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SubjectRe: [PATCH v3] net: ip, diag -- Add diag interface for raw sockets
On Mon, Sep 26, 2016 at 07:54:37PM -0600, David Ahern wrote:
> On 9/26/16 4:38 PM, Cyrill Gorcunov wrote:
> > Something like
> >
> > Index: linux-ml.git/include/uapi/linux/inet_diag.h
> > ===================================================================
> > --- linux-ml.git.orig/include/uapi/linux/inet_diag.h 2016-09-11 20:56:18.191584145 +0300
> > +++ linux-ml.git/include/uapi/linux/inet_diag.h 2016-09-27 01:34:08.413172394 +0300
> > @@ -38,7 +38,7 @@ struct inet_diag_req_v2 {
> > __u8 sdiag_family;
> > __u8 sdiag_protocol;
> > __u8 idiag_ext;
> > - __u8 pad;
> > + __u8 sdiag_raw_protocol; /* SOCK_RAW only, @pad for others */
>
> Seems like that should be a union to keep the API.

Is anonymous union (which is not part of c99) are acceptable in uapi?
Initially I declared it as union but then scratched my head if this
would be acceptable.

>
>
> > __u32 idiag_states;
> > struct inet_diag_sockid id;
> > };
> >
> > and in raw-diag module we will use @sdiag_raw_protocol instead of
> > @sdiag_protocol field. Didn't cover ss tool source code yet but
> > I think the idea is seen. Still not sure if start using @pad here
> > is a good idea (it's uapi), maybe beter to ask nla attribute which would
> > come right afterh the inet_diag_req_v2 message?
> >
>
> seems reasonable to me since 2 protocols need to be sent to the kernel.
>
> Alternatively, sdiag_protocol could be the actual protocol and the pad union be a flag field
> with say bit 0 = INET_DIAG_FLAG_SOCK_RAW. Allows other overrides in the future if needed.

The @sdiag_protocol used for matching in diag module handler, so no, I think
we should not change this semantics. I would stick with @pad usage and if
anonymous unions are acceptable this would be just great.

Cyrill

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