net/ipv4/tcp_offload.c - linux - Git at Google

 // 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/gro.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(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;

 	/* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
 	 * If it is a single frame, do not aggregate it if its length
 	 * is bigger than our mss.
 	 */
 	if (unlikely(skb_is_gso(skb)))
 		flush |= (mss != skb_shinfo(skb)->gso_size);
 	else
 		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:
 	/* Force a flush if last segment is smaller than mss. */
 	if (unlikely(skb_is_gso(skb)))
 		flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
 	else
 		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);
 }
	// 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/gro.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(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;

	/* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
	* If it is a single frame, do not aggregate it if its length
	* is bigger than our mss.
	*/
	if (unlikely(skb_is_gso(skb)))
	flush \|= (mss != skb_shinfo(skb)->gso_size);
	else
	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:
	/* Force a flush if last segment is smaller than mss. */
	if (unlikely(skb_is_gso(skb)))
	flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
	else
	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);
	}