Changeset 899 for branches/eraser6/Manager/DirectExecutor.cs

Timestamp:

4/28/2009 7:54:00 AM (9 years ago)

Author:

lowjoel

Message:

Refactored out the filesystem-specific code from DirectExecutor? to a FileSystem? class. Currently only implemented for NTFS

File:

• branches/eraser6/Manager/DirectExecutor.cs (modified) (12 diffs)

branches/eraser6/Manager/DirectExecutor.cs

@@ -589 +589 @@
             //Make a folder to dump our temporary files in
             DirectoryInfo info = new DirectoryInfo(target.Drive);
-            {
-                string directoryName;
-                do
-                    directoryName = GenerateRandomFileName(18);
-                while (Directory.Exists(info.FullName + Path.DirectorySeparatorChar + directoryName));
-                info = info.CreateSubdirectory(directoryName);
-            }
+            VolumeInfo volInfo = VolumeInfo.FromMountpoint(target.Drive);
+            FileSystem fsManager = FileSystem.Get(volInfo);
+            info = info.CreateSubdirectory(FileSystem.GenerateRandomFileName(info, 18));
 
             try
@@ -605 +601 @@
 
                 //Determine the total amount of data that needs to be written.
-                VolumeInfo volInfo = VolumeInfo.FromMountpoint(target.Drive);
                 long totalSize = method.CalculateEraseDataSize(null, volInfo.TotalFreeSpace);
 
@@ -614 +609 @@
                 {
                     //Generate a non-existant file name
-                    string currFile;
-                    do
-                        currFile = info.FullName + Path.DirectorySeparatorChar +
-                            GenerateRandomFileName(18);
-                    while (System.IO.File.Exists(currFile));
+                    string currFile = FileSystem.GenerateRandomFileName(info, 18);
 
                     //Create the stream
@@ -673 +664 @@
                 progress.Event.CurrentItemName = S._("Old resident file system table files");
                 task.OnProgressChanged(progress.Event);
-                EraseOldFilesystemResidentFiles(info, method, null);
+                fsManager.EraseOldFilesystemResidentFiles(volInfo, method, null);
             }
             finally
@@ -680 +671 @@
                 progress.Event.CurrentItemName = S._("Removing temporary files");
                 task.OnProgressChanged(progress.Event);
-                RemoveFolder(info);
+                fsManager.DeleteFolder(info);
             }
 
