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
180 self.xmlsec_path = '/usr/bin/env xmlsec1'
183 # Check if this is a legacy credential, translate it if so
184 if string or filename:
188 str = file(filename).read()
190 if str.strip().startswith("-----"):
191 self.legacy = CredentialLegacy(False,string=str)
192 self.translate_legacy(str)
198 def get_signature(self):
199 if not self.signature:
201 return self.signature
203 def set_signature(self, sig):
208 # Translate a legacy credential into a new one
210 # @param String of the legacy credential
212 def translate_legacy(self, str):
213 legacy = CredentialLegacy(False,string=str)
214 self.gidCaller = legacy.get_gid_caller()
215 self.gidObject = legacy.get_gid_object()
216 lifetime = legacy.get_lifetime()
218 # Default to two years
219 self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME)
221 self.set_lifetime(int(lifetime))
222 self.lifeTime = legacy.get_lifetime()
223 self.set_privileges(legacy.get_privileges())
224 self.get_privileges().delegate_all_privileges(legacy.get_delegate())
227 # Need the issuer's private key and name
228 # @param key Keypair object containing the private key of the issuer
229 # @param gid GID of the issuing authority
231 def set_issuer_keys(self, privkey, gid):
232 self.issuer_privkey = privkey
233 self.issuer_gid = gid
237 # Set this credential's parent
238 def set_parent(self, cred):
243 # set the GID of the caller
245 # @param gid GID object of the caller
247 def set_gid_caller(self, gid):
249 # gid origin caller is the caller's gid by default
250 self.gidOriginCaller = gid
253 # get the GID of the object
255 def get_gid_caller(self):
256 if not self.gidCaller:
258 return self.gidCaller
261 # set the GID of the object
263 # @param gid GID object of the object
265 def set_gid_object(self, gid):
269 # get the GID of the object
271 def get_gid_object(self):
272 if not self.gidObject:
274 return self.gidObject
277 # set the lifetime of this credential
279 # @param lifetime lifetime of credential
280 # . if lifeTime is a datetime object, it is used for the expiration time
281 # . if lifeTime is an integer value, it is considered the number of minutes
282 # remaining before expiration
284 def set_lifetime(self, lifeTime):
285 if isinstance(lifeTime, int):
286 self.expiration = datetime.timedelta(seconds=lifeTime*60) + datetime.datetime.utcnow()
288 self.expiration = lifeTime
291 # get the lifetime of the credential (in minutes)
293 def get_lifetime(self):
294 if not self.expiration:
296 return self.expiration
302 # @param privs either a comma-separated list of privileges of a RightList object
304 def set_privileges(self, privs):
305 if isinstance(privs, str):
306 self.privileges = RightList(string = privs)
308 self.privileges = privs
312 # return the privileges as a RightList object
314 def get_privileges(self):
315 if not self.privileges:
317 return self.privileges
320 # determine whether the credential allows a particular operation to be
323 # @param op_name string specifying name of operation ("lookup", "update", etc)
325 def can_perform(self, op_name):
326 rights = self.get_privileges()
331 return rights.can_perform(op_name)
335 # Encode the attributes of the credential into an XML string
336 # This should be done immediately before signing the credential.
338 # In general, a signed credential obtained externally should
339 # not be changed else the signature is no longer valid. So, once
340 # 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):
406 filename = "/tmp/cred_%d" % randint(0,999999999)
407 if not os.path.isfile(filename):
410 self.save_to_file(filename)
413 def save_to_file(self, filename, save_parents=True):
416 f = open(filename, "w")
420 def save_to_string(self, save_parents=True):
430 def set_refid(self, rid):
434 # Figure out what refids exist, and update this credential's id
435 # so that it doesn't clobber the others. Returns the refids of
438 def updateRefID(self):
440 self.set_refid('ref0')
445 next_cred = self.parent
447 refs.append(next_cred.get_refid())
449 next_cred = next_cred.parent
454 # Find a unique refid for this credential
455 rid = self.get_refid()
458 rid = "ref%d" % (val + 1)
463 # Return the set of parent credential ref ids
472 # Sign the XML file created by encode()
475 # In general, a signed credential obtained externally should
476 # not be changed else the signature is no longer valid. So, once
477 # you have loaded an existing signed credential, do not call encode() or sign() on it.
480 if not self.issuer_privkey or not self.issuer_gid:
482 doc = parseString(self.get_xml())
483 sigs = doc.getElementsByTagName("signatures")[0]
485 # Create the signature template to be signed
486 signature = Signature()
487 signature.set_refid(self.get_refid())
488 sdoc = parseString(signature.get_xml())
489 sig_ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True)
490 sigs.appendChild(sig_ele)
492 self.xml = doc.toxml()
495 # Split the issuer GID into multiple certificates if it's a chain
496 chain = GID(filename=self.issuer_gid)
499 gid_files.append(chain.save_to_random_tmp_file(False))
500 if chain.get_parent():
501 chain = chain.get_parent()
506 # Call out to xmlsec1 to sign it
507 ref = 'Sig_%s' % self.get_refid()
508 filename = self.save_to_random_tmp_file()
509 signed = os.popen('%s --sign --node-id "%s" --privkey-pem %s,%s %s' \
510 % (self.xmlsec_path, ref, self.issuer_privkey, ",".join(gid_files), filename)).read()
513 for gid_file in gid_files:
518 # This is no longer a legacy credential
529 # Retrieve the attributes of the credential from the XML.
530 # This is automatically called by the various get_* methods of
531 # this class and should not need to be called explicitly.
536 doc = parseString(self.xml)
538 signed_cred = doc.getElementsByTagName("signed-credential")
540 # Is this a signed-cred or just a cred?
