2 # Implements SFA Credentials
4 # Credentials are signed XML files that assign a subject gid privileges to an object gid
13 from random import randint
14 from xml.dom.minidom import Document, parseString
15 from lxml import etree
17 from sfa.trust.credential_legacy import CredentialLegacy
18 from sfa.trust.certificate import Certificate
19 from sfa.trust.rights import *
20 from sfa.trust.gid import *
21 from sfa.util.faults import *
22 from sfa.util.sfalogging import logger
26 # Two years, in minutes
27 DEFAULT_CREDENTIAL_LIFETIME = 1051200
31 # . make privs match between PG and PL
32 # . Need to add support for other types of credentials, e.g. tickets
36 signature_template = \
38 <Signature xml:id="Sig_%s" xmlns="http://www.w3.org/2000/09/xmldsig#">
40 <CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
41 <SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#rsa-sha1"/>
44 <Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature" />
46 <DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
47 <DigestValue></DigestValue>
63 # Convert a string into a bool
66 if str.lower() in ['yes','true','1']:
73 # Utility function to get the text of an XML element
75 def getTextNode(element, subele):
76 sub = element.getElementsByTagName(subele)[0]
77 if len(sub.childNodes) > 0:
78 return sub.childNodes[0].nodeValue
83 # Utility function to set the text of an XML element
84 # It creates the element, adds the text to it,
85 # and then appends it to the parent.
87 def append_sub(doc, parent, element, text):
88 ele = doc.createElement(element)
89 ele.appendChild(doc.createTextNode(text))
90 parent.appendChild(ele)
93 # Signature contains information about an xmlsec1 signature
94 # for a signed-credential
97 class Signature(object):
102 def __init__(self, string=None):
119 def set_refid(self, id):
122 def get_issuer_gid(self):
127 def set_issuer_gid(self, gid):
131 doc = parseString(self.xml)
132 sig = doc.getElementsByTagName("Signature")[0]
133 self.set_refid(sig.getAttribute("xml:id").strip("Sig_"))
134 keyinfo = sig.getElementsByTagName("X509Data")[0]
135 szgid = getTextNode(keyinfo, "X509Certificate")
136 szgid = "-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----" % szgid
137 self.set_issuer_gid(GID(string=szgid))
140 self.xml = signature_template % (self.get_refid(), self.get_refid())
144 # A credential provides a caller gid with privileges to an object gid.
145 # A signed credential is signed by the object's authority.
147 # Credentials are encoded in one of two ways. The legacy style places
148 # it in the subjectAltName of an X509 certificate. The new credentials
149 # are placed in signed XML.
152 # In general, a signed credential obtained externally should
153 # not be changed else the signature is no longer valid. So, once
154 # you have loaded an existing signed credential, do not call encode() or sign() on it.
157 class Credential(object):
162 issuer_privkey = None
172 # Create a Credential object
174 # @param create If true, create a blank x509 certificate
175 # @param subject If subject!=None, create an x509 cert with the subject name
176 # @param string If string!=None, load the credential from the string
177 # @param filename If filename!=None, load the credential from the file
179 def __init__(self, create=False, subject=None, string=None, filename=None):
181 # Check if this is a legacy credential, translate it if so
182 if string or filename:
186 str = file(filename).read()
188 if str.strip().startswith("-----"):
189 self.legacy = CredentialLegacy(False,string=str)
190 self.translate_legacy(str)
196 def get_signature(self):
197 if not self.signature:
199 return self.signature
201 def set_signature(self, sig):
206 # Translate a legacy credential into a new one
208 # @param String of the legacy credential
210 def translate_legacy(self, str):
211 legacy = CredentialLegacy(False,string=str)
212 self.gidCaller = legacy.get_gid_caller()
213 self.gidObject = legacy.get_gid_object()
214 lifetime = legacy.get_lifetime()
216 # Default to two years
217 self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME)
219 self.set_lifetime(int(lifetime))
220 self.lifeTime = legacy.get_lifetime()
221 self.set_privileges(legacy.get_privileges())
222 self.get_privileges().delegate_all_privileges(legacy.get_delegate())
225 # Need the issuer's private key and name
226 # @param key Keypair object containing the private key of the issuer
227 # @param gid GID of the issuing authority
229 def set_issuer_keys(self, privkey, gid):
230 self.issuer_privkey = privkey
231 self.issuer_gid = gid
235 # Set this credential's parent
236 def set_parent(self, cred):
241 # set the GID of the caller
243 # @param gid GID object of the caller
245 def set_gid_caller(self, gid):
247 # gid origin caller is the caller's gid by default
