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 __FBSDID("$FreeBSD$"); 35 36 #include "opt_inet.h" 37 #include "opt_inet6.h" 38 #include "opt_ipsec.h" 39 #include "opt_ratelimit.h" 40 #include <sys/param.h> 41 #include <sys/arb.h> 42 #include <sys/module.h> 43 #include <sys/kernel.h> 44 #ifdef TCP_HHOOK 45 #include <sys/hhook.h> 46 #endif 47 #include <sys/malloc.h> 48 #include <sys/mbuf.h> 49 #include <sys/proc.h> 50 #include <sys/qmath.h> 51 #include <sys/socket.h> 52 #include <sys/socketvar.h> 53 #include <sys/sysctl.h> 54 #include <sys/systm.h> 55 #include <sys/tree.h> 56 #ifdef NETFLIX_STATS 57 #include <sys/stats.h> /* Must come after qmath.h and tree.h */ 58 #endif 59 #include <sys/refcount.h> 60 #include <sys/queue.h> 61 #include <sys/smp.h> 62 #include <sys/kthread.h> 63 #include <sys/lock.h> 64 #include <sys/mutex.h> 65 #include <sys/tim_filter.h> 66 #include <sys/time.h> 67 #include <vm/uma.h> 68 #include <sys/kern_prefetch.h> 69 70 #include <net/route.h> 71 #include <net/vnet.h> 72 #include <net/ethernet.h> 73 #include <net/bpf.h> 74 75 #define TCPSTATES /* for logging */ 76 77 #include <netinet/in.h> 78 #include <netinet/in_kdtrace.h> 79 #include <netinet/in_pcb.h> 80 #include <netinet/ip.h> 81 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 82 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 83 #include <netinet/ip_var.h> 84 #include <netinet/ip6.h> 85 #include <netinet6/in6_pcb.h> 86 #include <netinet6/ip6_var.h> 87 #include <netinet/tcp.h> 88 #include <netinet/tcp_fsm.h> 89 #include <netinet/tcp_seq.h> 90 #include <netinet/tcp_timer.h> 91 #include <netinet/tcp_var.h> 92 #include <netinet/tcpip.h> 93 #include <netinet/tcp_ecn.h> 94 #include <netinet/tcp_hpts.h> 95 #include <netinet/tcp_lro.h> 96 #include <netinet/cc/cc.h> 97 #include <netinet/tcp_log_buf.h> 98 #ifdef TCP_OFFLOAD 99 #include <netinet/tcp_offload.h> 100 #endif 101 #ifdef INET6 102 #include <netinet6/tcp6_var.h> 103 #endif 104 #include <netinet/tcp_fastopen.h> 105 106 #include <netipsec/ipsec_support.h> 107 #include <net/if.h> 108 #include <net/if_var.h> 109 #include <net/if_private.h> 110 111 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 112 #include <netipsec/ipsec.h> 113 #include <netipsec/ipsec6.h> 114 #endif /* IPSEC */ 115 116 #include <netinet/udp.h> 117 #include <netinet/udp_var.h> 118 #include <machine/in_cksum.h> 119 120 #ifdef MAC 121 #include <security/mac/mac_framework.h> 122 #endif 123 #include "rack_bbr_common.h" 124 125 /* 126 * Common TCP Functions - These are shared by borth 127 * rack and BBR. 128 */ 129 static int 130 ctf_get_enet_type(struct ifnet *ifp, struct mbuf *m) 131 { 132 struct ether_header *eh; 133 #ifdef INET6 134 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 135 #endif 136 #ifdef INET 137 struct ip *ip = NULL; /* Keep compiler happy. */ 138 #endif 139 #if defined(INET) || defined(INET6) 140 struct tcphdr *th; 141 int32_t tlen; 142 uint16_t drop_hdrlen; 143 #endif 144 uint16_t etype; 145 #ifdef INET 146 uint8_t iptos; 147 #endif 148 149 /* Is it the easy way? */ 150 if (m->m_flags & M_LRO_EHDRSTRP) 151 return (m->m_pkthdr.lro_etype); 152 /* 153 * Ok this is the old style call, the ethernet header is here. 154 * This also means no checksum or BPF were done. This 155 * can happen if the race to setup the inp fails and 156 * LRO sees no INP at packet input, but by the time 157 * we queue the packets an INP gets there. Its rare 158 * but it can occur so we will handle it. Note that 159 * this means duplicated work but with the rarity of it 160 * its not worth worrying about. 