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|
/* vi: set sw=4 ts=4: */
/*
* Program to load an ELF binary on a linux system, and run it
* after resolving ELF shared library symbols
*
* Copyright (C) 2000-2004 by Erik Andersen <andersen@codepoet.org>
* Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
* David Engel, Hongjiu Lu and Mitch D'Souza
*
* 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. The name of the above contributors may not be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE 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 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 <ldso.h>
#include <stdio.h>
#if defined (__LIBDL_SHARED__)
/* When libdl is loaded as a shared library, we need to load in
* and use a pile of symbols from ldso... */
extern char *_dl_find_hash(const char *, struct dyn_elf *, struct elf_resolve *, int)
__attribute__ ((__weak__));
extern struct elf_resolve * _dl_load_shared_library(int, struct dyn_elf **,
struct elf_resolve *, char *, int) __attribute__ ((__weak__));
extern struct elf_resolve * _dl_check_if_named_library_is_loaded(const char *, int)
__attribute__ ((__weak__));
extern int _dl_fixup(struct dyn_elf *rpnt, int lazy)
__attribute__ ((__weak__));
extern void _dl_protect_relro(struct elf_resolve * tpnt)
__attribute__ ((__weak__));
extern int _dl_errno __attribute__ ((__weak__));
extern struct dyn_elf *_dl_symbol_tables __attribute__ ((__weak__));
extern struct dyn_elf *_dl_handles __attribute__ ((__weak__));
extern struct elf_resolve *_dl_loaded_modules __attribute__ ((__weak__));
extern struct r_debug *_dl_debug_addr __attribute__ ((__weak__));
extern unsigned long _dl_error_number __attribute__ ((__weak__));
extern void *(*_dl_malloc_function)(size_t) __attribute__ ((__weak__));
#ifdef __LDSO_CACHE_SUPPORT__
int _dl_map_cache(void) __attribute__ ((__weak__));
int _dl_unmap_cache(void) __attribute__ ((__weak__));
#endif
#ifdef __mips__
extern void _dl_perform_mips_global_got_relocations(struct elf_resolve *tpnt, int lazy)
__attribute__ ((__weak__));
#endif
#ifdef __SUPPORT_LD_DEBUG__
extern char *_dl_debug __attribute__ ((__weak__));
#endif
#else /* __LIBDL_SHARED__ */
/* When libdl is linked as a static library, we need to replace all
* the symbols that otherwise would have been loaded in from ldso... */
#ifdef __SUPPORT_LD_DEBUG__
char *_dl_debug = 0;
#endif
char *_dl_library_path = 0; /* Where we look for libraries */
char *_dl_ldsopath = 0; /* Location of the shared lib loader */
int _dl_errno = 0; /* We can't use the real errno in ldso */
size_t _dl_pagesize = PAGE_SIZE; /* Store the page size for use later */
/* This global variable is also to communicate with debuggers such as gdb. */
struct r_debug *_dl_debug_addr = NULL;
#define _dl_malloc malloc
#include "dl-progname.h"
#include "../ldso/dl-hash.c"
#define _dl_trace_loaded_objects 0
#include "../ldso/dl-elf.c"
#endif
static int do_dlclose(void *, int need_fini);
static const char *dl_error_names[] = {
"",
"File not found",
"Unable to open /dev/zero",
"Not an ELF file",
#if defined (__i386__)
"Not i386 binary",
#elif defined (__sparc__)
"Not sparc binary",
#elif defined (__mc68000__)
"Not m68k binary",
#else
"Unrecognized binary type",
#endif
"Not an ELF shared library",
"Unable to mmap file",
"No dynamic section",
#ifdef ELF_USES_RELOCA
"Unable to process REL relocs",
#else
"Unable to process RELA relocs",
#endif
"Bad handle",
"Unable to resolve symbol"
};
void __attribute__ ((destructor)) dl_cleanup(void)
{
struct dyn_elf *d;
for (d = _dl_handles; d; d = d->next_handle) {
do_dlclose(d, 1);
}
}
void *dlopen(const char *libname, int flag)
{
struct elf_resolve *tpnt, *tfrom, *tcurr;
struct dyn_elf *dyn_chain, *rpnt = NULL, *dyn_ptr, *relro_ptr;
struct dyn_elf *dpnt;
ElfW(Addr) from;
struct elf_resolve *tpnt1;
void (*dl_brk) (void);
int now_flag;
struct init_fini_list *tmp, *runp;
int nlist, i;
struct elf_resolve **init_fini_list;
/* A bit of sanity checking... */
if (!(flag & (RTLD_LAZY|RTLD_NOW))) {
_dl_error_number = LD_BAD_HANDLE;
return NULL;
}
from = (ElfW(Addr)) __builtin_return_address(0);
/* Cover the trivial case first */
if (!libname)
return _dl_symbol_tables;
_dl_map_cache();
/*
* Try and locate the module we were called from - we
* need this so that we get the correct RPATH. Note that
* this is the current behavior under Solaris, but the
* ABI+ specifies that we should only use the RPATH from
* the application. Thus this may go away at some time
* in the future.