248 self.gidOriginCaller = gid
251 # get the GID of the object
253 def get_gid_caller(self):
254 if not self.gidCaller:
256 return self.gidCaller
259 # set the GID of the object
261 # @param gid GID object of the object
263 def set_gid_object(self, gid):
267 # get the GID of the object
269 def get_gid_object(self):
270 if not self.gidObject:
272 return self.gidObject
275 # set the lifetime of this credential
277 # @param lifetime lifetime of credential
278 # . if lifeTime is a datetime object, it is used for the expiration time
279 # . if lifeTime is an integer value, it is considered the number of minutes
280 # remaining before expiration
282 def set_lifetime(self, lifeTime):
283 if isinstance(lifeTime, int):
284 self.expiration = datetime.timedelta(seconds=lifeTime*60) + datetime.datetime.utcnow()
286 self.expiration = lifeTime
289 # get the lifetime of the credential (in minutes)
291 def get_lifetime(self):
292 if not self.expiration:
294 return self.expiration
300 # @param privs either a comma-separated list of privileges of a RightList object
302 def set_privileges(self, privs):
303 if isinstance(privs, str):
304 self.privileges = RightList(string = privs)
306 self.privileges = privs
310 # return the privileges as a RightList object
312 def get_privileges(self):
313 if not self.privileges:
315 return self.privileges
318 # determine whether the credential allows a particular operation to be
321 # @param op_name string specifying name of operation ("lookup", "update", etc)
323 def can_perform(self, op_name):
324 rights = self.get_privileges()
329 return rights.can_perform(op_name)
333 # Encode the attributes of the credential into an XML string
334 # This should be done immediately before signing the credential.
336 # In general, a signed credential obtained externally should
337 # not be changed else the signature is no longer valid. So, once
338 # you have loaded an existing signed credential, do not call encode() or sign() on it.
343 # Create the XML document
345 signed_cred = doc.createElement("signed-credential")
346 doc.appendChild(signed_cred)
348 # Fill in the <credential> bit
349 cred = doc.createElement("credential")
350 cred.setAttribute("xml:id", self.get_refid())
351 signed_cred.appendChild(cred)
352 append_sub(doc, cred, "type", "privilege")
353 append_sub(doc, cred, "serial", "8")
354 append_sub(doc, cred, "owner_gid", self.gidCaller.save_to_string())
355 append_sub(doc, cred, "owner_urn", self.gidCaller.get_urn())
356 append_sub(doc, cred, "target_gid", self.gidObject.save_to_string())
357 append_sub(doc, cred, "target_urn", self.gidObject.get_urn())
358 append_sub(doc, cred, "uuid", "")
359 if not self.expiration:
360 self.set_lifetime(3600)
361 self.expiration = self.expiration.replace(microsecond=0)
362 append_sub(doc, cred, "expires", self.expiration.isoformat())
363 privileges = doc.createElement("privileges")
364 cred.appendChild(privileges)
367 rights = self.get_privileges()
368 for right in rights.rights:
369 priv = doc.createElement("privilege")
370 append_sub(doc, priv, "name", right.kind)
371 append_sub(doc, priv, "can_delegate", str(right.delegate).lower())
372 privileges.appendChild(priv)
374 # Add the parent credential if it exists
376 sdoc = parseString(self.parent.get_xml())
377 p_cred = doc.importNode(sdoc.getElementsByTagName("credential")[0], True)
378 p = doc.createElement("parent")
379 p.appendChild(p_cred)
383 # Create the <signatures> tag
384 signatures = doc.createElement("signatures")
385 signed_cred.appendChild(signatures)
387 # Add any parent signatures
389 cur_cred = self.parent
391 sdoc = parseString(cur_cred.get_signature().get_xml())
392 ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
393 signatures.appendChild(ele)
396 cur_cred = cur_cred.parent
400 # Get the finished product
401 self.xml = doc.toxml()
404 def save_to_random_tmp_file(self):
405 filename = "/tmp/cred_%d" % randint(0,999999999)
406 self.save_to_file(filename)
409 def save_to_file(self, filename, save_parents=True):
412 f = open(filename, "w")
416 def save_to_string(self, save_parents=True):
426 def set_refid(self, rid):
430 # Figure out what refids exist, and update this credential's id
431 # so that it doesn't clobber the others. Returns the refids of
434 def updateRefID(self):
436 self.set_refid('ref0')
441 next_cred = self.parent
443 refs.append(next_cred.get_refid())
445 next_cred = next_cred.parent
450 # Find a unique refid for this credential
451 rid = self.get_refid()
454 rid = "ref%d" % (val + 1)
459 # Return the set of parent credential ref ids
468 # Sign the XML file created by encode()
471 # In general, a signed credential obtained externally should
472 # not be changed else the signature is no longer valid. So, once
473 # you have loaded an existing signed credential, do not call encode() or sign() on it.
