1 /*- 2 * Copyright (c) 2016-9 3 * Netflix Inc. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 * 27 */ 28 /* 29 * Author: Randall Stewart <rrs@netflix.com> 30 * This work is based on the ACM Queue paper 31 * BBR - Congestion Based Congestion Control 32 * and also numerous discussions with Neal, Yuchung and Van. 33 */ 34 35 #include <sys/cdefs.h> 36 __FBSDID("$FreeBSD$"); 37 38 #include "opt_inet.h" 39 #include "opt_inet6.h" 40 #include "opt_ipsec.h" 41 #include "opt_tcpdebug.h" 42 #include "opt_ratelimit.h" 43 #include "opt_kern_tls.h" 44 #include <sys/param.h> 45 #include <sys/arb.h> 46 #include <sys/module.h> 47 #include <sys/kernel.h> 48 #ifdef TCP_HHOOK 49 #include <sys/hhook.h> 50 #endif 51 #include <sys/malloc.h> 52 #include <sys/mbuf.h> 53 #include <sys/proc.h> 54 #include <sys/qmath.h> 55 #include <sys/socket.h> 56 #include <sys/socketvar.h> 57 #ifdef KERN_TLS 58 #include <sys/ktls.h> 59 #endif 60 #include <sys/sysctl.h> 61 #include <sys/systm.h> 62 #include <sys/tree.h> 63 #ifdef NETFLIX_STATS 64 #include <sys/stats.h> /* Must come after qmath.h and tree.h */ 65 #endif 66 #include <sys/refcount.h> 67 #include <sys/queue.h> 68 #include <sys/smp.h> 69 #include <sys/kthread.h> 70 #include <sys/lock.h> 71 #include <sys/mutex.h> 72 #include <sys/tim_filter.h> 73 #include <sys/time.h> 74 #include <vm/uma.h> 75 #include <sys/kern_prefetch.h> 76 77 #include <net/route.h> 78 #include <net/vnet.h> 79 #include <net/ethernet.h> 80 #include <net/bpf.h> 81 82 #define TCPSTATES /* for logging */ 83 84 #include <netinet/in.h> 85 #include <netinet/in_kdtrace.h> 86 #include <netinet/in_pcb.h> 87 #include <netinet/ip.h> 88 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 89 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 90 #include <netinet/ip_var.h> 91 #include <netinet/ip6.h> 92 #include <netinet6/in6_pcb.h> 93 #include <netinet6/ip6_var.h> 94 #define TCPOUTFLAGS 95 #include <netinet/tcp.h> 96 #include <netinet/tcp_fsm.h> 97 #include <netinet/tcp_seq.h> 98 #include <netinet/tcp_timer.h> 99 #include <netinet/tcp_var.h> 100 #include <netinet/tcpip.h> 101 #include <netinet/tcp_hpts.h> 102 #include <netinet/cc/cc.h> 103 #include <netinet/tcp_log_buf.h> 104 #ifdef TCPDEBUG 105 #include <netinet/tcp_debug.h> 106 #endif /* TCPDEBUG */ 107 #ifdef TCP_OFFLOAD 108 #include <netinet/tcp_offload.h> 109 #endif 110 #ifdef INET6 111 #include <netinet6/tcp6_var.h> 112 #endif 113 #include <netinet/tcp_fastopen.h> 114 115 #include <netipsec/ipsec_support.h> 116 #include <net/if.h> 117 #include <net/if_var.h> 118 119 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 120 #include <netipsec/ipsec.h> 121 #include <netipsec/ipsec6.h> 122 #endif /* IPSEC */ 123 124 #include <netinet/udp.h> 125 #include <netinet/udp_var.h> 126 #include <machine/in_cksum.h> 127 128 #ifdef MAC 129 #include <security/mac/mac_framework.h> 130 #endif 131 #include "rack_bbr_common.h" 132 133 /* 134 * Common TCP Functions - These are shared by borth 135 * rack and BBR. 136 */ 137 #ifdef KERN_TLS 138 uint32_t 139 ctf_get_opt_tls_size(struct socket *so, uint32_t rwnd) 140 { 141 struct ktls_session *tls; 142 uint32_t len; 143 144 again: 145 tls = so->so_snd.sb_tls_info; 146 len = tls->params.max_frame_len; /* max tls payload */ 147 len += tls->params.tls_hlen; /* tls header len */ 148 len += tls->params.tls_tlen; /* tls trailer len */ 149 if ((len * 4) > rwnd) { 150 /* 151 * Stroke this will suck counter and what 152 * else should we do Drew? From the 153 * TCP perspective I am not sure 154 * what should be done... 155 */ 156 if (tls->params.max_frame_len > 4096) { 157 tls->params.max_frame_len -= 4096; 158 if (tls->params.max_frame_len < 4096) 159 tls->params.max_frame_len = 4096; 160 goto again; 161 } 162 } 163 return (len); 164 } 165 #endif 166 167 168 /* 169 * The function ctf_process_inbound_raw() is used by 170 * transport developers to do the steps needed to 171 * support MBUF Queuing i.e. the flags in 172 * inp->inp_flags2: 173 * 174 * - INP_SUPPORTS_MBUFQ 175 * - INP_MBUF_QUEUE_READY 176 * - INP_DONT_SACK_QUEUE 177 * 178 * These flags help control how LRO will deliver 179 * packets to the transport. You first set in inp_flags2 180 * the INP_SUPPORTS_MBUFQ to tell the LRO code that you 181 * will gladly take a queue of packets instead of a compressed 182 * single packet. You also set in your t_fb pointer the 183 * tfb_do_queued_segments to point to ctf_process_inbound_raw. 184 * 185 * This then gets you lists of inbound ACK's/Data instead 186 * of a condensed compressed ACK/DATA packet. Why would you 187 * want that? This will get you access to all the arrival 188 * times of at least LRO and possibly at the Hardware (if 189 * the interface card supports that) of the actual ACK/DATA. 190 * In some transport designs this is important since knowing 191 * the actual time we got the packet is useful information. 192 * 193 * Now there are some interesting Caveats that the transport 194 * designer needs to take into account when using this feature. 195 * 196 * 1) It is used with HPTS and pacing, when the pacing timer 197 * for output calls it will first call the input. 198 * 2) When you set INP_MBUF_QUEUE_READY this tells LRO 199 * queue normal packets, I am busy pacing out data and 200 * will process the queued packets before my tfb_tcp_output 201 * call from pacing. If a non-normal packet arrives, (e.g. sack) 202 * you will be awoken immediately. 203 * 3) Finally you can add the INP_DONT_SACK_QUEUE to not even 204 * be awoken if a SACK has arrived. You would do this when 205 * you were not only running a pacing for output timer 206 * but a Rack timer as well i.e. you know you are in recovery 207 * and are in the process (via the timers) of dealing with 208 * the loss. 209 * 210 * Now a critical thing you must be aware of here is that the 211 * use of the flags has a far greater scope then just your 212 * typical LRO. Why? Well thats because in the normal compressed 213 * LRO case at the end of a driver interupt all packets are going 214 * to get presented to the transport no matter if there is one 215 * or 100. With the MBUF_QUEUE model, this is not true. You will 216 * only be awoken to process the queue of packets when: 217 * a) The flags discussed above allow it. 218 * <or> 219 * b) You exceed a ack or data limit (by default the 220 * ack limit is infinity (64k acks) and the data 221 * limit is 64k of new TCP data) 222 * <or> 223 * c) The push bit has been set by the peer 224 */ 225 226 int 227 ctf_process_inbound_raw(struct tcpcb *tp, struct socket *so, struct mbuf *m, int has_pkt) 228 { 229 /* 230 * We are passed a raw change of mbuf packets 231 * that arrived in LRO. They are linked via 232 * the m_nextpkt link in the pkt-headers. 233 * 234 * We process each one by: 235 * a) saving off the next 236 * b) stripping off the ether-header 237 * c) formulating the arguments for 238 * the tfb_tcp_hpts_do_segment 239 * d) calling each mbuf to tfb_tcp_hpts_do_segment 240 * after adjusting the time to match the arrival time. 241 * Note that the LRO code assures no IP options are present. 242 * 243 * The symantics for calling tfb_tcp_hpts_do_segment are the 244 * following: 245 * 1) It returns 0 if all went well and you (the caller) need 246 * to release the lock. 247 * 2) If nxt_pkt is set, then the function will surpress calls 248 * to tfb_tcp_output() since you are promising to call again 249 * with another packet. 