cert-hostkey.sh

#	$OpenBSD: cert-hostkey.sh,v 1.14 2016/05/02 09:52:00 djm Exp $
#	Placed in the Public Domain.

tid="certified host keys"

rm -f $OBJ/known_hosts-cert* $OBJ/host_ca_key* $OBJ/host_revoked_*
rm -f $OBJ/cert_host_key* $OBJ/host_krl_*

# Allow all hostkey/pubkey types, prefer certs for the client
types=""
for i in `$SSH -Q key`; do
	if [ -z "$types" ]; then
		types="$i"
		continue
	fi
	case "$i" in
	*cert*)	types="$i,$types";;
	*)	types="$types,$i";;
	esac
done
(
	echo "HostKeyAlgorithms ${types}"
	echo "PubkeyAcceptedKeyTypes *"
) >> $OBJ/ssh_proxy
cp $OBJ/sshd_proxy $OBJ/sshd_proxy_bak
(
	echo "HostKeyAlgorithms *"
	echo "PubkeyAcceptedKeyTypes *"
) >> $OBJ/sshd_proxy_bak

HOSTS='localhost-with-alias,127.0.0.1,::1'

kh_ca() {
	for k in "$@" ; do
		printf "@cert-authority $HOSTS "
		cat $OBJ/$k || fatal "couldn't cat $k"
	done
}
kh_revoke() {
	for k in "$@" ; do
		printf "@revoked * "
		cat $OBJ/$k || fatal "couldn't cat $k"
	done
}

# Create a CA key and add it to known hosts. Ed25519 chosen for speed.
# RSA for testing RSA/SHA2 signatures.
${SSHKEYGEN} -q -N '' -t ed25519  -f $OBJ/host_ca_key ||\
	fail "ssh-keygen of host_ca_key failed"
${SSHKEYGEN} -q -N '' -t rsa  -f $OBJ/host_ca_key2 ||\
	fail "ssh-keygen of host_ca_key failed"

kh_ca host_ca_key.pub host_ca_key2.pub > $OBJ/known_hosts-cert.orig
cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert

# Plain text revocation files
touch $OBJ/host_revoked_empty
touch $OBJ/host_revoked_plain
touch $OBJ/host_revoked_cert
cat $OBJ/host_ca_key.pub $OBJ/host_ca_key2.pub > $OBJ/host_revoked_ca

PLAIN_TYPES=`$SSH -Q key-plain | sed 's/^ssh-dss/ssh-dsa/g;s/^ssh-//'`

if echo "$PLAIN_TYPES" | grep '^rsa$' >/dev/null 2>&1 ; then
	PLAIN_TYPES="$PLAIN_TYPES rsa-sha2-256 rsa-sha2-512"
fi

# Prepare certificate, plain key and CA KRLs
${SSHKEYGEN} -kf $OBJ/host_krl_empty || fatal "KRL init failed"
${SSHKEYGEN} -kf $OBJ/host_krl_plain || fatal "KRL init failed"
${SSHKEYGEN} -kf $OBJ/host_krl_cert || fatal "KRL init failed"
${SSHKEYGEN} -kf $OBJ/host_krl_ca $OBJ/host_ca_key.pub $OBJ/host_ca_key2.pub \
	|| fatal "KRL init failed"

# Generate and sign host keys
serial=1
for ktype in $PLAIN_TYPES ; do
	verbose "$tid: sign host ${ktype} cert"
	# Generate and sign a host key
	${SSHKEYGEN} -q -N '' -t ${ktype} \
	    -f $OBJ/cert_host_key_${ktype} || \
		fatal "ssh-keygen of cert_host_key_${ktype} failed"
	${SSHKEYGEN} -ukf $OBJ/host_krl_plain \
	    $OBJ/cert_host_key_${ktype}.pub || fatal "KRL update failed"
	cat $OBJ/cert_host_key_${ktype}.pub >> $OBJ/host_revoked_plain
	case $ktype in
	rsa-sha2-*)	tflag="-t $ktype"; ca="$OBJ/host_ca_key2" ;;
	*)		tflag=""; ca="$OBJ/host_ca_key" ;;
	esac
	${SSHKEYGEN} -h -q -s $ca -z $serial $tflag \
	    -I "regress host key for $USER" \
	    -n $HOSTS $OBJ/cert_host_key_${ktype} ||
		fatal "couldn't sign cert_host_key_${ktype}"
	${SSHKEYGEN} -ukf $OBJ/host_krl_cert \
	    $OBJ/cert_host_key_${ktype}-cert.pub || \
		fatal "KRL update failed"
	cat $OBJ/cert_host_key_${ktype}-cert.pub >> $OBJ/host_revoked_cert
	serial=`expr $serial + 1`
done

attempt_connect() {
	_ident="$1"
	_expect_success="$2"
	shift; shift
	verbose "$tid: $_ident expect success $_expect_success"
	cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
	${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
	    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
	    "$@" -F $OBJ/ssh_proxy somehost true
	_r=$?
	if [ "x$_expect_success" = "xyes" ] ; then
		if [ $_r -ne 0 ]; then
			fail "ssh cert connect $_ident failed"
		fi
	else
		if [ $_r -eq 0 ]; then
			fail "ssh cert connect $_ident succeeded unexpectedly"
		fi
	fi
}

