1 /*- 2 * Copyright (c) 2016-2020 Netflix, Inc. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23 * SUCH DAMAGE. 24 * 25 */ 26 /* 27 * Author: Randall Stewart <rrs@netflix.com> 28 * This work is based on the ACM Queue paper 29 * BBR - Congestion Based Congestion Control 30 * and also numerous discussions with Neal, Yuchung and Van. 31 */ 32 33 #include <sys/cdefs.h> 34 #include "opt_inet.h" 35 #include "opt_inet6.h" 36 #include "opt_ipsec.h" 37 #include "opt_ratelimit.h" 38 #include <sys/param.h> 39 #include <sys/arb.h> 40 #include <sys/module.h> 41 #include <sys/kernel.h> 42 #ifdef TCP_HHOOK 43 #include <sys/hhook.h> 44 #endif 45 #include <sys/malloc.h> 46 #include <sys/mbuf.h> 47 #include <sys/proc.h> 48 #include <sys/qmath.h> 49 #include <sys/socket.h> 50 #include <sys/socketvar.h> 51 #include <sys/sysctl.h> 52 #include <sys/systm.h> 53 #include <sys/tree.h> 54 #ifdef NETFLIX_STATS 55 #include <sys/stats.h> /* Must come after qmath.h and tree.h */ 56 #endif 57 #include <sys/refcount.h> 58 #include <sys/queue.h> 59 #include <sys/smp.h> 60 #include <sys/kthread.h> 61 #include <sys/lock.h> 62 #include <sys/mutex.h> 63 #include <sys/tim_filter.h> 64 #include <sys/time.h> 65 #include <vm/uma.h> 66 #include <sys/kern_prefetch.h> 67 68 #include <net/route.h> 69 #include <net/vnet.h> 70 #include <net/ethernet.h> 71 #include <net/bpf.h> 72 73 #define TCPSTATES /* for logging */ 74 75 #include <netinet/in.h> 76 #include <netinet/in_kdtrace.h> 77 #include <netinet/in_pcb.h> 78 #include <netinet/ip.h> 79 #include <netinet/ip_var.h> 80 #include <netinet/ip6.h> 81 #include <netinet6/in6_pcb.h> 82 #include <netinet6/ip6_var.h> 83 #include <netinet/tcp.h> 84 #include <netinet/tcp_fsm.h> 85 #include <netinet/tcp_seq.h> 86 #include <netinet/tcp_timer.h> 87 #include <netinet/tcp_var.h> 88 #include <netinet/tcpip.h> 89 #include <netinet/tcp_ecn.h> 90 #include <netinet/tcp_hpts.h> 91 #include <netinet/tcp_lro.h> 92 #include <netinet/cc/cc.h> 93 #include <netinet/tcp_log_buf.h> 94 #ifdef TCP_OFFLOAD 95 #include <netinet/tcp_offload.h> 96 #endif 97 #ifdef INET6 98 #include <netinet6/tcp6_var.h> 99 #endif 100 #include <netinet/tcp_fastopen.h> 101 102 #include <netipsec/ipsec_support.h> 103 #include <net/if.h> 104 #include <net/if_var.h> 105 #include <net/if_private.h> 106 107 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 108 #include <netipsec/ipsec.h> 109 #include <netipsec/ipsec6.h> 110 #endif /* IPSEC */ 111 112 #include <netinet/udp.h> 113 #include <netinet/udp_var.h> 114 #include <machine/in_cksum.h> 115 116 #ifdef MAC 117 #include <security/mac/mac_framework.h> 118 #endif 119 #include "rack_bbr_common.h" 120 121 /* 122 * Common TCP Functions - These are shared by borth 123 * rack and BBR. 124 */ 125 static int 126 ctf_get_enet_type(struct ifnet *ifp, struct mbuf *m) 127 { 128 struct ether_header *eh; 129 #ifdef INET6 130 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 131 #endif 132 #ifdef INET 133 struct ip *ip = NULL; /* Keep compiler happy. */ 134 #endif 135 #if defined(INET) || defined(INET6) 136 struct tcphdr *th; 137 int32_t tlen; 138 uint16_t drop_hdrlen; 139 #endif 140 uint16_t etype; 141 #ifdef INET 142 uint8_t iptos; 143 #endif 144 145 /* Is it the easy way? */ 146 if (m->m_flags & M_LRO_EHDRSTRP) 147 return (m->m_pkthdr.lro_etype); 148 /* 149 * Ok this is the old style call, the ethernet header is here. 150 * This also means no checksum or BPF were done. This 151 * can happen if the race to setup the inp fails and 152 * LRO sees no INP at packet input, but by the time 153 * we queue the packets an INP gets there. Its rare 154 * but it can occur so we will handle it. Note that 155 * this means duplicated work but with the rarity of it 156 * its not worth worrying about. 