[libvirt] [PATCH v2 0/4] Keep original file label

[Michal Privoznik]

This is a rework of v1 with which it doesn't have a single line
in common :)

This version uses XATTR heavily. The first two patches utilize
extended attributes to store the original owner and the reference
counter, while the next two are just a proof of concept. They
suffer with a serious defect - if there's already an ACL entry
for user, we completely overwrite it and dispose.

Anyway - I am solving atomicity problem for now. I need to
understand virlockd better, so if somebody has a bright idea how
to solve locking or somebody is willing to implement it himself,
feel free.

There are several questions I think we should agree on:

- namespace of XATTR labels:
  There are currently 4 namespaces: security, system, trusted and
  user.  I think trusted suits our needs the best. See man
  attr(5) for their description.

- Is it enough if we keep the original label only on those
  filesystems supporting XATTR? If so, should we turn libattr
  into hard dependency?

- Keeping the whole logic within XATTR drops need for security
  driver state XML. But what about those filesystems which does
  not support XATTR by design? (I don't want to point my finger)

- The atomicity problem. I guess we want virlockd however we
  don't want to enforce users to configure anything in order to
  use this functionality. But I don't think this can be achieved,
  if locks need to be shared among other hosts, right?

Michal Privoznik (4):
  virFile: Add APIs for extended attributes handling
  security_dac: Remember owner prior chown() and restore on relabel
  virfile: Introduce internal API for managing ACL
  security_dac: Favour ACLs over chown()

 configure.ac                |   2 +
 libvirt.spec.in             |   6 +
 src/libvirt_private.syms    |   5 +
 src/security/security_dac.c | 209 +++++++++++++++++++++++++-----
 src/util/virfile.c          | 308 ++++++++++++++++++++++++++++++++++++++++++++
 src/util/virfile.h          |  19 +++
 6 files changed, 515 insertions(+), 34 deletions(-)

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1.8.1.5