BACKPORT: gso: fix dodgy bit handling for GSO_UDP_L4
Commit 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4
packets.") checks DODGY bit for UDP, but for packets that can be fed
directly to the device after gso_segs reset, it actually falls through
to fragmentation:
https://lore.kernel.org/all/CAJPywTKDdjtwkLVUW6LRA2FU912qcDmQOQGt2WaDo28KzYDg+A@mail.gmail.com/
This change restores the expected behavior of GSO_UDP_L4 packets.
Bug: 327698903
Fixes: 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4 packets.")
Suggested-by: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Change-Id: Id7ff0fac79fb0b4fabb62b09a905f27a5e8cfea7
(cherry picked from commit 9840036786d90cea11a90d1f30b6dc003b34ee67)
[lena: Resolved conflict in net/ipv6/udp_offload.c ]
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit c38ea4a1319d052527deef514f615b1f18278be8)
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index 6d1a4be..d0e8239 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -273,13 +273,20 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
__sum16 check;
__be16 newlen;
- if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)
- return __udp_gso_segment_list(gso_skb, features, is_ipv6);
-
mss = skb_shinfo(gso_skb)->gso_size;
if (gso_skb->len <= sizeof(*uh) + mss)
return ERR_PTR(-EINVAL);
+ if (skb_gso_ok(gso_skb, features | NETIF_F_GSO_ROBUST)) {
+ /* Packet is from an untrusted source, reset gso_segs. */
+ skb_shinfo(gso_skb)->gso_segs = DIV_ROUND_UP(gso_skb->len - sizeof(*uh),
+ mss);
+ return NULL;
+ }
+
+ if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)
+ return __udp_gso_segment_list(gso_skb, features, is_ipv6);
+
skb_pull(gso_skb, sizeof(*uh));
/* clear destructor to avoid skb_segment assigning it to tail */
