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[idd] helper: run interactive process as desktop user

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Explorer file copies were invisible to the Helper because the service
launched its child with a duplicate of the LocalSystem token and changed
only TokenSessionId. The child therefore remained a System-integrity
process. Windows filtered Explorer's file clipboard formats across that
integrity boundary. Basic text and bitmap formats continued to work.

Keep only the SCM service privileged. Obtain the active session user's
primary token with WTSQueryUserToken. For elevated accounts, prefer the
linked limited token. Validate its session and security properties.
Build the user environment and launch the interactive Helper on
WinSta0\Default. Gate Helper activation until the service has rechecked
the active session and registered the clipboard authority.

Use random lifetime, stop, and activation objects owned by the service.
Give the target logon SID synchronization access only. Recheck the
active console session and service state before activation. Make the
lifetime mutex terminate the Helper if the service exits unexpectedly.
Restart it when the active session, IDD host, or authority changes.

Replace the old process-handle mapping transfer with a device-bound
authority protocol on the LGIdd device interface. The service verifies
the exact driver host instance, duplicates only section map rights into
that process, and registers the session, mapping identifier, and handle.
Bind authority lifetime to its WDF file object, revoke it synchronously
on cleanup, and poll the driver host identity while the child is active.

Restrict the device stack to SYSTEM and isolate LGIdd in a unique UMDF
device group. Restrict the shared section to SYSTEM and the target logon
SID. Apply a medium mandatory label that prevents low-integrity readers
and writers. Map it with read/write rights instead of all access.

Give each clipboard mapping a second random authority identifier. Store
it only inside the logon-SID-protected mapping and send it in the
mandatory HELLO. LGIdd matches it against the service-injected mapping.
This authenticates the user Helper without the unsupported UMDF call to
GetNamedPipeClientSessionId. Have the Helper verify that its pipe server
is in session zero.

Extend the pipe endpoint with bounded authentication reads, cancellable
overlapped I/O, periodic authorization checks, and explicit disconnects.
Serialize authority changes with clipboard attach and detach. Prevent
stale cleanup from tearing down a replacement mapping. Disconnect the
user pipe immediately when its owning authority is revoked.

Run clipboard, OLE, display, configuration, and file access in the
user's interactive process. Retain its process token for worker-thread
file operations instead of querying and impersonating the desktop user
from a System process. Store Helper logs in LocalAppData and grant only
the registry rights needed by interactive configuration and UMDF.

Keep immediate, stage-specific Win32 and HRESULT diagnostics throughout
clipboard capture. Probe CF_HDROP while holding the Win32 clipboard and
enumerate the OLE object's advertised file formats. Validate returned
storage and fall back to Shell item paths when direct retrieval fails.
Validate clipboard sequence changes and defer retries during contention
without publishing incomplete clipboard state.

Complete the 1 MiB transfer work with full-sized Windows copy buffers.
Use full-sized FUSE reads and retain the named 64 KiB X11 chunk limit.
Validate the user-writable mapping with CClipboardRing before attaching.

The pipe, mapping, and authority protocols change together. LGIdd.dll,
the INF, and LGIddHelper.exe must be rebuilt and installed as one
matching set.
This commit is contained in:
Geoffrey McRae
2026-08-15 00:11:01 +10:00
parent e40dc19c7e
commit f9ffce528a
35 changed files with 2803 additions and 665 deletions
Download Patch File Download Diff File Expand all files Collapse all files

