File: [local] / src / libexec / ld.so / loader.c (download)
Revision 1.73, Mon Feb 23 20:47:39 2004 UTC (20 years, 3 months ago) by drahn
Branch: MAIN
CVS Tags: OPENBSD_3_5_BASE, OPENBSD_3_5 Changes since 1.72: +30 -1 lines
Set the user variable environ early in ld.so so that library constructors can
properly see the environment. Fixes problem with MALLOC_OPTIONS on dynamic
executables. ok deraadt@
|
/* $OpenBSD: loader.c,v 1.73 2004/02/23 20:47:39 drahn 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 <sys/mman.h>
#include <sys/exec.h>
#include <sys/param.h>
#include <sys/sysctl.h>
#include <nlist.h>
#include <string.h>
#include <link.h>
#include <dlfcn.h>
#include "syscall.h"
#include "archdep.h"
#include "resolve.h"
#include "sod.h"
#include "stdlib.h"
/*
* Local decls.
*/
static char *_dl_getenv(const char *, char **);
static void _dl_unsetenv(const char *, char **);
unsigned long _dl_boot(const char **, char **, const long, long *);
void _dl_debug_state(void);
void _dl_setup_env(char **);
void _dl_dtors(void);
void _dl_boot_bind(const long, long *, Elf_Dyn *);
void _dl_fixup_user_env(void);
const char *_dl_progname;
int _dl_pagesz;
char *_dl_libpath;
char *_dl_preload;
char *_dl_bindnow;
char *_dl_traceld;
char *_dl_debug;
char *_dl_showmap;
char *_dl_norandom;
struct r_debug *_dl_debug_map;
void _dl_dopreload(char *paths);
void
_dl_debug_state(void)
{
/* Debugger stub */
}
/*
* Routine to walk through all of the objects except the first
* (main executable).
*/
void
_dl_run_dtors(elf_object_t *object)
{
DL_DEB(("doing dtors: [%s]\n", object->load_name));
if (object->dyn.fini)
(*object->dyn.fini)();
if (object->next)
_dl_run_dtors(object->next);
}
void
_dl_dtors(void)
{
DL_DEB(("doing dtors\n"));
if (_dl_objects->next)
_dl_run_dtors(_dl_objects->next);
}
void
_dl_dopreload(char *paths)
{
char *cp, *dp;
elf_object_t *shlib;
dp = paths = _dl_strdup(paths);
if (dp == NULL) {
_dl_printf("preload: out of memory");
_dl_exit(1);
}
while ((cp = _dl_strsep(&dp, ":")) != NULL) {
shlib = _dl_load_shlib(cp, _dl_objects, OBJTYPE_LIB,
DL_LAZY|RTLD_GLOBAL);
if (shlib == NULL) {
_dl_printf("%s: can't load library '%s'\n",
_dl_progname, cp);
_dl_exit(4);
}
_dl_add_object(shlib);
_dl_link_sub(shlib, _dl_objects);
}
_dl_free(paths);
return;
}
/*
* grab interesting environment variables, zap bad env vars if
* issetugid
*/
char **_dl_so_envp;
void
_dl_setup_env(char **envp)
{
/*
* Get paths to various things we are going to use.
*/
_dl_libpath = _dl_getenv("LD_LIBRARY_PATH", envp);
_dl_preload = _dl_getenv("LD_PRELOAD", envp);
_dl_bindnow = _dl_getenv("LD_BIND_NOW", envp);
_dl_traceld = _dl_getenv("LD_TRACE_LOADED_OBJECTS", envp);
_dl_debug = _dl_getenv("LD_DEBUG", envp);
_dl_norandom = _dl_getenv("LD_NORANDOM", envp);
/*
* Don't allow someone to change the search paths if he runs
* a suid program without credentials high enough.
*/
if (_dl_issetugid()) { /* Zap paths if s[ug]id... */
if (_dl_libpath) {
_dl_libpath = NULL;
_dl_unsetenv("LD_LIBRARY_PATH", envp);
}
if (_dl_preload) {
_dl_preload = NULL;
_dl_unsetenv("LD_PRELOAD", envp);
}
if (_dl_bindnow) {
_dl_bindnow = NULL;
_dl_unsetenv("LD_BIND_NOW", envp);
}
if (_dl_debug) {
_dl_debug = NULL;
_dl_unsetenv("LD_DEBUG", envp);
}
if (_dl_norandom) {
_dl_norandom = NULL;
_dl_unsetenv("LD_NORANDOM", envp);
}
}
_dl_so_envp = envp;
}
/*
* This is the dynamic loader entrypoint. When entering here, depending
* on architecture type, the stack and registers are set up according
* to the architectures ABI specification. The first thing required
* to do is to dig out all information we need to accomplish our task.
