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|
/* $NetBSD: mdreloc.c,v 1.14 2020/06/16 21:01:30 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.
*/
/*-
* Copyright (c) 2014-2015 The FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Andrew Turner
* under sponsorship from the FreeBSD Foundation.
*
* 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 AUTHOR 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 AUTHOR 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 1.14 2020/06/16 21:01:30 joerg Exp $");
#endif /* not lint */
#include <sys/types.h>
#include <string.h>
#include "debug.h"
#include "rtld.h"
struct tls_data {
size_t td_tlsindex;
Elf_Addr td_tlsoffs;
};
void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
Elf_Addr _rtld_bind(const Obj_Entry *, Elf_Word);
void *_rtld_tlsdesc_static(void *);
void *_rtld_tlsdesc_undef(void *);
void *_rtld_tlsdesc_dynamic(void *);
/*
* AARCH64 PLT looks like this;
*
* PLT HEADER <8 instructions>
* PLT ENTRY #0 <4 instructions>
* PLT ENTRY #1 <4 instructions>
* .
* .
* PLT ENTRY #n <4 instructions>
*
* PLT HEADER
* stp x16, x30, [sp, #-16]!
* adrp x16, (GOT+16)
* ldr x17, [x16, #PLT_GOT+0x10]
* add x16, x16, #PLT_GOT+0x10
* br x17
* nop
* nop
* nop
*
* PLT ENTRY #n
* adrp x16, PLTGOT + n * 8
* ldr x17, [x16, PLTGOT + n * 8]
* add x16, x16, :lo12:PLTGOT + n * 8
* br x17
*/
void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
obj->pltgot[1] = (Elf_Addr) obj;
obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
}
static struct tls_data *
_rtld_tlsdesc_alloc(size_t tlsindex, Elf_Addr offs)
{
struct tls_data *tlsdesc;
tlsdesc = xmalloc(sizeof(*tlsdesc));
tlsdesc->td_tlsindex = tlsindex;
tlsdesc->td_tlsoffs = offs;
return tlsdesc;
}
static void
_rtld_tlsdesc_fill(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *where, u_int flags)
{
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr offs = 0;
unsigned long symnum = ELF_R_SYM(rela->r_info);
if (symnum != 0) {
def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
flags);
if (def == NULL)
_rtld_die();
if (def == &_rtld_sym_zero) {
/* Weak undefined thread variable */
where[0] = (Elf_Addr)_rtld_tlsdesc_undef;
where[1] = rela->r_addend;
rdbg(("TLSDESC %s (weak) in %s --> %p",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)where[1]));
return;
}
offs = def->st_value;
} else {
defobj = obj;
}
offs += rela->r_addend;
if (defobj->tls_done) {
/* Variable is in initialy allocated TLS segment */
where[0] = (Elf_Addr)_rtld_tlsdesc_static;
where[1] = defobj->tlsoffset + offs +
sizeof(struct tls_tcb);
rdbg(("TLSDESC %s --> %p static",
obj->path, (void *)where[1]));
} else {
/* TLS offset is unknown at load time, use dynamic resolving */
where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic;
where[1] = (Elf_Addr)_rtld_tlsdesc_alloc(defobj->tlsindex, offs);
rdbg(("TLSDESC %s in %s --> %p dynamic (%zu, %p)",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)where[1], defobj->tlsindex, (void *)offs));
}
}
void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
const Elf_Rela *rela = 0, *relalim;
Elf_Addr relasz = 0;
Elf_Addr *where;
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 *)((const uint8_t *)rela + relasz);
for (; rela < relalim; rela++) {
where = (Elf_Addr *)(relocbase + rela->r_offset);
*where += (Elf_Addr)relocbase;
}
}
int
_rtld_relocate_nonplt_objects(Obj_Entry *obj)
{
const Elf_Sym *def = NULL;
const Obj_Entry *defobj = NULL;
unsigned long last_symnum = ULONG_MAX;
for (const Elf_Rela *rela = obj->rela; rela < obj->relalim; rela++) {
Elf_Addr *where;
Elf_Addr tmp;
unsigned long symnum = ULONG_MAX;
