pam_zfs_key: tests: check if zfs load-key works on short passphrases

The pam_zfs_key pam module does not enforce a minimum password
length while changing the user password and thus the users home
dataset passphrase. To not end up with a dateset `zfs load-key`
can't load the key for, `zfs load-key` should not enforce a minimum
passphrase length. This adds a test for that.

Reviewed-by: Felix Dörre <felix@dogcraft.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #12765
Closes #12651
Closes #12656

tests/runfiles/linux.run

@@ -125,7 +125,7 @@ tests = ['umount_unlinked_drain']
 tags = ['functional', 'mount']
 
 [tests/functional/pam:Linux]
-tests = ['pam_basic', 'pam_nounmount']
+tests = ['pam_basic', 'pam_nounmount', 'pam_short_password']
 tags = ['functional', 'pam']
 
 [tests/functional/procfs:Linux]

tests/zfs-tests/tests/functional/pam/Makefile.am

@@ -4,4 +4,5 @@ dist_pkgdata_SCRIPTS = \
 	cleanup.ksh \
 	pam_basic.ksh \
 	pam_nounmount.ksh \
+	pam_short_password.ksh \
 	utilities.kshlib

tests/zfs-tests/tests/functional/pam/pam_short_password.ksh

@@ -0,0 +1,84 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or http://www.opensolaris.org/os/licensing.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Copyright 2021 Attila Fülöp <attila@fueloep.org>
+#
+
+
+. $STF_SUITE/tests/functional/pam/utilities.kshlib
+
+if [[ -z pamservice ]]; then
+	pamservice=pam_zfs_key_test
+fi
+
+# DESCRIPTION:
+# If we set the encryption passphrase for a dataset via pam_zfs_key, a minimal
+# passphrase length isn't enforced. This leads to a non-loadable key if
+# `zfs load-key` enforces a minimal length. Make sure this isn't the case.
+
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+genconfig "homes=$TESTPOOL/pam runstatedir=${runstatedir}"
+
+# Load keys and mount userdir.
+echo "testpass" | pamtester ${pamservice} ${username} open_session
+references 1
+log_must ismounted "$TESTPOOL/pam/${username}"
+keystatus available
+
+# Change user and dataset password to short one.
+printf "short\nshort\n" | pamtester ${pamservice} ${username} chauthtok
+
+# Unmount and unload key.
+log_must pamtester ${pamservice} ${username} close_session
+references 0
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+# Check if password change succeeded.
+echo "testpass" | pamtester ${pamservice} ${username} open_session
+references 1
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+log_must pamtester ${pamservice} ${username} close_session
+references 0
+
+echo "short" | pamtester ${pamservice} ${username} open_session
+references 1
+log_must ismounted "$TESTPOOL/pam/${username}"
+keystatus available
+
+
+# Finally check if `zfs load-key` succeeds with the short password.
+log_must pamtester ${pamservice} ${username} close_session
+references 0
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+echo "short" | zfs load-key "$TESTPOOL/pam/${username}"
+keystatus available
+zfs unload-key "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+log_pass "done."