Disallow traversal outside of extraction directory

Use new parameter allowParentTraversal to re-enable past behaviour
Added new explicit exception for invalid names
Fixes icsharpcode#232

ICSharpCode.SharpZipLib/Core/InvalidNameException.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace ICSharpCode.SharpZipLib.Core
+{
+
+	/// <summary>
+	/// InvalidNameException is thrown for invalid names such as directory traversal paths and names with invalid characters
+	/// </summary>
+	public class InvalidNameException: SharpZipBaseException
+    {
+		/// <summary>
+		/// Initializes a new instance of the InvalidNameException class with a default error message.
+		/// </summary>
+		public InvalidNameException(): base("An invalid name was specified")
+		{
+		}
+
+		/// <summary>
+		/// Initializes a new instance of the InvalidNameException class with a specified error message.
+		/// </summary>
+		/// <param name="message">A message describing the exception.</param>
+		public InvalidNameException(string message) : base(message)
+		{
+		}
+
+		/// <summary>
+		/// Initializes a new instance of the InvalidNameException class with a specified
+		/// error message and a reference to the inner exception that is the cause of this exception.
+		/// </summary>
+		/// <param name="message">A message describing the exception.</param>
+		/// <param name="innerException">The inner exception</param>
+		public InvalidNameException(string message, Exception innerException) : base(message, innerException)
+		{
+		}
+	}
+}

ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj

@@ -87,6 +87,7 @@
     <Compile Include="Core\FileSystemScanner.cs" />
     <Compile Include="Core\INameTransform.cs" />
     <Compile Include="Core\IScanFilter.cs" />
+    <Compile Include="Core\InvalidNameException.cs" />
     <Compile Include="Core\NameFilter.cs" />
     <Compile Include="Core\PathFilter.cs" />
     <Compile Include="Core\StreamUtils.cs" />
@@ -157,4 +158,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>

ICSharpCode.SharpZipLib/Zip/FastZip.cs

@@ -371,12 +371,13 @@ public void ExtractZip(string zipFileName, string targetDirectory, string fileFi
 		/// <param name="fileFilter">A filter to apply to files.</param>
 		/// <param name="directoryFilter">A filter to apply to directories.</param>
 		/// <param name="restoreDateTime">Flag indicating whether to restore the date and time for extracted files.</param>
+		/// <param name="allowParentTraversal">Allow parent directory traversal in file paths (e.g. ../file)</param>
 		public void ExtractZip(string zipFileName, string targetDirectory,
 							   Overwrite overwrite, ConfirmOverwriteDelegate confirmDelegate,
-							   string fileFilter, string directoryFilter, bool restoreDateTime)
+							   string fileFilter, string directoryFilter, bool restoreDateTime, bool allowParentTraversal = false)
 		{
 			Stream inputStream = File.Open(zipFileName, FileMode.Open, FileAccess.Read, FileShare.Read);
-			ExtractZip(inputStream, targetDirectory, overwrite, confirmDelegate, fileFilter, directoryFilter, restoreDateTime, true);
+			ExtractZip(inputStream, targetDirectory, overwrite, confirmDelegate, fileFilter, directoryFilter, restoreDateTime, true, allowParentTraversal);
 		}
 
 		/// <summary>
@@ -390,10 +391,11 @@ public void ExtractZip(string zipFileName, string targetDirectory, string fileFi
 		/// <param name="directoryFilter">A filter to apply to directories.</param>
 		/// <param name="restoreDateTime">Flag indicating whether to restore the date and time for extracted files.</param>
 		/// <param name="isStreamOwner">Flag indicating whether the inputStream will be closed by this method.</param>
+		/// <param name="allowParentTraversal">Allow parent directory traversal in file paths (e.g. ../file)</param>
 		public void ExtractZip(Stream inputStream, string targetDirectory,
 					   Overwrite overwrite, ConfirmOverwriteDelegate confirmDelegate,
 					   string fileFilter, string directoryFilter, bool restoreDateTime,
-					   bool isStreamOwner)
+					   bool isStreamOwner, bool allowParentTraversal = false)
 		{
 			if ((overwrite == Overwrite.Prompt) && (confirmDelegate == null)) {
 				throw new ArgumentNullException(nameof(confirmDelegate));
@@ -402,7 +404,7 @@ public void ExtractZip(string zipFileName, string targetDirectory, string fileFi
 			continueRunning_ = true;
 			overwrite_ = overwrite;
 			confirmDelegate_ = confirmDelegate;
-			extractNameTransform_ = new WindowsNameTransform(targetDirectory);
+			extractNameTransform_ = new WindowsNameTransform(targetDirectory, allowParentTraversal);
 
 			fileFilter_ = new NameFilter(fileFilter);
 			directoryFilter_ = new NameFilter(directoryFilter);

ICSharpCode.SharpZipLib/Zip/WindowsNameTransform.cs

@@ -14,13 +14,11 @@ public class WindowsNameTransform : INameTransform
 		/// Initialises a new instance of <see cref="WindowsNameTransform"/>
 		/// </summary>
 		/// <param name="baseDirectory"></param>
-		public WindowsNameTransform(string baseDirectory)
+		/// <param name="allowParentTraversal">Allow parent directory traversal in file paths (e.g. ../file)</param>
+		public WindowsNameTransform(string baseDirectory, bool allowParentTraversal = false)
 		{
-			if (baseDirectory == null) {
-				throw new ArgumentNullException(nameof(baseDirectory), "Directory name is invalid");
-			}
-
-			BaseDirectory = baseDirectory;
+			BaseDirectory = baseDirectory ?? throw new ArgumentNullException(nameof(baseDirectory), "Directory name is invalid");
+			AllowParentTraversal = allowParentTraversal;
 		}
 
 		/// <summary>
@@ -45,6 +43,15 @@ public WindowsNameTransform()
 			}
 		}
 
+		/// <summary>
+		/// Allow parent directory traversal in file paths (e.g. ../file)
+		/// </summary>
+		public bool AllowParentTraversal
+		{
+			get => _allowParentTraversal;
+			set => _allowParentTraversal = value;
+		}
+
 		/// <summary>
 		/// Gets or sets a value indicating wether paths on incoming values should be removed.
 		/// </summary>
@@ -66,7 +73,7 @@ public string TransformDirectory(string name)
 					name = name.Remove(name.Length - 1, 1);
 				}
 			} else {
-				throw new ZipException("Cannot have an empty directory name");
+				throw new InvalidNameException("Cannot have an empty directory name");
 			}
 			return name;
 		}
@@ -89,6 +96,11 @@ public string TransformFile(string name)
 				// Combine will throw a PathTooLongException in that case.
 				if (_baseDirectory != null) {
 					name = Path.Combine(_baseDirectory, name);
+
+					if(!_allowParentTraversal && !Path.GetFullPath(name).StartsWith(_baseDirectory, StringComparison.InvariantCultureIgnoreCase))
+					{
+						throw new InvalidNameException("Parent traversal in paths is not allowed");
+					}
 				}
 			} else {
 				name = string.Empty;
@@ -216,6 +228,7 @@ public static string MakeValidName(string name, char replacement)
 		#region Instance Fields
 		string _baseDirectory;
 		bool _trimIncomingPaths;
+		private bool _allowParentTraversal;
 		char _replacementChar = '_';
 		#endregion