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#!/bin/bash
set -e
set -o pipefail
realm="EXAMPLE.FAKE"
myhostname="sshd-gssapi.${realm,,}"
testuser="testuser$$"
testuser2="testuser$$-2"
adduser --quiet --disabled-password --gecos "" "${testuser}"
adduser --quiet --disabled-password --gecos "" "${testuser2}"
password="secret"
user_principal="${testuser}@${realm}"
service_principal="host/${myhostname}"
ssh-keygen -t ed25519 -N '' -f "$HOME/.ssh/id_ed25519"
runuser -u "$testuser2" -- mkdir -m700 "/home/$testuser2/.ssh"
cp "$HOME/.ssh/id_ed25519.pub" "/home/$testuser2/.ssh/authorized_keys"
chown "$testuser2:" "/home/$testuser2/.ssh/authorized_keys"
source debian/tests/util
cleanup() {
if [ $? -ne 0 ]; then
echo "## Something failed"
echo
echo "## klist"
klist
echo
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echo "## ssh server log"
journalctl -b -u ssh.service --lines 100
echo
echo "## Kerberos KDC logs"
journalctl -b -u krb5-kdc.service --lines 100
echo
echo "## Kerberos Admin server logs"
journalctl -b -u krb5-admin-server.service --lines 100
echo
echo "## Skipping cleanup to facilitate troubleshooting"
else
echo "## ALL TESTS PASSED"
echo "## Cleaning up"
rm -f /etc/krb5.keytab
rm -f /etc/ssh/sshd_config.d/gssapi.conf
rm -f /etc/ssh/ssh_config.d/gssapi.conf
rm -f /etc/ssh/ssh_config.d/dep8.conf
fi
}
trap cleanup EXIT
setup() {
echo "## Setting up test environment"
adjust_hostname "${myhostname}"
echo "## Creating Kerberos realm ${realm}"
create_realm "${realm}" "${myhostname}"
echo "## Creating principals"
kadmin.local -q "addprinc -clearpolicy -pw ${password} ${user_principal}"
kadmin.local -q "addprinc -clearpolicy -randkey ${service_principal}"
echo "## Extracting service principal ${service_principal}"
kadmin.local -q "ktadd -k /etc/krb5.keytab ${service_principal}"
cat > /etc/ssh/ssh_config.d/dep8.conf <<EOF
Host *
StrictHostKeyChecking no
UserKnownHostsFile /dev/null
EOF
echo "## Adjusting /etc/krb5.conf"
cat > /etc/krb5.conf <<EOF
[libdefaults]
default_realm = ${realm}
rdns = false
forwardable = true
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dns_uri_lookup = false
dns_lookup_realm = false
[realms]
${realm} = {
kdc = ${myhostname}
admin_server = ${myhostname}
}
EOF
}
configure_sshd() {
local auth_method="${1}"
if [ "${auth_method}" = "gssapi-with-mic" ]; then
# server
echo "## Configuring sshd for ${auth_method} authentication"
cat > /etc/ssh/sshd_config.d/gssapi.conf <<EOF
GSSAPIAuthentication yes
GSSAPIKeyExchange no
GSSAPICleanupCredentials yes
EOF
# client
cat > /etc/ssh/ssh_config.d/gssapi.conf <<EOF
Host *
GSSAPIAuthentication yes
GSSAPIKeyExchange no
EOF
elif [ "${auth_method}" = "gssapi-keyex" ]; then
# server
echo "## Configuring sshd for ${auth_method} authentication"
cat > /etc/ssh/sshd_config.d/gssapi.conf <<EOF
GSSAPIAuthentication yes
GSSAPIKeyExchange yes
GSSAPICleanupCredentials yes
EOF
# client
cat > /etc/ssh/ssh_config.d/gssapi.conf <<EOF
Host *
GSSAPIAuthentication yes
GSSAPIKeyExchange yes
EOF
else
echo "## ERROR: unknown auth_method \"${auth_method}\""
return 1
fi
echo "## Restarting ssh"
systemctl restart ssh.service
}
_test_ssh_login() {
local initial_auth_method="${1}"
local user="${2}"
local final_auth_method="${3}"
local cursor
kdestroy 2>/dev/null || :
configure_sshd "${initial_auth_method}" || return $?
cursor="$(journalctl -u ssh.service --lines=1 --show-cursor | sed -n 's/^-- cursor: //p')"
echo "## Obtaining TGT"
echo "${password}" | timeout --verbose 30 kinit "${user_principal}" || return $?
klist
echo
echo "## ssh'ing into localhost using ${initial_auth_method} auth"
timeout --verbose 30 ssh "${user}@${myhostname}" date || return $?
echo
echo "## checking that we got a service ticket for ssh (host/)"
klist | grep -F "${service_principal}" || return $?
echo
echo "## Checking ssh logs to confirm ${final_auth_method} auth was used"
journalctl -u ssh.service --after-cursor="$cursor" --grep "Accepted ${final_auth_method}"
}
test_gssapi_login() {
_test_ssh_login gssapi-with-mic "${testuser}" gssapi-with-mic
}
test_gssapi_keyex_login() {
_test_ssh_login gssapi-keyex "${testuser}" gssapi-keyex
}
test_gssapi_keyex_pubkey_fallback() {
# GSS-API key exchange for the wrong user, falling back to public key
# authentication for the right user.
_test_ssh_login gssapi-keyex "${testuser2}" publickey
}
setup
echo "## TESTS"
echo
run_test test_gssapi_login
run_test test_gssapi_keyex_login
run_test test_gssapi_keyex_pubkey_fallback