svn commit: r368181 - in stable/12/sys/netinet: . tcp_stacks
Kyle Evans
kevans at freebsd.org
Wed Jan 13 15:16:52 UTC 2021
On Wed, Jan 6, 2021 at 9:01 AM Kyle Evans <kevans at freebsd.org> wrote:
>
> On Mon, Nov 30, 2020 at 3:45 AM Michael Tuexen <tuexen at freebsd.org> wrote:
> >
> > Author: tuexen
> > Date: Mon Nov 30 09:45:44 2020
> > New Revision: 368181
> > URL: https://svnweb.freebsd.org/changeset/base/368181
> >
> > Log:
> > MFC r367530:
> > RFC 7323 specifies that:
> > * TCP segments without timestamps should be dropped when support for
> > the timestamp option has been negotiated.
> > * TCP segments with timestamps should be processed normally if support
> > for the timestamp option has not been negotiated.
> > This patch enforces the above.
> > Manually resolved merge conflicts.
> >
> > MFC 367891:
> > Fix an issue I introuced in r367530: tcp_twcheck() can be called
> > with to == NULL for SYN segments. So don't assume tp != NULL.
> > Thanks to jhb@ for reporting and suggesting a fix.
> >
> > MFC r367946:
> > Fix two occurences of a typo in a comment introduced in r367530.
> > Thanks to lstewart@ for reporting them.
> >
>
> Hi Michael,
>
> Dmitri (CC'd) spotted a regression in the golang test suite along
> stable/12 and bisected it back to this MFC (reported via
> efnet#bsdports). The test puts up a local HTTP server and attempts to
> close the read-side while the write-side is still going, hopefully
> observing a write failure on the write-side in the process (but it
> never does).
>
> I minimized it to this (rough) reproducer, which shows the write side
> hanging around in CLOSE_WAIT and successfully writing the msg
> repeatedly on recent -CURRENT while 12.2 observes an EPIPE almost
> immediately: https://people.freebsd.org/~kevans/tcpr.c
>
> root at viper:~/grep# sockstat -s | grep 8993
> root a.out 80831 4 tcp4 127.0.0.1:8993 *:*
> LISTEN
> root a.out 80831 5 tcp4 127.0.0.1:8993
> 127.0.0.1:40319 CLOSE_WAIT
> root at viper:~/grep#
>
Ping?
> >
> > Modified:
> > stable/12/sys/netinet/tcp_input.c
> > stable/12/sys/netinet/tcp_stacks/rack.c
> > stable/12/sys/netinet/tcp_syncache.c
> > stable/12/sys/netinet/tcp_timewait.c
> > Directory Properties:
> > stable/12/ (props changed)
> >
> > Modified: stable/12/sys/netinet/tcp_input.c
> > ==============================================================================
> > --- stable/12/sys/netinet/tcp_input.c Mon Nov 30 09:22:33 2020 (r368180)
> > +++ stable/12/sys/netinet/tcp_input.c Mon Nov 30 09:45:44 2020 (r368181)
> > @@ -975,8 +975,8 @@ findpcb:
> > }
> > INP_INFO_RLOCK_ASSERT(&V_tcbinfo);
> >
> > - if (thflags & TH_SYN)
> > - tcp_dooptions(&to, optp, optlen, TO_SYN);
> > + tcp_dooptions(&to, optp, optlen,
> > + (thflags & TH_SYN) ? TO_SYN : 0);
> > /*
> > * NB: tcp_twcheck unlocks the INP and frees the mbuf.
> > */
> > @@ -1706,20 +1706,29 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, stru
> > }
> >
> > /*
> > - * If timestamps were negotiated during SYN/ACK they should
> > - * appear on every segment during this session and vice versa.
> > + * If timestamps were negotiated during SYN/ACK and a
> > + * segment without a timestamp is received, silently drop
> > + * the segment.
> > + * See section 3.2 of RFC 7323.
