drivers/firmware/efi/efivars.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Originally from efivars.c,
  *
  * Copyright (C) 2001,2003,2004 Dell <[email protected]>
  * Copyright (C) 2004 Intel Corporation <[email protected]>
  *
  * This code takes all variables accessible from EFI runtime and
  *  exports them via sysfs
  */

 #include <linux/efi.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/ucs2_string.h>
 #include <linux/compat.h>

 #define EFIVARS_VERSION "0.08"
 #define EFIVARS_DATE "2004-May-17"

 MODULE_AUTHOR("Matt Domsch <[email protected]>");
 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
 MODULE_LICENSE("GPL");
 MODULE_VERSION(EFIVARS_VERSION);
 MODULE_ALIAS("platform:efivars");

 LIST_HEAD(efivar_sysfs_list);
 EXPORT_SYMBOL_GPL(efivar_sysfs_list);

 static struct kset *efivars_kset;

 static struct bin_attribute *efivars_new_var;
 static struct bin_attribute *efivars_del_var;

 struct compat_efi_variable {
 	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
 	efi_guid_t    VendorGuid;
 	__u32         DataSize;
 	__u8          Data[1024];
 	__u32         Status;
 	__u32         Attributes;
 } __packed;

 struct efivar_attribute {
 	struct attribute attr;
 	ssize_t (*show) (struct efivar_entry *entry, char *buf);
 	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
 };

 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
 struct efivar_attribute efivar_attr_##_name = { \
 	.attr = {.name = __stringify(_name), .mode = _mode}, \
 	.show = _show, \
 	.store = _store, \
 };

 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
 #define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

 /*
  * Prototype for sysfs creation function
  */
 static int
 efivar_create_sysfs_entry(struct efivar_entry *new_var);

 static ssize_t
 efivar_guid_read(struct efivar_entry *entry, char *buf)
 {
 	struct efi_variable *var = &entry->var;
 	char *str = buf;

 	if (!entry || !buf)
 		return 0;

 	efi_guid_to_str(&var->VendorGuid, str);
 	str += strlen(str);
 	str += sprintf(str, "\n");

 	return str - buf;
 }

 static ssize_t
 efivar_attr_read(struct efivar_entry *entry, char *buf)
 {
 	struct efi_variable *var = &entry->var;
 	char *str = buf;

 	if (!entry || !buf)
 		return -EINVAL;

 	var->DataSize = 1024;
 	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
 		return -EIO;

 	if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
 		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
 	if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
 		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
 	if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
 		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
 	if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
 		str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
 	if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
 		str += sprintf(str,
 			"EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
 	if (var->Attributes &
 			EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
 		str += sprintf(str,
 			"EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
 	if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
 		str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
 	return str - buf;
 }

 static ssize_t
 efivar_size_read(struct efivar_entry *entry, char *buf)
 {
 	struct efi_variable *var = &entry->var;
 	char *str = buf;

 	if (!entry || !buf)
 		return -EINVAL;

 	var->DataSize = 1024;
 	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
 		return -EIO;

 	str += sprintf(str, "0x%lx\n", var->DataSize);
 	return str - buf;
 }

 static ssize_t
 efivar_data_read(struct efivar_entry *entry, char *buf)
 {
 	struct efi_variable *var = &entry->var;

 	if (!entry || !buf)
 		return -EINVAL;

 	var->DataSize = 1024;
 	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
 		return -EIO;

 	memcpy(buf, var->Data, var->DataSize);
 	return var->DataSize;
 }

 static inline int
 sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
 	     unsigned long size, u32 attributes, u8 *data)
 {
 	/*
 	 * If only updating the variable data, then the name
 	 * and guid should remain the same
 	 */
 	if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
 		efi_guidcmp(vendor, var->VendorGuid)) {
 		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
 		return -EINVAL;
 	}

 	if ((size <= 0) || (attributes == 0)){
 		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
 		return -EINVAL;
 	}

