From 803d4171bf24e82612c526d65de77aa580c8a62f Mon Sep 17 00:00:00 2001
From: Florian Zschocke <f.zschocke+git@gmail.com>
Date: Sat, 4 Apr 2020 19:43:35 +0200
Subject: Delete password from memory in AuthenticationManager

Zero out the password to remove it from memory after use.
This is only a first step, implementing it for one method:
`AuthenticationManager.authenticate(String, char[], String)`.
---
 .../com/gitblit/manager/AuthenticationManager.java | 42 ++++++++++++----------
 src/main/java/com/gitblit/utils/StringUtils.java   | 15 ++++++++
 2 files changed, 38 insertions(+), 19 deletions(-)

(limited to 'src/main/java/com/gitblit')

diff --git a/src/main/java/com/gitblit/manager/AuthenticationManager.java b/src/main/java/com/gitblit/manager/AuthenticationManager.java
index 4f3f4f85..68c83dae 100644
--- a/src/main/java/com/gitblit/manager/AuthenticationManager.java
+++ b/src/main/java/com/gitblit/manager/AuthenticationManager.java
@@ -452,7 +452,6 @@ public class AuthenticationManager implements IAuthenticationManager {
 	/**
 	 * Authenticate a user based on a username and password.
 	 *
-	 * @see IUserService.authenticate(String, char[])
 	 * @param username
 	 * @param password
 	 * @return a user object or null
@@ -471,34 +470,39 @@ public class AuthenticationManager implements IAuthenticationManager {
 		}
 		
 		String usernameDecoded = StringUtils.decodeUsername(username);
-		String pw = new String(password);
-		if (StringUtils.isEmpty(pw)) {
+		if (StringUtils.isEmpty(password)) {
 			// can not authenticate empty password
 			return null;
 		}
 
 		UserModel user = userManager.getUserModel(usernameDecoded);
 
-		// try local authentication
-		if (user != null && user.isLocalAccount()) {
-			UserModel returnedUser = authenticateLocal(user, password);
-			if (returnedUser != null) {
-				// user authenticated
-				return returnedUser;
-			}
-		} else {
-			// try registered external authentication providers
-			for (AuthenticationProvider provider : authenticationProviders) {
-				if (provider instanceof UsernamePasswordAuthenticationProvider) {
-					UserModel returnedUser = provider.authenticate(usernameDecoded, password);
-					if (returnedUser != null) {
-						// user authenticated
-						returnedUser.accountType = provider.getAccountType();
-						return validateAuthentication(returnedUser, AuthenticationType.CREDENTIALS);
+		try {
+			// try local authentication
+			if (user != null && user.isLocalAccount()) {
+				UserModel returnedUser = authenticateLocal(user, password);
+				if (returnedUser != null) {
+					// user authenticated
+					return returnedUser;
+				}
+			} else {
+				// try registered external authentication providers
+				for (AuthenticationProvider provider : authenticationProviders) {
+					if (provider instanceof UsernamePasswordAuthenticationProvider) {
+						UserModel returnedUser = provider.authenticate(usernameDecoded, password);
+						if (returnedUser != null) {
+							// user authenticated
+							returnedUser.accountType = provider.getAccountType();
+							return validateAuthentication(returnedUser, AuthenticationType.CREDENTIALS);
+						}
 					}
 				}
 			}
 		}
+		finally {
+			// Zero out password array to delete password from memory
+			Arrays.fill(password, Character.MIN_VALUE);
+		}
 
 		// could not authenticate locally or with a provider
 		logger.warn(MessageFormat.format("Failed login attempt for {0}, invalid credentials from {1}", username, 
diff --git a/src/main/java/com/gitblit/utils/StringUtils.java b/src/main/java/com/gitblit/utils/StringUtils.java
index b192c80b..442acbbf 100644
--- a/src/main/java/com/gitblit/utils/StringUtils.java
+++ b/src/main/java/com/gitblit/utils/StringUtils.java
@@ -56,6 +56,21 @@ public class StringUtils {
 		return value == null || value.trim().length() == 0;
 	}
 
+	/**
+	 * Returns true if the character array represents an empty String.
+	 * An empty character sequence is defined as a sequence that
+	 * either has no characters at all, or no characters above
+	 * '\u0020' (space).
+	 *
+	 * @param value
+	 * @return true if value is null or represents an empty String
+	 */
+	public static boolean isEmpty(char[] value) {
+		if (value == null || value.length == 0) return true;
+		for ( char c : value) if (c > '\u0020') return false;
+		return true;
+	}
+
 	/**
 	 * Replaces carriage returns and line feeds with html line breaks.
 	 *
-- 
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