#----------------------------------------------------------------------
# Copyright (c) 2008 Board of Trustees, Princeton University
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and/or hardware specification (the "Work") to
# deal in the Work without restriction, including without limitation the
# rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Work, and to permit persons to whom the Work
# is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Work.
#
# THE WORK IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE WORK OR THE USE OR OTHER DEALINGS
# IN THE WORK.
#----------------------------------------------------------------------
##
# Implements SFA Credentials
#
# Credentials are signed XML files that assign a subject gid privileges to an object gid
##
from __future__ import print_function
import os, os.path
import subprocess
import datetime
from tempfile import mkstemp
from xml.dom.minidom import Document, parseString
from sfa.util.py23 import StringType
from sfa.util.py23 import StringIO
HAVELXML = False
try:
from lxml import etree
HAVELXML = True
except:
pass
from xml.parsers.expat import ExpatError
from sfa.util.faults import CredentialNotVerifiable, ChildRightsNotSubsetOfParent
from sfa.util.sfalogging import logger
from sfa.util.sfatime import utcparse, SFATIME_FORMAT
from sfa.trust.rights import Right, Rights, determine_rights
from sfa.trust.gid import GID
from sfa.util.xrn import urn_to_hrn, hrn_authfor_hrn
# 31 days, in seconds
DEFAULT_CREDENTIAL_LIFETIME = 86400 * 31
# TODO:
# . make privs match between PG and PL
# . Need to add support for other types of credentials, e.g. tickets
# . add namespaces to signed-credential element?
signature_format = \
'''
'''
##
# Convert a string into a bool
# used to convert an xsd:boolean to a Python boolean
def str2bool(str):
if str.lower() in ['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):
# Helper function to pull characters off the front of a string if present
def remove_prefix(text, prefix):
if text and prefix and text.startswith(prefix):
return text[len(prefix):]
return text
try:
doc = parseString(self.xml)
except ExpatError as e:
logger.log_exc("Failed to parse credential, {}".format(self.xml))
raise
sig = doc.getElementsByTagName("Signature")[0]
## This code until the end of function rewritten by Aaron Helsinger
ref_id = remove_prefix(sig.getAttribute("xml:id").strip(), "Sig_")
# The xml:id tag is optional, and could be in a
# Reference xml:id or Reference UID sub element instead
if not ref_id or ref_id == '':
reference = sig.getElementsByTagName('Reference')[0]
ref_id = remove_prefix(reference.getAttribute('xml:id').strip(), "Sig_")
if not ref_id or ref_id == '':
ref_id = remove_prefix(reference.getAttribute('URI').strip(), "#")
self.set_refid(ref_id)
keyinfos = sig.getElementsByTagName("X509Data")
gids = None
for keyinfo in keyinfos:
certs = keyinfo.getElementsByTagName("X509Certificate")
for cert in certs:
if len(cert.childNodes) > 0:
szgid = cert.childNodes[0].nodeValue
szgid = szgid.strip()
szgid = "-----BEGIN CERTIFICATE-----\n{}\n-----END CERTIFICATE-----".format(szgid)
if gids is None:
gids = szgid
else:
gids += "\n" + szgid
if gids is None:
raise CredentialNotVerifiable("Malformed XML: No certificate found in signature")
self.set_issuer_gid(GID(string=gids))
def encode(self):
self.xml = signature_format.format(refid=self.get_refid())
##
# 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 (now unsupported) places it in the subjectAltName of an X509 certificate.
# The new credentials are placed in signed XML.
#
# 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 filter_creds_by_caller(creds, caller_hrn_list):
"""
Returns a list of creds who's gid caller matches the
specified caller hrn
"""
if not isinstance(creds, list): creds = [creds]
if not isinstance(caller_hrn_list, list):
caller_hrn_list = [caller_hrn_list]
caller_creds = []
for cred in creds:
try:
tmp_cred = Credential(string=cred)
if tmp_cred.type != Credential.SFA_CREDENTIAL_TYPE:
continue
if tmp_cred.get_gid_caller().get_hrn() in caller_hrn_list:
caller_creds.append(cred)
except: pass
return caller_creds
class Credential(object):
SFA_CREDENTIAL_TYPE = "geni_sfa"