 	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
 	    efivar_validate(vendor, name, data, size) == false) {
 		printk(KERN_ERR "efivars: Malformed variable content\n");
 		return -EINVAL;
 	}

 	return 0;
 }

 static void
 copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
 {
 	memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
 	memcpy(dst->Data, src->Data, sizeof(src->Data));

 	dst->VendorGuid = src->VendorGuid;
 	dst->DataSize = src->DataSize;
 	dst->Attributes = src->Attributes;
 }

 /*
  * We allow each variable to be edited via rewriting the
  * entire efi variable structure.
  */
 static ssize_t
 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 {
 	struct efi_variable *new_var, *var = &entry->var;
 	efi_char16_t *name;
 	unsigned long size;
 	efi_guid_t vendor;
 	u32 attributes;
 	u8 *data;
 	int err;

 	if (in_compat_syscall()) {
 		struct compat_efi_variable *compat;

 		if (count != sizeof(*compat))
 			return -EINVAL;

 		compat = (struct compat_efi_variable *)buf;
 		attributes = compat->Attributes;
 		vendor = compat->VendorGuid;
 		name = compat->VariableName;
 		size = compat->DataSize;
 		data = compat->Data;

 		err = sanity_check(var, name, vendor, size, attributes, data);
 		if (err)
 			return err;

 		copy_out_compat(&entry->var, compat);
 	} else {
 		if (count != sizeof(struct efi_variable))
 			return -EINVAL;

 		new_var = (struct efi_variable *)buf;

 		attributes = new_var->Attributes;
 		vendor = new_var->VendorGuid;
 		name = new_var->VariableName;
 		size = new_var->DataSize;
 		data = new_var->Data;

 		err = sanity_check(var, name, vendor, size, attributes, data);
 		if (err)
 			return err;

 		memcpy(&entry->var, new_var, count);
 	}

 	err = efivar_entry_set(entry, attributes, size, data, NULL);
 	if (err) {
 		printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
 		return -EIO;
 	}

 	return count;
 }

 static ssize_t
 efivar_show_raw(struct efivar_entry *entry, char *buf)
 {
 	struct efi_variable *var = &entry->var;
 	struct compat_efi_variable *compat;
 	size_t size;

 	if (!entry || !buf)
 		return 0;

 	var->DataSize = 1024;
 	if (efivar_entry_get(entry, &entry->var.Attributes,
 			     &entry->var.DataSize, entry->var.Data))
 		return -EIO;

 	if (in_compat_syscall()) {
 		compat = (struct compat_efi_variable *)buf;

 		size = sizeof(*compat);
 		memcpy(compat->VariableName, var->VariableName,
 			EFI_VAR_NAME_LEN);
 		memcpy(compat->Data, var->Data, sizeof(compat->Data));

 		compat->VendorGuid = var->VendorGuid;
 		compat->DataSize = var->DataSize;
 		compat->Attributes = var->Attributes;
 	} else {
 		size = sizeof(*var);
 		memcpy(buf, var, size);
 	}

 	return size;
 }

 /*
  * Generic read/write functions that call the specific functions of
  * the attributes...
  */
 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
 				char *buf)
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 	ssize_t ret = -EIO;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	if (efivar_attr->show) {
 		ret = efivar_attr->show(var, buf);
 	}
 	return ret;
 }

 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
 				const char *buf, size_t count)
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 	ssize_t ret = -EIO;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	if (efivar_attr->store)
 		ret = efivar_attr->store(var, buf, count);

 	return ret;
 }

 static const struct sysfs_ops efivar_attr_ops = {
 	.show = efivar_attr_show,
 	.store = efivar_attr_store,
 };

 static void efivar_release(struct kobject *kobj)
 {
 	struct efivar_entry *var = to_efivar_entry(kobj);
 	kfree(var);
 }

 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

 static struct attribute *def_attrs[] = {
 	&efivar_attr_guid.attr,
 	&efivar_attr_size.attr,
 	&efivar_attr_attributes.attr,
 	&efivar_attr_data.attr,
 	&efivar_attr_raw_var.attr,
 	NULL,
 };

 static struct kobj_type efivar_ktype = {
 	.release = efivar_release,
 	.sysfs_ops = &efivar_attr_ops,
 	.default_attrs = def_attrs,
 };

