efi_loader: memory buffer for variables

Saving UEFI variable as encoded U-Boot environment variables does not allow
support at runtime.

Provide functions to manage a memory buffer with UEFI variables.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

include/efi_variable.h

@@ -141,4 +141,58 @@ efi_status_t efi_var_to_file(void);
  */
 efi_status_t efi_var_from_file(void);
 
+/**
+ * efi_var_mem_init() - set-up variable list
+ *
+ * Return:	status code
+ */
+efi_status_t efi_var_mem_init(void);
+
+/**
+ * efi_var_mem_find() - find a variable in the list
+ *
+ * @guid:	GUID of the variable
+ * @name:	name of the variable
+ * @next:	on exit pointer to the next variable after the found one
+ * Return:	found variable
+ */
+struct efi_var_entry *efi_var_mem_find(const efi_guid_t *guid, const u16 *name,
+				       struct efi_var_entry **next);
+
+/**
+ * efi_var_mem_del() - delete a variable from the list of variables
+ *
+ * @var:	variable to delete
+ */
+void efi_var_mem_del(struct efi_var_entry *var);
+
+/**
+ * efi_var_mem_ins() - append a variable to the list of variables
+ *
+ * The variable is appended without checking if a variable of the same name
+ * already exists. The two data buffers are concatenated.
+ *
+ * @variable_name:	variable name
+ * @vendor:		GUID
+ * @attributes:		variable attributes
+ * @size1:		size of the first data buffer
+ * @data1:		first data buffer
+ * @size2:		size of the second data field
+ * @data2:		second data buffer
+ * @time:		time of authentication (as seconds since start of epoch)
+ * Result:		status code
+ */
+efi_status_t efi_var_mem_ins(u16 *variable_name,
+			     const efi_guid_t *vendor, u32 attributes,
+			     const efi_uintn_t size1, const void *data1,
+			     const efi_uintn_t size2, const void *data2,
+			     const u64 time);
+
+/**
+ * efi_var_mem_free() - determine free memory for variables
+ *
+ * Return:	maximum data size plus variable name size
+ */
+u64 efi_var_mem_free(void);
+
 #endif

lib/efi_loader/Makefile

@@ -36,6 +36,7 @@ obj-y += efi_runtime.o
 obj-y += efi_setup.o
 obj-$(CONFIG_EFI_UNICODE_COLLATION_PROTOCOL2) += efi_unicode_collation.o
 obj-y += efi_var_common.o
+obj-y += efi_var_mem.o
 ifeq ($(CONFIG_EFI_MM_COMM_TEE),y)
 obj-y += efi_variable_tee.o
 else

