Source code for

# Copyright 2017 The Forseti Security Authors. All rights reserved.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.

"""Rules engine for Blacklist of IP addresses."""
import itertools
import re
import urllib2
import struct
import socket

from collections import namedtuple

from import resource as resource_mod
from import logger
from import base_rules_engine as bre

LOGGER = logger.get_logger(__name__)

[docs]class BlacklistRulesEngine(bre.BaseRulesEngine): """Rules engine for BlacklistRules.""" def __init__(self, rules_file_path, snapshot_timestamp=None): """Initialize. Args: rules_file_path (str): file location of rules snapshot_timestamp (str): timestamp for database. """ super(BlacklistRulesEngine, self).__init__(rules_file_path=rules_file_path) self.rule_book = None
[docs] def build_rule_book(self, global_configs=None): """Build BlacklistRuleBook from rules definition file. Args: global_configs (dict): Global Configs """ self.rule_book = BlacklistRuleBook( self._load_rule_definitions())
[docs] def find_violations(self, instance_network_interface, force_rebuild=False): """Determine whether the networks violates rules. Args: instance_network_interface (list): list of instance_network_interface force_rebuild (bool): set to false to not force a rebuiid Return: list: iterator of all violations """ violations = itertools.chain() if self.rule_book is None or force_rebuild: self.build_rule_book() resource_rules = self.rule_book.get_resource_rules() for rule in resource_rules: violations = itertools.chain(violations, rule.find_violations( instance_network_interface)) return violations
[docs] def add_rules(self, rules): """Add rules to the rule book. Args: rules (dicts): rule definitions """ if self.rule_book is not None: self.rule_book.add_rules(rules)
[docs]class BlacklistRuleBook(bre.BaseRuleBook): """The RuleBook for networks resources.""" def __init__(self, rule_defs=None): """Initialize. Args: rule_defs (dict): The parsed dictionary of rules from the YAML definition file. """ super(BlacklistRuleBook, self).__init__() self.resource_rules_map = {} if not rule_defs: self.rule_defs = {} else: self.rule_defs = rule_defs self.add_rules(rule_defs)
[docs] def add_rules(self, rule_defs): """Add rules to the rule book. Args: rule_defs (dict): rules definitions """ for (i, rule) in enumerate(rule_defs.get('rules', [])): self.add_rule(rule, i)
[docs] def add_rule(self, rule_def, rule_index): """Add a rule to the rule book. Args: rule_def (dict): A dictionary containing rule definition properties. rule_index (int): The index of the rule from the rule definitions. Assigned automatically when the rule book is built. """ ips, nets = self.get_and_parse_blacklist(rule_def.get('url')) rule_def_resource = { 'ips_list': ips, 'nets_list': nets } rule = Rule(rule_blacklist=rule_def.get('blacklist'), rule_index=rule_index, rules=rule_def_resource) resource_rules = self.resource_rules_map.get(rule_index) if not resource_rules: self.resource_rules_map[rule_index] = rule
[docs] def get_resource_rules(self): """Get all the resource rules for (resource, RuleAppliesTo.*). Returns: list: A list of ResourceRules. """ resource_rules = [] for resource_rule in self.resource_rules_map: resource_rules.append(self.resource_rules_map[resource_rule]) return resource_rules
[docs] @staticmethod def get_and_parse_blacklist(url): """Download blacklist and parse it into IPs and netblocks. Args: url (str): url to download blacklist from Returns: lists: first one is IP addresses, second one is network blocks """ data = urllib2.urlopen(url).read() ip_addresses = re.findall(r'^[0-9]+(?:\.[0-9]+){3}$', data, re.M) netblocks = re.findall(r'^[0-9]+(?:\.[0-9]+){0,3}/[0-9]{1,2}$', data, re.M) return ip_addresses, netblocks
[docs]class Rule(object): """The rules class for instance_network_interface.""" def __init__(self, rule_blacklist, rule_index, rules): """Initialize. Args: rule_blacklist (str): Name of the loaded blacklist rule_index (int): The index of the rule from the definitions rules (dict): The resources associated with the rules like the whitelist """ self.rule_blacklist = rule_blacklist self.rule_index = rule_index self.rules = rules
[docs] @staticmethod def address_in_network(ipaddr, net): """ Checks if ip address is in net Args: ipaddr (str): IP address to check net (str): network to check Returns: bool: True if ipaddr in net """ ipaddrb = struct.unpack('!I', socket.inet_aton(ipaddr))[0] netstr, bits = net.split('/') netaddr = struct.unpack('!I', socket.inet_aton(netstr))[0] mask = (0xffffffff << (32 - int(bits))) & 0xffffffff return (ipaddrb & mask) == (netaddr & mask)
[docs] def is_blacklisted(self, ipaddr): """ Checks if ip address is in a blacklist Args: ipaddr (str): IP address to check Returns: bool: True if ipaddr is blacklisted """ if ipaddr: if ipaddr in self.rules['ips_list']: return True for ip_network in self.rules['nets_list']: if self.address_in_network(ipaddr, ip_network): return True return False
[docs] def find_violations(self, instance_network_interface): """Raise violation if the IP is not in the whitelist. Args: instance_network_interface (InstanceNetworkInterface): object Yields: namedtuple: Returns RuleViolation named tuple """ for network_interface in instance_network_interface: network_and_project = r'compute/[a-zA-Z0-9]+/projects/([^/]*).*networks/([^/]*)', project = network = if not network_interface.access_configs: LOGGER.warn('Unable to determine blacklist violation for ' 'network interface: %s, because it doesn\'t ' 'have external internet access.', network_interface.full_name) continue for access_config in network_interface.access_configs: ipaddr = access_config.get('natIP') if self.is_blacklisted(ipaddr): yield self.RuleViolation( resource_name=project, resource_type=resource_mod.ResourceType.INSTANCE, full_name=network_interface.full_name, rule_blacklist=self.rule_blacklist, rule_name=self.rule_blacklist, rule_index=self.rule_index, violation_type='BLACKLIST_VIOLATION', project=project, network=network, ip=access_config.get('natIP'), resource_data=network_interface.as_json())
# Rule violation. # resource_type: string # rule_blacklist: string # rule_name: string # rule_index: int # violation_type: BLACKLIST_VIOLATION # project: string # network: string # ip: string RuleViolation = namedtuple('RuleViolation', ['resource_type', 'full_name', 'resource_name', 'rule_blacklist', 'rule_name', 'rule_index', 'violation_type', 'project', 'network', 'ip', 'resource_data'])