istio.io/istio@v0.0.0-20240520182934-d79c90f27776/security/pkg/server/ca/authenticate/xfcc_authenticator.go (about)

     1  // Copyright Istio Authors
     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 authenticate
    16  
    17  import (
    18  	"fmt"
    19  	"net"
    20  	"net/netip"
    21  	"strings"
    22  
    23  	"github.com/alecholmes/xfccparser"
    24  
    25  	"istio.io/istio/pilot/pkg/features"
    26  	"istio.io/istio/pkg/log"
    27  	"istio.io/istio/pkg/security"
    28  )
    29  
    30  const (
    31  	XfccAuthenticatorType = "XfccAuthenticator"
    32  )
    33  
    34  // XfccAuthenticator extracts identities from Xfcc header.
    35  type XfccAuthenticator struct{}
    36  
    37  var _ security.Authenticator = &XfccAuthenticator{}
    38  
    39  func (xff XfccAuthenticator) AuthenticatorType() string {
    40  	return XfccAuthenticatorType
    41  }
    42  
    43  // Authenticate extracts identities from Xfcc Header.
    44  func (xff XfccAuthenticator) Authenticate(ctx security.AuthContext) (*security.Caller, error) {
    45  	remoteAddr := ctx.RemoteAddress()
    46  	xfccHeader := ctx.Header(xfccparser.ForwardedClientCertHeader)
    47  	if len(remoteAddr) == 0 || len(xfccHeader) == 0 {
    48  		return nil, fmt.Errorf("caller from %s does not have Xfcc header", remoteAddr)
    49  	}
    50  	// First check if client is trusted client so that we can "trust" the Xfcc Header.
    51  	if !isTrustedAddress(remoteAddr, features.TrustedGatewayCIDR) {
    52  		return nil, fmt.Errorf("caller from %s is not in the trusted network. XfccAuthenticator can not be used", remoteAddr)
    53  	}
    54  
    55  	return buildSecurityCaller(xfccHeader[0])
    56  }
    57  
    58  func buildSecurityCaller(xfccHeader string) (*security.Caller, error) {
    59  	clientCerts, err := xfccparser.ParseXFCCHeader(xfccHeader)
    60  	if err != nil {
    61  		message := fmt.Sprintf("error in parsing xfcc header: %v", err)
    62  		return nil, fmt.Errorf(message)
    63  	}
    64  	if len(clientCerts) == 0 {
    65  		message := "xfcc header does not have atleast one client certs"
    66  		return nil, fmt.Errorf(message)
    67  	}
    68  	ids := []string{}
    69  	for _, cc := range clientCerts {
    70  		ids = append(ids, cc.URI...)
    71  		ids = append(ids, cc.DNS...)
    72  		if cc.Subject != nil {
    73  			ids = append(ids, cc.Subject.CommonName)
    74  		}
    75  	}
    76  
    77  	return &security.Caller{
    78  		AuthSource: security.AuthSourceClientCertificate,
    79  		Identities: ids,
    80  	}, nil
    81  }
    82  
    83  func isTrustedAddress(addr string, trustedCidrs []string) bool {
    84  	ip, _, err := net.SplitHostPort(addr)
    85  	if err != nil {
    86  		log.Warnf("peer address %s can not be split in to proper host and port", addr)
    87  		return false
    88  	}
    89  	for _, cidr := range trustedCidrs {
    90  		if isInRange(ip, cidr) {
    91  			return true
    92  		}
    93  	}
    94  	// Always trust local host addresses.
    95  	return netip.MustParseAddr(ip).IsLoopback()
    96  }
    97  
    98  func isInRange(addr, cidr string) bool {
    99  	if strings.Contains(cidr, "/") {
   100  		ipp, err := netip.ParsePrefix(cidr)
   101  		if err != nil {
   102  			return false
   103  		}
   104  
   105  		return ipp.Contains(netip.MustParseAddr(addr))
   106  	}
   107  	return false
   108  }