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|
/* $OpenBSD: resolve.c,v 1.59 2012/07/06 23:15:50 matthew Exp $ */
/*
* Copyright (c) 1998 Per Fogelstrom, Opsycon AB
*
* 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 ``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.
*
*/
#define _DYN_LOADER
#include <sys/types.h>
#include <nlist.h>
#include <link.h>
#include "syscall.h"
#include "archdep.h"
#include "resolve.h"
#include "dl_prebind.h"
elf_object_t *_dl_objects;
elf_object_t *_dl_last_object;
elf_object_t *_dl_loading_object;
/*
* Add a new dynamic object to the object list.
*/
void
_dl_add_object(elf_object_t *object)
{
/* if a .so is marked nodelete, then add a reference */
if (object->obj_flags & DF_1_NODELETE &&
(object->status & STAT_NODELETE) == 0) {
DL_DEB(("objname %s is nodelete\n", object->load_name));
object->refcount++;
object->status |= STAT_NODELETE;
}
/*
* if this is a new object, prev will be NULL
* != NULL if an object already in the list
* prev == NULL for the first item in the list, but that will
* be the executable.
*/
if (object->prev != NULL)
return;
if (_dl_objects == NULL) { /* First object ? */
_dl_last_object = _dl_objects = object;
} else {
_dl_last_object->next = object;
object->prev = _dl_last_object;
_dl_last_object = object;
}
}
/*
* Initialize a new dynamic object.
*/
elf_object_t *
_dl_finalize_object(const char *objname, Elf_Dyn *dynp, Elf_Phdr *phdrp,
int phdrc, const int objtype, const long lbase, const long obase)
{
elf_object_t *object;
#if 0
_dl_printf("objname [%s], dynp %p, objtype %x lbase %lx, obase %lx\n",
objname, dynp, objtype, lbase, obase);
#endif
object = _dl_malloc(sizeof(elf_object_t));
object->prev = object->next = NULL;
object->load_dyn = dynp;
while (dynp->d_tag != DT_NULL) {
if (dynp->d_tag < DT_NUM)
object->Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
else if (dynp->d_tag >= DT_LOPROC &&
dynp->d_tag < DT_LOPROC + DT_PROCNUM)
object->Dyn.info[dynp->d_tag + DT_NUM - DT_LOPROC] =
dynp->d_un.d_val;
if (dynp->d_tag == DT_TEXTREL)
object->dyn.textrel = 1;
if (dynp->d_tag == DT_SYMBOLIC)
object->dyn.symbolic = 1;
if (dynp->d_tag == DT_BIND_NOW)
object->obj_flags |= DF_1_NOW;
if (dynp->d_tag == DT_FLAGS_1)
object->obj_flags |= dynp->d_un.d_val;
dynp++;
}
DL_DEB((" flags %s = 0x%x\n", objname, object->obj_flags ));
object->obj_type = objtype;
if (_dl_loading_object == NULL) {
/*
* no loading object, object is the loading object,
* as it is either executable, or dlopened()
*/
_dl_loading_object = object;
}
if ((object->obj_flags & DF_1_NOOPEN) != 0 &&
_dl_loading_object->obj_type == OBJTYPE_DLO &&
_dl_traceld == NULL) {
_dl_free(object);
_dl_errno = DL_CANT_LOAD_OBJ;
return(NULL);
}
/*
* Now relocate all pointer to dynamic info, but only
* the ones which have pointer values.
*/
if (object->Dyn.info[DT_PLTGOT])
object->Dyn.info[DT_PLTGOT] += obase;
if (object->Dyn.info[DT_HASH])
object->Dyn.info[DT_HASH] += obase;
if (object->Dyn.info[DT_STRTAB])
object->Dyn.info[DT_STRTAB] += obase;
if (object->Dyn.info[DT_SYMTAB])
object->Dyn.info[DT_SYMTAB] += obase;
if (object->Dyn.info[DT_RELA])
object->Dyn.info[DT_RELA] += obase;
if (object->Dyn.info[DT_SONAME])
object->Dyn.info[DT_SONAME] += object->Dyn.info[DT_STRTAB];
if (object->Dyn.info[DT_RPATH])
object->Dyn.info[DT_RPATH] += object->Dyn.info[DT_STRTAB];
if (object->Dyn.info[DT_REL])
object->Dyn.info[DT_REL] += obase;
if (object->Dyn.info[DT_INIT])
object->Dyn.info[DT_INIT] += obase;
if (object->Dyn.info[DT_FINI])
object->Dyn.info[DT_FINI] += obase;
if (object->Dyn.info[DT_JMPREL])
object->Dyn.info[DT_JMPREL] += obase;
if (object->Dyn.info[DT_HASH] != 0) {
Elf_Word *hashtab = (Elf_Word *)object->Dyn.info[DT_HASH];