 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 			     struct bin_attribute *bin_attr,
 			     char *buf, loff_t pos, size_t count)
 {
 	struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
 	struct efi_variable *new_var = (struct efi_variable *)buf;
 	struct efivar_entry *new_entry;
 	bool need_compat = in_compat_syscall();
 	efi_char16_t *name;
 	unsigned long size;
 	u32 attributes;
 	u8 *data;
 	int err;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	if (need_compat) {
 		if (count != sizeof(*compat))
 			return -EINVAL;

 		attributes = compat->Attributes;
 		name = compat->VariableName;
 		size = compat->DataSize;
 		data = compat->Data;
 	} else {
 		if (count != sizeof(*new_var))
 			return -EINVAL;

 		attributes = new_var->Attributes;
 		name = new_var->VariableName;
 		size = new_var->DataSize;
 		data = new_var->Data;
 	}

 	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
 	    efivar_validate(new_var->VendorGuid, name, data,
 			    size) == false) {
 		printk(KERN_ERR "efivars: Malformed variable content\n");
 		return -EINVAL;
 	}

 	new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
 	if (!new_entry)
 		return -ENOMEM;

 	if (need_compat)
 		copy_out_compat(&new_entry->var, compat);
 	else
 		memcpy(&new_entry->var, new_var, sizeof(*new_var));

 	err = efivar_entry_set(new_entry, attributes, size,
 			       data, &efivar_sysfs_list);
 	if (err) {
 		if (err == -EEXIST)
 			err = -EINVAL;
 		goto out;
 	}

 	if (efivar_create_sysfs_entry(new_entry)) {
 		printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
 		kfree(new_entry);
 	}
 	return count;

 out:
 	kfree(new_entry);
 	return err;
 }

 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 			     struct bin_attribute *bin_attr,
 			     char *buf, loff_t pos, size_t count)
 {
 	struct efi_variable *del_var = (struct efi_variable *)buf;
 	struct compat_efi_variable *compat;
 	struct efivar_entry *entry;
 	efi_char16_t *name;
 	efi_guid_t vendor;
 	int err = 0;

 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;

 	if (in_compat_syscall()) {
 		if (count != sizeof(*compat))
 			return -EINVAL;

 		compat = (struct compat_efi_variable *)buf;
 		name = compat->VariableName;
 		vendor = compat->VendorGuid;
 	} else {
 		if (count != sizeof(*del_var))
 			return -EINVAL;

 		name = del_var->VariableName;
 		vendor = del_var->VendorGuid;
 	}

 	if (efivar_entry_iter_begin())
 		return -EINTR;
 	entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
 	if (!entry)
 		err = -EINVAL;
 	else if (__efivar_entry_delete(entry))
 		err = -EIO;

 	if (err) {
 		efivar_entry_iter_end();
 		return err;
 	}

 	if (!entry->scanning) {
 		efivar_entry_iter_end();
 		efivar_unregister(entry);
 	} else
 		efivar_entry_iter_end();

 	/* It's dead Jim.... */
 	return count;
 }

 /**
  * efivar_create_sysfs_entry - create a new entry in sysfs
  * @new_var: efivar entry to create
  *
  * Returns 0 on success, negative error code on failure
  */
 static int
 efivar_create_sysfs_entry(struct efivar_entry *new_var)
 {
 	int short_name_size;
 	char *short_name;
 	unsigned long utf8_name_size;
 	efi_char16_t *variable_name = new_var->var.VariableName;
 	int ret;

 	/*
 	 * Length of the variable bytes in UTF8, plus the '-' separator,
 	 * plus the GUID, plus trailing NUL
 	 */
 	utf8_name_size = ucs2_utf8size(variable_name);
 	short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;

 	short_name = kmalloc(short_name_size, GFP_KERNEL);
 	if (!short_name)
 		return -ENOMEM;

 	ucs2_as_utf8(short_name, variable_name, short_name_size);

