x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
VERITYSETUP(8) Maintenance Commands VERITYSETUP(8)
NAME
veritysetup - manage dm-verity (block level verification) volumes
SYNOPSIS
veritysetup <action> [<options>] <action args>
DESCRIPTION
Veritysetup is used to configure dm-verity managed device-mapper
mappings.
Device-mapper verity target provides read-only transparent integrity
checking of block devices using kernel crypto API.
The dm-verity devices are always read-only.
BASIC ACTIONS
Veritysetup supports these operations:
FORMAT
format <data_device> <hash_device>
Calculates and permanently stores hash verification data for
data_device. Hash area can be located on the same device after data if
specified by --hash-offset option.
Note you need to provide root hash string for device verification or
activation. Root hash must be trusted.
The data or hash device argument can be block device or file image. If
hash device path doesn't exist, it will be created as file.
<options> can be [--hash, --no-superblock, --format, --data-block-size,
--hash-block-size, --data-blocks, --hash-offset, --salt, --uuid,
--root-hash-file].
If option --root-hash-file is used, the root hash is stored in
hex-encoded text format in <path>.
OPEN
open <data_device> <name> <hash_device> <root_hash>
open <data_device> <name> <hash_device> --root-hash-file <path>
create <name> <data_device> <hash_device> <root_hash> (OBSOLETE syntax)
Creates a mapping with <name> backed by device <data_device> and using
<hash_device> for in-kernel verification.
The <root_hash> is a hexadecimal string.
<options> can be [--hash-offset, --no-superblock, --ignore-corruption
or --restart-on-corruption, --panic-on-corruption,
--ignore-zero-blocks, --check-at-most-once, --root-hash-signature,
--root-hash-file, --use-tasklets].
If option --root-hash-file is used, the root hash is read from <path>
instead of from the command line parameter. Expects hex-encoded text,
without terminating newline.
If option --no-superblock is used, you have to use as the same options
as in initial format operation.
VERIFY
verify <data_device> <hash_device> <root_hash>
verify <data_device> <hash_device> --root-hash-file <path>
Verifies data on data_device with use of hash blocks stored on
hash_device.
This command performs userspace verification, no kernel device is
created.
The <root_hash> is a hexadecimal string.
If option --root-hash-file is used, the root hash is read from <path>
instead of from the command line parameter. Expects hex-encoded text,
without terminating newline.
<options> can be [--hash-offset, --no-superblock, --root-hash-file].
If option --no-superblock is used, you have to use as the same options
as in initial format operation.
CLOSE
close <name>
remove <name> (OBSOLETE syntax)
Removes existing mapping <name>.
<options> can be [--deferred] or [--cancel-deferred].
STATUS
status <name>
Reports status for the active verity mapping <name>.
DUMP
dump <hash_device>
Reports parameters of verity device from on-disk stored superblock.
<options> can be [--hash-offset].
OPTIONS
--no-superblock
Create or use dm-verity without permanent on-disk superblock.
--format=number
Specifies the hash version type. Format type 0 is original Chrome
OS version. Format type 1 is current version.
--data-block-size=bytes
Used block size for the data device. (Note kernel supports only
page-size as maximum here.)
--hash-block-size=bytes
Used block size for the hash device. (Note kernel supports only
page-size as maximum here.)
--data-blocks=blocks
Size of data device used in verification. If not specified, the
whole device is used.
--hash-offset=bytes
Offset of hash area/superblock on hash_device. Value must be
aligned to disk sector offset.
--salt=hex string
Salt used for format or verification. Format is a hexadecimal
string.
--uuid=UUID
Use the provided UUID for format command instead of generating new
one.
The UUID must be provided in standard UUID format, e.g.
12345678-1234-1234-1234-123456789abc. *--ignore-corruption ,
--restart-on-corruption ,
--panic-on-corruption*
Defines what to do if data integrity problem is detected (data
corruption).
Without these options kernel fails the IO operation with I/O error.
With --ignore-corruption option the corruption is only logged. With
--restart-on-corruption or --panic-on-corruption the kernel is
restarted (panicked) immediately. (You have to provide way how to
avoid restart loops.)
WARNING: Use these options only for very specific cases. These
options are available since Linux kernel version 4.1.
--ignore-zero-blocks
Instruct kernel to not verify blocks that are expected to contain
zeroes and always directly return zeroes instead.
WARNING: Use this option only in very specific cases. This option
is available since Linux kernel version 4.5.
--check-at-most-once
Instruct kernel to verify blocks only the first time they are read
from the data device, rather than every time.
WARNING: It provides a reduced level of security because only
offline tampering of the data device's content will be detected,
not online tampering. This option is available since Linux kernel
version 4.17.
