/*- * Copyright (c) 2016-2020 Netflix, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * */ /* * Author: Randall Stewart * This work is based on the ACM Queue paper * BBR - Congestion Based Congestion Control * and also numerous discussions with Neal, Yuchung and Van. */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include "opt_inet6.h" #include "opt_ipsec.h" #include "opt_ratelimit.h" #include "opt_kern_tls.h" #include #include #include #include #ifdef TCP_HHOOK #include #endif #include #include #include #include #include #include #ifdef KERN_TLS #include #endif #include #include #include #ifdef NETFLIX_STATS #include /* Must come after qmath.h and tree.h */ #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define TCPSTATES /* for logging */ #include #include #include #include #include /* required for icmp_var.h */ #include /* for ICMP_BANDLIM */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef TCP_OFFLOAD #include #endif #ifdef INET6 #include #endif #include #include #include #include #if defined(IPSEC) || defined(IPSEC_SUPPORT) #include #include #endif /* IPSEC */ #include #include #include #ifdef MAC #include #endif #include "rack_bbr_common.h" /* * Common TCP Functions - These are shared by borth * rack and BBR. */ #ifdef KERN_TLS uint32_t ctf_get_opt_tls_size(struct socket *so, uint32_t rwnd) { struct ktls_session *tls; uint32_t len; again: tls = so->so_snd.sb_tls_info; len = tls->params.max_frame_len; /* max tls payload */ len += tls->params.tls_hlen; /* tls header len */ len += tls->params.tls_tlen; /* tls trailer len */ if ((len * 4) > rwnd) { /* * Stroke this will suck counter and what * else should we do Drew? From the * TCP perspective I am not sure * what should be done... */ if (tls->params.max_frame_len > 4096) { tls->params.max_frame_len -= 4096; if (tls->params.max_frame_len < 4096) tls->params.max_frame_len = 4096; goto again; } } return (len); } #endif static int ctf_get_enet_type(struct ifnet *ifp, struct mbuf *m) { struct ether_header *eh; #ifdef INET6 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ #endif #ifdef INET struct ip *ip = NULL; /* Keep compiler happy. */ #endif #if defined(INET) || defined(INET6) struct tcphdr *th; int32_t tlen; uint16_t drop_hdrlen; #endif uint16_t etype; #ifdef INET uint8_t iptos; #endif /* Is it the easy way? */ if (m->m_flags & M_LRO_EHDRSTRP) return (m->m_pkthdr.lro_etype); /* * Ok this is the old style call, the ethernet header is here. * This also means no checksum or BPF were done. This * can happen if the race to setup the inp fails and * LRO sees no INP at packet input, but by the time * we queue the packets an INP gets there. Its rare * but it can occur so we will handle it. Note that * this means duplicated work but with the rarity of it * its not worth worrying about. */ /* Let the BPF see the packet */ if (bpf_peers_present(ifp->if_bpf)) ETHER_BPF_MTAP(ifp, m); /* Now the csum */ eh = mtod(m, struct ether_header *); etype = ntohs(eh->ether_type); m_adj(m, sizeof(*eh)); switch (etype) { #ifdef INET6 case ETHERTYPE_IPV6: { if (m->m_len < (sizeof(*ip6) + sizeof(*th))) { m = m_pullup(m, sizeof(*ip6) + sizeof(*th)); if (m == NULL) { KMOD_TCPSTAT_INC(tcps_rcvshort); return (-1); } } ip6 = (struct ip6_hdr *)(eh + 1); th = (struct tcphdr *)(ip6 + 1); drop_hdrlen = sizeof(*ip6); tlen = ntohs(ip6->ip6_plen); if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) th->th_sum = m->m_pkthdr.csum_data; else th->th_sum = in6_cksum_pseudo(ip6, tlen, IPPROTO_TCP, m->m_pkthdr.csum_data); th->th_sum ^= 0xffff; } else th->th_sum = in6_cksum(m, IPPROTO_TCP, drop_hdrlen, tlen); if (th->th_sum) { KMOD_TCPSTAT_INC(tcps_rcvbadsum); m_freem(m); return (-1); } return (etype); } #endif #ifdef INET case ETHERTYPE_IP: { if (m->m_len < sizeof (struct tcpiphdr)) { m = m_pullup(m, sizeof (struct tcpiphdr)); if (m == NULL) { KMOD_TCPSTAT_INC(tcps_rcvshort); return (-1); } } ip = (struct ip *)(eh + 1); th = (struct tcphdr *)(ip + 1); drop_hdrlen = sizeof(*ip); iptos = ip->ip_tos; tlen = ntohs(ip->ip_len) - sizeof(struct ip); if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) th->th_sum = m->m_pkthdr.csum_data; else th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, htonl(m->m_pkthdr.csum_data + tlen + IPPROTO_TCP)); th->th_sum ^= 0xffff; } else { int len; struct ipovly *ipov = (struct ipovly *)ip; /* * Checksum extended TCP header and data. */ len = drop_hdrlen + tlen; bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); ipov->ih_len = htons(tlen); th->th_sum = in_cksum(m, len); /* Reset length for SDT probes. */ ip->ip_len = htons(len); /* Reset TOS bits */ ip->ip_tos = iptos; /* Re-initialization for later version check */ ip->ip_v = IPVERSION; ip->ip_hl = sizeof(*ip) >> 2; } if (th->th_sum) { KMOD_TCPSTAT_INC(tcps_rcvbadsum); m_freem(m); return (-1); } break; } #endif }; return (etype); } /* * The function ctf_process_inbound_raw() is used by * transport developers to do the steps needed to * support MBUF Queuing i.e. the flags in * inp->inp_flags2: * * - INP_SUPPORTS_MBUFQ * - INP_MBUF_QUEUE_READY * - INP_DONT_SACK_QUEUE * - INP_MBUF_ACKCMP * * These flags help control how LRO will deliver * packets to the transport. You first set in inp_flags2 * the INP_SUPPORTS_MBUFQ to tell the LRO code that you * will gladly take a queue of packets instead of a compressed * single packet. You also set in your t_fb pointer the * tfb_do_queued_segments to point to ctf_process_inbound_raw. * * This then gets you lists of inbound ACK's/Data instead * of a condensed compressed ACK/DATA packet. Why would you * want that? This will get you access to all the arrival * times of at least LRO and possibly at the Hardware (if * the interface card supports that) of the actual ACK/DATA. * In some transport designs this is important since knowing * the actual time we got the packet is useful information. * * A new special type of mbuf may also be supported by the transport * if it has set the INP_MBUF_ACKCMP flag. If its set, LRO will * possibly create a M_ACKCMP type mbuf. This is a mbuf with * an array of "acks". One thing also to note is that when this * occurs a subsequent LRO may find at the back of the untouched * mbuf queue chain a M_ACKCMP and append on to it. This means * that until the transport pulls in the mbuf chain queued * for it more ack's may get on the mbufs that were already * delivered. There currently is a limit of 6 acks condensed * into 1 mbuf which means often when this is occuring, we * don't get that effect but it does happen. * * Now there are some interesting Caveats that the transport * designer needs to take into account when using this feature. * * 1) It is used with HPTS and pacing, when the pacing timer * for output calls it will first call the input. * 2) When you set INP_MBUF_QUEUE_READY this tells LRO * queue normal packets, I am busy pacing out data and * will process the queued packets before my tfb_tcp_output * call from pacing. If a non-normal packet arrives, (e.g. sack) * you will be awoken immediately. * 3) Finally you can add the