[or-cvs] [torsocks/master] LD_PRELOAD is ignored for binaries where setuid/gid is used. As used, torsocks doesn't detect this, which means that it provides a false sense of security when running these types of executables.

[mwenge at seul.org]

Author: mwenge <robert at roberthogan.net>
Date: Tue, 16 Jun 2009 23:59:13 +0100
Subject: LD_PRELOAD is ignored for binaries where setuid/gid is used. As used,
Commit: 3d774d0d05872510d495108b7bbc5e67e6dbb29e

Added logic that detects setuid/setgid programs and fails early with an
error message.

Further reorganized the file to simplify flow and improve command line
argument handling.

Patch by Marcus Griep <marcus at griep.us>
---
 src/usewithtor.in |   99 ++++++++++++++++++++++++++++++++++++-----------------
 1 files changed, 67 insertions(+), 32 deletions(-)

diff --git a/src/usewithtor.in b/src/usewithtor.in
index c2090fb..b252663 100644
--- a/src/usewithtor.in
+++ b/src/usewithtor.in
@@ -1,3 +1,4 @@
+#! /bin/sh
 # ***************************************************************************
 # *                                                                         *
 # * $Id: usewithtor.in,v 1.3 2008-07-06 15:17:35 hoganrobert Exp $*
@@ -25,50 +26,84 @@
 # *   Original copyright notice from tsocks source file follows:            *
 # ***************************************************************************
 
-
-#! /bin/sh
-
-# Wrapper script for use of the torsocks(8) transparent socksification library
-# See the torsocks(1) and usewithtor(1) manpages.
+# Wrapper script for use of the tsocks(8) transparent socksification library
+# See the tsocks(1) and torify(1) manpages.
 
 # Copyright (c) 2004, 2006 Peter Palfrader
 # Modified by Jacob Appelbaum <jacob at appelbaum.net> April 16th 2006
-# Modified by Robert Hogan <robert at roberthogan.net> March 2007
+# Modified by Marcus Griep <marcus at griep.us> June 16 2009
 # May be distributed under the same terms as Tor itself
 
 
-# Define and ensure we have torsocks
+# Define and ensure we have tsocks
 # XXX: what if we don't have which?
-TSOCKS="`which torsocks`"
-if [ ! -x "$TSOCKS" ]
-then
-        echo "$0: Can't find torsocks in PATH. Perhaps you haven't installed it?" >&2
-        exit 1
-fi
+TORSOCKS="`which torsocks`"
+PROG=
+VERBOSE=
+
+usage () {
+	echo "Usage: $0 [-hv] <command> [<options>...]"
+}
+
+set_id () {
+	echo "ERROR: $1 is set${2}id. usewithtor will not work on a set${2}id executable." >&2
+	exit 1
+}
 
 # Check for any argument list
-if [ "$#" = 0 ]
-then
-        echo "Usage: $0 <command> [<options>...]" >&2
-        exit 1
-fi
-if [ "$#" = 1 ] && ( [ "$1" = "-h" ] || [ "$1" = "--help" ] )
-then
-        echo "Usage: $0 <command> [<options>...]"
-        exit 0
+if [ "$#" = 0 ]; then
+	usage >&2
+	exit 1
 fi
 
-# Define our torsocks config file
-TSOCKS_CONF_FILE="@CONFDIR@/torsocks.conf"
-export TSOCKS_CONF_FILE
+while [ "$1" ]; do
+	case "$1" in
+		-h|--h*)
+			usage
+			exit 0
+			;;
+		-v|--v*)
+			VERBOSE=YesPlease
+			shift
+			;;
+		*)
+			break;
+	esac
+done
 
-# Check that we've got a torsocks config file
-if [ -r "$TSOCKS_CONF_FILE" ]
-then
-	exec torsocks "$@"
-	echo "$0: Failed to exec torsocks $@" >&2
-	exit 1
+if [ -u `which "$1"` ]; then
+	set_id $1 u
+elif [ -g `which "$1"` ]; then
+	set_id $1 g
+fi
+
+if [ -x "$TORSOCKS" ]; then
+	PROG=torsocks
 else
-	echo "$0: Missing torsocks configuration file \"$TSOCKS_CONF_FILE\"." >&2
+	echo "$0: Unable to find torsocks in PATH." >&2
+	echo "    Perhaps you haven't installed it?" >&2
 	exit 1
 fi
+
+if [ "$VERBOSE" ]; then
+	echo "We're armed with the following torsocks: $TORSOCKS"
+	echo "We're attempting to use $PROG for all tor action."
+fi
+
+if [ "$PROG" = "torsocks" ]; then
+	# Define our torsocks config file
+	TSOCKS_CONF_FILE="@CONFDIR@/torsocks.conf"
+	export TSOCKS_CONF_FILE
+
+	# Check that we've got a torsocks config file
+	if [ -r "$TSOCKS_CONF_FILE" ]; 	then
+		exec torsocks "$@"
+	else
+		echo "$0: Missing torsocks configuration file \"$TSOCKS_CONF_FILE\" - torsocks will use defaults sensible for Tor." >&2
+		exec torsocks "$@"
+	fi
+fi
+
+# We should have hit an exec. If we get here, we didn't exec
+echo "$0: failed to exec $PROG $@" >&2
+exit 1
-- 
1.5.6.5