_hardened_build not affecting libtool-compiled libraries
Richard W.M. Jones
rjones at redhat.com
Mon Jun 24 19:47:46 UTC 2013
On Mon, Jun 24, 2013 at 08:46:51PM +0100, Richard W.M. Jones wrote:
> On Mon, Jun 24, 2013 at 09:13:29PM +0200, Miloslav Trmač wrote:
> > On Mon, Jun 24, 2013 at 8:46 PM, Richard W.M. Jones <rjones at redhat.com> wrote:
> > > but the plugins from that build are not hardened fully:
> > Isn't it possible that the plugins are just so trivial that there were
> > no opportunities for hardening?
> > > $ hardening-check ./usr/lib64/nbdkit/plugins/nbdkit-example1-plugin.so
> > > ./usr/lib64/nbdkit/plugins/nbdkit-example1-plugin.so:
> > > Position Independent Executable: no, regular shared library (ignored)
> > > Stack protected: no, not found!
> > No on-stack arrays that I can find.
> > > Fortify Source functions: no, only unprotected functions found!
> > I can see libc calls with compile-time-known destination sizes except
> > for example1_load () where it can be statically proven the call is
> > safe.
> Yes, I think you're right. I only checked the simple example*
> plugins. The xz plugin which is rather more complicated does seem to
> be protected:
> $ hardening-check ./usr/lib64/nbdkit/plugins/nbdkit-xz-plugin.so
> Position Independent Executable: no, regular shared library (ignored)
> Stack protected: yes
> Fortify Source functions: yes (some protected functions found)
> Read-only relocations: yes
> Immediate binding: yes
Note there is still a problem that an LDFLAGS hack was needed in the
spec file, otherwise libtool (or something) eats the hardening LDFLAGS.
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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