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Donenfeld" , netdev@vger.kernel.org Cc: "Jason A. Donenfeld" , Adhipati Blambangan , David Ahern Subject: Re: [PATCH net v3] net: xdp: account for layer 3 packets in generic skb handler In-Reply-To: <20200427204208.2501-1-Jason@zx2c4.com> References: <20200427204208.2501-1-Jason@zx2c4.com> X-Clacks-Overhead: GNU Terry Pratchett Date: Mon, 27 Apr 2020 23:00:31 +0200 Message-ID: <87a72wy780.fsf@toke.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org "Jason A. Donenfeld" writes: > A user reported that packets from wireguard were possibly ignored by XDP > [1]. Apparently, the generic skb xdp handler path seems to assume that > packets will always have an ethernet header, which really isn't always > the case for layer 3 packets, which are produced by multiple drivers. > This patch fixes the oversight. If the mac_len is 0, then we assume > that it's a layer 3 packet, and in that case prepend a pseudo ethhdr to > the packet whose h_proto is copied from skb->protocol, which will have > the appropriate v4 or v6 ethertype. This allows us to keep XDP programs' > assumption correct about packets always having that ethernet header, so > that existing code doesn't break, while still allowing layer 3 devices > to use the generic XDP handler. > > [1] https://lore.kernel.org/wireguard/M5WzVK5--3-2@tuta.io/ > > Reported-by: Adhipati Blambangan > Cc: David Ahern > Cc: Toke H=C3=B8iland-J=C3=B8rgensen > Signed-off-by: Jason A. Donenfeld Acked-by: Toke H=C3=B8iland-J=C3=B8rgensen