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NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | SEE ALSO | NOTES | COLOPHON |
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INTEGRITYTAB(5) integritytab INTEGRITYTAB(5)
integritytab - Configuration for integrity block devices
/etc/integritytab
The /etc/integritytab file describes integrity protected block
devices that are set up during system boot.
Empty lines and lines starting with the "#" character are
ignored. Each of the remaining lines describes one verity
integrity protected block device. Fields are delimited by white
space.
Each line is in the form
volume-name block-device
[keyfile|-] [options|-]
The first two fields are mandatory, the remaining two are
optional and only required if user specified non-default options
during integrity format.
The first field contains the name of the resulting integrity
volume; its block device is set up below /dev/mapper/.
The second field contains a path to the underlying block device,
or a specification of a block device via "UUID=" followed by the
UUID, "PARTUUID=" followed by the partition UUID, "LABEL="
followed by the label, "PARTLABEL=" followed by the partition
label.
The third field if present contains an absolute filename path to
a key file or a "-" to specify none. When the filename is
present, the "integrity-algorithm" defaults to "hmac-sha256" with
the key length derived from the number of bytes in the key file.
At this time the only supported integrity algorithm when using
key file is hmac-sha256. The maximum size of the key file is 4096
bytes.
The fourth field, if present, is a comma-delimited list of
options or a "-" to specify none. The following options are
recognized:
allow-discards
Allow the use of discard (TRIM) requests for the device. This
option is available since the Linux kernel version 5.7.
Added in version 250.
mode=(journal|bitmap|direct)
Enable journaled, bitmapped or direct (passthrough) mode.
Journaled mode is the default when this option is not
specified. It provides safety against crashes, but can be
slow because all data has to be written twice. Bitmap mode is
more efficient since it requires only a single write, but it
is less reliable because if data corruption happens when the
machine crashes, it might not be detected. Direct mode
disables the journal and the bitmap. Corresponds to the
"direct writes" mode documented in the dm-integrity
documentation[1]. Note that without a journal, if there is a
crash, it is possible that the integrity tags and data will
not match. If used, the journal-* options below will have no
effect if passed.
Added in version 254.
journal-watermark=[0..100]%
Journal watermark in percent. When the journal percentage
exceeds this watermark, the journal flush will be started.
Setting a value of "0%" uses default value.
Added in version 250.
journal-commit-time=[0..N]
Commit time in milliseconds. When this time passes (and no
explicit flush operation was issued), the journal is written.
Setting a value of zero uses default value.
Added in version 250.
data-device=/dev/disk/by-...
Specify a separate block device that contains existing data.
The second field specified in the integritytab for block
device then will contain calculated integrity tags and
journal for data-device, but not the end user data.
Added in version 250.
integrity-algorithm=[crc32c|crc32|sha1|sha256|hmac-sha256]
The algorithm used for integrity checking. The default is
crc32c. Must match option used during format.
Added in version 250.
At early boot and when the system manager configuration is
reloaded, this file is translated into native systemd units by
systemd-integritysetup-generator(8).
Example 1. /etc/integritytab
Set up two integrity protected block devices.
home PARTUUID=4973d0b8-1b15-c449-96ec-94bab7f6a7b8 - journal-commit-time=10,allow-discards,journal-watermark=55%
data PARTUUID=5d4b1808-be76-774d-88af-03c4c3a41761 - allow-discards
Example 2. /etc/integritytab
Set up 1 integrity protected block device using defaults
home PARTUUID=4973d0b8-1b15-c449-96ec-94bab7f6a7b8
Example 3. /etc/integritytab
Set up 1 integrity device using existing data block device which
contains user data
home PARTUUID=4973d0b8-1b15-c449-96ec-94bab7f6a7b8 - data-device=/dev/disk/by-uuid/9276d9c0-d4e3-4297-b4ff-3307cd0d092f
Example 4. /etc/integritytab
Set up 1 integrity device using a HMAC key file using defaults
home PARTUUID=4973d0b8-1b15-c449-96ec-94bab7f6a7b8 /etc/hmac.key
systemd(1), [email protected](8),
systemd-integritysetup-generator(8), integritysetup(8)
1. the dm-integrity documentation
https://docs.kernel.org/admin-guide/device-mapper/dm-integrity.html
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have
a bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2024-06-14. (At that
time, the date of the most recent commit that was found in the
repository was 2024-06-13.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
systemd 257~devel INTEGRITYTAB(5)
Pages that refer to this page: systemd.directives(7), systemd.index(7), [email protected](8)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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