157 */ 158 /* Let the BPF see the packet */ 159 if (bpf_peers_present(ifp->if_bpf)) 160 ETHER_BPF_MTAP(ifp, m); 161 /* Now the csum */ 162 eh = mtod(m, struct ether_header *); 163 etype = ntohs(eh->ether_type); 164 m_adj(m, sizeof(*eh)); 165 switch (etype) { 166 #ifdef INET6 167 case ETHERTYPE_IPV6: 168 { 169 if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 170 m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 171 if (m == NULL) { 172 KMOD_TCPSTAT_INC(tcps_rcvshort); 173 return (-1); 174 } 175 } 176 ip6 = (struct ip6_hdr *)(eh + 1); 177 th = (struct tcphdr *)(ip6 + 1); 178 drop_hdrlen = sizeof(*ip6); 179 tlen = ntohs(ip6->ip6_plen); 180 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 181 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 182 th->th_sum = m->m_pkthdr.csum_data; 183 else 184 th->th_sum = in6_cksum_pseudo(ip6, tlen, 185 IPPROTO_TCP, 186 m->m_pkthdr.csum_data); 187 th->th_sum ^= 0xffff; 188 } else 189 th->th_sum = in6_cksum(m, IPPROTO_TCP, drop_hdrlen, tlen); 190 if (th->th_sum) { 191 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 192 m_freem(m); 193 return (-1); 194 } 195 return (etype); 196 } 197 #endif 198 #ifdef INET 199 case ETHERTYPE_IP: 200 { 201 if (m->m_len < sizeof (struct tcpiphdr)) { 202 m = m_pullup(m, sizeof (struct tcpiphdr)); 203 if (m == NULL) { 204 KMOD_TCPSTAT_INC(tcps_rcvshort); 205 return (-1); 206 } 207 } 208 ip = (struct ip *)(eh + 1); 209 th = (struct tcphdr *)(ip + 1); 210 drop_hdrlen = sizeof(*ip); 211 iptos = ip->ip_tos; 212 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 213 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 214 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 215 th->th_sum = m->m_pkthdr.csum_data; 216 else 217 th->th_sum = in_pseudo(ip->ip_src.s_addr, 218 ip->ip_dst.s_addr, 219 htonl(m->m_pkthdr.csum_data + tlen + IPPROTO_TCP)); 220 th->th_sum ^= 0xffff; 221 } else { 222 int len; 223 struct ipovly *ipov = (struct ipovly *)ip; 224 /* 225 * Checksum extended TCP header and data. 226 */ 227 len = drop_hdrlen + tlen; 228 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 229 ipov->ih_len = htons(tlen); 230 th->th_sum = in_cksum(m, len); 231 /* Reset length for SDT probes. */ 232 ip->ip_len = htons(len); 233 /* Reset TOS bits */ 234 ip->ip_tos = iptos; 235 /* Re-initialization for later version check */ 236 ip->ip_v = IPVERSION; 237 ip->ip_hl = sizeof(*ip) >> 2; 238 } 239 if (th->th_sum) { 240 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 241 m_freem(m); 242 return (-1); 243 } 244 break; 245 } 246 #endif 247 }; 248 return (etype); 249 } 250 251 /* 252 * The function ctf_process_inbound_raw() is used by 253 * transport developers to do the steps needed to 254 * support MBUF Queuing i.e. the flags in 255 * inp->inp_flags2: 256 * 257 * - INP_SUPPORTS_MBUFQ 258 * - INP_MBUF_QUEUE_READY 259 * - INP_DONT_SACK_QUEUE 260 * - INP_MBUF_ACKCMP 261 * 262 * These flags help control how LRO will deliver 263 * packets to the transport. You first set in inp_flags2 264 * the INP_SUPPORTS_MBUFQ to tell the LRO code that you 265 * will gladly take a queue of packets instead of a compressed 266 * single packet. You also set in your t_fb pointer the 267 * tfb_do_queued_segments to point to ctf_process_inbound_raw. 268 * 269 * This then gets you lists of inbound ACK's/Data instead 270 * of a condensed compressed ACK/DATA packet. Why would you 271 * want that? This will get you access to all the arrival 272 * times of at least LRO and possibly at the Hardware (if 273 * the interface card supports that) of the actual ACK/DATA. 274 * In some transport designs this is important since knowing 275 * the actual time we got the packet is useful information. 276 * 277 * A new special type of mbuf may also be supported by the transport 278 * if it has set the INP_MBUF_ACKCMP flag. If its set, LRO will 279 * possibly create a M_ACKCMP type mbuf. This is a mbuf with 280 * an array of "acks". One thing also to note is that when this 281 * occurs a subsequent LRO may find at the back of the untouched 282 * mbuf queue chain a M_ACKCMP and append on to it. This means 283 * that until the transport pulls in the mbuf chain queued 284 * for it more ack's may get on the mbufs that were already 285 * delivered. There currently is a limit of 6 acks condensed 286 * into 1 mbuf which means often when this is occuring, we 287 * don't get that effect but it does happen. 288 * 289 * Now there are some interesting Caveats that the transport 290 * designer needs to take into account when using this feature. 291 * 292 * 1) It is used with HPTS and pacing, when the pacing timer 293 * for output calls it will first call the input. 294 * 2) When you set INP_MBUF_QUEUE_READY this tells LRO 295 * queue normal packets, I am busy pacing out data and 296 * will process the queued packets before my tfb_tcp_output 297 * call from pacing. If a non-normal packet arrives, (e.g. sack) 298 * you will be awoken immediately. 299 * 3) Finally you can add the INP_DONT_SACK_QUEUE to not even 300 * be awoken if a SACK has arrived. You would do this when 301 * you were not only running a pacing for output timer 302 * but a Rack timer as well i.e. you know you are in recovery 303 * and are in the process (via the timers) of dealing with 304 * the loss. 305 * 306 * Now a critical thing you must be aware of here is that the 307 * use of the flags has a far greater scope then just your 308 * typical LRO. Why? Well thats because in the normal compressed 309 * LRO case at the end of a driver interupt all packets are going 310 * to get presented to the transport no matter if there is one 311 * or 100. With the MBUF_QUEUE model, this is not true. You will 312 * only be awoken to process the queue of packets when: 313 * a) The flags discussed above allow it. 314 * <or> 315 * b) You exceed a ack or data limit (by default the 316 * ack limit is infinity (64k acks) and the data 317 * limit is 64k of new TCP data) 318 * <or> 319 * c) The push bit has been set by the peer 320 */ 321 322 static int 323 ctf_process_inbound_raw(struct tcpcb *tp, struct mbuf *m, int has_pkt) 324 { 325 /* 326 * We are passed a raw change of mbuf packets 327 * that arrived in LRO. They are linked via 328 * the m_nextpkt link in the pkt-headers. 329 * 330 * We process each one by: 331 * a) saving off the next 332 * b) stripping off the ether-header 333 * c) formulating the arguments for tfb_do_segment_nounlock() 334 * d) calling each mbuf to tfb_do_segment_nounlock() 335 * after adjusting the time to match the arrival time. 336 * Note that the LRO code assures no IP options are present. 