linstor: fix encrypted volume snapshot backup and restore by rp- · Pull Request #13486 · apache/cloudstack · GitHub
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linstor: fix encrypted volume snapshot backup and restore#13486

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apache:4.22from
LINBIT:linstor-4.22-fix-encrypted-snapshot-restore
Open

linstor: fix encrypted volume snapshot backup and restore#13486
rp- wants to merge 1 commit into
apache:4.22from
LINBIT:linstor-4.22-fix-encrypted-snapshot-restore

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@rp-

@rp- rp- commented Jun 24, 2026

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Description

This PR fixes a bug that was reported on the linstor-server github project: LINBIT/linstor-server#495

Encrypted Linstor volumes use a LUKS layer inside the DRBD stack, so the storage-layer snapshot device holds ciphertext while the DRBD device CloudStack restores to is the decrypted view. Backing up the raw snapshot and writing it back to the decrypted device corrupted the volume (different data, unbootable root).

Back up encrypted snapshots from the decrypted DRBD device (forcing the temporary-resource path) and store them as a LUKS-encrypted qcow2 using the volume passphrase, so snapshots are not kept in clear text on secondary storage. On revert, decrypt the qcow2 and write plaintext to the DRBD device; the LUKS layer re-encrypts it. The qemu-img shrink is skipped for encrypted volumes (the DRBD device is already net-sized).

Add an integration test (test_linstor_encrypted_snapshots.py): the encrypted-root snapshot revert round-trip, that
create-volume-from-encrypted-snapshot is rejected by CloudStack core, and a best-effort check that the backed-up qcow2 is LUKS-encrypted at rest.

Types of changes

  • Breaking change (fix or feature that would cause existing functionality to change)
  • New feature (non-breaking change which adds functionality)
  • Bug fix (non-breaking change which fixes an issue)
  • Enhancement (improves an existing feature and functionality)
  • Cleanup (Code refactoring and cleanup, that may add test cases)
  • Build/CI
  • Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

  • Major
  • Minor

Bug Severity

  • BLOCKER
  • Critical
  • Major
  • Minor
  • Trivial

Screenshots (if appropriate):

How Has This Been Tested?

Added/Run integration tests to restore encrypted volumes.

@rp- rp- self-assigned this Jun 24, 2026
@rp- rp- force-pushed the linstor-4.22-fix-encrypted-snapshot-restore branch from 63786c5 to b44339a Compare June 24, 2026 13:32
@codecov

codecov Bot commented Jun 24, 2026

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@rp- rp- added this to the 4.22.2 milestone Jun 25, 2026
@rp- rp- requested review from Pearl1594, abh1sar and shwstppr June 25, 2026 19:38
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Encrypted Linstor volumes use a LUKS layer inside the DRBD stack, so
the storage-layer snapshot device holds ciphertext while the DRBD
device CloudStack restores to is the decrypted view. Backing up the
raw snapshot and writing it back to the decrypted device corrupted the
volume (different data, unbootable root).

Back up encrypted snapshots from the decrypted DRBD device (forcing
the temporary-resource path) and store them as a LUKS-encrypted qcow2
using the volume passphrase, so snapshots are not kept in clear text
on secondary storage. On revert, decrypt the qcow2 and write plaintext
to the DRBD device; the LUKS layer re-encrypts it. The qemu-img shrink
is skipped for encrypted volumes (the DRBD device is already
net-sized).

Add an integration test (test_linstor_encrypted_snapshots.py): the
encrypted-root snapshot revert round-trip, that
create-volume-from-encrypted-snapshot is rejected by CloudStack core,
and a best-effort check that the backed-up qcow2 is LUKS-encrypted at
rest.
@rp- rp- force-pushed the linstor-4.22-fix-encrypted-snapshot-restore branch from b44339a to f2a07d5 Compare June 29, 2026 19:21
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