On Wed, Jan 13, 2021 at 9:31 AM Michael Tuexen <tue...@freebsd.org> wrote:
>
> > On 13. Jan 2021, at 16:16, Kyle Evans <kev...@freebsd.org> wrote:
> >
> > On Wed, Jan 6, 2021 at 9:01 AM Kyle Evans <kev...@freebsd.org> wrote:
> >>
> >> On Mon, Nov 30, 2020 at 3:45 AM Michael Tuexen <tue...@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@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@viper:~/grep#
> >>
> >
> > Ping?
> Hi Kyle,
>
> thanks for pinging. I missed your original mail (not sure why it did not end
> up in the
> correct mailbox). Will look into it later today/tomorrow.
>
> Thanks for providing a reproducer. Just to get it crystal clear: You say that
> the
> programs runs fine on CURRENT but not on stable/12. Is that correct?
>
Excellent, thanks! It runs fine on 12.2, but not on an up-to-date
-CURRENT or stable/12 after this MFC.
> Best regards
> Michael
> >
> >>>
> >>> 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.
>
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
