1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IPV4 GSO/GRO offload support
4 * Linux INET implementation
5 *
6 * TCPv4 GSO/GRO support
7 */
8
9 #include <linux/indirect_call_wrapper.h>
10 #include <linux/skbuff.h>
11 #include <net/gro.h>
12 #include <net/gso.h>
13 #include <net/tcp.h>
14 #include <net/protocol.h>
15
tcp_gso_tstamp(struct sk_buff * skb,unsigned int ts_seq,unsigned int seq,unsigned int mss)16 static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
17 unsigned int seq, unsigned int mss)
18 {
19 while (skb) {
20 if (before(ts_seq, seq + mss)) {
21 skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
22 skb_shinfo(skb)->tskey = ts_seq;
23 return;
24 }
25
26 skb = skb->next;
27 seq += mss;
28 }
29 }
30
__tcpv4_gso_segment_csum(struct sk_buff * seg,__be32 * oldip,__be32 newip,__be16 * oldport,__be16 newport)31 static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
32 __be32 *oldip, __be32 newip,
33 __be16 *oldport, __be16 newport)
34 {
35 struct tcphdr *th;
36 struct iphdr *iph;
37
38 if (*oldip == newip && *oldport == newport)
39 return;
40
41 th = tcp_hdr(seg);
42 iph = ip_hdr(seg);
43
44 inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
45 inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
46 *oldport = newport;
47
48 csum_replace4(&iph->check, *oldip, newip);
49 *oldip = newip;
50 }
51
__tcpv4_gso_segment_list_csum(struct sk_buff * segs)52 static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
53 {
54 const struct tcphdr *th;
55 const struct iphdr *iph;
56 struct sk_buff *seg;
57 struct tcphdr *th2;
58 struct iphdr *iph2;
59
60 seg = segs;
61 th = tcp_hdr(seg);
62 iph = ip_hdr(seg);
63 th2 = tcp_hdr(seg->next);
64 iph2 = ip_hdr(seg->next);
65
66 if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
67 iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
68 return segs;
69
70 while ((seg = seg->next)) {
71 th2 = tcp_hdr(seg);
72 iph2 = ip_hdr(seg);
73
74 __tcpv4_gso_segment_csum(seg,
75 &iph2->saddr, iph->saddr,
76 &th2->source, th->source);
77 __tcpv4_gso_segment_csum(seg,
78 &iph2->daddr, iph->daddr,
79 &th2->dest, th->dest);
80 }
81
82 return segs;
83 }
84
__tcp4_gso_segment_list(struct sk_buff * skb,netdev_features_t features)85 static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
86 netdev_features_t features)
87 {
88 skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
89 if (IS_ERR(skb))
90 return skb;
91
92 return __tcpv4_gso_segment_list_csum(skb);
93 }
94
tcp4_gso_segment(struct sk_buff * skb,netdev_features_t features)95 static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
96 netdev_features_t features)
97 {
98 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
99 return ERR_PTR(-EINVAL);
100
101 if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
102 return ERR_PTR(-EINVAL);
103
104 if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
105 return __tcp4_gso_segment_list(skb, features);
106
107 if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
108 const struct iphdr *iph = ip_hdr(skb);
109 struct tcphdr *th = tcp_hdr(skb);
110
111 /* Set up checksum pseudo header, usually expect stack to
112 * have done this already.
113 */
114
115 th->check = 0;
116 skb->ip_summed = CHECKSUM_PARTIAL;
117 __tcp_v4_send_check(skb, iph->saddr, iph->daddr);
118 }
119
120 return tcp_gso_segment(skb, features);
121 }
122
tcp_gso_segment(struct sk_buff * skb,netdev_features_t features)123 struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
124 netdev_features_t features)
125 {
126 struct sk_buff *segs = ERR_PTR(-EINVAL);
127 unsigned int sum_truesize = 0;
128 struct tcphdr *th;
129 unsigned int thlen;
130 unsigned int seq;
131 unsigned int oldlen;
132 unsigned int mss;
133 struct sk_buff *gso_skb = skb;
134 __sum16 newcheck;
135 bool ooo_okay, copy_destructor;
136 __wsum delta;
137
138 th = tcp_hdr(skb);
139 thlen = th->doff * 4;
140 if (thlen < sizeof(*th))
141 goto out;
142
143 if (unlikely(skb_checksum_start(skb) != skb_transport_header(skb)))
144 goto out;
145
146 if (!pskb_may_pull(skb, thlen))
147 goto out;
148
149 oldlen = ~skb->len;
150 __skb_pull(skb, thlen);
151
152 mss = skb_shinfo(skb)->gso_size;
153 if (unlikely(skb->len <= mss))
154 goto out;
155
156 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
157 /* Packet is from an untrusted source, reset gso_segs. */
158
159 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
160
161 segs = NULL;
162 goto out;
163 }
164
165 copy_destructor = gso_skb->destructor == tcp_wfree;
166 ooo_okay = gso_skb->ooo_okay;
167 /* All segments but the first should have ooo_okay cleared */
168 skb->ooo_okay = 0;
169
170 segs = skb_segment(skb, features);
171 if (IS_ERR(segs))
172 goto out;
173
174 /* Only first segment might have ooo_okay set */
175 segs->ooo_okay = ooo_okay;
176
177 /* GSO partial and frag_list segmentation only requires splitting
178 * the frame into an MSS multiple and possibly a remainder, both
179 * cases return a GSO skb. So update the mss now.
