X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;ds=sidebyside;f=sfa%2Ftrust%2Fcredential.py;h=f3fb180bd0b13de6efb316ae4923d736031f4dea;hb=952322d76247f8991f3c2688ed7e1f5a22ca4572;hp=d8451d74d2c6ffa3a9347ef3f8179cd9cd1c51ee;hpb=43b44e012032d6a63d38bdf98caa25988fc27933;p=sfa.git diff --git a/sfa/trust/credential.py b/sfa/trust/credential.py index d8451d74..f3fb180b 100644 --- a/sfa/trust/credential.py +++ b/sfa/trust/credential.py @@ -1,34 +1,161 @@ ## # Implements SFA Credentials # -# Credentials are layered on top of certificates, and are essentially a -# certificate that stores a tuple of parameters. +# Credentials are signed XML files that assign a subject gid privileges to an object gid ## ### $Id$ ### $URL$ -import xmlrpclib +import os +import datetime +from xml.dom.minidom import Document, parseString +from tempfile import mkstemp -from sfa.trust.certificate import Certificate +from sfa.trust.credential_legacy import CredentialLegacy from sfa.trust.rights import * from sfa.trust.gid import * from sfa.util.faults import * +from sfa.util.sfalogging import logger +from dateutil.parser import parse + + + +# Two years, in seconds +DEFAULT_CREDENTIAL_LIFETIME = 60 * 60 * 24 * 365 * 2 + + +# TODO: +# . make privs match between PG and PL +# . Need to add support for other types of credentials, e.g. tickets + + + +signature_template = \ +''' + + + + + + + + + + + + + + + + + + + + + + +''' + +## +# Convert a string into a bool + +def str2bool(str): + if str.lower() in ['yes','true','1']: + return True + return False + + + +## +# Utility function to get the text of an XML element + +def getTextNode(element, subele): + sub = element.getElementsByTagName(subele)[0] + if len(sub.childNodes) > 0: + return sub.childNodes[0].nodeValue + else: + return None + +## +# Utility function to set the text of an XML element +# It creates the element, adds the text to it, +# and then appends it to the parent. + +def append_sub(doc, parent, element, text): + ele = doc.createElement(element) + ele.appendChild(doc.createTextNode(text)) + parent.appendChild(ele) + +## +# Signature contains information about an xmlsec1 signature +# for a signed-credential +# + +class Signature(object): + + + def __init__(self, string=None): + self.refid = None + self.issuer_gid = None + self.xml = None + if string: + self.xml = string + self.decode() + + + + def get_refid(self): + if not self.refid: + self.decode() + return self.refid + + def get_xml(self): + if not self.xml: + self.encode() + return self.xml + + def set_refid(self, id): + self.refid = id + + def get_issuer_gid(self): + if not self.gid: + self.decode() + return self.gid + + def set_issuer_gid(self, gid): + self.gid = gid + + def decode(self): + doc = parseString(self.xml) + sig = doc.getElementsByTagName("Signature")[0] + self.set_refid(sig.getAttribute("xml:id").strip("Sig_")) + keyinfo = sig.getElementsByTagName("X509Data")[0] + szgid = getTextNode(keyinfo, "X509Certificate") + szgid = "-----BEGIN CERTIFICATE-----\n%s\n-----END CERTIFICATE-----" % szgid + self.set_issuer_gid(GID(string=szgid)) + + def encode(self): + self.xml = signature_template % (self.get_refid(), self.get_refid()) + + ## -# Credential is a tuple: -# (GIDCaller, GIDObject, LifeTime, Privileges, Delegate) +# A credential provides a caller gid with privileges to an object gid. +# A signed credential is signed by the object's authority. +# +# Credentials are encoded in one of two ways. The legacy style places +# it in the subjectAltName of an X509 certificate. The new credentials +# are placed in signed XML. # -# These fields are encoded using xmlrpc into the subjectAltName field of the -# x509 certificate. Note: Call encode() once the fields have been filled in -# to perform this encoding. +# WARNING: +# In general, a signed credential obtained externally should +# not be changed else the signature is no longer valid. So, once +# you have loaded an existing signed credential, do not call encode() or sign() on it. + + +class Credential(object): -class Credential(Certificate): - gidCaller = None - gidObject = None - lifeTime = None - privileges = None - delegate = False ## # Create a Credential object @@ -39,7 +166,88 @@ class Credential(Certificate): # @param filename If filename!=None, load the credential from the file def __init__(self, create=False, subject=None, string=None, filename=None): - Certificate.