first pass

[PuTTY.git] / windows / winmisc.c

diff --git a/windows/winmisc.c b/windows/winmisc.c
index cd8d74ed1fdbfb76f1e6f02ffc01cdddf5d33011..8bd4c77f88171fbea6672425a5eabed1817ba4bc 100644 (file)
--- a/windows/winmisc.c
+++ b/windows/winmisc.c
@@ -71,6 +71,13 @@ Filename *filename_deserialise(void *vdata, int maxsize, int *used)
     return filename_from_str(data);
 }
 
+char filename_char_sanitise(char c)
+{
+    if (strchr("<>:\"/\\|?*", c))
+        return '.';
+    return c;
+}
+
 #ifndef NO_SECUREZEROMEMORY
 /*
  * Windows implementation of smemclr (see misc.c) using SecureZeroMemory.
@@ -142,6 +149,52 @@ char *get_username(void)
     return got_username ? user : NULL;
 }
 
+void dll_hijacking_protection(void)
+{
+    /*
+     * If the OS provides it, call SetDefaultDllDirectories() to
+     * prevent DLLs from being loaded from the directory containing
+     * our own binary, and instead only load from system32.
+     *
+     * This is a protection against hijacking attacks, if someone runs
+     * PuTTY directly from their web browser's download directory
+     * having previously been enticed into clicking on an unwise link
+     * that downloaded a malicious DLL to the same directory under one
+     * of various magic names that seem to be things that standard
+     * Windows DLLs delegate to.
+     *
+     * It shouldn't break deliberate loading of user-provided DLLs
+     * such as GSSAPI providers, because those are specified by their
+     * full pathname by the user-provided configuration.
+     */
+    static HMODULE kernel32_module;
+    DECL_WINDOWS_FUNCTION(static, BOOL, SetDefaultDllDirectories, (DWORD));
+
+    if (!kernel32_module) {
+        kernel32_module = load_system32_dll("kernel32.dll");
+        GET_WINDOWS_FUNCTION(kernel32_module, SetDefaultDllDirectories);
+    }
+
+    if (p_SetDefaultDllDirectories) {
+        /* LOAD_LIBRARY_SEARCH_SYSTEM32 | LOAD_LIBRARY_SEARCH_USER_DIRS only */
+        p_SetDefaultDllDirectories(0x800|0x400);
+    }
+}
+
+void dll_hijacking_protection_add_path(const wchar_t *path)
+{
+    static HMODULE kernel32_module;
+    DECL_WINDOWS_FUNCTION(static, BOOL, AddDllDirectory, (PCWSTR));
+
+    if (!kernel32_module) {
+        kernel32_module = load_system32_dll("kernel32.dll");
+        GET_WINDOWS_FUNCTION(kernel32_module, AddDllDirectory);
+    }
+
+    if (p_AddDllDirectory) {
+        p_AddDllDirectory(path);
+    }
+}
 BOOL init_winver(void)
 {
     ZeroMemory(&osVersion, sizeof(osVersion));
@@ -222,8 +275,8 @@ const char *win_strerror(int error)
                            MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
                            msgtext, lenof(msgtext)-1, NULL)) {
             sprintf(msgtext,
-                    "(unable to format: FormatMessage returned %d)",
-                    GetLastError());
+                    "(unable to format: FormatMessage returned %u)",
+                    (unsigned int)GetLastError());
         } else {
             int len = strlen(msgtext);
             if (len > 0 && msgtext[len-1] == '\n')