 	/* This is ugly, but necessary to separate one vendor's
 	   private variables from another's.         */
 	short_name[utf8_name_size] = '-';
 	efi_guid_to_str(&new_var->var.VendorGuid,
 			 short_name + utf8_name_size + 1);

 	new_var->kobj.kset = efivars_kset;

 	ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
 				   NULL, "%s", short_name);
 	kfree(short_name);
 	if (ret)
 		return ret;

 	kobject_uevent(&new_var->kobj, KOBJ_ADD);
 	if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
 		efivar_unregister(new_var);
 		return -EINTR;
 	}

 	return 0;
 }

 static int
 create_efivars_bin_attributes(void)
 {
 	struct bin_attribute *attr;
 	int error;

 	/* new_var */
 	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 	if (!attr)
 		return -ENOMEM;

 	attr->attr.name = "new_var";
 	attr->attr.mode = 0200;
 	attr->write = efivar_create;
 	efivars_new_var = attr;

 	/* del_var */
 	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 	if (!attr) {
 		error = -ENOMEM;
 		goto out_free;
 	}
 	attr->attr.name = "del_var";
 	attr->attr.mode = 0200;
 	attr->write = efivar_delete;
 	efivars_del_var = attr;

 	sysfs_bin_attr_init(efivars_new_var);
 	sysfs_bin_attr_init(efivars_del_var);

 	/* Register */
 	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
 	if (error) {
 		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
 			" due to error %d\n", error);
 		goto out_free;
 	}

 	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
 	if (error) {
 		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
 			" due to error %d\n", error);
 		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
 		goto out_free;
 	}

 	return 0;
 out_free:
 	kfree(efivars_del_var);
 	efivars_del_var = NULL;
 	kfree(efivars_new_var);
 	efivars_new_var = NULL;
 	return error;
 }

 static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
 				     unsigned long name_size, void *data)
 {
 	struct efivar_entry *entry = data;

 	if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
 		return 0;

 	memcpy(entry->var.VariableName, name, name_size);
 	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

 	return 1;
 }

 static void efivar_update_sysfs_entries(struct work_struct *work)
 {
 	struct efivar_entry *entry;
 	int err;

 	/* Add new sysfs entries */
 	while (1) {
 		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 		if (!entry)
 			return;

 		err = efivar_init(efivar_update_sysfs_entry, entry,
 				  false, &efivar_sysfs_list);
 		if (!err)
 			break;

 		efivar_create_sysfs_entry(entry);
 	}

 	kfree(entry);
 }

 static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
 				  unsigned long name_size, void *data)
 {
 	struct efivar_entry *entry;

 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry)
 		return -ENOMEM;

 	memcpy(entry->var.VariableName, name, name_size);
 	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

 	efivar_create_sysfs_entry(entry);

 	return 0;
 }

 static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
 {
 	int err = efivar_entry_remove(entry);

 	if (err)
 		return err;
 	efivar_unregister(entry);
 	return 0;
 }

 static void efivars_sysfs_exit(void)
 {
 	/* Remove all entries and destroy */
 	int err;

 	err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
 				  NULL, NULL);
 	if (err) {
 		pr_err("efivars: Failed to destroy sysfs entries\n");
 		return;
 	}

 	if (efivars_new_var)
 		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
 	if (efivars_del_var)
 		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
 	kfree(efivars_new_var);
 	kfree(efivars_del_var);
 	kset_unregister(efivars_kset);
 }

 int efivars_sysfs_init(void)
 {
 	struct kobject *parent_kobj = efivars_kobject();
 	int error = 0;

 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
 		return -ENODEV;

 	/* No efivars has been registered yet */
 	if (!parent_kobj)
 		return 0;

 	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
 	       EFIVARS_DATE);

 	efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
 	if (!efivars_kset) {
 		printk(KERN_ERR "efivars: Subsystem registration failed.\n");
 		return -ENOMEM;
 	}

 	efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list);

 	error = create_efivars_bin_attributes();
 	if (error) {
 		efivars_sysfs_exit();
 		return error;
 	}

