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Posted to dev@mina.apache.org by "pyckle (via GitHub)" <gi...@apache.org> on 2023/04/23 13:08:53 UTC
[GitHub] [mina-sshd] pyckle commented on a diff in pull request #362: Fix rooted filesystem
pyckle commented on code in PR #362:
URL: https://github.com/apache/mina-sshd/pull/362#discussion_r1174578418
##########
sshd-common/src/main/java/org/apache/sshd/common/util/io/IoUtils.java:
##########
@@ -637,4 +677,75 @@ public static List<String> readAllLines(BufferedReader reader, int lineCountHint
}
return result;
}
+
+ /**
+ * Chroot a path under the new root
+ *
+ * @param newRoot the new root
+ * @param toSanitize the path to sanitize and chroot
+ * @return the chrooted path under the newRoot filesystem
+ */
+ public static Path chroot(Path newRoot, Path toSanitize) {
+ Objects.requireNonNull(newRoot);
+ Objects.requireNonNull(toSanitize);
+ List<String> sanitized = removeExtraCdUps(toSanitize);
+ return buildPath(newRoot, newRoot.getFileSystem(), sanitized);
+ }
+
+ /**
+ * Remove any extra directory ups from the Path
+ *
+ * @param toSanitize the path to sanitize
+ * @return the sanitized path
+ */
+ public static Path removeCdUpAboveRoot(Path toSanitize) {
+ List<String> sanitized = removeExtraCdUps(toSanitize);
+ return buildPath(toSanitize.getRoot(), toSanitize.getFileSystem(), sanitized);
+ }
+
+ private static List<String> removeExtraCdUps(Path toResolve) {
+ List<String> newNames = new ArrayList<>(toResolve.getNameCount());
+
+ int numCdUps = 0;
+ int numDirParts = 0;
+ for (int i = 0; i < toResolve.getNameCount(); i++) {
+ String name = toResolve.getName(i).toString();
+ if ("..".equals(name)) {
+ // If we have more cdups than dir parts, so we ignore the ".." to avoid jail escapes
+ if (numDirParts > numCdUps) {
+ ++numCdUps;
+ newNames.add(name);
+ }
+ } else {
+ // if the current directory is a part of the name, don't increment number of dir parts, as it doesn't
+ // add to the number of ".."s that can be present before the root
+ if (!".".equals(name)) {
+ ++numDirParts;
+ }
+ newNames.add(name);
+ }
+ }
+ return newNames;
+ }
+
+ private static Path buildPath(Path root, FileSystem fs, List<String> namesList) {
+ if (namesList.isEmpty()) {
+ return root == null ? fs.getPath(".") : root;
+ }
+
+ Path cleanedPathToResolve = buildPath(fs, namesList);
+ return root.resolve(cleanedPathToResolve);
+ }
+
+ private static Path buildPath(FileSystem fs, List<String> namesList) {
Review Comment:
A List is an ordered collection. Why should this API permit an unordered collection?
##########
sshd-common/src/main/java/org/apache/sshd/common/util/io/IoUtils.java:
##########
@@ -637,4 +677,75 @@ public static List<String> readAllLines(BufferedReader reader, int lineCountHint
}
return result;
}
+
+ /**
+ * Chroot a path under the new root
+ *
+ * @param newRoot the new root
+ * @param toSanitize the path to sanitize and chroot
+ * @return the chrooted path under the newRoot filesystem
+ */
+ public static Path chroot(Path newRoot, Path toSanitize) {
+ Objects.requireNonNull(newRoot);
+ Objects.requireNonNull(toSanitize);
+ List<String> sanitized = removeExtraCdUps(toSanitize);
+ return buildPath(newRoot, newRoot.getFileSystem(), sanitized);
+ }
+
+ /**
+ * Remove any extra directory ups from the Path
+ *
+ * @param toSanitize the path to sanitize
+ * @return the sanitized path
+ */
+ public static Path removeCdUpAboveRoot(Path toSanitize) {
+ List<String> sanitized = removeExtraCdUps(toSanitize);
+ return buildPath(toSanitize.getRoot(), toSanitize.getFileSystem(), sanitized);
+ }
+
+ private static List<String> removeExtraCdUps(Path toResolve) {
+ List<String> newNames = new ArrayList<>(toResolve.getNameCount());
+
+ int numCdUps = 0;
+ int numDirParts = 0;
+ for (int i = 0; i < toResolve.getNameCount(); i++) {
+ String name = toResolve.getName(i).toString();
+ if ("..".equals(name)) {
+ // If we have more cdups than dir parts, so we ignore the ".." to avoid jail escapes
+ if (numDirParts > numCdUps) {
+ ++numCdUps;
+ newNames.add(name);
+ }
+ } else {
+ // if the current directory is a part of the name, don't increment number of dir parts, as it doesn't
+ // add to the number of ".."s that can be present before the root
+ if (!".".equals(name)) {
+ ++numDirParts;
+ }
+ newNames.add(name);
+ }
+ }
+ return newNames;
+ }
+
+ private static Path buildPath(Path root, FileSystem fs, List<String> namesList) {
Review Comment:
A List is an ordered collection. Why should this API permit an unordered collection?
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