From 9840036786d90cea11a90d1f30b6dc003b34ee67 Mon Sep 17 00:00:00 2001 From: Yan Zhai Date: Thu, 13 Jul 2023 10:28:00 -0700 Subject: [PATCH] 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. Fixes: 1fd54773c267 ("udp: allow header check for dodgy GSO_UDP_L4 packets.") Suggested-by: Willem de Bruijn Signed-off-by: Yan Zhai Reviewed-by: Willem de Bruijn Acked-by: Jason Wang Signed-off-by: David S. Miller --- 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 75aa4de..f402946 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -274,13 +274,20 @@ 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 */ @@ -388,8 +395,7 @@ 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 ad3b872..09fa7a4 100644 --- a/net/ipv6/udp_offload.c +++ b/net/ipv6/udp_offload.c @@ -43,8 +43,7 @@ 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; -- 2.7.4