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Re: [libvirt] PATCH: 1/7: Removing state from lxc_vm_t



On Mon, Aug 11, 2008 at 12:50:46PM +0200, Jim Meyering wrote:
> "Daniel P. Berrange" <berrange redhat com> wrote:
> > This patch does some simple re-factoring of the way the TTYs and
> > control socket are handled to reduce the amount of state stored
> > in the lxc_vm_t structure, in preparation for the switchover to
> > the generic domain handling APIs.
> 
> One more thing:
> 
> ...
> > diff -r 63b8398c302e src/lxc_container.c
> > --- a/src/lxc_container.c	Mon Jul 14 12:18:23 2008 +0100
> > +++ b/src/lxc_container.c	Tue Jul 15 11:55:48 2008 +0100
> ...
> > -    close(0); close(1); close(2);
> > +    /* Just in case someone forget to set FD_CLOEXEC, explicitly
> > +     * close all FDs before executing the container */
> > +    open_max = sysconf (_SC_OPEN_MAX);
> > +    for (i = 0; i < open_max; i++)
> > +        if (i != ttyfd)
> > +            close(i);
> 
> Do you really need to close all file descriptors > 2 ?
> I seem to recall that an application doing this caused trouble
> when it closed a file descriptor (opened via the shell that I
> was using for log output.

This is important to ensuring no file descriptors are leaked into the
container we run because that would be a potential security problem.
In any case this code will be replaced by a call to virExec() by a 
later patch in this series.

Daniel
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