736 Commits

Author SHA1 Message Date
Cole Robinson
a36d3b88d6 security: selinux: Add is_toplevel to SetImageLabelInternal
This will simplify future patches and make the logic easier to follow

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
65181d419e security: selinux: Drop !parent handling in SetImageLabelInternal
The only caller always passes in a non-null parent

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
6f1cd0a54e security: selinux: Simplify SetImageLabelInternal
All the SetFileCon calls only differ by the label they pass in.
Rework the conditionals to track what label we need, and use a
single SetFileCon call

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
efe3575e60 security: dac: Label externalDataStore
We mirror the labeling strategy that was used for its sibling
image

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
aa736c098e security: dac: break out SetImageLabelRelative
This will be used for recursing into externalDataStore

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
ee5a367d06 security: dac: Restore image label for externalDataStore
Rename the existing virSecurityDACRestoreImageLabelInt
to virSecurityDACRestoreImageLabelSingle, and extend the new
ImageLabelInt handle externalDataStore

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
c1f0b31267 security: dac: Add is_toplevel to SetImageLabelInternal
This will simplify future patches and make the logic easier to follow

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Cole Robinson
a7262a664d security: dac: Drop !parent handling in SetImageLabelInternal
The only caller always passes in a non-null parent

Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 14:25:59 -04:00
Michal Privoznik
4e95cdcbb3 security: Don't remember labels for TPM
https://bugzilla.redhat.com/show_bug.cgi?id=1755803

The /dev/tpmN file can be opened only once, as implemented in
drivers/char/tpm/tpm-dev.c:tpm_open() from the kernel's tree. Any
other attempt to open the file fails. And since we're opening the
file ourselves and passing the FD to qemu we will not succeed
opening the file again when locking it for seclabel remembering.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 17:05:55 +02:00
Michal Privoznik
2b44cf8c32 security_dac: Allow selective remember/recall for chardevs
While in most cases we want to remember/recall label for a
chardev, there are some special ones (like /dev/tpm0) where we
don't want to remember the seclabel nor recall it. See next
commit for rationale behind.

While the easiest way to implement this would be to just add new
argument to virSecurityDACSetChardevLabel() this one is also a
callback for virSecurityManagerSetChardevLabel() and thus has
more or less stable set of arguments. Therefore, the current
virSecurityDACSetChardevLabel() is renamed to
virSecurityDACSetChardevLabelHelper() and the original function
is set to call the new one.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 17:05:41 +02:00
Michal Privoznik
1a84a1ced1 security: Try to lock only paths with remember == true
So far all items on the chown/setfilecon list have the same
.remember value.  But this will change shortly. Therefore, don't
try to lock paths which we won't manipulate XATTRs for.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 17:01:08 +02:00
Cole Robinson
4dfc4d525e security: apparmor: Allow RO /usr/share/edk2/
On Fedora, already whitelisted paths to AAVMF and OVMF binaries
are symlinks to binaries under /usr/share/edk2/. Add that directory
to the RO whitelist so virt-aa-helper-test passes

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-11 10:52:54 -04:00
Cole Robinson
3a15c47253 security: apparmor: Make storage_source_add_files recursively callable
This will simplify adding support for qcow2 external data_file

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:16 -04:00
Cole Robinson
b2b003db74 security: apparmor: Use only virStorageSource for disk paths
This is closer to what security_selinux.c does, and will help add
support for qcow2 external data_files

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:16 -04:00
Cole Robinson
c7eea3f559 security: apparmor: Push virStorageSource checks to add_file_path
This mirrors the code layout in security_selinux.c. It will also make
it easier to share the checks for qcow2 external data_file support
eventually

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:16 -04:00
Cole Robinson
7c0bf48bc9 security: apparmor: Pass virStorageSource to add_file_path
The virStorageSource must have everything it needs

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:16 -04:00
Cole Robinson
488fce1220 security: apparmor: Drop disk_foreach_iterator
There's only one caller, so open code the file_add_path behavior

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:16 -04:00
Cole Robinson
780f8c94ca security: apparmor: Remove unused ignoreOpenFailure
true is always passed here, so delete the unused code path and
adjust the associated comment

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:17:14 -04:00
Cole Robinson
cb757f9d32 conf: Move -virDomainDiskDefForeachPath to virt-aa-helper
It is the only user. Rename it to match the local style

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Cole Robinson <crobinso@redhat.com>
2019-10-09 14:16:53 -04:00
Chris Coulson
d660dd95ea security: AppArmor profile fixes for swtpm
The AppArmor profile generated by virt-aa-helper is too strict for swtpm.
This change contains 2 small fixes:
- Relax append access to swtpm's log file to permit write access instead.
Append access is insufficient because the log is opened with O_CREAT.
- Permit swtpm to acquire a lock on its lock file.

