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From 62516194c424abad3bec12ea360dde06617fe97d Mon Sep 17 00:00:00 2001
From: Matthew Booth <mbooth@redhat.com>
Date: Fri, 11 Dec 2015 13:40:54 +0000
Subject: [PATCH 3/3] Fix backing file detection in libvirt live snapshot
When doing a live snapshot, the libvirt driver creates an intermediate
qcow2 file with the same backing file as the original disk. However,
it calls qemu-img info without specifying the input format explicitly.
An authenticated user can write data to a raw disk which will cause
this code to misinterpret the disk as a qcow2 file with a
user-specified backing file on the host, and return an arbitrary host
file as the backing file.
This bug does not appear to result in a data leak in this case, but
this is hard to verify. It certainly results in corrupt output.
Closes-Bug: #1524274
Change-Id: I11485f077d28f4e97529a691e55e3e3c0bea8872
(cherry picked from commit ccea9095d9fb5bcdcb61ee5e352c4a8163754b9d)
---
nova/tests/unit/virt/libvirt/fake_libvirt_utils.py | 4 ++--
nova/tests/unit/virt/libvirt/test_driver.py | 7 ++++---
nova/virt/images.py | 8 +++++---
nova/virt/libvirt/driver.py | 11 +++++++----
nova/virt/libvirt/utils.py | 9 +++++----
5 files changed, 23 insertions(+), 16 deletions(-)
diff --git a/nova/tests/unit/virt/libvirt/fake_libvirt_utils.py b/nova/tests/unit/virt/libvirt/fake_libvirt_utils.py
index 52d1e85..b474687 100644
--- a/nova/tests/unit/virt/libvirt/fake_libvirt_utils.py
+++ b/nova/tests/unit/virt/libvirt/fake_libvirt_utils.py
@@ -32,11 +32,11 @@ def create_cow_image(backing_file, path):
pass
-def get_disk_size(path):
+def get_disk_size(path, format=None):
return 0
-def get_disk_backing_file(path):
+def get_disk_backing_file(path, format=None):
return disk_backing_files.get(path, None)
diff --git a/nova/tests/unit/virt/libvirt/test_driver.py b/nova/tests/unit/virt/libvirt/test_driver.py
index 6fd8728..6d0afdf 100644
--- a/nova/tests/unit/virt/libvirt/test_driver.py
+++ b/nova/tests/unit/virt/libvirt/test_driver.py
@@ -12018,7 +12018,7 @@ class LibvirtConnTestCase(test.NoDBTestCase):
image_meta = objects.ImageMeta.from_dict(self.test_image_meta)
drvr._live_snapshot(self.context, self.test_instance, guest,
- srcfile, dstfile, "qcow2", image_meta)
+ srcfile, dstfile, "qcow2", "qcow2", image_meta)
mock_dom.XMLDesc.assert_called_once_with(flags=(
fakelibvirt.VIR_DOMAIN_XML_INACTIVE |
@@ -12029,8 +12029,9 @@ class LibvirtConnTestCase(test.NoDBTestCase):
fakelibvirt.VIR_DOMAIN_BLOCK_REBASE_REUSE_EXT |
fakelibvirt.VIR_DOMAIN_BLOCK_REBASE_SHALLOW))
- mock_size.assert_called_once_with(srcfile)
- mock_backing.assert_called_once_with(srcfile, basename=False)
+ mock_size.assert_called_once_with(srcfile, format="qcow2")
+ mock_backing.assert_called_once_with(srcfile, basename=False,
+ format="qcow2")
mock_create_cow.assert_called_once_with(bckfile, dltfile, 1004009)
mock_chown.assert_called_once_with(dltfile, os.getuid())
mock_snapshot.assert_called_once_with(dltfile, "qcow2",
diff --git a/nova/virt/images.py b/nova/virt/images.py
index e2b5b91..6f3e487 100644
--- a/nova/virt/images.py
+++ b/nova/virt/images.py
@@ -44,7 +44,7 @@ CONF.register_opts(image_opts)
IMAGE_API = image.API()
-def qemu_img_info(path):
+def qemu_img_info(path, format=None):
"""Return an object containing the parsed output from qemu-img info."""
# TODO(mikal): this code should not be referring to a libvirt specific
# flag.
@@ -56,8 +56,10 @@ def qemu_img_info(path):
msg = (_("Path does not exist %(path)s") % {'path': path})
raise exception.InvalidDiskInfo(reason=msg)
- out, err = utils.execute('env', 'LC_ALL=C', 'LANG=C',
- 'qemu-img', 'info', path)
+ cmd = ('env', 'LC_ALL=C', 'LANG=C', 'qemu-img', 'info', path)
+ if format is not None:
+ cmd = cmd + ('-f', format)
+ out, err = utils.execute(*cmd)
if not out:
msg = (_("Failed to run qemu-img info on %(path)s : %(error)s") %
{'path': path, 'error': err})
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index 51b1e4b..53a27b2 100644
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -1434,7 +1434,8 @@ class LibvirtDriver(driver.ComputeDriver):
# NOTE(xqueralt): libvirt needs o+x in the temp directory
os.chmod(tmpdir, 0o701)
self._live_snapshot(context, instance, guest, disk_path,
- out_path, image_format, image_meta)
+ out_path, source_format, image_format,
+ image_meta)
else:
snapshot_backend.snapshot_extract(out_path, image_format)
finally:
@@ -1540,7 +1541,7 @@ class LibvirtDriver(driver.ComputeDriver):
self._set_quiesced(context, instance, image_meta, False)
def _live_snapshot(self, context, instance, guest, disk_path, out_path,
- image_format, image_meta):
+ source_format, image_format, image_meta):
"""Snapshot an instance without downtime."""
dev = guest.get_block_device(disk_path)
@@ -1558,9 +1559,11 @@ class LibvirtDriver(driver.ComputeDriver):
# in QEMU 1.3. In order to do this, we need to create
# a destination image with the original backing file
# and matching size of the instance root disk.
- src_disk_size = libvirt_utils.get_disk_size(disk_path)
+ src_disk_size = libvirt_utils.get_disk_size(disk_path,
+ format=source_format)
src_back_path = libvirt_utils.get_disk_backing_file(disk_path,
- basename=False)
+ format=source_format,
+ basename=False)
disk_delta = out_path + '.delta'
libvirt_utils.create_cow_image(src_back_path, disk_delta,
src_disk_size)
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 062b2fb..7b0cf42 100644
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -160,24 +160,25 @@ def pick_disk_driver_name(hypervisor_version, is_block_dev=False):
return None
-def get_disk_size(path):
+def get_disk_size(path, format=None):
"""Get the (virtual) size of a disk image
:param path: Path to the disk image
+ :param format: the on-disk format of path
:returns: Size (in bytes) of the given disk image as it would be seen
by a virtual machine.
"""
- size = images.qemu_img_info(path).virtual_size
+ size = images.qemu_img_info(path, format).virtual_size
return int(size)
-def get_disk_backing_file(path, basename=True):
+def get_disk_backing_file(path, basename=True, format=None):
"""Get the backing file of a disk image
:param path: Path to the disk image
:returns: a path to the image's backing store
"""
- backing_file = images.qemu_img_info(path).backing_file
+ backing_file = images.qemu_img_info(path, format).backing_file
if backing_file and basename:
backing_file = os.path.basename(backing_file)
--
2.5.0
|
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