github.com/zmap/zlint@v1.1.0/lints/lint_subject_printable_string_badalpha.go (about)

     1  /*
     2   * ZLint Copyright 2019 Regents of the University of Michigan
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License"); you may not
     5   * use this file except in compliance with the License. You may obtain a copy
     6   * of the License at http://www.apache.org/licenses/LICENSE-2.0
     7   *
     8   * Unless required by applicable law or agreed to in writing, software
     9   * distributed under the License is distributed on an "AS IS" BASIS,
    10   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
    11   * implied. See the License for the specific language governing
    12   * permissions and limitations under the License.
    13   */
    14  
    15  package lints
    16  
    17  import (
    18  	"encoding/asn1"
    19  	"errors"
    20  	"fmt"
    21  	"regexp"
    22  
    23  	"github.com/zmap/zcrypto/x509"
    24  	"github.com/zmap/zlint/util"
    25  )
    26  
    27  var (
    28  	// Per RFC 5280, Appendix B. ASN.1 Notes:
    29  	//   The character string type PrintableString supports a very basic Latin
    30  	//   character set: the lowercase letters 'a' through 'z', uppercase
    31  	//   letters 'A' through 'Z', the digits '0' through '9', eleven special
    32  	//   characters ' = ( ) + , - . / : ? and space.
    33  	printableStringRegex = regexp.MustCompile(`^[a-zA-Z0-9\=\(\)\+,\-.\/:\? ']+$`)
    34  )
    35  
    36  // validatePrintableString returns an error if the provided encoded printable
    37  // string doesn't adhere to the character set defined in RFC 5280.
    38  func validatePrintableString(rawPS []byte) error {
    39  	if !printableStringRegex.Match(rawPS) {
    40  		return errors.New("encoded PrintableString contained illegal characters")
    41  	}
    42  	return nil
    43  }
    44  
    45  type subjectPrintableStringBadAlpha struct {
    46  }
    47  
    48  func (l *subjectPrintableStringBadAlpha) Initialize() error {
    49  	return nil
    50  }
    51  
    52  // CheckApplies returns true for any certificate with a non-empty RawSubject.
    53  func (l *subjectPrintableStringBadAlpha) CheckApplies(c *x509.Certificate) bool {
    54  	return len(c.RawSubject) > 0
    55  }
    56  
    57  // Execute checks the certificate's RawSubject to ensure that any
    58  // PrintableString attribute/value pairs in the Subject match the character set
    59  // defined for this type in RFC 5280. An Error level LintResult is returned if any
    60  // of the PrintableString attributes do not match a regular expression for the
    61  // allowed character set.
    62  func (l *subjectPrintableStringBadAlpha) Execute(c *x509.Certificate) *LintResult {
    63  	rdnSequence := util.RawRDNSequence{}
    64  	rest, err := asn1.Unmarshal(c.RawSubject, &rdnSequence)
    65  	if err != nil {
    66  		return &LintResult{
    67  			Status:  Fatal,
    68  			Details: "Failed to Unmarshal RawSubject into RawRDNSequence",
    69  		}
    70  	}
    71  	if len(rest) > 0 {
    72  		return &LintResult{
    73  			Status:  Fatal,
    74  			Details: "Trailing data after RawSubject RawRDNSequence",
    75  		}
    76  	}
    77  
    78  	for _, attrTypeAndValueSet := range rdnSequence {
    79  		for _, attrTypeAndValue := range attrTypeAndValueSet {
    80  			// If the attribute type is a PrintableString the bytes of the attribute
    81  			// value must match the printable string alphabet.
    82  			if attrTypeAndValue.Value.Tag == asn1.TagPrintableString {
    83  				if err := validatePrintableString(attrTypeAndValue.Value.Bytes); err != nil {
    84  					return &LintResult{
    85  						Status: Error,
    86  						Details: fmt.Sprintf("RawSubject attr oid %s %s",
    87  							attrTypeAndValue.Type, err.Error()),
    88  					}
    89  				}
    90  			}
    91  		}
    92  	}
    93  
    94  	return &LintResult{
    95  		Status: Pass,
    96  	}
    97  }
    98  
    99  func init() {
   100  	RegisterLint(&Lint{
   101  		Name:          "e_subject_printable_string_badalpha",
   102  		Description:   "PrintableString type's alphabet only includes a-z, A-Z, 0-9, and 11 special characters",
   103  		Citation:      "RFC 5280: Appendix B. ASN.1 Notes",
   104  		Source:        RFC5280,
   105  		EffectiveDate: util.RFC2459Date,
   106  		Lint:          &subjectPrintableStringBadAlpha{},
   107  	})
   108  }