##
# Create a Credential object
#
# @param create If true, create a blank x509 certificate
# @param subject If subject!=None, create an x509 cert with the subject name
# @param string If string!=None, load the credential from the string
# @param filename If filename!=None, load the credential from the file
# FIXME: create and subject are ignored!
def __init__(self, create=False, subject=None, string=None, filename=None, cred=None):
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.type = Credential.SFA_CREDENTIAL_TYPE
self.version = None
if cred:
if isinstance(cred, StringType):
string = cred
self.type = Credential.SFA_CREDENTIAL_TYPE
self.version = '3'
elif isinstance(cred, dict):
string = cred['geni_value']
self.type = cred['geni_type']
self.version = cred['geni_version']
if string or filename:
if string:
str = string
elif filename:
with open(filename) as infile:
str = infile.read()
# if this is a legacy credential, write error and bail out
if isinstance(str, StringType) and str.strip().startswith("-----"):
logger.error("Legacy credentials not supported any more - giving up with {}...".format(str[:10]))
return
else:
self.xml = str
self.decode()
# not strictly necessary but won't hurt either
self.get_xmlsec1_path()
@staticmethod
def get_xmlsec1_path():
if not getattr(Credential, 'xmlsec1_path', None):
# Find a xmlsec1 binary path
Credential.xmlsec1_path = ''
paths = ['/usr/bin', '/usr/local/bin', '/bin', '/opt/bin', '/opt/local/bin']
try: paths += os.getenv('PATH').split(':')
except: pass
for path in paths:
xmlsec1 = os.path.join(path, 'xmlsec1')
if os.path.isfile(xmlsec1):
Credential.xmlsec1_path = xmlsec1
break
if not Credential.xmlsec1_path:
logger.error("Could not locate required binary 'xmlsec1' - SFA will be unable to sign stuff !!")
return Credential.xmlsec1_path
def get_subject(self):
if not self.gidObject:
self.decode()
return self.gidObject.get_subject()
def pretty_subject(self):
subject = ""
if not self.gidObject:
self.decode()
if self.gidObject:
subject = self.gidObject.pretty_cert()
return subject
# sounds like this should be __repr__ instead ??
def pretty_cred(self):
if not self.gidObject:
self.decode()
obj = self.gidObject.pretty_cert()
caller = self.gidCaller.pretty_cert()
exp = self.get_expiration()
# Summarize the rights too? The issuer?
return "[Cred. for {caller} rights on {obj} until {exp} ]".format(**locals())
def get_signature(self):
if not self.signature:
self.decode()
return self.signature
def set_signature(self, sig):
self.signature = sig
##
# 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
#
# @param gid GID object of the caller
def set_gid_caller(self, gid):
self.gidCaller = gid
# gid origin caller is the caller's gid by default
self.gidOriginCaller = gid
##
# get the GID of the object
def get_gid_caller(self):
if not self.gidCaller:
self.decode()
return self.gidCaller
##
# set the GID of the object
#
# @param gid GID object of the object
def set_gid_object(self, gid):
self.gidObject = gid
##
# get the GID of the object
def get_gid_object(self):
if not self.gidObject:
self.decode()
return self.gidObject
##
# Expiration: an absolute UTC time of expiration (as either an int or string or datetime)
#
def set_expiration(self, expiration):
expiration_datetime = utcparse(expiration)
if expiration_datetime is not None:
self.expiration = expiration_datetime
else:
logger.error("unexpected input {} in Credential.set_expiration".format(expiration))
##
# get the lifetime of the credential (always in datetime format)
def get_expiration(self):
if not self.expiration:
self.decode()
# at this point self.expiration is normalized as a datetime - DON'T call utcparse again
return self.expiration
##
# set the privileges
#
# @param privs either a comma-separated list of privileges of a Rights object
def set_privileges(self, privs):
if isinstance(privs, str):
self.privileges = Rights(string = privs)
else:
self.privileges = privs
##
# return the privileges as a Rights object
def get_privileges(self):
if not self.privileges:
self.decode()
return self.privileges
##
# determine whether the credential allows a particular operation to be
# performed
#
# @param op_name string specifying name of operation ("lookup", "update", etc)
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 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):
# Create the XML document
doc = Document()
signed_cred = doc.createElement("signed-credential")
