tree d523665ca47dd355ee24762ad09ed85ce26c4652
parent 46249541ef18a58fe41279e5b45c06c130b6db7b
author Florian Westphal <fw@strlen.de> 1624531002 +0200
committer COS Cherry Picker <cloud-image-release@prod.google.com> 1674675515 -0800

netfilter: conntrack: do not renew entry stuck in tcp SYN_SENT state

[ Upstream commit e15d4cdf27cb0c1e977270270b2cea12e0955edd ]

Consider:
  client -----> conntrack ---> Host

client sends a SYN, but $Host is unreachable/silent.
Client eventually gives up and the conntrack entry will time out.

However, if the client is restarted with same addr/port pair, it
may prevent the conntrack entry from timing out.

This is noticeable when the existing conntrack entry has no NAT
transformation or an outdated one and port reuse happens either
on client or due to a NAT middlebox.

This change prevents refresh of the timeout for SYN retransmits,
so entry is going away after nf_conntrack_tcp_timeout_syn_sent
seconds (default: 60).

Entry will be re-created on next connection attempt, but then
nat rules will be evaluated again.

BUG=b/253760716
TEST=presubmit
RELEASE_NOTE=None

cos-patch: bug
Change-Id: Id74f74a39f4fc5bfb23b16bd4e78108de4bf5d8a
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/41468
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Meena Shanmugam <meenashanmugam@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>