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Merged
Dongbo Wang (daxian-dbw) merged 1 commit into from
Sep 11, 2026
+128 −39
Merged

Improve CAB extraction path handling #28009

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159 changes: 124 additions & 35 deletions src/System.Management.Automation/help/CabinetNativeApi.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -354,65 +354,154 @@ internal static int FdiSeek(IntPtr fp, int offset, int origin)
[UnmanagedFunctionPointer(CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
internal delegate IntPtr FdiNotifyDelegate(FdiNotificationType fdint, FdiNotification fdin);

/// <summary>
/// Validates that the extraction path is within the intended help directory.
/// Ensures proper handling of absolute paths, UNC paths, and relative path components.
/// </summary>
/// <param name="helpDirectory">The intended help directory for extraction.</param>
/// <param name="entryPath">The path from the CAB entry.</param>
/// <returns>The validated absolute file path.</returns>
/// <exception cref="InvalidOperationException">Thrown when path validation fails.</exception>
private static string ValidateExtractionPath(string helpDirectory, string entryPath)
{
// Reject absolute paths, UNC paths, or rooted paths in CAB entries
if (Path.IsPathRooted(entryPath))
{
throw new InvalidOperationException(
$"CAB entry contains an invalid rooted path: {entryPath}");
}

// Reject paths containing a colon to block Windows Alternate Data Streams (e.g. "file.txt:payload").
// Path.IsPathRooted and Path.GetFullPath do not reject these on .NET Core.
if (entryPath.Contains(':'))
{
throw new InvalidOperationException(
$"CAB entry contains an invalid path with a colon: {entryPath}");
}

// Get the canonical (absolute) help directory path with trailing separator
// The trailing separator is needed to prevent false positive matches where a directory
// name is a prefix of another (e.g., "/path/help" matching "/path/help-backup/file.txt")
string canonicalHelpDir = Path.GetFullPath(helpDirectory);
if (!canonicalHelpDir.EndsWith(Path.DirectorySeparatorChar.ToString()))

@iSazonov Ilya (iSazonov) Sep 14, 2026

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We have no need to use ToString().
Also now there is Path.EndsInDirectorySeparator() method.

Suggested change
if (!canonicalHelpDir.EndsWith(Path.DirectorySeparatorChar.ToString()))
if (!Path.EndsInDirectorySeparator(canonicalHelpDir))

{
canonicalHelpDir += Path.DirectorySeparatorChar;
}

// Combine and resolve the full extraction path
string candidatePath = Path.Combine(helpDirectory, entryPath);
string resolvedPath = Path.GetFullPath(candidatePath);

// Ensure resolved path starts with the canonical help directory.
// OrdinalIgnoreCase is intentional: NTFS on Windows is case-insensitive, so two paths that
// differ only in case refer to the same file and must be treated as equivalent here.
if (!resolvedPath.StartsWith(canonicalHelpDir, StringComparison.OrdinalIgnoreCase))
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{
throw new InvalidOperationException(
$"CAB entry path is invalid. Entry '{entryPath}' would extract to '{resolvedPath}' which is outside the intended directory '{canonicalHelpDir}'");
}

return resolvedPath;
}

// Handles FDI notification
internal static IntPtr FdiNotify(FdiNotificationType fdint, FdiNotification fdin)
{
switch (fdint)
{
case FdiNotificationType.FdintCOPY_FILE:
{
// TODO: Should I catch exceptions for the new functions?

// Copy target directory
string destPath = Marshal.PtrToStringAnsi(fdin.pv);
// Get the intended help directory
string helpDirectory = Marshal.PtrToStringAnsi(fdin.pv);
string absoluteFilePath;

// Split the path to a filename and path
string fileName = Path.GetFileName(fdin.psz1);
string remainingPsz1Path = Path.GetDirectoryName(fdin.psz1);
destPath = Path.Combine(destPath, remainingPsz1Path);

Directory.CreateDirectory(destPath); // Creates all intermediate directories if necessary.
try
{
// fdin.psz1 should contain a relative path from the CAB entry
absoluteFilePath = ValidateExtractionPath(helpDirectory, fdin.psz1);
// Create all intermediate directories if necessary
string directoryPath = Path.GetDirectoryName(absoluteFilePath);
Directory.CreateDirectory(directoryPath);
}
catch (Exception e) when (e is InvalidOperationException ||
e is ArgumentNullException ||
e is ArgumentException ||
e is NotSupportedException ||
e is PathTooLongException ||
e is System.Security.SecurityException ||
e is IOException ||
e is UnauthorizedAccessException)
{
// Path validation failed or directory could not be created - reject this CAB entry
return new IntPtr(-1);
}

// Create the file
string absoluteFilePath = Path.Combine(destPath, fileName);
return CabinetNativeApi.FdiOpen(absoluteFilePath, (int)OpFlags.Create, (int)(PermissionMode.Read | PermissionMode.Write)); // TODO: OK to ignore _O_SEQUENTIAL, WrOnly, and _O_BINARY?
// Note: OpFlags.Create and PermissionMode.Read|Write are sufficient for CAB extraction.
// The cabinet.dll API doesn't require _O_SEQUENTIAL, _O_WRONLY, or _O_BINARY flags.
return CabinetNativeApi.FdiOpen(absoluteFilePath, (int)OpFlags.Create, (int)(PermissionMode.Read | PermissionMode.Write));
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}
case FdiNotificationType.FdintCLOSE_FILE_INFO:
{
// Close the file
CabinetNativeApi.FdiClose(fdin.hf);

