Re: Secure Linux From Scratch

> > > I merged propolice.txt into winter.txt. Don't know what else to call
> > > it. SYNOPSIS:       ProPolice + Libsafe + Pax + PIE
> > > New hint and patches are on
> > > ftp://twocents.mooo.com/pub/
> >
> > Just went through it.....
> >
> > Nice. Couple of points though. It should be noted that Libsafe and
> > ProPolice both protect from buffer overflows. Thus there rises a question
> > of why we install both. Answer comes: Build statically a sample exploit
> > without -fstack-protector and see it seg fault even when libsafe is
> > present. Do it with -fstack-protector and it will *not* fail. Magic!!
> >
> > There should be added format string attacks to prove even more the
> > necessity for libsafe. I am currently working on some exploits to
> > provide.

<...>

> Libsafe and Propolice protect in completely different ways.

Agreed, acting as I proposed illustrates this difference, IMHO. I am not 
codemning any of the two-I just indicate a difference worth reporting in the 
book.

> Libsafe doesn't cost anything in preformance so I figured why not use it.

In fact, although libsafe's whitepaper claims that way, Immunux's whitepaper 
on StackGuard at the GCC procedings of 2003 notes that libsafe imposes some 
overhead (more than stackguard-propolice anyway) in string functions, whereas 
it is function calls that libsafe overthrows stackguard. Both have 
performance hit, but it is in both cases minimal. Certainly it is worth it. 
Should these points be added to the book? (yes if you ask me, thought I asked 
though, in case someone has reasons to suggest otherwise)

> winter.txt is
> anything but stable, it should be posible to use glibc-2.3.2 by adding two
> objects from Pax's site, I'm trying that right now. I'm trying to use
> whatever will work properly, but without downgrading to gcc-3.2. LFS-cvs is
> using a few newer packages, which are likely more secure then the ones from
> the 5.0 book. I would also like to note patch-2.5.9 is available in some
> places. I know the winter.txt needs more content and better tests, its
> public domain, so if you have additions feel free to add your name and
> submit changes, otherwise I'll get around to it.

-- 
himicos
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