> > */
> > if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) {
> > if ((s = tcp_log_addrs(inc, th, NULL, NULL))) {
> > log(LOG_DEBUG, "%s; %s: Timestamp missing, "
> > - "no action\n", s, __func__);
> > + "segment silently dropped\n", s, __func__);
> > free(s, M_TCPLOG);
> > }
> > + goto drop;
> > }
> > + /*
> > + * If timestamps were not negotiated during SYN/ACK and a
> > + * segment with a timestamp is received, ignore the
> > + * timestamp and process the packet normally.
> > + * See section 3.2 of RFC 7323.
> > + */
> > if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) {
> > if ((s = tcp_log_addrs(inc, th, NULL, NULL))) {
> > log(LOG_DEBUG, "%s; %s: Timestamp not expected, "
> > - "no action\n", s, __func__);
> > + "segment processed normally\n", s, __func__);
> > free(s, M_TCPLOG);
> > }
> > }
> >
> > Modified: stable/12/sys/netinet/tcp_stacks/rack.c
> > ==============================================================================
> > --- stable/12/sys/netinet/tcp_stacks/rack.c Mon Nov 30 09:22:33 2020 (r368180)
> > +++ stable/12/sys/netinet/tcp_stacks/rack.c Mon Nov 30 09:45:44 2020 (r368181)
> > @@ -6708,7 +6708,27 @@ rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th
> > TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0,
> > tlen, &log, true);
> > }
> > +
> > /*
> > + * Parse options on any incoming segment.
> > + */
> > + tcp_dooptions(&to, (u_char *)(th + 1),
> > + (th->th_off << 2) - sizeof(struct tcphdr),
> > + (thflags & TH_SYN) ? TO_SYN : 0);
> > +
> > + /*
> > + * If timestamps were negotiated during SYN/ACK and a
> > + * segment without a timestamp is received, silently drop
> > + * the segment.
> > + * See section 3.2 of RFC 7323.
> > + */
> > + if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) {
> > + way_out = 5;
> > + retval = 0;
> > + goto done_with_input;
> > + }
> > +
> > + /*
> > * Segment received on connection. Reset idle time and keep-alive
> > * timer. XXX: This should be done after segment validation to
> > * ignore broken/spoofed segs.
> > @@ -6761,12 +6781,6 @@ rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th
> > rack_cong_signal(tp, th, CC_ECN);
> > }
> > }
> > - /*
> > - * Parse options on any incoming segment.
> > - */
> > - tcp_dooptions(&to, (u_char *)(th + 1),
> > - (th->th_off << 2) - sizeof(struct tcphdr),
> > - (thflags & TH_SYN) ? TO_SYN : 0);
> >
> > /*
> > * If echoed timestamp is later than the current time, fall back to
> > @@ -6898,6 +6912,7 @@ rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th
> > rack_timer_audit(tp, rack, &so->so_snd);
> > way_out = 2;
> > }
> > + done_with_input:
> > rack_log_doseg_done(rack, cts, nxt_pkt, did_out, way_out);
> > if (did_out)
> > rack->r_wanted_output = 0;
> >
> > Modified: stable/12/sys/netinet/tcp_syncache.c
> > ==============================================================================
> > --- stable/12/sys/netinet/tcp_syncache.c Mon Nov 30 09:22:33 2020 (r368180)
> > +++ stable/12/sys/netinet/tcp_syncache.c Mon Nov 30 09:45:44 2020 (r368181)
> > @@ -1142,6 +1142,40 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt
> > }
> >
> > /*
> > + * If timestamps were not negotiated during SYN/ACK and a
> > + * segment with a timestamp is received, ignore the
> > + * timestamp and process the packet normally.
> > + * See section 3.2 of RFC 7323.
> > + */
> > + if (!(sc->sc_flags & SCF_TIMESTAMP) &&
> > + (to->to_flags & TOF_TS)) {
> > + if ((s = tcp_log_addrs(inc, th, NULL, NULL))) {
> > + log(LOG_DEBUG, "%s; %s: Timestamp not "
> > + "expected, segment processed normally\n",
> > + s, __func__);
> > + free(s, M_TCPLOG);
> > + s = NULL;
> > + }
> > + }
> > +
> > + /*
> > + * If timestamps were negotiated during SYN/ACK and a
> > + * segment without a timestamp is received, silently drop
> > + * the segment.
