From ad8b20e8e2cd71418a536a8068f8e37222bd3855 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         | 100 +++++++++++++++++++++++++++++---------------------
 shim.c        |  25 +++++++++++++
 shim.h        |   2 +
 5 files changed, 119 insertions(+), 41 deletions(-)

diff --git a/Make.defaults b/Make.defaults
index bbfc1d7f..d8b4ba25 100644
--- a/Make.defaults
+++ b/Make.defaults
@@ -124,6 +124,9 @@ 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 cfc4525b..7ad782ab 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 38675211..7734806b 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",
@@ -138,40 +132,54 @@ static EFI_STATUS 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);
@@ -223,11 +231,24 @@ EFI_STATUS import_mok_state(EFI_HANDLE image_handle)
 		UINT32 attrs = 0;
 		BOOLEAN delete = FALSE, present, addend;
 
+		addend = (v->flags & MOK_VARIABLE_APPEND_CERT) != 0;
+
 		efi_status = get_variable_attr(v->name,
 					       &v->data, &v->data_size,
 					       *v->guid, &attrs);
-		if (efi_status == EFI_NOT_FOUND)
+		if (efi_status == EFI_NOT_FOUND) {
+			if (v->rtname && addend) {
+				efi_status = mirror_one_mok_variable(v);
+				if (EFI_ERROR(efi_status) &&
+				    ret != EFI_SECURITY_VIOLATION)
+					ret = efi_status;
+			}
+			/*
+			 * after possibly adding, we can continue, no
+			 * further checks to be done.
+			 */
 			continue;
+		}
 		if (EFI_ERROR(efi_status)) {
 			perror(L"Could not verify %s: %r\n", v->name,
 			       efi_status);
@@ -272,9 +293,6 @@ EFI_STATUS import_mok_state(EFI_HANDLE image_handle)
 		}
 
 		present = (v->data && v->data_size) ? TRUE : FALSE;
-		addend = (v->addend_source && v->addend_size &&
-			  *v->addend_source && *v->addend_size)
-			? TRUE : FALSE;
 
 		if (v->flags & MOK_VARIABLE_MEASURE && present) {
 			/*
diff --git a/shim.c b/shim.c
index 05fc6500..64b79da5 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;
 
 /*
@@ -1065,6 +1069,25 @@ 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
 		 */
@@ -2541,8 +2564,10 @@ 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 2b359d82..2e411040 100644
--- a/shim.h
+++ b/shim.h
@@ -167,8 +167,10 @@ 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;