[PATCH 0/2] aarch64: Enable pointer auth in PLT

[Florian Weimer]

* Szabolcs Nagy:

> Pointer authentication is an armv8.3-a extension and it can be used
> to harden PLTGOT entries when that is not read-only protected.
>
> binutils bfd linker now supports creating binaries with -z pac-plt
> and then PLT entries authenticate the pointers loaded from PLTGOT.
>
> To support such binaries the glibc dynamic linker has to "sign" the
> pointers in the PLTGOT. On cpus without pointer authentication support,
> both the sign and authentication operations are nops, so such binaries
> may appear to work now, but on a new cpu they will crash without glibc
> support.

I think you need to enable this feature in a different way, similar to
the non-executable stack.  Otherwise, people will have to decide whether
they want to build portable binaries or binaries with security
hardening, which is not desirable.

Thanks,
Florian