github.com/galamsiva2020/kubernetes-heapster-monitoring@v0.0.0-20210823134957-3c1baa7c1e70/metrics/auth.go (about)

     1  // Copyright 2014 Google Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package main
    16  
    17  import (
    18  	"crypto/x509"
    19  	"fmt"
    20  	"io/ioutil"
    21  	"net/http"
    22  	"strings"
    23  
    24  	"k8s.io/apiserver/pkg/authentication/authenticator"
    25  	x509request "k8s.io/apiserver/pkg/authentication/request/x509"
    26  	"k8s.io/apiserver/pkg/authentication/user"
    27  	"k8s.io/heapster/metrics/options"
    28  )
    29  
    30  func newAuthHandler(opt *options.HeapsterRunOptions, handler http.Handler) (http.Handler, error) {
    31  	// Authn/Authz setup
    32  	authn, err := newAuthenticatorFromClientCAFile(opt.TLSClientCAFile)
    33  	if err != nil {
    34  		return nil, err
    35  	}
    36  
    37  	authz, err := newAuthorizerFromUserList(strings.Split(opt.AllowedUsers, ",")...)
    38  	if err != nil {
    39  		return nil, err
    40  	}
    41  
    42  	return http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
    43  		// Check authn
    44  		user, ok, err := authn.AuthenticateRequest(req)
    45  		if err != nil {
    46  			http.Error(w, err.Error(), http.StatusInternalServerError)
    47  			return
    48  		}
    49  		if !ok {
    50  			http.Error(w, "Unauthorized", http.StatusUnauthorized)
    51  			return
    52  		}
    53  
    54  		// Check authz
    55  		allowed, err := authz.AuthorizeRequest(req, user)
    56  		if err != nil {
    57  			http.Error(w, err.Error(), http.StatusInternalServerError)
    58  			return
    59  		}
    60  		if !allowed {
    61  			http.Error(w, "Forbidden", http.StatusForbidden)
    62  			return
    63  		}
    64  
    65  		handler.ServeHTTP(w, req)
    66  	}), nil
    67  }
    68  
    69  // newAuthenticatorFromClientCAFile returns an authenticator.Request or an error
    70  func newAuthenticatorFromClientCAFile(clientCAFile string) (authenticator.Request, error) {
    71  	opts := x509request.DefaultVerifyOptions()
    72  
    73  	// If at custom CA bundle is provided, load it (otherwise just use system roots)
    74  	if len(clientCAFile) > 0 {
    75  		if caData, err := ioutil.ReadFile(clientCAFile); err != nil {
    76  			return nil, err
    77  		} else if len(caData) > 0 {
    78  			roots := x509.NewCertPool()
    79  			if !roots.AppendCertsFromPEM(caData) {
    80  				return nil, fmt.Errorf("no valid certs found in %s", clientCAFile)
    81  			}
    82  			opts.Roots = roots
    83  		}
    84  	}
    85  
    86  	return x509request.New(opts, x509request.CommonNameUserConversion), nil
    87  }
    88  
    89  type Authorizer interface {
    90  	AuthorizeRequest(req *http.Request, user user.Info) (bool, error)
    91  }
    92  
    93  func newAuthorizerFromUserList(allowedUsers ...string) (Authorizer, error) {
    94  	if len(allowedUsers) == 1 && len(allowedUsers[0]) == 0 {
    95  		return &allowAnyAuthorizer{}, nil
    96  	}
    97  	u := map[string]bool{}
    98  	for _, allowedUser := range allowedUsers {
    99  		u[allowedUser] = true
   100  	}
   101  	return &userAuthorizer{u}, nil
   102  }
   103  
   104  type allowAnyAuthorizer struct{}
   105  
   106  func (a *allowAnyAuthorizer) AuthorizeRequest(req *http.Request, user user.Info) (bool, error) {
   107  	return true, nil
   108  }
   109  
   110  type userAuthorizer struct {
   111  	allowedUsers map[string]bool
   112  }
   113  
   114  func (a *userAuthorizer) AuthorizeRequest(req *http.Request, user user.Info) (bool, error) {
   115  	return a.allowedUsers[user.GetName()], nil
   116  }