j-hpn-ssh/regress/integrity.sh

#	$OpenBSD: integrity.sh,v 1.24 2020/01/21 08:06:27 djm Exp $
#	Placed in the Public Domain.

tid="integrity"
cp $OBJ/sshd_proxy $OBJ/sshd_proxy_bak

# start at byte 2900 (i.e. after kex) and corrupt at different offsets
tries=10
startoffset=2900
macs=$(${SSH} -Q mac)

# The following are not MACs, but ciphers with integrated integrity. They are
# handled specially below.
macs="$macs $(${SSH} -Q cipher-auth)"

# avoid DH group exchange as the extra traffic makes it harder to get the
# offset into the stream right.
#echo "KexAlgorithms -diffie-hellman-group*" \
#	>> $OBJ/ssh_proxy

# sshd-command for proxy (see test-exec.sh)
cmd="$SUDO env SSH_SK_HELPER="$SSH_SK_HELPER" sh ${SRC}/sshd-log-wrapper.sh ${TEST_SSHD_LOGFILE} ${SSHD} -i -f $OBJ/sshd_proxy"

for m in $macs; do
	# the none mac is now valid but tests against it will succeed when we expect it to
	# fail. so we need to explicity remove it from the list of macs returned.
	if [ $m == "none" ]; then
		continue
	fi

	trace "test $tid: mac $m"
	elen=0
	epad=0
	emac=0
	etmo=0
	ecnt=0
	skip=0
	for off in $(jot $tries $startoffset); do
		skip=$(expr $skip - 1)
		if [ $skip -gt 0 ]; then
			# avoid modifying the high bytes of the length
			continue
		fi
		cp $OBJ/sshd_proxy_bak $OBJ/sshd_proxy
		# modify output from sshd at offset $off
		pxy="proxycommand=$cmd | $OBJ/modpipe -wm xor:$off:1"
		if ${SSH} -Q cipher-auth | grep "^${m}\$" > /dev/null 2>&1; then
			echo "Ciphers=$m" >> $OBJ/sshd_proxy
			macopt="-c $m"
		else
			echo "Ciphers=aes128-ctr" >> $OBJ/sshd_proxy
			echo "MACs=$m" >> $OBJ/sshd_proxy
			macopt="-m $m -c aes128-ctr"
		fi
		verbose "test $tid: $m @$off"
		${SSH} $macopt -F $OBJ/ssh_proxy -o "$pxy" \
			-oServerAliveInterval=1  -oServerAliveCountMax=30 \
			999.999.999.999  'printf "%4096s" " "' > /dev/null
		if [ $? -eq 0 ]; then
			fail "ssh -m $m succeeds with bit-flip at $off"
		fi
		ecnt=$(expr $ecnt + 1)
		out=$(egrep -v "^debug" $TEST_SSH_LOGFILE | tail -2 |
			tr   -s '\r\n' '.')
		case "$out" in
			Bad?packet*)
				elen=$(        expr $elen + 1)
				skip=3
				;;
			Corrupted?MAC* | *message?authentication?code?incorrect*)
				emac=$(expr $emac + 1)
				skip=0
				;;
			padding*)
				epad=$(     expr $epad + 1)
				skip=0
				;;
			*Timeout,?server*)
				etmo=$(expr $etmo + 1)
				skip=0
				;;
			*) fail "unexpected error mac $m at $off: $out" ;;
		esac
	done
	verbose "test $tid: $ecnt errors: mac $emac padding $epad length $elen timeout $etmo"
	if [ $emac -eq 0 ]; then
		fail "$m: no mac errors"
	fi
	expect=$(expr $ecnt - $epad - $elen - $etmo)
	if [ $emac -ne $expect ]; then
		fail "$m: expected $expect mac errors, got $emac"
	fi
done