2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * Copyright 2009, 2010, 2011 Konstantin Belousov <kib@FreeBSD.ORG>.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 * Dynamic linker for ELF.
33 * John Polstra <jdp@polstra.com>.
37 #error "GCC is needed to compile this file"
40 #include <sys/param.h>
41 #include <sys/mount.h>
44 #include <sys/sysctl.h>
46 #include <sys/utsname.h>
47 #include <sys/ktrace.h>
48 #include <sys/resident.h>
51 #include <machine/tls.h>
66 #include "rtld_printf.h"
68 #define PATH_RTLD "/usr/libexec/ld-elf.so.2"
69 #define LD_ARY_CACHE 16
72 typedef void (*func_ptr_type)();
73 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
76 * Function declarations.
78 static const char *_getenv_ld(const char *id);
79 static void die(void) __dead2;
80 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
82 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *);
83 static void digest_dynamic(Obj_Entry *, int);
84 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
85 static Obj_Entry *dlcheck(void *);
86 static Obj_Entry *dlopen_object(const char *name, Obj_Entry *refobj,
87 int lo_flags, int mode);
88 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
89 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
90 static bool donelist_check(DoneList *, const Obj_Entry *);
91 static void errmsg_restore(char *);
92 static char *errmsg_save(void);
93 static void *fill_search_info(const char *, size_t, void *);
94 static char *find_library(const char *, const Obj_Entry *);
95 static const char *gethints(void);
96 static void init_dag(Obj_Entry *);
97 static void init_rtld(caddr_t, Elf_Auxinfo **);
98 static void initlist_add_neededs(Needed_Entry *, Objlist *);
99 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
100 static bool is_exported(const Elf_Sym *);
101 static void linkmap_add(Obj_Entry *);
102 static void linkmap_delete(Obj_Entry *);
103 static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
104 static void unload_filtees(Obj_Entry *);
105 static int load_needed_objects(Obj_Entry *, int);
106 static int load_preload_objects(void);
107 static Obj_Entry *load_object(const char *, const Obj_Entry *, int);
108 static void map_stacks_exec(RtldLockState *);
109 static Obj_Entry *obj_from_addr(const void *);
110 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
111 static void objlist_call_init(Objlist *, RtldLockState *);
112 static void preinitialize_main_object (void);
113 static void objlist_clear(Objlist *);
114 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
115 static void objlist_init(Objlist *);
116 static void objlist_push_head(Objlist *, Obj_Entry *);
117 static void objlist_push_tail(Objlist *, Obj_Entry *);
118 static void objlist_remove(Objlist *, Obj_Entry *);
119 static void *path_enumerate(const char *, path_enum_proc, void *);
120 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, RtldLockState *);
121 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
122 RtldLockState *lockstate);
123 static int rtld_dirname(const char *, char *);
124 static int rtld_dirname_abs(const char *, char *);
125 static void rtld_exit(void);
126 static char *search_library_path(const char *, const char *);
127 static const void **get_program_var_addr(const char *, RtldLockState *);
128 static void set_program_var(const char *, const void *);
129 static int symlook_default(SymLook *, const Obj_Entry *refobj);
130 static int symlook_global(SymLook *, DoneList *);
131 static void symlook_init_from_req(SymLook *, const SymLook *);
132 static int symlook_list(SymLook *, const Objlist *, DoneList *);
133 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
134 static int symlook_obj1(SymLook *, const Obj_Entry *);
135 static void trace_loaded_objects(Obj_Entry *);
136 static void unlink_object(Obj_Entry *);
137 static void unload_object(Obj_Entry *);
138 static void unref_dag(Obj_Entry *);
139 static void ref_dag(Obj_Entry *);
140 static int origin_subst_one(char **, const char *, const char *,
141 const char *, char *);
142 static char *origin_subst(const char *, const char *);
143 static int rtld_verify_versions(const Objlist *);
144 static int rtld_verify_object_versions(Obj_Entry *);
145 static void object_add_name(Obj_Entry *, const char *);
146 static int object_match_name(const Obj_Entry *, const char *);
147 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
148 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
149 struct dl_phdr_info *phdr_info);
151 void r_debug_state(struct r_debug *, struct link_map *) __noinline;
156 static char *error_message; /* Message for dlerror(), or NULL */
157 struct r_debug r_debug; /* for GDB; */
158 static bool libmap_disable; /* Disable libmap */
159 static bool ld_loadfltr; /* Immediate filters processing */
160 static char *libmap_override; /* Maps to use in addition to libmap.conf */
161 static bool trust; /* False for setuid and setgid programs */
162 static bool dangerous_ld_env; /* True if environment variables have been
163 used to affect the libraries loaded */
164 static const char *ld_bind_now; /* Environment variable for immediate binding */
165 static const char *ld_debug; /* Environment variable for debugging */
166 static const char *ld_library_path; /* Environment variable for search path */
167 static char *ld_preload; /* Environment variable for libraries to
169 static const char *ld_elf_hints_path; /* Environment variable for alternative hints path */
170 static const char *ld_tracing; /* Called from ldd to print libs */
171 static const char *ld_utrace; /* Use utrace() to log events. */
172 static int (*rtld_functrace)( /* Optional function call tracing hook */
173 const char *caller_obj,
174 const char *callee_obj,
175 const char *callee_func,
177 static const Obj_Entry *rtld_functrace_obj; /* Object thereof */
178 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
179 static Obj_Entry **obj_tail; /* Link field of last object in list */
180 static Obj_Entry **preload_tail;
181 static Obj_Entry *obj_main; /* The main program shared object */
182 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
183 static unsigned int obj_count; /* Number of objects in obj_list */
184 static unsigned int obj_loads; /* Number of objects in obj_list */
186 static int ld_resident; /* Non-zero if resident */
187 static const char *ld_ary[LD_ARY_CACHE];
189 static Objlist initlist;
191 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
192 STAILQ_HEAD_INITIALIZER(list_global);
193 static Objlist list_main = /* Objects loaded at program startup */
194 STAILQ_HEAD_INITIALIZER(list_main);
195 static Objlist list_fini = /* Objects needing fini() calls */
196 STAILQ_HEAD_INITIALIZER(list_fini);
198 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
200 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
202 extern Elf_Dyn _DYNAMIC;
203 #pragma weak _DYNAMIC
204 #ifndef RTLD_IS_DYNAMIC
205 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
208 #ifdef ENABLE_OSRELDATE
212 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
213 static int max_stack_flags;
216 * These are the functions the dynamic linker exports to application
217 * programs. They are the only symbols the dynamic linker is willing
218 * to export from itself.
220 static func_ptr_type exports[] = {
221 (func_ptr_type) &_rtld_error,
222 (func_ptr_type) &dlclose,
223 (func_ptr_type) &dlerror,
224 (func_ptr_type) &dlopen,
225 (func_ptr_type) &dlfunc,
226 (func_ptr_type) &dlsym,
227 (func_ptr_type) &dlvsym,
228 (func_ptr_type) &dladdr,
229 (func_ptr_type) &dlinfo,
230 (func_ptr_type) &dl_iterate_phdr,
232 (func_ptr_type) &___tls_get_addr,
234 (func_ptr_type) &__tls_get_addr,
235 (func_ptr_type) &__tls_get_addr_tcb,
236 (func_ptr_type) &_rtld_allocate_tls,
237 (func_ptr_type) &_rtld_free_tls,
238 (func_ptr_type) &_rtld_call_init,
239 (func_ptr_type) &_rtld_thread_init,
240 (func_ptr_type) &_rtld_addr_phdr,
241 (func_ptr_type) &_rtld_get_stack_prot,
246 * Global declarations normally provided by crt1. The dynamic linker is
247 * not built with crt1, so we have to provide them ourselves.
253 * Globals passed as arguments to .init_array and .preinit_array functions
260 * Globals to control TLS allocation.
262 size_t tls_last_offset; /* Static TLS offset of last module */
263 size_t tls_last_size; /* Static TLS size of last module */
264 size_t tls_static_space; /* Static TLS space allocated */
265 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
266 int tls_max_index = 1; /* Largest module index allocated */
269 * Fill in a DoneList with an allocation large enough to hold all of
270 * the currently-loaded objects. Keep this as a macro since it calls
271 * alloca and we want that to occur within the scope of the caller.
273 #define donelist_init(dlp) \
274 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
275 assert((dlp)->objs != NULL), \
276 (dlp)->num_alloc = obj_count, \
279 #define UTRACE_DLOPEN_START 1
280 #define UTRACE_DLOPEN_STOP 2
281 #define UTRACE_DLCLOSE_START 3
282 #define UTRACE_DLCLOSE_STOP 4
283 #define UTRACE_LOAD_OBJECT 5
284 #define UTRACE_UNLOAD_OBJECT 6
285 #define UTRACE_ADD_RUNDEP 7
286 #define UTRACE_PRELOAD_FINISHED 8
287 #define UTRACE_INIT_CALL 9
288 #define UTRACE_FINI_CALL 10
291 char sig[4]; /* 'RTLD' */
294 void *mapbase; /* Used for 'parent' and 'init/fini' */
296 int refcnt; /* Used for 'mode' */
297 char name[MAXPATHLEN];
300 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
301 if (ld_utrace != NULL) \
302 ld_utrace_log(e, h, mb, ms, r, n); \
306 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
307 int refcnt, const char *name)
309 struct utrace_rtld ut;
317 ut.mapbase = mapbase;
318 ut.mapsize = mapsize;
320 bzero(ut.name, sizeof(ut.name));
322 strlcpy(ut.name, name, sizeof(ut.name));
323 utrace(&ut, sizeof(ut));
327 * Main entry point for dynamic linking. The first argument is the
328 * stack pointer. The stack is expected to be laid out as described
329 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
330 * Specifically, the stack pointer points to a word containing
331 * ARGC. Following that in the stack is a null-terminated sequence
332 * of pointers to argument strings. Then comes a null-terminated
333 * sequence of pointers to environment strings. Finally, there is a
334 * sequence of "auxiliary vector" entries.
