/* $OpenBSD: tcp_subr.c,v 1.158 2017/01/10 09:01:18 mpi Exp $ */ /* $NetBSD: tcp_subr.c,v 1.22 1996/02/13 23:44:00 christos Exp $ */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993 * The Regents of the University of California. All rights reserved. * * 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. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * 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. * * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 * * NRL grants permission for redistribution and use in source and binary * forms, with or without modification, of the software and documentation * created at NRL 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgements: * This product includes software developed by the University of * California, Berkeley and its contributors. * This product includes software developed at the Information * Technology Division, US Naval Research Laboratory. * 4. Neither the name of the NRL nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL 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 NRL 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. * * The views and conclusions contained in the software and documentation * are those of the authors and should not be interpreted as representing * official policies, either expressed or implied, of the US Naval * Research Laboratory (NRL). */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #endif /* INET6 */ #include #include /* patchable/settable parameters for tcp */ int tcp_mssdflt = TCP_MSS; int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; /* values controllable via sysctl */ int tcp_do_rfc1323 = 1; #ifdef TCP_SACK int tcp_do_sack = 1; /* RFC 2018 selective ACKs */ #endif int tcp_ack_on_push = 0; /* set to enable immediate ACK-on-PUSH */ #ifdef TCP_ECN int tcp_do_ecn = 0; /* RFC3168 ECN enabled/disabled? */ #endif int tcp_do_rfc3390 = 2; /* Increase TCP's Initial Window to 10*mss */ u_int32_t tcp_now = 1; #ifndef TCB_INITIAL_HASH_SIZE #define TCB_INITIAL_HASH_SIZE 128 #endif int tcp_reass_limit = NMBCLUSTERS / 8; /* hardlimit for tcpqe_pool */ #ifdef TCP_SACK int tcp_sackhole_limit = 32*1024; /* hardlimit for sackhl_pool */ #endif struct pool tcpcb_pool; struct pool tcpqe_pool; #ifdef TCP_SACK struct pool sackhl_pool; #endif struct tcpstat tcpstat; /* tcp statistics */ tcp_seq tcp_iss; /* * Tcp initialization */ void tcp_init(void) { tcp_iss = 1; /* wrong */ pool_init(&tcpcb_pool, sizeof(struct tcpcb), 0, IPL_SOFTNET, 0, "tcpcb", NULL); pool_init(&tcpqe_pool, sizeof(struct tcpqent), 0, IPL_SOFTNET, 0, "tcpqe", NULL); pool_sethardlimit(&tcpqe_pool, tcp_reass_limit, NULL, 0); #ifdef TCP_SACK pool_init(&sackhl_pool, sizeof(struct sackhole), 0, IPL_SOFTNET, 0, "sackhl", NULL); pool_sethardlimit(&sackhl_pool, tcp_sackhole_limit, NULL, 0); #endif /* TCP_SACK */ in_pcbinit(&tcbtable, TCB_INITIAL_HASH_SIZE); #ifdef INET6 /* * Since sizeof(struct ip6_hdr) > sizeof(struct ip), we * do max length checks/computations only on the