2 # Implements SFA Credentials
4 # Credentials are signed XML files that assign a subject gid privileges to an object gid
12 from random import randint
13 from xml.dom.minidom import Document, parseString
15 from sfa.trust.credential_legacy import CredentialLegacy
16 from sfa.trust.rights import *
17 from sfa.trust.gid import *
18 from sfa.util.faults import *
20 from sfa.util.sfalogging import logger
24 # Two years, in minutes
25 DEFAULT_CREDENTIAL_LIFETIME = 1051200
29 # . make privs match between PG and PL
30 # . Need to add support for other types of credentials, e.g. tickets
34 signature_template = \
36 <Signature xml:id="Sig_%s" xmlns="http://www.w3.org/2000/09/xmldsig#">
38 <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
39 <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
42 <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
44 <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
45 <DigestValue></DigestValue>
61 # Convert a string into a bool
64 if str.lower() in ['yes','true','1']:
71 # Utility function to get the text of an XML element
73 def getTextNode(element, subele):
74 sub = element.getElementsByTagName(subele)[0]
75 if len(sub.childNodes) > 0:
76 return sub.childNodes[0].nodeValue
81 # Utility function to set the text of an XML element
82 # It creates the element, adds the text to it,
83 # and then appends it to the parent.
85 def append_sub(doc, parent, element, text):
86 ele = doc.createElement(element)
87 ele.appendChild(doc.createTextNode(text))
88 parent.appendChild(ele)
91 # Signature contains information about an xmlsec1 signature
92 # for a signed-credential
95 class Signature(object):
98 def __init__(self, string=None):
100 self.issuer_gid = None
118 def set_refid(self, id):
121 def get_issuer_gid(self):
126 def set_issuer_gid(self, gid):
130 doc = parseString(self.xml)
131 sig = doc.getElementsByTagName("Signature")[0]
132 self.set_refid(sig.getAttribute("xml:id").strip("Sig_"))
133 keyinfo = sig.getElementsByTagName("X509Data")[0]
134 szgid = getTextNode(keyinfo, "X509Certificate")
135 szgid = "-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----" % szgid
136 self.set_issuer_gid(GID(string=szgid))
139 self.xml = signature_template % (self.get_refid(), self.get_refid())
143 # A credential provides a caller gid with privileges to an object gid.
144 # A signed credential is signed by the object's authority.
146 # Credentials are encoded in one of two ways. The legacy style places
147 # it in the subjectAltName of an X509 certificate. The new credentials
148 # are placed in signed XML.
151 # In general, a signed credential obtained externally should
152 # not be changed else the signature is no longer valid. So, once
153 # you have loaded an existing signed credential, do not call encode() or sign() on it.
156 class Credential(object):
160 # Create a Credential object
162 # @param create If true, create a blank x509 certificate
163 # @param subject If subject!=None, create an x509 cert with the subject name
164 # @param string If string!=None, load the credential from the string
165 # @param filename If filename!=None, load the credential from the file
167 def __init__(self, create=False, subject=None, string=None, filename=None):
168 self.gidCaller = None
169 self.gidObject = None
170 self.expiration = None
171 self.privileges = None
172 self.issuer_privkey = None
173 self.issuer_gid = None
174 self.issuer_pubkey = None
176 self.signature = None
182 # Check if this is a legacy credential, translate it if so
183 if string or filename:
187 str = file(filename).read()
189 if str.strip().startswith("-----"):
190 self.legacy = CredentialLegacy(False,string=str)
191 self.translate_legacy(str)
197 def get_signature(self):
198 if not self.signature:
200 return self.signature
202 def set_signature(self, sig):
207 # Translate a legacy credential into a new one
209 # @param String of the legacy credential
211 def translate_legacy(self, str):
212 legacy = CredentialLegacy(False,string=str)
213 self.gidCaller = legacy.get_gid_caller()
214 self.gidObject = legacy.get_gid_object()
215 lifetime = legacy.get_lifetime()
217 # Default to two years
218 self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME)
220 self.set_lifetime(int(lifetime))
221 self.lifeTime = legacy.get_lifetime()
222 self.set_privileges(legacy.get_privileges())
223 self.get_privileges().delegate_all_privileges(legacy.get_delegate())
226 # Need the issuer's private key and name
227 # @param key Keypair object containing the private key of the issuer
228 # @param gid GID of the issuing authority
230 def set_issuer_keys(self, privkey, gid):
231 self.issuer_privkey = privkey
232 self.issuer_gid = gid
236 # Set this credential's parent
237 def set_parent(self, cred):
242 # set the GID of the caller
244 # @param gid GID object of the caller
246 def set_gid_caller(self, gid):
