Author: markt
Date: Thu Sep 21 20:09:32 2017
New Revision: 1809212
URL: http://svn.apache.org/viewvc?rev=1809212&view=rev
Log:
Refactor and add additional comments to make intended behaviour clearer.
Modified:
tomcat/trunk/java/org/apache/catalina/webresources/AbstractFileResourceSet.java
Modified:
tomcat/trunk/java/org/apache/catalina/webresources/AbstractFileResourceSet.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/webresources/AbstractFileResourceSet.java?rev=1809212&r1=1809211&r2=1809212&view=diff
==============================================================================
---
tomcat/trunk/java/org/apache/catalina/webresources/AbstractFileResourceSet.java
(original)
+++
tomcat/trunk/java/org/apache/catalina/webresources/AbstractFileResourceSet.java
Thu Sep 21 20:09:32 2017
@@ -65,50 +65,60 @@ public abstract class AbstractFileResour
return null;
}
- if (!mustExist || file.canRead()) {
+ // If the file/dir must exist but the identified file/dir can't be read
+ // then signal that the resource was not found
+ if (mustExist && !file.canRead()) {
+ return null;
+ }
- if (getRoot().getAllowLinking()) {
- return file;
- }
-
- // Check that this file is located under the WebResourceSet's base
- String canPath = null;
- try {
- canPath = file.getCanonicalPath();
- } catch (IOException e) {
- // Ignore
- }
- if (canPath == null)
- return null;
-
- if (!canPath.startsWith(canonicalBase)) {
- return null;
- }
-
- // Case sensitivity check
- // Note: We know the resource is located somewhere under base at
- // point. The purpose of this code is to check in a case
- // sensitive manner, the path to the resource under base
- // agrees with what was requested
- String absPath = normalize(file.getAbsolutePath());
- if ((absoluteBase.length() < absPath.length())
- && (canonicalBase.length() < canPath.length())) {
- absPath = absPath.substring(absoluteBase.length() + 1);
- if (absPath.equals("")) {
- absPath = "/";
- }
- canPath = canPath.substring(canonicalBase.length() + 1);
- if (canPath.equals("")) {
- canPath = "/";
- }
- if (!canPath.equals(absPath)) {
- return null;
- }
- }
+ // If allow linking is enabled, files are not limited to being located
+ // under the fileBase so all further checks are disabled.
+ if (getRoot().getAllowLinking()) {
+ return file;
+ }
- } else {
+ // Check that this file is located under the WebResourceSet's base
+ String canPath = null;
+ try {
+ canPath = file.getCanonicalPath();
+ } catch (IOException e) {
+ // Ignore
+ }
+ if (canPath == null || !canPath.startsWith(canonicalBase)) {
return null;
}
+
+ // Ensure that the file is not outside the fileBase. This should not be
+ // possible for standard requests (the request is normalized early in
+ // the request processing) but might be possible for some access via
the
+ // Servlet API (RequestDispatcher, HTTP/2 push etc.) therefore these
+ // checks are retained as an additional safety measure
+ // absoluteBase has been normalized so absPath needs to normalized as
+ // well.
+ String absPath = normalize(file.getAbsolutePath());
+ if (absoluteBase.length() > absPath.length() ||
+ canonicalBase.length() > canPath.length()) {
+ return null;
+ }
+
+ // Remove the fileBase location from the start of the paths since that
+ // was not part of the requested path and the remaining check only
+ // applies to the request path
+ absPath = absPath.substring(absoluteBase.length());
+ canPath = canPath.substring(canonicalBase.length());
+
+ // Case sensitivity check
+ // The normalized requested path should be an exact match the
equivalent
+ // canonical path. If it is not, possible reasons include:
+ // - case differences on case insensitive file systems
+ // - Windows removing a trailing ' ' or '.' from the file name
+ //
+ // In all cases, a mis-match here results in the resource not being
+ // found
+ if (!canPath.equals(absPath)) {
+ return null;
+ }
+
return file;
}
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