180 */
181 if (skb_is_gso(segs))
182 mss *= skb_shinfo(segs)->gso_segs;
183
184 delta = (__force __wsum)htonl(oldlen + thlen + mss);
185
186 skb = segs;
187 th = tcp_hdr(skb);
188 seq = ntohl(th->seq);
189
190 if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
191 tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
192
193 newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta));
194
195 while (skb->next) {
196 th->fin = th->psh = 0;
197 th->check = newcheck;
198
199 if (skb->ip_summed == CHECKSUM_PARTIAL)
200 gso_reset_checksum(skb, ~th->check);
201 else
202 th->check = gso_make_checksum(skb, ~th->check);
203
204 seq += mss;
205 if (copy_destructor) {
206 skb->destructor = gso_skb->destructor;
207 skb->sk = gso_skb->sk;
208 sum_truesize += skb->truesize;
209 }
210 skb = skb->next;
211 th = tcp_hdr(skb);
212
213 th->seq = htonl(seq);
214 th->cwr = 0;
215 }
216
217 /* Following permits TCP Small Queues to work well with GSO :
218 * The callback to TCP stack will be called at the time last frag
219 * is freed at TX completion, and not right now when gso_skb
220 * is freed by GSO engine
221 */
222 if (copy_destructor) {
223 int delta;
224
225 swap(gso_skb->sk, skb->sk);
226 swap(gso_skb->destructor, skb->destructor);
227 sum_truesize += skb->truesize;
228 delta = sum_truesize - gso_skb->truesize;
229 /* In some pathological cases, delta can be negative.
230 * We need to either use refcount_add() or refcount_sub_and_test()
231 */
232 if (likely(delta >= 0))
233 refcount_add(delta, &skb->sk->sk_wmem_alloc);
234 else
235 WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
236 }
237
238 delta = (__force __wsum)htonl(oldlen +
239 (skb_tail_pointer(skb) -
240 skb_transport_header(skb)) +
241 skb->data_len);
242 th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta));
243 if (skb->ip_summed == CHECKSUM_PARTIAL)
244 gso_reset_checksum(skb, ~th->check);
245 else
246 th->check = gso_make_checksum(skb, ~th->check);
247 out:
248 return segs;
249 }
250
tcp_gro_lookup(struct list_head * head,struct tcphdr * th)251 struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
252 {
253 struct tcphdr *th2;
254 struct sk_buff *p;
255
256 list_for_each_entry(p, head, list) {
257 if (!NAPI_GRO_CB(p)->same_flow)
258 continue;
259
260 th2 = tcp_hdr(p);
261 if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
262 NAPI_GRO_CB(p)->same_flow = 0;
263 continue;
264 }
265
266 return p;
267 }
268
269 return NULL;
270 }
271
tcp_gro_pull_header(struct sk_buff * skb)272 struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb)
273 {
274 unsigned int thlen, hlen, off;
275 struct tcphdr *th;
276
277 off = skb_gro_offset(skb);
278 hlen = off + sizeof(*th);
279 th = skb_gro_header(skb, hlen, off);
280 if (unlikely(!th))
281 return NULL;
282
283 thlen = th->doff * 4;
284 if (thlen < sizeof(*th))
285 return NULL;
286
287 hlen = off + thlen;
288 if (!skb_gro_may_pull(skb, hlen)) {
289 th = skb_gro_header_slow(skb, hlen, off);
290 if (unlikely(!th))
291 return NULL;
292 }
293
294 skb_gro_pull(skb, thlen);
295
296 return th;
297 }
298
tcp_gro_receive(struct list_head * head,struct sk_buff * skb,struct tcphdr * th)299 struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
300 struct tcphdr *th)
301 {
302 unsigned int thlen = th->doff * 4;
303 struct sk_buff *pp = NULL;
304 struct sk_buff *p;
305 struct tcphdr *th2;
306 unsigned int len;
307 __be32 flags;
308 unsigned int mss = 1;
309 int flush = 1;
310 int i;
311
312 len = skb_gro_len(skb);
313 flags = tcp_flag_word(th);
314
315 p = tcp_gro_lookup(head, th);
316 if (!p)
317 goto out_check_final;
318
319 th2 = tcp_hdr(p);
320 flush = (__force int)(flags & TCP_FLAG_CWR);
321 flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
322 ~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
323 flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
324 for (i = sizeof(*th); i < thlen; i += 4)
325 flush |= *(u32 *)((u8 *)th + i) ^
326 *(u32 *)((u8 *)th2 + i);
327
328 flush |= gro_receive_network_flush(th, th2, p);
329
330 mss = skb_shinfo(p)->gso_size;
331
332 /* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
333 * If it is a single frame, do not aggregate it if its length
334 * is bigger than our mss.