336 * The second argument points to a place to store the dynamic linker's
337 * exit procedure pointer and the third to a place to store the main
340 * The return value is the main program's entry point.
343 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
345 Elf_Auxinfo *aux_info[AT_COUNT];
353 Objlist_Entry *entry;
356 /* marino: DO NOT MOVE THESE VARIABLES TO _rtld
357 Obj_Entry **preload_tail;
359 from global to here. It will break the DWARF2 unwind scheme.
360 The system compilers were unaffected, but not gcc 4.6
364 * On entry, the dynamic linker itself has not been relocated yet.
365 * Be very careful not to reference any global data until after
366 * init_rtld has returned. It is OK to reference file-scope statics
367 * and string constants, and to call static and global functions.
370 /* Find the auxiliary vector on the stack. */
373 sp += argc + 1; /* Skip over arguments and NULL terminator */
377 * If we aren't already resident we have to dig out some more info.
378 * Note that auxinfo does not exist when we are resident.
380 * I'm not sure about the ld_resident check. It seems to read zero
381 * prior to relocation, which is what we want. When running from a
382 * resident copy everything will be relocated so we are definitely
385 if (ld_resident == 0) {
386 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
388 aux = (Elf_Auxinfo *) sp;
390 /* Digest the auxiliary vector. */
391 for (i = 0; i < AT_COUNT; i++)
393 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
394 if (auxp->a_type < AT_COUNT)
395 aux_info[auxp->a_type] = auxp;
398 /* Initialize and relocate ourselves. */
399 assert(aux_info[AT_BASE] != NULL);
400 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
403 ld_index = 0; /* don't use old env cache in case we are resident */
404 __progname = obj_rtld.path;
405 argv0 = argv[0] != NULL ? argv[0] : "(null)";
410 trust = !issetugid();
412 ld_bind_now = _getenv_ld("LD_BIND_NOW");
414 * If the process is tainted, then we un-set the dangerous environment
415 * variables. The process will be marked as tainted until setuid(2)
416 * is called. If any child process calls setuid(2) we do not want any
417 * future processes to honor the potentially un-safe variables.
420 if ( unsetenv("LD_DEBUG")
421 || unsetenv("LD_PRELOAD")
422 || unsetenv("LD_LIBRARY_PATH")
423 || unsetenv("LD_ELF_HINTS_PATH")
424 || unsetenv("LD_LIBMAP")
425 || unsetenv("LD_LIBMAP_DISABLE")
426 || unsetenv("LD_LOADFLTR")
428 _rtld_error("environment corrupt; aborting");
432 ld_debug = _getenv_ld("LD_DEBUG");
433 libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL;
434 libmap_override = (char *)_getenv_ld("LD_LIBMAP");
435 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
436 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
437 ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH");
438 ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL;
439 dangerous_ld_env = (ld_library_path != NULL)
440 || (ld_preload != NULL)
441 || (ld_elf_hints_path != NULL)
443 || (libmap_override != NULL)
446 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
447 ld_utrace = _getenv_ld("LD_UTRACE");
449 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
450 ld_elf_hints_path = _PATH_ELF_HINTS;
452 if (ld_debug != NULL && *ld_debug != '\0')
454 dbg("%s is initialized, base address = %p", __progname,
455 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
456 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
457 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
459 dbg("initializing thread locks");
463 * If we are resident we can skip work that we have already done.
464 * Note that the stack is reset and there is no Elf_Auxinfo
465 * when running from a resident image, and the static globals setup
466 * between here and resident_skip will have already been setup.
472 * Load the main program, or process its program header if it is
475 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
476 int fd = aux_info[AT_EXECFD]->a_un.a_val;
477 dbg("loading main program");
478 obj_main = map_object(fd, argv0, NULL);
480 if (obj_main == NULL)
482 max_stack_flags = obj->stack_flags;
483 } else { /* Main program already loaded. */
484 const Elf_Phdr *phdr;
488 dbg("processing main program's program header");
489 assert(aux_info[AT_PHDR] != NULL);
490 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
491 assert(aux_info[AT_PHNUM] != NULL);
492 phnum = aux_info[AT_PHNUM]->a_un.a_val;
493 assert(aux_info[AT_PHENT] != NULL);
494 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
495 assert(aux_info[AT_ENTRY] != NULL);
496 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
497 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
501 char buf[MAXPATHLEN];
502 if (aux_info[AT_EXECPATH] != 0) {
505 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
506 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
507 if (kexecpath[0] == '/')
508 obj_main->path = kexecpath;
509 else if (getcwd(buf, sizeof(buf)) == NULL ||
510 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
511 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
512 obj_main->path = xstrdup(argv0);
514 obj_main->path = xstrdup(buf);
516 char resolved[MAXPATHLEN];
517 dbg("No AT_EXECPATH");
518 if (argv0[0] == '/') {
519 if (realpath(argv0, resolved) != NULL)
520 obj_main->path = xstrdup(resolved);
522 obj_main->path = xstrdup(argv0);
524 if (getcwd(buf, sizeof(buf)) != NULL
525 && strlcat(buf, "/", sizeof(buf)) < sizeof(buf)
526 && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf)
527 && access(buf, R_OK) == 0
528 && realpath(buf, resolved) != NULL)
529 obj_main->path = xstrdup(resolved);
531 obj_main->path = xstrdup(argv0);
534 dbg("obj_main path %s", obj_main->path);
535 obj_main->mainprog = true;
537 if (aux_info[AT_STACKPROT] != NULL &&
538 aux_info[AT_STACKPROT]->a_un.a_val != 0)
539 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
542 * Get the actual dynamic linker pathname from the executable if
543 * possible. (It should always be possible.) That ensures that
544 * gdb will find the right dynamic linker even if a non-standard
547 if (obj_main->interp != NULL &&
548 strcmp(obj_main->interp, obj_rtld.path) != 0) {
550 obj_rtld.path = xstrdup(obj_main->interp);
551 __progname = obj_rtld.path;
554 digest_dynamic(obj_main, 0);
556 linkmap_add(obj_main);
557 linkmap_add(&obj_rtld);
559 /* Link the main program into the list of objects. */
560 *obj_tail = obj_main;
561 obj_tail = &obj_main->next;
564 /* Make sure we don't call the main program's init and fini functions. */
565 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
566 obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL;
568 /* Initialize a fake symbol for resolving undefined weak references. */
569 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
570 sym_zero.st_shndx = SHN_UNDEF;
571 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
574 libmap_disable = (bool)lm_init(libmap_override);
576 dbg("loading LD_PRELOAD libraries");
577 if (load_preload_objects() == -1)
579 preload_tail = obj_tail;
581 dbg("loading needed objects");
582 if (load_needed_objects(obj_main, 0) == -1)
585 /* Make a list of all objects loaded at startup. */
586 for (obj = obj_list; obj != NULL; obj = obj->next) {
587 objlist_push_tail(&list_main, obj);
591 dbg("checking for required versions");
592 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
597 if (ld_tracing) { /* We're done */
598 trace_loaded_objects(obj_main);
602 if (ld_resident) /* XXX clean this up! */
605 if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) {
606 dump_relocations(obj_main);
610 /* setup TLS for main thread */
611 dbg("initializing initial thread local storage");
612 STAILQ_FOREACH(entry, &list_main, link) {
614 * Allocate all the initial objects out of the static TLS
615 * block even if they didn't ask for it.
617 allocate_tls_offset(entry->obj);
620 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
623 * Do not try to allocate the TLS here, let libc do it itself.
624 * (crt1 for the program will call _init_tls())
627 if (relocate_objects(obj_main,
628 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, NULL) == -1)
631 dbg("doing copy relocations");
632 if (do_copy_relocations(obj_main) == -1)
637 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
638 if (exec_sys_unregister(-1) < 0) {
639 dbg("exec_sys_unregister failed %d\n", errno);
642 dbg("exec_sys_unregister success\n");
646 if (_getenv_ld("LD_DUMP_REL_POST") != NULL) {
647 dump_relocations(obj_main);
651 dbg("initializing key program variables");
652 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
653 set_program_var("environ", env);
654 set_program_var("__elf_aux_vector", aux);
656 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
657 extern void resident_start(void);
659 if (exec_sys_register(resident_start) < 0) {
660 dbg("exec_sys_register failed %d\n", errno);
663 dbg("exec_sys_register success\n");
667 /* Make a list of init functions to call. */
668 objlist_init(&initlist);
669 initlist_add_objects(obj_list, preload_tail, &initlist);
671 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
673 map_stacks_exec(NULL);
675 dbg("resolving ifuncs");
676 if (resolve_objects_ifunc(obj_main,
677 ld_bind_now != NULL && *ld_bind_now != '\0', NULL) == -1)
681 * Do NOT call the initlist here, give libc a chance to set up
682 * the initial TLS segment. crt1 will then call _rtld_call_init().
685 dbg("transferring control to program entry point = %p", obj_main->entry);
687 /* Return the exit procedure and the program entry point. */
688 *exit_proc = rtld_exit;
690 return (func_ptr_type) obj_main->entry;
694 * Call the initialization list for dynamically loaded libraries.
695 * (called from crt1.c).
