svn commit: r340782 - head/sys/netinet/tcp_stacks
Michael Tuexen
tuexen at FreeBSD.org
Thu Nov 22 20:05:58 UTC 2018
Author: tuexen
Date: Thu Nov 22 20:05:57 2018
New Revision: 340782
URL: https://svnweb.freebsd.org/changeset/base/340782
Log:
A TCP stack is required to check SEG.ACK first, when processing a
segment in the SYN-SENT state as stated in Section 3.9 of RFC 793,
page 66. Ensure this is also done by the TCP RACK stack.
Reviewed by: rrs@
MFC after: 1 week
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D18034
Modified:
head/sys/netinet/tcp_stacks/rack.c
Modified: head/sys/netinet/tcp_stacks/rack.c
==============================================================================
--- head/sys/netinet/tcp_stacks/rack.c Thu Nov 22 20:02:39 2018 (r340781)
+++ head/sys/netinet/tcp_stacks/rack.c Thu Nov 22 20:05:57 2018 (r340782)
@@ -6533,6 +6533,15 @@ rack_hpts_do_segment(struct mbuf *m, struct tcphdr *th
goto done_with_input;
}
/*
+ * If a segment with the ACK-bit set arrives in the SYN-SENT state
+ * check SEQ.ACK first as described on page 66 of RFC 793, section 3.9.
+ */
+ if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) &&
+ (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) {
+ rack_do_dropwithreset(m, tp, th, BANDLIM_RST_OPENPORT, tlen);
+ return;
+ }
+ /*
* Segment received on connection. Reset idle time and keep-alive
* timer. XXX: This should be done after segment validation to
* ignore broken/spoofed segs.
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