Re: [PATCH] cgroup: Fix crash with CLONE_INTO_CGROUP and v1 cgroups

[Tejun Heo]

Hello,

On Mon, Oct 10, 2022 at 11:50:50AM -0700, Yosry Ahmed wrote:
> The purpose of f3a2aebdd6 was to make cgroup_get_from_fd() support
> cgroup1, which IIUC makes sense. It was unrelated to IDs.

Ah, right you are. For some reason, I thought this was ID based.

> There are currently two users of
> cgroup_get_from_file()/cgroup_get_from_fd() AFAICT, one of which is
> the fork code fixed by this commit, the second is BPF cgroup prog
> attachment. I can send another patch to add explicit filtering in the
> BPF attachment code as well.
> 
> Alternatively, we can have separate functions that do the filtering if
> needed. For example:
> cgroup_get_from_fd() / cgroup_get_from_file() -> support both v1 and v2
> cgroup_get_dfl_from_fd() / cgroup_get_dfl_from_file() -> support only v2
> 
> We can then use the versions with filtering for all the current users
> except cgroup_iter (that needs to support both v1 and v2). WDYT?

Yes, but please leave the existing ones v2 only and add new ones which
allows cgroup1 too.

Thanks.

-- 
tejun