250 * 3) If it returns 1, then you must free all the packets being 251 * shipped in, the tcb has been destroyed (or about to be destroyed). 252 */ 253 struct mbuf *m_save; 254 struct ether_header *eh; 255 struct tcphdr *th; 256 #ifdef INET6 257 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ 258 #endif 259 #ifdef INET 260 struct ip *ip = NULL; /* Keep compiler happy. */ 261 #endif 262 struct ifnet *ifp; 263 struct timeval tv; 264 int32_t retval, nxt_pkt, tlen, off; 265 uint16_t etype; 266 uint16_t drop_hdrlen; 267 uint8_t iptos, no_vn=0, bpf_req=0; 268 269 NET_EPOCH_ASSERT(); 270 271 if (m && m->m_pkthdr.rcvif) 272 ifp = m->m_pkthdr.rcvif; 273 else 274 ifp = NULL; 275 if (ifp) { 276 bpf_req = bpf_peers_present(ifp->if_bpf); 277 } else { 278 /* 279 * We probably should not work around 280 * but kassert, since lro alwasy sets rcvif. 281 */ 282 no_vn = 1; 283 goto skip_vnet; 284 } 285 CURVNET_SET(ifp->if_vnet); 286 skip_vnet: 287 while (m) { 288 m_save = m->m_nextpkt; 289 m->m_nextpkt = NULL; 290 /* Now lets get the ether header */ 291 eh = mtod(m, struct ether_header *); 292 etype = ntohs(eh->ether_type); 293 /* Let the BPF see the packet */ 294 if (bpf_req && ifp) 295 ETHER_BPF_MTAP(ifp, m); 296 m_adj(m, sizeof(*eh)); 297 /* Trim off the ethernet header */ 298 switch (etype) { 299 #ifdef INET6 300 case ETHERTYPE_IPV6: 301 { 302 if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { 303 m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); 304 if (m == NULL) { 305 TCPSTAT_INC(tcps_rcvshort); 306 m_freem(m); 307 goto skipped_pkt; 308 } 309 } 310 ip6 = (struct ip6_hdr *)(eh + 1); 311 th = (struct tcphdr *)(ip6 + 1); 312 tlen = ntohs(ip6->ip6_plen); 313 drop_hdrlen = sizeof(*ip6); 314 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 315 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 316 th->th_sum = m->m_pkthdr.csum_data; 317 else 318 th->th_sum = in6_cksum_pseudo(ip6, tlen, 319 IPPROTO_TCP, m->m_pkthdr.csum_data); 320 th->th_sum ^= 0xffff; 321 } else 322 th->th_sum = in6_cksum(m, IPPROTO_TCP, drop_hdrlen, tlen); 323 if (th->th_sum) { 324 TCPSTAT_INC(tcps_rcvbadsum); 325 m_freem(m); 326 goto skipped_pkt; 327 } 328 /* 329 * Be proactive about unspecified IPv6 address in source. 330 * As we use all-zero to indicate unbounded/unconnected pcb, 331 * unspecified IPv6 address can be used to confuse us. 332 * 333 * Note that packets with unspecified IPv6 destination is 334 * already dropped in ip6_input. 335 */ 336 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 337 /* XXX stat */ 338 m_freem(m); 339 goto skipped_pkt; 340 } 341 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 342 break; 343 } 344 #endif 345 #ifdef INET 346 case ETHERTYPE_IP: 347 { 348 if (m->m_len < sizeof (struct tcpiphdr)) { 349 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 350 == NULL) { 351 TCPSTAT_INC(tcps_rcvshort); 352 m_freem(m); 353 goto skipped_pkt; 354 } 355 } 356 ip = (struct ip *)(eh + 1); 357 th = (struct tcphdr *)(ip + 1); 358 drop_hdrlen = sizeof(*ip); 359 iptos = ip->ip_tos; 360 tlen = ntohs(ip->ip_len) - sizeof(struct ip); 361 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 362 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 363 th->th_sum = m->m_pkthdr.csum_data; 364 else 365 th->th_sum = in_pseudo(ip->ip_src.s_addr, 366 ip->ip_dst.s_addr, 367 htonl(m->m_pkthdr.csum_data + tlen + 368 IPPROTO_TCP)); 369 th->th_sum ^= 0xffff; 370 } else { 371 int len; 372 struct ipovly *ipov = (struct ipovly *)ip; 373 /* 374 * Checksum extended TCP header and data. 375 */ 376 len = drop_hdrlen + tlen; 377 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 378 ipov->ih_len = htons(tlen); 379 th->th_sum = in_cksum(m, len); 380 /* Reset length for SDT probes. */ 381 ip->ip_len = htons(len); 382 /* Reset TOS bits */ 383 ip->ip_tos = iptos; 384 /* Re-initialization for later version check */ 385 ip->ip_v = IPVERSION; 386 ip->ip_hl = sizeof(*ip) >> 2; 387 } 388 if (th->th_sum) { 389 TCPSTAT_INC(tcps_rcvbadsum); 390 m_freem(m); 391 goto skipped_pkt; 392 } 393 break; 394 } 395 #endif 396 } 397 /* 398 * Convert TCP protocol specific fields to host format. 399 */ 400 tcp_fields_to_host(th); 401 402 off = th->th_off << 2; 403 if (off < sizeof (struct tcphdr) || off > tlen) { 404 TCPSTAT_INC(tcps_rcvbadoff); 405 m_freem(m); 406 goto skipped_pkt; 407 } 408 tlen -= off; 409 drop_hdrlen += off; 410 /* 411 * Now lets setup the timeval to be when we should 412 * have been called (if we can). 413 */ 414 m->m_pkthdr.lro_nsegs = 1; 415 if (m->m_flags & M_TSTMP_LRO) { 416 tv.tv_sec = m->m_pkthdr.rcv_tstmp /1000000000; 417 tv.tv_usec = (m->m_pkthdr.rcv_tstmp % 1000000000)/1000; 418 } else { 419 /* Should not be should we kassert instead? */ 420 tcp_get_usecs(&tv); 421 } 422 /* Now what about next packet? */ 423 if (m_save || has_pkt) 424 nxt_pkt = 1; 425 else 426 nxt_pkt = 0; 427 retval = (*tp->t_fb->tfb_do_segment_nounlock)(m, th, so, tp, drop_hdrlen, tlen, 428 iptos, nxt_pkt, &tv); 429 if (retval) { 430 /* We lost the lock and tcb probably */ 431 m = m_save; 432 while(m) { 433 m_save = m->m_nextpkt; 434 m->m_nextpkt = NULL; 435 m_freem(m); 436 m = m_save; 437 } 438 if (no_vn == 0) 439 CURVNET_RESTORE(); 440 return(retval); 441 } 442 skipped_pkt: 443 m = m_save; 444 } 445 if (no_vn == 0) 446 CURVNET_RESTORE(); 447 return(retval); 448 } 449 450 int 451 ctf_do_queued_segments(struct socket *so, struct tcpcb *tp, int have_pkt) 452 { 453 struct mbuf *m; 454 455 /* First lets see if we have old packets */ 456 if (tp->t_in_pkt) { 457 m = tp->t_in_pkt; 458 tp->t_in_pkt = NULL; 459 tp->t_tail_pkt = NULL; 460 if (ctf_process_inbound_raw(tp, so, m, have_pkt)) { 461 /* We lost the tcpcb (maybe a RST came in)? */ 462 return(1); 463 } 464 } 465 return (0); 466 } 467 468 uint32_t 469 ctf_outstanding(struct tcpcb *tp) 470 { 471 return(tp->snd_max - tp->snd_una); 472 } 473 474 uint32_t 475 ctf_flight_size(struct tcpcb *tp, uint32_t rc_sacked) 476 { 477 if (rc_sacked <= ctf_outstanding(tp)) 478 return(ctf_outstanding(tp) - rc_sacked); 479 else { 480 /* TSNH */ 481 #ifdef INVARIANTS 482 panic("tp:%p rc_sacked:%d > out:%d", 483 tp, rc_sacked, ctf_outstanding(tp)); 484 #endif 485 return (0); 486 } 487 } 488 489 void 490 ctf_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 491 int32_t rstreason, int32_t tlen) 492 { 493 if (tp != NULL) { 494 tcp_dropwithreset(m, th, tp, tlen, rstreason); 495 INP_WUNLOCK(tp->t_inpcb); 496 } else 497 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 498 } 499 500 /* 501 * ctf_drop_checks returns 1 for you should not proceed. It places 502 * in ret_val what should be returned 1/0 by the caller. The 1 indicates 503 * that the TCB is unlocked and probably dropped. The 0 indicates the 504 * TCB is still valid and locked. 505 */ 506 int 507 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) 508 { 509 int32_t todrop; 510 int32_t thflags; 511 int32_t tlen; 512 513 thflags = *thf; 514 tlen = *tlenp; 515 todrop = tp->rcv_nxt - th->th_seq; 516 if (todrop > 0) { 517 if (thflags & TH_SYN) { 518 thflags &= ~TH_SYN; 519 th->th_seq++; 520 if (th->th_urp > 1) 521 th->th_urp--; 522 else 523 thflags &= ~TH_URG; 524 todrop--; 525 } 526 /* 527 * Following if statement from Stevens, vol. 2, p. 960. 