698 _rtld_call_init(void)
700 RtldLockState lockstate;
703 preinitialize_main_object();
704 wlock_acquire(rtld_bind_lock, &lockstate);
705 objlist_call_init(&initlist, &lockstate);
706 objlist_clear(&initlist);
707 dbg("loading filtees");
708 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
709 if (ld_loadfltr || obj->z_loadfltr)
710 load_filtees(obj, 0, &lockstate);
712 lock_release(rtld_bind_lock, &lockstate);
716 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
721 ptr = (void *)make_function_pointer(def, obj);
722 target = ((Elf_Addr (*)(void))ptr)();
723 return ((void *)target);
727 _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack)
731 const Obj_Entry *defobj;
734 RtldLockState lockstate;
736 rlock_acquire(rtld_bind_lock, &lockstate);
737 if (sigsetjmp(lockstate.env, 0) != 0)
738 lock_upgrade(rtld_bind_lock, &lockstate);
740 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
742 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
744 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
745 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
749 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
750 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
752 target = (Elf_Addr)(defobj->relocbase + def->st_value);
754 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
755 defobj->strtab + def->st_name, basename(obj->path),
756 (void *)target, basename(defobj->path));
759 * If we have a function call tracing hook, and the
760 * hook would like to keep tracing this one function,
761 * prevent the relocation so we will wind up here
762 * the next time again.
764 * We don't want to functrace calls from the functracer
765 * to avoid recursive loops.
767 if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
768 if (rtld_functrace(obj->path,
770 defobj->strtab + def->st_name,
772 lock_release(rtld_bind_lock, &lockstate);
777 * Write the new contents for the jmpslot. Note that depending on
778 * architecture, the value which we need to return back to the
779 * lazy binding trampoline may or may not be the target
780 * address. The value returned from reloc_jmpslot() is the value
781 * that the trampoline needs.
783 target = reloc_jmpslot(where, target, defobj, obj, rel);
784 lock_release(rtld_bind_lock, &lockstate);
789 * Error reporting function. Use it like printf. If formats the message
790 * into a buffer, and sets things up so that the next call to dlerror()
791 * will return the message.
794 _rtld_error(const char *fmt, ...)
796 static char buf[512];
800 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
806 * Return a dynamically-allocated copy of the current error message, if any.
811 return error_message == NULL ? NULL : xstrdup(error_message);
815 * Restore the current error message from a copy which was previously saved
816 * by errmsg_save(). The copy is freed.
819 errmsg_restore(char *saved_msg)
821 if (saved_msg == NULL)
822 error_message = NULL;
824 _rtld_error("%s", saved_msg);
830 basename(const char *name)
832 const char *p = strrchr(name, '/');
833 return p != NULL ? p + 1 : name;
836 static struct utsname uts;
839 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
849 subst_len = kw_len = 0;
853 if (subst_len == 0) {
854 subst_len = strlen(subst);
858 *res = xmalloc(PATH_MAX);
861 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
862 _rtld_error("Substitution of %s in %s cannot be performed",
864 if (may_free != NULL)
869 memcpy(res1, p, p1 - p);
871 memcpy(res1, subst, subst_len);
876 if (may_free != NULL)
879 *res = xstrdup(real);
883 if (may_free != NULL)
885 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
895 origin_subst(const char *real, const char *origin_path)
897 char *res1, *res2, *res3, *res4;
899 if (uts.sysname[0] == '\0') {
900 if (uname(&uts) != 0) {
901 _rtld_error("utsname failed: %d", errno);
905 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
906 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
907 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
908 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
916 const char *msg = dlerror();
920 rtld_fdputstr(STDERR_FILENO, msg);
925 * Process a shared object's DYNAMIC section, and save the important
926 * information in its Obj_Entry structure.
929 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
930 const Elf_Dyn **dyn_soname)
933 Needed_Entry **needed_tail = &obj->needed;
934 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
935 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
936 int plttype = DT_REL;
941 obj->bind_now = false;
942 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
943 switch (dynp->d_tag) {
946 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
950 obj->relsize = dynp->d_un.d_val;
954 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
958 obj->pltrel = (const Elf_Rel *)
959 (obj->relocbase + dynp->d_un.d_ptr);
963 obj->pltrelsize = dynp->d_un.d_val;
967 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
971 obj->relasize = dynp->d_un.d_val;
975 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
979 plttype = dynp->d_un.d_val;
980 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
984 obj->symtab = (const Elf_Sym *)
985 (obj->relocbase + dynp->d_un.d_ptr);
989 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
993 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
997 obj->strsize = dynp->d_un.d_val;
1001 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1006 obj->verneednum = dynp->d_un.d_val;
1010 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1015 obj->verdefnum = dynp->d_un.d_val;
1019 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1025 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1026 (obj->relocbase + dynp->d_un.d_ptr);
1027 obj->nbuckets = hashtab[0];
1028 obj->nchains = hashtab[1];
1029 obj->buckets = hashtab + 2;
1030 obj->chains = obj->buckets + obj->nbuckets;
1036 Needed_Entry *nep = NEW(Needed_Entry);
1037 nep->name = dynp->d_un.d_val;
1042 needed_tail = &nep->next;
1048 Needed_Entry *nep = NEW(Needed_Entry);
1049 nep->name = dynp->d_un.d_val;
1053 *needed_filtees_tail = nep;
1054 needed_filtees_tail = &nep->next;
1060 Needed_Entry *nep = NEW(Needed_Entry);
1061 nep->name = dynp->d_un.d_val;
1065 *needed_aux_filtees_tail = nep;
1066 needed_aux_filtees_tail = &nep->next;
1071 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1075 obj->textrel = true;
1079 obj->symbolic = true;
1083 case DT_RUNPATH: /* XXX: process separately */
1085 * We have to wait until later to process this, because we
1086 * might not have gotten the address of the string table yet.
1096 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1100 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1103 case DT_PREINIT_ARRAY:
1104 obj->preinit_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1108 obj->init_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1112 obj->fini_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1115 case DT_PREINIT_ARRAYSZ:
1116 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1119 case DT_INIT_ARRAYSZ:
1120 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1123 case DT_FINI_ARRAYSZ:
1124 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1128 /* XXX - not implemented yet */
1130 dbg("Filling in DT_DEBUG entry");
1131 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1135 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1136 obj->z_origin = true;
1137 if (dynp->d_un.d_val & DF_SYMBOLIC)
1138 obj->symbolic = true;
1139 if (dynp->d_un.d_val & DF_TEXTREL)
1140 obj->textrel = true;
1141 if (dynp->d_un.d_val & DF_BIND_NOW)
1142 obj->bind_now = true;
1143 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1148 if (dynp->d_un.d_val & DF_1_NOOPEN)
1149 obj->z_noopen = true;
1150 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1151 obj->z_origin = true;
1152 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1154 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1155 obj->bind_now = true;
1156 if (dynp->d_un.d_val & DF_1_NODELETE)
1157 obj->z_nodelete = true;
1158 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1159 obj->z_loadfltr = true;
1164 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1171 obj->traced = false;
1173 if (plttype == DT_RELA) {
1174 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1176 obj->pltrelasize = obj->pltrelsize;
1177 obj->pltrelsize = 0;
1182 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1183 const Elf_Dyn *dyn_soname)
1186 if (obj->z_origin && obj->origin_path == NULL) {
1187 obj->origin_path = xmalloc(PATH_MAX);
1188 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1192 if (dyn_rpath != NULL) {
1193 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1195 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1198 if (dyn_soname != NULL)
1199 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1203 digest_dynamic(Obj_Entry *obj, int early)
1205 const Elf_Dyn *dyn_rpath;
1206 const Elf_Dyn *dyn_soname;
1208 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname);
1209 digest_dynamic2(obj, dyn_rpath, dyn_soname);
1213 * Process a shared object's program header. This is used only for the
1214 * main program, when the kernel has already loaded the main program
1215 * into memory before calling the dynamic linker. It creates and
1216 * returns an Obj_Entry structure.
1219 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1222 const Elf_Phdr *phlimit = phdr + phnum;
1227 for (ph = phdr; ph < phlimit; ph++) {
1228 if (ph->p_type != PT_PHDR)
1232 obj->phsize = ph->p_memsz;
1233 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1237 obj->stack_flags = PF_X | PF_R | PF_W;
1239 for (ph = phdr; ph < phlimit; ph++) {
1240 switch (ph->p_type) {
1243 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1247 if (nsegs == 0) { /* First load segment */
1248 obj->vaddrbase = trunc_page(ph->p_vaddr);
1249 obj->mapbase = obj->vaddrbase + obj->relocbase;
1250 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1252 } else { /* Last load segment */
1253 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1260 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1265 obj->tlssize = ph->p_memsz;
1266 obj->tlsalign = ph->p_align;
1267 obj->tlsinitsize = ph->p_filesz;
1268 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1272 obj->stack_flags = ph->p_flags;
1276 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1277 obj->relro_size = round_page(ph->p_memsz);
1282 _rtld_error("%s: too few PT_LOAD segments", path);
1291 dlcheck(void *handle)
1295 for (obj = obj_list; obj != NULL; obj = obj->next)
1296 if (obj == (Obj_Entry *) handle)
1299 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1300 _rtld_error("Invalid shared object handle %p", handle);
1307 * If the given object is already in the donelist, return true. Otherwise
1308 * add the object to the list and return false.
1311 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1315 for (i = 0; i < dlp->num_used; i++)
1316 if (dlp->objs[i] == obj)
1319 * Our donelist allocation should always be sufficient. But if
1320 * our threads locking isn't working properly, more shared objects
1321 * could have been loaded since we allocated the list. That should
1322 * never happen, but we'll handle it properly just in case it does.
1324 if (dlp->num_used < dlp->num_alloc)
1325 dlp->objs[dlp->num_used++] = obj;
1330 * Hash function for symbol table lookup. Don't even think about changing
1331 * this. It is specified by the System V ABI.
1334 elf_hash(const char *name)
1336 const unsigned char *p = (const unsigned char *) name;
1337 unsigned long h = 0;
1340 while (*p != '\0') {
1341 h = (h << 4) + *p++;
1342 if ((g = h & 0xf0000000) != 0)
1350 * Find the library with the given name, and return its full pathname.
1351 * The returned string is dynamically allocated. Generates an error
1352 * message and returns NULL if the library cannot be found.
1354 * If the second argument is non-NULL, then it refers to an already-
1355 * loaded shared object, whose library search path will be searched.