# Basic connect and revocation tests.
for privsep in yes no ; do
	for ktype in $PLAIN_TYPES ; do
		verbose "$tid: host ${ktype} cert connect privsep $privsep"
		(
			cat $OBJ/sshd_proxy_bak
			echo HostKey $OBJ/cert_host_key_${ktype}
			echo HostCertificate $OBJ/cert_host_key_${ktype}-cert.pub
			echo UsePrivilegeSeparation $privsep
		) > $OBJ/sshd_proxy

		#               test name                         expect success
		attempt_connect "$ktype basic connect"			"yes"
		attempt_connect "$ktype empty KRL"			"yes" \
		    -oRevokedHostKeys=$OBJ/host_krl_empty
		attempt_connect "$ktype KRL w/ plain key revoked"	"no" \
		    -oRevokedHostKeys=$OBJ/host_krl_plain
		attempt_connect "$ktype KRL w/ cert revoked"		"no" \
		    -oRevokedHostKeys=$OBJ/host_krl_cert
		attempt_connect "$ktype KRL w/ CA revoked"		"no" \
		    -oRevokedHostKeys=$OBJ/host_krl_ca
		attempt_connect "$ktype empty plaintext revocation"	"yes" \
		    -oRevokedHostKeys=$OBJ/host_revoked_empty
		attempt_connect "$ktype plain key plaintext revocation"	"no" \
		    -oRevokedHostKeys=$OBJ/host_revoked_plain
		attempt_connect "$ktype cert plaintext revocation"	"no" \
		    -oRevokedHostKeys=$OBJ/host_revoked_cert
		attempt_connect "$ktype CA plaintext revocation"	"no" \
		    -oRevokedHostKeys=$OBJ/host_revoked_ca
	done
done

# Revoked certificates with key present
kh_ca host_ca_key.pub host_ca_key2.pub > $OBJ/known_hosts-cert.orig
for ktype in $PLAIN_TYPES ; do
	test -f "$OBJ/cert_host_key_${ktype}.pub" || fatal "no pubkey"
	kh_revoke cert_host_key_${ktype}.pub >> $OBJ/known_hosts-cert.orig
done
cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
for privsep in yes no ; do
	for ktype in $PLAIN_TYPES ; do
		verbose "$tid: host ${ktype} revoked cert privsep $privsep"
		(
			cat $OBJ/sshd_proxy_bak
			echo HostKey $OBJ/cert_host_key_${ktype}
			echo HostCertificate $OBJ/cert_host_key_${ktype}-cert.pub
			echo UsePrivilegeSeparation $privsep
		) > $OBJ/sshd_proxy

		cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
		${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
		    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
			-F $OBJ/ssh_proxy somehost true >/dev/null 2>&1
		if [ $? -eq 0 ]; then
			fail "ssh cert connect succeeded unexpectedly"
		fi
	done
done

# Revoked CA
kh_ca host_ca_key.pub host_ca_key2.pub > $OBJ/known_hosts-cert.orig
kh_revoke host_ca_key.pub host_ca_key2.pub >> $OBJ/known_hosts-cert.orig
cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
for ktype in $PLAIN_TYPES ; do
	verbose "$tid: host ${ktype} revoked cert"
	(
		cat $OBJ/sshd_proxy_bak
		echo HostKey $OBJ/cert_host_key_${ktype}
		echo HostCertificate $OBJ/cert_host_key_${ktype}-cert.pub
	) > $OBJ/sshd_proxy
	cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
	${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
	    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
		-F $OBJ/ssh_proxy somehost true >/dev/null 2>&1
	if [ $? -eq 0 ]; then
		fail "ssh cert connect succeeded unexpectedly"
	fi
done