 	INIT_WORK(&efivar_work, efivar_update_sysfs_entries);

 	return 0;
 }
 EXPORT_SYMBOL_GPL(efivars_sysfs_init);

 module_init(efivars_sysfs_init);
 module_exit(efivars_sysfs_exit);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Originally from efivars.c,
	*
	* Copyright (C) 2001,2003,2004 Dell <[email protected]>
	* Copyright (C) 2004 Intel Corporation <[email protected]>
	*
	* This code takes all variables accessible from EFI runtime and
	* exports them via sysfs
	*/

	#include <linux/efi.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/ucs2_string.h>
	#include <linux/compat.h>

	#define EFIVARS_VERSION "0.08"
	#define EFIVARS_DATE "2004-May-17"

	MODULE_AUTHOR("Matt Domsch <[email protected]>");
	MODULE_DESCRIPTION("sysfs interface to EFI Variables");
	MODULE_LICENSE("GPL");
	MODULE_VERSION(EFIVARS_VERSION);
	MODULE_ALIAS("platform:efivars");

	LIST_HEAD(efivar_sysfs_list);
	EXPORT_SYMBOL_GPL(efivar_sysfs_list);

	static struct kset *efivars_kset;

	static struct bin_attribute *efivars_new_var;
	static struct bin_attribute *efivars_del_var;

	struct compat_efi_variable {
	efi_char16_t VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
	efi_guid_t VendorGuid;
	__u32 DataSize;
	__u8 Data[1024];
	__u32 Status;
	__u32 Attributes;
	} __packed;

	struct efivar_attribute {
	struct attribute attr;
	ssize_t (show) (struct efivar_entry entry, char *buf);
	ssize_t (store)(struct efivar_entry entry, const char *buf, size_t count);
	};

	#define EFIVAR_ATTR(_name, _mode, _show, _store) \
	struct efivar_attribute efivar_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode}, \
	.show = _show, \
	.store = _store, \
	};

	#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
	#define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)

	/*
	* Prototype for sysfs creation function
	*/
	static int
	efivar_create_sysfs_entry(struct efivar_entry *new_var);

	static ssize_t
	efivar_guid_read(struct efivar_entry entry, char buf)
	{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry \|\| !buf)
	return 0;

	efi_guid_to_str(&var->VendorGuid, str);
	str += strlen(str);
	str += sprintf(str, "\n");

	return str - buf;
	}

	static ssize_t
	efivar_attr_read(struct efivar_entry entry, char buf)
	{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry \|\| !buf)
	return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
	return -EIO;

	if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
	str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
	if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
	str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
	str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
	str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
	if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
	str += sprintf(str,
	"EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
	if (var->Attributes &
	EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
	str += sprintf(str,
	"EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
	str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
	return str - buf;
	}

	static ssize_t
	efivar_size_read(struct efivar_entry entry, char buf)
	{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry \|\| !buf)
	return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
	return -EIO;

	str += sprintf(str, "0x%lx\n", var->DataSize);
	return str - buf;
	}

	static ssize_t
	efivar_data_read(struct efivar_entry entry, char buf)
	{
	struct efi_variable *var = &entry->var;

	if (!entry \|\| !buf)
	return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
	return -EIO;

	memcpy(buf, var->Data, var->DataSize);
	return var->DataSize;
	}

	static inline int
	sanity_check(struct efi_variable var, efi_char16_t name, efi_guid_t vendor,
	unsigned long size, u32 attributes, u8 *data)
	{
	/*
	* If only updating the variable data, then the name
	* and guid should remain the same
	*/
	if (memcmp(name, var->VariableName, sizeof(var->VariableName)) \|\|
	efi_guidcmp(vendor, var->VendorGuid)) {
	printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
	return -EINVAL;
	}

	if ((size <= 0) \|\| (attributes == 0)){
	printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
	return -EINVAL;
	}

	if ((attributes & ~EFI_VARIABLE_MASK) != 0 \|\|
	efivar_validate(vendor, name, data, size) == false) {
	printk(KERN_ERR "efivars: Malformed variable content\n");
	return -EINVAL;
	}

	return 0;
	}

	static void
	copy_out_compat(struct efi_variable dst, struct compat_efi_variable src)
	{
	memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
	memcpy(dst->Data, src->Data, sizeof(src->Data));

	dst->VendorGuid = src->VendorGuid;
	dst->DataSize = src->DataSize;
	dst->Attributes = src->Attributes;
	}