1357 * The search order is:
1359 * rpath in the referencing file
1364 find_library(const char *xname, const Obj_Entry *refobj)
1369 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1370 if (xname[0] != '/' && !trust) {
1371 _rtld_error("Absolute pathname required for shared object \"%s\"",
1375 if (refobj != NULL && refobj->z_origin)
1376 return origin_subst(xname, refobj->origin_path);
1378 return xstrdup(xname);
1381 if (libmap_disable || (refobj == NULL) ||
1382 (name = lm_find(refobj->path, xname)) == NULL)
1383 name = (char *)xname;
1385 dbg(" Searching for \"%s\"", name);
1387 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1389 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1390 (pathname = search_library_path(name, gethints())) != NULL ||
1391 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1394 if(refobj != NULL && refobj->path != NULL) {
1395 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1396 name, basename(refobj->path));
1398 _rtld_error("Shared object \"%s\" not found", name);
1404 * Given a symbol number in a referencing object, find the corresponding
1405 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1406 * no definition was found. Returns a pointer to the Obj_Entry of the
1407 * defining object via the reference parameter DEFOBJ_OUT.
1410 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1411 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1412 RtldLockState *lockstate)
1416 const Obj_Entry *defobj;
1422 * If we have already found this symbol, get the information from
1425 if (symnum >= refobj->nchains)
1426 return NULL; /* Bad object */
1427 if (cache != NULL && cache[symnum].sym != NULL) {
1428 *defobj_out = cache[symnum].obj;
1429 return cache[symnum].sym;
1432 ref = refobj->symtab + symnum;
1433 name = refobj->strtab + ref->st_name;
1438 * We don't have to do a full scale lookup if the symbol is local.
1439 * We know it will bind to the instance in this load module; to
1440 * which we already have a pointer (ie ref). By not doing a lookup,
1441 * we not only improve performance, but it also avoids unresolvable
1442 * symbols when local symbols are not in the hash table.
1444 * This might occur for TLS module relocations, which simply use
1447 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1448 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1449 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1452 symlook_init(&req, name);
1454 req.ventry = fetch_ventry(refobj, symnum);
1455 req.lockstate = lockstate;
1456 res = symlook_default(&req, refobj);
1459 defobj = req.defobj_out;
1467 * If we found no definition and the reference is weak, treat the
1468 * symbol as having the value zero.
1470 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1476 *defobj_out = defobj;
1477 /* Record the information in the cache to avoid subsequent lookups. */
1478 if (cache != NULL) {
1479 cache[symnum].sym = def;
1480 cache[symnum].obj = defobj;
1483 if (refobj != &obj_rtld)
1484 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1490 * Return the search path from the ldconfig hints file, reading it if
1491 * necessary. Returns NULL if there are problems with the hints file,
1492 * or if the search path there is empty.
1499 if (hints == NULL) {
1501 struct elfhints_hdr hdr;
1504 /* Keep from trying again in case the hints file is bad. */
1507 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1509 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1510 hdr.magic != ELFHINTS_MAGIC ||
1515 p = xmalloc(hdr.dirlistlen + 1);
1516 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1517 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1525 return hints[0] != '\0' ? hints : NULL;
1529 init_dag(Obj_Entry *root)
1531 const Needed_Entry *needed;
1532 const Objlist_Entry *elm;
1535 if (root->dag_inited)
1537 donelist_init(&donelist);
1539 /* Root object belongs to own DAG. */
1540 objlist_push_tail(&root->dldags, root);
1541 objlist_push_tail(&root->dagmembers, root);
1542 donelist_check(&donelist, root);
1545 * Add dependencies of root object to DAG in breadth order
1546 * by exploiting the fact that each new object get added
1547 * to the tail of the dagmembers list.
1549 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1550 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1551 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1553 objlist_push_tail(&needed->obj->dldags, root);
1554 objlist_push_tail(&root->dagmembers, needed->obj);
1557 root->dag_inited = true;
1561 * Initialize the dynamic linker. The argument is the address at which
1562 * the dynamic linker has been mapped into memory. The primary task of
1563 * this function is to relocate the dynamic linker.
1566 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1568 Obj_Entry objtmp; /* Temporary rtld object */
1569 const Elf_Dyn *dyn_rpath;
1570 const Elf_Dyn *dyn_soname;
1573 * Conjure up an Obj_Entry structure for the dynamic linker.
1575 * The "path" member can't be initialized yet because string constants
1576 * cannot yet be accessed. Below we will set it correctly.
1578 memset(&objtmp, 0, sizeof(objtmp));
1581 objtmp.mapbase = mapbase;
1583 objtmp.relocbase = mapbase;
1585 if (RTLD_IS_DYNAMIC()) {
1586 objtmp.dynamic = rtld_dynamic(&objtmp);
1587 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname);
1588 assert(objtmp.needed == NULL);
1589 assert(!objtmp.textrel);
1592 * Temporarily put the dynamic linker entry into the object list, so
1593 * that symbols can be found.
1596 relocate_objects(&objtmp, true, &objtmp, NULL);
1599 /* Initialize the object list. */
1600 obj_tail = &obj_list;
1602 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1603 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1605 #ifdef ENABLE_OSRELDATE
1606 if (aux_info[AT_OSRELDATE] != NULL)
1607 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1610 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname);
1612 /* Replace the path with a dynamically allocated copy. */
1613 obj_rtld.path = xstrdup(PATH_RTLD);
1615 r_debug.r_brk = r_debug_state;
1616 r_debug.r_state = RT_CONSISTENT;
1620 * Add the init functions from a needed object list (and its recursive
1621 * needed objects) to "list". This is not used directly; it is a helper
1622 * function for initlist_add_objects(). The write lock must be held
1623 * when this function is called.
1626 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1628 /* Recursively process the successor needed objects. */
1629 if (needed->next != NULL)
1630 initlist_add_neededs(needed->next, list);
1632 /* Process the current needed object. */
1633 if (needed->obj != NULL)
1634 initlist_add_objects(needed->obj, &needed->obj->next, list);
1638 * Scan all of the DAGs rooted in the range of objects from "obj" to
1639 * "tail" and add their init functions to "list". This recurses over
1640 * the DAGs and ensure the proper init ordering such that each object's
1641 * needed libraries are initialized before the object itself. At the
1642 * same time, this function adds the objects to the global finalization
1643 * list "list_fini" in the opposite order. The write lock must be
1644 * held when this function is called.
1647 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1649 if (obj->init_scanned || obj->init_done)
1651 obj->init_scanned = true;
1653 /* Recursively process the successor objects. */
1654 if (&obj->next != tail)
1655 initlist_add_objects(obj->next, tail, list);
1657 /* Recursively process the needed objects. */
1658 if (obj->needed != NULL)
1659 initlist_add_neededs(obj->needed, list);
1661 /* Add the object to the init list. */
1662 if (obj->init != (Elf_Addr)NULL || obj->init_array != (Elf_Addr)NULL)
1663 objlist_push_tail(list, obj);
1665 /* Add the object to the global fini list in the reverse order. */
1666 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1667 && !obj->on_fini_list) {
1668 objlist_push_head(&list_fini, obj);
1669 obj->on_fini_list = true;
1674 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1678 is_exported(const Elf_Sym *def)
1681 const func_ptr_type *p;
1683 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1684 for (p = exports; *p != NULL; p++)
1685 if (FPTR_TARGET(*p) == value)
1691 free_needed_filtees(Needed_Entry *n)
1693 Needed_Entry *needed, *needed1;
1695 for (needed = n; needed != NULL; needed = needed->next) {
1696 if (needed->obj != NULL) {
1697 dlclose(needed->obj);
1701 for (needed = n; needed != NULL; needed = needed1) {
1702 needed1 = needed->next;
1708 unload_filtees(Obj_Entry *obj)
1711 free_needed_filtees(obj->needed_filtees);
1712 obj->needed_filtees = NULL;
1713 free_needed_filtees(obj->needed_aux_filtees);
1714 obj->needed_aux_filtees = NULL;
1715 obj->filtees_loaded = false;
1719 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags)
1722 for (; needed != NULL; needed = needed->next) {
1723 needed->obj = dlopen_object(obj->strtab + needed->name, obj,
1724 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
1730 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
1733 lock_restart_for_upgrade(lockstate);
1734 if (!obj->filtees_loaded) {
1735 load_filtee1(obj, obj->needed_filtees, flags);
1736 load_filtee1(obj, obj->needed_aux_filtees, flags);
1737 obj->filtees_loaded = true;
1742 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
1746 for (; needed != NULL; needed = needed->next) {
1747 obj1 = needed->obj = load_object(obj->strtab + needed->name, obj,
1748 flags & ~RTLD_LO_NOLOAD);
1749 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
1751 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1752 dbg("obj %s nodelete", obj1->path);
1755 obj1->ref_nodel = true;
1762 * Given a shared object, traverse its list of needed objects, and load
1763 * each of them. Returns 0 on success. Generates an error message and
1764 * returns -1 on failure.
1767 load_needed_objects(Obj_Entry *first, int flags)
1771 for (obj = first; obj != NULL; obj = obj->next) {
1772 if (process_needed(obj, obj->needed, flags) == -1)
1779 load_preload_objects(void)
1781 char *p = ld_preload;
1782 static const char delim[] = " \t:;";
1787 p += strspn(p, delim);
1788 while (*p != '\0') {
1789 size_t len = strcspn(p, delim);
1797 obj = load_object(p, NULL, 0);
1799 return -1; /* XXX - cleanup */
1802 p += strspn(p, delim);
1804 /* Check for the magic tracing function */
1805 symlook_init(&req, RTLD_FUNCTRACE);
1806 res = symlook_obj(&req, obj);
1808 rtld_functrace = (void *)(req.defobj_out->relocbase +
1809 req.sym_out->st_value);
1810 rtld_functrace_obj = req.defobj_out;
1813 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
1818 * Load a shared object into memory, if it is not already loaded.
