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/* $NetBSD: reloc.c,v 1.107 2014/08/25 20:40:52 joerg Exp $ */
/*
* Copyright 1996 John D. Polstra.
* Copyright 1996 Matt Thomas <matt@3am-software.com>
* All rights reserved.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Polstra.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
/*
* Dynamic linker for ELF.
*
* John Polstra <jdp@polstra.com>.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: reloc.c,v 1.107 2014/08/25 20:40:52 joerg Exp $");
#endif /* not lint */
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/bitops.h>
#include <dirent.h>
#include "debug.h"
#include "rtld.h"
#ifndef RTLD_INHIBIT_COPY_RELOCS
static int _rtld_do_copy_relocation(const Obj_Entry *, const Elf_Rela *);
static int
_rtld_do_copy_relocation(const Obj_Entry *dstobj, const Elf_Rela *rela)
{
void *dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
const Elf_Sym *dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
const char *name = dstobj->strtab + dstsym->st_name;
unsigned long hash = _rtld_elf_hash(name);
size_t size = dstsym->st_size;
const void *srcaddr;
const Elf_Sym *srcsym = NULL;
Obj_Entry *srcobj;
for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) {
srcsym = _rtld_symlook_obj(name, hash, srcobj, 0,
_rtld_fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)));
if (srcsym != NULL)
break;
}
if (srcobj == NULL) {
_rtld_error("Undefined symbol \"%s\" referenced from COPY"
" relocation in %s", name, dstobj->path);
return (-1);
}
srcaddr = (const void *)(srcobj->relocbase + srcsym->st_value);
(void)memcpy(dstaddr, srcaddr, size);
rdbg(("COPY %s %s %s --> src=%p dst=%p size %ld",
dstobj->path, srcobj->path, name, srcaddr,
(void *)dstaddr, (long)size));
return (0);
}
#endif /* RTLD_INHIBIT_COPY_RELOCS */
/*
* Process the special R_xxx_COPY relocations in the main program. These
* copy data from a shared object into a region in the main program's BSS
* segment.
*
* Returns 0 on success, -1 on failure.
*/
int
_rtld_do_copy_relocations(const Obj_Entry *dstobj)
{
#ifndef RTLD_INHIBIT_COPY_RELOCS
/* COPY relocations are invalid elsewhere */
assert(!dstobj->isdynamic);
if (dstobj->rel != NULL) {
const Elf_Rel *rel;
for (rel = dstobj->rel; rel < dstobj->rellim; ++rel) {
if (ELF_R_TYPE(rel->r_info) == R_TYPE(COPY)) {
Elf_Rela ourrela;
ourrela.r_info = rel->r_info;
ourrela.r_offset = rel->r_offset;
ourrela.r_addend = 0;
if (_rtld_do_copy_relocation(dstobj,
&ourrela) < 0)
return (-1);
}
}
}
if (dstobj->rela != NULL) {
const Elf_Rela *rela;
for (rela = dstobj->rela; rela < dstobj->relalim; ++rela) {
if (ELF_R_TYPE(rela->r_info) == R_TYPE(COPY)) {
if (_rtld_do_copy_relocation(dstobj, rela) < 0)
return (-1);
}
}
}
#endif /* RTLD_INHIBIT_COPY_RELOCS */
return (0);
}
/*
* Relocate newly-loaded shared objects. The argument is a pointer to
* the Obj_Entry for the first such object. All objects from the first
* to the end of the list of objects are relocated. Returns 0 on success,
* or -1 on failure.
*/
int
_rtld_relocate_objects(Obj_Entry *first, bool bind_now)
{
Obj_Entry *obj;
int ok = 1;
for (obj = first; obj != NULL; obj = obj->next) {
if (obj->nbuckets == 0 || obj->nchains == 0 ||
obj->buckets == NULL || obj->symtab == NULL ||
obj->strtab == NULL) {
_rtld_error("%s: Shared object has no run-time"
" symbol table", obj->path);
return -1;
}
if (obj->nbuckets == UINT32_MAX) {
_rtld_error("%s: Symbol table too large", obj->path);
return -1;
}
rdbg((" relocating %s (%ld/%ld rel/rela, %ld/%ld plt rel/rela)",
obj->path,
(long)(obj->rellim - obj->rel),
(long)(obj->relalim - obj->rela),
(long)(obj->pltrellim - obj->pltrel),
(long)(obj->pltrelalim - obj->pltrela)));
#if !defined(__minix)
if (obj->textrel) {
/*
* There are relocations to the write-protected text
* segment.
*/
if (mprotect(obj->mapbase, obj->textsize,
PROT_READ | PROT_WRITE | PROT_EXEC) == -1) {
_rtld_error("%s: Cannot write-enable text "
"segment: %s", obj->path, xstrerror(errno));
return -1;
}
}
#endif /* !defined(__minix) */
dbg(("doing non-PLT relocations"));
if (_rtld_relocate_nonplt_objects(obj) < 0)
ok = 0;
#if !defined(__minix)
if (obj->textrel) { /* Re-protected the text segment. */
if (mprotect(obj->mapbase, obj->textsize,
PROT_READ | PROT_EXEC) == -1) {
_rtld_error("%s: Cannot write-protect text "
"segment: %s", obj->path, xstrerror(errno));
return -1;
}
}
#endif /* !defined(__minix) */
dbg(("doing lazy PLT binding"));
if (_rtld_relocate_plt_lazy(obj) < 0)
ok = 0;
if (obj->z_now || bind_now) {
dbg(("doing immediate PLT binding"));
if (_rtld_relocate_plt_objects(obj) < 0)
ok = 0;
}
if (!ok)
return -1;
/* Set some sanity-checking numbers in the Obj_Entry. */
obj->magic = RTLD_MAGIC;
obj->version = RTLD_VERSION;
/*
* Fill in the backwards compatibility dynamic linker entry points.
*
* DO NOT ADD TO THIS LIST
*/
obj->dlopen = dlopen;
obj->dlsym = dlsym;
obj->dlerror = dlerror;
obj->dlclose = dlclose;
obj->dladdr = dladdr;
dbg(("fixing up PLTGOT"));
/* Set the special PLTGOT entries. */
if (obj->pltgot != NULL)
_rtld_setup_pltgot(obj);
}
return 0;
}
Elf_Addr
_rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
{
Elf_Addr target;
_rtld_shared_exit();
target = _rtld_call_function_addr(obj,
(Elf_Addr)obj->relocbase + def->st_value);
_rtld_shared_enter();
return target;
}
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