Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/netinet/tcp_lro.c
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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: releng/9.2/sys/netinet/tcp_lro.c 247470 2013-02-28 16:32:36Z gallatin $"); 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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