mirror of
https://github.com/fail2ban/fail2ban.git
synced 2026-03-11 08:55:31 +00:00
941a2b6c82
implemented caching functionality for same substitutions inside replaceTag: very actual and extreme performance growth (up to 1000 times) for ban/unban because too slow substituteRecursiveTags by several tags and many includes, but totally unnecessary as long as parameters are not changing;
566 lines
15 KiB
Python
566 lines
15 KiB
Python
# emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: t -*-
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# vi: set ft=python sts=4 ts=4 sw=4 noet :
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# This file is part of Fail2Ban.
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#
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# Fail2Ban is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# Fail2Ban 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 General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Fail2Ban; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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__author__ = "Cyril Jaquier and Fail2Ban Contributors"
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__copyright__ = "Copyright (c) 2004 Cyril Jaquier, 2011-2012 Yaroslav Halchenko"
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__license__ = "GPL"
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import logging
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import os
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import re
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import signal
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import subprocess
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import tempfile
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import threading
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import time
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from abc import ABCMeta
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from collections import MutableMapping
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from .ipdns import asip
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from .mytime import MyTime
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from .utils import Utils
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from ..helpers import getLogger
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# Gets the instance of the logger.
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logSys = getLogger(__name__)
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# Create a lock for running system commands
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_cmd_lock = threading.Lock()
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# Todo: make it configurable resp. automatically set, ex.: `[ -f /proc/net/if_inet6 ] && echo 'yes' || echo 'no'`:
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allowed_ipv6 = True
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# compiled RE for tag name (replacement name)
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TAG_CRE = re.compile(r'<([^ <>]+)>')
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class CallingMap(MutableMapping):
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"""A Mapping type which returns the result of callable values.
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`CallingMap` behaves similar to a standard python dictionary,
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with the exception that any values which are callable, are called
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and the result is returned as the value.
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No error handling is in place, such that any errors raised in the
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callable will raised as usual.
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Actual dictionary is stored in property `data`, and can be accessed
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to obtain original callable values.
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Attributes
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----------
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data : dict
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The dictionary data which can be accessed to obtain items uncalled
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"""
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def __init__(self, *args, **kwargs):
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self.data = dict(*args, **kwargs)
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def __repr__(self):
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return "%s(%r)" % (self.__class__.__name__, self.data)
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def __getitem__(self, key):
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value = self.data[key]
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if callable(value):
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return value()
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else:
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return value
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def __setitem__(self, key, value):
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self.data[key] = value
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def __delitem__(self, key):
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del self.data[key]
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def __iter__(self):
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return iter(self.data)
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def __len__(self):
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return len(self.data)
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def copy(self):
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return self.__class__(self.data.copy())
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class ActionBase(object):
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"""An abstract base class for actions in Fail2Ban.
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Action Base is a base definition of what methods need to be in
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place to create a Python based action for Fail2Ban. This class can
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be inherited from to ease implementation.
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Required methods:
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- __init__(jail, name)
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- start()
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- stop()
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- ban(aInfo)
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- unban(aInfo)
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Called when action is created, but before the jail/actions is
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started. This should carry out necessary methods to initialise
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the action but not "start" the action.
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Parameters
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----------
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jail : Jail
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The jail in which the action belongs to.
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name : str
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Name assigned to the action.
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Notes
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-----
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Any additional arguments specified in `jail.conf` or passed
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via `fail2ban-client` will be passed as keyword arguments.
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"""
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__metaclass__ = ABCMeta
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@classmethod
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def __subclasshook__(cls, C):
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required = (
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"start",
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"stop",
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"ban",
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"unban",
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)
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for method in required:
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if not callable(getattr(C, method, None)):
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return False
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return True
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def __init__(self, jail, name):
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self._jail = jail
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self._name = name
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self._logSys = getLogger("fail2ban.%s" % self.__class__.__name__)
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def start(self):
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"""Executed when the jail/action is started.
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"""
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pass
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def stop(self):
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"""Executed when the jail/action is stopped.
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"""
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pass
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def ban(self, aInfo):
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"""Executed when a ban occurs.
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Parameters
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----------
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aInfo : dict
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Dictionary which includes information in relation to
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the ban.
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"""
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pass
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def unban(self, aInfo):
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"""Executed when a ban expires.
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Parameters
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----------
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aInfo : dict
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Dictionary which includes information in relation to
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the ban.
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"""
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pass
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class CommandAction(ActionBase):
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"""A action which executes OS shell commands.
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This is the default type of action which Fail2Ban uses.
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Default sets all commands for actions as empty string, such
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no command is executed.
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Parameters
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----------
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jail : Jail
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The jail in which the action belongs to.
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name : str
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Name assigned to the action.
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Attributes
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----------
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actionban
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actionstart
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actionstop
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actionunban
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timeout
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"""
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_escapedTags = set(('matches', 'ipmatches', 'ipjailmatches'))
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timeout = 60
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## Command executed in order to initialize the system.
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actionstart = ''
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## Command executed when an IP address gets banned.
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actionban = ''
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## Command executed when an IP address gets removed.