*/
unsigned long
_dl_boot(const char **argv, char **envp, const long loff, long *dl_data)
{
struct elf_object *exe_obj; /* Pointer to executable object */
struct elf_object *dyn_obj; /* Pointer to executable object */
struct r_debug **map_link; /* Where to put pointer for gdb */
struct r_debug *debug_map;
Elf_Dyn *dynp;
elf_object_t *dynobj;
Elf_Phdr *phdp;
char *us = "";
unsigned int i;
int libcnt = 0;
_dl_setup_env(envp);
_dl_progname = argv[0];
if (dl_data[AUX_pagesz] != 0)
_dl_pagesz = dl_data[AUX_pagesz];
else
_dl_pagesz = 4096;
/*
* now that GOT and PLT has been relocated, and we know
* page size, protect it from modification
*/
{
extern char *__got_start;
extern char *__got_end;
#ifndef RTLD_TEXT_PLT
extern char *__plt_start;
extern char *__plt_end;
#endif
_dl_mprotect((void *)ELF_TRUNC((long)&__got_start, _dl_pagesz),
ELF_ROUND((long)&__got_end,_dl_pagesz) -
ELF_TRUNC((long)&__got_start, _dl_pagesz),
GOT_PERMS);
#ifndef RTLD_TEXT_PLT
/* only for DATA_PLT or BSS_PLT */
_dl_mprotect((void *)ELF_TRUNC((long)&__plt_start, _dl_pagesz),
ELF_ROUND((long)&__plt_end,_dl_pagesz) -
ELF_TRUNC((long)&__plt_start, _dl_pagesz),
PROT_READ|PROT_EXEC);
#endif
}
DL_DEB(("rtld loading: '%s'\n", _dl_progname));
exe_obj = NULL;
/*
* Examine the user application and set up object information.
*/
phdp = (Elf_Phdr *)dl_data[AUX_phdr];
for (i = 0; i < dl_data[AUX_phnum]; i++) {
if (phdp->p_type == PT_DYNAMIC) {
exe_obj = _dl_finalize_object(argv[0],
(Elf_Dyn *)phdp->p_vaddr, dl_data, OBJTYPE_EXE,
0, 0);
_dl_add_object(exe_obj);
} else if (phdp->p_type == PT_INTERP) {
us = _dl_strdup((char *)phdp->p_vaddr);
}
phdp++;
}
if (_dl_preload != NULL)
_dl_dopreload(_dl_preload);
/*
* Now, pick up and 'load' all libraries required. Start
* with the first on the list and then do whatever gets
* added along the tour.
*/
dynobj = _dl_objects;
for (dynobj = _dl_objects; dynobj != NULL; dynobj = dynobj->next) {
DL_DEB(("examining: '%s'\n", dynobj->load_name));
libcnt = 0;
for (dynp = dynobj->load_dyn; dynp->d_tag; dynp++) {
if (dynp->d_tag == DT_NEEDED) {
libcnt++;
}
}
if ( libcnt != 0) {
struct listent {
Elf_Dyn *dynp;
elf_object_t *dynobj;
} *liblist;
int *randomlist;
liblist = _dl_malloc(libcnt * sizeof(struct listent));
randomlist = _dl_malloc(libcnt * sizeof(int));
if (liblist == NULL)
_dl_exit(5);
for (dynp = dynobj->load_dyn, i = 0;
dynp->d_tag;
dynp++) {
if (dynp->d_tag == DT_NEEDED) {
liblist[i++].dynp = dynp;
}
}
/* Randomize these */
for (i = 0; i < libcnt; i++)
randomlist[i] = i;
if (!_dl_norandom)
for (i = 1; i < libcnt; i++) {
unsigned int rnd;
int cur;
rnd = _dl_random();
rnd = rnd % (i+1);
cur = randomlist[rnd];
randomlist[rnd] = randomlist[i];
randomlist[i] = cur;
}
for (i = 0; i < libcnt; i++) {
elf_object_t *depobj;
const char *libname;
libname = dynobj->dyn.strtab;
libname +=
liblist[randomlist[i]].dynp->d_un.d_val;
DL_DEB(("needs: '%s'\n", libname));
depobj = _dl_load_shlib(libname, dynobj,
OBJTYPE_LIB, DL_LAZY|RTLD_GLOBAL);
if (depobj == 0) {
_dl_printf(
"%s: can't load library '%s'\n",
_dl_progname, libname);
_dl_exit(4);
}
liblist[randomlist[i]].dynobj = depobj;
}
for (i = 0; i < libcnt; i++) {
_dl_add_object(liblist[i].dynobj);
_dl_link_sub(liblist[i].dynobj, dynobj);
}
_dl_free(liblist);
}
}
/*
* Now add the dynamic loader itself last in the object list
* so we can use the _dl_ code when serving dl.... calls.