476 if not self.issuer_privkey or not self.issuer_gid:
478 doc = parseString(self.get_xml())
479 sigs = doc.getElementsByTagName("signatures")[0]
481 # Create the signature template to be signed
482 signature = Signature()
483 signature.set_refid(self.get_refid())
484 sdoc = parseString(signature.get_xml())
485 sig_ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
486 sigs.appendChild(sig_ele)
488 self.xml = doc.toxml()
491 # Split the issuer GID into multiple certificates if it's a chain
492 chain = GID(filename=self.issuer_gid)
495 gid_files.append(chain.save_to_random_tmp_file(False))
496 if chain.get_parent():
497 chain = chain.get_parent()
502 # Call out to xmlsec1 to sign it
503 ref = 'Sig_%s' % self.get_refid()
504 filename = self.save_to_random_tmp_file()
505 signed = os.popen('/usr/bin/xmlsec1 --sign --node-id "%s" --privkey-pem %s,%s %s' \
506 % (ref, self.issuer_privkey, ",".join(gid_files), filename)).read()
509 for gid_file in gid_files:
514 # This is no longer a legacy credential
525 # Retrieve the attributes of the credential from the XML.
526 # This is automatically called by the various get_* methods of
527 # this class and should not need to be called explicitly.
532 doc = parseString(self.xml)
534 signed_cred = doc.getElementsByTagName("signed-credential")
536 # Is this a signed-cred or just a cred?
537 if len(signed_cred) > 0:
538 cred = signed_cred[0].getElementsByTagName("credential")[0]
539 signatures = signed_cred[0].getElementsByTagName("signatures")
540 if len(signatures) > 0:
541 sigs = signatures[0].getElementsByTagName("Signature")
543 cred = doc.getElementsByTagName("credential")[0]
547 self.set_refid(cred.getAttribute("xml:id"))
548 sz_expires = getTextNode(cred, "expires")
550 self.expiration = datetime.datetime.strptime(sz_expires, '%Y-%m-%dT%H:%M:%S')
551 self.lifeTime = getTextNode(cred, "expires")
552 self.gidCaller = GID(string=getTextNode(cred, "owner_gid"))
553 self.gidObject = GID(string=getTextNode(cred, "target_gid"))
557 privs = cred.getElementsByTagName("privileges")[0]
559 for priv in privs.getElementsByTagName("privilege"):
560 kind = getTextNode(priv, "name")
561 deleg = str2bool(getTextNode(priv, "can_delegate"))
563 # Convert * into the default privileges for the credential's type
564 _ , type = urn_to_hrn(self.gidObject)
565 rl = rlist.determine_rights(type, urn)
566 for r in rlist.rights:
569 rlist.add(Right(kind.strip(), deleg))
570 self.set_privileges(rlist)
574 parent = cred.getElementsByTagName("parent")
576 parent_doc = parent[0].getElementsByTagName("credential")[0]
577 parent_xml = parent_doc.toxml()
578 self.parent = Credential(string=parent_xml)
581 # Assign the signatures to the credentials
583 Sig = Signature(string=sig.toxml())
587 if cur_cred.get_refid() == Sig.get_refid():
588 cur_cred.set_signature(Sig)
591 cur_cred = cur_cred.parent
598 # . All of the signatures are valid and that the issuers trace back
599 # to trusted roots (performed by xmlsec1)
600 # . The XML matches the credential schema
601 # . That the issuer of the credential is the authority in the target's urn
602 # . In the case of a delegated credential, this must be true of the root
603 # . That all of the gids presented in the credential are valid
605 # -- For Delegates (credentials with parents)
606 # . The privileges must be a subset of the parent credentials
607 # . The privileges must have "can_delegate" set for each delegated privilege
608 # . The target gid must be the same between child and parents
609 # . The expiry time on the child must be no later than the parent
610 # . The signer of the child must be the owner of the parent
612 # -- Verify does *NOT*
613 # . ensure that an xmlrpc client's gid matches a credential gid, that
614 # must be done elsewhere
616 # @param trusted_certs: The certificates of trusted CA certificates
618 def verify(self, trusted_certs):
622 # Check for schema conformance
