mirror of
https://github.com/SELinuxProject/setools
synced 2025-04-01 14:48:07 +00:00
277 lines
9.3 KiB
Python
277 lines
9.3 KiB
Python
# Copyright 2014-2015, Tresys Technology, LLC
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#
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# This file is part of SETools.
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#
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# SETools is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as
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# published by the Free Software Foundation, either version 2.1 of
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# the License, or (at your option) any later version.
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#
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# SETools is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with SETools. If not, see
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# <http://www.gnu.org/licenses/>.
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#
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from . import policyrep
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class RuleTypeError(Exception):
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"""Exception for using rules with incorrect rule type."""
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pass
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class UnmappedClass(Exception):
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"""Exception for classes that are unmapped"""
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pass
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class UnmappedPermission(Exception):
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"""Exception for permissions that are unmapped"""
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pass
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class PermissionMap(object):
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"""Permission Map for information flow analysis."""
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valid_infoflow_directions = ["r", "w", "b", "n", "u"]
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min_weight = 1
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max_weight = 10
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def __init__(self, permmapfile="/usr/share/setools/perm_map"):
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"""
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Parameter:
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permmapfile The path to the permission map to load.
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"""
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self.load(permmapfile)
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def load(self, permmapfile):
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"""
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Parameter:
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permmapfile The path to the permission map to load.
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"""
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# state machine
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# 1 = read number of classes
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# 2 = read class name and number of perms
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# 3 = read perms
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with open(permmapfile, "r") as fd:
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class_count = 0
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num_classes = 0
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state = 1
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self.permmap = dict()
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for line_num, line in enumerate(fd, start=1):
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entry = line.split()
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if class_count > num_classes:
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break
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if len(entry) == 0 or entry[0][0] == '#':
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continue
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if state == 1:
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try:
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num_classes = int(entry[0])
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except ValueError:
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raise SyntaxError(
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"{0}:{1}:Invalid number of classes: {2}".
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format(permmapfile, line_num, entry[0]))
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if num_classes < 1:
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SyntaxError(
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"{0}:{1}:Number of classes must be 1-32: {2}".
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format(permmapfile, line_num, entry[2]))
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state = 2
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elif state == 2:
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if len(entry) != 3 or entry[0] != "class":
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raise SyntaxError(
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"{0}:{1}:Invalid class declaration: {2}".
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format(permmapfile, line_num, entry))
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class_name = str(entry[1])
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try:
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num_perms = int(entry[2])
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except ValueError:
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raise SyntaxError(
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"{0}:{1}:Invalid number of permissions: {2}".
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format(permmapfile, line_num, entry[2]))
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if num_perms < 1:
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SyntaxError(
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"{0}:{1}:Number of permissions must be 1-32: {2}".
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format(permmapfile, line_num, entry[2]))
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self.permmap[class_name] = dict()
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class_count += 1
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perm_count = 0
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state = 3
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elif state == 3:
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perm_name = entry[0]
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flow_direction = str(entry[1])
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if flow_direction not in self.valid_infoflow_directions:
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raise SyntaxError(
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"{0}:{1}:Invalid information flow direction: {2}".
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format(permmapfile, line_num, entry[1]))
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try:
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weight = int(entry[2])
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except ValueError:
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SyntaxError(
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"{0}:{1}:Invalid permission weight: {2}".
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format(permmapfile, line_num, entry[2]))
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if not self.min_weight <= weight <= self.max_weight:
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SyntaxError(
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"{0}:{1}:Permission weight must be 1-10: {2}".
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format(permmapfile, line_num, entry[2]))
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self.permmap[class_name][perm_name] = {'direction': flow_direction,
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'weight': weight,
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'enabled': True}
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perm_count += 1
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if perm_count >= num_perms:
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state = 2
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def exclude_class(self, class_):
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"""
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Exclude all permissions in an object class for calculating rule weights.
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Parameter:
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class_ The object class to exclude.
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Exceptions:
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UnmappedClass The specified object class is not mapped.
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"""
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classname = str(class_)
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try:
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for perm in self.permmap[classname]:
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self.permmap[classname][perm]['enabled'] = False
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except KeyError:
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raise UnmappedClass("{0} is not mapped.".format(classname))
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def exclude_permission(self, class_, permission):
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"""
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Exclude a permission for calculating rule weights.
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Parameter:
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class_ The object class of the permission.
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permission The permission name to exclude.
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Exceptions:
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UnmappedClass The specified object class is not mapped.
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UnmappedPermission The specified permission is not mapped for the object class.
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"""
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classname = str(class_)
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if classname not in self.permmap:
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raise UnmappedClass("{0} is not mapped.".format(classname))
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try:
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self.permmap[classname][permission]['enabled'] = False
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except KeyError:
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raise UnmappedPermission("{0}:{1} is not mapped.".format(classname, permission))
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def include_class(self, class_):
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"""
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Include all permissions in an object class for calculating rule weights.
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Parameter:
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class_ The object class to include.
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Exceptions:
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UnmappedClass The specified object class is not mapped.
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"""
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classname = str(class_)
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try:
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for perm in self.permmap[classname]:
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self.permmap[classname][perm]['enabled'] = True
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except KeyError:
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raise UnmappedClass("{0} is not mapped.".format(classname))
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def include_permission(self, class_, permission):
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"""
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Include a permission for calculating rule weights.
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Parameter:
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class_ The object class of the permission.
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permission The permission name to include.
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Exceptions:
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UnmappedClass The specified object class is not mapped.
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UnmappedPermission The specified permission is not mapped for the object class.
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"""
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classname = str(class_)
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if classname not in self.permmap:
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raise UnmappedClass("{0} is not mapped.".format(classname))
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try:
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self.permmap[classname][permission]['enabled'] = True
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except KeyError:
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raise UnmappedPermission("{0}:{1} is not mapped.".format(classname, permission))
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def rule_weight(self, rule):
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"""
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Get the type enforcement rule's information flow read and write weights.
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Parameter:
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rule A type enforcement rule.
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Return: Tuple(read_weight, write_weight)
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read_weight The type enforcement rule's read weight.
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write_weight The type enforcement rule's write weight.
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"""
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write_weight = 0
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read_weight = 0
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class_name = str(rule.tclass)
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if rule.ruletype != 'allow':
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raise RuleTypeError("{0} rules cannot be used for calculating a weight".
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format(rule.ruletype))
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if class_name not in self.permmap:
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raise UnmappedClass("{0} is not mapped.".format(class_name))
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# iterate over the permissions and determine the
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# weight of the rule in each direction. The result
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# is the largest-weight permission in each direction
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for perm_name in rule.perms:
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try:
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mapping = self.permmap[class_name][perm_name]
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except KeyError:
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raise UnmappedPermission("{0}:{1} is not mapped.".format(class_name, perm_name))
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if not mapping['enabled']:
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continue
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if mapping['direction'] == "r":
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read_weight = max(read_weight, mapping['weight'])
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elif mapping['direction'] == "w":
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write_weight = max(write_weight, mapping['weight'])
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elif mapping['direction'] == "b":
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read_weight = max(read_weight, mapping['weight'])
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write_weight = max(write_weight, mapping['weight'])
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return (read_weight, write_weight)
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