former. */ if (max_protohdr < (sizeof(struct ip6_hdr) + sizeof(struct tcphdr))) max_protohdr = (sizeof(struct ip6_hdr) + sizeof(struct tcphdr)); if ((max_linkhdr + sizeof(struct ip6_hdr) + sizeof(struct tcphdr)) > MHLEN) panic("tcp_init"); icmp6_mtudisc_callback_register(tcp6_mtudisc_callback); #endif /* INET6 */ /* Initialize the compressed state engine. */ syn_cache_init(); /* Initialize timer state. */ tcp_timer_init(); } /* * Create template to be used to send tcp packets on a connection. * Call after host entry created, allocates an mbuf and fills * in a skeletal tcp/ip header, minimizing the amount of work * necessary when the connection is used. * * To support IPv6 in addition to IPv4 and considering that the sizes of * the IPv4 and IPv6 headers are not the same, we now use a separate pointer * for the TCP header. Also, we made the former tcpiphdr header pointer * into just an IP overlay pointer, with casting as appropriate for v6. rja */ struct mbuf * tcp_template(struct tcpcb *tp) { struct inpcb *inp = tp->t_inpcb; struct mbuf *m; struct tcphdr *th; if ((m = tp->t_template) == 0) { m = m_get(M_DONTWAIT, MT_HEADER); if (m == NULL) return (0); switch (tp->pf) { case 0: /*default to PF_INET*/ case AF_INET: m->m_len = sizeof(struct ip); break; #ifdef INET6 case AF_INET6: m->m_len = sizeof(struct ip6_hdr); break; #endif /* INET6 */ } m->m_len += sizeof (struct tcphdr); /* * The link header, network header, TCP header, and TCP options * all must fit in this mbuf. For now, assume the worst case of * TCP options size. Eventually, compute this from tp flags. */ if (m->m_len + MAX_TCPOPTLEN + max_linkhdr >= MHLEN) { MCLGET(m, M_DONTWAIT); if ((m->m_flags & M_EXT) == 0) { m_free(m); return (0); } } } switch(tp->pf) { case AF_INET: { struct ipovly *ipovly; ipovly = mtod(m, struct ipovly *); bzero(ipovly->ih_x1, sizeof ipovly->ih_x1); ipovly->ih_pr = IPPROTO_TCP; ipovly->ih_len = htons(sizeof (struct tcphdr)); ipovly->ih_src = inp->inp_laddr; ipovly->ih_dst = inp->inp_faddr; th = (struct tcphdr *)(mtod(m, caddr_t) + sizeof(struct ip)); } break; #ifdef INET6 case AF_INET6: { struct ip6_hdr *ip6; ip6 = mtod(m, struct ip6_hdr *); ip6->ip6_src = inp->inp_laddr6; ip6->ip6_dst = inp->inp_faddr6; ip6->ip6_flow = htonl(0x60000000) | (inp->inp_flowinfo & IPV6_FLOWLABEL_MASK); ip6->ip6_nxt = IPPROTO_TCP; ip6->ip6_plen = htons(sizeof(struct tcphdr)); /*XXX*/ ip6->ip6_hlim = in6_selecthlim(inp); /*XXX*/ th = (struct tcphdr *)(mtod(m, caddr_t) + sizeof(struct ip6_hdr)); } break; #endif /* INET6 */ } th->th_sport = inp->inp_lport; th->th_dport = inp->inp_fport; th->th_seq = 0; th->th_ack = 0; th->th_x2 = 0; th->th_off = 5; th->th_flags = 0; th->th_win = 0; th->th_urp = 0; th->th_sum = 0; return (m); } /* * Send a single message to the TCP at address specified by * the given TCP/IP header. If m == 0, then we make a copy * of the tcpiphdr at ti and send directly to the addressed host. * This is used to force keep alive messages out using the TCP * template for a connection