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

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

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