358 lines
14 KiB
Python
358 lines
14 KiB
Python
"""
|
|
Scyther : An automatic verifier for security protocols.
|
|
Copyright (C) 2007-2013 Cas Cremers
|
|
|
|
This program is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU General Public License
|
|
as published by the Free Software Foundation; either version 2
|
|
of the License, or (at your option) any later version.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
"""
|
|
|
|
#
|
|
# XMLReader
|
|
#
|
|
# Note:
|
|
# This requires python elementtree to work
|
|
# See: http://effbot.org/zone/element-index.htm
|
|
#
|
|
# On Fedora Core you can install this by installing the python-elementtree rpm
|
|
# Things will be a lot faster and consume less memory if you install the
|
|
# cElementTree module
|
|
#
|
|
# In python 2.5 cElementTree is in the core, so you don't need to install
|
|
# extra packages
|
|
#
|
|
|
|
import sys
|
|
|
|
# Check for cElementTree presence. Otherwise use ElementTree.
|
|
useiter = True
|
|
try:
|
|
# python 2.5 has cElementTree in the core
|
|
import xml.etree.cElementTree as cElementTree
|
|
except:
|
|
# try the old way
|
|
try:
|
|
import cElementTree
|
|
except ImportError:
|
|
useiter = False
|
|
try:
|
|
from elementtree import ElementTree
|
|
except ImportError:
|
|
print """
|
|
ERROR:
|
|
|
|
Could not locate either the [elementtree] or the [cElementTree] package.
|
|
Please install one of them in order to work with the Scyther python interface.
|
|
The [cElementTree] packages can be found at http://effbot.org/zone/celementtree.htm
|
|
|
|
Note that you can still use the Scyther binaries in the 'Bin' directory.
|
|
"""
|
|
sys.exit(1)
|
|
|
|
## Simply pick cElementTree
|
|
#import cElementTree
|
|
## Simply pick ElementTree
|
|
#useiter = False
|
|
#from elementtree import ElementTree
|
|
|
|
import Term
|
|
import Attack
|
|
import Trace
|
|
import Claim
|
|
|
|
class XMLReader(object):
|
|
|
|
def __init__ (self):
|
|
self.varlist = []
|
|
pass
|
|
|
|
def readXML(self, input):
|
|
# Use iter parse when possble so we can clear the attack after reading
|
|
# it in order to preserve memory (this requires cElementTree)
|
|
|
|
attackbuffer = []
|
|
claims = []
|
|
|
|
if useiter:
|
|
parser = cElementTree.iterparse(input)
|
|
else:
|
|
parser = ElementTree.parse(input).findall('*')
|
|
|
|
for elem in parser:
|
|
# The iter parser receives the input in tuples (event and element)
|
|
# we only need the event
|
|
if useiter:
|
|
elem = elem[1]
|
|
|
|
if elem.tag == 'state':
|
|
attack = self.readAttack(elem)
|
|
attackbuffer.append(attack)
|
|
if useiter:
|
|
elem.clear()
|
|
|
|
if elem.tag == 'claimstatus':
|
|
claim = self.readClaim(elem)
|
|
claim.attacks = attackbuffer
|
|
claims.append(claim)
|
|
|
|
# link to parent
|
|
for attack in claim.attacks:
|
|
attack.claim = claim
|
|
|
|
attackbuffer = []
|
|
if useiter:
|
|
elem.clear()
|
|
|
|
return claims
|
|
|
|
# Read a term from XML
|
|
def readTerm(self,xml):
|
|
# If xml is None the term should also be none
|
|
if xml == None:
|
|
return None
|
|
# If this is a term variable read it directly
|
|
if (xml.tag in ('tuple','const','apply','encrypt','var')):
|
|
return self.readSubTerm(xml)
|
|
# Otherwise read from it's first child
|
|
children = xml.getchildren()
|
|
assert(len(children) == 1)
|
|
return self.readSubTerm(children[0])
|
|
|
|
def readSubTerm(self, tag):
|
|
if tag.tag == 'tuple':
|
|
return Term.TermTuple(self.readTerm(tag.find('op1')),self.readTerm(tag.find('op2')))
|
|
elif tag.tag == 'const':
|
|
return Term.TermConstant(tag.text)
|
|
elif tag.tag == 'apply':
|
|
return Term.TermApply(self.readTerm(tag.find('function')),self.readTerm(tag.find('arg')))
|
|
elif tag.tag == 'encrypt':
|
|
return Term.TermEncrypt(self.readTerm(tag.find('op')),self.readTerm(tag.find('key')))
|
|
