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 use Time::HiRes qw[ time sleep ];
  29
  30 require Guardian::Config;
  31 require Guardian::Parser;
  32 require Guardian::Socket;
  33
  34 use warnings;
  35
  36 # Define version.
  37 my $version ="2.0";
  38
  39 # Array to store the monitored logfiles.
  40 my @monitored_files = (
  41         "/var/log/snort/alert",
  42 );
  43
  44 # Get and store the given command line arguments in a hash.
  45 my %cmdargs = ();
  46
  47 &GetOptions (\%cmdargs,
  48         'foreground|f',
  49         'config|c=s',
  50         'help|h',
  51         'version|v',
  52 );
  53
  54 # Show help / version information.
  55 if (defined($cmdargs{"help"})) {
  56         print "Guardian $version \n";
  57         print "Usage: guardian <optional arguments>\n";
  58         print " -c, --config\t\tspecifiy a configuration file other than the default (/etc/guardian/guardian.conf)\n";
  59         print " -f, --foreground\trun in the foreground (doesn't fork, any output goes to STDOUT)\n";
  60         print " -h, --help\t\tshows this help\n";
  61         print " -v, --version\t\tdisplay programm version and exit.\n";
  62         exit;
  63 } elsif (defined($cmdargs{"version"})) {
  64         print "Guardian $version \n";
  65         exit;
  66 }
  67
  68 # Read-in the configuration file and store the settings.
  69 # Push the may be given config file argument.
  70 my %mainsettings = &Guardian::Config::UseConfig($cmdargs{"config"});
  71
  72 # Create the main queue. It is used to store and process all events which are
  73 # reported and enqueued by the worker threads.
  74 my $queue :shared = new Thread::Queue or die "Could not create new, empty queue. $!\n";;
  75
  76 # Call Init function to initzialize guardian.
  77 &Init();
  78
  79 # Infinite main loop, which processes all queued events.
  80 while(1) {
  81         # Get the amount of elements in our queue.
  82         # "undef" will be returned if it is empty.
  83         my $current_events = $queue->pending();
  84
  85         # If there is at least one element enqued
  86         if($current_events > 0) {
  87                 # Grab the data of the top enqueued event.
  88                 my $event = $queue->peek();
  89
  90                 print "Got event: $event\n";
  91
  92                 # Drop processed event from queue.
  93                 $queue->dequeue();
  94         }
  95
  96         # Sleep 10ms to reduce the load of the main process.
  97         sleep(0.01);
  98 }
  99
 100 #
 101 ## Init function.
 102 #
 103 ## This function contains code which has to be executed while guardian
 104 ## is starting.
 105 #
 106 sub Init () {
 107         # Setup signal handler.
 108         &SignalHandler();
 109
 110         # Setup IPC mechanism via Socket in an own thread.
 111         threads->create(\&Socket);
 112
 113         # Loop through the array of which files should be monitored and
 114         # create a worker thread for each single one.
 115         foreach my $monitored_file (@monitored_files) {
 116                 # Check if the file exists and is readable.
 117                 if (-r "$monitored_file") {
 118                         # Create worker thread for the file.
 119                         threads->create(\&Worker,$monitored_file);
 120                 }
 121         }
 122 }
 123
 124 #
 125 ## Worker function.
 126 #
 127 ## This function is responsible for monitoring modifications of the given logfile,
 128 ## read them and pass them to the message parser.
 129 #
 130 ## To get file modifications the inotify subsystem of the linux kernel is used.
 131 #
 132 ## In order to prevent from permanently read and keep files opened, or dealing
 133 ## with huge logfiles, at initialization time of the worker process, the file will
 134 ## be opened once and the cursor position of the end of file (EOF) get stored. When
 135 ## reading any newly added lines from the file, we directly can jump to the last
 136 ## known position and get these lines. Afterwards, we store the current curser position
 137 ## again, so we can do it in this way over and over again.
 138 #
 139 ## All read lines get stored in an array, which will be passed to the Parser.
 140 #
 141 ## If any response (action) from the parser get recieved, it will be put into the
 142 ## shared event queue.
 143 #
 144 sub Worker ($) {
 145         my $file = @_[0];
 146
 147         # Get the fileposition.
 148         my $fileposition = &Init_fileposition("$file");
 149
 150         # Create inotify watcher.
 151         my $watcher = new Linux::Inotify2 or die "Could not use inotify. $!\n";
 152
 153         # Monitor the specified file.
