util.go

Documentation: k8s.io/kubernetes/plugin/pkg/admission/certificates

     1  /*
     2  Copyright 2020 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package certificates
    18  
    19  import (
    20  	"context"
    21  	"strings"
    22  
    23  	"k8s.io/apiserver/pkg/authentication/user"
    24  	"k8s.io/apiserver/pkg/authorization/authorizer"
    25  	"k8s.io/klog/v2"
    26  )
    27  
    28  // IsAuthorizedForSignerName returns true if 'info' is authorized to perform the given
    29  // 'verb' on the synthetic 'signers' resource with the given signerName.
    30  // If the user does not have permission to perform the 'verb' on the given signerName,
    31  // it will also perform an authorization check against {domain portion}/*, for example
    32  // `kubernetes.io/*`. This allows an entity to be granted permission to 'verb' on all
    33  // signerNames with a given 'domain portion'.
    34  func IsAuthorizedForSignerName(ctx context.Context, authz authorizer.Authorizer, info user.Info, verb, signerName string) bool {
    35  	// First check if the user has explicit permission to 'verb' for the given signerName.
    36  	attr := buildAttributes(info, verb, signerName)
    37  	decision, reason, err := authz.Authorize(ctx, attr)
    38  	switch {
    39  	case err != nil:
    40  		klog.V(3).Infof("cannot authorize %q %q for policy: %v,%v", verb, attr.GetName(), reason, err)
    41  	case decision == authorizer.DecisionAllow:
    42  		return true
    43  	}
    44  
    45  	// If not, check if the user has wildcard permissions to 'verb' for the domain portion of the signerName, e.g.
    46  	// 'kubernetes.io/*'.
    47  	attr = buildWildcardAttributes(info, verb, signerName)
    48  	decision, reason, err = authz.Authorize(ctx, attr)
    49  	switch {
    50  	case err != nil:
    51  		klog.V(3).Infof("cannot authorize %q %q for policy: %v,%v", verb, attr.GetName(), reason, err)
    52  	case decision == authorizer.DecisionAllow:
    53  		return true
    54  	}
    55  
    56  	return false
    57  }
    58  
    59  func buildAttributes(info user.Info, verb, signerName string) authorizer.Attributes {
    60  	return authorizer.AttributesRecord{
    61  		User:            info,
    62  		Verb:            verb,
    63  		Name:            signerName,
    64  		APIGroup:        "certificates.k8s.io",
    65  		APIVersion:      "*",
    66  		Resource:        "signers",
    67  		ResourceRequest: true,
    68  	}
    69  }
    70  
    71  func buildWildcardAttributes(info user.Info, verb, signerName string) authorizer.Attributes {
    72  	parts := strings.Split(signerName, "/")
    73  	domain := parts[0]
    74  	return buildAttributes(info, verb, domain+"/*")
    75  }
    76
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