WIP - attempts to bypass shim lock

4 files changed, 38 insertions, 63 deletions

diff --git a/src/config/console.h b/src/config/console.h
index 9f770d094..689e0519f 100644
--- a/src/config/console.h
+++ b/src/config/console.h
@@ -39,7 +39,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 //#define	CONSOLE_SYSLOG		/* Syslog console */
 //#define	CONSOLE_SYSLOGS		/* Encrypted syslog console */
 //#define	CONSOLE_VMWARE		/* VMware logfile console */
-//#define	CONSOLE_DEBUGCON	/* Bochs/QEMU/KVM debug port console */
+#define	CONSOLE_DEBUGCON	/* Bochs/QEMU/KVM debug port console */
 //#define	CONSOLE_INT13		/* INT13 disk log console */
 
 /*
diff --git a/src/image/efi_image.c b/src/image/efi_image.c
index 13f08de28..d56f4cdd4 100644
--- a/src/image/efi_image.c
+++ b/src/image/efi_image.c
@@ -156,7 +156,6 @@ static int efi_image_exec ( struct image *image ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 	struct efi_snp_device *snpdev;
 	EFI_DEVICE_PATH_PROTOCOL *path;
-	struct efi_shim_unlocker unlocker;
 	union {
 		EFI_LOADED_IMAGE_PROTOCOL *image;
 		void *interface;
@@ -235,8 +234,7 @@ static int efi_image_exec ( struct image *image ) {
 	}
 
 	/* Install shim unlocker (if using a shim) */
-	if ( shim &&
-	     ( ( rc = efi_shim_install ( &unlocker ) ) != 0 ) ) {
+	if ( shim && ( ( rc = efi_shim_install() ) != 0 ) ) {
 		DBGC ( image, "EFIIMAGE %s could not install shim unlocker: "
 		       "%s\n", image->name, strerror ( rc ) );
 		goto err_shim_install;
@@ -295,6 +293,9 @@ static int efi_image_exec ( struct image *image ) {
 	/* Wrap calls made by the loaded image (for debugging) */
 	efi_wrap ( handle );
 
+	///
+	DBG ( "***** loaded image systab %p\n", loaded.image->SystemTable );
+
 	/* Reset console since image will probably use it */
 	console_reset();
 
@@ -337,7 +338,7 @@ static int efi_image_exec ( struct image *image ) {
 		bs->UnloadImage ( handle );
  err_load_image:
 	if ( shim )
-		efi_shim_uninstall ( &unlocker );
+		efi_shim_uninstall();
  err_shim_install:
 	free ( cmdline );
  err_cmdline:
diff --git a/src/include/ipxe/efi/efi_shim.h b/src/include/ipxe/efi/efi_shim.h
index ec7803d66..6d146a4eb 100644
--- a/src/include/ipxe/efi/efi_shim.h
+++ b/src/include/ipxe/efi/efi_shim.h
@@ -12,18 +12,10 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/image.h>
 #include <ipxe/efi/efi.h>
 
-/** A shim unlocker */
-struct efi_shim_unlocker {
-	/** Protocol installation event */
-	EFI_EVENT event;
-	/** Protocol notification registration token */
-	void *token;
-};
-
 extern struct image_tag efi_shim __image_tag;
 extern struct image_tag efi_shim_crutch __image_tag;
 
-extern int efi_shim_install ( struct efi_shim_unlocker *unlocker );
-extern void efi_shim_uninstall ( struct efi_shim_unlocker *unlocker );
+extern int efi_shim_install ( void );
+extern void efi_shim_uninstall ( void );
 
 #endif /* _IPXE_EFI_SHIM_H */
diff --git a/src/interface/efi/efi_shim.c b/src/interface/efi/efi_shim.c
index b0caf227d..500a274a3 100644
--- a/src/interface/efi/efi_shim.c
+++ b/src/interface/efi/efi_shim.c
@@ -38,21 +38,25 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
-/** EFI shim image */
+/** UEFI shim image */
 struct image_tag efi_shim __image_tag = {
 	.name = "SHIM",
 };
 
-/** EFI shim crutch image */
+/** UEFI shim crutch image */
 struct image_tag efi_shim_crutch __image_tag = {
 	.name = "SHIMCRUTCH",
 };
 