*/
dynp = (Elf_Dyn *)((void *)_DYNAMIC);
dyn_obj = _dl_finalize_object(us, dynp, 0, OBJTYPE_LDR,
dl_data[AUX_base], loff);
_dl_add_object(dyn_obj);
dyn_obj->status |= STAT_RELOC_DONE;
if (_dl_traceld == NULL)
_dl_fixup_user_env();
/*
* Everything should be in place now for doing the relocation
* and binding. Call _dl_rtld to do the job. Fingers crossed.
*/
if (_dl_traceld == NULL)
_dl_rtld(_dl_objects);
/*
* The first object is the executable itself,
* it is responsible for running it's own ctors/dtors
* thus do NOT run the ctors for the executable, all of
* the shared libraries which follow.
* Do not run init code if run from ldd.
*/
if ((_dl_traceld == NULL) && (_dl_objects->next != NULL)) {
_dl_objects->status |= STAT_INIT_DONE;
_dl_call_init(_dl_objects);
}
/*
* Schedule a routine to be run at shutdown, by using atexit.
* Cannot call atexit directly from ld.so?
* Do not schedule destructors if run from ldd.
*/
if (_dl_traceld == NULL) {
const Elf_Sym *sym;
Elf_Addr ooff;
sym = NULL;
ooff = _dl_find_symbol("atexit", _dl_objects, &sym,
SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT, 0, dyn_obj);
if (sym == NULL)
_dl_printf("cannot find atexit, destructors will not be run!\n");
else
(*(void (*)(Elf_Addr))(sym->st_value + ooff))
((Elf_Addr)_dl_dtors);
}
/*
* Finally make something to help gdb when poking around in the code.
*/
#ifdef __mips__
map_link = (struct r_debug **)(exe_obj->Dyn.info[DT_MIPS_RLD_MAP -
DT_LOPROC + DT_NUM]);
#else
map_link = NULL;
for (dynp = exe_obj->load_dyn; dynp->d_tag; dynp++) {
if (dynp->d_tag == DT_DEBUG) {
map_link = (struct r_debug **)&dynp->d_un.d_ptr;
break;
}
}
if (dynp->d_tag != DT_DEBUG)
DL_DEB(("failed to mark DTDEBUG\n"));
#endif
if (map_link) {
debug_map = (struct r_debug *)_dl_malloc(sizeof(*debug_map));
debug_map->r_version = 1;
debug_map->r_map = (struct link_map *)_dl_objects;
debug_map->r_brk = (Elf_Addr)_dl_debug_state;
debug_map->r_state = RT_CONSISTENT;
debug_map->r_ldbase = loff;
_dl_debug_map = debug_map;
*map_link = _dl_debug_map;
}
_dl_debug_state();
if (_dl_debug || _dl_traceld) {
_dl_show_objects();
DL_DEB(("dynamic loading done.\n"));
}
if (_dl_traceld)
_dl_exit(0);
DL_DEB(("entry point: 0x%lx\n", dl_data[AUX_entry]));
/*
* Return the entry point.
*/
return(dl_data[AUX_entry]);
}
void
_dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynamicp)
{
struct elf_object dynld; /* Resolver data for the loader */
AuxInfo *auxstack;
long *stack;
Elf_Dyn *dynp;
int n, argc;
char **argv, **envp;
long loff;
/*
* Scan argument and environment vectors. Find dynamic
* data vector put after them.
