netdev - Re: [PATCH net] ip: Fix SO_MARK in RST, ACK and ICMP packets

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Date:   Wed, 1 Jul 2020 17:26:15 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>, Martin Lau <kafai@...com>
Subject: Re: [PATCH net] ip: Fix SO_MARK in RST, ACK and ICMP packets

On Wed, Jul 1, 2020 at 4:00 PM Willem de Bruijn
<willemdebruijn.kernel@...il.com> wrote:
>
> From: Willem de Bruijn <willemb@...gle.com>
>
> When no full socket is available, skbs are sent over a per-netns
> control socket. Its sk_mark is temporarily adjusted to match that
> of the real (request or timewait) socket or to reflect an incoming
> skb, so that the outgoing skb inherits this in __ip_make_skb.
>
> Introduction of the socket cookie mark field broke this. Now the
> skb is set through the cookie and cork:
>
> <caller>                # init sockc.mark from sk_mark or cmsg
> ip_append_data
>   ip_setup_cork         # convert sockc.mark to cork mark
> ip_push_pending_frames
>   ip_finish_skb
>     __ip_make_skb       # set skb->mark to cork mark
>
> But I missed these special control sockets. Update all callers of
> __ip(6)_make_skb that were originally missed.
>
> For IPv6, the same two icmp(v6) paths are affected. The third
> case is not, as commit 92e55f412cff ("tcp: don't annotate
> mark on control socket from tcp_v6_send_response()") replaced
> the ctl_sk->sk_mark with passing the mark field directly as a
> function argument. That commit predates the commit that
> introduced the bug.
>
> Fixes: c6af0c227a22 ("ip: support SO_MARK cmsg")
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>
> Reported-by: Martin KaFai Lau <kafai@...com>

I spotted another missing case, in ping_v6_sendmsg. Will have to send a v2.