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tcp: fix simultaneous open and refine e80062a2d4

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- The soisconnected() call on transition from SYN_RCVD to ESTABLISHED
  is also necessary for a half-synchronized connection.  Fix that
  just setting the flag, when we transfer SYN-SENT -> SYN-RECEIVED.
- Provide a comment that explains at what conditions the call to
  soisconnected() is necessary.
- Hence mechanically rename the TF_INCQUEUE flag to TF_SONOTCONN.
- Extend the change to the BBR and RACK stacks.

Note: the interaction between the accept_filter(9) and the socket layer
is not fully consistent, yet.  For most accept filters this call to
soisconnected() will not move the connection from the incomplete queue
to the complete.  The move would happen only when the filter has received
the desired data, and soisconnected() would be called once again from
sorwakeup().  Ideally, we should mark socket as connected only there,
and leave the soisconnected() from SYN_RCVD->ESTABLISHED only for the
simultaneous open case.  However, this doesn't yet work.

Reviewed by:		rscheff, tuexen, rrs
Differential revision:	https://reviews.freebsd.org/D36641
This commit is contained in:
Gleb Smirnoff 2022-09-21 14:02:49 -07:00
parent d819ddba9a
commit 493105c2a8
6 changed files with 26 additions and 11 deletions
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15
sys/netinet/tcp_input.c
View File

@ -2105,7 +2105,7 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
* SYN-SENT -> SYN-RECEIVED
* SYN-SENT* -> SYN-RECEIVED*
*/
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN);
tcp_timer_activate(tp, TT_REXMT, 0);
tcp_state_change(tp, TCPS_SYN_RECEIVED);
}
@ -2433,8 +2433,17 @@ tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so,
case TCPS_SYN_RECEIVED:
TCPSTAT_INC(tcps_connects);
if (tp->t_flags & TF_INCQUEUE) {
tp->t_flags &= ~TF_INCQUEUE;
if (tp->t_flags & TF_SONOTCONN) {
/*
* Usually SYN_RECEIVED had been created from a LISTEN,
* and solisten_enqueue() has already marked the socket
* layer as connected. If it didn't, which can happen
* only with an accept_filter(9), then the tp is marked
* with TF_SONOTCONN. The other reason for this mark
* to be set is a simultaneous open, a SYN_RECEIVED
* that had been created from SYN_SENT.
*/
tp->t_flags &= ~TF_SONOTCONN;
soisconnected(so);
}
/* Do window scaling? */

7
sys/netinet/tcp_stacks/bbr.c
View File

@ -8902,7 +8902,7 @@ bbr_do_syn_sent(struct mbuf *m, struct tcphdr *th, struct socket *so,
* SYN-SENT -> SYN-RECEIVED SYN-SENT* -> SYN-RECEIVED* If
* there was no CC option, clear cached CC value.
*/
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN);
tcp_state_change(tp, TCPS_SYN_RECEIVED);
}
INP_WLOCK_ASSERT(tp->t_inpcb);
@ -9088,7 +9088,10 @@ bbr_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
tiwin, thflags, nxt_pkt));
}
KMOD_TCPSTAT_INC(tcps_connects);
soisconnected(so);
if (tp->t_flags & TF_SONOTCONN) {
tp->t_flags &= ~TF_SONOTCONN;
soisconnected(so);
}
/* Do window scaling? */
if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
(TF_RCVD_SCALE | TF_REQ_SCALE)) {

7
sys/netinet/tcp_stacks/rack.c
View File

@ -11318,7 +11318,7 @@ rack_do_syn_sent(struct mbuf *m, struct tcphdr *th, struct socket *so,
* SYN-SENT -> SYN-RECEIVED SYN-SENT* -> SYN-RECEIVED* If
* there was no CC option, clear cached CC value.
*/
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN);
tcp_state_change(tp, TCPS_SYN_RECEIVED);
}
INP_WLOCK_ASSERT(tp->t_inpcb);
@ -11507,7 +11507,10 @@ rack_do_syn_recv(struct mbuf *m, struct tcphdr *th, struct socket *so,
tiwin, thflags, nxt_pkt));
}
KMOD_TCPSTAT_INC(tcps_connects);
soisconnected(so);
if (tp->t_flags & TF_SONOTCONN) {
tp->t_flags &= ~TF_SONOTCONN;
soisconnected(so);
}
/* Do window scaling? */
if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
(TF_RCVD_SCALE | TF_REQ_SCALE)) {

2
sys/netinet/tcp_syncache.c
View File

@ -1040,7 +1040,7 @@ syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
TCP_PROBE6(state__change, NULL, tp, NULL, tp, NULL, TCPS_LISTEN);
if (!solisten_enqueue(so, SS_ISCONNECTED))
tp->t_flags |= TF_INCQUEUE;
tp->t_flags |= TF_SONOTCONN;
return (so);

4
sys/netinet/tcp_usrreq.c
View File

@ -2978,8 +2978,8 @@ db_print_tflags(u_int t_flags)
db_printf("%sTF_MORETOCOME", comma ? ", " : "");
comma = 1;
}
if (t_flags & TF_INCQUEUE) {
db_printf("%sTF_INCQUEUE", comma ? ", " : "");
if (t_flags & TF_SONOTCONN) {
db_printf("%sTF_SONOTCONN", comma ? ", " : "");
comma = 1;
}
if (t_flags & TF_LASTIDLE) {

2
sys/netinet/tcp_var.h
View File

@ -515,7 +515,7 @@ tcp_unlock_or_drop(struct tcpcb *tp, int tcp_output_retval)
#define TF_WAKESOR 0x00004000 /* wake up receive socket */
#define TF_GPUTINPROG 0x00008000 /* Goodput measurement in progress */
#define TF_MORETOCOME 0x00010000 /* More data to be appended to sock */
#define TF_INCQUEUE 0x00020000 /* on incomplete queue of listener */
#define TF_SONOTCONN 0x00020000 /* needs soisconnected() on ESTAB */
#define TF_LASTIDLE 0x00040000 /* connection was previously idle */
#define TF_RXWIN0SENT 0x00080000 /* sent a receiver win 0 in response */
#define TF_FASTRECOVERY 0x00100000 /* in NewReno Fast Recovery */