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326 lines
9.9 KiB
326 lines
9.9 KiB
/*++
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Copyright (c) 1999-2000 Microsoft Corporation
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Module Name:
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SafeExt.c (WinSAFER File Extension)
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Abstract:
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This module implements the WinSAFER APIs that evaluate the system
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policies to determine if a given file extension is an "executable"
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file that needs to have different enforcement policies considered.
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Author:
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Jeffrey Lawson (JLawson) - Nov 1999
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Environment:
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User mode only.
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Exported Functions:
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Revision History:
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Created - Jul 2000
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--*/
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#include "pch.h"
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#pragma hdrstop
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#include <winsafer.h>
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#include <winsaferp.h>
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#include "saferp.h"
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NTSTATUS NTAPI
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__CodeAuthzIsExecutableFileTypeHelper(
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IN PUNICODE_STRING UnicodeFullPathname,
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IN DWORD dwScopeId,
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IN BOOLEAN bFromShellExecute,
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OUT PBOOLEAN pbResult
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)
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{
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NTSTATUS Status;
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LPCWSTR szExtension, szPtr, szEnd;
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ULONG ulExtensionLength;
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HANDLE hKeyBadTypes;
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DWORD dwAllocatedSize = 0, dwActualSize;
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PKEY_VALUE_PARTIAL_INFORMATION pKeyValueInfo = NULL;
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const static UNICODE_STRING UnicodeValueName =
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RTL_CONSTANT_STRING(SAFER_EXETYPES_REGVALUE);
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if (!ARGUMENT_PRESENT(UnicodeFullPathname) ||
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UnicodeFullPathname->Buffer == NULL ||
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UnicodeFullPathname->Length == 0)
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{
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Status = STATUS_INVALID_PARAMETER;
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goto ExitHandler;
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}
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if (!ARGUMENT_PRESENT(pbResult)) {
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Status = STATUS_ACCESS_VIOLATION;
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goto ExitHandler;
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}
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//
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// Start from the end of the string and scan backwards to
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// look for the period separator and find the extension.
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//
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szExtension = UnicodeFullPathname->Buffer +
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(UnicodeFullPathname->Length / sizeof(WCHAR));
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ASSERT(szExtension >= UnicodeFullPathname->Buffer);
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for (;;) {
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if (szExtension < UnicodeFullPathname->Buffer ||
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*szExtension == L'\\' || *szExtension == L'/') {
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// We scanned back too far, but did not find the extension.
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Status = STATUS_NOT_FOUND;
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goto ExitHandler;
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}
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if (*szExtension == L'.') {
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// We found the period that marks the extension.
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szExtension++;
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break;
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}
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szExtension--;
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}
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ulExtensionLength = (UnicodeFullPathname->Length / sizeof(WCHAR)) -
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(ULONG) (szExtension - UnicodeFullPathname->Buffer);
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if (ulExtensionLength == 0) {
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// We found a period, but there was no extension.
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Status = STATUS_NOT_FOUND;
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goto ExitHandler;
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}
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if (bFromShellExecute) {
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if ( _wcsicmp(szExtension, L"exe") == 0 ){
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*pbResult = FALSE;
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Status = STATUS_SUCCESS;
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goto ExitHandler;
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}
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}
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//
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// Open and query the registry value containing the list of extensions.
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//
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Status = CodeAuthzpOpenPolicyRootKey(
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dwScopeId,
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NULL,
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SAFER_CODEIDS_REGSUBKEY,
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KEY_READ,
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FALSE,
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&hKeyBadTypes
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);
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if (!NT_SUCCESS(Status)) {
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goto ExitHandler;
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}
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for (;;) {
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Status = NtQueryValueKey(
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hKeyBadTypes,
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(PUNICODE_STRING) &UnicodeValueName,
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KeyValuePartialInformation,
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pKeyValueInfo, dwAllocatedSize, &dwActualSize);
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if (NT_SUCCESS(Status)) {
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break;
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}
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else if ((Status == STATUS_BUFFER_OVERFLOW ||
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Status == STATUS_BUFFER_TOO_SMALL) &&
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dwActualSize > dwAllocatedSize)
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{
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if (pKeyValueInfo != NULL) {
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RtlFreeHeap(RtlProcessHeap(), 0, pKeyValueInfo);
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}
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dwAllocatedSize = dwActualSize;
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pKeyValueInfo = (PKEY_VALUE_PARTIAL_INFORMATION)
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RtlAllocateHeap(RtlProcessHeap(), 0, dwAllocatedSize);
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if (!pKeyValueInfo) {
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Status = STATUS_NO_MEMORY;
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goto ExitHandler2;
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}
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}
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else {
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goto ExitHandler3;
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}
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}
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//
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// See if the extension is in one of those specified in the list.
