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Merged
jkotas merged 2 commits into from
Oct 17, 2026
Merged

Fix Unix mutex directory validation and default-scope test expectations #135898

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Copilot Oct 15, 2026
8a044cd
Fix Unix mutex directory compatibility and default-scope tests
Copilot Oct 15, 2026
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12 changes: 0 additions & 12 deletions src/libraries/System.Private.CoreLib/src/Resources/Strings.resx
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Original file line number Diff line number Diff line change
Expand Up @@ -4459,18 +4459,6 @@
<data name="IO_SharedMemory_PathExistsButNotDirectory" xml:space="preserve">
<value>The path '{0}' exists but is not a directory.</value>
</data>
<data name="IO_SharedMemory_DirectoryPermissionsIncorrect" xml:space="preserve">
<value>The directory '{0}' does not have the expected owner or permissions for system scope: {1}, {2}.</value>
</data>
<data name="IO_SharedMemory_DirectoryNotOwnedByUid" xml:space="preserve">
<value>The directory '{0}' is not owned by the current user with UID {1}.</value>
</data>
<data name="IO_SharedMemory_DirectoryPermissionsIncorrectUserScope" xml:space="preserve">
<value>The directory '{0}' does not have the expected permissions for user scope: {1}.</value>
</data>
<data name="IO_SharedMemory_DirectoryOwnerPermissionsIncorrect" xml:space="preserve">
<value>The directory '{0}' does not have the expected owner permissions: {1}.</value>
</data>
<data name="Argument_MustBeFunctionPointer" xml:space="preserve">
<value>Argument must represent a function pointer type.</value>
</data>
Expand Down
106 changes: 2 additions & 104 deletions src/libraries/System.Private.CoreLib/src/System/IO/SharedMemoryManager.Unix.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -372,10 +372,8 @@ internal static class SharedMemoryHelpers
{
private const UnixFileMode PermissionsMask_OwnerUser_ReadWrite = UnixFileMode.UserRead | UnixFileMode.UserWrite;
private const UnixFileMode PermissionsMask_OwnerUser_ReadWriteExecute = PermissionsMask_OwnerUser_ReadWrite | UnixFileMode.UserExecute;
private const UnixFileMode PermissionsMask_NonOwnerUsers_Write = UnixFileMode.GroupWrite | UnixFileMode.OtherWrite;
private const UnixFileMode PermissionsMask_AllUsers_ReadWrite = UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.GroupRead | UnixFileMode.GroupWrite | UnixFileMode.OtherRead | UnixFileMode.OtherWrite;
private const UnixFileMode PermissionsMask_AllUsers_ReadWriteExecute = PermissionsMask_AllUsers_ReadWrite | UnixFileMode.UserExecute | UnixFileMode.GroupExecute | UnixFileMode.OtherExecute;
private const UnixFileMode PermissionsMask_Sticky = UnixFileMode.StickyBit;

private const int TransientRetryCount = 10;

Expand Down Expand Up @@ -499,45 +497,7 @@ public static SafeFileHandle OpenSharedFilesSystemDirectory(SharedMemoryId id)

if (!directoryHandle.IsInvalid)
{
if (Interop.Sys.FStat(directoryHandle, out Interop.Sys.FileStatus fileStatus) != 0)
{
Interop.ErrorInfo fstatError = Interop.Sys.GetLastErrorInfo();
directoryHandle.Dispose();
if ((fstatError.Error == Interop.Error.ENOENT || fstatError.Error == Interop.Error.EACCES) &&
RetryOnTransientPermissionFailure(ref transientRetryCount))
{
continue;
}

