diff options
| author | Alexey Kodanev <alexey.kodanev@oracle.com> | 2017-02-22 13:23:55 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-02-23 00:35:32 +0300 |
| commit | 00355fa5bb89840c48eb11eb6d84c6c3b128a839 (patch) | |
| tree | 544ae213a42d76846ecbf01f87bd404dee819312 /net/ipv4 | |
| parent | ec7cb62d18d854ea09df8b7194e7e710985f8b9a (diff) | |
| download | linux-00355fa5bb89840c48eb11eb6d84c6c3b128a839.tar.xz | |
tcp: setup timestamp offset when write_seq already set
Found that when randomized tcp offsets are enabled (by default)
TCP client can still start new connections without them. Later,
if server does active close and re-uses sockets in TIME-WAIT
state, new SYN from client can be rejected on PAWS check inside
tcp_timewait_state_process(), because either tw_ts_recent or
rcv_tsval doesn't really have an offset set.
Here is how to reproduce it with LTP netstress tool:
netstress -R 1 &
netstress -H 127.0.0.1 -lr 1000000 -a1
[...]
< S seq 1956977072 win 43690 TS val 295618 ecr 459956970
> . ack 1956911535 win 342 TS val 459967184 ecr 1547117608
< R seq 1956911535 win 0 length 0
+1. < S seq 1956977072 win 43690 TS val 296640 ecr 459956970
> S. seq 657450664 ack 1956977073 win 43690 TS val 459968205 ecr 296640
Fixes: 95a22caee396 ("tcp: randomize tcp timestamp offsets for each connection")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 8c124d4ef4b7..9a89b8deafae 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -145,6 +145,7 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) struct flowi4 *fl4; struct rtable *rt; int err; + u32 seq; struct ip_options_rcu *inet_opt; struct inet_timewait_death_row *tcp_death_row = &sock_net(sk)->ipv4.tcp_death_row; @@ -234,12 +235,15 @@ int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len) sk_setup_caps(sk, &rt->dst); rt = NULL; - if (!tp->write_seq && likely(!tp->repair)) - tp->write_seq = secure_tcp_sequence_number(inet->inet_saddr, - inet->inet_daddr, - inet->inet_sport, - usin->sin_port, - &tp->tsoffset); + if (likely(!tp->repair)) { + seq = secure_tcp_sequence_number(inet->inet_saddr, + inet->inet_daddr, + inet->inet_sport, + usin->sin_port, + &tp->tsoffset); + if (!tp->write_seq) + tp->write_seq = seq; + } inet->inet_id = tp->write_seq ^ jiffies; |