canonical · chrisccoulson · Feb 13, 2026 · Feb 12, 2026
diff --git a/efi/preinstall/preinstall_test.go b/efi/preinstall/preinstall_test.go
@@ -45,23 +45,28 @@ var (
 	//go:embed testdata/MicrosoftUefiCA2023.crt
 	msUefiCACert2023PEM []byte
 
+	//go:embed testdata/MicrosoftOptionROMUefiCA2023.crt
+	msOptionROMUefiCACert2023PEM []byte
+
 	//go:embed testdata/shim-signed_1.54+15.7-0ubuntu1_amd64_latest.pk7
 	shimUbuntuSig4PEM []byte
 
 	//go:embed testdata/PkKek-1-snakeoil.pem
 	snakeoilCertPEM []byte
 
-	msUefiCACert     []byte
-	msUefiCACert2023 []byte
-	shimUbuntuSig4   []byte
-	snakeoilCert     []byte
+	msUefiCACert              []byte
+	msUefiCACert2023          []byte
+	msOptionROMUefiCACert2023 []byte
+	shimUbuntuSig4            []byte
+	snakeoilCert              []byte
 )
 
 func init() {
 	tpm2_testutil.AddCommandLineFlags()
 
 	msUefiCACert = testutil.MustDecodePEMType("CERTIFICATE", msUefiCACertPEM)
 	msUefiCACert2023 = testutil.MustDecodePEMType("CERTIFICATE", msUefiCACert2023PEM)
+	msOptionROMUefiCACert2023 = testutil.MustDecodePEMType("CERTIFICATE", msOptionROMUefiCACert2023PEM)
 	shimUbuntuSig4 = testutil.MustDecodePEMType("PKCS7", shimUbuntuSig4PEM)
 	snakeoilCert = testutil.MustDecodePEMType("CERTIFICATE", snakeoilCertPEM)
 }

diff --git a/efi/preinstall/profile.go b/efi/preinstall/profile.go
@@ -103,8 +103,27 @@ type authorityTrustData struct {
 
 var (
 	knownCAs = authorityTrustDataSet{
+		// The 2011 UEFI CA was used to sign both drivers and boot code. Because
+		// what is signed isn't audit-able, and we know it signed boot code that
+		// doesn't meet our requirements for FDE, we distrust it for both drivers
+		// and boot code.
 		{internal_efi.MSUefiCA2011, 0},
-		{internal_efi.MSUefiCA2023, 0}, // be conservative here for now, but will we be able to set the authorityTrustDrivers flag for the MS2023 CA?
+
+		// The 2023 UEFI CA is only used for signing boot code. Like with the 2011
+		// UEFI CA, the boot code that is signed isn't audit-able so we distrust
+		// it for signing boot code because we can't be sure that everything it
+		// signed meets our requirements for FDE. We trust it for signing drivers
+		// based on the fact it isn't used for this, which allows us to optimise
+		// the PCR selection for this CA.
+		{internal_efi.MSUefiCA2023, authorityTrustDrivers},
+
+		// The 2023 option ROM UEFI CA is only used for signing drivers. Like with
+		// the 2011 UEFI CA, the drivers that are signed aren't audit-able so we
+		// distrust it for signing drivers because we can't be sure that everything
+		// it signed meets our requirements for FDE. We trust it for signing boot
+		// code based on the fact it isn't used for this, which allows us to optimise
+		// the PCR selection for this CA.
+		{internal_efi.MSOptionROMUefiCA2023, authorityTrustBootCode},
 	}
 )
 

diff --git a/efi/preinstall/profile_test.go b/efi/preinstall/profile_test.go
@@ -209,25 +209,13 @@ func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionLockToPlatformFirmar
 //}
 
 func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionDefaultCAsTrustedForDrivers(c *C) {
-	restore := MockKnownCAs(AuthorityTrustDataSet{
-		{internal_efi.MSUefiCA2011, 0},
-		{internal_efi.MSUefiCA2023, AuthorityTrustDrivers},
-	})
-	defer restore()
-
 	s.testWithAutoTCGPCRProfilePCRSelection(c, &testWithAutoTCGPCRProfilePCRSelectionParams{
 		usedSecureBootCAs: [][]byte{msUefiCACert2023},
 		expectedPcrs:      tpm2.HandleList{4, 7},
 	})
 }
 
 func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionLockToDriversAndApps(c *C) {
-	restore := MockKnownCAs(AuthorityTrustDataSet{
-		{internal_efi.MSUefiCA2011, 0},
-		{internal_efi.MSUefiCA2023, AuthorityTrustDrivers},
-	})
-	defer restore()
-
 	s.testWithAutoTCGPCRProfilePCRSelection(c, &testWithAutoTCGPCRProfilePCRSelectionParams{
 		usedSecureBootCAs: [][]byte{msUefiCACert2023},
 		opts:              PCRProfileOptionLockToDriversAndApps,
@@ -270,27 +258,15 @@ func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionTrustSecureBootAutho
 //}
 