// Set the file attributes
string destPath = Marshal.PtrToStringAnsi(fdin.pv);
string absoluteFilePath = Path.Combine(destPath, fdin.psz1);
// Get the intended help directory
string helpDirectory = Marshal.PtrToStringAnsi(fdin.pv);
string absoluteFilePath;

IntPtr hFile = PlatformInvokes.CreateFile(
absoluteFilePath,
PlatformInvokes.FileDesiredAccess.GenericRead | PlatformInvokes.FileDesiredAccess.GenericWrite,
PlatformInvokes.FileShareMode.Read,
IntPtr.Zero,
PlatformInvokes.FileCreationDisposition.OpenExisting,
PlatformInvokes.FileAttributes.Normal,
IntPtr.Zero);
try
{
absoluteFilePath = ValidateExtractionPath(helpDirectory, fdin.psz1);
}
catch (Exception e) when (e is InvalidOperationException ||
e is ArgumentNullException ||
e is ArgumentException ||
e is NotSupportedException ||
e is PathTooLongException ||
e is System.Security.SecurityException)
{
// Path validation failed - reject this CAB entry
return new IntPtr(0);
}

if (hFile != IntPtr.Zero)
try
{
PlatformInvokes.FILETIME ftFile = new PlatformInvokes.FILETIME();
if (PlatformInvokes.DosDateTimeToFileTime(fdin.date, fdin.time, ftFile))
// Set the file attributes
IntPtr hFile = PlatformInvokes.CreateFile(
absoluteFilePath,
PlatformInvokes.FileDesiredAccess.GenericRead | PlatformInvokes.FileDesiredAccess.GenericWrite,
PlatformInvokes.FileShareMode.Read,
IntPtr.Zero,
PlatformInvokes.FileCreationDisposition.OpenExisting,
PlatformInvokes.FileAttributes.Normal,
IntPtr.Zero);

if (hFile != IntPtr.Zero)
{
PlatformInvokes.FILETIME ftLocal = new PlatformInvokes.FILETIME();
if (PlatformInvokes.LocalFileTimeToFileTime(ftFile, ftLocal))
PlatformInvokes.FILETIME ftFile = new PlatformInvokes.FILETIME();
if (PlatformInvokes.DosDateTimeToFileTime(fdin.date, fdin.time, ftFile))
{
PlatformInvokes.SetFileTime(hFile, ftLocal, null, ftLocal);
PlatformInvokes.FILETIME ftLocal = new PlatformInvokes.FILETIME();
if (PlatformInvokes.LocalFileTimeToFileTime(ftFile, ftLocal))
{
PlatformInvokes.SetFileTime(hFile, ftLocal, null, ftLocal);
}
}

PlatformInvokes.CloseHandle(hFile);
}

PlatformInvokes.CloseHandle(hFile);
}
PlatformInvokes.SetFileAttributesW(
absoluteFilePath,
(PlatformInvokes.FileAttributes)fdin.attribs & (PlatformInvokes.FileAttributes.ReadOnly | PlatformInvokes.FileAttributes.Hidden | PlatformInvokes.FileAttributes.System | PlatformInvokes.FileAttributes.Archive));

PlatformInvokes.SetFileAttributesW(
absoluteFilePath,
(PlatformInvokes.FileAttributes)fdin.attribs & (PlatformInvokes.FileAttributes.ReadOnly | PlatformInvokes.FileAttributes.Hidden | PlatformInvokes.FileAttributes.System | PlatformInvokes.FileAttributes.Archive));
}
catch (Exception e) when (e is IOException ||
e is UnauthorizedAccessException ||
e is System.Security.SecurityException)
{
return new IntPtr(0);
}

// Call notification function
return new IntPtr(1);
Expand Down
8 changes: 4 additions & 4 deletions test/powershell/Modules/Microsoft.PowerShell.Utility/Debug-Runspace.Tests.ps1
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Original file line number Diff line number Diff line change
Expand Up @@ -31,10 +31,10 @@ Describe "Debug-Runspace" -Tag "CI" {
$rs1.Debugger.SetDebugMode("None")
{ Debug-Runspace -Runspace $rs1 -ErrorAction stop } | Should -Throw -ErrorId "InvalidOperation,Microsoft.PowerShell.Commands.DebugRunspaceCommand"
}

It "Should write attach event and mark runspace as having a remote debugger attached" {
$onAttachName = [System.Management.Automation.PSEngineEvent]::OnDebugAttach

$debugTarget = [PowerShell]::Create()
$null = $debugTarget.AddCommand('Wait-Event').AddParameter('SourceIdentifier', $onAttachName)
$waitTask = $debugTarget.BeginInvoke()
Expand All @@ -44,8 +44,8 @@ Describe "Debug-Runspace" -Tag "CI" {
$debugger = [PowerShell]::Create()
$null = $debugger.AddCommand('Debug-Runspace').AddParameter('Id', $debugTarget.Runspace.Id)
$debugTask = $debugger.BeginInvoke()
$waitTask.AsyncWaitHandle.WaitOne(5000) | Should -BeTrue

$waitTask.AsyncWaitHandle.WaitOne(10000) | Should -BeTrue
$waitInfo = $debugTarget.EndInvoke($waitTask)
$waitInfo.SourceIdentifier | Should -Be $onAttachName

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