efivarfs

Documentation

Overview

Package efivarfs allows interaction with efivarfs of the linux kernel.

Package efivarfs allows interaction with efivarfs of the linux kernel.

Index

• Constants
• Variables
• func RemoveVariable(e EFIVar, desc VariableDescriptor) error
• func SimpleListVariables(e EFIVar) ([]string, error)
• func SimpleRemoveVariable(e EFIVar, v string) error
• func SimpleWriteVariable(e EFIVar, v string, attrs VariableAttributes, data *bytes.Buffer) error
• func WriteVariable(e EFIVar, desc VariableDescriptor, attrs VariableAttributes, data []byte) error
• type EFIVar
• type EFIVarFS
  • func New() (*EFIVarFS, error)
  • func NewPath(p string) (*EFIVarFS, error)
  • func (v *EFIVarFS) Get(desc VariableDescriptor) (VariableAttributes, []byte, error)
  • func (v *EFIVarFS) List() ([]VariableDescriptor, error)
  • func (v *EFIVarFS) Remove(desc VariableDescriptor) error
  • func (v *EFIVarFS) Set(desc VariableDescriptor, attrs VariableAttributes, data []byte) error
• type VariableAttributes
  • func ReadVariable(e EFIVar, desc VariableDescriptor) (VariableAttributes, []byte, error)
  • func SimpleReadVariable(e EFIVar, v string) (VariableAttributes, *bytes.Reader, error)
• type VariableDescriptor
  • func ListVariables(e EFIVar) ([]VariableDescriptor, error)

Constants

const DefaultVarFS = "/sys/firmware/efi/efivars/"

DefaultVarFS is the path to the efivarfs mount point

const FS_IMMUTABLE_FL = 0x10

FS_IMMUTABLE_FL is an inode flag to make a file immutable.

Variables

var (
	// ErrVarsUnavailable is caused by not having a valid backend
	ErrVarsUnavailable = fmt.Errorf("no variable backend is available:%w", os.ErrNotExist)

	// ErrVarNotExist is caused by accessing a non-existing variable
	ErrVarNotExist = os.ErrNotExist

	// ErrVarPermission is caused by not haven the right permissions either
	// because of not being root or xattrs not allowing changes
	ErrVarPermission = os.ErrPermission

	// ErrNoFS is returned when the file system is not available for some
	// reason.
	ErrNoFS = errors.New("varfs not available")
)

var (
	// ErrBadGUID is for any errors parsing GUIDs.
	ErrBadGUID = errors.New("Bad GUID")
)

Functions

func RemoveVariable

func RemoveVariable(e EFIVar, desc VariableDescriptor) error

RemoveVariable calls remove() on the current efivarfs backend.

func SimpleListVariables

func SimpleListVariables(e EFIVar) ([]string, error)

SimpleListVariables is like ListVariables but returns a []string instead of a []VariableDescriptor.

func SimpleRemoveVariable

func SimpleRemoveVariable(e EFIVar, v string) error

SimpleRemoveVariable is like RemoveVariable but takes the combined name and guid string of the form name-guid.

func SimpleWriteVariable

func SimpleWriteVariable(e EFIVar, v string, attrs VariableAttributes, data *bytes.Buffer) error

SimpleWriteVariable is like WriteVariables but takes the combined name and guid string of the form name-guid and returns a bytes.Buffer instead of a []byte.

func WriteVariable

func WriteVariable(e EFIVar, desc VariableDescriptor, attrs VariableAttributes, data []byte) error

WriteVariable calls set() on the current efivarfs backend.

Types

type EFIVar

type EFIVar interface {
	Get(desc VariableDescriptor) (VariableAttributes, []byte, error)
	List() ([]VariableDescriptor, error)
	Remove(desc VariableDescriptor) error
	Set(desc VariableDescriptor, attrs VariableAttributes, data []byte) error
}

EFIVar is the interface for EFI variables. Note that it need not use a file system, but typically does.

type EFIVarFS

type EFIVarFS struct {
	// contains filtered or unexported fields
}

EFIVarFS implements EFIVar

func New

func New() (*EFIVarFS, error)

New returns an EFIVarFS using the default path.

func NewPath

func NewPath(p string) (*EFIVarFS, error)

NewPath returns an EFIVarFS given a path.

func (*EFIVarFS) Get

func (v *EFIVarFS) Get(desc VariableDescriptor) (VariableAttributes, []byte, error)

Get reads the contents of an efivar if it exists and has the necessary permission

func (*EFIVarFS) List

func (v *EFIVarFS) List() ([]VariableDescriptor, error)

List returns the VariableDescriptor for each efivar in the system TODO: why can't list implement

func (*EFIVarFS) Remove

func (v *EFIVarFS) Remove(desc VariableDescriptor) error

Remove makes the specified EFI var mutable and then deletes it

func (*EFIVarFS) Set

func (v *EFIVarFS) Set(desc VariableDescriptor, attrs VariableAttributes, data []byte) error

Set modifies a given efivar with the provided contents

type VariableAttributes

type VariableAttributes uint32

VariableAttributes is an uint32 identifying the variables attributes.

const (
	// AttributeNonVolatile indicates a variable is non volatile.
	AttributeNonVolatile VariableAttributes = 0x00000001
	// AttributeBootserviceAccess indicates a variable is accessible during boot service.
	AttributeBootserviceAccess VariableAttributes = 0x00000002
	// AttributeRuntimeAccess indicates a variable is accessible during runtime.
	AttributeRuntimeAccess VariableAttributes = 0x00000004
	// AttributeHardwareErrorRecord indicates a variable holds hardware error records.
	AttributeHardwareErrorRecord VariableAttributes = 0x00000008
	// AttributeAuthenticatedWriteAccess indicates a variable needs authentication before write access.
	AttributeAuthenticatedWriteAccess VariableAttributes = 0x00000010
	// AttributeTimeBasedAuthenticatedWriteAccess indicates a variable needs time based authentication before write access.
	AttributeTimeBasedAuthenticatedWriteAccess VariableAttributes = 0x00000020
	// AttributeAppendWrite indicates data written to this variable is appended.
	AttributeAppendWrite VariableAttributes = 0x00000040
	// AttributeEnhancedAuthenticatedAccess indicate a variable uses the new authentication format.
	AttributeEnhancedAuthenticatedAccess VariableAttributes = 0x00000080
)

func ReadVariable

func ReadVariable(e EFIVar, desc VariableDescriptor) (VariableAttributes, []byte, error)

ReadVariable calls get() on the current efivarfs backend.

func SimpleReadVariable

func SimpleReadVariable(e EFIVar, v string) (VariableAttributes, *bytes.Reader, error)

SimpleReadVariable is like ReadVariables but takes the combined name and guid string of the form name-guid and returns a bytes.Reader instead of a []byte.

type VariableDescriptor

type VariableDescriptor struct {
	Name string
	GUID guid.UUID
}

VariableDescriptor contains the name and GUID identifying a variable

func ListVariables

func ListVariables(e EFIVar) ([]VariableDescriptor, error)

ListVariables calls list() on the current efivarfs backend.