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nixos/sslh: add transparent proxying support (#41412)
[x] Support transparent proxying. This means services behind sslh (Apache, sshd and so on) will see the external IP and ports as if the external world connected directly to them. [x] Run sslh daemon as unprivileged user instead of root (it is not only for security, transparent proxying requires it) [x] Removed pidFile support (it is not compatible with running sslh daemon as unprivileged user) [x] listenAddress default changed from "config.networking.hostName" (which resolves to meaningless "127.0.0.1" as with current /etc/hosts production) to "0.0.0.0" (all addresses)
This commit is contained in:
volth
xeji
parent
3c0498518f
commit
2874e56c05
@ -4,15 +4,14 @@ with lib;
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let
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cfg = config.services.sslh;
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user = "sslh";
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configFile = pkgs.writeText "sslh.conf" ''
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verbose: ${boolToString cfg.verbose};
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foreground: true;
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inetd: false;
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numeric: false;
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transparent: false;
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transparent: ${boolToString cfg.transparent};
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timeout: "${toString cfg.timeout}";
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user: "nobody";
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pidfile: "${cfg.pidfile}";
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listen:
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(
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@ -50,16 +49,16 @@ in
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description = "Timeout in seconds.";
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};
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pidfile = mkOption {
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type = types.path;
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default = "/run/sslh.pid";
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description = "PID file path for sslh daemon.";
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transparent = mkOption {
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type = types.bool;
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default = false;
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description = "Will the services behind sslh (Apache, sshd and so on) see the external IP and ports as if the external world connected directly to them";
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};
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listenAddress = mkOption {
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type = types.str;
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default = config.networking.hostName;
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description = "Listening hostname.";
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default = "0.0.0.0";
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description = "Listening address or hostname.";
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};
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port = mkOption {
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@ -76,14 +75,91 @@ in
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};
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};
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config = mkIf cfg.enable {
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systemd.services.sslh = {
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description = "Applicative Protocol Multiplexer (e.g. share SSH and HTTPS on the same port)";
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after = [ "network.target" ];
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wantedBy = [ "multi-user.target" ];
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serviceConfig.ExecStart = "${pkgs.sslh}/bin/sslh -F${configFile}";
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serviceConfig.KillMode = "process";
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serviceConfig.PIDFile = "${cfg.pidfile}";
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};
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};
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config = mkMerge [
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(mkIf cfg.enable {
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users.users.${user} = {
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description = "sslh daemon user";
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isSystemUser = true;
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};
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systemd.services.sslh = {
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description = "Applicative Protocol Multiplexer (e.g. share SSH and HTTPS on the same port)";
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after = [ "network.target" ];
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wantedBy = [ "multi-user.target" ];
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serviceConfig = {
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User = user;
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Group = "nogroup";
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PermissionsStartOnly = true;
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Restart = "always";
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RestartSec = "1s";
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ExecStart = "${pkgs.sslh}/bin/sslh -F${configFile}";
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KillMode = "process";
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AmbientCapabilities = "CAP_NET_BIND_SERVICE CAP_NET_ADMIN CAP_SETGID CAP_SETUID";
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PrivateTmp = true;
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PrivateDevices = true;
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ProtectSystem = "full";
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ProtectHome = true;
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};
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};
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})
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# code from https://github.com/yrutschle/sslh#transparent-proxy-support
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# the only difference is using iptables mark 0x2 instead of 0x1 to avoid conflicts with nixos/nat module
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(mkIf (cfg.enable && cfg.transparent) {
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# Set route_localnet = 1 on all interfaces so that ssl can use "localhost" as destination
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boot.kernel.sysctl."net.ipv4.conf.default.route_localnet" = 1;
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boot.kernel.sysctl."net.ipv4.conf.all.route_localnet" = 1;
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systemd.services.sslh = let
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iptablesCommands = [
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# DROP martian packets as they would have been if route_localnet was zero
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# Note: packets not leaving the server aren't affected by this, thus sslh will still work
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{ table = "raw"; command = "PREROUTING ! -i lo -d 127.0.0.0/8 -j DROP"; }
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{ table = "mangle"; command = "POSTROUTING ! -o lo -s 127.0.0.0/8 -j DROP"; }
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# Mark all connections made by ssl for special treatment (here sslh is run as user ${user})
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{ table = "nat"; command = "OUTPUT -m owner --uid-owner ${user} -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x02/0x0f"; }
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# Outgoing packets that should go to sslh instead have to be rerouted, so mark them accordingly (copying over the connection mark)
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{ table = "mangle"; command = "OUTPUT ! -o lo -p tcp -m connmark --mark 0x02/0x0f -j CONNMARK --restore-mark --mask 0x0f"; }
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];
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ip6tablesCommands = [
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{ table = "raw"; command = "PREROUTING ! -i lo -d ::1/128 -j DROP"; }
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{ table = "mangle"; command = "POSTROUTING ! -o lo -s ::1/128 -j DROP"; }
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{ table = "nat"; command = "OUTPUT -m owner --uid-owner ${user} -p tcp --tcp-flags FIN,SYN,RST,ACK SYN -j CONNMARK --set-xmark 0x02/0x0f"; }
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{ table = "mangle"; command = "OUTPUT ! -o lo -p tcp -m connmark --mark 0x02/0x0f -j CONNMARK --restore-mark --mask 0x0f"; }
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];
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in {
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path = [ pkgs.iptables pkgs.iproute pkgs.procps ];
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preStart = ''
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# Cleanup old iptables entries which might be still there
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${concatMapStringsSep "\n" ({table, command}: "while iptables -w -t ${table} -D ${command} 2>/dev/null; do echo; done") iptablesCommands}
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${concatMapStringsSep "\n" ({table, command}: "iptables -w -t ${table} -A ${command}" ) iptablesCommands}
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# Configure routing for those marked packets
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ip rule add fwmark 0x2 lookup 100
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ip route add local 0.0.0.0/0 dev lo table 100
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'' + optionalString config.networking.enableIPv6 ''
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${concatMapStringsSep "\n" ({table, command}: "while ip6tables -w -t ${table} -D ${command} 2>/dev/null; do echo; done") ip6tablesCommands}
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${concatMapStringsSep "\n" ({table, command}: "ip6tables -w -t ${table} -A ${command}" ) ip6tablesCommands}
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ip -6 rule add fwmark 0x2 lookup 100
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ip -6 route add local ::/0 dev lo table 100
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'';
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postStop = ''
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${concatMapStringsSep "\n" ({table, command}: "iptables -w -t ${table} -D ${command}") iptablesCommands}
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ip rule del fwmark 0x2 lookup 100
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ip route del local 0.0.0.0/0 dev lo table 100
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'' + optionalString config.networking.enableIPv6 ''
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${concatMapStringsSep "\n" ({table, command}: "ip6tables -w -t ${table} -D ${command}") ip6tablesCommands}
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ip -6 rule del fwmark 0x2 lookup 100
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ip -6 route del local ::/0 dev lo table 100
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'';
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};
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})
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];
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}
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