Author: tuexen Date: Fri Jun 15 12:28:43 2018 New Revision: 335194 URL: https://svnweb.freebsd.org/changeset/base/335194
Log: When retransmitting TCP SYN-ACK segments with the TCP timestamp option enabled use an updated timestamp instead of reusing the one used in the initial TCP SYN-ACK segment. This patch ensures that an updated timestamp is used when sending the SYN-ACK from the syncache code. It was already done if the SYN-ACK was retransmitted from the generic code. This makes the behaviour consistent and also conformant with the TCP specification. Reviewed by: jtl@, Jason Eggleston MFC after: 1 month Sponsored by: Neflix, Inc. Differential Revision: https://reviews.freebsd.org/D15634 Modified: head/sys/netinet/tcp_syncache.c head/sys/netinet/tcp_syncache.h Modified: head/sys/netinet/tcp_syncache.c ============================================================================== --- head/sys/netinet/tcp_syncache.c Fri Jun 15 11:54:55 2018 (r335193) +++ head/sys/netinet/tcp_syncache.c Fri Jun 15 12:28:43 2018 (r335194) @@ -1168,25 +1168,6 @@ syncache_expand(struct in_conninfo *inc, struct tcpopt } } - /* - * If timestamps were negotiated, the reflected timestamp - * must be equal to what we actually sent in the SYN|ACK - * except in the case of 0. Some boxes are known for sending - * broken timestamp replies during the 3whs (and potentially - * during the connection also). - * - * Accept the final ACK of 3whs with reflected timestamp of 0 - * instead of sending a RST and deleting the syncache entry. - */ - if ((to->to_flags & TOF_TS) && to->to_tsecr && - to->to_tsecr != sc->sc_ts) { - if ((s = tcp_log_addrs(inc, th, NULL, NULL))) - log(LOG_DEBUG, "%s; %s: TSECR %u != TS %u, " - "segment rejected\n", - s, __func__, to->to_tsecr, sc->sc_ts); - goto failed; - } - *lsop = syncache_socket(sc, *lsop, m); if (*lsop == NULL) @@ -1513,7 +1494,6 @@ skip_alloc: */ if (to->to_flags & TOF_TS) { sc->sc_tsreflect = to->to_tsval; - sc->sc_ts = tcp_ts_getticks(); sc->sc_flags |= SCF_TIMESTAMP; } if (to->to_flags & TOF_SCALE) { @@ -1742,8 +1722,7 @@ syncache_respond(struct syncache *sc, struct syncache_ to.to_flags |= TOF_SCALE; } if (sc->sc_flags & SCF_TIMESTAMP) { - /* Virgin timestamp or TCP cookie enhanced one. */ - to.to_tsval = sc->sc_ts; + to.to_tsval = sc->sc_tsoff + tcp_ts_getticks(); to.to_tsecr = sc->sc_tsreflect; to.to_flags |= TOF_TS; } @@ -2050,8 +2029,7 @@ syncookie_generate(struct syncache_head *sch, struct s /* Randomize the timestamp. */ if (sc->sc_flags & SCF_TIMESTAMP) { - sc->sc_ts = arc4random(); - sc->sc_tsoff = sc->sc_ts - tcp_ts_getticks(); + sc->sc_tsoff = arc4random() - tcp_ts_getticks(); } TCPSTAT_INC(tcps_sc_sendcookie); @@ -2140,7 +2118,6 @@ syncookie_lookup(struct in_conninfo *inc, struct synca if (to->to_flags & TOF_TS) { sc->sc_flags |= SCF_TIMESTAMP; sc->sc_tsreflect = to->to_tsval; - sc->sc_ts = to->to_tsecr; sc->sc_tsoff = to->to_tsecr - tcp_ts_getticks(); } Modified: head/sys/netinet/tcp_syncache.h ============================================================================== --- head/sys/netinet/tcp_syncache.h Fri Jun 15 11:54:55 2018 (r335193) +++ head/sys/netinet/tcp_syncache.h Fri Jun 15 12:28:43 2018 (r335194) @@ -56,7 +56,6 @@ struct syncache { int sc_rxttime; /* retransmit time */ u_int16_t sc_rxmits; /* retransmit counter */ u_int32_t sc_tsreflect; /* timestamp to reflect */ - u_int32_t sc_ts; /* our timestamp to send */ u_int32_t sc_tsoff; /* ts offset w/ syncookies */ u_int32_t sc_flowlabel; /* IPv6 flowlabel */ tcp_seq sc_irs; /* seq from peer */ _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