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//
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szEnd = (LPCWSTR) ( ((LPBYTE) pKeyValueInfo->Data) +
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pKeyValueInfo->DataLength);
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for (szPtr = (LPCWSTR) pKeyValueInfo->Data; szPtr < szEnd; ) {
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ULONG ulOneExtension = wcslen(szPtr);
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if (szPtr + ulOneExtension > szEnd) {
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ulOneExtension = (ULONG) (szEnd - szPtr);
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}
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if (ulOneExtension == ulExtensionLength &&
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_wcsnicmp(szExtension, szPtr, ulExtensionLength) == 0) {
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*pbResult = TRUE;
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Status = STATUS_SUCCESS;
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goto ExitHandler3;
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}
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szPtr += ulOneExtension + 1;
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}
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*pbResult = FALSE;
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Status = STATUS_SUCCESS;
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ExitHandler3:
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if (pKeyValueInfo != NULL) {
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RtlFreeHeap(RtlProcessHeap(), 0, pKeyValueInfo);
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}
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ExitHandler2:
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NtClose(hKeyBadTypes);
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ExitHandler:
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return Status;
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}
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NTSTATUS NTAPI
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CodeAuthzIsExecutableFileType(
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IN PUNICODE_STRING UnicodeFullPathname,
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IN BOOLEAN bFromShellExecute,
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OUT PBOOLEAN pbResult
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)
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/*++
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Routine Description:
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This API determines if a specified filename has an extension that
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is considered an "executable" extension. Applications can take
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special precautions to avoid invoking untrusted files that might
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be considered executable.
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Common examples of extensions that are considered executable include:
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EXE, COM, BAT, CMD, VBS, JS, URL, LNK, SHS, PIF, PL, and others.
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Arguments:
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UnicodeFullPathname - pointer to a Unicode string of the
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full path and/or filename to evaluate. Only the file's extension
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(the portion of the specified path following the last period)
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is used in this evaluation. File extension comparisons are done
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case-insensitively, without regard to case.
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An error will be returned if this pointer is NULL, or if the length
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of the path is zero, or if the file does not have an extension.
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Although applications are encouraged to supply the entire,
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fully-qualified pathname to this API, the szFullPathname argument
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will also accept only the file extension, by ensuring that the
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file extension is preceeded by a period (for example: L".exe")
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bFromShellExecute - for performance reasons, if this is being called
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from ShellExecute, we'd like to skip exe checking since CreateProcess
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will do the check
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pbResult - pointer to a variable that will receive a TRUE or FALSE
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result value if this API executes successfully. An error will
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be returned if this pointer is NULL.
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Return Value:
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Returns STATUS_SUCCESS if the API executes successfully, otherwise a
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valid NTSTATUS error code is returned. If the return value indicates
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success, then the argument 'pbResult' will also receive a boolean
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value indicating whether or not the pathname represented an executable
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file type.
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--*/
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{
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NTSTATUS Status;
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Status = __CodeAuthzIsExecutableFileTypeHelper(
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UnicodeFullPathname,
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SAFER_SCOPEID_MACHINE,
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bFromShellExecute,
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pbResult
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);
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if (!NT_SUCCESS(Status)) {
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Status = __CodeAuthzIsExecutableFileTypeHelper(
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UnicodeFullPathname,
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SAFER_SCOPEID_USER,
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bFromShellExecute,
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pbResult
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);
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}
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return Status;
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}
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BOOL WINAPI
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SaferiIsExecutableFileType(
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IN LPCWSTR szFullPathname,
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IN BOOLEAN bFromShellExecute
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)
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/*++
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Routine Description:
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This API determines if a specified filename has an extension that
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is considered an "executable" extension. Applications can take
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special precautions to avoid invoking untrusted files that might
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be considered executable.
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Common examples of extensions that are considered executable include:
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EXE, COM, BAT, CMD, VBS, JS, URL, LNK, SHS, PIF, PL, and others.
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Arguments:
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szFullPathname - pointer to a Null-terminated Unicode string of the
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full path and/or filename to evaluate. Only the file's extension
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(the portion of the specified path following the last period)
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is used in this evaluation. File extension comparisons are done
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case-insensitively, without regard to case.
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An error will be returned if this pointer is NULL, or if the length
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of the path is zero, or if the file does not have an extension.
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Although applications are encouraged to supply the entire,
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fully-qualified pathname to this API, the szFullPathname argument
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will also accept only the file extension, by ensuring that the
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file extension is preceeded by a period (for example: L".exe")
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bFromShellExecute - for performance reasons, if this is being called
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from ShellExecute, we'd like to skip exe checking since CreateProcess
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will do the check
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Return Value:
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Returns TRUE if the API executes successfully and the filepath's
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extension was recognized as one of the "executable extensions".
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Otherwise a return value of FALSE will either indicate unsuccessful
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API execution, or identification of a non-executable extension.
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--*/
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{
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NTSTATUS Status;
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UNICODE_STRING UnicodePathname;
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BOOLEAN bResult;
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RtlInitUnicodeString(&UnicodePathname, szFullPathname);
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Status = CodeAuthzIsExecutableFileType(
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&UnicodePathname, bFromShellExecute, &bResult);
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if (!NT_SUCCESS(Status)) {
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BaseSetLastNTError(Status);
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return FALSE;
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}
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if (!bResult) {
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BaseSetLastNTError(STATUS_NOT_FOUND);
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return FALSE;
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} else {
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return TRUE;
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}
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}
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