tp->t_template. If flags are given * then we send a message back to the TCP which originated the * segment ti, and discard the mbuf containing it and any other * attached mbufs. * * In any case the ack and sequence number of the transmitted * segment are as specified by the parameters. */ void tcp_respond(struct tcpcb *tp, caddr_t template, struct tcphdr *th0, tcp_seq ack, tcp_seq seq, int flags, u_int rtableid) { int tlen; int win = 0; struct mbuf *m = NULL; struct tcphdr *th; struct ip *ip; #ifdef INET6 struct ip6_hdr *ip6; #endif int af; /* af on wire */ if (tp) { win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); /* * If this is called with an unconnected * socket/tp/pcb (tp->pf is 0), we lose. */ af = tp->pf; } else af = (((struct ip *)template)->ip_v == 6) ? AF_INET6 : AF_INET; m = m_gethdr(M_DONTWAIT, MT_HEADER); if (m == NULL) return; m->m_data += max_linkhdr; tlen = 0; #define xchg(a,b,type) do { type t; t=a; a=b; b=t; } while (0) switch (af) { #ifdef INET6 case AF_INET6: ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(ip6 + 1); tlen = sizeof(*ip6) + sizeof(*th); if (th0) { bcopy(template, ip6, sizeof(*ip6)); bcopy(th0, th, sizeof(*th)); xchg(ip6->ip6_dst, ip6->ip6_src, struct in6_addr); } else { bcopy(template, ip6, tlen); } break; #endif /* INET6 */ case AF_INET: ip = mtod(m, struct ip *); th = (struct tcphdr *)(ip + 1); tlen = sizeof(*ip) + sizeof(*th); if (th0) { bcopy(template, ip, sizeof(*ip)); bcopy(th0, th, sizeof(*th)); xchg(ip->ip_dst.s_addr, ip->ip_src.s_addr, u_int32_t); } else { bcopy(template, ip, tlen); } break; } if (th0) xchg(th->th_dport, th->th_sport, u_int16_t); else flags = TH_ACK; #undef xchg th->th_seq = htonl(seq); th->th_ack = htonl(ack); th->th_x2 = 0; th->th_off = sizeof (struct tcphdr) >> 2; th->th_flags = flags; if (tp) win >>= tp->rcv_scale; if (win > TCP_MAXWIN) win = TCP_MAXWIN; th->th_win = htons((u_int16_t)win); th->th_urp = 0; if (tp && (tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && (flags & TH_RST) == 0 && (tp->t_flags & TF_RCVD_TSTMP)) { u_int32_t *lp = (u_int32_t *)(th + 1); /* Form timestamp option as shown in appendix A of RFC 1323. */ *lp++ = htonl(TCPOPT_TSTAMP_HDR); *lp++ = htonl(tcp_now + tp->ts_modulate); *lp = htonl(tp->ts_recent); tlen += TCPOLEN_TSTAMP_APPA; th->th_off = (sizeof(struct tcphdr) + TCPOLEN_TSTAMP_APPA) >> 2; } m->m_len = tlen; m->m_pkthdr.len = tlen; m->m_pkthdr.ph_ifidx = 0; m->m_pkthdr.csum_flags |= M_TCP_CSUM_OUT; /* force routing table */ if (tp) m->m_pkthdr.ph_rtableid = tp->t_inpcb->inp_rtableid; else m->m_pkthdr.ph_rtableid = rtableid; switch (af) { #ifdef INET6 case AF_INET6: ip6->ip6_flow = htonl(0x60000000); ip6->ip6_nxt = IPPROTO_TCP; ip6->ip6_hlim = in6_selecthlim(tp ? tp->t_inpcb : NULL); /*XXX*/ ip6->ip6_plen = tlen - sizeof(struct ip6_hdr); ip6->ip6_plen = htons(ip6->ip6_plen); ip6_output(m, tp ? tp->t_inpcb->inp_outputopts6 : NULL, tp ? &tp->t_inpcb->inp_route6 : NULL, 0, NULL, tp ? tp->t_inpcb : NULL); break; #endif /* INET6 */ case