mkimage: Add -K to write public keys to an FDT blob

FIT image verification requires public keys. Add a convenient option to
mkimage to write the public keys to an FDT blob when it uses then for
signing an image. This allows us to use:

   mkimage -f test.its -K dest.dtb -k keys test.fit

and have the signatures written to test.fit and the corresponding public
keys written to dest.dtb. Then dest.dtb can be used as the control FDT
for U-Boot (CONFIG_OF_CONTROL), thus providing U-Boot with access to the
public keys it needs.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>

3 files changed, 28 insertions, 4 deletions

diff --git a/tools/fit_image.c b/tools/fit_image.c
index 339e0f8..b17fa2d 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -105,9 +105,11 @@ static int fit_handle_file (struct mkimage_params *params)
 {
 	char tmpfile[MKIMAGE_MAX_TMPFILE_LEN];
 	char cmd[MKIMAGE_MAX_DTC_CMDLINE_LEN];
-	int tfd;
+	int tfd, destfd = 0;
+	void *dest_blob = NULL;
 	struct stat sbuf;
 	void *ptr;
+	off_t destfd_size = 0;
 
 	/* Flattened Image Tree (FIT) format  handling */
 	debug ("FIT format handling\n");
@@ -132,12 +134,20 @@ static int fit_handle_file (struct mkimage_params *params)
 		goto err_system;
 	}
 
+	if (params->keydest) {
+		destfd = mmap_fdt(params, params->keydest, &dest_blob, &sbuf);
+		if (destfd < 0)
+			goto err_keydest;
+		destfd_size = sbuf.st_size;
+	}
+
 	tfd = mmap_fdt(params, tmpfile, &ptr, &sbuf);
 	if (tfd < 0)
 		goto err_mmap;
 
 	/* set hashes for images in the blob */
-	if (fit_add_verification_data(params->keydir, NULL, ptr, NULL, 0)) {
+	if (fit_add_verification_data(params->keydir, dest_blob, ptr,
+				      NULL, 0)) {
 		fprintf (stderr, "%s Can't add hashes to FIT blob",
 				params->cmdname);
 		goto err_add_hashes;
@@ -153,6 +163,10 @@ static int fit_handle_file (struct mkimage_params *params)
 
 	munmap ((void *)ptr, sbuf.st_size);
 	close (tfd);
+	if (dest_blob) {
+		munmap(dest_blob, destfd_size);
+		close(destfd);
+	}
 
 	if (rename (tmpfile, params->imagefile) == -1) {
 		fprintf (stderr, "%s: Can't rename %s to %s: %s\n",
@@ -168,6 +182,9 @@ err_add_timestamp:
 err_add_hashes:
 	munmap(ptr, sbuf.st_size);
 err_mmap:
+	if (dest_blob)
+		munmap(dest_blob, destfd_size);
+err_keydest:
 err_system:
 	unlink(tmpfile);
 	return -1;
diff --git a/tools/mkimage.c b/tools/mkimage.c
index def7df2..3760392 100644
--- a/tools/mkimage.c
+++ b/tools/mkimage.c
@@ -253,6 +253,11 @@ main (int argc, char **argv)
 					usage();
 				params.keydir = *++argv;
 				goto NXTARG;
+			case 'K':
+				if (--argc <= 0)
+					usage();
+				params.keydest = *++argv;
+				goto NXTARG;
 			case 'n':
 				if (--argc <= 0)
 					usage ();
@@ -633,8 +638,9 @@ usage ()
 	fprintf(stderr, "          -D => set options for device tree compiler\n"
 			"          -f => input filename for FIT source\n");
 #ifdef CONFIG_FIT_SIGNATURE
-	fprintf(stderr, "Signing / verified boot options: [-k keydir]\n"
-			"          -k => set directory containing private keys\n");
+	fprintf(stderr, "Signing / verified boot options: [-k keydir] [-K dtb]\n"
+			"          -k => set directory containing private keys\n"
+			"          -K => write public keys to this .dtb file\n");
 #else
 	fprintf(stderr, "Signing / verified boot not supported (CONFIG_FIT_SIGNATURE undefined)\n");
 #endif
diff --git a/tools/mkimage.h b/tools/mkimage.h
index 059e124..63b9b4f 100644
--- a/tools/mkimage.h
+++ b/tools/mkimage.h
@@ -88,6 +88,7 @@ struct mkimage_params {
 	char *imagefile;
 	char *cmdname;
 	const char *keydir;	/* Directory holding private keys */
+	const char *keydest;	/* Destination .dtb for public key */
 };
 
 /*