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_tcpdebug.h" 40 #include "opt_ratelimit.h" 41 #include "opt_kern_tls.h" 42 #include <sys/param.h> 43 #include <sys/arb.h> 44 #include <sys/module.h> 45 #include <sys/kernel.h> 46 #ifdef TCP_HHOOK 47 #include <sys/hhook.h> 48 #endif 49 #include <sys/malloc.h> 50 #include <sys/mbuf.h> 51 #include <sys/proc.h> 52 #include <sys/qmath.h> 53 #include <sys/socket.h> 54 #include <sys/socketvar.h> 55 #ifdef KERN_TLS 56 #include <sys/ktls.h> 57 #endif 58 #include <sys/sysctl.h> 59 #include <sys/systm.h> 60 #include <sys/tree.h> 61 #ifdef NETFLIX_STATS 62 #include <sys/stats.h> /* Must come after qmath.h and tree.h */ 63 #endif 64 #include <sys/refcount.h> 65 #include <sys/queue.h> 66 #include <sys/smp.h> 67 #include <sys/kthread.h> 68 #include <sys/lock.h> 69 #include <sys/mutex.h> 70 #include <sys/tim_filter.h> 71 #include <sys/time.h> 72 #include <vm/uma.h> 73 #include <sys/kern_prefetch.h> 74 75 #include <net/route.h> 76 #include <net/vnet.h> 77 #include <net/ethernet.h> 78 #include <net/bpf.h> 79 80 #define TCPSTATES /* for logging */ 81 82 #include <netinet/in.h> 83 #include <netinet/in_kdtrace.h> 84 #include <netinet/in_pcb.h> 85 #include <netinet/ip.h> 86 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 87 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 88 #include <netinet/ip_var.h> 89 #include <netinet/ip6.h> 90 #include <netinet6/in6_pcb.h> 91 #include <netinet6/ip6_var.h> 92 #include <netinet/tcp.h> 93 #include <netinet/tcp_fsm.h> 94 #include <netinet/tcp_seq.h> 95 #include <netinet/tcp_timer.h> 96 #include <netinet/tcp_var.h> 97 #include <netinet/tcpip.h> 98 #include <netinet/tcp_hpts.h> 99 #include <netinet/cc/cc.h> 100 #include <netinet/tcp_log_buf.h> 101 #ifdef TCPDEBUG 102 #include <netinet/tcp_debug.h> 103 #endif /* TCPDEBUG */ 104 #ifdef TCP_OFFLOAD 105 #include <netinet/tcp_offload.h> 106 #endif 107 #ifdef INET6 108 #include <netinet6/tcp6_var.h> 109 #endif 110 #include <netinet/tcp_fastopen.h> 111 112 #include <netipsec/ipsec_support.h> 113 #include <net/if.h> 114 #include <net/if_var.h> 115 116 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 117 #include <netipsec/ipsec.h> 118 #include <netipsec/ipsec6.h> 119 #endif /* IPSEC */ 120 121 #include <netinet/udp.h> 122 #include <netinet/udp_var.h> 123 #include <machine/in_cksum.h> 124 125 #ifdef MAC 126 #include <security/mac/mac_framework.h> 127 #endif 128 #include "rack_bbr_common.h" 129 130 /* 131 * Common TCP Functions - These are shared by borth 132 * rack and BBR. 133 */ 134 #ifdef KERN_TLS 135 uint32_t 136 ctf_get_opt_tls_size(struct socket *so, uint32_t rwnd) 137 { 138 struct ktls_session *tls; 139 uint32_t len; 140 141 again: 142 tls = so->so_snd.sb_tls_info; 143 len = tls->params.max_frame_len; /* max tls payload */ 144 len += tls->params.tls_hlen; /* tls header len */ 145 len += tls->params.tls_tlen; /* tls trailer len */ 146 if ((len * 4) > rwnd) { 147 /* 148 * Stroke this will suck counter and what 149 * else should we do Drew? From the 150 * TCP perspective I am not sure 151 * what should be done... 152 */ 153 if (tls->params.max_frame_len > 4096) { 154 tls->params.max_frame_len -= 4096; 155 if (tls->params.max_frame_len < 4096) 156 tls->params.max_frame_len = 4096; 157 goto