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25  
26  package sun.security.x509;
27  
28  import java.io.IOException;
29  import java.io.OutputStream;
30  import java.security.cert.CertificateException;
31  import java.security.cert.X509Certificate;
32  import java.util.*;
33  
34  import javax.security.auth.x500.X500Principal;
35  
36  import sun.security.util.*;
37  import sun.security.pkcs.PKCS9Attribute;
38  
39  /**
40   * This class defines the Name Constraints Extension.
41   * <p>
42   * The name constraints extension provides permitted and excluded
43   * subtrees that place restrictions on names that may be included within
44   * a certificate issued by a given CA.  Restrictions may apply to the
45   * subject distinguished name or subject alternative names.  Any name
46   * matching a restriction in the excluded subtrees field is invalid
47   * regardless of information appearing in the permitted subtrees.
48   * <p>
49   * The ASN.1 syntax for this is:
50   * <pre>
51   * NameConstraints ::= SEQUENCE {
52   *    permittedSubtrees [0]  GeneralSubtrees OPTIONAL,
53   *    excludedSubtrees  [1]  GeneralSubtrees OPTIONAL
54   * }
55   * GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
56   * </pre>
57   *
58   * @author Amit Kapoor
59   * @author Hemma Prafullchandra
60   * @see Extension
61   * @see CertAttrSet
62   */
63  public class NameConstraintsExtension extends Extension
64  implements CertAttrSet<String>, Cloneable {
65      /**
66       * Identifier for this attribute, to be used with the
67       * get, set, delete methods of Certificate, x509 type.
68       */
69      public static final String IDENT = "x509.info.extensions.NameConstraints";
70      /**
71       * Attribute names.
72       */
73      public static final String NAME = "NameConstraints";
74      public static final String PERMITTED_SUBTREES = "permitted_subtrees";
75      public static final String EXCLUDED_SUBTREES = "excluded_subtrees";
76  
77      // Private data members
78      private static final byte TAG_PERMITTED = 0;
79      private static final byte TAG_EXCLUDED = 1;
80  
81      private GeneralSubtrees     permitted = null;
82      private GeneralSubtrees     excluded = null;
83  
84      private boolean hasMin;
85      private boolean hasMax;
86      private boolean minMaxValid = false;
87  
88      // Recalculate hasMin and hasMax flags.
89      private void calcMinMax() throws IOException {
90          hasMin = false;
91          hasMax = false;
92          if (excluded != null) {
93              for (int i = 0; i < excluded.size(); i++) {
94                  GeneralSubtree subtree = excluded.get(i);
95                  if (subtree.getMinimum() != 0)
96                      hasMin = true;
97                  if (subtree.getMaximum() != -1)
98                      hasMax = true;
99              }
100         }
101 
102         if (permitted != null) {
103             for (int i = 0; i < permitted.size(); i++) {
104                 GeneralSubtree subtree = permitted.get(i);
105                 if (subtree.getMinimum() != 0)
106                     hasMin = true;
107                 if (subtree.getMaximum() != -1)
108                     hasMax = true;
109             }
110         }
111         minMaxValid = true;
112     }
113 
114     // Encode this extension value.
115     private void encodeThis() throws IOException {
116         minMaxValid = false;
117         if (permitted == null && excluded == null) {
118             this.extensionValue = null;
119             return;
120         }
121         DerOutputStream seq = new DerOutputStream();
122 
123         DerOutputStream tagged = new DerOutputStream();
124         if (permitted != null) {
125             DerOutputStream tmp = new DerOutputStream();
126             permitted.encode(tmp);
127             tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
128                                  true, TAG_PERMITTED), tmp);
129         }
130         if (excluded != null) {
131             DerOutputStream tmp = new DerOutputStream();
132             excluded.encode(tmp);
133             tagged.writeImplicit(DerValue.createTag(DerValue.TAG_CONTEXT,
134                                  true, TAG_EXCLUDED), tmp);
135         }
136         seq.write(DerValue.tag_Sequence, tagged);
137         this.extensionValue = seq.toByteArray();
138     }
139 
140     /**
141      * The default constructor for this class. Both parameters
142      * are optional and can be set to null.  The extension criticality
143      * is set to true.