528 */ 529 if (todrop > tlen 530 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 531 /* 532 * Any valid FIN must be to the left of the window. 533 * At this point the FIN must be a duplicate or out 534 * of sequence; drop it. 535 */ 536 thflags &= ~TH_FIN; 537 /* 538 * Send an ACK to resynchronize and drop any data. 539 * But keep on processing for RST or ACK. 540 */ 541 tp->t_flags |= TF_ACKNOW; 542 todrop = tlen; 543 TCPSTAT_INC(tcps_rcvduppack); 544 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 545 } else { 546 TCPSTAT_INC(tcps_rcvpartduppack); 547 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 548 } 549 /* 550 * DSACK - add SACK block for dropped range 551 */ 552 if (tp->t_flags & TF_SACK_PERMIT) { 553 tcp_update_sack_list(tp, th->th_seq, 554 th->th_seq + todrop); 555 /* 556 * ACK now, as the next in-sequence segment 557 * will clear the DSACK block again 558 */ 559 tp->t_flags |= TF_ACKNOW; 560 } 561 *drop_hdrlen += todrop; /* drop from the top afterwards */ 562 th->th_seq += todrop; 563 tlen -= todrop; 564 if (th->th_urp > todrop) 565 th->th_urp -= todrop; 566 else { 567 thflags &= ~TH_URG; 568 th->th_urp = 0; 569 } 570 } 571 /* 572 * If segment ends after window, drop trailing data (and PUSH and 573 * FIN); if nothing left, just ACK. 574 */ 575 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 576 if (todrop > 0) { 577 TCPSTAT_INC(tcps_rcvpackafterwin); 578 if (todrop >= tlen) { 579 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 580 /* 581 * If window is closed can only take segments at 582 * window edge, and have to drop data and PUSH from 583 * incoming segments. Continue processing, but 584 * remember to ack. Otherwise, drop segment and 585 * ack. 586 */ 587 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 588 tp->t_flags |= TF_ACKNOW; 589 TCPSTAT_INC(tcps_rcvwinprobe); 590 } else { 591 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 592 return (1); 593 } 594 } else 595 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 596 m_adj(m, -todrop); 597 tlen -= todrop; 598 thflags &= ~(TH_PUSH | TH_FIN); 599 } 600 *thf = thflags; 601 *tlenp = tlen; 602 return (0); 603 } 604 605 /* 606 * The value in ret_val informs the caller 607 * if we dropped the tcb (and lock) or not. 608 * 1 = we dropped it, 0 = the TCB is still locked 609 * and valid. 610 */ 611 void 612 ctf_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t * ret_val) 613 { 614 /* 615 * Generate an ACK dropping incoming segment if it occupies sequence 616 * space, where the ACK reflects our state. 617 * 618 * We can now skip the test for the RST flag since all paths to this 619 * code happen after packets containing RST have been dropped. 620 * 621 * In the SYN-RECEIVED state, don't send an ACK unless the segment 622 * we received passes the SYN-RECEIVED ACK test. If it fails send a 623 * RST. This breaks the loop in the "LAND" DoS attack, and also 624 * prevents an ACK storm between two listening ports that have been 625 * sent forged SYN segments, each with the source address of the 626 * other. 627 */ 628 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 629 (SEQ_GT(tp->snd_una, th->th_ack) || 630 SEQ_GT(th->th_ack, tp->snd_max))) { 631 *ret_val = 1; 632 ctf_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen); 633 return; 634 } else 635 *ret_val = 0; 636 tp->t_flags |= TF_ACKNOW; 637 if (m) 638 m_freem(m); 639 } 640 641 void 642 ctf_do_drop(struct mbuf *m, struct tcpcb *tp) 643 { 644 645 /* 646 * Drop space held by incoming segment and return. 