1 #----------------------------------------------------------------------
2 # Copyright (c) 2008 Board of Trustees, Princeton University
4 # Permission is hereby granted, free of charge, to any person obtaining
5 # a copy of this software and/or hardware specification (the "Work") to
6 # deal in the Work without restriction, including without limitation the
7 # rights to use, copy, modify, merge, publish, distribute, sublicense,
8 # and/or sell copies of the Work, and to permit persons to whom the Work
9 # is furnished to do so, subject to the following conditions:
11 # The above copyright notice and this permission notice shall be
12 # included in all copies or substantial portions of the Work.
14 # THE WORK IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
17 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
18 # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
19 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 # OUT OF OR IN CONNECTION WITH THE WORK OR THE USE OR OTHER DEALINGS
22 #----------------------------------------------------------------------
24 # Implements SFA Credentials
26 # Credentials are signed XML files that assign a subject gid privileges to an object gid
29 ### $Id: credential.py 18654 2010-08-23 18:54:57Z tmack $
30 ### $URL: http://svn.planet-lab.org/svn/sfa/trunk/sfa/trust/credential.py $
34 from xml.dom.minidom import Document, parseString
35 from tempfile import mkstemp
36 from sfa.trust.certificate import Keypair
37 from sfa.trust.credential_legacy import CredentialLegacy
38 from sfa.trust.rights import *
39 from sfa.trust.gid import *
40 from sfa.util.faults import *
42 from sfa.util.sfalogging import logger
43 from dateutil.parser import parse
47 # Two years, in seconds
48 DEFAULT_CREDENTIAL_LIFETIME = 60 * 60 * 24 * 365 * 2
52 # . make privs match between PG and PL
53 # . Need to add support for other types of credentials, e.g. tickets
56 signature_template = \
58 <Signature xml:id="Sig_%s" xmlns="http://www.w3.org/2000/09/xmldsig#">
60 <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
61 <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
64 <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
66 <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
67 <DigestValue></DigestValue>
83 # Convert a string into a bool
86 if str.lower() in ['yes','true','1']:
92 # Utility function to get the text of an XML element
94 def getTextNode(element, subele):
95 sub = element.getElementsByTagName(subele)[0]
96 if len(sub.childNodes) > 0:
97 return sub.childNodes[0].nodeValue
102 # Utility function to set the text of an XML element
103 # It creates the element, adds the text to it,
104 # and then appends it to the parent.
106 def append_sub(doc, parent, element, text):
107 ele = doc.createElement(element)
108 ele.appendChild(doc.createTextNode(text))
109 parent.appendChild(ele)
112 # Signature contains information about an xmlsec1 signature
113 # for a signed-credential
116 class Signature(object):
118 def __init__(self, string=None):
120 self.issuer_gid = None
137 def set_refid(self, id):
140 def get_issuer_gid(self):
145 def set_issuer_gid(self, gid):
149 doc = parseString(self.xml)
150 sig = doc.getElementsByTagName("Signature")[0]
151 self.set_refid(sig.getAttribute("xml:id").strip("Sig_"))
152 keyinfo = sig.getElementsByTagName("X509Data")[0]
153 szgid = getTextNode(keyinfo, "X509Certificate")
154 szgid = "-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----" % szgid
155 self.set_issuer_gid(GID(string=szgid))
158 self.xml = signature_template % (self.get_refid(), self.get_refid())
162 # A credential provides a caller gid with privileges to an object gid.
163 # A signed credential is signed by the object's authority.
165 # Credentials are encoded in one of two ways. The legacy style places
166 # it in the subjectAltName of an X509 certificate. The new credentials
167 # are placed in signed XML.
170 # In general, a signed credential obtained externally should
171 # not be changed else the signature is no longer valid. So, once
172 # you have loaded an existing signed credential, do not call encode() or sign() on it.
174 def filter_creds_by_caller(creds, caller_hrn):
176 Returns a list of creds who's gid caller matches the
179 if not isinstance(creds, list): creds = [creds]
183 tmp_cred = Credential(string=cred)
184 if tmp_cred.get_gid_caller().get_hrn() == caller_hrn:
185 caller_creds.append(cred)
189 class Credential(object):
192 # Create a Credential object
194 # @param create If true, create a blank x509 certificate
195 # @param subject If subject!=None, create an x509 cert with the subject name
196 # @param string If string!=None, load the credential from the string
197 # @param filename If filename!=None, load the credential from the file
198 # FIXME: create and subject are ignored!
