Kenneth Skovhede
a7ef8e42f2
This PR is a security hardning change and will break some setups. The hardning is done to ensure the datafolder is not compromised and particularly that it is not maliciously seeded. The changes now **requires** that the datafolder is locked down with exact permissions, or Duplicati will refuse to use it. This is a change to prior functionality where the folder would simply be locked down if it was not already locked. Previously, a file named `insecure-permissions.txt` could be placed in the folder to instruct Duplicati not to set permissions. With this change that file is no longer supported. The only way to opt-out of the permission check is to supply `--allow-insecure-datafolder` or the environment variable `DUPLICATI__ALLOW_INSECURE_DATAFOLDER`. Once either of those are set, Duplicati will no longer check permissions and accept folders with other permissions. The setting can be applied to `preload.json`, but the file needs to be in a trusted location, which is either the directory with the binaries or the file pointed to by `DUPLICATI_PRELOAD_SETTINGS`. The setting cannot be placed in a `preload.json` file that is in an insecure folder as the folder is not read if the permissions are not correct. The previous paths `/usr/local/share/Duplicati/preload.json` and `C:\ProgramData\Duplicati\preload.json` are no longer supported as they cannot be guaranteed to be locked down. A `preload.json` in the datafolder is still supported, provided the folder passes the permission check (or the `--allow-insecure-datafolder` is passed to the executable). For most users, this should not cause any problems as Duplicati has been locking down the folders, so they should be correctly locked down already. The configuretool has been updated with a `secure-datafolder` command that can be used to force the correct permissions on a folder, in case the folder did not have the correct permissions. For some Docker setups it may not be possible to set the permissions and the check will fail. These setup will need to apply `DUPLICATI__ALLOW_INSECURE_DATAFOLDER=true` in the image to run without the protections.
555 lines
20 KiB
C#
555 lines
20 KiB
C#
// Copyright (C) 2026, The Duplicati Team
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// https://duplicati.com, hello@duplicati.com
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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using System;
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using System.IO;
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using System.Linq;
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using System.Collections.Generic;
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using Duplicati.Library.Interface;
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using Duplicati.Library.Logging;
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using System.Runtime.Versioning;
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using System.Runtime.InteropServices;
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namespace Duplicati.Library.Common.IO
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{
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[SupportedOSPlatform("linux")]
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[SupportedOSPlatform("macOS")]
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public struct SystemIOLinux : ISystemIO
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{
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/// <summary>
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/// The log tag for messages
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/// </summary>
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private static readonly string LOGTAG = Log.LogTagFromType(typeof(SystemIOLinux));
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/// <summary>
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/// PInvoke methods
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/// </summary>
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private static class PInvoke
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{
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/// <summary>
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/// Gets the user ID of the current user
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/// </summary>
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/// <returns>The user ID</returns>
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[DllImport("libc")]
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public static extern uint getuid();
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/// <summary>
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/// Gets the group ID of the current user
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/// </summary>
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/// <returns></returns>
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[DllImport("libc")]
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public static extern uint getgid();
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}
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#region ISystemIO implementation
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public void DirectoryCreate(string path)
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{
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Directory.CreateDirectory(NormalizePath(path));
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}
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public void DirectoryDelete(string path, bool recursive)
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{
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Directory.Delete(NormalizePath(path), recursive);
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}
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public bool DirectoryExists(string path)
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{
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return Directory.Exists(NormalizePath(path));
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}
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public void DirectoryMove(string sourceDirName, string destDirName)
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{
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System.IO.Directory.Move(NormalizePath(sourceDirName), NormalizePath(destDirName));
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}
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public void FileDelete(string path)
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{
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File.Delete(path);
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}
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public void FileSetLastWriteTimeUtc(string path, DateTime time)
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{
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File.SetLastWriteTimeUtc(path, time);
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var gtime = FileGetLastWriteTimeUtc(path);
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if (gtime != time)
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{
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Console.Error.WriteLine($"DISS: {path} {gtime.ToFileTimeUtc() - time.ToFileTimeUtc()}");
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}
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}
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public void FileSetCreationTimeUtc(string path, DateTime time)
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{
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File.SetCreationTimeUtc(path, time);
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}
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public DateTime FileGetLastWriteTimeUtc(string path)
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{
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return File.GetLastWriteTimeUtc(path);
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}
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public DateTime FileGetCreationTimeUtc(string path)
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{
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return File.GetCreationTimeUtc(path);
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}
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public bool FileExists(string path)
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{
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return File.Exists(path);
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}
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public FileStream FileOpenRead(string path)
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{
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return File.OpenRead(path);
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}
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public FileStream FileOpenReadWrite(string path)
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{
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return File.Exists(path)
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? File.Open(path, FileMode.Open, FileAccess.ReadWrite)
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: File.Create(path);
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}
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public FileStream FileOpenWrite(string path)
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{
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return File.OpenWrite(path);
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}
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public FileStream FileCreate(string path)
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{
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return File.Create(path);
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}
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public FileAttributes GetFileAttributes(string path)
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{
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return File.GetAttributes(NormalizePath(path));
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}
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public void SetFileAttributes(string path, FileAttributes attributes)
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{
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File.SetAttributes(path, attributes);
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}
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public void CreateSymlink(string symlinkfile, string target, bool asDir)
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{
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PosixFile.CreateSymlink(symlinkfile, target);
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}
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public string GetSymlinkTarget(string path)
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{
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return PosixFile.GetSymlinkTarget(NormalizePath(path));