__init__(self, create, subject, string, filename) + self.gidCaller = None + self.gidObject = None + self.expiration = None + self.privileges = None + self.issuer_privkey = None + self.issuer_gid = None + self.issuer_pubkey = None + self.parent = None + self.signature = None + self.xml = None + self.refid = None + self.legacy = None + + + + + # Check if this is a legacy credential, translate it if so + if string or filename: + if string: + str = string + elif filename: + str = file(filename).read() + + if str.strip().startswith("-----"): + self.legacy = CredentialLegacy(False,string=str) + self.translate_legacy(str) + else: + self.xml = str + self.decode() + + # Find an xmlsec1 path + self.xmlsec_path = '' + paths = ['/usr/bin','/usr/local/bin','/bin','/opt/bin','/opt/local/bin'] + for path in paths: + if os.path.isfile(path + '/' + 'xmlsec1'): + self.xmlsec_path = path + '/' + 'xmlsec1' + break + + + def get_signature(self): + if not self.signature: + self.decode() + return self.signature + + def set_signature(self, sig): + self.signature = sig + + + ## + # Translate a legacy credential into a new one + # + # @param String of the legacy credential + + def translate_legacy(self, str): + legacy = CredentialLegacy(False,string=str) + self.gidCaller = legacy.get_gid_caller() + self.gidObject = legacy.get_gid_object() + lifetime = legacy.get_lifetime() + if not lifetime: + # Default to two years + self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME) + else: + self.set_lifetime(int(lifetime)) + self.lifeTime = legacy.get_lifetime() + self.set_privileges(legacy.get_privileges()) + self.get_privileges().delegate_all_privileges(legacy.get_delegate()) + + ## + # Need the issuer's private key and name + # @param key Keypair object containing the private key of the issuer + # @param gid GID of the issuing authority + + def set_issuer_keys(self, privkey, gid): + self.issuer_privkey = privkey + self.issuer_gid = gid + + + ## + # Set this credential's parent + def set_parent(self, cred): + self.parent = cred + self.updateRefID() ## # set the GID of the caller @@ -79,34 +287,25 @@ class Credential(Certificate): # set the lifetime of this credential # # @param lifetime lifetime of credential + # . if lifeTime is a datetime object, it is used for the expiration time + # . if lifeTime is an integer value, it is considered the number of seconds + # remaining before expiration def set_lifetime(self, lifeTime): - self.lifeTime = lifeTime + if isinstance(lifeTime, int): + self.expiration = datetime.timedelta(seconds=lifeTime) + datetime.datetime.utcnow() + else: + self.expiration = lifeTime ## - # get the lifetime of the credential + # get the lifetime of the credential (in datetime format) def get_lifetime(self): - if not self.lifeTime: - self.decode() - return self.lifeTime - - ## - # set the delegate bit - # - # @param delegate boolean (True or False) - - def set_delegate(self, delegate): - self.delegate = delegate - - ## - # get the delegate bit - - def get_delegate(self): - if not self.delegate: + if not self.expiration: self.decode() - return self.delegate + return self.expiration + ## # set the privileges # @@ -117,6 +316,7 @@ class Credential(Certificate): self.privileges = RightList(string = privs) else: self.privileges = privs + ## # return the privileges as a RightList object @@ -134,88 +334,405 @@ class Credential(Certificate): def can_perform(self, op_name): rights = self.get_privileges() + if not rights: return False + return rights.can_perform(op_name) + ## - # Encode the attributes of the credential into a string and store that - # string in the alt-subject-name field of the X509 object. This should be - # done immediately before signing the credential. + # Encode the attributes of the credential into an XML string + # This should be done immediately before signing the credential. + # WARNING: + # In general, a signed credential obtained externally should + # not be changed else the signature is no longer valid. So, once + # you have loaded an existing signed credential, do not call encode() or sign() on it. def encode(self): - dict = {"gidCaller": None, - "gidObject": None, - "lifeTime": self.lifeTime, - "privileges": None, - "delegate": self.delegate} - if self.gidCaller: - dict["gidCaller"] = self.gidCaller.save_to_string(save_parents=True) - if self.gidObject: - dict["gidObject"] = self.gidObject.save_to_string(save_parents=True) + # Create the XML document + doc = Document() + signed_cred = doc.createElement("signed-credential") + doc.appendChild(signed_cred) + + # Fill in the bit + cred = doc.createElement("credential") + cred.setAttribute("xml:id", self.get_refid()) + signed_cred.appendChild(cred) + append_sub(doc, cred, "type", "privilege") + append_sub(doc, cred, "serial", "8") + append_sub(doc, cred, "owner_gid", self.gidCaller.save_to_string()) + append_sub(doc, cred, "owner_urn", self.gidCaller.get_urn()) + append_sub(doc, cred, "target_gid", self.gidObject.save_to_string()) + append_sub(doc, cred, "target_urn", self.gidObject.get_urn()) + append_sub(doc, cred, "uuid", "") + if not self.expiration: + self.set_lifetime(DEFAULT_CREDENTIAL_LIFETIME) + self.expiration = self.expiration.replace(microsecond=0) + append_sub(doc, cred, "expires", self.expiration.isoformat()) + privileges = doc.createElement("privileges") + cred.appendChild(privileges) + if self.privileges: - dict["privileges"] = self.privileges.save_to_string() - str = xmlrpclib.dumps((dict,), allow_none=True) - self.set_data(str) + rights = self.get_privileges() + for right in rights.rights: + priv = doc.createElement("privilege") + append_sub(doc, priv, "name", right.kind) + append_sub(doc, priv, "can_delegate", str(right.delegate).lower()) + privileges.appendChild(priv) + + # Add the parent credential if it exists + if self.parent: + sdoc = parseString(self.parent.get_xml()) + p_cred = doc.importNode(sdoc.getElementsByTagName("credential")[0], True) + p = doc.createElement("parent") + p.appendChild(p_cred) + cred.appendChild(p) - ## - # Retrieve the attributes of the credential from the alt-subject-name field - # of the X509 certificate. This is automatically done by the various - # get_* methods of this class and should not need to be called explicitly. - def decode(self): - data = self.get_data() - if data: - dict = xmlrpclib.loads(self.get_data())[0][0] + # Create the tag + signatures = doc.createElement("signatures") + signed_cred.appendChild(signatures) + + # Add any parent signatures + if self.parent: + for cur_cred in self.get_credential_list()[1:]: + sdoc = parseString(cur_cred.get_signature().get_xml()) + ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True) + signatures.appendChild(ele) + + # Get the finished product + self.xml = doc.toxml() + + + def save_to_random_tmp_file(self): + fp, filename = mkstemp(suffix='cred', text=True) + fp = os.fdopen(fp, "w") + self.save_to_file(filename, save_parents=True, filep=fp) + return filename + + def save_to_file(self, filename, save_parents=True, filep=None): + if not self.xml: + self.encode() + if filep: + f = filep else: - dict = {} + f = open(filename, "w") + f.write(self.xml) + f.close() - self.lifeTime = dict.get("lifeTime", None) - self.delegate = dict.get("delegate", None) + def save_to_string(self, save_parents=True): + if not self.xml: + self.encode() + return self.xml - privStr = dict.get("privileges", None) - if privStr: - self.privileges = RightList(string = privStr) - else: - self.privileges = None + def get_refid(self): + if not self.refid: + self.refid = 'ref0' + return self.refid - gidCallerStr = dict.get("gidCaller", None) - if gidCallerStr: - self.gidCaller = GID(string=gidCallerStr) - else: - self.gidCaller = None + def set_refid(self, rid): + self.refid = rid - gidObjectStr = dict.get("gidObject", None) - if gidObjectStr: - self.gidObject = GID(string=gidObjectStr) - else: - self.gidObject = None + ## + # Figure out what refids exist, and update this credential's id + # so that it doesn't clobber the others. Returns the refids of + # the parents. + + def updateRefID(self): + if not self.parent: + self.set_refid('ref0') + return [] + + refs = [] + + next_cred = self.parent + while next_cred: + refs.append(next_cred.get_refid()) + if next_cred.parent: + next_cred = next_cred.parent + else: + next_cred = None + + + # Find a unique refid for this credential + rid = self.get_refid() + while rid in refs: + val = int(rid[3:]) + rid = "ref%d" % (val + 1) + + # Set the new refid + self.set_refid(rid) + + # Return the set of parent credential ref ids + return refs + + def get_xml(self): + if not self.xml: + self.encode() + return self.xml ## - # Verify that a chain of credentials is valid (see cert.py:verify). In - # addition to the checks for ordinary certificates, verification also - # ensures that the delegate bit was set by each parent in the chain. If - # a delegate bit was not set, then an exception is thrown. + # Sign the XML file created by encode() # - # Each credential must be a subset of the rights of the parent. + # WARNING: + # In general, a signed credential obtained externally should + # not be changed else the signature is no longer valid. So, once + # you have loaded an existing signed credential, do not call encode() or sign() on it. + + def sign(self): + if not self.issuer_privkey or not self.issuer_gid: + return + doc = parseString(self.get_xml()) + sigs = doc.getElementsByTagName("signatures")[0] + + # Create the signature template to be signed + signature = Signature() + signature.set_refid(self.get_refid()) + sdoc = parseString(signature.get_xml()) + sig_ele = doc.importNode(sdoc.getElementsByTagName("Signature")[0], True) + sigs.appendChild(sig_ele) + + self.xml = doc.toxml() + + + # Split the issuer GID into multiple certificates if it's a chain + chain = GID(filename=self.issuer_gid) + gid_files = [] + while chain: + gid_files.append(chain.save_to_random_tmp_file(False)) + if chain.get_parent(): + chain = chain.get_parent() + else: + chain = None + + + # Call out to xmlsec1 to sign it + ref = 'Sig_%s' % self.get_refid() + filename = self.save_to_random_tmp_file() + signed = os.popen('%s --sign --node-id "%s" --privkey-pem %s,%s %s' \ + % (self.xmlsec_path, ref, self.issuer_privkey, ",".join(gid_files), filename)).read() + os.remove(filename) + + for gid_file in gid_files: + os.remove(gid_file) + + self.xml = signed + + # This is no longer a legacy credential + if self.legacy: + self.legacy = None + + # Update signatures + self.decode() - def verify_chain(self, trusted_certs = None): - # do the normal certificate verification stuff - Certificate.verify_chain(self, trusted_certs) + + + ## + # Retrieve the attributes of the credential from the XML. + # This is automatically called by the various get_* methods of + # this class and should not need to be called explicitly. + + def decode(self): + if not self.xml: + return + doc = parseString(self.xml) + sigs = [] + signed_cred = doc.getElementsByTagName("signed-credential") + + # Is this a signed-cred or just a cred? + if len(signed_cred) > 0: + cred = signed_cred[0].getElementsByTagName("credential")[0] + signatures = signed_cred[0].getElementsByTagName("signatures") + if len(signatures) > 0: + sigs = signatures[0].getElementsByTagName("Signature") + else: + cred = doc.getElementsByTagName("credential")[0] + + + + self.set_refid(cred.getAttribute("xml:id")) + self.set_lifetime(parse(getTextNode(cred, "expires"))) + self.gidCaller = GID(string=getTextNode(cred, "owner_gid")) + self.gidObject = GID(string=getTextNode(cred, "target_gid")) + + + # Process privileges + privs = cred.getElementsByTagName("privileges")[0] + rlist = RightList() + for priv in privs.getElementsByTagName("privilege"): + kind = getTextNode(priv, "name") + deleg = str2bool(getTextNode(priv, "can_delegate")) + if kind == '*': + # Convert * into the default privileges for the credential's type + _ , type = urn_to_hrn(self.gidObject.get_urn()) + rl = rlist.determine_rights(type, self.gidObject.get_urn()) + for r in rl.rights: + rlist.add(r) + else: + rlist.add(Right(kind.strip(), deleg)) + self.set_privileges(rlist) + + + # Is there a parent? + parent = cred.getElementsByTagName("parent") + if len(parent) > 0: + parent_doc = parent[0].getElementsByTagName("credential")[0] + parent_xml = parent_doc.toxml() + self.parent = Credential(string=parent_xml) + self.updateRefID() + + # Assign the signatures to the credentials + for sig in sigs: + Sig = Signature(string=sig.toxml()) + + for cur_cred in self.get_credential_list(): + if cur_cred.get_refid() == Sig.get_refid(): + cur_cred.set_signature(Sig) + + + ## + # Verify + # trusted_certs: A list of trusted GID filenames (not GID objects!) + # Chaining is not supported within the GIDs by xmlsec1. + # + # Verify that: + # . All of the signatures are valid and that the issuers trace back + # to trusted roots (performed by xmlsec1) + # . The XML matches the credential schema + # . That the issuer of the credential is the authority in the target's urn + # . In the case of a delegated credential, this must be true of the root + # . That all of the gids presented in the credential are valid + # . The credential is not expired + # + # -- For Delegates (credentials with parents) + # . The privileges must be a subset of the parent credentials + # . The privileges must have "can_delegate" set for each delegated privilege + # . The target gid must be the same between child and parents + # . The expiry time on the child must be no later than the parent + # . The signer of the child must be the owner of the parent + # + # -- Verify does *NOT* + # . ensure that an xmlrpc client's gid matches a credential gid, that + # must be done elsewhere + # + # @param trusted_certs: The certificates of trusted CA certificates + + def verify(self, trusted_certs): + if not self.xml: + self.decode() + trusted_cert_objects = [GID(filename=f) for f in trusted_certs] + + # Use legacy verification if this is a legacy credential + if