diff options
| author |   Stefan Baranoff <sbaranoff@gmail.com> | 2018-07-10 17:25:20 -0400 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2018-07-12 14:33:45 -0700 |
| commit | 21684dc46c598e477707487c009f9773f7c0382d (patch) | |
| tree | e32dc7d79947a09fc058069de742ea476db4cc83 /net | |
| parent | sch_fq_codel: zero q->flows_cnt when fq_codel_init fails (diff) | |
| download | linux-dev-21684dc46c598e477707487c009f9773f7c0382d.tar.xz linux-dev-21684dc46c598e477707487c009f9773f7c0382d.zip | |
tcp: fix sequence numbers for repaired sockets re-using TIME-WAIT sockets
This patch fixes a bug where the sequence numbers of a socket created using
TCP repair functionality are lower than set after connect is called.
This occurs when the repair socket overlaps with a TIME-WAIT socket and
triggers the re-use code. The amount lower is equal to the number of times
that a particular IP/port set is re-used and then put back into TIME-WAIT.
Re-using the first time the sequence number is 1 lower, closing that socket
and then re-opening (with repair) a new socket with the same addresses/ports
puts the sequence number 2 lower than set via setsockopt. The third time is
3 lower, etc. I have not tested what the limit of this acrewal is, if any.
The fix is, if a socket is in repair mode, to respect the already set
sequence number and timestamp when it would have already re-used the
TIME-WAIT socket.
Signed-off-by: Stefan Baranoff <sbaranoff@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index bea17f1e8302..3b2711e33e4c 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -156,11 +156,24 @@ int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp) */ if (tcptw->tw_ts_recent_stamp && (!twp || (reuse && get_seconds() - tcptw->tw_ts_recent_stamp > 1))) { - tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2; - if (tp->write_seq == 0) - tp->write_seq = 1; - tp->rx_opt.ts_recent = tcptw->tw_ts_recent; - tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; + /* In case of repair and re-using TIME-WAIT sockets we still + * want to be sure that it is safe as above but honor the + * sequence numbers and time stamps set as part of the repair + * process. + * + * Without this check re-using a TIME-WAIT socket with TCP + * repair would accumulate a -1 on the repair assigned + * sequence number. The first time it is reused the sequence + * is -1, the second time -2, etc. This fixes that issue + * without appearing to create any others. + */ + if (likely(!tp->repair)) { + tp->write_seq = tcptw->tw_snd_nxt + 65535 + 2; + if (tp->write_seq == 0) + tp->write_seq = 1; + tp->rx_opt.ts_recent = tcptw->tw_ts_recent; + tp->rx_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; + } sock_hold(sktw); return 1; } |