Re: hardening

[ng0 <ng0@n0.is>]

ng0 transcribed 1.6K bytes:
> Alex Vong transcribed 1.3K bytes:
> > Hello,
> > 
> > ng0@n0.is writes:
> > 
> > > Hi,
> > >
> > > as we've long talked and not really taken action on hardening builds
> > > I've started working on an opt-in way as last discussed in
> > > september 2016, modifying the gnu-build-system with a
> > > #:hardening-flags keyword.
> > >
> > > For my testing purposes I will use
> > >
> > >> CFLAGS="-fPIE -fstack-protector-all -D_FORTIFY_SOURCE=2"
> > > LDFLAGS="-Wl,-z,now -Wl,-z,relro"
> > >
> > > which is used by Gentoo, but adjustments (wether to opt-in or
> > > opt-out) will be made.
> > 
> > The flags I use (suggested by Debian Wiki[0]) are:
> > 
> >   CPPFLAGS=-D_FORTIFY_SOURCE=2
> 
> How does this differ from "-O2 -D_FORTIFY_SOURCE" in CFLAGS?
> I know O2 is optimization and that FORTIFY_SOURCE requires optimization
> to be specified.

Okay, I've read some related commits and bug tickets, I understand
the difference now.

> >   CFLAGS=-fstack-protector-strong
> >   CXXFLAGS=-fstack-protector-strong
> >   LDFLAGS=-Wl,-z,relro,-z,now,--as-needed
> 
> What are your opinions about:
>  -pipe -fPIE -fstack-shuffle -fstack-protector-all
> 
> > Also, should we use retpoline flags for all native binaries? This
> > article[1] suggests ``applying a software mitigation (e.g., Google's
> > Retpoline) to the hypervisor, operating system kernel, system programs
> > and libraries, and user applications''. I've sent a patch to do so when
> > bootstraping GCC 7 itself[2] but no reply are received yet (maybe I
> > should have open a new bug instead of changing the title of an old
> > bug).
> > 
> > [0]: https://wiki.debian.org/Hardening
> > [1]: https://security.googleblog.com/2018/01/more-details-about-mitigations-for-cpu_4.html
> > [2]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=30111
> > 
> 
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