again; 158 } 159 } 160 return (len); 161 } 162 #endif 163 164 165 /* 166 * The function ctf_process_inbound_raw() is used by 167 * transport developers to do the steps needed to 168 * support MBUF Queuing i.e. the flags in 169 * inp->inp_flags2: 170 * 171 * - INP_SUPPORTS_MBUFQ 172 * - INP_MBUF_QUEUE_READY 173 * - INP_DONT_SACK_QUEUE 174 * 175 * These flags help control how LRO will deliver 176 * packets to the transport. You first set in inp_flags2 177 * the INP_SUPPORTS_MBUFQ to tell the LRO code that you 178 * will gladly take a queue of packets instead of a compressed 179 * single packet. You also set in your t_fb pointer the 180 * tfb_do_queued_segments to point to ctf_process_inbound_raw. 181 * 182 * This then gets you lists of inbound ACK's/Data instead 183 * of a condensed compressed ACK/DATA packet. Why would you 184 * want that? This will get you access to all the arrival 185 * times of at least LRO and possibly at the Hardware (if 186 * the interface card supports that) of the actual ACK/DATA. 187 * In some transport designs this is important since knowing 188 * the actual time we got the packet is useful information. 189 * 190 * Now there are some interesting Caveats that the transport 191 * designer needs to take into account when using this feature. 192 * 193 * 1) It is used with HPTS and pacing, when the pacing timer 194 * for output calls it will first call the input. 195 * 2) When you set INP_MBUF_QUEUE_READY this tells LRO 196 * queue normal packets, I am busy pacing out data and 197 * will process the queued packets before my tfb_tcp_output 198 * call from pacing. If a non-normal packet arrives, (e.g. sack) 199 * you will be awoken immediately. 200 * 3) Finally you can add the INP_DONT_SACK_QUEUE to not even 201 * be awoken if a SACK has arrived. You would do this when 202 * you were not only running a pacing for output timer 203 * but a Rack timer as well i.e. you know you are in recovery 204 * and are in the process (via the timers) of dealing with 205 * the loss. 206 * 207 * Now a critical thing you must be aware of here is that the 208 * use of the flags has a far greater scope then just your 209 * typical LRO. Why? Well thats because in the normal compressed 210 * LRO case at the end of a driver interupt all packets are going 211 * to get presented to the transport no matter if there is one 212 * or 100. With the MBUF_QUEUE model, this is not true. You will 213 * only be awoken to process the queue of packets when: 214 * a) The flags discussed above allow it. 215 * <or> 216 * b) You exceed a ack or data limit (by default the 217 * ack limit is infinity (64k acks) and the data 218 * limit is 64k of new TCP data) 219 * <or> 220 * c) The push bit has been set by the peer 221 */ 222 223 int 224 ctf_process_inbound_raw(struct tcpcb *tp, struct socket *so, struct mbuf *m, int has_pkt) 225 { 226 /* 227 * We are passed a raw change of mbuf packets 228 * that arrived in LRO. They are linked via 229 * the m_nextpkt link in the pkt-headers. 230 * 231 * We process each one by: 232 * a) saving off the next 233 * b) stripping off the ether-header 234 * c) formulating the arguments for 235 * the tfb_tcp_hpts_do_segment 236 * d) calling each mbuf to tfb_tcp_hpts_do_segment 237 * after adjusting the time to match the arrival time. 238 * Note that the LRO code assures no IP options are present. 