Signed-off-by: Chris Coulson <chris.coulson@canonical.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
2019-09-30 15:15:11 +02:00
Daniel P. Berrangé
2c535e50f5 util: remove some no-op thread functions
Neither virThreadInitialize or virThreadOnExit do anything since we
dropped the Win32 threads impl, in favour of win-pthreads with:

  commit 0240d94c36c8ce0e7c35b5be430acd9ebf5adcfa
  Author: Daniel P. Berrange <berrange@redhat.com>
  Date:   Wed Jan 22 16:17:10 2014 +0000

      Remove windows thread implementation in favour of pthreads

Reviewed-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2019-09-19 12:50:21 +01:00
Jim Fehlig
281a7f1d40 apparmor: avoid copying empty profile name
AppArmorGetSecurityProcessLabel copies the VM's profile name to the
label member of virSecurityLabel struct. If the profile is not loaded,
the name is set empty before calling virStrcpy to copy it. However,
virStrcpy will fail if src is empty (0 length), causing
AppArmorGetSecurityProcessLabel to needlessly fail. Simple operations
that report security driver information will subsequently fail

virsh dominfo test
Id:             248
Name:           test
...
Security model: apparmor
Security DOI:   0
error: internal error: error copying profile name

Avoid copying an empty profile name when the profile is not loaded.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
2019-09-13 12:26:51 -06:00
Daniel P. Berrangé
b1b878c512 util: activate directory override when used from library
The Perl bindings for libvirt use the test driver for unit tests. This
tries to load the cpu_map/index.xml file, and when run from an
uninstalled build will fail.

The problem is that virFileActivateDirOverride is called by our various
binaries like libvirtd, virsh, but is not called when a 3rd party app
uses libvirt.so

To deal with this we allow the LIBVIRT_DIR_OVERRIDE=1 env variable to be
set and make virInitialize look for this. The 'run' script will set it,
so now build using this script to run against an uninstalled tree we
will correctly resolve files to the source tree.

Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2019-09-10 11:03:35 +01:00
Michal Privoznik
6bb4242d9f lib: Define and use autofree for virConfPtr
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
2019-09-10 09:34:37 +02:00
Martin Kletzander
86289374ef selinux: Do not report an error when not returning -1
I guess the reason for that was the automatic interpretation/stringification of
setfilecon_errno, but the code was not nice to read and it was a bit confusing.
Also, the logs and error states get cleaner this way.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-31 08:48:51 +02:00
Michal Privoznik
8fe953805a security_selinux: Play nicely with network FS that only emulates SELinux
There are some network file systems that do support XATTRs (e.g.
gluster via FUSE). And they appear to support SELinux too.
However, not really. Problem is, that it is impossible to change
SELinux label of a file stored there, and yet we claim success
(rightfully - hypervisor succeeds in opening the file). But this
creates a problem for us - from XATTR bookkeeping POV, we haven't
changed the label and thus if we remembered any label, we must
roll back and remove it.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1740506

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-30 12:50:09 +02:00
Michal Privoznik
eaa2a064fa security_selinux: Drop virSecuritySELinuxSetFileconHelper
This function is no longer needed because after previous commits
it's just an alias to virSecuritySELinuxSetFilecon.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-30 12:46:54 +02:00
Michal Privoznik
b71d54f447 security_selinux: Drop @optional from _virSecuritySELinuxContextItem
Now, that we don't need to remember if setting context is
'optional' (the argument only made
virSecuritySELinuxSetFileconImpl() return a different success
code), we can drop it from the _virSecuritySELinuxContextItem
structure as we don't need to remember it in transactions.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-30 12:38:52 +02:00
Michal Privoznik
079c1d6a29 security_selinux: Drop virSecuritySELinuxSetFileconOptional()
There is no real difference between
virSecuritySELinuxSetFilecon() and
virSecuritySELinuxSetFileconOptional(). Drop the latter in favour
of the former.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-30 12:38:12 +02:00
Michal Privoznik
34712a5e3b virSecuritySELinuxSetFileconImpl: Drop @optional argument
The only thing that the @optional argument does is that it makes
the function return 1 instead of 0 if setting SELinux context
failed in a non-critical fashion. Drop the argument then and
return 1 in that case. This enables caller to learn if SELinux
context was set or not.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-30 12:33:04 +02:00
Nikolay Shirokovskiy
7c40211a5a security_util: verify xattrs only if ref is present
After 7cfb7aab573 commit starting a domain pullutes logs with
warnings like [1]. The reason is resource files do not
have timestamp before starting a domain and after destroying
domain the timestamp is cleared. Let's check the timestamp
only if attribute with refcounter is found.

