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firewall service: add support for loose reverse path filter check (#19122)

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Jaka Hudoklin 2016-10-08 14:26:52 +02:00 committed by Franz Pletz
parent 38074ec9df
commit afbe339e7d
1 changed files with 7 additions and 6 deletions
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13
nixos/modules/services/networking/firewall.nix
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@ -100,13 +100,13 @@ let
# Perform a reverse-path test to refuse spoofers
# For now, we just drop, as the raw table doesn't have a log-refuse yet
${optionalString (kernelHasRPFilter && cfg.checkReversePath) ''
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
# Clean up rpfilter rules
ip46tables -t raw -D PREROUTING -j nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t raw -F nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t raw -N nixos-fw-rpfilter 2> /dev/null || true
ip46tables -t raw -A nixos-fw-rpfilter -m rpfilter -j RETURN
ip46tables -t raw -A nixos-fw-rpfilter -m rpfilter ${optionalString (cfg.checkReversePath == "loose") "--loose"} -j RETURN
# Allows this host to act as a DHCPv4 server
iptables -t raw -A nixos-fw-rpfilter -s 0.0.0.0 -d 255.255.255.255 -p udp --sport 68 --dport 67 -j RETURN
@ -200,7 +200,7 @@ let
# Clean up after added ruleset
ip46tables -D INPUT -j nixos-fw 2>/dev/null || true
${optionalString (kernelHasRPFilter && cfg.checkReversePath) ''
${optionalString (kernelHasRPFilter && (cfg.checkReversePath != false)) ''
ip46tables -t raw -D PREROUTING -j nixos-fw-rpfilter 2>/dev/null || true
''}
@ -373,7 +373,7 @@ in
networking.firewall.checkReversePath = mkOption {
default = kernelHasRPFilter;
type = types.bool;
type = types.either types.bool (types.enum ["strict" "loose"]);
description =
''
Performs a reverse path filter test on a packet.
@ -381,7 +381,8 @@ in
that the packet arrived on, it is refused.
If using asymmetric routing or other complicated routing,
disable this setting and setup your own counter-measures.
set this option to loose mode or disable it and setup your
own counter-measures.
(needs kernel 3.3+)
'';
@ -482,7 +483,7 @@ in
options nf_conntrack nf_conntrack_helper=0
'';
assertions = [ { assertion = ! cfg.checkReversePath || kernelHasRPFilter;
assertions = [ { assertion = (cfg.checkReversePath != false) || kernelHasRPFilter;
message = "This kernel does not support rpfilter"; }
{ assertion = cfg.autoLoadConntrackHelpers || kernelCanDisableHelpers;
message = "This kernel does not support disabling conntrack helpers"; }