object->nbuckets = hashtab[0];
object->nchains = hashtab[1];
object->buckets = hashtab + 2;
object->chains = object->buckets + object->nbuckets;
}
object->phdrp = phdrp;
object->phdrc = phdrc;
object->load_base = lbase;
object->obj_base = obase;
object->load_name = _dl_strdup(objname);
object->load_object = _dl_loading_object;
if (object->load_object == object)
DL_DEB(("head %s\n", object->load_name));
DL_DEB(("obj %s has %s as head\n", object->load_name,
_dl_loading_object->load_name ));
object->refcount = 0;
TAILQ_INIT(&object->child_list);
object->opencount = 0; /* # dlopen() & exe */
object->grprefcount = 0;
/* default dev, inode for dlopen-able objects. */
object->dev = 0;
object->inode = 0;
object->lastlookup = 0;
TAILQ_INIT(&object->grpsym_list);
TAILQ_INIT(&object->grpref_list);
return(object);
}
void
_dl_tailq_free(struct dep_node *n)
{
struct dep_node *next;
while (n != NULL) {
next = TAILQ_NEXT(n, next_sib);
_dl_free(n);
n = next;
}
}
elf_object_t *free_objects;
void _dl_cleanup_objects(void);
void
_dl_cleanup_objects()
{
elf_object_t *nobj, *head;
struct dep_node *n, *next;
n = TAILQ_FIRST(&_dlopened_child_list);
while (n != NULL) {
next = TAILQ_NEXT(n, next_sib);
if (OBJECT_DLREF_CNT(n->data) == 0) {
TAILQ_REMOVE(&_dlopened_child_list, n, next_sib);
_dl_free(n);
}
n = next;
}
head = free_objects;
free_objects = NULL;
while (head != NULL) {
if (head->load_name)
_dl_free(head->load_name);
if (head->sod.sod_name)
_dl_free((char *)head->sod.sod_name);
_dl_tailq_free(TAILQ_FIRST(&head->grpsym_list));
_dl_tailq_free(TAILQ_FIRST(&head->child_list));
_dl_tailq_free(TAILQ_FIRST(&head->grpref_list));
nobj = head->next;
_dl_free(head);
head = nobj;
}
}
void
_dl_remove_object(elf_object_t *object)
{
object->prev->next = object->next;
if (object->next)
object->next->prev = object->prev;
if (_dl_last_object == object)
_dl_last_object = object->prev;
object->next = free_objects;
free_objects = object;
}
int _dl_find_symbol_obj(elf_object_t *object, const char *name,
unsigned long hash, int flags, const Elf_Sym **ref,
const Elf_Sym **weak_sym,
elf_object_t **weak_object);
sym_cache *_dl_symcache;
int _dl_symcachestat_hits;
int _dl_symcachestat_lookups;
Elf_Addr
_dl_find_symbol_bysym(elf_object_t *req_obj, unsigned int symidx,
const Elf_Sym **this, int flags, const Elf_Sym *ref_sym, const elf_object_t **pobj)
{
Elf_Addr ret;
const Elf_Sym *sym;
const char *symn;
const elf_object_t *sobj;
_dl_symcachestat_lookups ++;
if (_dl_symcache != NULL &&
symidx < req_obj->nchains &&
_dl_symcache[symidx].obj != NULL &&
_dl_symcache[symidx].sym != NULL &&
_dl_symcache[symidx].flags == flags) {
_dl_symcachestat_hits++;
sobj = _dl_symcache[symidx].obj;
*this = _dl_symcache[symidx].sym;
if (pobj)
*pobj = sobj;
if (_dl_prebind_validate) /* XXX */
prebind_validate(req_obj, symidx, flags, ref_sym);
return sobj->obj_base;
}
sym = req_obj->dyn.symtab;
sym += symidx;
symn = req_obj->dyn.strtab + sym->st_name;
ret = _dl_find_symbol(symn, this, flags, ref_sym, req_obj, &sobj);
if (pobj)
*pobj = sobj;
if (_dl_symcache != NULL && symidx < req_obj->nchains) {
#if 0
DL_DEB(("cache miss %d %p %p, %p %p %s %s %d %d %s\n",
symidx,
_dl_symcache[symidx].sym, *this,
_dl_symcache[symidx].obj, sobj, sobj->load_name,
sobj->dyn.strtab + (*this)->st_name,
_dl_symcache[symidx].flags, flags, req_obj->load_name));
#endif
_dl_symcache[symidx].sym = *this;
_dl_symcache[symidx].obj = sobj;
_dl_symcache[symidx].flags = flags;
}
return ret;
}
int _dl_searchnum = 0;
void
_dl_newsymsearch(void)
{
_dl_searchnum += 1;
if (_dl_searchnum < 0) {
/*
* If the signed number rolls over, reset all counters so
* we dont get accidental collision.
