[linux-block.git] / net / ipv4 / tcp_offload.c

// 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);
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
28850dc7 DB	2	/*
	3	* IPV4 GSO/GRO offload support
	4	* Linux INET implementation
	5	*
28850dc7 DB	6	* TCPv4 GSO/GRO support
	7	*/
	8
028e0a47	9	#include <linux/indirect_call_wrapper.h>
28850dc7	10	#include <linux/skbuff.h>
4721031c	11	#include <net/gro.h>
28850dc7 DB	12	#include <net/tcp.h>
	13	#include <net/protocol.h>
	14
f066e2b0 WB	15	static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
f066e2b0 WB	16	unsigned int seq, unsigned int mss)
4ed2d765 WB	17	{
4ed2d765 WB	18	while (skb) {
f066e2b0 WB	19	if (before(ts_seq, seq + mss)) {
f066e2b0 WB	20	skb_shinfo(skb)->tx_flags \|= SKBTX_SW_TSTAMP;
4ed2d765 WB	21	skb_shinfo(skb)->tskey = ts_seq;
	22	return;
	23	}
	24
	25	skb = skb->next;
	26	seq += mss;
	27	}
	28	}
	29
74abc20c ED	30	static struct sk_buff tcp4_gso_segment(struct sk_buff skb,
74abc20c ED	31	netdev_features_t features)
d020f8f7	32	{
121d57af WB	33	if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
	34	return ERR_PTR(-EINVAL);
	35
d020f8f7 TH	36	if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
	37	return ERR_PTR(-EINVAL);
	38
	39	if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
	40	const struct iphdr *iph = ip_hdr(skb);
	41	struct tcphdr *th = tcp_hdr(skb);
	42
	43	/* Set up checksum pseudo header, usually expect stack to
	44	* have done this already.
	45	*/
	46
	47	th->check = 0;
	48	skb->ip_summed = CHECKSUM_PARTIAL;
	49	__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
	50	}
	51
	52	return tcp_gso_segment(skb, features);
	53	}
	54
28be6e07	55	struct sk_buff tcp_gso_segment(struct sk_buff skb,
28850dc7 DB	56	netdev_features_t features)
	57	{
	58	struct sk_buff *segs = ERR_PTR(-EINVAL);
0d08c42c	59	unsigned int sum_truesize = 0;
28850dc7 DB	60	struct tcphdr *th;
	61	unsigned int thlen;
	62	unsigned int seq;
	63	__be32 delta;
	64	unsigned int oldlen;
	65	unsigned int mss;
	66	struct sk_buff *gso_skb = skb;
	67	__sum16 newcheck;
	68	bool ooo_okay, copy_destructor;
	69
28850dc7 DB	70	th = tcp_hdr(skb);
	71	thlen = th->doff * 4;
	72	if (thlen < sizeof(*th))
	73	goto out;
	74
	75	if (!pskb_may_pull(skb, thlen))
	76	goto out;
	77
	78	oldlen = (u16)~skb->len;
	79	__skb_pull(skb, thlen);
	80
a7eea416	81	mss = skb_shinfo(skb)->gso_size;
28850dc7 DB	82	if (unlikely(skb->len <= mss))
	83	goto out;
	84
	85	if (skb_gso_ok(skb, features \| NETIF_F_GSO_ROBUST)) {
	86	/* Packet is from an untrusted source, reset gso_segs. */
28850dc7 DB	87
	88	skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
	89
	90	segs = NULL;
	91	goto out;
	92	}
	93
	94	copy_destructor = gso_skb->destructor == tcp_wfree;
	95	ooo_okay = gso_skb->ooo_okay;
	96	/* All segments but the first should have ooo_okay cleared */
	97	skb->ooo_okay = 0;
	98
	99	segs = skb_segment(skb, features);
	100	if (IS_ERR(segs))
	101	goto out;
	102
	103	/* Only first segment might have ooo_okay set */
	104	segs->ooo_okay = ooo_okay;
	105
07b26c94 SK	106	/* GSO partial and frag_list segmentation only requires splitting
	107	* the frame into an MSS multiple and possibly a remainder, both
	108	* cases return a GSO skb. So update the mss now.
