bl_common.c

/*
 * Copyright (c) 2013-2018, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <arch.h>
#include <arch_helpers.h>
#include <assert.h>
#include <auth_mod.h>
#include <bl_common.h>
#include <debug.h>
#include <errno.h>
#include <io_storage.h>
#include <platform.h>
#include <string.h>
#include <utils.h>
#include <xlat_tables_defs.h>

#if TRUSTED_BOARD_BOOT
# ifdef DYN_DISABLE_AUTH
static int disable_auth;

/******************************************************************************
 * API to dynamically disable authentication. Only meant for development
 * systems. This is only invoked if DYN_DISABLE_AUTH is defined.
 *****************************************************************************/
void dyn_disable_auth(void)
{
	INFO("Disabling authentication of images dynamically\n");
	disable_auth = 1;
}
# endif /* DYN_DISABLE_AUTH */

/******************************************************************************
 * Function to determine whether the authentication is disabled dynamically.
 *****************************************************************************/
static int dyn_is_auth_disabled(void)
{
# ifdef DYN_DISABLE_AUTH
	return disable_auth;
# else
	return 0;
# endif
}
#endif /* TRUSTED_BOARD_BOOT */

uintptr_t page_align(uintptr_t value, unsigned dir)
{
	/* Round up the limit to the next page boundary */
	if (value & (PAGE_SIZE - 1)) {
		value &= ~(PAGE_SIZE - 1);
		if (dir == UP)
			value += PAGE_SIZE;
	}

	return value;
}

/******************************************************************************
 * Determine whether the memory region delimited by 'addr' and 'size' is free,
 * given the extents of free memory.
 * Return 1 if it is free, 0 if it is not free or if the input values are
 * invalid.
 *****************************************************************************/
int is_mem_free(uintptr_t free_base, size_t free_size,
		uintptr_t addr, size_t size)
{
	uintptr_t free_end, requested_end;

	/*
	 * Handle corner cases first.
	 *
	 * The order of the 2 tests is important, because if there's no space
	 * left (i.e. free_size == 0) but we don't ask for any memory
	 * (i.e. size == 0) then we should report that the memory is free.
	 */
	if (size == 0)
		return 1;	/* A zero-byte region is always free */
	if (free_size == 0)
		return 0;

	/*
	 * Check that the end addresses don't overflow.
	 * If they do, consider that this memory region is not free, as this
	 * is an invalid scenario.
	 */
	if (check_uptr_overflow(free_base, free_size - 1))
		return 0;
	free_end = free_base + (free_size - 1);

	if (check_uptr_overflow(addr, size - 1))
		return 0;
	requested_end = addr + (size - 1);

	/*
	 * Finally, check that the requested memory region lies within the free
	 * region.
	 */
	return (addr >= free_base) && (requested_end <= free_end);
}

/* Generic function to return the size of an image */
size_t get_image_size(unsigned int image_id)
{
	uintptr_t dev_handle;
	uintptr_t image_handle;
	uintptr_t image_spec;
	size_t image_size = 0;
	int io_result;

	/* Obtain a reference to the image by querying the platform layer */
	io_result = plat_get_image_source(image_id, &dev_handle, &image_spec);
	if (io_result != 0) {
		WARN("Failed to obtain reference to image id=%u (%i)\n",
			image_id, io_result);
		return 0;
	}

	/* Attempt to access the image */
	io_result = io_open(dev_handle, image_spec, &image_handle);
	if (io_result != 0) {
		WARN("Failed to access image id=%u (%i)\n",
			image_id, io_result);
		return 0;
	}

	/* Find the size of the image */
	io_result = io_size(image_handle, &image_size);
	if ((io_result != 0) || (image_size == 0)) {
		WARN("Failed to determine the size of the image id=%u (%i)\n",
			image_id, io_result);
	}
	io_result = io_close(image_handle);
	/* Ignore improbable/unrecoverable error in 'close' */

	/* TODO: Consider maintaining open device connection from this
	 * bootloader stage
	 */
	io_result = io_dev_close(dev_handle);
	/* Ignore improbable/unrecoverable error in 'dev_close' */

	return image_size;
}

/*******************************************************************************
 * Internal function to load an image at a specific address given
 * an image ID and extents of free memory.
 *
 * If the load is successful then the image information is updated.
 *
 * Returns 0 on success, a negative error code otherwise.
 ******************************************************************************/
static int load_image(unsigned int image_id, image_info_t *image_data)
{
	uintptr_t dev_handle;
	uintptr_t image_handle;
	uintptr_t image_spec;
	uintptr_t image_base;
	size_t image_size;
	size_t bytes_read;
	int io_result;

	assert(image_data != NULL);
	assert(image_data->h.version >= VERSION_2);

	image_base = image_data->image_base;

	/* Obtain a reference to the image by querying the platform layer */
	io_result = plat_get_image_source(image_id, &dev_handle, &image_spec);
	if (io_result != 0) {
		WARN("Failed to obtain reference to image id=%u (%i)\n",
			image_id, io_result);
		return io_result;
	}

