Re: [PATCH bpf-next v3 1/4] bpf: sock ops: add netns ino and dev in bpf context

[Alban Crequy <alban@xxxxxxxxxx>]

On Fri, Apr 26, 2019 at 11:03 PM Jakub Kicinski
<jakub.kicinski@xxxxxxxxxxxxx> wrote:
>
> On Fri, 26 Apr 2019 17:48:45 +0200, Alban Crequy wrote:
> > In the unlikely case where network namespaces are not compiled in
> > (CONFIG_NET_NS=n), the verifier will not allow access to ->netns_*.
>
> Naive question - why return an error?  init_net should always be there,
> no?

True for netns_dev. However, without CONFIG_NET_NS, we cannot access netns_ino:

(struct sock_common).possible_net_t.(struct net *):

typedef struct {
#ifdef CONFIG_NET_NS
        struct net *net;
#endif
} possible_net_t;

And I don't think it would make much sense to allow access to
netns_dev but not netns_ino.