1 #----------------------------------------------------------------------
2 # Copyright (c) 2014 Raytheon BBN Technologies
4 # Permission is hereby granted, free of charge, to any person obtaining
5 # a copy of this software and/or hardware specification (the "Work") to
6 # deal in the Work without restriction, including without limitation the
7 # rights to use, copy, modify, merge, publish, distribute, sublicense,
8 # and/or sell copies of the Work, and to permit persons to whom the Work
9 # is furnished to do so, subject to the following conditions:
11 # The above copyright notice and this permission notice shall be
12 # included in all copies or substantial portions of the Work.
14 # THE WORK IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
16 # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
17 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
18 # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
19 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 # OUT OF OR IN CONNECTION WITH THE WORK OR THE USE OR OTHER DEALINGS
22 #----------------------------------------------------------------------
24 from __future__ import print_function
26 from sfa.trust.credential import Credential, append_sub, DEFAULT_CREDENTIAL_LIFETIME
27 from sfa.util.sfalogging import logger
28 from sfa.util.sfatime import SFATIME_FORMAT
30 from StringIO import StringIO
31 from xml.dom.minidom import Document, parseString
35 from lxml import etree
40 # This module defines a subtype of sfa.trust,credential.Credential
41 # called an ABACCredential. An ABAC credential is a signed statement
42 # asserting a role representing the relationship between a subject and target
43 # or between a subject and a class of targets (all those satisfying a role).
45 # An ABAC credential is like a normal SFA credential in that it has
46 # a validated signature block and is checked for expiration.
47 # It does not, however, have 'privileges'. Rather it contains a 'head' and
48 # list of 'tails' of elements, each of which represents a principal and
51 # A special case of an ABAC credential is a speaks_for credential. Such
52 # a credential is simply an ABAC credential in form, but has a single
53 # tail and fixed role 'speaks_for'. In ABAC notation, it asserts
54 # AGENT.speaks_for(AGENT)<-CLIENT, or "AGENT asserts that CLIENT may speak
55 # for AGENT". The AGENT in this case is the head and the CLIENT is the
56 # tail and 'speaks_for_AGENT' is the role on the head. These speaks-for
57 # Credentials are used to allow a tool to 'speak as' itself but be recognized
58 # as speaking for an individual and be authorized to the rights of that
59 # individual and not to the rights of the tool itself.
61 # For more detail on the semantics and syntax and expected usage patterns
62 # of ABAC credentials, see http://groups.geni.net/geni/wiki/TIEDABACCredential.
65 # An ABAC element contains a principal (keyid and optional mnemonic)
66 # and optional role and linking_role element
68 def __init__(self, principal_keyid, principal_mnemonic=None, \
69 role=None, linking_role=None):
70 self._principal_keyid = principal_keyid
71 self._principal_mnemonic = principal_mnemonic
73 self._linking_role = linking_role
75 def get_principal_keyid(self): return self._principal_keyid
76 def get_principal_mnemonic(self): return self._principal_mnemonic
77 def get_role(self): return self._role
78 def get_linking_role(self): return self._linking_role
81 ret = self._principal_keyid
82 if self._principal_mnemonic:
83 ret = "%s (%s)" % (self._principal_mnemonic, self._principal_keyid)
84 if self._linking_role:
85 ret += ".%s" % self._linking_role
87 ret += ".%s" % self._role
90 # Subclass of Credential for handling ABAC credentials
91 # They have a different cred_type (geni_abac vs. geni_sfa)
92 # and they have a head and tail and role (as opposed to privileges)
93 class ABACCredential(Credential):
95 ABAC_CREDENTIAL_TYPE = 'geni_abac'
97 def __init__(self, create=False, subject=None,
98 string=None, filename=None):
99 self.head = None # An ABACElemenet
100 self.tails = [] # List of ABACElements
101 super(ABACCredential, self).__init__(create=create,
105 self.cred_type = ABACCredential.ABAC_CREDENTIAL_TYPE
112 def get_tails(self) :
113 if len(self.tails) == 0:
118 super(ABACCredential, self).decode()
119 # Pull out the ABAC-specific info
120 doc = parseString(self.xml)
121 rt0s = doc.getElementsByTagName('rt0')
123 raise CredentialNotVerifiable("ABAC credential had no rt0 element")
125 heads = self._get_abac_elements(rt0_root, 'head')
127 raise CredentialNotVerifiable("ABAC credential should have exactly 1 head element, had %d" % len(heads))
130 self.tails = self._get_abac_elements(rt0_root, 'tail')
132 def _get_abac_elements(self, root, label):
134 elements = root.getElementsByTagName(label)
136 keyids = elt.getElementsByTagName('keyid')
138 raise CredentialNotVerifiable("ABAC credential element '%s' should have exactly 1 keyid, had %d." % (label, len(keyids)))
139 keyid_elt = keyids[0]
140 keyid = keyid_elt.childNodes[0].nodeValue.strip()
143 mnemonic_elts = elt.getElementsByTagName('mnemonic')
144 if len(mnemonic_elts) > 0:
145 mnemonic = mnemonic_elts[0].childNodes[0].nodeValue.strip()
148 role_elts = elt.getElementsByTagName('role')
149 if len(role_elts) > 0:
150 role = role_elts[0].childNodes[0].nodeValue.strip()
153 linking_role_elts = elt.getElementsByTagName('linking_role')
154 if len(linking_role_elts) > 0:
155 linking_role = linking_role_elts[0].childNodes[0].nodeValue.strip()
157 abac_element = ABACElement(keyid, mnemonic, role, linking_role)
158 abac_elements.append(abac_element)
162 def dump_string(self, dump_parents=False, show_xml=False):
163 result = "ABAC Credential\n"
164 filename=self.get_filename()
165 if filename: result += "Filename %s\n"%filename
167 result += "\texpiration: %s \n" % self.expiration.strftime(SFATIME_FORMAT)
169 result += "\tHead: %s\n" % self.get_head()
170 for tail in self.get_tails():
171 result += "\tTail: %s\n" % tail
172 if self.get_signature():
173 result += " gidIssuer:\n"
174 result += self.get_signature().get_issuer_gid().dump_string(8, dump_parents)
175 if show_xml and HAVELXML:
177 tree = etree.parse(StringIO(self.xml))
178 aside = etree.tostring(tree, pretty_print=True)
179 result += "\nXML:\n\n"
181 result += "\nEnd XML\n"
184 print("exc. Credential.dump_string / XML")
185 traceback.print_exc()
188 # sounds like this should be __repr__ instead ??
