1 files changed, 348 insertions, 0 deletions
diff --git a/net/ipv4/tcp_offload.c b/net/ipv4/tcp_offload.c
new file mode 100644
index 000000000..fc61cd3fe
--- /dev/null
+++ b/net/ipv4/tcp_offload.c
@@ -0,0 +1,348 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *	IPV4 GSO/GRO offload support
+ *	Linux INET implementation
+ *
+ *	TCPv4 GSO/GRO support
+ */
+
+#include <linux/indirect_call_wrapper.h>
+#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;
+
+	if (skb->encapsulation)
+		skb->inner_transport_header = skb->transport_header;
+
+	return 0;
+}
+EXPORT_SYMBOL(tcp_gro_complete);
+
+INDIRECT_CALLABLE_SCOPE
+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);
+}
+
+INDIRECT_CALLABLE_SCOPE 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);
+}