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/*
* ZLint Copyright 2024 Regents of the University of Michigan
*
* 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 http://www.apache.org/licenses/LICENSE-2.0
*
* 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.
*/
package mozilla
import (
"time"
"github.com/zmap/zcrypto/x509"
"github.com/zmap/zlint/v3/lint"
"github.com/zmap/zlint/v3/util"
)
type allowedEKU struct{}
/********************************************************************
Section 5.3 - Intermediate Certificates
Intermediate certificates created after January 1, 2019, with the exception
of cross-certificates that share a private key with a corresponding root
certificate: MUST contain an EKU extension; and, MUST NOT include the
anyExtendedKeyUsage KeyPurposeId; and, * MUST NOT include both the
id-kp-serverAuth and id-kp-emailProtection KeyPurposeIds in the same
certificate.
Note that the lint cannot distinguish cross-certificates from other
intermediates.
********************************************************************/
func init() {
lint.RegisterCertificateLint(&lint.CertificateLint{
LintMetadata: lint.LintMetadata{
Name: "n_mp_allowed_eku",
Description: "A SubCA certificate must not have key usage that allows for both server auth and email protection, and must not use anyExtendedKeyUsage",
Citation: "Mozilla Root Store Policy / Section 5.3",
Source: lint.MozillaRootStorePolicy,
EffectiveDate: time.Date(2019, time.January, 1, 0, 0, 0, 0, time.UTC),
},
Lint: NewAllowedEKU,
})
}
func NewAllowedEKU() lint.LintInterface {
return &allowedEKU{}
}
func (l *allowedEKU) CheckApplies(c *x509.Certificate) bool {
// TODO(@cpu): This lint should be limited to SubCAs that do not share
// a private key with a corresponding root certificate in the Mozilla root
// store. See https://github.com/zmap/zlint/issues/352
return util.IsSubCA(c)
}
func (l *allowedEKU) Execute(c *x509.Certificate) *lint.LintResult {
noEKU := len(c.ExtKeyUsage) == 0
anyEKU := util.HasEKU(c, x509.ExtKeyUsageAny)
emailAndServerAuthEKU :=
util.HasEKU(c, x509.ExtKeyUsageEmailProtection) &&
util.HasEKU(c, x509.ExtKeyUsageServerAuth)
if noEKU || anyEKU || emailAndServerAuthEKU {
// NOTE(@cpu): When this lint's scope is improved (see CheckApplies TODO)
// this should be a lint.Error result instead of lint.Notice. See
// https://github.com/zmap/zlint/issues/352
return &lint.LintResult{Status: lint.Notice}
}
return &lint.LintResult{Status: lint.Pass}
}
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