VeraCrypt
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authorMounir IDRASSI <mounir.idrassi@idrix.fr>2019-10-03 17:30:50 (GMT)
committerMounir IDRASSI <mounir.idrassi@idrix.fr>2019-10-03 17:32:45 (GMT)
commitccda60f82f0dd3ba41c54bf14b4b553a87cac794 (patch)
tree8a5e10e0dc8a77041ef49d5e9195e5a1d5db26eb
parent1298f83aa49948962b57dc302cc868130b60c0b5 (diff)
downloadVeraCrypt-ccda60f82f0dd3ba41c54bf14b4b553a87cac794.zip
VeraCrypt-ccda60f82f0dd3ba41c54bf14b4b553a87cac794.tar.gz
Windows: If Secure Desktop is started and random generator was not initialized before us, then stop random generator after we finish in order to avoid consuming CPU because of periodic fast poll thread. Next time a critical operation that requires RNG is performed, it will be initialized again. We do this because since the addition of secure desktop support, every time secure desktop is displayed, the RNG fast poll thread was started even if the user will never perform any critical operation that requires random bytes.
-rw-r--r--src/Common/Dlgcode.c123
1 files changed, 70 insertions, 53 deletions
diff --git a/src/Common/Dlgcode.c b/src/Common/Dlgcode.c
index 654e29a..08e2499 100644
--- a/src/Common/Dlgcode.c
+++ b/src/Common/Dlgcode.c
@@ -13392,7 +13392,8 @@ BOOL DeleteDirectory (const wchar_t* szDirName)
static BOOL GenerateRandomString (HWND hwndDlg, LPTSTR szName, DWORD maxCharsCount)
{
BOOL bRet = FALSE;
- if (Randinit () != ERR_SUCCESS)
+ int alreadyInitialized = 0;
+ if (RandinitWithCheck (&alreadyInitialized) != ERR_SUCCESS)
{
handleError (hwndDlg, (CryptoAPILastError == ERROR_SUCCESS)? ERR_RAND_INIT_FAILED : ERR_CAPI_INIT_FAILED, SRC_POS);
}
@@ -13416,6 +13417,19 @@ static BOOL GenerateRandomString (HWND hwndDlg, LPTSTR szName, DWORD maxCharsCou
}
burn (indexes, maxCharsCount + 1);
free (indexes);
+
+ /* If RNG was not initialized before us, then stop it in order to
+ * stop the fast poll thread which consumes CPU. Next time a critical operation
+ * that requires RNG is performed, it will be initialized again.
+ *
+ * We do this because since the addition of secure desktop support, every time
+ * secure desktop is displayed, the RNG fast poll thread was started even if the
+ * user will never perform any critical operation that requires random bytes.
+ */
+ if (!alreadyInitialized)
+ {
+ RandStop (FALSE);
+ }
}
return bRet;
@@ -13583,76 +13597,79 @@ INT_PTR SecureDesktopDialogBoxParam(
INT_PTR retValue = 0;
BOOL bEffectiveUseSecureDesktop = bCmdUseSecureDesktopValid? bCmdUseSecureDesktop : bUseSecureDesktop;
- if (bEffectiveUseSecureDesktop && GenerateRandomString (hWndParent, szDesktopName, 64))
+ if (bEffectiveUseSecureDesktop)
{
- map<DWORD, BOOL> ctfmonBeforeList, ctfmonAfterList;
- DWORD desktopAccess = DESKTOP_CREATEMENU | DESKTOP_CREATEWINDOW | DESKTOP_READOBJECTS | DESKTOP_SWITCHDESKTOP | DESKTOP_WRITEOBJECTS;
- HDESK hSecureDesk;
-
- HDESK hInputDesk = NULL;
-
EnterCriticalSection (&csSecureDesktop);
bSecureDesktopOngoing = TRUE;
finally_do ({ bSecureDesktopOngoing = FALSE; LeaveCriticalSection (&csSecureDesktop); });
- // wait for the input desktop to be available before switching to
- // secure desktop. Under Windows 10, the user session can be started
- // in the background even before the user has authenticated and in this
- // case, we wait for the user to be really authenticated before starting
- // secure desktop mechanism
-
