Normally, multiple public keys can be provided and U-Boot is not required to use all of them for verification. This is because some images may not be signed, or may be optionally signed.
But we still need a mechanism to determine when a key must be used. This feature cannot be implemented in the FIT itself, since anyone could change it to mark a key as optional. The requirement for key verification must go in with the public keys, in a place that is protected from modification.
Add a -r option which tells mkimage to mark all keys that it uses for signing as 'required'.
If some keys are optional and some are required, run mkimage several times (perhaps with different key directories if some keys are very secret) using the -F flag to update an existing FIT.
Signed-off-by: Simon Glass sjg@chromium.org Reviewed-by: Marek Vasut marex@denx.de --- Changes in v3: None Changes in v2: - Adjust mkimage help to separate out signing options - Rebase on previous patches
doc/mkimage.1 | 6 ++++++ tools/fit_image.c | 9 +++++---- tools/mkimage.c | 8 ++++++-- tools/mkimage.h | 1 + 4 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/doc/mkimage.1 b/doc/mkimage.1 index b67a351..14374da 100644 --- a/doc/mkimage.1 +++ b/doc/mkimage.1 @@ -133,6 +133,12 @@ the corresponding public key is written into this file for for run-time verification. Typically the file here is the device tree binary used by CONFIG_OF_CONTROL in U-Boot.
+.TP +.BI "-r +Specifies that keys used to sign the FIT are required. This means that they +must be verified for the image to boot. Without this option, the verification +will be optional (useful for testing but not for release). + .SH EXAMPLES
List image information: diff --git a/tools/fit_image.c b/tools/fit_image.c index d48f571..281c2bd 100644 --- a/tools/fit_image.c +++ b/tools/fit_image.c @@ -152,10 +152,11 @@ static int fit_handle_file (struct mkimage_params *params) goto err_mmap;
/* set hashes for images in the blob */ - if (fit_add_verification_data(params->keydir, dest_blob, ptr, - params->comment, 0)) { - fprintf (stderr, "%s Can't add hashes to FIT blob", - params->cmdname); + if (fit_add_verification_data(params->keydir, + dest_blob, ptr, params->comment, + params->require_keys)) { + fprintf(stderr, "%s Can't add hashes to FIT blob\n", + params->cmdname); goto err_add_hashes; }
diff --git a/tools/mkimage.c b/tools/mkimage.c index b3b45a4..d312844 100644 --- a/tools/mkimage.c +++ b/tools/mkimage.c @@ -270,6 +270,9 @@ main (int argc, char **argv) usage (); params.imagename = *++argv; goto NXTARG; + case 'r': + params.require_keys = 1; + break; case 'R': if (--argc <= 0) usage(); @@ -645,11 +648,12 @@ 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] [-K dtb] [ -c <comment>]\n" + fprintf(stderr, "Signing / verified boot options: [-k keydir] [-K dtb] [ -c <comment>] [-r]\n" " -k => set directory containing private keys\n" " -K => write public keys to this .dtb file\n" " -c => add comment in signature node\n" - " -F => re-sign existing FIT image\n"); + " -F => re-sign existing FIT image\n" + " -r => mark keys used as 'required' in dtb\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 ab8baf8..1d9984e 100644 --- a/tools/mkimage.h +++ b/tools/mkimage.h @@ -90,6 +90,7 @@ struct mkimage_params { const char *keydir; /* Directory holding private keys */ const char *keydest; /* Destination .dtb for public key */ const char *comment; /* Comment to add to signature node */ + int require_keys; /* 1 to mark signing keys as 'required' */ };
/*