libexec/ld.so/loader.c - master - nerfur/openbsd-src

libexec/ld.so/loader.c
1 155 строк29 KB
deraadt
ugly whitespaces
22 янв 2024, 05:08
22 янв 2024, 05:08210cc31
/*	$OpenBSD: loader.c,v 1.223 2024/01/22 02:08:31 deraadt 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/syscall.h>
#include <sys/exec.h>
#ifdef __i386__
# include <machine/vmparam.h>
#endif
#include <string.h>
#include <link.h>
#include <limits.h>			/* NAME_MAX */
#include <dlfcn.h>
#include <tib.h>

#include "syscall.h"
#include "util.h"
#include "resolve.h"
#include "path.h"
#include "sod.h"

/*
 * Local decls.
 */
unsigned long _dl_boot(const char **, char **, const long, long *) __boot;
void _dl_debug_state(void);
void _dl_setup_env(const char *_argv0, char **_envp) __boot;
void _dl_dtors(void);
void _dl_dopreload(char *_paths) __boot;
void _dl_fixup_user_env(void) __boot;
void _dl_call_preinit(elf_object_t *) __boot;
void _dl_call_init_recurse(elf_object_t *object, int initfirst);
void _dl_clean_boot(void);
static inline void unprotect_if_textrel(elf_object_t *_object);
static inline void reprotect_if_textrel(elf_object_t *_object);
static void _dl_rreloc(elf_object_t *_object);

int _dl_pagesz __relro = 4096;
int _dl_bindnow __relro = 0;
int _dl_debug __relro = 0;
int _dl_trust __relro = 0;
char **_dl_libpath __relro = NULL;
const char **_dl_argv __relro = NULL;
int _dl_argc __relro = 0;
const char *_dl_libcname;

char *_dl_preload __boot_data = NULL;
char *_dl_tracefmt1 __boot_data = NULL;
char *_dl_tracefmt2 __boot_data = NULL;
char *_dl_traceprog __boot_data = NULL;
void *_dl_exec_hint __boot_data = NULL;

char **environ = NULL;
char *__progname = NULL;

int _dl_traceld;
struct r_debug *_dl_debug_map;

static dl_cb_cb _dl_cb_cb;
const struct dl_cb_0 callbacks_0 = {
	.dl_allocate_tib	= &_dl_allocate_tib,
	.dl_free_tib		= &_dl_free_tib,
#if DO_CLEAN_BOOT
	.dl_clean_boot		= &_dl_clean_boot,
#endif
	.dlopen			= &dlopen,
	.dlclose		= &dlclose,
	.dlsym			= &dlsym,
	.dladdr			= &dladdr,
	.dlctl			= &dlctl,
	.dlerror		= &dlerror,
	.dl_iterate_phdr	= &dl_iterate_phdr,
};


/*
 * Run dtors for a single object.
 */
void
_dl_run_dtors(elf_object_t *obj)
{
	if (obj->dyn.fini_array) {
		int num = obj->dyn.fini_arraysz / sizeof(Elf_Addr);
		int i;

		DL_DEB(("doing finiarray obj %p @%p: [%s]\n",
		    obj, obj->dyn.fini_array, obj->load_name));
		for (i = num; i > 0; i--)
			(*obj->dyn.fini_array[i-1])();
	}

	if (obj->dyn.fini) {
		DL_DEB(("doing dtors obj %p @%p: [%s]\n",
		    obj, obj->dyn.fini, obj->load_name));
		(*obj->dyn.fini)();
	}
}

/*
 * Run dtors for all objects that are eligible.
 */
void
_dl_run_all_dtors(void)
{
	elf_object_t *node;
	int fini_complete;
	int skip_initfirst;
	int initfirst_skipped;

	fini_complete = 0;
	skip_initfirst = 1;
	initfirst_skipped = 0;

	while (fini_complete == 0) {
		fini_complete = 1;
		for (node = _dl_objects;
		    node != NULL;
		    node = node->next) {
			if ((node->dyn.fini || node->dyn.fini_array) &&
			    (OBJECT_REF_CNT(node) == 0) &&
			    (node->status & STAT_INIT_DONE) &&
			    ((node->status & STAT_FINI_DONE) == 0)) {
				if (skip_initfirst &&
				    (node->obj_flags & DF_1_INITFIRST))
					initfirst_skipped = 1;
				else
					node->status |= STAT_FINI_READY;
			    }
		}
		for (node = _dl_objects;
		    node != NULL;
		    node = node->next) {
			if ((node->dyn.fini || node->dyn.fini_array) &&
			    (OBJECT_REF_CNT(node) == 0) &&
			    (node->status & STAT_INIT_DONE) &&
			    ((node->status & STAT_FINI_DONE) == 0) &&
			    (!skip_initfirst ||
			    (node->obj_flags & DF_1_INITFIRST) == 0)) {
				struct object_vector vec = node->child_vec;
				int i;

