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Fix PAWS (Protect Against Wrapped Sequence numbers) in cases when

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hz >> 1000 and thus getting outside the timestamp clock frequenceny of
1ms < x < 1s per tick as mandated by RFC1323, leading to connection
resets on idle connections.

Always use a granularity of 1ms using getmicrouptime() making all but
relevant callouts independent of hz.

Use getmicrouptime(), not getmicrotime() as the latter may make a jump
possibly breaking TCP nfsroot mounts having our timestamps move forward
for more than 24.8 days in a second without having been idle for that
long.

PR:		kern/61404
Reviewed by:	jhb, mav, rrs
Discussed with:	silby, lstewart
Sponsored by:	Sandvine Incorporated (originally in 2011)
MFC after:	6 weeks
This commit is contained in:
Bjoern A. Zeeb 2012-02-15 16:09:56 +00:00
parent b99a737923
commit d8951c8a2f
5 changed files with 54 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

32
sys/netinet/tcp_input.c
View File

@ -1493,7 +1493,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
*/
if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) {
to.to_tsecr -= tp->ts_offset;
if (TSTMP_GT(to.to_tsecr, ticks))
if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks()))
to.to_tsecr = 0;
}
@ -1518,7 +1518,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
if (to.to_flags & TOF_TS) {
tp->t_flags |= TF_RCVD_TSTMP;
tp->ts_recent = to.to_tsval;
tp->ts_recent_age = ticks;
tp->ts_recent_age = tcp_ts_getticks();
}
if (to.to_flags & TOF_MSS)
tcp_mss(tp, to.to_mss);
@ -1562,7 +1562,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
*/
if ((to.to_flags & TOF_TS) != 0 &&
SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
tp->ts_recent_age = ticks;
tp->ts_recent_age = tcp_ts_getticks();
tp->ts_recent = to.to_tsval;
}
@ -1600,11 +1600,13 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
*/
if ((to.to_flags & TOF_TS) != 0 &&
to.to_tsecr) {
if (!tp->t_rttlow ||
tp->t_rttlow > ticks - to.to_tsecr)
tp->t_rttlow = ticks - to.to_tsecr;
u_int t;
t = tcp_ts_getticks() - to.to_tsecr;
if (!tp->t_rttlow || tp->t_rttlow > t)
tp->t_rttlow = t;
tcp_xmit_timer(tp,
ticks - to.to_tsecr + 1);
TCP_TS_TO_TICKS(t) + 1);
} else if (tp->t_rtttime &&
SEQ_GT(th->th_ack, tp->t_rtseq)) {
if (!tp->t_rttlow ||
@ -2070,7 +2072,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
TSTMP_LT(to.to_tsval, tp->ts_recent)) {
/* Check to see if ts_recent is over 24 days old. */
if (ticks - tp->ts_recent_age > TCP_PAWS_IDLE) {
if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) {
/*
* Invalidate ts_recent. If this segment updates
* ts_recent, the age will be reset later and ts_recent
@ -2229,7 +2231,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen +
((thflags & (TH_SYN|TH_FIN)) != 0))) {
tp->ts_recent_age = ticks;
tp->ts_recent_age = tcp_ts_getticks();
tp->ts_recent = to.to_tsval;
}
@ -2543,11 +2545,13 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
* timestamps of 0 or we could calculate a
* huge RTT and blow up the retransmit timer.
*/
if ((to.to_flags & TOF_TS) != 0 &&
to.to_tsecr) {
if (!tp->t_rttlow || tp->t_rttlow > ticks - to.to_tsecr)
tp->t_rttlow = ticks - to.to_tsecr;
tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) {
u_int t;
t = tcp_ts_getticks() - to.to_tsecr;
if (!tp->t_rttlow || tp->t_rttlow > t)
tp->t_rttlow = t;
tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1);
} else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) {
if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime)
tp->t_rttlow = ticks - tp->t_rtttime;

