diff options
| author |   Mikulas Patocka <mpatocka@redhat.com> | 2021-01-20 13:59:11 -0500 |
|---|---|---|
| committer |   Mike Snitzer <snitzer@redhat.com> | 2021-01-21 15:05:21 -0500 |
| commit | 5c02406428d5219c367c5f53457698c58bc5f917 (patch) | |
| tree | eb0725e9c82b535733156d6aa9edc53cde1fed89 /Documentation | |
| parent | dm integrity: fix a crash if "recalculate" used without "internal_hash" (diff) | |
| download | linux-dev-5c02406428d5219c367c5f53457698c58bc5f917.tar.xz linux-dev-5c02406428d5219c367c5f53457698c58bc5f917.zip | |
dm integrity: conditionally disable "recalculate" feature
Otherwise a malicious user could (ab)use the "recalculate" feature
that makes dm-integrity calculate the checksums in the background
while the device is already usable. When the system restarts before all
checksums have been calculated, the calculation continues where it was
interrupted even if the recalculate feature is not requested the next
time the dm device is set up.
Disable recalculating if we use internal_hash or journal_hash with a
key (e.g. HMAC) and we don't have the "legacy_recalculate" flag.
This may break activation of a volume, created by an older kernel,
that is not yet fully recalculated -- if this happens, the user should
add the "legacy_recalculate" flag to constructor parameters.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reported-by: Daniel Glockner <dg@emlix.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/device-mapper/dm-integrity.rst | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/Documentation/admin-guide/device-mapper/dm-integrity.rst b/Documentation/admin-guide/device-mapper/dm-integrity.rst index 4e6f504474ac..2cc5488acbd9 100644 --- a/Documentation/admin-guide/device-mapper/dm-integrity.rst +++ b/Documentation/admin-guide/device-mapper/dm-integrity.rst @@ -177,14 +177,20 @@ bitmap_flush_interval:number The bitmap flush interval in milliseconds. The metadata buffers are synchronized when this interval expires. +allow_discards + Allow block discard requests (a.k.a. TRIM) for the integrity device. + Discards are only allowed to devices using internal hash. + fix_padding Use a smaller padding of the tag area that is more space-efficient. If this option is not present, large padding is used - that is for compatibility with older kernels. -allow_discards - Allow block discard requests (a.k.a. TRIM) for the integrity device. - Discards are only allowed to devices using internal hash. +legacy_recalculate + Allow recalculating of volumes with HMAC keys. This is disabled by + default for security reasons - an attacker could modify the volume, + set recalc_sector to zero, and the kernel would not detect the + modification. The journal mode (D/J), buffer_sectors, journal_watermark, commit_time and allow_discards can be changed when reloading the target (load an inactive |