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package efi
// Top level API for goefi
import (
"encoding/binary"
"fmt"
"io"
"os"
"github.com/foxboron/go-uefi/efi/attributes"
"github.com/foxboron/go-uefi/efi/device"
"github.com/foxboron/go-uefi/efi/signature"
"github.com/foxboron/go-uefi/efi/util"
"github.com/pkg/errors"
)
// Keeps track of expected attributes for each variable
var ValidAttributes = map[string]attributes.Attributes{
"SetupMode": attributes.EFI_VARIABLE_NON_VOLATILE |
attributes.EFI_VARIABLE_BOOTSERVICE_ACCESS,
"PK": attributes.EFI_VARIABLE_NON_VOLATILE |
attributes.EFI_VARIABLE_BOOTSERVICE_ACCESS |
attributes.EFI_VARIABLE_RUNTIME_ACCESS |
attributes.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS,
"KEK": attributes.EFI_VARIABLE_NON_VOLATILE |
attributes.EFI_VARIABLE_BOOTSERVICE_ACCESS |
attributes.EFI_VARIABLE_RUNTIME_ACCESS |
attributes.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS,
"db": attributes.EFI_VARIABLE_NON_VOLATILE |
attributes.EFI_VARIABLE_BOOTSERVICE_ACCESS |
attributes.EFI_VARIABLE_RUNTIME_ACCESS |
attributes.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS,
"dbx": attributes.EFI_VARIABLE_NON_VOLATILE |
attributes.EFI_VARIABLE_BOOTSERVICE_ACCESS |
attributes.EFI_VARIABLE_RUNTIME_ACCESS |
attributes.EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS,
}
func GetBootOrder() []string {
ret := []string{}
_, data, _ := attributes.ReadEfivars("BootOrder")
for i := 0; i < data.Len(); i += 2 {
b := make([]byte, 2)
data.Read(b)
val := binary.BigEndian.Uint16([]byte{b[1], b[0]})
ret = append(ret, fmt.Sprintf("Boot%04x\n", val))
}
return ret
}
func GetBootEntry(entry string) (*device.EFILoadOption, error) {
_, f, _ := attributes.ReadEfivars(entry)
loadOption, err := device.ParseEFILoadOption(f)
if err != nil {
return nil, err
}
loadOption.FilePath, err = device.ParseDevicePath(f)
if err != nil {
return nil, err
}
return loadOption, nil
}
// GetSetupMode returns if setup mode has been enabled on the machine.
func GetSetupMode() bool {
if _, data, err := attributes.ReadEfivars("SetupMode"); err == nil {
b, _ := data.ReadByte()
if b == 1 {
return true
}
}
return false
}
// GetSecureBoot returns if secure boot has been enabled on the machine.
func GetSecureBoot() bool {
if _, data, err := attributes.ReadEfivars("SecureBoot"); err == nil {
b, _ := data.ReadByte()
if b == 1 {
return true
}
}
return false
}
func GetPK() (*signature.SignatureDatabase, error) {
efivar := "PK"
attributes, data, err := attributes.ReadEfivars(efivar)
if err != nil {
if errors.Is(err, io.EOF) || os.IsNotExist(err) {
return &signature.SignatureDatabase{}, nil
}
return &signature.SignatureDatabase{}, err
}
if (ValidAttributes[efivar] & attributes) != ValidAttributes[efivar] {
return nil, fmt.Errorf("invalid bitmask")
}
siglist, err := signature.ReadSignatureDatabase(data)
if err != nil {
return nil, errors.Wrapf(err, "can't parse Platform Key")
}
return &siglist, nil
}
func GetKEK() (*signature.SignatureDatabase, error) {
efivar := "KEK"
attr, data, err := attributes.ReadEfivars(efivar)
if err != nil {
if errors.Is(err, io.EOF) || os.IsNotExist(err) {
return &signature.SignatureDatabase{}, nil
}
return &signature.SignatureDatabase{}, err
}
if (ValidAttributes[efivar] & attr) != ValidAttributes[efivar] {
return nil, fmt.Errorf("invalid bitmask")
}
siglist, err := signature.ReadSignatureDatabase(data)
if err != nil {
return nil, errors.Wrapf(err, "can't parse Key Exchange key")
}
return &siglist, nil
}
func Getdb() (*signature.SignatureDatabase, error) {
efivar := "db"
attr, data, err := attributes.ReadEfivars(efivar)
if err != nil {
if errors.Is(err, io.EOF) || os.IsNotExist(err) {
return &signature.SignatureDatabase{}, nil
}
return &signature.SignatureDatabase{}, err
}
if (ValidAttributes[efivar] & attr) != ValidAttributes[efivar] {
return nil, fmt.Errorf("invalid bitmask")
}
siglist, err := signature.ReadSignatureDatabase(data)
if err != nil {
return nil, errors.Wrapf(err, "can't parse database key")
}
return &siglist, nil
}
func Getdbx() (*signature.SignatureDatabase, error) {
efivar := "dbx"
attr, data, err := attributes.ReadEfivars(efivar)
if err != nil {
if errors.Is(err, io.EOF) || os.IsNotExist(err) {
return &signature.SignatureDatabase{}, nil
}
return &signature.SignatureDatabase{}, err
}
if (ValidAttributes[efivar] & attr) != ValidAttributes[efivar] {
return nil, fmt.Errorf("invalid bitmask")
}
siglist, err := signature.ReadSignatureDatabase(data)
if err != nil {
return nil, errors.Wrapf(err, "can't parse forbidden database key")
}
return &siglist, nil
}
func WriteEFIVariable(variable string, buf []byte) error {
attrs := ValidAttributes[variable]
if err := attributes.WriteEfivars(variable, attrs, buf); err != nil {
return err
}
return nil
}
// Return the boot entry which is currently booted.
func GetCurrentlyBootedEntry() (string, error) {
_, data, err := attributes.ReadEfivarsWithGuid(
"LoaderEntrySelected",
*util.StringToGUID("4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"),
)
if err != nil {
return "", err
}
name, err := util.ParseUtf16Var(data)
if err != nil {
return "", err
}
return name, nil
}
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