +		goto pack_attr_exit;
> +	}
> +
> +	elements = obj->package.elements;
> +
> +	/* sanity checking */
> +	if (elements[NAME].type != ACPI_TYPE_STRING) {
> +		pr_debug("incorrect element type\n");
> +		goto pack_attr_exit;
> +	}
> +	if (strlen(elements[NAME].string.pointer) == 0) {
> +		pr_debug("empty attribute found\n");
> +		goto pack_attr_exit;
> +	}
> +
> +	if (attr_type == HPWMI_PASSWORD_TYPE)
> +		temp_kset = bioscfg_drv.authentication_dir_kset;
> +	else
> +		temp_kset = bioscfg_drv.main_dir_kset;
> +
> +	/* convert attribute name to string */
> +	retval = convert_hexstr_to_str(elements[NAME].string.pointer,
> +				       elements[NAME].string.length,
> +				       &str_value, &str_len);
> +
> +	if (retval) {
> +		pr_debug("Failed to populate integer package data. Error [0%0x]\n",
> +			 retval);
> +		kfree(str_value);
> +		return retval;

Use goto instead.

> +	}
> +
> +	/* All duplicate attributes found are ignored */
> +	if (kset_find_obj(temp_kset, str_value)) {
> +		pr_debug("Duplicate attribute name found - %s\n",
> +			 str_value);
> +		goto pack_attr_exit;
> +	}
> +
> +	/* build attribute */
> +	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
> +	if (!attr_name_kobj) {
> +		retval = -ENOMEM;
> +		goto pack_attr_exit;
> +	}
> +
> +	attr_name_kobj->kset = temp_kset;
> +
> +	retval = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
> +				      NULL, "%s", str_value);
> +
> +	if (retval) {
> +		kobject_put(attr_name_kobj);
> +		goto pack_attr_exit;
> +	}
> +
> +	/* enumerate all of these attributes */
> +	switch (attr_type) {
> +	case HPWMI_STRING_TYPE:
> +		retval = populate_string_package_data(elements,
> +						      instance_id,
> +						      attr_name_kobj);
> +		break;
> +	case HPWMI_INTEGER_TYPE:
> +		retval = populate_integer_package_data(elements,
> +						       instance_id,
> +						       attr_name_kobj);
> +		break;
> +	case HPWMI_ENUMERATION_TYPE:
> +		retval = populate_enumeration_package_data(elements,
> +							   instance_id,
> +							   attr_name_kobj);
> +		break;
> +	case HPWMI_ORDERED_LIST_TYPE:
> +		retval = populate_ordered_list_package_data(elements,
> +							    instance_id,
> +							    attr_name_kobj);
> +		break;
> +	case HPWMI_PASSWORD_TYPE:
> +		retval = populate_password_package_data(elements,
> +							instance_id,
> +							attr_name_kobj);
> +		break;
> +	default:
> +		pr_debug("Unknown attribute type found: 0x%x\n", attr_type);

Should this set retval?
Should it do kobject_put()?

> +		break;
> +	}
> +
> +pack_attr_exit:
> +	kfree(str_value);
> +	return retval;
> +}
> +
> +static int hp_init_bios_buffer_attribute(enum hp_wmi_data_type attr_type,
> +					 union acpi_object *obj,
> +					 const char *guid, int min_elements,
> +					 int instance_id)
> +{
> +	struct kobject *attr_name_kobj;
> +	struct kset *temp_kset;
> +	char str[MAX_BUFF];
> +
> +	char *temp_str = NULL;
> +	char *str_value = NULL;
> +	u8 *buffer_ptr = NULL;
> +	int buffer_size;
> +	int retval = 0;
> +
> +	buffer_size = obj->buffer.length;
> +	buffer_ptr = obj->buffer.pointer;
> +
> +	retval = get_string_from_buffer(&buffer_ptr,
> +					&buffer_size, str, MAX_BUFF);

One line. 

> +

Remove extra newline.

