Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932647AbbLROm4 (ORCPT ); Fri, 18 Dec 2015 09:42:56 -0500 Received: from mail-vk0-f46.google.com ([209.85.213.46]:35345 "EHLO mail-vk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932435AbbLROmx (ORCPT ); Fri, 18 Dec 2015 09:42:53 -0500 MIME-Version: 1.0 In-Reply-To: <20151218000302.29802.28710.stgit@warthog.procyon.org.uk> References: <20151218000302.29802.28710.stgit@warthog.procyon.org.uk> Date: Fri, 18 Dec 2015 09:42:52 -0500 X-Google-Sender-Auth: 1VEqjUmd6VrqSBOteh2aChsflAU Message-ID: Subject: Re: [PATCH] X.509: Fix determination of self-signedness From: Josh Boyer To: David Howells Cc: keyrings@vger.kernel.org, linux-security-module , David Woodhouse , "Linux-Kernel@Vger. Kernel. Org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2503 Lines: 55 On Thu, Dec 17, 2015 at 7:03 PM, David Howells wrote: > Fix determination of whether an X.509 certificate is self-signed or not. > > It is currently assumed that a cert is self-signed if has no > authorityKeyIdentifier or the authorityKeyIdentifier matches the > subjectKeyIdentifier. However, it is possible to encounter a certificate > that has neither AKID not SKID but is not self-signed. > > This symptoms of this show up as an attempt to load a certificate failing > with -ERANGE or -EBADMSG, produced from the RSA module when the result of > calculating "m = s^e mod n" is checked. > > To fix this, don't check to see if a certificate is self-signed if the > Issuer and Subject names differ. > > Signed-off-by: David Howells > cc: David Woodhouse Should this also be Cc'd to stable? josh > --- > > crypto/asymmetric_keys/x509_public_key.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c > index 2a44b3752471..6236e7996f19 100644 > --- a/crypto/asymmetric_keys/x509_public_key.c > +++ b/crypto/asymmetric_keys/x509_public_key.c > @@ -313,9 +313,14 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) > cert->pub->id_type = PKEY_ID_X509; > > /* Check the signature on the key if it appears to be self-signed */ > - if ((!cert->akid_skid && !cert->akid_id) || > - asymmetric_key_id_same(cert->skid, cert->akid_skid) || > - asymmetric_key_id_same(cert->id, cert->akid_id)) { > + if ((!cert->akid_skid && !cert->akid_id)) { > + if (cert->raw_issuer_size == cert->raw_subject_size && > + memcmp(cert->raw_issuer, cert->raw_subject, > + cert->raw_subject_size) == 0) > + goto self_signed; > + } else if (asymmetric_key_id_same(cert->skid, cert->akid_skid) || > + asymmetric_key_id_same(cert->id, cert->akid_id)) { > +self_signed: > ret = x509_check_signature(cert->pub, cert); /* self-signed */ > if (ret < 0) > goto error_free_cert; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/