161 */ 162 /* Let the BPF see the packet */ 163 if (bpf_peers_present(ifp->if_bpf)) 164 ETHER_BPF_MTAP(ifp, m); 165 /* Now the csum */ 166 eh = mtod(m, struct ether_header *); 167 etype = ntohs(eh->ether_type); 168 m_adj(m, sizeof(*eh)); 169 switch (etype) { 170 #ifdef INET6 171 case ETHERTYPE_IPV6: 172 { 173 if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 174 m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 175 if (m == NULL) { 176 KMOD_TCPSTAT_INC(tcps_rcvshort); 177 return (-1); 178 } 179 } 180 ip6 = (struct ip6_hdr *)(eh + 1); 181 th = (struct tcphdr *)(ip6 + 1); 182 drop_hdrlen = sizeof(*ip6); 183 tlen = ntohs(ip6->ip6_plen); 184 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 185 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 186 th->th_sum = m->m_pkthdr.csum_data; 187 else 188 th->th_sum = in6_cksum_pseudo(ip6, tlen, 189 IPPROTO_TCP, 190 m->m_pkthdr.csum_data); 191 th->th_sum ^= 0xffff; 192 } else 193 th->th_sum = in6_cksum(m, IPPROTO_TCP, drop_hdrlen, tlen); 194 if (th->th_sum) { 195 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 196 m_freem(m); 197 return (-1); 198 } 199 return (etype); 200 } 201 #endif 202 #ifdef INET 203 case ETHERTYPE_IP: 204 { 205 if (m->m_len < sizeof (struct tcpiphdr)) { 206 m = m_pullup(m, sizeof (struct tcpiphdr)); 207 if (m == NULL) { 208 KMOD_TCPSTAT_INC(tcps_rcvshort); 209 return (-1); 210 } 211 } 212 ip = (struct ip *)(eh + 1); 213 th = (struct tcphdr *)(ip + 1); 214 drop_hdrlen = sizeof(*ip); 215 iptos = ip->ip_tos; 216 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 217 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 218 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 219 th->th_sum = m->m_pkthdr.csum_data; 220 else 221 th->th_sum = in_pseudo(ip->ip_src.s_addr, 222 ip->ip_dst.s_addr, 223 htonl(m->m_pkthdr.csum_data + tlen + IPPROTO_TCP)); 224 th->th_sum ^= 0xffff; 225 } else { 226 int len; 227 struct ipovly *ipov = (struct ipovly *)ip; 228 /* 229 * Checksum extended TCP header and data. 230 */ 231 len = drop_hdrlen + tlen; 232 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 233 ipov->ih_len = htons(tlen); 234 th->th_sum = in_cksum(m, len); 235 /* Reset length for SDT probes. */ 236 ip->ip_len = htons(len); 237 /* Reset TOS bits */ 238 ip->ip_tos = iptos; 239 /* Re-initialization for later version check */ 240 ip->ip_v = IPVERSION; 241 ip->ip_hl = sizeof(*ip) >> 2; 242 } 243 if (th->th_sum) { 244 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 245 m_freem(m); 246 return (-1); 247 } 248 break; 249 } 250 #endif 251 }; 252 return (etype); 253 } 254 255 /* 256 * The function ctf_process_inbound_raw() is used by 257 * transport developers to do the steps needed to 258 * support MBUF Queuing i.e. the flags in 259 * inp->inp_flags2: 260 * 261 * - INP_SUPPORTS_MBUFQ 262 * - INP_MBUF_QUEUE_READY 263 * - INP_DONT_SACK_QUEUE 264 * - INP_MBUF_ACKCMP 265 * 266 * These flags help control how LRO will deliver 267 * packets to the transport. You first set in inp_flags2 268 * the INP_SUPPORTS_MBUFQ to tell the LRO code that you 269 * will gladly take a queue of packets instead of a compressed 270 * single packet. You also set in your t_fb pointer the 271 * tfb_do_queued_segments to point to ctf_process_inbound_raw. 272 * 273 * This then gets you lists of inbound ACK's/Data instead 274 * of a condensed compressed ACK/DATA packet. Why would you 275 * want that? This will get you access to all the arrival 276 * times of at least LRO and possibly at the Hardware (if 277 * the interface card supports that) of the actual ACK/DATA. 278 * In some transport designs this is important since knowing 279 * the actual time we got the packet is useful information. 