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(ABS64): /* word S + A */
case R_TYPE(GLOB_DAT): /* word S + A */
case R_TLS_TYPE(TLS_DTPREL):
case R_TLS_TYPE(TLS_DTPMOD):
case R_TLS_TYPE(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;
}
default:
break;
}
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(NONE):
break;
case R_TYPE(ABS64): /* word S + A */
case R_TYPE(GLOB_DAT): /* word S + A */
tmp = (Elf_Addr)defobj->relocbase + def->st_value +
rela->r_addend;
if (*where != tmp)
*where = tmp;
rdbg(("ABS64/GLOB_DAT %s in %s --> %p @ %p in %s",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)tmp, where, defobj->path));
break;
case R_TYPE(RELATIVE): /* word B + A */
*where = (Elf_Addr)(obj->relocbase + rela->r_addend);
rdbg(("RELATIVE in %s --> %p", obj->path,
(void *)*where));
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_TYPE(TLSDESC):
_rtld_tlsdesc_fill(obj, rela, where, 0);
break;
case R_TLS_TYPE(TLS_DTPREL):
*where = (Elf_Addr)(def->st_value + rela->r_addend);
rdbg(("TLS_DTPREL %s in %s --> %p",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)*where));
break;
case R_TLS_TYPE(TLS_DTPMOD):
*where = (Elf_Addr)(defobj->tlsindex);
rdbg(("TLS_DTPMOD %s in %s --> %p",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)*where));
break;
case R_TLS_TYPE(TLS_TPREL):
if (!defobj->tls_done &&
_rtld_tls_offset_allocate(obj))
return -1;
*where = (Elf_Addr)(def->st_value + defobj->tlsoffset +
rela->r_addend + sizeof(struct tls_tcb));
rdbg(("TLS_TPREL %s in %s --> %p in %s",
obj->strtab + obj->symtab[symnum].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) ELF_R_TYPE(rela->r_info));
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);
assert((ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT)) ||
(ELF_R_TYPE(rela->r_info) == R_TYPE(TLSDESC)));
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(JUMP_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;
case R_TYPE(TLSDESC):
_rtld_tlsdesc_fill(obj, rela, where, SYMLOOK_IN_PLT);
break;
}
}
return 0;
}
void
_rtld_call_ifunc(Obj_Entry *obj, sigset_t *mask, u_int cur_objgen)
{
const Elf_Rela *rela;
Elf_Addr *where, target;
while (obj->ifunc_remaining > 0 && _rtld_objgen == cur_objgen) {
rela = obj->pltrelalim - obj->ifunc_remaining;
--obj->ifunc_remaining;
if (ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)) {
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
target = (Elf_Addr)(obj->relocbase + rela->r_addend);
_rtld_exclusive_exit(mask);
target = _rtld_resolve_ifunc2(obj, target);
_rtld_exclusive_enter(mask);
if (*where != target)
*where = target;
}
}
}
static int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela,
Elf_Addr *tp)
{
Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
Elf_Addr new_value;
const Elf_Sym *def;
const Obj_Entry *defobj;
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(JUMP_SLOT):
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 0;
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;
break;
case R_TYPE(TLSDESC):
_rtld_tlsdesc_fill(obj, rela, where, SYMLOOK_IN_PLT);
break;
}
return 0;
}
Elf_Addr
_rtld_bind(const Obj_Entry *obj, Elf_Word relaidx)
{
const Elf_Rela *rela = obj->pltrela + relaidx;
Elf_Addr new_value = 0;
_rtld_shared_enter();
int err = _rtld_relocate_plt_object(obj, rela, &new_value);
if (err)
_rtld_die();
_rtld_shared_exit();
return new_value;
}
int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
const Elf_Rela *rela;
int err = 0;
for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
err = _rtld_relocate_plt_object(obj, rela, NULL);
if (err)
break;
}
return err;
}
|