239 * 240 * The symantics for calling tfb_tcp_hpts_do_segment are the 241 * following: 242 * 1) It returns 0 if all went well and you (the caller) need 243 * to release the lock. 244 * 2) If nxt_pkt is set, then the function will surpress calls 245 * to tfb_tcp_output() since you are promising to call again 246 * with another packet. 247 * 3) If it returns 1, then you must free all the packets being 248 * shipped in, the tcb has been destroyed (or about to be destroyed). 249 */ 250 struct mbuf *m_save; 251 struct ether_header *eh; 252 struct tcphdr *th; 253 #ifdef INET6 254 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 255 #endif 256 #ifdef INET 257 struct ip *ip = NULL; /* Keep compiler happy. */ 258 #endif 259 struct ifnet *ifp; 260 struct timeval tv; 261 int32_t retval, nxt_pkt, tlen, off; 262 uint16_t etype; 263 uint16_t drop_hdrlen; 264 uint8_t iptos, no_vn=0, bpf_req=0; 265 266 NET_EPOCH_ASSERT(); 267 268 if (m && m->m_pkthdr.rcvif) 269 ifp = m->m_pkthdr.rcvif; 270 else 271 ifp = NULL; 272 if (ifp) { 273 bpf_req = bpf_peers_present(ifp->if_bpf); 274 } else { 275 /* 276 * We probably should not work around 277 * but kassert, since lro alwasy sets rcvif. 278 */ 279 no_vn = 1; 280 goto skip_vnet; 281 } 282 CURVNET_SET(ifp->if_vnet); 283 skip_vnet: 284 while (m) { 285 m_save = m->m_nextpkt; 286 m->m_nextpkt = NULL; 287 /* Now lets get the ether header */ 288 eh = mtod(m, struct ether_header *); 289 etype = ntohs(eh->ether_type); 290 /* Let the BPF see the packet */ 291 if (bpf_req && ifp) 292 ETHER_BPF_MTAP(ifp, m); 293 m_adj(m, sizeof(*eh)); 294 /* Trim off the ethernet header */ 295 switch (etype) { 296 #ifdef INET6 297 case ETHERTYPE_IPV6: 298 { 299 if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 300 m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 301 if (m == NULL) { 302 KMOD_TCPSTAT_INC(tcps_rcvshort); 303 m_freem(m); 304 goto skipped_pkt; 305 } 306 } 307 ip6 = (struct ip6_hdr *)(eh + 1); 308 th = (struct tcphdr *)(ip6 + 1); 309 tlen = ntohs(ip6->ip6_plen); 310 drop_hdrlen = sizeof(*ip6); 311 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 312 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 313 th->th_sum = m->m_pkthdr.csum_data; 314 else 315 th->th_sum = in6_cksum_pseudo(ip6, tlen, 316 IPPROTO_TCP, m->m_pkthdr.csum_data); 317 th->th_sum ^= 0xffff; 318 } else 319 th->th_sum = in6_cksum(m, IPPROTO_TCP, drop_hdrlen, tlen); 320 if (th->th_sum) { 321 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 322 m_freem(m); 323 goto skipped_pkt; 324 } 325 /* 326 * Be proactive about unspecified IPv6 address in source. 327 * As we use all-zero to indicate unbounded/unconnected pcb, 328 * unspecified IPv6 address can be used to confuse us. 329 * 330 * Note that packets with unspecified IPv6 destination is 331 * already dropped in ip6_input. 