0df8d18100
executable was of type ET_DYN. Use this instead of `mainprog' to determine whether we need to do base-relative fixups of the PLT. (This allows loading non-relocatable objects, should we desire to do that at some point...)
281 lines
8.2 KiB
C
281 lines
8.2 KiB
C
/* $NetBSD: reloc.c,v 1.64 2002/09/06 13:20:30 mycroft Exp $ */
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/*
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* Copyright 1996 John D. Polstra.
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* Copyright 1996 Matt Thomas <matt@3am-software.com>
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* All rights reserved.
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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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by John Polstra.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Dynamic linker for ELF.
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*
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* John Polstra <jdp@polstra.com>.
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*/
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/mman.h>
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#include <dirent.h>
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#include "debug.h"
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#include "rtld.h"
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#ifndef RTLD_INHIBIT_COPY_RELOCS
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static int _rtld_do_copy_relocation __P((const Obj_Entry *, const Elf_Rela *,
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bool));
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/*
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* XXX: These don't work for the alpha and i386; don't know about powerpc
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* The alpha and the i386 avoid the problem by compiling everything PIC.
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* These relocation are supposed to be writing the address of the
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* function to be called on the bss.rel or bss.rela segment, but:
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* - st_size == 0
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* - on the i386 at least the call instruction is a direct call
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* not an indirect call.
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*/
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static int
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_rtld_do_copy_relocation(dstobj, rela, dodebug)
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const Obj_Entry *dstobj;
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const Elf_Rela *rela;
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bool dodebug;
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{
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void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
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const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
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const char *name = dstobj->strtab + dstsym->st_name;
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unsigned long hash = _rtld_elf_hash(name);
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size_t size = dstsym->st_size;
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const void *srcaddr;
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const Elf_Sym *srcsym = NULL;
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Obj_Entry *srcobj;
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for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
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if ((srcsym = _rtld_symlook_obj(name, hash, srcobj,
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false)) != NULL)
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break;
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if (srcobj == NULL) {
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_rtld_error("Undefined symbol \"%s\" referenced from COPY"
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" relocation in %s", name, dstobj->path);
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return (-1);
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}
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srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value);
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(void)memcpy(dstaddr, srcaddr, size);
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rdbg(dodebug, ("COPY %s %s %s --> src=%p dst=%p *dst= %p size %ld",
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dstobj->path, srcobj->path, name, (void *)srcaddr,
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(void *)dstaddr, (void *)*(long *)dstaddr, (long)size));
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return (0);
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}
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#endif /* RTLD_INHIBIT_COPY_RELOCS */
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/*
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* Process the special R_xxx_COPY relocations in the main program. These
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* copy data from a shared object into a region in the main program's BSS
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* segment.
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*
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* Returns 0 on success, -1 on failure.
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*/
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int
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_rtld_do_copy_relocations(dstobj, dodebug)
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const Obj_Entry *dstobj;
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bool dodebug;
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{
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#ifndef RTLD_INHIBIT_COPY_RELOCS
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/* COPY relocations are invalid elsewhere */
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assert(!dstobj->isdynamic);
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if (dstobj->rel != NULL) {
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const Elf_Rel *rel;
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for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) {
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if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) {
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Elf_Rela ourrela;
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ourrela.r_info = rel->r_info;
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ourrela.r_offset = rel->r_offset;
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ourrela.r_addend = 0;
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if (_rtld_do_copy_relocation(dstobj,
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&ourrela, dodebug) < 0)
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return (-1);
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}
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}
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}
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if (dstobj->rela != NULL) {
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const Elf_Rela *rela;
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for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) {
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if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) {
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if (_rtld_do_copy_relocation(dstobj, rela,
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dodebug) < 0)
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return (-1);
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}
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}
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}
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#endif /* RTLD_INHIBIT_COPY_RELOCS */
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return (0);
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}
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caddr_t
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_rtld_bind(obj, reloff)
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const Obj_Entry *obj;
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Elf_Word reloff;
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{
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const Elf_Rela *rela;
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Elf_Rela ourrela;
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caddr_t addr;
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if (obj->pltrel != NULL) {
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const Elf_Rel *rel;
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rel = (const Elf_Rel *)((caddr_t) obj->pltrel + reloff);
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ourrela.r_info = rel->r_info;
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ourrela.r_offset = rel->r_offset;
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ourrela.r_addend = 0;
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rela = &ourrela;
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} else {
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rela = (const Elf_Rela *)((caddr_t) obj->pltrela + reloff);
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#ifdef __sparc64__
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if (ELF_R_TYPE(obj->pltrela->r_info) == R_TYPE(JMP_SLOT)) {
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/*
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* XXXX
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*
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* The first four PLT entries are reserved. There
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* is some disagreement whether they should have
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* associated relocation entries. Both the SPARC
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* 32-bit and 64-bit ELF specifications say that
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* they should have relocation entries, but the
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* 32-bit SPARC binutils do not generate them,
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* and now the 64-bit SPARC binutils have stopped
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* generating them too.
