suricata: correct rule actions in IPS mode

In IPS mode rule actions need to be have the action 'drop' for the
protection to work, however this is not appropriate for all rules.
Modify the generator for oinkmaster-modify-sids.conf to leave
rules with the action 'alert' here this is appropriate.  Also add
a script to be run on update to correct existing downloaded rules.

Fixes #12086

Signed-off-by: Tim FitzGeorge <ipfr@tfitzgeorge.me.uk>
Tested-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Stefan Schantl <stefan.schantl@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>

config/cfgroot/ids-functions.pl

@@ -243,7 +243,7 @@ sub downloadruleset {
 	# Load perl module to deal with temporary files.
 	use File::Temp;
 
-	# Generate temporay file name, located in "/var/tmp" and with a suffix of ".tar.gz".
+	# Generate temporary file name, located in "/var/tmp" and with a suffix of ".tar.gz".
 	my $tmp = File::Temp->new( SUFFIX => ".tar.gz", DIR => "/var/tmp/", UNLINK => 0 );
 	my $tmpfile = $tmp->filename();
 
@@ -293,6 +293,9 @@ sub downloadruleset {
 	# Overwrite existing rules tarball with the new downloaded one.
 	move("$tmpfile", "$rulestarball");
 
+	# Set correct ownership for the rulesdir and files.
+	set_ownership("$rulestarball");
+
 	# If we got here, everything worked fine. Return nothing.
 	return;
 }
@@ -726,8 +729,8 @@ sub write_used_rulefiles_file(@) {
 #
 ## Function to generate and write the file for modify the ruleset.
 #
-sub write_modify_sids_file($) {
-	my ($ruleaction) = @_;
+sub write_modify_sids_file($$) {
+	my ($ruleaction,$rulefile) = @_;
 
 	# Open modify sid's file for writing.
 	open(FILE, ">$modify_sids_file") or die "Could not write to $modify_sids_file. $!\n";
@@ -737,8 +740,39 @@ sub write_modify_sids_file($) {
 
 	# Check if the traffic only should be monitored.
 	unless($ruleaction eq "alert") {
-		# Tell oinkmaster to switch all rules from alert to drop.
-		print FILE "modifysid \* \"alert\" \| \"drop\"\n";
+		# Suricata is in IPS mode, which means that the rule actions have to be changed
+		# from 'alert' to 'drop', however not all rules should be changed.  Some rules
+		# exist purely to set a flowbit which is used to convey other information, such
+		# as a specific type of file being downloaded, to other rulewhich then check for
+		# malware in that file.  Rules which fall into the first category should stay as
+		# alert since not all flows of that type contain malware.
+
+		if($rulefile eq 'registered' or $rulefile eq 'subscripted' or $rulefile eq 'community') {
+			# These types of rulesfiles contain meta-data which gives the action that should
+			# be used when in IPS mode.  Do the following:
+			#
+			# 1. Disable all rules and set the action to 'drop'
+			# 2. Set the action back to 'alert' if the rule contains 'flowbits:noalert;'
+			#    This should give rules not in the policy a reasonable default if the user
+			#    manually enables them.
+			# 3. Enable rules and set actions according to the meta-data strings.
+
+			my $policy = 'balanced';  # Placeholder to allow policy to be changed.
+
+			print FILE <<END;
+modifysid * "^#?(?:alert|drop)" | "#drop"
+modifysid * "^#drop(.+flowbits:noalert;)" | "#alert\${1}"
+modifysid * "^#(?:alert|drop)(.+policy $policy-ips alert)" | "alert\${1}"
+modifysid * "^#(?:alert|drop)(.+policy $policy-ips drop)" | "drop\${1}"
+END
+		} else {
+			# These rulefiles don't have the metadata, so set rules to 'drop' unless they
+			# contain the string 'flowbits:noalert;'.
+			print FILE <<END;
+modifysid * "^(#?)(?:alert|drop)" | "\${1}drop"
+modifysid * "^(#?)drop(.+flowbits:noalert;)" | "\${1}alert\${2}"
+END
+		}
 	}
 
 	# Close file handle.

config/rootfiles/common/configroot

@@ -3,6 +3,7 @@ usr/sbin/convert-outgoingfw
 usr/sbin/convert-portfw
 usr/sbin/convert-snort
 usr/sbin/convert-xtaccess
+usr/sbin/convert-ids-modifysids-file
 usr/sbin/firewall-policy
 #var/ipfire
 var/ipfire/addon-lang

config/rootfiles/core/133/update.sh

@@ -62,6 +62,9 @@ telinit u
 # Regenerate /etc/ipsec.conf
 sudo -u nobody /srv/web/ipfire/cgi-bin/vpnmain.cgi
 
+# Modify suricata modify-sids file
+/usr/sbin/convert-ids-modifysids-file
+
 # Start services
 /usr/local/bin/ipsecctrl S
 /etc/init.d/suricata restart

config/suricata/convert-ids-modifysids-file

@@ -0,0 +1,84 @@
+#!/usr/bin/perl
+###############################################################################
+#                                                                             #
+# IPFire.org - A linux based firewall                                         #
+# Copyright (C) 2019 IPFire Development Team <info@ipfire.org>                #
+#                                                                             #
+# This program 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 3 of the License, or           #
+# (at your option) any later version.                                         #
+#                                                                             #
+# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.       #
+#                                                                             #
+###############################################################################
+
+use strict;
+
+require '/var/ipfire/general-functions.pl';
+require "${General::swroot}/ids-functions.pl";
+
+# Hash which contains the IDS (suricata) settings.
+my %idssettings;
+
+# Hash which contains the RULES settings.
+my %rulessettings;
+
+#
+## Step 1: Read IDS and rules settings.
+#
+
+exit unless(-f $IDS::ids_settings_file and -f $IDS::rules_settings_file);
+
+# Read IDS settings.
+&General::readhash("$IDS::ids_settings_file", \%idssettings);
+
+# Read rules settings.
+&General::readhash("$IDS::rules_settings_file", \%rulessettings);
+
+#
+## Step 2: Generate and write the file to modify the ruleset.
+#
+
+my $IDS_action = "drop";
+
+# Check if the traffic only should be monitored.
+if ($idssettings{"MONITOR_TRAFFIC_ONLY"} eq "on") {
+	# Switch IDS action to alert only.
+	$IDS_action = "alert";
+}
+
+# Call subfunction and pass the desired IDS action.
+&IDS::write_modify_sids_file($IDS_action, $rulessettings{RULES});
+
+# Set correct ownership.
+&IDS::set_ownership("$IDS::modify_sids_file");
+
+#
+## Step 3: Call oinkmaster to extract and setup the rules structures.
+#
+
+# Check if a rulestarball is present.
+if (-f $IDS::rulestarball) {
+	# Launch oinkmaster by calling the subfunction.
+	&IDS::oinkmaster();
+
+	# Set correct ownership for the rulesdir and files.
+	&IDS::set_ownership("$IDS::rulespath");
+}
+
+#
+## Step 4: Start the IDS if enabled.
+#
+
+# Check if the IDS should be started.
+if($idssettings{"ENABLE_IDS"} eq "on") {
+	# Call suricatactrl and reload the rules.
+	&IDS::call_suricatactrl("reload");
+}