Patch proposal - mkimage: fit: Support signed conf 'auto' FITs
Sean Anderson
sean.anderson at seco.com
Mon Nov 28 16:45:52 CET 2022
On 11/22/22 21:09, Simon Glass wrote:
> Hi Pegorer,
>
> On Sat, 19 Nov 2022 at 11:01, Pegorer Massimo <Massimo.Pegorer at 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 at 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 at 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
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