199 def __init__(self, create=False, subject=None, string=None, filename=None):
200 self.gidCaller = None
201 self.gidObject = None
202 self.expiration = None
203 self.privileges = None
204 self.issuer_privkey = None
205 self.issuer_gid = None
206 self.issuer_pubkey = None
208 self.signature = None
213 # Check if this is a legacy credential, translate it if so
214 if string or filename:
218 str = file(filename).read()
220 if str.strip().startswith("-----"):
221 self.legacy = CredentialLegacy(False,string=str)
222 self.translate_legacy(str)
227 # Find an xmlsec1 path
228 self.xmlsec_path = ''
229 paths = ['/usr/bin','/usr/local/bin','/bin','/opt/bin','/opt/local/bin']
231 if os.path.isfile(path + '/' + 'xmlsec1'):
232 self.xmlsec_path = path + '/' + 'xmlsec1'
235 def get_subject(self):
236 if not self.gidObject:
238 return self.gidObject.get_subject()
240 def get_signature(self):
241 if not self.signature:
243 return self.signature
245 def set_signature(self, sig):
250 # Translate a legacy credential into a new one
252 # @param String of the legacy credential
254 def translate_legacy(self, str):
255 legacy = CredentialLegacy(False,string=str)
256 self.gidCaller = legacy.get_gid_caller()
257 self.gidObject = legacy.get_gid_object()
258 lifetime = legacy.get_lifetime()
260 # Default to two years
261 self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME)
263 self.set_lifetime(int(lifetime))
264 self.lifeTime = legacy.get_lifetime()
265 self.set_privileges(legacy.get_privileges())
266 self.get_privileges().delegate_all_privileges(legacy.get_delegate())
269 # Need the issuer's private key and name
270 # @param key Keypair object containing the private key of the issuer
271 # @param gid GID of the issuing authority
273 def set_issuer_keys(self, privkey, gid):
274 self.issuer_privkey = privkey
275 self.issuer_gid = gid
279 # Set this credential's parent
280 def set_parent(self, cred):
285 # set the GID of the caller
287 # @param gid GID object of the caller
289 def set_gid_caller(self, gid):
291 # gid origin caller is the caller's gid by default
292 self.gidOriginCaller = gid
295 # get the GID of the object
297 def get_gid_caller(self):
298 if not self.gidCaller:
300 return self.gidCaller
303 # set the GID of the object
305 # @param gid GID object of the object
307 def set_gid_object(self, gid):
311 # get the GID of the object
313 def get_gid_object(self):
314 if not self.gidObject:
316 return self.gidObject
319 # set the lifetime of this credential
321 # @param lifetime lifetime of credential
322 # . if lifeTime is a datetime object, it is used for the expiration time
323 # . if lifeTime is an integer value, it is considered the number of seconds
324 # remaining before expiration
326 def set_lifetime(self, lifeTime):
327 if isinstance(lifeTime, int):
328 self.expiration = datetime.timedelta(seconds=lifeTime) + datetime.datetime.utcnow()
330 self.expiration = lifeTime
333 # get the lifetime of the credential (in datetime format)
335 def get_lifetime(self):
336 if not self.expiration:
338 return self.expiration
344 # @param privs either a comma-separated list of privileges of a RightList object
346 def set_privileges(self, privs):
347 if isinstance(privs, str):
348 self.privileges = RightList(string = privs)
350 self.privileges = privs
354 # return the privileges as a RightList object
356 def get_privileges(self):
357 if not self.privileges:
359 return self.privileges
362 # determine whether the credential allows a particular operation to be
365 # @param op_name string specifying name of operation ("lookup", "update", etc)
367 def can_perform(self, op_name):
368 rights = self.get_privileges()
373 return rights.can_perform(op_name)
377 # Encode the attributes of the credential into an XML string
378 # This should be done immediately before signing the credential.
380 # In general, a signed credential obtained externally should
381 # not be changed else the signature is no longer valid. So, once
382 # you have loaded an existing signed credential, do not call encode() or sign() on it.
