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100 lines
3.2 KiB
Go
100 lines
3.2 KiB
Go
/*
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Copyright 2020 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package approval
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import (
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"context"
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"fmt"
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"io"
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"k8s.io/klog/v2"
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"k8s.io/apiserver/pkg/admission"
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genericadmissioninit "k8s.io/apiserver/pkg/admission/initializer"
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"k8s.io/apiserver/pkg/authorization/authorizer"
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api "k8s.io/kubernetes/pkg/apis/certificates"
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"k8s.io/kubernetes/plugin/pkg/admission/certificates"
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)
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// PluginName is a string with the name of the plugin
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const PluginName = "CertificateApproval"
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// Register registers a plugin
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func Register(plugins *admission.Plugins) {
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plugins.Register(PluginName, func(config io.Reader) (admission.Interface, error) {
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return NewPlugin(), nil
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})
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}
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// Plugin holds state for and implements the admission plugin.
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type Plugin struct {
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*admission.Handler
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authz authorizer.Authorizer
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}
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// SetAuthorizer sets the authorizer.
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func (p *Plugin) SetAuthorizer(authz authorizer.Authorizer) {
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p.authz = authz
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}
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// ValidateInitialization ensures an authorizer is set.
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func (p *Plugin) ValidateInitialization() error {
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if p.authz == nil {
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return fmt.Errorf("%s requires an authorizer", PluginName)
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}
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return nil
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}
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var _ admission.ValidationInterface = &Plugin{}
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var _ genericadmissioninit.WantsAuthorizer = &Plugin{}
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// NewPlugin creates a new CSR approval admission plugin
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func NewPlugin() *Plugin {
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return &Plugin{
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Handler: admission.NewHandler(admission.Update),
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}
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}
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var csrGroupResource = api.Resource("certificatesigningrequests")
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// Validate verifies that the requesting user has permission to approve
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// CertificateSigningRequests for the specified signerName.
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func (p *Plugin) Validate(ctx context.Context, a admission.Attributes, _ admission.ObjectInterfaces) error {
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// Ignore all calls to anything other than 'certificatesigningrequests/approval'.
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// Ignore all operations other than UPDATE.
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if a.GetSubresource() != "approval" ||
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a.GetResource().GroupResource() != csrGroupResource {
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return nil
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}
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// We check permissions against the *old* version of the resource, in case
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// a user is attempting to update the SignerName when calling the approval
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// endpoint (which is an invalid/not allowed operation)
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csr, ok := a.GetOldObject().(*api.CertificateSigningRequest)
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if !ok {
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return admission.NewForbidden(a, fmt.Errorf("expected type CertificateSigningRequest, got: %T", a.GetOldObject()))
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}
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if !certificates.IsAuthorizedForSignerName(ctx, p.authz, a.GetUserInfo(), "approve", csr.Spec.SignerName) {
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klog.V(4).Infof("user not permitted to approve CertificateSigningRequest %q with signerName %q", csr.Name, csr.Spec.SignerName)
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return admission.NewForbidden(a, fmt.Errorf("user not permitted to approve requests with signerName %q", csr.Spec.SignerName))
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}
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return nil
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}
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