*/
tfrom = NULL;
for (dpnt = _dl_symbol_tables; dpnt; dpnt = dpnt->next) {
tpnt = dpnt->dyn;
if (tpnt->loadaddr < from
&& (tfrom == NULL || tfrom->loadaddr < tpnt->loadaddr))
tfrom = tpnt;
}
for(rpnt = _dl_symbol_tables; rpnt->next; rpnt=rpnt->next);
relro_ptr = rpnt;
/* Try to load the specified library */
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "Trying to dlopen '%s'\n", (char*)libname);
#endif
tpnt = _dl_check_if_named_library_is_loaded((char *)libname, 0);
if (!(tpnt))
tpnt = _dl_load_shared_library(0, &rpnt, tfrom, (char*)libname, 0);
else
tpnt->usage_count++;
if (tpnt == NULL) {
_dl_unmap_cache();
return NULL;
}
dyn_chain = (struct dyn_elf *) malloc(sizeof(struct dyn_elf));
_dl_memset(dyn_chain, 0, sizeof(struct dyn_elf));
dyn_chain->dyn = tpnt;
tpnt->rtld_flags |= (flag & RTLD_GLOBAL);
dyn_chain->next_handle = _dl_handles;
_dl_handles = dyn_ptr = dyn_chain;
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "Looking for needed libraries\n");
#endif
nlist = 0;
for (tcurr = tpnt; tcurr; tcurr = tcurr->next)
{
Elf32_Dyn *dpnt;
char *lpntstr;
nlist++;
tcurr->init_fini = NULL; /* clear any previous dependcies */
for (dpnt = (Elf32_Dyn *) tcurr->dynamic_addr; dpnt->d_tag; dpnt++) {
if (dpnt->d_tag == DT_NEEDED) {
char *name;
lpntstr = (char*) (tcurr->loadaddr + tcurr->dynamic_info[DT_STRTAB] +
dpnt->d_un.d_val);
name = _dl_get_last_path_component(lpntstr);
tpnt1 = _dl_check_if_named_library_is_loaded(name, 0);
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "Trying to load '%s', needed by '%s'\n",
lpntstr, tcurr->libname);
#endif
if (tpnt1) {
tpnt1->usage_count++;
} else {
tpnt1 = _dl_load_shared_library(0, &rpnt, tcurr, lpntstr, 0);
if (!tpnt1)
goto oops;
}
tpnt1->rtld_flags |= (flag & RTLD_GLOBAL);
dyn_ptr->next = (struct dyn_elf *) malloc(sizeof(struct dyn_elf));
_dl_memset (dyn_ptr->next, 0, sizeof (struct dyn_elf));
dyn_ptr = dyn_ptr->next;
dyn_ptr->dyn = tpnt1;
tmp = alloca(sizeof(struct init_fini_list)); /* Allocates on stack, no need to free this memory */
tmp->tpnt = tpnt1;
tmp->next = tcurr->init_fini;
tcurr->init_fini = tmp;
}
}
}
init_fini_list = malloc(nlist * sizeof(struct elf_resolve *));
dyn_chain->init_fini.init_fini = init_fini_list;
dyn_chain->init_fini.nlist = nlist;
i = 0;
for (tcurr = tpnt; tcurr; tcurr = tcurr->next) {
init_fini_list[i++] = tcurr;
for(runp = tcurr->init_fini; runp; runp = runp->next){
if (!(runp->tpnt->rtld_flags & RTLD_GLOBAL)) {
tmp = malloc(sizeof(struct init_fini_list));
tmp->tpnt = runp->tpnt;
tmp->next = tcurr->rtld_local;
tcurr->rtld_local = tmp;
}
}
}
/* Sort the INIT/FINI list in dependency order. */
for (tcurr = tpnt; tcurr; tcurr = tcurr->next) {
int j, k;
for (j = 0; init_fini_list[j] != tcurr; ++j)
/* Empty */;
for (k = j + 1; k < nlist; ++k) {
struct init_fini_list *runp = init_fini_list[k]->init_fini;
for (; runp; runp = runp->next) {
if (runp->tpnt == tcurr) {
struct elf_resolve *here = init_fini_list[k];
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "Move %s from pos %d to %d in INIT/FINI list.\n", here->libname, k, j);
#endif
for (i = (k - j); i; --i)
init_fini_list[i+j] = init_fini_list[i+j-1];
init_fini_list[j] = here;
++j;
break;
}
}
}
}
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug) {
