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// SPDX-License-Identifier: GPL-2.0+
/*
* File interface for UEFI variables
*
* Copyright (c) 2020, Heinrich Schuchardt
*/
#define LOG_CATEGORY LOGC_EFI
#include <charset.h>
#include <fs.h>
#include <log.h>
#include <malloc.h>
#include <mapmem.h>
#include <efi_loader.h>
#include <efi_variable.h>
#define PART_STR_LEN 10
/**
* efi_set_blk_dev_to_system_partition() - select EFI system partition
*
* Set the EFI system partition as current block device.
*
* Return: status code
*/
static efi_status_t __maybe_unused efi_set_blk_dev_to_system_partition(void)
{
char part_str[PART_STR_LEN];
int r;
if (efi_system_partition.uclass_id == UCLASS_INVALID)
return EFI_DEVICE_ERROR;
snprintf(part_str, PART_STR_LEN, "%x:%x",
efi_system_partition.devnum, efi_system_partition.part);
r = fs_set_blk_dev(blk_get_uclass_name(efi_system_partition.uclass_id),
part_str, FS_TYPE_ANY);
if (r)
return EFI_DEVICE_ERROR;
return EFI_SUCCESS;
}
/**
* efi_var_to_storage() - save non-volatile variables as file
*
* File ubootefi.var is created on the EFI system partion.
*
* Return: status code
*/
efi_status_t efi_var_to_storage(void)
{
efi_status_t ret;
struct efi_var_file *buf;
loff_t len;
loff_t actlen;
int r;
static bool once;
ret = efi_var_collect(&buf, &len, EFI_VARIABLE_NON_VOLATILE);
if (ret != EFI_SUCCESS)
goto error;
ret = efi_set_blk_dev_to_system_partition();
if (ret != EFI_SUCCESS) {
if (!once) {
log_warning("Cannot persist EFI variables without system partition\n");
once = true;
}
goto out;
}
once = false;
r = fs_write(EFI_VAR_FILE_NAME, map_to_sysmem(buf), 0, len, &actlen);
if (r || len != actlen)
ret = EFI_DEVICE_ERROR;
error:
if (ret != EFI_SUCCESS)
log_err("Failed to persist EFI variables\n");
out:
free(buf);
return ret;
}
/**
* efi_var_from_storage() - read variables from file
*
* File ubootefi.var is read from the EFI system partitions and the variables
* stored in the file are created.
*
* On first boot the file ubootefi.var does not exist yet. This is why we must
* return EFI_SUCCESS in this case.
*
* If the variable file is corrupted, e.g. incorrect CRC32, we do not want to
* stop the boot process. We deliberately return EFI_SUCCESS in this case, too.
*
* Return: status code
*/
efi_status_t efi_var_from_storage(void)
{
struct efi_var_file *buf;
loff_t len;
efi_status_t ret;
int r;
buf = calloc(1, EFI_VAR_BUF_SIZE);
if (!buf) {
log_err("Out of memory\n");
return EFI_OUT_OF_RESOURCES;
}
ret = efi_set_blk_dev_to_system_partition();
if (ret != EFI_SUCCESS)
goto error;
r = fs_read(EFI_VAR_FILE_NAME, map_to_sysmem(buf), 0, EFI_VAR_BUF_SIZE,
&len);
if (r || len < sizeof(struct efi_var_file)) {
log_info("No EFI variables loaded\n");
goto error;
}
if (buf->length != len || efi_var_restore(buf, false) != EFI_SUCCESS)
log_err("Invalid EFI variables file\n");
error:
free(buf);
return EFI_SUCCESS;
}
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