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authorRandall Stewart <rrs@FreeBSD.org>2021-09-23 15:43:29 +0000
committerRandall Stewart <rrs@FreeBSD.org>2021-09-23 15:43:29 +0000
commit1ca931a540cbb1891f535832ee6ef40ae3ed3910 (patch)
tree8f8aaa2bb4d2f902cab433766d84f51dd3bb794d /sys/netinet
parentfd69939e79a65d0dea766ac05e4d8b7335819ae1 (diff)
downloadsrc-1ca931a540cbb1891f535832ee6ef40ae3ed3910.tar.gz
src-1ca931a540cbb1891f535832ee6ef40ae3ed3910.zip
tcp: Rack compressed ack path updates the recv window too easily
The compressed ack path of rack is not following proper procedures in updating the peers window. It should be checking the seq and ack values before updating and instead it is blindly updating the values. This could in theory get the wrong window in the connection for some length of time. Reviewed by: tuexen Sponsored by: Netflix Inc. Differential Revision: https://reviews.freebsd.org/D32082
Diffstat (limited to 'sys/netinet')
-rw-r--r--sys/netinet/tcp_stacks/rack.c35
1 files changed, 25 insertions, 10 deletions
diff --git a/sys/netinet/tcp_stacks/rack.c b/sys/netinet/tcp_stacks/rack.c
index 23b1ff1fc584..2369a1c368bf 100644
--- a/sys/netinet/tcp_stacks/rack.c
+++ b/sys/netinet/tcp_stacks/rack.c
@@ -13116,10 +13116,28 @@ rack_timer_audit(struct tcpcb *tp, struct tcp_rack *rack, struct sockbuf *sb)
static void
rack_do_win_updates(struct tcpcb *tp, struct tcp_rack *rack, uint32_t tiwin, uint32_t seq, uint32_t ack, uint32_t cts, uint32_t high_seq)
{
- tp->snd_wnd = tiwin;
- rack_validate_fo_sendwin_up(tp, rack);
- tp->snd_wl1 = seq;
- tp->snd_wl2 = ack;
+ if ((SEQ_LT(tp->snd_wl1, seq) ||
+ (tp->snd_wl1 == seq && (SEQ_LT(tp->snd_wl2, ack) ||
+ (tp->snd_wl2 == ack && tiwin > tp->snd_wnd))))) {
+ /* keep track of pure window updates */
+ if ((tp->snd_wl2 == ack) && (tiwin > tp->snd_wnd))
+ KMOD_TCPSTAT_INC(tcps_rcvwinupd);
+ tp->snd_wnd = tiwin;
+ rack_validate_fo_sendwin_up(tp, rack);
+ tp->snd_wl1 = seq;
+ tp->snd_wl2 = ack;
+ if (tp->snd_wnd > tp->max_sndwnd)
+ tp->max_sndwnd = tp->snd_wnd;
+ rack->r_wanted_output = 1;
+ } else if ((tp->snd_wl2 == ack) && (tiwin < tp->snd_wnd)) {
+ tp->snd_wnd = tiwin;
+ rack_validate_fo_sendwin_up(tp, rack);
+ tp->snd_wl1 = seq;
+ tp->snd_wl2 = ack;
+ } else {
+ /* Not a valid win update */
+ return;
+ }
if (tp->snd_wnd > tp->max_sndwnd)
tp->max_sndwnd = tp->snd_wnd;
if (tp->snd_wnd < (tp->snd_max - high_seq)) {
@@ -13324,8 +13342,8 @@ rack_do_compressed_ack_processing(struct tcpcb *tp, struct socket *so, struct mb
struct tcp_ackent *ae;
uint32_t tiwin, ms_cts, cts, acked, acked_amount, high_seq, win_seq, the_win, win_upd_ack;
int cnt, i, did_out, ourfinisacked = 0;
- int win_up_req = 0;
struct tcpopt to_holder, *to = NULL;
+ int win_up_req = 0;
int nsegs = 0;
int under_pacing = 1;
int recovery = 0;
@@ -13519,11 +13537,11 @@ rack_do_compressed_ack_processing(struct tcpcb *tp, struct socket *so, struct mb
rack_strike_dupack(rack);
} else if (ae->ack_val_set == ACK_RWND) {
/* Case C */
-
win_up_req = 1;
win_upd_ack = ae->ack;
win_seq = ae->seq;
the_win = tiwin;
+ rack_do_win_updates(tp, rack, the_win, win_seq, win_upd_ack, cts, high_seq);
} else {
/* Case A */
if (SEQ_GT(ae->ack, tp->snd_max)) {
@@ -13540,10 +13558,10 @@ rack_do_compressed_ack_processing(struct tcpcb *tp, struct socket *so, struct mb
nsegs++;
/* If the window changed setup to update */
if (tiwin != tp->snd_wnd) {
- win_up_req = 1;
win_upd_ack = ae->ack;
win_seq = ae->seq;
the_win = tiwin;
+ rack_do_win_updates(tp, rack, the_win, win_seq, win_upd_ack, cts, high_seq);
}
#ifdef TCP_ACCOUNTING
/* Account for the acks */
@@ -13592,9 +13610,6 @@ rack_do_compressed_ack_processing(struct tcpcb *tp, struct socket *so, struct mb
ts_val = get_cyclecount();
#endif
acked_amount = acked = (high_seq - tp->snd_una);
- if (win_up_req) {
- rack_do_win_updates(tp, rack, the_win, win_seq, win_upd_ack, cts, high_seq);
- }
if (acked) {
if (rack->sack_attack_disable == 0)
rack_do_decay(rack);