v4.19.13 snapshot.
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
new file mode 100644
index 0000000..870b0a3
--- /dev/null
+++ b/net/ipv4/tcp_offload.c
@@ -0,0 +1,347 @@
+/*
+ * IPV4 GSO/GRO offload support
+ * Linux INET implementation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * TCPv4 GSO/GRO support
+ */
+
+#include <linux/skbuff.h>
+#include <net/tcp.h>
+#include <net/protocol.h>
+
+static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
+ unsigned int seq, unsigned int mss)
+{
+ while (skb) {
+ if (before(ts_seq, seq + mss)) {
+ skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
+ skb_shinfo(skb)->tskey = ts_seq;
+ return;
+ }
+
+ skb = skb->next;
+ seq += mss;
+ }
+}
+
+static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
+ return ERR_PTR(-EINVAL);
+
+ if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
+ return ERR_PTR(-EINVAL);
+
+ if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
+ const struct iphdr *iph = ip_hdr(skb);
+ struct tcphdr *th = tcp_hdr(skb);
+
+ /* Set up checksum pseudo header, usually expect stack to
+ * have done this already.
+ */
+
+ th->check = 0;
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
+ }
+
+ return tcp_gso_segment(skb, features);
+}
+
+struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
+ netdev_features_t features)
+{
+ struct sk_buff *segs = ERR_PTR(-EINVAL);
+ unsigned int sum_truesize = 0;
+ struct tcphdr *th;
+ unsigned int thlen;
+ unsigned int seq;
+ __be32 delta;
+ unsigned int oldlen;
+ unsigned int mss;
+ struct sk_buff *gso_skb = skb;
+ __sum16 newcheck;
+ bool ooo_okay, copy_destructor;
+
+ th = tcp_hdr(skb);
+ thlen = th->doff * 4;
+ if (thlen < sizeof(*th))
+ goto out;
+
+ if (!pskb_may_pull(skb, thlen))
+ goto out;
+
+ oldlen = (u16)~skb->len;
+ __skb_pull(skb, thlen);
+
+ mss = skb_shinfo(skb)->gso_size;
+ if (unlikely(skb->len <= mss))
+ goto out;
+
+ if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+ /* Packet is from an untrusted source, reset gso_segs. */
+
+ skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
+
+ segs = NULL;
+ goto out;
+ }
+
+ copy_destructor = gso_skb->destructor == tcp_wfree;
+ ooo_okay = gso_skb->ooo_okay;
+ /* All segments but the first should have ooo_okay cleared */
+ skb->ooo_okay = 0;
+
+ segs = skb_segment(skb, features);
+ if (IS_ERR(segs))
+ goto out;
+
+ /* Only first segment might have ooo_okay set */
+ segs->ooo_okay = ooo_okay;
+
+ /* GSO partial and frag_list segmentation only requires splitting
+ * the frame into an MSS multiple and possibly a remainder, both
+ * cases return a GSO skb. So update the mss now.
+ */
+ if (skb_is_gso(segs))
+ mss *= skb_shinfo(segs)->gso_segs;
+
+ delta = htonl(oldlen + (thlen + mss));
+
+ skb = segs;
+ th = tcp_hdr(skb);
+ seq = ntohl(th->seq);
+
+ if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
+ tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
+
+ newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
+ (__force u32)delta));
+
+ while (skb->next) {
+ th->fin = th->psh = 0;
+ th->check = newcheck;
+
+ if (skb->ip_summed == CHECKSUM_PARTIAL)
+ gso_reset_checksum(skb, ~th->check);
+ else
+ th->check = gso_make_checksum(skb, ~th->check);
+
+ seq += mss;
+ if (copy_destructor) {
+ skb->destructor = gso_skb->destructor;
+ skb->sk = gso_skb->sk;
+ sum_truesize += skb->truesize;
+ }
+ skb = skb->next;
+ th = tcp_hdr(skb);
+
+ th->seq = htonl(seq);
+ th->cwr = 0;
+ }
+
+ /* Following permits TCP Small Queues to work well with GSO :
+ * The callback to TCP stack will be called at the time last frag
+ * is freed at TX completion, and not right now when gso_skb
+ * is freed by GSO engine
+ */
+ if (copy_destructor) {
+ int delta;
+
+ swap(gso_skb->sk, skb->sk);
+ swap(gso_skb->destructor, skb->destructor);
+ sum_truesize += skb->truesize;
+ delta = sum_truesize - gso_skb->truesize;
+ /* In some pathological cases, delta can be negative.
+ * We need to either use refcount_add() or refcount_sub_and_test()
+ */
+ if (likely(delta >= 0))
+ refcount_add(delta, &skb->sk->sk_wmem_alloc);
+ else
+ WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
+ }
+
+ delta = htonl(oldlen + (skb_tail_pointer(skb) -
+ skb_transport_header(skb)) +
+ skb->data_len);
+ th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
+ (__force u32)delta));
+ if (skb->ip_summed == CHECKSUM_PARTIAL)
+ gso_reset_checksum(skb, ~th->check);
+ else
+ th->check = gso_make_checksum(skb, ~th->check);
+out:
+ return segs;
+}
+
+struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb)
+{
+ struct sk_buff *pp = NULL;
+ struct sk_buff *p;
+ struct tcphdr *th;
+ struct tcphdr *th2;
+ unsigned int len;
+ unsigned int thlen;
+ __be32 flags;
+ unsigned int mss = 1;
+ unsigned int hlen;
+ unsigned int off;
+ int flush = 1;
+ int i;
+
+ off = skb_gro_offset(skb);
+ hlen = off + sizeof(*th);
+ th = skb_gro_header_fast(skb, off);
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
+
+ thlen = th->doff * 4;
+ if (thlen < sizeof(*th))
+ goto out;
+
+ hlen = off + thlen;
+ if (skb_gro_header_hard(skb, hlen)) {
+ th = skb_gro_header_slow(skb, hlen, off);
+ if (unlikely(!th))
+ goto out;
+ }
+
+ skb_gro_pull(skb, thlen);
+
+ len = skb_gro_len(skb);
+ flags = tcp_flag_word(th);
+
+ list_for_each_entry(p, head, list) {
+ if (!NAPI_GRO_CB(p)->same_flow)
+ continue;
+
+ th2 = tcp_hdr(p);
+
+ if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
+ NAPI_GRO_CB(p)->same_flow = 0;
+ continue;
+ }
+
+ goto found;
+ }
+ p = NULL;
+ goto out_check_final;
+
+found:
+ /* Include the IP ID check below from the inner most IP hdr */
+ flush = NAPI_GRO_CB(p)->flush;
+ flush |= (__force int)(flags & TCP_FLAG_CWR);
+ flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
+ ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
+ flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
+ for (i = sizeof(*th); i < thlen; i += 4)
+ flush |= *(u32 *)((u8 *)th + i) ^
+ *(u32 *)((u8 *)th2 + i);
+
+ /* When we receive our second frame we can made a decision on if we
+ * continue this flow as an atomic flow with a fixed ID or if we use
+ * an incrementing ID.
+ */
+ if (NAPI_GRO_CB(p)->flush_id != 1 ||
+ NAPI_GRO_CB(p)->count != 1 ||
+ !NAPI_GRO_CB(p)->is_atomic)
+ flush |= NAPI_GRO_CB(p)->flush_id;
+ else
+ NAPI_GRO_CB(p)->is_atomic = false;
+
+ mss = skb_shinfo(p)->gso_size;
+
+ flush |= (len - 1) >= mss;
+ flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
+#ifdef CONFIG_TLS_DEVICE
+ flush |= p->decrypted ^ skb->decrypted;
+#endif
+
+ if (flush || skb_gro_receive(p, skb)) {
+ mss = 1;
+ goto out_check_final;
+ }
+
+ tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
+
+out_check_final:
+ flush = len < mss;
+ flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
+ TCP_FLAG_RST | TCP_FLAG_SYN |
+ TCP_FLAG_FIN));
+
+ if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
+ pp = p;
+
+out:
+ NAPI_GRO_CB(skb)->flush |= (flush != 0);
+
+ return pp;
+}
+
+int tcp_gro_complete(struct sk_buff *skb)
+{
+ struct tcphdr *th = tcp_hdr(skb);
+
+ skb->csum_start = (unsigned char *)th - skb->head;
+ skb->csum_offset = offsetof(struct tcphdr, check);
+ skb->ip_summed = CHECKSUM_PARTIAL;
+
+ skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
+
+ if (th->cwr)
+ skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
+
+ return 0;
+}
+EXPORT_SYMBOL(tcp_gro_complete);
+
+static struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
+{
+ /* Don't bother verifying checksum if we're going to flush anyway. */
+ if (!NAPI_GRO_CB(skb)->flush &&
+ skb_gro_checksum_validate(skb, IPPROTO_TCP,
+ inet_gro_compute_pseudo)) {
+ NAPI_GRO_CB(skb)->flush = 1;
+ return NULL;
+ }
+
+ return tcp_gro_receive(head, skb);
+}
+
+static int tcp4_gro_complete(struct sk_buff *skb, int thoff)
+{
+ const struct iphdr *iph = ip_hdr(skb);
+ struct tcphdr *th = tcp_hdr(skb);
+
+ th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
+ iph->daddr, 0);
+ skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4;
+
+ if (NAPI_GRO_CB(skb)->is_atomic)
+ skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_FIXEDID;
+
+ return tcp_gro_complete(skb);
+}
+
+static const struct net_offload tcpv4_offload = {
+ .callbacks = {
+ .gso_segment = tcp4_gso_segment,
+ .gro_receive = tcp4_gro_receive,
+ .gro_complete = tcp4_gro_complete,
+ },
+};
+
+int __init tcpv4_offload_init(void)
+{
+ return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
+}