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