Received-SPF: pass (google.com: domain of linux-kernel+bounces-205457-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Precedence: bulk
MIME-Version: 1.0
References: <20240606192139.1872461-1-joshwash@google.com> <20240607060958.2789886-1-joshwash@google.com>
In-Reply-To: <20240607060958.2789886-1-joshwash@google.com>
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 7 Jun 2024 08:35:30 +0200
Message-ID: <CANn89iLy1qGXzrv_coRcaRDOrOMHKb-NG1xn06Sat0QTvrDwXA@mail.gmail.com>
Subject: Re: [PATCH net v2] gve: ignore nonrelevant GSO type bits when
 processing TSO headers
To: joshwash@google.com
Cc: netdev@vger.kernel.org, davem@davemloft.net, kuba@kernel.org, 
	stable@kernel.org, Praveen Kaligineedi <pkaligineedi@google.com>, 
	Harshitha Ramamurthy <hramamurthy@google.com>, Willem de Bruijn <willemb@google.com>, 
	Andrei Vagin <avagin@gmail.com>, Jeroen de Borst <jeroendb@google.com>, 
	Shailend Chand <shailend@google.com>, Paolo Abeni <pabeni@redhat.com>, 
	Rushil Gupta <rushilg@google.com>, Bailey Forrest <bcf@google.com>, 
	Catherine Sullivan <csully@google.com>, open list <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Fri, Jun 7, 2024 at 8:10=E2=80=AFAM <joshwash@google.com> wrote:
>
> From: Joshua Washington <joshwash@google.com>
>
> TSO currently fails when the skb's gso_type field has more than one bit
> set.
>
> TSO packets can be passed from userspace using PF_PACKET, TUNTAP and a
> few others, using virtio_net_hdr (e.g., PACKET_VNET_HDR). This includes
> virtualization, such as QEMU, a real use-case.
>
> The gso_type and gso_size fields as passed from userspace in
> virtio_net_hdr are not trusted blindly by the kernel. It adds gso_type
> |=3D SKB_GSO_DODGY to force the packet to enter the software GSO stack
> for verification.
>
> This issue might similarly come up when the CWR bit is set in the TCP
> header for congestion control, causing the SKB_GSO_TCP_ECN gso_type bit
> to be set.
>
> Fixes: a57e5de476be ("gve: DQO: Add TX path")
> Signed-off-by: Joshua Washington <joshwash@google.com>
> Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
> Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
> Reviewed-by: Willem de Bruijn <willemb@google.com>
> Suggested-by: Eric Dumazet <edumazet@google.com>
> Acked-by: Andrei Vagin <avagin@gmail.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>