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Tue, 13 Oct 2026 04:05:37 -0700 (PDT) Date: Tue, 13 Oct 2026 07:05:34 -0400 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Willem de Bruijn , Jason Wang , Eugenio =?iso-8859-1?Q?P=E9rez?= , Xuan Zhuo , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, virtualization@lists.linux.dev, Max Krasnyansky , Paulos Yibelo , Chris Arges Subject: Re: [PATCH net-next 0/4] more virtio-net csum hardening Message-ID: <20261013070259-mutt-send-email-mst@kernel.org> References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Oct 13, 2026 at 06:58:28AM -0400, Michael S. Tsirkin wrote: > Allowing untrusted hardware to specify csum start/offset for > CHECKSUM_PARTIAL was not a good idea, because, if it edits the packet > outside the actual checksum, and depending on the setup, the networking > stack could be looking at the packet both before and after the edit, and > seeing different results. > > Previously, commit 6785011f8b16 ("ipv4: validate checksum_start before > completing checksum") validated all known instances where this > causes the most grief, but the real fix is to make sure > that either only actual checksum fields are ever edited, > or the checksum is completed before the net stack looks at it, > so it is always consistent. > > This basically does this: checksum at ingress, except in a narrow list > of specified known good cases. > > Fixes: f43798c27684 ("tun: Allow GSO using virtio_net_hdr") I forgot. Reported-by: Paulos Yibelo Reported-by: Chris Arges > Michael S. Tsirkin (4): > net: add ip4_parse() > net: use ip4_parse() in receive validation > net: resolve uncommon partial checksums at ingress > net: account for ingress-resolved virtio net hdr state > > drivers/net/tap.c | 4 +- > drivers/net/tun.c | 44 +++++++- > drivers/net/virtio_net.c | 2 +- > include/linux/ip.h | 24 +++++ > include/linux/virtio_net.h | 161 ++++++++++++++++++++++++---- > net/bridge/br_netfilter_hooks.c | 15 +-- > net/ipv4/ip_input.c | 13 +-- > net/ipv4/netfilter/nf_reject_ipv4.c | 13 +-- > net/packet/af_packet.c | 4 +- > 9 files changed, 228 insertions(+), 52 deletions(-) > > -- > MST >