sys/netinet/tcp_stacks/rack_bbr_common.c

   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 }