Following API calls trigerred LUKS2 metadata reload
from storage in case of failure:
crypt_convert
crypt_keyslot_add_by_key
crypt_keyslot_add_by_keyfile_device_offset
crypt_keyslot_add_by_passphrase
crypt_keyslot_change_by_passphrase
crypt_reencrypt_init_by_keyring
crypt_reencrypt_init_by_passphrase
This patch replaces LUKS2 metadata reload with
backup LUKS2 metadata copy kept in memory that is updated on
each sucessfull metadata write and rolled back to it whenever
needed in any of those calls listed above.
The content of LUKS header is not a key material, no need
to lock memory for possibly big header and big memory area locks.
Just ensure we wipe buffer before release of memory.
Do not invalidate LUKS2 format when future online-reencrypt
requirement flag is encountered (by older releases).
But it must stop device from being activated, reencrypted
or modified.
Invalid values that overflows in interval check were silently ignored.
Fix this by explictily adding check for interval overflow in keyslots
and segment validation.
Fixes: #748
Adds support for LUKS2 decryption of devices with a
header put in the head of data device. During the initialization
header is exported to a file and first data segment
is moved to head of data device in place of original header.
The feature introduces several new resilience modes (combination
of existing modes datashift and "checksum" or "journal").
Where datashift resilience mode is applied for data moved towards
the first segment and first segment is decrypted in-place.
The mode is not backward compatible with prior LUKS2 reencryption
and therefor interrupted operation in progress can not be resumed
using older cryptsetup releases.
Fixes: #669.
If LUKS2 is used with integrity protection, there is always a dm-integrity
device underneath.
We should deactivate the device if DM status return tag size (it means,
that dm-crypt uses dm-integrity DIF).
This allows "cryptsetup close <name>" peroperly remove both stacked devices
even if LUKS2 header is no longer available (like in detached header activation).
The function wrongly expected segment objects being
ordered (ascending order) in segments container.
The LUKS2 format never guaranteed that and it could
lead to wrong LUKS2 device size calculation in case
last segment (by key) was stored before any other segment
with fixed size.
Attribute unused is useless and makes code imcomprehensible
when decorates internal functions not exposed via API.
Let's cleanup internal funtion prototypes whenever possible.
crypt_reencrypt_status() returns this flag if old
online-reencrypt requirement is detected and reencryption
keyslot digest is missing.
crypt_reencrypt_init_by_passphrase() with same flag applied
repairs (upgrade) reencryption metadata so that
automatic reencryption recovery during activation
is again possible and reencryption operation can be resumed
post CVE-2021-4122 fix.
Fix possible attacks against data confidentiality through LUKS2 online
reencryption extension crash recovery.
An attacker can modify on-disk metadata to simulate decryption in
progress with crashed (unfinished) reencryption step and persistently
decrypt part of the LUKS device.
This attack requires repeated physical access to the LUKS device but
no knowledge of user passphrases.
The decryption step is performed after a valid user activates
the device with a correct passphrase and modified metadata.
There are no visible warnings for the user that such recovery happened
(except using the luksDump command). The attack can also be reversed
afterward (simulating crashed encryption from a plaintext) with
possible modification of revealed plaintext.
The problem was caused by reusing a mechanism designed for actual
reencryption operation without reassessing the security impact for new
encryption and decryption operations. While the reencryption requires
calculating and verifying both key digests, no digest was needed to
initiate decryption recovery if the destination is plaintext (no
encryption key). Also, some metadata (like encryption cipher) is not
protected, and an attacker could change it. Note that LUKS2 protects
visible metadata only when a random change occurs. It does not protect
against intentional modification but such modification must not cause
a violation of data confidentiality.
The fix introduces additional digest protection of reencryption
metadata. The digest is calculated from known keys and critical
reencryption metadata. Now an attacker cannot create correct metadata
digest without knowledge of a passphrase for used keyslots.
For more details, see LUKS2 On-Disk Format Specification version 1.1.0.
Add API call that can directly print JSON metadata area from LUKS2 device.
For commandline it also adds --dump-json-metadata option for luksDump action.
Note that the binary metadata (UUID, version etc) is not part of this output.
(We reserve flags parameter to be able to add this later.)
Fixes: #511
Keep it simple. If there's not enough memory we can't validate
segments. The LUKS2 specification does not recommend to continue
processing LUKS2 metadata if it can not be properly validated.
In case LUKS2 backup segment creates gap in between last regular
segment and backup segment report invalid metadata imediately. We stop
on first error so there's no need to allocate large memory on heap
(we may ran with mlock(MCL_FUTURE) set).
Example:
- total segments count is 3
- regular segments have keys "0" and "1"
- first backup segment has key "42"
Segments are validated in hdr_validate_segments. Gaps in segment keys
are detected when collecting offsets. But if an invalid segment is very
large, larger than count, it could happen that cryptsetup is unable to
allocate enough memory, not giving a clue about what actually is the
problem.
Therefore check for gaps even if not enough memory is available. This
gives much more information with debug output enabled.
Obviously cryptsetup still fails if segments are perfectly fine but not
enough RAM available. But at that stage, the user knows that it's the
fault of the system, not of an invalid segment.
These performance options, introduced in kernel 5.9, configures
dm-crypt to bypass read or write workqueues and run encryption
synchronously.
Also support persistent storage of these flags for LUKS2.
* TRUE/FALSE are not defined anymore. 1 and 0 are used instead.
* json_object_get_uint64() and json_object_new_uint64() are part
of the upstream API now.
Kernel 5.7 adds support for optional discard/TRIM operation
for dm-integrity (available only for internal hash, not for LUKS2
with integrity).
This patch adds support for the new option.
Some kernels show invalid dm-integrity table if suberblock
contains "recalculate" bit.
We can workaround that by setting recalculate option in table
(kernel uses bits from superblock anyway), so the table displayed
is always correct.
Fixes: #538
