package/openssh: manage sshd using start-stop-daemon

The previously used "killall sshd" stopped all instances of sshd. With
OpenSSH before 9.8 that meant not only the listening server, but also
instances serving currently open sessions, possibly including the one
used to send the restart command, preventing it from completing the
"start" part of "restart" and leaving the system unreachable over SSH.

start-stop-daemon uses the PID file to target only the intended
process, and has built-in capability to check if it is running. This
ensures any open SSH sessions are unaffected, as well as unrelated
processes (in case a daemon crashed and the PID got reused).

Signed-off-by: Fiona Klute (WIWA) <fiona.klute@gmx.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

.checkpackageignore

@@ -1103,7 +1103,7 @@ package/openrc/0003-init.d-agetty-replace-sbin-agetty-by-sbin-getty.patch lib_pa
 package/openrc/0004-init.d-agetty-start-agetty-after-all-sevices.patch lib_patch.Upstream
 package/openrc/0005-runlevels-do-not-add-agetty.tty-1-6-if-MKSYSVINIT-ye.patch lib_patch.Upstream
 package/openrc/0006-Also-create-run-lock-subsys-directory.patch lib_patch.Upstream
-package/openssh/S50sshd lib_sysv.EmptyLastLine lib_sysv.Indent lib_sysv.Variables
+package/openssh/S50sshd lib_sysv.Indent
 package/openswan/0001-lib-libopenswan-constants.c-workaround-missing-ns_t_.patch lib_patch.Upstream
 package/opentyrian/0001-Move-definitions-that-don-t-need-to-be-exposed-from-opl-h-to-opl-c.patch lib_patch.Upstream
 package/openvmtools/0001-no_cflags_werror.patch lib_patch.Upstream

package/openssh/S50sshd

@@ -3,6 +3,9 @@
 # sshd        Starts sshd.
 #
 
+DAEMON="sshd"
+PIDFILE="/var/run/$DAEMON.pid"
+
 # Make sure the ssh-keygen progam exists
 [ -f /usr/bin/ssh-keygen ] || exit 0
 
@@ -12,17 +15,35 @@ start() {
 	# Create any missing keys
 	/usr/bin/ssh-keygen -A
 
-	printf "Starting sshd: "
-	/usr/sbin/sshd
-	touch /var/lock/sshd
-	echo "OK"
+	printf "Starting %s: " "$DAEMON"
+	start-stop-daemon -S -q -p "$PIDFILE" \
+		-x "/usr/sbin/$DAEMON"
+	status=$?
+	if [ "$status" -eq 0 ]; then
+		echo "OK"
+	else
+		echo "FAIL"
+	fi
+	return "$status"
 }
+
 stop() {
 	printf "Stopping sshd: "
-	killall sshd
-	rm -f /var/lock/sshd
-	echo "OK"
+	start-stop-daemon -K -q -p "$PIDFILE" \
+		-x "/usr/sbin/$DAEMON"
+	status=$?
+	if [ "$status" -eq 0 ]; then
+		echo "OK"
+	else
+		echo "FAIL"
+	fi
+	# sshd deletes its PID file on exit, wait for it to be gone
+	while [ -f "$PIDFILE" ]; do
+		sleep 0.1
+	done
+	return "$status"
 }
+
 restart() {
 	stop
 	start
@@ -44,4 +65,3 @@ case "$1" in
 esac
 
 exit $?
-