# Re: \[PATCH bpf-next v2 1/2\] bpf: Allow bpf\_get\_netns\_cookie in BPF\_PROG\_TYPE\_CGROUP\_SOCKOPT

- From: \<hidden\>
- Date: 2021-08-13 21:23:09 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/08/7776515
- Thread: https://ratatoskr.run/netdev/2021/08/7776478/t.md

```text
On 08/13, Martin KaFai Lau wrote:
> On Thu, Aug 12, 2021 at 08:30:10AM -0700, Stanislav Fomichev wrote:
> > This is similar to existing BPF_PROG_TYPE_CGROUP_SOCK
> > and BPF_PROG_TYPE_CGROUP_SOCK_ADDR.
> >
> > Signed-off-by: Stanislav Fomichev <redacted>
> > ---
> >  kernel/bpf/cgroup.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
> > index b567ca46555c..ca5af8852260 100644
> > --- a/kernel/bpf/cgroup.c
> > +++ b/kernel/bpf/cgroup.c
> > @@ -1846,11 +1846,30 @@ const struct bpf_verifier_ops cg_sysctl_verifier_ops = {
> >  const struct bpf_prog_ops cg_sysctl_prog_ops = {
> >  };
> >
> > +#ifdef CONFIG_NET
> > +BPF_CALL_1(bpf_get_netns_cookie_sockopt, struct bpf_sockopt_kern *, ctx)
> > +{
> > +	struct sock *sk = ctx ? ctx->sk : NULL;
> > +	const struct net *net = sk ? sock_net(sk) : &init_net;
> A nit.

> ctx->sk can not be NULL here, so it only depends on ctx is NULL or not.

> If I read it correctly, would it be less convoluted to directly test ctx
> and use ctx->sk here, like:

> 	const struct net *net = ctx ? sock_net(ctx->sk) : &init_net;

> and the previous "struct sock *sk = ctx ? ctx->sk : NULL;" statement
> can also be removed.
Agreed, makes sense. Let me also add bpf_get_netns_cookie to some
existing BPF prog to make sure it's executed. That ctx.c isn't
really running the prog..
```