--hash=hash
Hash algorithm for dm-verity. For default see --help option.
--fec-device=fec_device
Use forward error correction (FEC) to recover from corruption if
hash verification fails. Use encoding data from the specified
device.
The fec device argument can be block device or file image. For
format, if fec device path doesn't exist, it will be created as
file.
Block sizes for data and hash devices must match. Also, if the
verity data_device is encrypted the fec_device should be too.
FEC calculation covers data, hash area, and optional foreign
metadata stored on the same device with the hash tree (additional
space after hash area). Size of this optional additional area
protected by FEC is calculated from image sizes, so you must be
sure that you use the same images for activation.
If the hash device is in a separate image, metadata covers the
whole rest of the image after the hash area.
If hash and FEC device is in the image, metadata ends on the FEC
area offset.
--fec-offset=bytes
This is the offset, in bytes, from the start of the FEC device to
the beginning of the encoding data.
--fec-roots=num
Number of generator roots. This equals to the number of parity
bytes in the encoding data. In RS(M, N) encoding, the number of
roots is M-N. M is 255 and M-N is between 2 and 24 (including).
--root-hash-file=FILE
Path to file with stored root hash in hex-encoded text.
--root-hash-signature=FILE
Path to root hash signature file used to verify the root hash (in
kernel). This feature requires Linux kernel version 5.4 or more
recent.
--use-tasklets
Try to use kernel tasklets in dm-verity driver for performance
reasons. This option is available since Linux kernel version 6.0.
--deferred
Defers device removal in close command until the last user closes
it.
--cancel-deferred
Removes a previously configured deferred device removal in close
command.
--verbose, -v
Print more information on command execution.
--debug
Run in debug mode with full diagnostic logs. Debug output lines are
always prefixed by #.
--version, -V
Show the program version.
--batch-mode, -q
Do not ask for confirmation.
--usage
Show short option help.
--help, -?
Show help text and default parameters.
RETURN CODES
Veritysetup returns 0 on success and a non-zero value on error.
Error codes are: 1 wrong parameters, 2 no permission, 3 out of memory,
4 wrong device specified, 5 device already exists or device is busy.
EXAMPLES
veritysetup --data-blocks=256 format <data_device> <hash_device>
Calculates and stores verification data on hash_device for the first
256 blocks (of block-size). If hash_device does not exist, it is
created (as file image).
veritysetup format --root-hash-file <path> <data_device> <hash_device>
Calculates and stores verification data on hash_device for the whole
data_device, and store the root hash as hex-encoded text in <path>.
veritysetup --data-blocks=256 --hash-offset=1052672 format <device>
<device>
Verification data (hashes) is stored on the same device as data
(starting at hash-offset). Hash-offset must be greater than number of
blocks in data-area.
veritysetup --data-blocks=256 --hash-offset=1052672 create test-device
<device> <device> <root_hash>
Activates the verity device named test-device. Options --data-blocks
and --hash-offset are the same as in the format command. The
<root_hash> was calculated in format command.
veritysetup --data-blocks=256 --hash-offset=1052672 verify
<data_device> <hash_device> <root_hash>
Verifies device without activation (in userspace).
veritysetup --data-blocks=256 --hash-offset=1052672 --root-hash-file
<path> verify <data_device> <hash_device>
Verifies device without activation (in userspace). Root hash passed via
a file rather than inline.
veritysetup --fec-device=<fec_device> --fec-roots=10 format
<data_device> <hash_device>
Calculates and stores verification and encoding data for data_device.
DM-VERITY ON-DISK SPECIFICATION
The on-disk format specification is available at DMVerity
<https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity> page.
AUTHORS
The first implementation of veritysetup was written by Chrome OS
authors.
This version is based on verification code written by Mikulas Patocka
<mpatocka@redhat.com> and rewritten for libcryptsetup by Milan Broz
<gmazyland@gmail.com>.
REPORTING BUGS
Report bugs at cryptsetup mailing list <cryptsetup@lists.linux.dev> or
in Issues project section
<https://gitlab.com/cryptsetup/cryptsetup/-/issues/new>.
Please attach output of the failed command with --debug option added.
SEE ALSO
Cryptsetup FAQ
<https://gitlab.com/cryptsetup/cryptsetup/wikis/FrequentlyAskedQuestions>
cryptsetup(8), integritysetup(8) and veritysetup(8)
CRYPTSETUP
Part of cryptsetup project <https://gitlab.com/cryptsetup/cryptsetup/>.
veritysetup 2.7.0 2024-08-30 VERITYSETUP(8)
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