fail2ban/server/action.py

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# emacs: -*- mode: python; py-indent-offset: 4; indent-tabs-mode: t -*-
# vi: set ft=python sts=4 ts=4 sw=4 noet :
# This file is part of Fail2Ban.
#
# Fail2Ban 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.
#
# Fail2Ban 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 Fail2Ban; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
__author__ = "Cyril Jaquier and Fail2Ban Contributors"
__copyright__ = "Copyright (c) 2004 Cyril Jaquier, 2011-2012 Yaroslav Halchenko"
__license__ = "GPL"
import logging, os
import threading, re
#from subprocess import call
# Gets the instance of the logger.
logSys = logging.getLogger("fail2ban.actions.action")
# Create a lock for running system commands
_cmd_lock = threading.Lock()
# Some hints on common abnormal exit codes
_RETCODE_HINTS = {
0x7f00: '"Command not found". Make sure that all commands in %(realCmd)r '
'are in the PATH of fail2ban-server process '
'(grep -a PATH= /proc/`pidof -x fail2ban-server`/environ). '
'You may want to start '
'"fail2ban-server -f" separately, initiate it with '
'"fail2ban-client reload" in another shell session and observe if '
'additional informative error messages appear in the terminals.'
}
##
# Execute commands.
#
# This class reads the failures from the Jail queue and decide if an
# action has to be taken. A BanManager take care of the banned IP
# addresses.
class Action:
def __init__(self, name):
self.__name = name
self.__cInfo = dict()
## Command executed in order to initialize the system.
self.__actionStart = ''
## Command executed when an IP address gets banned.
self.__actionBan = ''
## Command executed when an IP address gets removed.
self.__actionUnban = ''
## Command executed in order to check requirements.
self.__actionCheck = ''
## Command executed in order to stop the system.
self.__actionStop = ''
logSys.debug("Created Action")
##
# Sets the action name.
#
# @param name the name of the action
def setName(self, name):
self.__name = name
##
# Returns the action name.
#
# @return the name of the action
def getName(self):
return self.__name
##
# Sets a "CInfo".
#
# CInfo are statically defined properties. They can be definied by
# the user and are used to set e-mail addresses, port, host or
# anything that should not change during the life of the server.
#
# @param key the property name
# @param value the property value
def setCInfo(self, key, value):
self.__cInfo[key] = value
##
# Returns a "CInfo".
#
# @param key the property name
def getCInfo(self, key):
return self.__cInfo[key]
##
# Removes a "CInfo".
#
# @param key the property name
def delCInfo(self, key):
del self.__cInfo[key]
##
# Set the "start" command.
#
# @param value the command
def setActionStart(self, value):
self.__actionStart = value
logSys.debug("Set actionStart = %s" % value)
##
# Get the "start" command.
#
# @return the command
def getActionStart(self):
return self.__actionStart
##
# Executes the action "start" command.
#
# Replaces the tags in the action command with value of "cInfo"
# and executes the resulting command.
#
# @return True if the command succeeded
def execActionStart(self):
if self.__cInfo:
if not Action.substituteRecursiveTags(self.__cInfo):
logSys.error("Cinfo/definitions contain self referencing definitions and cannot be resolved")
return False
startCmd = Action.replaceTag(self.__actionStart, self.__cInfo)
return Action.executeCmd(startCmd)
##
# Set the "ban" command.
#
# @param value the command
def setActionBan(self, value):
self.__actionBan = value
logSys.debug("Set actionBan = %s" % value)
##
# Get the "ban" command.
#
# @return the command
def getActionBan(self):
return self.__actionBan
##
# Executes the action "ban" command.
#
# @return True if the command succeeded
def execActionBan(self, aInfo):
return self.__processCmd(self.__actionBan, aInfo)
##
# Set the "unban" command.
#
# @param value the command
def setActionUnban(self, value):
self.__actionUnban = value
logSys.debug("Set actionUnban = %s" % value)
##
# Get the "unban" command.
#
# @return the command
def getActionUnban(self):
return self.__actionUnban
##
# Executes the action "unban" command.
#
# @return True if the command succeeded
def execActionUnban(self, aInfo):
return self.__processCmd(self.__actionUnban, aInfo)
##
# Set the "check" command.
#
# @param value the command
def setActionCheck(self, value):
self.__actionCheck = value
logSys.debug("Set actionCheck = %s" % value)
##
# Get the "check" command.
#
# @return the command
def getActionCheck(self):
