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([2a0d:3341:cc59:6510::f39]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442cd3aeb26sm201239565e9.29.2025.05.13.00.45.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 13 May 2025 00:45:14 -0700 (PDT) Message-ID: <3a173ede-e2db-463e-a135-7dc9c7976cd7@redhat.com> Date: Tue, 13 May 2025 09:45:13 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 04/10] ovpn: don't drop skb's dst when xmitting packet To: Antonio Quartulli , netdev@vger.kernel.org Cc: Eric Dumazet , Jakub Kicinski , Sabrina Dubroca , Gert Doering References: <20250509142630.6947-1-antonio@openvpn.net> <20250509142630.6947-5-antonio@openvpn.net> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250509142630.6947-5-antonio@openvpn.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/9/25 4:26 PM, Antonio Quartulli wrote: > When routing a packet to a LAN behind a peer, ovpn needs to > inspect the route entry that brought the packet there in the > first place. > > If this packet is truly routable, the route entry provides the > GW to be used when looking up the VPN peer to send the packet to. > > However, the route entry is currently dropped before entering > the ovpn xmit function, because the IFF_XMIT_DST_RELEASE priv_flag > is enabled by default. > > Clear the IFF_XMIT_DST_RELEASE flag during interface setup to allow > the route entry (skb's dst) to survive and thus be inspected > by the ovpn routing logic. > > Fixes: a3aaef8cd173 ("ovpn: implement peer lookup logic") > Reported-by: Gert Doering > Tested-by: Gert Doering > Acked-by: Gert Doering # as a primary user > Signed-off-by: Antonio Quartulli > --- > drivers/net/ovpn/io.c | 2 ++ > drivers/net/ovpn/main.c | 5 +++++ > 2 files changed, 7 insertions(+) > > diff --git a/drivers/net/ovpn/io.c b/drivers/net/ovpn/io.c > index dd8a8055d967..7e4b89484c9d 100644 > --- a/drivers/net/ovpn/io.c > +++ b/drivers/net/ovpn/io.c > @@ -398,6 +398,8 @@ netdev_tx_t ovpn_net_xmit(struct sk_buff *skb, struct net_device *dev) > netdev_name(ovpn->dev)); > goto drop; > } > + /* dst was needed for peer selection - it can now be dropped */ > + skb_dst_drop(skb); > > ovpn_peer_stats_increment_tx(&peer->vpn_stats, skb->len); > ovpn_send(ovpn, skb_list.next, peer); > diff --git a/drivers/net/ovpn/main.c b/drivers/net/ovpn/main.c > index 0acb0934c1be..dcc094bf3ade 100644 > --- a/drivers/net/ovpn/main.c > +++ b/drivers/net/ovpn/main.c > @@ -157,6 +157,11 @@ static void ovpn_setup(struct net_device *dev) > dev->type = ARPHRD_NONE; > dev->flags = IFF_POINTOPOINT | IFF_NOARP; > dev->priv_flags |= IFF_NO_QUEUE; > + /* when routing packets to a LAN behind a client, we rely on the > + * route entry that originally brought the packet into ovpn, so > + * don't release it > + */ > + dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; See commit 0287587884b15041203b3a362d485e1ab1f24445; the above should be netif_keep_dst(dev); and no need to additional comment, as the helper nails it. Thanks, Paolo