385 # Create the XML document
387 signed_cred = doc.createElement("signed-credential")
388 doc.appendChild(signed_cred)
390 # Fill in the <credential> bit
391 cred = doc.createElement("credential")
392 cred.setAttribute("xml:id", self.get_refid())
393 signed_cred.appendChild(cred)
394 append_sub(doc, cred, "type", "privilege")
395 append_sub(doc, cred, "serial", "8")
396 append_sub(doc, cred, "owner_gid", self.gidCaller.save_to_string())
397 append_sub(doc, cred, "owner_urn", self.gidCaller.get_urn())
398 append_sub(doc, cred, "target_gid", self.gidObject.save_to_string())
399 append_sub(doc, cred, "target_urn", self.gidObject.get_urn())
400 append_sub(doc, cred, "uuid", "")
401 if not self.expiration:
402 self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME)
403 self.expiration = self.expiration.replace(microsecond=0)
404 append_sub(doc, cred, "expires", self.expiration.isoformat())
405 privileges = doc.createElement("privileges")
406 cred.appendChild(privileges)
409 rights = self.get_privileges()
410 for right in rights.rights:
411 priv = doc.createElement("privilege")
412 append_sub(doc, priv, "name", right.kind)
413 append_sub(doc, priv, "can_delegate", str(right.delegate).lower())
414 privileges.appendChild(priv)
416 # Add the parent credential if it exists
418 sdoc = parseString(self.parent.get_xml())
419 p_cred = doc.importNode(sdoc.getElementsByTagName("credential")[0], True)
420 p = doc.createElement("parent")
421 p.appendChild(p_cred)
425 # Create the <signatures> tag
426 signatures = doc.createElement("signatures")
427 signed_cred.appendChild(signatures)
429 # Add any parent signatures
431 for cur_cred in self.get_credential_list()[1:]:
432 sdoc = parseString(cur_cred.get_signature().get_xml())
433 ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
434 signatures.appendChild(ele)
436 # Get the finished product
437 self.xml = doc.toxml()
440 def save_to_random_tmp_file(self):
441 fp, filename = mkstemp(suffix='cred', text=True)
442 fp = os.fdopen(fp, "w")
443 self.save_to_file(filename, save_parents=True, filep=fp)
446 def save_to_file(self, filename, save_parents=True, filep=None):
452 f = open(filename, "w")
456 def save_to_string(self, save_parents=True):
466 def set_refid(self, rid):
470 # Figure out what refids exist, and update this credential's id
471 # so that it doesn't clobber the others. Returns the refids of
474 def updateRefID(self):
476 self.set_refid('ref0')
481 next_cred = self.parent
483 refs.append(next_cred.get_refid())
485 next_cred = next_cred.parent
490 # Find a unique refid for this credential
491 rid = self.get_refid()
494 rid = "ref%d" % (val + 1)
499 # Return the set of parent credential ref ids
508 # Sign the XML file created by encode()
511 # In general, a signed credential obtained externally should
512 # not be changed else the signature is no longer valid. So, once
513 # you have loaded an existing signed credential, do not call encode() or sign() on it.
516 if not self.issuer_privkey or not self.issuer_gid:
518 doc = parseString(self.get_xml())
519 sigs = doc.getElementsByTagName("signatures")[0]
521 # Create the signature template to be signed
522 signature = Signature()
523 signature.set_refid(self.get_refid())
524 sdoc = parseString(signature.get_xml())
525 sig_ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
526 sigs.appendChild(sig_ele)
528 self.xml = doc.toxml()
531 # Split the issuer GID into multiple certificates if it's a chain
532 chain = GID(filename=self.issuer_gid)
535 gid_files.append(chain.save_to_random_tmp_file(False))
536 if chain.get_parent():
537 chain = chain.get_parent()
542 # Call out to xmlsec1 to sign it
543 ref = 'Sig_%s' % self.get_refid()
544 filename = self.save_to_random_tmp_file()
545 signed = os.popen('%s --sign --node-id "%s" --privkey-pem %s,%s %s' \
546 % (self.xmlsec_path, ref, self.issuer_privkey, ",".join(gid_files), filename)).read()
549 for gid_file in gid_files:
554 # This is no longer a legacy credential
563 # Retrieve the attributes of the credential from the XML.
564 # This is automatically called by the various get_* methods of
565 # this class and should not need to be called explicitly.
570 doc = parseString(self.xml)
572 signed_cred = doc.getElementsByTagName("signed-credential")
574 # Is this a signed-cred or just a cred?