332 */ 333 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 334 /* XXX stat */ 335 m_freem(m); 336 goto skipped_pkt; 337 } 338 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 339 break; 340 } 341 #endif 342 #ifdef INET 343 case ETHERTYPE_IP: 344 { 345 if (m->m_len < sizeof (struct tcpiphdr)) { 346 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 347 == NULL) { 348 KMOD_TCPSTAT_INC(tcps_rcvshort); 349 m_freem(m); 350 goto skipped_pkt; 351 } 352 } 353 ip = (struct ip *)(eh + 1); 354 th = (struct tcphdr *)(ip + 1); 355 drop_hdrlen = sizeof(*ip); 356 iptos = ip->ip_tos; 357 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 358 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 359 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 360 th->th_sum = m->m_pkthdr.csum_data; 361 else 362 th->th_sum = in_pseudo(ip->ip_src.s_addr, 363 ip->ip_dst.s_addr, 364 htonl(m->m_pkthdr.csum_data + tlen + 365 IPPROTO_TCP)); 366 th->th_sum ^= 0xffff; 367 } else { 368 int len; 369 struct ipovly *ipov = (struct ipovly *)ip; 370 /* 371 * Checksum extended TCP header and data. 372 */ 373 len = drop_hdrlen + tlen; 374 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 375 ipov->ih_len = htons(tlen); 376 th->th_sum = in_cksum(m, len); 377 /* Reset length for SDT probes. */ 378 ip->ip_len = htons(len); 379 /* Reset TOS bits */ 380 ip->ip_tos = iptos; 381 /* Re-initialization for later version check */ 382 ip->ip_v = IPVERSION; 383 ip->ip_hl = sizeof(*ip) >> 2; 384 } 385 if (th->th_sum) { 386 KMOD_TCPSTAT_INC(tcps_rcvbadsum); 387 m_freem(m); 388 goto skipped_pkt; 389 } 390 break; 391 } 392 #endif 393 } 394 /* 395 * Convert TCP protocol specific fields to host format. 396 */ 397 tcp_fields_to_host(th); 398 399 off = th->th_off << 2; 400 if (off < sizeof (struct tcphdr) || off > tlen) { 401 KMOD_TCPSTAT_INC(tcps_rcvbadoff); 402 m_freem(m); 403 goto skipped_pkt; 404 } 405 tlen -= off; 406 drop_hdrlen += off; 407 /* 408 * Now lets setup the timeval to be when we should 409 * have been called (if we can). 410 */ 411 m->m_pkthdr.lro_nsegs = 1; 412 if (m->m_flags & M_TSTMP_LRO) { 413 tv.tv_sec = m->m_pkthdr.rcv_tstmp /1000000000; 414 tv.tv_usec = (m->m_pkthdr.rcv_tstmp % 1000000000)/1000; 415 } else { 416 /* Should not be should we kassert instead? */ 417 tcp_get_usecs(&tv); 418 } 419 /* Now what about next packet? */ 420 if (m_save || has_pkt) 421 nxt_pkt = 1; 422 else 423 nxt_pkt = 0; 424 KMOD_TCPSTAT_INC(tcps_rcvtotal); 425 retval = (*tp->t_fb->tfb_do_segment_nounlock)(m, th, so, tp, drop_hdrlen, tlen, 426 iptos, nxt_pkt, &tv); 427 if (retval) { 428 /* We lost the lock and tcb probably */ 429 m = m_save; 430 while(m) { 431 m_save = m->m_nextpkt; 432 m->m_nextpkt = NULL; 433 m_freem(m); 434 m = m_save; 435 } 436 if (no_vn == 0) 437 CURVNET_RESTORE(); 438 return(retval); 439 } 440 skipped_pkt: 441 m = m_save; 442 } 443 if (no_vn == 0) 444 CURVNET_RESTORE(); 445 return(retval); 446 } 447 448 int 449 ctf_do_queued_segments(struct socket *so, struct tcpcb *tp, int have_pkt) 450 { 451 struct mbuf *m; 452 453 /* First lets see if we have old packets */ 454 if (tp->t_in_pkt) { 455 m = tp->t_in_pkt; 456 tp->t_in_pkt = NULL; 457 tp->t_tail_pkt = NULL; 458 if (ctf_process_inbound_raw(tp, so, m, have_pkt)) { 459 /* We lost the tcpcb (maybe a RST came in)? */ 460 return(1); 461 } 462 } 463 return (0); 464 } 465 466 uint32_t 467 ctf_outstanding(struct tcpcb *tp) 468 { 469 uint32_t bytes_out; 470 471 bytes_out = tp->snd_max - tp->snd_una; 472 if (tp->t_state < TCPS_ESTABLISHED) 473 bytes_out++; 474 if (tp->t_flags & TF_SENTFIN) 475 bytes_out++; 476 return (bytes_out); 477 } 478 479 uint32_t 480 