# Declare namespaces
# Note that credential/policy.xsd are really the PG schemas
# in a PL namespace.
# Note that delegation of credentials between the 2 only really works
# cause those schemas are identical.
# Also note these PG schemas talk about PG tickets and CM policies.
signed_cred.setAttribute("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance")
# FIXME: See v2 schema at www.geni.net/resources/credential/2/credential.xsd
signed_cred.setAttribute("xsi:noNamespaceSchemaLocation", "http://www.planet-lab.org/resources/sfa/credential.xsd")
signed_cred.setAttribute("xsi:schemaLocation", "http://www.planet-lab.org/resources/sfa/ext/policy/1 http://www.planet-lab.org/resources/sfa/ext/policy/1/policy.xsd")
# PG says for those last 2:
# signed_cred.setAttribute("xsi:noNamespaceSchemaLocation", "http://www.protogeni.net/resources/credential/credential.xsd")
# signed_cred.setAttribute("xsi:schemaLocation", "http://www.protogeni.net/resources/credential/ext/policy/1 http://www.protogeni.net/resources/credential/ext/policy/1/policy.xsd")
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:
logger.debug("Creating credential valid for {} s".format(DEFAULT_CREDENTIAL_LIFETIME))
self.set_expiration(datetime.datetime.utcnow() + datetime.timedelta(seconds=DEFAULT_CREDENTIAL_LIFETIME))
self.expiration = self.expiration.replace(microsecond=0)
if self.expiration.tzinfo is not None and self.expiration.tzinfo.utcoffset(self.expiration) is not None:
# TZ aware. Make sure it is UTC - by Aaron Helsinger
self.expiration = self.expiration.astimezone(tz.tzutc())
append_sub(doc, cred, "expires", self.expiration.strftime(SFATIME_FORMAT))
privileges = doc.createElement("privileges")
cred.appendChild(privileges)
if self.privileges:
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())
# If the root node is a signed-credential (it should be), then
# get all its attributes and attach those to our signed_cred
# node.
# Specifically, PG and PLadd attributes for namespaces (which is reasonable),
# and we need to include those again here or else their signature
# no longer matches on the credential.
# We expect three of these, but here we copy them all:
# signed_cred.setAttribute("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance")
# and from PG (PL is equivalent, as shown above):
# signed_cred.setAttribute("xsi:noNamespaceSchemaLocation", "http://www.protogeni.net/resources/credential/credential.xsd")
# signed_cred.setAttribute("xsi:schemaLocation", "http://www.protogeni.net/resources/credential/ext/policy/1 http://www.protogeni.net/resources/credential/ext/policy/1/policy.xsd")
