Index: head/sys/netinet/tcp_timewait.c =================================================================== --- head/sys/netinet/tcp_timewait.c (revision 324178) +++ head/sys/netinet/tcp_timewait.c (revision 324179) @@ -1,739 +1,758 @@ /*- * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 * 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. * * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 */ #include __FBSDID("$FreeBSD$"); #include "opt_inet.h" #include "opt_inet6.h" #include "opt_tcpdebug.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef INET6 #include #include #include #include #include #endif #include #include #include #include #include #ifdef INET6 #include #endif #include #ifdef TCPDEBUG #include #endif #ifdef INET6 #include #endif #include #include static VNET_DEFINE(uma_zone_t, tcptw_zone); #define V_tcptw_zone VNET(tcptw_zone) static int maxtcptw; /* * The timed wait queue contains references to each of the TCP sessions * currently in the TIME_WAIT state. The queue pointers, including the * queue pointers in each tcptw structure, are protected using the global * timewait lock, which must be held over queue iteration and modification. * * Rules on tcptw usage: * - a inpcb is always freed _after_ its tcptw * - a tcptw relies on its inpcb reference counting for memory stability * - a tcptw is dereferenceable only while its inpcb is locked */ static VNET_DEFINE(TAILQ_HEAD(, tcptw), twq_2msl); #define V_twq_2msl VNET(twq_2msl) /* Global timewait lock */ static VNET_DEFINE(struct rwlock, tw_lock); #define V_tw_lock VNET(tw_lock) #define TW_LOCK_INIT(tw, d) rw_init_flags(&(tw), (d), 0) #define TW_LOCK_DESTROY(tw) rw_destroy(&(tw)) #define TW_RLOCK(tw) rw_rlock(&(tw)) #define TW_WLOCK(tw) rw_wlock(&(tw)) #define TW_RUNLOCK(tw) rw_runlock(&(tw)) #define TW_WUNLOCK(tw) rw_wunlock(&(tw)) #define TW_LOCK_ASSERT(tw) rw_assert(&(tw), RA_LOCKED) #define TW_RLOCK_ASSERT(tw) rw_assert(&(tw), RA_RLOCKED) #define TW_WLOCK_ASSERT(tw) rw_assert(&(tw), RA_WLOCKED) #define TW_UNLOCK_ASSERT(tw) rw_assert(&(tw), RA_UNLOCKED) static void tcp_tw_2msl_reset(struct tcptw *, int); static void tcp_tw_2msl_stop(struct tcptw *, int); static int tcp_twrespond(struct tcptw *, int); static int tcptw_auto_size(void) { int halfrange; /* * Max out at half the ephemeral port range so that TIME_WAIT * sockets don't tie up too many ephemeral ports. */ if (V_ipport_lastauto > V_ipport_firstauto) halfrange = (V_ipport_lastauto - V_ipport_firstauto) / 2; else halfrange = (V_ipport_firstauto - V_ipport_lastauto) / 2; /* Protect against goofy port ranges smaller than 32. */ return (imin(imax(halfrange, 32), maxsockets / 5)); } static int sysctl_maxtcptw(SYSCTL_HANDLER_ARGS) { int error, new; if (maxtcptw == 0) new = tcptw_auto_size(); else new = maxtcptw; error = sysctl_handle_int(oidp, &new, 0, req); if (error == 0 && req->newptr) if (new >= 32) { maxtcptw = new; uma_zone_set_max(V_tcptw_zone, maxtcptw); } return (error); } SYSCTL_PROC(_net_inet_tcp, OID_AUTO, maxtcptw, CTLTYPE_INT|CTLFLAG_RW, &maxtcptw, 0, sysctl_maxtcptw, "IU", "Maximum number of compressed TCP TIME_WAIT entries"); VNET_DEFINE(int, nolocaltimewait) = 0; #define V_nolocaltimewait