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270 lines
7.2 KiB
C
270 lines
7.2 KiB
C
/* $NetBSD: mdreloc.c,v 1.2 2014/08/25 20:40:52 joerg Exp $ */
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/*-
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* Copyright (c) 2014 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Matt Thomas of 3am Software Foundry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: mdreloc.c,v 1.2 2014/08/25 20:40:52 joerg Exp $");
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#endif /* not lint */
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#include <sys/types.h>
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#include <string.h>
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#include "debug.h"
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#include "rtld.h"
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void _rtld_bind_start(void);
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void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
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caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
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void
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_rtld_setup_pltgot(const Obj_Entry *obj)
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{
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obj->pltgot[1] = (Elf_Addr) obj;
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obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
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}
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void
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_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
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{
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const Elf_Rel *rel = 0, *rellim;
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Elf_Addr relsz = 0;
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Elf_Addr *where;
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for (; dynp->d_tag != DT_NULL; dynp++) {
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switch (dynp->d_tag) {
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case DT_REL:
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rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
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break;
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case DT_RELSZ:
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relsz = dynp->d_un.d_val;
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break;
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}
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}
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rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz);
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for (; rel < rellim; rel++) {
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where = (Elf_Addr *)(relocbase + rel->r_offset);
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*where += (Elf_Addr)relocbase;
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}
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}
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int
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_rtld_relocate_nonplt_objects(Obj_Entry *obj)
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{
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for (const Elf_Rela *rela = obj->rela; rela < obj->relalim; rela++) {
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Elf_Addr *where;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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unsigned long symnum;
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Elf_Addr addend;
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where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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symnum = ELF_R_SYM(rela->r_info);
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addend = rela->r_addend;
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switch (ELF_R_TYPE(rela->r_info)) {
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case R_TYPE(NONE):
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break;
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case R_TYPE(ABS64): /* word B + S + A */
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case R_TYPE(GLOB_DAT): /* word B + S */
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def = _rtld_find_symdef(symnum, obj, &defobj, false);
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if (def == NULL)
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return -1;
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*where = addend + (Elf_Addr)defobj->relocbase +
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def->st_value;
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rdbg(("ABS64/GLOB_DAT %s in %s --> %p @ %p in %s",
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obj->strtab + obj->symtab[symnum].st_name,
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obj->path, (void *)tmp, where, defobj->path));
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break;
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case R_TYPE(RELATIVE): /* word B + A */
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*where = addend + (Elf_Addr)obj->relocbase;
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rdbg(("RELATIVE in %s --> %p", obj->path,
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(void *)tmp));
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break;
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case R_TYPE(COPY):
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/*
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* These are deferred until all other relocations have
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* been done. All we do here is make sure that the
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* COPY relocation is not in a shared library. They
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* are allowed only in executable files.
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*/
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if (obj->isdynamic) {
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_rtld_error(
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"%s: Unexpected R_COPY relocation in shared library",
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obj->path);
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return -1;
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}
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rdbg(("COPY (avoid in main)"));
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break;
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case R_TLS_TYPE(TLS_DTPREL):
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def = _rtld_find_symdef(symnum, obj, &defobj, false);
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if (def == NULL)
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return -1;
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*where = addend + (Elf_Addr)(def->st_value);
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rdbg(("TLS_DTPOFF32 %s in %s --> %p",
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obj->strtab + obj->symtab[symnum].st_name,
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obj->path, (void *)tmp));
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break;
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case R_TLS_TYPE(TLS_DTPMOD):
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def = _rtld_find_symdef(symnum, obj, &defobj, false);
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if (def == NULL)
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return -1;
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*where = (Elf_Addr)(defobj->tlsindex);
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rdbg(("TLS_DTPMOD %s in %s --> %p",
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obj->strtab + obj->symtab[symnum].st_name,
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obj->path, (void *)tmp));
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break;
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case R_TLS_TYPE(TLS_TPREL):
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def = _rtld_find_symdef(symnum, obj, &defobj, false);
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if (def == NULL)
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return -1;
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if (!defobj->tls_done &&
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_rtld_tls_offset_allocate(obj))
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return -1;
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*where = (Elf_Addr)def->st_value + defobj->tlsoffset +
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sizeof(struct tls_tcb);
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rdbg(("TLS_TPOFF32 %s in %s --> %p",
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obj->strtab + obj->symtab[symnum].st_name,
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obj->path, (void *)tmp));
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break;
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default:
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rdbg(("sym = %lu, type = %lu, offset = %p, "
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"contents = %p, symbol = %s",
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symnum, (u_long)ELF_R_TYPE(rela->r_info),
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(void *)rela->r_offset, *where,
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obj->strtab + obj->symtab[symnum].st_name));
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_rtld_error("%s: Unsupported relocation type %ld "
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"in non-PLT relocations",
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obj->path, (u_long) ELF_R_TYPE(rela->r_info));
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return -1;
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}
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}
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return 0;
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}
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int
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_rtld_relocate_plt_lazy(const Obj_Entry *obj)
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{
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if (!obj->relocbase)
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return 0;
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for (const Elf_Rel *rel = obj->pltrel; rel < obj->pltrellim; rel++) {
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Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
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assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT));
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/* Just relocate the GOT slots pointing into the PLT */
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*where += (Elf_Addr)obj->relocbase;
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rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
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}
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return 0;
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}
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static int
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_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel,
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Elf_Addr *tp)
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{
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Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
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Elf_Addr new_value;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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unsigned long info = rel->r_info;
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assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT));
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def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
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if (__predict_false(def == NULL))
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return -1;
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if (__predict_false(def == &_rtld_sym_zero))
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return 0;
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if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
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if (tp == NULL)
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return 0;
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new_value = _rtld_resolve_ifunc(defobj, def);
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} else {
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new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
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}
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rdbg(("bind now/fixup in %s --> old=%p new=%p",
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defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
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if (*where != new_value)
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*where = new_value;
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if (tp)
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*tp = new_value;
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return 0;
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}
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caddr_t
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_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
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{
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const Elf_Rel *rel = obj->pltrel + reloff;
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Elf_Addr new_value = 0; /* XXX gcc */
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_rtld_shared_enter();
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int err = _rtld_relocate_plt_object(obj, rel, &new_value);
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if (err)
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_rtld_die();
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_rtld_shared_exit();
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return (caddr_t)new_value;
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}
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int
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_rtld_relocate_plt_objects(const Obj_Entry *obj)
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{
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const Elf_Rel *rel;
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int err = 0;
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for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
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err = _rtld_relocate_plt_object(obj, rel, NULL);
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if (err)
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break;
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}
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return err;
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}
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