575 if len(signed_cred) > 0:
576 cred = signed_cred[0].getElementsByTagName("credential")[0]
577 signatures = signed_cred[0].getElementsByTagName("signatures")
578 if len(signatures) > 0:
579 sigs = signatures[0].getElementsByTagName("Signature")
581 cred = doc.getElementsByTagName("credential")[0]
584 self.set_refid(cred.getAttribute("xml:id"))
585 self.set_lifetime(parse(getTextNode(cred, "expires")))
586 self.gidCaller = GID(string=getTextNode(cred, "owner_gid"))
587 self.gidObject = GID(string=getTextNode(cred, "target_gid"))
591 privs = cred.getElementsByTagName("privileges")[0]
593 for priv in privs.getElementsByTagName("privilege"):
594 kind = getTextNode(priv, "name")
595 deleg = str2bool(getTextNode(priv, "can_delegate"))
597 # Convert * into the default privileges for the credential's type
598 _ , type = urn_to_hrn(self.gidObject.get_urn())
599 rl = rlist.determine_rights(type, self.gidObject.get_urn())
603 rlist.add(Right(kind.strip(), deleg))
604 self.set_privileges(rlist)
608 parent = cred.getElementsByTagName("parent")
610 parent_doc = parent[0].getElementsByTagName("credential")[0]
611 parent_xml = parent_doc.toxml()
612 self.parent = Credential(string=parent_xml)
615 # Assign the signatures to the credentials
617 Sig = Signature(string=sig.toxml())
619 for cur_cred in self.get_credential_list():
620 if cur_cred.get_refid() == Sig.get_refid():
621 cur_cred.set_signature(Sig)
626 # trusted_certs: A list of trusted GID filenames (not GID objects!)
627 # Chaining is not supported within the GIDs by xmlsec1.
630 # . All of the signatures are valid and that the issuers trace back
631 # to trusted roots (performed by xmlsec1)
632 # . The XML matches the credential schema
633 # . That the issuer of the credential is the authority in the target's urn
634 # . In the case of a delegated credential, this must be true of the root
635 # . That all of the gids presented in the credential are valid
636 # . The credential is not expired
638 # -- For Delegates (credentials with parents)
639 # . The privileges must be a subset of the parent credentials
640 # . The privileges must have "can_delegate" set for each delegated privilege
641 # . The target gid must be the same between child and parents
642 # . The expiry time on the child must be no later than the parent
643 # . The signer of the child must be the owner of the parent
645 # -- Verify does *NOT*
646 # . ensure that an xmlrpc client's gid matches a credential gid, that
647 # must be done elsewhere
649 # @param trusted_certs: The certificates of trusted CA certificates
650 def verify(self, trusted_certs):
654 # trusted_cert_objects = [GID(filename=f) for f in trusted_certs]
655 trusted_cert_objects = []
656 ok_trusted_certs = []
657 for f in trusted_certs:
659 # Failures here include unreadable files
661 trusted_cert_objects.append(GID(filename=f))
662 ok_trusted_certs.append(f)
663 except Exception, exc:
664 logger.error("Failed to load trusted cert from %s: %r", f, exc)
665 trusted_certs = ok_trusted_certs
667 # Use legacy verification if this is a legacy credential
669 self.legacy.verify_chain(trusted_cert_objects)
670 if self.legacy.client_gid:
671 self.legacy.client_gid.verify_chain(trusted_cert_objects)
672 if self.legacy.object_gid:
673 self.legacy.object_gid.verify_chain(trusted_cert_objects)
676 # make sure it is not expired
677 if self.get_lifetime() < datetime.datetime.utcnow():
678 raise CredentialNotVerifiable("Credential expired at %s" % self.expiration.isoformat())
680 # Verify the signatures
681 filename = self.save_to_random_tmp_file()
682 cert_args = " ".join(['--trusted-pem %s' % x for x in trusted_certs])
684 # Verify the gids of this cred and of its parents
685 for cur_cred in self.get_credential_list():
686 cur_cred.get_gid_object().verify_chain(trusted_cert_objects)
687 cur_cred.get_gid_caller().verify_chain(trusted_cert_objects)
690 refs.append("Sig_%s" % self.get_refid())
692 parentRefs = self.updateRefID()
693 for ref in parentRefs:
694 refs.append("Sig_%s" % ref)
697 verified = os.popen('%s --verify --node-id "%s" %s %s 2>&1' \
698 % (self.xmlsec_path, ref, cert_args, filename)).read()
699 if not verified.strip().startswith("OK"):
700 raise CredentialNotVerifiable("xmlsec1 error verifying cert: " + verified)
703 # Verify the parents (delegation)
705 self.verify_parent(self.parent)
707 # Make sure the issuer is the target's authority
712 # Creates a list of the credential and its parents, with the root
713 # (original delegated credential) as the last item in the list
714 def get_credential_list(self):
718 list.append(cur_cred)
720 cur_cred = cur_cred.parent
726 # Make sure the credential's target gid was signed by (or is the same) the entity that signed
727 # the original credential or an authority over that namespace.