				for (i = 0; i < vec.len; i++)
					vec.vec[i]->status &= ~STAT_FINI_READY;
			}
		}

		for (node = _dl_objects;
		    node != NULL;
		    node = node->next) {
			if (node->status & STAT_FINI_READY) {
				fini_complete = 0;
				node->status |= STAT_FINI_DONE;
				node->status &= ~STAT_FINI_READY;
				_dl_run_dtors(node);
			}
		}

		if (fini_complete && initfirst_skipped)
			fini_complete = initfirst_skipped = skip_initfirst = 0;
	}
}

/*
 * Routine to walk through all of the objects except the first
 * (main executable).
 *
 * Big question, should dlopen()ed objects be unloaded before or after
 * the destructor for the main application runs?
 */
void
_dl_dtors(void)
{
	_dl_thread_kern_stop();

	/* ORDER? */
	_dl_unload_dlopen();

	DL_DEB(("doing dtors\n"));

	_dl_objects->opencount--;
	_dl_notify_unload_shlib(_dl_objects);

	_dl_run_all_dtors();
}

#if DO_CLEAN_BOOT
void
_dl_clean_boot(void)
{
	extern char boot_text_start[], boot_text_end[];
#if 0	/* XXX breaks boehm-gc?!? */
	extern char boot_data_start[], boot_data_end[];
#endif

	_dl_mmap(boot_text_start, boot_text_end - boot_text_start,
	    PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0);
	_dl_mimmutable(boot_text_start, boot_text_end - boot_text_start);
#if 0	/* XXX breaks boehm-gc?!? */
	_dl_mmap(boot_data_start, boot_data_end - boot_data_start,
	    PROT_NONE, MAP_FIXED | MAP_PRIVATE | MAP_ANON, -1, 0);
	_dl_mimmutable(boot_data_start, boot_data_end - boot_data_start);
#endif
}
#endif /* DO_CLEAN_BOOT */

void
_dl_dopreload(char *paths)
{
	char		*cp, *dp;
	elf_object_t	*shlib;
	int		count;

	dp = paths = _dl_strdup(paths);
	if (dp == NULL)
		_dl_oom();

	/* preallocate child_vec for the LD_PRELOAD objects */
	count = 1;
	while (*dp++ != '\0')
		if (*dp == ':')
			count++;
	object_vec_grow(&_dl_objects->child_vec, count);

	dp = paths;
	while ((cp = _dl_strsep(&dp, ":")) != NULL) {
		shlib = _dl_load_shlib(cp, _dl_objects, OBJTYPE_LIB,
		    _dl_objects->obj_flags, 1);
		if (shlib == NULL)
			_dl_die("can't preload library '%s'", cp);
		_dl_add_object(shlib);
		_dl_link_child(shlib, _dl_objects);
	}
	_dl_free(paths);
	return;
}

/*
 * grab interesting environment variables, zap bad env vars if
 * issetugid, and set the exported environ and __progname variables
 */
void
_dl_setup_env(const char *argv0, char **envp)
{
	static char progname_storage[NAME_MAX+1] = "";

	/*
	 * Don't allow someone to change the search paths if he runs
	 * a suid program without credentials high enough.
	 */
	_dl_trust = !_dl_issetugid();
	if (!_dl_trust) {	/* Zap paths if s[ug]id... */
		_dl_unsetenv("LD_DEBUG", envp);
		_dl_unsetenv("LD_LIBRARY_PATH", envp);
		_dl_unsetenv("LD_PRELOAD", envp);
		_dl_unsetenv("LD_BIND_NOW", envp);
	} else {
		/*
		 * Get paths to various things we are going to use.
		 */
		_dl_debug = _dl_getenv("LD_DEBUG", envp) != NULL;
		_dl_libpath = _dl_split_path(_dl_getenv("LD_LIBRARY_PATH",
		    envp));
		_dl_preload = _dl_getenv("LD_PRELOAD", envp);
		_dl_bindnow = _dl_getenv("LD_BIND_NOW", envp) != NULL;
	}

