fixed security hole with world-open umask

debian/postinst

@@ -0,0 +1,44 @@
+#! /bin/sh
+# postinst script for fail2ban
+#
+# see: dh_installdeb(1)
+
+set -e
+
+# summary of how this script can be called:
+#        * <postinst> `configure' <most-recently-configured-version>
+#        * <old-postinst> `abort-upgrade' <new version>
+#        * <conflictor's-postinst> `abort-remove' `in-favour' <package>
+#          <new-version>
+#        * <deconfigured's-postinst> `abort-deconfigure' `in-favour'
+#          <failed-install-package> <version> `removing'
+#          <conflicting-package> <version>
+# for details, see http://www.debian.org/doc/debian-policy/ or
+# the debian-policy package
+#
+
+case "$1" in
+    configure)
+       # To fix the bug in generated by previous version files permissions
+        LOG=/var/log/fail2ban.log
+        [ -f $LOG ] && chmod go-w $LOG
+    ;;
+
+    abort-upgrade|abort-remove|abort-deconfigure)
+
+    ;;
+
+    *)
+        echo "postinst called with unknown argument \`$1'" >&2
+        exit 1
+    ;;
+esac
+
+# dh_installdeb will replace this with shell code automatically
+# generated by other debhelper scripts.
+
+#DEBHELPER#
+
+exit 0
+
+

fail2ban.py

@@ -129,7 +129,9 @@ def createDaemon():
 			# to do this could make a filesystem unmountable.
 			os.chdir("/")
 			# Give the child complete control over permissions.
-			os.umask(0)
+                        # yoh: BAD BAD BAD IDEA - generated files are writable by everybody
+                        # changing to restrictive umask
+			os.umask(0022)
 		else:
 			os._exit(0)	  # Exit parent (the first child) of the second child.
 	else: