FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_lro.c
1 /*-
2 * Copyright (c) 2007, Myricom Inc.
3 * Copyright (c) 2008, Intel Corporation.
4 * Copyright (c) 2012 The FreeBSD Foundation
5 * All rights reserved.
6 *
7 * Portions of this software were developed by Bjoern Zeeb
8 * under sponsorship from the FreeBSD Foundation.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include "opt_inet.h"
36 #include "opt_inet6.h"
37
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/mbuf.h>
41 #include <sys/kernel.h>
42 #include <sys/socket.h>
43
44 #include <net/if.h>
45 #include <net/if_var.h>
46 #include <net/ethernet.h>
47 #include <net/vnet.h>
48
49 #include <netinet/in_systm.h>
50 #include <netinet/in.h>
51 #include <netinet/ip6.h>
52 #include <netinet/ip.h>
53 #include <netinet/ip_var.h>
54 #include <netinet/tcp.h>
55 #include <netinet/tcp_lro.h>
56
57 #include <netinet6/ip6_var.h>
58
59 #include <machine/in_cksum.h>
60
61 #ifndef LRO_ENTRIES
62 #define LRO_ENTRIES 8 /* # of LRO entries per RX queue. */
63 #endif
64
65 #define TCP_LRO_UPDATE_CSUM 1
66 #ifndef TCP_LRO_UPDATE_CSUM
67 #define TCP_LRO_INVALID_CSUM 0x0000
68 #endif
69
70 int
71 tcp_lro_init(struct lro_ctrl *lc)
72 {
73 struct lro_entry *le;
74 int error, i;
75
76 lc->lro_bad_csum = 0;
77 lc->lro_queued = 0;
78 lc->lro_flushed = 0;
79 lc->lro_cnt = 0;
80 SLIST_INIT(&lc->lro_free);
81 SLIST_INIT(&lc->lro_active);
82
83 error = 0;
84 for (i = 0; i < LRO_ENTRIES; i++) {
85 le = (struct lro_entry *)malloc(sizeof(*le), M_DEVBUF,
86 M_NOWAIT | M_ZERO);
87 if (le == NULL) {
88 if (i == 0)
89 error = ENOMEM;
90 break;
91 }
92 lc->lro_cnt = i + 1;
93 SLIST_INSERT_HEAD(&lc->lro_free, le, next);
94 }
95
96 return (error);
97 }
98
99 void
100 tcp_lro_free(struct lro_ctrl *lc)
101 {
102 struct lro_entry *le;
103
104 while (!SLIST_EMPTY(&lc->lro_free)) {
105 le = SLIST_FIRST(&lc->lro_free);
106 SLIST_REMOVE_HEAD(&lc->lro_free, next);
107 free(le, M_DEVBUF);
108 }
109 }
110
111 #ifdef TCP_LRO_UPDATE_CSUM
112 static uint16_t
113 tcp_lro_csum_th(struct tcphdr *th)
114 {
115 uint32_t ch;
116 uint16_t *p, l;
117
118 ch = th->th_sum = 0x0000;
119 l = th->th_off;
120 p = (uint16_t *)th;
121 while (l > 0) {
122 ch += *p;
123 p++;
124 ch += *p;
125 p++;
126 l--;
127 }
128 while (ch > 0xffff)
129 ch = (ch >> 16) + (ch & 0xffff);
130
131 return (ch & 0xffff);
132 }
133
134 static uint16_t
135 tcp_lro_rx_csum_fixup(struct lro_entry *le, void *l3hdr, struct tcphdr *th,
136 uint16_t tcp_data_len, uint16_t csum)
137 {
138 uint32_t c;
139 uint16_t cs;
140
141 c = csum;
142
143 /* Remove length from checksum. */
144 switch (le->eh_type) {
145 #ifdef INET6
146 case ETHERTYPE_IPV6:
147 {
148 struct ip6_hdr *ip6;
149
150 ip6 = (struct ip6_hdr *)l3hdr;
151 if (le->append_cnt == 0)
152 cs = ip6->ip6_plen;
153 else {
154 uint32_t cx;
155
156 cx = ntohs(ip6->ip6_plen);
157 cs = in6_cksum_pseudo(ip6, cx, ip6->ip6_nxt, 0);
158 }
159 break;
160 }
161 #endif
162 #ifdef INET
163 case ETHERTYPE_IP:
164 {
165 struct ip *ip4;
166
167 ip4 = (struct ip *)l3hdr;
168 if (le->append_cnt == 0)
169 cs = ip4->ip_len;
170 else {
171 cs = in_addword(ntohs(ip4->ip_len) - sizeof(*ip4),
172 IPPROTO_TCP);
173 cs = in_pseudo(ip4->ip_src.s_addr, ip4->ip_dst.s_addr,
174 htons(cs));
175 }
176 break;
177 }
178 #endif
179 default:
180 cs = 0; /* Keep compiler happy. */
181 }
182
183 cs = ~cs;
184 c += cs;
185
186 /* Remove TCP header csum. */
187 cs = ~tcp_lro_csum_th(th);
188 c += cs;
189 while (c > 0xffff)
190 c = (c >> 16) + (c & 0xffff);
191
192 return (c & 0xffff);
193 }
194 #endif
195
196 void
197 tcp_lro_flush(struct lro_ctrl *lc, struct lro_entry *le)
198 {
199
200 if (le->append_cnt > 0) {
201 struct tcphdr *th;
202 uint16_t p_len;
203
204 p_len = htons(le->p_len);
205 switch (le->eh_type) {
206 #ifdef INET6
207 case ETHERTYPE_IPV6:
208 {
209 struct ip6_hdr *ip6;
210
211 ip6 = le->le_ip6;
212 ip6->ip6_plen = p_len;
213 th = (struct tcphdr *)(ip6 + 1);
214 le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
215 CSUM_PSEUDO_HDR;
216 le->p_len += ETHER_HDR_LEN + sizeof(*ip6);
217 break;
218 }
219 #endif
220 #ifdef INET
221 case ETHERTYPE_IP:
222 {
223 struct ip *ip4;
224 #ifdef TCP_LRO_UPDATE_CSUM
225 uint32_t cl;
226 uint16_t c;
227 #endif
228
229 ip4 = le->le_ip4;
230 #ifdef TCP_LRO_UPDATE_CSUM
231 /* Fix IP header checksum for new length. */
232 c = ~ip4->ip_sum;
233 cl = c;
234 c = ~ip4->ip_len;
235 cl += c + p_len;
236 while (cl > 0xffff)
237 cl = (cl >> 16) + (cl & 0xffff);
238 c = cl;
239 ip4->ip_sum = ~c;
240 #else
241 ip4->ip_sum = TCP_LRO_INVALID_CSUM;
242 #endif
243 ip4->ip_len = p_len;
244 th = (struct tcphdr *)(ip4 + 1);
245 le->m_head->m_pkthdr.csum_flags = CSUM_DATA_VALID |
246 CSUM_PSEUDO_HDR | CSUM_IP_CHECKED | CSUM_IP_VALID;
247 le->p_len += ETHER_HDR_LEN;
248 break;
249 }
250 #endif
251 default:
252 th = NULL; /* Keep compiler happy. */
253 }
254 le->m_head->m_pkthdr.csum_data = 0xffff;
255 le->m_head->m_pkthdr.len = le->p_len;
256
257 /* Incorporate the latest ACK into the TCP header. */
258 th->th_ack = le->ack_seq;
259 th->th_win = le->window;
260 /* Incorporate latest timestamp into the TCP header. */
261 if (le->timestamp != 0) {
262 uint32_t *ts_ptr;
263
264 ts_ptr = (uint32_t *)(th + 1);
265 ts_ptr[1] = htonl(le->tsval);
266 ts_ptr[2] = le->tsecr;
267 }
268 #ifdef TCP_LRO_UPDATE_CSUM
269 /* Update the TCP header checksum. */
270 le->ulp_csum += p_len;
271 le->ulp_csum += tcp_lro_csum_th(th);
272 while (le->ulp_csum > 0xffff)
273 le->ulp_csum = (le->ulp_csum >> 16) +
274 (le->ulp_csum & 0xffff);
275 th->th_sum = (le->ulp_csum & 0xffff);
276 th->th_sum = ~th->th_sum;
277 #else
278 th->th_sum = TCP_LRO_INVALID_CSUM;
279 #endif
280 }
281
282 (*lc->ifp->if_input)(lc->ifp, le->m_head);
283 lc->lro_queued += le->append_cnt + 1;
284 lc->lro_flushed++;
285 bzero(le, sizeof(*le));
286 SLIST_INSERT_HEAD(&lc->lro_free, le, next);
287 }
288
289 #ifdef INET6
290 static int
291 tcp_lro_rx_ipv6(struct lro_ctrl *lc, struct mbuf *m, struct ip6_hdr *ip6,
292 struct tcphdr **th)
293 {
294
295 /* XXX-BZ we should check the flow-label. */
296
297 /* XXX-BZ We do not yet support ext. hdrs. */
298 if (ip6->ip6_nxt != IPPROTO_TCP)
299 return (TCP_LRO_NOT_SUPPORTED);
300
301 /* Find the TCP header. */
302 *th = (struct tcphdr *)(ip6 + 1);
303
304 return (0);
305 }
306 #endif
307
308 #ifdef INET
309 static int
310 tcp_lro_rx_ipv4(struct lro_ctrl *lc, struct mbuf *m, struct ip *ip4,
311 struct tcphdr **th)
312 {
313 int csum_flags;
314 uint16_t csum;
315
316 if (ip4->ip_p != IPPROTO_TCP)
317 return (TCP_LRO_NOT_SUPPORTED);
318
319 /* Ensure there are no options. */
320 if ((ip4->ip_hl << 2) != sizeof (*ip4))
321 return (TCP_LRO_CANNOT);
322
323 /* .. and the packet is not fragmented. */
324 if (ip4->ip_off & htons(IP_MF|IP_OFFMASK))
325 return (TCP_LRO_CANNOT);
326
327 /* Legacy IP has a header checksum that needs to be correct. */
328 csum_flags = m->m_pkthdr.csum_flags;
329 if (csum_flags & CSUM_IP_CHECKED) {
330 if (__predict_false((csum_flags & CSUM_IP_VALID) == 0)) {
331 lc->lro_bad_csum++;
332 return (TCP_LRO_CANNOT);
333 }
334 } else {
335 csum = in_cksum_hdr(ip4);
336 if (__predict_false((csum) != 0)) {
337 lc->lro_bad_csum++;
338 return (TCP_LRO_CANNOT);
339 }
340 }
341
342 /* Find the TCP header (we assured there are no IP options). */
343 *th = (struct tcphdr *)(ip4 + 1);
344
345 return (0);
346 }
347 #endif
348
349 int
350 tcp_lro_rx(struct lro_ctrl *lc, struct mbuf *m, uint32_t csum)
351 {
352 struct lro_entry *le;
353 struct ether_header *eh;
354 #ifdef INET6
355 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */
356 #endif
357 #ifdef INET
358 struct ip *ip4 = NULL; /* Keep compiler happy. */
359 #endif
360 struct tcphdr *th;
361 void *l3hdr = NULL; /* Keep compiler happy. */
362 uint32_t *ts_ptr;
363 tcp_seq seq;
364 int error, ip_len, l;
365 uint16_t eh_type, tcp_data_len;
366
367 /* We expect a contiguous header [eh, ip, tcp]. */
368
369 eh = mtod(m, struct ether_header *);
370 eh_type = ntohs(eh->ether_type);
371 switch (eh_type) {
372 #ifdef INET6
373 case ETHERTYPE_IPV6:
374 {
375 CURVNET_SET(lc->ifp->if_vnet);
376 if (V_ip6_forwarding != 0) {
377 /* XXX-BZ stats but changing lro_ctrl is a problem. */
378 CURVNET_RESTORE();
379 return (TCP_LRO_CANNOT);
380 }
381 CURVNET_RESTORE();
382 l3hdr = ip6 = (struct ip6_hdr *)(eh + 1);
383 error = tcp_lro_rx_ipv6(lc, m, ip6, &th);
384 if (error != 0)
385 return (error);
386 tcp_data_len = ntohs(ip6->ip6_plen);
387 ip_len = sizeof(*ip6) + tcp_data_len;
388 break;
389 }
390 #endif
391 #ifdef INET
392 case ETHERTYPE_IP:
393 {
394 CURVNET_SET(lc->ifp->if_vnet);
395 if (V_ipforwarding != 0) {
396 /* XXX-BZ stats but changing lro_ctrl is a problem. */
397 CURVNET_RESTORE();
398 return (TCP_LRO_CANNOT);
399 }
400 CURVNET_RESTORE();
401 l3hdr = ip4 = (struct ip *)(eh + 1);
402 error = tcp_lro_rx_ipv4(lc, m, ip4, &th);
403 if (error != 0)
404 return (error);
405 ip_len = ntohs(ip4->ip_len);
406 tcp_data_len = ip_len - sizeof(*ip4);
407 break;
408 }
409 #endif
410 /* XXX-BZ what happens in case of VLAN(s)? */
411 default:
412 return (TCP_LRO_NOT_SUPPORTED);
413 }
414
415 /*
416 * If the frame is padded beyond the end of the IP packet, then we must
417 * trim the extra bytes off.