INP_DONT_SACK_QUEUE to not even * be awoken if a SACK has arrived. You would do this when * you were not only running a pacing for output timer * but a Rack timer as well i.e. you know you are in recovery * and are in the process (via the timers) of dealing with * the loss. * * Now a critical thing you must be aware of here is that the * use of the flags has a far greater scope then just your * typical LRO. Why? Well thats because in the normal compressed * LRO case at the end of a driver interupt all packets are going * to get presented to the transport no matter if there is one * or 100. With the MBUF_QUEUE model, this is not true. You will * only be awoken to process the queue of packets when: * a) The flags discussed above allow it. * * b) You exceed a ack or data limit (by default the * ack limit is infinity (64k acks) and the data * limit is 64k of new TCP data) * * c) The push bit has been set by the peer */ int ctf_process_inbound_raw(struct tcpcb *tp, struct socket *so, struct mbuf *m, int has_pkt) { /* * We are passed a raw change of mbuf packets * that arrived in LRO. They are linked via * the m_nextpkt link in the pkt-headers. * * We process each one by: * a) saving off the next * b) stripping off the ether-header * c) formulating the arguments for * the tfb_tcp_hpts_do_segment * d) calling each mbuf to tfb_tcp_hpts_do_segment * after adjusting the time to match the arrival time. * Note that the LRO code assures no IP options are present. * * The symantics for calling tfb_tcp_hpts_do_segment are the * following: * 1) It returns 0 if all went well and you (the caller) need * to release the lock. * 2) If nxt_pkt is set, then the function will surpress calls * to tcp_output() since you are promising to call again * with another packet. * 3) If it returns 1, then you must free all the packets being * shipped in, the tcb has been destroyed (or about to be destroyed). */ struct mbuf *m_save; struct tcphdr *th; #ifdef INET6 struct ip6_hdr *ip6 = NULL; /* Keep compiler happy. */ #endif #ifdef INET struct ip *ip = NULL; /* Keep compiler happy. */ #endif struct ifnet *ifp; struct timeval tv; struct inpcb *inp __diagused; int32_t retval, nxt_pkt, tlen, off; int etype = 0; uint16_t drop_hdrlen; uint8_t iptos, no_vn=0; inp = tptoinpcb(tp); INP_WLOCK_ASSERT(inp); NET_EPOCH_ASSERT(); if (m) ifp = m_rcvif(m); else ifp = NULL; if (ifp == NULL) { /* * We probably should not work around * but kassert, since lro alwasy sets rcvif. */ no_vn = 1; goto skip_vnet; } CURVNET_SET(ifp->if_vnet); skip_vnet: tcp_get_usecs(&tv); while (m) { m_save = m->m_nextpkt; m->m_nextpkt = NULL; if ((m->m_flags & M_ACKCMP) == 0) { /* Now lets get the ether header */ etype = ctf_get_enet_type(ifp, m); if (etype == -1) { /* Skip this packet it was freed by checksum */ goto skipped_pkt; } KASSERT(((etype == ETHERTYPE_IPV6) || (etype == ETHERTYPE_IP)), ("tp:%p m:%p etype:0x%x -- not IP or IPv6", tp, m, etype)); /* Trim off the ethernet header */ switch (etype) { #ifdef INET6 case ETHERTYPE_IPV6: ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(ip6 + 1); tlen = ntohs(ip6->ip6_plen); drop_hdrlen = sizeof(*ip6); iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; break; #endif #ifdef INET case ETHERTYPE_IP: ip = mtod(m, struct ip *); th = (struct tcphdr *)(ip + 1); drop_hdrlen = sizeof(*ip); iptos = ip->ip_tos; tlen = ntohs(ip->ip_len) - sizeof(struct ip); break; #endif } /* end switch */ /* * Convert TCP protocol specific fields to host format. */ tcp_fields_to_host(th); off = th->th_off << 