From 2a413da57efc4c2009c984c63def8e9060771269 Mon Sep 17 00:00:00 2001
From: Izorkin <izorkin@elven.pw>
Date: Thu, 30 May 2019 14:11:56 +0300
Subject: [PATCH] nixos/nginx: do not run anything as root

---
 nixos/doc/manual/release-notes/rl-2003.xml    | 12 +++++++
 .../services/web-servers/nginx/default.nix    | 31 ++++++++++++-------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/nixos/doc/manual/release-notes/rl-2003.xml b/nixos/doc/manual/release-notes/rl-2003.xml
index 579b8d537444..55bd88ba8509 100644
--- a/nixos/doc/manual/release-notes/rl-2003.xml
+++ b/nixos/doc/manual/release-notes/rl-2003.xml
@@ -249,6 +249,18 @@
    <listitem>
      <para>SD images are now compressed by default using <literal>bzip2</literal>.</para>
    </listitem>
+   <listitem>
+    <para>
+     The nginx web server previously started its master process as root
+     privileged, then ran worker processes as a less privileged identity user.
+     This was changed to start all of nginx as a less privileged user (defined by
+     <literal>services.nginx.user</literal> and
+     <literal>services.nginx.group</literal>). As a consequence, all files that
+     are needed for nginx to run (included configuration fragments, SSL
+     certificates and keys, etc.) must now be readable by this less privileged
+     user/group.
+    </para>
+   </listitem>
    <listitem>
     <para>
      OpenSSH has been upgraded from 7.9 to 8.1, improving security and adding features
diff --git a/nixos/modules/services/web-servers/nginx/default.nix b/nixos/modules/services/web-servers/nginx/default.nix
index eb90dae94dfe..9b476ba7f1e5 100644
--- a/nixos/modules/services/web-servers/nginx/default.nix
+++ b/nixos/modules/services/web-servers/nginx/default.nix
@@ -47,7 +47,7 @@ let
   ''));
 
   configFile = pkgs.writers.writeNginxConfig "nginx.conf" ''
-    user ${cfg.user} ${cfg.group};
+    pid /run/nginx/nginx.pid;
     error_log ${cfg.logError};
     daemon off;
 
@@ -366,12 +366,7 @@ in
 
       preStart =  mkOption {
         type = types.lines;
-        default = ''
-          test -d ${cfg.stateDir}/logs || mkdir -m 750 -p ${cfg.stateDir}/logs
-          test `stat -c %a ${cfg.stateDir}` = "750" || chmod 750 ${cfg.stateDir}
-          test `stat -c %a ${cfg.stateDir}/logs` = "750" || chmod 750 ${cfg.stateDir}/logs
-          chown -R ${cfg.user}:${cfg.group} ${cfg.stateDir}
-        '';
+        default = "";
         description = "
           Shell commands executed before the service's nginx is started.
         ";
@@ -673,23 +668,35 @@ in
       }
     ];
 
+    systemd.tmpfiles.rules = [
+      "d '${cfg.stateDir}' 0750 ${cfg.user} ${cfg.group} - -"
+      "d '${cfg.stateDir}/logs' 0750 ${cfg.user} ${cfg.group} - -"
+    ];
+
     systemd.services.nginx = {
       description = "Nginx Web Server";
       wantedBy = [ "multi-user.target" ];
       wants = concatLists (map (vhostConfig: ["acme-${vhostConfig.serverName}.service" "acme-selfsigned-${vhostConfig.serverName}.service"]) acmeEnabledVhosts);
       after = [ "network.target" ] ++ map (vhostConfig: "acme-selfsigned-${vhostConfig.serverName}.service") acmeEnabledVhosts;
       stopIfChanged = false;
-      preStart =
-        ''
+      preStart = ''
         ${cfg.preStart}
-        ${cfg.package}/bin/nginx -c ${configPath} -p ${cfg.stateDir} -t
-        '';
+        ${cfg.package}/bin/nginx -c '${configPath}' -p '${cfg.stateDir}' -t
+      '';
       serviceConfig = {
-        ExecStart = "${cfg.package}/bin/nginx -c ${configPath} -p ${cfg.stateDir}";
+        ExecStart = "${cfg.package}/bin/nginx -c '${configPath}' -p '${cfg.stateDir}'";
         ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
         Restart = "always";
         RestartSec = "10s";
         StartLimitInterval = "1min";
+        # User and group
+        User = cfg.user;
+        Group = cfg.group;
+        # Runtime directory and mode
+        RuntimeDirectory = "nginx";
+        RuntimeDirectoryMode = "0750";
+        # Capabilities
+        AmbientCapabilities = [ "CAP_NET_BIND_SERVICE" "CAP_SYS_RESOURCE" ];
       };
     };