6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Yan Zhai <yan@xxxxxxxxxxxxxx>
commit 9840036786d90cea11a90d1f30b6dc003b34ee67 upstream.
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@xxxxxxxxxxxxxx/
This change restores the expected behavior of GSO_UDP_L4 packets.
Fixes: 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4 packets.")
Suggested-by: Willem de Bruijn <willemdebruijn.kernel@xxxxxxxxx>
Signed-off-by: Yan Zhai <yan@xxxxxxxxxxxxxx>
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv4/udp_offload.c | 16 +++++++++++-----
net/ipv6/udp_offload.c | 3 +--
2 files changed, 12 insertions(+), 7 deletions(-)
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c
@@ -273,13 +273,20 @@ struct sk_buff *__udp_gso_segment(struct
__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 */
@@ -387,8 +394,7 @@ static struct sk_buff *udp4_ufo_fragment
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
- if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 &&
- !skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST))
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
return __udp_gso_segment(skb, features, false);
mss = skb_shinfo(skb)->gso_size;
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c
@@ -42,8 +42,7 @@ static struct sk_buff *udp6_ufo_fragment
if (!pskb_may_pull(skb, sizeof(struct udphdr)))
goto out;
- if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4 &&
- !skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST))
+ if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
return __udp_gso_segment(skb, features, true);
mss = skb_shinfo(skb)->gso_size;
