On Mon, Feb 21, 2022 at 02:46:26AM +0100, Jarkko Sakkinen wrote:
> On Mon, Jan 31, 2022 at 04:34:14PM -0800, Eric Biggers wrote:
> > From: Eric Biggers <ebiggers@xxxxxxxxxx>
> >
> > It is insecure to allow arbitrary hash algorithms and signature
> > encodings to be used with arbitrary signature algorithms. Notably,
> > ECDSA, ECRDSA, and SM2 all sign/verify raw hash values and don't
> > disambiguate between different hash algorithms like RSA PKCS#1 v1.5
> > padding does. Therefore, they need to be restricted to certain sets of
> > hash algorithms (ideally just one, but in practice small sets are used).
> > Additionally, the encoding is an integral part of modern signature
> > algorithms, and is not supposed to vary.
> >
> > Therefore, tighten the checks of hash_algo and encoding done by
> > software_key_determine_akcipher().
> >
> > Also rearrange the parameters to software_key_determine_akcipher() to
> > put the public_key first, as this is the most important parameter and it
> > often determines everything else.
> >
> > Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys")
> > Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification")
> > Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> > ---
> > crypto/asymmetric_keys/public_key.c | 111 +++++++++++++++++++---------
> > 1 file changed, 76 insertions(+), 35 deletions(-)
> >
> > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> > index aba7113d86c76..a603ee8afdb8d 100644
> > --- a/crypto/asymmetric_keys/public_key.c
> > +++ b/crypto/asymmetric_keys/public_key.c
> > @@ -60,39 +60,83 @@ static void public_key_destroy(void *payload0, void *payload3)
> > }
> >
> > /*
> > - * Determine the crypto algorithm name.
> > + * Given a public_key, and an encoding and hash_algo to be used for signing
> > + * and/or verification with that key, determine the name of the corresponding
> > + * akcipher algorithm. Also check that encoding and hash_algo are allowed.
> > */
> > -static
> > -int software_key_determine_akcipher(const char *encoding,
> > - const char *hash_algo,
> > - const struct public_key *pkey,
> > - char alg_name[CRYPTO_MAX_ALG_NAME])
> > +static int
> > +software_key_determine_akcipher(const struct public_key *pkey,
> > + const char *encoding, const char *hash_algo,
> > + char alg_name[CRYPTO_MAX_ALG_NAME])
>
> Why is changing parameter order necessary?
>
It's mentioned in the commit message. It's obviously not necessary but this way
makes much more sense IMO.
- Eric