251
idd/LGIddHelper/CPipeClient.cpp
View File

@@ -391,6 +391,12 @@ bool CPipeClient::Init()
return false;
}
{
CSRWExclusiveLock lock(m_clipboardSetupLock);
if (!PrepareClipboardMappingLocked())
return false;
}
m_endpoint.SetHandler(this);
return m_endpoint.Start(
LG_PIPE_NAME,
@@ -477,6 +483,44 @@ void CPipeClient::WriteMsg(const LGPipeMsg& msg)
m_endpoint.Send(&msg, sizeof(msg));
}
bool CPipeClient::PipeServerIsAuthorized(HANDLE pipe)
{
DWORD session = 0xFFFFFFFFU;
if (!GetNamedPipeServerSessionId(pipe, &session))
{
const DWORD error = GetLastError();
DEBUG_WARN_HR(error, "Failed to identify named pipe server session");
return false;
}
if (session != 0)
{
DEBUG_WARN(
"Rejected named pipe server outside the service session");
return false;
}
return true;
}
bool CPipeClient::BuildPipeClientHello(void * message, size_t size)
{
CSRWSharedLock setupLock(m_clipboardSetupLock);
if (!message || size != sizeof(LGPipeMsg) ||
!m_clipboardMapping || !m_clipboardEpoch)
{
DEBUG_ERROR("Clipboard mapping was not prepared before pipe connection");
return false;
}
LGPipeMsg& hello = *static_cast<LGPipeMsg *>(message);
hello = {};
hello.size = sizeof(hello);
hello.type = LGPipeMsg::HELLO;
hello.hello.version = LGPipeMsg::PROTOCOL_VERSION;
hello.hello.authorityId[0] = m_clipboardAuthorityId[0];
hello.hello.authorityId[1] = m_clipboardAuthorityId[1];
return true;
}
void CPipeClient::OnPipeConnected()
{
bool hasStatus;
@@ -489,82 +533,6 @@ void CPipeClient::OnPipeConnected()
if (hasStatus)
WriteMsg(status);
if (!m_clipboardEnabled)
return;
CSRWExclusiveLock setupLock(m_clipboardSetupLock);
ResetClipboardSetupLocked();
LARGE_INTEGER size = {};
size.QuadPart = sizeof(ClipboardMapping);
m_clipboardMapping = CreateFileMappingW(INVALID_HANDLE_VALUE, nullptr,
PAGE_READWRITE, size.HighPart, size.LowPart, nullptr);
if (!m_clipboardMapping)
{
DEBUG_ERROR_HR(GetLastError(),
"Failed to create the clipboard mapping");
return;
}
ClipboardMapping * view = static_cast<ClipboardMapping *>(MapViewOfFile(
m_clipboardMapping, FILE_MAP_ALL_ACCESS, 0, 0,
sizeof(ClipboardMapping)));
if (!view)
{
DEBUG_ERROR_HR(GetLastError(),
"Failed to initialize the clipboard mapping");
ResetClipboardSetupLocked();
return;
}
++m_clipboardEpochCounter;
if (!m_clipboardEpochCounter)
++m_clipboardEpochCounter;
m_clipboardEpoch = m_clipboardEpochCounter;
CClipboardRing::Initialize(*view, m_clipboardEpoch);
UnmapViewOfFile(view);
DWORD serverPid = 0;
if (!GetNamedPipeServerProcessId(m_endpoint.NativeHandle(), &serverPid))
{
DEBUG_ERROR_HR(GetLastError(),
"Failed to identify the clipboard mapping target");
ResetClipboardSetupLocked();
return;
}
HANDLE target = OpenProcess(PROCESS_DUP_HANDLE, FALSE, serverPid);
HANDLE remote = nullptr;
if (!target || !DuplicateHandle(GetCurrentProcess(),
m_clipboardMapping, target, &remote, 0, FALSE,
DUPLICATE_SAME_ACCESS))
{
DEBUG_ERROR_HR(GetLastError(),
"Failed to share the clipboard mapping with the IDD");
if (target)
CloseHandle(target);
ResetClipboardSetupLocked();
return;
}
LGPipeMsg setup = {};
setup.size = sizeof(setup);
setup.type = LGPipeMsg::CLIPBOARD_SETUP;
setup.clipboardSetup.handle =
static_cast<uint64_t>(reinterpret_cast<uintptr_t>(remote));
setup.clipboardSetup.bytes = sizeof(ClipboardMapping);
const bool sent = m_endpoint.Send(&setup, sizeof(setup));
if (!sent)
{
DEBUG_WARN("Failed to send clipboard mapping setup");
HANDLE reclaimed = nullptr;
if (DuplicateHandle(target, remote, GetCurrentProcess(), &reclaimed,
0, FALSE, DUPLICATE_SAME_ACCESS | DUPLICATE_CLOSE_SOURCE))
CloseHandle(reclaimed);
ResetClipboardSetupLocked();
}
CloseHandle(target);
}
void CPipeClient::OnPipeDisconnected()
@@ -589,6 +557,12 @@ bool CPipeClient::ShouldReconnect()
const bool attached = IsLGIddDeviceAttached();
if (!attached)
DEBUG_INFO("Looking Glass Indirect Display Device was removed");
else
{
CSRWExclusiveLock lock(m_clipboardSetupLock);
if (!m_clipboardMapping && !PrepareClipboardMappingLocked())
DEBUG_WARN("Clipboard mapping is not ready for reconnection");
}
return attached;
}
@@ -840,13 +814,46 @@ bool CPipeClient::OnPipeMessage(const void * message, size_t size)
return true;
}
HANDLE mapping = nullptr;
if (!m_clipboardMapping ||
