[PATCH] lib: rsa: Extract public key from private key if keyfile argument is used

[Simon Glass]

Hi Donald,

On Wed, 28 Jul 2021 at 18:35, Donald Chan <hoiho at lab126.com> wrote:
>
> If the 'keyfile' (-G) argument is used, there is little value to require
> 'keydir' (-k) argument since the public key can also be extracted from the
> private key itself.
>
> Signed-off-by: Donald Chan <hoiho at lab126.com>
> ---
>  lib/rsa/rsa-sign.c | 28 +++++++++++++++++++++-------
>  1 file changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
> index f4ed11e74a..f70f352311 100644
> --- a/lib/rsa/rsa-sign.c
> +++ b/lib/rsa/rsa-sign.c
> @@ -49,16 +49,16 @@ static int rsa_err(const char *msg)
>  }
>
>  /**
> - * rsa_pem_get_pub_key() - read a public key from a .crt file
> + * rsa_pem_get_pub_key() - read a public key from a private key file or .crt file
>   *
> - * @keydir:    Directory containins the key
> - * @name       Name of key file (will have a .crt extension)
> + * @keydir:    Directory containing the key, can be NULL
> + * @name       Name of key file (will apply a .crt extension if keydir is not NULL)
>   * @evpp       Returns EVP_PKEY object, or NULL on failure
>   * @return 0 if ok, -ve on error (in which case *evpp will be set to NULL)
>   */
>  static int rsa_pem_get_pub_key(const char *keydir, const char *name, EVP_PKEY **evpp)
>  {
> -       char path[1024];
> +       char path[1024] = {0};
>         EVP_PKEY *key = NULL;
>         X509 *cert;
>         FILE *f;
> @@ -68,7 +68,10 @@ static int rsa_pem_get_pub_key(const char *keydir, const char *name, EVP_PKEY **
>                 return -EINVAL;
>
>         *evpp = NULL;
> -       snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
> +       if (keydir && name)
> +               snprintf(path, sizeof(path), "%s/%s.crt", keydir, name);
> +       else if (name)
> +               snprintf(path, sizeof(path), "%s", name);
>         f = fopen(path, "r");
>         if (!f) {
>                 fprintf(stderr, "Couldn't open RSA certificate: '%s': %s\n",
> @@ -76,7 +79,13 @@ static int rsa_pem_get_pub_key(const char *keydir, const char *name, EVP_PKEY **
>                 return -EACCES;
>         }
>
> -       /* Read the certificate */
> +       /* See if it contains a PEM private key? */
> +       if (PEM_read_PrivateKey(f, evpp, NULL, path)) {
> +               fclose(f);
> +               return 0;
> +       }
> +
> +       /* Not a PEM private key, read the certificate */
>         cert = NULL;
>         if (!PEM_read_X509(f, &cert, NULL, NULL)) {
>                 rsa_err("Couldn't read certificate");
> @@ -672,7 +681,12 @@ int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
>                 if (ret)
>                         return ret;
>         }
> -       ret = rsa_get_pub_key(info->keydir, info->keyname, e, &pkey);
> +       if (info->keydir && info->keyname)
> +               ret = rsa_get_pub_key(info->keydir, info->keyname, e, &pkey);
> +       else if (info->keyfile)
> +               ret = rsa_get_pub_key(NULL, info->keyfile, e, &pkey);
> +       else
> +               ret = -EINVAL;
>         if (ret)
>                 goto err_get_pub_key;
>  #if OPENSSL_VERSION_NUMBER < 0x10100000L || \
> --
> 2.16.6
>

Can we work this into a test somehow? The normal test is test_vboot.py
- you could modify that or add a new test into that file perhaps?

Regards,
Simon