1820 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1824 load_object(const char *name, const Obj_Entry *refobj, int flags)
1831 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1832 if (object_match_name(obj, name))
1835 path = find_library(name, refobj);
1840 * If we didn't find a match by pathname, open the file and check
1841 * again by device and inode. This avoids false mismatches caused
1842 * by multiple links or ".." in pathnames.
1844 * To avoid a race, we open the file and use fstat() rather than
1847 if ((fd = open(path, O_RDONLY)) == -1) {
1848 _rtld_error("Cannot open \"%s\"", path);
1852 if (fstat(fd, &sb) == -1) {
1853 _rtld_error("Cannot fstat \"%s\"", path);
1858 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1859 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
1862 object_add_name(obj, name);
1867 if (flags & RTLD_LO_NOLOAD) {
1873 /* First use of this object, so we must map it in */
1874 obj = do_load_object(fd, name, path, &sb, flags);
1883 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
1890 * but first, make sure that environment variables haven't been
1891 * used to circumvent the noexec flag on a filesystem.
1893 if (dangerous_ld_env) {
1894 if (fstatfs(fd, &fs) != 0) {
1895 _rtld_error("Cannot fstatfs \"%s\"", path);
1898 if (fs.f_flags & MNT_NOEXEC) {
1899 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
1903 dbg("loading \"%s\"", path);
1904 obj = map_object(fd, path, sbp);
1908 object_add_name(obj, name);
1910 digest_dynamic(obj, 0);
1911 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
1913 dbg("refusing to load non-loadable \"%s\"", obj->path);
1914 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
1915 munmap(obj->mapbase, obj->mapsize);
1921 obj_tail = &obj->next;
1924 linkmap_add(obj); /* for GDB & dlinfo() */
1925 max_stack_flags |= obj->stack_flags;
1927 dbg(" %p .. %p: %s", obj->mapbase,
1928 obj->mapbase + obj->mapsize - 1, obj->path);
1930 dbg(" WARNING: %s has impure text", obj->path);
1931 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
1938 obj_from_addr(const void *addr)
1942 for (obj = obj_list; obj != NULL; obj = obj->next) {
1943 if (addr < (void *) obj->mapbase)
1945 if (addr < (void *) (obj->mapbase + obj->mapsize))
1952 * Call the finalization functions for each of the objects in "list"
1953 * belonging to the DAG of "root" and referenced once. If NULL "root"
1954 * is specified, every finalization function will be called regardless
1955 * of the reference count and the list elements won't be freed. All of
1956 * the objects are expected to have non-NULL fini functions.
1959 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
1963 Elf_Addr *fini_addr;
1966 assert(root == NULL || root->refcount == 1);
1969 * Preserve the current error message since a fini function might
1970 * call into the dynamic linker and overwrite it.
1972 saved_msg = errmsg_save();
1974 STAILQ_FOREACH(elm, list, link) {
1975 if (root != NULL && (elm->obj->refcount != 1 ||
1976 objlist_find(&root->dagmembers, elm->obj) == NULL))
1979 /* Remove object from fini list to prevent recursive invocation. */
1980 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1982 * XXX: If a dlopen() call references an object while the
1983 * fini function is in progress, we might end up trying to
1984 * unload the referenced object in dlclose() or the object
1985 * won't be unloaded although its fini function has been
1988 lock_release(rtld_bind_lock, lockstate);
1991 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. When this
1992 * happens, DT_FINI_ARRAY is processed first, and it is also processed
1993 * backwards. It is possible to encounter DT_FINI_ARRAY elements with
1994 * values of 0 or 1, but they need to be ignored.
1996 fini_addr = (Elf_Addr *)elm->obj->fini_array;
1997 if (fini_addr != (Elf_Addr)NULL) {
1998 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
1999 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2000 dbg("DSO Array: calling fini function for %s at %p",
2001 elm->obj->path, (void *)fini_addr[index]);
2002 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2003 (void *)fini_addr[index], 0, 0, elm->obj->path);
2004 call_initfini_pointer(elm->obj, fini_addr[index]);
2008 if (elm->obj->fini != (Elf_Addr)NULL) {
2009 dbg("DSO: calling fini function for %s at %p", elm->obj->path,
2010 (void *)elm->obj->fini);
2011 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2012 0, 0, elm->obj->path);
2013 call_initfini_pointer(elm->obj, elm->obj->fini);
2015 wlock_acquire(rtld_bind_lock, lockstate);
2016 /* No need to free anything if process is going down. */
2020 * We must restart the list traversal after every fini call
2021 * because a dlclose() call from the fini function or from
2022 * another thread might have modified the reference counts.
2026 } while (elm != NULL);
2027 errmsg_restore(saved_msg);
2031 * If the main program is defined with a .preinit_array section, call
2032 * each function in order. This must occur before the initialization
2033 * of any shared object or the main program.
2036 preinitialize_main_object (void)
2038 Elf_Addr *init_addr;
2041 init_addr = (Elf_Addr *)obj_main->preinit_array;
2042 if (init_addr == (Elf_Addr)NULL)
2045 for (index = 0; index < obj_main->preinit_array_num; index++)
2046 if (init_addr[index] != 0 && init_addr[index] != 1) {
2047 dbg("Calling preinit array function for %s at %p",
2048 (void *) obj_main->path, (void *)init_addr[index]);
2049 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)init_addr[index],
2050 0, 0, obj_main->path);
2051 call_array_pointer(init_addr[index], glac, glav, environ);
2056 * Call the initialization functions for each of the objects in
2057 * "list". All of the objects are expected to have non-NULL init
2061 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2066 Elf_Addr *init_addr;
2070 * Clean init_scanned flag so that objects can be rechecked and
2071 * possibly initialized earlier if any of vectors called below
2072 * cause the change by using dlopen.
2074 for (obj = obj_list; obj != NULL; obj = obj->next)
2075 obj->init_scanned = false;
2078 * Preserve the current error message since an init function might
2079 * call into the dynamic linker and overwrite it.
2081 saved_msg = errmsg_save();
2082 STAILQ_FOREACH(elm, list, link) {
2083 if (elm->obj->init_done) /* Initialized early. */
2087 * Race: other thread might try to use this object before current
2088 * one completes the initilization. Not much can be done here
2089 * without better locking.
2091 elm->obj->init_done = true;
2092 lock_release(rtld_bind_lock, lockstate);
2095 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. When
2096 * this happens, DT_INIT is processed first. It is possible to
2097 * encounter DT_INIT_ARRAY elements with values of 0 or 1, but they
2098 * need to be ignored.
2100 if (elm->obj->init != (Elf_Addr)NULL) {
2101 dbg("DSO: calling init function for %s at %p", elm->obj->path,
2102 (void *)elm->obj->init);
2103 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2104 0, 0, elm->obj->path);
2105 call_initfini_pointer(elm->obj, elm->obj->init);
2107 init_addr = (Elf_Addr *)elm->obj->init_array;
2108 if (init_addr != (Elf_Addr)NULL) {
2109 for (index = 0; index < elm->obj->init_array_num; index++)
2110 if (init_addr[index] != 0 && init_addr[index] != 1) {
2111 dbg("DSO Array: calling init function for %s at %p",
2112 elm->obj->path, (void *)init_addr[index]);
2113 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2114 (void *)init_addr[index], 0, 0, elm->obj->path);
2115 call_array_pointer(init_addr[index], glac, glav, environ);
2118 wlock_acquire(rtld_bind_lock, lockstate);
2120 errmsg_restore(saved_msg);
2124 objlist_clear(Objlist *list)
2128 while (!STAILQ_EMPTY(list)) {
2129 elm = STAILQ_FIRST(list);
2130 STAILQ_REMOVE_HEAD(list, link);
2135 static Objlist_Entry *
2136 objlist_find(Objlist *list, const Obj_Entry *obj)
2140 STAILQ_FOREACH(elm, list, link)
2141 if (elm->obj == obj)
2147 objlist_init(Objlist *list)
2153 objlist_push_head(Objlist *list, Obj_Entry *obj)
2157 elm = NEW(Objlist_Entry);
2159 STAILQ_INSERT_HEAD(list, elm, link);
2163 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2167 elm = NEW(Objlist_Entry);
2169 STAILQ_INSERT_TAIL(list, elm, link);
2173 objlist_remove(Objlist *list, Obj_Entry *obj)
2177 if ((elm = objlist_find(list, obj)) != NULL) {
2178 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2184 * Relocate newly-loaded shared objects. The argument is a pointer to
2185 * the Obj_Entry for the first such object. All objects from the first
2186 * to the end of the list of objects are relocated. Returns 0 on success,
2190 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2191 RtldLockState *lockstate)
2195 for (obj = first; obj != NULL; obj = obj->next) {
2197 dbg("relocating \"%s\"", obj->path);
2198 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
2199 obj->symtab == NULL || obj->strtab == NULL) {
2200 _rtld_error("%s: Shared object has no run-time symbol table",
2206 /* There are relocations to the write-protected text segment. */
2207 if (mprotect(obj->mapbase, obj->textsize,
2208 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2209 _rtld_error("%s: Cannot write-enable text segment: %s",
2210 obj->path, strerror(errno));
2215 /* Process the non-PLT relocations. */
2216 if (reloc_non_plt(obj, rtldobj, lockstate))
2220 * Reprotect the text segment. Make sure it is included in the
2221 * core dump since we modified it. This unfortunately causes the
2222 * entire text segment to core-out but we don't have much of a
2223 * choice. We could try to only reenable core dumps on pages
2224 * in which relocations occured but that is likely most of the text
2225 * pages anyway, and even that would not work because the rest of
2226 * the text pages would wind up as a read-only OBJT_DEFAULT object
2227 * (created due to our modifications) backed by the original OBJT_VNODE
2228 * object, and the ELF coredump code is currently only able to dump
2229 * vnode records for pure vnode-backed mappings, not vnode backings
2230 * to memory objects.