335 */
336 if (unlikely(skb_is_gso(skb)))
337 flush |= (mss != skb_shinfo(skb)->gso_size);
338 else
339 flush |= (len - 1) >= mss;
340
341 flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
342 flush |= skb_cmp_decrypted(p, skb);
343
344 if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
345 flush |= (__force int)(flags ^ tcp_flag_word(th2));
346 flush |= skb->ip_summed != p->ip_summed;
347 flush |= skb->csum_level != p->csum_level;
348 flush |= NAPI_GRO_CB(p)->count >= 64;
349
350 if (flush || skb_gro_receive_list(p, skb))
351 mss = 1;
352
353 goto out_check_final;
354 }
355
356 if (flush || skb_gro_receive(p, skb)) {
357 mss = 1;
358 goto out_check_final;
359 }
360
361 tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
362
363 out_check_final:
364 /* Force a flush if last segment is smaller than mss. */
365 if (unlikely(skb_is_gso(skb)))
366 flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
367 else
368 flush = len < mss;
369
370 flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
371 TCP_FLAG_RST | TCP_FLAG_SYN |
372 TCP_FLAG_FIN));
373
374 if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
375 pp = p;
376
377 NAPI_GRO_CB(skb)->flush |= (flush != 0);
378
379 return pp;
380 }
381
tcp_gro_complete(struct sk_buff * skb)382 void tcp_gro_complete(struct sk_buff *skb)
383 {
384 struct tcphdr *th = tcp_hdr(skb);
385 struct skb_shared_info *shinfo;
386
387 if (skb->encapsulation)
388 skb->inner_transport_header = skb->transport_header;
389
390 skb->csum_start = (unsigned char *)th - skb->head;
391 skb->csum_offset = offsetof(struct tcphdr, check);
392 skb->ip_summed = CHECKSUM_PARTIAL;
393
394 shinfo = skb_shinfo(skb);
395 shinfo->gso_segs = NAPI_GRO_CB(skb)->count;
396
397 if (th->cwr)
398 shinfo->gso_type |= SKB_GSO_TCP_ECN;
399 }
400 EXPORT_SYMBOL(tcp_gro_complete);
401
tcp4_check_fraglist_gro(struct list_head * head,struct sk_buff * skb,struct tcphdr * th)402 static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
403 struct tcphdr *th)
404 {
405 const struct iphdr *iph;
406 struct sk_buff *p;
407 struct sock *sk;
408 struct net *net;
409 int iif, sdif;
410
411 if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
412 return;
413
414 p = tcp_gro_lookup(head, th);
415 if (p) {
416 NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
417 return;
418 }
419
420 inet_get_iif_sdif(skb, &iif, &sdif);
421 iph = skb_gro_network_header(skb);
422 net = dev_net(skb->dev);
423 sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
424 iph->saddr, th->source,
425 iph->daddr, ntohs(th->dest),
426 iif, sdif);
427 NAPI_GRO_CB(skb)->is_flist = !sk;
428 if (sk)
429 sock_put(sk);
430 }
431
432 INDIRECT_CALLABLE_SCOPE
tcp4_gro_receive(struct list_head * head,struct sk_buff * skb)433 struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
434 {
435 struct tcphdr *th;
436
437 /* Don't bother verifying checksum if we're going to flush anyway. */
438 if (!NAPI_GRO_CB(skb)->flush &&
439 skb_gro_checksum_validate(skb, IPPROTO_TCP,
440 inet_gro_compute_pseudo))
441 goto flush;
442
443 th = tcp_gro_pull_header(skb);
444 if (!th)
445 goto flush;
446
447 tcp4_check_fraglist_gro(head, skb, th);
448
449 return tcp_gro_receive(head, skb, th);
450
451 flush:
452 NAPI_GRO_CB(skb)->flush = 1;
453 return NULL;
454 }
455
tcp4_gro_complete(struct sk_buff * skb,int thoff)456 INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
457 {
458 const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
459 const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
460 struct tcphdr *th = tcp_hdr(skb);
461
462 if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
463 skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
464 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
465
466 __skb_incr_checksum_unnecessary(skb);
467
468 return 0;
469 }
470
471 th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
472 iph->daddr, 0);
473
474 skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
475 (NAPI_GRO_CB(skb)->ip_fixedid * SKB_GSO_TCP_FIXEDID);
476
477 tcp_gro_complete(skb);
478 return 0;
479 }
480
tcpv4_offload_init(void)481 int __init tcpv4_offload_init(void)
482 {
483 net_hotdata.tcpv4_offload = (struct net_offload) {
484 .callbacks = {
485 .gso_segment = tcp4_gso_segment,
486 .gro_receive = tcp4_gro_receive,
487 .gro_complete = tcp4_gro_complete,
488 },
489 };
490 return inet_add_offload(&net_hotdata.tcpv4_offload, IPPROTO_TCP);
491 }
492