[libvirt] [PATCH] Fix a compilation problem with LXC drop capabilities

[Daniel P. Berrange]

On Fri, May 29, 2009 at 04:42:54PM -0500, Serge E. Hallyn wrote:
> Quoting Ryota Ozaki (ozaki.ryota at gmail.com):
> > On Fri, May 29, 2009 at 9:20 PM, Daniel Veillard <veillard at redhat.com> wrote:
> 
> Hmm, yeah but note that often userspace is out of date with respect to
> "recent" new kernel-related defines.  I do a lot of testing on a rhel
> 5.3 partition with spanking-new kernels, so rare is the time that I
> don't have to do
> 
> #ifndef PR_CAPBSET_DROP
> #define PR_CAPBSET_DROP 24
> #endif
> 
> and same for clone flags (CLONE_NEWIPC), securebits, capabilities,
> etc.
> 
> So if the prctl(PR_CAPBSET_DROP) returns -ENOSYS then absolutely I
> agree, 

This makes sense as a way to deal with this problem, since it matches
what we already do with the various CLONE_XXX & MOUNT_XXX flags too.


NB, in the not too distant future I'm going to submit code for making
the libvirtd daemon drop alot of its capabilities, including clearing
the bounding set to prevent inheritance by any child processes except
in required circumstances. For that I'll likely use libcap-ng so we
will be able to stop callin prctl() directly in the LXC driver.

Regards,
Daniel

[1] libcap-ng isn't technically yet announced to the world, but it'll
    appear real soon...
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