2233 madvise(obj->mapbase, obj->textsize, MADV_CORE);
2234 if (mprotect(obj->mapbase, obj->textsize,
2235 PROT_READ|PROT_EXEC) == -1) {
2236 _rtld_error("%s: Cannot write-protect text segment: %s",
2237 obj->path, strerror(errno));
2243 /* Set the special PLT or GOT entries. */
2246 /* Process the PLT relocations. */
2247 if (reloc_plt(obj) == -1)
2249 /* Relocate the jump slots if we are doing immediate binding. */
2250 if (obj->bind_now || bind_now)
2251 if (reloc_jmpslots(obj, lockstate) == -1)
2255 * Set up the magic number and version in the Obj_Entry. These
2256 * were checked in the crt1.o from the original ElfKit, so we
2257 * set them for backward compatibility.
2259 obj->magic = RTLD_MAGIC;
2260 obj->version = RTLD_VERSION;
2263 * Set relocated data to read-only status if protection specified
2266 if (obj->relro_size) {
2267 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
2268 _rtld_error("%s: Cannot enforce relro relocation: %s",
2269 obj->path, strerror(errno));
2279 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2280 * referencing STT_GNU_IFUNC symbols is postponed till the other
2281 * relocations are done. The indirect functions specified as
2282 * ifunc are allowed to call other symbols, so we need to have
2283 * objects relocated before asking for resolution from indirects.
2285 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2286 * instead of the usual lazy handling of PLT slots. It is
2287 * consistent with how GNU does it.
2290 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, RtldLockState *lockstate)
2292 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2294 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2295 reloc_gnu_ifunc(obj, lockstate) == -1)
2301 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, RtldLockState *lockstate)
2305 for (obj = first; obj != NULL; obj = obj->next) {
2306 if (resolve_object_ifunc(obj, bind_now, lockstate) == -1)
2313 initlist_objects_ifunc(Objlist *list, bool bind_now, RtldLockState *lockstate)
2317 STAILQ_FOREACH(elm, list, link) {
2318 if (resolve_object_ifunc(elm->obj, bind_now, lockstate) == -1)
2325 * Cleanup procedure. It will be called (by the atexit mechanism) just
2326 * before the process exits.
2331 RtldLockState lockstate;
2333 wlock_acquire(rtld_bind_lock, &lockstate);
2335 objlist_call_fini(&list_fini, NULL, &lockstate);
2336 /* No need to remove the items from the list, since we are exiting. */
2337 if (!libmap_disable)
2339 lock_release(rtld_bind_lock, &lockstate);
2343 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2348 path += strspn(path, ":;");
2349 while (*path != '\0') {
2353 len = strcspn(path, ":;");
2354 res = callback(path, len, arg);
2360 path += strspn(path, ":;");
2366 struct try_library_args {
2374 try_library_path(const char *dir, size_t dirlen, void *param)
2376 struct try_library_args *arg;
2379 if (*dir == '/' || trust) {
2382 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2385 pathname = arg->buffer;
2386 strncpy(pathname, dir, dirlen);
2387 pathname[dirlen] = '/';
2388 strcpy(pathname + dirlen + 1, arg->name);
2390 dbg(" Trying \"%s\"", pathname);
2391 if (access(pathname, F_OK) == 0) { /* We found it */
2392 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2393 strcpy(pathname, arg->buffer);
2401 search_library_path(const char *name, const char *path)
2404 struct try_library_args arg;
2410 arg.namelen = strlen(name);
2411 arg.buffer = xmalloc(PATH_MAX);
2412 arg.buflen = PATH_MAX;
2414 p = path_enumerate(path, try_library_path, &arg);
2422 dlclose(void *handle)
2425 RtldLockState lockstate;
2427 wlock_acquire(rtld_bind_lock, &lockstate);
2428 root = dlcheck(handle);
2430 lock_release(rtld_bind_lock, &lockstate);
2433 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2436 /* Unreference the object and its dependencies. */
2437 root->dl_refcount--;
2439 if (root->refcount == 1) {
2441 * The object will be no longer referenced, so we must unload it.
2442 * First, call the fini functions.
2444 objlist_call_fini(&list_fini, root, &lockstate);
2448 /* Finish cleaning up the newly-unreferenced objects. */
2449 GDB_STATE(RT_DELETE,&root->linkmap);
2450 unload_object(root);
2451 GDB_STATE(RT_CONSISTENT,NULL);
2455 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2456 lock_release(rtld_bind_lock, &lockstate);
2463 char *msg = error_message;
2464 error_message = NULL;
2469 dlopen(const char *name, int mode)
2471 RtldLockState lockstate;
2474 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2475 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2476 if (ld_tracing != NULL) {
2477 rlock_acquire(rtld_bind_lock, &lockstate);
2478 if (sigsetjmp(lockstate.env, 0) != 0)
2479 lock_upgrade(rtld_bind_lock, &lockstate);
2480 environ = (char **)*get_program_var_addr("environ", &lockstate);
2481 lock_release(rtld_bind_lock, &lockstate);
2483 lo_flags = RTLD_LO_DLOPEN;
2484 if (mode & RTLD_NODELETE)
2485 lo_flags |= RTLD_LO_NODELETE;
2486 if (mode & RTLD_NOLOAD)
2487 lo_flags |= RTLD_LO_NOLOAD;
2488 if (ld_tracing != NULL)
2489 lo_flags |= RTLD_LO_TRACE;
2491 return (dlopen_object(name, obj_main, lo_flags,
2492 mode & (RTLD_MODEMASK | RTLD_GLOBAL)));
2496 dlopen_cleanup(Obj_Entry *obj)
2501 if (obj->refcount == 0)
2506 dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode)
2508 Obj_Entry **old_obj_tail;
2511 RtldLockState lockstate;
2514 objlist_init(&initlist);
2516 wlock_acquire(rtld_bind_lock, &lockstate);
2517 GDB_STATE(RT_ADD,NULL);
2519 old_obj_tail = obj_tail;
2525 obj = load_object(name, refobj, lo_flags);
2530 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2531 objlist_push_tail(&list_global, obj);
2532 if (*old_obj_tail != NULL) { /* We loaded something new. */
2533 assert(*old_obj_tail == obj);
2534 result = load_needed_objects(obj, lo_flags & RTLD_LO_DLOPEN);
2538 result = rtld_verify_versions(&obj->dagmembers);
2539 if (result != -1 && ld_tracing)
2541 if (result == -1 || (relocate_objects(obj, (mode & RTLD_MODEMASK)
2542 == RTLD_NOW, &obj_rtld, &lockstate)) == -1) {
2543 dlopen_cleanup(obj);
2546 /* Make list of init functions to call. */
2547 initlist_add_objects(obj, &obj->next, &initlist);
2552 * Bump the reference counts for objects on this DAG. If
2553 * this is the first dlopen() call for the object that was
2554 * already loaded as a dependency, initialize the dag
2560 if ((lo_flags & RTLD_LO_TRACE) != 0)
2563 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
2564 obj->z_nodelete) && !obj->ref_nodel) {
2565 dbg("obj %s nodelete", obj->path);
2567 obj->z_nodelete = obj->ref_nodel = true;
2571 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2573 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2575 map_stacks_exec(&lockstate);
2577 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
2578 &lockstate) == -1) {
2579 objlist_clear(&initlist);
2580 dlopen_cleanup(obj);
2581 lock_release(rtld_bind_lock, &lockstate);
2585 /* Call the init functions. */
2586 objlist_call_init(&initlist, &lockstate);
2587 objlist_clear(&initlist);
2588 lock_release(rtld_bind_lock, &lockstate);
2591 trace_loaded_objects(obj);
2592 lock_release(rtld_bind_lock, &lockstate);
2597 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2601 const Obj_Entry *obj, *defobj;
2604 RtldLockState lockstate;
2609 symlook_init(&req, name);
2611 req.flags = flags | SYMLOOK_IN_PLT;
2612 req.lockstate = &lockstate;
2614 rlock_acquire(rtld_bind_lock, &lockstate);
2615 if (sigsetjmp(lockstate.env, 0) != 0)
2616 lock_upgrade(rtld_bind_lock, &lockstate);
2617 if (handle == NULL || handle == RTLD_NEXT ||
2618 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2620 if ((obj = obj_from_addr(retaddr)) == NULL) {
2621 _rtld_error("Cannot determine caller's shared object");
2622 lock_release(rtld_bind_lock, &lockstate);
2625 if (handle == NULL) { /* Just the caller's shared object. */
2626 res = symlook_obj(&req, obj);
2629 defobj = req.defobj_out;
2631 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2632 handle == RTLD_SELF) { /* ... caller included */
2633 if (handle == RTLD_NEXT)
2635 for (; obj != NULL; obj = obj->next) {
2636 res = symlook_obj(&req, obj);
2639 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
2641 defobj = req.defobj_out;
2642 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2648 * Search the dynamic linker itself, and possibly resolve the
2649 * symbol from there. This is how the application links to
2650 * dynamic linker services such as dlopen.
2652 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2653 res = symlook_obj(&req, &obj_rtld);
2654 if (res == 0 && is_exported(req.sym_out)) {
2656 defobj = req.defobj_out;
2660 assert(handle == RTLD_DEFAULT);
2661 res = symlook_default(&req, obj);
2663 defobj = req.defobj_out;
2668 if ((obj = dlcheck(handle)) == NULL) {
2669 lock_release(rtld_bind_lock, &lockstate);
2673 donelist_init(&donelist);
2674 if (obj->mainprog) {
2675 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
2676 res = symlook_global(&req, &donelist);
2679 defobj = req.defobj_out;
2682 * Search the dynamic linker itself, and possibly resolve the
2683 * symbol from there. This is how the application links to
2684 * dynamic linker services such as dlopen.
