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Preserve conntrack table during firewall rules reload (SIGHUP) (#233)

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Currently, we drop the conntrack table when firewall rules change during a SIGHUP reload. This means responses to inflight HTTP requests can be dropped, among other issues. This change copies the conntrack table over to the new firewall (it holds the conntrack mutex lock during this process, to be safe).

This change also records which firewall rules hash each conntrack entry used, so that we can re-verify the rules after the new firewall has been loaded.
This commit is contained in:
Wade Simmons 2020-07-31 18:53:36 -04:00 • committed by GitHub
parent 9b06748506
commit f3a6d8d990
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3 changed files with 189 additions and 42 deletions
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17
interface.go
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@ -219,11 +219,28 @@ func (f *Interface) reloadFirewall(c *Config) {
}
oldFw := f.firewall
conntrack := oldFw.Conntrack
conntrack.Lock()
defer conntrack.Unlock()
fw.rulesVersion = oldFw.rulesVersion + 1
// If rulesVersion is back to zero, we have wrapped all the way around. Be
// safe and just reset conntrack in this case.
if fw.rulesVersion == 0 {
l.WithField("firewallHash", fw.GetRuleHash()).
WithField("oldFirewallHash", oldFw.GetRuleHash()).
WithField("rulesVersion", fw.rulesVersion).
Warn("firewall rulesVersion has overflowed, resetting conntrack")
} else {
fw.Conntrack = conntrack
}
f.firewall = fw
oldFw.Destroy()
l.WithField("firewallHash", fw.GetRuleHash()).
WithField("oldFirewallHash", oldFw.GetRuleHash()).
WithField("rulesVersion", fw.rulesVersion).
Info("New firewall has been installed")
}