2; if (off < sizeof (struct tcphdr) || off > tlen) { printf("off:%d < hdrlen:%zu || > tlen:%u -- dump\n", off, sizeof(struct tcphdr), tlen); KMOD_TCPSTAT_INC(tcps_rcvbadoff); m_freem(m); goto skipped_pkt; } tlen -= off; drop_hdrlen += off; /* * Now lets setup the timeval to be when we should * have been called (if we can). */ m->m_pkthdr.lro_nsegs = 1; /* Now what about next packet? */ } else { /* * This mbuf is an array of acks that have * been compressed. We assert the inp has * the flag set to enable this! */ KASSERT((inp->inp_flags2 & INP_MBUF_ACKCMP), ("tp:%p inp:%p no INP_MBUF_ACKCMP flags?", tp, inp)); tlen = 0; drop_hdrlen = 0; th = NULL; iptos = 0; } tcp_get_usecs(&tv); if (m_save || has_pkt) nxt_pkt = 1; else nxt_pkt = 0; if ((m->m_flags & M_ACKCMP) == 0) KMOD_TCPSTAT_INC(tcps_rcvtotal); else KMOD_TCPSTAT_ADD(tcps_rcvtotal, (m->m_len / sizeof(struct tcp_ackent))); retval = (*tp->t_fb->tfb_do_segment_nounlock)(m, th, so, tp, drop_hdrlen, tlen, iptos, nxt_pkt, &tv); if (retval) { /* We lost the lock and tcb probably */ m = m_save; while(m) { m_save = m->m_nextpkt; m->m_nextpkt = NULL; m_freem(m); m = m_save; } if (no_vn == 0) { CURVNET_RESTORE(); } INP_UNLOCK_ASSERT(inp); return(retval); } skipped_pkt: m = m_save; } if (no_vn == 0) { CURVNET_RESTORE(); } return(retval); } int ctf_do_queued_segments(struct socket *so, struct tcpcb *tp, int have_pkt) { struct mbuf *m; /* First lets see if we have old packets */ if (tp->t_in_pkt) { m = tp->t_in_pkt; tp->t_in_pkt = NULL; tp->t_tail_pkt = NULL; if (ctf_process_inbound_raw(tp, so, m, have_pkt)) { /* We lost the tcpcb (maybe a RST came in)? */ return(1); } } return (0); } uint32_t ctf_outstanding(struct tcpcb *tp) { uint32_t bytes_out; bytes_out = tp->snd_max - tp->snd_una; if (tp->t_state < TCPS_ESTABLISHED) bytes_out++; if (tp->t_flags & TF_SENTFIN) bytes_out++; return (bytes_out); } uint32_t ctf_flight_size(struct tcpcb *tp, uint32_t rc_sacked) { if (rc_sacked <= ctf_outstanding(tp)) return(ctf_outstanding(tp) - rc_sacked); else { return (0); } } void ctf_do_dropwithreset(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t rstreason, int32_t tlen) { if (tp != NULL) { tcp_dropwithreset(m, th, tp, tlen, rstreason); INP_WUNLOCK(tptoinpcb(tp)); } else tcp_dropwithreset(m, th, NULL, tlen, rstreason); } void ctf_ack_war_checks(struct tcpcb *tp, uint32_t *ts, uint32_t *cnt) { if ((ts != NULL) && (cnt != NULL) && (tcp_ack_war_time_window > 0) && (tcp_ack_war_cnt > 0)) { /* We are possibly doing ack war prevention */ uint32_t cts; /* * We use a msec tick here which gives us * roughly 49 days. We don't need the * precision of a microsecond timestamp which * would only give us hours. */ cts = tcp_ts_getticks(); if (TSTMP_LT((*ts), cts)) { /* Timestamp is in the past */ *cnt = 0; *ts = (cts + tcp_ack_war_time_window); } if (*cnt < tcp_ack_war_cnt) { *cnt = (*cnt + 1); tp->t_flags |= TF_ACKNOW; } else tp->t_flags &= ~TF_ACKNOW; } else tp->t_flags |= TF_ACKNOW; } /* * ctf_drop_checks returns 1 for you should not proceed. It places * in ret_val what should be returned 1/0 by the caller. The 1 indicates * that the TCB is unlocked and probably dropped. The 0 indicates the * TCB is still valid and locked. */ int _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, uint32_t *ts, uint32_t *cnt) { int32_t todrop; int32_t thflags; int32_t tlen; thflags = *thf; tlen = *tlenp; todrop = tp->rcv_nxt - th->th_seq; if (todrop > 0) { if (thflags & TH_SYN) { thflags &= ~TH_SYN; th->th_seq++; if (th->th_urp > 1) th->th_urp--; else