647 */ 648 if (tp != NULL) 649 INP_WUNLOCK(tp->t_inpcb); 650 if (m) 651 m_freem(m); 652 } 653 654 int 655 ctf_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, struct tcpcb *tp) 656 { 657 /* 658 * RFC5961 Section 3.2 659 * 660 * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in 661 * window, we send challenge ACK. 662 * 663 * Note: to take into account delayed ACKs, we should test against 664 * last_ack_sent instead of rcv_nxt. Note 2: we handle special case 665 * of closed window, not covered by the RFC. 666 */ 667 int dropped = 0; 668 669 if ((SEQ_GEQ(th->th_seq, (tp->last_ack_sent - 1)) && 670 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 671 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 672 673 KASSERT(tp->t_state != TCPS_SYN_SENT, 674 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 675 __func__, th, tp)); 676 677 if (V_tcp_insecure_rst || 678 (tp->last_ack_sent == th->th_seq) || 679 (tp->rcv_nxt == th->th_seq) || 680 ((tp->last_ack_sent - 1) == th->th_seq)) { 681 TCPSTAT_INC(tcps_drops); 682 /* Drop the connection. */ 683 switch (tp->t_state) { 684 case TCPS_SYN_RECEIVED: 685 so->so_error = ECONNREFUSED; 686 goto close; 687 case TCPS_ESTABLISHED: 688 case TCPS_FIN_WAIT_1: 689 case TCPS_FIN_WAIT_2: 690 case TCPS_CLOSE_WAIT: 691 case TCPS_CLOSING: 692 case TCPS_LAST_ACK: 693 so->so_error = ECONNRESET; 694 close: 695 tcp_state_change(tp, TCPS_CLOSED); 696 /* FALLTHROUGH */ 697 default: 698 tp = tcp_close(tp); 699 } 700 dropped = 1; 701 ctf_do_drop(m, tp); 702 } else { 703 TCPSTAT_INC(tcps_badrst); 704 /* Send challenge ACK. */ 705 tcp_respond(tp, mtod(m, void *), th, m, 706 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 707 tp->last_ack_sent = tp->rcv_nxt; 708 } 709 } else { 710 m_freem(m); 711 } 712 return (dropped); 713 } 714 715 /* 716 * The value in ret_val informs the caller 717 * if we dropped the tcb (and lock) or not. 718 * 1 = we dropped it, 0 = the TCB is still locked 719 * and valid. 720 */ 721 void 722 ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t * ret_val) 723 { 724 725 NET_EPOCH_ASSERT(); 726 727 TCPSTAT_INC(tcps_badsyn); 728 if (V_tcp_insecure_syn && 729 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 730 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 731 tp = tcp_drop(tp, ECONNRESET); 732 *ret_val = 1; 733 ctf_do_drop(m, tp); 734 } else { 735 /* Send challenge ACK. */ 736 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 737 tp->snd_nxt, TH_ACK); 738 tp->last_ack_sent = tp->rcv_nxt; 739 m = NULL; 740 *ret_val = 0; 741 ctf_do_drop(m, NULL); 742 } 743 } 744 745 /* 746 * bbr_ts_check returns 1 for you should not proceed, the state 747 * machine should return. It places in ret_val what should 748 * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates 749 * that the TCB is unlocked and probably dropped. The 0 indicates the 750 * TCB is still valid and locked. 751 */ 752 int 753 ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 754 int32_t tlen, int32_t thflags, int32_t * ret_val) 755 { 756 757 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 758 /* 759 * Invalidate ts_recent. If this segment updates ts_recent, 760 * the age will be reset later and ts_recent will get a 761 * valid value. If it does not, setting ts_recent to zero 762 * will at least satisfy the requirement that zero be placed 763 * in the timestamp echo reply when ts_recent isn't valid. 764 * The age isn't reset until we get a valid ts_recent 765 * because we don't want out-of-order segments to be dropped 766 * when ts_recent is old. 767 */ 768 tp->ts_recent = 0; 769 } else { 770 TCPSTAT_INC(tcps_rcvduppack); 771 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 772 TCPSTAT_INC(tcps_pawsdrop); 773 *ret_val = 0; 774 if (tlen) { 775 ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); 776 } else { 777 ctf_do_drop(m, NULL); 778 } 779 return (1); 780 } 781 return (0); 782 } 783 784 void 785 ctf_calc_rwin(struct socket *so, struct tcpcb *tp) 786 { 787 int32_t win; 788 789 /* 790 * Calculate amount of space in receive window, and then do TCP 791 * input processing. Receive window is amount of space in rcv queue, 792 * but not less than advertised window. 