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actionunban = ''
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## Command executed in order to check requirements.
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actioncheck = ''
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## Command executed in order to stop the system.
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actionstop = ''
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def __init__(self, jail, name):
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super(CommandAction, self).__init__(jail, name)
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self.__properties = None
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self.__substCache = {}
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self._logSys.debug("Created %s" % self.__class__)
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@classmethod
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def __subclasshook__(cls, C):
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return NotImplemented # Standard checks
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def __setattr__(self, name, value):
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if not name.startswith('_') and not callable(value):
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# special case for some pasrameters:
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if name == 'timeout':
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value = MyTime.str2seconds(value)
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# parameters changed - clear properties and substitution cache:
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self.__properties = None
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self.__substCache.clear()
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#self._logSys.debug("Set action %r %s = %r", self._name, name, value)
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self._logSys.debug(" Set %s = %r", name, value)
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# set:
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self.__dict__[name] = value
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@property
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def _properties(self):
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"""A dictionary of the actions properties.
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This is used to subsitute "tags" in the commands.
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"""
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# if we have a properties - return it:
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if self.__properties is not None:
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return self.__properties
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# otherwise retrieve:
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self.__properties = dict(
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(key, getattr(self, key))
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for key in dir(self)
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if not key.startswith("_") and not callable(getattr(self, key)))
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#
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return self.__properties
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@property
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def _substCache(self):
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return self.__substCache
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def start(self):
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"""Executes the "actionstart" command.
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Replace the tags in the action command with actions properties
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and executes the resulting command.
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"""
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# check valid tags in properties (raises ValueError if self recursion, etc.):
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try:
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# common (resp. ipv4):
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startCmd = self.replaceTag('<actionstart>', self._properties,
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conditional='family=inet4', cache=self.__substCache)
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res = self.executeCmd(startCmd, self.timeout)
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# start ipv6 actions if available:
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if allowed_ipv6:
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startCmd6 = self.replaceTag('<actionstart>', self._properties,
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conditional='family=inet6', cache=self.__substCache)
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if startCmd6 != startCmd:
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res &= self.executeCmd(startCmd6, self.timeout)
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if not res:
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raise RuntimeError("Error starting action %s/%s" % (self._jail, self._name,))
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except ValueError, e:
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raise RuntimeError("Error starting action %s/%s: %r" % (self._jail, self._name, e))
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def ban(self, aInfo):
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"""Executes the "actionban" command.
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Replaces the tags in the action command with actions properties
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and ban information, and executes the resulting command.
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Parameters
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----------
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aInfo : dict
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Dictionary which includes information in relation to
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the ban.
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"""
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if not self._processCmd('<actionban>', aInfo):
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raise RuntimeError("Error banning %(ip)s" % aInfo)
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def unban(self, aInfo):
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"""Executes the "actionunban" command.
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Replaces the tags in the action command with actions properties
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and ban information, and executes the resulting command.
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Parameters
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----------
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aInfo : dict
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Dictionary which includes information in relation to
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the ban.
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"""
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if not self._processCmd('<actionunban>', aInfo):
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raise RuntimeError("Error unbanning %(ip)s" % aInfo)
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def stop(self):
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"""Executes the "actionstop" command.
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Replaces the tags in the action command with actions properties
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and executes the resulting command.
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"""
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# common (resp. ipv4):
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stopCmd = self.replaceTag('<actionstop>', self._properties,
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conditional='family=inet4', cache=self.__substCache)
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res = self.executeCmd(stopCmd, self.timeout)
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# ipv6 actions if available:
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if allowed_ipv6:
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stopCmd6 = self.replaceTag('<actionstop>', self._properties,
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conditional='family=inet6', cache=self.__substCache)
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if stopCmd6 != stopCmd:
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res &= self.executeCmd(stopCmd6, self.timeout)
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if not res:
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raise RuntimeError("Error stopping action")
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@classmethod
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def substituteRecursiveTags(cls, inptags, conditional=''):
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"""Sort out tag definitions within other tags.
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Since v.0.9.2 supports embedded interpolation (see test cases for examples).
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so: becomes:
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a = 3 a = 3
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b = <a>_3 b = 3_3
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Parameters
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----------
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inptags : dict
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Dictionary of tags(keys) and their values.
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Returns
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-------
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dict
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Dictionary of tags(keys) and their values, with tags
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within the values recursively replaced.
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"""
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# copy return tags dict to prevent modifying of inptags:
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tags = inptags.copy()
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t = TAG_CRE
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# repeat substitution while embedded-recursive (repFlag is True)
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while True:
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repFlag = False
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# substitute each value:
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for tag in tags.iterkeys():
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if tag in cls._escapedTags:
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# Escaped so won't match
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continue
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value = str(tags[tag])
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# search and replace all tags within value, that can be interpolated using other tags:
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m = t.search(value)
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done = []
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#logSys.log(5, 'TAG: %s, value: %s' % (tag, value))
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while m:
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found_tag = m.group(1)
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#logSys.log(5, 'found: %s' % found_tag)
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if found_tag == tag or found_tag in done:
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# recursive definitions are bad
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#logSys.log(5, 'recursion fail tag: %s value: %s' % (tag, value) )
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raise ValueError(
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"properties contain self referencing definitions "
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"and cannot be resolved, fail tag: %s value: %s" % (tag, value))
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repl = None
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if found_tag not in cls._escapedTags:
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repl = tags.get(found_tag + '?' + conditional)
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if repl is None:
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repl = tags.get(found_tag)
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if repl is None:
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# Escaped or missing tags - just continue on searching after end of match
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# Missing tags are ok - cInfo can contain aInfo elements like <HOST> and valid shell
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# constructs like <STDIN>.