# HOWEVER!
# PL now also declares these, with different URLs, so
# the code notices those attributes already existed with
# different values, and complains.
# This happens regularly on delegation now that PG and
# PL both declare the namespace with different URLs.
# If the content ever differs this is a problem,
# but for now it works - different URLs (values in the attributes)
# but the same actual schema, so using the PG schema
# on delegated-to-PL credentials works fine.
# Note: you could also not copy attributes
# which already exist. It appears that both PG and PL
# will actually validate a slicecred with a parent
# signed using PG namespaces and a child signed with PL
# namespaces over the whole thing. But I don't know
# if that is a bug in xmlsec1, an accident since
# the contents of the schemas are the same,
# or something else, but it seems odd. And this works.
parentRoot = sdoc.documentElement
if parentRoot.tagName == "signed-credential" and parentRoot.hasAttributes():
for attrIx in range(0, parentRoot.attributes.length):
attr = parentRoot.attributes.item(attrIx)
# returns the old attribute of same name that was
# on the credential
# Below throws InUse exception if we forgot to clone the attribute first
oldAttr = signed_cred.setAttributeNode(attr.cloneNode(True))
if oldAttr and oldAttr.value != attr.value:
msg = "Delegating cred from owner {} to {} over {}:\n"
"- Replaced attribute {} value '{}' with '{}'"\
.format(self.parent.gidCaller.get_urn(), self.gidCaller.get_urn(),
self.gidObject.get_urn(), oldAttr.name, oldAttr.value, attr.value)
logger.warn(msg)
#raise CredentialNotVerifiable("Can't encode new valid delegated credential: {}".format(msg))
p_cred = doc.importNode(sdoc.getElementsByTagName("credential")[0], True)
p = doc.createElement("parent")
p.appendChild(p_cred)
cred.appendChild(p)
# done handling parent credential
# 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("utf-8")
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:
f = open(filename, "w")
f.write(self.xml)
f.close()
def save_to_string(self, save_parents=True):
if not self.xml:
self.encode()
return self.xml
def get_refid(self):
if not self.refid:
self.refid = 'ref0'
return self.refid
def set_refid(self, rid):
self.refid = rid
##
# 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{}".format(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
##
# Sign the XML file created by encode()
#
# 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:
logger.warn("Cannot sign credential (no private key)")
return
if not self.issuer_gid:
logger.warn("Cannot sign credential (no 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("utf-8")
# 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_{}'.format(self.get_refid())
filename = self.save_to_random_tmp_file()
xmlsec1 = self.get_xmlsec1_path()
if not xmlsec1:
raise Exception("Could not locate required 'xmlsec1' program")
command = '{} --sign --node-id "{}" --privkey-pem {},{} {}' \
.format(xmlsec1, ref, self.issuer_privkey, ",".join(gid_files), filename)
signed = os.popen(command).read()
os.remove(filename)
for gid_file in gid_files:
os.remove(gid_file)
self.xml = signed
# Update signatures
self.decode()
##
# 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 = None
try:
doc = parseString(self.xml)
except ExpatError as e:
raise CredentialNotVerifiable("Malformed credential")
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:
creds = signed_cred[0].getElementsByTagName("credential")
signatures = signed_cred[0].getElementsByTagName("signatures")
if len(signatures) > 0:
sigs = signatures[0].getElementsByTagName("Signature")
else:
creds = doc.getElementsByTagName("credential")
if creds is None or len(creds) == 0:
# malformed cred file
raise CredentialNotVerifiable("Malformed XML: No credential tag found")
# Just take the first cred if there are more than one
cred = creds[0]
self.set_refid(cred.getAttribute("xml:id"))
self.set_expiration(utcparse(getTextNode(cred, "expires")))
self.gidCaller = GID(string=getTextNode(cred, "owner_gid"))
self.gidObject = GID(string=getTextNode(cred, "target_gid"))
## This code until the end of function rewritten by Aaron Helsinger
# Process privileges
rlist = Rights()
priv_nodes = cred.getElementsByTagName("privileges")
if len(priv_nodes) > 0:
privs = priv_nodes[0]
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
# Each inherits the delegatability from the * above
_ , type = urn_to_hrn(self.gidObject.get_urn())
rl = determine_rights(type, self.gidObject.get_urn())
for r in rl.rights:
r.delegate = deleg
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("utf-8")
if parent_xml is None or parent_xml.strip() == "":
raise CredentialNotVerifiable("Malformed XML: Had parent tag but it is empty")
self.parent = Credential(string=parent_xml)
self.updateRefID()
# Assign the signatures to the credentials
for sig in sigs:
Sig = Signature(string=sig.toxml("utf-8"))
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.
#
# trusted_certs_required: Should usually be true. Set False means an
# empty list of trusted_certs would still let this method pass.
# It just skips xmlsec1 verification et al. Only used by some utils
#
# 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
# . Including verifying GID chains, and includ the issuer
# . 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=None, schema=None, trusted_certs_required=True):
if not self.xml:
self.decode()
# validate against RelaxNG schema
if HAVELXML:
if schema and os.path.exists(schema):
tree = etree.parse(StringIO(self.xml))
schema_doc = etree.parse(schema)
xmlschema = etree.XMLSchema(schema_doc)
if not xmlschema.validate(tree):
error = xmlschema.error_log.last_error
message = "{}: {} (line {})".format(self.pretty_cred(),
error.message, error.line)
raise CredentialNotVerifiable(message)
if trusted_certs_required and trusted_certs is None:
trusted_certs = []
# trusted_cert_objects = [GID(filename=f) for f in trusted_certs]
trusted_cert_objects = []
ok_trusted_certs = []
