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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This code is made available to you under your choice of the following sets
* of licensing terms:
*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
*/
/* Copyright 2014 Mozilla Contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "mozpkix/pkixutil.h"
namespace mozilla { namespace pkix {
Result
BackCert::Init()
{
Result rv;
// Certificate ::= SEQUENCE {
// tbsCertificate TBSCertificate,
// signatureAlgorithm AlgorithmIdentifier,
// signatureValue BIT STRING }
Reader tbsCertificate;
// The scope of |input| and |certificate| are limited to this block so we
// don't accidentally confuse them for tbsCertificate later.
{
Reader certificate;
rv = der::ExpectTagAndGetValueAtEnd(der, der::SEQUENCE, certificate);
if (rv != Success) {
return rv;
}
rv = der::SignedData(certificate, tbsCertificate, signedData);
if (rv != Success) {
return rv;
}
rv = der::End(certificate);
if (rv != Success) {
return rv;
}
}
// TBSCertificate ::= SEQUENCE {
// version [0] EXPLICIT Version DEFAULT v1,
// serialNumber CertificateSerialNumber,
// signature AlgorithmIdentifier,
// issuer Name,
// validity Validity,
// subject Name,
// subjectPublicKeyInfo SubjectPublicKeyInfo,
// issuerUniqueID [1] IMPLICIT UniqueIdentifier OPTIONAL,
// -- If present, version MUST be v2 or v3
// subjectUniqueID [2] IMPLICIT UniqueIdentifier OPTIONAL,
// -- If present, version MUST be v2 or v3
// extensions [3] EXPLICIT Extensions OPTIONAL
// -- If present, version MUST be v3
// }
rv = der::OptionalVersion(tbsCertificate, version);
if (rv != Success) {
return rv;
}
rv = der::CertificateSerialNumber(tbsCertificate, serialNumber);
if (rv != Success) {
return rv;
}
rv = der::ExpectTagAndGetValue(tbsCertificate, der::SEQUENCE, signature);
if (rv != Success) {
return rv;
}
rv = der::ExpectTagAndGetTLV(tbsCertificate, der::SEQUENCE, issuer);
if (rv != Success) {
return rv;
}
rv = der::ExpectTagAndGetValue(tbsCertificate, der::SEQUENCE, validity);
if (rv != Success) {
return rv;
}
// TODO(bug XXXXXXX): We rely on the the caller of mozilla::pkix to validate
// that the name is syntactically valid, if they care. In Gecko we do this
// implicitly by parsing the certificate into a CERTCertificate object.
// Instead of relying on the caller to do this, we should do it ourselves.
rv = der::ExpectTagAndGetTLV(tbsCertificate, der::SEQUENCE, subject);
if (rv != Success) {
return rv;
}
rv = der::ExpectTagAndGetTLV(tbsCertificate, der::SEQUENCE,
subjectPublicKeyInfo);
if (rv != Success) {
return rv;
}
// According to RFC 5280, all fields below this line are forbidden for
// certificate versions less than v3. However, for compatibility reasons,
// we parse v1/v2 certificates in the same way as v3 certificates. So if
// these fields appear in a v1 certificate, they will be used.
// Ignore issuerUniqueID if present.
rv = der::SkipOptionalImplicitPrimitiveTag(tbsCertificate, 1);
if (rv != Success) {
return rv;
}
// Ignore subjectUniqueID if present.
rv = der::SkipOptionalImplicitPrimitiveTag(tbsCertificate, 2);
if (rv != Success) {
return rv;
}
static const uint8_t CSC = der::CONTEXT_SPECIFIC | der::CONSTRUCTED;
rv = der::OptionalExtensions(
tbsCertificate, CSC | 3,
[this](Reader& extnID, const Input& extnValue, bool critical,
/*out*/ bool& understood) {
return RememberExtension(extnID, extnValue, critical, understood);
});
if (rv != Success) {
return rv;
}
// The Netscape Certificate Type extension is an obsolete
// Netscape-proprietary mechanism that we ignore in favor of the standard
// extensions. However, some CAs have issued certificates with the Netscape
// Cert Type extension marked critical. Thus, for compatibility reasons, we
// "understand" this extension by ignoring it when it is not critical, and
// by ensuring that the equivalent standardized extensions are present when
// it is marked critical, based on the assumption that the information in
// the Netscape Cert Type extension is consistent with the information in
// the standard extensions.