[1] warning : virSecurityValidateTimestamp:198 : Invalid XATTR timestamp detected on \
    /some/path secdriver=dac

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@virtuozzo.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
2019-08-29 15:55:10 +02:00
Daniel P. Berrangé
d29c917ef4 src: honour the RUNSTATEDIR variable in all code
All code using LOCALSTATEDIR "/run" is updated to use RUNSTATEDIR
instead. The exception is the remote driver client which still
uses LOCALSTATEDIR "/run". The client needs to connect to remote
machines which may not be using /run, so /var/run is more portable
due to the /var/run -> /run symlink.

Some duplicate paths in the apparmor code are also purged.

There's no functional change by default yet since both expressions
expand to the same value.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
2019-08-27 10:23:13 +01:00
Michal Privoznik
7cfb7aab57 security_util: Remove stale XATTRs
It may happen that we leave some XATTRs behind. For instance, on
a sudden power loss, the host just shuts down without calling
restore on domain paths. This creates a problem, because when the
host starts up again, the XATTRs are there but they don't reflect
the true state and this may result in libvirt denying start of a
domain.

To solve this, save a unique timestamp (host boot time) among
with our XATTRs.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1741140

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
2019-08-22 17:05:17 +02:00
Michal Privoznik
6a2806fd54 security: Don't increase XATTRs refcounter on failure
If user has two domains, each have the same disk (configured for
RW) but each runs with different seclabel then we deny start of
the second domain because in order to do that we would need to
relabel the disk but that would cut the first domain off. Even if
we did not do that, qemu would fail to start because it would be
unable to lock the disk image for the second time. So far, this
behaviour is expected. But what is not expected is that we
increase the refcounter in XATTRs and leave it like that.

What happens is that when the second domain starts,
virSecuritySetRememberedLabel() is called, and since there are
XATTRs from the first domain it increments the refcounter and
returns it (refcounter == 2 at this point). Then callers
(virSecurityDACSetOwnership() and
virSecuritySELinuxSetFileconHelper()) realize that refcounter is
greater than 1 and desired seclabel doesn't match the one the
disk image already has and an error is produced. But the
refcounter is never decremented.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1740024

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-22 15:50:21 +02:00
Andrea Bolognani
60dfe76990 virt-aa-helper: Drop unnecessary AppArmor rule
Apparently /proc/self is automatically converted to /proc/@{pid}
before checking rules, which makes spelling it out explicitly
redundant.

Suggested-by: Jamie Strandboge <jamie@canonical.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
2019-08-22 10:58:41 +02:00
Michal Privoznik
359c7c1e94 security_util: Document virSecurityMoveRememberedLabel
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
2019-08-22 10:34:42 +02:00
Michal Privoznik
8ced0909e5 security_util: Use more VIR_AUTOFREE()
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
2019-08-22 10:34:42 +02:00
Andrea Bolognani
9c2446ed4a virt-aa-helper: Actually fix AppArmor profile
Tried previously in

  commit b1eb8b3e8fd1d4cb1da8e5e2b16f2c10837fd823
  Author: Andrea Bolognani <abologna@redhat.com>
  Date:   Mon Aug 19 10:23:42 2019 +0200

    virt-aa-helper: Fix AppArmor profile

  v5.6.0-243-gb1eb8b3e8f

with somewhat disappointing results.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2019-08-20 10:35:18 +02:00
Andrea Bolognani
b1eb8b3e8f virt-aa-helper: Fix AppArmor profile
Since

  commit 432faf259b696043ee5d7e8f657d855419a9a3fa
  Author: Michal Privoznik <mprivozn@redhat.com>
  Date:   Tue Jul 2 19:49:51 2019 +0200

    virCommand: use procfs to learn opened FDs

    When spawning a child process, between fork() and exec() we close
    all file descriptors and keep only those the caller wants us to
    pass onto the child. The problem is how we do that. Currently, we
    get the limit of opened files and then iterate through each one
    of them and either close() it or make it survive exec(). This
    approach is suboptimal (although, not that much in default
    configurations where the limit is pretty low - 1024). We have
    /proc where we can learn what FDs we hold open and thus we can
    selectively close only those.

