1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * efibc: control EFI bootloaders which obey LoaderEntryOneShot var 4 * Copyright (c) 2013-2016, Intel Corporation. 5 */ 6 7 #define pr_fmt(fmt) "efibc: " fmt 8 9 #include <linux/efi.h> 10 #include <linux/module.h> 11 #include <linux/reboot.h> 12 #include <linux/slab.h> 13 14 static void efibc_str_to_str16(const char *str, efi_char16_t *str16) 15 { 16 size_t i; 17 18 for (i = 0; i < strlen(str); i++) 19 str16[i] = str[i]; 20 21 str16[i] = '\0'; 22 } 23 24 static int efibc_set_variable(const char *name, const char *value) 25 { 26 int ret; 27 efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID; 28 struct efivar_entry *entry; 29 size_t size = (strlen(value) + 1) * sizeof(efi_char16_t); 30 31 if (size > sizeof(entry->var.Data)) { 32 pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name); 33 return -EINVAL; 34 } 35 36 entry = kmalloc(sizeof(*entry), GFP_KERNEL); 37 if (!entry) { 38 pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name); 39 return -ENOMEM; 40 } 41 42 efibc_str_to_str16(name, entry->var.VariableName); 43 efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data); 44 memcpy(&entry->var.VendorGuid, &guid, sizeof(guid)); 45 46 ret = efivar_entry_set_safe(entry->var.VariableName, 47 entry->var.VendorGuid, 48 EFI_VARIABLE_NON_VOLATILE 49 | EFI_VARIABLE_BOOTSERVICE_ACCESS 50 | EFI_VARIABLE_RUNTIME_ACCESS, 51 false, size, entry->var.Data); 52 53 if (ret) 54 pr_err("failed to set %s EFI variable: 0x%x\n", 55 name, ret); 56 57 kfree(entry); 58 return ret; 59 } 60 61 static int efibc_reboot_notifier_call(struct notifier_block *notifier, 62 unsigned long event, void *data) 63 { 64 const char *reason = "shutdown"; 65 int ret; 66 67 if (event == SYS_RESTART) 68 reason = "reboot"; 69 70 ret = efibc_set_variable("LoaderEntryRebootReason", reason); 71 if (ret || !data) 72 return NOTIFY_DONE; 73 74 efibc_set_variable("LoaderEntryOneShot", (char *)data); 75 76 return NOTIFY_DONE; 77 } 78 79 static struct notifier_block efibc_reboot_notifier = { 80 .notifier_call = efibc_reboot_notifier_call, 81 }; 82 83 static int __init efibc_init(void) 84 { 85 int ret; 86 87 if (!efi_enabled(EFI_RUNTIME_SERVICES)) 88 return -ENODEV; 89 90 ret = register_reboot_notifier(&efibc_reboot_notifier); 91 if (ret) 92 pr_err("unable to register reboot notifier\n"); 93 94 return ret; 95 } 96 module_init(efibc_init); 97 98 static void __exit efibc_exit(void) 99 { 100 unregister_reboot_notifier(&efibc_reboot_notifier); 101 } 102 module_exit(efibc_exit); 103 104 MODULE_AUTHOR("Jeremy Compostella <jeremy.compostella@intel.com>"); 105 MODULE_AUTHOR("Matt Gumbel <matthew.k.gumbel@intel.com"); 106 MODULE_DESCRIPTION("EFI Bootloader Control"); 107 MODULE_LICENSE("GPL v2"); 108