--- /dev/null
+# $OpenBSD: limit-keytype.sh,v 1.1 2015/01/13 07:49:49 djm Exp $
+# Placed in the Public Domain.
+
+tid="restrict pubkey type"
+
+rm -f $OBJ/authorized_keys_$USER $OBJ/user_ca_key* $OBJ/user_key*
+rm -f $OBJ/authorized_principals_$USER $OBJ/cert_user_key*
+
+mv $OBJ/sshd_proxy $OBJ/sshd_proxy.orig
+mv $OBJ/ssh_proxy $OBJ/ssh_proxy.orig
+
+# Create a CA key
+${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_ca_key ||\
+ fatal "ssh-keygen failed"
+
+# Make some keys and a certificate.
+${SSHKEYGEN} -q -N '' -t ed25519 -f $OBJ/user_key1 || \
+ fatal "ssh-keygen failed"
+${SSHKEYGEN} -q -N '' -t rsa -f $OBJ/user_key2 || \
+ fatal "ssh-keygen failed"
+${SSHKEYGEN} -q -N '' -t rsa -f $OBJ/user_key3 || \
+ fatal "ssh-keygen failed"
+${SSHKEYGEN} -q -s $OBJ/user_ca_key -I "regress user key for $USER" \
+ -z $$ -n ${USER},mekmitasdigoat $OBJ/user_key3 ||
+ fatal "couldn't sign user_key1"
+# Copy the private key alongside the cert to allow better control of when
+# it is offered.
+mv $OBJ/user_key3-cert.pub $OBJ/cert_user_key3.pub
+cp -p $OBJ/user_key3 $OBJ/cert_user_key3
+
+grep -v IdentityFile $OBJ/ssh_proxy.orig > $OBJ/ssh_proxy
+
+opts="-oProtocol=2 -F $OBJ/ssh_proxy -oIdentitiesOnly=yes"
+fullopts="$opts -i $OBJ/cert_user_key3 -i $OBJ/user_key1 -i $OBJ/user_key2"
+
+echo mekmitasdigoat > $OBJ/authorized_principals_$USER
+cat $OBJ/user_key1.pub > $OBJ/authorized_keys_$USER
+cat $OBJ/user_key2.pub >> $OBJ/authorized_keys_$USER
+
+prepare_config() {
+ (
+ grep -v "Protocol" $OBJ/sshd_proxy.orig
+ echo "Protocol 2"
+ echo "AuthenticationMethods publickey"
+ echo "TrustedUserCAKeys $OBJ/user_ca_key.pub"
+ echo "AuthorizedPrincipalsFile $OBJ/authorized_principals_%u"
+ for x in "$@" ; do
+ echo "$x"
+ done
+ ) > $OBJ/sshd_proxy
+}
+
+prepare_config
+
+# Check we can log in with all key types.
+${SSH} $opts -i $OBJ/cert_user_key3 proxy true || fatal "cert failed"
+${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
+${SSH} $opts -i $OBJ/user_key2 proxy true || fatal "key2 failed"
+
+# Allow plain Ed25519 and RSA. The certificate should fail.
+verbose "privsep=$privsep allow rsa,ed25519"
+prepare_config "PubkeyAcceptedKeyTypes ssh-rsa,ssh-ed25519"
+${SSH} $opts -i $OBJ/cert_user_key3 proxy true && fatal "cert succeeded"
+${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
+${SSH} $opts -i $OBJ/user_key2 proxy true || fatal "key2 failed"
+
+# Allow Ed25519 only.
+verbose "privsep=$privsep allow ed25519"
+prepare_config "PubkeyAcceptedKeyTypes ssh-ed25519"
+${SSH} $opts -i $OBJ/cert_user_key3 proxy true && fatal "cert succeeded"
+${SSH} $opts -i $OBJ/user_key1 proxy true || fatal "key1 failed"
+${SSH} $opts -i $OBJ/user_key2 proxy true && fatal "key2 succeeded"
+
+# Allow all certs. Plain keys should fail.
+verbose "privsep=$privsep allow cert only"
+prepare_config "PubkeyAcceptedKeyTypes ssh-*-cert-v01@openssh.com"
+${SSH} $opts -i $OBJ/cert_user_key3 proxy true || fatal "cert failed"
+${SSH} $opts -i $OBJ/user_key1 proxy true && fatal "key1 succeeded"
+${SSH} $opts -i $OBJ/user_key2 proxy true && fatal "key2 succeeded"
+