From ab26d9a5c035cd56e1b1ae8b0ef74e059fe61d77 Mon Sep 17 00:00:00 2001

From: Patrick Uiterwijk <patrick@puiterwijk.org>

Date: Sat, 21 Jul 2018 04:12:57 +0200

Subject: [PATCH] Implement vendor EFI Signature List (ESL)

Signed-off-by: Patrick Uiterwijk <patrick@puiterwijk.org>

---

 Make.defaults |  3 ++

 cert.S        | 30 ++++++++++++++++++

 mok.c         | 86 +++++++++++++++++++++++++++------------------------

 shim.c        | 25 +++++++++++++++

 shim.h        |  2 ++

 5 files changed, 106 insertions(+), 40 deletions(-)

diff --git a/Make.defaults b/Make.defaults

index 4c26c1a..0f9b979 100644

--- a/Make.defaults

+++ b/Make.defaults

@@ -126,6 +126,9 @@ CFLAGS += "-DEFI_ARCH=L\"$(ARCH_SUFFIX)\"" "-DDEBUGDIR=L\"/usr/lib/debug/usr/sha

 ifneq ($(origin VENDOR_CERT_FILE), undefined)

 	CFLAGS += -DVENDOR_CERT_FILE=\"$(VENDOR_CERT_FILE)\"

 endif

+ifneq ($(origin VENDOR_ESL_FILE), undefined)

+	CFLAGS += -DVENDOR_ESL_FILE=\"$(VENDOR_ESL_FILE)\"

+endif

 ifneq ($(origin VENDOR_DBX_FILE), undefined)

 	CFLAGS += -DVENDOR_DBX_FILE=\"$(VENDOR_DBX_FILE)\"

 endif

diff --git a/cert.S b/cert.S

index cfc4525..7ad782a 100644

--- a/cert.S

+++ b/cert.S

@@ -8,12 +8,18 @@ cert_table:

 #else

 	.long	0

 #endif

+#if defined(VENDOR_ESL_FILE)

+	.long	vendor_esl_priv_end - vendor_esl_priv

+#else

+	.long	0

+#endif

 #if defined(VENDOR_DBX_FILE)

 	.long	vendor_dbx_priv_end - vendor_dbx_priv

 #else

 	.long	0

 #endif

 	.long	vendor_cert_priv - cert_table

+	.long	vendor_esl_priv - cert_table

 	.long	vendor_dbx_priv - cert_table

 #if defined(VENDOR_CERT_FILE)

 	.data

@@ -39,6 +45,30 @@ vendor_cert_priv:

 	.section .vendor_cert, "a", %progbits

 vendor_cert_priv_end:

 #endif

+#if defined(VENDOR_ESL_FILE)

+	.data

+	.align	1

+	.type	vendor_esl_priv, %object

+	.size	vendor_esl_priv, vendor_esl_priv_end-vendor_esl_priv

+	.section .vendor_cert, "a", %progbits

+vendor_esl_priv:

+.incbin VENDOR_ESL_FILE

+vendor_esl_priv_end:

+#else

+	.bss

+	.type	vendor_esl_priv, %object

+	.size	vendor_esl_priv, 1

+	.section .vendor_cert, "a", %progbits

+vendor_esl_priv:

+	.zero	1

+

+	.data

+	.align 4

+	.type	vendor_esl_size_priv, %object

+	.size	vendor_esl_size_priv, 4

+	.section .vendor_cert, "a", %progbits

+vendor_esl_priv_end:

+#endif

 #if defined(VENDOR_DBX_FILE)

 	.data

 	.align	1

diff --git a/mok.c b/mok.c

index 2b9d796..f52e286 100644

--- a/mok.c

+++ b/mok.c

@@ -62,12 +62,6 @@ struct mok_state_variable {

 	EFI_GUID *guid;

 	UINT8 *data;

 	UINTN data_size;

-	/*

-	 * These two are indirect pointers just to make initialization

-	 * saner...