 func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionDefaultCAsTrustedForBootCode(c *C) {
-	restore := MockKnownCAs(AuthorityTrustDataSet{
-		{internal_efi.MSUefiCA2011, 0},
-		{internal_efi.MSUefiCA2023, AuthorityTrustBootCode},
-	})
-	defer restore()
-
 	s.testWithAutoTCGPCRProfilePCRSelection(c, &testWithAutoTCGPCRProfilePCRSelectionParams{
-		usedSecureBootCAs: [][]byte{msUefiCACert2023},
+		usedSecureBootCAs: [][]byte{msOptionROMUefiCACert2023},
 		expectedPcrs:      tpm2.HandleList{2, 7},
 	})
 }
 
 func (s *profileSuite) TestWithAutoTCGPCRProfilePCRSelectionLockToBootManagerCode(c *C) {
-	restore := MockKnownCAs(AuthorityTrustDataSet{
-		{internal_efi.MSUefiCA2011, 0},
-		{internal_efi.MSUefiCA2023, AuthorityTrustBootCode},
-	})
-	defer restore()
-
 	s.testWithAutoTCGPCRProfilePCRSelection(c, &testWithAutoTCGPCRProfilePCRSelectionParams{
-		usedSecureBootCAs: [][]byte{msUefiCACert2023},
+		usedSecureBootCAs: [][]byte{msOptionROMUefiCACert2023},
 		opts:              PCRProfileOptionLockToBootManagerCode,
 		expectedPcrs:      tpm2.HandleList{2, 4, 7},
 	})

diff --git a/efi/preinstall/testdata/MicrosoftOptionROMUefiCA2023.crt b/efi/preinstall/testdata/MicrosoftOptionROMUefiCA2023.crt
@@ -0,0 +1,33 @@
+-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
diff --git a/internal/efi/known_secureboot_cas.go b/internal/efi/known_secureboot_cas.go
@@ -119,4 +119,42 @@ var (
 		},
 		SignatureAlgorithm: x509.SHA256WithRSA,
 	}
+
+	MSOptionROMUefiCA2023 = &SecureBootAuthorityIdentity{
+		// CN=Microsoft Option ROM UEFI CA 2023,O=Microsoft Corporation,C=US
+		Subject: []byte{
+			0x30, 0x59, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04,
+			0x06, 0x13, 0x02, 0x55, 0x53, 0x31, 0x1e, 0x30, 0x1c, 0x06,
+			0x03, 0x55, 0x04, 0x0a, 0x13, 0x15, 0x4d, 0x69, 0x63, 0x72,
+			0x6f, 0x73, 0x6f, 0x66, 0x74, 0x20, 0x43, 0x6f, 0x72, 0x70,
+			0x6f, 0x72, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x31, 0x2a, 0x30,
+			0x28, 0x06, 0x03, 0x55, 0x04, 0x03, 0x13, 0x21, 0x4d, 0x69,
+			0x63, 0x72, 0x6f, 0x73, 0x6f, 0x66, 0x74, 0x20, 0x4f, 0x70,
+			0x74, 0x69, 0x6f, 0x6e, 0x20, 0x52, 0x4f, 0x4d, 0x20, 0x55,
+			0x45, 0x46, 0x49, 0x20, 0x43, 0x41, 0x20, 0x32, 0x30, 0x32,
+			0x33,
+		},
+		SubjectKeyId: []byte{
+			0x51, 0x4f, 0xbf, 0x93, 0x7f, 0xa4, 0x6f, 0xb5, 0x7b, 0xf0,
+			0x7a, 0xf8, 0xbe, 0xd8, 0x4b, 0x3b, 0x86, 0x4b, 0x17, 0x11,
+		},
+		PublicKeyAlgorithm: x509.RSA,
+		Issuer: []byte{
+			0x30, 0x5a, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04,
+			0x06, 0x13, 0x02, 0x55, 0x53, 0x31, 0x1e, 0x30, 0x1c, 0x06,
+			0x03, 0x55, 0x04, 0x0a, 0x13, 0x15, 0x4d, 0x69, 0x63, 0x72,
+			0x6f, 0x73, 0x6f, 0x66, 0x74, 0x20, 0x43, 0x6f, 0x72, 0x70,
+			0x6f, 0x72, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x31, 0x2b, 0x30,
+			0x29, 0x06, 0x03, 0x55, 0x04, 0x03, 0x13, 0x22, 0x4d, 0x69,
+			0x63, 0x72, 0x6f, 0x73, 0x6f, 0x66, 0x74, 0x20, 0x52, 0x53,
+			0x41, 0x20, 0x44, 0x65, 0x76, 0x69, 0x63, 0x65, 0x73, 0x20,
+			0x52, 0x6f, 0x6f, 0x74, 0x20, 0x43, 0x41, 0x20, 0x32, 0x30,
+			0x32, 0x31,
+		},
+		AuthorityKeyId: []byte{
+			0x84, 0x44, 0x86, 0x06, 0x00, 0x98, 0x3f, 0x2c, 0xaa, 0xb3,
+			0xc5, 0x89, 0xf3, 0xac, 0x2e, 0xc9, 0xe6, 0x9d, 0x09, 0x03,
+		},
+		SignatureAlgorithm: x509.SHA256WithRSA,
+	}
 )