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// SPDX-License-Identifier: GPL-2.0
/*
* efibc: control EFI bootloaders which obey LoaderEntryOneShot var
* Copyright (c) 2013-2016, Intel Corporation.
*/
#define pr_fmt(fmt) "efibc: " fmt
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/slab.h>
static void efibc_str_to_str16(const char *str, efi_char16_t *str16)
{
size_t i;
for (i = 0; i < strlen(str); i++)
str16[i] = str[i];
str16[i] = '\0';
}
static int efibc_set_variable(const char *name, const char *value)
{
int ret;
efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
struct efivar_entry *entry;
size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
if (size > sizeof(entry->var.Data)) {
pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
return -EINVAL;
}
entry = kmalloc(sizeof(*entry), GFP_KERNEL);
if (!entry) {
pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
return -ENOMEM;
}
efibc_str_to_str16(name, entry->var.VariableName);
efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
ret = efivar_entry_set_safe(entry->var.VariableName,
entry->var.VendorGuid,
EFI_VARIABLE_NON_VOLATILE
| EFI_VARIABLE_BOOTSERVICE_ACCESS
| EFI_VARIABLE_RUNTIME_ACCESS,
false, size, entry->var.Data);
if (ret)
pr_err("failed to set %s EFI variable: 0x%x\n",
name, ret);
kfree(entry);
return ret;
}
static int efibc_reboot_notifier_call(struct notifier_block *notifier,
unsigned long event, void *data)
{
const char *reason = "shutdown";
int ret;
if (event == SYS_RESTART)
reason = "reboot";
ret = efibc_set_variable("LoaderEntryRebootReason", reason);
if (ret || !data)
return NOTIFY_DONE;
efibc_set_variable("LoaderEntryOneShot", (char *)data);
return NOTIFY_DONE;
}
static struct notifier_block efibc_reboot_notifier = {
.notifier_call = efibc_reboot_notifier_call,
};
static int __init efibc_init(void)
{
int ret;
if (!efivars_kobject() || !efivar_supports_writes())
return -ENODEV;
ret = register_reboot_notifier(&efibc_reboot_notifier);
if (ret)
pr_err("unable to register reboot notifier\n");
return ret;
}
module_init(efibc_init);
static void __exit efibc_exit(void)
{
unregister_reboot_notifier(&efibc_reboot_notifier);
}
module_exit(efibc_exit);
MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>");
MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com");
MODULE_DESCRIPTION("EFI Bootloader Control");
MODULE_LICENSE("GPL v2");
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