AF_INET: ip->ip_len = htons(tlen); ip->ip_ttl = ip_defttl; ip->ip_tos = 0; ip_output(m, NULL, tp ? &tp->t_inpcb->inp_route : NULL, ip_mtudisc ? IP_MTUDISC : 0, NULL, tp ? tp->t_inpcb : NULL, 0); break; } } /* * Create a new TCP control block, making an * empty reassembly queue and hooking it to the argument * protocol control block. */ struct tcpcb * tcp_newtcpcb(struct inpcb *inp) { struct tcpcb *tp; int i; tp = pool_get(&tcpcb_pool, PR_NOWAIT|PR_ZERO); if (tp == NULL) return (NULL); TAILQ_INIT(&tp->t_segq); tp->t_maxseg = tcp_mssdflt; tp->t_maxopd = 0; TCP_INIT_DELACK(tp); for (i = 0; i < TCPT_NTIMERS; i++) TCP_TIMER_INIT(tp, i); timeout_set(&tp->t_reap_to, tcp_reaper, tp); #ifdef TCP_SACK tp->sack_enable = tcp_do_sack; #endif tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; tp->t_inpcb = inp; /* * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives * reasonable initial retransmit time. */ tp->t_srtt = TCPTV_SRTTBASE; tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << (TCP_RTTVAR_SHIFT + TCP_RTT_BASE_SHIFT - 1); tp->t_rttmin = TCPTV_MIN; TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), TCPTV_MIN, TCPTV_REXMTMAX); tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; tp->t_pmtud_mtu_sent = 0; tp->t_pmtud_mss_acked = 0; #ifdef INET6 /* we disallow IPv4 mapped address completely. */ if ((inp->inp_flags & INP_IPV6) == 0) tp->pf = PF_INET; else tp->pf = PF_INET6; #else tp->pf = PF_INET; #endif #ifdef INET6 if (inp->inp_flags & INP_IPV6) inp->inp_ipv6.ip6_hlim = ip6_defhlim; else #endif /* INET6 */ inp->inp_ip.ip_ttl = ip_defttl; inp->inp_ppcb = (caddr_t)tp; return (tp); } /* * Drop a TCP connection, reporting * the specified error. If connection is synchronized, * then send a RST to peer. */ struct tcpcb * tcp_drop(struct tcpcb *tp, int errno) { struct socket *so = tp->t_inpcb->inp_socket; if (TCPS_HAVERCVDSYN(tp->t_state)) { tp->t_state = TCPS_CLOSED; (void) tcp_output(tp); tcpstat.tcps_drops++; } else tcpstat.tcps_conndrops++; if (errno == ETIMEDOUT && tp->t_softerror) errno = tp->t_softerror; so->so_error = errno; return (tcp_close(tp)); } /* * Close a TCP control block: * discard all space held by the tcp * discard internet protocol block * wake up any sleepers */ struct tcpcb * tcp_close(struct tcpcb *tp) { struct inpcb *inp = tp->t_inpcb; struct socket *so = inp->inp_socket; #ifdef TCP_SACK struct sackhole *p, *q; #endif /* free the reassembly queue, if any */ tcp_freeq(tp); tcp_canceltimers(tp); TCP_CLEAR_DELACK(tp); syn_cache_cleanup(tp); #ifdef TCP_SACK /* Free SACK holes. */ q = p = tp->snd_holes; while (p != 0) { q = p->next; pool_put(&sackhl_pool, p); p = q; } #endif m_free(tp->t_template); tp->t_flags |= TF_DEAD; timeout_add(&tp->t_reap_to, 0); inp->inp_ppcb = 0; soisdisconnected(so); in_pcbdetach(inp); return (NULL); } void tcp_reaper(void *arg) { struct tcpcb *tp = arg; pool_put(&tcpcb_pool, tp); tcpstat.tcps_closed++; } int tcp_freeq(struct tcpcb *tp) { struct tcpqent *qe; int rv = 