shell bypass 403
# Authors: Karl MacMillan <kmacmillan@mentalrootkit.com>
#
# Copyright (C) 2006 Red Hat
# see file 'COPYING' for use and warranty information
#
# 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; version 2 only
#
# 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
"""
Classes for representing and manipulating interfaces.
"""
import copy
import itertools
from . import access
from . import refpolicy
from . import objectmodel
from . import matching
from .sepolgeni18n import _
class Param:
"""
Object representing a paramater for an interface.
"""
def __init__(self):
self.__name = ""
self.type = refpolicy.SRC_TYPE
self.obj_classes = refpolicy.IdSet()
self.required = True
def set_name(self, name):
if not access.is_idparam(name):
raise ValueError("Name [%s] is not a param" % name)
self.__name = name
def get_name(self):
return self.__name
name = property(get_name, set_name)
num = property(fget=lambda self: int(self.name[1:]))
def __repr__(self):
return "<sepolgen.policygen.Param instance [%s, %s, %s]>" % \
(self.name, refpolicy.field_to_str[self.type], " ".join(self.obj_classes))
# Helper for extract perms
def __param_insert(name, type, av, params):
ret = 0
if name in params:
p = params[name]
# The entries are identical - we're done
if type == p.type:
return
# Hanldle implicitly typed objects (like process)
if (type == refpolicy.SRC_TYPE or type == refpolicy.TGT_TYPE) and \
(p.type == refpolicy.TGT_TYPE or p.type == refpolicy.SRC_TYPE):
#print name, refpolicy.field_to_str[p.type]
# If the object is not implicitly typed, tell the
# caller there is a likely conflict.
ret = 1
if av:
avobjs = [av.obj_class]
else:
avobjs = []
for obj in itertools.chain(p.obj_classes, avobjs):
if obj in objectmodel.implicitly_typed_objects:
ret = 0
break
# "Promote" to a SRC_TYPE as this is the likely usage.
# We do this even if the above test fails on purpose
# as there is really no sane way to resolve the conflict
# here. The caller can take other actions if needed.
p.type = refpolicy.SRC_TYPE
else:
# There is some conflict - no way to resolve it really
# so we just leave the first entry and tell the caller
# there was a conflict.
ret = 1
else:
p = Param()
p.name = name
p.type = type
params[p.name] = p
if av:
p.obj_classes.add(av.obj_class)
return ret
def av_extract_params(av, params):
"""Extract the paramaters from an access vector.
Extract the paramaters (in the form $N) from an access
vector, storing them as Param objects in a dictionary.
Some attempt is made at resolving conflicts with other
entries in the dict, but if an unresolvable conflict is
found it is reported to the caller.
The goal here is to figure out how interface paramaters are
actually used in the interface - e.g., that $1 is a domain used as
a SRC_TYPE. In general an interface will look like this:
interface(`foo', `
allow $1 foo : file read;
')
This is simple to figure out - $1 is a SRC_TYPE. A few interfaces
are more complex, for example:
interface(`foo_trans',`
domain_auto_trans($1,fingerd_exec_t,fingerd_t)
allow $1 fingerd_t:fd use;
allow fingerd_t $1:fd use;
allow fingerd_t $1:fifo_file rw_file_perms;
allow fingerd_t $1:process sigchld;
')
Here the usage seems ambigious, but it is not. $1 is still domain
and therefore should be returned as a SRC_TYPE.
