A record may have more than just FieldDecls in it. If so, then we're
likely to drop them if we only randomize the FieldDecls.
We need to be careful about anonymous structs/unions. Their fields are
made available in the RecordDecl as IndirectFieldDecls, which are listed
after the anonymous struct/union. The ordering doesn't appear to be
super important, however we place them unrandomized at the end of the
RecordDecl just in case. There's also the possiblity of
StaticAssertDecls. We also want those at the end.
All other non-FieldDecls we place at the top, just in case we get
something like:
struct foo {
enum e { BORK };
enum e a;
};
Link: https://github.com/KSPP/linux/issues/185
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D123958
This uses "llvm::shuffle" to stop differences in shuffle ordering on
different platforms.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D124199
The Randstruct feature is a compile-time hardening technique that
randomizes the field layout for designated structures of a code base.
Admittedly, this is mostly useful for closed-source releases of code,
since the randomization seed would need to be available for public and
open source applications.
Why implement it? This patch set enhances Clang’s feature parity with
that of GCC which already has the Randstruct feature. It's used by the
Linux kernel in certain structures to help thwart attacks that depend on
structure layouts in memory.
This patch set is a from-scratch reimplementation of the Randstruct
feature that was originally ported to GCC. The patches for the GCC
implementation can be found here:
https://www.openwall.com/lists/kernel-hardening/2017/04/06/14
Link: https://lists.llvm.org/pipermail/cfe-dev/2019-March/061607.html
Co-authored-by: Cole Nixon <nixontcole@gmail.com>
Co-authored-by: Connor Kuehl <cipkuehl@gmail.com>
Co-authored-by: James Foster <jafosterja@gmail.com>
Co-authored-by: Jeff Takahashi <jeffrey.takahashi@gmail.com>
Co-authored-by: Jordan Cantrell <jordan.cantrell@mail.com>
Co-authored-by: Nikk Forbus <nicholas.forbus@gmail.com>
Co-authored-by: Tim Pugh <nwtpugh@gmail.com>
Co-authored-by: Bill Wendling <isanbard@gmail.com>
Signed-off-by: Bill Wendling <isanbard@gmail.com>
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D121556
This reverts commit 3f0587d0c6.
Not all tests pass after a few rounds of fixes.
I spot one failure that std::shuffle (potentially different results with
different STL implementations) was misused and replaced it with llvm::shuffle,
but there appears to be another failure in a Windows build.
The latest failure is reported on https://reviews.llvm.org/D121556#3440383
The Randstruct feature is a compile-time hardening technique that
randomizes the field layout for designated structures of a code base.
Admittedly, this is mostly useful for closed-source releases of code,
since the randomization seed would need to be available for public and
open source applications.
Why implement it? This patch set enhances Clang’s feature parity with
that of GCC which already has the Randstruct feature. It's used by the
Linux kernel in certain structures to help thwart attacks that depend on
structure layouts in memory.
This patch set is a from-scratch reimplementation of the Randstruct
feature that was originally ported to GCC. The patches for the GCC
implementation can be found here:
https://www.openwall.com/lists/kernel-hardening/2017/04/06/14
Link: https://lists.llvm.org/pipermail/cfe-dev/2019-March/061607.html
Co-authored-by: Cole Nixon <nixontcole@gmail.com>
Co-authored-by: Connor Kuehl <cipkuehl@gmail.com>
Co-authored-by: James Foster <jafosterja@gmail.com>
Co-authored-by: Jeff Takahashi <jeffrey.takahashi@gmail.com>
Co-authored-by: Jordan Cantrell <jordan.cantrell@mail.com>
Co-authored-by: Nikk Forbus <nicholas.forbus@gmail.com>
Co-authored-by: Tim Pugh <nwtpugh@gmail.com>
Co-authored-by: Bill Wendling <isanbard@gmail.com>
Signed-off-by: Bill Wendling <isanbard@gmail.com>
Reviewed By: aaron.ballman
Differential Revision: https://reviews.llvm.org/D121556
Bill Wendling