linux-kernel - [RFC PATCH v3 0/3] Safe, dynamically loadable LSM hooks

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Date:   Tue, 20 Feb 2018 02:13:58 +0000
From:   Sargun Dhillon <sargun@...gun.me>
To:     linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     james.l.morris@...cle.com, penguin-kernel@...ove.sakura.ne.jp,
        keescook@...omium.org, igor.stoppa@...wei.com,
        casey@...aufler-ca.com
Subject: [RFC PATCH v3 0/3] Safe, dynamically loadable LSM hooks

This patchset introduces safe dynamic LSM support. These are currently
not unloadable, until we figure out a use case that needs that. Adding
an unload hook is trivial given the way the patch is written.

This exposes a second mechanism of loading hooks which are in modules,
because they are behind static keys, and kept in a set of hooks which
is not marked as read only.

The point of this security feature is to resolve "unknown unknowns"
as well. Although, livepatch is excellent, sometimes, a surgical
LSM is simpler.

It includes an example LSM that prevents specific time travel.

Changes since v2:
  * inode get/set security is readded
  * xfrm singleton hook readded
  * Security hooks are turned into an array
  * Security hooks and dynamic hooks enum is collapsed

Changes since v1:
  * It no longer allows unloading of modules
  * prctl is fixed
  * inode get/set security is removed
  * xfrm singleton hook removed


Sargun Dhillon (3):
  security: Refactor LSM hooks into an array
  security: Expose a mechanism to load lsm hooks dynamically at runtime
  security: Add an example sample dynamic LSM

 include/linux/lsm_hooks.h | 454 ++++++++++++++++++++++++----------------------
 samples/Kconfig           |   6 +
 samples/Makefile          |   2 +-
 samples/lsm/Makefile      |   4 +
 samples/lsm/lsm_example.c |  33 ++++
 security/Kconfig          |   9 +
 security/inode.c          |  13 +-
 security/security.c       | 250 +++++++++++++++++++++++--
 8 files changed, 531 insertions(+), 240 deletions(-)
 create mode 100644 samples/lsm/Makefile
 create mode 100644 samples/lsm/lsm_example.c

-- 
2.14.1