[libvirt] [PATCH 4/5] storage: Properly resize a local volume using LUKS

[Michal Privoznik]

On 10/06/2017 08:13 PM, John Ferlan wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=1490279
> 
> Turns out the virStorageBackendVolResizeLocal did not differentiate
> whether the target volume was a LUKS volume or not and just blindly
> did the ftruncate() on the target volume.
> 
> Follow the volume creation logic (in general) and create a qemu-img
> resize command to resize the target volume for LUKS ensuring that
> the --object secret is provided as well as the '--image-opts' used
> by the qemu-img resize logic to describe the path and secret ensuring
> that it's using the luks driver on the volume of course.
> 
> Signed-off-by: John Ferlan <jferlan at redhat.com>
> ---
>  src/storage/storage_util.c | 98 ++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 90 insertions(+), 8 deletions(-)
> 
> diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c
> index e6d2747e8d..e485fa5a95 100644
> --- a/src/storage/storage_util.c
> +++ b/src/storage/storage_util.c
> @@ -1143,6 +1143,37 @@ storageBackendCreateQemuImgSecretObject(virCommandPtr cmd,
>  }
>  
>  
> +/* Add a --image-opts to the qemu-img resize command line:
> + *    --image-opts driver=luks,file.filename=$volpath,key-secret=$secretAlias
> + *
> + *    NB: format=raw is assumed
> + */
> +static int
> +storageBackendResizeQemuImgImageOpts(virCommandPtr cmd,
> +                                     const char *path,
> +                                     const char *secretAlias)
> +{
> +    virBuffer buf = VIR_BUFFER_INITIALIZER;
> +    char *commandStr = NULL;
> +
> +    virBufferAsprintf(&buf, "driver=luks,key-secret=%s,file.filename=",
> +                      secretAlias);
> +    virQEMUBuildBufferEscapeComma(&buf, path);
> +
> +    if (virBufferCheckError(&buf) < 0) {
> +        virBufferFreeAndReset(&buf);
> +        return -1;
> +    }
> +
> +    commandStr = virBufferContentAndReset(&buf);
> +
> +    virCommandAddArgList(cmd, "--image-opts", commandStr, NULL);
> +
> +    VIR_FREE(commandStr);
> +    return 0;
> +}
> +
> +
>  /* Create a qemu-img virCommand from the supplied binary path,
>   * volume definitions and imgformat
>   */
> @@ -2286,12 +2317,17 @@ virStorageBackendVolRefreshLocal(virConnectPtr conn,
>  
>  
>  static int
> -storageBackendResizeQemuImg(virStorageVolDefPtr vol,
> +storageBackendResizeQemuImg(virConnectPtr conn,
> +                            virStoragePoolObjPtr pool,
> +                            virStorageVolDefPtr vol,
>                              unsigned long long capacity)
>  {
>      int ret = -1;
> -    char *img_tool;
> +    char *img_tool = NULL;
>      virCommandPtr cmd = NULL;
> +    const char *type;
> +    char *secretPath = NULL;
> +    char *secretAlias = NULL;
>  
>      img_tool = virFindFileInPath("qemu-img");
>      if (!img_tool) {
> @@ -2300,19 +2336,56 @@ storageBackendResizeQemuImg(virStorageVolDefPtr vol,
>          return -1;
>      }
>  
> +    if (vol->target.encryption) {
> +        if (vol->target.format == VIR_STORAGE_FILE_RAW)
> +            type = "luks";
> +        else
> +            type = virStorageFileFormatTypeToString(vol->target.format);
> +
> +        storageBackendLoadDefaultSecrets(conn, vol);
> +
> +        if (storageBackendCreateQemuImgCheckEncryption(vol->target.format,
> +                                                       type, NULL, vol) < 0)
> +            goto cleanup;
> +
> +        if (!(secretPath =
> +              storageBackendCreateQemuImgSecretPath(conn, pool, vol)))
> +            goto cleanup;
> +
> +        if (virAsprintf(&secretAlias, "%s_luks0", vol->name) < 0)
> +            goto cleanup;
> +    }
> +
>      /* Round capacity as qemu-img resize errors out on sizes which are not
>       * a multiple of 512 */
>      capacity = VIR_ROUND_UP(capacity, 512);
>  
>      cmd = virCommandNew(img_tool);
> -    virCommandAddArgList(cmd, "resize", vol->target.path, NULL);
> +    if (!vol->target.encryption) {
> +        virCommandAddArgList(cmd, "resize", vol->target.path, NULL);
> +    } else {
> +        virCommandAddArgList(cmd, "resize", NULL);

Or just virCommandAddArd(cmd, "resize");

> +
> +        if (storageBackendCreateQemuImgSecretObject(cmd, secretPath,
> +                                                    secretAlias) < 0)
> +            goto cleanup;
> +
> +        if (storageBackendResizeQemuImgImageOpts(cmd, vol->target.path,
> +                                                 secretAlias) < 0)
> +            goto cleanup;
> +    }

Michal