337 * 338 * The symantics for calling tfb_do_segment_nounlock() are the 339 * following: 340 * 1) It returns 0 if all went well and you (the caller) need 341 * to release the lock. 342 * 2) If nxt_pkt is set, then the function will surpress calls 343 * to tcp_output() since you are promising to call again 344 * with another packet. 345 * 3) If it returns 1, then you must free all the packets being 346 * shipped in, the tcb has been destroyed (or about to be destroyed). 347 */ 348 struct mbuf *m_save; 349 struct tcphdr *th; 350 #ifdef INET6 351 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 352 #endif 353 #ifdef INET 354 struct ip *ip = NULL; /* Keep compiler happy. */ 355 #endif 356 struct ifnet *ifp; 357 struct timeval tv; 358 struct inpcb *inp __diagused; 359 int32_t retval, nxt_pkt, tlen, off; 360 int etype = 0; 361 uint16_t drop_hdrlen; 362 uint8_t iptos; 363 364 inp = tptoinpcb(tp); 365 INP_WLOCK_ASSERT(inp); 366 NET_EPOCH_ASSERT(); 367 KASSERT(m != NULL, ("ctf_process_inbound_raw: m == NULL")); 368 ifp = m_rcvif(m); 369 KASSERT(ifp != NULL, ("ctf_process_inbound_raw: ifp == NULL")); 370 CURVNET_SET(ifp->if_vnet); 371 tcp_get_usecs(&tv); 372 while (m) { 373 m_save = m->m_nextpkt; 374 m->m_nextpkt = NULL; 375 if ((m->m_flags & M_ACKCMP) == 0) { 376 /* Now lets get the ether header */ 377 etype = ctf_get_enet_type(ifp, m); 378 if (etype == -1) { 379 /* Skip this packet it was freed by checksum */ 380 goto skipped_pkt; 381 } 382 KASSERT(((etype == ETHERTYPE_IPV6) || (etype == ETHERTYPE_IP)), 383 ("tp:%p m:%p etype:0x%x -- not IP or IPv6", tp, m, etype)); 384 /* Trim off the ethernet header */ 385 switch (etype) { 386 #ifdef INET6 387 case ETHERTYPE_IPV6: 388 ip6 = mtod(m, struct ip6_hdr *); 389 th = (struct tcphdr *)(ip6 + 1); 390 tlen = ntohs(ip6->ip6_plen); 391 drop_hdrlen = sizeof(*ip6); 392 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 393 break; 394 #endif 395 #ifdef INET 396 case ETHERTYPE_IP: 397 ip = mtod(m, struct ip *); 398 th = (struct tcphdr *)(ip + 1); 399 drop_hdrlen = sizeof(*ip); 400 iptos = ip->ip_tos; 401 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 402 break; 403 #endif 404 } /* end switch */ 405 off = th->th_off << 2; 406 if (off < sizeof (struct tcphdr) || off > tlen) { 407 printf("off:%d < hdrlen:%zu || > tlen:%u -- dump\n", 408 off, 409 sizeof(struct tcphdr), 410 tlen); 411 KMOD_TCPSTAT_INC(tcps_rcvbadoff); 412 m_freem(m); 413 goto skipped_pkt; 414 } 415 tlen -= off; 416 drop_hdrlen += off; 417 /* 418 * Now lets setup the timeval to be when we should 419 * have been called (if we can). 420 */ 421 m->m_pkthdr.lro_nsegs = 1; 422 /* Now what about next packet? */ 423 } else { 424 /* 425 * This mbuf is an array of acks that have 426 * been compressed. We assert the inp has 427 * the flag set to enable this! 428 */ 429 KASSERT((tp->t_flags2 & TF2_MBUF_ACKCMP), 430 ("tp:%p no TF2_MBUF_ACKCMP flags?", tp)); 431 tlen = 0; 432 drop_hdrlen = 0; 433 th = NULL; 434 iptos = 0; 435 } 436 tcp_get_usecs(&tv); 437 if (m_save || has_pkt) 438 nxt_pkt = 1; 439 else 440 nxt_pkt = 0; 441 if ((m->m_flags & M_ACKCMP) == 0) 442 KMOD_TCPSTAT_INC(tcps_rcvtotal); 443 else 444 KMOD_TCPSTAT_ADD(tcps_rcvtotal, (m->m_len / sizeof(struct tcp_ackent))); 445 retval = (*tp->t_fb->tfb_do_segment_nounlock)(tp, m, th, 446 drop_hdrlen, tlen, iptos, nxt_pkt, &tv); 447 if (retval) { 448 /* We lost the lock and tcb probably */ 449 m = m_save; 450 