541 if len(signed_cred) > 0:
542 cred = signed_cred[0].getElementsByTagName("credential")[0]
543 signatures = signed_cred[0].getElementsByTagName("signatures")
544 if len(signatures) > 0:
545 sigs = signatures[0].getElementsByTagName("Signature")
547 cred = doc.getElementsByTagName("credential")[0]
551 self.set_refid(cred.getAttribute("xml:id"))
552 sz_expires = getTextNode(cred, "expires")
554 self.expiration = datetime.datetime.strptime(sz_expires, '%Y-%m-%dT%H:%M:%S')
555 self.lifeTime = getTextNode(cred, "expires")
556 self.gidCaller = GID(string=getTextNode(cred, "owner_gid"))
557 self.gidObject = GID(string=getTextNode(cred, "target_gid"))
561 privs = cred.getElementsByTagName("privileges")[0]
563 for priv in privs.getElementsByTagName("privilege"):
564 kind = getTextNode(priv, "name")
565 deleg = str2bool(getTextNode(priv, "can_delegate"))
567 # Convert * into the default privileges for the credential's type
568 _ , type = urn_to_hrn(self.gidObject.get_urn())
569 rl = rlist.determine_rights(type, self.gidObject.get_urn())
573 rlist.add(Right(kind.strip(), deleg))
574 self.set_privileges(rlist)
578 parent = cred.getElementsByTagName("parent")
580 parent_doc = parent[0].getElementsByTagName("credential")[0]
581 parent_xml = parent_doc.toxml()
582 self.parent = Credential(string=parent_xml)
585 # Assign the signatures to the credentials
587 Sig = Signature(string=sig.toxml())
591 if cur_cred.get_refid() == Sig.get_refid():
592 cur_cred.set_signature(Sig)
595 cur_cred = cur_cred.parent
602 # . All of the signatures are valid and that the issuers trace back
603 # to trusted roots (performed by xmlsec1)
604 # . The XML matches the credential schema
605 # . That the issuer of the credential is the authority in the target's urn
606 # . In the case of a delegated credential, this must be true of the root
607 # . That all of the gids presented in the credential are valid
609 # -- For Delegates (credentials with parents)
610 # . The privileges must be a subset of the parent credentials
611 # . The privileges must have "can_delegate" set for each delegated privilege
612 # . The target gid must be the same between child and parents
613 # . The expiry time on the child must be no later than the parent
614 # . The signer of the child must be the owner of the parent
616 # -- Verify does *NOT*
617 # . ensure that an xmlrpc client's gid matches a credential gid, that
618 # must be done elsewhere
620 # @param trusted_certs: The certificates of trusted CA certificates
622 def verify(self, trusted_certs):
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('%s --verify --node-id "%s" %s %s 2>&1' \
661 % (self.xmlsec_path, ref, cert_args, filename)).read()
662 if not verified.strip().startswith("OK"):
663 raise CredentialNotVerifiable("xmlsec1 error: " + verified)
666 # Verify the parents (delegation)
668 self.verify_parent(self.parent)
669 # Make sure the issuer is the target's authority
675 # Make sure the issuer of this credential is the target's authority
676 def verify_issuer(self):
677 target_authority = get_authority(self.get_gid_object().get_urn())
680 # Find the root credential's signature
684 cur_cred = cur_cred.parent
686 root_issuer = cur_cred.get_signature().get_issuer_gid().get_urn()
689 # Ensure that the signer of the root credential is the target_authority
690 target_authority = hrn_to_urn(target_authority, 'authority')
692 if root_issuer != target_authority:
693 raise CredentialNotVerifiable("issuer (%s) != authority of target (%s)" \
694 % (root_issuer, target_authority))
697 # -- For Delegates (credentials with parents) verify that:
698 # . The privileges must be a subset of the parent credentials
699 # . The privileges must have "can_delegate" set for each delegated privilege
700 # . The target gid must be the same between child and parents
701 # . The expiry time on the child must be no later than the parent
702 # . The signer of the child must be the owner of the parent
704 def verify_parent(self, parent_cred):
705 # make sure the rights given to the child are a subset of the
706 # parents rights (and check delegate bits)
707 if not parent_cred.get_privileges().is_superset(self.get_privileges()):
708 raise ChildRightsNotSubsetOfParent(
709 self.parent.get_privileges().save_to_string() + " " +
710 self.get_privileges().save_to_string())
712 # make sure my target gid is the same as the parent's
713 if not parent_cred.get_gid_object().save_to_string() == \
714 self.get_gid_object().save_to_string():
715 raise CredentialNotVerifiable("target gid not equal between parent and child")
717 # make sure my expiry time is <= my parent's
718 if not parent_cred.get_lifetime() >= self.get_lifetime():
719 raise CredentialNotVerifiable("delegated credential expires after parent")
721 # make sure my signer is the parent's caller
722 if not parent_cred.get_gid_caller().save_to_string(False) == \
723 self.get_signature().get_issuer_gid().save_to_string(False):
724 raise CredentialNotVerifiable("delegated credential not signed by parent caller")
726 if parent_cred.parent:
727 parent_cred.verify_parent(parent_cred.parent)
730 # Dump the contents of a credential to stdout in human-readable format
732 # @param dump_parents If true, also dump the parent certificates
734 def dump(self, dump_parents=False):
735 print "CREDENTIAL", self.get_subject()
737 print " privs:", self.get_privileges().save_to_string()
740 gidCaller = self.get_gid_caller()
742 gidCaller.dump(8, dump_parents)
745 gidObject = self.get_gid_object()
747 gidObject.dump(8, dump_parents)
750 if self.parent and dump_parents:
752 self.parent.dump_parents()