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@@ -0,0 +1,332 @@
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+/*
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+ * IPV4 GSO/GRO offload support
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+ * Linux INET implementation
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * as published by the Free Software Foundation; either version
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+ * 2 of the License, or (at your option) any later version.
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+ *
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+ * TCPv4 GSO/GRO support
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+ */
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+
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+#include <linux/skbuff.h>
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+#include <net/tcp.h>
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+#include <net/protocol.h>
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+
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+struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
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+ netdev_features_t features)
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+{
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+ struct sk_buff *segs = ERR_PTR(-EINVAL);
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+ struct tcphdr *th;
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+ unsigned int thlen;
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+ unsigned int seq;
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+ __be32 delta;
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+ unsigned int oldlen;
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+ unsigned int mss;
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+ struct sk_buff *gso_skb = skb;
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+ __sum16 newcheck;
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+ bool ooo_okay, copy_destructor;
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+
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+ if (!pskb_may_pull(skb, sizeof(*th)))
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+ goto out;
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+
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+ th = tcp_hdr(skb);
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+ thlen = th->doff * 4;
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+ if (thlen < sizeof(*th))
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+ goto out;
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+
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+ if (!pskb_may_pull(skb, thlen))
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+ goto out;
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+
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+ oldlen = (u16)~skb->len;
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+ __skb_pull(skb, thlen);
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+
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+ mss = tcp_skb_mss(skb);
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+ if (unlikely(skb->len <= mss))
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+ goto out;
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+
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+ if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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+ /* Packet is from an untrusted source, reset gso_segs. */
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+ int type = skb_shinfo(skb)->gso_type;
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+
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+ if (unlikely(type &
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+ ~(SKB_GSO_TCPV4 |
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+ SKB_GSO_DODGY |
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+ SKB_GSO_TCP_ECN |
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+ SKB_GSO_TCPV6 |
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+ SKB_GSO_GRE |
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+ SKB_GSO_MPLS |
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+ SKB_GSO_UDP_TUNNEL |
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+ 0) ||
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+ !(type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6))))
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+ goto out;
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+
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+ skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
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+
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+ segs = NULL;
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+ goto out;
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+ }
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+
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+ copy_destructor = gso_skb->destructor == tcp_wfree;
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+ ooo_okay = gso_skb->ooo_okay;
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+ /* All segments but the first should have ooo_okay cleared */
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+ skb->ooo_okay = 0;
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+
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+ segs = skb_segment(skb, features);
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+ if (IS_ERR(segs))
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+ goto out;
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+
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+ /* Only first segment might have ooo_okay set */
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+ segs->ooo_okay = ooo_okay;
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+
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+ delta = htonl(oldlen + (thlen + mss));
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+
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+ skb = segs;
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+ th = tcp_hdr(skb);
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+ seq = ntohl(th->seq);
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+
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+ newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
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+ (__force u32)delta));
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+
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+ do {
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+ th->fin = th->psh = 0;
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+ th->check = newcheck;
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+
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+ if (skb->ip_summed != CHECKSUM_PARTIAL)
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+ th->check =
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+ csum_fold(csum_partial(skb_transport_header(skb),
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+ thlen, skb->csum));
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+
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+ seq += mss;
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+ if (copy_destructor) {
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+ skb->destructor = gso_skb->destructor;
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+ skb->sk = gso_skb->sk;
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+ /* {tcp|sock}_wfree() use exact truesize accounting :
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+ * sum(skb->truesize) MUST be exactly be gso_skb->truesize
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+ * So we account mss bytes of 'true size' for each segment.
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+ * The last segment will contain the remaining.
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+ */
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+ skb->truesize = mss;
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+ gso_skb->truesize -= mss;
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+ }
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+ skb = skb->next;
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+ th = tcp_hdr(skb);
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+
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+ th->seq = htonl(seq);
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+ th->cwr = 0;
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+ } while (skb->next);
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+
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+ /* Following permits TCP Small Queues to work well with GSO :
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+ * The callback to TCP stack will be called at the time last frag
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+ * is freed at TX completion, and not right now when gso_skb
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+ * is freed by GSO engine
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+ */
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+ if (copy_destructor) {
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+ swap(gso_skb->sk, skb->sk);
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+ swap(gso_skb->destructor, skb->destructor);
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+ swap(gso_skb->truesize, skb->truesize);
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+ }
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+
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+ delta = htonl(oldlen + (skb_tail_pointer(skb) -
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+ skb_transport_header(skb)) +
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+ skb->data_len);
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+ th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
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+ (__force u32)delta));
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+ if (skb->ip_summed != CHECKSUM_PARTIAL)
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+ th->check = csum_fold(csum_partial(skb_transport_header(skb),
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+ thlen, skb->csum));
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+out:
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+ return segs;
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+}
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+EXPORT_SYMBOL(tcp_tso_segment);
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+
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+struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
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+{
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+ struct sk_buff **pp = NULL;
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+ struct sk_buff *p;
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+ struct tcphdr *th;
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+ struct tcphdr *th2;
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+ unsigned int len;
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+ unsigned int thlen;
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+ __be32 flags;
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+ unsigned int mss = 1;
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+ unsigned int hlen;
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+ unsigned int off;
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+ int flush = 1;
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+ int i;
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+
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+ off = skb_gro_offset(skb);
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+ hlen = off + sizeof(*th);
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+ th = skb_gro_header_fast(skb, off);
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+ if (skb_gro_header_hard(skb, hlen)) {
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+ th = skb_gro_header_slow(skb, hlen, off);
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+ if (unlikely(!th))
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+ goto out;
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+ }
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+
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+ thlen = th->doff * 4;
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+ if (thlen < sizeof(*th))
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+ goto out;
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+
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+ hlen = off + thlen;
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+ if (skb_gro_header_hard(skb, hlen)) {
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+ th = skb_gro_header_slow(skb, hlen, off);
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+ if (unlikely(!th))
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+ goto out;
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+ }
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+
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+ skb_gro_pull(skb, thlen);
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+
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+ len = skb_gro_len(skb);
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+ flags = tcp_flag_word(th);
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+
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+ for (; (p = *head); head = &p->next) {
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+ if (!NAPI_GRO_CB(p)->same_flow)
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+ continue;
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+
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+ th2 = tcp_hdr(p);
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+
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+ if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
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+ NAPI_GRO_CB(p)->same_flow = 0;
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+ continue;
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+ }
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+
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+ goto found;
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+ }
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+
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+ goto out_check_final;
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+
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+found:
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+ flush = NAPI_GRO_CB(p)->flush;
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+ flush |= (__force int)(flags & TCP_FLAG_CWR);
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+ flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
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+ ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
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+ flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
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+ for (i = sizeof(*th); i < thlen; i += 4)
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+ flush |= *(u32 *)((u8 *)th + i) ^
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+ *(u32 *)((u8 *)th2 + i);
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+
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+ mss = tcp_skb_mss(p);
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+
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+ flush |= (len - 1) >= mss;
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+ flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
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+
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+ if (flush || skb_gro_receive(head, skb)) {
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+ mss = 1;
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+ goto out_check_final;
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+ }
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+
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+ p = *head;
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+ th2 = tcp_hdr(p);
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+ tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
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+
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+out_check_final:
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+ flush = len < mss;
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+ flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
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+ TCP_FLAG_RST | TCP_FLAG_SYN |
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+ TCP_FLAG_FIN));
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+
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+ if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
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+ pp = head;
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+
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+out:
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+ NAPI_GRO_CB(skb)->flush |= flush;
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+
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+ return pp;
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+}
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+EXPORT_SYMBOL(tcp_gro_receive);
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+
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+int tcp_gro_complete(struct sk_buff *skb)
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+{
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+ struct tcphdr *th = tcp_hdr(skb);
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+
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+ skb->csum_start = skb_transport_header(skb) - skb->head;
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+ skb->csum_offset = offsetof(struct tcphdr, check);
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+ skb->ip_summed = CHECKSUM_PARTIAL;
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+
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+ skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
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+
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+ if (th->cwr)
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+ skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL(tcp_gro_complete);
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+
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+static int tcp_v4_gso_send_check(struct sk_buff *skb)
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+{
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+ const struct iphdr *iph;
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+ struct tcphdr *th;
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+
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+ if (!pskb_may_pull(skb, sizeof(*th)))
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+ return -EINVAL;
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+
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+ iph = ip_hdr(skb);
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+ th = tcp_hdr(skb);
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+
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+ th->check = 0;
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+ skb->ip_summed = CHECKSUM_PARTIAL;
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+ __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
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+ return 0;
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+}
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+
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+static struct sk_buff **tcp4_gro_receive(struct sk_buff **head, struct sk_buff *skb)
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+{
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+ const struct iphdr *iph = skb_gro_network_header(skb);
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+ __wsum wsum;
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+ __sum16 sum;
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+
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+ switch (skb->ip_summed) {
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+ case CHECKSUM_COMPLETE:
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+ if (!tcp_v4_check(skb_gro_len(skb), iph->saddr, iph->daddr,
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+ skb->csum)) {
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+ skb->ip_summed = CHECKSUM_UNNECESSARY;
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+ break;
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+ }
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+flush:
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+ NAPI_GRO_CB(skb)->flush = 1;
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+ return NULL;
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+
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+ case CHECKSUM_NONE:
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+ wsum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
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+ skb_gro_len(skb), IPPROTO_TCP, 0);
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+ sum = csum_fold(skb_checksum(skb,
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+ skb_gro_offset(skb),
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+ skb_gro_len(skb),
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+ wsum));
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+ if (sum)
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+ goto flush;
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+
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+ skb->ip_summed = CHECKSUM_UNNECESSARY;
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+ break;
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+ }
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+
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+ return tcp_gro_receive(head, skb);
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+}
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+
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+static int tcp4_gro_complete(struct sk_buff *skb)
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+{
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+ const struct iphdr *iph = ip_hdr(skb);
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+ struct tcphdr *th = tcp_hdr(skb);
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+
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+ th->check = ~tcp_v4_check(skb->len - skb_transport_offset(skb),
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+ iph->saddr, iph->daddr, 0);
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+ skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
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+
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+ return tcp_gro_complete(skb);
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+}
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+
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+static const struct net_offload tcpv4_offload = {
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+ .callbacks = {
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+ .gso_send_check = tcp_v4_gso_send_check,
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+ .gso_segment = tcp_tso_segment,
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+ .gro_receive = tcp4_gro_receive,
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+ .gro_complete = tcp4_gro_complete,
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+ },
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+};
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+
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+int __init tcpv4_offload_init(void)
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+{
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+ return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
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+}
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Daniel Borkmann