systemd/units/systemd-random-seed.service.in

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2017-11-19 00:35:03 +08:00
# SPDX-License-Identifier: LGPL-2.1+
#
# 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=Load/Save Random Seed
Documentation=man:systemd-random-seed.service(8) man:random(4)
DefaultDependencies=no
RequiresMountsFor=@RANDOM_SEED@
Conflicts=shutdown.target
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After=systemd-remount-fs.service
Before=shutdown.target
ConditionVirtualization=!container
[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=@rootlibexecdir@/systemd-random-seed load
ExecStop=@rootlibexecdir@/systemd-random-seed save
random-seed: rework systemd-random-seed.service substantially This makes two major changes to the way systemd-random-seed operates: 1. We now optionally credit entropy if this is configured (via an env var). Previously we never would do that, with this change we still don't by default, but it's possible to enable this if people acknowledge that they shouldn't replicate an image with a contained random seed to multiple systems. Note that in this patch crediting entropy is a boolean thing (unlike in previous attempts such as #1062), where only a relative amount of bits was credited. The simpler scheme implemented here should be OK though as the random seeds saved to disk are now written only with data from the kernel's entropy pool retrieved after the pool is fully initialized. Specifically: 2. This makes systemd-random-seed.service a synchronization point for kernel entropy pool initialization. It was already used like this, for example by systemd-cryptsetup-generator's /dev/urandom passphrase handling, with this change it explicitly operates like that (at least systems which provide getrandom(), where we can support this). This means services that rely on an initialized random pool should now place After=systemd-random-seed.service and everything should be fine. Note that with this change sysinit.target (and thus early boot) is NOT systematically delayed until the entropy pool is initialized, i.e. regular services need to add explicit ordering deps on this service if they require an initialized random pool. Fixes: #4271 Replaces: #10621 #4513
2019-07-22 19:51:30 +08:00
# This service waits until the kernel's entropy pool is initialized, and may be
# used as ordering barrier for service that require an initialized entropy
# pool. Since initialization can take a while on entropy-starved systems, let's
# increase the timeout substantially here.
random-seed: rework systemd-random-seed.service substantially This makes two major changes to the way systemd-random-seed operates: 1. We now optionally credit entropy if this is configured (via an env var). Previously we never would do that, with this change we still don't by default, but it's possible to enable this if people acknowledge that they shouldn't replicate an image with a contained random seed to multiple systems. Note that in this patch crediting entropy is a boolean thing (unlike in previous attempts such as #1062), where only a relative amount of bits was credited. The simpler scheme implemented here should be OK though as the random seeds saved to disk are now written only with data from the kernel's entropy pool retrieved after the pool is fully initialized. Specifically: 2. This makes systemd-random-seed.service a synchronization point for kernel entropy pool initialization. It was already used like this, for example by systemd-cryptsetup-generator's /dev/urandom passphrase handling, with this change it explicitly operates like that (at least systems which provide getrandom(), where we can support this). This means services that rely on an initialized random pool should now place After=systemd-random-seed.service and everything should be fine. Note that with this change sysinit.target (and thus early boot) is NOT systematically delayed until the entropy pool is initialized, i.e. regular services need to add explicit ordering deps on this service if they require an initialized random pool. Fixes: #4271 Replaces: #10621 #4513
2019-07-22 19:51:30 +08:00
TimeoutSec=10min