Support for multi-segment devices is requirement for online
reencryption to work. Introducing modififed dm backend that
splits data structures describing active device and individual
dm target (or segment).
The new flag is supposed to refresh (reload) active dm-crypt
mapping with new set of activation flags. CRYPT_ACTIVATE_READONLY
can not be switched for already active device.
The flag is silently ignored for tcrypt, verity and integrity
devices. LUKS2 with authenticated encryption support is added in
later commit.
Also print these area sizes in dump command.
NOTE: since now, the metadata area size in dump command contains
mandatory 4k binary section (to be aligned with API definition).
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.
Due to previous fix it's no longer needed to add
all keyslot area lengths and check if result sum
is lower than keyslots_size.
(We already check lower limit, upper limit and
overlapping areas)
This commit fixes two problems:
a) Replace hardcoded 16KiB metadata variant as lower limit
for keyslot area offset with current value set in config
section (already validated).
b) Replace segment offset (if not zero) as upper limit for
keyslot area offset + size with value calculated as
2 * metadata size + keyslots_size as acquired from
config section (also already validated)
Swap config and keyslot areas validation code order.
Also split original keyslots_size validation code in
between config and keyslot areas routines for furhter
changes in the code later. This commit has no funtional
impact.
Keyslot areas were validated from each keyslot
validation routine and later one more time
in general header validation routine. The call
from header validation routine is good enough.
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.
crypt segment data offset has nothing to do with encryption sector
size. The device may hint alignment offset which is completely
unrelated and LUKS2 validation blocks it.
When LUKS2 crypt_format() is called with detached header and custom data
alignment is requested, keyslots area is miscalculated. This mistake
is correctly detected by LUKS2 validation code but it's feature
regression with regard to LUKSv1 format.
