From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2530EB64DA for ; Wed, 14 Jun 2023 09:51:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243504AbjFNJvK (ORCPT ); Wed, 14 Jun 2023 05:51:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241748AbjFNJvI (ORCPT ); Wed, 14 Jun 2023 05:51:08 -0400 Received: from 167-179-156-38.a7b39c.syd.nbn.aussiebb.net (167-179-156-38.a7b39c.syd.nbn.aussiebb.net [167.179.156.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3314B19F; Wed, 14 Jun 2023 02:51:02 -0700 (PDT) Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1q9N9Q-002ond-3C; Wed, 14 Jun 2023 17:50:53 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Wed, 14 Jun 2023 17:50:52 +0800 Date: Wed, 14 Jun 2023 17:50:52 +0800 From: Herbert Xu To: Mahmoud Adam Cc: davem@davemloft.net, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Stephan Mueller Subject: Re: [PATCH] crypto: rsa - allow only odd e and restrict value in FIPS mode Message-ID: References: <20230613161731.74081-1-mngyadam@amazon.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230613161731.74081-1-mngyadam@amazon.com> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, Jun 13, 2023 at 04:17:31PM +0000, Mahmoud Adam wrote: > check if rsa public exponent is odd and check its value is between > 2^16 < e < 2^256. > > FIPS 186-5 DSS (page 35)[1] specify that: > 1. The public exponent e shall be selected with the following constraints: > (a) The public verification exponent e shall be selected prior to > generating the primes, p and q, and the private signature exponent > d. > (b) The exponent e shall be an odd positive integer such that: > 2^16 < e < 2^256. > > [1] https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5.pdf > > Signed-off-by: Mahmoud Adam > --- > crypto/rsa.c | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/crypto/rsa.c b/crypto/rsa.c > index c50f2d2a4d06..c79613cdce6e 100644 > --- a/crypto/rsa.c > +++ b/crypto/rsa.c > @@ -205,6 +205,32 @@ static int rsa_check_key_length(unsigned int len) > return -EINVAL; > } > > +static int rsa_check_exponent_fips(MPI e) > +{ > + MPI e_max = NULL; > + > + /* check if odd */ > + if (!mpi_test_bit(e, 0)) { > + return -EINVAL; > + } > + > + /* check if 2^16 < e < 2^256. */ > + if (mpi_cmp_ui(e, 65536) <= 0) { > + return -EINVAL; > + } > + > + e_max = mpi_alloc(0); > + mpi_set_bit(e_max, 256); > + > + if (mpi_cmp(e, e_max) >= 0) { > + mpi_free(e_max); > + return -EINVAL; > + } > + > + mpi_free(e_max); > + return 0; > +} > + > static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, > unsigned int keylen) > { > @@ -232,6 +258,11 @@ static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, > return -EINVAL; > } > > + if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) { > + rsa_free_mpi_key(mpi_key); > + return -EINVAL; > + } > + > return 0; > > err: > @@ -290,6 +321,11 @@ static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key, > return -EINVAL; > } > > + if (fips_enabled && rsa_check_exponent_fips(mpi_key->e)) { > + rsa_free_mpi_key(mpi_key); > + return -EINVAL; > + } > + > return 0; > > err: > -- > 2.40.1 Cc Stephan Mueller -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt