[PATCH v4 net-next v4 2/6] net: add support for segmenting TCP fraglist GSO packets

Felix Fietkau
2024-04-27T18:23:15Z

Preparation for adding TCP fraglist GRO support. It expects packets to be
combined in a similar way as UDP fraglist GSO packets.
For IPv4 packets, NAT is handled in the same way as UDP fraglist GSO.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
net/ipv4/tcp_offload.c | 67 ++++++++++++++++++++++++++++++++++++++++
net/ipv6/tcpv6_offload.c | 58 ++++++++++++++++++++++++++++++++++
2 files changed, 125 insertions(+)

diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
index fab0973f995b..affd4ed28cfe 100644
--- a/net/ipv4/tcp_offload.c
+++ b/net/ipv4/tcp_offload.c
@@ -28,6 +28,70 @@ static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
}
}

+static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
+ __be32 *oldip, __be32 newip,
+ __be16 *oldport, __be16 newport)
+{
+ struct tcphdr *th;
+ struct iphdr *iph;
+
+ if (*oldip == newip && *oldport == newport)
+ return;
+
+ th = tcp_hdr(seg);
+ iph = ip_hdr(seg);
+
+ inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
+ inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
+ *oldport = newport;
+
+ csum_replace4(&iph->check, *oldip, newip);
+ *oldip = newip;
+}
+
+static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
+{
+ const struct tcphdr *th;
+ const struct iphdr *iph;
+ struct sk_buff *seg;
+ struct tcphdr *th2;
+ struct iphdr *iph2;
+
+ seg = segs;
+ th = tcp_hdr(seg);
+ iph = ip_hdr(seg);
+ th2 = tcp_hdr(seg->next);
+ iph2 = ip_hdr(seg->next);
+
+ if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
+ iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
+ return segs;
+
+ while ((seg = seg->next)) {
+ th2 = tcp_hdr(seg);
+ iph2 = ip_hdr(seg);
+
+ __tcpv4_gso_segment_csum(seg,
+ &iph2->saddr, iph->saddr,
+ &th2->source, th->source);
+ __tcpv4_gso_segment_csum(seg,
+ &iph2->daddr, iph->daddr,
+ &th2->dest, th->dest);
+ }
+
+ return segs;
+}
+
+static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
+ if (IS_ERR(skb))
+ return skb;
+
+ return __tcpv4_gso_segment_list_csum(skb);
+}
+
static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
@@ -37,6 +101,9 @@ static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
return ERR_PTR(-EINVAL);

+ if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
+ return __tcp4_gso_segment_list(skb, features);
+
if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
const struct iphdr *iph = ip_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);
diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
index 4b07d1e6c952..7180c30dbbef 100644
--- a/net/ipv6/tcpv6_offload.c
+++ b/net/ipv6/tcpv6_offload.c
@@ -40,6 +40,61 @@ INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
return 0;
}

+static void __tcpv6_gso_segment_csum(struct sk_buff *seg,
+ __be16 *oldport, __be16 newport)
+{
+ struct tcphdr *th;
+
+ if (*oldport == newport)
+ return;
+
+ th = tcp_hdr(seg);
+ inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
+ *oldport = newport;
+}
+
+static struct sk_buff *__tcpv6_gso_segment_list_csum(struct sk_buff *segs)
+{
+ const struct tcphdr *th;
+ const struct ipv6hdr *iph;
+ struct sk_buff *seg;
+ struct tcphdr *th2;
+ struct ipv6hdr *iph2;
+
+ seg = segs;
+ th = tcp_hdr(seg);
+ iph = ipv6_hdr(seg);
+ th2 = tcp_hdr(seg->next);
+ iph2 = ipv6_hdr(seg->next);
+
+ if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
+ ipv6_addr_equal(&iph->saddr, &iph2->saddr) &&
+ ipv6_addr_equal(&iph->daddr, &iph2->daddr))
+ return segs;
+
+ while ((seg = seg->next)) {
+ th2 = tcp_hdr(seg);
+ iph2 = ipv6_hdr(seg);
+
+ iph2->saddr = iph->saddr;
+ iph2->daddr = iph->daddr;
+ __tcpv6_gso_segment_csum(seg, &th2->source, th->source);
+ __tcpv6_gso_segment_csum(seg, &th2->dest, th->dest);
+ }
+
+ return segs;
+}
+
+static struct sk_buff *__tcp6_gso_segment_list(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
+ if (IS_ERR(skb))
+ return skb;
+
+ return __tcpv6_gso_segment_list_csum(skb);
+}
+
static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
@@ -51,6 +106,9 @@ static struct sk_buff *tcp6_gso_segment(struct sk_buff *skb,
if (!pskb_may_pull(skb, sizeof(*th)))
return ERR_PTR(-EINVAL);

+ if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
+ return __tcp6_gso_segment_list(skb, features);
+
if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
struct tcphdr *th = tcp_hdr(skb);
--
2.44.0