UDP/IP header of UDP GROed frag_skbs are not updated even after NAT forwarding. Only the header of head_skb from ip_finish_output_gso -> skb_gso_segment is updated but following frag_skbs are not updated.
A call path skb_mac_gso_segment -> inet_gso_segment -> udp4_ufo_fragment -> __udp_gso_segment -> __udp_gso_segment_list does not try to update UDP/IP header of the segment list. Update dport, daddr and checksums of each skb of the segment list after __udp_gso_segment. Fixes: 9fd1ff5d2ac7 (udp: Support UDP fraglist GRO/GSO.) Signed-off-by: Dongseok Yi <dseok...@samsung.com> --- Steffen Klassert said, there could be 2 options. https://lore.kernel.org/patchwork/patch/1362257/ I was trying to write a quick fix, but it was not easy to forward segmented list. Currently, assuming DNAT only. Should we consider SNAT too? net/ipv4/udp_offload.c | 45 +++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 41 insertions(+), 4 deletions(-) diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c index ff39e94..7e24928 100644 --- a/net/ipv4/udp_offload.c +++ b/net/ipv4/udp_offload.c @@ -309,10 +309,12 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, netdev_features_t features) { struct sk_buff *segs = ERR_PTR(-EINVAL); + struct sk_buff *seg; unsigned int mss; __wsum csum; - struct udphdr *uh; - struct iphdr *iph; + struct udphdr *uh, *uh2; + struct iphdr *iph, *iph2; + bool is_fraglist = false; if (skb->encapsulation && (skb_shinfo(skb)->gso_type & @@ -327,8 +329,43 @@ 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) - return __udp_gso_segment(skb, features); + if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) { + if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) + is_fraglist = true; + + segs = __udp_gso_segment(skb, features); + if (IS_ERR_OR_NULL(segs) || !is_fraglist) + return segs; + + seg = segs; + uh = udp_hdr(seg); + iph = ip_hdr(seg); + + while ((seg = seg->next)) { + uh2 = udp_hdr(seg); + iph2 = ip_hdr(seg); + + if (uh->dest == uh2->dest && iph->daddr == iph2->daddr) + continue; + + if (uh2->check) { + inet_proto_csum_replace4(&uh2->check, seg, + iph2->daddr, + iph->daddr, true); + inet_proto_csum_replace2(&uh2->check, seg, + uh2->dest, uh->dest, + false); + if (!uh2->check) + uh2->check = CSUM_MANGLED_0; + } + uh2->dest = uh->dest; + + csum_replace4(&iph2->check, iph2->daddr, iph->daddr); + iph2->daddr = iph->daddr; + } + + return segs; + } mss = skb_shinfo(skb)->gso_size; if (unlikely(skb->len <= mss)) -- 2.7.4
