Re: Patch proposal - mkimage: fit: Support signed conf 'auto' FITs

On 11/22/22 21:09, Simon Glass wrote:

Hi Pegorer,

On Sat, 19 Nov 2022 at 11:01, Pegorer Massimo Massimo.Pegorer@vimar.com wrote:

...

Commit 87b0af9317cb4105f3f29cb0a4c28c7cd87ea65f added support for signing auto-generated (mkimage -f auto) FIT. Unfortunately, this signs 'images' subnodes but not 'configurations' ones. Following patch is a proposal to support also 'configurations' signing + 'images' hashing, as an alternative to 'images' signing, with 'auto' FIT. For this purpose, a new optional argument is added to mkimage '-r' option: any other better idea?

=====

From 8c8c8f421d541cc2eccb50490a57e86b81dc8df2 Mon Sep 17 00:00:00 2001 From: Massimo Pegorer massimo.pegorer@vimar.com Date: Sat, 19 Nov 2022 16:25:58 +0100 Subject: [PATCH] mkimage: fit: Support signed conf 'auto' FITs

Extend support for signing in auto-generated FITs. Previously, it was possible to sign 'images' subnodes in auto FIT, but not 'configurations' subnodes. Consequently, usage with -K and -r options (i.e. write keys as 'required' in a .dtb file) resulted in adding a signature node with required = "image" property in the dtb.

This patch allows usage of an optional argument with -r option to select which subnodes, 'images' ones or 'configurations' ones, have to be signed (in the second case 'images' subnodes are hashed): with '-r' or '-rimage' the firsts are signed, while with '-rconf' the seconds; argument values different than 'image' and 'conf' are invalid.

Example to write a key with required = "conf" attribute into a dtb file:

mkimage -f auto -rconf -d /dev/null -K <dtb-file> -o <algo> \ -g <key-name-hint> -k <path-to-key-file> <dummy-itb-file>

Signed-off-by: Massimo Pegorer massimo.pegorer@vimar.com

tools/fit_image.c | 25 +++++++++++++++++-------- tools/mkimage.c | 18 ++++++++++++++----

Remember to update the man page for your next revision.

...

2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/tools/fit_image.c b/tools/fit_image.c index 923a9755b7..c78d83d509 100644 --- a/tools/fit_image.c +++ b/tools/fit_image.c @@ -199,19 +199,22 @@ static void get_basename(char *str, int size, const char *fname) }

/**

• • add_hash_node() - Add a hash or signature node

• • add_hash_or_sign_node() - Add a hash or signature node
  • @params: Image parameters
  • @fdt: Device tree to add to (in sequential-write mode)
• • @do_add_hash: true to add hash even if key name hint is provided

• • If there is a key name hint, try to sign the images. Otherwise, just add a
• • CRC.

• • If do_add_hash is false (default) and there is a key name hint, try to add
• • a sign node to parent. Otherwise, just add a CRC. Rationale: if conf have
• • to be signed, image/dt have to be hashed even if there is a key name hint.
  • Return: 0 on success, or -1 on failure
  */

-static int add_hash_node(struct image_tool_params *params, void *fdt) +static int add_hash_or_sig_node(struct image_tool_params *params, void *fdt,

•                           bool do_add_hash)
  

{

•   if (params->keyname) {
  

•   if (!do_add_hash && params->keyname) {
            if (!params->algo_name) {
                    fprintf(stderr,
                            "%s: Algorithm name must be specified\n",
  

@@ -269,7 +272,7 @@ 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;

•   ret = add_hash_node(params, fdt);
  

•   ret = add_hash_or_sig_node(params, fdt, (params->require_keys == 2));
    if (ret)
            return ret;
    fdt_end_node(fdt);
  

@@ -294,7 +297,8 @@ 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));

•           ret = add_hash_node(params, fdt);
  

•           ret = add_hash_or_sig_node(params, fdt,
  

•                                      (params->require_keys == 2));
            if (ret)
                    return ret;
            fdt_end_node(fdt);
  

@@ -314,7 +318,8 @@ static int fit_write_images(struct image_tool_params *params, char *fdt) params->fit_ramdisk); if (ret) return ret;

