linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
* [PATCH v3 0/7] mm, security, bpf: Fine-grained control over memory policy adjustments with lsm bpf
@ 2023-12-01  9:46 Yafang Shao
  2023-12-01  9:46 ` [PATCH v3 1/7] mm, doc: Add doc for MPOL_F_NUMA_BALANCING Yafang Shao
                   ` (6 more replies)
  0 siblings, 7 replies; 10+ messages in thread
From: Yafang Shao @ 2023-12-01  9:46 UTC (permalink / raw)
  To: akpm, paul, jmorris, serge, omosnace, mhocko, ying.huang
  Cc: linux-mm, linux-security-module, bpf, ligang.bdlg, Yafang Shao

Background
==========

In our containerized environment, we've identified unexpected OOM events
where the OOM-killer terminates tasks despite having ample free memory.
This anomaly is traced back to tasks within a container using mbind(2) to
bind memory to a specific NUMA node. When the allocated memory on this node
is exhausted, the OOM-killer, prioritizing tasks based on oom_score,
indiscriminately kills tasks. 

The Challenge 
=============
In a containerized environment, independent memory binding by a user can
lead to unexpected system issues or disrupt tasks being run by other users
on the same server. If a user genuinely requires memory binding, we will
allocate dedicated servers to them by leveraging kubelet deployment.

Currently, users possess the ability to autonomously bind their memory to
specific nodes without explicit agreement or authorization from our end.
It's imperative that we establish a method to prevent this behavior.

Proposed Solution
=================

- Capability
  Currently, any task can perform MPOL_BIND without specific capabilities.
  Enforcing CAP_SYS_RESOURCE or CAP_SYS_NICE could be an option, but this
  may have unintended consequences. Capabilities, being broad, might grant
  unnecessary privileges. We should explore alternatives to prevent
  unexpected side effects.

- LSM 
  Introduce LSM hooks for syscalls such as mbind(2) and set_mempolicy(2)
  to disable MPOL_BIND. This approach is more flexibility and allows for
  fine-grained control without unintended consequences. A sample LSM BPF
  program is included, demonstrating practical implementation in a
  production environment.

- seccomp
  seccomp is relatively heavyweight, making it less suitable for
  enabling in our production environment:
  - Both kubelet and containers need adaptation to support it.
  - Dynamically altering security policies for individual containers
    without interrupting their operations isn't straightforward.

Future Considerations
=====================

In addition, there's room for enhancement in the OOM-killer for cases
involving CONSTRAINT_MEMORY_POLICY. It would be more beneficial to
prioritize selecting a victim that has allocated memory on the same NUMA
node. My exploration on the lore led me to a proposal[0] related to this
matter, although consensus seems elusive at this point. Nevertheless,
delving into this specific topic is beyond the scope of the current
patchset.

[0]. https://lore.kernel.org/lkml/20220512044634.63586-1-ligang.bdlg@bytedance.com/

Changes:
- RCC v2 -> v3:
  - Add MPOL_F_NUMA_BALANCING man-page (Ying)
  - Fix bpf selftests error reported by bot+bpf-ci
- RFC v1 -> RFC v2: https://lwn.net/Articles/952339/
  - Refine the commit log to avoid misleading
  - Use one common lsm hook instead and add comment for it
  - Add selinux implementation
  - Other improments in mempolicy
- RFC v1: https://lwn.net/Articles/951188/

Yafang Shao (6):
  mm, doc: Add doc for MPOL_F_NUMA_BALANCING
  mm: mempolicy: Revise comment regarding mempolicy mode flags
  mm, security: Fix missed security_task_movememory()
  mm, security: Add lsm hook for memory policy adjustment
  security: selinux: Implement set_mempolicy hook
  selftests/bpf: Add selftests for set_mempolicy with a lsm prog

 .../admin-guide/mm/numa_memory_policy.rst     | 27 +++++++
 include/linux/lsm_hook_defs.h                 |  3 +
 include/linux/security.h                      |  9 +++
 include/uapi/linux/mempolicy.h                |  2 +-
 mm/mempolicy.c                                | 22 ++++-
 security/security.c                           | 13 +++
 security/selinux/hooks.c                      |  8 ++
 security/selinux/include/classmap.h           |  2 +-
 .../selftests/bpf/prog_tests/set_mempolicy.c  | 81 +++++++++++++++++++
 .../selftests/bpf/progs/test_set_mempolicy.c  | 28 +++++++
 10 files changed, 192 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/set_mempolicy.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_set_mempolicy.c

NOT kernel:

Yafang Shao (1):
NOT kernel/man2/mbind.2: Add mode flag MPOL_F_NUMA_BALANCING

-- 
2.30.1 (Apple Git-130)



^ permalink raw reply	[flat|nested] 10+ messages in thread
end of thread, other threads:[~2023-12-03  2:58 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-12-01  9:46 [PATCH v3 0/7] mm, security, bpf: Fine-grained control over memory policy adjustments with lsm bpf Yafang Shao
2023-12-01  9:46 ` [PATCH v3 1/7] mm, doc: Add doc for MPOL_F_NUMA_BALANCING Yafang Shao
2023-12-01  9:46 ` [PATCH v3 2/7] mm: mempolicy: Revise comment regarding mempolicy mode flags Yafang Shao
2023-12-01  9:46 ` [PATCH v3 3/7] mm, security: Fix missed security_task_movememory() Yafang Shao
2023-12-01 20:50   ` Serge E. Hallyn
2023-12-03  2:57     ` Yafang Shao
2023-12-01  9:46 ` [PATCH v3 4/7] mm, security: Add lsm hook for memory policy adjustment Yafang Shao
2023-12-01  9:46 ` [PATCH v3 5/7] security: selinux: Implement set_mempolicy hook Yafang Shao
2023-12-01  9:46 ` [PATCH v3 6/7] selftests/bpf: Add selftests for set_mempolicy with a lsm prog Yafang Shao
2023-12-01  9:46 ` [PATCH v3 7/7] NOT kernel/man2/mbind.2: Add mode flag MPOL_F_NUMA_BALANCING Yafang Shao

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox