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Re: Hardening patch

On Wed, Sep 07, 2011 at 01:46:21PM -0700, Kees Cook wrote:
> Hi,
> On Wed, Sep 07, 2011 at 10:37:13PM +0200, Guillem Jover wrote:
> > Also I'm not sure now if this has been brought up before, but the
> > bindnow option might have noticable startup speed impact depending
> > on the amount of symbols and shared objects to resolve and load.
> > The other options seem sane in general.
> This is, thankfully, no longer the case now that the linker uses string
> hashes for symbol resolution. I could not measure a difference in load
> times (any delta seemed lost in the noise) even for giant (firefox,
> openoffice.org) applications.

It was my understanding that for iceweasel the biggest cost of
starting up is in fact the dynamic linker resolving all the
relocations.  I currently still see this in libxul.so:
Relocation section '.rel.dyn' at offset 0x2b480 contains 180767 entries:
Relocation section '.rel.plt' at offset 0x18c578 contains 2853 entries:

Not to mention all the other libraries that get linked in.

Does anybody know if I set bindnow on an executable that it has effect
on all libraries that get loaded, or only on the directly linked

Did you try this after a reboot, or was everything already cached?

What behaviour do you get for shared libraries that have undefined
symbols?  I assume they'll break?


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