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.
Currently, this maintains an entirely separate mechanism to attach hooks because the hooks are behind managed static_keys to prevent overhead. This is also done so sealable memory support could be added at a later point. The callbacks currently include a percpu_counter, but that could sit outside of the struct itself. This may also have a benefit that these counters, could have __cacheline_aligned_in_smp. Although, in my testing I was unable to find much performance delta with percpu_counters that were not aligned. 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 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: Add safe, dynamic (runtime-loadable) hook support LSM: Add statistics about the invocation of dynamic hooks LSM: Add an example sample dynamic LSM include/linux/lsm_hooks.h | 254 ++++++++++++++++++++++++++++++++++++++++ samples/Kconfig | 6 + samples/Makefile | 2 +- samples/lsm/Makefile | 4 + samples/lsm/lsm_example.c | 39 +++++++ security/Kconfig | 16 +++ security/Makefile | 2 + security/dynamic.c | 291 ++++++++++++++++++++++++++++++++++++++++++++++ security/dynamic.h | 32 +++++ security/dynamicfs.c | 109 +++++++++++++++++ security/inode.c | 2 + security/security.c | 114 ++++++++++++++++-- 12 files changed, 863 insertions(+), 8 deletions(-) create mode 100644 samples/lsm/Makefile create mode 100644 samples/lsm/lsm_example.c create mode 100644 security/dynamic.c create mode 100644 security/dynamic.h create mode 100644 security/dynamicfs.c -- 2.14.1
