Jack Howarth <howa...@bromo.med.uc.edu> writes: > What is the current state of supporting hardened operating systems > that default to -fpie/-fPIE/-pie in gcc trunk? Do those releases still use > their own patches for gcc or has all of those changes been committed to gcc > trunk? > If so, does anyone recall the specific commits? In particular, I am interested > in any fixes to boehm-gc, libffi and pch to support PIE.
I know there are variants of gcc out there which default to -fPIE when compiling and -pie when linking. As far as I know there is no support for that in trunk, unless you count the --with-specs configure option which may be used to implement these defaults. I don't see why -pie should make any difference for boehm-gc or libffi. Is there some known problem with them? For PCH what matters is not whether gcc defaults to generating PIE, but whether gcc itself is compiled as a PIE. In general I believe that a PIE gcc will not support PCH--it will work most of the time, but will occasionally fail. However, I have not actually tested this. If I'm right about this limitation, it would be quite difficult to fix given the current PCH implementation. Fortunately, as far as I can see, the kind of attacks which PIE protects against are unimportant when attacking gcc, as gcc simply runs under your own user ID on your own system. Anything the user can somehow suborn gcc into doing, the user can do anyhow. So I see no reason to build gcc as a PIE. Of course those considerations would change if somebody is running a compilation server on the net which invokes gcc; such a setup might get some small benefit from building gcc as a PIE, but such a setup would be unlikely to support PCH in any case. Ian