return self.__actionCheck
##
# Set the "stop" command.
#
# @param value the command
def setActionStop(self, value):
self.__actionStop = value
logSys.debug("Set actionStop = %s" % value)
##
# Get the "stop" command.
#
# @return the command
def getActionStop(self):
return self.__actionStop
##
# Executes the action "stop" command.
#
# Replaces the tags in the action command with value of "cInfo"
# and executes the resulting command.
#
# @return True if the command succeeded
def execActionStop(self):
stopCmd = Action.replaceTag(self.__actionStop, self.__cInfo)
return Action.executeCmd(stopCmd)
##
# Sort out tag definitions within other tags
#
# so: becomes:
# a = 3 a = 3
# b = <a>_3 b = 3_3
# @param tags, a dictionary
# @returns tags altered or False if there is a recursive definition
#@staticmethod
def substituteRecursiveTags(tags):
t = re.compile(r'<([^ >]+)>')
for tag, value in tags.iteritems():
value = str(value)
m = t.search(value)
while m:
if m.group(1) == tag:
# recursive definitions are bad
return False
else:
if tags.has_key(m.group(1)):
value = value[0:m.start()] + tags[m.group(1)] + value[m.end():]
m = t.search(value, m.start())
else:
# Missing tags are ok so we just continue on searching.
# cInfo can contain aInfo elements like <HOST> and valid shell
# constructs like <STDIN>.
m = t.search(value, m.start() + 1)
tags[tag] = value
return tags
substituteRecursiveTags = staticmethod(substituteRecursiveTags)
#@staticmethod
def escapeTag(tag):
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for c in '\\#&;`|*?~<>^()[]{}$\n\'"':
if c in tag:
tag = tag.replace(c, '\\' + c)
return tag
escapeTag = staticmethod(escapeTag)
##
# Replaces tags in query with property values in aInfo.
#
# @param query the query string with tags
# @param aInfo the properties
# @return a string
#@staticmethod
def replaceTag(query, aInfo):
""" Replace tags in query
"""
string = query
for tag, value in aInfo.iteritems():
value = str(value) # assure string
if tag == 'matches':
# That one needs to be escaped since its content is
# out of our control
value = Action.escapeTag(value)
string = string.replace('<' + tag + '>', value)
# New line
string = string.replace("<br>", '\n')
return string
replaceTag = staticmethod(replaceTag)
##
# Executes a command with preliminary checks and substitutions.
#
# 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,
# it tries to restore a sane environment before executing the real
# command.
# Replaces "aInfo" and "cInfo" in the query too.
#
# @param cmd The command to execute
# @param aInfo Dynamic properties
# @return True if the command succeeded
def __processCmd(self, cmd, aInfo = None):
""" Executes an OS command.
"""
if cmd == "":
logSys.debug("Nothing to do")
return True
checkCmd = Action.replaceTag(self.__actionCheck, self.__cInfo)
if not Action.executeCmd(checkCmd):
logSys.error("Invariant check failed. Trying to restore a sane" +
" environment")
self.execActionStop()
self.execActionStart()
if not Action.executeCmd(checkCmd):
logSys.fatal("Unable to restore environment")
return False
# Replace tags
if not aInfo is None:
realCmd = Action.replaceTag(cmd, aInfo)
else:
realCmd = cmd
# Replace static fields
realCmd = Action.replaceTag(realCmd, self.__cInfo)
return Action.executeCmd(realCmd)
##
# Executes a command.
#
# We need a shell here because commands are mainly shell script. They
# contain pipe, redirection, etc.
#
# @todo Force the use of bash!?
# @todo Kill the command after a given timeout
#
# @param realCmd the command to execute
# @return True if the command succeeded
#@staticmethod
def executeCmd(realCmd):
logSys.debug(realCmd)
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if realCmd is None or realCmd == "":
logSys.debug("Nothing to do")
return True
_cmd_lock.acquire()
try: # Try wrapped within another try needed for python version < 2.5
try:
# The following line gives deadlock with multiple jails
#retcode = call(realCmd, shell=True)
retcode = os.system(realCmd)
if retcode == 0:
logSys.debug("%s returned successfully" % realCmd)
return True
else:
msg = _RETCODE_HINTS.get(retcode, None)
logSys.error("%s returned %x" % (realCmd, retcode))
if msg:
logSys.info("HINT on %x: %s"
% (retcode, msg % locals()))
except OSError, e:
logSys.error("%s failed with %s" % (realCmd, e))
finally:
_cmd_lock.release()
return False
executeCmd = staticmethod(executeCmd)