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 tcp_handle_wakeup(tp, so); 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 KASSERT(tp->t_state != TCPS_SYN_SENT, 678 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 679 __func__, th, tp)); 680 681 if (V_tcp_insecure_rst || 682 (tp->last_ack_sent == th->th_seq) || 683 (tp->rcv_nxt == th->th_seq) || 684 ((tp->last_ack_sent - 1) == th->th_seq)) { 685 KMOD_TCPSTAT_INC(tcps_drops); 686 /* Drop the connection. */ 687 switch (tp->t_state) { 688 case TCPS_SYN_RECEIVED: 689 so->so_error = ECONNREFUSED; 690 goto close; 691 case TCPS_ESTABLISHED: 692 case TCPS_FIN_WAIT_1: 693 case TCPS_FIN_WAIT_2: 694 case TCPS_CLOSE_WAIT: 695 case TCPS_CLOSING: 696 case TCPS_LAST_ACK: 697 so->so_error = ECONNRESET; 698 close: 699 tcp_state_change(tp, TCPS_CLOSED); 700 /* FALLTHROUGH */ 701 default: 702 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 703 tp = tcp_close(tp); 704 } 705 dropped = 1; 706 ctf_do_drop(m, tp); 707 } else { 708 KMOD_TCPSTAT_INC(tcps_badrst); 709 /* Send challenge ACK. */ 710 tcp_respond(tp, mtod(m, void *), th, m, 711 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 712 tp->last_ack_sent = tp->rcv_nxt; 713 } 714 } else { 715 m_freem(m); 716 } 717 return (dropped); 718 } 719 720 /* 721 * The value in ret_val informs the caller 722 * if we dropped the tcb (and lock) or not. 723 * 1 = we dropped it, 0 = the TCB is still locked 724 * and valid. 725 */ 726 void 727 ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * ret_val) 728 { 729 730 NET_EPOCH_ASSERT(); 731 732 KMOD_TCPSTAT_INC(tcps_badsyn); 733 if (V_tcp_insecure_syn && 734 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 735 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 736 tp = tcp_drop(tp, ECONNRESET); 737 *ret_val = 1; 738 ctf_do_drop(m, tp); 739 } else { 740 /* Send challenge ACK. */ 741 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 742 tp->snd_nxt, TH_ACK); 743 tp->last_ack_sent = tp->rcv_nxt; 744 m = NULL; 745 *ret_val = 0; 746 ctf_do_drop(m, NULL); 747 } 748 } 749 750 /* 751 * bbr_ts_check returns 1 for you should not proceed, the state 752 * machine should return. It places in ret_val what should 753 * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates 754 * that the TCB is unlocked and probably dropped. The 0 indicates the 755 * TCB is still valid and locked. 756 */ 757 int 758 ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 759 int32_t tlen, int32_t thflags, int32_t * ret_val) 760 { 761 762 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 763 /* 764 * Invalidate ts_recent. If this segment updates ts_recent, 765 * the age will be reset later and ts_recent will get a 766 * valid value. If it does not, setting ts_recent to zero 767 * will at least satisfy the requirement that zero be placed 768 * in the timestamp echo reply when ts_recent isn't valid. 769 * The age isn't reset until we get a valid ts_recent 770 * because we don't want out-of-order segments to be dropped 771 * when ts_recent is old. 772 */ 773 tp->ts_recent = 0; 774 } else { 775 KMOD_TCPSTAT_INC(tcps_rcvduppack); 776 KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 777 KMOD_TCPSTAT_INC(tcps_pawsdrop); 778 *ret_val = 0; 779 if (tlen) { 780 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 781 } else { 782 ctf_do_drop(m, NULL); 783 } 784 return (1); 785 } 786 return (0); 787 } 788 789 void 790 ctf_calc_rwin(struct socket *so, struct tcpcb *tp) 791 { 792 int32_t win; 793 794 /* 795 * Calculate amount of space in receive window, and then do TCP 796 * input processing. Receive window is amount of space in rcv queue, 797 * but not less than advertised window. 798 */ 799 win = sbspace(&so->so_rcv); 800 if (win < 0) 801 win = 0; 802 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 803 } 804 805 void 806 ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 807 int32_t rstreason, int32_t tlen) 808 { 809 810 if (tp->t_inpcb) { 811 tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT); 812 } 813 tcp_dropwithreset(m, th, tp, tlen, rstreason); 814 INP_WUNLOCK(tp->t_inpcb); 815 } 816 817 uint32_t 818 ctf_fixed_maxseg(struct tcpcb *tp) 819 { 820 int optlen; 821 822 if (tp->t_flags & TF_NOOPT) 823 return (tp->t_maxseg); 824 825 /* 826 * Here we have a simplified code from tcp_addoptions(), 827 * without a proper loop, and having most of paddings hardcoded. 828 * We only consider fixed options that we would send every 829 * time I.e. SACK is not considered. 830 * 831 */ 832 #define PAD(len) ((((len) / 4) + !!((len) % 4)) * 4) 833 if (TCPS_HAVEESTABLISHED(tp->t_state)) { 834 if (tp->t_flags & TF_RCVD_TSTMP) 835 optlen = TCPOLEN_TSTAMP_APPA; 836 else 837 optlen = 0; 838 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 839 if (tp->t_flags & TF_SIGNATURE) 840 optlen += PAD(TCPOLEN_SIGNATURE); 841 #endif 842 } else { 843 if (tp->t_flags & TF_REQ_TSTMP) 844 optlen = TCPOLEN_TSTAMP_APPA; 845 else 846 optlen = PAD(TCPOLEN_MAXSEG); 847 if (tp->t_flags & TF_REQ_SCALE) 848 optlen += PAD(TCPOLEN_WINDOW); 849 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 850 if (tp->t_flags & TF_SIGNATURE) 851 optlen += PAD(TCPOLEN_SIGNATURE); 852 #endif 853 if (tp->t_flags & TF_SACK_PERMIT) 854 optlen += PAD(TCPOLEN_SACK_PERMITTED); 855 } 856 #undef PAD 857 optlen = min(optlen, TCP_MAXOLEN); 858 return (tp->t_maxseg - optlen); 859 } 860 861 void 862 ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) 863 { 864 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 865 union tcp_log_stackspecific log; 866 struct timeval tv; 867 868 memset(&log, 0, sizeof(log)); 869 log.u_bbr.timeStamp = tcp_get_usecs(&tv); 870 log.u_bbr.flex8 = num_sack_blks; 871 if (num_sack_blks > 0) { 872 log.u_bbr.flex1 = sack_blocks[0].start; 873 log.u_bbr.flex2 = sack_blocks[0].end; 874 } 875 if (num_sack_blks > 1) { 876 log.u_bbr.flex3 = sack_blocks[1].start; 877 log.u_bbr.flex4 = sack_blocks[1].end; 878 } 879 if (num_sack_blks > 2) { 880 log.u_bbr.flex5 = sack_blocks[2].start; 881 log.u_bbr.flex6 = sack_blocks[2].end; 882 } 883 if (num_sack_blks > 3) { 884 log.u_bbr.applimited = sack_blocks[3].start; 885 log.u_bbr.pkts_out = sack_blocks[3].end; 886 } 887 TCP_LOG_EVENTP(tp, NULL, 888 &tp->t_inpcb->inp_socket->so_rcv, 889 &tp->t_inpcb->inp_socket->so_snd, 890 TCP_SACK_FILTER_RES, 0, 891 0, &log, false, &tv); 892 } 893 } 894 895 uint32_t 896 ctf_decay_count(uint32_t count, uint32_t decay) 897 { 898 /* 899 * Given a count, decay it by a set percentage. The 900 * percentage is in thousands i.e. 100% = 1000, 901 * 19.3% = 193. 902 */ 903 uint64_t perc_count, decay_per; 904 uint32_t decayed_count; 905 if (decay > 1000) { 906 /* We don't raise it */ 907 return (count); 908 } 909 perc_count = count; 910 decay_per = decay; 911 perc_count *= decay_per; 912 perc_count /= 1000; 913 /* 914 * So now perc_count holds the 915 * count decay value. 916 */ 917 decayed_count = count - (uint32_t)perc_count; 918 return(decayed_count); 919 } 920 921 int32_t 922 ctf_progress_timeout_check(struct tcpcb *tp, bool log) 923 { 924 if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) { 925 if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) { 926 /* 927 * There is an assumption that the caller 928 * will drop the connection so we will 929 * increment the counters here. 930 */ 931 if (log) 932 tcp_log_end_status(tp, TCP_EI_STATUS_PROGRESS); 933 #ifdef NETFLIX_STATS 934 KMOD_TCPSTAT_INC(tcps_progdrops); 935 #endif 936 return (1); 937 } 938 } 939 return (0); 940 } 941