veritysetup(8)
NAME
veritysetup - manage dm-verity (block level verification) volumes
SYNOPSIS
veritysetup <options> <action> <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.
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]
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.
remove <name>
Removes existing mapping <name>.
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]
OPTIONS
--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 verion. 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.
--version
Show the program version.
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.
REPORTING BUGS
Report bugs, including ones in the documentation, on the cryptsetup mailing list at <[email protected]> or in the 'Issues' section on LUKS website. Please attach the output of the failed command with the --debug option added.
AUTHORS
The first implementation of veritysetup was written by Chrome OS authors. This version is based on verification code written by Mikulas Patocka <[email protected]> and rewritten for libcryptsetup by Milan Broz <[email protected]>.
COPYRIGHT
Copyright 2012-2016 Red Hat, Inc. Copyright 2012-2016 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.
SEE ALSO
The project website at https://gitlab.com/cryptsetup/cryptsetup The verity on-disk format specification available at https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
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