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

20 Nov 2019

Simon,
On Tue, Nov 19, 2019 at 06:59:56PM -0800, Simon Glass wrote:
...
Hi Takahiro,
On Tue, 12 Nov 2019 at 16:47, AKASHI Takahiro
takahiro.akashi@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@linaro.org
lib/rsa/rsa-verify.c | 57 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)
Reviewed-by: Simon Glass sjg@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
Sure.
...
...
+#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.
Okay.
...
...

  if (!prop) {


          debug("Generating necessary parameter for decoding failed\n");


          return -EACCES;



return real error here.
Okay.
Thanks,
-Takahiro Akashi
...
...

  }



  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

    