2686 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2687 res = symlook_obj(&req, &obj_rtld);
2690 defobj = req.defobj_out;
2695 /* Search the whole DAG rooted at the given object. */
2696 res = symlook_list(&req, &obj->dagmembers, &donelist);
2699 defobj = req.defobj_out;
2705 lock_release(rtld_bind_lock, &lockstate);
2708 * The value required by the caller is derived from the value
2709 * of the symbol. For the ia64 architecture, we need to
2710 * construct a function descriptor which the caller can use to
2711 * call the function with the right 'gp' value. For other
2712 * architectures and for non-functions, the value is simply
2713 * the relocated value of the symbol.
2715 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
2716 return (make_function_pointer(def, defobj));
2717 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
2718 return (rtld_resolve_ifunc(defobj, def));
2720 return (defobj->relocbase + def->st_value);
2723 _rtld_error("Undefined symbol \"%s\"", name);
2724 lock_release(rtld_bind_lock, &lockstate);
2729 dlsym(void *handle, const char *name)
2731 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
2736 dlfunc(void *handle, const char *name)
2743 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
2749 dlvsym(void *handle, const char *name, const char *version)
2753 ventry.name = version;
2755 ventry.hash = elf_hash(version);
2757 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
2762 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
2764 const Obj_Entry *obj;
2765 RtldLockState lockstate;
2767 rlock_acquire(rtld_bind_lock, &lockstate);
2768 obj = obj_from_addr(addr);
2770 _rtld_error("No shared object contains address");
2771 lock_release(rtld_bind_lock, &lockstate);
2774 rtld_fill_dl_phdr_info(obj, phdr_info);
2775 lock_release(rtld_bind_lock, &lockstate);
2780 dladdr(const void *addr, Dl_info *info)
2782 const Obj_Entry *obj;
2785 unsigned long symoffset;
2786 RtldLockState lockstate;
2788 rlock_acquire(rtld_bind_lock, &lockstate);
2789 obj = obj_from_addr(addr);
2791 _rtld_error("No shared object contains address");
2792 lock_release(rtld_bind_lock, &lockstate);
2795 info->dli_fname = obj->path;
2796 info->dli_fbase = obj->mapbase;
2797 info->dli_saddr = NULL;
2798 info->dli_sname = NULL;
2801 * Walk the symbol list looking for the symbol whose address is
2802 * closest to the address sent in.
2804 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
2805 def = obj->symtab + symoffset;
2808 * For skip the symbol if st_shndx is either SHN_UNDEF or
2811 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
2815 * If the symbol is greater than the specified address, or if it
2816 * is further away from addr than the current nearest symbol,
2819 symbol_addr = obj->relocbase + def->st_value;
2820 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
2823 /* Update our idea of the nearest symbol. */
2824 info->dli_sname = obj->strtab + def->st_name;
2825 info->dli_saddr = symbol_addr;
2828 if (info->dli_saddr == addr)
2831 lock_release(rtld_bind_lock, &lockstate);
2836 dlinfo(void *handle, int request, void *p)
2838 const Obj_Entry *obj;
2839 RtldLockState lockstate;
2842 rlock_acquire(rtld_bind_lock, &lockstate);
2844 if (handle == NULL || handle == RTLD_SELF) {
2847 retaddr = __builtin_return_address(0); /* __GNUC__ only */
2848 if ((obj = obj_from_addr(retaddr)) == NULL)
2849 _rtld_error("Cannot determine caller's shared object");
2851 obj = dlcheck(handle);
2854 lock_release(rtld_bind_lock, &lockstate);
2860 case RTLD_DI_LINKMAP:
2861 *((struct link_map const **)p) = &obj->linkmap;
2863 case RTLD_DI_ORIGIN:
2864 error = rtld_dirname(obj->path, p);
2867 case RTLD_DI_SERINFOSIZE:
2868 case RTLD_DI_SERINFO:
2869 error = do_search_info(obj, request, (struct dl_serinfo *)p);
2873 _rtld_error("Invalid request %d passed to dlinfo()", request);
2877 lock_release(rtld_bind_lock, &lockstate);
2883 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
2886 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
2887 phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ?
2888 STAILQ_FIRST(&obj->names)->name : obj->path;
2889 phdr_info->dlpi_phdr = obj->phdr;
2890 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
2891 phdr_info->dlpi_tls_modid = obj->tlsindex;
2892 phdr_info->dlpi_tls_data = obj->tlsinit;
2893 phdr_info->dlpi_adds = obj_loads;
2894 phdr_info->dlpi_subs = obj_loads - obj_count;
2898 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
2900 struct dl_phdr_info phdr_info;
2901 const Obj_Entry *obj;
2902 RtldLockState bind_lockstate, phdr_lockstate;
2905 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
2906 rlock_acquire(rtld_bind_lock, &bind_lockstate);
2910 for (obj = obj_list; obj != NULL; obj = obj->next) {
2911 rtld_fill_dl_phdr_info(obj, &phdr_info);
2912 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
2916 lock_release(rtld_bind_lock, &bind_lockstate);
2917 lock_release(rtld_phdr_lock, &phdr_lockstate);
2922 struct fill_search_info_args {
2925 Dl_serinfo *serinfo;
2926 Dl_serpath *serpath;
2931 fill_search_info(const char *dir, size_t dirlen, void *param)
2933 struct fill_search_info_args *arg;
2937 if (arg->request == RTLD_DI_SERINFOSIZE) {
2938 arg->serinfo->dls_cnt ++;
2939 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1;
2941 struct dl_serpath *s_entry;
2943 s_entry = arg->serpath;
2944 s_entry->dls_name = arg->strspace;
2945 s_entry->dls_flags = arg->flags;
2947 strncpy(arg->strspace, dir, dirlen);
2948 arg->strspace[dirlen] = '\0';
2950 arg->strspace += dirlen + 1;
2958 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2960 struct dl_serinfo _info;
2961 struct fill_search_info_args args;
2963 args.request = RTLD_DI_SERINFOSIZE;
2964 args.serinfo = &_info;
2966 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2969 path_enumerate(ld_library_path, fill_search_info, &args);
2970 path_enumerate(obj->rpath, fill_search_info, &args);
2971 path_enumerate(gethints(), fill_search_info, &args);
2972 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2975 if (request == RTLD_DI_SERINFOSIZE) {
2976 info->dls_size = _info.dls_size;
2977 info->dls_cnt = _info.dls_cnt;
2981 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2982 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2986 args.request = RTLD_DI_SERINFO;
2987 args.serinfo = info;
2988 args.serpath = &info->dls_serpath[0];
2989 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2991 args.flags = LA_SER_LIBPATH;
2992 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2995 args.flags = LA_SER_RUNPATH;
2996 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2999 args.flags = LA_SER_CONFIG;
3000 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
3003 args.flags = LA_SER_DEFAULT;
3004 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3010 rtld_dirname(const char *path, char *bname)
3014 /* Empty or NULL string gets treated as "." */
3015 if (path == NULL || *path == '\0') {
3021 /* Strip trailing slashes */
3022 endp = path + strlen(path) - 1;
3023 while (endp > path && *endp == '/')
3026 /* Find the start of the dir */
3027 while (endp > path && *endp != '/')
3030 /* Either the dir is "/" or there are no slashes */
3032 bname[0] = *endp == '/' ? '/' : '.';
3038 } while (endp > path && *endp == '/');
3041 if (endp - path + 2 > PATH_MAX)
3043 _rtld_error("Filename is too long: %s", path);
3047 strncpy(bname, path, endp - path + 1);
3048 bname[endp - path + 1] = '\0';
3053 rtld_dirname_abs(const char *path, char *base)
3055 char base_rel[PATH_MAX];
3057 if (rtld_dirname(path, base) == -1)
3061 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
3062 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
3063 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
3065 strcpy(base, base_rel);
3070 linkmap_add(Obj_Entry *obj)
3072 struct link_map *l = &obj->linkmap;
3073 struct link_map *prev;
3075 obj->linkmap.l_name = obj->path;
3076 obj->linkmap.l_addr = obj->mapbase;
3077 obj->linkmap.l_ld = obj->dynamic;
3079 /* GDB needs load offset on MIPS to use the symbols */
3080 obj->linkmap.l_offs = obj->relocbase;
3083 if (r_debug.r_map == NULL) {
3089 * Scan to the end of the list, but not past the entry for the
3090 * dynamic linker, which we want to keep at the very end.
3092 for (prev = r_debug.r_map;
3093 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3094 prev = prev->l_next)
3097 /* Link in the new entry. */
3099 l->l_next = prev->l_next;
3100 if (l->l_next != NULL)
3101 l->l_next->l_prev = l;
3106 linkmap_delete(Obj_Entry *obj)
3108 struct link_map *l = &obj->linkmap;
3110 if (l->l_prev == NULL) {
3111 if ((r_debug.r_map = l->l_next) != NULL)
3112 l->l_next->l_prev = NULL;
3116 if ((l->l_prev->l_next = l->l_next) != NULL)
3117 l->l_next->l_prev = l->l_prev;
3121 * Function for the debugger to set a breakpoint on to gain control.
3123 * The two parameters allow the debugger to easily find and determine
3124 * what the runtime loader is doing and to whom it is doing it.
3126 * When the loadhook trap is hit (r_debug_state, set at program
3127 * initialization), the arguments can be found on the stack:
3129 * +8 struct link_map *m
3130 * +4 struct r_debug *rd
3134 r_debug_state(struct r_debug* rd, struct link_map *m)
3137 * The following is a hack to force the compiler to emit calls to
3138 * this function, even when optimizing. If the function is empty,
3139 * the compiler is not obliged to emit any code for calls to it,
3140 * even when marked __noinline. However, gdb depends on those
3143 __asm __volatile("" : : : "memory");
3147 * Get address of the pointer variable in the main program.
3148 * Prefer non-weak symbol over the weak one.