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}
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public string PathGetDirectoryName(string path)
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{
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return Path.GetDirectoryName(NormalizePath(path));
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}
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public IEnumerable<string> EnumerateFileSystemEntries(string path)
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{
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return Directory.EnumerateFileSystemEntries(path);
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}
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public IEnumerable<string> EnumerateFiles(string path)
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{
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return Directory.EnumerateFiles(path);
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}
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public IEnumerable<string> EnumerateFiles(string path, string searchPattern, SearchOption searchOption)
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{
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return Directory.EnumerateFiles(path, searchPattern, searchOption);
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}
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public IEnumerable<IFileEntry> EnumerateFileEntries(string path)
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{
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// For consistency with previous implementation, enumerate files first and directories after
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DirectoryInfo dir = new DirectoryInfo(path);
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foreach (FileInfo file in dir.EnumerateFiles())
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{
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yield return FileEntry(file);
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}
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foreach (DirectoryInfo d in dir.EnumerateDirectories())
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{
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yield return DirectoryEntry(d);
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}
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}
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public string PathGetFileName(string path)
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{
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return Path.GetFileName(path);
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}
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public string PathGetExtension(string path)
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{
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return Path.GetExtension(path);
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}
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public string PathChangeExtension(string path, string extension)
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{
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return Path.ChangeExtension(path, extension);
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}
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public string PathCombine(params string[] paths)
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{
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return Path.Combine(paths);
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}
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public void DirectorySetLastWriteTimeUtc(string path, DateTime time)
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{
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Directory.SetLastWriteTimeUtc(NormalizePath(path), time);
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}
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public void DirectorySetCreationTimeUtc(string path, DateTime time)
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{
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Directory.SetCreationTimeUtc(NormalizePath(path), time);
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}
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public void FileMove(string source, string target)
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{
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File.Move(source, target);
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}
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public long FileLength(string path)
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{
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return new FileInfo(path).Length;
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}
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public Dictionary<string, string> GetMetadata(string file, bool isSymlink, bool followSymlink)
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{
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var f = NormalizePath(file);
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var dict = new Dictionary<string, string>();
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var n = PosixFile.GetExtendedAttributes(f, isSymlink, followSymlink);
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if (n != null)
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foreach (var x in n)
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dict["unix-ext:" + x.Key] = Convert.ToBase64String(x.Value);
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var fse = PosixFile.GetUserGroupAndPermissions(f);
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dict["unix:uid-gid-perm"] = string.Format("{0}-{1}-{2}", fse.UID, fse.GID, fse.Permissions);
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if (fse.OwnerName != null)
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{
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dict["unix:owner-name"] = fse.OwnerName;
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}
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if (fse.GroupName != null)
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{
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dict["unix:group-name"] = fse.GroupName;
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}
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if (OperatingSystem.IsMacOS())
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{
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try
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{
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var flags = PosixFile.GetFileFlags(f, isSymlink, followSymlink);
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if (flags.HasValue)
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dict["macos:flags"] = flags.Value.ToString();
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}
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catch (Exception ex)
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{
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Log.WriteVerboseMessage(LOGTAG, "GetFileFlagsFailed", ex, "Failed to get file flags for \"{0}\"", f);
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}
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try
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{
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var acl = PosixFile.GetAcl(f, isSymlink, followSymlink);
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if (!string.IsNullOrEmpty(acl))
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dict["macos:acl"] = acl;
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}
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catch (Exception ex)
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{
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Log.WriteVerboseMessage(LOGTAG, "GetAclFailed", ex, "Failed to get ACL for \"{0}\"", f);
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}
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}
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return dict;
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}
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public void SetMetadata(string file, Dictionary<string, string> data, bool restorePermissions)
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{
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if (data == null)
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return;
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var f = NormalizePath(file);
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foreach (var x in data.Where(x => x.Key.StartsWith("unix-ext:", StringComparison.Ordinal)).Select(x => new KeyValuePair<string, byte[]>(x.Key.Substring("unix-ext:".Length), Convert.FromBase64String(x.Value))))
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PosixFile.SetExtendedAttribute(f, x.Key, x.Value);
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if (restorePermissions && data.ContainsKey("unix:uid-gid-perm"))
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{
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var parts = data["unix:uid-gid-perm"].Split(new char[] { '-' });
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if (parts.Length == 3)
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{
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long uid;
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long gid;
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long perm;
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if (long.TryParse(parts[0], out uid) && long.TryParse(parts[1], out gid) && long.TryParse(parts[2], out perm))
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{
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if (data.ContainsKey("unix:owner-name"))
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try { uid = PosixFile.GetUserID(data["unix:owner-name"]); }
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catch { }
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if (data.ContainsKey("unix:group-name"))
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try { gid = PosixFile.GetGroupID(data["unix:group-name"]); }
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catch { }
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PosixFile.SetUserGroupAndPermissions(f, uid, gid, perm);
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}
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}
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}
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if (OperatingSystem.IsMacOS())
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{
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// SetMetadata is only reached for a symlink when the metadata should be
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// applied to the link itself (the restore destination skips symlinks
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// otherwise), so operate on the link rather than following it.
