go-uefi

A UEFI library written to interact with Linux efivars. The goal is to provide a Go library to enable application authors to better utilize secure boot and UEFI. This also includes unit-testing to ensure the library is compatible with existing tools, and integration tests to ensure the library is able of deal with future UEFI revisions.

Features

• Implements most Secure Boot relevant structs as defined in UEFI Spec Version 2.8 Errata A (February 14th 2020).
• PE/COFF Checksumming.
• Microsoft Authenticode signing.
• A subset of PKCS7
• Working with EFI_SIGNATURE_LIST and EFI_SIGNATURE_DATABASE.
• Integration tests utilizing vmtest and tianocore.
• Virtual filesystem support for easier testing.

Examples

Some example can be found under cmd/.

Code Examples

Append signatures to db

package main
import (
	"github.com/foxboron/go-uefi/efi/signature"
	"github.com/foxboron/go-uefi/efi/util"
	"github.com/foxboron/go-uefi/efivar"
	"github.com/foxboron/go-uefi/efivarfs"
)

var (
    cert, _ = util.ReadKeyFromFile("signing.key")
    key, _ = util.ReadCertFromFile("signing.cert")
    sigdata = signature.SignatureData{
	    Owner: util.EFIGUID{Data1: 0xc1095e1b, Data2: 0x8a3b, Data3: 0x4cf5, Data4: [8]uint8{0x9d, 0x4a, 0xaf, 0xc7, 0xd7, 0x5d, 0xca, 0x68}},
	    Data:  []uint8{}}
)

func main() {
	efifs := efivarfs.NewFS().Open()
	db, _ := efifs.Getdb()
	db.AppendSignature(signature.CERT_SHA256_GUID, &sigdata)
	efifs.WriteSignedUpdate(efivar.Db, db, key, cert)
}

Use a in-memory efivarfs for tests

package main
import (
	"github.com/foxboron/go-uefi/efi"
	"github.com/foxboron/go-uefi/efi/efitest"
	"github.com/foxboron/go-uefi/efi/signature"
	"github.com/foxboron/go-uefi/efivarfs"
)

func TestSecureBootOn(t *testing.T) {
	efifs := efivarfs.NewTestFS().
		With(efitest.SecureBootOn()).
		Open()
	ok, err := efifs.GetSetupMode()
	if err != nil {
		t.Fatalf("%v", err)
	}
	if !ok {
		t.Fatalf("Secure Boot is not enabled")
	}
}

Sign UEFI binary

package main
import (
	"github.com/foxboron/go-uefi/authenticode"
	"github.com/foxboron/go-uefi/efi/util"
)

var (
	key, _ := util.ReadKeyFromFile("signing.key")
	cert, _ := util.ReadCertFromFile("signing.cert")
)

func main(){
	peFile, _ := os.ReadFile("somefile")
	file, _ := authenticode.Parse(peFile)
	file.Sign(key, cert)
	os.WriteFile("somefile.signed", file.Bytes(), 0644)
}

Checksum UEFI executable

package main
import (
	"github.com/foxboron/go-uefi/authenticode"
)

func main(){
	peFile, _ := os.ReadFile("somefile")
	file, _ := authenticode.Parse(peFile)
	checksum := file.Hash(crypto.SHA256)
	fmt.Printf("%x\n", checksum)
}