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authorAlexey Kodanev <alexey.kodanev@oracle.com>2017-02-22 13:23:55 +0300
committerDavid S. Miller <davem@davemloft.net>2017-02-22 16:35:32 -0500
commit00355fa5bb89840c48eb11eb6d84c6c3b128a839 (patch)
tree544ae213a42d76846ecbf01f87bd404dee819312 /net/ipv4
parentec7cb62d18d854ea09df8b7194e7e710985f8b9a (diff)
downloadlinux-00355fa5bb89840c48eb11eb6d84c6c3b128a839.tar.bz2
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.c16
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;