[PATCH 2/5] lib: ecdsa: Add skeleton to implement ecdsa verification in u-boot

[Alex G.]

Hi Patrick,

On 2/9/21 9:11 AM, Patrick DELAUNAY wrote:
> Hi,
> 
> On 1/11/21 4:41 PM, Alexandru Gagniuc wrote:
>> Prepare the source tree for accepting implementations of the ECDSA
>> algorithm. This patch deals with the boring aspects of Makefiles and
>> Kconfig files.
>>
>> Signed-off-by: Alexandru Gagniuc<mr.nuke.me at gmail.com>
>> ---
>>   include/image.h          | 10 +++++-----
>>   include/u-boot/rsa.h     |  2 +-
>>   lib/Kconfig              |  1 +
>>   lib/Makefile             |  1 +
>>   lib/ecdsa/Kconfig        | 23 +++++++++++++++++++++++
>>   lib/ecdsa/Makefile       |  1 +
>>   lib/ecdsa/ecdsa-verify.c | 13 +++++++++++++
>>   7 files changed, 45 insertions(+), 6 deletions(-)
>>   create mode 100644 lib/ecdsa/Kconfig
>>   create mode 100644 lib/ecdsa/Makefile
>>   create mode 100644 lib/ecdsa/ecdsa-verify.c
>>
>> diff --git a/include/image.h b/include/image.h
>> index 6628173dca..1d70ba0ece 100644
>> --- a/include/image.h
>> +++ b/include/image.h
>> @@ -1198,20 +1198,20 @@ int calculate_hash(const void *data, int 
>> data_len, const char *algo,
>>   #if defined(USE_HOSTCC)
>>   # if defined(CONFIG_FIT_SIGNATURE)
>>   #  define IMAGE_ENABLE_SIGN    1
>> -#  define IMAGE_ENABLE_VERIFY    1
>> +#  define IMAGE_ENABLE_VERIFY_RSA    1
>>   #  define IMAGE_ENABLE_VERIFY_ECDSA    1
>>   #  define FIT_IMAGE_ENABLE_VERIFY    1
>>   #  include <openssl/evp.h>
>>   # else
>>   #  define IMAGE_ENABLE_SIGN    0
>> -#  define IMAGE_ENABLE_VERIFY    0
>> +#  define IMAGE_ENABLE_VERIFY_RSA    0
>>   # define IMAGE_ENABLE_VERIFY_ECDSA    0
>>   #  define FIT_IMAGE_ENABLE_VERIFY    0
>>   # endif
>>   #else
>>   # define IMAGE_ENABLE_SIGN    0
>> -# define IMAGE_ENABLE_VERIFY        CONFIG_IS_ENABLED(RSA_VERIFY)
>> -# define IMAGE_ENABLE_VERIFY_ECDSA    0
>> +# define IMAGE_ENABLE_VERIFY_RSA    CONFIG_IS_ENABLED(RSA_VERIFY)
>> +# define IMAGE_ENABLE_VERIFY_ECDSA    CONFIG_IS_ENABLED(ECDSA_VERIFY)
> 
> here you are using CONFIG_IS_ENABLED.
> 
> This macro imply to test CONFIG_ECDSA_VERIFY or CONFIG_SPL_ECDSA_VERIFY 
> (for SPL build)
> 
> => but CONFIG_SPL_ECDSA_VERIFY is missing, I think you need to add it, 
> as RSA

This patch adds both "config ECDSA_VERIFY" and "config SPL_ECDSA_VERIFY"
see @lib/ecdsa/Kconfig. I believe this achieves what you need.

[snip]
>> diff --git a/lib/Makefile b/lib/Makefile
>> index cf64188ba5..ab86be2678 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -59,6 +59,7 @@ endif
>>   obj-$(CONFIG_$(SPL_)ACPIGEN) += acpi/
>>   obj-$(CONFIG_$(SPL_)MD5) += md5.o
>> +obj-$(CONFIG_ECDSA) += ecdsa/
> 
> obj-$(CONFIG_$(SPL_)ECDSA) += ecdsa/

The intent here is to use CONFIG_ECDSA to denote ECDSA support. 
CONFIG_ECDSA_VERIFY and CONFIG_SPL_ECDSA_VERIFY are used to enable the 
code in u-boot and SPL respectively. Only verification is supported on 
the target, so these are the only switches that enable or disable code.

> 
>>   obj-$(CONFIG_$(SPL_)RSA) += rsa/
>>   obj-$(CONFIG_FIT_SIGNATURE) += hash-checksum.o
>>   obj-$(CONFIG_SHA1) += sha1.o
>> diff --git a/lib/ecdsa/Kconfig b/lib/ecdsa/Kconfig
>> new file mode 100644
>> index 0000000000..1244d6b6ea
>> --- /dev/null
>> +++ b/lib/ecdsa/Kconfig
>> @@ -0,0 +1,23 @@
>> +config ECDSA
>> +    bool "Enable ECDSA support"
>> +    depends on DM
>> +    help
>> +      This enables the ECDSA algorithm for FIT image verification in 
>> U-Boot.
>> +      See doc/uImage.FIT/signature.txt for more details.
>> +      The ECDSA algorithm is implemented using the driver model. So
>> +      CONFIG_DM is required by this library.
>> +      ECDSA is enabled for mkimage regardless of this  option.
>> +
>> +if ECDSA
>> +
> 
> Add CONFIG_SPL_ECDSA to select independently support in SPL et/or in U-Boot
> as it is done for RSA
> 
> + config SPL_ECDSA
> +    bool "Use ECDSA library within in SPL"
> 
I though about an SPL_ECDSA kconfig. As mentioned above, we have 
independent switches to enable the code for u-boot/SPL. We can enable 
ECDSA support in u-boot, SPL, neither or both. What would this switch add?

> 
>> +config ECDSA_VERIFY
>> +    bool "Enable ECDSA verification support in U-Boot."
> 
> 
> + select SPL_ECDSA
> 
> 
>> +    help
>> +      Allow ECDSA signatures to be recognized and verified in U-Boot.
>> +
>> +config SPL_ECDSA_VERIFY
>> +    bool "Enable ECDSA verification support in SPL"
>> +    help
>> +      Allow ECDSA signatures to be recognized and verified in SPL.

This is the switch for SPL (@mentioned earlier).


Alex