Merge pull request #23 from rfjakob/master

Add integration tests & Compare MACs in constant time

encfs/MACFileIO.cpp

@@ -206,12 +206,18 @@ ssize_t MACFileIO::readOneBlock( const IORequest &req ) const
             uint64_t mac = cipher->MAC_64( tmp.data + macBytes, 
                     readSize - macBytes, key );
 
+            // Constant time comparision to prevent timing attacks
+            unsigned char fail = 0;
             for(int i=0; i<macBytes; ++i, mac >>= 8)
             {
                 int test = mac & 0xff;
                 int stored = tmp.data[i];
-                if(test != stored)
+
-                {
+                fail |= (test ^ stored);
+            }
+
+            if( fail > 0 )
+            {
                     // uh oh.. 
                     long blockNum = req.offset / bs;
                     rWarning(_("MAC comparison failure in block %li"), 
@@ -222,8 +228,6 @@ ssize_t MACFileIO::readOneBlock( const IORequest &req ) const
                         throw ERROR(
                                 _("MAC comparison failure, refusing to read"));
                     }
-                    break;
-                }
             }
         }
 

tests/default.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<!DOCTYPE boost_serialization>
+<boost_serialization signature="serialization::archive" version="10">
+<cfg class_id="0" tracking_level="0" version="20">
+	<version>20100713</version>
+	<creator>EncFS 1.7.5</creator>
+	<cipherAlg class_id="1" tracking_level="0" version="0">
+		<name>ssl/aes</name>
+		<major>3</major>
+		<minor>0</minor>
+	</cipherAlg>
+	<nameAlg>
+		<name>nameio/block</name>
+		<major>4</major>
+		<minor>0</minor>
+	</nameAlg>
+	<keySize>192</keySize>
+	<blockSize>1024</blockSize>
+	<uniqueIV>1</uniqueIV>
+	<chainedNameIV>1</chainedNameIV>
+	<externalIVChaining>0</externalIVChaining>
+	<blockMACBytes>0</blockMACBytes>
+	<blockMACRandBytes>0</blockMACRandBytes>
+	<allowHoles>1</allowHoles>
+	<encodedKeySize>44</encodedKeySize>
+	<encodedKeyData>
+AL2iRMLYyuf7RXcFCK0CcegQ/+enbaaqTq1OY3WULMLpcz0yvo8K4KtVw7c=
+	</encodedKeyData>
+	<saltLen>20</saltLen>
+	<saltData>
+RVCTqJyxxp7ZN0AsLJhgpvSuUB8=
+	</saltData>
+	<kdfIterations>170562</kdfIterations>
+	<desiredKDFDuration>500</desiredKDFDuration>
+</cfg>
+</boost_serialization>
+

tests/mac.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes" ?>
+<!DOCTYPE boost_serialization>
+<boost_serialization signature="serialization::archive" version="10">
+<cfg class_id="0" tracking_level="0" version="20">
+	<version>20100713</version>
+	<creator>EncFS 1.7.5</creator>
+	<cipherAlg class_id="1" tracking_level="0" version="0">
+		<name>ssl/aes</name>
+		<major>3</major>
+		<minor>0</minor>
+	</cipherAlg>
+	<nameAlg>
+		<name>nameio/block</name>
+		<major>4</major>
+		<minor>0</minor>
+	</nameAlg>
+	<keySize>192</keySize>
+	<blockSize>1024</blockSize>
+	<uniqueIV>1</uniqueIV>
+	<chainedNameIV>1</chainedNameIV>
+	<externalIVChaining>0</externalIVChaining>
+	<blockMACBytes>8</blockMACBytes>
+	<blockMACRandBytes>0</blockMACRandBytes>
+	<allowHoles>1</allowHoles>
+	<encodedKeySize>44</encodedKeySize>
+	<encodedKeyData>
+AL2iRMLYyuf7RXcFCK0CcegQ/+enbaaqTq1OY3WULMLpcz0yvo8K4KtVw7c=
+	</encodedKeyData>
+	<saltLen>20</saltLen>
+	<saltData>
+RVCTqJyxxp7ZN0AsLJhgpvSuUB8=
+	</saltData>
+	<kdfIterations>170562</kdfIterations>
+	<desiredKDFDuration>500</desiredKDFDuration>
+</cfg>
+</boost_serialization>
+

