Avoid abusing the efivar API by passing locally instantiated
efivar_entry structs into efivar_set_entry_safe(), rather than using the
API as intended. Instead, just call efi.set_variable() directly.
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
drivers/firmware/efi/Kconfig | 1 +
drivers/firmware/efi/efibc.c | 76 ++++++++++++++----------------------
2 files changed, 30 insertions(+), 47 deletions(-)
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 7aa4717cdcac..6fd4414c4836 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -145,6 +145,7 @@ config EFI_GENERIC_STUB_INITRD_CMDLINE_LOADER
config EFI_BOOTLOADER_CONTROL
tristate "EFI Bootloader Control"
+ select UCS2_STRING
default n
help
This module installs a reboot hook, such that if reboot() is
diff --git a/drivers/firmware/efi/efibc.c b/drivers/firmware/efi/efibc.c
index 15a47539dc56..8ced7af8e56d 100644
--- a/drivers/firmware/efi/efibc.c
+++ b/drivers/firmware/efi/efibc.c
@@ -10,69 +10,51 @@
#include <linux/module.h>
#include <linux/reboot.h>
#include <linux/slab.h>
+#include <linux/ucs2_string.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';
-}
+#define MAX_DATA_LEN 512
-static int efibc_set_variable(const char *name, const char *value)
+static int efibc_set_variable(efi_char16_t *name, efi_char16_t *value,
+ unsigned long len)
{
- 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);
+ efi_status_t status;
- if (size > sizeof(entry->var.Data)) {
- pr_err("value is too large (%zu bytes) for '%s' EFI variable\n", size, name);
- return -EINVAL;
- }
+ status = efi.set_variable(name, &LINUX_EFI_LOADER_ENTRY_GUID,
+ EFI_VARIABLE_NON_VOLATILE
+ | EFI_VARIABLE_BOOTSERVICE_ACCESS
+ | EFI_VARIABLE_RUNTIME_ACCESS,
+ len * sizeof(efi_char16_t), value);
- entry = kmalloc(sizeof(*entry), GFP_KERNEL);
- if (!entry) {
- pr_err("failed to allocate efivar entry for '%s' EFI variable\n", name);
- return -ENOMEM;
+ if (status != EFI_SUCCESS) {
+ pr_err("failed to set EFI variable: 0x%lx\n", status);
+ return -EIO;
}
-
- 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;
+ return 0;
}
static int efibc_reboot_notifier_call(struct notifier_block *notifier,
unsigned long event, void *data)
{
- const char *reason = "shutdown";
+ efi_char16_t *reason = event == SYS_RESTART ? L"reboot"
+ : L"shutdown";
+ const u8 *str = data;
+ efi_char16_t *wdata;
+ unsigned long l;
int ret;
- if (event == SYS_RESTART)
- reason = "reboot";
-
- ret = efibc_set_variable("LoaderEntryRebootReason", reason);
+ ret = efibc_set_variable(L"LoaderEntryRebootReason", reason,
+ ucs2_strlen(reason));
if (ret || !data)
return NOTIFY_DONE;
- efibc_set_variable("LoaderEntryOneShot", (char *)data);
+ wdata = kmalloc(MAX_DATA_LEN * sizeof(efi_char16_t), GFP_KERNEL);
+ for (l = 0; l < MAX_DATA_LEN - 1 && str[l] != '\0'; l++)
+ wdata[l] = str[l];
+ wdata[l] = L'\0';
+
+ efibc_set_variable(L"LoaderEntryOneShot", wdata, l);
+ kfree(wdata);
return NOTIFY_DONE;
}
@@ -84,7 +66,7 @@ static int __init efibc_init(void)
{
int ret;
- if (!efivars_kobject() || !efivar_supports_writes())
+ if (!efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
return -ENODEV;
ret = register_reboot_notifier(&efibc_reboot_notifier);
--
2.35.1