280 * 281 * A new special type of mbuf may also be supported by the transport 282 * if it has set the INP_MBUF_ACKCMP flag. If its set, LRO will 283 * possibly create a M_ACKCMP type mbuf. This is a mbuf with 284 * an array of "acks". One thing also to note is that when this 285 * occurs a subsequent LRO may find at the back of the untouched 286 * mbuf queue chain a M_ACKCMP and append on to it. This means 287 * that until the transport pulls in the mbuf chain queued 288 * for it more ack's may get on the mbufs that were already 289 * delivered. There currently is a limit of 6 acks condensed 290 * into 1 mbuf which means often when this is occuring, we 291 * don't get that effect but it does happen. 292 * 293 * Now there are some interesting Caveats that the transport 294 * designer needs to take into account when using this feature. 295 * 296 * 1) It is used with HPTS and pacing, when the pacing timer 297 * for output calls it will first call the input. 298 * 2) When you set INP_MBUF_QUEUE_READY this tells LRO 299 * queue normal packets, I am busy pacing out data and 300 * will process the queued packets before my tfb_tcp_output 301 * call from pacing. If a non-normal packet arrives, (e.g. sack) 302 * you will be awoken immediately. 303 * 3) Finally you can add the INP_DONT_SACK_QUEUE to not even 304 * be awoken if a SACK has arrived. You would do this when 305 * you were not only running a pacing for output timer 306 * but a Rack timer as well i.e. you know you are in recovery 307 * and are in the process (via the timers) of dealing with 308 * the loss. 309 * 310 * Now a critical thing you must be aware of here is that the 311 * use of the flags has a far greater scope then just your 312 * typical LRO. Why? Well thats because in the normal compressed 313 * LRO case at the end of a driver interupt all packets are going 314 * to get presented to the transport no matter if there is one 315 * or 100. With the MBUF_QUEUE model, this is not true. You will 316 * only be awoken to process the queue of packets when: 317 * a) The flags discussed above allow it. 318 * <or> 319 * b) You exceed a ack or data limit (by default the 320 * ack limit is infinity (64k acks) and the data 321 * limit is 64k of new TCP data) 322 * <or> 323 * c) The push bit has been set by the peer 324 */ 325 326 int 327 ctf_process_inbound_raw(struct tcpcb *tp, struct socket *so, struct mbuf *m, int has_pkt) 328 { 329 /* 330 * We are passed a raw change of mbuf packets 331 * that arrived in LRO. They are linked via 332 * the m_nextpkt link in the pkt-headers. 333 * 334 * We process each one by: 335 * a) saving off the next 336 * b) stripping off the ether-header 337 * c) formulating the arguments for 338 * the tfb_tcp_hpts_do_segment 339 * d) calling each mbuf to tfb_tcp_hpts_do_segment 340 * after adjusting the time to match the arrival time. 341 * Note that the LRO code assures no IP options are present. 342 * 343 * The symantics for calling tfb_tcp_hpts_do_segment are the 344 * following: 345 * 1) It returns 0 if all went well and you (the caller) need 346 * to release the lock. 347 * 2) If nxt_pkt is set, then the function will surpress calls 348 * to tcp_output() since you are promising to call again 349 * with another packet. 350 * 3) If it returns 1, then you must free all the packets being 351 * shipped in, the tcb has been destroyed (or about to be destroyed). 