lib/efi_loader/efi_var_mem.c

@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * File interface for UEFI variables
+ *
+ * Copyright (c) 2020, Heinrich Schuchardt
+ */
+
+#include <common.h>
+#include <efi_loader.h>
+#include <efi_variable.h>
+#include <u-boot/crc.h>
+
+static struct efi_var_file __efi_runtime_data *efi_var_buf;
+static struct efi_var_entry __efi_runtime_data *efi_current_var;
+
+/**
+ * efi_var_mem_compare() - compare GUID and name with a variable
+ *
+ * @var:	variable to compare
+ * @guid:	GUID to compare
+ * @name:	variable name to compare
+ * @next:	pointer to next variable
+ * Return:	true if match
+ */
+static bool __efi_runtime
+efi_var_mem_compare(struct efi_var_entry *var, const efi_guid_t *guid,
+		    const u16 *name, struct efi_var_entry **next)
+{
+	int i;
+	u8 *guid1, *guid2;
+	const u16 *data, *var_name;
+	bool match = true;
+
+	for (guid1 = (u8 *)&var->guid, guid2 = (u8 *)guid, i = 0;
+	     i < sizeof(efi_guid_t) && match; ++i)
+		match = (guid1[i] == guid2[i]);
+
+	for (data = var->name, var_name = name;; ++data, ++var_name) {
+		if (match)
+			match = (*data == *var_name);
+		if (!*data)
+			break;
+	}
+
+	++data;
+
+	if (next)
+		*next = (struct efi_var_entry *)
+			ALIGN((uintptr_t)data + var->length, 8);
+
+	if (match)
+		efi_current_var = var;
+
+	return match;
+}
+
+struct efi_var_entry __efi_runtime
+*efi_var_mem_find(const efi_guid_t *guid, const u16 *name,
+		  struct efi_var_entry **next)
+{
+	struct efi_var_entry *var, *last;
+
+	last = (struct efi_var_entry *)
+	       ((uintptr_t)efi_var_buf + efi_var_buf->length);
+
+	if (!*name) {
+		if (next) {
+			*next = efi_var_buf->var;
+			if (*next >= last)
+				*next = NULL;
+		}
+		return NULL;
+	}
+	if (efi_current_var &&
+	    efi_var_mem_compare(efi_current_var, guid, name, next)) {
+		if (next && *next >= last)
+			*next = NULL;
+		return efi_current_var;
+	}
+
+	var = efi_var_buf->var;
+	if (var < last) {
+		for (; var;) {
+			struct efi_var_entry *pos;
+			bool match;
+
+			match = efi_var_mem_compare(var, guid, name, &pos);
+			if (pos >= last)
+				pos = NULL;
+			if (match) {
+				if (next)
+					*next = pos;
+				return var;
+			}
+			var = pos;
+		}
+	}
+	if (next)
+		*next = NULL;
+	return NULL;
+}
+
+void __efi_runtime efi_var_mem_del(struct efi_var_entry *var)
+{
+	u16 *data;
+	struct efi_var_entry *next, *last;
+
+	if (!var)
+		return;
+
+	last = (struct efi_var_entry *)
+	       ((uintptr_t)efi_var_buf + efi_var_buf->length);
+	if (var <= efi_current_var)
+		efi_current_var = NULL;
+
+	for (data = var->name; *data; ++data)
+		;
+	++data;
+	next = (struct efi_var_entry *)
+	       ALIGN((uintptr_t)data + var->length, 8);
+	efi_var_buf->length -= (uintptr_t)next - (uintptr_t)var;
+
+	memmove(var, next, (uintptr_t)last - (uintptr_t)next);
+	efi_var_buf->crc32 = crc32(0, (u8 *)efi_var_buf->var,
+				   efi_var_buf->length -
+				   sizeof(struct efi_var_file));
+}
+
+efi_status_t __efi_runtime efi_var_mem_ins(
+				u16 *variable_name,
+				const efi_guid_t *vendor, u32 attributes,
+				const efi_uintn_t size1, const void *data1,
+				const efi_uintn_t size2, const void *data2,
+				const u64 time)
+{
+	u16 *data;
+	struct efi_var_entry *var;
+	u32 var_name_len;
+
+	var = (struct efi_var_entry *)
+	      ((uintptr_t)efi_var_buf + efi_var_buf->length);
+	for (var_name_len = 0; variable_name[var_name_len]; ++var_name_len)
+		;
+	++var_name_len;
+	data = var->name + var_name_len;
+
+	if ((uintptr_t)data - (uintptr_t)efi_var_buf + size1 + size2 >
+	    EFI_VAR_BUF_SIZE)
+		return EFI_OUT_OF_RESOURCES;
+
+	var->attr = attributes;
+	var->length = size1 + size2;
+	var->time = time;
+
+	efi_memcpy_runtime(&var->guid, vendor, sizeof(efi_guid_t));
+	efi_memcpy_runtime(var->name, variable_name,
+			   sizeof(u16) * var_name_len);
+	efi_memcpy_runtime(data, data1, size1);
+	efi_memcpy_runtime((u8 *)data + size1, data2, size2);
+
+	var = (struct efi_var_entry *)
+	      ALIGN((uintptr_t)data + var->length, 8);
+	efi_var_buf->length = (uintptr_t)var - (uintptr_t)efi_var_buf;
+	efi_var_buf->crc32 = crc32(0, (u8 *)efi_var_buf->var,
+				   efi_var_buf->length -
+				   sizeof(struct efi_var_file));
+
+	return EFI_SUCCESS;
+}
+
+u64 __efi_runtime efi_var_mem_free(void)
+{
+	return EFI_VAR_BUF_SIZE - efi_var_buf->length -
+	       sizeof(struct efi_var_entry);
+}
+
+/**
+ * efi_var_mem_bs_del() - delete boot service only variables
+ */
+static void efi_var_mem_bs_del(void)
+{
+	struct efi_var_entry *var = efi_var_buf->var;
+
+	for (;;) {
+		struct efi_var_entry *last;
+
+		last = (struct efi_var_entry *)
+		       ((uintptr_t)efi_var_buf + efi_var_buf->length);
+		if (var >= last)
+			break;
+		if (var->attr & EFI_VARIABLE_RUNTIME_ACCESS) {
+			u16 *data;
+
+			/* skip variable */
+			for (data = var->name; *data; ++data)
+				;
+			++data;
+			var = (struct efi_var_entry *)
+			      ALIGN((uintptr_t)data + var->length, 8);
+		} else {
+			/* delete variable */
+			efi_var_mem_del(var);
+		}
+	}
+}
+
+/**
+ * efi_var_mem_notify_exit_boot_services() - ExitBootService callback
+ *
+ * @event:	callback event
+ * @context:	callback context
+ */
+static void EFIAPI __efi_runtime
+efi_var_mem_notify_exit_boot_services(struct efi_event *event, void *context)
+{
+	EFI_ENTRY("%p, %p", event, context);
+
+	/* Delete boot service only variables */
+	efi_var_mem_bs_del();
+
+	EFI_EXIT(EFI_SUCCESS);
+}
+
+/**
+ * efi_var_mem_notify_exit_boot_services() - SetVirtualMemoryMap callback
+ *
+ * @event:	callback event
+ * @context:	callback context
+ */
+static void EFIAPI __efi_runtime
+efi_var_mem_notify_virtual_address_map(struct efi_event *event, void *context)
+{
+	efi_convert_pointer(0, (void **)&efi_var_buf);
+}
+
+efi_status_t efi_var_mem_init(void)
+{
+	u64 memory;
+	efi_status_t ret;
+	struct efi_event *event;
+
+	ret = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES,
+				 EFI_RUNTIME_SERVICES_DATA,
+				 efi_size_in_pages(EFI_VAR_BUF_SIZE),
+				 &memory);
+	if (ret != EFI_SUCCESS)
+		return ret;
+	efi_var_buf = (struct efi_var_file *)(uintptr_t)memory;
+	memset(efi_var_buf, 0, EFI_VAR_BUF_SIZE);
+	efi_var_buf->magic = EFI_VAR_FILE_MAGIC;
+	efi_var_buf->length = (uintptr_t)efi_var_buf->var -
+			      (uintptr_t)efi_var_buf;
+	/* crc32 for 0 bytes = 0 */
+
+	ret = efi_create_event(EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_CALLBACK,
+			       efi_var_mem_notify_exit_boot_services, NULL,
+			       NULL, &event);
+	if (ret != EFI_SUCCESS)
+		return ret;
+	ret = efi_create_event(EVT_SIGNAL_VIRTUAL_ADDRESS_CHANGE, TPL_CALLBACK,
+			       efi_var_mem_notify_virtual_address_map, NULL,
+			       NULL, &event);
+	if (ret != EFI_SUCCESS)
+		return ret;
+	return ret;
+}