0; while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { TAILQ_REMOVE(&tp->t_segq, qe, tcpqe_q); m_freem(qe->tcpqe_m); pool_put(&tcpqe_pool, qe); rv = 1; } return (rv); } /* * Compute proper scaling value for receiver window from buffer space */ void tcp_rscale(struct tcpcb *tp, u_long hiwat) { tp->request_r_scale = 0; while (tp->request_r_scale < TCP_MAX_WINSHIFT && TCP_MAXWIN << tp->request_r_scale < hiwat) tp->request_r_scale++; } /* * Notify a tcp user of an asynchronous error; * store error as soft error, but wake up user * (for now, won't do anything until can select for soft error). */ void tcp_notify(struct inpcb *inp, int error) { struct tcpcb *tp = intotcpcb(inp); struct socket *so = inp->inp_socket; /* * Ignore some errors if we are hooked up. * If connection hasn't completed, has retransmitted several times, * and receives a second error, give up now. This is better * than waiting a long time to establish a connection that * can never complete. */ if (tp->t_state == TCPS_ESTABLISHED && (error == EHOSTUNREACH || error == ENETUNREACH || error == EHOSTDOWN)) { return; } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 && tp->t_rxtshift > 3 && tp->t_softerror) so->so_error = error; else tp->t_softerror = error; wakeup((caddr_t) &so->so_timeo); sorwakeup(so); sowwakeup(so); } #ifdef INET6 void tcp6_ctlinput(int cmd, struct sockaddr *sa, u_int rdomain, void *d) { struct tcphdr th; struct tcpcb *tp; void (*notify)(struct inpcb *, int) = tcp_notify; struct ip6_hdr *ip6; const struct sockaddr_in6 *sa6_src = NULL; struct sockaddr_in6 *sa6 = satosin6(sa); struct inpcb *inp; struct mbuf *m; tcp_seq seq; int off; struct { u_int16_t th_sport; u_int16_t th_dport; u_int32_t th_seq; } *thp; if (sa->sa_family != AF_INET6 || sa->sa_len != sizeof(struct sockaddr_in6) || IN6_IS_ADDR_UNSPECIFIED(&sa6->sin6_addr) || IN6_IS_ADDR_V4MAPPED(&sa6->sin6_addr)) return; if ((unsigned)cmd >= PRC_NCMDS) return; else if (cmd == PRC_QUENCH) { /* * Don't honor ICMP Source Quench messages meant for * TCP connections. */ /* XXX there's no PRC_QUENCH in IPv6 */ return; } else if (PRC_IS_REDIRECT(cmd)) notify = in_rtchange, d = NULL; else if (cmd == PRC_MSGSIZE) ; /* special code is present, see below */ else if (cmd == PRC_HOSTDEAD) d = NULL; else if (inet6ctlerrmap[cmd] == 0) return; /* if the parameter is from icmp6, decode it. */ if (d != NULL) { struct ip6ctlparam *ip6cp = (struct ip6ctlparam *)d; m = ip6cp->ip6c_m; ip6 = ip6cp->ip6c_ip6; off = ip6cp->ip6c_off; sa6_src = ip6cp->ip6c_src; } else { m = NULL; ip6 = NULL; sa6_src = &sa6_any; } if (ip6) { /* * XXX: We assume that when ip6 is non NULL, * M and OFF are valid. */ /* check if we can safely examine src and dst ports */ if (m->m_pkthdr.len < off + sizeof(*thp)) return; bzero(&th, sizeof(th)); #ifdef DIAGNOSTIC if (sizeof(*thp) > sizeof(th)) panic("assumption failed in tcp6_ctlinput"); #endif m_copydata(m, off, sizeof(*thp), (caddr_t)&th); /* * Check to see if we have a valid TCP connection * corresponding to the address in the ICMPv6 