ctf_flight_size(struct tcpcb *tp, uint32_t rc_sacked) 481 { 482 if (rc_sacked <= ctf_outstanding(tp)) 483 return(ctf_outstanding(tp) - rc_sacked); 484 else { 485 /* TSNH */ 486 #ifdef INVARIANTS 487 panic("tp:%p rc_sacked:%d > out:%d", 488 tp, rc_sacked, ctf_outstanding(tp)); 489 #endif 490 return (0); 491 } 492 } 493 494 void 495 ctf_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 496 int32_t rstreason, int32_t tlen) 497 { 498 if (tp != NULL) { 499 tcp_dropwithreset(m, th, tp, tlen, rstreason); 500 INP_WUNLOCK(tp->t_inpcb); 501 } else 502 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 503 } 504 505 /* 506 * ctf_drop_checks returns 1 for you should not proceed. It places 507 * in ret_val what should be returned 1/0 by the caller. The 1 indicates 508 * that the TCB is unlocked and probably dropped. The 0 indicates the 509 * TCB is still valid and locked. 510 */ 511 int 512 ctf_drop_checks(struct tcpopt *to, struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * tlenp, int32_t * thf, int32_t * drop_hdrlen, int32_t * ret_val) 513 { 514 int32_t todrop; 515 int32_t thflags; 516 int32_t tlen; 517 518 thflags = *thf; 519 tlen = *tlenp; 520 todrop = tp->rcv_nxt - th->th_seq; 521 if (todrop > 0) { 522 if (thflags & TH_SYN) { 523 thflags &= ~TH_SYN; 524 th->th_seq++; 525 if (th->th_urp > 1) 526 th->th_urp--; 527 else 528 thflags &= ~TH_URG; 529 todrop--; 530 } 531 /* 532 * Following if statement from Stevens, vol. 2, p. 960. 533 */ 534 if (todrop > tlen 535 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 536 /* 537 * Any valid FIN must be to the left of the window. 538 * At this point the FIN must be a duplicate or out 539 * of sequence; drop it. 540 */ 541 thflags &= ~TH_FIN; 542 /* 543 * Send an ACK to resynchronize and drop any data. 544 * But keep on processing for RST or ACK. 545 */ 546 tp->t_flags |= TF_ACKNOW; 547 todrop = tlen; 548 KMOD_TCPSTAT_INC(tcps_rcvduppack); 549 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 550 } else { 551 KMOD_TCPSTAT_INC(tcps_rcvpartduppack); 552 KMOD_TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 553 } 554 /* 555 * DSACK - add SACK block for dropped range 556 */ 557 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 558 tcp_update_sack_list(tp, th->th_seq, 559 th->th_seq + todrop); 560 /* 561 * ACK now, as the next in-sequence segment 562 * will clear the DSACK block again 563 */ 564 tp->t_flags |= TF_ACKNOW; 565 } 566 *drop_hdrlen += todrop; /* drop from the top afterwards */ 567 th->th_seq += todrop; 568 tlen -= todrop; 569 if (th->th_urp > todrop) 570 th->th_urp -= todrop; 571 else { 572 thflags &= ~TH_URG; 573 th->th_urp = 0; 574 } 575 } 576 /* 577 * If segment ends after window, drop trailing data (and PUSH and 578 * FIN); if nothing left, just ACK. 579 */ 580 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 581 if (todrop > 0) { 582 KMOD_TCPSTAT_INC(tcps_rcvpackafterwin); 583 if (todrop >= tlen) { 584 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 585 /* 586 * If window is closed can only take segments at 587 * window edge, and have to drop data and PUSH from 588 * incoming segments. Continue processing, but 589 * remember to ack. Otherwise, drop segment and 590 * ack. 591 */ 592 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 593 