[U-Boot] [PATCH v3 5/6] lib: rsa: add rsa_verify_with_pkey()

[Simon Glass]

Hi Takahiro,

On Tue, 12 Nov 2019 at 16:47, AKASHI Takahiro
<takahiro.akashi at linaro.org> wrote:
>
> This function, and hence rsa_verify(), will perform RSA verification
> with two essential parameters for a RSA public key in contract of
> rsa_verify_with_keynode(), which requires additional three parameters
> stored in FIT image.
>
> It will be used in implementing UEFI secure boot, i.e. image authentication
> and variable authentication.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> ---
>  lib/rsa/rsa-verify.c | 57 +++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 56 insertions(+), 1 deletion(-)

Reviewed-by: Simon Glass <sjg at chromium.org>

Nits below though

>
> diff --git a/lib/rsa/rsa-verify.c b/lib/rsa/rsa-verify.c
> index d2fd0692fa13..3f63bd9c175b 100644
> --- a/lib/rsa/rsa-verify.c
> +++ b/lib/rsa/rsa-verify.c
> @@ -17,9 +17,14 @@
>  #include "mkimage.h"
>  #include <fdt_support.h>
>  #endif
> +#include <linux/kconfig.h>
>  #include <u-boot/rsa-mod-exp.h>
>  #include <u-boot/rsa.h>
>
> +#ifndef __UBOOT__ /* for host tools */

Comment here as to why this is needed

> +#undef CONFIG_RSA_VERIFY_WITH_PKEY
> +#endif
> +
>  /* Default public exponent for backward compatibility */
>  #define RSA_DEFAULT_PUBEXP     65537
>
> @@ -270,7 +275,7 @@ out:
>  }
>  #endif
>
> -#if CONFIG_IS_ENABLED(FIT_SIGNATURE)
> +#if CONFIG_IS_ENABLED(FIT_SIGNATURE) || IS_ENABLED(CONFIG_RSA_VERIFY_WITH_PKEY)
>  /**
>   * rsa_verify_key() - Verify a signature against some data using RSA Key
>   *
> @@ -344,6 +349,49 @@ static int rsa_verify_key(struct image_sign_info *info,
>  }
>  #endif
>
> +#ifdef CONFIG_RSA_VERIFY_WITH_PKEY
> +/**
> + * rsa_verify_with_pkey() - Verify a signature against some data using
> + * only modulus and exponent as RSA key properties.
> + * @info:      Specifies key information
> + * @hash:      Pointer to the expected hash
> + * @sig:       Signature
> + * @sig_len:   Number of bytes in signature
> + *
> + * Parse a RSA public key blob in DER format pointed to in @info and fill
> + * a key_prop structure with properties of the key. Then verify a RSA PKCS1.5
> + * signature against an expected hash using the calculated properties.
> + *
> + * Return      0 if verified, -ve on error
> + */
> +static int rsa_verify_with_pkey(struct image_sign_info *info,
> +                               const void *hash, uint8_t *sig, uint sig_len)
> +{
> +       struct key_prop *prop;
> +       int ret;
> +
> +       /* Public key is self-described to fill key_prop */
> +       prop = rsa_gen_key_prop(info->key, info->keylen);

This function should return an int error code, with the pointer as one
of the parameters. It isn't good to lose the real error here.

> +       if (!prop) {
> +               debug("Generating necessary parameter for decoding failed\n");
> +               return -EACCES;

return real error here.

> +       }
> +
> +       ret = rsa_verify_key(info, prop, sig, sig_len, hash,
> +                            info->crypto->key_len);
> +
> +       rsa_free_key_prop(prop);
> +
> +       return ret;
> +}
> +#else
> +static int rsa_verify_with_pkey(struct image_sign_info *info,
> +                               const void *hash, uint8_t *sig, uint sig_len)
> +{
> +       return -EACCES;
> +}
> +#endif
> +
>  #if CONFIG_IS_ENABLED(FIT_SIGNATURE)
>  /**
>   * rsa_verify_with_keynode() - Verify a signature against some data using
> @@ -434,6 +482,13 @@ int rsa_verify(struct image_sign_info *info,
>                 return -EINVAL;
>         }
>
> +       if (IS_ENABLED(CONFIG_RSA_VERIFY_WITH_PKEY) && !info->fdt_blob) {
> +               /* don't rely on fdt properties */
> +               ret = rsa_verify_with_pkey(info, hash, sig, sig_len);
> +
> +               return ret;
> +       }
> +
>         if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
>                 const void *blob = info->fdt_blob;
>                 int ndepth, noffset;
> --
> 2.21.0
>

Regards,
Simon