+/** Original ExitBootServices() function */
+static EFI_EXIT_BOOT_SERVICES efi_shim_orig_ebs;
+
 /**
  * Unlock UEFI shim
  *
- * @v event		Event
- * @v context		Event context
+ * @v image		Image handle
+ * @v key		Map key
+ * @ret efirc		EFI status code
  *
  * The UEFI shim is gradually becoming less capable of directly
  * executing a kernel image, due to an ever increasing list of
@@ -68,77 +72,55 @@ struct image_tag efi_shim_crutch __image_tag = {
  * this spurious requirement for the use of an additional second stage
  * loader.
  */
-static EFIAPI void efi_shim_unlock ( EFI_EVENT event __unused, void *context ) {
+static EFIAPI EFI_STATUS efi_shim_unlock ( EFI_HANDLE image, UINTN key ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-	EFI_GUID *protocol = &efi_shim_lock_protocol_guid;
-	struct efi_shim_unlocker *unlocker = context;
+	uint8_t empty[0];
 	union {
 		EFI_SHIM_LOCK_PROTOCOL *lock;
 		void *interface;
 	} u;
-	uint8_t empty[0];
 	EFI_STATUS efirc;
 
-	/* Process all new instances of the shim lock protocol */
-	while ( 1 ) {
+	//
+	DBG ( "******** called\n" );
 
-		/* Get next instance */
-		if ( ( efirc = bs->LocateProtocol ( protocol, unlocker->token,
-						    &u.interface ) ) != 0 )
-			break;
-
-		/* Call shim lock protocol with empty buffer */
+	/* Locate shim lock protocol */
+	if ( ( efirc = bs->LocateProtocol ( &efi_shim_lock_protocol_guid,
+					    NULL, &u.interface ) ) == 0 ) {
 		u.lock->Verify ( empty, sizeof ( empty ) );
-		DBGC ( unlocker, "SHIM unlocked %p\n", u.interface );
+		DBGC ( u.lock, "SHIM unlocked %p\n", u.lock );
 	}
+
+	/* Hand off to original ExitBootServices() */
+	return efi_shim_orig_ebs ( image, key );
 }
 
 /**
  * Install UEFI shim unlocker
  *
- * @v unlocker		Shim unlocker
  * @ret rc		Return status code
  */
-int efi_shim_install ( struct efi_shim_unlocker *unlocker ) {
+int efi_shim_install (  ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
-	EFI_GUID *protocol = &efi_shim_lock_protocol_guid;
-	EFI_STATUS efirc;
-	int rc;
-
-	/* Create event */
-	if ( ( efirc = bs->CreateEvent ( EVT_NOTIFY_SIGNAL, TPL_CALLBACK,
-					 efi_shim_unlock, unlocker,
-					 &unlocker->event ) ) != 0 ) {
-		rc = -EEFI ( efirc );
-		DBGC ( unlocker, "SHIM could not create event: %s\n",
-		       strerror ( rc ) );
-		goto err_create_event;
-	}
 
-	/* Register for protocol installations */
-	if ( ( efirc = bs->RegisterProtocolNotify ( protocol, unlocker->event,
-						    &unlocker->token ) ) != 0){
-		rc = -EEFI ( efirc );
-		DBGC ( unlocker, "SHIM could not register for protocols: %s\n",
-		       strerror ( rc ) );
-		goto err_register_notify;
-	}
+	/* Intercept ExitBootServices() via boot services table */
+	efi_shim_orig_ebs = bs->ExitBootServices;
+	bs->ExitBootServices = efi_shim_unlock;
 
-	return 0;
+	//
+	DBG ( "******** hooked in systab %p\n", efi_systab );
 
- err_register_notify:
-	bs->CloseEvent ( unlocker->event );
- err_create_event:
-	return rc;
+
+	return 0;
 }
 
 /**
  * Uninstall UEFI shim unlocker
  *
- * @v unlocker		Shim unlocker
  */
-void efi_shim_uninstall ( struct efi_shim_unlocker *unlocker ) {
+void efi_shim_uninstall ( void ) {
 	EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
 
-	bs->CloseEvent ( unlocker->event );
+	/* Restore original ExitBootServices() */
+	bs->ExitBootServices = efi_shim_orig_ebs;
 }