escalation_check.go

Documentation: k8s.io/kubernetes/pkg/registry/rbac

     1  /*
     2  Copyright 2016 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 rbac
    18  
    19  import (
    20  	"context"
    21  	"fmt"
    22  
    23  	"k8s.io/apimachinery/pkg/runtime/schema"
    24  	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
    25  	"k8s.io/apiserver/pkg/authentication/user"
    26  	"k8s.io/apiserver/pkg/authorization/authorizer"
    27  	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
    28  	"k8s.io/kubernetes/pkg/apis/rbac"
    29  )
    30  
    31  // EscalationAllowed checks if the user associated with the context is a superuser
    32  func EscalationAllowed(ctx context.Context) bool {
    33  	u, ok := genericapirequest.UserFrom(ctx)
    34  	if !ok {
    35  		return false
    36  	}
    37  
    38  	// system:masters is special because the API server uses it for privileged loopback connections
    39  	// therefore we know that a member of system:masters can always do anything
    40  	for _, group := range u.GetGroups() {
    41  		if group == user.SystemPrivilegedGroup {
    42  			return true
    43  		}
    44  	}
    45  
    46  	return false
    47  }
    48  
    49  var roleResources = map[schema.GroupResource]bool{
    50  	rbac.SchemeGroupVersion.WithResource("clusterroles").GroupResource(): true,
    51  	rbac.SchemeGroupVersion.WithResource("roles").GroupResource():        true,
    52  }
    53  
    54  // RoleEscalationAuthorized checks if the user associated with the context is explicitly authorized to escalate the role resource associated with the context
    55  func RoleEscalationAuthorized(ctx context.Context, a authorizer.Authorizer) bool {
    56  	if a == nil {
    57  		return false
    58  	}
    59  
    60  	user, ok := genericapirequest.UserFrom(ctx)
    61  	if !ok {
    62  		return false
    63  	}
    64  
    65  	requestInfo, ok := genericapirequest.RequestInfoFrom(ctx)
    66  	if !ok {
    67  		return false
    68  	}
    69  
    70  	if !requestInfo.IsResourceRequest {
    71  		return false
    72  	}
    73  
    74  	requestResource := schema.GroupResource{Group: requestInfo.APIGroup, Resource: requestInfo.Resource}
    75  	if !roleResources[requestResource] {
    76  		return false
    77  	}
    78  
    79  	attrs := authorizer.AttributesRecord{
    80  		User:            user,
    81  		Verb:            "escalate",
    82  		APIGroup:        requestInfo.APIGroup,
    83  		APIVersion:      "*",
    84  		Resource:        requestInfo.Resource,
    85  		Name:            requestInfo.Name,
    86  		Namespace:       requestInfo.Namespace,
    87  		ResourceRequest: true,
    88  	}
    89  
    90  	decision, _, err := a.Authorize(ctx, attrs)
    91  	if err != nil {
    92  		utilruntime.HandleError(fmt.Errorf(
    93  			"error authorizing user %#v to escalate %#v named %q in namespace %q: %v",
    94  			user, requestResource, requestInfo.Name, requestInfo.Namespace, err,
    95  		))
    96  	}
    97  	return decision == authorizer.DecisionAllow
    98  }
    99  
   100  // BindingAuthorized returns true if the user associated with the context is explicitly authorized to bind the specified roleRef
   101  func BindingAuthorized(ctx context.Context, roleRef rbac.RoleRef, bindingNamespace string, a authorizer.Authorizer) bool {
   102  	if a == nil {
   103  		return false
   104  	}
   105  
   106  	user, ok := genericapirequest.UserFrom(ctx)
   107  	if !ok {
   108  		return false
   109  	}
   110  
   111  	attrs := authorizer.AttributesRecord{
   112  		User: user,
   113  		Verb: "bind",
   114  		// check against the namespace where the binding is being created (or the empty namespace for clusterrolebindings).
   115  		// this allows delegation to bind particular clusterroles in rolebindings within particular namespaces,
   116  		// and to authorize binding a clusterrole across all namespaces in a clusterrolebinding.
   117  		Namespace:       bindingNamespace,
   118  		ResourceRequest: true,
   119  	}
   120  
   121  	// This occurs after defaulting and conversion, so values pulled from the roleRef won't change
   122  	// Invalid APIGroup or Name values will fail validation
   123  	switch roleRef.Kind {
   124  	case "ClusterRole":
   125  		attrs.APIGroup = roleRef.APIGroup
   126  		attrs.APIVersion = "*"
   127  		attrs.Resource = "clusterroles"
   128  		attrs.Name = roleRef.Name
   129  	case "Role":
   130  		attrs.APIGroup = roleRef.APIGroup
   131  		attrs.APIVersion = "*"
   132  		attrs.Resource = "roles"
   133  		attrs.Name = roleRef.Name
   134  	default:
   135  		return false
   136  	}
   137  
   138  	decision, _, err := a.Authorize(ctx, attrs)
   139  	if err != nil {
   140  		utilruntime.HandleError(fmt.Errorf(
   141  			"error authorizing user %#v to bind %#v in namespace %s: %v",
   142  			user, roleRef, bindingNamespace, err,
   143  		))
   144  	}
   145  	return decision == authorizer.DecisionAllow
   146  }
   147
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