	/* these are usable even in setugid processes */
	_dl_traceld = _dl_getenv("LD_TRACE_LOADED_OBJECTS", envp) != NULL;
	_dl_tracefmt1 = _dl_getenv("LD_TRACE_LOADED_OBJECTS_FMT1", envp);
	_dl_tracefmt2 = _dl_getenv("LD_TRACE_LOADED_OBJECTS_FMT2", envp);
	_dl_traceprog = _dl_getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME", envp);

	environ = envp;

	_dl_trace_setup(envp);

	if (argv0 != NULL) {		/* NULL ptr if argc = 0 */
		const char *p = _dl_strrchr(argv0, '/');

		if (p == NULL)
			p = argv0;
		else
			p++;
		_dl_strlcpy(progname_storage, p, sizeof(progname_storage));
	}
	__progname = progname_storage;
}

int
_dl_load_dep_libs(elf_object_t *object, int flags, int booting)
{
	elf_object_t *dynobj;
	Elf_Dyn *dynp;
	unsigned int loop;
	int libcount;
	int depflags, nodelete = 0;

	dynobj = object;
	while (dynobj) {
		DL_DEB(("examining: '%s'\n", dynobj->load_name));
		libcount = 0;

		/* propagate DF_1_NOW to deplibs (can be set by dynamic tags) */
		depflags = flags | (dynobj->obj_flags & DF_1_NOW);
		if (booting || object->nodelete)
			nodelete = 1;

		for (dynp = dynobj->load_dyn; dynp->d_tag; dynp++) {
			if (dynp->d_tag == DT_NEEDED) {
				libcount++;
			}
		}

		if (libcount != 0) {
			struct listent {
				Elf_Dyn *dynp;
				elf_object_t *depobj;
			} *liblist;
			int *randomlist;

			liblist = _dl_reallocarray(NULL, libcount,
			    sizeof(struct listent));
			randomlist =  _dl_reallocarray(NULL, libcount,
			    sizeof(int));

			if (liblist == NULL || randomlist == NULL)
				_dl_oom();

			for (dynp = dynobj->load_dyn, loop = 0; dynp->d_tag;
			    dynp++)
				if (dynp->d_tag == DT_NEEDED)
					liblist[loop++].dynp = dynp;

			/*
			 * We can't support multiple versions of libc
			 * in a single process.  So remember the first
			 * libc SONAME we encounter as a dependency
			 * and use it in further loads of libc.  In
			 * practice this means we will always use the
			 * libc version that the binary was linked
			 * against.  This isn't entirely correct, but
			 * it will keep most binaries running when
			 * transitioning over a libc major bump.
			 */
			if (_dl_libcname == NULL) {
				for (loop = 0; loop < libcount; loop++) {
					const char *libname;
					libname = dynobj->dyn.strtab;
					libname +=
					    liblist[loop].dynp->d_un.d_val;
					if (_dl_strncmp(libname,
					    "libc.so.", 8) == 0) {
						_dl_libcname = libname;
						break;
					}
				}
			}

			/* Randomize these */
			for (loop = 0; loop < libcount; loop++)
				randomlist[loop] = loop;

			for (loop = 1; loop < libcount; loop++) {
				unsigned int rnd;
				int cur;
				rnd = _dl_arc4random();
				rnd = rnd % (loop+1);
				cur = randomlist[rnd];
				randomlist[rnd] = randomlist[loop];
				randomlist[loop] = cur;
			}

			for (loop = 0; loop < libcount; loop++) {
				elf_object_t *depobj;
				const char *libname;
				libname = dynobj->dyn.strtab;
				libname +=
				    liblist[randomlist[loop]].dynp->d_un.d_val;
				DL_DEB(("loading: %s required by %s\n", libname,
				    dynobj->load_name));
				if (_dl_strncmp(libname, "libc.so.", 8) == 0) {
					if (_dl_libcname)
						libname = _dl_libcname;
				}
				depobj = _dl_load_shlib(libname, dynobj,
				    OBJTYPE_LIB, depflags, nodelete);
				if (depobj == 0) {
					if (booting) {
						_dl_die(
						    "can't load library '%s'",
						    libname);
					}
					DL_DEB(("dlopen: failed to open %s\n",
					    libname));
					_dl_free(liblist);
					_dl_free(randomlist);
					return (1);
				}
				liblist[randomlist[loop]].depobj = depobj;
			}

			object_vec_grow(&dynobj->child_vec, libcount);
			for (loop = 0; loop < libcount; loop++) {
				_dl_add_object(liblist[loop].depobj);
				_dl_link_child(liblist[loop].depobj, dynobj);
			}
			_dl_free(liblist);
			_dl_free(randomlist);
		}
		dynobj = dynobj->next;
	}