144      *
145      * @param permitted the permitted GeneralSubtrees (null for optional).
146      * @param excluded the excluded GeneralSubtrees (null for optional).
147      */
148     public NameConstraintsExtension(GeneralSubtrees permitted,
149                                     GeneralSubtrees excluded)
150     throws IOException {
151         this.permitted = permitted;
152         this.excluded = excluded;
153 
154         this.extensionId = PKIXExtensions.NameConstraints_Id;
155         this.critical = true;
156         encodeThis();
157     }
158 
159     /**
160      * Create the extension from the passed DER encoded value.
161      *
162      * @param critical true if the extension is to be treated as critical.
163      * @param value an array of DER encoded bytes of the actual value.
164      * @exception ClassCastException if value is not an array of bytes
165      * @exception IOException on error.
166      */
167     public NameConstraintsExtension(Boolean critical, Object value)
168     throws IOException {
169         this.extensionId = PKIXExtensions.NameConstraints_Id;
170         this.critical = critical.booleanValue();
171 
172         this.extensionValue = (byte[]) value;
173         DerValue val = new DerValue(this.extensionValue);
174         if (val.tag != DerValue.tag_Sequence) {
175             throw new IOException("Invalid encoding for" +
176                                   " NameConstraintsExtension.");
177         }
178 
179         // NB. this is always encoded with the IMPLICIT tag
180         // The checks only make sense if we assume implicit tagging,
181         // with explicit tagging the form is always constructed.
182         // Note that all the fields in NameConstraints are defined as
183         // being OPTIONAL, i.e., there could be an empty SEQUENCE, resulting
184         // in val.data being null.
185         if (val.data == null)
186             return;
187         while (val.data.available() != 0) {
188             DerValue opt = val.data.getDerValue();
189 
190             if (opt.isContextSpecific(TAG_PERMITTED) && opt.isConstructed()) {
191                 if (permitted != null) {
192                     throw new IOException("Duplicate permitted " +
193                          "GeneralSubtrees in NameConstraintsExtension.");
194                 }
195                 opt.resetTag(DerValue.tag_Sequence);
196                 permitted = new GeneralSubtrees(opt);
197 
198             } else if (opt.isContextSpecific(TAG_EXCLUDED) &&
199                        opt.isConstructed()) {
200                 if (excluded != null) {
201                     throw new IOException("Duplicate excluded " +
202                              "GeneralSubtrees in NameConstraintsExtension.");
203                 }
204                 opt.resetTag(DerValue.tag_Sequence);
205                 excluded = new GeneralSubtrees(opt);
206             } else
207                 throw new IOException("Invalid encoding of " +
208                                       "NameConstraintsExtension.");
209         }
210         minMaxValid = false;
211     }
212 
213     /**
214      * Return the printable string.
215      */
216     public String toString() {
217         return (super.toString() + "NameConstraints: [" +
218                 ((permitted == null) ? "" :
219                      ("\n    Permitted:" + permitted.toString())) +
220                 ((excluded == null) ? "" :
221                      ("\n    Excluded:" + excluded.toString()))
222                 + "   ]\n");
223     }
224 
225     /**
226      * Write the extension to the OutputStream.
227      *
228      * @param out the OutputStream to write the extension to.
229      * @exception IOException on encoding errors.
230      */
231     public void encode(OutputStream out) throws IOException {
232         DerOutputStream tmp = new DerOutputStream();
233         if (this.extensionValue == null) {
234             this.extensionId = PKIXExtensions.NameConstraints_Id;
235             this.critical = true;
236             encodeThis();
237         }
238         super.encode(tmp);
239         out.write(tmp.toByteArray());
240     }
241 
242     /**
243      * Set the attribute value.
