mkimage: Support signing 'auto' FITs

This adds support for signing images in auto-generated FITs. To do this,
we need to add a signature node. The algorithm name property already has
its own option, but we need one for the key name hint. We could have
gone the -G route and added an explicit name for the public key (like
what is done for the private key). However, many places assume the
public key can be constructed from the key dir and hint, and I don't
want to do the refactoring necessary.

As a consequence of this, it is now easier to add public keys to an
existing image without signing something. This could be done all along,
but now you don't have to create an its just to do it. Ideally, we
wouldn't create a FIT at the end. This could be done by calling
fit_image_setup_sig/info.crypto->add_verify_data directly.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>

3 files changed, 39 insertions, 8 deletions

diff --git a/tools/fit_image.c b/tools/fit_image.c
index 1884a2e..979f241 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -199,15 +199,36 @@ static void get_basename(char *str, int size, const char *fname)
 }
 
 /**
- * add_crc_node() - Add a hash node to request a CRC checksum for an image
+ * add_hash_node() - Add a hash or signature node
  *
+ * @params: Image parameters
  * @fdt: Device tree to add to (in sequential-write mode)
+ *
+ * If there is a key name hint, try to sign the images. Otherwise, just add a
+ * CRC.
+ *
+ * Return: 0 on success, or -1 on failure
  */
-static void add_crc_node(void *fdt)
+static int add_hash_node(struct image_tool_params *params, void *fdt)
 {
-	fdt_begin_node(fdt, "hash-1");
-	fdt_property_string(fdt, FIT_ALGO_PROP, "crc32");
+	if (params->keyname) {
+		if (!params->algo_name) {
+			fprintf(stderr,
+				"%s: Algorithm name must be specified\n",
+				params->cmdname);
+			return -1;
+		}
+
+		fdt_begin_node(fdt, "signature-1");
+		fdt_property_string(fdt, FIT_ALGO_PROP, params->algo_name);
+		fdt_property_string(fdt, FIT_KEY_HINT, params->keyname);
+	} else {
+		fdt_begin_node(fdt, "hash-1");
+		fdt_property_string(fdt, FIT_ALGO_PROP, "crc32");
+	}
+
 	fdt_end_node(fdt);
+	return 0;
 }
 
 /**
@@ -248,7 +269,9 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 	ret = fdt_property_file(params, fdt, FIT_DATA_PROP, params->datafile);
 	if (ret)
 		return ret;
-	add_crc_node(fdt);
+	ret = add_hash_node(params, fdt);
+	if (ret)
+		return ret;
 	fdt_end_node(fdt);
 
 	/* Now the device tree files if available */
@@ -271,7 +294,9 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 				    genimg_get_arch_short_name(params->arch));
 		fdt_property_string(fdt, FIT_COMP_PROP,
 				    genimg_get_comp_short_name(IH_COMP_NONE));
-		add_crc_node(fdt);
+		ret = add_hash_node(params, fdt);
+		if (ret)
+			return ret;
 		fdt_end_node(fdt);
 	}
 
@@ -289,7 +314,9 @@ static int fit_write_images(struct image_tool_params *params, char *fdt)
 					params->fit_ramdisk);
 		if (ret)
 			return ret;
-		add_crc_node(fdt);
+		ret = add_hash_node(params, fdt);
+		if (ret)
+			return ret;
 		fdt_end_node(fdt);
 	}
 
diff --git a/tools/imagetool.h b/tools/imagetool.h
index 05dd94d..ca7c2e4 100644
--- a/tools/imagetool.h
+++ b/tools/imagetool.h
@@ -71,6 +71,7 @@ struct image_tool_params {
 	const char *keydir;	/* Directory holding private keys */
 	const char *keydest;	/* Destination .dtb for public key */
 	const char *keyfile;	/* Filename of private or public key */
+	const char *keyname;	/* Key name "hint" */
 	const char *comment;	/* Comment to add to signature node */
 	/* Algorithm name to use for hashing/signing or NULL to use the one
 	 * specified in the its */
diff --git a/tools/mkimage.c b/tools/mkimage.c
index 5c6a60e..0e1198b 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -119,6 +119,7 @@ static void usage(const char *msg)
 		"Signing / verified boot options: [-k keydir] [-K dtb] [ -c <comment>] [-p addr] [-r] [-N engine]\n"
 		"          -k => set directory containing private keys\n"
 		"          -K => write public keys to this .dtb file\n"
+		"          -g => set key name hint\n"
 		"          -G => use this signing key (in lieu of -k)\n"
 		"          -c => add comment in signature node\n"
 		"          -F => re-sign existing FIT image\n"
@@ -163,7 +164,7 @@ static void process_args(int argc, char **argv)
 	int opt;
 
 	while ((opt = getopt(argc, argv,
-		   "a:A:b:B:c:C:d:D:e:Ef:FG:k:i:K:ln:N:p:o:O:rR:qstT:vVx")) != -1) {
+		   "a:A:b:B:c:C:d:D:e:Ef:Fg:G:k:i:K:ln:N:p:o:O:rR:qstT:vVx")) != -1) {
 		switch (opt) {
 		case 'a':
 			params.addr = strtoull(optarg, &ptr, 16);
@@ -239,6 +240,8 @@ static void process_args(int argc, char **argv)
 			params.type = IH_TYPE_FLATDT;
 			params.fflag = 1;
 			break;
+		case 'g':
+			params.keyname = optarg;
 		case 'G':
 			params.keyfile = optarg;
 			break;