linux-kernel - [PATCH 0/3] ELF interpretor info: align and add random padding

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Date:   Thu, 13 Jun 2019 13:26:03 +0200
From:   Yann Droneaud <ydroneaud@...eya.com>
To:     linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Yann Droneaud <ydroneaud@...eya.com>
Subject: [PATCH 0/3] ELF interpretor info: align and add random padding

Hi,

The following patches are mostly focused on ensuring AT_RANDOM array is
aligned on 16bytes boundary, and while being located at a pseudo-random
offset on stack (at most 256 bytes).

This patchset also insert a random sized (at most 15 bytes) padding between
AT_RANDOM and AT_PLATFORM and/or AT_BASE_PLATFORM.

It also insert a random sized padding (at most 256 bytes) between those
data and the arrays passed to userspace (argv[] + environ[] + auxv[])
as defined by ABI.

Adding random padding around AT_RANDOM, AT_PLATFORM, AT_BASE_PLATEFORM
should be viewed as an exercise of cargo-cult security as I'm not aware
of any attack that can be prevented with this mechanism in place.

Regards.

Yann Droneaud (3):
  binfmt/elf: use functions for stack manipulation
  binfmt/elf: align AT_RANDOM array
  binfmt/elf: randomize padding between ELF interp info

 fs/binfmt_elf.c | 110 +++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 86 insertions(+), 24 deletions(-)

-- 
2.21.0