@@ -687 +678 @@
             ProgressManager fsEntriesProgress = new ProgressManager();
             fsEntriesProgress.Start();
-            EraseOldFilesystemEntries(info.Parent,
+            fsManager.EraseDirectoryStructures(volInfo,
                 delegate(int currentFile, int totalFiles)
                 {
+                    lock (currentTask)
+                        if (currentTask.Cancelled)
+                            throw new FatalException(S._("The task was cancelled."));
+
                     //Compute the progress
                     fsEntriesProgress.Total = totalFiles;
@@ -869 +864 @@
         #region Filesystem Object erasure functions
         /// <summary>
-        /// The prototype of callbacks handling the file system table erase progress
-        /// </summary>
-        /// <param name="currentFile">The current file being erased.</param>
-        /// <param name="totalFiles">The estimated number of files that must be erased.</param>
-        private delegate void FilesystemEntriesEraseProgress(int currentFile, int totalFiles);
-        
-        /// <summary>
-        /// Erases old file system table-resident files. This creates small one-byte
-        /// files until disk is full. This will erase unused space which was used for
-        /// files resident in the file system table.
-        /// </summary>
-        /// <param name="info">The directory information structure containing
-        /// the path to store the temporary one-byte files. The file system table
-        /// of that drive will be erased.</param>
-        /// <param name="method">The method used to erase the files.</param>
-        private void EraseOldFilesystemResidentFiles(DirectoryInfo info, ErasureMethod method,
-            FilesystemEntriesEraseProgress callback)
-        {
-            VolumeInfo volInfo = VolumeInfo.FromMountpoint(info.FullName);
-            if (volInfo.VolumeFormat == "NTFS")
-            {
-                try
-                {
-                    //Squeeze one-byte files until the volume or the MFT is full.
-                    long oldMFTSize = NtfsAPI.GetMftValidSize(volInfo);
-                    for ( ; ; )
-                    {
-                        //Open this stream
-                        using (FileStream strm = new FileStream(Path.Combine(
-                            info.FullName, GenerateRandomFileName(18)),
-                            FileMode.CreateNew, FileAccess.Write, FileShare.None, 8,
-                            FileOptions.WriteThrough))
-                        {
-                            //Stretch the file size to use up some of the resident space.
-                            strm.SetLength(1);
-
-                            //Then run the erase task
-                            method.Erase(strm, long.MaxValue,
-                                PRNGManager.GetInstance(ManagerLibrary.Instance.Settings.ActivePRNG),
-                                null);
-                        }
-
-                        //We can stop when the MFT has grown.
-                        if (NtfsAPI.GetMftValidSize(volInfo) > oldMFTSize)
-                            break;
-                    }
-                }
-                catch (IOException)
-                {
-                    //OK, enough squeezing.
-                }
-            }
-        }
-
-        /// <summary>
-        /// Erases the unused space in the file system table by creating files, until
-        /// the table grows.
-        /// 
-        /// This will overwrite unused portions of the table which were previously
-        /// used to store file entries.
-        /// </summary>
-        /// <param name="info">The directory information structure containing the path
-        /// to store the temporary files.</param>
-        /// <param name="callback">The callback function to handle the progress of the
-        /// file system entry erasure.</param>
-        private void EraseOldFilesystemEntries(DirectoryInfo info, FilesystemEntriesEraseProgress callback)
-        {
-            VolumeInfo volInfo = VolumeInfo.FromMountpoint(info.FullName);
-            if (volInfo.VolumeFormat == "NTFS")
-            {
-                //Create a directory to hold all the temporary files
-                DirectoryInfo tempDir = info.CreateSubdirectory(GenerateRandomFileName(32));
-
-                try
-                {
-                    //Get the size of the MFT
-                    long mftSize = NtfsAPI.GetMftValidSize(volInfo);
-                    long mftRecordSegmentSize = NtfsAPI.GetMftRecordSegmentSize(volInfo);
-                    int pollingInterval = (int)Math.Max(1, (mftSize / volInfo.ClusterSize / 20));
-                    int totalFiles = (int)Math.Max(1L, mftSize / mftRecordSegmentSize) *
-                        (FilenameErasePasses + 1);
-                    int filesCreated = 0;
-
-                    while (true)
-                    {
-                        ++filesCreated;
-                        using (FileStream strm = new FileStream(Path.Combine(
-                            tempDir.FullName, GenerateRandomFileName(220)),
-                            FileMode.CreateNew, FileAccess.Write))
-                        {
-                        }
-
-                        if (filesCreated % pollingInterval == 0)
-                        {
-                            if (callback != null)
-                                callback(filesCreated, totalFiles);
-
-                            lock (currentTask)
-                                if (currentTask.Cancelled)
-                                    throw new FatalException(S._("The task was cancelled."));
-
-                            //Check if the MFT has grown.
-                            if (mftSize < NtfsAPI.GetMftValidSize(volInfo))
-                                break;
-                        }
-                    }
-                }
-                catch (IOException)
-                {
-                }
-                finally
-                {
-                    //Clear up all the temporary files
-                    FileInfo[] files = tempDir.GetFiles("*", SearchOption.AllDirectories);
-                    int totalFiles = files.Length * (FilenameErasePasses + 1);
-                    for (int i = 0; i < files.Length; ++i)
-                    {
-                        if (callback != null && i % 50 == 0)
-                            callback(files.Length + i * FilenameErasePasses, totalFiles);
-                        RemoveFile(files[i]);
-                    }
-                    
-                    RemoveFolder(tempDir);
-                }
-            }
-            else
-                throw new NotImplementedException(S._("Could not erase old file system " +
-                    "entries: Unsupported File system")); //Eraser.cpp@2348
-        }
-
-        /// <summary>
         /// Erases a file or folder on the volume.
         /// </summary>
@@ -1028 +892 @@
                 progress.Event.CurrentTargetTotalPasses = method.Passes;
                 task.OnProgressChanged(progress.Event);
-
                 