352 */ 353 struct mbuf *m_save; 354 struct tcphdr *th; 355 #ifdef INET6 356 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 357 #endif 358 #ifdef INET 359 struct ip *ip = NULL; /* Keep compiler happy. */ 360 #endif 361 struct ifnet *ifp; 362 struct timeval tv; 363 struct inpcb *inp __diagused; 364 int32_t retval, nxt_pkt, tlen, off; 365 int etype = 0; 366 uint16_t drop_hdrlen; 367 uint8_t iptos, no_vn=0; 368 369 inp = tptoinpcb(tp); 370 INP_WLOCK_ASSERT(inp); 371 NET_EPOCH_ASSERT(); 372 373 if (m) 374 ifp = m_rcvif(m); 375 else 376 ifp = NULL; 377 if (ifp == NULL) { 378 /* 379 * We probably should not work around 380 * but kassert, since lro alwasy sets rcvif. 381 */ 382 no_vn = 1; 383 goto skip_vnet; 384 } 385 CURVNET_SET(ifp->if_vnet); 386 skip_vnet: 387 tcp_get_usecs(&tv); 388 while (m) { 389 m_save = m->m_nextpkt; 390 m->m_nextpkt = NULL; 391 if ((m->m_flags & M_ACKCMP) == 0) { 392 /* Now lets get the ether header */ 393 etype = ctf_get_enet_type(ifp, m); 394 if (etype == -1) { 395 /* Skip this packet it was freed by checksum */ 396 goto skipped_pkt; 397 } 398 KASSERT(((etype == ETHERTYPE_IPV6) || (etype == ETHERTYPE_IP)), 399 ("tp:%p m:%p etype:0x%x -- not IP or IPv6", tp, m, etype)); 400 /* Trim off the ethernet header */ 401 switch (etype) { 402 #ifdef INET6 403 case ETHERTYPE_IPV6: 404 ip6 = mtod(m, struct ip6_hdr *); 405 th = (struct tcphdr *)(ip6 + 1); 406 tlen = ntohs(ip6->ip6_plen); 407 drop_hdrlen = sizeof(*ip6); 408 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 409 break; 410 #endif 411 #ifdef INET 412 case ETHERTYPE_IP: 413 ip = mtod(m, struct ip *); 414 th = (struct tcphdr *)(ip + 1); 415 drop_hdrlen = sizeof(*ip); 416 iptos = ip->ip_tos; 417 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 418 break; 419 #endif 420 } /* end switch */ 421 /* 422 * Convert TCP protocol specific fields to host format. 423 */ 424 tcp_fields_to_host(th); 425 off = th->th_off << 2; 426 if (off < sizeof (struct tcphdr) || off > tlen) { 427 printf("off:%d < hdrlen:%zu || > tlen:%u -- dump\n", 428 off, 429 sizeof(struct tcphdr), 430 tlen); 431 KMOD_TCPSTAT_INC(tcps_rcvbadoff); 432 m_freem(m); 433 goto skipped_pkt; 434 } 435 tlen -= off; 436 drop_hdrlen += off; 437 /* 438 * Now lets setup the timeval to be when we should 439 * have been called (if we can). 440 */ 441 m->m_pkthdr.lro_nsegs = 1; 442 /* Now what about next packet? */ 443 } else { 444 /* 445 * This mbuf is an array of acks that have 446 * been compressed. We assert the inp has 447 * the flag set to enable this! 448 */ 449 KASSERT((inp->inp_flags2 & INP_MBUF_ACKCMP), 450 ("tp:%p inp:%p no INP_MBUF_ACKCMP flags?", tp, inp)); 451 tlen = 0; 452 drop_hdrlen = 0; 453 th = NULL; 454 iptos = 0; 455 } 456 tcp_get_usecs(&tv); 457 if (m_save || has_pkt) 458 nxt_pkt = 1; 459 else 460 nxt_pkt = 0; 461 if ((m->m_flags & M_ACKCMP) == 0) 462 KMOD_TCPSTAT_INC(tcps_rcvtotal); 463 else 464 KMOD_TCPSTAT_ADD(tcps_rcvtotal, (m->m_len / sizeof(struct tcp_ackent))); 465 retval = (*tp->t_fb->tfb_do_segment_nounlock)(m, th, so, tp, drop_hdrlen, tlen, 466 iptos, nxt_pkt, &tv); 467 if (retval) { 468 /* We lost the lock and tcb probably */ 469 m = m_save; 470 while(m) { 471 m_save = m->m_nextpkt; 472 m->m_nextpkt = NULL; 473 m_freem(m); 474 m = m_save; 475 } 476 if (no_vn == 0) { 477 CURVNET_RESTORE(); 478 } 479 INP_UNLOCK_ASSERT(inp); 480 return(retval); 481 } 482 skipped_pkt: 483 m = m_save; 484 } 485 if (no_vn == 0) { 486 CURVNET_RESTORE(); 487 } 488 return(retval); 489 } 490 491 int 492 ctf_do_queued_segments(struct socket *so, struct tcpcb *tp, int have_pkt) 493 { 494 struct mbuf *m; 495 496 /* First lets see if we have old packets */ 497 if (tp->t_in_pkt) { 498 m = tp->t_in_pkt; 499 tp->t_in_pkt = NULL; 500 tp->t_tail_pkt = NULL; 501 if (ctf_process_inbound_raw(tp, so, m, have_pkt)) { 502 /* We lost the tcpcb (maybe a RST came in)? */ 503 return(1); 504 } 505 } 506 return (0); 507 } 