From: Willem de Bruijn willemb@google.com
[ Upstream commit 96aa1b22bd6bb9fccf62f6261f390ed6f3e7967f ]
Tun in IFF_NAPI_FRAGS mode calls napi_gro_frags. Unlike netif_rx and netif_gro_receive, this expects skb->data to point to the mac layer.
But skb_probe_transport_header, __skb_get_hash_symmetric, and xdp_do_generic in tun_get_user need skb->data to point to the network header. Flow dissection also needs skb->protocol set, so eth_type_trans has to be called.
Ensure the link layer header lies in linear as eth_type_trans pulls ETH_HLEN. Then take the same code paths for frags as for not frags. Push the link layer header back just before calling napi_gro_frags.
By pulling up to ETH_HLEN from frag0 into linear, this disables the frag0 optimization in the special case when IFF_NAPI_FRAGS is used with zero length iov[0] (and thus empty skb->linear).
Fixes: 90e33d459407 ("tun: enable napi_gro_frags() for TUN/TAP driver") Signed-off-by: Willem de Bruijn willemb@google.com Acked-by: Petar Penkov ppenkov@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/tun.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 44889eba1dbc..b984733c6c31 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1871,8 +1871,11 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, skb->dev = tun->dev; break; case IFF_TAP: - if (!frags) - skb->protocol = eth_type_trans(skb, tun->dev); + if (frags && !pskb_may_pull(skb, ETH_HLEN)) { + err = -ENOMEM; + goto drop; + } + skb->protocol = eth_type_trans(skb, tun->dev); break; }
@@ -1929,9 +1932,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, }
if (frags) { + u32 headlen; + /* Exercise flow dissector code path. */ - u32 headlen = eth_get_headlen(tun->dev, skb->data, - skb_headlen(skb)); + skb_push(skb, ETH_HLEN); + headlen = eth_get_headlen(tun->dev, skb->data, + skb_headlen(skb));
if (unlikely(headlen > skb_headlen(skb))) { this_cpu_inc(tun->pcpu_stats->rx_dropped);