throw Interop.GetExceptionForIoErrno(fstatError, directoryPath);
}

// For system directories (such as TEMP_DIRECTORY_PATH), require sufficient permissions only for the
// owner user. For instance, "docker run --mount ..." to mount /tmp to some directory on the host mounts the
// destination directory with the same permissions as the source directory, which may not include some permissions for
// other users. In the docker container, other user permissions are typically not relevant and relaxing the permissions
// requirement allows for that scenario to work without having to work around it by first giving sufficient permissions
// for all users.
//
// If the directory is being used for user-scoped shared memory data, also ensure that either it has the sticky bit or
// it's owned by the current user and without write access for other users.
if ((fileStatus.Mode & (int)PermissionsMask_OwnerUser_ReadWriteExecute) == (int)PermissionsMask_OwnerUser_ReadWriteExecute
&& (
!id.IsUserScope ||
(fileStatus.Mode & (int)PermissionsMask_Sticky) == (int)PermissionsMask_Sticky ||
(fileStatus.Uid == id.Uid && (fileStatus.Mode & (int)PermissionsMask_NonOwnerUsers_Write) == 0)
))
{
return directoryHandle;
}

directoryHandle.Dispose();
if (RetryOnTransientPermissionFailure(ref transientRetryCount))
{
continue;
}

throw new IOException(SR.Format(SR.IO_SharedMemory_DirectoryPermissionsIncorrect, directoryPath, fileStatus.Uid, Convert.ToString(fileStatus.Mode, 8)));
return directoryHandle;
}

Interop.ErrorInfo error = Interop.Sys.GetLastErrorInfo();
Expand Down Expand Up @@ -781,72 +741,10 @@ internal static SafeFileHandle EnsureDirectoryExists(
throw Interop.GetExceptionForIoErrno(openError, directoryPathForError);
}

if (ValidateDirectory(directoryHandle, directoryPathForError, id, ref transientRetryCount))
{
return directoryHandle;
}

directoryHandle.Dispose();
return directoryHandle;
}
}

private static bool ValidateDirectory(
SafeFileHandle directoryHandle,
string directoryPathForError,
SharedMemoryId id,
ref int transientRetryCount)
{
if (Interop.Sys.FStat(directoryHandle, out Interop.Sys.FileStatus fileStatus) != 0)
{
Interop.ErrorInfo error = Interop.Sys.GetLastErrorInfo();
if ((error.Error == Interop.Error.ENOENT || error.Error == Interop.Error.EACCES) &&
RetryOnTransientPermissionFailure(ref transientRetryCount))
{
return false;
}

throw Interop.GetExceptionForIoErrno(error, directoryPathForError);
}

UnixFileMode permissionsMask = id.IsUserScope
? PermissionsMask_OwnerUser_ReadWriteExecute
: PermissionsMask_AllUsers_ReadWriteExecute;

// For non-system directories (such as SharedFilesPath/UserUnscopedRuntimeTempDirectoryName),
// require the sufficient permissions, so that shared memory files may be shared according to its scope.

// For user-scoped directories, verify the owner UID.
if (id.IsUserScope && fileStatus.Uid != id.Uid)
{
if (RetryOnTransientPermissionFailure(ref transientRetryCount))
{
return false;
}

throw new IOException(SR.Format(SR.IO_SharedMemory_DirectoryNotOwnedByUid, directoryPathForError, id.Uid));
}

// Verify the permissions correct.
if ((fileStatus.Mode & (int)permissionsMask) == (int)permissionsMask)
{
return true;
}

if (RetryOnTransientPermissionFailure(ref transientRetryCount))
{
return false;
}

// We were not able to verify the necessary permissions.
// Throw an exception with a message that is specific to the scope of the shared memory data.
if (id.IsUserScope)
{
throw new IOException(SR.Format(SR.IO_SharedMemory_DirectoryPermissionsIncorrectUserScope, directoryPathForError, Convert.ToString(fileStatus.Mode, 8)));
}

throw new IOException(SR.Format(SR.IO_SharedMemory_DirectoryOwnerPermissionsIncorrect, directoryPathForError, Convert.ToString(fileStatus.Mode, 8)));
}

private static bool RetryOnTransientPermissionFailure(ref int transientRetryCount)
{
if (transientRetryCount >= TransientRetryCount)
Expand Down
56 changes: 52 additions & 4 deletions src/libraries/System.Threading/tests/MutexTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -394,6 +394,7 @@ public void NameOptionsApiCompatibilityTest(string namePrefix)
string name = Guid.NewGuid().ToString("N");
string prefixedName = namePrefix + name;
bool currentSessionOnly = namePrefix != @"Global\";
bool currentUserOnly = !PlatformDetection.IsWindows;