	/*
	* We allow each variable to be edited via rewriting the
	* entire efi variable structure.
	*/
	static ssize_t
	efivar_store_raw(struct efivar_entry entry, const char buf, size_t count)
	{
	struct efi_variable new_var, var = &entry->var;
	efi_char16_t *name;
	unsigned long size;
	efi_guid_t vendor;
	u32 attributes;
	u8 *data;
	int err;

	if (in_compat_syscall()) {
	struct compat_efi_variable *compat;

	if (count != sizeof(*compat))
	return -EINVAL;

	compat = (struct compat_efi_variable *)buf;
	attributes = compat->Attributes;
	vendor = compat->VendorGuid;
	name = compat->VariableName;
	size = compat->DataSize;
	data = compat->Data;

	err = sanity_check(var, name, vendor, size, attributes, data);
	if (err)
	return err;

	copy_out_compat(&entry->var, compat);
	} else {
	if (count != sizeof(struct efi_variable))
	return -EINVAL;

	new_var = (struct efi_variable *)buf;

	attributes = new_var->Attributes;
	vendor = new_var->VendorGuid;
	name = new_var->VariableName;
	size = new_var->DataSize;
	data = new_var->Data;

	err = sanity_check(var, name, vendor, size, attributes, data);
	if (err)
	return err;

	memcpy(&entry->var, new_var, count);
	}

	err = efivar_entry_set(entry, attributes, size, data, NULL);
	if (err) {
	printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
	return -EIO;
	}

	return count;
	}

	static ssize_t
	efivar_show_raw(struct efivar_entry entry, char buf)
	{
	struct efi_variable *var = &entry->var;
	struct compat_efi_variable *compat;
	size_t size;

	if (!entry \|\| !buf)
	return 0;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &entry->var.Attributes,
	&entry->var.DataSize, entry->var.Data))
	return -EIO;

	if (in_compat_syscall()) {
	compat = (struct compat_efi_variable *)buf;

	size = sizeof(*compat);
	memcpy(compat->VariableName, var->VariableName,
	EFI_VAR_NAME_LEN);
	memcpy(compat->Data, var->Data, sizeof(compat->Data));

	compat->VendorGuid = var->VendorGuid;
	compat->DataSize = var->DataSize;
	compat->Attributes = var->Attributes;
	} else {
	size = sizeof(*var);
	memcpy(buf, var, size);
	}

	return size;
	}

	/*
	* Generic read/write functions that call the specific functions of
	* the attributes...
	*/
	static ssize_t efivar_attr_show(struct kobject kobj, struct attribute attr,
	char *buf)
	{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	if (efivar_attr->show) {
	ret = efivar_attr->show(var, buf);
	}
	return ret;
	}

	static ssize_t efivar_attr_store(struct kobject kobj, struct attribute attr,
	const char *buf, size_t count)
	{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	if (efivar_attr->store)
	ret = efivar_attr->store(var, buf, count);

	return ret;
	}

	static const struct sysfs_ops efivar_attr_ops = {
	.show = efivar_attr_show,
	.store = efivar_attr_store,
	};

	static void efivar_release(struct kobject *kobj)
	{
	struct efivar_entry *var = to_efivar_entry(kobj);
	kfree(var);
	}

	static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
	static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
	static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
	static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
	static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

	static struct attribute *def_attrs[] = {
	&efivar_attr_guid.attr,
	&efivar_attr_size.attr,
	&efivar_attr_attributes.attr,
	&efivar_attr_data.attr,
	&efivar_attr_raw_var.attr,
	NULL,
	};

	static struct kobj_type efivar_ktype = {
	.release = efivar_release,
	.sysfs_ops = &efivar_attr_ops,
	.default_attrs = def_attrs,
	};