+                //Get the filesystem provider to handle the secure file erasures
+                FileSystem fsManager = FileSystem.Get(VolumeInfo.FromMountpoint(paths[i]));
+
                 //Remove the read-only flag, if it is set.
                 StreamInfo info = new StreamInfo(paths[i]);
@@ -1095 +961 @@
                     FileInfo fileInfo = info.File;
                     if (fileInfo != null)
-                        RemoveFile(fileInfo);
+                        fsManager.DeleteFile(fileInfo);
                 }
                 catch (UnauthorizedAccessException)
@@ -1118 +984 @@
             if (target is Task.Folder)
             {
+                progress.Event.CurrentItemName = S._("Removing folders...");
+                task.OnProgressChanged(progress.Event);
+
                 Task.Folder fldr = (Task.Folder)target;
                 if (fldr.DeleteIfEmpty)
-                    RemoveFolder(new DirectoryInfo(fldr.Path));
+                {
+                    FileSystem fsManager = FileSystem.Get(VolumeInfo.FromMountpoint(fldr.Path));
+                    fsManager.DeleteFolder(new DirectoryInfo(fldr.Path));
+                }
             }
 
@@ -1126 +998 @@
             if (target is Task.RecycleBin)
             {
+                progress.Event.CurrentItemName = S._("Emptying recycle bin...");
+                task.OnProgressChanged(progress.Event);
+
                 ShellAPI.SHEmptyRecycleBin(IntPtr.Zero, null,
                     ShellAPI.SHEmptyRecycleBinFlags.SHERB_NOCONFIRMATION |
@@ -1149 +1024 @@
 