248 # gid origin caller is the caller's gid by default
249 self.gidOriginCaller = gid
252 # get the GID of the object
254 def get_gid_caller(self):
255 if not self.gidCaller:
257 return self.gidCaller
260 # set the GID of the object
262 # @param gid GID object of the object
264 def set_gid_object(self, gid):
268 # get the GID of the object
270 def get_gid_object(self):
271 if not self.gidObject:
273 return self.gidObject
276 # set the lifetime of this credential
278 # @param lifetime lifetime of credential
279 # . if lifeTime is a datetime object, it is used for the expiration time
280 # . if lifeTime is an integer value, it is considered the number of minutes
281 # remaining before expiration
283 def set_lifetime(self, lifeTime):
284 if isinstance(lifeTime, int):
285 self.expiration = datetime.timedelta(seconds=lifeTime*60) + datetime.datetime.utcnow()
287 self.expiration = lifeTime
290 # get the lifetime of the credential (in minutes)
292 def get_lifetime(self):
293 if not self.expiration:
295 return self.expiration
301 # @param privs either a comma-separated list of privileges of a RightList object
303 def set_privileges(self, privs):
304 if isinstance(privs, str):
305 self.privileges = RightList(string = privs)
307 self.privileges = privs
311 # return the privileges as a RightList object
313 def get_privileges(self):
314 if not self.privileges:
316 return self.privileges
319 # determine whether the credential allows a particular operation to be
322 # @param op_name string specifying name of operation ("lookup", "update", etc)
324 def can_perform(self, op_name):
325 rights = self.get_privileges()
330 return rights.can_perform(op_name)
334 # Encode the attributes of the credential into an XML string
335 # This should be done immediately before signing the credential.
337 # In general, a signed credential obtained externally should
338 # not be changed else the signature is no longer valid. So, once
339 # you have loaded an existing signed credential, do not call encode() or sign() on it.
342 # Create the XML document
344 signed_cred = doc.createElement("signed-credential")
345 doc.appendChild(signed_cred)
347 # Fill in the <credential> bit
348 cred = doc.createElement("credential")
349 cred.setAttribute("xml:id", self.get_refid())
350 signed_cred.appendChild(cred)
351 append_sub(doc, cred, "type", "privilege")
352 append_sub(doc, cred, "serial", "8")
353 append_sub(doc, cred, "owner_gid", self.gidCaller.save_to_string())
354 append_sub(doc, cred, "owner_urn", self.gidCaller.get_urn())
355 append_sub(doc, cred, "target_gid", self.gidObject.save_to_string())
356 append_sub(doc, cred, "target_urn", self.gidObject.get_urn())
357 append_sub(doc, cred, "uuid", "")
358 if not self.expiration:
359 self.set_lifetime(3600)
360 self.expiration = self.expiration.replace(microsecond=0)
361 append_sub(doc, cred, "expires", self.expiration.isoformat())
362 privileges = doc.createElement("privileges")
363 cred.appendChild(privileges)
366 rights = self.get_privileges()
367 for right in rights.rights:
368 priv = doc.createElement("privilege")
369 append_sub(doc, priv, "name", right.kind)
370 append_sub(doc, priv, "can_delegate", str(right.delegate).lower())
371 privileges.appendChild(priv)
373 # Add the parent credential if it exists
375 sdoc = parseString(self.parent.get_xml())
376 p_cred = doc.importNode(sdoc.getElementsByTagName("credential")[0], True)
377 p = doc.createElement("parent")
378 p.appendChild(p_cred)
382 # Create the <signatures> tag
383 signatures = doc.createElement("signatures")
384 signed_cred.appendChild(signatures)
386 # Add any parent signatures
388 cur_cred = self.parent
390 sdoc = parseString(cur_cred.get_signature().get_xml())
391 ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
392 signatures.appendChild(ele)
395 cur_cred = cur_cred.parent
399 # Get the finished product
400 self.xml = doc.toxml()
403 def save_to_random_tmp_file(self):
404 filename = "/tmp/cred_%d" % randint(0,999999999)
405 self.save_to_file(filename)
408 def save_to_file(self, filename, save_parents=True):
411 f = open(filename, "w")
415 def save_to_string(self, save_parents=True):
425 def set_refid(self, rid):
429 # Figure out what refids exist, and update this credential's id
430 # so that it doesn't clobber the others. Returns the refids of
433 def updateRefID(self):
435 self.set_refid('ref0')
440 next_cred = self.parent
442 refs.append(next_cred.get_refid())
444 next_cred = next_cred.parent
449 # Find a unique refid for this credential
450 rid = self.get_refid()
453 rid = "ref%d" % (val + 1)
458 # Return the set of parent credential ref ids
467 # Sign the XML file created by encode()
470 # In general, a signed credential obtained externally should
471 # not be changed else the signature is no longer valid. So, once
472 # you have loaded an existing signed credential, do not call encode() or sign() on it.
