guardian

   1 #!/usr/bin/perl
   2 ###############################################################################
   3 #                                                                             #
   4 # IPFire.org - A linux based firewall                                         #
   5 # Copyright (C) 2015  IPFire Development Team                                 #
   6 #                                                                             #
   7 # This program is free software: you can redistribute it and/or modify        #
   8 # it under the terms of the GNU General Public License as published by        #
   9 # the Free Software Foundation, either version 3 of the License, or           #
  10 # (at your option) any later version.                                         #
  11 #                                                                             #
  12 # This program is distributed in the hope that it will be useful,             #
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of              #
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the               #
  15 # GNU General Public License for more details.                                #
  16 #                                                                             #
  17 # You should have received a copy of the GNU General Public License           #
  18 # along with this program.  If not, see <http://www.gnu.org/licenses/>.       #
  19 #                                                                             #
  20 ###############################################################################
  21
  22 use strict;
  23 use threads;
  24 use threads::shared;
  25 use Getopt::Long;
  26 use Thread::Queue;
  27 use Linux::Inotify2;
  28
  29 require Guardian::Config;
  30 require Guardian::Parser;
  31 require Guardian::Socket;
  32
  33 # Define version.
  34 my $version ="2.0";
  35
  36 # Array to store the monitored logfiles.
  37 my @monitored_files = (
  38         "/var/log/snort/alert",
  39 );
  40
  41 # Get and store the given command line arguments in a hash.
  42 my %cmdargs = ();
  43
  44 &GetOptions (\%cmdargs,
  45         'foreground|f',
  46         'config|c=s',
  47         'help|h',
  48         'version|v',
  49 );
  50
  51 # Show help / version information.
  52 if (defined($cmdargs{"help"})) {
  53         print "Guardian $version \n";
  54         print "Usage: guardian <optional arguments>\n";
  55         print " -c, --config\t\tspecifiy a configuration file other than the default (/etc/guardian/guardian.conf)\n";
  56         print " -f, --foreground\trun in the foreground (doesn't fork, any output goes to STDOUT)\n";
  57         print " -h, --help\t\tshows this help\n";
  58         print " -v, --version\t\tdisplay programm version and exit.\n";
  59         exit;
  60 } elsif (defined($cmdargs{"version"})) {
  61         print "Guardian $version \n";
  62         exit;
  63 }
  64
  65 # Read-in the configuration file and store the settings.
  66 # Push the may be given config file argument.
  67 my %mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});
  68
  69 # Create the main queue. It is used to store and process all events which are
  70 # reported and enqueued by the worker threads.
  71 my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!\n";;
  72
  73 # Call Init function to initzialize guardian.
  74 &Init();
  75
  76 # Infinite main loop, which processes all queued events.
  77 while(1) {
  78         # Get the amount of elements in our queue.
  79         # "undef" will be returned if it is empty.
  80         my $current_events = $queue->pending();
  81
  82         # If there is at least one element enqued
  83         if($current_events > 0) {
  84                 # Grab the data of the top enqueued event.
  85                 my $event = $queue->peek();
  86
  87                 print "Got event: $event\n";
  88
  89                 # Drop processed event from queue.
  90                 $queue->dequeue();
  91         }
  92
  93         # XXX
  94         # Temporary workaround to reduce the load of the main process.
  95         sleep(1);
  96 }
  97
  98 #
  99 ## Init function.
 100 #
 101 ## This function contains code which has to be executed while guardian
 102 ## is starting.
 103 #
 104 sub Init () {
 105         # Setup IPC mechanism via Socket in an own thread.
 106         threads->create(\&Socket);
 107
 108         # Loop through the array of which files should be monitored and
 109         # create a worker thread for each single one.
 110         foreach my $monitored_file (@monitored_files) {
 111                 # Check if the file exists and is readable.
 112                 if (-r "$monitored_file") {
 113                         # Create worker thread for the file.
 114                         threads->create(\&Worker,$monitored_file);
 115                 }
 116         }
 117 }
 118
 119 #
 120 ## Worker function.
 121 #
 122 ## This function is responsible for monitoring modifications of the given logfile,
 123 ## read them and pass them to the message parser.
 124 #
 125 ## To get file modifications the inotify subsystem of the linux kernel is used.