	/* Attempt to access the image */
	io_result = io_open(dev_handle, image_spec, &image_handle);
	if (io_result != 0) {
		WARN("Failed to access image id=%u (%i)\n",
			image_id, io_result);
		return io_result;
	}

	INFO("Loading image id=%u at address %p\n", image_id,
		(void *) image_base);

	/* Find the size of the image */
	io_result = io_size(image_handle, &image_size);
	if ((io_result != 0) || (image_size == 0)) {
		WARN("Failed to determine the size of the image id=%u (%i)\n",
			image_id, io_result);
		goto exit;
	}

	/* Check that the image size to load is within limit */
	if (image_size > image_data->image_max_size) {
		WARN("Image id=%u size out of bounds\n", image_id);
		io_result = -EFBIG;
		goto exit;
	}

	image_data->image_size = image_size;

	/* We have enough space so load the image now */
	/* TODO: Consider whether to try to recover/retry a partially successful read */
	io_result = io_read(image_handle, image_base, image_size, &bytes_read);
	if ((io_result != 0) || (bytes_read < image_size)) {
		WARN("Failed to load image id=%u (%i)\n", image_id, io_result);
		goto exit;
	}

	INFO("Image id=%u loaded: %p - %p\n", image_id, (void *) image_base,
	     (void *) (image_base + image_size));

exit:
	io_close(image_handle);
	/* Ignore improbable/unrecoverable error in 'close' */

	/* TODO: Consider maintaining open device connection from this bootloader stage */
	io_dev_close(dev_handle);
	/* Ignore improbable/unrecoverable error in 'dev_close' */

	return io_result;
}

static int load_auth_image_internal(unsigned int image_id,
				    image_info_t *image_data,
				    int is_parent_image)
{
	int rc;

#if TRUSTED_BOARD_BOOT
	if (dyn_is_auth_disabled() == 0) {
		unsigned int parent_id;

		/* Use recursion to authenticate parent images */
		rc = auth_mod_get_parent_id(image_id, &parent_id);
		if (rc == 0) {
			rc = load_auth_image_internal(parent_id, image_data, 1);
			if (rc != 0) {
				return rc;
			}
		}
	}
#endif /* TRUSTED_BOARD_BOOT */

	/* Load the image */
	rc = load_image(image_id, image_data);
	if (rc != 0) {
		return rc;
	}

#if TRUSTED_BOARD_BOOT
	if (dyn_is_auth_disabled() == 0) {
		/* Authenticate it */
		rc = auth_mod_verify_img(image_id,
					 (void *)image_data->image_base,
					 image_data->image_size);
		if (rc != 0) {
			/* Authentication error, zero memory and flush it right away. */
			zero_normalmem((void *)image_data->image_base,
			       image_data->image_size);
			flush_dcache_range(image_data->image_base,
					   image_data->image_size);
			return -EAUTH;
		}
	}
#endif /* TRUSTED_BOARD_BOOT */

	/*
	 * Flush the image to main memory so that it can be executed later by
	 * any CPU, regardless of cache and MMU state. If TBB is enabled, then
	 * the file has been successfully loaded and authenticated and flush
	 * only for child images, not for the parents (certificates).
	 */
	if (!is_parent_image) {
		flush_dcache_range(image_data->image_base,
				   image_data->image_size);
	}


	return 0;
}

/*******************************************************************************
 * Generic function to load and authenticate an image. The image is actually
 * loaded by calling the 'load_image()' function. Therefore, it returns the
 * same error codes if the loading operation failed, or -EAUTH if the
 * authentication failed. In addition, this function uses recursion to
 * authenticate the parent images up to the root of trust.
 ******************************************************************************/
int load_auth_image(unsigned int image_id, image_info_t *image_data)
{
	int err;

	do {
		err = load_auth_image_internal(image_id, image_data, 0);
	} while (err != 0 && plat_try_next_boot_source());

	return err;
}

/*******************************************************************************
 * Print the content of an entry_point_info_t structure.
 ******************************************************************************/
void print_entry_point_info(const entry_point_info_t *ep_info)
{
	INFO("Entry point address = %p\n", (void *)ep_info->pc);
	INFO("SPSR = 0x%x\n", ep_info->spsr);

#define PRINT_IMAGE_ARG(n)					\
	VERBOSE("Argument #" #n " = 0x%llx\n",			\
		(unsigned long long) ep_info->args.arg##n)

	PRINT_IMAGE_ARG(0);
	PRINT_IMAGE_ARG(1);
	PRINT_IMAGE_ARG(2);
	PRINT_IMAGE_ARG(3);
#ifndef AARCH32
	PRINT_IMAGE_ARG(4);
	PRINT_IMAGE_ARG(5);
	PRINT_IMAGE_ARG(6);
	PRINT_IMAGE_ARG(7);
#endif
#undef PRINT_IMAGE_ARG
}