systemd-cryptsetup-generator (8) - Linux Manuals

systemd-cryptsetup-generator: Unit generator for /etc/crypttab

NAME

systemd-cryptsetup-generator - Unit generator for /etc/crypttab

SYNOPSIS

/lib/systemd/system-generators/systemd-cryptsetup-generator

DESCRIPTION

systemd-cryptsetup-generator is a generator that translates /etc/crypttab into native systemd units early at boot and when configuration of the system manager is reloaded. This will create systemd-cryptsetup [at] .service(8) units as necessary.

systemd-cryptsetup-generator implements systemd.generator(7).

KERNEL COMMAND LINE

systemd-cryptsetup-generator understands the following kernel command line parameters:

luks=, rd.luks=

Takes a boolean argument. Defaults to "yes". If "no", disables the generator entirely. rd.luks= is honored only by initial RAM disk (initrd) while luks= is honored by both the main system and the initrd.

luks.crypttab=, rd.luks.crypttab=

Takes a boolean argument. Defaults to "yes". If "no", causes the generator to ignore any devices configured in /etc/crypttab (luks.uuid= will still work however). rd.luks.crypttab= is honored only by initial RAM disk (initrd) while luks.crypttab= is honored by both the main system and the initrd.

luks.uuid=, rd.luks.uuid=

Takes a LUKS superblock UUID as argument. This will activate the specified device as part of the boot process as if it was listed in /etc/crypttab. This option may be specified more than once in order to set up multiple devices. rd.luks.uuid= is honored only by initial RAM disk (initrd) while luks.uuid= is honored by both the main system and the initrd.

If /etc/crypttab contains entries with the same UUID, then the name, keyfile and options specified there will be used. Otherwise, the device will have the name "luks-UUID".

If /etc/crypttab exists, only those UUIDs specified on the kernel command line will be activated in the initrd or the real root.

luks.name=, rd.luks.name=

Takes a LUKS super block UUID followed by an "=" and a name. This implies rd.luks.uuid= or luks.uuid= and will additionally make the LUKS device given by the UUID appear under the provided name.

This parameter is the analogue of the first crypttab(5) field volume-name.

rd.luks.name= is honored only by initial RAM disk (initrd) while luks.name= is honored by both the main system and the initrd.

luks.data=, rd.luks.data=

Takes a LUKS super block UUID followed by a "=" and a block device specification for device hosting encrypted data.

For those entries specified with rd.luks.uuid= or luks.uuid=, the data device will be set to the one specified by rd.luks.data= or luks.data= of the corresponding UUID.

LUKS data device parameter is useful for specifying encrypted data devices with detached headers specified in luks.options entry containing "header=" argument. For example, rd.luks.uuid=b40f1abf-2a53-400a-889a-2eccc27eaa40 rd.luks.options=b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/path/to/luks.hdr rd.luks.data=b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx. Hence, in this case, we will attempt to unlock LUKS device assembled from data device "/dev/sdx" and LUKS header (metadata) put in "/path/to/luks.hdr" file. This syntax is for now only supported on a per-device basis, i.e. you have to specify LUKS device UUID.

This parameter is the analogue of the second crypttab(5) field encrypted-device.

rd.luks.data= is honored only by initial RAM disk (initrd) while luks.data= is honored by both the main system and the initrd.

luks.key=, rd.luks.key=

Takes a password file name as argument or a LUKS super block UUID followed by a "=" and a password file name.

For those entries specified with rd.luks.uuid= or luks.uuid=, the password file will be set to the one specified by rd.luks.key= or luks.key= of the corresponding UUID, or the password file that was specified without a UUID.

It is also possible to specify an external device which should be mounted before we attempt to unlock the LUKS device. systemd-cryptsetup will use password file stored on that device. Device containing password file is specified by appending colon and a device identifier to the password file path. For example, rd.luks.uuid=b40f1abf-2a53-400a-889a-2eccc27eaa40 rd.luks.key=b40f1abf-2a53-400a-889a-2eccc27eaa40=/keyfile:LABEL=keydev. Hence, in this case, we will attempt to mount file system residing on the block device with label "keydev". This syntax is for now only supported on a per-device basis, i.e. you have to specify LUKS device UUID.

This parameter is the analogue of the third crypttab(5) field key-file.

rd.luks.key= is honored only by initial RAM disk (initrd) while luks.key= is honored by both the main system and the initrd.

luks.options=, rd.luks.options=

Takes a LUKS super block UUID followed by an "=" and a string of options separated by commas as argument. This will override the options for the given UUID.

If only a list of options, without an UUID, is specified, they apply to any UUIDs not specified elsewhere, and without an entry in /etc/crypttab.

This parameter is the analogue of the fourth crypttab(5) field options.

It is possible to specify an external device which should be mounted before we attempt to unlock the LUKS device. systemd-cryptsetup will assemble LUKS device by combining data device specified in luks.data with detached LUKS header found in "header=" argument. For example, rd.luks.uuid=b40f1abf-2a53-400a-889a-2eccc27eaa40 rd.luks.options=b40f1abf-2a53-400a-889a-2eccc27eaa40=header=/luks.hdr:LABEL=hdrdev rd.luks.data=b40f1abf-2a53-400a-889a-2eccc27eaa40=/dev/sdx. Hence, in this case, we will attempt to mount file system residing on the block device with label "hdrdev", and look for "luks.hdr" on that file system. Said header will be used to unlock (decrypt) encrypted data stored on /dev/sdx. This syntax is for now only supported on a per-device basis, i.e. you have to specify LUKS device UUID.

rd.luks.options= is honored only by initial RAM disk (initrd) while luks.options= is honored by both the main system and the initrd.