 126 #
 127 ## In order to prevent from permanently read and keep files opened, or dealing
 128 ## with huge logfiles, at initialization time of the worker process, the file will
 129 ## be opened once and the cursor position of the end of file (EOF) get stored. When
 130 ## reading any newly added lines from the file, we directly can jump to the last
 131 ## known position and get these lines. Afterwards, we store the current curser position
 132 ## again, so we can do it in this way over and over again.
 133 #
 134 ## All read lines get stored in an array, which will be passed to the Parser.
 135 #
 136 ## If any response (action) from the parser get recieved, it will be put into the
 137 ## shared event queue.
 138 #
 139 sub Worker ($) {
 140         my $file = @_[0];
 141
 142         # Get the fileposition.
 143         my $fileposition = &Init_fileposition("$file");
 144
 145         # Create inotify watcher.
 146         my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!\n";
 147
 148         # Monitor the specified file.
 149         $watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!\n";
 150
 151         # Get all notifications.
 152         while ($watcher->read) {
 153                 my @message = ();
 154
 155                 # Open the file.
 156                 open (FILE, $file) or die "Could not open $file. $!\n";
 157
 158                 # Seek to the last known position.
 159                 seek (FILE, $fileposition, 0);
 160
 161                 # Get the log message.
 162                 while (my $line = <FILE>) {
 163                         # Remove any newlines.
 164                         chomp $line;
 165
 166                         # Add all lines to the message array.
 167                         push (@message, $line);
 168                 }
 169
 170                 # Update fileposition.
 171                 $fileposition = tell(FILE);
 172
 173                 # Close file.
 174                 close(FILE);
 175
 176                 # Send filename and message to the parser,
 177                 # which will return if an action has to be performed.
 178                 my @action = &Guardian::Parser::Parser("$file", @message);
 179
 180                 # Send the action to the main process and put it into
 181                 # the queue.
 182                 if (@action) {
 183                         # Lock the queue.
 184                         lock($queue);
 185
 186                         # Put the required action into the queue.
 187                         $queue->enqueue(@action);
 188                 }
 189         }
 190 }
 191
 192 #
 193 ## Socket function.
 194 #
 195 ## This function uses the Socket module to create and listen to an UNIX socket.
 196 ## It automatically accepts all incomming connections and pass the recieved
 197 ## data messages to the the Message_Parser function which is also part of the
 198 ## socket module.
 199 #
 200 ## If a valid command has been sent through the socket, the corresponding event
 201 ## will be enqueued into the shared event queue.
 202 #
 203 sub Socket () {
 204         # Create the Server socket by calling the responsible function.
 205         my $server = &Guardian::Socket::Server();
 206
 207         # Accept incomming connections from the socket.
 208         while (my $connection = $server->accept()) {
 209                 # Autoflush the socket after the data
 210                 # has been recieved.
 211                 $connection->autoflush(1);
 212
 213                 # Gather all data from the connection.
 214                 while (my $message = <$connection>) {
 215                         # Remove any newlines.
 216                         chomp($message);
 217
 218                         # Send the recieved data message to the
 219                         # socket parser.
 220                         my $action = &Guardian::Socket::Message_Parser($message);
 221
 222                         # If the parser returns to perform an action,
 223                         # add it to the main event queue.
 224                         if ($action) {
 225                                 # Lock the queue.
 226                                 lock($queue);
 227
 228                                 # Enqueue the returned action.
 229                                 $queue->enqueue($action);
 230                         }
 231                 }
 232         }
 233 }
 234
 235 #
 236 ## Function for fileposition initialization.
 237 #
 238 ## This function is used to get the cursor position of the end of file (EOF) of
 239 ## a specified file.
 240 #
 241 ## In order to prevent from permanently read and keep files opened, or dealing
 242 ## with huge logfiles, at initialization time of the worker processes, the file will
 243 ## be opened once and the cursor position of the end of file (EOF) get stored.
 244 #
 245 sub Init_fileposition ($) {
 246         my $file = $_[0];
 247
 248         # Open the file.
 249         open(FILE, $file) or die "Could not open $file. $!\n";
 250
 251         # Just seek to the end of the file (EOF).
 252         seek(FILE, 0, 2);
 253
 254         # Get and store the position.
 255         my $position = tell(FILE),
 256
 257         # Close the file again.
 258         close(FILE);
 259
 260         # Return the position.
 261         return $position;
 262 }