PathToUniqueRegistryPath(HWND hwndParent, int string_size,
TCHAR *variables, stack_t **stacktop,
void *extra)
{
TCHAR tmp[MAX_PATH] = { L'\0' };
WCHAR installBasePath[MAX_PATH] = { '\0' };
popstring(stacktop, tmp, MAX_PATH);
#if !defined(UNICODE)
MultiByteToWideChar(CP_ACP, 0, tmp, -1, installBasePath, MAX_PATH);
#else
wcscpy(installBasePath, tmp);
#endif
WCHAR registryPath[MAX_PATH + 1] = { '\0' };
if (CalculateRegistryPathFromFilePath(installBasePath, registryPath)) {
pushstring(stacktop, registryPath, wcslen(registryPath) + 1);
} else {
pushstring(stacktop, TEXT(""), 1);
}
}
/**
* Verifies if the file path matches any certificate stored in the registry.
*
* @param filePath The file path of the application to check if allowed.
* @param allowFallbackKeySkip when this is TRUE the fallback registry key will
* be used to skip the certificate check. This is the default since the
* fallback registry key is located under HKEY_LOCAL_MACHINE which can't be
* written to by a low integrity process.
* Note: the maintenance service binary can be used to perform this check for
* testing or troubleshooting.
* @return TRUE if the binary matches any of the allowed certificates.
*/
BOOL
DoesBinaryMatchAllowedCertificates(LPCWSTR basePathForUpdate, LPCWSTR filePath,
BOOL allowFallbackKeySkip)
{
WCHAR maintenanceServiceKey[MAX_PATH + 1];
if (!CalculateRegistryPathFromFilePath(basePathForUpdate,
maintenanceServiceKey)) {
return FALSE;
}
// We use KEY_WOW64_64KEY to always force 64-bit view.
// The user may have both x86 and x64 applications installed
// which each register information. We need a consistent place
// to put those certificate attributes in and hence why we always
// force the non redirected registry under Wow6432Node.
// This flag is ignored on 32bit systems.
HKEY baseKey;
LONG retCode = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
maintenanceServiceKey, 0,
KEY_READ | KEY_WOW64_64KEY, &baseKey);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not open key. (%d)", retCode));
// Our tests run with a different apply directory for each test.
// We use this registry key on our test slaves to store the
// allowed name/issuers.
retCode = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
TEST_ONLY_FALLBACK_KEY_PATH, 0,
KEY_READ | KEY_WOW64_64KEY, &baseKey);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not open fallback key. (%d)", retCode));
return FALSE;
} else if (allowFallbackKeySkip) {
LOG_WARN(("Fallback key present, skipping VerifyCertificateTrustForFile "
"check and the certificate attribute registry matching "
"check."));
RegCloseKey(baseKey);
return TRUE;
}
}
// Get the number of subkeys.
DWORD subkeyCount = 0;
retCode = RegQueryInfoKeyW(baseKey, nullptr, nullptr, nullptr, &subkeyCount,
nullptr, nullptr, nullptr, nullptr, nullptr,
nullptr, nullptr);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not query info key. (%d)", retCode));
RegCloseKey(baseKey);
return FALSE;
}
// Enumerate the subkeys, each subkey represents an allowed certificate.
for (DWORD i = 0; i < subkeyCount; i++) {
WCHAR subkeyBuffer[MAX_KEY_LENGTH];
DWORD subkeyBufferCount = MAX_KEY_LENGTH;
retCode = RegEnumKeyExW(baseKey, i, subkeyBuffer,
&subkeyBufferCount, nullptr,
nullptr, nullptr, nullptr);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not enum certs. (%d)", retCode));
RegCloseKey(baseKey);
return FALSE;
}
// Open the subkey for the current certificate
HKEY subKey;
retCode = RegOpenKeyExW(baseKey,
subkeyBuffer,
0,
KEY_READ | KEY_WOW64_64KEY,
&subKey);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not open subkey. (%d)", retCode));
continue; // Try the next subkey
}
const int MAX_CHAR_COUNT = 256;
DWORD valueBufSize = MAX_CHAR_COUNT * sizeof(WCHAR);
WCHAR name[MAX_CHAR_COUNT] = { L'\0' };
WCHAR issuer[MAX_CHAR_COUNT] = { L'\0' };
// Get the name from the registry
retCode = RegQueryValueExW(subKey, L"name", 0, nullptr,
(LPBYTE)name, &valueBufSize);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not obtain name from registry. (%d)", retCode));
RegCloseKey(subKey);
continue; // Try the next subkey
}
// Get the issuer from the registry
valueBufSize = MAX_CHAR_COUNT * sizeof(WCHAR);
retCode = RegQueryValueExW(subKey, L"issuer", 0, nullptr,
(LPBYTE)issuer, &valueBufSize);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Could not obtain issuer from registry. (%d)", retCode));
RegCloseKey(subKey);
continue; // Try the next subkey
}
CertificateCheckInfo allowedCertificate = {
name,
issuer,
};
retCode = CheckCertificateForPEFile(filePath, allowedCertificate);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Error on certificate check. (%d)", retCode));
RegCloseKey(subKey);
continue; // Try the next subkey
}
retCode = VerifyCertificateTrustForFile(filePath);
if (retCode != ERROR_SUCCESS) {
LOG_WARN(("Error on certificate trust check. (%d)", retCode));
RegCloseKey(subKey);
continue; // Try the next subkey
}
RegCloseKey(baseKey);
// Raise the roof, we found a match!
return TRUE;
}
RegCloseKey(baseKey);
// No certificates match, :'(
return FALSE;
}