VNET(nolocaltimewait) SYSCTL_INT(_net_inet_tcp, OID_AUTO, nolocaltimewait, CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(nolocaltimewait), 0, "Do not create compressed TCP TIME_WAIT entries for local connections"); void tcp_tw_zone_change(void) { if (maxtcptw == 0) uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); } void tcp_tw_init(void) { V_tcptw_zone = uma_zcreate("tcptw", sizeof(struct tcptw), NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); TUNABLE_INT_FETCH("net.inet.tcp.maxtcptw", &maxtcptw); if (maxtcptw == 0) uma_zone_set_max(V_tcptw_zone, tcptw_auto_size()); else uma_zone_set_max(V_tcptw_zone, maxtcptw); TAILQ_INIT(&V_twq_2msl); TW_LOCK_INIT(V_tw_lock, "tcptw"); } #ifdef VIMAGE void tcp_tw_destroy(void) { struct tcptw *tw; INP_INFO_RLOCK(&V_tcbinfo); while ((tw = TAILQ_FIRST(&V_twq_2msl)) != NULL) tcp_twclose(tw, 0); INP_INFO_RUNLOCK(&V_tcbinfo); TW_LOCK_DESTROY(V_tw_lock); uma_zdestroy(V_tcptw_zone); } #endif /* * Move a TCP connection into TIME_WAIT state. * tcbinfo is locked. * inp is locked, and is unlocked before returning. */ void tcp_twstart(struct tcpcb *tp) { struct tcptw *tw; struct inpcb *inp = tp->t_inpcb; int acknow; struct socket *so; #ifdef INET6 int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; #endif INP_INFO_RLOCK_ASSERT(&V_tcbinfo); INP_WLOCK_ASSERT(inp); /* A dropped inp should never transition to TIME_WAIT state. */ KASSERT((inp->inp_flags & INP_DROPPED) == 0, ("tcp_twstart: " "(inp->inp_flags & INP_DROPPED) != 0")); if (V_nolocaltimewait) { int error = 0; #ifdef INET6 if (isipv6) error = in6_localaddr(&inp->in6p_faddr); #endif #if defined(INET6) && defined(INET) else #endif #ifdef INET error = in_localip(inp->inp_faddr); #endif if (error) { tp = tcp_close(tp); if (tp != NULL) INP_WUNLOCK(inp); return; } } /* * For use only by DTrace. We do not reference the state * after this point so modifying it in place is not a problem. */ tcp_state_change(tp, TCPS_TIME_WAIT); tw = uma_zalloc(V_tcptw_zone, M_NOWAIT); if (tw == NULL) { /* * Reached limit on total number of TIMEWAIT connections * allowed. Remove a connection from TIMEWAIT queue in LRU * fashion to make room for this connection. * * XXX: Check if it possible to always have enough room * in advance based on guarantees provided by uma_zalloc(). */ tw = tcp_tw_2msl_scan(1); if (tw == NULL) { tp = tcp_close(tp); if (tp != NULL) INP_WUNLOCK(inp); return; } } /* * The tcptw will hold a reference on its inpcb until tcp_twclose * is called */ tw->tw_inpcb = inp; in_pcbref(inp); /* Reference from tw */ /* * Recover last window size sent. */ if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) tw->last_win = (tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale; else tw->last_win = 0; /* * Set t_recent if timestamps are used on the connection. */ if ((tp->t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP|TF_NOOPT)) == (TF_REQ_TSTMP|TF_RCVD_TSTMP)) { tw->t_recent = tp->ts_recent; tw->ts_offset = tp->ts_offset; } else { tw->t_recent = 0; tw->ts_offset = 0; } tw->snd_nxt = tp->snd_nxt; tw->rcv_nxt = tp->rcv_nxt; tw->iss = tp->iss; tw->irs = tp->irs; tw->t_starttime = tp->t_starttime; tw->tw_time = 0; /* XXX * If this code will * be used for fin-wait-2 state also, then we may need * a ts_recent from the last segment. */ acknow = tp->t_flags & TF_ACKNOW; /* * First, discard