Source code for plaso.parsers.selinux

# -*- coding: utf-8 -*-
"""This file contains SELinux audit log (audit.log) file parser.

Information updated 16 january 2013.

An example:

type=AVC msg=audit(1105758604.519:420): avc: denied { getattr } for pid=5962
comm="httpd" path="/home/auser/public_html" dev=sdb2 ino=921135

Where msg=audit(1105758604.519:420) contains the number of seconds since
January 1, 1970 00:00:00 UTC and the number of milliseconds after the dot
for example: "seconds: 1105758604, milliseconds: 519".

The number after the timestamp (420 in the example) is a 'serial number'
that can be used to correlate multiple logs generated from the same event.

import pyparsing

from dfdatetime import posix_time as dfdatetime_posix_time

from plaso.containers import events
from plaso.containers import time_events
from plaso.lib import errors
from plaso.lib import definitions
from plaso.parsers import logger
from plaso.parsers import manager
from plaso.parsers import text_parser

[docs]class SELinuxLogEventData(events.EventData): """SELinux log event data. Attributes: audit_type (str): audit type. body (str): body of the log line. pid (int): process identifier (PID) that created the SELinux log line. """ DATA_TYPE = 'selinux:line' def __init__(self): """Initializes event data.""" super(SELinuxLogEventData, self).__init__(data_type=self.DATA_TYPE) self.audit_type = None self.body = None = None
[docs]class SELinuxParser(text_parser.PyparsingSingleLineTextParser): """Parser for SELinux audit log (audit.log) files.""" NAME = 'selinux' DATA_FORMAT = 'SELinux audit log (audit.log) file' _ENCODING = 'utf-8' _SELINUX_KEY_VALUE_GROUP = pyparsing.Group( pyparsing.Word(pyparsing.alphanums).setResultsName('key') + pyparsing.Suppress('=') + ( pyparsing.QuotedString('"') ^ pyparsing.Word(pyparsing.printables)).setResultsName('value')) _SELINUX_KEY_VALUE_DICT = pyparsing.Dict( pyparsing.ZeroOrMore(_SELINUX_KEY_VALUE_GROUP)) _SELINUX_BODY_GROUP = pyparsing.Group( pyparsing.Empty().setResultsName('key') + pyparsing.restOfLine.setResultsName('value')) _SELINUX_MSG_GROUP = pyparsing.Group( pyparsing.Literal('msg').setResultsName('key') + pyparsing.Suppress('=audit(') + pyparsing.Word(pyparsing.nums).setResultsName('seconds') + pyparsing.Suppress('.') + pyparsing.Word(pyparsing.nums).setResultsName('milliseconds') + pyparsing.Suppress(':') + pyparsing.Word(pyparsing.nums).setResultsName('serial') + pyparsing.Suppress('):')) _SELINUX_TYPE_GROUP = pyparsing.Group( pyparsing.Literal('type').setResultsName('key') + pyparsing.Suppress('=') + ( pyparsing.Word(pyparsing.srange('[A-Z_]')) ^ pyparsing.Regex(r'UNKNOWN\[[0-9]+\]')).setResultsName('value')) _SELINUX_TYPE_AVC_GROUP = pyparsing.Group( pyparsing.Literal('type').setResultsName('key') + pyparsing.Suppress('=') + ( pyparsing.Word('AVC') ^ pyparsing.Word('USER_AVC')).setResultsName('value')) # A log line is formatted as: type=TYPE msg=audit([0-9]+\.[0-9]+:[0-9]+): .* _SELINUX_LOG_LINE = pyparsing.Dict( _SELINUX_TYPE_GROUP + _SELINUX_MSG_GROUP + _SELINUX_BODY_GROUP) LINE_STRUCTURES = [('line', _SELINUX_LOG_LINE)]
[docs] def ParseRecord(self, parser_mediator, key, structure): """Parses a structure of tokens derived from a line of a text file. Args: parser_mediator (ParserMediator): mediates interactions between parsers and other components, such as storage and dfvfs. key (str): name of the parsed structure. structure (pyparsing.ParseResults): structure of tokens derived from a line of a text file. Raises: ParseError: when the structure type is unknown. """ if key != 'line': raise errors.ParseError( 'Unable to parse record, unknown structure: {0:s}'.format(key)) msg_value = self._GetValueFromStructure(structure, 'msg') if not msg_value: parser_mediator.ProduceExtractionWarning( 'missing msg value: {0!s}'.format(structure)) return try: seconds = int(msg_value[0], 10) except ValueError: parser_mediator.ProduceExtractionWarning( 'unsupported number of seconds in msg value: {0!s}'.format( structure)) return try: milliseconds = int(msg_value[1], 10) except ValueError: parser_mediator.ProduceExtractionWarning( 'unsupported number of milliseconds in msg value: {0!s}'.format( structure)) return timestamp = ((seconds * 1000) + milliseconds) * 1000 body_text = structure[2][0] try: # Try to parse the body text as key value pairs. Note that not # all log lines will be properly formatted key value pairs. body_structure = self._SELINUX_KEY_VALUE_DICT.parseString(body_text) except pyparsing.ParseException: body_structure = pyparsing.ParseResults() event_data = SELinuxLogEventData() event_data.audit_type = self._GetValueFromStructure(structure, 'type') event_data.body = body_text = self._GetValueFromStructure(body_structure, 'pid') # TODO: pass line number to offset or remove. event_data.offset = 0 date_time = dfdatetime_posix_time.PosixTimeInMicroseconds( timestamp=timestamp) event = time_events.DateTimeValuesEvent( date_time, definitions.TIME_DESCRIPTION_WRITTEN) parser_mediator.ProduceEventWithEventData(event, event_data)
[docs] def VerifyStructure(self, parser_mediator, line): """Verifies if a line from a text file is in the expected format. Args: parser_mediator (ParserMediator): mediates interactions between parsers and other components, such as storage and dfvfs. line (str): line from a text file. Returns: bool: True if the line is in the expected format, False if not. """ try: structure = self._SELINUX_LOG_LINE.parseString(line) except pyparsing.ParseException as exception: logger.debug( 'Unable to parse SELinux audit.log file with error: {0!s}'.format( exception)) return False return 'type' in structure and 'msg' in structure