Date: Sat, 19 Apr 2025 13:38:44 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@freebsd.org> Cc: FreeBSD Current <current@freebsd.org> Subject: Re: RTLD_DEEPBIND question Message-ID: <aAN9NH1IR-gZceP4@kib.kiev.ua> In-Reply-To: <aAN69URjEJFuOLxR@kib.kiev.ua> References: <0b3dda4e-53e4-40e5-9484-8b5ffb84e658@FreeBSD.org> <aALjHwFnFKChuAdR@kib.kiev.ua> <900c8521-559a-47b5-acaa-ae941f6852c4@freebsd.org> <fd12cce4-7e6b-4ab6-bced-b36e98c995ba@FreeBSD.org> <7c4e1682-d797-493c-8326-08d51dde3359@FreeBSD.org> <aAN69URjEJFuOLxR@kib.kiev.ua>
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On Sat, Apr 19, 2025 at 01:29:15PM +0300, Konstantin Belousov wrote:
> 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:
>
And there is the version with the recursive marking by deepbind:
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 2346c6eae9f6..9767c8e7016c 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -3824,27 +3824,26 @@ dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
if ((lo_flags & (RTLD_LO_EARLY | RTLD_LO_IGNSTLS)) ==
0 &&
obj->static_tls && !allocate_tls_offset(obj)) {
- _rtld_error("%s: No space available "
- "for static Thread Local Storage",
+ _rtld_error(
+ "%s: No space available for static Thread Local Storage",
obj->path);
result = -1;
}
if (result != -1)
result = load_needed_objects(obj,
- lo_flags &
- (RTLD_LO_DLOPEN | RTLD_LO_EARLY |
- RTLD_LO_IGNSTLS | RTLD_LO_TRACE));
+ lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY |
+ RTLD_LO_IGNSTLS | RTLD_LO_TRACE |
+ RTLD_LO_DEEPBIND));
init_dag(obj);
ref_dag(obj);
if (result != -1)
result = rtld_verify_versions(&obj->dagmembers);
if (result != -1 && ld_tracing)
goto trace;
- if (result == -1 ||
- relocate_object_dag(obj,
- (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
- (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
- lockstate) == -1) {
+ if (result == -1 || relocate_object_dag(obj,
+ (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
+ (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
+ lockstate) == -1) {
dlopen_cleanup(obj, lockstate);
obj = NULL;
} else if (lo_flags & RTLD_LO_EARLY) {
@@ -4679,12 +4678,13 @@ 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)
help
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