while(m) { 451 m_save = m->m_nextpkt; 452 m->m_nextpkt = NULL; 453 m_freem(m); 454 m = m_save; 455 } 456 CURVNET_RESTORE(); 457 INP_UNLOCK_ASSERT(inp); 458 return (retval); 459 } 460 skipped_pkt: 461 m = m_save; 462 } 463 CURVNET_RESTORE(); 464 return (0); 465 } 466 467 int 468 ctf_do_queued_segments(struct tcpcb *tp, int have_pkt) 469 { 470 struct mbuf *m; 471 472 /* First lets see if we have old packets */ 473 if ((m = STAILQ_FIRST(&tp->t_inqueue)) != NULL) { 474 STAILQ_INIT(&tp->t_inqueue); 475 if (ctf_process_inbound_raw(tp, m, have_pkt)) { 476 /* We lost the tcpcb (maybe a RST came in)? */ 477 return(1); 478 } 479 } 480 return (0); 481 } 482 483 uint32_t 484 ctf_outstanding(struct tcpcb *tp) 485 { 486 uint32_t bytes_out; 487 488 bytes_out = tp->snd_max - tp->snd_una; 489 if (tp->t_state < TCPS_ESTABLISHED) 490 bytes_out++; 491 if (tp->t_flags & TF_SENTFIN) 492 bytes_out++; 493 return (bytes_out); 494 } 495 496 uint32_t 497 ctf_flight_size(struct tcpcb *tp, uint32_t rc_sacked) 498 { 499 if (rc_sacked <= ctf_outstanding(tp)) 500 return(ctf_outstanding(tp) - rc_sacked); 501 else { 502 return (0); 503 } 504 } 505 506 void 507 ctf_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 508 int32_t tlen) 509 { 510 tcp_dropwithreset(m, th, tp, tlen); 511 if (tp != NULL) 512 INP_WUNLOCK(tptoinpcb(tp)); 513 } 514 515 void 516 ctf_ack_war_checks(struct tcpcb *tp) 517 { 518 sbintime_t now; 519 520 if ((V_tcp_ack_war_time_window > 0) && (V_tcp_ack_war_cnt > 0)) { 521 now = getsbinuptime(); 522 if (tp->t_challenge_ack_end < now) { 523 tp->t_challenge_ack_cnt = 0; 524 tp->t_challenge_ack_end = now + 525 V_tcp_ack_war_time_window * SBT_1MS; 526 } 527 if (tp->t_challenge_ack_cnt < V_tcp_ack_war_cnt) { 528 tp->t_challenge_ack_cnt++; 529 tp->t_flags |= TF_ACKNOW; 530 } else 531 tp->t_flags &= ~TF_ACKNOW; 532 } else 533 tp->t_flags |= TF_ACKNOW; 534 } 535 536 /* 537 * ctf_drop_checks returns 1 for you should not proceed. It places 538 * in ret_val what should be returned 1/0 by the caller. The 1 indicates 539 * that the TCB is unlocked and probably dropped. The 0 indicates the 540 * TCB is still valid and locked. 541 */ 542 int 543 ctf_drop_checks(struct tcpopt *to, struct mbuf *m, struct tcphdr *th, 544 struct tcpcb *tp, int32_t *tlenp, 545 int32_t *thf, int32_t *drop_hdrlen, int32_t *ret_val) 546 { 547 int32_t todrop; 548 int32_t thflags; 549 int32_t tlen; 550 551 thflags = *thf; 552 tlen = *tlenp; 553 todrop = tp->rcv_nxt - th->th_seq; 554 if (todrop > 0) { 555 if (thflags & TH_SYN) { 556 thflags &= ~TH_SYN; 557 th->th_seq++; 558 if (th->th_urp > 1) 559 th->th_urp--; 560 else 561 thflags &= ~TH_URG; 562 todrop--; 563 } 564 /* 565 * Following if statement from Stevens, vol. 2, p. 960. 566 */ 567 if (todrop > tlen 568 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 569 /* 570 * Any valid FIN must be to the left of the window. 571 * At this point the FIN must be a duplicate or out 572 * of sequence; drop it. 573 */ 574 thflags &= ~TH_FIN; 575 /* 576 * Send an ACK to resynchronize and drop any data. 577 * But keep on processing for RST or ACK. 578 */ 579 ctf_ack_war_checks(tp); 580 todrop = tlen; 581 KMOD_TCPSTAT_INC(tcps_rcvduppack); 582 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 583 } else { 584 KMOD_TCPSTAT_INC(tcps_rcvpartduppack); 585 KMOD_TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 586 } 587 /* 588 * DSACK - add SACK block for dropped range 589 */ 590 