-	 */

-	UINT8 **addend_source;

-	UINT32 *addend_size;

 	UINT32 yes_attr;

 	UINT32 no_attr;

 	UINT32 flags;

@@ -75,10 +69,11 @@ struct mok_state_variable {

 	UINT8 *state;

 };

-#define MOK_MIRROR_KEYDB	0x01

-#define MOK_MIRROR_DELETE_FIRST	0x02

-#define MOK_VARIABLE_MEASURE	0x04

-#define MOK_VARIABLE_LOG	0x08

+#define MOK_MIRROR_KEYDB		0x01

+#define MOK_MIRROR_DELETE_FIRST		0x02

+#define MOK_VARIABLE_MEASURE		0x04

+#define MOK_VARIABLE_LOG		0x08

+#define MOK_VARIABLE_APPEND_CERT	0x10

 struct mok_state_variable mok_state_variables[] = {

 	{.name = L"MokList",

@@ -88,10 +83,9 @@ struct mok_state_variable mok_state_variables[] = {

 	 .yes_attr = EFI_VARIABLE_BOOTSERVICE_ACCESS |

 		     EFI_VARIABLE_NON_VOLATILE,

 	 .no_attr = EFI_VARIABLE_RUNTIME_ACCESS,

-	 .addend_source = &vendor_cert,

-	 .addend_size = &vendor_cert_size,

 	 .flags = MOK_MIRROR_KEYDB |

-		  MOK_VARIABLE_LOG,

+		  MOK_VARIABLE_LOG |

+		  MOK_VARIABLE_APPEND_CERT,

 	 .pcr = 14,

 	},

 	{.name = L"MokListX",

@@ -139,40 +133,54 @@ mirror_one_mok_variable(struct mok_state_variable *v)

 	uint8_t *p = NULL;

 	if ((v->flags & MOK_MIRROR_KEYDB) &&

-	    v->addend_source && *v->addend_source &&

-	    v->addend_size && *v->addend_size) {

-		EFI_SIGNATURE_LIST *CertList = NULL;

-		EFI_SIGNATURE_DATA *CertData = NULL;

-		FullDataSize = v->data_size

-			     + sizeof (*CertList)

-			     + sizeof (EFI_GUID)

-			     + *v->addend_size;

+	    (v->flags & MOK_VARIABLE_APPEND_CERT)) {

+		FullDataSize = v->data_size;

+

+		if (vendor_esl_size) {

+			FullDataSize += vendor_esl_size;

+		}

+		if (vendor_cert_size) {

+			FullDataSize += sizeof (EFI_SIGNATURE_LIST)

+				     + sizeof (EFI_GUID)

+			             + vendor_cert_size;

+		}

+

 		FullData = AllocatePool(FullDataSize);

 		if (!FullData) {

 			perror(L"Failed to allocate space for MokListRT\n");

 			return EFI_OUT_OF_RESOURCES;

 		}

 		p = FullData;

-

 		if (!EFI_ERROR(efi_status) && v->data_size > 0) {

 			CopyMem(p, v->data, v->data_size);

 			p += v->data_size;

 		}

-		CertList = (EFI_SIGNATURE_LIST *)p;

-		p += sizeof (*CertList);

-		CertData = (EFI_SIGNATURE_DATA *)p;

-		p += sizeof (EFI_GUID);

-

-		CertList->SignatureType = EFI_CERT_TYPE_X509_GUID;

-		CertList->SignatureListSize = *v->addend_size

-					      + sizeof (*CertList)

-					      + sizeof (*CertData)

-					      -1;

-		CertList->SignatureHeaderSize = 0;

-		CertList->SignatureSize = *v->addend_size + sizeof (EFI_GUID);

-

-		CertData->SignatureOwner = SHIM_LOCK_GUID;

-		CopyMem(p, *v->addend_source, *v->addend_size);

+

+		if (vendor_esl_size) {

+			CopyMem(p, vendor_esl, vendor_esl_size);

+			p += vendor_esl_size;

+		}

+

+		if (vendor_cert_size) {

+			EFI_SIGNATURE_LIST *CertList = NULL;

+			EFI_SIGNATURE_DATA *CertData = NULL;

+

+			CertList = (EFI_SIGNATURE_LIST *)p;

+			p += sizeof (*CertList);

+			CertData = (EFI_SIGNATURE_DATA *)p;

+			p += sizeof (EFI_GUID);

+

+			CertList->SignatureType = EFI_CERT_TYPE_X509_GUID;

+			CertList->SignatureListSize = vendor_cert_size

+						      + sizeof (*CertList)

