|
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | RETURN CODES | EXAMPLES | REPORTING BUGS | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON |
VERITYSETUP(8) Maintenance Commands VERITYSETUP(8)
veritysetup - manage dm-verity (block level verification) volumes
veritysetup <options> <action> <action args>
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.
Veritysetup supports these operations:
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]
open <data_device> <name> <hash_device> <root_hash> create <name>
<data_device> <hash_device> <root_hash>
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, --ignore-zero-blocks]
If option --no-superblock is used, you have to use as the same
options as in initial format operation.
verify <data_device> <hash_device> <root_hash>
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.
<options> can be [--hash-offset, --no-superblock]
If option --no-superblock is used, you have to use as the same
options as in initial format operation.
close <name>
Removes existing mapping <name>.
For backward compatibility there is remove command alias for
close command.
status <name>
Reports status for the active verity mapping <name>.
dump <hash_device>
Reports parameters of verity device from on-disk stored
superblock.
<options> can be [--no-superblock]
--verbose, -v
Print more information on command execution.
--debug
Run in debug mode with full diagnostic logs. Debug output
lines are always prefixed by '#'.
--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
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 the kernel is restarted
immediatelly. (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.
--hash=hash
Hash algorithm for dm-verity. For default see --help option.
--version
Show the program version.
--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.
Note: block sizes for data and hash devices must match. Also,
if the verity data_device is encrypted the fec_device should
be too.
--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).
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.
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 <data_device> <hash_device>
Calculates and stores verification data on hash_device for the whole
data_device.
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>
Acivatees 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 --fec-device=<fec_device> --fec-roots=10 format
<data_device> <hash_device>
Calculates and stores verification and encoding data for data_device.
Report bugs, including ones in the documentation, on the cryptsetup
mailing list at <dm-crypt@saout.de> or in the 'Issues' section on
LUKS website. Please attach the output of the failed command with
the --debug option added.
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>.
Copyright © 2012-2017 Red Hat, Inc.
Copyright © 2012-2017 Milan Broz
This is free software; see the source for copying conditions. There
is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.
The project website at https://gitlab.com/cryptsetup/cryptsetup
The verity on-disk format specification available at
https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
This page is part of the Cryptsetup ((open-source disk encryption))
project. Information about the project can be found at
⟨https://gitlab.com/cryptsetup/cryptsetup⟩. If you have a bug report
for this manual page, send it to dm-crypt@saout.de. This page was
obtained from the project's upstream Git repository
⟨https://gitlab.com/cryptsetup/cryptsetup.git⟩ on 2017-07-05. 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 man-pages@man7.org
veritysetup March 2017 VERITYSETUP(8)