	static ssize_t efivar_create(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buf, loff_t pos, size_t count)
	{
	struct compat_efi_variable compat = (struct compat_efi_variable )buf;
	struct efi_variable new_var = (struct efi_variable )buf;
	struct efivar_entry *new_entry;
	bool need_compat = in_compat_syscall();
	efi_char16_t *name;
	unsigned long size;
	u32 attributes;
	u8 *data;
	int err;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	if (need_compat) {
	if (count != sizeof(*compat))
	return -EINVAL;

	attributes = compat->Attributes;
	name = compat->VariableName;
	size = compat->DataSize;
	data = compat->Data;
	} else {
	if (count != sizeof(*new_var))
	return -EINVAL;

	attributes = new_var->Attributes;
	name = new_var->VariableName;
	size = new_var->DataSize;
	data = new_var->Data;
	}

	if ((attributes & ~EFI_VARIABLE_MASK) != 0 \|\|
	efivar_validate(new_var->VendorGuid, name, data,
	size) == false) {
	printk(KERN_ERR "efivars: Malformed variable content\n");
	return -EINVAL;
	}

	new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
	if (!new_entry)
	return -ENOMEM;

	if (need_compat)
	copy_out_compat(&new_entry->var, compat);
	else
	memcpy(&new_entry->var, new_var, sizeof(*new_var));

	err = efivar_entry_set(new_entry, attributes, size,
	data, &efivar_sysfs_list);
	if (err) {
	if (err == -EEXIST)
	err = -EINVAL;
	goto out;
	}

	if (efivar_create_sysfs_entry(new_entry)) {
	printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
	kfree(new_entry);
	}
	return count;

	out:
	kfree(new_entry);
	return err;
	}

	static ssize_t efivar_delete(struct file filp, struct kobject kobj,
	struct bin_attribute *bin_attr,
	char *buf, loff_t pos, size_t count)
	{
	struct efi_variable del_var = (struct efi_variable )buf;
	struct compat_efi_variable *compat;
	struct efivar_entry *entry;
	efi_char16_t *name;
	efi_guid_t vendor;
	int err = 0;

	if (!capable(CAP_SYS_ADMIN))
	return -EACCES;

	if (in_compat_syscall()) {
	if (count != sizeof(*compat))
	return -EINVAL;

	compat = (struct compat_efi_variable *)buf;
	name = compat->VariableName;
	vendor = compat->VendorGuid;
	} else {
	if (count != sizeof(*del_var))
	return -EINVAL;

	name = del_var->VariableName;
	vendor = del_var->VendorGuid;
	}

	if (efivar_entry_iter_begin())
	return -EINTR;
	entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
	if (!entry)
	err = -EINVAL;
	else if (__efivar_entry_delete(entry))
	err = -EIO;

	if (err) {
	efivar_entry_iter_end();
	return err;
	}

	if (!entry->scanning) {
	efivar_entry_iter_end();
	efivar_unregister(entry);
	} else
	efivar_entry_iter_end();

	/* It's dead Jim.... */
	return count;
	}

	/**
	* efivar_create_sysfs_entry - create a new entry in sysfs
	* @new_var: efivar entry to create
	*
	* Returns 0 on success, negative error code on failure
	*/
	static int
	efivar_create_sysfs_entry(struct efivar_entry *new_var)
	{
	int short_name_size;
	char *short_name;
	unsigned long utf8_name_size;
	efi_char16_t *variable_name = new_var->var.VariableName;
	int ret;

	/*
	* Length of the variable bytes in UTF8, plus the '-' separator,
	* plus the GUID, plus trailing NUL
	*/
	utf8_name_size = ucs2_utf8size(variable_name);
	short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;

	short_name = kmalloc(short_name_size, GFP_KERNEL);
	if (!short_name)
	return -ENOMEM;

	ucs2_as_utf8(short_name, variable_name, short_name_size);