626 trusted_cert_objects = [GID(filename=f) for f in trusted_certs]
628 # Use legacy verification if this is a legacy credential
630 self.legacy.verify_chain(trusted_cert_objects)
631 if self.legacy.client_gid:
632 self.legacy.client_gid.verify_chain(trusted_cert_objects)
633 if self.legacy.object_gid:
634 self.legacy.object_gid.verify_chain(trusted_cert_objects)
637 # Verify the signatures
638 filename = self.save_to_random_tmp_file()
639 cert_args = " ".join(['--trusted-pem %s' % x for x in trusted_certs])
641 # Verify the gids of this cred and of its parents
645 cur_cred.get_gid_object().verify_chain(trusted_cert_objects)
646 cur_cred.get_gid_caller().verify_chain(trusted_cert_objects)
648 cur_cred = cur_cred.parent
653 refs.append("Sig_%s" % self.get_refid())
655 parentRefs = self.updateRefID()
656 for ref in parentRefs:
657 refs.append("Sig_%s" % ref)
660 verified = os.popen('/usr/bin/xmlsec1 --verify --node-id "%s" %s %s 2>&1' \
661 % (ref, cert_args, filename)).read()
662 if not verified.strip().startswith("OK"):
663 raise CredentialNotVerifiable("xmlsec1 error: " + verified)
667 # Verify the parents (delegation)
669 self.verify_parent(self.parent)
671 # Make sure the issuer is the target's authority
678 # Make sure the issuer of this credential is the target's authority
679 def verify_issuer(self):
680 target_authority = get_authority(self.get_gid_object().get_urn())
682 # Find the root credential's signature
687 cur_cred = cur_cred.parent
689 root_issuer = cur_cred.get_signature().get_issuer_gid().get_urn()
693 # Ensure that the signer of the root credential is the target_authority
694 target_authority = hrn_to_urn(target_authority, 'authority')
696 if root_issuer != target_authority:
697 raise CredentialNotVerifiable("issuer (%s) != authority of target (%s)" \
698 % (root_issuer, target_authority))
701 # -- For Delegates (credentials with parents) verify that:
702 # . The privileges must be a subset of the parent credentials
703 # . The privileges must have "can_delegate" set for each delegated privilege
704 # . The target gid must be the same between child and parents
705 # . The expiry time on the child must be no later than the parent
706 # . The signer of the child must be the owner of the parent
708 def verify_parent(self, parent_cred):
709 # make sure the rights given to the child are a subset of the
710 # parents rights (and check delegate bits)
711 if not parent_cred.get_privileges().is_superset(self.get_privileges()):
712 raise ChildRightsNotSubsetOfParent(
713 self.parent.get_privileges().save_to_string() + " " +
714 self.get_privileges().save_to_string())
716 # make sure my target gid is the same as the parent's
717 if not parent_cred.get_gid_object().save_to_string() == \
718 self.get_gid_object().save_to_string():
719 raise CredentialNotVerifiable("target gid not equal between parent and child")
721 # make sure my expiry time is <= my parent's
722 if not parent_cred.get_lifetime() >= self.get_lifetime():
723 raise CredentialNotVerifiable("delegated credential expires after parent")
725 # make sure my signer is the parent's caller
726 if not parent_cred.get_gid_caller().save_to_string(False) == \
727 self.get_signature().get_issuer_gid().save_to_string(False):
728 raise CredentialNotVerifiable("delegated credential not signed by parent caller")
730 if parent_cred.parent:
731 parent_cred.verify_parent(parent_cred.parent)
734 # Dump the contents of a credential to stdout in human-readable format
736 # @param dump_parents If true, also dump the parent certificates
738 def dump(self, dump_parents=False):
739 print "CREDENTIAL", self.get_subject()
741 print " privs:", self.get_privileges().save_to_string()
744 gidCaller = self.get_gid_caller()
746 gidCaller.dump(8, dump_parents)
749 gidObject = self.get_gid_object()
751 gidObject.dump(8, dump_parents)
754 if self.parent and dump_parents:
756 self.parent.dump_parents()