# If caller explicitly passed in None that means skip cert chain validation.
# Strange and not typical
if trusted_certs is not None:
for f in trusted_certs:
try:
# Failures here include unreadable files
# or non PEM files
trusted_cert_objects.append(GID(filename=f))
ok_trusted_certs.append(f)
except Exception as exc:
logger.error("Failed to load trusted cert from {}: {}".format(f, exc))
trusted_certs = ok_trusted_certs
# make sure it is not expired
if self.get_expiration() < datetime.datetime.utcnow():
raise CredentialNotVerifiable("Credential {} expired at {}" \
.format(self.pretty_cred(),
self.expiration.strftime(SFATIME_FORMAT)))
# Verify the signatures
filename = self.save_to_random_tmp_file()
# If caller explicitly passed in None that means skip cert chain validation.
# - Strange and not typical
if trusted_certs is not None:
# 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_{}".format(self.get_refid()))
parentRefs = self.updateRefID()
for ref in parentRefs:
refs.append("Sig_{}".format(ref))
for ref in refs:
# If caller explicitly passed in None that means skip xmlsec1 validation.
# Strange and not typical
if trusted_certs is None:
break
# Thierry - jan 2015
# up to fedora20 we used os.popen and checked that the output begins with OK
# turns out, with fedora21, there is extra input before this 'OK' thing
# looks like we're better off just using the exit code - that's what it is made for
#cert_args = " ".join(['--trusted-pem {}'.format(x) for x in trusted_certs])
#command = '{} --verify --node-id "{}" {} {} 2>&1'.\
# format(self.xmlsec_path, ref, cert_args, filename)
xmlsec1 = self.get_xmlsec1_path()
if not xmlsec1:
raise Exception("Could not locate required 'xmlsec1' program")
command = [ xmlsec1, '--verify', '--node-id', ref ]
for trusted in trusted_certs:
command += ["--trusted-pem", trusted ]
command += [ filename ]
logger.debug("Running " + " ".join(command))
try:
verified = subprocess.check_output(command, stderr=subprocess.STDOUT)
logger.debug("xmlsec command returned {}".format(verified))
if "OK\n" not in verified:
logger.warning("WARNING: xmlsec1 seemed to return fine but without a OK in its output")
except subprocess.CalledProcessError as e:
verified = e.output
# xmlsec errors have a msg= which is the interesting bit.
mstart = verified.find("msg=")
msg = ""
if mstart > -1 and len(verified) > 4:
mstart = mstart + 4
mend = verified.find('\\', mstart)
msg = verified[mstart:mend]
logger.warning("Credential.verify - failed - xmlsec1 returned {}".format(verified.strip()))
raise CredentialNotVerifiable("xmlsec1 error verifying cred {} using Signature ID {}: {}"\
.format(self.pretty_cred(), ref, msg))
os.remove(filename)
# Verify the parents (delegation)
if self.parent:
self.verify_parent(self.parent)
# Make sure the issuer is the target's authority, and is
# itself a valid GID
self.verify_issuer(trusted_cert_objects)
return True
##
# 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 (a) was signed by or (b)
# is the same as the entity that signed the original credential,
# or (c) is an authority over the target's namespace.
# Also ensure that the credential issuer / signer itself has a valid
# GID signature chain (signed by an authority with namespace rights).
def verify_issuer(self, trusted_gids):
root_cred = self.get_credential_list()[-1]
root_target_gid = root_cred.get_gid_object()
if root_cred.get_signature() is None:
# malformed
raise CredentialNotVerifiable("Could not verify credential owned by {} for object {}. "
"Cred has no signature" \
.format(self.gidCaller.get_urn(), self.gidObject.get_urn()))
root_cred_signer = root_cred.get_signature().get_issuer_gid()