+						      + sizeof (*CertData)

+						      -1;

+			CertList->SignatureHeaderSize = 0;

+			CertList->SignatureSize = vendor_cert_size + sizeof (EFI_GUID);

+

+			CertData->SignatureOwner = SHIM_LOCK_GUID;

+			CopyMem(p, vendor_cert, vendor_cert_size);

+		}

 		if (v->data && v->data_size)

 			FreePool(v->data);

@@ -247,9 +255,7 @@ EFI_STATUS import_mok_state(EFI_HANDLE image_handle)

 		UINT32 attrs = 0;

 		BOOLEAN delete = FALSE, present, addend;

-		addend = (v->addend_source && v->addend_size &&

-			  *v->addend_source && *v->addend_size)

-			? TRUE : FALSE;

+		addend = (v->flags & MOK_VARIABLE_APPEND_CERT) != 0;

 		efi_status = get_variable_attr(v->name,

 					       &v->data, &v->data_size,

diff --git a/shim.c b/shim.c

index 0015534..15b29fb 100644

--- a/shim.c

+++ b/shim.c

@@ -66,14 +66,18 @@ static UINT32 load_options_size;

  */

 extern struct {

 	UINT32 vendor_cert_size;

+	UINT32 vendor_esl_size;

 	UINT32 vendor_dbx_size;

 	UINT32 vendor_cert_offset;

+	UINT32 vendor_esl_offset;

 	UINT32 vendor_dbx_offset;

 } cert_table;

 UINT32 vendor_cert_size;

+UINT32 vendor_esl_size;

 UINT32 vendor_dbx_size;

 UINT8 *vendor_cert;

+UINT8 *vendor_esl;

 UINT8 *vendor_dbx;

 /*

@@ -1059,6 +1063,25 @@ static EFI_STATUS verify_buffer (char *data, int datasize,

 		}

 #endif /* defined(ENABLE_SHIM_CERT) */

+		/*

+		 * Check against a built-in EFI Signature List (ESL)

+		 */

+		if (vendor_esl_size &&

+		    check_db_cert_in_ram((EFI_SIGNATURE_LIST*)vendor_esl,

+					 vendor_esl_size,

+					 cert,

+					 sha256hash,

+					 L"Shim",

+					 SHIM_LOCK_GUID) == DATA_FOUND) {

+			update_verification_method(VERIFIED_BY_CERT);

+			// tpm_measurement is done by check_db_cert_in_ram

+			efi_status = EFI_SUCCESS;

+			drain_openssl_errors();

+			return efi_status;

+		} else {

+			LogError(L"check_db_cert_in_ram(vendor_esl) failed\n");

+		}

+

 		/*

 		 * And finally, check against shim's built-in key

 		 */

@@ -2535,8 +2558,10 @@ efi_main (EFI_HANDLE passed_image_handle, EFI_SYSTEM_TABLE *passed_systab)

 	verification_method = VERIFIED_BY_NOTHING;

 	vendor_cert_size = cert_table.vendor_cert_size;

+	vendor_esl_size = cert_table.vendor_esl_size;

 	vendor_dbx_size = cert_table.vendor_dbx_size;

 	vendor_cert = (UINT8 *)&cert_table + cert_table.vendor_cert_offset;

+	vendor_esl = (UINT8 *)&cert_table + cert_table.vendor_esl_offset;

 	vendor_dbx = (UINT8 *)&cert_table + cert_table.vendor_dbx_offset;

 	CHAR16 *msgs[] = {

 		L"import_mok_state() failed\n",

diff --git a/shim.h b/shim.h

index 04e770b..fb58b69 100644

--- a/shim.h

+++ b/shim.h

@@ -169,8 +169,10 @@ extern EFI_STATUS start_image(EFI_HANDLE image_handle, CHAR16 *ImagePath);

 extern EFI_STATUS import_mok_state(EFI_HANDLE image_handle);

 extern UINT32 vendor_cert_size;

+extern UINT32 vendor_esl_size;

 extern UINT32 vendor_dbx_size;

 extern UINT8 *vendor_cert;

+extern UINT8 *vendor_esl;

 extern UINT8 *vendor_dbx;

 extern UINT8 user_insecure_mode;

-- 

2.18.1