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89d51d5f29
Because this exploit has been widely known for years and has not been fixed by Mojang, we decided that it was worth allowing people to toggle it on/off due to how easy it is to make it configurable. It should be noted that this decision does not promise all future exploits will be configurable.
80 lines
4.1 KiB
Diff
80 lines
4.1 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: egg82 <eggys82@gmail.com>
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Date: Sat, 11 Sep 2021 22:55:14 +0200
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Subject: [PATCH] Add root/admin user detection
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This patch detects whether or not the server is currently executing as a privileged user and spits out a warning.
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The warning serves as a sort-of PSA for newer server admins who don't understand the risks of running as root.
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We've seen plenty of bad/malicious plugins hit markets, and there's been a few close-calls with exploits in the past.
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Hopefully this helps mitigate some potential damage to servers, even if it is just a warning.
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Co-authored-by: Noah van der Aa <ndvdaa@gmail.com>
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diff --git a/src/main/java/io/papermc/paper/util/ServerEnvironment.java b/src/main/java/io/papermc/paper/util/ServerEnvironment.java
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new file mode 100644
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index 0000000000000000000000000000000000000000..6bd0afddbcc461149dfe9a5c7a86fff6ea13a5f1
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--- /dev/null
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+++ b/src/main/java/io/papermc/paper/util/ServerEnvironment.java
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@@ -0,0 +1,40 @@
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+package io.papermc.paper.util;
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+
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+import com.sun.security.auth.module.NTSystem;
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+import com.sun.security.auth.module.UnixSystem;
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+import org.apache.commons.lang.SystemUtils;
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+
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+import java.io.IOException;
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+import java.io.InputStream;
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+import java.util.Set;
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+
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+public class ServerEnvironment {
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+ private static final boolean RUNNING_AS_ROOT_OR_ADMIN;
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+ private static final String WINDOWS_HIGH_INTEGRITY_LEVEL = "S-1-16-12288";
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+
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+ static {
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+ if (SystemUtils.IS_OS_WINDOWS) {
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+ RUNNING_AS_ROOT_OR_ADMIN = Set.of(new NTSystem().getGroupIDs()).contains(WINDOWS_HIGH_INTEGRITY_LEVEL);
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+ } else {
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+ boolean isRunningAsRoot = false;
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+ if (new UnixSystem().getUid() == 0) {
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+ // Due to an OpenJDK bug (https://bugs.openjdk.java.net/browse/JDK-8274721), UnixSystem#getUid incorrectly
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+ // returns 0 when the user doesn't have a username. Because of this, we'll have to double-check if the user ID is
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+ // actually 0 by running the id -u command.
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+ try {
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+ Process process = new ProcessBuilder("id", "-u").start();
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+ process.waitFor();
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+ InputStream inputStream = process.getInputStream();
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+ isRunningAsRoot = new String(inputStream.readAllBytes()).trim().equals("0");
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+ } catch (InterruptedException | IOException ignored) {
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+ isRunningAsRoot = false;
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+ }
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+ }
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+ RUNNING_AS_ROOT_OR_ADMIN = isRunningAsRoot;
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+ }
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+ }
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+
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+ public static boolean userIsRootOrAdmin() {
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+ return RUNNING_AS_ROOT_OR_ADMIN;
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+ }
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+}
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diff --git a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
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index 6b4c9ef02931491dd048646ead494892f06504c5..608d860b940dee870a3df3d52efaed5e9eab17cf 100644
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--- a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
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+++ b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
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@@ -179,6 +179,16 @@ public class DedicatedServer extends MinecraftServer implements ServerInterface
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DedicatedServer.LOGGER.warn("To start the server with more ram, launch it as \"java -Xmx1024M -Xms1024M -jar minecraft_server.jar\"");
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}
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+ // Paper start - detect running as root
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+ if (io.papermc.paper.util.ServerEnvironment.userIsRootOrAdmin()) {
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+ DedicatedServer.LOGGER.warn("****************************");
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+ DedicatedServer.LOGGER.warn("YOU ARE RUNNING THIS SERVER AS AN ADMINISTRATIVE OR ROOT USER. THIS IS NOT ADVISED.");
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+ DedicatedServer.LOGGER.warn("YOU ARE OPENING YOURSELF UP TO POTENTIAL RISKS WHEN DOING THIS.");
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+ DedicatedServer.LOGGER.warn("FOR MORE INFORMATION, SEE https://madelinemiller.dev/blog/root-minecraft-server/");
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+ DedicatedServer.LOGGER.warn("****************************");
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+ }
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+ // Paper end - detect running as root
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+
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DedicatedServer.LOGGER.info("Loading properties");
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DedicatedServerProperties dedicatedserverproperties = this.settings.getProperties();
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