dlwrap: Add new dlwrap_dlopen_libfips function

Previously, two different pieces of fips code (both for dlopen and for
glXGetProcAddress) both needed to dlopen the fips library
itself. However, the two pieces were implemented differently, (one
passed a symbol to dladdr to find a filename to dlopen, the other just
passed NULL to dlsym and hopef for the best).

Make things consistent by having a single, shared implementation in
the new function dlwrap_dlopen_libfips, (and implement it with the
more reliable approach of calling dladdr and then the real dlopen).

diff --git a/dlwrap.c b/dlwrap.c
index dda7a77a00590e53a5101b98d6961092315ab7c3..036d981d909feb56e857726b7a0ff0bf165d9763 100644 (file)
--- a/dlwrap.c
+++ b/dlwrap.c
@@ -66,6 +66,31 @@ find_wrapped_library_index (const char *filename, unsigned *index_ret)
        return false;
 }
 
+/* Perform a dlopen on the libfips library itself.
+ *
+ * Many places in fips need to lookup symbols within the libfips
+ * library itself, (and not in any other library). This function
+ * provides a reliable way to get a handle for performing such
+ * lookups.
+ *
+ * The returned handle can be passed to dlwrap_real_dlsym for the
+ * lookups. */
+void *
+dlwrap_dlopen_libfips (void)
+{
+       Dl_info info;
+
+       /* We first find our own filename by looking up a function
+        * known to exist only in libfips. This function itself
+        * (dlwrap_dlopen_libfips) is a good one for that purpose. */
+       if (dladdr (dlwrap_dlopen_libfips, &info) == 0) {
+               fprintf (stderr, "Internal error: Failed to lookup filename of libfips library with dladdr\n");
+               exit (1);
+       }
+
+       return dlwrap_real_dlopen (info.dli_fname, RTLD_NOW);
+}
+
 /* Many (most?) OpenGL programs dlopen libGL.so.1 rather than linking
  * against it directly, which means they would not be seeing our
  * wrapped GL symbols via LD_PRELOAD. So we catch the dlopen in a
@@ -74,7 +99,6 @@ find_wrapped_library_index (const char *filename, unsigned *index_ret)
 void *
 dlopen (const char *filename, int flag)
 {
-       Dl_info info;
        void *ret;
        unsigned index;
 
@@ -99,23 +123,13 @@ dlopen (const char *filename, int flag)
        assert (index < ARRAY_SIZE(orig_handles));
        orig_handles[index] = ret;
 
+       if (libfips_handle == NULL)
+               libfips_handle = dlwrap_dlopen_libfips ();
+
        /* Otherwise, we return our own handle so that we can intercept
         * future calls to dlsym. We encode the index in the return value
         * so that we can later map back to the originally requested
         * dlopen-handle if necessary. */
-       if (libfips_handle)
-               return libfips_handle + index;
-
-       /* We find our own filename by looking up this very function
-        * (that is, this "dlopen"), with dladdr).*/
-       if (dladdr (dlopen, &info) == 0) {
-               fprintf (stderr, "Error: Failed to redirect dlopen of %s:\n",
-                        filename);
-               exit (1);
-       }
-
-       libfips_handle = dlwrap_real_dlopen (info.dli_fname, flag);
-
        return libfips_handle + index;
 }
 

diff --git a/dlwrap.h b/dlwrap.h
index cad5a62f7d86a901521fcd74e07634d4ee6ca8ed..6460dfef136b0370ba78eb45f9d47f8a19974fed 100644 (file)
--- a/dlwrap.h
+++ b/dlwrap.h
@@ -33,6 +33,18 @@
 void *
 dlwrap_real_dlopen (const char *filename, int flag);
 
+/* Perform a dlopen on the libfips library itself.
+ *
+ * Many places in fips need to lookup symbols within the libfips
+ * library itself, (and not in any other library). This function
+ * provides a reliable way to get a handle for performing such
+ * lookups.
+ *
+ * The returned handle can be passed to dlwrap_real_dlsym for the
+ * lookups. */
+void *
+dlwrap_dlopen_libfips (void);
+
 /* Call the *real* dlsym. We have our own wrapper for dlsym that, of
  * necessity must use claim the symbol 'dlsym'. So whenever anything
  * internal needs to call the real, underlying dlysm function, the

diff --git a/glxwrap.c b/glxwrap.c
index d7d4191ce528ae5b59c5f8a9317b8e99a179d679..cccc05f99e1295b0c51165cf226e61164cec956d 100644 (file)
--- a/glxwrap.c
+++ b/glxwrap.c
@@ -47,10 +47,14 @@ glXSwapBuffers (Display *dpy, GLXDrawable drawable)
  */
 void (*glXGetProcAddressARB (const GLubyte *func))(void)
 {
+       static void *libfips_handle = NULL;
        void *ret;
 
+       if (libfips_handle == NULL)
+               libfips_handle = dlwrap_dlopen_libfips ();
+
        /* If our library has this symbol, that's what we want to give. */
-       ret = dlwrap_real_dlsym (NULL, (const char *) func);
+       ret = dlwrap_real_dlsym (libfips_handle, (const char *) func);
        if (ret)
                return ret;