Re: [PATCH] add new prctl for a per process wide close on exec

[Al Viro <viro@ZenIV.linux.org.uk>]

On Tue, Oct 22, 2013 at 09:27:18PM +0200, Stefani Seibold wrote:

> This patch will increase security since no developers can review all libraries
> which there are using. Also in a team of developers it is not always possible
> to have a full survey over the code which is produced. Or the output of a code
> generators and so one. This patch allows a kind of preventive measures.
> 
> It can also prevent resource occupation. Imagine a long running process (a
> daemon) is execute from the application after open some file desciptors. For
> example libpcsclite.so will not open the socket with SOCK_CLOEXEC. Or a device
> driver which alows only a single open. In both cases the resource cannot
> reopened after a close. Sigh!
> 
> What do you think?

That it's a bad idea.  Not to mention anything else, the same unreviewed
libraries can get buggered if the program sets that "global close-on-exec"
and it's not at all obvious whether the breakage from that change will be less
or more dangerous than leaking opened files to children.

Al, fully expecting the Linux S-M crowd to jump on that one and come up with
yet another one-shot LSM... ;-/