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 591 /* 592 * ACK now, as the next in-sequence segment 593 * will clear the DSACK block again 594 */ 595 ctf_ack_war_checks(tp); 596 if (tp->t_flags & TF_ACKNOW) 597 tcp_update_sack_list(tp, th->th_seq, 598 th->th_seq + todrop); 599 } 600 *drop_hdrlen += todrop; /* drop from the top afterwards */ 601 th->th_seq += todrop; 602 tlen -= todrop; 603 if (th->th_urp > todrop) 604 th->th_urp -= todrop; 605 else { 606 thflags &= ~TH_URG; 607 th->th_urp = 0; 608 } 609 } 610 /* 611 * If segment ends after window, drop trailing data (and PUSH and 612 * FIN); if nothing left, just ACK. 613 */ 614 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 615 if (todrop > 0) { 616 KMOD_TCPSTAT_INC(tcps_rcvpackafterwin); 617 if (todrop >= tlen) { 618 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 619 /* 620 * If window is closed can only take segments at 621 * window edge, and have to drop data and PUSH from 622 * incoming segments. Continue processing, but 623 * remember to ack. Otherwise, drop segment and 624 * ack. 625 */ 626 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 627 ctf_ack_war_checks(tp); 628 KMOD_TCPSTAT_INC(tcps_rcvwinprobe); 629 } else { 630 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 631 return (1); 632 } 633 } else 634 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 635 m_adj(m, -todrop); 636 tlen -= todrop; 637 thflags &= ~(TH_PUSH | TH_FIN); 638 } 639 *thf = thflags; 640 *tlenp = tlen; 641 return (0); 642 } 643 644 /* 645 * The value in ret_val informs the caller 646 * if we dropped the tcb (and lock) or not. 647 * 1 = we dropped it, 0 = the TCB is still locked 648 * and valid. 649 */ 650 void 651 ctf_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t *ret_val) 652 { 653 /* 654 * Generate an ACK dropping incoming segment if it occupies sequence 655 * space, where the ACK reflects our state. 656 * 657 * We can now skip the test for the RST flag since all paths to this 658 * code happen after packets containing RST have been dropped. 659 * 660 * In the SYN-RECEIVED state, don't send an ACK unless the segment 661 * we received passes the SYN-RECEIVED ACK test. If it fails send a 662 * RST. This breaks the loop in the "LAND" DoS attack, and also 663 * prevents an ACK storm between two listening ports that have been 664 * sent forged SYN segments, each with the source address of the 665 * other. 666 */ 667 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 668 (SEQ_GT(tp->snd_una, th->th_ack) || 669 SEQ_GT(th->th_ack, tp->snd_max))) { 670 *ret_val = 1; 671 ctf_do_dropwithreset(m, tp, th, tlen); 672 return; 673 } else 674 *ret_val = 0; 675 ctf_ack_war_checks(tp); 676 if (m) 677 m_freem(m); 678 } 679 680 void 681 ctf_do_drop(struct mbuf *m, struct tcpcb *tp) 682 { 683 684 /* 685 * Drop space held by incoming segment and return. 686 */ 687 if (tp != NULL) 688 INP_WUNLOCK(tptoinpcb(tp)); 689 if (m) 690 m_freem(m); 691 } 692 693 int 694 ctf_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, 695 struct tcpcb *tp) 696 { 697 /* 698 * RFC5961 Section 3.2 699 * 700 * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in 701 * window, we send challenge ACK. 702 * 703 * Note: to take into account delayed ACKs, we should test against 704 * last_ack_sent instead of rcv_nxt. Note 2: we handle special case 705 * of closed window, not covered by the RFC. 706 */ 707 int dropped = 0; 708 709 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 