Author: tuexen
Date: Mon Nov 9 21:49:40 2020
New Revision: 367530
URL: https://svnweb.freebsd.org/changeset/base/367530
Log:
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.
PR: 250499
Reviewed by: gnn, rrs
MFC after: 1 week
Sponsored by: Netflix, Inc
Differential Revision: https://reviews.freebsd.org/D27148
Modified:
head/sys/netinet/tcp_input.c
head/sys/netinet/tcp_stacks/bbr.c
head/sys/netinet/tcp_stacks/rack.c
head/sys/netinet/tcp_syncache.c
head/sys/netinet/tcp_timewait.c
Modified: head/sys/netinet/tcp_input.c
==============================================================================
--- head/sys/netinet/tcp_input.c Mon Nov 9 21:19:17 2020
(r367529)
+++ head/sys/netinet/tcp_input.c Mon Nov 9 21:49:40 2020
(r367530)
@@ -977,8 +977,8 @@ findpcb:
* XXXRW: It may be time to rethink timewait locking.
*/
if (inp->inp_flags & INP_TIMEWAIT) {
- 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.
*/
@@ -1680,20 +1680,29 @@ 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 without 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: head/sys/netinet/tcp_stacks/bbr.c
==============================================================================
--- head/sys/netinet/tcp_stacks/bbr.c Mon Nov 9 21:19:17 2020
(r367529)
+++ head/sys/netinet/tcp_stacks/bbr.c Mon Nov 9 21:49:40 2020
(r367530)
@@ -11430,12 +11430,6 @@ bbr_do_segment_nounlock(struct mbuf *m, struct tcphdr
#ifdef STATS
stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin);
#endif
- /*
- * 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 (m->m_flags & M_TSTMP) {
/* Prefer the hardware timestamp if present */
@@ -11458,6 +11452,23 @@ bbr_do_segment_nounlock(struct mbuf *m, struct tcphdr
* Ok just get the current time.
*/
bbr->r_ctl.rc_rcvtime = lcts = cts = tcp_get_usecs(&bbr->rc_tv);
+ }
+ /*
+ * 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)) {
+ retval = 0;
+ goto done_with_input;
}
/*
* If echoed timestamp is later than the current time, fall back to
Modified: head/sys/netinet/tcp_stacks/rack.c
==============================================================================
--- head/sys/netinet/tcp_stacks/rack.c Mon Nov 9 21:19:17 2020
(r367529)
+++ head/sys/netinet/tcp_stacks/rack.c Mon Nov 9 21:49:40 2020
(r367530)
@@ -10525,7 +10525,7 @@ rack_handoff_ok(struct tcpcb *tp)
if ((tp->t_state == TCPS_SYN_SENT) ||
(tp->t_state == TCPS_SYN_RECEIVED)) {
/*
- * We really don't know if you support sack,
+ * We really don't know if you support sack,
* you have to get to ESTAB or beyond to tell.
*/
return (EAGAIN);
@@ -10868,7 +10868,27 @@ rack_do_segment_nounlock(struct mbuf *m, struct tcphdr
ctf_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
return(1);
}
+
/*
+ * 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.
@@ -10920,12 +10940,6 @@ rack_do_segment_nounlock(struct mbuf *m, struct tcphdr
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
Modified: head/sys/netinet/tcp_syncache.c
==============================================================================
--- head/sys/netinet/tcp_syncache.c Mon Nov 9 21:19:17 2020
(r367529)
+++ head/sys/netinet/tcp_syncache.c Mon Nov 9 21:49:40 2020
(r367530)
@@ -1212,6 +1212,40 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt
}
/*
+ * If timestamps were not negotiated during SYN/ACK and a
+ * segment without 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
@@ -1254,32 +1288,6 @@ 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: head/sys/netinet/tcp_timewait.c
==============================================================================
--- head/sys/netinet/tcp_timewait.c Mon Nov 9 21:19:17 2020
(r367529)
+++ head/sys/netinet/tcp_timewait.c Mon Nov 9 21:49:40 2020
(r367530)
@@ -376,7 +376,7 @@ tcp_twstart(struct tcpcb *tp)
* looking for a pcb in the listen state. Returns 0 otherwise.
*/
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;
@@ -410,6 +410,16 @@ tcp_twcheck(struct inpcb *inp, struct tcpopt *to __unu
*/
if (thflags & TH_RST)
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;
+ }
#if 0
/* PAWS not needed at the moment */
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