	/* This is ugly, but necessary to separate one vendor's
	private variables from another's. */
	short_name[utf8_name_size] = '-';
	efi_guid_to_str(&new_var->var.VendorGuid,
	short_name + utf8_name_size + 1);

	new_var->kobj.kset = efivars_kset;

	ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
	NULL, "%s", short_name);
	kfree(short_name);
	if (ret)
	return ret;

	kobject_uevent(&new_var->kobj, KOBJ_ADD);
	if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
	efivar_unregister(new_var);
	return -EINTR;
	}

	return 0;
	}

	static int
	create_efivars_bin_attributes(void)
	{
	struct bin_attribute *attr;
	int error;

	/* new_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr)
	return -ENOMEM;

	attr->attr.name = "new_var";
	attr->attr.mode = 0200;
	attr->write = efivar_create;
	efivars_new_var = attr;

	/* del_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr) {
	error = -ENOMEM;
	goto out_free;
	}
	attr->attr.name = "del_var";
	attr->attr.mode = 0200;
	attr->write = efivar_delete;
	efivars_del_var = attr;

	sysfs_bin_attr_init(efivars_new_var);
	sysfs_bin_attr_init(efivars_del_var);

	/* Register */
	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
	if (error) {
	printk(KERN_ERR "efivars: unable to create new_var sysfs file"
	" due to error %d\n", error);
	goto out_free;
	}

	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
	if (error) {
	printk(KERN_ERR "efivars: unable to create del_var sysfs file"
	" due to error %d\n", error);
	sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
	goto out_free;
	}

	return 0;
	out_free:
	kfree(efivars_del_var);
	efivars_del_var = NULL;
	kfree(efivars_new_var);
	efivars_new_var = NULL;
	return error;
	}

	static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
	unsigned long name_size, void *data)
	{
	struct efivar_entry *entry = data;

	if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
	return 0;

	memcpy(entry->var.VariableName, name, name_size);
	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

	return 1;
	}

	static void efivar_update_sysfs_entries(struct work_struct *work)
	{
	struct efivar_entry *entry;
	int err;

	/* Add new sysfs entries */
	while (1) {
	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
	return;

	err = efivar_init(efivar_update_sysfs_entry, entry,
	false, &efivar_sysfs_list);
	if (!err)
	break;

	efivar_create_sysfs_entry(entry);
	}

	kfree(entry);
	}

	static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
	unsigned long name_size, void *data)
	{
	struct efivar_entry *entry;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
	return -ENOMEM;

	memcpy(entry->var.VariableName, name, name_size);
	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

	efivar_create_sysfs_entry(entry);

	return 0;
	}

	static int efivar_sysfs_destroy(struct efivar_entry entry, void data)
	{
	int err = efivar_entry_remove(entry);

	if (err)
	return err;
	efivar_unregister(entry);
	return 0;
	}

	static void efivars_sysfs_exit(void)
	{
	/* Remove all entries and destroy */
	int err;

	err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
	NULL, NULL);
	if (err) {
	pr_err("efivars: Failed to destroy sysfs entries\n");
	return;
	}

	if (efivars_new_var)
	sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
	if (efivars_del_var)
	sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
	kfree(efivars_new_var);
	kfree(efivars_del_var);
	kset_unregister(efivars_kset);
	}

	int efivars_sysfs_init(void)
	{
	struct kobject *parent_kobj = efivars_kobject();
	int error = 0;

	if (!efi_enabled(EFI_RUNTIME_SERVICES))
	return -ENODEV;

	/* No efivars has been registered yet */
	if (!parent_kobj)
	return 0;

	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
	EFIVARS_DATE);

	efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
	if (!efivars_kset) {
	printk(KERN_ERR "efivars: Subsystem registration failed.\n");
	return -ENOMEM;
	}

	efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list);

	error = create_efivars_bin_attributes();
	if (error) {
	efivars_sysfs_exit();
	return error;
	}

	INIT_WORK(&efivar_work, efivar_update_sysfs_entries);

	return 0;
	}
	EXPORT_SYMBOL_GPL(efivars_sysfs_init);

	module_init(efivars_sysfs_init);
	module_exit(efivars_sysfs_exit);