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systemd/units/systemd-timesyncd.service.in
Lennart Poettering abf4e5c1d3 units: turn off DNSSEC validation when timesyncd resolves hostnames
We have a chicken and egg problem: validation of DNSSEC signatures
doesn't work without a correct clock, but to set the correct clock we
need to contact NTP servers which requires resolving a hostname, which
would normally require DNSSEC validation.

Let's break the cycle by excluding NTP hostname resolution from
validation for now.

Of course, this leaves NTP traffic unprotected. To cover that we need
NTPSEC support, which we can add later.

Fixes: #5873 #15607
2021-02-14 22:05:18 +01:00

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1.7 KiB
SYSTEMD

# SPDX-License-Identifier: LGPL-2.1-or-later
#
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
[Unit]
Description=Network Time Synchronization
Documentation=man:systemd-timesyncd.service(8)
ConditionCapability=CAP_SYS_TIME
ConditionVirtualization=!container
DefaultDependencies=no
After=systemd-sysusers.service
Before=time-set.target sysinit.target shutdown.target
Conflicts=shutdown.target
Wants=time-set.target
[Service]
AmbientCapabilities=CAP_SYS_TIME
BusName=org.freedesktop.timesync1
CapabilityBoundingSet=CAP_SYS_TIME
# Turn off DNSSEC validation for hostname look-ups, since those need the
# correct time to work, but we likely won't acquire that without NTP. Let's
# break this chicken-and-egg cycle here.
Environment=SYSTEMD_NSS_RESOLVE_VALIDATE=0
ExecStart=!!@rootlibexecdir@/systemd-timesyncd
LockPersonality=yes
MemoryDenyWriteExecute=yes
NoNewPrivileges=yes
PrivateDevices=yes
PrivateTmp=yes
ProtectProc=invisible
ProtectControlGroups=yes
ProtectHome=yes
ProtectHostname=yes
ProtectKernelLogs=yes
ProtectKernelModules=yes
ProtectKernelTunables=yes
ProtectSystem=strict
Restart=always
RestartSec=0
RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
RestrictNamespaces=yes
RestrictRealtime=yes
RestrictSUIDSGID=yes
RuntimeDirectory=systemd/timesync
StateDirectory=systemd/timesync
SystemCallArchitectures=native
SystemCallErrorNumber=EPERM
SystemCallFilter=@system-service @clock
Type=notify
User=systemd-timesync
@SERVICE_WATCHDOG@
[Install]
WantedBy=sysinit.target
Alias=dbus-org.freedesktop.timesync1.service