[PATCH 1/3] fit: support signing with only an engine_id

[Quentin Schulz <foss+uboot@0leil.net>]

From: Quentin Schulz <quentin.schulz@cherry.de>

Currently, when one wants to use an OpenSSL engine to sign a FIT image,
one needs to pass a keydir (via -k) to mkimage which will then be
prepended to the value of the key-name-hint before being passed as
key_id argument to the OpenSSL Engine API, or pass a keyfile (via -G) to
mkimage.

My OpenSSL engine only has "slots" which are not mapped like
directories, so using keydir is not proper, though I could simply have
-k '' I guess but this won't work currently with binman anyway.

Additionally, passing a keyfile when using an engine doesn't make sense
as the key is stored in the engine.

Let simply allow FIT images be signed if both keydir and keyfile are
missing but an engine is to be used.

The keyname member is already filled by looking at key-name-hint
property in the FIT and passed verbatim to the engine, which is exactly
what is needed here.

Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
---
 tools/fit_image.c  | 3 ++-
 tools/image-host.c | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tools/fit_image.c b/tools/fit_image.c
index 0306333141e..694bb927c7d 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -26,7 +26,8 @@ static struct legacy_img_hdr header;
 
 static int fit_estimate_hash_sig_size(struct image_tool_params *params, const char *fname)
 {
-	bool signing = IMAGE_ENABLE_SIGN && (params->keydir || params->keyfile);
+	bool signing = IMAGE_ENABLE_SIGN &&
+		(params->keydir || params->keyfile || params->engine_id);
 	struct stat sbuf;
 	void *fdt;
 	int fd;
diff --git a/tools/image-host.c b/tools/image-host.c
index 21dd7f2d922..54df86316ae 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -696,7 +696,7 @@ int fit_image_add_verification_data(const char *keydir, const char *keyfile,
 			     strlen(FIT_HASH_NODENAME))) {
 			ret = fit_image_process_hash(fit, image_name, noffset,
 						data, size);
-		} else if (IMAGE_ENABLE_SIGN && (keydir || keyfile) &&
+		} else if (IMAGE_ENABLE_SIGN && (keydir || keyfile || engine_id) &&
 			   !strncmp(node_name, FIT_SIG_NODENAME,
 				strlen(FIT_SIG_NODENAME))) {
 			ret = fit_image_process_sig(keydir, keyfile, keydest,
@@ -1366,7 +1366,7 @@ int fit_add_verification_data(const char *keydir, const char *keyfile,
 	}
 
 	/* If there are no keys, we can't sign configurations */
-	if (!IMAGE_ENABLE_SIGN || !(keydir || keyfile))
+	if (!IMAGE_ENABLE_SIGN || !(keydir || keyfile || engine_id))
 		return 0;
 
 	/* Find configurations parent node offset */

-- 
2.51.0