Re: [libvirt] [PATCH v2] storage: Add capability to use LUKS encryption for disk backend

On Tue, May 29, 2018 at 08:53:06 -0400, John Ferlan wrote: > https://bugzilla.redhat.com/show_bug.cgi?id=1560946 > > Similar to the the Logical backend, use qemu-img on the created > disk partition device to set up for LUKS encryption. Secret mgmt > for the device can be complicated by a reboot possibly changing > the path to the device if the infrastructure changes. > > Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; > --- > Changes in v2: Don't alter the result 'endOffset' of the > DiskPartBoundaries, rather modify the input capacity value. > Alteration of the value for the error path won't matter > since the volume would be deleted anyway. The call to > virStorageBackendDiskPartBoundaries was also slightly > modified to check the return value vs -1 rather than != 0 > so that the call is similar to other calls. Separating > that into it's own patch could have been done, but just > felt like too much "busy work" to be worth the trouble. > > src/storage/storage_backend_disk.c | 49 ++++++++++++++++++++++---------------- > 1 file changed, 29 insertions(+), 20 deletions(-) > > diff --git a/src/storage/storage_backend_disk.c b/src/storage/storage_backend_disk.c > index 2e3d1e04a4..e9578d01d6 100644 > --- a/src/storage/storage_backend_disk.c > +++ b/src/storage/storage_backend_disk.c > @@ -879,28 +879,26 @@ virStorageBackendDiskCreateVol(virStoragePoolObjPtr pool, > char *partFormat = NULL; > unsigned long long startOffset = 0, endOffset = 0; > virStoragePoolDefPtr def = virStoragePoolObjGetDef(pool); > + virErrorPtr save_err; > virCommandPtr cmd = virCommandNewArgList(PARTED, > def->source.devices[0].path, > "mkpart", > "--script", > NULL); > > - if (vol->target.encryption != NULL) { > - virReportError(VIR_ERR_CONFIG_UNSUPPORTED, > - "%s", _("storage pool does not support encrypted " > - "volumes")); > - goto cleanup; > - } > - > if (virStorageBackendDiskPartFormat(pool, vol, &partFormat) != 0) > goto cleanup; > virCommandAddArg(cmd, partFormat); > > - if (virStorageBackendDiskPartBoundaries(pool, &startOffset, > - &endOffset, > - vol->target.capacity) != 0) { > + /* If we're going to encrypt using LUKS, then we could need up to > + * an extra 2MB for the LUKS header - so account for that now */ > + if (vol->target.encryption && > + vol->target.encryption->format == VIR_STORAGE_ENCRYPTION_FORMAT_LUKS) > + vol->target.capacity += 2 * 1024 * 1024; So this is done only for LUKS encryption ... > + > + if (virStorageBackendDiskPartBoundaries(pool, &startOffset, &endOffset, > + vol->target.capacity) < 0) > goto cleanup; > - } > > virCommandAddArgFormat(cmd, "%lluB", startOffset); > virCommandAddArgFormat(cmd, "%lluB", endOffset); > @@ -919,15 +917,15 @@ virStorageBackendDiskCreateVol(virStoragePoolObjPtr pool, > VIR_FREE(vol->target.path); > > /* Fetch actual extent info, generate key */ > - if (virStorageBackendDiskReadPartitions(pool, vol) < 0) { > - /* Best effort to remove the partition. Ignore any errors > - * since we could be calling this with vol->target.path == NULL > - */ > - virErrorPtr save_err = virSaveLastError(); > - ignore_value(virStorageBackendDiskDeleteVol(pool, vol, 0)); > - virSetError(save_err); > - virFreeError(save_err); > - goto cleanup; > + if (virStorageBackendDiskReadPartitions(pool, vol) < 0) > + goto error; > + > + if (vol->target.encryption) { > + /* Adjust the sizes to account for the LUKS header */ > + vol->target.capacity -= 2 * 1024 * 1024; > + vol->target.allocation -= 2 * 1024 * 1024; but this is done for any encryption type, so if VIR_STORAGE_ENCRYPTION_FORMAT_QCOW would be used it would rob off two megabytes of the volume size. Honestly I think that VIR_STORAGE_ENCRYPTION_FORMAT_QCOW should be disallowed for creation code right away, so that nobody creates the broken format any more. That way we don't have to deal with possibility that somebody with a old qemu-img would run into problems here without adding much spurious code. > + if (virStorageBackendCreateVolUsingQemuImg(pool, vol, NULL, 0) < 0) > + goto error; ACK if you reject VIR_STORAGE_ENCRYPTION_FORMAT_QCOW right at the beginning.