tp->t_flags |= TF_ACKNOW; 594 KMOD_TCPSTAT_INC(tcps_rcvwinprobe); 595 } else { 596 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 597 return (1); 598 } 599 } else 600 KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 601 m_adj(m, -todrop); 602 tlen -= todrop; 603 thflags &= ~(TH_PUSH | TH_FIN); 604 } 605 *thf = thflags; 606 *tlenp = tlen; 607 return (0); 608 } 609 610 /* 611 * The value in ret_val informs the caller 612 * if we dropped the tcb (and lock) or not. 613 * 1 = we dropped it, 0 = the TCB is still locked 614 * and valid. 615 */ 616 void 617 ctf_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t * ret_val) 618 { 619 /* 620 * Generate an ACK dropping incoming segment if it occupies sequence 621 * space, where the ACK reflects our state. 622 * 623 * We can now skip the test for the RST flag since all paths to this 624 * code happen after packets containing RST have been dropped. 625 * 626 * In the SYN-RECEIVED state, don't send an ACK unless the segment 627 * we received passes the SYN-RECEIVED ACK test. If it fails send a 628 * RST. This breaks the loop in the "LAND" DoS attack, and also 629 * prevents an ACK storm between two listening ports that have been 630 * sent forged SYN segments, each with the source address of the 631 * other. 632 */ 633 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 634 (SEQ_GT(tp->snd_una, th->th_ack) || 635 SEQ_GT(th->th_ack, tp->snd_max))) { 636 *ret_val = 1; 637 ctf_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen); 638 return; 639 } else 640 *ret_val = 0; 641 tp->t_flags |= TF_ACKNOW; 642 if (m) 643 m_freem(m); 644 } 645 646 void 647 ctf_do_drop(struct mbuf *m, struct tcpcb *tp) 648 { 649 650 /* 651 * Drop space held by incoming segment and return. 652 */ 653 if (tp != NULL) 654 INP_WUNLOCK(tp->t_inpcb); 655 if (m) 656 m_freem(m); 657 } 658 659 int 660 ctf_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, struct tcpcb *tp) 661 { 662 /* 663 * RFC5961 Section 3.2 664 * 665 * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in 666 * window, we send challenge ACK. 667 * 668 * Note: to take into account delayed ACKs, we should test against 669 * last_ack_sent instead of rcv_nxt. Note 2: we handle special case 670 * of closed window, not covered by the RFC. 671 */ 672 int dropped = 0; 673 674 if ((SEQ_GEQ(th->th_seq, (tp->last_ack_sent - 1)) && 675 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 676 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 677 678 KASSERT(tp->t_state != TCPS_SYN_SENT, 679 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 680 __func__, th, tp)); 681 682 if (V_tcp_insecure_rst || 683 (tp->last_ack_sent == th->th_seq) || 684 (tp->rcv_nxt == th->th_seq) || 685 ((tp->last_ack_sent - 1) == th->th_seq)) { 686 KMOD_TCPSTAT_INC(tcps_drops); 687 /* Drop the connection. */ 688 switch (tp->t_state) { 689 case TCPS_SYN_RECEIVED: 690 so->so_error = ECONNREFUSED; 691 goto close; 692 case TCPS_ESTABLISHED: 693 case TCPS_FIN_WAIT_1: 694 case TCPS_FIN_WAIT_2: 695 case TCPS_CLOSE_WAIT: 696 case TCPS_CLOSING: 697 case TCPS_LAST_ACK: 698 so->so_error = ECONNRESET; 699 close: 700 tcp_state_change(tp, TCPS_CLOSED); 701 /* FALLTHROUGH */ 702 default: 703 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 704 tp = tcp_close(tp); 