 154         $watcher->watch("$file", IN_MODIFY) or die "Could not monitor $file. $!\n";
 155
 156         # Get all notifications.
 157         while ($watcher->read) {
 158                 my @message = ();
 159
 160                 # Open the file.
 161                 open (FILE, $file) or die "Could not open $file. $!\n";
 162
 163                 # Seek to the last known position.
 164                 seek (FILE, $fileposition, 0);
 165
 166                 # Get the log message.
 167                 while (my $line = <FILE>) {
 168                         # Remove any newlines.
 169                         chomp $line;
 170
 171                         # Add all lines to the message array.
 172                         push (@message, $line);
 173                 }
 174
 175                 # Update fileposition.
 176                 $fileposition = tell(FILE);
 177
 178                 # Close file.
 179                 close(FILE);
 180
 181                 # Send filename and message to the parser,
 182                 # which will return if an action has to be performed.
 183                 my @action = &Guardian::Parser::Parser("$file", @message);
 184
 185                 # Send the action to the main process and put it into
 186                 # the queue.
 187                 if (@action) {
 188                         # Lock the queue.
 189                         lock($queue);
 190
 191                         # Put the required action into the queue.
 192                         $queue->enqueue(@action);
 193                 }
 194         }
 195 }
 196
 197 #
 198 ## Socket function.
 199 #
 200 ## This function uses the Socket module to create and listen to an UNIX socket.
 201 ## It automatically accepts all incomming connections and pass the recieved
 202 ## data messages to the the Message_Parser function which is also part of the
 203 ## socket module.
 204 #
 205 ## If a valid command has been sent through the socket, the corresponding event
 206 ## will be enqueued into the shared event queue.
 207 #
 208 sub Socket () {
 209         # Create the Server socket by calling the responsible function.
 210         my $server = &Guardian::Socket::Server();
 211
 212         # Accept incomming connections from the socket.
 213         while (my $connection = $server->accept()) {
 214                 # Autoflush the socket after the data
 215                 # has been recieved.
 216                 $connection->autoflush(1);
 217
 218                 # Gather all data from the connection.
 219                 while (my $message = <$connection>) {
 220                         # Remove any newlines.
 221                         chomp($message);
 222
 223                         # Send the recieved data message to the
 224                         # socket parser.
 225                         my $action = &Guardian::Socket::Message_Parser($message);
 226
 227                         # If the parser returns to perform an action,
 228                         # add it to the main event queue.
 229                         if ($action) {
 230                                 # Lock the queue.
 231                                 lock($queue);
 232
 233                                 # Enqueue the returned action.
 234                                 $queue->enqueue($action);
 235                         }
 236                 }
 237         }
 238 }
 239
 240 #
 241 ## Function for fileposition initialization.
 242 #
 243 ## This function is used to get the cursor position of the end of file (EOF) of
 244 ## a specified file.
 245 #
 246 ## In order to prevent from permanently read and keep files opened, or dealing
 247 ## with huge logfiles, at initialization time of the worker processes, the file will
 248 ## be opened once and the cursor position of the end of file (EOF) get stored.
 249 #
 250 sub Init_fileposition ($) {
 251         my $file = $_[0];
 252
 253         # Open the file.
 254         open(FILE, $file) or die "Could not open $file. $!\n";
 255
 256         # Just seek to the end of the file (EOF).
 257         seek(FILE, 0, 2);
 258
 259         # Get and store the position.
 260         my $position = tell(FILE),
 261
 262         # Close the file again.
 263         close(FILE);
 264
 265         # Return the position.
 266         return $position;
 267 }
 268
 269 #
 270 ## Function for capturing process signals.
 271 #
 272 ## This function captures any sent process signals and will call various
 273 ## actions, basend on the captured signal.
 274 #
 275 sub SignalHandler {
 276         $SIG{INT} = \&Shutdown;
 277         $SIG{TERM} = \&Shutdown;
 278         $SIG{QUIT} = \&Shutdown;
 279 }
 280
 281 #
 282 ## Shutdown function.
 283 #
 284 ## This function is used to do a clean shutdown of guardian. It will be called
 285 ## by the signal handler when recieving INT (2), QUIT (3) and TERM (15) signals.
 286 #
 287 sub Shutdown () {
 288         # Remove socket file on exit.
 289         &Guardian::Socket::RemoveSocketFile();
 290
 291         # Exit guardian.
 292         exit;
 293 }