475 if not self.issuer_privkey or not self.issuer_gid:
477 doc = parseString(self.get_xml())
478 sigs = doc.getElementsByTagName("signatures")[0]
480 # Create the signature template to be signed
481 signature = Signature()
482 signature.set_refid(self.get_refid())
483 sdoc = parseString(signature.get_xml())
484 sig_ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
485 sigs.appendChild(sig_ele)
487 self.xml = doc.toxml()
490 # Split the issuer GID into multiple certificates if it's a chain
491 chain = GID(filename=self.issuer_gid)
494 gid_files.append(chain.save_to_random_tmp_file(False))
495 if chain.get_parent():
496 chain = chain.get_parent()
501 # Call out to xmlsec1 to sign it
502 ref = 'Sig_%s' % self.get_refid()
503 filename = self.save_to_random_tmp_file()
504 signed = os.popen('/usr/bin/xmlsec1 --sign --node-id "%s" --privkey-pem %s,%s %s' \
505 % (ref, self.issuer_privkey, ",".join(gid_files), filename)).read()
508 for gid_file in gid_files:
513 # This is no longer a legacy credential
524 # Retrieve the attributes of the credential from the XML.
525 # This is automatically called by the various get_* methods of
526 # this class and should not need to be called explicitly.
531 doc = parseString(self.xml)
533 signed_cred = doc.getElementsByTagName("signed-credential")
535 # Is this a signed-cred or just a cred?
536 if len(signed_cred) > 0:
537 cred = signed_cred[0].getElementsByTagName("credential")[0]
538 signatures = signed_cred[0].getElementsByTagName("signatures")
539 if len(signatures) > 0:
540 sigs = signatures[0].getElementsByTagName("Signature")
542 cred = doc.getElementsByTagName("credential")[0]
546 self.set_refid(cred.getAttribute("xml:id"))
547 sz_expires = getTextNode(cred, "expires")
549 self.expiration = datetime.datetime.strptime(sz_expires, '%Y-%m-%dT%H:%M:%S')
550 self.lifeTime = getTextNode(cred, "expires")
551 self.gidCaller = GID(string=getTextNode(cred, "owner_gid"))
552 self.gidObject = GID(string=getTextNode(cred, "target_gid"))
556 privs = cred.getElementsByTagName("privileges")[0]
558 for priv in privs.getElementsByTagName("privilege"):
559 kind = getTextNode(priv, "name")
560 deleg = str2bool(getTextNode(priv, "can_delegate"))
562 # Convert * into the default privileges for the credential's type
563 _ , type = urn_to_hrn(self.gidObject.get_urn())
564 rl = rlist.determine_rights(type, self.gidObject.get_urn())
568 rlist.add(Right(kind.strip(), deleg))
569 self.set_privileges(rlist)
573 parent = cred.getElementsByTagName("parent")
575 parent_doc = parent[0].getElementsByTagName("credential")[0]
576 parent_xml = parent_doc.toxml()
577 self.parent = Credential(string=parent_xml)
580 # Assign the signatures to the credentials
582 Sig = Signature(string=sig.toxml())
586 if cur_cred.get_refid() == Sig.get_refid():
587 cur_cred.set_signature(Sig)
590 cur_cred = cur_cred.parent
597 # . All of the signatures are valid and that the issuers trace back
598 # to trusted roots (performed by xmlsec1)
599 # . The XML matches the credential schema
600 # . That the issuer of the credential is the authority in the target's urn
601 # . In the case of a delegated credential, this must be true of the root
602 # . That all of the gids presented in the credential are valid
604 # -- For Delegates (credentials with parents)
605 # . The privileges must be a subset of the parent credentials
606 # . The privileges must have "can_delegate" set for each delegated privilege
607 # . The target gid must be the same between child and parents
608 # . The expiry time on the child must be no later than the parent
609 # . The signer of the child must be the owner of the parent
611 # -- Verify does *NOT*
612 # . ensure that an xmlrpc client's gid matches a credential gid, that
613 # must be done elsewhere
615 # @param trusted_certs: The certificates of trusted CA certificates
617 def verify(self, trusted_certs):
621 trusted_cert_objects = [GID(filename=f) for f in trusted_certs]