elif tag.tag == 'var':
|
|
name = Term.TermConstant(tag.get('name'))
|
|
# Instantiate this variable if possible (note this list is empty while reading
|
|
# the variables section of the XML file)
|
|
for inst in self.varlist:
|
|
if inst.name == name:
|
|
return inst
|
|
# If it is not instantiated in varlist, just return a variable with this name and no
|
|
# value
|
|
return Term.TermVariable(name,None)
|
|
else:
|
|
raise Term.InvalidTerm, "Invalid term type in XML: %s" % tag.tag
|
|
|
|
def readEvent(self,xml):
|
|
label = self.readTerm(xml.find('label'))
|
|
follows = xml.findall('follows')
|
|
followlist = []
|
|
for follow in follows:
|
|
follow = follow.find('after')
|
|
if follow == None:
|
|
# Ignore follow definitions that do not contain after
|
|
continue
|
|
follow = (int(follow.get('run')),int(follow.get('index')))
|
|
followlist.append(follow)
|
|
|
|
(etype,index) = (xml.get('type'),int(xml.get('index')))
|
|
if etype in ('send','read','recv'):
|
|
fr = self.readTerm(xml.find('from'))
|
|
to = self.readTerm(xml.find('to'))
|
|
message = self.readTerm(xml.find('message'))
|
|
if (etype == 'send'):
|
|
return Trace.EventSend(index,label,followlist,fr,to,message)
|
|
else:
|
|
return Trace.EventRead(index,label,followlist,fr,to,message)
|
|
elif xml.get('type') == 'claim':
|
|
role = self.readTerm(xml.find('role'))
|
|
etype = self.readTerm(xml.find('type'))
|
|
argument = self.readTerm(xml.find('argument'))
|
|
# Freshness claims are implemented as Empty claims with
|
|
# (Fresh,Value) as arguments
|
|
try:
|
|
if etype == 'Empty' and argument[0] == 'Fresh':
|
|
etype = Term.TermConstant('Fresh')
|
|
argument = argument[1]
|
|
elif etype == 'Empty' and argument[0] == 'Compromised':
|
|
etype = Term.TermConstant('Compromised')
|
|
argument = argument[1]
|
|
except:
|
|
pass
|
|
return Trace.EventClaim(index,label,followlist,role,etype,argument)
|
|
else:
|
|
raise Trace.InvalidAction, "Invalid action in XML: %s" % (xml.get('type'))
|
|
|
|
def readRun(self,xml):
|
|
assert(xml.tag == 'run')
|
|
run = Trace.Run()
|
|
run.id = int(xml.find('runid').text)
|
|
# TODO why is protocol name a term??
|
|
run.protocol = str(self.readTerm(xml.find('protocol')))
|
|
run.intruder = xml.find('protocol').get('intruder') == 'true'
|
|
run.role = xml.find('rolename').text
|
|
for role in xml.find('roleagents'):
|
|
name = role.find('rolename').text
|
|
agent = self.readTerm(role.find('agent'))
|
|
run.roleAgents[name] = agent
|
|
for eventxml in xml.find('eventlist'):
|
|
action = self.readEvent(eventxml)
|
|
action.run = run
|
|
run.eventList.append(action)
|
|
for variable in xml.find('variables'):
|
|
# Read the variables one by one
|
|
assert(variable.tag == 'variable')
|
|
var = self.readTerm(variable.find('name').find('term'))
|
|
var.types = self.readTypeList(variable.find('name'))
|
|
|
|
substxml = variable.find('substitution')
|
|
# Read substitution if present
|
|
if substxml != None:
|
|
subst = self.readTerm(substxml.find('term'))
|
|
subst.types = self.readTypeList(substxml)
|
|
newvar = Term.TermVariable(var.name,subst)
|
|
newvar.types = var.types
|
|
var = newvar
|
|
|
|
run.variables.append(var)
|
|
return run
|
|
|
|
# Read protocol description for a certain role
|
|
def readRoleDescr(self,xml):
|
|
assert(xml.tag == 'role')
|
|
run = Trace.Run()
|
|
# We will need the last label later on to see if a
|
|
# run is complete
|
|
run.lastLabel = None
|
|
run.role = xml.find('rolename').text
|
|
for eventxml in xml.find('eventlist'):
|
|
action = self.readEvent(eventxml)
|
|
action.run = run
|
|
run.eventList.append(action)
|
|
run.lastLabel = action.label
|
|
return run
|
|
|
|
def readTypeList(self,xml):
|
|
result = []
|
|
vartypes = xml.find('type').find('termlist')
|
|
for vartype in vartypes:
|
|
# We will assume that types are simple strings
|