728 def verify_issuer(self):
729 root_cred = self.get_credential_list()[-1]
730 root_target_gid = root_cred.get_gid_object()
731 root_cred_signer = root_cred.get_signature().get_issuer_gid()
733 if root_target_gid.is_signed_by_cert(root_cred_signer):
734 # cred signer matches target signer, return success
737 root_target_gid_str = root_target_gid.save_to_string()
738 root_cred_signer_str = root_cred_signer.save_to_string()
739 if root_target_gid_str == root_cred_signer_str:
740 # cred signer is target, return success
743 # See if it the signer is an authority over the domain of the target
744 # Maybe should be (hrn, type) = urn_to_hrn(root_cred_signer.get_urn())
745 root_cred_signer_type = root_cred_signer.get_type()
746 if (root_cred_signer_type == 'authority'):
747 #logger.debug('Cred signer is an authority')
748 # signer is an authority, see if target is in authority's domain
749 hrn = root_cred_signer.get_hrn()
750 if root_target_gid.get_hrn().startswith(hrn):
753 # We've required that the credential be signed by an authority
754 # for that domain. Reasonable and probably correct.
755 # A looser model would also allow the signer to be an authority
756 # in my control framework - eg My CA or CH. Even if it is not
757 # the CH that issued these, eg, user credentials.
759 # Give up, credential does not pass issuer verification
761 raise CredentialNotVerifiable("Could not verify credential owned by %s for object %s. Cred signer %s not the trusted authority for Cred target %s" % (self.gidCaller.get_urn(), self.gidObject.get_urn(), root_cred_signer.get_hrn(), root_target_gid.get_hrn()))
765 # -- For Delegates (credentials with parents) verify that:
766 # . The privileges must be a subset of the parent credentials
767 # . The privileges must have "can_delegate" set for each delegated privilege
768 # . The target gid must be the same between child and parents
769 # . The expiry time on the child must be no later than the parent
770 # . The signer of the child must be the owner of the parent
771 def verify_parent(self, parent_cred):
772 # make sure the rights given to the child are a subset of the
773 # parents rights (and check delegate bits)
774 if not parent_cred.get_privileges().is_superset(self.get_privileges()):
775 raise ChildRightsNotSubsetOfParent(
776 self.parent.get_privileges().save_to_string() + " " +
777 self.get_privileges().save_to_string())
779 # make sure my target gid is the same as the parent's
780 if not parent_cred.get_gid_object().save_to_string() == \
781 self.get_gid_object().save_to_string():
782 raise CredentialNotVerifiable("Target gid not equal between parent and child")
784 # make sure my expiry time is <= my parent's
785 if not parent_cred.get_lifetime() >= self.get_lifetime():
786 raise CredentialNotVerifiable("Delegated credential expires after parent")
788 # make sure my signer is the parent's caller
789 if not parent_cred.get_gid_caller().save_to_string(False) == \
790 self.get_signature().get_issuer_gid().save_to_string(False):
791 raise CredentialNotVerifiable("Delegated credential not signed by parent caller")
794 if parent_cred.parent:
795 parent_cred.verify_parent(parent_cred.parent)
798 def delegate(self, delegee_gidfile, caller_keyfile, caller_gidfile):
800 Return a delegated copy of this credential, delegated to the
801 specified gid's user.
803 # get the gid of the object we are delegating
804 object_gid = self.get_gid_object()
805 object_hrn = object_gid.get_hrn()
807 # the hrn of the user who will be delegated to
808 delegee_gid = GID(filename=delegee_gidfile)
809 delegee_hrn = delegee_gid.get_hrn()
811 #user_key = Keypair(filename=keyfile)
812 #user_hrn = self.get_gid_caller().get_hrn()
813 subject_string = "%s delegated to %s" % (object_hrn, delegee_hrn)
814 dcred = Credential(subject=subject_string)
815 dcred.set_gid_caller(delegee_gid)
816 dcred.set_gid_object(object_gid)
817 dcred.set_parent(self)
818 dcred.set_lifetime(self.get_lifetime())
819 dcred.set_privileges(self.get_privileges())
820 dcred.get_privileges().delegate_all_privileges(True)
821 #dcred.set_issuer_keys(keyfile, delegee_gidfile)
822 dcred.set_issuer_keys(caller_keyfile, caller_gidfile)
828 # Dump the contents of a credential to stdout in human-readable format
830 # @param dump_parents If true, also dump the parent certificates
832 def dump(self, dump_parents=False):
833 print "CREDENTIAL", self.get_subject()
835 print " privs:", self.get_privileges().save_to_string()
838 gidCaller = self.get_gid_caller()
840 gidCaller.dump(8, dump_parents)
843 gidObject = self.get_gid_object()
845 gidObject.dump(8, dump_parents)
848 if self.parent and dump_parents:
850 self.parent.dump_parents()