From d82bae12dc38d79a2b77473f5eb0612a3d69c55b Mon Sep 17 00:00:00 2001 From: Soheil Hassas Yeganeh Date: Wed, 15 Mar 2017 16:30:45 -0400 Subject: tcp: remove per-destination timestamp cache Commit 8a5bd45f6616 (tcp: randomize tcp timestamp offsets for each connection) randomizes TCP timestamps per connection. After this commit, there is no guarantee that the timestamps received from the same destination are monotonically increasing. As a result, the per-destination timestamp cache in TCP metrics (i.e., tcpm_ts in struct tcp_metrics_block) is broken and cannot be relied upon. Remove the per-destination timestamp cache and all related code paths. Note that this cache was already broken for caching timestamps of multiple machines behind a NAT sharing the same address. Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Eric Dumazet Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Cc: Lutz Vieweg Cc: Florian Westphal Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'net/ipv4/tcp_input.c') diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 96b67a8b18c3..aafec0676d3e 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6342,8 +6342,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, dst = af_ops->route_req(sk, &fl, req, &strict); if (dst && strict && - !tcp_peer_is_proven(req, dst, true, - tmp_opt.saw_tstamp)) { + !tcp_peer_is_proven(req, dst)) { NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED); goto drop_and_release; } @@ -6352,8 +6351,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, else if (!net->ipv4.sysctl_tcp_syncookies && (net->ipv4.sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) < (net->ipv4.sysctl_max_syn_backlog >> 2)) && - !tcp_peer_is_proven(req, dst, false, - tmp_opt.saw_tstamp)) { + !tcp_peer_is_proven(req, dst)) { /* Without syncookies last quarter of * backlog is filled with destinations, * proven to be alive. -- cgit v1.2.3