	_dl_cache_grpsym_list_setup(object);
	return(0);
}


/* do any RWX -> RX fixups for executable PLTs and apply GNU_RELRO */
static inline void
_dl_self_relro(long loff)
{
	Elf_Ehdr *ehdp;
	Elf_Phdr *phdp;
	int i;

	ehdp = (Elf_Ehdr *)loff;
	phdp = (Elf_Phdr *)(loff + ehdp->e_phoff);
	for (i = 0; i < ehdp->e_phnum; i++, phdp++) {
		switch (phdp->p_type) {
#if defined(__alpha__) || defined(__hppa__) || defined(__powerpc__) || \
    defined(__sparc64__)
		case PT_LOAD:
			if ((phdp->p_flags & (PF_X | PF_W)) != (PF_X | PF_W))
				break;
			_dl_mprotect((void *)(phdp->p_vaddr + loff),
			    phdp->p_memsz, PROT_READ);
			break;
#endif
		case PT_GNU_RELRO:
			_dl_mprotect((void *)(phdp->p_vaddr + loff),
			    phdp->p_memsz, PROT_READ);
			_dl_mimmutable((void *)(phdp->p_vaddr + loff),
			    phdp->p_memsz);
			break;
		}
	}
}


#define PFLAGS(X) ((((X) & PF_R) ? PROT_READ : 0) | \
		   (((X) & PF_W) ? PROT_WRITE : 0) | \
		   (((X) & PF_X) ? PROT_EXEC : 0))

/*
 * To avoid kbind(2) becoming a powerful gadget, it is called inline to a
 * function.  Therefore we cannot create a precise pinsyscall label.  Instead
 * create a duplicate entry to force the kernel's pinsyscall code to skip
 * validation, rather than labelling it illegal.  kbind(2) remains safe
 * because it self-protects by checking its calling address.
 */
#define __STRINGIFY(x)  #x
#define STRINGIFY(x)    __STRINGIFY(x)
#ifdef __arm__
__asm__(".pushsection .openbsd.syscalls,\"\",%progbits;"
    ".p2align 2;"
    ".long 0;"
    ".long " STRINGIFY(SYS_kbind) ";"
    ".popsection");
#else
__asm__(".pushsection .openbsd.syscalls,\"\",@progbits;"
    ".p2align 2;"
    ".long 0;"
    ".long " STRINGIFY(SYS_kbind) ";"
    ".popsection");
#endif

/*
 * 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 dyn_loff, long *dl_data)
{
	struct elf_object *exe_obj;	/* Pointer to executable object */
	struct elf_object *dyn_obj;	/* Pointer to ld.so object */
	struct r_debug **map_link;	/* Where to put pointer for gdb */
	struct r_debug *debug_map;
	struct load_list *next_load, *load_list = NULL;
	Elf_Dyn *dynp;
	Elf_Phdr *phdp;
	Elf_Ehdr *ehdr;
	char *us = NULL;
	unsigned int loop;
	int failed;
	struct dep_node *n;
	Elf_Addr minva, maxva, exe_loff, exec_end, cur_exec_end;
	Elf_Addr relro_addr = 0, relro_size = 0;
	Elf_Phdr *ptls = NULL;
	int align;

	if (dl_data[AUX_pagesz] != 0)
		_dl_pagesz = dl_data[AUX_pagesz];
	_dl_malloc_init();

	_dl_argv = argv;
	while (_dl_argv[_dl_argc] != NULL)
		_dl_argc++;
	_dl_setup_env(argv[0], envp);

	/*
	 * Make read-only the GOT and PLT and variables initialized
	 * during the ld.so setup above.
	 */
	_dl_self_relro(dyn_loff);

	align = _dl_pagesz - 1;

#define ROUND_PG(x) (((x) + align) & ~(align))
#define TRUNC_PG(x) ((x) & ~(align))

	if (_dl_bindnow) {
		/* Lazy binding disabled, so disable kbind */
		_dl_kbind(NULL, 0, 0);
	}

	DL_DEB(("ld.so loading: '%s'\n", __progname));

	/* init this in runtime, not statically */
	TAILQ_INIT(&_dlopened_child_list);

	exe_obj = NULL;
	_dl_loading_object = NULL;

	minva = ELF_NO_ADDR;
	maxva = exe_loff = exec_end = 0;