4
sys/netinet/tcp_output.c
View File

@ -680,13 +680,13 @@ tcp_output(struct tcpcb *tp)
/* Timestamps. */
if ((tp->t_flags & TF_RCVD_TSTMP) ||
((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) {
to.to_tsval = ticks + tp->ts_offset;
to.to_tsval = tcp_ts_getticks() + tp->ts_offset;
to.to_tsecr = tp->ts_recent;
to.to_flags |= TOF_TS;
/* Set receive buffer autosizing timestamp. */
if (tp->rfbuf_ts == 0 &&
(so->so_rcv.sb_flags & SB_AUTOSIZE))
tp->rfbuf_ts = ticks;
tp->rfbuf_ts = tcp_ts_getticks();
}
/* Selective ACK's. */
if (tp->t_flags & TF_SACK_PERMIT) {

31
sys/netinet/tcp_seq.h
View File

@ -62,7 +62,34 @@
(tp)->snd_una = (tp)->snd_nxt = (tp)->snd_max = (tp)->snd_up = \
(tp)->snd_recover = (tp)->iss
#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * hz)
/* timestamp wrap-around time */
#ifdef _KERNEL
/*
* Clock macros for RFC 1323 timestamps.
*/
#define TCP_TS_TO_TICKS(_t) ((_t) * hz / 1000)
/* Timestamp wrap-around time, 24 days. */
#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * 1000)
/*
* tcp_ts_getticks() in ms, should be 1ms < x < 1000ms according to RFC 1323.
* We always use 1ms granularity independent of hz.
*/
static __inline u_int
tcp_ts_getticks(void)
{
struct timeval tv;
u_long ms;
/*
* getmicrouptime() should be good enough for any 1-1000ms granularity.
* Do not use getmicrotime() here as it might break nfsroot/tcp.
*/
getmicrouptime(&tv);
ms = tv.tv_sec * 1000 + tv.tv_usec / 1000;
return (ms);
}
#endif /* _KERNEL */
#endif /* _NETINET_TCP_SEQ_H_ */

8
sys/netinet/tcp_syncache.c
View File

@ -819,7 +819,7 @@ syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
if (sc->sc_flags & SCF_TIMESTAMP) {
tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP;
tp->ts_recent = sc->sc_tsreflect;
tp->ts_recent_age = ticks;
tp->ts_recent_age = tcp_ts_getticks();
tp->ts_offset = sc->sc_tsoff;
}
#ifdef TCP_SIGNATURE
@ -1226,7 +1226,7 @@ _syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
*/
if (to->to_flags & TOF_TS) {
sc->sc_tsreflect = to->to_tsval;
sc->sc_ts = ticks;
sc->sc_ts = tcp_ts_getticks();
sc->sc_flags |= SCF_TIMESTAMP;
}
if (to->to_flags & TOF_SCALE) {
@ -1667,7 +1667,7 @@ syncookie_generate(struct syncache_head *sch, struct syncache *sc,
data |= md5_buffer[2] << 10; /* more digest bits */
data ^= md5_buffer[3];
sc->sc_ts = data;
sc->sc_tsoff = data - ticks; /* after XOR */
sc->sc_tsoff = data - tcp_ts_getticks(); /* after XOR */
}
TCPSTAT_INC(tcps_sc_sendcookie);
@ -1752,7 +1752,7 @@ syncookie_lookup(struct in_conninfo *inc, struct syncache_head *sch,
sc->sc_flags |= SCF_TIMESTAMP;
sc->sc_tsreflect = to->to_tsval;
sc->sc_ts = to->to_tsecr;
sc->sc_tsoff = to->to_tsecr - ticks;
sc->sc_tsoff = to->to_tsecr - tcp_ts_getticks();
sc->sc_flags |= (data & 0x1) ? SCF_SIGNATURE : 0;
sc->sc_flags |= ((data >> 1) & 0x1) ? SCF_SACK : 0;
sc->sc_requested_s_scale = min((data >> 2) & 0xf,

2
sys/netinet/tcp_timewait.c
View File

@ -558,7 +558,7 @@ tcp_twrespond(struct tcptw *tw, int flags)
*/
if (tw->t_recent && flags == TH_ACK) {
to.to_flags |= TOF_TS;
to.to_tsval = ticks + tw->ts_offset;
to.to_tsval = tcp_ts_getticks() + tw->ts_offset;
to.to_tsecr = tw->t_recent;
}
optlen = tcp_addoptions(&to, (u_char *)(th + 1));