fprintf(stderr, "\nINIT/FINI order and dependencies:\n");
for (i=0;i < nlist;i++) {
fprintf(stderr, "lib: %s has deps:\n", init_fini_list[i]->libname);
runp = init_fini_list[i]->init_fini;
for ( ;runp; runp = runp->next)
printf(" %s ", runp->tpnt->libname);
printf("\n");
}
}
#endif
if (dyn_chain->dyn->init_flag & INIT_FUNCS_CALLED) {
/* If the init and fini stuff has already been run, that means
* the dlopen'd library has already been loaded, and nothing
* further needs to be done. */
return (void *) dyn_chain;
}
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "Beginning dlopen relocation fixups\n");
#endif
/*
* OK, now all of the kids are tucked into bed in their proper addresses.
* Now we go through and look for REL and RELA records that indicate fixups
* to the GOT tables. We need to do this in reverse order so that COPY
* directives work correctly */
now_flag = (flag & RTLD_NOW) ? RTLD_NOW : 0;
if (getenv("LD_BIND_NOW"))
now_flag = RTLD_NOW;
#ifdef __mips__
/*
* Relocation of the GOT entries for MIPS have to be done
* after all the libraries have been loaded.
*/
_dl_perform_mips_global_got_relocations(tpnt, !now_flag);
#endif
if (_dl_fixup(dyn_chain, now_flag))
goto oops;
for (rpnt = relro_ptr->next; rpnt; rpnt = rpnt->next) {
if (rpnt->dyn->relro_size)
_dl_protect_relro(rpnt->dyn);
}
/* TODO: Should we set the protections of all pages back to R/O now ? */
/* Notify the debugger we have added some objects. */
if (_dl_debug_addr) {
dl_brk = (void (*)(void)) _dl_debug_addr->r_brk;
if (dl_brk != NULL) {
_dl_debug_addr->r_state = RT_ADD;
(*dl_brk) ();
_dl_debug_addr->r_state = RT_CONSISTENT;
(*dl_brk) ();
}
}
#if defined (__LIBDL_SHARED__)
/* Run the ctors and setup the dtors */
for (i = nlist; i; --i) {
tpnt = init_fini_list[i-1];
if (tpnt->init_flag & INIT_FUNCS_CALLED)
continue;
tpnt->init_flag |= INIT_FUNCS_CALLED;
if (tpnt->dynamic_info[DT_INIT]) {
void (*dl_elf_func) (void);
dl_elf_func = (void (*)(void)) (tpnt->loadaddr + tpnt->dynamic_info[DT_INIT]);
if (dl_elf_func && *dl_elf_func != NULL) {
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "running ctors for library %s at '%x'\n", tpnt->libname, dl_elf_func);
#endif
(*dl_elf_func) ();
}
}
}
#endif
_dl_unmap_cache();
return (void *) dyn_chain;
oops:
/* Something went wrong. Clean up and return NULL. */
_dl_unmap_cache();
do_dlclose(dyn_chain, 0);
return NULL;
}
void *dlsym(void *vhandle, const char *name)
{
struct elf_resolve *tpnt, *tfrom;
struct dyn_elf *handle;
ElfW(Addr) from;
struct dyn_elf *rpnt;
void *ret;
handle = (struct dyn_elf *) vhandle;
/* First of all verify that we have a real handle
of some kind. Return NULL if not a valid handle. */
if (handle == NULL)
handle = _dl_symbol_tables;
else if (handle != RTLD_NEXT && handle != _dl_symbol_tables) {
for (rpnt = _dl_handles; rpnt; rpnt = rpnt->next_handle)
if (rpnt == handle)
break;
if (!rpnt) {
_dl_error_number = LD_BAD_HANDLE;
return NULL;
}
} else if (handle == RTLD_NEXT) {
/*
* Try and locate the module we were called from - we
* need this so that we know where to start searching
* from. We never pass RTLD_NEXT down into the actual
* dynamic loader itself, as it doesn't know
* how to properly treat it.