	/*
	 * Examine the user application and set up object information.
	 */
	phdp = (Elf_Phdr *)dl_data[AUX_phdr];
	for (loop = 0; loop < dl_data[AUX_phnum]; loop++) {
		switch (phdp->p_type) {
		case PT_PHDR:
			exe_loff = (Elf_Addr)dl_data[AUX_phdr] - phdp->p_vaddr;
			us += exe_loff;
			DL_DEB(("exe load offset:  0x%lx\n", exe_loff));
			break;
		case PT_DYNAMIC:
			minva = TRUNC_PG(minva);
			maxva = ROUND_PG(maxva);
			exe_obj = _dl_finalize_object(argv[0] ? argv[0] : "",
			    (Elf_Dyn *)(phdp->p_vaddr + exe_loff),
			    (Elf_Phdr *)dl_data[AUX_phdr],
			    dl_data[AUX_phnum], OBJTYPE_EXE, minva + exe_loff,
			    exe_loff);
			_dl_add_object(exe_obj);
			break;
		case PT_INTERP:
			us += phdp->p_vaddr;
			break;
		case PT_LOAD:
			if (phdp->p_vaddr < minva)
				minva = phdp->p_vaddr;
			if (phdp->p_vaddr > maxva)
				maxva = phdp->p_vaddr + phdp->p_memsz;

			next_load = _dl_calloc(1, sizeof(struct load_list));
			if (next_load == NULL)
				_dl_oom();
			next_load->next = load_list;
			load_list = next_load;
			next_load->start = (char *)TRUNC_PG(phdp->p_vaddr) + exe_loff;
			next_load->size = (phdp->p_vaddr & align) + phdp->p_filesz;
			next_load->prot = PFLAGS(phdp->p_flags);
			cur_exec_end = (Elf_Addr)next_load->start + next_load->size;
			if ((next_load->prot & PROT_EXEC) != 0 &&
			    cur_exec_end > exec_end)
				exec_end = cur_exec_end;
			break;
		case PT_TLS:
			if (phdp->p_filesz > phdp->p_memsz)
				_dl_die("invalid tls data");
			ptls = phdp;
			break;
		case PT_GNU_RELRO:
			relro_addr = phdp->p_vaddr + exe_loff;
			relro_size = phdp->p_memsz;
			break;
		}
		phdp++;
	}
	exe_obj->load_list = load_list;
	exe_obj->obj_flags |= DF_1_GLOBAL;
	exe_obj->nodelete = 1;
	exe_obj->load_size = maxva - minva;
	exe_obj->relro_addr = relro_addr;
	exe_obj->relro_size = relro_size;
	_dl_set_sod(exe_obj->load_name, &exe_obj->sod);

#ifdef __i386__
	if (exec_end > I386_MAX_EXE_ADDR)
		_dl_exec_hint = (void *)ROUND_PG(exec_end-I386_MAX_EXE_ADDR);
	DL_DEB(("_dl_exec_hint:  0x%lx\n", _dl_exec_hint));
#endif

	/* TLS bits in the base executable */
	if (ptls != NULL && ptls->p_memsz)
		_dl_set_tls(exe_obj, ptls, exe_loff, NULL);

	n = _dl_malloc(sizeof *n);
	if (n == NULL)
		_dl_oom();
	n->data = exe_obj;
	TAILQ_INSERT_TAIL(&_dlopened_child_list, n, next_sib);
	exe_obj->opencount++;

	if (_dl_preload != NULL)
		_dl_dopreload(_dl_preload);

	_dl_load_dep_libs(exe_obj, exe_obj->obj_flags, 1);

	/*
	 * Now add the dynamic loader itself last in the object list
	 * so we can use the _dl_ code when serving dl.... calls.
	 * Intentionally left off the exe child_vec.
	 */
	dynp = (Elf_Dyn *)((void *)_DYNAMIC);
	ehdr = (Elf_Ehdr *)dl_data[AUX_base];
	dyn_obj = _dl_finalize_object(us, dynp,
	    (Elf_Phdr *)((char *)dl_data[AUX_base] + ehdr->e_phoff),
	    ehdr->e_phnum, OBJTYPE_LDR, dl_data[AUX_base], dyn_loff);
	_dl_add_object(dyn_obj);

	dyn_obj->refcount++;
	_dl_link_grpsym(dyn_obj);

	dyn_obj->status |= STAT_RELOC_DONE;
	_dl_set_sod(dyn_obj->load_name, &dyn_obj->sod);