!DuplicateHandle(GetCurrentProcess(), m_clipboardMapping,
GetCurrentProcess(), &mapping, 0, FALSE, DUPLICATE_SAME_ACCESS) ||
!m_clipboard.Attach(mapping, m_clipboardEpoch, true, *this))
if (!m_clipboardEnabled)
{
const uint64_t epoch = m_clipboardEpoch;
ResetClipboardSetupLocked();
setupLock.Unlock();
LGPipeMsg failure = {};
failure.size = sizeof(failure);
failure.type = LGPipeMsg::CLIPBOARD_READY;
failure.clipboardReady.epoch = epoch;
failure.clipboardReady.status = ERROR_NOT_SUPPORTED;
m_endpoint.Send(&failure, sizeof(failure));
return true;
}
HANDLE mapping = nullptr;
DWORD failureStatus = ERROR_SUCCESS;
if (!m_clipboardMapping)
{
failureStatus = ERROR_NOT_READY;
DEBUG_ERROR_HR(failureStatus,
"Service-owned clipboard mapping is unavailable");
}
else if (!DuplicateHandle(GetCurrentProcess(), m_clipboardMapping,
GetCurrentProcess(), &mapping, 0, FALSE, DUPLICATE_SAME_ACCESS))
{
failureStatus = GetLastError();
DEBUG_ERROR_HR(failureStatus,
"Failed to duplicate the service-owned clipboard mapping");
}
else if (!m_clipboard.Attach(
mapping, m_clipboardEpoch, true, *this))
{
failureStatus = ERROR_INVALID_DATA;
DEBUG_ERROR_HR(failureStatus,
"Failed to activate the service-owned clipboard mapping");
}
if (failureStatus != ERROR_SUCCESS)
{
DEBUG_ERROR("Failed to activate the clipboard mapping");
const uint64_t epoch = m_clipboardEpoch;
ResetClipboardSetupLocked();
setupLock.Unlock();
@@ -857,7 +864,7 @@ bool CPipeClient::OnPipeMessage(const void * message, size_t size)
failure.size = sizeof(failure);
failure.type = LGPipeMsg::CLIPBOARD_READY;
failure.clipboardReady.epoch = epoch;
failure.clipboardReady.status = ERROR_NOT_READY;
failure.clipboardReady.status = failureStatus;
m_endpoint.Send(&failure, sizeof(failure));
}
return true;
@@ -897,13 +904,87 @@ void CPipeClient::ClipboardResetPeer(uint64_t epoch, uint32_t reason)
m_endpoint.Send(&msg, sizeof(msg));
}
bool CPipeClient::PrepareClipboardMappingLocked()
{
if (m_clipboardMapping)
return true;
if (!m_clipboardMappingId[0] || !m_clipboardMappingId[1])
{
DEBUG_ERROR("Invalid service-owned clipboard mapping identifier");
return false;
}
wchar_t mappingName[128];
const int nameResult = _snwprintf_s(
mappingName, _countof(mappingName), _TRUNCATE,
L"Global\\LookingGlassIDDClipboard-%016llx%016llx",
static_cast<unsigned long long>(m_clipboardMappingId[0]),
static_cast<unsigned long long>(m_clipboardMappingId[1]));
if (nameResult < 0)
{
DEBUG_ERROR_HR(ERROR_INSUFFICIENT_BUFFER,
"Failed to format service-owned clipboard mapping name");
return false;
}
m_clipboardMapping = OpenFileMappingW(
FILE_MAP_READ | FILE_MAP_WRITE, FALSE, mappingName);
if (!m_clipboardMapping)
{
const DWORD error = GetLastError();
DEBUG_ERROR_HR(error,
"Failed to open service-owned clipboard mapping");
return false;
}
ClipboardMapping * view = static_cast<ClipboardMapping *>(MapViewOfFile(
m_clipboardMapping, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0,
sizeof(ClipboardMapping)));
if (!view)
{
const DWORD error = GetLastError();
DEBUG_ERROR_HR(error,
"Failed to initialize service-owned clipboard mapping");
ResetClipboardSetupLocked();
return false;
}
m_clipboardAuthorityId[0] = view->authorityId[0];
m_clipboardAuthorityId[1] = view->authorityId[1];
if (!m_clipboardAuthorityId[0] || !m_clipboardAuthorityId[1])
{
DEBUG_ERROR("Invalid clipboard authority identifier");
UnmapViewOfFile(view);
ResetClipboardSetupLocked();
return false;
}
++m_clipboardEpochCounter;
if (!m_clipboardEpochCounter)
++m_clipboardEpochCounter;
m_clipboardEpoch = m_clipboardEpochCounter;
CClipboardRing::Initialize(
*view, m_clipboardEpoch, m_clipboardAuthorityId);
if (!UnmapViewOfFile(view))
{
const DWORD error = GetLastError();
DEBUG_ERROR_HR(error,
"Failed to unmap initialized service-owned clipboard mapping");
ResetClipboardSetupLocked();
return false;
}
return true;
}
void CPipeClient::ResetClipboardSetupLocked()
{
m_clipboard.Detach();
if (m_clipboardMapping)
CloseHandle(m_clipboardMapping);
m_clipboardMapping = nullptr;
m_clipboardEpoch = 0;
m_clipboardMapping = nullptr;
m_clipboardEpoch = 0;
m_clipboardAuthorityId[0] = 0;
m_clipboardAuthorityId[1] = 0;
}
void CPipeClient::HandleSetCursorPos(const LGPipeMsg& msg)