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Emulate the standard symbol search order in dlsym() i.e. resolve weak or 

not found symbols that are in the dynamic linker list of exported symbols
from the dynamic linker itself.
This commit is contained in:
christos 2016-11-30 19:43:32 +00:00
parent 2bf20eb795
commit d32757ced4
3 changed files with 22 additions and 6 deletions
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19
libexec/ld.elf_so/rtld.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: rtld.c,v 1.178 2016/05/24 20:32:33 christos Exp $ */
/* $NetBSD: rtld.c,v 1.179 2016/11/30 19:43:32 christos Exp $ */
/*
* Copyright 1996 John D. Polstra.
@ -40,7 +40,7 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: rtld.c,v 1.178 2016/05/24 20:32:33 christos Exp $");
__RCSID("$NetBSD: rtld.c,v 1.179 2016/11/30 19:43:32 christos Exp $");
#endif /* not lint */
#include <sys/param.h>
@ -1134,6 +1134,21 @@ do_dlsym(void *handle, const char *name, const Ver_Entry *ventry, void *retaddr)
break;
}
}
/*
* Search the dynamic linker itself, and possibly * resolve the symbol from there if it is not defined
* already or weak. This is how the application links
* to dynamic linker services such as dlopen. Only the
* values listed in the "_rtld_exports" array can be
* resolved from the dynamic linker.
*/
if (!def || ELF_ST_BIND(def->st_info) == STB_WEAK) {
const Elf_Sym *symp = _rtld_symlook_obj(name,
hash, &_rtld_objself, flags, ventry);
if (symp != NULL && _rtld_is_exported(symp)) {
def = symp;
defobj = &_rtld_objself;
}
}
break;
case (intptr_t)RTLD_DEFAULT:

3
libexec/ld.elf_so/rtld.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: rtld.h,v 1.125 2016/06/14 13:06:41 christos Exp $ */
/* $NetBSD: rtld.h,v 1.126 2016/11/30 19:43:32 christos Exp $ */
/*
* Copyright 1996 John D. Polstra.
@ -416,6 +416,7 @@ Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *);
Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
/* symbol.c */
bool _rtld_is_exported(const Elf_Sym *);
unsigned long _rtld_elf_hash(const char *);
const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long,
const Obj_Entry *, u_int, const Ver_Entry *);

6
libexec/ld.elf_so/symbol.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: symbol.c,v 1.65 2014/08/10 23:35:26 matt Exp $ */
/* $NetBSD: symbol.c,v 1.66 2016/11/30 19:43:32 christos Exp $ */
/*
* Copyright 1996 John D. Polstra.
@ -40,7 +40,7 @@
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: symbol.c,v 1.65 2014/08/10 23:35:26 matt Exp $");
__RCSID("$NetBSD: symbol.c,v 1.66 2016/11/30 19:43:32 christos Exp $");
#endif /* not lint */
#include <err.h>
@ -80,7 +80,7 @@ _rtld_donelist_check(DoneList *dlp, const Obj_Entry *obj)
return false;
}
static bool
bool
_rtld_is_exported(const Elf_Sym *def)
{
static const fptr_t _rtld_exports[] = {