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[libvirt] [PATCH 4/9] Add support for encrypted (qcow) volume creation.



Supports only virStorageVolCreateXML, not virStorageVolCreateXMLFrom.

Curiously, qemu-img does not need the passphrase for anything to create
an encrypted volume.  This implementation is sufficient for the qcow2
format, and for other formats when all encryption parameters are
pre-specified.

The qcow2 passphrase is stored in libvirt only during the volume
creation operation, and automatically deleted afterwards.  Other users
might be able to query the volume properties while the volume is being
created, but virStorageVolGetXMLDesc() won't reveal the passphrase to
them.

An earlier patch description has mentioned the possibility of a libvirt
user specifying only the encryption format (or not even the format),
letting libvirt to choose the parameters and return them.  This would
require libvirt interface extensions, and it is not supported by this
patch.
---
 src/storage_backend.c         |   41 +++++++++++++++++++++++++++++++++++++++--
 src/storage_backend_disk.c    |    7 +++++++
 src/storage_backend_fs.c      |    7 +++++++
 src/storage_backend_logical.c |    7 +++++++
 src/storage_driver.c          |    4 ++++
 5 files changed, 64 insertions(+), 2 deletions(-)

diff --git a/src/storage_backend.c b/src/storage_backend.c
index 1664804..42c59ad 100644
--- a/src/storage_backend.c
+++ b/src/storage_backend.c
@@ -246,6 +246,13 @@ virStorageBackendCreateRaw(virConnectPtr conn,
     unsigned long long remain;
     char *buf = NULL;
 
+    if (vol->encryption != NULL) {
+        virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                              "%s", _("storage pool does not support encrypted "
+                                      "volumes"));
+        return -1;
+    }
+
     if ((fd = open(vol->target.path, O_RDWR | O_CREAT | O_EXCL,
                    vol->target.perms.mode)) < 0) {
         virReportSystemError(conn, errno,
@@ -346,15 +353,17 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
                             NULL;
 
     const char **imgargv;
+    /* The extra NULL field is for indicating encryption (-e). */
     const char *imgargvnormal[] = {
         NULL, "create",
         "-f", type,
         vol->target.path,
         size,
         NULL,
+        NULL
     };
     /* Extra NULL fields are for including "backingType" when using
-     * kvm-img. It's -F backingType
+     * kvm-img (-F backingType), and for indicating encryption (-e).
      */
     const char *imgargvbacking[] = {
         NULL, "create",
@@ -364,6 +373,7 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
         size,
         NULL,
         NULL,
+        NULL,
         NULL
     };
     const char *convargv[] = {
@@ -417,6 +427,22 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
         }
     }
 
+    if (vol->encryption != NULL) {
+        if (vol->encryption->format != VIR_STORAGE_ENCRYPTION_FORMAT_QCOW) {
+            virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                                  _("unsupported volume encryption format %d"),
+                                  vol->encryption->format);
+            return -1;
+        }
+        if (vol->target.format != VIR_STORAGE_VOL_FILE_QCOW &&
+            vol->target.format != VIR_STORAGE_VOL_FILE_QCOW2) {
+            virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                                  _("qcow volume encryption unsupported with "
+                                    "volume format %s"), type);
+            return -1;
+        }
+    }
+
     if ((create_tool = virFindFileInPath("kvm-img")) != NULL)
         use_kvmimg = 1;
     else if ((create_tool = virFindFileInPath("qemu-img")) != NULL)
@@ -437,11 +463,16 @@ virStorageBackendCreateQemuImg(virConnectPtr conn,
             imgargvbacking[7] = backingType;
             imgargvbacking[8] = vol->target.path;
             imgargvbacking[9] = size;
-        }
+            if (vol->encryption != NULL)
+                imgargvbacking[10] = "-e";
+        } else if (vol->encryption != NULL)
+            imgargvbacking[8] = "-e";
         imgargv = imgargvbacking;
     } else {
         imgargvnormal[0] = create_tool;
         imgargv = imgargvnormal;
+        if (vol->encryption != NULL)
+            imgargv[6] = "-e";
     }
 
 
@@ -490,6 +521,12 @@ virStorageBackendCreateQcowCreate(virConnectPtr conn,
                               "qcow-create"));
         return -1;
     }
+    if (vol->encryption != NULL) {
+        virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                              "%s", _("encrypted volumes not supported with "
+                                      "qcow-create"));
+        return -1;
+    }
 
     /* Size in MB - yes different units to qemu-img :-( */
     snprintf(size, sizeof(size), "%llu", vol->capacity/1024/1024);
diff --git a/src/storage_backend_disk.c b/src/storage_backend_disk.c
index ae2acae..8f4f0ed 100644
--- a/src/storage_backend_disk.c
+++ b/src/storage_backend_disk.c
@@ -557,6 +557,13 @@ virStorageBackendDiskCreateVol(virConnectPtr conn,
         NULL
     };
 
+    if (vol->encryption != NULL) {
+        virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                              "%s", _("storage pool does not support encrypted "
+                                      "volumes"));
+        return -1;
+    }
+
     if (virStorageBackendDiskPartFormat(conn, pool, vol, partFormat) != 0) {
         return -1;
     }
diff --git a/src/storage_backend_fs.c b/src/storage_backend_fs.c
index 0219eb6..b43daef 100644
--- a/src/storage_backend_fs.c
+++ b/src/storage_backend_fs.c
@@ -1070,6 +1070,13 @@ _virStorageBackendFileSystemVolBuild(virConnectPtr conn,
     int tool_type;
 
     if (inputvol) {
+        if (vol->encryption != NULL) {
+            virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                                  "%s", _("storage pool does not support "
+                                          "building encrypted volumes from "
+                                          "other volumes"));
+            return -1;
+        }
         create_func = virStorageBackendGetBuildVolFromFunction(conn, vol,
                                                                inputvol);
         if (!create_func)
diff --git a/src/storage_backend_logical.c b/src/storage_backend_logical.c
index 6c123ae..822d321 100644
--- a/src/storage_backend_logical.c
+++ b/src/storage_backend_logical.c
@@ -581,6 +581,13 @@ virStorageBackendLogicalCreateVol(virConnectPtr conn,
     };
     const char **cmdargv = cmdargvnew;
 
+    if (vol->encryption != NULL) {
+        virStorageReportError(conn, VIR_ERR_NO_SUPPORT,
+                              "%s", _("storage pool does not support encrypted "
+                                      "volumes"));
+        return -1;
+    }
+
     if (vol->backingStore.path) {
         cmdargv = cmdargvsnap;
     }
diff --git a/src/storage_driver.c b/src/storage_driver.c
index e9ecb20..98db9a0 100644
--- a/src/storage_driver.c
+++ b/src/storage_driver.c
@@ -1305,6 +1305,8 @@ storageVolumeCreateXML(virStoragePoolPtr obj,
 cleanup:
     if (volobj)
         virUnrefStorageVol(volobj);
+    if (voldef)
+        virStorageEncryptionDropSecrets(voldef->encryption);
     virStorageVolDefFree(voldef);
     if (pool)
         virStoragePoolObjUnlock(pool);
@@ -1466,6 +1468,8 @@ storageVolumeCreateXMLFrom(virStoragePoolPtr obj,
 cleanup:
     if (volobj)
         virUnrefStorageVol(volobj);
+    if (newvol)
+        virStorageEncryptionDropSecrets(newvol->encryption);
     virStorageVolDefFree(newvol);
     if (pool)
         virStoragePoolObjUnlock(pool);
-- 
1.6.2.5


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