tcpcb state, which includes stopping its timers and * freeing it. tcp_discardcb() used to also release the inpcb, but * that work is now done in the caller. * * Note: soisdisconnected() call used to be made in tcp_discardcb(), * and might not be needed here any longer. */ tcp_discardcb(tp); so = inp->inp_socket; soisdisconnected(so); tw->tw_cred = crhold(so->so_cred); SOCK_LOCK(so); tw->tw_so_options = so->so_options; SOCK_UNLOCK(so); if (acknow) tcp_twrespond(tw, TH_ACK); inp->inp_ppcb = tw; inp->inp_flags |= INP_TIMEWAIT; TCPSTATES_INC(TCPS_TIME_WAIT); tcp_tw_2msl_reset(tw, 0); /* * If the inpcb owns the sole reference to the socket, then we can * detach and free the socket as it is not needed in time wait. */ if (inp->inp_flags & INP_SOCKREF) { KASSERT(so->so_state & SS_PROTOREF, ("tcp_twstart: !SS_PROTOREF")); inp->inp_flags &= ~INP_SOCKREF; INP_WUNLOCK(inp); SOCK_LOCK(so); so->so_state &= ~SS_PROTOREF; sofree(so); } else INP_WUNLOCK(inp); } /* * Returns 1 if the TIME_WAIT state was killed and we should start over, * looking for a pcb in the listen state. Returns 0 otherwise. */ int tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th, struct mbuf *m, int tlen) { struct tcptw *tw; int thflags; tcp_seq seq; INP_INFO_RLOCK_ASSERT(&V_tcbinfo); INP_WLOCK_ASSERT(inp); /* * XXXRW: Time wait state for inpcb has been recycled, but inpcb is * still present. This is undesirable, but temporarily necessary * until we work out how to handle inpcb's who's timewait state has * been removed. */ tw = intotw(inp); if (tw == NULL) goto drop; thflags = th->th_flags; /* * NOTE: for FIN_WAIT_2 (to be added later), * must validate sequence number before accepting RST */ /* * If the segment contains RST: * Drop the segment - see Stevens, vol. 2, p. 964 and * RFC 1337. */ if (thflags & TH_RST) goto drop; #if 0 /* PAWS not needed at the moment */ /* * RFC 1323 PAWS: If we have a timestamp reply on this segment * and it's less than ts_recent, drop it. */ if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && TSTMP_LT(to.to_tsval, tp->ts_recent)) { if ((thflags & TH_ACK) == 0) goto drop; goto ack; } /* * ts_recent is never updated because we never accept new segments. */ #endif /* * If a new connection request is received * while in TIME_WAIT, drop the old connection * and start over if the sequence numbers * are above the previous ones. */ if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { tcp_twclose(tw, 0); return (1); } /* * Drop the segment if it does not contain an ACK. */ if ((thflags & TH_ACK) == 0) goto drop; /* * Reset the 2MSL timer if this is a duplicate FIN. */ if (thflags & TH_FIN) { seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); if (seq + 1 == tw->rcv_nxt) tcp_tw_2msl_reset(tw, 1); } /* * Acknowledge the segment if it has data or is not a duplicate ACK. */ if (thflags != TH_ACK || tlen != 0 || th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) tcp_twrespond(tw, TH_ACK); drop: INP_WUNLOCK(inp); m_freem(m); return (0); } void tcp_twclose(struct tcptw *tw, int reuse) { struct socket *so; struct inpcb *inp; /* * At this point, we are in one of two situations: * * (1) We have no socket, just an inpcb<->twtcp pair. We can free * all state. * * (2) We have a socket -- if we own a