508 509 uint32_t 510 ctf_outstanding(struct tcpcb *tp) 511 { 512 uint32_t bytes_out; 513 514 bytes_out = tp->snd_max - tp->snd_una; 515 if (tp->t_state < TCPS_ESTABLISHED) 516 bytes_out++; 517 if (tp->t_flags & TF_SENTFIN) 518 bytes_out++; 519 return (bytes_out); 520 } 521 522 uint32_t 523 ctf_flight_size(struct tcpcb *tp, uint32_t rc_sacked) 524 { 525 if (rc_sacked <= ctf_outstanding(tp)) 526 return(ctf_outstanding(tp) - rc_sacked); 527 else { 528 return (0); 529 } 530 } 531 532 void 533 ctf_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 534 int32_t rstreason, int32_t tlen) 535 { 536 if (tp != NULL) { 537 tcp_dropwithreset(m, th, tp, tlen, rstreason); 538 INP_WUNLOCK(tptoinpcb(tp)); 539 } else 540 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 541 } 542 543 void 544 ctf_ack_war_checks(struct tcpcb *tp, uint32_t *ts, uint32_t *cnt) 545 { 546 if ((ts != NULL) && (cnt != NULL) && 547 (tcp_ack_war_time_window > 0) && 548 (tcp_ack_war_cnt > 0)) { 549 /* We are possibly doing ack war prevention */ 550 uint32_t cts; 551 552 /* 553 * We use a msec tick here which gives us 554 * roughly 49 days. We don't need the 555 * precision of a microsecond timestamp which 556 * would only give us hours. 557 */ 558 cts = tcp_ts_getticks(); 559 if (TSTMP_LT((*ts), cts)) { 560 /* Timestamp is in the past */ 561 *cnt = 0; 562 *ts = (cts + tcp_ack_war_time_window); 563 } 564 if (*cnt < tcp_ack_war_cnt) { 565 *cnt = (*cnt + 1); 566 tp->t_flags |= TF_ACKNOW; 567 } else 568 tp->t_flags &= ~TF_ACKNOW; 569 } else 570 tp->t_flags |= TF_ACKNOW; 571 } 572 573 /* 574 * ctf_drop_checks returns 1 for you should not proceed. It places 575 * in ret_val what should be returned 1/0 by the caller. The 1 indicates 576 * that the TCB is unlocked and probably dropped. The 0 indicates the 577 * TCB is still valid and locked. 578 */ 579 int 580 _ctf_drop_checks(struct tcpopt *to, struct mbuf *m, struct tcphdr *th, 581 struct tcpcb *tp, int32_t *tlenp, 582 int32_t *thf, int32_t *drop_hdrlen, int32_t *ret_val, 583 uint32_t *ts, uint32_t *cnt) 584 { 585 int32_t todrop; 586 int32_t thflags; 587 int32_t tlen; 588 589 thflags = *thf; 590 tlen = *tlenp; 591 todrop = tp->rcv_nxt - th->th_seq; 592 if (todrop > 0) { 593 if (thflags & TH_SYN) { 594 thflags &= ~TH_SYN; 595 th->th_seq++; 596 if (th->th_urp > 1) 597 th->th_urp--; 598 else 599 thflags &= ~TH_URG; 600 todrop--; 601 } 602 /* 603 * Following if statement from Stevens, vol. 2, p. 960. 604 */ 605 if (todrop > tlen 606 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 607 /* 608 * Any valid FIN must be to the left of the window. 609 * At this point the FIN must be a duplicate or out 610 * of sequence; drop it. 611 */ 612 thflags &= ~TH_FIN; 613 /* 614 * Send an ACK to resynchronize and drop any data. 615 * But keep on processing for RST or ACK. 616 */ 617 ctf_ack_war_checks(tp, ts, cnt); 618 todrop = tlen; 619 KMOD_TCPSTAT_INC(tcps_rcvduppack); 620 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 621 } else { 622 KMOD_TCPSTAT_INC(tcps_rcvpartduppack); 623 KMOD_TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 624 } 625 /* 626 * DSACK - add SACK block for dropped range 627 */ 628 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 629 /* 630 * ACK now, as the next in-sequence segment 631 * will clear the DSACK block again 632 */ 633 ctf_ack_war_checks(tp, ts, cnt); 634 if (tp->t_flags & TF_ACKNOW) 635 tcp_update_sack_list(tp, th->th_seq, 636 th->th_seq + todrop); 637 } 638 *drop_hdrlen += todrop; /* drop from the top afterwards */ 639 th->th_seq += todrop; 640 tlen -= todrop; 641 if (th->th_urp > todrop) 642 th->th_urp -= todrop; 643 else { 644 