	109	*/
	110	if (skb_is_gso(segs))
	111	mss *= skb_shinfo(segs)->gso_segs;
	112
28850dc7 DB	113	delta = htonl(oldlen + (thlen + mss));
	114
	115	skb = segs;
	116	th = tcp_hdr(skb);
	117	seq = ntohl(th->seq);
	118
4ed2d765 WB	119	if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
	120	tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
	121
28850dc7 DB	122	newcheck = ~csum_fold((__force __wsum)((__force u32)th->check +
	123	(__force u32)delta));
	124
802ab55a	125	while (skb->next) {
28850dc7 DB	126	th->fin = th->psh = 0;
	127	th->check = newcheck;
	128
08b64fcc AD	129	if (skb->ip_summed == CHECKSUM_PARTIAL)
	130	gso_reset_checksum(skb, ~th->check);
	131	else
e9c3a24b	132	th->check = gso_make_checksum(skb, ~th->check);
28850dc7 DB	133
	134	seq += mss;
	135	if (copy_destructor) {
	136	skb->destructor = gso_skb->destructor;
	137	skb->sk = gso_skb->sk;
0d08c42c	138	sum_truesize += skb->truesize;
28850dc7 DB	139	}
	140	skb = skb->next;
	141	th = tcp_hdr(skb);
	142
	143	th->seq = htonl(seq);
	144	th->cwr = 0;
802ab55a	145	}
28850dc7 DB	146
	147	/* Following permits TCP Small Queues to work well with GSO :
	148	* The callback to TCP stack will be called at the time last frag
	149	* is freed at TX completion, and not right now when gso_skb
	150	* is freed by GSO engine
	151	*/
	152	if (copy_destructor) {
7ec318fe ED	153	int delta;
7ec318fe ED	154
28850dc7 DB	155	swap(gso_skb->sk, skb->sk);
28850dc7 DB	156	swap(gso_skb->destructor, skb->destructor);
0d08c42c	157	sum_truesize += skb->truesize;
7ec318fe ED	158	delta = sum_truesize - gso_skb->truesize;
	159	/* In some pathological cases, delta can be negative.
	160	* We need to either use refcount_add() or refcount_sub_and_test()
	161	*/
	162	if (likely(delta >= 0))
	163	refcount_add(delta, &skb->sk->sk_wmem_alloc);
	164	else
	165	WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
28850dc7 DB	166	}
	167
	168	delta = htonl(oldlen + (skb_tail_pointer(skb) -
	169	skb_transport_header(skb)) +
	170	skb->data_len);
	171	th->check = ~csum_fold((__force __wsum)((__force u32)th->check +
	172	(__force u32)delta));
08b64fcc AD	173	if (skb->ip_summed == CHECKSUM_PARTIAL)
	174	gso_reset_checksum(skb, ~th->check);
	175	else
e9c3a24b	176	th->check = gso_make_checksum(skb, ~th->check);
28850dc7 DB	177	out:
	178	return segs;
	179	}
28850dc7	180
d4546c25	181	struct sk_buff tcp_gro_receive(struct list_head head, struct sk_buff *skb)
28850dc7	182	{
d4546c25	183	struct sk_buff *pp = NULL;
28850dc7 DB	184	struct sk_buff *p;
	185	struct tcphdr *th;
	186	struct tcphdr *th2;
	187	unsigned int len;
	188	unsigned int thlen;
	189	__be32 flags;
	190	unsigned int mss = 1;
	191	unsigned int hlen;
	192	unsigned int off;
	193	int flush = 1;
	194	int i;
	195
	196	off = skb_gro_offset(skb);
	197	hlen = off + sizeof(*th);
35ffb665 RG	198	th = skb_gro_header(skb, hlen, off);
	199	if (unlikely(!th))
	200	goto out;
28850dc7 DB	201
	202	thlen = th->doff * 4;
	203	if (thlen < sizeof(*th))
	204	goto out;
	205
	206	hlen = off + thlen;
	207	if (skb_gro_header_hard(skb, hlen)) {
	208	th = skb_gro_header_slow(skb, hlen, off);
	209	if (unlikely(!th))
	210	goto out;
	211	}
	212
	213	skb_gro_pull(skb, thlen);
	214
	215	len = skb_gro_len(skb);
	216	flags = tcp_flag_word(th);
	217
d4546c25	218	list_for_each_entry(p, head, list) {
28850dc7 DB	219	if (!NAPI_GRO_CB(p)->same_flow)
	220	continue;
	221
	222	th2 = tcp_hdr(p);
	223
	224	if ((u32 )&th->source ^ (u32 )&th2->source) {
	225	NAPI_GRO_CB(p)->same_flow = 0;
	226	continue;
	227	}
	228
	229	goto found;
	230	}
d4546c25	231	p = NULL;
28850dc7 DB	232	goto out_check_final;
	233
	234	found:
bf5a755f	235	/* Include the IP ID check below from the inner most IP hdr */
1530545e	236	flush = NAPI_GRO_CB(p)->flush;
28850dc7 DB	237	flush \|= (__force int)(flags & TCP_FLAG_CWR);
	238	flush \|= (__force int)((flags ^ tcp_flag_word(th2)) &
	239	~(TCP_FLAG_CWR \| TCP_FLAG_FIN \| TCP_FLAG_PSH));
	240	flush \|= (__force int)(th->ack_seq ^ th2->ack_seq);
	241	for (i = sizeof(*th); i < thlen; i += 4)
	242	flush \|= (u32 )((u8 *)th + i) ^
	243	(u32 )((u8 *)th2 + i);
	244
1530545e AD	245	/* When we receive our second frame we can made a decision on if we
	246	* continue this flow as an atomic flow with a fixed ID or if we use
	247	* an incrementing ID.