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var isSymlink = false;
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try { isSymlink = PosixFile.GetFileType(f) == PosixFile.FileType.Symlink; }
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catch { }
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if (restorePermissions)
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{
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// Apply ACL before file flags, as flags like uchg (immutable) can prevent ACL changes
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if (data.TryGetValue("macos:acl", out var acl) && !string.IsNullOrWhiteSpace(acl))
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{
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try { PosixFile.SetAcl(f, acl, isSymlink, followSymlink: false); }
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catch (Exception ex)
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{
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Log.WriteWarningMessage(LOGTAG, "SetAclFailed", ex, "Failed to restore ACL on \"{0}\": {1}", f, ex.Message);
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}
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}
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// We consider file flags to be part of the permissions
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if (data.TryGetValue("macos:flags", out var flagsStr) && uint.TryParse(flagsStr, out var flags))
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{
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try { PosixFile.SetFileFlags(f, flags, isSymlink, followSymlink: false); }
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catch (Exception ex)
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{
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Log.WriteWarningMessage(LOGTAG, "SetFileFlagsFailed", ex, "Failed to restore file flags on \"{0}\": {1}", f, ex.Message);
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}
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}
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}
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}
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}
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public string GetPathRoot(string path)
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{
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return Path.GetPathRoot(path);
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}
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public string[] GetDirectories(string path)
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{
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return Directory.GetDirectories(path);
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}
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public string[] GetFiles(string path)
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{
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return Directory.GetFiles(path);
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}
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public string[] GetFiles(string path, string searchPattern)
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{
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return Directory.GetFiles(path, searchPattern);
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}
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public DateTime GetCreationTimeUtc(string path)
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{
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return File.GetCreationTimeUtc(path);
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}
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public DateTime GetLastWriteTimeUtc(string path)
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{
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return File.GetLastWriteTimeUtc(path);
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}
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public IEnumerable<string> EnumerateDirectories(string path)
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{
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return Directory.EnumerateDirectories(path);
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}
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public void FileCopy(string source, string target, bool overwrite)
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{
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File.Copy(source, target, overwrite);
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}
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public string PathGetFullPath(string path)
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{
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return Path.GetFullPath(path);
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}
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#endregion
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/// <summary>
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/// Normalizes a path, by removing any trailing slash, before calling system methods
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/// </summary>
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/// <returns>The path to normalize.</returns>
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/// <param name="path">The normalized path.</param>
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public static string NormalizePath(string path)
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{
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var p = Path.GetFullPath(path);
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// This should not be required, but some versions of Mono apparently do not strip the trailing slash
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return p.Length > 1 && p[p.Length - 1] == Path.DirectorySeparatorChar ? p.Substring(0, p.Length - 1) : p;
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}
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public IFileEntry DirectoryEntry(string path)
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{
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return DirectoryEntry(new DirectoryInfo(path));
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}
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public IFileEntry DirectoryEntry(DirectoryInfo dInfo)
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{
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return new FileEntry(dInfo.Name, 0, dInfo.LastAccessTime, dInfo.LastWriteTime)
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{
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IsFolder = true
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};
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}
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public IFileEntry FileEntry(string path)
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{
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return FileEntry(new FileInfo(path));
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}
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public IFileEntry FileEntry(FileInfo fileInfo)
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{
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return new FileEntry(fileInfo.Name, fileInfo.Length, fileInfo.LastAccessTime, fileInfo.LastWriteTime);
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}
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private static (long uid, long gid) GetOwnerAndGroup(string path)
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{
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var fi = PosixFile.GetUserGroupAndPermissions(path);
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return (fi.UID, fi.GID);
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}
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/// <summary>
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/// Sets the unix permission user read-write Only.
