Re: dlsym() on implicit loaded symbols

[Kostik Belousov]

On Sun, Jul 16, 2006 at 03:26:33PM +0200, Roland Dittel wrote:
> 
> Am 16.07.2006 um 14:33 schrieb Simon 'corecode' Schubert:
> 
> >Roland Dittel wrote:
> >>>>We have a issue with dlsym() on symbols imported by a library that 
> >>>>was loaded with dlopen(). Our code loads the libssl with dlopen() 
> >>>>and then do a dlsym() on several symbols. This works for all 
> >>>>symbols exported by libssl itself but fails for symbols exported by 
> >>>>libcrypto.
> >[..]
> >>      func = dlsym(handle, "CRYPTO_set_id_callback");
> >
> >you have to use RTLD_DEFAULT instead of handle, but I agree, this is 
> >not in conformance with SUSv3:
> 
> That's it. Thank you very much.
> 
> Roland
> 
> >
> >   The dlsym() function shall search for the named symbol in all 
> >objects loaded automatically as a result of loading the object 
> >referenced by handle (see dlopen()). Load ordering is used in dlsym() 
> >operations upon the global symbol object. The symbol resolution 
> >algorithm used shall be dependency order as described in dlopen().
> >
> >   The RTLD_DEFAULT and RTLD_NEXT flags are reserved for future use.
> >
> >Note "in all objects loaded automatically".  Good catch!
> >
Try this (against RELENG_6), patch for CURRENT needs some editing.

Index: rtld.c
===================================================================
RCS file: /usr/local/arch/ncvs/src/libexec/rtld-elf/rtld.c,v
retrieving revision 1.106.2.2
diff -u -r1.106.2.2 rtld.c
--- rtld.c      30 Dec 2005 22:13:56 -0000      1.106.2.2
+++ rtld.c      16 Jul 2006 18:05:39 -0000
@@ -123,7 +123,7 @@
 static const Elf_Sym *symlook_default(const char *, unsigned long hash,
   const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
 static const Elf_Sym *symlook_list(const char *, unsigned long,
-  Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
+  const Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
 static void trace_loaded_objects(Obj_Entry *obj);
 static void unlink_object(Obj_Entry *);
 static void unload_object(Obj_Entry *);
@@ -1805,25 +1805,22 @@
            def = symlook_default(name, hash, obj, &defobj, true);
        }
     } else {
+        DoneList donelist;
+
        if ((obj = dlcheck(handle)) == NULL) {
            rlock_release(rtld_bind_lock, lockstate);
            return NULL;
        }
 
+       donelist_init(&donelist);
        if (obj->mainprog) {
-           DoneList donelist;
 
            /* Search main program and all libraries loaded by it. */
-           donelist_init(&donelist);
            def = symlook_list(name, hash, &list_main, &defobj, true,
              &donelist);
        } else {
-           /*
-            * XXX - This isn't correct.  The search should include the whole
-            * DAG rooted at the given object.
-            */
-           def = symlook_obj(name, hash, obj, true);
-           defobj = obj;
+           def = symlook_list(name, hash, &(obj->dagmembers), &defobj, true,
+             &donelist);
        }
     }
 
@@ -2274,7 +2271,7 @@
 }
 
 static const Elf_Sym *
-symlook_list(const char *name, unsigned long hash, Objlist *objlist,
+symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
   const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
 {
     const Elf_Sym *symp;

pgpmppDFtcE3r.pgp
Description: PGP signature