message * payload. */ inp = in6_pcbhashlookup(&tcbtable, &sa6->sin6_addr, th.th_dport, (struct in6_addr *)&sa6_src->sin6_addr, th.th_sport, rdomain); if (cmd == PRC_MSGSIZE) { /* * Depending on the value of "valid" and routing table * size (mtudisc_{hi,lo}wat), we will: * - recalcurate the new MTU and create the * corresponding routing entry, or * - ignore the MTU change notification. */ icmp6_mtudisc_update((struct ip6ctlparam *)d, inp != NULL); return; } if (inp) { seq = ntohl(th.th_seq); if (inp->inp_socket && (tp = intotcpcb(inp)) && SEQ_GEQ(seq, tp->snd_una) && SEQ_LT(seq, tp->snd_max)) notify(inp, inet6ctlerrmap[cmd]); } else if (inet6ctlerrmap[cmd] == EHOSTUNREACH || inet6ctlerrmap[cmd] == ENETUNREACH || inet6ctlerrmap[cmd] == EHOSTDOWN) syn_cache_unreach((struct sockaddr *)sa6_src, sa, &th, rdomain); } else { (void) in6_pcbnotify(&tcbtable, sa6, 0, sa6_src, 0, rdomain, cmd, NULL, notify); } } #endif void * tcp_ctlinput(int cmd, struct sockaddr *sa, u_int rdomain, void *v) { struct ip *ip = v; struct tcphdr *th; struct tcpcb *tp; struct inpcb *inp; struct in_addr faddr; tcp_seq seq; u_int mtu; void (*notify)(struct inpcb *, int) = tcp_notify; int errno; if (sa->sa_family != AF_INET) return NULL; faddr = satosin(sa)->sin_addr; if (faddr.s_addr == INADDR_ANY) return NULL; if ((unsigned)cmd >= PRC_NCMDS) return NULL; errno = inetctlerrmap[cmd]; if (cmd == PRC_QUENCH) /* * Don't honor ICMP Source Quench messages meant for * TCP connections. */ return NULL; else if (PRC_IS_REDIRECT(cmd)) notify = in_rtchange, ip = 0; else if (cmd == PRC_MSGSIZE && ip_mtudisc && ip) { /* * Verify that the packet in the icmp payload refers * to an existing TCP connection. */ th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); seq = ntohl(th->th_seq); inp = in_pcbhashlookup(&tcbtable, ip->ip_dst, th->th_dport, ip->ip_src, th->th_sport, rdomain); if (inp && (tp = intotcpcb(inp)) && SEQ_GEQ(seq, tp->snd_una) && SEQ_LT(seq, tp->snd_max)) { struct icmp *icp; icp = (struct icmp *)((caddr_t)ip - offsetof(struct icmp, icmp_ip)); /* * If the ICMP message advertises a Next-Hop MTU * equal or larger than the maximum packet size we have * ever sent, drop the message. */ mtu = (u_int)ntohs(icp->icmp_nextmtu); if (mtu >= tp->t_pmtud_mtu_sent) return NULL; if (mtu >= tcp_hdrsz(tp) + tp->t_pmtud_mss_acked) { /* * Calculate new MTU, and create corresponding * route (traditional PMTUD). */ tp->t_flags &= ~TF_PMTUD_PEND; icmp_mtudisc(icp, inp->inp_rtableid); } else { /* * Record the information got in the ICMP * message; act on it later. * If we had already recorded an ICMP message, * replace the old one only if the new message * refers to an older TCP segment */ if (tp->t_flags & TF_PMTUD_PEND) { if (SEQ_LT(tp->t_pmtud_th_seq, seq)) return NULL; } else tp->t_flags |= TF_PMTUD_PEND; tp->t_pmtud_th_seq = seq; tp->t_pmtud_nextmtu = icp->icmp_nextmtu; tp->t_pmtud_ip_len = icp->icmp_ip.ip_len; tp->t_pmtud_ip_hl = icp->icmp_ip.ip_hl; return NULL; } } else { /* ignore if we don't