*/
from = (ElfW(Addr)) __builtin_return_address(0);
tfrom = NULL;
for (rpnt = _dl_symbol_tables; rpnt; rpnt = rpnt->next) {
tpnt = rpnt->dyn;
if (tpnt->loadaddr < from
&& (tfrom == NULL || tfrom->loadaddr < tpnt->loadaddr)) {
tfrom = tpnt;
handle = rpnt->next;
}
}
}
ret = _dl_find_hash((char*)name, handle, NULL, 0);
/*
* Nothing found.
*/
if (!ret)
_dl_error_number = LD_NO_SYMBOL;
return ret;
}
static int do_dlclose(void *vhandle, int need_fini)
{
struct dyn_elf *rpnt, *rpnt1;
struct init_fini_list *runp, *tmp;
ElfW(Phdr) *ppnt;
struct elf_resolve *tpnt;
int (*dl_elf_fini) (void);
void (*dl_brk) (void);
struct dyn_elf *handle;
unsigned int end;
int i = 0;
handle = (struct dyn_elf *) vhandle;
rpnt1 = NULL;
for (rpnt = _dl_handles; rpnt; rpnt = rpnt->next_handle) {
if (rpnt == handle)
break;
rpnt1 = rpnt;
}
if (!rpnt) {
_dl_error_number = LD_BAD_HANDLE;
return 1;
}
if (rpnt1)
rpnt1->next_handle = rpnt->next_handle;
else
_dl_handles = rpnt->next_handle;
if (need_fini) {
for (i = 0; i < handle->init_fini.nlist; ++i) {
tpnt = handle->init_fini.init_fini[i];
if (tpnt->dynamic_info[DT_FINI] && tpnt->usage_count == 1 &&
!(tpnt->init_flag & FINI_FUNCS_CALLED)) {
tpnt->init_flag |= FINI_FUNCS_CALLED;
dl_elf_fini = (int (*)(void)) (tpnt->loadaddr + tpnt->dynamic_info[DT_FINI]);
#ifdef __SUPPORT_LD_DEBUG__
if(_dl_debug)
fprintf(stderr, "running dtors for library %s at '%x'\n", tpnt->libname, dl_elf_fini);
#endif
(*dl_elf_fini) ();
}
}
}
if (handle->dyn->usage_count == 1)
free(handle->init_fini.init_fini);
/* OK, this is a valid handle - now close out the file */
for (rpnt = handle; rpnt; rpnt = rpnt->next) {
tpnt = rpnt->dyn;
if (--tpnt->usage_count == 0) {
end = 0;
for (i = 0, ppnt = tpnt->ppnt;
i < tpnt->n_phent; ppnt++, i++) {
if (ppnt->p_type != PT_LOAD)
continue;
if (end < ppnt->p_vaddr + ppnt->p_memsz)
end = ppnt->p_vaddr + ppnt->p_memsz;
}
_dl_munmap((void*)tpnt->loadaddr, end);
/* Free elements in RTLD_LOCAL scope list */
for (runp = tpnt->rtld_local; runp; runp = tmp) {
tmp = runp->next;
free(runp);
}
/* Next, remove tpnt from the loaded_module list */
if (_dl_loaded_modules == tpnt) {
_dl_loaded_modules = tpnt->next;
if (_dl_loaded_modules)
_dl_loaded_modules->prev = 0;
} else
for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next)
if (tpnt->next == rpnt->dyn) {
tpnt->next = tpnt->next->next;
if (tpnt->next)
tpnt->next->prev = tpnt;
break;
}
/* Next, remove tpnt from the global symbol table list */
if (_dl_symbol_tables->dyn == rpnt->dyn) {
_dl_symbol_tables = rpnt->next;
if (_dl_symbol_tables)
_dl_symbol_tables->prev = 0;
} else
for (rpnt1 = _dl_symbol_tables; rpnt1->next; rpnt1 = rpnt1->next) {
if (rpnt1->next->dyn == rpnt->dyn) {
free(rpnt1->next);
rpnt1->next = rpnt1->next->next;
if (rpnt1->next)
rpnt1->next->prev = rpnt1;
break;
}
}
free(rpnt->dyn->libname);
free(rpnt->dyn);
}
free(rpnt);
}
if (_dl_debug_addr) {
dl_brk = (void (*)(void)) _dl_debug_addr->r_brk;