//
// Here is a mapping between the Netscape Cert Type extension and the
// standard extensions:
//
// Netscape Cert Type | BasicConstraints.cA | Extended Key Usage
// --------------------+-----------------------+----------------------
// SSL Server | false | id_kp_serverAuth
// SSL Client | false | id_kp_clientAuth
// S/MIME Client | false | id_kp_emailProtection
// Object Signing | false | id_kp_codeSigning
// SSL Server CA | true | id_kp_serverAuth
// SSL Client CA | true | id_kp_clientAuth
// S/MIME CA | true | id_kp_emailProtection
// Object Signing CA | true | id_kp_codeSigning
if (criticalNetscapeCertificateType.GetLength() > 0 &&
(basicConstraints.GetLength() == 0 || extKeyUsage.GetLength() == 0)) {
return Result::ERROR_UNKNOWN_CRITICAL_EXTENSION;
}
return der::End(tbsCertificate);
}
Result
BackCert::RememberExtension(Reader& extnID, Input extnValue,
bool critical, /*out*/ bool& understood)
{
understood = false;
// python DottedOIDToCode.py id-ce-keyUsage 2.5.29.15
static const uint8_t id_ce_keyUsage[] = {
0x55, 0x1d, 0x0f
};
// python DottedOIDToCode.py id-ce-subjectAltName 2.5.29.17
static const uint8_t id_ce_subjectAltName[] = {
0x55, 0x1d, 0x11
};
// python DottedOIDToCode.py id-ce-basicConstraints 2.5.29.19
static const uint8_t id_ce_basicConstraints[] = {
0x55, 0x1d, 0x13
};
// python DottedOIDToCode.py id-ce-nameConstraints 2.5.29.30
static const uint8_t id_ce_nameConstraints[] = {
0x55, 0x1d, 0x1e
};
// python DottedOIDToCode.py id-ce-certificatePolicies 2.5.29.32
static const uint8_t id_ce_certificatePolicies[] = {
0x55, 0x1d, 0x20
};
// python DottedOIDToCode.py id-ce-policyConstraints 2.5.29.36
static const uint8_t id_ce_policyConstraints[] = {
0x55, 0x1d, 0x24
};
// python DottedOIDToCode.py id-ce-extKeyUsage 2.5.29.37
static const uint8_t id_ce_extKeyUsage[] = {
0x55, 0x1d, 0x25
};
// python DottedOIDToCode.py id-ce-inhibitAnyPolicy 2.5.29.54
static const uint8_t id_ce_inhibitAnyPolicy[] = {
0x55, 0x1d, 0x36
};
// python DottedOIDToCode.py id-pe-authorityInfoAccess 1.3.6.1.5.5.7.1.1
static const uint8_t id_pe_authorityInfoAccess[] = {
0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x01, 0x01
};
// python DottedOIDToCode.py id-pkix-ocsp-nocheck 1.3.6.1.5.5.7.48.1.5
static const uint8_t id_pkix_ocsp_nocheck[] = {
0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x30, 0x01, 0x05
};
// python DottedOIDToCode.py Netscape-certificate-type 2.16.840.1.113730.1.1
static const uint8_t Netscape_certificate_type[] = {
0x60, 0x86, 0x48, 0x01, 0x86, 0xf8, 0x42, 0x01, 0x01
};
// python DottedOIDToCode.py id-pe-tlsfeature 1.3.6.1.5.5.7.1.24
static const uint8_t id_pe_tlsfeature[] = {
0x2b, 0x06, 0x01, 0x05, 0x05, 0x07, 0x01, 0x18
};
// python DottedOIDToCode.py id-embeddedSctList 1.3.6.1.4.1.11129.2.4.2
// See Section 3.3 of RFC 6962.
static const uint8_t id_embeddedSctList[] = {
0x2b, 0x06, 0x01, 0x04, 0x01, 0xd6, 0x79, 0x02, 0x04, 0x02
};
Input* out = nullptr;
// We already enforce the maximum possible constraints for policies so we
// can safely ignore even critical policy constraint extensions.