# Case 1:
# Allow non authority to sign target and cred about target.
#
# Why do we need to allow non authorities to sign?
# If in the target gid validation step we correctly
# checked that the target is only signed by an authority,
# then this is just a special case of case 3.
# This short-circuit is the common case currently -
# and cause GID validation doesn't check 'authority',
# this allows users to generate valid slice credentials.
if root_target_gid.is_signed_by_cert(root_cred_signer):
# cred signer matches target signer, return success
return
# Case 2:
# Allow someone to sign credential about themeselves. Used?
# If not, remove this.
#root_target_gid_str = root_target_gid.save_to_string()
#root_cred_signer_str = root_cred_signer.save_to_string()
#if root_target_gid_str == root_cred_signer_str:
# # cred signer is target, return success
# return
# Case 3:
# root_cred_signer is not the target_gid
# So this is a different gid that we have not verified.
# xmlsec1 verified the cert chain on this already, but
# it hasn't verified that the gid meets the HRN namespace
# requirements.
# Below we'll ensure that it is an authority.
# But we haven't verified that it is _signed by_ an authority
# We also don't know if xmlsec1 requires that cert signers
# are marked as CAs.
# Note that if verify() gave us no trusted_gids then this
# call will fail. So skip it if we have no trusted_gids
if trusted_gids and len(trusted_gids) > 0:
root_cred_signer.verify_chain(trusted_gids)
else:
logger.debug("Cannot verify that cred signer is signed by a trusted authority. "
"No trusted gids. Skipping that check.")
# See if the signer is an authority over the domain of the target.
# There are multiple types of authority - accept them all here
# Maybe should be (hrn, type) = urn_to_hrn(root_cred_signer.get_urn())
root_cred_signer_type = root_cred_signer.get_type()
if root_cred_signer_type.find('authority') == 0:
#logger.debug('Cred signer is an authority')
# signer is an authority, see if target is in authority's domain
signerhrn = root_cred_signer.get_hrn()
if hrn_authfor_hrn(signerhrn, root_target_gid.get_hrn()):
return
# We've required that the credential be signed by an authority
# for that domain. Reasonable and probably correct.
# A looser model would also allow the signer to be an authority
# in my control framework - eg My CA or CH. Even if it is not
# the CH that issued these, eg, user credentials.
# Give up, credential does not pass issuer verification
raise CredentialNotVerifiable(
"Could not verify credential owned by {} for object {}. "
"Cred signer {} not the trusted authority for Cred target {}"
.format(self.gidCaller.get_hrn(), self.gidObject.get_hrn(),
root_cred_signer.get_hrn(), root_target_gid.get_hrn()))
##
# -- 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()):
message = (
"Parent cred {} (ref {}) rights {} "
" not superset of delegated cred {} (ref {}) rights {}"
.format(parent_cred.pretty_cred(),parent_cred.get_refid(),
parent_cred.get_privileges().pretty_rights(),
self.pretty_cred(), self.get_refid(),
self.get_privileges().pretty_rights()))
logger.error(message)
logger.error("parent details {}".format(parent_cred.get_privileges().save_to_string()))
logger.error("self details {}".format(self.get_privileges().save_to_string()))
raise ChildRightsNotSubsetOfParent(message)
# 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():
message = (
"Delegated cred {}: Target gid not equal between parent and child. Parent {}"
.format(self.pretty_cred(), parent_cred.pretty_cred()))
logger.error(message)
logger.error("parent details {}".format(parent_cred.save_to_string()))
logger.error("self details {}".format(self.save_to_string()))
raise CredentialNotVerifiable(message)
# make sure my expiry time is <= my parent's
if not parent_cred.get_expiration() >= self.get_expiration():
raise CredentialNotVerifiable(
"Delegated credential {} expires after parent {}"
.format(self.pretty_cred(), parent_cred.pretty_cred()))
# 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):
message = "Delegated credential {} not signed by parent {}'s caller"\
.format(self.pretty_cred(), parent_cred.pretty_cred())
logger.error(message)
logger.error("compare1 parent {}".format(parent_cred.get_gid_caller().pretty_cred()))
logger.error("compare1 parent details {}".format(parent_cred.get_gid_caller().save_to_string()))
logger.error("compare2 self {}".format(self.get_signature().get_issuer_gid().pretty_cred()))
logger.error("compare2 self details {}".format(self.get_signature().get_issuer_gid().save_to_string()))
raise CredentialNotVerifiable(message)
# Recurse
if parent_cred.parent:
parent_cred.verify_parent(parent_cred.parent)
def delegate(self, delegee_gidfile, caller_keyfile, caller_gidfile):
"""
Return a delegated copy of this credential, delegated to the
specified gid's user.