- while (!(hInputDesk = OpenInputDesktop (0, TRUE, GENERIC_READ)))
+ if (GenerateRandomString (hWndParent, szDesktopName, 64))
{
- Sleep (SECUREDESKTOP_MONOTIR_PERIOD);
- }
+ map<DWORD, BOOL> ctfmonBeforeList, ctfmonAfterList;
+ DWORD desktopAccess = DESKTOP_CREATEMENU | DESKTOP_CREATEWINDOW | DESKTOP_READOBJECTS | DESKTOP_SWITCHDESKTOP | DESKTOP_WRITEOBJECTS;
+ HDESK hSecureDesk;
- CloseDesktop (hInputDesk);
-
- // get the initial list of ctfmon.exe processes before creating new desktop
- GetCtfMonProcessIdList (ctfmonBeforeList);
+ HDESK hInputDesk = NULL;
- hSecureDesk = CreateDesktop (szDesktopName, NULL, NULL, 0, desktopAccess, NULL);
- if (hSecureDesk)
- {
- SecureDesktopThreadParam param;
-
- param.hDesk = hSecureDesk;
- param.szDesktopName = szDesktopName;
- param.hInstance = hInstance;
- param.lpTemplateName = lpTemplateName;
- param.lpDialogFunc = lpDialogFunc;
- param.dwInitParam = dwInitParam;
- param.retValue = 0;
+ // wait for the input desktop to be available before switching to
+ // secure desktop. Under Windows 10, the user session can be started
+ // in the background even before the user has authenticated and in this
+ // case, we wait for the user to be really authenticated before starting
+ // secure desktop mechanism
- HANDLE hThread = ::CreateThread (NULL, 0, SecureDesktopThread, (LPVOID) &param, 0, NULL);
- if (hThread)
+ while (!(hInputDesk = OpenInputDesktop (0, TRUE, GENERIC_READ)))
{
- WaitForSingleObject (hThread, INFINITE);
- CloseHandle (hThread);
-
- retValue = param.retValue;
- bSuccess = TRUE;
+ Sleep (SECUREDESKTOP_MONOTIR_PERIOD);
}
- CloseDesktop (hSecureDesk);
-
- // get the new list of ctfmon.exe processes in order to find the ID of the
- // ctfmon.exe instance that corresponds to the desktop we create so that
- // we can kill it, otherwise it would remain running
- GetCtfMonProcessIdList (ctfmonAfterList);
+ CloseDesktop (hInputDesk);
+
+ // get the initial list of ctfmon.exe processes before creating new desktop
+ GetCtfMonProcessIdList (ctfmonBeforeList);
- for (map<DWORD, BOOL>::iterator It = ctfmonAfterList.begin();
- It != ctfmonAfterList.end(); It++)
+ hSecureDesk = CreateDesktop (szDesktopName, NULL, NULL, 0, desktopAccess, NULL);
+ if (hSecureDesk)
{
- if (ctfmonBeforeList[It->first] != TRUE)
+ SecureDesktopThreadParam param;
+
+ param.hDesk = hSecureDesk;
+ param.szDesktopName = szDesktopName;
+ param.hInstance = hInstance;
+ param.lpTemplateName = lpTemplateName;
+ param.lpDialogFunc = lpDialogFunc;
+ param.dwInitParam = dwInitParam;
+ param.retValue = 0;
+
+ HANDLE hThread = ::CreateThread (NULL, 0, SecureDesktopThread, (LPVOID) &param, 0, NULL);
+ if (hThread)
{
- // Kill process
- KillProcess (It->first);
+ WaitForSingleObject (hThread, INFINITE);
+ CloseHandle (hThread);
+
+ retValue = param.retValue;
+ bSuccess = TRUE;
+ }
+
+ CloseDesktop (hSecureDesk);
+
+ // get the new list of ctfmon.exe processes in order to find the ID of the
+ // ctfmon.exe instance that corresponds to the desktop we create so that
+ // we can kill it, otherwise it would remain running
+ GetCtfMonProcessIdList (ctfmonAfterList);
+
+ for (map<DWORD, BOOL>::iterator It = ctfmonAfterList.begin();
+ It != ctfmonAfterList.end(); It++)
+ {
+ if (ctfmonBeforeList[It->first] != TRUE)
+ {
+ // Kill process
+ KillProcess (It->first);
+ }
}
}
- }
- burn (szDesktopName, sizeof (szDesktopName));
+ burn (szDesktopName, sizeof (szDesktopName));
+ }
}
if (!bSuccess)