using (var m = new Mutex(initiallyOwned: false, prefixedName, out bool createdNew))
{
Expand All @@ -402,18 +403,18 @@ public void NameOptionsApiCompatibilityTest(string namePrefix)
new Mutex(
initiallyOwned: false,
name,
new() { CurrentUserOnly = false, CurrentSessionOnly = currentSessionOnly },
new() { CurrentUserOnly = currentUserOnly, CurrentSessionOnly = currentSessionOnly },
out createdNew).Dispose();
Assert.False(createdNew);

Mutex.OpenExisting(
name,
new() { CurrentUserOnly = false, CurrentSessionOnly = currentSessionOnly }).Dispose();
new() { CurrentUserOnly = currentUserOnly, CurrentSessionOnly = currentSessionOnly }).Dispose();

Assert.True(
Mutex.TryOpenExisting(
name,
new() { CurrentUserOnly = false, CurrentSessionOnly = currentSessionOnly },
new() { CurrentUserOnly = currentUserOnly, CurrentSessionOnly = currentSessionOnly },
out Mutex m2));
m2.Dispose();
}
Expand All @@ -422,7 +423,7 @@ public void NameOptionsApiCompatibilityTest(string namePrefix)
new Mutex(
initiallyOwned: false,
name,
new() { CurrentUserOnly = false, CurrentSessionOnly = currentSessionOnly },
new() { CurrentUserOnly = currentUserOnly, CurrentSessionOnly = currentSessionOnly },
out bool createdNew))
{
Assert.True(createdNew);
Expand Down Expand Up @@ -1100,6 +1101,53 @@ public void NamedMutex_OtherEvent_NotCompatible()
| UnixFileMode.UserWrite
| UnixFileMode.UserExecute;

[ConditionalTheory(nameof(IsRemoteExecutorAndCrossProcessNamedMutexSupported))]
[InlineData(OwnerUserRwx)]
[InlineData(AllUsersRwx)]
[PlatformSpecific(TestPlatforms.Linux)]
[UnsupportedOSPlatform("windows")]
public void NamedMutex_ExistingSharedMemoryDirectories_PermissionsAreUnchanged(UnixFileMode directoryMode)
{
string userRuntimeDirectory = GetTestFilePath();
Directory.CreateDirectory(userRuntimeDirectory);

RemoteInvokeOptions remoteInvokeOptions = new();
remoteInvokeOptions.StartInfo.EnvironmentVariables["XDG_RUNTIME_DIR"] = userRuntimeDirectory;

RemoteExecutor.Invoke(
(userRuntimeDirectory, mode) =>
{
UnixFileMode directoryMode = Enum.Parse<UnixFileMode>(mode);
string[] directories =
{
userRuntimeDirectory,
Path.Combine(userRuntimeDirectory, ".dotnet"),
Path.Combine(userRuntimeDirectory, ".dotnet", "shm"),
Path.Combine(userRuntimeDirectory, ".dotnet", "shm", "global")
};
foreach (string directory in directories)
{
Directory.CreateDirectory(directory);
File.SetUnixFileMode(directory, directoryMode);
}

string name = $"Global\\{Guid.NewGuid():N}";
using Mutex mutex = new(false, name, out bool createdNew);
Assert.True(createdNew);
using Mutex openedMutex = Mutex.OpenExisting(name);
Assert.True(Mutex.TryOpenExisting(name, out Mutex existingMutex));
existingMutex.Dispose();

foreach (string directory in directories)
{
Assert.Equal(directoryMode, File.GetUnixFileMode(directory));
}
},
userRuntimeDirectory,
directoryMode.ToString(),
remoteInvokeOptions).Dispose();
}

[ConditionalTheory(nameof(IsRemoteExecutorAndCrossProcessNamedMutexSupported))]
[InlineData(null)]
[InlineData(false)]
Expand Down
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