"""
# get the gid of the object we are delegating
object_gid = self.get_gid_object()
object_hrn = object_gid.get_hrn()
# the hrn of the user who will be delegated to
delegee_gid = GID(filename=delegee_gidfile)
delegee_hrn = delegee_gid.get_hrn()
#user_key = Keypair(filename=keyfile)
#user_hrn = self.get_gid_caller().get_hrn()
subject_string = "{} delegated to {}".format(object_hrn, delegee_hrn)
dcred = Credential(subject=subject_string)
dcred.set_gid_caller(delegee_gid)
dcred.set_gid_object(object_gid)
dcred.set_parent(self)
dcred.set_expiration(self.get_expiration())
dcred.set_privileges(self.get_privileges())
dcred.get_privileges().delegate_all_privileges(True)
#dcred.set_issuer_keys(keyfile, delegee_gidfile)
dcred.set_issuer_keys(caller_keyfile, caller_gidfile)
dcred.encode()
dcred.sign()
return dcred
# only informative
def get_filename(self):
return getattr(self,'filename',None)
def actual_caller_hrn(self):
"""a helper method used by some API calls like e.g. Allocate
to try and find out who really is the original caller
This admittedly is a bit of a hack, please USE IN LAST RESORT
This code uses a heuristic to identify a delegated credential
A first known restriction if for traffic that gets through a slice manager
in this case the hrn reported is the one from the last SM in the call graph
which is not at all what is meant here"""
caller_hrn = self.get_gid_caller().get_hrn()
issuer_hrn = self.get_signature().get_issuer_gid().get_hrn()
subject_hrn = self.get_gid_object().get_hrn()
# if we find that the caller_hrn is an immediate descendant of the issuer, then
# this seems to be a 'regular' credential
if caller_hrn.startswith(issuer_hrn):
actual_caller_hrn=caller_hrn
# else this looks like a delegated credential, and the real caller is the issuer
else:
actual_caller_hrn=issuer_hrn
logger.info("actual_caller_hrn: caller_hrn={}, issuer_hrn={}, returning {}"
.format(caller_hrn,issuer_hrn,actual_caller_hrn))
return actual_caller_hrn
##
# Dump the contents of a credential to stdout in human-readable format
#
# @param dump_parents If true, also dump the parent certificates
def dump(self, *args, **kwargs):
print(self.dump_string(*args, **kwargs))
# SFA code ignores show_xml and disables printing the cred xml
def dump_string(self, dump_parents=False, show_xml=False):
result=""
result += "CREDENTIAL {}\n".format(self.pretty_subject())
filename=self.get_filename()
if filename: result += "Filename {}\n".format(filename)
privileges = self.get_privileges()
if privileges:
result += " privs: {}\n".format(privileges.save_to_string())
else:
result += " privs: \n"
gidCaller = self.get_gid_caller()
if gidCaller:
result += " gidCaller:\n"
result += gidCaller.dump_string(8, dump_parents)
if self.get_signature():
result += " gidIssuer:\n"
result += self.get_signature().get_issuer_gid().dump_string(8, dump_parents)
if self.expiration:
result += " expiration: " + self.expiration.strftime(SFATIME_FORMAT) + "\n"
gidObject = self.get_gid_object()
if gidObject:
result += " gidObject:\n"
result += gidObject.dump_string(8, dump_parents)
if self.parent and dump_parents:
result += "\nPARENT"
result += self.parent.dump_string(True)
if show_xml and HAVELXML:
try:
tree = etree.parse(StringIO(self.xml))
aside = etree.tostring(tree, pretty_print=True)
result += "\nXML:\n\n"
result += aside
result += "\nEnd XML\n"
except:
import traceback
print("exc. Credential.dump_string / XML")
traceback.print_exc()
return result