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*
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* So, to provide binary compatibility, we will
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* check the first entry, if it is reserved it
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* should not be of the type JMP_SLOT. If it
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* is JMP_SLOT, then the 4 reserved entries were
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* not generated and our index is 4 entries too far.
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*/
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rela -= 4;
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}
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#endif
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}
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if (_rtld_relocate_plt_object(obj, rela, &addr, true) < 0)
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_rtld_die();
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return addr;
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}
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/*
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* Relocate newly-loaded shared objects. The argument is a pointer to
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* the Obj_Entry for the first such object. All objects from the first
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* to the end of the list of objects are relocated. Returns 0 on success,
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* or -1 on failure.
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*/
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int
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_rtld_relocate_objects(first, bind_now, dodebug)
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Obj_Entry *first;
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bool bind_now;
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bool dodebug;
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{
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Obj_Entry *obj;
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int ok = 1;
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for (obj = first; obj != NULL; obj = obj->next) {
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if (obj->nbuckets == 0 || obj->nchains == 0 ||
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obj->buckets == NULL || obj->symtab == NULL ||
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obj->strtab == NULL) {
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_rtld_error("%s: Shared object has no run-time"
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" symbol table", obj->path);
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return -1;
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}
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rdbg(dodebug, (" relocating %s (%ld/%ld rel/rela, "
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"%ld/%ld plt rel/rela)",
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obj->path,
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(long)(obj->rellim - obj->rel),
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(long)(obj->relalim - obj->rela),
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(long)(obj->pltrellim - obj->pltrel),
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(long)(obj->pltrelalim - obj->pltrela)));
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if (obj->textrel) {
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/*
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* There are relocations to the write-protected text
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* segment.
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*/
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if (mprotect(obj->mapbase, obj->textsize,
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PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
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_rtld_error("%s: Cannot write-enable text "
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"segment: %s", obj->path, xstrerror(errno));
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return -1;
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}
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}
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if (_rtld_relocate_nonplt_objects(obj, dodebug) < 0)
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ok = 0;
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if (obj->textrel) { /* Re-protected the text segment. */
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if (mprotect(obj->mapbase, obj->textsize,
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PROT_READ | PROT_EXEC) == -1) {
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_rtld_error("%s: Cannot write-protect text "
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"segment: %s", obj->path, xstrerror(errno));
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return -1;
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}
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}
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if (_rtld_relocate_plt_lazy(obj, dodebug) < 0)
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ok = 0;
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#if 0
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if (bind_now)
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if (_rtld_relocate_plt_object(obj, dodebug) < 0)
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ok = 0;
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#endif
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if (!ok)
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return -1;
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/* Set some sanity-checking numbers in the Obj_Entry. */
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obj->magic = RTLD_MAGIC;
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obj->version = RTLD_VERSION;
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/* Fill in the dynamic linker entry points. */
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obj->dlopen = _rtld_dlopen;
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obj->dlsym = _rtld_dlsym;
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obj->dlerror = _rtld_dlerror;
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obj->dlclose = _rtld_dlclose;
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obj->dladdr = _rtld_dladdr;
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/* Set the special PLTGOT entries. */
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if (obj->pltgot != NULL)
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_rtld_setup_pltgot(obj);
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}
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return 0;
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}
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