•           ret = add_hash_node(params, fdt);
  

•           ret = add_hash_or_sig_node(params, fdt,
  

•                                      (params->require_keys == 2));
            if (ret)
                    return ret;
            fdt_end_node(fdt);
  

@@ -366,6 +371,8 @@ static void fit_write_configs(struct image_tool_params *params, char *fdt)

            snprintf(str, sizeof(str), FIT_FDT_PROP "-%d", upto);
            fdt_property_string(fdt, FIT_FDT_PROP, str);

•           if (params->require_keys == 2)
  

•                   add_hash_or_sig_node(params, fdt, false);
            fdt_end_node(fdt);
    }
  
  

@@ -378,6 +385,8 @@ static void fit_write_configs(struct image_tool_params *params, char *fdt) if (params->fit_ramdisk) fdt_property_string(fdt, FIT_RAMDISK_PROP, FIT_RAMDISK_PROP "-1");

•           if (params->require_keys == 2)
  

•                   add_hash_or_sig_node(params, fdt, false);
  
            fdt_end_node(fdt);
    }
  

diff --git a/tools/mkimage.c b/tools/mkimage.c index 30c6df7708..4d4f128b54 100644 --- a/tools/mkimage.c +++ b/tools/mkimage.c @@ -125,7 +125,7 @@ static void usage(const char *msg) " -c => add comment in signature node\n" " -F => re-sign existing FIT image\n" " -p => place external data at a static position\n"

•           "          -r => mark keys used as 'required' in dtb\n"
  

•           "          -r => mark keys used as 'required' in dtb (-rconf for 'auto' FIT with signed config)\n"
            "          -N => openssl engine to use for signing\n"
            "          -o => algorithm to use for signing\n");
  

#else @@ -159,7 +159,7 @@ static int add_content(int type, const char *fname) }

static const char optstring[] =

•   "a:A:b:B:c:C:d:D:e:Ef:Fg:G:i:k:K:ln:N:o:O:p:qrR:stT:vVx";
  

•   "a:A:b:B:c:C:d:D:e:Ef:Fg:G:i:k:K:ln:N:o:O:p:qr::R:stT:vVx";
  
  

static const struct option longopts[] = { { "load-address", required_argument, NULL, 'a' }, @@ -187,7 +187,7 @@ static const struct option longopts[] = { { "os", required_argument, NULL, 'O' }, { "position", required_argument, NULL, 'p' }, { "quiet", no_argument, NULL, 'q' },

•   { "key-required", no_argument, NULL, 'r' },
  

•   { "key-required", optional_argument, NULL, 'r' },
    { "secondary-config", required_argument, NULL, 'R' },
    { "no-copy", no_argument, NULL, 's' },
    { "touch", no_argument, NULL, 't' },
  

@@ -326,7 +326,12 @@ static void process_args(int argc, char **argv) params.quiet = 1; break; case 'r':

•                   params.require_keys = 1;
  

•                   if (!optarg || !strcmp(optarg, "image"))
  

The default should be "conf", as that is the current behavior.

...

•                           params.require_keys = 1;
  

•                   else if (!strcmp(optarg, "conf"))
  

•                           params.require_keys = 2;
  

Please use an enum instead of 1/2/etc.

Can we also support "both"?

...

•                   else
  

•                           usage("Invalid key-required option argument");
                    break;
            case 'R':
                    /*
  

@@ -370,6 +375,11 @@ static void process_args(int argc, char **argv) if (optind < argc) params.imagefile = argv[optind];

•   if (params.require_keys == 2)
  

•           if (!params.auto_its || !params.keyname || !params.algo_name)
  

•                   usage("Auto FIT with signed config requires -f auto "
  

•                           "-rconf -g <key name hint> -o <algorithm>");
  

•   /*
     * For auto-generated FIT images we need to know the image type to put
     * in the FIT, which is separate from the file's image type (which
  

-- 2.34.1

I think this is a reasonable feature, but how about using '-f auto-conf' as the way to select this feature? The '-r' argument is intended to indicate that the keys are required to be verified.

I think that extending -r with an argument is reasonable here. There's no way to specify required = "image" either...

--Sean