705 } 706 dropped = 1; 707 ctf_do_drop(m, tp); 708 } else { 709 KMOD_TCPSTAT_INC(tcps_badrst); 710 /* Send challenge ACK. */ 711 tcp_respond(tp, mtod(m, void *), th, m, 712 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 713 tp->last_ack_sent = tp->rcv_nxt; 714 } 715 } else { 716 m_freem(m); 717 } 718 return (dropped); 719 } 720 721 /* 722 * The value in ret_val informs the caller 723 * if we dropped the tcb (and lock) or not. 724 * 1 = we dropped it, 0 = the TCB is still locked 725 * and valid. 726 */ 727 void 728 ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * ret_val) 729 { 730 731 NET_EPOCH_ASSERT(); 732 733 KMOD_TCPSTAT_INC(tcps_badsyn); 734 if (V_tcp_insecure_syn && 735 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 736 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 737 tp = tcp_drop(tp, ECONNRESET); 738 *ret_val = 1; 739 ctf_do_drop(m, tp); 740 } else { 741 /* Send challenge ACK. */ 742 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 743 tp->snd_nxt, TH_ACK); 744 tp->last_ack_sent = tp->rcv_nxt; 745 m = NULL; 746 *ret_val = 0; 747 ctf_do_drop(m, NULL); 748 } 749 } 750 751 /* 752 * bbr_ts_check returns 1 for you should not proceed, the state 753 * machine should return. It places in ret_val what should 754 * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates 755 * that the TCB is unlocked and probably dropped. The 0 indicates the 756 * TCB is still valid and locked. 757 */ 758 int 759 ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 760 int32_t tlen, int32_t thflags, int32_t * ret_val) 761 { 762 763 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 764 /* 765 * Invalidate ts_recent. If this segment updates ts_recent, 766 * the age will be reset later and ts_recent will get a 767 * valid value. If it does not, setting ts_recent to zero 768 * will at least satisfy the requirement that zero be placed 769 * in the timestamp echo reply when ts_recent isn't valid. 770 * The age isn't reset until we get a valid ts_recent 771 * because we don't want out-of-order segments to be dropped 772 * when ts_recent is old. 773 */ 774 tp->ts_recent = 0; 775 } else { 776 KMOD_TCPSTAT_INC(tcps_rcvduppack); 777 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 778 KMOD_TCPSTAT_INC(tcps_pawsdrop); 779 *ret_val = 0; 780 if (tlen) { 781 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 782 } else { 783 ctf_do_drop(m, NULL); 784 } 785 return (1); 786 } 787 return (0); 788 } 789 790 void 791 ctf_calc_rwin(struct socket *so, struct tcpcb *tp) 792 { 793 int32_t win; 794 795 /* 796 * Calculate amount of space in receive window, and then do TCP 797 * input processing. Receive window is amount of space in rcv queue, 798 * but not less than advertised window. 799 */ 800 win = sbspace(&so->so_rcv); 801 if (win < 0) 802 win = 0; 803 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 804 } 805 806 void 807 ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 808 int32_t rstreason, int32_t tlen) 809 { 810 811 if (tp->t_inpcb) { 812 tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT); 813 } 814 tcp_dropwithreset(m, th, tp, tlen, rstreason); 815 INP_WUNLOCK(tp->t_inpcb); 816 } 817 818 uint32_t 819 ctf_fixed_maxseg(struct tcpcb *tp) 820 { 821 int optlen; 822 823 if (tp->t_flags & TF_NOOPT) 824 return (tp->t_maxseg); 825 826 /* 827 * Here we have a simplified code from tcp_addoptions(), 828 * without a proper loop, and having most of paddings hardcoded. 