netdev - Re: [PATCH] net-timestamp: Fix a documentation typo

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CA+FuTSenSVXP-=hH+erpoE7yz1HbF8n9PeD_Xof-W=3GaQ6OFA@mail.gmail.com>
Date:	Mon, 24 Nov 2014 17:11:28 -0500
From:	Willem de Bruijn <willemb@...gle.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	Network Development <netdev@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH] net-timestamp: Fix a documentation typo

On Mon, Nov 24, 2014 at 3:02 PM, Andy Lutomirski <luto@...capital.net> wrote:
> SOF_TIMESTAMPING_OPT_ID puts the id in ee_data, not ee_info.
>
> Cc: Willem de Bruijn <willemb@...gle.com>
> Signed-off-by: Andy Lutomirski <luto@...capital.net>

Acked-by: Willem de Bruijn <willemb@...gle.com>

> ---

Thanks for sending a fix.

> While I'm here, the docs say:
>
>     In practice, it [ee_data] is a monotonically increasing u32 (that wraps).
>
> Is user code supposed to rely on this and, further, on the fact that the
> counter starts at zero?  If not, how else is user code supposed to match
> outgoing data to timestamps?

That is correct. The per-socket counter is reset when
SOF_TIMESTAMPING_OPT_ID is set. On datagram sockets, it returns the
packet number since the reset. On stream sockets, it returns the byte
offset since the reset.

> Also, is it intentional that the payload data associated with the tx
> timestamp is (I think) the full outgoing packet including lower-layer
> headers?

Absolutely not. I'll look into that right away. It doesn't on ACK, and
should certainly not expose this info in the other cases, either.

> And, finally, would it be possible to attach IP_PKTINFO to the looped
> timestamp?  That way I could finally update my fancy ping program to
> track which outgoing interface was used for a request.

If socket option IP_PKTINFO is set, you want to receive in_pktinfo for
any packet that happens to be queued onto the error queue? Both
SKB_EXT_ERR(skb) and PKTINFO_SKB_CB(skb) use the control block to
store data that is later encoded in a cmsg, so there may not be enough
room to hold both. I'll take a look.
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html