    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
    Reviewed-by: Ján Tomko <jtomko@redhat.com>

  v5.5.0-173-g432faf259b

programs using the virCommand APIs on Linux need read access to
/proc/self/fd, or they will fail like

  error : virCommandWait:2796 : internal error: Child process
  (LIBVIRT_LOG_OUTPUTS=3:stderr /usr/lib/libvirt/virt-aa-helper -c
   -u libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6) unexpected exit
  status 1: libvirt:  error : cannot open directory '/proc/self/fd':
  Permission denied
  virt-aa-helper: error: apparmor_parser exited with error

Update the AppArmor profile for virt-aa-helper so that read access
to the relevant path is granted.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2019-08-19 15:47:24 +02:00
Andrea Bolognani
b194c3d9c7 virt-aa-helper: Call virCommandRawStatus()
The way we're processing the return status, using WIFEXITED() and
friends, only works when we have the raw return status; however,
virCommand defaults to processing the return status for us. Call
virCommandRawStatus() before virCommandRun() so that we get the raw
return status and the logic can actually work.

This results in guest startup failures caused by AppArmor issues
being reported much earlier: for example, if virt-aa-helper exits
with an error we're now reporting

  error: internal error: cannot load AppArmor profile 'libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6'

instead of the misleading

  error: internal error: Process exited prior to exec: libvirt:
  error : unable to set AppArmor profile 'libvirt-b20e9a8e-091a-45e0-8823-537119e98bc6'
  for '/usr/bin/qemu-system-x86_64': No such file or directory

Suggested-by: Ján Tomko <jtomko@redhat.com>
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2019-08-19 15:47:05 +02:00
Andrea Bolognani
7d3a0f56b8 virt-aa-helper: Use virCommand APIs directly
Right now we're using the virRun() convenience API, but that
doesn't allow the kind of control we want. Use the virCommand
APIs directly instead.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
2019-08-19 15:46:58 +02:00
Erik Skultety
5801ef06ec src: security: Replace bitwise OR with logical OR
Typo introduced by commit d73f3f58360.

https://bugzilla.redhat.com/show_bug.cgi?id=1738483

Signed-off-by: Erik Skultety <eskultet@redhat.com>
2019-08-07 12:08:46 +02:00
Michal Privoznik
c012e0f7fa virSecurityManagerMetadataLock: Skip over duplicate paths
If there are two paths on the list that are the same we need to
lock it only once. Because when we try to lock it the second time
then open() fails. And if it didn't, locking it the second time
would fail for sure. After all, it is sufficient to lock all
paths just once satisfy the caller.

Reported-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
2019-07-18 15:13:13 +02:00
Michal Privoznik
ee6501ab05 virSecurityManagerMetadataLock: Expand the comment on deadlocks
Document why we need to sort paths while it's still fresh in my
memory.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Daniel Henrique Barboza <danielhb413@gmail.com>
2019-07-18 15:13:05 +02:00
Christian Ehrhardt
bc85411c49
security: aa-helper: allow virt-aa-helper to read .vhd images
VHD images can be used as any other, so we should add them to the list
of types that virt-aa-helper can read when creating the per-guest rules
for backing files.

Signed-off-by: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Reviewed-by: Andrea Bolognani <abologna@redhat.com>
Acked-by: Jamie Strandboge <jamie@canonical.com>
2019-07-15 13:43:51 +02:00
Michal Privoznik
44a204e674 security_selinux: Implement virSecurityManagerMoveImageMetadata
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
a379b86cd2 security_dac: Implement virSecurityManagerMoveImageMetadata
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
d73f3f5836 security_util: Introduce virSecurityMoveRememberedLabel
A simple helper function that would be used from DAC and SELinux
drivers.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
8b74cecbdf security: Introduce virSecurityManagerMoveImageMetadata
The purpose of this API is to allow caller move XATTRs (or remove
them) from one file to another. This will be needed when moving
top level of disk chain (either by introducing new HEAD or
removing it).

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Cole Robinson <crobinso@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-07-03 08:36:04 +02:00
Michal Privoznik
8b1660e530 security: Don't remember owner for shared resources
This effectively reverts d7420430ce6 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