|
result.append(str(self.readTerm(vartype)))
|
|
return result
|
|
|
|
def readClaim(self, xml):
|
|
claim = Claim.Claim()
|
|
for event in xml.getchildren():
|
|
if event.tag == 'claimtype':
|
|
claim.claimtype = self.readTerm(event)
|
|
elif event.tag == 'label':
|
|
# We store the full protocol,label construct for
|
|
# consistency with the technical parts, so it is left to
|
|
# the __str__ of claim to select the right element
|
|
claim.label = self.readTerm(event)
|
|
elif event.tag == 'protocol':
|
|
claim.protocol = self.readTerm(event)
|
|
elif event.tag == 'role':
|
|
claim.role = self.readTerm(event)
|
|
elif event.tag == 'parameter':
|
|
claim.parameter = self.readTerm(event)
|
|
|
|
elif event.tag == 'failed':
|
|
claim.failed = int(event.text)
|
|
elif event.tag == 'count':
|
|
claim.count = int(event.text)
|
|
elif event.tag == 'states':
|
|
claim.states = int(event.text)
|
|
|
|
elif event.tag == 'complete':
|
|
claim.complete = True
|
|
elif event.tag == 'timebound':
|
|
claim.timebound = True
|
|
else:
|
|
print >>sys.stderr,"Warning unknown tag in claim: %s" % claim.tag
|
|
|
|
claim.analyze()
|
|
return claim
|
|
|
|
def readAttack(self, xml):
|
|
self.varlist = []
|
|
attack = Attack.Attack()
|
|
attack.id = int(xml.get('id'))
|
|
# A state contains 4 direct child nodes:
|
|
# broken, system, variables and semitrace
|
|
# optionally a fifth: dot
|
|
for event in xml.getchildren():
|
|
if event.tag == 'broken':
|
|
attack.broken.append((self.readTerm(event.find('claim')),
|
|
self.readTerm(event.find('label'))))
|
|
elif event.tag == 'system':
|
|
attack.match = int(event.find('match').text)
|
|
for term in event.find('commandline'):
|
|
if attack.commandline != '':
|
|
attack.commandline += ' '
|
|
attack.commandline += term.text
|
|
for term in event.find('untrusted').find('termlist'):
|
|
attack.untrusted.append(str(self.readTerm(term)))
|
|
for term in event.find('initialknowledge').find('termlist'):
|
|
attack.initialKnowledge.append(self.readTerm(term))
|
|
for keypair in event.find('inversekeys'):
|
|
inverse = []
|
|
for term in keypair:
|
|
inverse.append(self.readTerm(term))
|
|
assert(len(inverse) == 0 or len(inverse) == 2)
|
|
attack.inverseKeys.append(inverse)
|
|
# TODO why is protocol name a term??
|
|
for protocolxml in event.findall('protocol'):
|
|
protocol = str(self.readTerm(protocolxml.find('name')))
|
|
descr = Trace.ProtocolDescription(protocol)
|
|
attack.protocoldescr[protocol] = descr
|
|
for rolexml in protocolxml.findall('role'):
|
|
roledescr = self.readRoleDescr(rolexml)
|
|
descr.roledescr[roledescr.role] = roledescr
|
|
|
|
elif event.tag == 'semitrace':
|
|
for runxml in event:
|
|
run = self.readRun(runxml)
|
|
run.attack = attack
|
|
attack.semiTrace.runs.append(run)
|
|
|
|
elif event.tag == 'dot':
|
|
# Apparently Scyther already generated dot output,
|
|
# store
|
|
attack.scytherDot = event.text
|
|
|
|
elif event.tag == 'variables':
|
|
# Read the variables one by one
|
|
for varxml in event:
|
|
if varxml.get('typeflaw') == 'true':
|
|
attack.typeflaws = True
|
|
var = self.readTerm(varxml.find('name').find('term'))
|
|
var.types = self.readTypeList(varxml.find('name'))
|
|
|
|
substxml = varxml.find('substitution')
|
|
# Read substitution if present
|
|
if substxml != None:
|
|
subst = self.readTerm(substxml.find('term'))
|
|
subst.types = self.readTypeList(substxml)
|
|
newvar = Term.TermVariable(var.name,subst)
|
|
newvar.types = var.types
|
|
var = newvar
|
|
|
|
attack.variables.append(var)
|
|
|
|
# When all have been read set self.varlist so that when
|
|
# we read terms in the attacks they can be filled in using
|
|
# this list
|
|
self.varlist = attack.variables
|
|
else:
|
|
print >>sys.stderr,"Warning unknown tag in attack: %s" % event.tag
|
|
return attack
|
|
|