Add security_SymlinkRestriction test

This adds tests for the symlink restrictions introduced by the Yama LSM
in the kernel.

BUG=chromium-os:22137
TEST=passes on x86-alex when Yama is enabled (using patch series from
 https://gerrit.chromium.org/gerrit/12409)

Change-Id: If157681a55340883ac82e194a457574aa3b528ea
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/12522
Reviewed-by: Jim Hebert <jimhebert@chromium.org>
2 files changed