418 */
419 l = m->m_pkthdr.len - (ETHER_HDR_LEN + ip_len);
420 if (l != 0) {
421 if (l < 0)
422 /* Truncated packet. */
423 return (TCP_LRO_CANNOT);
424
425 m_adj(m, -l);
426 }
427
428 /*
429 * Check TCP header constraints.
430 */
431 /* Ensure no bits set besides ACK or PSH. */
432 if ((th->th_flags & ~(TH_ACK | TH_PUSH)) != 0)
433 return (TCP_LRO_CANNOT);
434
435 /* XXX-BZ We lose a AKC|PUSH flag concatinating multiple segments. */
436 /* XXX-BZ Ideally we'd flush on PUSH? */
437
438 /*
439 * Check for timestamps.
440 * Since the only option we handle are timestamps, we only have to
441 * handle the simple case of aligned timestamps.
442 */
443 l = (th->th_off << 2);
444 tcp_data_len -= l;
445 l -= sizeof(*th);
446 ts_ptr = (uint32_t *)(th + 1);
447 if (l != 0 && (__predict_false(l != TCPOLEN_TSTAMP_APPA) ||
448 (*ts_ptr != ntohl(TCPOPT_NOP<<24|TCPOPT_NOP<<16|
449 TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP))))
450 return (TCP_LRO_CANNOT);
451
452 /* If the driver did not pass in the checksum, set it now. */
453 if (csum == 0x0000)
454 csum = th->th_sum;
455
456 seq = ntohl(th->th_seq);
457
458 /* Try to find a matching previous segment. */
459 SLIST_FOREACH(le, &lc->lro_active, next) {
460 if (le->eh_type != eh_type)
461 continue;
462 if (le->source_port != th->th_sport ||
463 le->dest_port != th->th_dport)
464 continue;
465 switch (eh_type) {
466 #ifdef INET6
467 case ETHERTYPE_IPV6:
468 if (bcmp(&le->source_ip6, &ip6->ip6_src,
469 sizeof(struct in6_addr)) != 0 ||
470 bcmp(&le->dest_ip6, &ip6->ip6_dst,
471 sizeof(struct in6_addr)) != 0)
472 continue;
473 break;
474 #endif
475 #ifdef INET
476 case ETHERTYPE_IP:
477 if (le->source_ip4 != ip4->ip_src.s_addr ||
478 le->dest_ip4 != ip4->ip_dst.s_addr)
479 continue;
480 break;
481 #endif
482 }
483
484 /* Flush now if appending will result in overflow. */
485 if (le->p_len > (65535 - tcp_data_len)) {
486 SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
487 tcp_lro_flush(lc, le);
488 break;
489 }
490
491 /* Try to append the new segment. */
492 if (__predict_false(seq != le->next_seq ||
493 (tcp_data_len == 0 && le->ack_seq == th->th_ack))) {
494 /* Out of order packet or duplicate ACK. */
495 SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
496 tcp_lro_flush(lc, le);
497 return (TCP_LRO_CANNOT);
498 }
499
500 if (l != 0) {
501 uint32_t tsval = ntohl(*(ts_ptr + 1));
502 /* Make sure timestamp values are increasing. */
503 /* XXX-BZ flip and use TSTMP_GEQ macro for this? */
504 if (__predict_false(le->tsval > tsval ||
505 *(ts_ptr + 2) == 0))
506 return (TCP_LRO_CANNOT);
507 le->tsval = tsval;
508 le->tsecr = *(ts_ptr + 2);
509 }
510
511 le->next_seq += tcp_data_len;
512 le->ack_seq = th->th_ack;
513 le->window = th->th_win;
514 le->append_cnt++;
515
516 #ifdef TCP_LRO_UPDATE_CSUM
517 le->ulp_csum += tcp_lro_rx_csum_fixup(le, l3hdr, th,
518 tcp_data_len, ~csum);
519 #endif
520
521 if (tcp_data_len == 0) {
522 m_freem(m);
523 return (0);
524 }
525
526 le->p_len += tcp_data_len;
527
528 /*
529 * Adjust the mbuf so that m_data points to the first byte of
530 * the ULP payload. Adjust the mbuf to avoid complications and
531 * append new segment to existing mbuf chain.