793 */ 794 win = sbspace(&so->so_rcv); 795 if (win < 0) 796 win = 0; 797 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 798 } 799 800 void 801 ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, 802 int32_t rstreason, int32_t tlen) 803 { 804 805 if (tp->t_inpcb) { 806 tcp_set_inp_to_drop(tp->t_inpcb, ETIMEDOUT); 807 } 808 tcp_dropwithreset(m, th, tp, tlen, rstreason); 809 INP_WUNLOCK(tp->t_inpcb); 810 } 811 812 uint32_t 813 ctf_fixed_maxseg(struct tcpcb *tp) 814 { 815 int optlen; 816 817 if (tp->t_flags & TF_NOOPT) 818 return (tp->t_maxseg); 819 820 /* 821 * Here we have a simplified code from tcp_addoptions(), 822 * without a proper loop, and having most of paddings hardcoded. 823 * We only consider fixed options that we would send every 824 * time I.e. SACK is not considered. 825 * 826 */ 827 #define PAD(len) ((((len) / 4) + !!((len) % 4)) * 4) 828 if (TCPS_HAVEESTABLISHED(tp->t_state)) { 829 if (tp->t_flags & TF_RCVD_TSTMP) 830 optlen = TCPOLEN_TSTAMP_APPA; 831 else 832 optlen = 0; 833 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 834 if (tp->t_flags & TF_SIGNATURE) 835 optlen += PAD(TCPOLEN_SIGNATURE); 836 #endif 837 } else { 838 if (tp->t_flags & TF_REQ_TSTMP) 839 optlen = TCPOLEN_TSTAMP_APPA; 840 else 841 optlen = PAD(TCPOLEN_MAXSEG); 842 if (tp->t_flags & TF_REQ_SCALE) 843 optlen += PAD(TCPOLEN_WINDOW); 844 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 845 if (tp->t_flags & TF_SIGNATURE) 846 optlen += PAD(TCPOLEN_SIGNATURE); 847 #endif 848 if (tp->t_flags & TF_SACK_PERMIT) 849 optlen += PAD(TCPOLEN_SACK_PERMITTED); 850 } 851 #undef PAD 852 optlen = min(optlen, TCP_MAXOLEN); 853 return (tp->t_maxseg - optlen); 854 } 855 856 void 857 ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) 858 { 859 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 860 union tcp_log_stackspecific log; 861 struct timeval tv; 862 863 memset(&log, 0, sizeof(log)); 864 log.u_bbr.timeStamp = tcp_get_usecs(&tv); 865 log.u_bbr.flex8 = num_sack_blks; 866 if (num_sack_blks > 0) { 867 log.u_bbr.flex1 = sack_blocks[0].start; 868 log.u_bbr.flex2 = sack_blocks[0].end; 869 } 870 if (num_sack_blks > 1) { 871 log.u_bbr.flex3 = sack_blocks[1].start; 872 log.u_bbr.flex4 = sack_blocks[1].end; 873 } 874 if (num_sack_blks > 2) { 875 log.u_bbr.flex5 = sack_blocks[2].start; 876 log.u_bbr.flex6 = sack_blocks[2].end; 877 } 878 if (num_sack_blks > 3) { 879 log.u_bbr.applimited = sack_blocks[3].start; 880 log.u_bbr.pkts_out = sack_blocks[3].end; 881 } 882 TCP_LOG_EVENTP(tp, NULL, 883 &tp->t_inpcb->inp_socket->so_rcv, 884 &tp->t_inpcb->inp_socket->so_snd, 885 TCP_SACK_FILTER_RES, 0, 886 0, &log, false, &tv); 887 } 888 } 889 890 uint32_t 891 ctf_decay_count(uint32_t count, uint32_t decay) 892 { 893 /* 894 * Given a count, decay it by a set percentage. The 895 * percentage is in thousands i.e. 100% = 1000, 896 * 19.3% = 193. 897 */ 898 uint64_t perc_count, decay_per; 899 uint32_t decayed_count; 900 if (decay > 1000) { 901 /* We don't raise it */ 902 return (count); 903 } 904 perc_count = count; 905 decay_per = decay; 906 perc_count *= decay_per; 907 perc_count /= 1000; 908 /* 909 * So now perc_count holds the 910 * count decay value. 911 */ 912 decayed_count = count - (uint32_t)perc_count; 913 return(decayed_count); 914 } 915