net: inet_diag: export IPV6_V6ONLY sockopt

On Fri, 2015-06-19 at 14:15 +0200, Phil Sutter wrote:
> For AF_INET6 sockets, the value of struct ipv6_pinfo.ipv6only is
> exported to userspace. It indicates whether an unbound socket listens on
> IPv4 as well as IPv6.

What is an 'unbound socket' ??? This makes no sense to me here.

>  Since the socket is natively IPv6, it is not
> listed by e.g. 'netstat -l -4'.

netstat does not use this interface. iproute2/ss does.

> 
> Signed-off-by: Phil Sutter <phil@nwl.cc>
> ---
> This patch is accompanied by an appropriate one for iproute2 to enable
> the additional information in 'ss -e'.
> ---
>  include/uapi/linux/inet_diag.h | 3 ++-
>  net/ipv4/inet_diag.c           | 4 ++++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
> index c7093c7..9ca4834 100644
> --- a/include/uapi/linux/inet_diag.h
> +++ b/include/uapi/linux/inet_diag.h
> @@ -111,9 +111,10 @@ enum {
>  	INET_DIAG_SKMEMINFO,
>  	INET_DIAG_SHUTDOWN,
>  	INET_DIAG_DCTCPINFO,
> +	INET_DIAG_SKV6ONLY,
>  };
>  
> -#define INET_DIAG_MAX INET_DIAG_DCTCPINFO
> +#define INET_DIAG_MAX INET_DIAG_SKV6ONLY
>  
>  /* INET_DIAG_MEM */
>  
> diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
> index 4d32262..4bf6d03 100644
> --- a/net/ipv4/inet_diag.c
> +++ b/net/ipv4/inet_diag.c
> @@ -151,6 +151,10 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
>  			if (nla_put_u8(skb, INET_DIAG_TCLASS,
>  				       inet6_sk(sk)->tclass) < 0)
>  				goto errout;
> +
> +		if (nla_put_u8(skb, INET_DIAG_SKV6ONLY,
> +				inet6_sk(sk)->ipv6only) < 0)
> +			goto errout;
>  	}
>  #endif
>  

1) This certainly should not compile on current linux trees.
   Always submit such patches on net-next.

2) It is not clear why we would add this attribute if it is 0.
    This looks a waste of data.

So I would rather use :



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On Fri, Jun 19, 2015 at 06:52:00AM -0700, Eric Dumazet wrote:
> On Fri, 2015-06-19 at 14:15 +0200, Phil Sutter wrote:
> > For AF_INET6 sockets, the value of struct ipv6_pinfo.ipv6only is
> > exported to userspace. It indicates whether an unbound socket listens on
> > IPv4 as well as IPv6.
> 
> What is an 'unbound socket' ??? This makes no sense to me here.

Indeed, this is just plain wrong. Actually meant "not bound to a
specific IPv6 address".

> >  Since the socket is natively IPv6, it is not
> > listed by e.g. 'netstat -l -4'.
> 
> netstat does not use this interface. iproute2/ss does.

Just used this as a simple example illustrating the problem, but doing
the same with 'ss' is truly a better choice.

[...]

> 1) This certainly should not compile on current linux trees.
>    Always submit such patches on net-next.

It cleanly applies to net.git.

> 2) It is not clear why we would add this attribute if it is 0.
>     This looks a waste of data.
> 
> So I would rather use :

ACK. Thanks for reviewing, v2 follows after I've tested it.

Cheers, Phil
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On Sun, 2015-06-21 at 03:47 +0200, Phil Sutter wrote:

> 
> > 1) This certainly should not compile on current linux trees.
> >    Always submit such patches on net-next.
> 
> It cleanly applies to net.git.

A very old one, because there is no ipv6only field anymore after
commit 9fe516ba3fb29b6f6a752ffd93342fdee500ec01 ("inet: move ipv6only in
sock_common") back in linux 3.17 

inet6_sk(sk)->ipv6only can not possibly compile today, I am pretty sure
of this.

# git grep -n ipv6only -- include
include/linux/ipv6.h:285:#define __ipv6_only_sock(sk)   (sk->sk_ipv6only)
include/linux/ipv6.h:297:static inline int inet_v6_ipv6only(const struct sock *sk)
include/linux/ipv6.h:299:       /* ipv6only field is at same position for timewait and other sockets */
include/linux/ipv6.h:324:#define tcp_twsk_ipv6only(__sk)                0
include/linux/ipv6.h:325:#define inet_v6_ipv6only(__sk)         0
include/net/inet_timewait_sock.h:58:#define tw_ipv6only         __tw_common.skc_ipv6only
include/net/sock.h:186: unsigned char           skc_ipv6only:1;
include/net/sock.h:325:#define sk_ipv6only              __sk_common.skc_ipv6only

So always make sure your tree is not one year old before submitting a patch.

Thanks.


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