This patch series add support to write cgroup interfaces from BPF. It is useful to freeze a cgroup hierarchy on suspicious activity for a more thorough analysis before killing it. Planned users of this feature are: systemd and BPF tools where the cgroup hierarchy could be a system service, user session, k8s pod or a container. The writing happens via kernfs nodes and the cgroup must be on the default hierarchy. It implements the requests and feedback from v1 [1] where now we use a unified path for cgroup user space and BPF writing. So I want to validate that this is the right approach first. Todo: * Limit size of data to be written. * Further tests. * Add cgroup kill support. # RFC v1 -> v2 * Implemented Alexei and Tejun requests [1]. * Unified path where user space or BPF writing end up taking directly a kernfs_node with an example on the "cgroup.freeze" interface. [1] https://lore.kernel.org/bpf/20240327225334.58474-1-tixxdz@xxxxxxxxx/ Djalal Harouni (3): kernfs: cgroup: support writing cgroup interfaces from a kernfs node bpf: cgroup: Add BPF Kfunc to write cgroup interfaces selftests/bpf: add selftest for bpf_cgroup_write_interface include/linux/cgroup.h | 3 ++ kernel/bpf/helpers.c | 45 +++++ kernel/cgroup/cgroup.c | 102 +++++++ tools/testing/selftests/bpf/prog_tests/task_freeze_cgroup.c | 172 ++++++++++++ tools/testing/selftests/bpf/progs/test_task_freeze_cgroup.c | 155 ++++++++++ 5 files changed, 471 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/task_freeze_cgroup.c create mode 100644 tools/testing/selftests/bpf/progs/test_task_freeze_cgroup.c -- 2.34.1
