Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934305AbbLRADH (ORCPT ); Thu, 17 Dec 2015 19:03:07 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43053 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933136AbbLRADE (ORCPT ); Thu, 17 Dec 2015 19:03:04 -0500 Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH] X.509: Fix determination of self-signedness From: David Howells To: keyrings@vger.kernel.org Cc: dhowells@redhat.com, linux-security-module@vger.kernel.org, David Woodhouse , linux-kernel@vger.kernel.org Date: Fri, 18 Dec 2015 00:03:02 +0000 Message-ID: <20151218000302.29802.28710.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2137 Lines: 49 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 --- 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/