[libvirt] [PATCH 2/2] storage: Check qemu-img encryption type capability

[John Ferlan]

https://bugzilla.redhat.com/show_bug.cgi?id=1526382

As of QEMU 2.9, qemu-img has enforced using the "key-secret" for
creation of encrypted volumes. That is, LUKS encryption is now
required and the old (awful) qcow[2] encryption methodolgy is
no longer supported.

In order to check for this, we scan the qemu-img -o help options
looking for "key-secret" and if set, we enforce during the create
volume processing that the about to be encrypted volume doesn't
attempt to use the old crufty encryption mechanism.

Signed-off-by: John Ferlan <jferlan at redhat.com>
---
 src/storage/storage_util.c | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/src/storage/storage_util.c b/src/storage/storage_util.c
index 7df52239c2..d2e02a57ca 100644
--- a/src/storage/storage_util.c
+++ b/src/storage/storage_util.c
@@ -797,6 +797,7 @@ storagePloopResize(virStorageVolDefPtr vol,
 enum {
     QEMU_IMG_BACKING_FORMAT_OPTIONS = 0,
     QEMU_IMG_BACKING_FORMAT_OPTIONS_COMPAT,
+    QEMU_IMG_BACKING_FORMAT_OPTIONS_KEY_SECRET,
 };
 
 static char *
@@ -824,6 +825,14 @@ virStorageBackendQemuImgSupportsCompat(const char *output)
     return strstr(output, "\ncompat ");
 }
 
+
+static bool
+virStorageBackendQemuImgRequiresKeySecret(const char *output)
+{
+    return strstr(output, "key-secret");
+}
+
+
 static int
 virStorageBackendQEMUImgBackingFormat(const char *qemuimg)
 {
@@ -843,6 +852,11 @@ virStorageBackendQEMUImgBackingFormat(const char *qemuimg)
     if (virStorageBackendQemuImgSupportsCompat(output))
         ret = QEMU_IMG_BACKING_FORMAT_OPTIONS_COMPAT;
 
+    /* QEMU 2.9 enforced that qemu-img creation of an encrypted volume
+     * uses LUKS encryption. */
+    if (virStorageBackendQemuImgRequiresKeySecret(output))
+        ret = QEMU_IMG_BACKING_FORMAT_OPTIONS_KEY_SECRET;
+
  cleanup:
     VIR_FREE(output);
     return ret;
@@ -934,6 +948,7 @@ storageBackendCreateQemuImgOpts(virStorageEncryptionInfoDefPtr enc,
 
 /* storageBackendCreateQemuImgCheckEncryption:
  * @format: format of file found
+ * @imgformat: image format capability
  * @conn: pointer to connection
  * @vol: pointer to volume def
  *
@@ -943,6 +958,7 @@ storageBackendCreateQemuImgOpts(virStorageEncryptionInfoDefPtr enc,
  */
 static int
 storageBackendCreateQemuImgCheckEncryption(int format,
+                                           int imgformat,
                                            const char *type,
                                            virStorageVolDefPtr vol)
 {
@@ -956,6 +972,12 @@ storageBackendCreateQemuImgCheckEncryption(int format,
                            vol->target.encryption->format);
             return -1;
         }
+        if (imgformat >= QEMU_IMG_BACKING_FORMAT_OPTIONS_KEY_SECRET) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("qemu-img no longer supports qcow encryption, "
+                             "use LUKS encryption instead"));
+            return -1;
+        }
         if (enc->nsecrets > 1) {
             virReportError(VIR_ERR_XML_ERROR, "%s",
                            _("too many secrets for qcow encryption"));
@@ -1264,8 +1286,8 @@ virStorageBackendCreateQemuImgCmdFromVol(virStoragePoolObjPtr pool,
         return NULL;
 
     if (info.encryption &&
-        storageBackendCreateQemuImgCheckEncryption(info.format, type,
-                                                   vol) < 0)
+        storageBackendCreateQemuImgCheckEncryption(info.format, imgformat,
+                                                   type, vol) < 0)
         return NULL;
 
 
@@ -2359,6 +2381,7 @@ storageBackendResizeQemuImg(virStoragePoolObjPtr pool,
 {
     int ret = -1;
     char *img_tool = NULL;
+    int imgformat;
     virCommandPtr cmd = NULL;
     const char *type;
     char *secretPath = NULL;
@@ -2371,6 +2394,10 @@ storageBackendResizeQemuImg(virStoragePoolObjPtr pool,
         return -1;
     }
 
+    imgformat = virStorageBackendQEMUImgBackingFormat("qemu-img");
+    if (imgformat < 0)
+        goto cleanup;
+
     if (vol->target.encryption) {
         if (vol->target.format == VIR_STORAGE_FILE_RAW)
             type = "luks";
@@ -2380,6 +2407,7 @@ storageBackendResizeQemuImg(virStoragePoolObjPtr pool,
         storageBackendLoadDefaultSecrets(vol);
 
         if (storageBackendCreateQemuImgCheckEncryption(vol->target.format,
+                                                       imgformat,
                                                        type, vol) < 0)
             goto cleanup;
 
-- 
2.13.6