1 files changed, 185 insertions, 0 deletions

diff --git a/symlink.c b/symlink.c
new file mode 100644
index 0000000..237ac97
--- /dev/null
+++ b/symlink.c
@@ -0,0 +1,185 @@
+/*
+ * Copyright (c) 2004 Security Architects Corporation. All rights reserved.
+ *
+ * Module Name:
+ *
+ *              symlink.c
+ *
+ * Abstract:
+ *
+ *              This module implements various symbolic link object hooking routines.
+ *
+ * Author:
+ *
+ *              Eugene Tsyrklevich 25-Mar-2004
+ *
+ * Revision History:
+ *
+ *              None.
+ */
+
+
+#include "symlink.h"
+#include "media.h"
+
+
+#ifdef ALLOC_PRAGMA
+#pragma alloc_text (INIT, InitSymlinkHooks)
+#endif
+
+
+fpZwCreateSymbolicLinkObject    OriginalNtCreateSymbolicLinkObject = NULL;
+fpZwOpenSymbolicLinkObject              OriginalNtOpenSymbolicLinkObject = NULL;
+
+
+/*
+ * HookedNtCreateSymbolicLinkObject()
+ *
+ * Description:
+ *              This function mediates the NtCreateSymbolicLinkObject() system service and checks the
+ *              provided symbolic link object name against the global and current process security policies.
+ *
+ *              NOTE: ZwCreateSymbolicLinkObject creates or opens a symbolic link object. [NAR]
+ *
+ * Parameters:
+ *              Those of NtCreateSymbolicLinkObject().
+ *
+ * Returns:
+ *              STATUS_ACCESS_DENIED if the call does not pass the security policy check.
+ *              Otherwise, NTSTATUS returned by NtCreateSymbolicLinkObject().
+ */
+
+NTSTATUS
+NTAPI
+HookedNtCreateSymbolicLinkObject
+(
+        OUT PHANDLE SymbolicLinkHandle,
+        IN ACCESS_MASK DesiredAccess,
+        IN POBJECT_ATTRIBUTES ObjectAttributes,
+        IN PUNICODE_STRING TargetName
+)
+{
+        PCHAR                   FunctionName = "HookedNtCreateSymbolicLinkObject";
+        CHAR                    SYMLINKNAME[MAX_PATH];
+
+
+        HOOK_ROUTINE_ENTER();
+
+
+        if (LearningMode == FALSE && GetPathFromOA(ObjectAttributes, SYMLINKNAME, MAX_PATH, RESOLVE_LINKS))
+        {
+                /* TargetName is not verified to be valid but it's ok as we don't use it for anything but printing (in debugging mode only) */
+                if (TargetName)
+                        LOG(LOG_SS_SYMLINK, LOG_PRIORITY_VERBOSE, ("%d HookedNtCreateSymbolicLinkObject: %s -> %S\n", (ULONG) PsGetCurrentProcessId(), SYMLINKNAME, TargetName->Buffer));
+                else
+                        LOG(LOG_SS_SYMLINK, LOG_PRIORITY_VERBOSE, ("%d HookedNtCreateSymbolicLinkObject: %s ->.\n", (ULONG) PsGetCurrentProcessId(), SYMLINKNAME));
+
+
+                POLICY_CHECK_OPTYPE_NAME(SYMLINK, Get_SYMLINK_OperationType(DesiredAccess));
+        }
+
+
+        ASSERT(OriginalNtCreateSymbolicLinkObject);
+
+        rc = OriginalNtCreateSymbolicLinkObject(SymbolicLinkHandle, DesiredAccess, ObjectAttributes, TargetName);
+
+
+#if HOOK_MEDIA
+        /* removable media hook */
+        if (LearningMode == FALSE && NT_SUCCESS(rc) && KeGetPreviousMode() == KernelMode)
+        {
+                MonitorDriveLinks(SYMLINKNAME);
+        }
+#endif
+
+
+        HOOK_ROUTINE_FINISH(SYMLINK);
+}
+
+
+
+/*
+ * HookedNtOpenSymbolicLinkObject()
+ *
+ * Description:
+ *              This function mediates the NtOpenSymbolicLinkObject() system service and checks the
+ *              provided symbolic link object name against the global and current process security policies.
+ *
+ *              NOTE: ZwOpenSymbolicLinkObject opens a symbolic link object. [NAR]
+ *
+ * Parameters:
+ *              Those of NtOpenSymbolicLinkObject().
+ *
+ * Returns:
+ *              STATUS_ACCESS_DENIED if the call does not pass the security policy check.
+ *              Otherwise, NTSTATUS returned by NtOpenSymbolicLinkObject().
+ */
+
+NTSTATUS
+NTAPI
+HookedNtOpenSymbolicLinkObject
+(
+        OUT PHANDLE SymbolicLinkHandle,
+        IN ACCESS_MASK DesiredAccess,
+        IN POBJECT_ATTRIBUTES ObjectAttributes
+)
+{
+        PCHAR                   FunctionName = "HookedNtOpenSymbolicLinkObject";
+        CHAR                    SYMLINKNAME[MAX_PATH];
+
+
+        HOOK_ROUTINE_ENTER();
+
+
+        /* Cannot use RESOLVE_LINKS! (to avoid infinite recursion) */
+        if (LearningMode == FALSE && GetPathFromOA(ObjectAttributes, SYMLINKNAME, MAX_PATH, DO_NOT_RESOLVE_LINKS))
+        {
+                POLICY_CHECK_OPTYPE_NAME(SYMLINK, Get_SYMLINK_OperationType(DesiredAccess));
+        }
+
+
+        ASSERT(OriginalNtOpenSymbolicLinkObject);
+
+        rc = OriginalNtOpenSymbolicLinkObject(SymbolicLinkHandle, DesiredAccess, ObjectAttributes);
+
+
+        HOOK_ROUTINE_FINISH(SYMLINK);
+}
+
+
+
+/*
+ * InitSymlinkHooks()
+ *
+ * Description:
+ *              Initializes all the mediated symbolic link object operation pointers. The "OriginalFunction" pointers
+ *              are initialized by InstallSyscallsHooks() that must be called prior to this function.
+ *
+ *              NOTE: Called once during driver initialization (DriverEntry()).
+ *
+ * Parameters:
+ *              None.
+ *
+ * Returns:
+ *              TRUE to indicate success, FALSE if failed.
+ */
+
+BOOLEAN
+InitSymlinkHooks()
+{
+        if ( (OriginalNtCreateSymbolicLinkObject = (fpZwCreateSymbolicLinkObject) ZwCalls[ZW_CREATE_SYMLINK_INDEX].OriginalFunction) == NULL)
+        {
+                LOG(LOG_SS_SYMLINK, LOG_PRIORITY_DEBUG, ("InitSymlinkHooks: OriginalNtCreateSymbolicLinkObject is NULL\n"));
+                return FALSE;
+        }
+/*
+        disabled due to performance issues - this function is called by every system call (from ResolveFilename)
+
+        if ( (OriginalNtOpenSymbolicLinkObject = (fpZwOpenSymbolicLinkObject) ZwCalls[ZW_OPEN_SYMLINK_INDEX].OriginalFunction) == NULL)
+        {
+                LOG(LOG_SS_SYMLINK, LOG_PRIORITY_DEBUG, ("InitSymlinkHooks: OriginalNtOpenSymbolicLinkObject is NULL\n"));
+                return FALSE;
+        }
+*/
+        return TRUE;
+}