reference, release it and * notify the socket layer. */ inp = tw->tw_inpcb; KASSERT((inp->inp_flags & INP_TIMEWAIT), ("tcp_twclose: !timewait")); KASSERT(intotw(inp) == tw, ("tcp_twclose: inp_ppcb != tw")); INP_INFO_RLOCK_ASSERT(&V_tcbinfo); /* in_pcbfree() */ INP_WLOCK_ASSERT(inp); tcp_tw_2msl_stop(tw, reuse); inp->inp_ppcb = NULL; in_pcbdrop(inp); so = inp->inp_socket; if (so != NULL) { /* * If there's a socket, handle two cases: first, we own a * strong reference, which we will now release, or we don't * in which case another reference exists (XXXRW: think * about this more), and we don't need to take action. */ if (inp->inp_flags & INP_SOCKREF) { inp->inp_flags &= ~INP_SOCKREF; INP_WUNLOCK(inp); SOCK_LOCK(so); KASSERT(so->so_state & SS_PROTOREF, ("tcp_twclose: INP_SOCKREF && !SS_PROTOREF")); so->so_state &= ~SS_PROTOREF; sofree(so); } else { /* * If we don't own the only reference, the socket and * inpcb need to be left around to be handled by * tcp_usr_detach() later. */ INP_WUNLOCK(inp); } } else { /* * The socket has been already cleaned-up for us, only free the * inpcb. */ in_pcbfree(inp); } TCPSTAT_INC(tcps_closed); } static int tcp_twrespond(struct tcptw *tw, int flags) { struct inpcb *inp = tw->tw_inpcb; #if defined(INET6) || defined(INET) struct tcphdr *th = NULL; #endif struct mbuf *m; #ifdef INET struct ip *ip = NULL; #endif u_int hdrlen, optlen; int error = 0; /* Keep compiler happy */ struct tcpopt to; #ifdef INET6 struct ip6_hdr *ip6 = NULL; int isipv6 = inp->inp_inc.inc_flags & INC_ISIPV6; #endif hdrlen = 0; /* Keep compiler happy */ INP_WLOCK_ASSERT(inp); m = m_gethdr(M_NOWAIT, MT_DATA); if (m == NULL) return (ENOBUFS); m->m_data += max_linkhdr; #ifdef MAC mac_inpcb_create_mbuf(inp, m); #endif #ifdef INET6 if (isipv6) { hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)(ip6 + 1); tcpip_fillheaders(inp, ip6, th); } #endif #if defined(INET6) && defined(INET) else #endif #ifdef INET { hdrlen = sizeof(struct tcpiphdr); ip = mtod(m, struct ip *); th = (struct tcphdr *)(ip + 1); tcpip_fillheaders(inp, ip, th); } #endif to.to_flags = 0; /* * Send a timestamp and echo-reply if both our side and our peer * have sent timestamps in our SYN's and this is not a RST. */ if (tw->t_recent && flags == TH_ACK) { to.to_flags |= TOF_TS; to.to_tsval = tcp_ts_getticks() + tw->ts_offset; to.to_tsecr = tw->t_recent; } optlen = tcp_addoptions(&to, (u_char *)(th + 1)); m->m_len = hdrlen + optlen; m->m_pkthdr.len = m->m_len; KASSERT(max_linkhdr + m->m_len <= MHLEN, ("tcptw: mbuf too small")); th->th_seq = htonl(tw->snd_nxt); th->th_ack = htonl(tw->rcv_nxt); th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; th->th_flags = flags; th->th_win = htons(tw->last_win); m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); #ifdef INET6 if (isipv6) { m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; th->th_sum = in6_cksum_pseudo(ip6, sizeof(struct tcphdr) + optlen, IPPROTO_TCP, 0); ip6->ip6_hlim = in6_selecthlim(inp, NULL); error = ip6_output(m, inp->in6p_outputopts, NULL, (tw->tw_so_options & SO_DONTROUTE), NULL, NULL, inp); } #endif #if defined(INET6) && defined(INET) else #endif #ifdef INET { m->m_pkthdr.csum_flags = CSUM_TCP; th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr, htons(sizeof(struct