244      */
245     public void set(String name, Object obj) throws IOException {
246         if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
247             if (!(obj instanceof GeneralSubtrees)) {
248                 throw new IOException("Attribute value should be"
249                                     + " of type GeneralSubtrees.");
250             }
251             permitted = (GeneralSubtrees)obj;
252         } else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
253             if (!(obj instanceof GeneralSubtrees)) {
254                 throw new IOException("Attribute value should be "
255                                     + "of type GeneralSubtrees.");
256             }
257             excluded = (GeneralSubtrees)obj;
258         } else {
259           throw new IOException("Attribute name not recognized by " +
260                         "CertAttrSet:NameConstraintsExtension.");
261         }
262         encodeThis();
263     }
264 
265     /**
266      * Get the attribute value.
267      */
268     public GeneralSubtrees get(String name) throws IOException {
269         if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
270             return (permitted);
271         } else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
272             return (excluded);
273         } else {
274           throw new IOException("Attribute name not recognized by " +
275                         "CertAttrSet:NameConstraintsExtension.");
276         }
277     }
278 
279     /**
280      * Delete the attribute value.
281      */
282     public void delete(String name) throws IOException {
283         if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
284             permitted = null;
285         } else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
286             excluded = null;
287         } else {
288           throw new IOException("Attribute name not recognized by " +
289                         "CertAttrSet:NameConstraintsExtension.");
290         }
291         encodeThis();
292     }
293 
294     /**
295      * Return an enumeration of names of attributes existing within this
296      * attribute.
297      */
298     public Enumeration<String> getElements() {
299         AttributeNameEnumeration elements = new AttributeNameEnumeration();
300         elements.addElement(PERMITTED_SUBTREES);
301         elements.addElement(EXCLUDED_SUBTREES);
302 
303         return (elements.elements());
304     }
305 
306     /**
307      * Return the name of this attribute.
308      */
309     public String getName() {
310         return (NAME);
311     }
312 
313     /**
314      * Merge additional name constraints with existing ones.
315      * This function is used in certification path processing
316      * to accumulate name constraints from successive certificates
317      * in the path.  Note that NameConstraints can never be
318      * expanded by a merge, just remain constant or become more
319      * limiting.
320      * <p>
321      * IETF RFC2459 specifies the processing of Name Constraints as
322      * follows:
323      * <p>
324      * (j)  If permittedSubtrees is present in the certificate, set the
325      * constrained subtrees state variable to the intersection of its
326      * previous value and the value indicated in the extension field.
327      * <p>
328      * (k)  If excludedSubtrees is present in the certificate, set the
329      * excluded subtrees state variable to the union of its previous
330      * value and the value indicated in the extension field.
331      * <p>
332      * @param newConstraints additional NameConstraints to be applied
333      * @throws IOException on error
334      */
335     public void merge(NameConstraintsExtension newConstraints)
336             throws IOException {
337 
338         if (newConstraints == null) {
339             // absence of any explicit constraints implies unconstrained
340             return;
341         }
342 
343         /*
344          * If excludedSubtrees is present in the certificate, set the
345          * excluded subtrees state variable to the union of its previous
346          * value and the value indicated in the extension field.
347          */
348 
349         GeneralSubtrees newExcluded = newConstraints.get(EXCLUDED_SUBTREES);
350         if (excluded == null) {
351             excluded = (newExcluded != null) ?
352                         (GeneralSubtrees)newExcluded.clone() : null;
353         } else {
354             if (newExcluded != null) {
355                 // Merge new excluded with current excluded (union)
356                 excluded.union(newExcluded);
357             }
358         }
359 
360         /*
361          * If permittedSubtrees is present in the certificate, set the
362          * constrained subtrees state variable to the intersection of its
363          * previous value and the value indicated in the extension field.
364          */
365 
366         GeneralSubtrees newPermitted = newConstraints.get(PERMITTED_SUBTREES);
367         if (permitted == null) {
368             permitted = (newPermitted != null) ?
