When formating LUKS2 device with no keyslots area (it's valid
LUKS2 header) there's a bug in wipe routine that is supposed
to wipe LUKS2 keyslots area. When the keyslots area size is of
zero length it causes wipe function to erase whole data device
starting at defined data offset.
Let's make LUKS2_generate_hdr as clean as possible. Cipher
specification string can be constructed in upper layers.
This will make future LUKS2_generate_hdr extension easier.
The integrity is optional parameter of dm-crypt segment definition.
Move the low level json code in appropriate json helper.
It will make adding new segment easier. The future hw-opal-crypt
segment will inherit all crypt fields.
Move all metadata size and data offset calculations
logic away from LUKS2_generate_hdr. The function
was meant to generate solely LUKS2 header on disk json
format.
The aim is to have all logic related data offset and metadata
size in one place available to be calculated in advance so
that we can easily extend the code.
The device_check is done in header write functions,
but these are not recached in normal format path as wipe call
is called earlier.
Call the device check also from wipe function to get better error
description.
This situation happens for example when a block device is too small
(regular file can be enlarged by falloc(); block device cannot).
Attribute unused is useless and makes code imcomprehensible
when decorates internal functions not exposed via API.
Let's cleanup internal funtion prototypes whenever possible.
The code expects that change key is done in-place if there is not
a free space in keyslot area for safe key swap.
This patch makes the code behaves the same as in LUKS1,
luksChangeKey now works the same.
When creating LUKS2 header with specified --offset much larger
then LUKS2 header size we needlessly also wipe (allocate up to
--offset) much larger file than needed.
Unless user explicitly asks for keyslots areas size
(either via --luks2-keyslots-size or --offset) reduce keyslots
size so that it fits in metadata device.
The JSON structures should not be printed by default to debug log.
This flag introduces new debug level that prints JSON structures
and keeps default debug output separate.
The crypt_set_data_offset sets the data offset for LUKS and LUKS2 devices
to specified value in 512-byte sectors.
This value should replace alignment calculation in LUKS param structures.
LUKS2 specification allows various size of LUKS2 metadata.
The single metadata instance is composed of LUKS2 binary header
(4096 bytes) and immediately following json area. The resulting
assembled metadata size have to be one of following values,
all in KiB:
16, 32, 64, 128, 256, 512, 1024, 2048 or 4096
All previous version of cryptsetup wiped only first 4k for LUKS1
and both JSON areas for LUKS2 (first 32k) and the allocated
keyslot area (as it contained the generated key).
Remaining areas (unused keyslots, padding, and alignment) were
not wiped and could contain some previous data.
Since this commit, the whole area up to the data offset is zeroed,
and subsequently, all keyslots areas are wiped with random data.
Only exceptions are
- padding/alignment areas for detached header
if the data offset is set to 0
- bogus LUKS1 keyslot areas (upstream code never
created such keyslots but someone could use that).
This operation could slow down luksFormat on some devices, but
it guarantees that after this operation LUKS header does not
contain any foreign data.