thflags &= ~TH_URG; todrop--; } /* * Following if statement from Stevens, vol. 2, p. 960. */ if (todrop > tlen || (todrop == tlen && (thflags & TH_FIN) == 0)) { /* * Any valid FIN must be to the left of the window. * At this point the FIN must be a duplicate or out * of sequence; drop it. */ thflags &= ~TH_FIN; /* * Send an ACK to resynchronize and drop any data. * But keep on processing for RST or ACK. */ ctf_ack_war_checks(tp, ts, cnt); todrop = tlen; KMOD_TCPSTAT_INC(tcps_rcvduppack); KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, todrop); } else { KMOD_TCPSTAT_INC(tcps_rcvpartduppack); KMOD_TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); } /* * DSACK - add SACK block for dropped range */ if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { /* * ACK now, as the next in-sequence segment * will clear the DSACK block again */ ctf_ack_war_checks(tp, ts, cnt); if (tp->t_flags & TF_ACKNOW) tcp_update_sack_list(tp, th->th_seq, th->th_seq + todrop); } *drop_hdrlen += todrop; /* drop from the top afterwards */ th->th_seq += todrop; tlen -= todrop; if (th->th_urp > todrop) th->th_urp -= todrop; else { thflags &= ~TH_URG; th->th_urp = 0; } } /* * If segment ends after window, drop trailing data (and PUSH and * FIN); if nothing left, just ACK. */ todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); if (todrop > 0) { KMOD_TCPSTAT_INC(tcps_rcvpackafterwin); if (todrop >= tlen) { KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); /* * If window is closed can only take segments at * window edge, and have to drop data and PUSH from * incoming segments. Continue processing, but * remember to ack. Otherwise, drop segment and * ack. */ if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { ctf_ack_war_checks(tp, ts, cnt); KMOD_TCPSTAT_INC(tcps_rcvwinprobe); } else { __ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val, ts, cnt); return (1); } } else KMOD_TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); m_adj(m, -todrop); tlen -= todrop; thflags &= ~(TH_PUSH | TH_FIN); } *thf = thflags; *tlenp = tlen; return (0); } /* * The value in ret_val informs the caller * if we dropped the tcb (and lock) or not. * 1 = we dropped it, 0 = the TCB is still locked * and valid. */ void __ctf_do_dropafterack(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t thflags, int32_t tlen, int32_t *ret_val, uint32_t *ts, uint32_t *cnt) { /* * Generate an ACK dropping incoming segment if it occupies sequence * space, where the ACK reflects our state. * * We can now skip the test for the RST flag since all paths to this * code happen after packets containing RST have been dropped. * * In the SYN-RECEIVED state, don't send an ACK unless the segment * we received passes the SYN-RECEIVED ACK test. If it fails send a * RST. This breaks the loop in the "LAND" DoS attack, and also * prevents an ACK storm between two listening ports that have been * sent forged SYN segments, each with the source address of the * other. */ if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && (SEQ_GT(tp->snd_una, th->th_ack) || SEQ_GT(th->th_ack, tp->snd_max))) { *ret_val = 1; ctf_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen); return; } else *ret_val = 0; ctf_ack_war_checks(tp, ts, cnt); if (m) m_freem(m); } void ctf_do_drop(struct mbuf *m, struct tcpcb *tp) { /* * Drop space held by incoming segment and return. */ if (tp != NULL) INP_WUNLOCK(tptoinpcb(tp)); if (m) m_freem(m); } int __ctf_process_rst(struct mbuf *m, struct tcphdr *th, struct socket *so, struct tcpcb *tp, uint32_t *ts, uint32_t *cnt) { /* * RFC5961 Section 3.2 * * - RST drops connection only if SEG.SEQ == RCV.NXT. - If RST is in * window, we send challenge ACK. * * Note: to take into account delayed ACKs, we should test against * last_ack_sent instead of rcv_nxt. Note 2: we handle special case * of closed window, not covered by the RFC. */ int dropped = 0; if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { KASSERT(tp->t_state != TCPS_SYN_SENT, ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", __func__, th, tp)); if (V_tcp_insecure_rst || (tp->last_ack_sent == th->th_seq) || (tp->rcv_nxt == th->th_seq)) { KMOD_TCPSTAT_INC(tcps_drops); /* Drop the connection. */ switch (tp->t_state) { case TCPS_SYN_RECEIVED: so->so_error = ECONNREFUSED; goto close; case TCPS_ESTABLISHED: case TCPS_FIN_WAIT_1: case TCPS_FIN_WAIT_2: case TCPS_CLOSE_WAIT: case TCPS_CLOSING: case TCPS_LAST_ACK: so->so_error = ECONNRESET; close: tcp_state_change(tp, TCPS_CLOSED); /* FALLTHROUGH */ default: tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); tp = tcp_close(tp); } dropped = 1; ctf_do_drop(m, tp); } else { int send_challenge; KMOD_TCPSTAT_INC(tcps_badrst); if ((ts != NULL) && (cnt != NULL) && (tcp_ack_war_time_window > 0) && (tcp_ack_war_cnt > 0)) { /* We are possibly preventing an ack-rst war prevention */ uint32_t cts; /* * We use a msec tick here which gives us * roughly 49 days. We don't need the * precision of a microsecond timestamp which * would only give us hours. */ cts = tcp_ts_getticks(); if (TSTMP_LT((*ts), cts)) { /* Timestamp is in the past */ *cnt = 0; *ts = (cts + tcp_ack_war_time_window); } if (*cnt < tcp_ack_war_cnt) { *cnt = (*cnt + 1); send_challenge = 1; } else send_challenge = 0; } else send_challenge = 1; if (send_challenge) { /* Send challenge ACK. */ tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, tp->snd_nxt, TH_ACK); tp->last_ack_sent = tp->rcv_nxt; } } } else { m_freem(m); } return (dropped); } /* * The value in ret_val informs the caller * if we dropped the tcb (and lock) or not. * 1 = we dropped it, 0 = the TCB is still locked * and valid. */ void ctf_challenge_ack(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, uint8_t iptos, int32_t * ret_val) { NET_EPOCH_ASSERT(); KMOD_TCPSTAT_INC(tcps_badsyn); if (V_tcp_insecure_syn && SEQ_GEQ(th->th_seq, tp->last_ack_sent) && SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { tp = tcp_drop(tp, ECONNRESET); *ret_val = 1; ctf_do_drop(m, tp); } else { tcp_ecn_input_syn_sent(tp, tcp_get_flags(th), iptos); /* Send challenge ACK. */ tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, tp->snd_nxt, TH_ACK); tp->last_ack_sent = tp->rcv_nxt; m = NULL; *ret_val = 0; ctf_do_drop(m, NULL); } } /* * ctf_ts_check returns 1 for you should not proceed, the state * machine should return. It places in ret_val what should * be returned 1/0 by the caller (hpts_do_segment). The 1 indicates * that the TCB is unlocked and probably dropped. The 0 indicates the * TCB is still valid and locked. */ int ctf_ts_check(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int32_t tlen, int32_t thflags, int32_t * ret_val) { if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { /* * Invalidate ts_recent. If this segment updates ts_recent, * the age will be reset later and ts_recent will get a * valid value. If it does not, setting ts_recent to zero * will at least satisfy the requirement that zero be placed * in the timestamp echo reply when ts_recent isn't valid. * The age isn't reset until we get a valid