PAM: support password changes even when not mounted

There's usually no requirement that a user be logged in for changing
their password, so let's not be surprising here.

We need to use the fetch_lazy mechanism for the old password to avoid
a double prompt for it, so that mechanism is now generalized a bit.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Felix Dörre <felix@dogcraft.de>
Signed-off-by: Val Packett <val@packett.cool>
Closes #14834

tests/runfiles/linux.run

@@ -140,7 +140,8 @@ tests = ['umount_unlinked_drain']
 tags = ['functional', 'mount']
 
 [tests/functional/pam:Linux]
-tests = ['pam_basic', 'pam_nounmount', 'pam_recursive', 'pam_short_password']
+tests = ['pam_basic', 'pam_change_unmounted', 'pam_nounmount', 'pam_recursive',
+    'pam_short_password']
 tags = ['functional', 'pam']
 
 [tests/functional/procfs:Linux]

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

@@ -0,0 +1,55 @@
+#!/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 https://opensource.org/licenses/CDDL-1.0.
+# 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
+#
+
+. $STF_SUITE/tests/functional/pam/utilities.kshlib
+
+if [ -n "$ASAN_OPTIONS" ]; then
+	export LD_PRELOAD=$(ldd "$(command -v zfs)" | awk '/libasan\.so/ {print $3}')
+fi
+
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+genconfig "homes=$TESTPOOL/pam runstatedir=${runstatedir}"
+
+printf "testpass\nsecondpass\nsecondpass\n" | pamtester -v ${pamservice} ${username} chauthtok
+
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+echo "secondpass" | pamtester ${pamservice} ${username} open_session
+references 1
+log_must ismounted "$TESTPOOL/pam/${username}"
+keystatus available
+
+printf "secondpass\ntestpass\ntestpass\n" | pamtester -v ${pamservice} ${username} chauthtok
+
+log_must ismounted "$TESTPOOL/pam/${username}"
+log_must ismounted "$TESTPOOL/pam/${username}"
+keystatus available
+
+log_must pamtester ${pamservice} ${username} close_session
+references 0
+log_mustnot ismounted "$TESTPOOL/pam/${username}"
+keystatus unavailable
+
+log_pass "done."

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

@@ -52,7 +52,7 @@ log_must ismounted "$TESTPOOL/pam/${username}"
 keystatus available
 
 # Change user and dataset password to short one.
-printf "short\nshort\n" | pamtester ${pamservice} ${username} chauthtok
+printf "testpass\nshort\nshort\n" | pamtester -v ${pamservice} ${username} chauthtok
 
 # Unmount and unload key.
 log_must pamtester ${pamservice} ${username} close_session