Returns:
0 - success
1 - conflict found
"""
ret = 0
found_src = False
if access.is_idparam(av.src_type):
if __param_insert(av.src_type, refpolicy.SRC_TYPE, av, params) == 1:
ret = 1
if access.is_idparam(av.tgt_type):
if __param_insert(av.tgt_type, refpolicy.TGT_TYPE, av, params) == 1:
ret = 1
if access.is_idparam(av.obj_class):
if __param_insert(av.obj_class, refpolicy.OBJ_CLASS, av, params) == 1:
ret = 1
for perm in av.perms:
if access.is_idparam(perm):
if __param_insert(perm, PERM) == 1:
ret = 1
return ret
def role_extract_params(role, params):
if access.is_idparam(role.role):
return __param_insert(role.role, refpolicy.ROLE, None, params)
def type_rule_extract_params(rule, params):
def extract_from_set(set, type):
ret = 0
for x in set:
if access.is_idparam(x):
if __param_insert(x, type, None, params):
ret = 1
return ret
ret = 0
if extract_from_set(rule.src_types, refpolicy.SRC_TYPE):
ret = 1
if extract_from_set(rule.tgt_types, refpolicy.TGT_TYPE):
ret = 1
if extract_from_set(rule.obj_classes, refpolicy.OBJ_CLASS):
ret = 1
if access.is_idparam(rule.dest_type):
if __param_insert(rule.dest_type, refpolicy.DEST_TYPE, None, params):
ret = 1
return ret
def ifcall_extract_params(ifcall, params):
ret = 0
for arg in ifcall.args:
if access.is_idparam(arg):
# Assume interface arguments are source types. Fairly safe
# assumption for most interfaces
if __param_insert(arg, refpolicy.SRC_TYPE, None, params):
ret = 1
return ret
class AttributeVector:
def __init__(self):
self.name = ""
self.access = access.AccessVectorSet()
def add_av(self, av):
self.access.add_av(av)
class AttributeSet:
def __init__(self):
self.attributes = { }
def add_attr(self, attr):
self.attributes[attr.name] = attr
def from_file(self, fd):
def parse_attr(line):
fields = line[1:-1].split()
if len(fields) != 2 or fields[0] != "Attribute":
raise SyntaxError("Syntax error Attribute statement %s" % line)
a = AttributeVector()
a.name = fields[1]
return a
a = None
for line in fd:
line = line[:-1]
if line[0] == "[":
if a:
self.add_attr(a)
a = parse_attr(line)
elif a:
l = line.split(",")
av = access.AccessVector(l)
a.add_av(av)
if a:
self.add_attr(a)
class InterfaceVector:
def __init__(self, interface=None, attributes={}):
# Enabled is a loose concept currently - we are essentially
# not enabling interfaces that we can't handle currently.
# See InterfaceVector.add_ifv for more information.
self.enabled = True
self.name = ""
# The access that is enabled by this interface - eventually
# this will include indirect access from typeattribute
# statements.
self.access = access.AccessVectorSet()
# Paramaters are stored in a dictionary (key: param name
# value: Param object).
self.params = { }
if interface:
self.from_interface(interface, attributes)
self.expanded = False
def from_interface(self, interface, attributes={}):
self.name = interface.name
# Add allow rules
for avrule in interface.avrules():
if avrule.rule_type != refpolicy.AVRule.ALLOW:
continue
# Handle some policy bugs
if "dontaudit" in interface.name:
#print "allow rule in interface: %s" % interface
continue
avs = access.avrule_to_access_vectors(avrule)
for av in avs:
self.add_av(av)
# Add typeattribute access
if attributes:
for typeattribute in interface.typeattributes():
for attr in typeattribute.attributes:
if attr not in attributes.attributes:
# print "missing attribute " + attr
continue
attr_vec = attributes.attributes[attr]
for a in attr_vec.access:
av = copy.copy(a)
if av.src_type == attr_vec.name:
av.src_type = typeattribute.type
if av.tgt_type == attr_vec.name:
av.tgt_type = typeattribute.type
self.add_av(av)
# Extract paramaters from roles
for role in interface.roles():
if role_extract_params(role, self.params):
pass
#print "found conflicting role param %s for interface %s" % \
# (role.name, interface.name)
# Extract paramaters from type rules
for rule in interface.typerules():
if type_rule_extract_params(rule, self.params):
pass
#print "found conflicting params in rule %s in interface %s" % \
# (str(rule), interface.name)
for ifcall in interface.interface_calls():
if ifcall_extract_params(ifcall, self.params):
pass
#print "found conflicting params in ifcall %s in interface %s" % \
# (str(ifcall), interface.name)
def add_av(self, av):
if av_extract_params(av, self.params) == 1:
pass
#print "found conflicting perms [%s]" % str(av)
self.access.add_av(av)
