[0/3] ELF interpretor info: align and add random padding

Message

Yann Droneaud June 13, 2019, 11:26 a.m. UTC

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(-)