tests/run.sh

@@ -0,0 +1,109 @@
+#!/bin/bash
+
+# This is the wrapper script for all tests.
+# It calls the unit tests and all integration tests.
+#
+# Functions that are useful in more than one integration test
+# should be defined here.
+
+set -eu
+
+# Set up envrionment variables, cd to the correct directory
+function init {
+
+	# Make sure we are in the "tests" directory
+	TESTDIR=$(dirname $(realpath "$0"))
+	cd $TESTDIR
+
+	# Full path to encfs binary
+	ENCFS=$(realpath ../encfs/encfs)
+
+	# Directory for temporary files (scratch)
+	SCRATCH=$(realpath scratch)
+	LOWER=$SCRATCH/lower
+	UPPER=$SCRATCH/upper
+
+	# Test number counter
+	TESTNO=1
+
+	trap 'echo -e "***\e[31m test(s) FAILED\e[0m"' ERR
+}
+
+# Run all test_*.sh files
+function run_cli_tests {
+
+	cd $TESTDIR
+	for i in $(echo test_*.sh)
+	do
+		cleanup
+		mkdir $SCRATCH
+		echo "*** running $i"
+		source $i
+	done
+}
+
+# fresh_mount CONFIG
+#
+# Mount a fresh, empty encfs filesystem using the encfs config file
+# CONFIG as .encfs6.xml. The password must be set to "a".
+# The backing files will be at $LOWER, the mounted filesystem at $UPPER.
+function fresh_mount {
+	cd $TESTDIR
+	fusermount -q -u $UPPER 2> /dev/null || true
+	wait
+	rm -Rf $LOWER $UPPER
+	mkdir -p $LOWER $UPPER
+	touch $UPPER/not_yet_mounted
+
+	cp $TESTDIR/$1 $SCRATCH/lower/.encfs6.xml
+
+	echo a | $ENCFS -f -S -o nonempty $LOWER $UPPER 2> /dev/null &
+	while [ -e $UPPER/not_yet_mounted ]
+	do
+		sleep 0.1s
+	done
+}
+
+# Clean up scratch directory
+function cleanup {
+	test -d $SCRATCH || return 0
+
+	cd $SCRATCH/..
+	fusermount -q -u $UPPER 2> /dev/null || true
+	wait
+	rm -Rf $SCRATCH
+}
+
+# Get the plain MD5 sum of a file, without the filename that is output
+# by md5sum
+# md5sum foo:    5f47bbbd6db883f93f5d00fd05f149ff  foo
+# plain_md5 foo: 5f47bbbd6db883f93f5d00fd05f149ff
+function md5 {
+	OUTPUT=$(md5sum "$1") # Capture md5sum output
+	ARRAY=($OUTPUT)       # Split into array
+	echo ${ARRAY[0]}      # Return first element
+}
+
+# Indicate beginning of a test
+# Prints test number and title
+function test_begin {
+	echo -n "$TESTNO $1: "
+	let TESTNO++
+}
+
+# Indicate successful completion of a test
+function test_ok {
+	echo "OK"
+}
+
+init
+
+test_begin "Running unit tests"
+../encfs/test 2> /dev/null
+test_ok
+
+run_cli_tests
+
+echo -e "***\e[32m All tests OK\e[0m"
+
+cleanup

tests/test_corruption.sh

@@ -0,0 +1,31 @@
+fresh_mount default.xml
+cd $SCRATCH
+dd if=/dev/urandom of=foo bs=1M count=1 2> /dev/null
+A=$(md5 foo)
+cp foo $UPPER
+cd $UPPER
+test_begin "Reading file"
+B=$(md5 foo)
+test $A = $B
+test_ok
+
+test_begin "Reading corrupted file"
+echo DEADBEEF >> $LOWER/$(ls $LOWER)
+B=$(md5 foo)
+test $A != $B
+test_ok
+
+fresh_mount mac.xml
+cd $SCRATCH
+cp foo $UPPER
+cd $UPPER
+test_begin "Reading file with MAC"
+B=$(md5 foo)
+test $A = $B
+test_ok
+
+test_begin "Corruption with MAC returns IO error"
+echo DEADBEEF >> $LOWER/$(ls $LOWER)
+md5 foo 2>&1 | grep "Input/output error" > /dev/null
+test_ok
+

tests/test_file_expansion.sh

@@ -0,0 +1,40 @@
+fresh_mount default.xml
+cd $UPPER
+test_begin "Creating files of different sizes: "
+for i in `seq 0 50` `seq 1000 1050`
+do
+	OUTPUT=$(dd if=/dev/zero bs=$i count=1 2> /dev/null | tee $i | md5sum)
+	ARRAY=($OUTPUT)
+	A=${ARRAY[0]} # Remove filename
+	B=$(md5 $i)
+	test $A = $B
+done
+test_ok
+
+test_begin "Growing file"
+rm -f ../grow
+for i in `seq 0 300`
+do
+	echo -n "abcdefg" >> ../grow
+	echo -n "abcdefg" >> grow
+	
+	A=$(md5 ../grow)
+	B=$(md5 grow)
+	test "$A" = "$B"
+done
+test_ok
+
+test_begin "Internal modification"
+dd if=/dev/urandom of=../internal bs=1M count=2 2> /dev/null
+cp ../internal internal
+for i in 0 30 1020 1200
+do
+	dd if=/dev/zero of=../internal bs=1 count=1 skip=$i 2> /dev/null
+	dd if=/dev/zero of=internal bs=1 count=1 skip=$i 2> /dev/null
+
+	A=$(md5 ../internal)
+	B=$(md5 internal)
+	test "$A" = "$B"
+done
+test_ok
+