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

[Pegorer Massimo <Massimo.Pegorer@vimar.com>]

Hi Simon,

> Da: Simon Glass <sjg@chromium.org>
> Inviato: mercoledì 23 novembre 2022 03:09
> 
> 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 ++++++++++++++----
> >  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"))
> > +                               params.require_keys = 1;
> > +                       else if (!strcmp(optarg, "conf"))
> > +                               params.require_keys = 2;
> > +                       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.

Yes, seems better. Do you think I can move the image_tool_params.auto_its
from bool to int type, to carry more than just a boolean value, or do you
prefer a new 'flag' to be added to image_tool_params? The first is my
preferred one if nobody complain.

Best regards,
Massimo

> Regards,
> SImon