From: Yan Zhai yan@cloudflare.com
[ Upstream commit 9840036786d90cea11a90d1f30b6dc003b34ee67 ]
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/CAJPywTKDdjtwkLVUW6LRA2FU912qcDmQOQGt2WaDo28KzYD...
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@gmail.com 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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/udp_offload.c | 16 +++++++++++----- net/ipv6/udp_offload.c | 3 +-- 2 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index 1f01e15ca24fd..4a61832e7f69b 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 */ @@ -387,8 +394,7 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 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; diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c index c39c1e32f9804..e0e10f6bcdc18 100644 --- a/net/ipv6/udp_offload.c +++ b/net/ipv6/udp_offload.c @@ -42,8 +42,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, 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;