	248	*/
	249	if (NAPI_GRO_CB(p)->flush_id != 1 \|\|
	250	NAPI_GRO_CB(p)->count != 1 \|\|
	251	!NAPI_GRO_CB(p)->is_atomic)
	252	flush \|= NAPI_GRO_CB(p)->flush_id;
	253	else
	254	NAPI_GRO_CB(p)->is_atomic = false;
	255
a7eea416	256	mss = skb_shinfo(p)->gso_size;
28850dc7	257
5eddb249 CL	258	/* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
	259	* If it is a single frame, do not aggregate it if its length
	260	* is bigger than our mss.
	261	*/
	262	if (unlikely(skb_is_gso(skb)))
	263	flush \|= (mss != skb_shinfo(skb)->gso_size);
	264	else
	265	flush \|= (len - 1) >= mss;
	266
28850dc7	267	flush \|= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
41ed9c04 BP	268	#ifdef CONFIG_TLS_DEVICE
	269	flush \|= p->decrypted ^ skb->decrypted;
	270	#endif
28850dc7	271
d4546c25	272	if (flush \|\| skb_gro_receive(p, skb)) {
28850dc7 DB	273	mss = 1;
	274	goto out_check_final;
	275	}
	276
28850dc7 DB	277	tcp_flag_word(th2) \|= flags & (TCP_FLAG_FIN \| TCP_FLAG_PSH);
	278
	279	out_check_final:
5eddb249 CL	280	/* Force a flush if last segment is smaller than mss. */
	281	if (unlikely(skb_is_gso(skb)))
	282	flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
	283	else
	284	flush = len < mss;
	285
28850dc7 DB	286	flush \|= (__force int)(flags & (TCP_FLAG_URG \| TCP_FLAG_PSH \|
	287	TCP_FLAG_RST \| TCP_FLAG_SYN \|
	288	TCP_FLAG_FIN));
	289
	290	if (p && (!NAPI_GRO_CB(skb)->same_flow \|\| flush))
d4546c25	291	pp = p;
28850dc7 DB	292
28850dc7 DB	293	out:
bf5a755f	294	NAPI_GRO_CB(skb)->flush \|= (flush != 0);
28850dc7 DB	295
	296	return pp;
	297	}
28850dc7 DB	298
	299	int tcp_gro_complete(struct sk_buff *skb)
	300	{
	301	struct tcphdr *th = tcp_hdr(skb);
	302
299603e8	303	skb->csum_start = (unsigned char *)th - skb->head;
28850dc7 DB	304	skb->csum_offset = offsetof(struct tcphdr, check);
	305	skb->ip_summed = CHECKSUM_PARTIAL;
	306
	307	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
	308
	309	if (th->cwr)
	310	skb_shinfo(skb)->gso_type \|= SKB_GSO_TCP_ECN;
	311
d51c5907 JS	312	if (skb->encapsulation)
	313	skb->inner_transport_header = skb->transport_header;
	314
28850dc7 DB	315	return 0;
	316	}
	317	EXPORT_SYMBOL(tcp_gro_complete);
	318
028e0a47 PA	319	INDIRECT_CALLABLE_SCOPE
028e0a47 PA	320	struct sk_buff tcp4_gro_receive(struct list_head head, struct sk_buff *skb)
28850dc7	321	{
cc5c00bb	322	/* Don't bother verifying checksum if we're going to flush anyway. */
149d0774 TH	323	if (!NAPI_GRO_CB(skb)->flush &&
	324	skb_gro_checksum_validate(skb, IPPROTO_TCP,
	325	inet_gro_compute_pseudo)) {
28850dc7 DB	326	NAPI_GRO_CB(skb)->flush = 1;
28850dc7 DB	327	return NULL;
28850dc7 DB	328	}
	329
	330	return tcp_gro_receive(head, skb);
	331	}
	332
028e0a47	333	INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
28850dc7 DB	334	{
	335	const struct iphdr *iph = ip_hdr(skb);
	336	struct tcphdr *th = tcp_hdr(skb);
	337
299603e8 JC	338	th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
299603e8 JC	339	iph->daddr, 0);
c3caf119	340	skb_shinfo(skb)->gso_type \|= SKB_GSO_TCPV4;
28850dc7	341
1530545e AD	342	if (NAPI_GRO_CB(skb)->is_atomic)
	343	skb_shinfo(skb)->gso_type \|= SKB_GSO_TCP_FIXEDID;
	344
28850dc7 DB	345	return tcp_gro_complete(skb);
	346	}
	347
	348	static const struct net_offload tcpv4_offload = {
	349	.callbacks = {
d020f8f7	350	.gso_segment = tcp4_gso_segment,
28850dc7 DB	351	.gro_receive = tcp4_gro_receive,
	352	.gro_complete = tcp4_gro_complete,
	353	},
	354	};
	355
	356	int __init tcpv4_offload_init(void)
	357	{
	358	return inet_add_offload(&tcpv4_offload, IPPROTO_TCP);
	359	}