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/// </summary>
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/// <param name="path">The file to set permissions on.</param>
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public void FileSetPermissionUserRWOnly(string path)
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{
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PosixFile.SetUserGroupAndPermissions(
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path,
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PInvoke.getuid(),
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PInvoke.getgid(),
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Convert.ToInt32("600", 8) /* FilePermissions.S_IRUSR | FilePermissions.S_IWUSR*/
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);
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}
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/// <summary>
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/// Sets the permission to read-write only for the current user.
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/// </summary>
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/// <param name="path">The directory to set permissions on.</param>
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public void DirectorySetPermissionUserRWOnly(string path)
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{
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PosixFile.SetUserGroupAndPermissions(
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path,
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PInvoke.getuid(),
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PInvoke.getgid(),
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Convert.ToInt32("700", 8) /* FilePermissions.S_IRUSR | FilePermissions.S_IWUSR | FilePermissions.S_IXUSR */
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);
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}
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/// <summary>
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/// Checks whether the directory has the read-write only permission for the current user,
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/// matching the permissions applied by <see cref="DirectorySetPermissionUserRWOnly"/>.
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/// </summary>
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/// <param name="path">The directory to check permissions on.</param>
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/// <param name="detail">A human-readable description of why the check failed, if it did; otherwise <see cref="string.Empty"/>.</param>
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/// <returns><c>true</c> if the directory has the expected permissions; otherwise <c>false</c>.</returns>
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public bool DirectoryHasPermissionUserRWOnly(string path, out string detail)
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=> HasPermissionUserRWOnly(path, Convert.ToInt32("700", 8), out detail);
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/// <summary>
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/// The root user id, which is always considered a trusted owner.
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/// </summary>
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private const long RootUid = 0;
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/// <summary>
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/// Checks whether the path has the expected user read-write only permission.
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/// The owner may be either the current user or root: a root-owned, mode 0700
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/// directory is a common and secure setup (for example a system service reading a
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/// configuration folder provisioned by an installer running as root), so it must not
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/// be rejected. The security property that matters is that no group or other access
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/// bits are set; the exact owning uid/gid beyond "current user or root" is not required.
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/// </summary>
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/// <param name="path">The path to check permissions on.</param>
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/// <param name="expectedMode">The expected octal mode (e.g. 0700 for directories).</param>
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/// <param name="detail">A human-readable description of why the check failed, if it did; otherwise <see cref="string.Empty"/>.</param>
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/// <returns><c>true</c> if the expected permissions are set; otherwise <c>false</c>.</returns>
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private static bool HasPermissionUserRWOnly(string path, int expectedMode, out string detail)
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{
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detail = string.Empty;
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try
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{
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var info = PosixFile.GetUserGroupAndPermissions(path);
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var expectedModeStr = Convert.ToString(expectedMode, 8);
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if ((info.Permissions & expectedMode) != expectedMode)
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{
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detail = $"permissions are {Convert.ToString((long)info.Permissions, 8)} but expected {expectedModeStr}";
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return false;
|
|
}
|
|
|
|
// No group/other access bits should be set
|
|
var groupAndOther = Convert.ToInt32("077", 8);
|
|
if ((info.Permissions & groupAndOther) != 0)
|
|
{
|
|
detail = $"permissions allow group or other access ({Convert.ToString((long)info.Permissions, 8)})";
|
|
return false;
|
|
}
|
|
|
|
// The owner must be the current user or root. A root-owned folder is trusted
|
|
// because only root (a fully privileged principal) could have created it, and
|
|
// an unprivileged attacker cannot own a folder as root.
|
|
var uid = PInvoke.getuid();
|
|
if (info.UID != uid && info.UID != RootUid)
|
|
{
|
|
detail = $"owner is uid {info.UID} but expected the current user (uid {uid}) or root";
|
|
return false;
|
|
}
|
|
}
|
|
catch (Exception ex)
|
|
{
|
|
detail = $"failed to read permissions: {ex.Message}";
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// <inheritdoc />
|
|
public bool SupportsAlternateDataStreams => false;
|
|
|
|
/// <inheritdoc />
|
|
public IEnumerable<string> EnumerateAlternateDataStreams(string path)
|
|
=> [];
|
|
|
|
/// <inheritdoc />
|
|
public bool IsAlternateDataStream(string path)
|
|
=> false;
|
|
|
|
/// <inheritdoc />
|
|
public string GetAlternateDataStreamParent(string path)
|
|
=> path;
|
|
}
|
|
}
|
|
|