> > + * See section 3.2 of RFC 7323.
> > + */
> > + if ((sc->sc_flags & SCF_TIMESTAMP) &&
> > + !(to->to_flags & TOF_TS)) {
> > + SCH_UNLOCK(sch);
> > + if ((s = tcp_log_addrs(inc, th, NULL, NULL))) {
> > + log(LOG_DEBUG, "%s; %s: Timestamp missing, "
> > + "segment silently dropped\n", s, __func__);
> > + free(s, M_TCPLOG);
> > + }
> > + return (-1); /* Do not send RST */
> > + }
> > +
> > + /*
> > * Pull out the entry to unlock the bucket row.
> > *
> > * NOTE: We must decrease TCPS_SYN_RECEIVED count here, not
> > @@ -1184,32 +1218,6 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt
> > log(LOG_DEBUG, "%s; %s: SEQ %u != IRS+1 %u, segment "
> > "rejected\n", s, __func__, th->th_seq, sc->sc_irs);
> > goto failed;
> > - }
> > -
> > - /*
> > - * If timestamps were not negotiated during SYN/ACK they
> > - * must not appear on any segment during this session.
> > - */
> > - if (!(sc->sc_flags & SCF_TIMESTAMP) && (to->to_flags & TOF_TS)) {
> > - if ((s = tcp_log_addrs(inc, th, NULL, NULL)))
> > - log(LOG_DEBUG, "%s; %s: Timestamp not expected, "
> > - "segment rejected\n", s, __func__);
> > - goto failed;
> > - }
> > -
> > - /*
> > - * If timestamps were negotiated during SYN/ACK they should
> > - * appear on every segment during this session.
> > - * XXXAO: This is only informal as there have been unverified
> > - * reports of non-compliants stacks.
> > - */
> > - if ((sc->sc_flags & SCF_TIMESTAMP) && !(to->to_flags & TOF_TS)) {
> > - if ((s = tcp_log_addrs(inc, th, NULL, NULL))) {
> > - log(LOG_DEBUG, "%s; %s: Timestamp missing, "
> > - "no action\n", s, __func__);
> > - free(s, M_TCPLOG);
> > - s = NULL;
> > - }
> > }
> >
> > *lsop = syncache_socket(sc, *lsop, m);
> >
> > Modified: stable/12/sys/netinet/tcp_timewait.c
> > ==============================================================================
> > --- stable/12/sys/netinet/tcp_timewait.c Mon Nov 30 09:22:33 2020 (r368180)
> > +++ stable/12/sys/netinet/tcp_timewait.c Mon Nov 30 09:45:44 2020 (r368181)
> > @@ -373,9 +373,10 @@ tcp_twstart(struct tcpcb *tp)
> > /*
> > * 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.
> > + * It be called with to == NULL only for pure SYN-segments.
> > */
> > int
> > -tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unused, struct tcphdr *th,
> > +tcp_twcheck(struct inpcb *inp, struct tcpopt *to, struct tcphdr *th,
> > struct mbuf *m, int tlen)
> > {
> > struct tcptw *tw;
> > @@ -396,6 +397,8 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unu
> > goto drop;
> >
> > thflags = th->th_flags;
> > + KASSERT(to != NULL || (thflags & (TH_SYN | TH_ACK)) == TH_SYN,
> > + ("tcp_twcheck: called without options on a non-SYN segment"));
> >
> > /*
> > * NOTE: for FIN_WAIT_2 (to be added later),
> > @@ -443,6 +446,16 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unu
> > */
> > if ((thflags & TH_ACK) == 0)
> > goto drop;
> > +
> > + /*
> > + * If timestamps were negotiated during SYN/ACK and a
> > + * segment without a timestamp is received, silently drop
> > + * the segment.
> > + * See section 3.2 of RFC 7323.
> > + */
> > + if (((to->to_flags & TOF_TS) == 0) && (tw->t_recent != 0)) {
> > + goto drop;
> > + }
> >
> > /*
> > * Reset the 2MSL timer if this is a duplicate FIN.
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