189 # Produce the ABAC assertion. Something like [ABAC cred: Me.role<-You] or similar
190 def pretty_cred(self):
191 result = "[ABAC cred: " + str(self.get_head())
192 for tail in self.get_tails():
193 result += "<-%s" % str(tail)
197 def createABACElement(self, doc, tagName, abacObj):
198 kid = abacObj.get_principal_keyid()
199 mnem = abacObj.get_principal_mnemonic() # may be None
200 role = abacObj.get_role() # may be None
201 link = abacObj.get_linking_role() # may be None
202 ele = doc.createElement(tagName)
203 prin = doc.createElement('ABACprincipal')
204 ele.appendChild(prin)
205 append_sub(doc, prin, "keyid", kid)
207 append_sub(doc, prin, "mnemonic", mnem)
209 append_sub(doc, ele, "role", role)
211 append_sub(doc, ele, "linking_role", link)
215 # Encode the attributes of the credential into an XML string
216 # This should be done immediately before signing the credential.
218 # In general, a signed credential obtained externally should
219 # not be changed else the signature is no longer valid. So, once
220 # you have loaded an existing signed credential, do not call encode() or sign() on it.
223 # Create the XML document
225 signed_cred = doc.createElement("signed-credential")
228 # Note that credential/policy.xsd are really the PG schemas
230 # Note that delegation of credentials between the 2 only really works
231 # cause those schemas are identical.
232 # Also note these PG schemas talk about PG tickets and CM policies.
233 signed_cred.setAttribute("xmlns:xsi", "http://www.w3.org/2001/XMLSchema-instance")
234 signed_cred.setAttribute("xsi:noNamespaceSchemaLocation", "http://www.geni.net/resources/credential/2/credential.xsd")
235 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")
237 # PG says for those last 2:
238 # signed_cred.setAttribute("xsi:noNamespaceSchemaLocation", "http://www.protogeni.net/resources/credential/credential.xsd")
239 # 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")
241 doc.appendChild(signed_cred)
243 # Fill in the <credential> bit
244 cred = doc.createElement("credential")
245 cred.setAttribute("xml:id", self.get_refid())
246 signed_cred.appendChild(cred)
247 append_sub(doc, cred, "type", "abac")
250 append_sub(doc, cred, "serial", "8")
251 append_sub(doc, cred, "owner_gid", '')
252 append_sub(doc, cred, "owner_urn", '')
253 append_sub(doc, cred, "target_gid", '')
254 append_sub(doc, cred, "target_urn", '')
255 append_sub(doc, cred, "uuid", "")
257 if not self.expiration:
258 self.set_expiration(datetime.datetime.utcnow() + datetime.timedelta(seconds=DEFAULT_CREDENTIAL_LIFETIME))
259 self.expiration = self.expiration.replace(microsecond=0)
260 if self.expiration.tzinfo is not None and self.expiration.tzinfo.utcoffset(self.expiration) is not None:
261 # TZ aware. Make sure it is UTC
262 self.expiration = self.expiration.astimezone(tz.tzutc())
263 append_sub(doc, cred, "expires", self.expiration.strftime(SFATIME_FORMAT)) # RFC3339
265 abac = doc.createElement("abac")
266 rt0 = doc.createElement("rt0")
267 abac.appendChild(rt0)
268 cred.appendChild(abac)
269 append_sub(doc, rt0, "version", "1.1")
270 head = self.createABACElement(doc, "head", self.get_head())
271 rt0.appendChild(head)
272 for tail in self.get_tails():
273 tailEle = self.createABACElement(doc, "tail", tail)
274 rt0.appendChild(tailEle)
276 # Create the <signatures> tag
277 signatures = doc.createElement("signatures")
278 signed_cred.appendChild(signatures)
280 # Get the finished product
281 self.xml = doc.toxml("utf-8")