Changeset 87031 in vbox for trunk/src/VBox/HostDrivers

Timestamp:

Dec 2, 2020 11:57:03 AM (4 years ago)

Author:

vboxsync

Message:

Support,FE/VirtualBox: Move the issetugid() hack to the hardened support code to reduce the number of hacks in the VirtualBox frontend

File:

• trunk/src/VBox/HostDrivers/Support/darwin/SUPR3HardenedMain-darwin.cpp (modified) (4 diffs)

trunk/src/VBox/HostDrivers/Support/darwin/SUPR3HardenedMain-darwin.cpp

@@ -41 +41 @@
 #include <stdio.h>
 #include <stdint.h>
+#include <unistd.h> /* issetugid() */
 #include <mach-o/dyld.h>
 
@@ -86 +87 @@
 
 static void * supR3HardenedDarwinDlopenInterpose(const char *path, int mode);
+static int supR3HardenedDarwinIssetugidInterpose(void);
 
 
@@ -102 +104 @@
 static const DYLDINTERPOSE     g_aInterposers[] =
 {
-    { (const void *)(uintptr_t)&supR3HardenedDarwinDlopenInterpose, (const void *)(uintptr_t)&dlopen }
+    { (const void *)(uintptr_t)&supR3HardenedDarwinDlopenInterpose,    (const void *)(uintptr_t)&dlopen    },
+    { (const void *)(uintptr_t)&supR3HardenedDarwinIssetugidInterpose, (const void *)(uintptr_t)&issetugid }
 };
 
@@ -147 +150 @@
 
 /**
+ * Override this one to try hide the fact that we're setuid to root orginially.
+ *
+ * @sa issetugid() man page.
+ *
+ * Mac OS X: Really ugly hack to bypass a set-uid check in AppKit.
+ *
+ * This will modify the issetugid() function to always return zero.  This must
+ * be done _before_ AppKit is initialized, otherwise it will refuse to play ball
+ * with us as it distrusts set-uid processes since Snow Leopard.  We, however,
+ * have carefully dropped all root privileges at this point and there should be
+ * no reason for any security concern here.
+ */
+static int supR3HardenedDarwinIssetugidInterpose(void)
+{
+    Dl_info Info = {0};
+    char szMsg[512];
+    size_t cchMsg;
+    const void * uCaller = __builtin_return_address(0);
+    if (dladdr(uCaller, &Info))
+        cchMsg = snprintf(szMsg, sizeof(szMsg), "DEBUG: issetugid_for_AppKit was called by %p %s::%s+%p (via %p)\n",
+                          uCaller, Info.dli_fname, Info.dli_sname, (void *)((uintptr_t)uCaller - (uintptr_t)Info.dli_saddr), __builtin_return_address(1));
+    else
+        cchMsg = snprintf(szMsg, sizeof(szMsg), "DEBUG: issetugid_for_AppKit was called by %p (via %p)\n", uCaller, __builtin_return_address(1));
+    write(2, szMsg, cchMsg);
+    return 0;
+}
+
+
+/**
  * Callback to get notified of new images being loaded to be able to apply our dlopn() interposer.
  *