On Thu, Jun 20, 2019 at 05:42:18PM -0400, Mimi Zohar wrote:
> On Tue, 2019-06-18 at 16:56 +0300, Vitaly Chikunov wrote:
> > Fix off-by-one error of the output buffer passed to sign_hash().
> >
> > Signed-off-by: Vitaly Chikunov <vt@xxxxxxxxxxxx>
> > ---
> > src/evmctl.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/src/evmctl.c b/src/evmctl.c
> > index 15a7226..03f41fe 100644
> > --- a/src/evmctl.c
> > +++ b/src/evmctl.c
> > @@ -510,7 +510,7 @@ static int calc_evm_hash(const char *file, unsigned char *hash)
> > static int sign_evm(const char *file, const char *key)
> > {
> > unsigned char hash[MAX_DIGEST_SIZE];
> > - unsigned char sig[MAX_SIGNATURE_SIZE];
> > + unsigned char sig[MAX_SIGNATURE_SIZE + 1];
> > int len, err;
> >
> > len = calc_evm_hash(file, hash);
> > @@ -519,7 +519,7 @@ static int sign_evm(const char *file, const char *key)
> > return len;
> >
> > len = sign_hash(params.hash_algo, hash, len, key, NULL, sig + 1);
> > - assert(len < sizeof(sig));
> > + assert(len <= MAX_SIGNATURE_SIZE);
> > if (len <= 1)
> > return len;
> >
>
> A similar problem occurs in sign_ima. Without these changes
> sign_hash() succeeds, returning a length of 520 for
> sha256/streebog256.
I will add it. Also, I found more similar errors and will fix them together.
> With these patches, for streebog256
> EVP_PKEY_CTX_set_signature_md is failing, returning -1,
> but works for sha256.
Probably your openssl does not support streebog256.
> With a similar change as this patch, it also works, returning
> 520.
This is above level than this change so it can not be related.
When I try streebog256 with similar change to sign_ima() I get error
like this:
$ evmctl ima_sign --key privkey_rsa.pem -a streebog256 --xattr-user test.txt
sign_hash_v2: signing failed: (invalid digest)
error:0408C09D:rsa routines:check_padding_md:invalid digest
Which is correct.
Thanks,