if (dl_brk != NULL) {
_dl_debug_addr->r_state = RT_DELETE;
(*dl_brk) ();
_dl_debug_addr->r_state = RT_CONSISTENT;
(*dl_brk) ();
}
}
return 0;
}
int dlclose(void *vhandle)
{
return do_dlclose(vhandle, 1);
}
const char *dlerror(void)
{
const char *retval;
if (!_dl_error_number)
return NULL;
retval = dl_error_names[_dl_error_number];
_dl_error_number = 0;
return retval;
}
/*
* Dump information to stderrr about the current loaded modules
*/
static char *type[] = { "Lib", "Exe", "Int", "Mod" };
void dlinfo(void)
{
struct elf_resolve *tpnt;
struct dyn_elf *rpnt, *hpnt;
fprintf(stderr, "List of loaded modules\n");
/* First start with a complete list of all of the loaded files. */
for (tpnt = _dl_loaded_modules; tpnt; tpnt = tpnt->next) {
fprintf(stderr, "\t%x %x %x %s %d %s\n",
(unsigned) tpnt->loadaddr, (unsigned) tpnt,
(unsigned) tpnt->symbol_scope,
type[tpnt->libtype],
tpnt->usage_count, tpnt->libname);
}
/* Next dump the module list for the application itself */
fprintf(stderr, "\nModules for application (%x):\n",
(unsigned) _dl_symbol_tables);
for (rpnt = _dl_symbol_tables; rpnt; rpnt = rpnt->next)
fprintf(stderr, "\t%x %s\n", (unsigned) rpnt->dyn, rpnt->dyn->libname);
for (hpnt = _dl_handles; hpnt; hpnt = hpnt->next_handle) {
fprintf(stderr, "Modules for handle %x\n", (unsigned) hpnt);
for (rpnt = hpnt; rpnt; rpnt = rpnt->next)
fprintf(stderr, "\t%x %s\n", (unsigned) rpnt->dyn,
rpnt->dyn->libname);
}
}
int dladdr(const void *__address, Dl_info * __info)
{
struct elf_resolve *pelf;
struct elf_resolve *rpnt;
_dl_map_cache();
/*
* Try and locate the module address is in
*/
pelf = NULL;
#if 0
fprintf(stderr, "dladdr( %x, %x )\n", __address, __info);
#endif
for (rpnt = _dl_loaded_modules; rpnt; rpnt = rpnt->next) {
struct elf_resolve *tpnt;
tpnt = rpnt;
#if 0
fprintf(stderr, "Module \"%s\" at %x\n",
tpnt->libname, tpnt->loadaddr);
#endif
if (tpnt->loadaddr < (ElfW(Addr)) __address
&& (pelf == NULL || pelf->loadaddr < tpnt->loadaddr)) {
pelf = tpnt;
}
}
if (!pelf) {
return 0;
}
/*
* Try and locate the symbol of address
*/
{
char *strtab;
Elf32_Sym *symtab;
int hn, si;
int sf;
int sn = 0;
ElfW(Addr) sa;
sa = 0;
symtab = (Elf32_Sym *) (pelf->dynamic_info[DT_SYMTAB] + pelf->loadaddr);
strtab = (char *) (pelf->dynamic_info[DT_STRTAB] + pelf->loadaddr);
sf = 0;
for (hn = 0; hn < pelf->nbucket; hn++) {
for (si = pelf->elf_buckets[hn]; si; si = pelf->chains[si]) {
ElfW(Addr) symbol_addr;
symbol_addr = pelf->loadaddr + symtab[si].st_value;
if (symbol_addr <= (ElfW(Addr))__address && (!sf || sa < symbol_addr)) {
sa = symbol_addr;
sn = si;
sf = 1;
}
#if 0
fprintf(stderr, "Symbol \"%s\" at %x\n",
strtab + symtab[si].st_name, symbol_addr);
#endif
}
}
if (sf) {
__info->dli_fname = pelf->libname;
__info->dli_fbase = (void *)pelf->loadaddr;
__info->dli_sname = strtab + symtab[sn].st_name;
__info->dli_saddr = (void *)sa;
}
return 1;
}
}
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