*/
elf_object_t *walkobj;
for (walkobj = _dl_objects;
walkobj != NULL;
walkobj = walkobj->next) {
walkobj->lastlookup = 0;
}
_dl_searchnum = 1;
}
}
Elf_Addr
_dl_find_symbol(const char *name, const Elf_Sym **this,
int flags, const Elf_Sym *ref_sym, elf_object_t *req_obj,
const elf_object_t **pobj)
{
const Elf_Sym *weak_sym = NULL;
unsigned long h = 0;
const char *p = name;
elf_object_t *object = NULL, *weak_object = NULL;
int found = 0;
struct dep_node *n, *m;
while (*p) {
unsigned long g;
h = (h << 4) + *p++;
if ((g = h & 0xf0000000))
h ^= g >> 24;
h &= ~g;
}
if (req_obj->dyn.symbolic)
if (_dl_find_symbol_obj(req_obj, name, h, flags, this, &weak_sym,
&weak_object)) {
object = req_obj;
found = 1;
goto found;
}
if (flags & SYM_SEARCH_OBJ) {
if (_dl_find_symbol_obj(req_obj, name, h, flags, this,
&weak_sym, &weak_object)) {
object = req_obj;
found = 1;
}
} else if (flags & SYM_DLSYM) {
if (_dl_find_symbol_obj(req_obj, name, h, flags, this,
&weak_sym, &weak_object)) {
object = req_obj;
found = 1;
}
if (weak_object != NULL && found == 0) {
object=weak_object;
*this = weak_sym;
found = 1;
}
/* search dlopened obj and all children */
if (found == 0) {
TAILQ_FOREACH(n, &req_obj->load_object->grpsym_list,
next_sib) {
if (_dl_find_symbol_obj(n->data, name, h,
flags, this,
&weak_sym, &weak_object)) {
object = n->data;
found = 1;
break;
}
}
}
} else {
int skip = 0;
if ((flags & SYM_SEARCH_SELF) || (flags & SYM_SEARCH_NEXT))
skip = 1;
_dl_newsymsearch();
/*
* search dlopened objects: global or req_obj == dlopened_obj
* and and it's children
*/
TAILQ_FOREACH(n, &_dlopened_child_list, next_sib) {
if (((n->data->obj_flags & DF_1_GLOBAL) == 0) &&
(n->data != req_obj->load_object))
continue;
n->data->lastlookup_head = _dl_searchnum;
TAILQ_FOREACH(m, &n->data->grpsym_list, next_sib) {
if (skip == 1) {
if (m->data == req_obj) {
skip = 0;
if (flags & SYM_SEARCH_NEXT)
continue;
} else
continue;
}
if ((flags & SYM_SEARCH_OTHER) &&
(m->data == req_obj))
continue;
m->data->lastlookup = _dl_searchnum;
if (_dl_find_symbol_obj(m->data, name, h, flags,
this, &weak_sym, &weak_object)) {
object = m->data;
found = 1;
goto found;
}
}
}
}
found:
if (weak_object != NULL && found == 0) {
object=weak_object;
*this = weak_sym;
found = 1;
}
if (found == 0) {
if ((ref_sym == NULL ||
(ELF_ST_BIND(ref_sym->st_info) != STB_WEAK)) &&
(flags & SYM_WARNNOTFOUND))
_dl_printf("%s:%s: undefined symbol '%s'\n",
_dl_progname, req_obj->load_name, name);
return (0);
}
if (ref_sym != NULL && ref_sym->st_size != 0 &&
(ref_sym->st_size != (*this)->st_size) &&
(ELF_ST_TYPE((*this)->st_info) != STT_FUNC) ) {
_dl_printf("%s:%s: %s : WARNING: "
"symbol(%s) size mismatch, relink your program\n",
_dl_progname, req_obj->load_name,
object->load_name, name);
}
if (pobj)
*pobj = object;
return (object->obj_base);
}
int
_dl_find_symbol_obj(elf_object_t *object, const char *name, unsigned long hash,
int flags, const Elf_Sym **this, const Elf_Sym **weak_sym,
elf_object_t **weak_object)
{
const Elf_Sym *symt = object->dyn.symtab;
const char *strt = object->dyn.strtab;
long si;
const char *symn;
for (si = object->buckets[hash % object->nbuckets];
si != STN_UNDEF; si = object->chains[si]) {
const Elf_Sym *sym = symt + si;
if (sym->st_value == 0)
continue;
if (ELF_ST_TYPE(sym->st_info) != STT_NOTYPE &&
ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
ELF_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
symn = strt + sym->st_name;
if (sym != *this && _dl_strcmp(symn, name))
continue;
/* allow this symbol if we are referring to a function
* which has a value, even if section is UNDEF.
* this allows &func to refer to PLT as per the
* ELF spec. st_value is checked above.
* if flags has SYM_PLT set, we must have actual
* symbol, so this symbol is skipped.
*/
if (sym->st_shndx == SHN_UNDEF) {
if ((flags & SYM_PLT) || sym->st_value == 0 ||
ELF_ST_TYPE(sym->st_info) != STT_FUNC)
continue;
}
if (ELF_ST_BIND(sym->st_info) == STB_GLOBAL) {
*this = sym;
return 1;
} else if (ELF_ST_BIND(sym->st_info) == STB_WEAK) {
if (!*weak_sym) {
*weak_sym = sym;
*weak_object = object;
}
}
}
return 0;
}
void
_dl_debug_state(void)
{
/* Debugger stub */
}
|