Re: [PATCH v2 net] sock: ignore SCM_RIGHTS and SCM_CREDENTIALS in __sock_cmsg_send

From: Soheil Hassas Yeganeh <redacted>
Date: Mon, 11 Jul 2016 16:51:26 -0400

From: Soheil Hassas Yeganeh <redacted>

Sergei Trofimovich reported that pulse audio sends SCM_CREDENTIALS
as a control message to TCP. Since __sock_cmsg_send does not
support SCM_RIGHTS and SCM_CREDENTIALS, it returns an error and
hence breaks pulse audio over TCP.

SCM_RIGHTS and SCM_CREDENTIALS are sent on the SOL_SOCKET layer
but they semantically belong to SOL_UNIX. Since all
cmsg-processing functions including sock_cmsg_send ignore control
messages of other layers, it is best to ignore SCM_RIGHTS
and SCM_CREDENTIALS for consistency (and also for fixing pulse
audio over TCP).

Fixes: c14ac9451c34 ("sock: enable timestamping using control messages")
Signed-off-by: Soheil Hassas Yeganeh <redacted>
Reported-by: Sergei Trofimovich <redacted>
Tested-by: Sergei Trofimovich <redacted>

Applied and queued up for -stable, thanks.