/* $NetBSD: mdreloc.c,v 1.9 2023/06/04 01:24:58 joerg Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Thomas of 3am Software Foundry.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: mdreloc.c,v 1.9 2023/06/04 01:24:58 joerg Exp $");
#endif /* not lint */
#include <sys/types.h>
#include <sys/endian.h>
#include <sys/tls.h>
#include <stdlib.h>
#include <string.h>
#include "debug.h"
#include "rtld.h"
void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
void *_rtld_bind(const Obj_Entry *, Elf_Word);
void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
obj->pltgot[1] = (Elf_Addr) obj;
}
void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
const Elf_Rela *rela = NULL, *relalim;
Elf_Addr relasz = 0;
for (; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
case DT_RELA:
rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
break;
case DT_RELASZ:
relasz = dynp->d_un.d_val;
break;
}
}
relalim = (const Elf_Rela *)((uintptr_t)rela + relasz);
for (; rela < relalim; rela++) {
Elf_Word r_type = ELF_R_TYPE(rela->r_info);
Elf_Addr *where = (Elf_Addr *)(relocbase + rela->r_offset);
switch (r_type) {
case R_TYPE(RELATIVE): {
Elf_Addr val = relocbase + rela->r_addend;
*where = val;
rdbg(("RELATIVE/L(%p) -> %p in <self>",
where, (void *)val));
break;
}
case R_TYPE(NONE):
break;
default:
abort();
}
}
}
int
_rtld_relocate_nonplt_objects(Obj_Entry *obj)
{
const Elf_Rela *rela;
const Elf_Sym *def = NULL;
const Obj_Entry *defobj = NULL;
unsigned long last_symnum = ULONG_MAX;
for (rela = obj->rela; rela < obj->relalim; rela++) {
Elf_Addr * const where =
(Elf_Addr *)(obj->relocbase + rela->r_offset);
const Elf_Word r_type = ELF_R_TYPE(rela->r_info);
unsigned long symnum;
switch (r_type) {
case R_TYPESZ(ADDR):
case R_TYPESZ(TLS_DTPMOD):
case R_TYPESZ(TLS_DTPREL):
case R_TYPESZ(TLS_TPREL):
symnum = ELF_R_SYM(rela->r_info);
if (last_symnum != symnum) {
last_symnum = symnum;
def = _rtld_find_symdef(symnum, obj, &defobj,
false);
if (def == NULL)
return -1;
}
break;
default:
break;
}
switch (r_type) {
case R_TYPE(NONE):
break;
case R_TYPE(RELATIVE): {
const Elf_Addr val = (Elf_Addr)obj->relocbase +
rela->r_addend;
rdbg(("RELATIVE(%p) -> %p (%s) in %s",
where, (void *)val,
obj->strtab +
obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
obj->path));
*where = val;
break;
}
case R_TYPESZ(ADDR): {
const Elf_Addr val = (Elf_Addr)defobj->relocbase +
def->st_value + rela->r_addend;
rdbg(("ADDR(%p) -> %p (%s) in %s%s",
where, (void *)val,
obj->strtab +
obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
obj->path,
def == &_rtld_sym_zero ? " (symzero)" : ""));
*where = val;
break;
}
case R_TYPE(COPY):
/*
* These are deferred until all other relocations have
* been done. All we do here is make sure that the
* COPY relocation is not in a shared library. They
* are allowed only in executable files.
*/
if (obj->isdynamic) {
_rtld_error("%s: Unexpected R_COPY relocation"
" in shared library", obj->path);
return -1;
}
rdbg(("COPY (avoid in main)"));
break;
case R_TYPESZ(TLS_DTPMOD): {
const Elf_Addr val = (Elf_Addr)defobj->tlsindex;
rdbg(("TLS_DTPMOD(%p) -> %p (%s) in %s",
where, (void *)val,
obj->strtab +
obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
obj->path));
*where = val;
break;
}
case R_TYPESZ(TLS_DTPREL): {
const Elf_Addr val = (Elf_Addr)(def->st_value +
rela->r_addend - TLS_DTV_OFFSET);
rdbg(("TLS_DTPREL(%p) -> %p (%s) in %s",
where, (void *)val,
obj->strtab +
obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
defobj->path));
*where = val;
break;
}
case R_TYPESZ(TLS_TPREL):
if (!defobj->tls_static &&
_rtld_tls_offset_allocate(__UNCONST(defobj)))
return -1;
*where = (Elf_Addr)(def->st_value + defobj->tlsoffset +
rela->r_addend);
rdbg(("TLS_TPREL %s in %s --> %p in %s",
obj->strtab +
obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
obj->path, (void *)*where, defobj->path));
break;
default:
rdbg(("sym = %lu, type = %lu, offset = %p, "
"addend = %p, contents = %p",
(u_long)ELF_R_SYM(rela->r_info),
(u_long)ELF_R_TYPE(rela->r_info),
(void *)rela->r_offset, (void *)rela->r_addend,
(void *)*where));
_rtld_error("%s: Unsupported relocation type %ld "
"in non-PLT relocations",
obj->path, (u_long)r_type);
return -1;
}
}
return 0;
}
int
_rtld_relocate_plt_lazy(Obj_Entry *obj)
{
if (!obj->relocbase)
return 0;
for (const Elf_Rela *rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(JMP_SLOT):
/* Just relocate the GOT slots pointing into the PLT */
*where += (Elf_Addr)obj->relocbase;
rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
break;
default:
rdbg(("not yet... %d", (int)ELF_R_TYPE(rela->r_info) ));
}
}
return 0;
}
static int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela,
Elf_Addr *tp)
{
Elf_Addr * const where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
const Obj_Entry *defobj;
Elf_Addr new_value;
assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
const Elf_Sym *def = _rtld_find_plt_symdef(ELF_R_SYM(rela->r_info),
obj, &defobj, tp != NULL);
if (__predict_false(def == NULL))
return -1;
if (__predict_false(def == &_rtld_sym_zero))
return -1;
if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
if (tp == NULL)
return 0;
new_value = _rtld_resolve_ifunc(defobj, def);
} else {
new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
}
rdbg(("bind now/fixup in %s --> old=%p new=%p",
defobj->strtab + def->st_name, (void *)*where,
(void *)new_value));
if (*where != new_value)
*where = new_value;
if (tp)
*tp = new_value;
return 0;
}
void *
_rtld_bind(const Obj_Entry *obj, Elf_Word gotoff)
{
const Elf_Addr relidx = (gotoff / sizeof(Elf_Addr));
const Elf_Rela *pltrela = obj->pltrela + relidx;
Elf_Addr new_value = 0;
_rtld_shared_enter();
const int err = _rtld_relocate_plt_object(obj, pltrela, &new_value);
if (err)
_rtld_die();
_rtld_shared_exit();
return (void *)new_value;
}
int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
for (const Elf_Rela *rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
return -1;
}
return 0;
}