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Date:   Thu, 6 Aug 2020 11:46:57 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     Rouven Czerwinski <r.czerwinski@pengutronix.de>
Cc:     Boris Pismenny <borisp@mellanox.com>,
        Aviad Yehezkel <aviadye@mellanox.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Daniel Borkmann <daniel@iogearbox.net>,
        "David S. Miller" <davem@davemloft.net>, kernel@pengutronix.de,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 net-next] net/tls: allow MSG_CMSG_COMPAT in sendmsg
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On Thu,  6 Aug 2020 08:49:06 +0200 Rouven Czerwinski wrote:
> Trying to use ktls on a system with 32-bit userspace and 64-bit kernel
> results in a EOPNOTSUPP message during sendmsg:
>=20
>   setsockopt(3, SOL_TLS, TLS_TX, =E2=80=A6, 40) =3D 0
>   sendmsg(3, =E2=80=A6, msg_flags=3D0}, 0) =3D -1 EOPNOTSUPP (Operation n=
ot supported)
>=20
> The tls_sw implementation does strict flag checking and does not allow
> the MSG_CMSG_COMPAT flag, which is set if the message comes in through
> the compat syscall.
>=20
> This patch adds MSG_CMSG_COMPAT to the flag check to allow the usage of
> the TLS SW implementation on systems using the compat syscall path.
>=20
> Note that the same check is present in the sendmsg path for the TLS
> device implementation, however the flag hasn't been added there for lack
> of testing hardware.
>=20
> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>

I don't know much about the compat stuff, I trust our cmsg handling is
fine?

Just to be sure - did you run tools/testing/selftests/net/tls ?