def to_string(self):
s = []
s.append("[InterfaceVector %s]" % self.name)
for av in self.access:
s.append(str(av))
return "\n".join(s)
def __str__(self):
return self.__repr__()
def __repr__(self):
return "<InterfaceVector %s:%s>" % (self.name, self.enabled)
class InterfaceSet:
def __init__(self, output=None):
self.interfaces = { }
self.tgt_type_map = { }
self.tgt_type_all = []
self.output = output
def o(self, str):
if self.output:
self.output.write(str + "\n")
def to_file(self, fd):
for iv in sorted(self.interfaces.values(), key=lambda x: x.name):
fd.write("[InterfaceVector %s " % iv.name)
for param in sorted(iv.params.values(), key=lambda x: x.name):
fd.write("%s:%s " % (param.name, refpolicy.field_to_str[param.type]))
fd.write("]\n")
avl = sorted(iv.access.to_list())
for av in avl:
fd.write(",".join(av))
fd.write("\n")
def from_file(self, fd):
def parse_ifv(line):
fields = line[1:-1].split()
if len(fields) < 2 or fields[0] != "InterfaceVector":
raise SyntaxError("Syntax error InterfaceVector statement %s" % line)
ifv = InterfaceVector()
ifv.name = fields[1]
if len(fields) == 2:
return
for field in fields[2:]:
p = field.split(":")
if len(p) != 2:
raise SyntaxError("Invalid param in InterfaceVector statement %s" % line)
param = Param()
param.name = p[0]
param.type = refpolicy.str_to_field[p[1]]
ifv.params[param.name] = param
return ifv
ifv = None
for line in fd:
line = line[:-1]
if line[0] == "[":
if ifv:
self.add_ifv(ifv)
ifv = parse_ifv(line)
elif ifv:
l = line.split(",")
av = access.AccessVector(l)
ifv.add_av(av)
if ifv:
self.add_ifv(ifv)
self.index()
def add_ifv(self, ifv):
self.interfaces[ifv.name] = ifv
def index(self):
for ifv in self.interfaces.values():
tgt_types = set()
for av in ifv.access:
if access.is_idparam(av.tgt_type):
self.tgt_type_all.append(ifv)
tgt_types = set()
break
tgt_types.add(av.tgt_type)
for type in tgt_types:
l = self.tgt_type_map.setdefault(type, [])
l.append(ifv)
def add(self, interface, attributes={}):
ifv = InterfaceVector(interface, attributes)
self.add_ifv(ifv)
def add_headers(self, headers, output=None, attributes={}):
for i in itertools.chain(headers.interfaces(), headers.templates()):
self.add(i, attributes)
self.expand_ifcalls(headers)
self.index()
def map_param(self, id, ifcall):
if access.is_idparam(id):
num = int(id[1:])
if num > len(ifcall.args):
# Tell caller to drop this because it must have
# been generated from an optional param.
return None
else:
arg = ifcall.args[num - 1]
if isinstance(arg, list):
return arg
else:
return [arg]
else:
return [id]
def map_add_av(self, ifv, av, ifcall):
src_types = self.map_param(av.src_type, ifcall)
if src_types is None:
return
tgt_types = self.map_param(av.tgt_type, ifcall)
if tgt_types is None:
return
obj_classes = self.map_param(av.obj_class, ifcall)
if obj_classes is None:
return
new_perms = refpolicy.IdSet()
for perm in av.perms:
p = self.map_param(perm, ifcall)
if p is None:
continue
else:
new_perms.update(p)
if len(new_perms) == 0:
return
for src_type in src_types:
for tgt_type in tgt_types:
for obj_class in obj_classes:
ifv.access.add(src_type, tgt_type, obj_class, new_perms)
def do_expand_ifcalls(self, interface, if_by_name):
# Descend an interface call tree adding the access
# from each interface. This is a depth first walk
# of the tree.
stack = [(interface, None)]
ifv = self.interfaces[interface.name]
ifv.expanded = True
while len(stack) > 0:
cur, cur_ifcall = stack.pop(-1)
cur_ifv = self.interfaces[cur.name]
if cur != interface:
for av in cur_ifv.access:
self.map_add_av(ifv, av, cur_ifcall)
# If we have already fully expanded this interface
# there is no reason to descend further.
if cur_ifv.expanded:
continue
for ifcall in cur.interface_calls():
if ifcall.ifname == interface.name:
self.o(_("Found circular interface class"))
return
try:
newif = if_by_name[ifcall.ifname]
except KeyError:
self.o(_("Missing interface definition for %s" % ifcall.ifname))
continue
stack.append((newif, ifcall))
def expand_ifcalls(self, headers):
# Create a map of interface names to interfaces -
# this mirrors the interface vector map we already
# have.
if_by_name = { }
for i in itertools.chain(headers.interfaces(), headers.templates()):
if_by_name[i.name] = i
for interface in itertools.chain(headers.interfaces(), headers.templates()):
self.do_expand_ifcalls(interface, if_by_name)