Hi!
On Sun, 2023-07-02 at 00:02:46 +0300, Adrian Bunk wrote:
> Package: dpkg-dev
> Version: 1.21.22
> Severity: normal
> X-Debbugs-Cc: debian-al...@lists.debian.org, debian-ia64@lists.debian.org
> Since stretch all release architectures are using PIE by default,
> and all future release architectures (including riscv64) will also
> use PIE by default.
>
> Many packages in Debian are building with hardening=+all, and the
> effect regarding PIE is "enable PIE for this package on some obscure
> ports architectures that don't have it enabled by default" which is
> unlikely to be what the maintainer intended.
>
> There are also some pre-stretch "hardening=+pie" left
> in some packages.
Yeah, I've never been very satisfied with our pie handling. :/
> There are some problems with this:
>
> 1. PIE should either be default or not be used
>
> I suspect x32 might be able to default to PIE without problems
> (there might just not be enough interest left to change the default).
>
> On alpha the toolchain has already become quite brittle
> with frequent issues like (reproducible) linker segfaults,
> any variations that affects the toolchain are bad.
>
> It is for the port maintainers to decide whether or not PIE
> is considered stable on a port, and accordingly either make
> it default (which also avoids the other issues below) or not.
>
> It is clear that a non-PIE architecture would no longer be
> considered suitable as release architecture.
In general the way this is handled in dpkg, is that if the flags
supposedly work on that arch they are allowed, but if they are not
supported or are broken then they are masked.
> 2. It causes weird issues on undersupported architectures
>
> gluegen2 passes LDFLAGS to ld instead of gcc.
>
> Several packages have relocation errors only on affected
> architectures.
>
> ...
>
> Such issues could be debugged and fixed, but in practice
> trying to handle such issues that happen only with
> pie-{compile,link}.spec creates additional work that frustrates
> the few people keeping these non-release architectures alive.
Regardless of this report, I think this would still be worthwhile,
as otherwise you cannot for example disable them globally on arches
where it is a builtin in the compiler (as those will also need the
spec files.
> The lowest effort fix would be to patch debian/rules of affected
> packages to disable hardening=+pie on affected architectures,
> but that would still be spending time on working around a problem
> that shouldn't exist.
Yeah, that does not look like the right thing to be spending time on.
> 3. It breaks some cases of static linking
>
> Linking a package with hardening=+all against a static library
> from a package not using hardening=+all cannot work on the
> affected architectures.
>
> Static linking is relatively rare, but I remember requesting binNMUs
> for static linking cases to fix FTBFS on release architectures when
> the default changed before stretch.
Hmm, ah or even packages not respecting DEB_BUILD_OPTIONS, right.
> Please drop pie-{compile,link}.spec, on the architectures
> where it has any effect it is doing more harm than good.
For example hppa has pie masked for build flags. If the porters for
alpha and/or ia64 consider that they should also get pie masked for
those arches, I'm fine doing the changes. Although that means on those
ports it will not be possible to enable pie at all, even if asked for
explicitly, as in «hardening=+pie».
Thanks,
Guillem