thflags &= ~TH_URG; 645 th->th_urp = 0; 646 } 647 } 648 /* 649 * If segment ends after window, drop trailing data (and PUSH and 650 * FIN); if nothing left, just ACK. 651 */ 652 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 653 if (todrop > 0) { 654 KMOD_TCPSTAT_INC(tcps_rcvpackafterwin); 655 if (todrop >= tlen) { 656 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 657 /* 658 * If window is closed can only take segments at 659 * window edge, and have to drop data and PUSH from 660 * incoming segments. Continue processing, but 661 * remember to ack. Otherwise, drop segment and 662 * ack. 663 */ 664 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 665 ctf_ack_war_checks(tp, ts, cnt); 666 KMOD_TCPSTAT_INC(tcps_rcvwinprobe); 667 } else { 668 __ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val, ts, cnt); 669 return (1); 670 } 671 } else 672 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 673 m_adj(m, -todrop); 674 tlen -= todrop; 675 thflags &= ~(TH_PUSH | TH_FIN); 676 } 677 *thf = thflags; 678 *tlenp = tlen; 679 return (0); 680 } 681 682 /* 683 * The value in ret_val informs the caller 684 * if we dropped the tcb (and lock) or not. 685 * 1 = we dropped it, 0 = the TCB is still locked 686 * and valid. 687 */ 688 void 689 __ctf_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t *ret_val, uint32_t *ts, uint32_t *cnt) 690 { 691 /* 692 * Generate an ACK dropping incoming segment if it occupies sequence 693 * space, where the ACK reflects our state. 694 * 695 * We can now skip the test for the RST flag since all paths to this 696 * code happen after packets containing RST have been dropped. 697 * 698 * In the SYN-RECEIVED state, don't send an ACK unless the segment 699 * we received passes the SYN-RECEIVED ACK test. If it fails send a 700 * RST. This breaks the loop in the "LAND" DoS attack, and also 701 * prevents an ACK storm between two listening ports that have been 702 * sent forged SYN segments, each with the source address of the 703 * other. 704 */ 705 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 706 (SEQ_GT(tp->snd_una, th->th_ack) || 707 SEQ_GT(th->th_ack, tp->snd_max))) { 708 *ret_val = 1; 709 ctf_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen); 710 return; 711 } else 712 *ret_val = 0; 713 ctf_ack_war_checks(tp, ts, cnt); 714 if (m) 715 m_freem(m); 716 } 717 718 void 719 ctf_do_drop(struct mbuf *m, struct tcpcb *tp) 720 { 721 722 /* 723 * Drop space held by incoming segment and return. 724 */ 725 if (tp != NULL) 726 INP_WUNLOCK(tptoinpcb(tp)); 727 if (m) 728 m_freem(m); 729 } 730 731 int 732 __ctf_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, 733 struct tcpcb *tp, uint32_t *ts, uint32_t *cnt) 734 { 735 /* 736 * RFC5961 Section 3.2 737 * 738 * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in 739 * window, we send challenge ACK. 740 * 741 * Note: to take into account delayed ACKs, we should test against 742 * last_ack_sent instead of rcv_nxt. Note 2: we handle special case 743 * of closed window, not covered by the RFC. 744 */ 745 int dropped = 0; 746 747 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 748 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 749 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 750 KASSERT(tp->t_state != TCPS_SYN_SENT, 751 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 752 __func__, th, tp)); 753 754 if (V_tcp_insecure_rst || 755 (tp->last_ack_sent == th->th_seq) || 756 (tp->rcv_nxt == th->th_seq)) { 757 KMOD_TCPSTAT_INC(tcps_drops); 758 /* Drop the connection. */ 759 switch (tp->t_state) { 760 case TCPS_SYN_RECEIVED: 761 so->so_error = ECONNREFUSED; 762 goto close; 