369                         (GeneralSubtrees)newPermitted.clone() : null;
370         } else {
371             if (newPermitted != null) {
372                 // Merge new permitted with current permitted (intersection)
373                 newExcluded = permitted.intersect(newPermitted);
374 
375                 // Merge new excluded subtrees to current excluded (union)
376                 if (newExcluded != null) {
377                     if (excluded != null) {
378                         excluded.union(newExcluded);
379                     } else {
380                         excluded = (GeneralSubtrees)newExcluded.clone();
381                     }
382                 }
383             }
384         }
385 
386         // Optional optimization: remove permitted subtrees that are excluded.
387         // This is not necessary for algorithm correctness, but it makes
388         // subsequent operations on the NameConstraints faster and require
389         // less space.
390         if (permitted != null) {
391             permitted.reduce(excluded);
392         }
393 
394         // The NameConstraints have been changed, so re-encode them.  Methods in
395         // this class assume that the encodings have already been done.
396         encodeThis();
397 
398     }
399 
400     /**
401      * check whether a certificate conforms to these NameConstraints.
402      * This involves verifying that the subject name and subjectAltName
403      * extension (critical or noncritical) is consistent with the permitted
404      * subtrees state variables.  Also verify that the subject name and
405      * subjectAltName extension (critical or noncritical) is consistent with
406      * the excluded subtrees state variables.
407      *
408      * @param cert X509Certificate to be verified
409      * @returns true if certificate verifies successfully
410      * @throws IOException on error
411      */
412     public boolean verify(X509Certificate cert) throws IOException {
413 
414         if (cert == null) {
415             throw new IOException("Certificate is null");
416         }
417 
418         // Calculate hasMin and hasMax booleans (if necessary)
419         if (!minMaxValid) {
420             calcMinMax();
421         }
422 
423         if (hasMin) {
424             throw new IOException("Non-zero minimum BaseDistance in"
425                                 + " name constraints not supported");
426         }
427 
428         if (hasMax) {
429             throw new IOException("Maximum BaseDistance in"
430                                 + " name constraints not supported");
431         }
432 
433         X500Principal subjectPrincipal = cert.getSubjectX500Principal();
434         X500Name subject = X500Name.asX500Name(subjectPrincipal);
435 
436         if (subject.isEmpty() == false) {
437             if (verify(subject) == false) {
438                 return false;
439             }
440         }
441 
442         GeneralNames altNames = null;
443         // extract altNames
444         try {
445             // extract extensions, if any, from certInfo
446             // following returns null if certificate contains no extensions
447             X509CertImpl certImpl = X509CertImpl.toImpl(cert);
448             SubjectAlternativeNameExtension altNameExt =
449                 certImpl.getSubjectAlternativeNameExtension();
450             if (altNameExt != null) {
451                 // extract altNames from extension; this call does not
452                 // return an IOException on null altnames
453                 altNames = altNameExt.get(
454                         SubjectAlternativeNameExtension.SUBJECT_NAME);
455             }
456         } catch (CertificateException ce) {
457             throw new IOException("Unable to extract extensions from " +
458                         "certificate: " + ce.getMessage());
459         }
460 
461         // If there are no subjectAlternativeNames, perform the special-case
462         // check where if the subjectName contains any EMAILADDRESS
463         // attributes, they must be checked against RFC822 constraints.
464         // If that passes, we're fine.
465         if (altNames == null) {
466             return verifyRFC822SpecialCase(subject);
467         }
468 
469         // verify each subjectAltName
470         for (int i = 0; i < altNames.size(); i++) {
471             GeneralNameInterface altGNI = altNames.get(i).getName();
472             if (!verify(altGNI)) {
473                 return false;
474             }
475         }
476 
477         // All tests passed.
478         return true;
479     }
480 
481     /**
482      * check whether a name conforms to these NameConstraints.
483      * This involves verifying that the name is consistent with the
484      * permitted and excluded subtrees variables.