	/* calculate the offsets for static TLS allocations */
	_dl_allocate_tls_offsets();

	/*
	 * Make something to help gdb when poking around in the code.
	 * Do this poking at the .dynamic section now, before relocation
	 * renders it read-only
	 */
	map_link = NULL;
#ifdef __mips__
	for (dynp = exe_obj->load_dyn; dynp->d_tag; dynp++) {
		if (dynp->d_tag == DT_MIPS_RLD_MAP_REL) {
			map_link = (struct r_debug **)
			    (dynp->d_un.d_ptr + (Elf_Addr)dynp);
			break;
		} else if (dynp->d_tag == DT_MIPS_RLD_MAP) {
			map_link = (struct r_debug **)
			    (dynp->d_un.d_ptr + exe_loff);
			break;
		}
	}
#endif
	if (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"));
	}
	if (map_link) {
		debug_map = _dl_malloc(sizeof(*debug_map));
		if (debug_map == NULL)
			_dl_oom();
		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 = dyn_loff;
		_dl_debug_map = debug_map;
#ifdef __mips__
		relro_addr = exe_obj->relro_addr;
		if (dynp->d_tag == DT_DEBUG &&
		    ((Elf_Addr)map_link + sizeof(*map_link) <= relro_addr ||
		     (Elf_Addr)map_link >= relro_addr + exe_obj->relro_size)) {
			_dl_mprotect(map_link, sizeof(*map_link),
			    PROT_READ|PROT_WRITE);
			*map_link = _dl_debug_map;
			_dl_mprotect(map_link, sizeof(*map_link),
			    PROT_READ|PROT_EXEC);
		} else
#endif
			*map_link = _dl_debug_map;
	}


	/*
	 * Everything should be in place now for doing the relocation
	 * and binding. Call _dl_rtld to do the job. Fingers crossed.
	 */

	failed = 0;
	if (!_dl_traceld)
		failed = _dl_rtld(_dl_objects);

	if (_dl_debug || _dl_traceld) {
		if (_dl_traceld)
			_dl_pledge("stdio rpath", NULL);
		_dl_show_objects(NULL);
	}

	DL_DEB(("dynamic loading done, %s.\n",
	    (failed == 0) ? "success":"failed"));

	if (failed != 0)
		_dl_die("relocation failed");

	if (_dl_traceld)
		_dl_exit(0);

	_dl_loading_object = NULL;

	/* set up the TIB for the initial thread */
	_dl_allocate_first_tib();

	_dl_fixup_user_env();

	_dl_debug_state();

	/*
	 * Do not run init code if run from ldd.
	 */
	if (_dl_objects->next != NULL) {
		_dl_call_preinit(_dl_objects);
		_dl_call_init(_dl_objects);
	}

	DL_DEB(("entry point: 0x%lx\n", dl_data[AUX_entry]));

	/*
	 * Return the entry point.
	 */
	return(dl_data[AUX_entry]);
}

int
_dl_rtld(elf_object_t *object)
{
	struct load_list *llist;
	int fails = 0;

	if (object->next)
		fails += _dl_rtld(object->next);

	if (object->status & STAT_RELOC_DONE)
		return 0;

	/*
	 * Do relocation information first, then GOT.
	 */
	unprotect_if_textrel(object);
	_dl_rreloc(object);
	fails =_dl_md_reloc(object, DT_REL, DT_RELSZ);
	fails += _dl_md_reloc(object, DT_RELA, DT_RELASZ);
	reprotect_if_textrel(object);

	/*
	 * We do lazy resolution by default, doing eager resolution if
	 *  - the object requests it with -znow, OR
	 *  - LD_BIND_NOW is set and this object isn't being ltraced
	 *
	 * Note that -znow disables ltrace for the object: on at least
	 * amd64 'ld' doesn't generate the trampoline for lazy relocation
	 * when -znow is used.
	 */
	fails += _dl_md_reloc_got(object, !(object->obj_flags & DF_1_NOW) &&
	    !(_dl_bindnow && !object->traced));

	/*
	 * Look for W&X segments and make them read-only.
	 */
	for (llist = object->load_list; llist != NULL; llist = llist->next) {
		if ((llist->prot & PROT_WRITE) && (llist->prot & PROT_EXEC)) {
			_dl_mprotect(llist->start, llist->size,
			    llist->prot & ~PROT_WRITE);
		}
	}

