From 007db8bd94b2dd4ded9ceeb8a248ea2ba8d5ab06 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 2 Nov 2020 12:07:05 +0100
Subject: [PATCH] api: serialize driver installation

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 api/adapter.c   | 18 +++++++++++++-----
 api/namespace.c | 26 +++++++++++++++++++++++++-
 api/namespace.h |  6 +++++-
 3 files changed, 43 insertions(+), 7 deletions(-)

diff --git a/api/adapter.c b/api/adapter.c
index 7db8023..d996d99 100644
--- a/api/adapter.c
+++ b/api/adapter.c
@@ -621,7 +621,7 @@ WintunGetAdapter(_In_z_ const WCHAR *Pool, _In_z_ const WCHAR *Name, _Out_ WINTU
         return LOG(WINTUN_LOG_ERR, L"Failed to impersonate SYSTEM user"), ERROR_ACCESS_DENIED;
 
     DWORD Result;
-    HANDLE Mutex = NamespaceTakeMutex(Pool);
+    HANDLE Mutex = NamespaceTakePoolMutex(Pool);
     if (!Mutex)
     {
         Result = ERROR_INVALID_HANDLE;
@@ -1029,7 +1029,7 @@ CreateAdapter(
     LOG(WINTUN_LOG_INFO, L"Creating adapter");
 
     DWORD Result;
-    HANDLE Mutex = NamespaceTakeMutex(Pool);
+    HANDLE Mutex = NamespaceTakePoolMutex(Pool);
     if (!Mutex)
         return ERROR_INVALID_HANDLE;
 
@@ -1428,10 +1428,16 @@ static BOOL EnsureWintunUnloaded(VOID)
 static WINTUN_STATUS
 InstallDriver(_Out_writes_z_(MAX_PATH) WCHAR InfStorePath[MAX_PATH], _Inout_ BOOL *RebootRequired)
 {
+    HANDLE DriverInstallationLock = NamespaceTakeDriverInstallationMutex();
+    if (!DriverInstallationLock)
+        return LOG_LAST_ERROR(L"Failed to take driver installation mutex");
     DWORD Result;
     WCHAR RandomTempSubDirectory[MAX_PATH];
     if ((Result = CreateTemporaryDirectory(RandomTempSubDirectory)) != ERROR_SUCCESS)
-        return LOG(WINTUN_LOG_ERR, L"Failed to create temporary folder"), Result;
+    {
+        LOG(WINTUN_LOG_ERR, L"Failed to create temporary folder");
+        goto cleanupDriverInstallationLock;
+    }
 
     WCHAR CatPath[MAX_PATH] = { 0 };
     WCHAR SysPath[MAX_PATH] = { 0 };
@@ -1518,6 +1524,8 @@ cleanupDelete:
     DeleteFileW(InfPath);
 cleanupDirectory:
     RemoveDirectoryW(RandomTempSubDirectory);
+cleanupDriverInstallationLock:
+    NamespaceReleaseMutex(DriverInstallationLock);
     return Result;
 }
 
@@ -1730,7 +1738,7 @@ cleanupDirectory:
 static WINTUN_STATUS
 GetAdapter(_In_z_ const WCHAR *Pool, _In_ const GUID *CfgInstanceID, _Out_ WINTUN_ADAPTER **Adapter)
 {
-    HANDLE Mutex = NamespaceTakeMutex(Pool);
+    HANDLE Mutex = NamespaceTakePoolMutex(Pool);
     if (!Mutex)
         return ERROR_INVALID_HANDLE;
     HDEVINFO DevInfo;
@@ -1940,7 +1948,7 @@ cleanupToken:
 WINTUN_STATUS WINAPI
 WintunEnumAdapters(_In_z_ const WCHAR *Pool, _In_ WINTUN_ENUM_CALLBACK_FUNC Func, _In_ LPARAM Param)
 {
-    HANDLE Mutex = NamespaceTakeMutex(Pool);
+    HANDLE Mutex = NamespaceTakePoolMutex(Pool);
     if (!Mutex)
         return ERROR_INVALID_HANDLE;
     DWORD Result = ERROR_SUCCESS;
diff --git a/api/namespace.c b/api/namespace.c
index 9258b53..7f6959b 100644
--- a/api/namespace.c
+++ b/api/namespace.c
@@ -102,7 +102,7 @@ cleanupLeaveCriticalSection:
 
 _Check_return_
 HANDLE
-NamespaceTakeMutex(_In_z_ const WCHAR *Pool)
+NamespaceTakePoolMutex(_In_z_ const WCHAR *Pool)
 {
     HANDLE Mutex = NULL;
 
@@ -147,6 +147,30 @@ cleanupSha256:
     return Mutex;
 }
 
+_Check_return_
+HANDLE
+NamespaceTakeDriverInstallationMutex(void)
+{
+    HANDLE Mutex = NULL;
+
+    if (NamespaceRuntimeInit() != ERROR_SUCCESS)
+        return NULL;
+    Mutex = CreateMutexW(&SecurityAttributes, FALSE, L"Wintun\\Wintun-Driver-Installation-Mutex");
+    if (!Mutex)
+        return NULL;
+    switch (WaitForSingleObject(Mutex, INFINITE))
+    {
+    case WAIT_OBJECT_0:
+    case WAIT_ABANDONED:
+        goto out;
+    }
+
+    CloseHandle(Mutex);
+    Mutex = NULL;
+out:
+    return Mutex;
+}
+
 void
 NamespaceReleaseMutex(_In_ HANDLE Mutex)
 {
diff --git a/api/namespace.h b/api/namespace.h
index 753068d..0f2598a 100644
--- a/api/namespace.h
+++ b/api/namespace.h
@@ -9,7 +9,11 @@
 
 _Check_return_
 HANDLE
-NamespaceTakeMutex(_In_z_ const WCHAR *Pool);
+NamespaceTakePoolMutex(_In_z_ const WCHAR *Pool);
+
+_Check_return_
+HANDLE
+NamespaceTakeDriverInstallationMutex(void);
 
 void
 NamespaceReleaseMutex(_In_ HANDLE Mutex);