485      *
486      * @param name GeneralNameInterface name to be verified
487      * @returns true if certificate verifies successfully
488      * @throws IOException on error
489      */
490     public boolean verify(GeneralNameInterface name) throws IOException {
491         if (name == null) {
492             throw new IOException("name is null");
493         }
494 
495         // Verify that the name is consistent with the excluded subtrees
496         if (excluded != null && excluded.size() > 0) {
497 
498             for (int i = 0; i < excluded.size(); i++) {
499                 GeneralSubtree gs = excluded.get(i);
500                 if (gs == null)
501                     continue;
502                 GeneralName gn = gs.getName();
503                 if (gn == null)
504                     continue;
505                 GeneralNameInterface exName = gn.getName();
506                 if (exName == null)
507                     continue;
508 
509                 // if name matches or narrows any excluded subtree,
510                 // return false
511                 switch (exName.constrains(name)) {
512                 case GeneralNameInterface.NAME_DIFF_TYPE:
513                 case GeneralNameInterface.NAME_WIDENS: // name widens excluded
514                 case GeneralNameInterface.NAME_SAME_TYPE:
515                     break;
516                 case GeneralNameInterface.NAME_MATCH:
517                 case GeneralNameInterface.NAME_NARROWS: // subject name excluded
518                     return false;
519                 }
520             }
521         }
522 
523         // Verify that the name is consistent with the permitted subtrees
524         if (permitted != null && permitted.size() > 0) {
525 
526             boolean sameType = false;
527 
528             for (int i = 0; i < permitted.size(); i++) {
529                 GeneralSubtree gs = permitted.get(i);
530                 if (gs == null)
531                     continue;
532                 GeneralName gn = gs.getName();
533                 if (gn == null)
534                     continue;
535                 GeneralNameInterface perName = gn.getName();
536                 if (perName == null)
537                     continue;
538 
539                 // if Name matches any type in permitted,
540                 // and Name does not match or narrow some permitted subtree,
541                 // return false
542                 switch (perName.constrains(name)) {
543                 case GeneralNameInterface.NAME_DIFF_TYPE:
544                     continue; // continue checking other permitted names
545                 case GeneralNameInterface.NAME_WIDENS: // name widens permitted
546                 case GeneralNameInterface.NAME_SAME_TYPE:
547                     sameType = true;
548                     continue; // continue to look for a match or narrow
549                 case GeneralNameInterface.NAME_MATCH:
550                 case GeneralNameInterface.NAME_NARROWS:
551                     // name narrows permitted
552                     return true; // name is definitely OK, so break out of loop
553                 }
554             }
555             if (sameType) {
556                 return false;
557             }
558         }
559         return true;
560     }
561 
562     /**
563      * Perform the RFC 822 special case check. We have a certificate
564      * that does not contain any subject alternative names. Check that
565      * any EMAILADDRESS attributes in its subject name conform to these
566      * NameConstraints.
567      *
568      * @param subject the certificate's subject name
569      * @returns true if certificate verifies successfully
570      * @throws IOException on error
571      */
572     public boolean verifyRFC822SpecialCase(X500Name subject) throws IOException {
573         for (AVA ava : subject.allAvas()) {
574             ObjectIdentifier attrOID = ava.getObjectIdentifier();
575             if (attrOID.equals((Object)PKCS9Attribute.EMAIL_ADDRESS_OID)) {
576                 String attrValue = ava.getValueString();
577                 if (attrValue != null) {
578                     RFC822Name emailName;
579                     try {
580                         emailName = new RFC822Name(attrValue);
581                     } catch (IOException ioe) {
582                         continue;
583                     }
584                     if (!verify(emailName)) {
585                         return(false);
586                     }
587                 }
588              }
589         }
590         return true;
591     }
592 
593     /**
594      * Clone all objects that may be modified during certificate validation.
595      */
596     public Object clone() {
597         try {
598             NameConstraintsExtension newNCE =
599                 (NameConstraintsExtension) super.clone();
600 
601             if (permitted != null) {
602                 newNCE.permitted = (GeneralSubtrees) permitted.clone();
603             }
604             if (excluded != null) {
605                 newNCE.excluded = (GeneralSubtrees) excluded.clone();
606             }
607             return newNCE;
608         } catch (CloneNotSupportedException cnsee) {
609             throw new RuntimeException("CloneNotSupportedException while " +
610                 "cloning NameConstraintsException. This should never happen.");
611         }
612     }
613 }