*/
stack = (long *)sp;
argc = *stack++;
argv = (char **)stack;
envp = &argv[argc + 1];
stack = (long *)envp;
while (*stack++ != NULL)
;
/*
* Zero out dl_data.
*/
for (n = 0; n < AUX_entry; n++)
dl_data[n] = 0;
/*
* Dig out auxiliary data set up by exec call. Move all known
* tags to an indexed local table for easy access.
*/
for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
auxstack++) {
if (auxstack->au_id > AUX_entry)
continue;
dl_data[auxstack->au_id] = auxstack->au_v;
}
loff = dl_data[AUX_base]; /* XXX assumes linked at 0x0 */
/*
* We need to do 'selfreloc' in case the code weren't
* loaded at the address it was linked to.
*
* Scan the DYNAMIC section for the loader.
* Cache the data for easier access.
*/
#if defined(__alpha__)
dynp = (Elf_Dyn *)((long)_DYNAMIC);
#elif defined(__sparc__) || defined(__sparc64__) || defined(__powerpc__)
dynp = dynamicp;
#else
dynp = (Elf_Dyn *)((long)_DYNAMIC + loff);
#endif
while (dynp != NULL && dynp->d_tag != DT_NULL) {
if (dynp->d_tag < DT_NUM)
dynld.Dyn.info[dynp->d_tag] = dynp->d_un.d_val;
else if (dynp->d_tag >= DT_LOPROC &&
dynp->d_tag < DT_LOPROC + DT_PROCNUM)
dynld.Dyn.info[dynp->d_tag - DT_LOPROC + DT_NUM] =
dynp->d_un.d_val;
if (dynp->d_tag == DT_TEXTREL)
dynld.dyn.textrel = 1;
dynp++;
}
/*
* Do the 'bootstrap relocation'. This is really only needed if
* the code was loaded at another location than it was linked to.
* We don't do undefined symbols resolving (to difficult..)
*/
/* "relocate" dyn.X values if they represent addresses */
{
int i, val;
/* must be code, not pic data */
int table[20];
i = 0;
table[i++] = DT_PLTGOT;
table[i++] = DT_HASH;
table[i++] = DT_STRTAB;
table[i++] = DT_SYMTAB;
table[i++] = DT_RELA;
table[i++] = DT_INIT;
table[i++] = DT_FINI;
table[i++] = DT_REL;
table[i++] = DT_JMPREL;
/* other processors insert their extras here */
table[i++] = DT_NULL;
for (i = 0; table[i] != DT_NULL; i++) {
val = table[i];
if (val > DT_HIPROC) /* ??? */
continue;
if (val > DT_LOPROC)
val -= DT_LOPROC + DT_NUM;
if (dynld.Dyn.info[val] != 0)
dynld.Dyn.info[val] += loff;
}
}
{
u_int32_t rs;
Elf_Rel *rp;
int i;
rp = (Elf_Rel *)(dynld.Dyn.info[DT_REL]);
rs = dynld.dyn.relsz;
for (i = 0; i < rs; i += sizeof (Elf_Rel)) {
Elf_Addr *ra;
const Elf_Sym *sp;
sp = dynld.dyn.symtab;
sp += ELF_R_SYM(rp->r_info);
if (ELF_R_SYM(rp->r_info) && sp->st_value == 0) {
#if 0
/* cannot printf in this function */
_dl_wrstderr("Dynamic loader failure: self bootstrapping impossible.\n");
_dl_wrstderr("Undefined symbol: ");
_dl_wrstderr((char *)dynld.dyn.strtab +
sp->st_name);
#endif
_dl_exit(5);
}
ra = (Elf_Addr *)(rp->r_offset + loff);
RELOC_REL(rp, sp, ra, loff);
rp++;
}
}
for (n = 0; n < 2; n++) {
unsigned long rs;
Elf_RelA *rp;
int i;
switch (n) {
case 0:
rp = (Elf_RelA *)(dynld.Dyn.info[DT_JMPREL]);
rs = dynld.dyn.pltrelsz;
break;
case 1:
rp = (Elf_RelA *)(dynld.Dyn.info[DT_RELA]);
rs = dynld.dyn.relasz;
break;
default:
rp = NULL;
rs = 0;
}
for (i = 0; i < rs; i += sizeof (Elf_RelA)) {
Elf_Addr *ra;
const Elf_Sym *sp;
