summaryrefslogtreecommitdiff
path: root/net/ipv4/tcp_offload.c
blob: 2308665b51c5388814e5b61a262a1636d897c4a9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
// 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/gso.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 void __tcpv4_gso_segment_csum(struct sk_buff *seg,
				     __be32 *oldip, __be32 newip,
				     __be16 *oldport, __be16 newport)
{
	struct tcphdr *th;
	struct iphdr *iph;

	if (*oldip == newip && *oldport == newport)
		return;

	th = tcp_hdr(seg);
	iph = ip_hdr(seg);

	inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
	inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
	*oldport = newport;

	csum_replace4(&iph->check, *oldip, newip);
	*oldip = newip;
}

static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
{
	const struct tcphdr *th;
	const struct iphdr *iph;
	struct sk_buff *seg;
	struct tcphdr *th2;
	struct iphdr *iph2;

	seg = segs;
	th = tcp_hdr(seg);
	iph = ip_hdr(seg);
	th2 = tcp_hdr(seg->next);
	iph2 = ip_hdr(seg->next);

	if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
	    iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
		return segs;

	while ((seg = seg->next)) {
		th2 = tcp_hdr(seg);
		iph2 = ip_hdr(seg);

		__tcpv4_gso_segment_csum(seg,
					 &iph2->saddr, iph->saddr,
					 &th2->source, th->source);
		__tcpv4_gso_segment_csum(seg,
					 &iph2->daddr, iph->daddr,
					 &th2->dest, th->dest);
	}

	return segs;
}

static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
					      netdev_features_t features)
{
	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
	if (IS_ERR(skb))
		return skb;

	return __tcpv4_gso_segment_list_csum(skb);
}

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 (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST) {
		struct tcphdr *th = tcp_hdr(skb);

		if (skb_pagelen(skb) - th->doff * 4 == skb_shinfo(skb)->gso_size)
			return __tcp4_gso_segment_list(skb, features);

		skb->ip_summed = CHECKSUM_NONE;
	}

	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;
	unsigned int oldlen;
	unsigned int mss;
	struct sk_buff *gso_skb = skb;
	__sum16 newcheck;
	bool ooo_okay, copy_destructor;
	__wsum delta;

	th = tcp_hdr(skb);
	thlen = th->doff * 4;
	if (thlen < sizeof(*th))
		goto out;

	if (unlikely(skb_checksum_start(skb) != skb_transport_header(skb)))
		goto out;

	if (!pskb_may_pull(skb, thlen))
		goto out;

	oldlen = ~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 = (__force __wsum)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(csum_add(csum_unfold(th->check), 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 = (__force __wsum)htonl(oldlen +
				      (skb_tail_pointer(skb) -
				       skb_transport_header(skb)) +
				      skb->data_len);
	th->check = ~csum_fold(csum_add(csum_unfold(th->check), 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_lookup(struct list_head *head, struct tcphdr *th)
{
	struct tcphdr *th2;
	struct sk_buff *p;

	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;
		}

		return p;
	}

	return NULL;
}

struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb)
{
	unsigned int thlen, hlen, off;
	struct tcphdr *th;

	off = skb_gro_offset(skb);
	hlen = off + sizeof(*th);
	th = skb_gro_header(skb, hlen, off);
	if (unlikely(!th))
		return NULL;

	thlen = th->doff * 4;
	if (thlen < sizeof(*th))
		return NULL;

	hlen = off + thlen;
	if (!skb_gro_may_pull(skb, hlen)) {
		th = skb_gro_header_slow(skb, hlen, off);
		if (unlikely(!th))
			return NULL;
	}

	skb_gro_pull(skb, thlen);

	return th;
}

struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
				struct tcphdr *th)
{
	unsigned int thlen = th->doff * 4;
	struct sk_buff *pp = NULL;
	struct sk_buff *p;
	struct tcphdr *th2;
	unsigned int len;
	__be32 flags;
	unsigned int mss = 1;
	int flush = 1;
	int i;

	len = skb_gro_len(skb);
	flags = tcp_flag_word(th);

	p = tcp_gro_lookup(head, th);
	if (!p)
		goto out_check_final;

	th2 = tcp_hdr(p);
	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);

	flush |= gro_receive_network_flush(th, th2, p);

	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);
	flush |= skb_cmp_decrypted(p, skb);

	if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
		flush |= (__force int)(flags ^ tcp_flag_word(th2));
		flush |= skb->ip_summed != p->ip_summed;
		flush |= skb->csum_level != p->csum_level;
		flush |= NAPI_GRO_CB(p)->count >= 64;

		if (flush || skb_gro_receive_list(p, skb))
			mss = 1;

		goto out_check_final;
	}

	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;

	NAPI_GRO_CB(skb)->flush |= (flush != 0);

	return pp;
}

void tcp_gro_complete(struct sk_buff *skb)
{
	struct tcphdr *th = tcp_hdr(skb);
	struct skb_shared_info *shinfo;

	if (skb->encapsulation)
		skb->inner_transport_header = skb->transport_header;

	skb->csum_start = (unsigned char *)th - skb->head;
	skb->csum_offset = offsetof(struct tcphdr, check);
	skb->ip_summed = CHECKSUM_PARTIAL;

	shinfo = skb_shinfo(skb);
	shinfo->gso_segs = NAPI_GRO_CB(skb)->count;

	if (th->cwr)
		shinfo->gso_type |= SKB_GSO_TCP_ECN;
}
EXPORT_SYMBOL(tcp_gro_complete);

static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
				    struct tcphdr *th)
{
	const struct iphdr *iph;
	struct sk_buff *p;
	struct sock *sk;
	struct net *net;
	int iif, sdif;

	if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
		return;

	p = tcp_gro_lookup(head, th);
	if (p) {
		NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
		return;
	}

	inet_get_iif_sdif(skb, &iif, &sdif);
	iph = skb_gro_network_header(skb);
	net = dev_net(skb->dev);
	sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
				       iph->saddr, th->source,
				       iph->daddr, ntohs(th->dest),
				       iif, sdif);
	NAPI_GRO_CB(skb)->is_flist = !sk;
	if (sk)
		sock_put(sk);
}

INDIRECT_CALLABLE_SCOPE
struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
{
	struct tcphdr *th;

	/* 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))
		goto flush;

	th = tcp_gro_pull_header(skb);
	if (!th)
		goto flush;

	tcp4_check_fraglist_gro(head, skb, th);

	return tcp_gro_receive(head, skb, th);

flush:
	NAPI_GRO_CB(skb)->flush = 1;
	return NULL;
}

INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
{
	const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
	const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
	struct tcphdr *th = tcp_hdr(skb);

	if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
		skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
		skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;

		__skb_incr_checksum_unnecessary(skb);

		return 0;
	}

	th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
				  iph->daddr, 0);

	skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
			(NAPI_GRO_CB(skb)->ip_fixedid * SKB_GSO_TCP_FIXEDID);

	tcp_gro_complete(skb);
	return 0;
}

int __init tcpv4_offload_init(void)
{
	net_hotdata.tcpv4_offload = (struct net_offload) {
		.callbacks = {
			.gso_segment	=	tcp4_gso_segment,
			.gro_receive	=	tcp4_gro_receive,
			.gro_complete	=	tcp4_gro_complete,
		},
	};
	return inet_add_offload(&net_hotdata.tcpv4_offload, IPPROTO_TCP);
}