> +	if (retval < 0)
> +		goto buff_attr_exit;
> +
> +	if (attr_type == HPWMI_PASSWORD_TYPE ||
> +	    attr_type == HPWMI_SECURE_PLATFORM_TYPE)
> +		temp_kset = bioscfg_drv.authentication_dir_kset;
> +	else
> +		temp_kset = bioscfg_drv.main_dir_kset;
> +
> +	/* All duplicate attributes found are ignored */
> +	if (kset_find_obj(temp_kset, str)) {
> +		pr_debug("Duplicate attribute name found - %s\n", str);
> +		goto buff_attr_exit;
> +	}
> +
> +	/* build attribute */
> +	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
> +	if (!attr_name_kobj) {
> +		retval = -ENOMEM;
> +		goto buff_attr_exit;
> +	}
> +
> +	attr_name_kobj->kset = temp_kset;
> +
> +	temp_str = str;
> +	if (attr_type == HPWMI_SECURE_PLATFORM_TYPE)
> +		temp_str = "SPM";
> +
> +	retval = kobject_init_and_add(attr_name_kobj,
> +				      &attr_name_ktype, NULL, "%s",
> +				      temp_str);
> +	if (retval) {
> +		kobject_put(attr_name_kobj);
> +		goto buff_attr_exit;
> +	}
> +
> +	/* enumerate all of these attributes */
> +	switch (attr_type) {
> +	case HPWMI_STRING_TYPE:
> +		retval = populate_string_buffer_data(buffer_ptr,
> +						     &buffer_size,
> +						     instance_id,
> +						     attr_name_kobj);
> +		break;
> +	case HPWMI_INTEGER_TYPE:
> +		retval = populate_integer_buffer_data(buffer_ptr,
> +						      &buffer_size,
> +						      instance_id,
> +						      attr_name_kobj);
> +		break;
> +	case HPWMI_ENUMERATION_TYPE:
> +		retval = populate_enumeration_buffer_data(buffer_ptr,
> +							  &buffer_size,
> +							  instance_id,
> +							  attr_name_kobj);
> +		break;
> +	case HPWMI_ORDERED_LIST_TYPE:
> +		retval = populate_ordered_list_buffer_data(buffer_ptr,
> +							   &buffer_size,
> +							   instance_id,
> +							   attr_name_kobj);
> +		break;
> +	case HPWMI_PASSWORD_TYPE:
> +		retval = populate_password_buffer_data(buffer_ptr,
> +						       &buffer_size,
> +						       instance_id,
> +						       attr_name_kobj);
> +		break;
> +	default:
> +		pr_debug("Unknown attribute type found: 0x%x\n", attr_type);

retval?
kobject_put()?

> +		break;
> +	}
> +
> +buff_attr_exit:
> +	kfree(str_value);
> +	return retval;
> +}
> +
> +/*
> + * hp_init_bios_attributes - Initialize all attributes for a type
> + * @attr_type: The attribute type to initialize
> + * @guid: The WMI GUID associated with this type to initialize
> + *
> + * Initialiaze all 5 types of attributes: enumeration, integer,
> + * string, password, ordered list  object.  Populates each attrbute types
> + * respective properties under sysfs files
> + */
> +static int hp_init_bios_attributes(enum hp_wmi_data_type attr_type, const char *guid)
> +{
> +	union acpi_object *obj = NULL;
> +	int min_elements;
> +
> +	/* instance_id needs to be reset for each type GUID
> +	 * also, instance IDs are unique within GUID but not across
> +	 */

This comment breaks declarations and seems out-of-place anyway.

> +	int instance_id = 0;
> +	int retval = 0;
> +
> +	retval = alloc_attributes_data(attr_type);
> +	if (retval)
> +		return retval;
> +
> +	switch (attr_type) {
> +	case HPWMI_STRING_TYPE:
> +		min_elements = STR_ELEM_CNT;
> +		break;
> +	case HPWMI_INTEGER_TYPE:
> +		min_elements = INT_ELEM_CNT;
> +		break;
> +	case HPWMI_ENUMERATION_TYPE:
> +		min_elements = ENUM_ELEM_CNT;
> +		break;
> +	case HPWMI_ORDERED_LIST_TYPE:
> +		min_elements = ORD_ELEM_CNT;
> +		break;
> +	case HPWMI_PASSWORD_TYPE:
> +		min_elements = PSWD_ELEM_CNT;
> +		break;
> +	default:
> +		pr_err("Error: Unknown attr_type: %d\n", attr_type);
> +		return -EINVAL;
> +	}
> +
> +	/* need to use specific instance_id and guid combination to get right data */
> +	obj = get_wmiobj_pointer(instance_id, guid);
> +	if (!obj)
> +		return -ENODEV;
> +
> +	mutex_lock(&bioscfg_drv.mutex);
> +	while (obj) {
> +		/* Take action appropriate to each ACPI TYPE */
> +		if (obj->type == ACPI_TYPE_PACKAGE) {
> +			retval = hp_init_bios_package_attribute(attr_type, obj,
> +								guid, min_elements,
> +								instance_id);
> +			if (retval)
> +				goto err_attr_init;
> +		} else if (obj->type == ACPI_TYPE_BUFFER) {
> +			retval = hp_init_bios_buffer_attribute(attr_type, obj,
> +							       guid, min_elements,
> +							       instance_id);
> +			if (retval)
> +				goto err_attr_init;
> +		} else {
> +			pr_err("Expected ACPI-package or buffer type, got: %d\n",
> +			       obj->type);
> +			retval = -EIO;
> +			goto err_attr_init;
> +		}
> +
> +		kfree(obj);
> +		instance_id++;
> +		obj = get_wmiobj_pointer(instance_id, guid);
> +	}
> +
> +err_attr_init:
> +	mutex_unlock(&bioscfg_drv.mutex);
> +	kfree(obj);
> +	return retval;
> +}
> +
> +static int __init hp_init(void)
> +{
> +	int ret;
> +	int hp_bios_capable = wmi_has_guid(HP_WMI_BIOS_GUID);
> +	int set_bios_settings = wmi_has_guid(HP_WMI_SET_BIOS_SETTING_GUID);
> +
> +	if (!hp_bios_capable) {
> +		pr_err("Unable to run on non-HP system\n");
> +		return -ENODEV;
> +	}
> +
> +	if (!set_bios_settings) {
> +		pr_err("Unable to set BIOS settings on HP systems\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = init_hp_attr_set_interface();
> +	if (ret)
> +		return ret;
> +
> +	ret = fw_attributes_class_get(&fw_attr_class);
> +	if (ret)
> +		goto err_unregister_class;
> +
> +	bioscfg_drv.class_dev = device_create(fw_attr_class, NULL, MKDEV(0, 0),
> +					      NULL, "%s", DRIVER_NAME);
> +	if (IS_ERR(bioscfg_drv.class_dev)) {
> +		ret = PTR_ERR(bioscfg_drv.class_dev);
> +		goto err_unregister_class;
> +	}
> +
> +	bioscfg_drv.main_dir_kset = kset_create_and_add("attributes", NULL,
> +							&bioscfg_drv.class_dev->kobj);
> +	if (!bioscfg_drv.main_dir_kset) {
> +		ret = -ENOMEM;
> +		pr_debug("Failed to create and add attributes\n");
> +		goto err_destroy_classdev;
> +	}
> +
> +	bioscfg_drv.authentication_dir_kset = kset_create_and_add("authentication", NULL,
> +								  &bioscfg_drv.class_dev->kobj);
> +	if (!bioscfg_drv.authentication_dir_kset) {
> +		ret = -ENOMEM;
> +		pr_debug("Failed to create and add authentication\n");
> +		goto err_release_attributes_data;
> +	}
> +
> +	/*
> +	 * sysfs level attributes.
> +	 * - pending_reboot
> +	 */

