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, 45 insertions, 0 deletions

diff --git a/doc/uImage.FIT/sign-configs.its b/doc/uImage.FIT/sign-configs.its
new file mode 100644
index 0000000..3c17f04
--- /dev/null
+++ b/doc/uImage.FIT/sign-configs.its
@@ -0,0 +1,45 @@
+/dts-v1/;
+
+/ {
+	description = "Chrome OS kernel image with one or more FDT blobs";
+	#address-cells = <1>;
+
+	images {
+		kernel@1 {
+			data = /incbin/("test-kernel.bin");
+			type = "kernel_noload";
+			arch = "sandbox";
+			os = "linux";
+			compression = "lzo";
+			load = <0x4>;
+			entry = <0x8>;
+			kernel-version = <1>;
+			hash@1 {
+				algo = "sha1";
+			};
+		};
+		fdt@1 {
+			description = "snow";
+			data = /incbin/("sandbox-kernel.dtb");
+			type = "flat_dt";
+			arch = "sandbox";
+			compression = "none";
+			fdt-version = <1>;
+			hash@1 {
+				algo = "sha1";
+			};
+		};
+	};
+	configurations {
+		default = "conf@1";
+		conf@1 {
+			kernel = "kernel@1";
+			fdt = "fdt@1";
+			signature@1 {
+				algo = "sha1,rsa2048";
+				key-name-hint = "dev";
+				sign-images = "fdt", "kernel";
+			};
+		};
+	};
+};