self.legacy: + self.legacy.verify_chain(trusted_cert_objects) + if self.legacy.client_gid: + self.legacy.client_gid.verify_chain(trusted_cert_objects) + if self.legacy.object_gid: + self.legacy.object_gid.verify_chain(trusted_cert_objects) + return True + + # make sure it is not expired + if self.get_lifetime() < datetime.datetime.utcnow(): + raise CredentialNotVerifiable("credential is expired") + + # Verify the signatures + filename = self.save_to_random_tmp_file() + cert_args = " ".join(['--trusted-pem %s' % x for x in trusted_certs]) + + # Verify the gids of this cred and of its parents + + + + for cur_cred in self.get_credential_list(): + cur_cred.get_gid_object().verify_chain(trusted_cert_objects) + cur_cred.get_gid_caller().verify_chain(trusted_cert_objects) + + + refs = [] + refs.append("Sig_%s" % self.get_refid()) + + parentRefs = self.updateRefID() + for ref in parentRefs: + refs.append("Sig_%s" % ref) + + for ref in refs: + verified = os.popen('%s --verify --node-id "%s" %s %s 2>&1' \ + % (self.xmlsec_path, ref, cert_args, filename)).read() + if not verified.strip().startswith("OK"): + raise CredentialNotVerifiable("xmlsec1 error: " + verified) + os.remove(filename) + + # Verify the parents (delegation) if self.parent: - # make sure the parent delegated rights to the child - if not self.parent.get_delegate(): - raise MissingDelegateBit(self.parent.get_subject()) + self.verify_parent(self.parent) + + # Make sure the issuer is the target's authority + self.verify_issuer() + return True - # make sure the rights given to the child are a subset of the - # parents rights - if not self.parent.get_privileges().is_superset(self.get_privileges()): - raise ChildRightsNotSubsetOfParent(self.get_subject() - + " " + self.parent.get_privileges().save_to_string() - + " " + self.get_privileges().save_to_string()) + ## + # Creates a list of the credential and its parents, with the root + # (original delegated credential) as the last item in the list + def get_credential_list(self): + cur_cred = self + list = [] + while cur_cred: + list.append(cur_cred) + if cur_cred.parent: + cur_cred = cur_cred.parent + else: + cur_cred = None + return list + + ## + # Make sure the credential's target gid was signed by (or is the same) as the entity that signed + # the original credential. + def verify_issuer(self): + root_cred = self.get_credential_list()[-1] + root_target_gid = root_cred.get_gid_object() + root_cred_signer = root_cred.get_signature().get_issuer_gid() + + if root_target_gid.is_signed_by_cert(root_cred_signer) or \ + root_target_gid.save_to_string() == root_cred_signer.save_to_string(): + pass + else: + raise CredentialNotVerifiable("Could not verify credential signer") + - return + ## + # -- For Delegates (credentials with parents) verify that: + # . The privileges must be a subset of the parent credentials + # . The privileges must have "can_delegate" set for each delegated privilege + # . The target gid must be the same between child and parents + # . The expiry time on the child must be no later than the parent + # . The signer of the child must be the owner of the parent + + def verify_parent(self, parent_cred): + # make sure the rights given to the child are a subset of the + # parents rights (and check delegate bits) + if not parent_cred.get_privileges().is_superset(self.get_privileges()): + raise ChildRightsNotSubsetOfParent( + self.parent.get_privileges().save_to_string() + " " + + self.get_privileges().save_to_string()) + + # make sure my target gid is the same as the parent's + if not parent_cred.get_gid_object().save_to_string() == \ + self.get_gid_object().save_to_string(): + raise CredentialNotVerifiable("target gid not equal between parent and child") + + # make sure my expiry time is <= my parent's + if not parent_cred.get_lifetime() >= self.get_lifetime(): + raise CredentialNotVerifiable("delegated credential expires after parent") + + # make sure my signer is the parent's caller + if not parent_cred.get_gid_caller().save_to_string(False) == \ + self.get_signature().get_issuer_gid().save_to_string(False): + raise CredentialNotVerifiable("delegated credential not signed by parent caller") + + if parent_cred.parent: + parent_cred.verify_parent(parent_cred.parent) ## # Dump the contents of a credential to stdout in human-readable format @@ -237,9 +754,8 @@ class Credential(Certificate): if gidObject: gidObject.dump(8, dump_parents) - print " delegate:", self.get_delegate() if self.parent and dump_parents: - print "PARENT", - self.parent.dump(dump_parents) + print "PARENT", + self.parent.dump_parents()