[PATCH net v3] udp: ipv4: manipulate network header of NATed UDP GRO fraglist
From: Dongseok Yi <hidden>
Date: 2021-01-21 13:41:52
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 but copy only the MAC header. Update port, addr and check of each skb of the segment list in __udp_gso_segment_list. It covers both SNAT and DNAT. Fixes: 9fd1ff5d2ac7 (udp: Support UDP fraglist GRO/GSO.) Signed-off-by: Dongseok Yi <redacted> --- v1: 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. v2: Per Steffen Klassert request, moved the procedure from udp4_ufo_fragment to __udp_gso_segment_list and support SNAT. v3: Per Steffen Klassert request, applied fast return by comparing seg and seg->next at the beginning of __udpv4_gso_segment_list_csum. Fixed uh->dest = *newport and iph->daddr = *newip to *oldport = *newport and *oldip = *newip. include/net/udp.h | 2 +- net/ipv4/udp_offload.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++---- net/ipv6/udp_offload.c | 2 +- 3 files changed, 69 insertions(+), 7 deletions(-)
diff --git a/include/net/udp.h b/include/net/udp.h
index 877832b..01351ba 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h@@ -178,7 +178,7 @@ struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb, int udp_gro_complete(struct sk_buff *skb, int nhoff, udp_lookup_t lookup); struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, - netdev_features_t features); + netdev_features_t features, bool is_ipv6); static inline struct udphdr *udp_gro_udphdr(struct sk_buff *skb) {
diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
index ff39e94..43660cf 100644
--- a/net/ipv4/udp_offload.c
+++ b/net/ipv4/udp_offload.c@@ -187,8 +187,67 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, } EXPORT_SYMBOL(skb_udp_tunnel_segment); +static void __udpv4_gso_segment_csum(struct sk_buff *seg, + __be32 *oldip, __be32 *newip, + __be16 *oldport, __be16 *newport) +{ + struct udphdr *uh; + struct iphdr *iph; + + if (*oldip == *newip && *oldport == *newport) + return; + + uh = udp_hdr(seg); + iph = ip_hdr(seg); + + if (uh->check) { + inet_proto_csum_replace4(&uh->check, seg, *oldip, *newip, + true); + inet_proto_csum_replace2(&uh->check, seg, *oldport, *newport, + false); + if (!uh->check) + uh->check = CSUM_MANGLED_0; + } + *oldport = *newport; + + csum_replace4(&iph->check, *oldip, *newip); + *oldip = *newip; +} + +static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs) +{ + struct sk_buff *seg; + struct udphdr *uh, *uh2; + struct iphdr *iph, *iph2; + + seg = segs; + uh = udp_hdr(seg); + iph = ip_hdr(seg); + + if ((udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) && + (udp_hdr(seg)->source == udp_hdr(seg->next)->source) && + (ip_hdr(seg)->daddr == ip_hdr(seg->next)->daddr) && + (ip_hdr(seg)->saddr == ip_hdr(seg->next)->saddr)) + return segs; + + while ((seg = seg->next)) { + uh2 = udp_hdr(seg); + iph2 = ip_hdr(seg); + + __udpv4_gso_segment_csum(seg, + &iph2->saddr, &iph->saddr, + &uh2->source, &uh->source); + __udpv4_gso_segment_csum(seg, + &iph2->daddr, &iph->daddr, + &uh2->dest, &uh->dest); + } + + return segs; +} + static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb, - netdev_features_t features) + netdev_features_t features, + bool is_ipv6) { unsigned int mss = skb_shinfo(skb)->gso_size;
@@ -198,11 +257,14 @@ static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb, udp_hdr(skb)->len = htons(sizeof(struct udphdr) + mss); - return skb; + if (is_ipv6) + return skb; + else + return __udpv4_gso_segment_list_csum(skb); } struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, - netdev_features_t features) + netdev_features_t features, bool is_ipv6) { struct sock *sk = gso_skb->sk; unsigned int sum_truesize = 0;
@@ -214,7 +276,7 @@ struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb, __be16 newlen; if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST) - return __udp_gso_segment_list(gso_skb, features); + return __udp_gso_segment_list(gso_skb, features, is_ipv6); mss = skb_shinfo(gso_skb)->gso_size; if (gso_skb->len <= sizeof(*uh) + mss)
@@ -328,7 +390,7 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, goto out; if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) - return __udp_gso_segment(skb, features); + return __udp_gso_segment(skb, features, false); mss = skb_shinfo(skb)->gso_size; if (unlikely(skb->len <= mss))
diff --git a/net/ipv6/udp_offload.c b/net/ipv6/udp_offload.c
index c7bd7b1..faa823c 100644
--- a/net/ipv6/udp_offload.c
+++ b/net/ipv6/udp_offload.c@@ -42,7 +42,7 @@ static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb, goto out; if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4) - return __udp_gso_segment(skb, features); + return __udp_gso_segment(skb, features, true); mss = skb_shinfo(skb)->gso_size; if (unlikely(skb->len <= mss))
--
2.7.4