sp = dynld.dyn.symtab;
sp += ELF_R_SYM(rp->r_info);
if (ELF_R_SYM(rp->r_info) && sp->st_value == 0) {
#if 0
_dl_wrstderr("Dynamic loader failure: self bootstrapping impossible.\n");
_dl_wrstderr("Undefined symbol: ");
_dl_wrstderr((char *)dynld.dyn.strtab +
sp->st_name);
#endif
_dl_exit(6);
}
ra = (Elf_Addr *)(rp->r_offset + loff);
RELOC_RELA(rp, sp, ra, loff);
rp++;
}
}
RELOC_GOT(&dynld, loff);
/*
* we have been fully relocated here, so most things no longer
* need the loff adjustment
*/
}
#define DL_SM_SYMBUF_CNT 512
sym_cache _dl_sm_symcache_buffer[DL_SM_SYMBUF_CNT];
void
_dl_rtld(elf_object_t *object)
{
size_t sz;
if (object->next)
_dl_rtld(object->next);
if (object->status & STAT_RELOC_DONE)
return;
sz = 0;
if (object->nchains < DL_SM_SYMBUF_CNT) {
_dl_symcache = _dl_sm_symcache_buffer;
DL_DEB(("using static buffer for %d entries\n",
object->nchains));
_dl_memset(_dl_symcache, 0,
sizeof (sym_cache) * object->nchains);
} else {
sz = ELF_ROUND(sizeof (sym_cache) * object->nchains,
_dl_pagesz);
DL_DEB(("allocating symcache sz %x with mmap\n", sz));
_dl_symcache = (void *)_dl_mmap(0, sz, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANON, -1, 0);
if (_dl_symcache == (void *)MAP_FAILED) {
sz = 0;
_dl_symcache = NULL;
}
}
/*
* Do relocation information first, then GOT.
*/
_dl_md_reloc(object, DT_REL, DT_RELSZ);
_dl_md_reloc(object, DT_RELA, DT_RELASZ);
_dl_md_reloc_got(object, !(_dl_bindnow || object->dyn.bind_now));
if (_dl_symcache != NULL) {
if (sz != 0)
_dl_munmap( _dl_symcache, sz);
_dl_symcache = NULL;
}
object->status |= STAT_RELOC_DONE;
}
void
_dl_call_init(elf_object_t *object)
{
struct dep_node *n;
for (n = object->first_child; n; n = n->next_sibling) {
if (n->data->status & STAT_INIT_DONE)
continue;
_dl_call_init(n->data);
}
if (object->status & STAT_INIT_DONE)
return;
DL_DEB(("doing ctors: [%s]\n", object->load_name));
if (object->dyn.init)
(*object->dyn.init)();
/* What about loops? */
object->status |= STAT_INIT_DONE;
}
static char *
_dl_getenv(const char *var, char **env)
{
const char *ep;
while ((ep = *env++)) {
const char *vp = var;
while (*vp && *vp == *ep) {
vp++;
ep++;
}
if (*vp == '\0' && *ep++ == '=')
return((char *)ep);
}
return(NULL);
}
static void
_dl_unsetenv(const char *var, char **env)
{
char *ep;
while ((ep = *env)) {
const char *vp = var;
while (*vp && *vp == *ep) {
vp++;
ep++;
}
if (*vp == '\0' && *ep++ == '=') {
char **P;
for (P = env;; ++P)
if (!(*P = *(P + 1)))
break;
}
env++;
}
}
/*
* _dl_fixup_user_env()
*
* Set the user environment so that programs can use the environment
* while running constructors. Specifically, MALLOC_OPTIONS= for malloc()
*/
void
_dl_fixup_user_env(void)
{
const Elf_Sym *sym;
Elf_Addr ooff;
struct elf_object dummy_obj;
dummy_obj.dyn.symbolic = 0;
dummy_obj.load_name = "ld.so";
sym = NULL;
ooff = _dl_find_symbol("environ", _dl_objects, &sym,
SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT, 0, &dummy_obj);
if (sym != NULL)
*((char ***)(sym->st_value + ooff)) = _dl_so_envp;
}