829 * We only consider fixed options that we would send every 830 * time I.e. SACK is not considered. 831 * 832 */ 833 #define PAD(len) ((((len) / 4) + !!((len) % 4)) * 4) 834 if (TCPS_HAVEESTABLISHED(tp->t_state)) { 835 if (tp->t_flags & TF_RCVD_TSTMP) 836 optlen = TCPOLEN_TSTAMP_APPA; 837 else 838 optlen = 0; 839 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 840 if (tp->t_flags & TF_SIGNATURE) 841 optlen += PAD(TCPOLEN_SIGNATURE); 842 #endif 843 } else { 844 if (tp->t_flags & TF_REQ_TSTMP) 845 optlen = TCPOLEN_TSTAMP_APPA; 846 else 847 optlen = PAD(TCPOLEN_MAXSEG); 848 if (tp->t_flags & TF_REQ_SCALE) 849 optlen += PAD(TCPOLEN_WINDOW); 850 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 851 if (tp->t_flags & TF_SIGNATURE) 852 optlen += PAD(TCPOLEN_SIGNATURE); 853 #endif 854 if (tp->t_flags & TF_SACK_PERMIT) 855 optlen += PAD(TCPOLEN_SACK_PERMITTED); 856 } 857 #undef PAD 858 optlen = min(optlen, TCP_MAXOLEN); 859 return (tp->t_maxseg - optlen); 860 } 861 862 void 863 ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) 864 { 865 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 866 union tcp_log_stackspecific log; 867 struct timeval tv; 868 869 memset(&log, 0, sizeof(log)); 870 log.u_bbr.timeStamp = tcp_get_usecs(&tv); 871 log.u_bbr.flex8 = num_sack_blks; 872 if (num_sack_blks > 0) { 873 log.u_bbr.flex1 = sack_blocks[0].start; 874 log.u_bbr.flex2 = sack_blocks[0].end; 875 } 876 if (num_sack_blks > 1) { 877 log.u_bbr.flex3 = sack_blocks[1].start; 878 log.u_bbr.flex4 = sack_blocks[1].end; 879 } 880 if (num_sack_blks > 2) { 881 log.u_bbr.flex5 = sack_blocks[2].start; 882 log.u_bbr.flex6 = sack_blocks[2].end; 883 } 884 if (num_sack_blks > 3) { 885 log.u_bbr.applimited = sack_blocks[3].start; 886 log.u_bbr.pkts_out = sack_blocks[3].end; 887 } 888 TCP_LOG_EVENTP(tp, NULL, 889 &tp->t_inpcb->inp_socket->so_rcv, 890 &tp->t_inpcb->inp_socket->so_snd, 891 TCP_SACK_FILTER_RES, 0, 892 0, &log, false, &tv); 893 } 894 } 895 896 uint32_t 897 ctf_decay_count(uint32_t count, uint32_t decay) 898 { 899 /* 900 * Given a count, decay it by a set percentage. The 901 * percentage is in thousands i.e. 100% = 1000, 902 * 19.3% = 193. 903 */ 904 uint64_t perc_count, decay_per; 905 uint32_t decayed_count; 906 if (decay > 1000) { 907 /* We don't raise it */ 908 return (count); 909 } 910 perc_count = count; 911 decay_per = decay; 912 perc_count *= decay_per; 913 perc_count /= 1000; 914 /* 915 * So now perc_count holds the 916 * count decay value. 917 */ 918 decayed_count = count - (uint32_t)perc_count; 919 return(decayed_count); 920 } 921 922 int32_t 923 ctf_progress_timeout_check(struct tcpcb *tp, bool log) 924 { 925 if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) { 926 if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) { 927 /* 928 * There is an assumption that the caller 929 * will drop the connection so we will 930 * increment the counters here. 931 */ 932 if (log) 933 tcp_log_end_status(tp, TCP_EI_STATUS_PROGRESS); 934 #ifdef NETFLIX_STATS 935 KMOD_TCPSTAT_INC(tcps_progdrops); 936 #endif 937 return (1); 938 } 939 } 940 return (0); 941 } 942