710 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 711 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 712 KASSERT(tp->t_state != TCPS_SYN_SENT, 713 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 714 __func__, th, tp)); 715 716 if (V_tcp_insecure_rst || 717 (tp->last_ack_sent == th->th_seq) || 718 (tp->rcv_nxt == th->th_seq)) { 719 KMOD_TCPSTAT_INC(tcps_drops); 720 /* Drop the connection. */ 721 switch (tp->t_state) { 722 case TCPS_SYN_RECEIVED: 723 so->so_error = ECONNREFUSED; 724 goto close; 725 case TCPS_ESTABLISHED: 726 case TCPS_FIN_WAIT_1: 727 case TCPS_FIN_WAIT_2: 728 case TCPS_CLOSE_WAIT: 729 case TCPS_CLOSING: 730 case TCPS_LAST_ACK: 731 so->so_error = ECONNRESET; 732 close: 733 tcp_state_change(tp, TCPS_CLOSED); 734 /* FALLTHROUGH */ 735 default: 736 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 737 tp = tcp_close(tp); 738 } 739 dropped = 1; 740 ctf_do_drop(m, tp); 741 } else { 742 KMOD_TCPSTAT_INC(tcps_badrst); 743 tcp_send_challenge_ack(tp, th, m); 744 } 745 } else { 746 m_freem(m); 747 } 748 return (dropped); 749 } 750 751 /* 752 * The value in ret_val informs the caller 753 * if we dropped the tcb (and lock) or not. 754 * 1 = we dropped it, 0 = the TCB is still locked 755 * and valid. 756 */ 757 void 758 ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, uint8_t iptos, int32_t * ret_val) 759 { 760 761 NET_EPOCH_ASSERT(); 762 763 KMOD_TCPSTAT_INC(tcps_badsyn); 764 if (V_tcp_insecure_syn && 765 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 766 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 767 tp = tcp_drop(tp, ECONNRESET); 768 *ret_val = 1; 769 ctf_do_drop(m, tp); 770 } else { 771 tcp_ecn_input_syn_sent(tp, tcp_get_flags(th), iptos); 772 /* Send challenge ACK. */ 773 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 774 tp->snd_nxt, TH_ACK); 775 tp->last_ack_sent = tp->rcv_nxt; 776 m = NULL; 777 *ret_val = 0; 778 ctf_do_drop(m, NULL); 779 } 780 } 781 782 /* 783 * ctf_ts_check returns 1 for you should not proceed, the state 784 * machine should return. It places in ret_val what should 785 * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates 786 * that the TCB is unlocked and probably dropped. The 0 indicates the 787 * TCB is still valid and locked. 788 */ 789 int 790 ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 791 int32_t tlen, int32_t thflags, int32_t * ret_val) 792 { 793 794 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 795 /* 796 * Invalidate ts_recent. If this segment updates ts_recent, 797 * the age will be reset later and ts_recent will get a 798 * valid value. If it does not, setting ts_recent to zero 799 * will at least satisfy the requirement that zero be placed 800 * in the timestamp echo reply when ts_recent isn't valid. 801 * The age isn't reset until we get a valid ts_recent 802 * because we don't want out-of-order segments to be dropped 803 * when ts_recent is old. 804 */ 805 tp->ts_recent = 0; 806 } else { 807 KMOD_TCPSTAT_INC(tcps_rcvduppack); 808 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 809 KMOD_TCPSTAT_INC(tcps_pawsdrop); 810 *ret_val = 0; 811 if (tlen) { 812 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 813 } else { 814 ctf_do_drop(m, NULL); 815 } 816 return (1); 817 } 818 return (0); 819 } 820 821 int 822 ctf_ts_check_ac(struct tcpcb *tp, int32_t thflags) 823 { 824 825 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 826 /* 827 * Invalidate ts_recent. If this segment updates ts_recent, 828 * the age will be reset later and ts_recent will get a 829 * valid value. If it does not, setting ts_recent to zero 830 * will at least satisfy the requirement that zero be placed 831 * in the timestamp echo reply when ts_recent isn't valid. 