linux-kernel - Re: [PATCH v2 02/23] bpf: initial support for attaching struct ops to cgroups

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aQKa5L345s-vBJR1@slm.duckdns.org>
Date: Wed, 29 Oct 2025 12:53:24 -1000
From: Tejun Heo <tj@...nel.org>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Roman Gushchin <roman.gushchin@...ux.dev>, Song Liu <song@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...nel.org>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	JP Kobryn <inwardvessel@...il.com>, linux-mm <linux-mm@...ck.org>,
	"open list:CONTROL GROUP (CGROUP)" <cgroups@...r.kernel.org>,
	bpf <bpf@...r.kernel.org>, Martin KaFai Lau <martin.lau@...nel.org>,
	Kumar Kartikeya Dwivedi <memxor@...il.com>
Subject: Re: [PATCH v2 02/23] bpf: initial support for attaching struct ops
 to cgroups

Hello,

On Wed, Oct 29, 2025 at 03:43:39PM -0700, Alexei Starovoitov wrote:
...
> I think the general bpf philosophy that load and attach are two
> separate steps. For struct-ops it's almost there, but not quite.
> struct-ops shouldn't be an exception.
> The bpf infra should be able to load a set of progs (aka struct-ops)
> and attach it with a link to different entities. Like cgroups.
> I think sched-ext should do that too. Even if there is no use case
> today for the same sched-ext in two different cgroups.

I'm not sure it's just that there's no use case.

- How would recursion work with private stacks? Aren't those attached to
  each BPF program?

- Wouldn't that also complicate attributing kfunc calls to the handle
  instance? If there is one struct_ops per cgroup, the oom kill kfunc can
  look that up and then verify that the struct_ops has authority over the
  target process. Multiple attachments can work too but that'd require
  iterating all attachments, right?

Thanks.

-- 
tejun