Is this comment useful?

> +	ret = create_attributes_level_sysfs_files();
> +	if (ret)
> +		pr_debug("Failed to create sysfs level attributes\n");

Should this do error rollback and return error instead?

> +	ret = hp_init_bios_attributes(HPWMI_STRING_TYPE, HP_WMI_BIOS_STRING_GUID);
> +	if (ret)
> +		pr_debug("Failed to populate string type attributes\n");
> +
> +	ret = hp_init_bios_attributes(HPWMI_INTEGER_TYPE, HP_WMI_BIOS_INTEGER_GUID);
> +	if (ret)
> +		pr_debug("Failed to populate integer type attributes\n");
> +
> +	ret = hp_init_bios_attributes(HPWMI_ENUMERATION_TYPE, HP_WMI_BIOS_ENUMERATION_GUID);
> +	if (ret)
> +		pr_debug("Failed to populate enumeration type attributes\n");
> +
> +	ret = hp_init_bios_attributes(HPWMI_ORDERED_LIST_TYPE, HP_WMI_BIOS_ORDERED_LIST_GUID);
> +	if (ret)
> +		pr_debug("Failed to populate ordered list object type attributes\n");
> +
> +	ret = hp_init_bios_attributes(HPWMI_PASSWORD_TYPE, HP_WMI_BIOS_PASSWORD_GUID);
> +	if (ret)
> +		pr_debug("Failed to populate password object type attributes\n");
> +
> +	bioscfg_drv.spm_data.attr_name_kobj = NULL;
> +	ret = hp_add_other_attributes(HPWMI_SECURE_PLATFORM_TYPE);
> +	if (ret)
> +		pr_debug("Failed to populate secure platform object type attribute\n");
> +
> +	bioscfg_drv.sure_start_attr_kobj = NULL;
> +	ret = hp_add_other_attributes(HPWMI_SURE_START_TYPE);
> +	if (ret)
> +		pr_debug("Failed to populate sure start object type attribute\n");
> +
> +	return 0;
> +
> +err_release_attributes_data:
> +	release_attributes_data();
> +
> +err_destroy_classdev:
> +	device_destroy(fw_attr_class, MKDEV(0, 0));
> +
> +err_unregister_class:
> +	fw_attributes_class_put();
> +	exit_hp_attr_set_interface();
> +
> +	return ret;
> +}
> +
> +static void __exit hp_exit(void)
> +{
> +	release_attributes_data();
> +	device_destroy(fw_attr_class, MKDEV(0, 0));
> +
> +	fw_attributes_class_put();
> +	exit_hp_attr_set_interface();
> +}
> +
> +module_init(hp_init);
> +module_exit(hp_exit);
> 

-- 
 i.