832 * The age isn't reset until we get a valid ts_recent 833 * because we don't want out-of-order segments to be dropped 834 * when ts_recent is old. 835 */ 836 tp->ts_recent = 0; 837 } else { 838 KMOD_TCPSTAT_INC(tcps_rcvduppack); 839 KMOD_TCPSTAT_INC(tcps_pawsdrop); 840 return (1); 841 } 842 return (0); 843 } 844 845 846 847 void 848 ctf_calc_rwin(struct socket *so, struct tcpcb *tp) 849 { 850 int32_t win; 851 852 /* 853 * Calculate amount of space in receive window, and then do TCP 854 * input processing. Receive window is amount of space in rcv queue, 855 * but not less than advertised window. 856 */ 857 win = sbspace(&so->so_rcv); 858 if (win < 0) 859 win = 0; 860 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 861 } 862 863 void 864 ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 865 int32_t tlen) 866 { 867 868 tcp_dropwithreset(m, th, tp, tlen); 869 tp = tcp_drop(tp, ETIMEDOUT); 870 if (tp) 871 INP_WUNLOCK(tptoinpcb(tp)); 872 } 873 874 uint32_t 875 ctf_fixed_maxseg(struct tcpcb *tp) 876 { 877 return (tcp_fixed_maxseg(tp)); 878 } 879 880 void 881 ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) 882 { 883 if (tcp_bblogging_on(tp)) { 884 union tcp_log_stackspecific log; 885 struct timeval tv; 886 887 memset(&log, 0, sizeof(log)); 888 log.u_bbr.timeStamp = tcp_get_usecs(&tv); 889 log.u_bbr.flex8 = num_sack_blks; 890 if (num_sack_blks > 0) { 891 log.u_bbr.flex1 = sack_blocks[0].start; 892 log.u_bbr.flex2 = sack_blocks[0].end; 893 } 894 if (num_sack_blks > 1) { 895 log.u_bbr.flex3 = sack_blocks[1].start; 896 log.u_bbr.flex4 = sack_blocks[1].end; 897 } 898 if (num_sack_blks > 2) { 899 log.u_bbr.flex5 = sack_blocks[2].start; 900 log.u_bbr.flex6 = sack_blocks[2].end; 901 } 902 if (num_sack_blks > 3) { 903 log.u_bbr.applimited = sack_blocks[3].start; 904 log.u_bbr.pkts_out = sack_blocks[3].end; 905 } 906 TCP_LOG_EVENTP(tp, NULL, 907 &tptosocket(tp)->so_rcv, 908 &tptosocket(tp)->so_snd, 909 TCP_SACK_FILTER_RES, 0, 910 0, &log, false, &tv); 911 } 912 } 913 914 uint32_t 915 ctf_decay_count(uint32_t count, uint32_t decay) 916 { 917 /* 918 * Given a count, decay it by a set percentage. The 919 * percentage is in thousands i.e. 100% = 1000, 920 * 19.3% = 193. 921 */ 922 uint64_t perc_count, decay_per; 923 uint32_t decayed_count; 924 if (decay > 1000) { 925 /* We don't raise it */ 926 return (count); 927 } 928 perc_count = count; 929 decay_per = decay; 930 perc_count *= decay_per; 931 perc_count /= 1000; 932 /* 933 * So now perc_count holds the 934 * count decay value. 935 */ 936 decayed_count = count - (uint32_t)perc_count; 937 return(decayed_count); 938 } 939 940 int32_t 941 ctf_progress_timeout_check(struct tcpcb *tp, bool log) 942 { 943 if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) { 944 if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) { 945 /* 946 * There is an assumption that the caller 947 * will drop the connection so we will 948 * increment the counters here. 949 */ 950 if (log) 951 tcp_log_end_status(tp, TCP_EI_STATUS_PROGRESS); 952 #ifdef NETFLIX_STATS 953 KMOD_TCPSTAT_INC(tcps_progdrops); 954 #endif 955 return (1); 956 } 957 } 958 return (0); 959 } 960