763 case TCPS_ESTABLISHED: 764 case TCPS_FIN_WAIT_1: 765 case TCPS_FIN_WAIT_2: 766 case TCPS_CLOSE_WAIT: 767 case TCPS_CLOSING: 768 case TCPS_LAST_ACK: 769 so->so_error = ECONNRESET; 770 close: 771 tcp_state_change(tp, TCPS_CLOSED); 772 /* FALLTHROUGH */ 773 default: 774 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 775 tp = tcp_close(tp); 776 } 777 dropped = 1; 778 ctf_do_drop(m, tp); 779 } else { 780 int send_challenge; 781 782 KMOD_TCPSTAT_INC(tcps_badrst); 783 if ((ts != NULL) && (cnt != NULL) && 784 (tcp_ack_war_time_window > 0) && 785 (tcp_ack_war_cnt > 0)) { 786 /* We are possibly preventing an ack-rst war prevention */ 787 uint32_t cts; 788 789 /* 790 * We use a msec tick here which gives us 791 * roughly 49 days. We don't need the 792 * precision of a microsecond timestamp which 793 * would only give us hours. 794 */ 795 cts = tcp_ts_getticks(); 796 if (TSTMP_LT((*ts), cts)) { 797 /* Timestamp is in the past */ 798 *cnt = 0; 799 *ts = (cts + tcp_ack_war_time_window); 800 } 801 if (*cnt < tcp_ack_war_cnt) { 802 *cnt = (*cnt + 1); 803 send_challenge = 1; 804 } else 805 send_challenge = 0; 806 } else 807 send_challenge = 1; 808 if (send_challenge) { 809 /* Send challenge ACK. */ 810 tcp_respond(tp, mtod(m, void *), th, m, 811 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 812 tp->last_ack_sent = tp->rcv_nxt; 813 } 814 } 815 } else { 816 m_freem(m); 817 } 818 return (dropped); 819 } 820 821 /* 822 * The value in ret_val informs the caller 823 * if we dropped the tcb (and lock) or not. 824 * 1 = we dropped it, 0 = the TCB is still locked 825 * and valid. 826 */ 827 void 828 ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, uint8_t iptos, int32_t * ret_val) 829 { 830 831 NET_EPOCH_ASSERT(); 832 833 KMOD_TCPSTAT_INC(tcps_badsyn); 834 if (V_tcp_insecure_syn && 835 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 836 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 837 tp = tcp_drop(tp, ECONNRESET); 838 *ret_val = 1; 839 ctf_do_drop(m, tp); 840 } else { 841 tcp_ecn_input_syn_sent(tp, tcp_get_flags(th), iptos); 842 /* Send challenge ACK. */ 843 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 844 tp->snd_nxt, TH_ACK); 845 tp->last_ack_sent = tp->rcv_nxt; 846 m = NULL; 847 *ret_val = 0; 848 ctf_do_drop(m, NULL); 849 } 850 } 851 852 /* 853 * ctf_ts_check returns 1 for you should not proceed, the state 854 * machine should return. It places in ret_val what should 855 * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates 856 * that the TCB is unlocked and probably dropped. The 0 indicates the 857 * TCB is still valid and locked. 858 */ 859 int 860 ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 861 int32_t tlen, int32_t thflags, int32_t * ret_val) 862 { 863 864 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 865 /* 866 * Invalidate ts_recent. If this segment updates ts_recent, 867 * the age will be reset later and ts_recent will get a 868 * valid value. If it does not, setting ts_recent to zero 869 * will at least satisfy the requirement that zero be placed 870 * in the timestamp echo reply when ts_recent isn't valid. 871 * The age isn't reset until we get a valid ts_recent 872 * because we don't want out-of-order segments to be dropped 873 * when ts_recent is old. 874 */ 875 tp->ts_recent = 0; 876 } else { 877 KMOD_TCPSTAT_INC(tcps_rcvduppack); 878 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 879 KMOD_TCPSTAT_INC(tcps_pawsdrop); 880 *ret_val = 0; 881 if (tlen) { 882 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 883 } else { 884 ctf_do_drop(m, NULL); 885 } 886 return (1); 887 } 888 return (0); 889 } 890 891 int 892 ctf_ts_check_ac(struct tcpcb *tp, int32_t thflags) 893 { 894 895 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 896 /* 897 * Invalidate ts_recent. If this segment updates ts_recent, 898 * the age will be reset later and ts_recent will get a 899 * valid value. If it does not, setting ts_recent to zero 900 * will at least satisfy the requirement that zero be placed 901 * in the timestamp echo reply when ts_recent isn't valid. 