ts_recent * because we don't want out-of-order segments to be dropped * when ts_recent is old. */ tp->ts_recent = 0; } else { KMOD_TCPSTAT_INC(tcps_rcvduppack); KMOD_TCPSTAT_ADD(tcps_rcvdupbyte, tlen); KMOD_TCPSTAT_INC(tcps_pawsdrop); *ret_val = 0; if (tlen) { ctf_do_dropafterack(m, tp, th, thflags, tlen, ret_val); } else { ctf_do_drop(m, NULL); } return (1); } return (0); } int ctf_ts_check_ac(struct tcpcb *tp, int32_t thflags) { if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { /* * Invalidate ts_recent. If this segment updates ts_recent, * the age will be reset later and ts_recent will get a * valid value. If it does not, setting ts_recent to zero * will at least satisfy the requirement that zero be placed * in the timestamp echo reply when ts_recent isn't valid. * The age isn't reset until we get a valid ts_recent * because we don't want out-of-order segments to be dropped * when ts_recent is old. */ tp->ts_recent = 0; } else { KMOD_TCPSTAT_INC(tcps_rcvduppack); KMOD_TCPSTAT_INC(tcps_pawsdrop); return (1); } return (0); } void ctf_calc_rwin(struct socket *so, struct tcpcb *tp) { int32_t win; /* * Calculate amount of space in receive window, and then do TCP * input processing. Receive window is amount of space in rcv queue, * but not less than advertised window. */ win = sbspace(&so->so_rcv); if (win < 0) win = 0; tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); } void ctf_do_dropwithreset_conn(struct mbuf *m, struct tcpcb *tp, struct tcphdr *th, int32_t rstreason, int32_t tlen) { tcp_dropwithreset(m, th, tp, tlen, rstreason); tp = tcp_drop(tp, ETIMEDOUT); if (tp) INP_WUNLOCK(tptoinpcb(tp)); } uint32_t ctf_fixed_maxseg(struct tcpcb *tp) { return (tcp_fixed_maxseg(tp)); } void ctf_log_sack_filter(struct tcpcb *tp, int num_sack_blks, struct sackblk *sack_blocks) { if (tp->t_logstate != TCP_LOG_STATE_OFF) { union tcp_log_stackspecific log; struct timeval tv; memset(&log, 0, sizeof(log)); log.u_bbr.timeStamp = tcp_get_usecs(&tv); log.u_bbr.flex8 = num_sack_blks; if (num_sack_blks > 0) { log.u_bbr.flex1 = sack_blocks[0].start; log.u_bbr.flex2 = sack_blocks[0].end; } if (num_sack_blks > 1) { log.u_bbr.flex3 = sack_blocks[1].start; log.u_bbr.flex4 = sack_blocks[1].end; } if (num_sack_blks > 2) { log.u_bbr.flex5 = sack_blocks[2].start; log.u_bbr.flex6 = sack_blocks[2].end; } if (num_sack_blks > 3) { log.u_bbr.applimited = sack_blocks[3].start; log.u_bbr.pkts_out = sack_blocks[3].end; } TCP_LOG_EVENTP(tp, NULL, &tptosocket(tp)->so_rcv, &tptosocket(tp)->so_snd, TCP_SACK_FILTER_RES, 0, 0, &log, false, &tv); } } uint32_t ctf_decay_count(uint32_t count, uint32_t decay) { /* * Given a count, decay it by a set percentage. The * percentage is in thousands i.e. 100% = 1000, * 19.3% = 193. */ uint64_t perc_count, decay_per; uint32_t decayed_count; if (decay > 1000) { /* We don't raise it */ return (count); } perc_count = count; decay_per = decay; perc_count *= decay_per; perc_count /= 1000; /* * So now perc_count holds the * count decay value. */ decayed_count = count - (uint32_t)perc_count; return(decayed_count); } int32_t ctf_progress_timeout_check(struct tcpcb *tp, bool log) { if (tp->t_maxunacktime && tp->t_acktime && TSTMP_GT(ticks, tp->t_acktime)) { if ((ticks - tp->t_acktime) >= tp->t_maxunacktime) { /* * There is an assumption that the caller * will drop the connection so we will * increment the counters here. */ if (log) tcp_log_end_status(tp, TCP_EI_STATUS_PROGRESS); #ifdef NETFLIX_STATS KMOD_TCPSTAT_INC(tcps_progdrops); #endif return (1); } } return (0); }