         /// <summary>
-        /// Securely removes files.
-        /// </summary>
-        /// <param name="info">The FileInfo object representing the file.</param>
-        private static void RemoveFile(FileInfo info)
-        {
-            //Set the date of the file to be invalid to prevent forensic
-            //detection
-            info.CreationTime = info.LastWriteTime = info.LastAccessTime =
-                new DateTime(1980, 1, 1, 0, 0, 0);
-            info.Attributes = FileAttributes.Normal;
-            info.Attributes = FileAttributes.NotContentIndexed;
-
-            //Rename the file a few times to erase the entry from the file system
-            //table.
-            string newPath = info.DirectoryName + Path.DirectorySeparatorChar +
-                GenerateRandomFileName(info.Name.Length);
-            for (int i = 0, tries = 0; i < FilenameErasePasses; ++tries)
-            {
-                //Try to rename the file. If it fails, it is probably due to another
-                //process locking the file. Defer, then rename again.
-                try
-                {
-                    info.MoveTo(newPath);
-                    ++i;
-                }
-                catch (IOException)
-                {
-                    Thread.Sleep(100);
-
-                    //If after FilenameEraseTries the file is still locked, some program is
-                    //definitely using the file; throw an exception.
-                    if (tries > FilenameEraseTries)
-                        throw new IOException(S._("The file {0} is currently in use and " +
-                            "cannot be removed.", info.FullName));
-                }
-            }
-
-            //If the user wants plausible deniability, find a random file on the same
-            //volume and write it over.
-            if (Manager.ManagerLibrary.Instance.Settings.PlausibleDeniability)
-            {
-                //Get the template file to copy
-                FileInfo shadowFileInfo;
-                {
-                    string shadowFile = null;
-                    List<string> entries = ManagerLibrary.Instance.Settings.PlausibleDeniabilityFiles.GetRange(
-                        0, ManagerLibrary.Instance.Settings.PlausibleDeniabilityFiles.Count);
-                    PRNG prng = PRNGManager.GetInstance(ManagerLibrary.Instance.Settings.ActivePRNG);
-                    do
-                    {
-                        if (entries.Count == 0)
-                            throw new FatalException(S._("Plausible deniability was selected, " +
-                                "but no decoy files were found. The current file has been only " +
-                                "replaced with random data."));
-
-                        int index = prng.Next(entries.Count - 1);
-                        if ((System.IO.File.GetAttributes(entries[index]) & FileAttributes.Directory) != 0)
-                        {
-                            DirectoryInfo dir = new DirectoryInfo(entries[index]);
-                            FileInfo[] files = dir.GetFiles("*", SearchOption.AllDirectories);
-                            foreach (FileInfo f in files)
-                                entries.Add(f.FullName);
-                        }
-                        else
-                            shadowFile = entries[index];
-
-                        entries.RemoveAt(index);
-                    }
-                    while (shadowFile == null || shadowFile.Length == 0);
-                    shadowFileInfo = new FileInfo(shadowFile);
-                }
-
-                //Dump the copy (the first 4MB, or less, depending on the file size and available
-                //user space)
-                long amountToCopy = Math.Min(4 * 1024 * 1024, shadowFileInfo.Length);
-                using (FileStream shadowFileStream = shadowFileInfo.OpenRead())
-                using (FileStream destFileStream = info.OpenWrite())
-                {
-                    while (destFileStream.Position < amountToCopy)
-                    {
-                        byte[] buf = new byte[524288];
-                        int bytesRead = shadowFileStream.Read(buf, 0, buf.Length);
-
-                        //Stop bothering if the input stream is at the end
-                        if (bytesRead == 0)
-                            break;
-
-                        //Dump the read contents onto the file to be deleted
-                        destFileStream.Write(buf, 0,
-                            (int)Math.Min(bytesRead, amountToCopy - destFileStream.Position));
-                    }
-                }
-            }
-
-            //Then delete the file.
-            for (int i = 0; i < FilenameEraseTries; ++i)
-                try
-                {
-                    info.Delete();
-                    break;
-                }
-                catch (IOException)
-                {
-                    if (i > FilenameEraseTries)
-                        throw new IOException(S._("The file {0} is currently in use and " +
-                            "cannot be removed.", info.FullName));
-                    Thread.Sleep(100);
-                }
-        }
-
-        /// <summary>
-        /// Removes the folder and all its contents.
-        /// </summary>
-        /// <param name="info">The folder to remove.</param>
-        private static void RemoveFolder(DirectoryInfo info)
-        {
-            foreach (DirectoryInfo dir in info.GetDirectories())
-                RemoveFolder(dir);
-            foreach (FileInfo file in info.GetFiles())
-                RemoveFile(file);
-
-            //Then clean up this folder.
-            for (int i = 0; i < FilenameErasePasses; ++i)
-            {
-                //Rename the folder.
-                string newPath = info.Parent.FullName + Path.DirectorySeparatorChar +
-                    GenerateRandomFileName(info.Name.Length);
-
-                //Try to rename the file. If it fails, it is probably due to another
-                //process locking the file. Defer, then rename again.
-                try
-                {
-                    info.MoveTo(newPath);
-                }
-                catch (IOException)
-                {
-                    Thread.Sleep(100);
-                    --i;
-                }
-            }
-
-            //Remove the folder
-            info.Delete(true);
-        }
-
-        /// <summary>
-        /// Generates a random file name with the given length.
-        /// </summary>
-        /// <param name="length">The length of the file name to generate.</param>
-        /// <returns>A random file name.</returns>
-        private static string GenerateRandomFileName(int length)
-        {
-            //Get a random file name
-            PRNG prng = PRNGManager.GetInstance(ManagerLibrary.Instance.Settings.ActivePRNG);
-            byte[] newFileNameAry = new byte[length];
-            prng.NextBytes(newFileNameAry);
-
-            //Validate the name
-            string validFileNameChars = "0123456789abcdefghijklmnopqrstuvwxyz" +
-                "ABCDEFGHIJKLMNOPQRSTUVWXYZ _+=-()[]{}',`~!";
-            for (int j = 0, k = newFileNameAry.Length; j < k; ++j)
-                newFileNameAry[j] = (byte)validFileNameChars[
-                    (int)newFileNameAry[j] % validFileNameChars.Length];
-
-            return new System.Text.UTF8Encoding().GetString(newFileNameAry);
-        }
-
-        /// <summary>
-        /// Gets a random file from within the provided directory.
-        /// </summary>
-        /// <param name="info">The directory to get a random file name from.</param>
-        /// <returns>A string containing the full path to the file.</returns>
-        private static string GetRandomFileName(DirectoryInfo info)
-        {
-            //First retrieve the list of files and folders in the provided directory.
-            FileSystemInfo[] entries = null;
-            try
-            {
-                entries = info.GetFileSystemInfos();
-            }
-            catch (Exception)
-            {
-                return string.Empty;
-            }
-            if (entries.Length == 0)
-                return string.Empty;
-
-            //Find a random entry.
-            PRNG prng = PRNGManager.GetInstance(ManagerLibrary.Instance.Settings.ActivePRNG);
-            string result = string.Empty;
-            while (result.Length == 0)
-            {
-                int index = prng.Next(entries.Length - 1);
-                if (entries[index] is DirectoryInfo)
-                    result = GetRandomFileName((DirectoryInfo)entries[index]);
-                else
-                    result = ((FileInfo)entries[index]).FullName;
-            }
-
-            return result;
-        }
-
-        /// <summary>
         /// The thread object.
         /// </summary>