623 # Use legacy verification if this is a legacy credential
625 self.legacy.verify_chain(trusted_cert_objects)
626 if self.legacy.client_gid:
627 self.legacy.client_gid.verify_chain(trusted_cert_objects)
628 if self.legacy.object_gid:
629 self.legacy.object_gid.verify_chain(trusted_cert_objects)
632 # Verify the signatures
633 filename = self.save_to_random_tmp_file()
634 cert_args = " ".join(['--trusted-pem %s' % x for x in trusted_certs])
636 # Verify the gids of this cred and of its parents
640 cur_cred.get_gid_object().verify_chain(trusted_cert_objects)
641 cur_cred.get_gid_caller().verify_chain(trusted_cert_objects)
643 cur_cred = cur_cred.parent
648 refs.append("Sig_%s" % self.get_refid())
650 parentRefs = self.updateRefID()
651 for ref in parentRefs:
652 refs.append("Sig_%s" % ref)
655 verified = os.popen('/usr/bin/xmlsec1 --verify --node-id "%s" %s %s 2>&1' \
656 % (ref, cert_args, filename)).read()
657 if not verified.strip().startswith("OK"):
658 raise CredentialNotVerifiable("xmlsec1 error: " + verified)
661 # Verify the parents (delegation)
663 self.verify_parent(self.parent)
664 # Make sure the issuer is the target's authority
670 # Make sure the issuer of this credential is the target's authority
671 def verify_issuer(self):
672 target_authority = get_authority(self.get_gid_object().get_urn())
675 # Find the root credential's signature
679 cur_cred = cur_cred.parent
681 root_issuer = cur_cred.get_signature().get_issuer_gid().get_urn()
684 # Ensure that the signer of the root credential is the target_authority
685 target_authority = hrn_to_urn(target_authority, 'authority')
687 logger.info( "%s %s" % (root_issuer, target_authority))
689 if root_issuer != target_authority:
690 raise CredentialNotVerifiable("issuer (%s) != authority of target (%s)" \
691 % (root_issuer, target_authority))
694 # -- For Delegates (credentials with parents) verify that:
695 # . The privileges must be a subset of the parent credentials
696 # . The privileges must have "can_delegate" set for each delegated privilege
697 # . The target gid must be the same between child and parents
698 # . The expiry time on the child must be no later than the parent
699 # . The signer of the child must be the owner of the parent
701 def verify_parent(self, parent_cred):
702 # make sure the rights given to the child are a subset of the
703 # parents rights (and check delegate bits)
704 if not parent_cred.get_privileges().is_superset(self.get_privileges()):
705 raise ChildRightsNotSubsetOfParent(
706 self.parent.get_privileges().save_to_string() + " " +
707 self.get_privileges().save_to_string())
709 # make sure my target gid is the same as the parent's
710 if not parent_cred.get_gid_object().save_to_string() == \
711 self.get_gid_object().save_to_string():
712 raise CredentialNotVerifiable("target gid not equal between parent and child")
714 # make sure my expiry time is <= my parent's
715 if not parent_cred.get_lifetime() >= self.get_lifetime():
716 raise CredentialNotVerifiable("delegated credential expires after parent")
718 # make sure my signer is the parent's caller
719 if not parent_cred.get_gid_caller().save_to_string(False) == \
720 self.get_signature().get_issuer_gid().save_to_string(False):
721 raise CredentialNotVerifiable("delegated credential not signed by parent caller")
723 if parent_cred.parent:
724 parent_cred.verify_parent(parent_cred.parent)
727 # Dump the contents of a credential to stdout in human-readable format
729 # @param dump_parents If true, also dump the parent certificates
731 def dump(self, dump_parents=False):
732 print "CREDENTIAL", self.get_subject()
734 print " privs:", self.get_privileges().save_to_string()
737 gidCaller = self.get_gid_caller()
739 gidCaller.dump(8, dump_parents)
742 gidObject = self.get_gid_object()
744 gidObject.dump(8, dump_parents)
747 if self.parent and dump_parents:
749 self.parent.dump_parents()