tcphdr) + optlen + IPPROTO_TCP)); ip->ip_len = htons(m->m_pkthdr.len); if (V_path_mtu_discovery) ip->ip_off |= htons(IP_DF); error = ip_output(m, inp->inp_options, NULL, ((tw->tw_so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), NULL, inp); } #endif if (flags & TH_ACK) TCPSTAT_INC(tcps_sndacks); else TCPSTAT_INC(tcps_sndctrl); TCPSTAT_INC(tcps_sndtotal); return (error); } static void tcp_tw_2msl_reset(struct tcptw *tw, int rearm) { INP_INFO_RLOCK_ASSERT(&V_tcbinfo); INP_WLOCK_ASSERT(tw->tw_inpcb); TW_WLOCK(V_tw_lock); if (rearm) TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); tw->tw_time = ticks + 2 * tcp_msl; TAILQ_INSERT_TAIL(&V_twq_2msl, tw, tw_2msl); TW_WUNLOCK(V_tw_lock); } static void tcp_tw_2msl_stop(struct tcptw *tw, int reuse) { struct ucred *cred; struct inpcb *inp; int released; INP_INFO_RLOCK_ASSERT(&V_tcbinfo); TW_WLOCK(V_tw_lock); inp = tw->tw_inpcb; tw->tw_inpcb = NULL; TAILQ_REMOVE(&V_twq_2msl, tw, tw_2msl); cred = tw->tw_cred; tw->tw_cred = NULL; TW_WUNLOCK(V_tw_lock); if (cred != NULL) crfree(cred); released = in_pcbrele_wlocked(inp); KASSERT(!released, ("%s: inp should not be released here", __func__)); if (!reuse) uma_zfree(V_tcptw_zone, tw); TCPSTATES_DEC(TCPS_TIME_WAIT); } struct tcptw * tcp_tw_2msl_scan(int reuse) { struct tcptw *tw; struct inpcb *inp; #ifdef INVARIANTS if (reuse) { /* * Exclusive pcbinfo lock is not required in reuse case even if * two inpcb locks can be acquired simultaneously: * - the inpcb transitioning to TIME_WAIT state in * tcp_tw_start(), * - the inpcb closed by tcp_twclose(). * * It is because only inpcbs in FIN_WAIT2 or CLOSING states can * transition in TIME_WAIT state. Then a pcbcb cannot be in * TIME_WAIT list and transitioning to TIME_WAIT state at same * time. */ INP_INFO_RLOCK_ASSERT(&V_tcbinfo); } #endif for (;;) { TW_RLOCK(V_tw_lock); tw = TAILQ_FIRST(&V_twq_2msl); if (tw == NULL || (!reuse && (tw->tw_time - ticks) > 0)) { TW_RUNLOCK(V_tw_lock); break; } KASSERT(tw->tw_inpcb != NULL, ("%s: tw->tw_inpcb == NULL", __func__)); inp = tw->tw_inpcb; in_pcbref(inp); TW_RUNLOCK(V_tw_lock); if (INP_INFO_TRY_RLOCK(&V_tcbinfo)) { INP_WLOCK(inp); tw = intotw(inp); if (in_pcbrele_wlocked(inp)) { - KASSERT(tw == NULL, ("%s: held last inp " - "reference but tw not NULL", __func__)); - INP_INFO_RUNLOCK(&V_tcbinfo); - continue; + if (__predict_true(tw == NULL)) { + INP_INFO_RUNLOCK(&V_tcbinfo); + continue; + } else { + /* This should not happen as in TIMEWAIT + * state the inp should not be destroyed + * before its tcptw. If INVARIANTS is + * defined panic. + */ +#ifdef INVARIANTS + panic("%s: Panic before an infinite " + "loop: INP_TIMEWAIT && (INP_FREED " + "|| inp last reference) && tw != " + "NULL", __func__); +#else + log(LOG_ERR, "%s: Avoid an infinite " + "loop: INP_TIMEWAIT && (INP_FREED " + "|| inp last reference) && tw != " + "NULL", __func__); +#endif + INP_INFO_RUNLOCK(&V_tcbinfo); + break; + } } if (tw == NULL) { /* tcp_twclose() has already been called */ INP_WUNLOCK(inp); INP_INFO_RUNLOCK(&V_tcbinfo); continue; } tcp_twclose(tw, reuse); INP_INFO_RUNLOCK(&V_tcbinfo); if (reuse) return tw; } else { /* INP_INFO lock is busy, continue later. */ INP_WLOCK(inp); if (!in_pcbrele_wlocked(inp)) INP_WUNLOCK(inp); break; } } return NULL; }