# Create a CA key and add it to known hosts
kh_ca host_ca_key.pub host_ca_key2.pub > $OBJ/known_hosts-cert.orig
cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert

test_one() {
	ident=$1
	result=$2
	sign_opts=$3

	for kt in rsa ed25519 ; do
		case $ktype in
		rsa-sha2-*)	tflag="-t $ktype"; ca="$OBJ/host_ca_key2" ;;
		*)		tflag=""; ca="$OBJ/host_ca_key" ;;
		esac
		${SSHKEYGEN} -q -s $ca $tflag -I "regress host key for $USER" \
		    $sign_opts $OBJ/cert_host_key_${kt} ||
			fatal "couldn't sign cert_host_key_${kt}"
		(
			cat $OBJ/sshd_proxy_bak
			echo HostKey $OBJ/cert_host_key_${kt}
			echo HostCertificate $OBJ/cert_host_key_${kt}-cert.pub
		) > $OBJ/sshd_proxy

		cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
		${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
		    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
		    -F $OBJ/ssh_proxy somehost true >/dev/null 2>&1
		rc=$?
		if [ "x$result" = "xsuccess" ] ; then
			if [ $rc -ne 0 ]; then
				fail "ssh cert connect $ident failed unexpectedly"
			fi
		else
			if [ $rc -eq 0 ]; then
				fail "ssh cert connect $ident succeeded unexpectedly"
			fi
		fi
	done
}

test_one "user-certificate"	failure "-n $HOSTS"
test_one "empty principals"	success "-h"
test_one "wrong principals"	failure "-h -n foo"
test_one "cert not yet valid"	failure "-h -V20200101:20300101"
test_one "cert expired"		failure "-h -V19800101:19900101"
test_one "cert valid interval"	success "-h -V-1w:+2w"
test_one "cert has constraints"	failure "-h -Oforce-command=false"

# Check downgrade of cert to raw key when no CA found
for ktype in $PLAIN_TYPES ; do
	rm -f $OBJ/known_hosts-cert $OBJ/cert_host_key*
	verbose "$tid: host ${ktype} ${v} cert downgrade to raw key"
	# Generate and sign a host key
	${SSHKEYGEN} -q -N '' -t ${ktype} -f $OBJ/cert_host_key_${ktype} || \
		fail "ssh-keygen of cert_host_key_${ktype} failed"
	case $ktype in
	rsa-sha2-*)	tflag="-t $ktype"; ca="$OBJ/host_ca_key2" ;;
	*)		tflag=""; ca="$OBJ/host_ca_key" ;;
	esac
	${SSHKEYGEN} -h -q $tflag -s $ca $tflag \
	    -I "regress host key for $USER" \
	    -n $HOSTS $OBJ/cert_host_key_${ktype} ||
		fatal "couldn't sign cert_host_key_${ktype}"
	(
		printf "$HOSTS "
		cat $OBJ/cert_host_key_${ktype}.pub
	) > $OBJ/known_hosts-cert
	(
		cat $OBJ/sshd_proxy_bak
		echo HostKey $OBJ/cert_host_key_${ktype}
		echo HostCertificate $OBJ/cert_host_key_${ktype}-cert.pub
	) > $OBJ/sshd_proxy

	${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
	    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
		-F $OBJ/ssh_proxy somehost true
	if [ $? -ne 0 ]; then
		fail "ssh cert connect failed"
	fi
done

# Wrong certificate
kh_ca host_ca_key.pub host_ca_key2.pub > $OBJ/known_hosts-cert.orig
cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
for kt in $PLAIN_TYPES ; do
	verbose "$tid: host ${kt} connect wrong cert"
	rm -f $OBJ/cert_host_key*
	# Self-sign key
	${SSHKEYGEN} -q -N '' -t ${kt} -f $OBJ/cert_host_key_${kt} || \
		fail "ssh-keygen of cert_host_key_${kt} failed"
	case $kt in
	rsa-sha2-*)	tflag="-t $kt" ;;
	*)		tflag="" ;;
	esac
	${SSHKEYGEN} $tflag -h -q -s $OBJ/cert_host_key_${kt} \
	    -I "regress host key for $USER" \
	    -n $HOSTS $OBJ/cert_host_key_${kt} ||
		fatal "couldn't sign cert_host_key_${kt}"
	(
		cat $OBJ/sshd_proxy_bak
		echo HostKey $OBJ/cert_host_key_${kt}
		echo HostCertificate $OBJ/cert_host_key_${kt}-cert.pub
	) > $OBJ/sshd_proxy

	cp $OBJ/known_hosts-cert.orig $OBJ/known_hosts-cert
	${SSH} -2 -oUserKnownHostsFile=$OBJ/known_hosts-cert \
	    -oGlobalKnownHostsFile=$OBJ/known_hosts-cert \
		-F $OBJ/ssh_proxy -q somehost true >/dev/null 2>&1
	if [ $? -eq 0 ]; then
		fail "ssh cert connect $ident succeeded unexpectedly"
	fi
done

rm -f $OBJ/known_hosts-cert* $OBJ/host_ca_key* $OBJ/cert_host_key*