	/*
	 * TEXTREL binaries are loaded without immutable on un-writeable sections.
	 * After text relocations are finished, these regions can become
	 * immutable.  OPENBSD_MUTABLE section always overlaps writeable LOADs,
	 * so don't be afraid.
	 */
	if (object->dyn.textrel) {
		for (llist = object->load_list; llist != NULL; llist = llist->next)
			if ((llist->prot & PROT_WRITE) == 0)
				_dl_mimmutable(llist->start, llist->size);
	}

	if (fails == 0)
		object->status |= STAT_RELOC_DONE;

	return (fails);
}

void
_dl_call_preinit(elf_object_t *object)
{
	if (object->dyn.preinit_array) {
		int num = object->dyn.preinit_arraysz / sizeof(Elf_Addr);
		int i;

		DL_DEB(("doing preinitarray obj %p @%p: [%s]\n",
		    object, object->dyn.preinit_array, object->load_name));
		for (i = 0; i < num; i++)
			(*object->dyn.preinit_array[i])(_dl_argc, _dl_argv,
			    environ, &_dl_cb_cb);
	}
}

void
_dl_call_init(elf_object_t *object)
{
	_dl_call_init_recurse(object, 1);
	_dl_call_init_recurse(object, 0);
}

static void
_dl_relro(elf_object_t *object)
{
	/*
	 * Handle GNU_RELRO
	 */
	if (object->relro_addr != 0 && object->relro_size != 0) {
		Elf_Addr addr = object->relro_addr;

		DL_DEB(("protect RELRO [0x%lx,0x%lx) in %s\n",
		    addr, addr + object->relro_size, object->load_name));
		_dl_mprotect((void *)addr, object->relro_size, PROT_READ);

		/* if library will never be unloaded, RELRO can be immutable */
		if (object->nodelete)
			_dl_mimmutable((void *)addr, object->relro_size);
	}
}

void
_dl_call_init_recurse(elf_object_t *object, int initfirst)
{
	struct object_vector vec;
	int visited_flag = initfirst ? STAT_VISIT_INITFIRST : STAT_VISIT_INIT;
	int i;

	object->status |= visited_flag;

	for (vec = object->child_vec, i = 0; i < vec.len; i++) {
		if (vec.vec[i]->status & visited_flag)
			continue;
		_dl_call_init_recurse(vec.vec[i], initfirst);
	}

	if (object->status & STAT_INIT_DONE)
		return;

	if (initfirst && (object->obj_flags & DF_1_INITFIRST) == 0)
		return;

	if (!initfirst) {
		_dl_relro(object);
		_dl_apply_immutable(object);
	}

	if (object->dyn.init) {
		DL_DEB(("doing ctors obj %p @%p: [%s]\n",
		    object, object->dyn.init, object->load_name));
		(*object->dyn.init)();
	}

	if (object->dyn.init_array) {
		int num = object->dyn.init_arraysz / sizeof(Elf_Addr);
		int i;

		DL_DEB(("doing initarray obj %p @%p: [%s]\n",
		    object, object->dyn.init_array, object->load_name));
		for (i = 0; i < num; i++)
			(*object->dyn.init_array[i])(_dl_argc, _dl_argv,
			    environ, &_dl_cb_cb);
	}

	if (initfirst) {
		_dl_relro(object);
		_dl_apply_immutable(object);
	}

	object->status |= STAT_INIT_DONE;
}

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);
}

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;
		} else
			env++;
	}
}

static inline void
fixup_sym(struct elf_object *dummy_obj, const char *name, void *addr)
{
	struct sym_res sr;

	sr = _dl_find_symbol(name, SYM_SEARCH_ALL|SYM_NOWARNNOTFOUND|SYM_PLT,
	    NULL, dummy_obj);
	if (sr.sym != NULL) {
		void *p = (void *)(sr.sym->st_value + sr.obj->obj_base);
		if (p != addr) {
			DL_DEB(("setting %s %p@%s[%p] from %p\n", name,
			    p, sr.obj->load_name, (void *)sr.obj, addr));
			*(void **)p = *(void **)addr;
		}
	}
}

