Re: [RFC] "Text file busy" when overwriting libraries

Alexander Viro
2001-10-15T12:11:10Z

On Mon, 15 Oct 2001, Alan Cox wrote:

> > Anyone can write it, but what the hell will he do without write access to
> > any place that wouldn't be mounted noexec? Environment can be restricted
> > even if you give them shell...
>
> He will type "perl" and interactively issue any damn syscall he likes
> subject to the normal permissions rules. Noexec is only useful for a user
> given virtually nothing.

... and will hit "permission denied" on attempt to exec /usr/bin/perl.
Blanket noexec on /usr instance mounted in his chroot with selective turning
the thing off on some binaries. And yes, I realize that one can always
hunt for buffer overruns in sh(1)...