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.
Currently hard memory limit is 1 GiB. Soft limit is
1/4 of system memory.
Note that --hotzone-size cryptsetup parameter can only further
lower hard and soft memory limit on hotzone size and not bypass
it.
- Remove all 'LUKS2_' name prefixes from internal routines
- Make all internal routines prefixed with 'reencrypt_' instead
- Drop few static routines by refactoring
- Rename all variables and routines containing 'pre' prefix to
contain 'hot' prefix instead (when referring to segments
undergoing reencryption)
- Rename all variables and routines containing 'after' prefix to
contain 'post' prefix instead
- Rename all routines prefixed with '_' to 'reencrypt_' instead
It's useful to reencrypt only initial device part only.
For example with golden image reencryption it may be useful
to reencrypt only first X bytes of device because we know
the rest of device is empty.
If passed key matches any existing digest we will not create
new digest but assign the keyslot to already existing one.
Because reencryption should be able to create more than one
keyslot assigned to new key digest.
TODO: Tests for the new feature
This patch makes available LUKS2 per-keyslot encryption settings to user.
In LUKS2, keyslot can use different encryption that data.
We can use new crypt_keyslot_get_encryption and crypt_keyslot_set_encryption
API calls to set/get this encryption.
For cryptsetup new --keyslot-cipher and --keyslot-key-size options are added.
The default keyslot encryption algorithm (if cannot be derived from data encryption)
is now available as configure options (default is aes-xts-plain64 with 512-bits key).
NOTE: default was increased from 256-bits.
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.
