image: Add support for signing of FIT configurations

While signing images is useful, it does not provide complete protection
against several types of attack. For example, it it possible to create a
FIT with the same signed images, but with the configuration changed such
that a different one is selected (mix and match attack). It is also possible
to substitute a signed image from an older FIT version into a newer FIT
(roll-back attack).

Add support for signing of FIT configurations using the libfdt's region
support.

Please see doc/uImage.FIT/signature.txt for more information.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/image.h b/include/image.h
index da7b9a04f1..261491880e 100644
--- a/include/image.h
+++ b/include/image.h
@@ -964,6 +964,22 @@ int fit_image_verify_required_sigs(const void *fit, int image_noffset,
 int fit_image_check_sig(const void *fit, int noffset, const void *data,
 		size_t size, int required_keynode, char **err_msgp);
 
+/**
+ * fit_region_make_list() - Make a list of regions to hash
+ *
+ * Given a list of FIT regions (offset, size) provided by libfdt, create
+ * a list of regions (void *, size) for use by the signature creationg
+ * and verification code.
+ *
+ * @fit:		FIT image to process
+ * @fdt_regions:	Regions as returned by libfdt
+ * @count:		Number of regions returned by libfdt
+ * @region:		Place to put list of regions (NULL to allocate it)
+ * @return pointer to list of regions, or NULL if out of memory
+ */
+struct image_region *fit_region_make_list(const void *fit,
+		struct fdt_region *fdt_regions, int count,
+		struct image_region *region);
 
 static inline int fit_image_check_target_arch(const void *fdt, int node)
 {