902 * The age isn't reset until we get a valid ts_recent 903 * because we don't want out-of-order segments to be dropped 904 * when ts_recent is old. 905 */ 906 tp->ts_recent = 0; 907 } else { 908 KMOD_TCPSTAT_INC(tcps_rcvduppack); 909 KMOD_TCPSTAT_INC(tcps_pawsdrop); 910 return (1); 911 } 912 return (0); 913 } 914 915 916 917 void 918 ctf_calc_rwin(struct socket *so, struct tcpcb *tp) 919 { 920 int32_t win; 921 922 /* 923 * Calculate amount of space in receive window, and then do TCP 924 * input processing. Receive window is amount of space in rcv queue, 925 * but not less than advertised window. 926 */ 927 win = sbspace(&so->so_rcv); 928 if (win < 0) 929 win = 0; 930 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 931 } 932 933 void 934 ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 935 int32_t rstreason, int32_t tlen) 936 { 937 938 tcp_dropwithreset(m, th, tp, tlen, rstreason); 939 tp = tcp_drop(tp, ETIMEDOUT); 940 if (tp) 941 INP_WUNLOCK(tptoinpcb(tp)); 942 } 943 944 uint32_t 945 ctf_fixed_maxseg(struct tcpcb *tp) 946 { 947 return (tcp_fixed_maxseg(tp)); 948 } 949 950 void 951 ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) 952 { 953 if (tcp_bblogging_on(tp)) { 954 union tcp_log_stackspecific log; 955 struct timeval tv; 956 957 memset(&log, 0, sizeof(log)); 958 log.u_bbr.timeStamp = tcp_get_usecs(&tv); 959 log.u_bbr.flex8 = num_sack_blks; 960 if (num_sack_blks > 0) { 961 log.u_bbr.flex1 = sack_blocks[0].start; 962 log.u_bbr.flex2 = sack_blocks[0].end; 963 } 964 if (num_sack_blks > 1) { 965 log.u_bbr.flex3 = sack_blocks[1].start; 966 log.u_bbr.flex4 = sack_blocks[1].end; 967 } 968 if (num_sack_blks > 2) { 969 log.u_bbr.flex5 = sack_blocks[2].start; 970 log.u_bbr.flex6 = sack_blocks[2].end; 971 } 972 if (num_sack_blks > 3) { 973 log.u_bbr.applimited = sack_blocks[3].start; 974 log.u_bbr.pkts_out = sack_blocks[3].end; 975 } 976 TCP_LOG_EVENTP(tp, NULL, 977 &tptosocket(tp)->so_rcv, 978 &tptosocket(tp)->so_snd, 979 TCP_SACK_FILTER_RES, 0, 980 0, &log, false, &tv); 981 } 982 } 983 984 uint32_t 985 ctf_decay_count(uint32_t count, uint32_t decay) 986 { 987 /* 988 * Given a count, decay it by a set percentage. The 989 * percentage is in thousands i.e. 100% = 1000, 990 * 19.3% = 193. 991 */ 992 uint64_t perc_count, decay_per; 993 uint32_t decayed_count; 994 if (decay > 1000) { 995 /* We don't raise it */ 996 return (count); 997 } 998 perc_count = count; 999 decay_per = decay; 1000 perc_count *= decay_per; 1001 perc_count /= 1000; 1002 /* 1003 * So now perc_count holds the 1004 * count decay value. 1005 */ 1006 decayed_count = count - (uint32_t)perc_count; 1007 return(decayed_count); 1008 } 1009 1010 int32_t 1011 ctf_progress_timeout_check(struct tcpcb *tp, bool log) 1012 { 1013 if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) { 1014 if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) { 1015 /* 1016 * There is an assumption that the caller 1017 * will drop the connection so we will 1018 * increment the counters here. 1019 */ 1020 if (log) 1021 tcp_log_end_status(tp, TCP_EI_STATUS_PROGRESS); 1022 #ifdef NETFLIX_STATS 1023 KMOD_TCPSTAT_INC(tcps_progdrops); 1024 #endif 1025 return (1); 1026 } 1027 } 1028 return (0); 1029 } 1030