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Adrian Reber
600fcc6dcb
Set DISSECT_IMAGE_TPM2_UNLOCK where unlocking an image's LUKS partitions via the local TPM2 is wanted and the caller is trusted: * systemd-dissect, an admin tool operating on an image the invoking user can read anyway; * systemd-nspawn --image=, which already prompts for a passphrase interactivly, so TPM2 first and passphrase second is the natural order; * systemd-sysext/systemd-confext, which decrypt without any passphrase, so extension images sealed to the host can be activated without user interaction. For sysext/confext setting the flag at merge time is not enough: before merging, the extension-release metadata is read via image_read_metadata() in discover-image.c, which uses its own flag set and would already fail with -ENOKEY on an encrypted image. Give it an extra_flags parameter and pass the flag from there, too; the other callers (machined, portabled) pass 0 and keep their behaviour. Two units need adjusting for this to work when started by the service manager: systemd-nspawn@.service has DevicePolicy=closed, so allow /dev/tpmrm0 there, and the sysext/confext services are not ordered against the TPM2 device showing up, so order them after tpm2.target like the pcr* services. The initrd variants cannot be ordered the same way: they run before local-fs-pre.target, while the software TPM fallback only becomes available after the early ESP mount, which is ordered after local-fs-pre.target, so a static After=tpm2.target would be an ordering cycle with systemd.tpm2_software_fallback=1. Hence systemd-tpm2-generator adds the ordering as a drop-in instead, unless the fallback is in use. That drop-in also orders them after systemd-pcrphase-initrd.service: nothing else guarantees the "enter-initrd" phase has been measured into PCR 11 before the initrd extension units merge their images (the barrier's Before=systemd-sysext.service is a leftover from when that unit was also used in the initrd), so tokens bound to a signed PCR 11 policy or a pcrlock policy would race the measurement. Deliberately not enabled for now: RootImage=/ExtensionImages=/MountImages= in units, portabled and gpt-auto. For those an unconditional default is probably not wanted but a per-unit or per-image switch, which is left for a follow-up. systemd-mountfsd, which unprivileged systemd-dissect and systemd-nspawn delegate to, keeps its own flag set and does not honour the flag, hence TPM2 unlocking is only available when running privileged; the man pages say so. Document the behaviour and $SYSTEMD_DISSECT_TPM2_UNLOCK= in the dissect, nspawn and sysext man pages and in docs/ENVIRONMENT.md.
40 lines
1.5 KiB
Desktop File
40 lines
1.5 KiB
Desktop File
# SPDX-License-Identifier: LGPL-2.1-or-later
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#
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# This file is part of systemd.
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#
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# systemd is free software; you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or
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# (at your option) any later version.
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[Unit]
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Description=Merge System Extension Images into /usr/ and /opt/ of the initrd
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Documentation=man:systemd-sysext-initrd.service(8)
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ConditionCapability=CAP_SYS_ADMIN
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ConditionDirectoryNotEmpty=|/etc/extensions
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ConditionDirectoryNotEmpty=|/run/extensions
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ConditionDirectoryNotEmpty=|/var/lib/extensions
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ConditionDirectoryNotEmpty=|/.extra/sysext
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ConditionDirectoryNotEmpty=|/.extra/global_sysext
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ConditionPathExists=/etc/initrd-release
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ConditionKernelCommandLine=!rd.systemd.sysext=0
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DefaultDependencies=no
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After=systemd-confext-initrd.service
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# Extension images might be LUKS encrypted and sealed to the local TPM2, but ordering after tpm2.target here
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# would be a cycle with the software TPM fallback, hence systemd-tpm2-generator adds it where possible
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Before=local-fs-pre.target cryptsetup-pre.target systemd-tmpfiles-setup.service
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Wants=local-fs-pre.target cryptsetup-pre.target
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Conflicts=initrd-switch-root.target
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Before=initrd-switch-root.target
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Wants=modprobe@loop.service modprobe@dm_mod.service
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After=modprobe@loop.service modprobe@dm_mod.service
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[Service]
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Type=oneshot
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RemainAfterExit=yes
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ExecStart=systemd-sysext refresh
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ExecReload=systemd-sysext refresh
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ExecStop=systemd-sysext unmerge
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