have a matching connection */ return NULL; } notify = tcp_mtudisc, ip = 0; } else if (cmd == PRC_MTUINC) notify = tcp_mtudisc_increase, ip = 0; else if (cmd == PRC_HOSTDEAD) ip = 0; else if (errno == 0) return NULL; if (ip) { th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); inp = in_pcbhashlookup(&tcbtable, ip->ip_dst, th->th_dport, ip->ip_src, th->th_sport, rdomain); if (inp) { seq = ntohl(th->th_seq); if (inp->inp_socket && (tp = intotcpcb(inp)) && SEQ_GEQ(seq, tp->snd_una) && SEQ_LT(seq, tp->snd_max)) notify(inp, errno); } else if (inetctlerrmap[cmd] == EHOSTUNREACH || inetctlerrmap[cmd] == ENETUNREACH || inetctlerrmap[cmd] == EHOSTDOWN) { struct sockaddr_in sin; bzero(&sin, sizeof(sin)); sin.sin_len = sizeof(sin); sin.sin_family = AF_INET; sin.sin_port = th->th_sport; sin.sin_addr = ip->ip_src; syn_cache_unreach(sintosa(&sin), sa, th, rdomain); } } else in_pcbnotifyall(&tcbtable, sa, rdomain, errno, notify); return NULL; } #ifdef INET6 /* * Path MTU Discovery handlers. */ void tcp6_mtudisc_callback(struct sockaddr_in6 *sin6, u_int rdomain) { (void) in6_pcbnotify(&tcbtable, sin6, 0, &sa6_any, 0, rdomain, PRC_MSGSIZE, NULL, tcp_mtudisc); } #endif /* INET6 */ /* * On receipt of path MTU corrections, flush old route and replace it * with the new one. Retransmit all unacknowledged packets, to ensure * that all packets will be received. */ void tcp_mtudisc(struct inpcb *inp, int errno) { struct tcpcb *tp = intotcpcb(inp); struct rtentry *rt = in_pcbrtentry(inp); int change = 0; if (tp != 0) { int orig_maxseg = tp->t_maxseg; if (rt != 0) { /* * If this was not a host route, remove and realloc. */ if ((rt->rt_flags & RTF_HOST) == 0) { in_rtchange(inp, errno); if ((rt = in_pcbrtentry(inp)) == 0) return; } if (orig_maxseg != tp->t_maxseg || (rt->rt_rmx.rmx_locks & RTV_MTU)) change = 1; } tcp_mss(tp, -1); /* * Resend unacknowledged packets */ tp->snd_nxt = tp->snd_una; if (change || errno > 0) tcp_output(tp); } } void tcp_mtudisc_increase(struct inpcb *inp, int errno) { struct tcpcb *tp = intotcpcb(inp); struct rtentry *rt = in_pcbrtentry(inp); if (tp != 0 && rt != 0) { /* * If this was a host route, remove and realloc. */ if (rt->rt_flags & RTF_HOST) in_rtchange(inp, errno); /* also takes care of congestion window */ tcp_mss(tp, -1); } } /* * Generate new ISNs with a method based on RFC1948 */ #define TCP_ISS_CONN_INC 4096 int tcp_secret_init; u_char tcp_secret[16]; SHA2_CTX tcp_secret_ctx; void tcp_set_iss_tsm(struct tcpcb *tp) { SHA2_CTX ctx; union { uint8_t bytes[SHA512_DIGEST_LENGTH]; uint32_t words[2]; } digest; u_int rdomain = rtable_l2(tp->t_inpcb->inp_rtableid); if (tcp_secret_init == 0) { arc4random_buf(tcp_secret, sizeof(tcp_secret)); SHA512Init(&tcp_secret_ctx); SHA512Update(&tcp_secret_ctx, tcp_secret, sizeof(tcp_secret)); tcp_secret_init = 1; } ctx = tcp_secret_ctx; SHA512Update(&ctx, &rdomain, sizeof(rdomain)); SHA512Update(&ctx, &tp->t_inpcb->inp_lport, sizeof(u_short)); SHA512Update(&ctx, &tp->t_inpcb->inp_fport, sizeof(u_short)); if (tp->pf == AF_INET6) { SHA512Update(&ctx, &tp->t_inpcb->inp_laddr6, sizeof(struct in6_addr)); SHA512Update(&ctx, &tp->t_inpcb->inp_faddr6, sizeof(struct in6_addr)); } else { SHA512Update(&ctx, &tp->t_inpcb->inp_laddr, sizeof(struct in_addr)); SHA512Update(&ctx, &tp->t_inpcb->inp_faddr, sizeof(struct in_addr)); } SHA512Final(digest.bytes, &ctx); tcp_iss += TCP_ISS_CONN_INC; tp->iss = digest.words[0] + tcp_iss; tp->ts_modulate = digest.words[1]; } #ifdef TCP_SIGNATURE int tcp_signature_tdb_attach(void) { return (0); } int tcp_signature_tdb_init(struct tdb *tdbp, struct xformsw *xsp, struct ipsecinit *ii) { if ((ii->ii_authkeylen < 1) || (ii->ii_authkeylen > 80)) return (EINVAL); tdbp->tdb_amxkey = malloc(ii->ii_authkeylen, M_XDATA, M_NOWAIT); if (tdbp->tdb_amxkey == NULL) return (ENOMEM); bcopy(ii->ii_authkey, tdbp->tdb_amxkey, ii->ii_authkeylen); tdbp->tdb_amxkeylen = ii->ii_authkeylen; return (0); } int tcp_signature_tdb_zeroize(struct tdb *tdbp) { if (tdbp->tdb_amxkey) { explicit_bzero(tdbp->tdb_amxkey, tdbp->tdb_amxkeylen); free(tdbp->tdb_amxkey, M_XDATA, 0); tdbp->tdb_amxkey = NULL; } return (0); } int tcp_signature_tdb_input(struct mbuf *m, struct tdb *tdbp, int skip, int protoff) { return (0); } int tcp_signature_tdb_output(struct mbuf *m, struct tdb *tdbp, struct mbuf **mp, int skip, int protoff) { return (EINVAL); } int tcp_signature_apply(caddr_t fstate, caddr_t data, unsigned int len) { MD5Update((MD5_CTX *)fstate, (char *)data, len); return 0; } int tcp_signature(struct tdb *tdb, int af, struct mbuf *m, struct tcphdr *th, int iphlen, int doswap, char *sig) { MD5_CTX ctx; int len; struct tcphdr th0; MD5Init(&ctx); switch(af) { case 0: case AF_INET: { struct ippseudo ippseudo; struct ip *ip; ip = mtod(m, struct ip *); ippseudo.ippseudo_src = ip->ip_src; ippseudo.ippseudo_dst = ip->ip_dst; ippseudo.ippseudo_pad = 0; ippseudo.ippseudo_p = IPPROTO_TCP; ippseudo.ippseudo_len = htons(m->m_pkthdr.len - iphlen); MD5Update(&ctx, (char *)&ippseudo, sizeof(struct ippseudo)); break; } #ifdef INET6 case AF_INET6: { struct ip6_hdr_pseudo ip6pseudo; struct ip6_hdr *ip6; ip6 = mtod(m, struct ip6_hdr *); bzero(&ip6pseudo, sizeof(ip6pseudo)); ip6pseudo.ip6ph_src = ip6->ip6_src; ip6pseudo.ip6ph_dst = ip6->ip6_dst; in6_clearscope(&ip6pseudo.ip6ph_src); in6_clearscope(&ip6pseudo.ip6ph_dst); ip6pseudo.ip6ph_nxt = IPPROTO_TCP; ip6pseudo.ip6ph_len = htonl(m->m_pkthdr.len - iphlen); MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); break; } #endif } th0 = *th; th0.th_sum = 0; if (doswap) { th0.th_seq = htonl(th0.th_seq); th0.th_ack = htonl(th0.th_ack); th0.th_win = htons(th0.th_win); th0.th_urp = htons(th0.th_urp); } MD5Update(&ctx, (char *)&th0, sizeof(th0)); len = m->m_pkthdr.len - iphlen - th->th_off * sizeof(uint32_t); if (len > 0 && m_apply(m, iphlen + th->th_off * sizeof(uint32_t), len, tcp_signature_apply, (caddr_t)&ctx)) return (-1); MD5Update(&ctx, tdb->tdb_amxkey, tdb->tdb_amxkeylen); MD5Final(sig, &ctx); return (0); } #endif /* TCP_SIGNATURE */