Re: RTLD_DEEPBIND question

On Sat, Apr 19, 2025 at 01:25:28PM +0300, Andriy Gapon wrote:
> On 19/04/2025 12:39, Andriy Gapon wrote:
> > On 19/04/2025 12:25, Andriy Gapon wrote:
> > > On 19/04/2025 02:41, Konstantin Belousov wrote:
> > > > RTLD_DEEPBIND works by first iterating over all (recursive) DT_NEEEDED
> > > > object for the object where the symbol is resolved, then by looking at
> > > > the global list of loaded objects.
> > > > Non-deepbind resolution is performed by looking at the global list.
> > > > 
> > > > You can see it in the rtld.c:symlook_default().
> > 
> >  From a quick look at the code, should we try to resolve the symbol in
> > refobj itself when it's marked with deepbind?
> Oh, and it looks like objects loaded under the "deepbind" object (e.g.,
> needed objects) may not be aware that they are in the deepbind sub-tree?

But should they?

Lets start with some minimal intrusive change:

commit b4f4feb883a1be1d4ca3867f49baa20ce0c13d8d
Author: Konstantin Belousov <kib@FreeBSD.org>
Date:   Sat Apr 19 13:26:58 2025 +0300

    rtld: symbolic and deepbind are equivalent for the refobj
    
    Reported by:    avg

diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 2346c6eae9f6..8ea6afb43752 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -4679,12 +4679,13 @@ symlook_default(SymLook *req, const Obj_Entry *refobj)
 	 */
 	res = symlook_obj(&req1, refobj);
 	if (res == 0 && (refobj->symbolic ||
-	    ELF_ST_VISIBILITY(req1.sym_out->st_other) == STV_PROTECTED)) {
+	    ELF_ST_VISIBILITY(req1.sym_out->st_other) == STV_PROTECTED ||
+	    refobj->deepbind)) {
 		req->sym_out = req1.sym_out;
 		req->defobj_out = req1.defobj_out;
 		assert(req->defobj_out != NULL);
 	}
-	if (refobj->symbolic || req->defobj_out != NULL)
+	if (refobj->symbolic || req->defobj_out != NULL || refobj->deepbind)
 		donelist_check(&donelist, refobj);
 
 	if (!refobj->deepbind)