532 */
533 m_adj(m, m->m_pkthdr.len - tcp_data_len);
534 m->m_flags &= ~M_PKTHDR;
535
536 le->m_tail->m_next = m;
537 le->m_tail = m_last(m);
538
539 /*
540 * If a possible next full length packet would cause an
541 * overflow, pro-actively flush now.
542 */
543 if (le->p_len > (65535 - lc->ifp->if_mtu)) {
544 SLIST_REMOVE(&lc->lro_active, le, lro_entry, next);
545 tcp_lro_flush(lc, le);
546 }
547
548 return (0);
549 }
550
551 /* Try to find an empty slot. */
552 if (SLIST_EMPTY(&lc->lro_free))
553 return (TCP_LRO_CANNOT);
554
555 /* Start a new segment chain. */
556 le = SLIST_FIRST(&lc->lro_free);
557 SLIST_REMOVE_HEAD(&lc->lro_free, next);
558 SLIST_INSERT_HEAD(&lc->lro_active, le, next);
559
560 /* Start filling in details. */
561 switch (eh_type) {
562 #ifdef INET6
563 case ETHERTYPE_IPV6:
564 le->le_ip6 = ip6;
565 le->source_ip6 = ip6->ip6_src;
566 le->dest_ip6 = ip6->ip6_dst;
567 le->eh_type = eh_type;
568 le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN - sizeof(*ip6);
569 break;
570 #endif
571 #ifdef INET
572 case ETHERTYPE_IP:
573 le->le_ip4 = ip4;
574 le->source_ip4 = ip4->ip_src.s_addr;
575 le->dest_ip4 = ip4->ip_dst.s_addr;
576 le->eh_type = eh_type;
577 le->p_len = m->m_pkthdr.len - ETHER_HDR_LEN;
578 break;
579 #endif
580 }
581 le->source_port = th->th_sport;
582 le->dest_port = th->th_dport;
583
584 le->next_seq = seq + tcp_data_len;
585 le->ack_seq = th->th_ack;
586 le->window = th->th_win;
587 if (l != 0) {
588 le->timestamp = 1;
589 le->tsval = ntohl(*(ts_ptr + 1));
590 le->tsecr = *(ts_ptr + 2);
591 }
592
593 #ifdef TCP_LRO_UPDATE_CSUM
594 /*
595 * Do not touch the csum of the first packet. However save the
596 * "adjusted" checksum of just the source and destination addresses,
597 * the next header and the TCP payload. The length and TCP header
598 * parts may change, so we remove those from the saved checksum and
599 * re-add with final values on tcp_lro_flush() if needed.
600 */
601 KASSERT(le->ulp_csum == 0, ("%s: le=%p le->ulp_csum=0x%04x\n",
602 __func__, le, le->ulp_csum));
603
604 le->ulp_csum = tcp_lro_rx_csum_fixup(le, l3hdr, th, tcp_data_len,
605 ~csum);
606 th->th_sum = csum; /* Restore checksum on first packet. */
607 #endif
608
609 le->m_head = m;
610 le->m_tail = m_last(m);
611
612 return (0);
613 }
614
615 /* end */
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