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m = t.search(value, m.end())
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continue
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value = value.replace('<%s>' % found_tag, repl)
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#logSys.log(5, 'value now: %s' % value)
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done.append(found_tag)
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m = t.search(value, m.start())
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#logSys.log(5, 'TAG: %s, newvalue: %s' % (tag, value))
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# was substituted?
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if tags[tag] != value:
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# check still contains any tag - should be repeated (possible embedded-recursive substitution):
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if t.search(value):
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repFlag = True
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tags[tag] = value
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if not repFlag:
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break
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return tags
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@staticmethod
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def escapeTag(value):
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"""Escape characters which may be used for command injection.
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Parameters
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----------
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value : str
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A string of which characters will be escaped.
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Returns
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-------
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str
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`value` with certain characters escaped.
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Notes
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-----
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The following characters are escaped::
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\\#&;`|*?~<>^()[]{}$'"
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"""
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for c in '\\#&;`|*?~<>^()[]{}$\'"':
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if c in value:
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value = value.replace(c, '\\' + c)
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return value
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@classmethod
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def replaceTag(cls, query, aInfo, conditional='', cache=None):
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"""Replaces tags in `query` with property values.
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Parameters
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----------
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query : str
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String with tags.
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aInfo : dict
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Tags(keys) and associated values for substitution in query.
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Returns
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-------
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str
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`query` string with tags replaced.
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"""
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# use cache if allowed:
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if cache is not None:
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ckey = (query, conditional)
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string = cache.get(ckey)
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if string is not None:
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return string
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# replace:
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string = query
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aInfo = cls.substituteRecursiveTags(aInfo, conditional)
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for tag in aInfo:
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if "<%s>" % tag in query:
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value = aInfo.get(tag + '?' + conditional)
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if value is None:
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value = aInfo.get(tag)
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value = str(value) # assure string
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if tag in cls._escapedTags:
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# That one needs to be escaped since its content is
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# out of our control
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value = cls.escapeTag(value)
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string = string.replace('<' + tag + '>', value)
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# New line, space
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string = reduce(lambda s, kv: s.replace(*kv), (("<br>", '\n'), ("<sp>", " ")), string)
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# cache if properties:
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if cache is not None:
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cache[ckey] = string
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#
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return string
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def _processCmd(self, cmd, aInfo=None, conditional=''):
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"""Executes a command with preliminary checks and substitutions.
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Before executing any commands, executes the "check" command first
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in order to check if pre-requirements are met. If this check fails,
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it tries to restore a sane environment before executing the real
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command.
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Parameters
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----------
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cmd : str
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The command to execute.
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aInfo : dictionary
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Dynamic properties.
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Returns
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-------
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bool
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True if the command succeeded.
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"""
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if cmd == "":
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self._logSys.debug("Nothing to do")
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return True
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# conditional corresponding family of the given ip:
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if conditional == '':
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conditional = 'family=inet4'
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if allowed_ipv6:
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try:
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ip = aInfo["ip"]
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if ip and asip(ip).isIPv6:
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conditional = 'family=inet6'
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except KeyError:
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pass
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checkCmd = self.replaceTag('<actioncheck>', self._properties,
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conditional=conditional, cache=self.__substCache)
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if not self.executeCmd(checkCmd, self.timeout):
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self._logSys.error(
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"Invariant check failed. Trying to restore a sane environment")
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self.stop()
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self.start()
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if not self.executeCmd(checkCmd, self.timeout):
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self._logSys.critical("Unable to restore environment")
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return False
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# Replace static fields
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realCmd = self.replaceTag(cmd, self._properties,
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conditional=conditional, cache=self.__substCache)
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# Replace tags
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if aInfo is not None:
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realCmd = self.replaceTag(realCmd, aInfo, conditional=conditional)
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else:
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realCmd = cmd
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return self.executeCmd(realCmd, self.timeout)
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@staticmethod
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def executeCmd(realCmd, timeout=60):
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"""Executes a command.
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Parameters
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----------
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realCmd : str
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The command to execute.
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timeout : int
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The time out in seconds for the command.
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Returns
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-------
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bool
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True if the command succeeded.
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Raises
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------
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OSError
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If command fails to be executed.
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RuntimeError
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If command execution times out.
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"""
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logSys.debug(realCmd)
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if not realCmd:
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logSys.debug("Nothing to do")
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return True
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_cmd_lock.acquire()
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try:
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return Utils.executeCmd(realCmd, timeout, shell=True, output=False)
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finally:
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_cmd_lock.release()
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