//
// XXX: Doing it this way won't allow us to detect duplicate
// policyConstraints extensions, but that's OK because (and only because) we
// ignore the extension.
Input dummyPolicyConstraints;
// We don't need to save the contents of this extension if it is present. We
// just need to handle its presence (it is essentially ignored right now).
Input dummyOCSPNocheck;
// For compatibility reasons, for some extensions we have to allow empty
// extension values. This would normally interfere with our duplicate
// extension checking code. However, as long as the extensions we allow to
// have empty values are also the ones we implicitly allow duplicates of,
// this will work fine.
bool emptyValueAllowed = false;
// RFC says "Conforming CAs MUST mark this extension as non-critical" for
// both authorityKeyIdentifier and subjectKeyIdentifier, and we do not use
// them for anything, so we totally ignore them here.
if (extnID.MatchRest(id_ce_keyUsage)) {
out = &keyUsage;
} else if (extnID.MatchRest(id_ce_subjectAltName)) {
out = &subjectAltName;
} else if (extnID.MatchRest(id_ce_basicConstraints)) {
out = &basicConstraints;
} else if (extnID.MatchRest(id_ce_nameConstraints)) {
out = &nameConstraints;
} else if (extnID.MatchRest(id_ce_certificatePolicies)) {
out = &certificatePolicies;
} else if (extnID.MatchRest(id_ce_policyConstraints)) {
out = &dummyPolicyConstraints;
} else if (extnID.MatchRest(id_ce_extKeyUsage)) {
out = &extKeyUsage;
} else if (extnID.MatchRest(id_ce_inhibitAnyPolicy)) {
out = &inhibitAnyPolicy;
} else if (extnID.MatchRest(id_pe_authorityInfoAccess)) {
out = &authorityInfoAccess;
} else if (extnID.MatchRest(id_pe_tlsfeature)) {
out = &requiredTLSFeatures;
} else if (extnID.MatchRest(id_embeddedSctList)) {
out = &signedCertificateTimestamps;
} else if (extnID.MatchRest(id_pkix_ocsp_nocheck) && critical) {
// We need to make sure we don't reject delegated OCSP response signing
// certificates that contain the id-pkix-ocsp-nocheck extension marked as
// critical when validating OCSP responses. Without this, an application
// that implements soft-fail OCSP might ignore a valid Revoked or Unknown
// response, and an application that implements hard-fail OCSP might fail
// to connect to a server given a valid Good response.
out = &dummyOCSPNocheck;
// We allow this extension to have an empty value.
emptyValueAllowed = true;
} else if (extnID.MatchRest(Netscape_certificate_type) && critical) {
out = &criticalNetscapeCertificateType;
}
if (out) {
// Don't allow an empty value for any extension we understand. This way, we
// can test out->GetLength() != 0 or out->Init() to check for duplicates.
if (extnValue.GetLength() == 0 && !emptyValueAllowed) {
return Result::ERROR_EXTENSION_VALUE_INVALID;
}
if (out->Init(extnValue) != Success) {
// Duplicate extension
return Result::ERROR_EXTENSION_VALUE_INVALID;
}
understood = true;
}
return Success;
}
Result
ExtractSignedCertificateTimestampListFromExtension(Input extnValue,
Input& sctList)
{
Reader decodedValue;
Result rv = der::ExpectTagAndGetValueAtEnd(extnValue, der::OCTET_STRING,
decodedValue);
if (rv != Success) {
return rv;
}
return decodedValue.SkipToEnd(sctList);
}
} } // namespace mozilla::pkix