/*
 * _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)
{
	struct elf_object dummy_obj;

	dummy_obj.dyn.symbolic = 0;
	dummy_obj.load_name = "ld.so";
	fixup_sym(&dummy_obj, "environ", &environ);
	fixup_sym(&dummy_obj, "__progname", &__progname);
}

const void *
_dl_cb_cb(int version)
{
	DL_DEB(("version %d callbacks requested\n", version));
	if (version == 0)
		return &callbacks_0;
	return NULL;
}

static inline void
unprotect_if_textrel(elf_object_t *object)
{
	struct load_list *ll;

	if (__predict_false(object->dyn.textrel == 1)) {
		for (ll = object->load_list; ll != NULL; ll = ll->next) {
			if ((ll->prot & PROT_WRITE) == 0)
				_dl_mprotect(ll->start, ll->size,
				    PROT_READ | PROT_WRITE);
		}
	}
}

static inline void
reprotect_if_textrel(elf_object_t *object)
{
	struct load_list *ll;

	if (__predict_false(object->dyn.textrel == 1)) {
		for (ll = object->load_list; ll != NULL; ll = ll->next) {
			if ((ll->prot & PROT_WRITE) == 0)
				_dl_mprotect(ll->start, ll->size, ll->prot);
		}
	}
}

static void
_dl_rreloc(elf_object_t *object)
{
	const Elf_Relr	*reloc, *rend;
	Elf_Addr	loff = object->obj_base;

	reloc = object->dyn.relr;
	rend  = (const Elf_Relr *)((char *)reloc + object->dyn.relrsz);

	while (reloc < rend) {
		Elf_Addr *where;

		where = (Elf_Addr *)(*reloc + loff);
		*where++ += loff;

		for (reloc++; reloc < rend && (*reloc & 1); reloc++) {
			Elf_Addr bits = *reloc >> 1;

			Elf_Addr *here = where;
			while (bits != 0) {
				if (bits & 1) {
					*here += loff;
				}
				bits >>= 1;
				here++;
			}
			where += (8 * sizeof *reloc) - 1;
		}
	}
}

void
_dl_push_range(struct range_vector *v, vaddr_t s, vaddr_t e)
{
	int i = v->count;

	if (i == nitems(v->slice)) {
		_dl_die("too many ranges");
	}
	/* Skips the empty ranges (s == e). */
	if (s < e) {
		v->slice[i].start = s;
		v->slice[i].end = e;
		v->count++;
	} else if (s > e) {
		_dl_die("invalid range");
	}
}

void
_dl_push_range_size(struct range_vector *v, vaddr_t s, vsize_t size)
{
	_dl_push_range(v, s, s + size);
}

/*
 * Finds the truly immutable ranges by taking mutable ones out.  Implements
 * interval difference of imut and mut. Interval splitting necessitates
 * intermediate storage and complex double buffering.
 */
void
_dl_apply_immutable(elf_object_t *object)
{
	struct range_vector acc[2];  /* flips out to avoid copying */
	struct addr_range *m, *im;
	int i, j, imut, in, out;

	if (object->obj_type != OBJTYPE_LIB)
		return;

	for (imut = 0; imut < object->imut.count; imut++) {
		im = &object->imut.slice[imut];
		out = 0;
		acc[out].count = 0;
		_dl_push_range(&acc[out], im->start, im->end);

		for (i = 0; i < object->mut.count; i++) {
			m = &object->mut.slice[i];
			in = out;
			out = 1 - in;
			acc[out].count = 0;
			for (j = 0; j < acc[in].count; j++) {
				const vaddr_t ms = m->start, me = m->end;
				const vaddr_t is = acc[in].slice[j].start,
				    ie = acc[in].slice[j].end;
				if (ie <= ms || me <= is) {
					/* is .. ie .. ms .. me -> is .. ie */
					/* ms .. me .. is .. ie -> is .. ie */
					_dl_push_range(&acc[out], is, ie);
				} else if (ms <= is && ie <= me) {
					/* PROVIDED: ms < ie && is < me */
					/* ms .. is .. ie .. me -> [] */
					;
				} else if (ie <= me) {
					/* is .. ms .. ie .. me -> is .. ms */
					_dl_push_range(&acc[out], is, ms);
				} else if (is < ms) {
					/* is .. ms .. me .. ie -> is .. ms */
					_dl_push_range(&acc[out], is, ms);
					_dl_push_range(&acc[out], me, ie);
				} else {
					/* ms .. is .. me .. ie -> me .. ie */
					_dl_push_range(&acc[out], me, ie);
				}
			}
		}

		/* and now, install immutability for objects */
		for (i = 0; i < acc[out].count; i++) {
			const struct addr_range *ar = &acc[out].slice[i];
			_dl_mimmutable((void *)ar->start, ar->end - ar->start);
		}

	}
}