Commit Graph

7 Commits

Author SHA1 Message Date
Michal Privoznik
8b1660e530 security: Don't remember owner for shared resources
This effectively reverts d7420430ce and adds new code.

Here is the problem: Imagine a file X that is to be shared
between two domains as a disk. Let the first domain (vm1) have
seclabel remembering turned on and the other (vm2) has it turned
off. Assume that both domains will run under the same user, but
the original owner of X is different (i.e. trying to access X
without relabelling leads to EPERM).

Let's start vm1 first. This will cause X to be relabelled and to
gain new attributes:

  trusted.libvirt.security.ref_dac="1"
  trusted.libvirt.security.dac="$originalOwner"

When vm2 is started, X will again be relabelled, but since the
new label is the same as X already has (because of vm1) nothing
changes and vm1 and vm2 can access X just fine. Note that no
XATTR is changed (especially the refcounter keeps its value of 1)
because the vm2 domain has the feature turned off.

Now, vm1 is shut off and vm2 continues running. In seclabel
restore process we would get to X and since its refcounter is 1
we would restore the $originalOwner on it. But this is unsafe to
do because vm2 is still using X (remember the assumption that
$originalOwner and vm2's seclabel are distinct?).

The problem is that refcounter stored in XATTRs doesn't reflect
the actual times a resource is in use. Since I don't see any easy
way around it let's just not store original owner on shared
resources. Shared resource in world of domain disks is:

  - whole backing chain but the top layer,
  - read only disk (we don't require CDROM to be explicitly
    marked as shareable),
  - disk marked as shareable.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
760fa05436 qemusecuritymock: Allow some paths to be not restored
Some paths will not be restored. Because we can't possibly know
if they are still in use or not. Reflect this in the test so that
we can test more domains. Also see next commit for more detailed
explanation.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
90540a37be qemusecuritytest: Fix capabilities loading
Having to enumerate all capabilities that we want domain to have
is too verbose and prevents us from adding more tests. Have the
domain always have the latest x86_64 capabilities. This means
that we have to drop two arm tests, but on the other hand, I'm
introducing 50 new cases. I've listed 50 biggest .args files and
added those:

  libvirt.git $ ls -Sr $(find tests/qemuxml2argvdata/ \
  -type f -iname "*.x86_64-latest.args") | tail -n 50

Except for two:
1) disk-backing-chains-noindex - this XML has some disks with
backing chain. And since set is done on the whole backing chain
and restore only on the top layer this would lead to instant test
failure. Don't worry, secdrivers will be fixed shortly too and
the test case will be added.

2) hostdev-mdev-display-spice-egl-headless - for this XML
secdriver tries to find IOMMU group that mdev lives in. Since we
are not mocking sysfs access this test case would fail.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:03 +02:00
Michal Privoznik
3c02d383f9 qemusecuritytest: Use AUTOFREE/AUTOUNREF
This simplifies the code a bit and removes the need for cleanup
label in one case. In the other case the label is kept because
it's going to be used later.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:03 +02:00
Michal Privoznik
1d34d2462e qemusecuritytest: Drop unused variable
The @securityManager variable in testDomain() is unused. Drop it.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:03 +02:00
Michal Privoznik
8ffb5f2738 qemusecuritymock: Introduce and use freePaths()
Problem with current approach is that if
qemuSecuritySetAllLabel() fails, then the @chown_paths and
@xattr_paths hash tables are not freed and preserve values
already stored there into the next test case.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:03 +02:00
Michal Privoznik
1e63dea999 tests: Introduce qemusecuritytest
This test checks if security label remembering works correctly.
It uses qemuSecurity* APIs to do that. And some mocking (even
though it's not real mocking as we are used to from other tests
like virpcitest). So far, only DAC driver is tested.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2018-12-19 15:32:43 +01:00