3150 static const void **
3151 get_program_var_addr(const char *name, RtldLockState *lockstate)
3156 symlook_init(&req, name);
3157 req.lockstate = lockstate;
3158 donelist_init(&donelist);
3159 if (symlook_global(&req, &donelist) != 0)
3161 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3162 return ((const void **)make_function_pointer(req.sym_out,
3164 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3165 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3167 return ((const void **)(req.defobj_out->relocbase +
3168 req.sym_out->st_value));
3172 * Set a pointer variable in the main program to the given value. This
3173 * is used to set key variables such as "environ" before any of the
3174 * init functions are called.
3177 set_program_var(const char *name, const void *value)
3181 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3182 dbg("\"%s\": *%p <-- %p", name, addr, value);
3188 * Search the global objects, including dependencies and main object,
3189 * for the given symbol.
3192 symlook_global(SymLook *req, DoneList *donelist)
3195 const Objlist_Entry *elm;
3198 symlook_init_from_req(&req1, req);
3200 /* Search all objects loaded at program start up. */
3201 if (req->defobj_out == NULL ||
3202 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3203 res = symlook_list(&req1, &list_main, donelist);
3204 if (res == 0 && (req->defobj_out == NULL ||
3205 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3206 req->sym_out = req1.sym_out;
3207 req->defobj_out = req1.defobj_out;
3208 assert(req->defobj_out != NULL);
3212 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3213 STAILQ_FOREACH(elm, &list_global, link) {
3214 if (req->defobj_out != NULL &&
3215 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3217 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3218 if (res == 0 && (req->defobj_out == NULL ||
3219 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3220 req->sym_out = req1.sym_out;
3221 req->defobj_out = req1.defobj_out;
3222 assert(req->defobj_out != NULL);
3226 return (req->sym_out != NULL ? 0 : ESRCH);
3230 * This is a special version of getenv which is far more efficient
3231 * at finding LD_ environment vars.
3235 _getenv_ld(const char *id)
3239 int idlen = strlen(id);
3241 if (ld_index == LD_ARY_CACHE)
3243 if (ld_index == 0) {
3244 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
3245 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
3252 for (i = ld_index - 1; i >= 0; --i) {
3253 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
3254 return(ld_ary[i] + idlen + 1);
3260 * Given a symbol name in a referencing object, find the corresponding
3261 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3262 * no definition was found. Returns a pointer to the Obj_Entry of the
3263 * defining object via the reference parameter DEFOBJ_OUT.
3266 symlook_default(SymLook *req, const Obj_Entry *refobj)
3269 const Objlist_Entry *elm;
3273 donelist_init(&donelist);
3274 symlook_init_from_req(&req1, req);
3276 /* Look first in the referencing object if linked symbolically. */
3277 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3278 res = symlook_obj(&req1, refobj);
3280 req->sym_out = req1.sym_out;
3281 req->defobj_out = req1.defobj_out;
3282 assert(req->defobj_out != NULL);
3286 symlook_global(req, &donelist);
3288 /* Search all dlopened DAGs containing the referencing object. */
3289 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3290 if (req->sym_out != NULL &&
3291 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3293 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3294 if (res == 0 && (req->sym_out == NULL ||
3295 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3296 req->sym_out = req1.sym_out;
3297 req->defobj_out = req1.defobj_out;
3298 assert(req->defobj_out != NULL);
3303 * Search the dynamic linker itself, and possibly resolve the
3304 * symbol from there. This is how the application links to
3305 * dynamic linker services such as dlopen. Only the values listed
3306 * in the "exports" array can be resolved from the dynamic linker.
3308 if (req->sym_out == NULL ||
3309 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3310 res = symlook_obj(&req1, &obj_rtld);
3311 if (res == 0 && is_exported(req1.sym_out)) {
3312 req->sym_out = req1.sym_out;
3313 req->defobj_out = req1.defobj_out;
3314 assert(req->defobj_out != NULL);
3318 return (req->sym_out != NULL ? 0 : ESRCH);
3322 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3325 const Obj_Entry *defobj;
3326 const Objlist_Entry *elm;
3332 STAILQ_FOREACH(elm, objlist, link) {
3333 if (donelist_check(dlp, elm->obj))
3335 symlook_init_from_req(&req1, req);
3336 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3337 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3339 defobj = req1.defobj_out;
3340 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3347 req->defobj_out = defobj;
3354 * Search the chain of DAGS cointed to by the given Needed_Entry
3355 * for a symbol of the given name. Each DAG is scanned completely
3356 * before advancing to the next one. Returns a pointer to the symbol,
3357 * or NULL if no definition was found.
3360 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3363 const Needed_Entry *n;
3364 const Obj_Entry *defobj;
3370 symlook_init_from_req(&req1, req);
3371 for (n = needed; n != NULL; n = n->next) {
3372 if (n->obj == NULL ||
3373 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3375 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3377 defobj = req1.defobj_out;
3378 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3384 req->defobj_out = defobj;
3391 * Search the symbol table of a single shared object for a symbol of
3392 * the given name and version, if requested. Returns a pointer to the
3393 * symbol, or NULL if no definition was found. If the object is
3394 * filter, return filtered symbol from filtee.
3396 * The symbol's hash value is passed in for efficiency reasons; that
3397 * eliminates many recomputations of the hash value.
3400 symlook_obj(SymLook *req, const Obj_Entry *obj)
3406 mres = symlook_obj1(req, obj);
3408 if (obj->needed_filtees != NULL) {
3409 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate);
3410 donelist_init(&donelist);
3411 symlook_init_from_req(&req1, req);
3412 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3414 req->sym_out = req1.sym_out;
3415 req->defobj_out = req1.defobj_out;
3419 if (obj->needed_aux_filtees != NULL) {
3420 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate);
3421 donelist_init(&donelist);
3422 symlook_init_from_req(&req1, req);
3423 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3425 req->sym_out = req1.sym_out;
3426 req->defobj_out = req1.defobj_out;
3435 symlook_obj1(SymLook *req, const Obj_Entry *obj)
3437 unsigned long symnum;
3438 const Elf_Sym *vsymp;
3442 if (obj->buckets == NULL)
3447 symnum = obj->buckets[req->hash % obj->nbuckets];
3449 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
3450 const Elf_Sym *symp;
3453 if (symnum >= obj->nchains)
3454 return (ESRCH); /* Bad object */
3456 symp = obj->symtab + symnum;
3457 strp = obj->strtab + symp->st_name;
3459 switch (ELF_ST_TYPE(symp->st_info)) {
3464 if (symp->st_value == 0)
3468 if (symp->st_shndx != SHN_UNDEF)
3470 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3471 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3477 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
3480 if (req->ventry == NULL) {
3481 if (obj->versyms != NULL) {
3482 verndx = VER_NDX(obj->versyms[symnum]);
3483 if (verndx > obj->vernum) {
3484 _rtld_error("%s: symbol %s references wrong version %d",
3485 obj->path, obj->strtab + symnum, verndx);
3489 * If we are not called from dlsym (i.e. this is a normal
3490 * relocation from unversioned binary), accept the symbol
3491 * immediately if it happens to have first version after
3492 * this shared object became versioned. Otherwise, if
3493 * symbol is versioned and not hidden, remember it. If it
3494 * is the only symbol with this name exported by the
3495 * shared object, it will be returned as a match at the
3496 * end of the function. If symbol is global (verndx < 2)
3497 * accept it unconditionally.
3499 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
3500 verndx == VER_NDX_GIVEN) {
3501 req->sym_out = symp;
3502 req->defobj_out = obj;
3505 else if (verndx >= VER_NDX_GIVEN) {
3506 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
3514 req->sym_out = symp;
3515 req->defobj_out = obj;
3518 if (obj->versyms == NULL) {
3519 if (object_match_name(obj, req->ventry->name)) {
3520 _rtld_error("%s: object %s should provide version %s for "
3521 "symbol %s", obj_rtld.path, obj->path,
3522 req->ventry->name, obj->strtab + symnum);
3526 verndx = VER_NDX(obj->versyms[symnum]);
3527 if (verndx > obj->vernum) {
3528 _rtld_error("%s: symbol %s references wrong version %d",
3529 obj->path, obj->strtab + symnum, verndx);
3532 if (obj->vertab[verndx].hash != req->ventry->hash ||
3533 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
3535 * Version does not match. Look if this is a global symbol
3536 * and if it is not hidden. If global symbol (verndx < 2)
3537 * is available, use it. Do not return symbol if we are
3538 * called by dlvsym, because dlvsym looks for a specific
3539 * version and default one is not what dlvsym wants.
3541 if ((req->flags & SYMLOOK_DLSYM) ||
3542 (obj->versyms[symnum] & VER_NDX_HIDDEN) ||
3543 (verndx >= VER_NDX_GIVEN))
3547 req->sym_out = symp;
3548 req->defobj_out = obj;
3553 req->sym_out = vsymp;
3554 req->defobj_out = obj;
3561 trace_loaded_objects(Obj_Entry *obj)
3563 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
3566 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
3569 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
3570 fmt1 = "\t%o => %p (%x)\n";
3572 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
3573 fmt2 = "\t%o (%x)\n";
3575 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");
3577 for (; obj; obj = obj->next) {
3578 Needed_Entry *needed;
3582 if (list_containers && obj->needed != NULL)
3583 rtld_printf("%s:\n", obj->path);
3584 for (needed = obj->needed; needed; needed = needed->next) {
3585 if (needed->obj != NULL) {
3586 if (needed->obj->traced && !list_containers)
3588 needed->obj->traced = true;
3589 path = needed->obj->path;
3593 name = (char *)obj->strtab + needed->name;
3594 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
3596 fmt = is_lib ? fmt1 : fmt2;
3597 while ((c = *fmt++) != '\0') {
3623 rtld_putstr(main_local);
3626 rtld_putstr(obj_main->path);
3635 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
3648 * Unload a dlopened object and its dependencies from memory and from
3649 * our data structures. It is assumed that the DAG rooted in the
3650 * object has already been unreferenced, and that the object has a
3651 * reference count of 0.
3654 unload_object(Obj_Entry *root)
3659 assert(root->refcount == 0);
3662 * Pass over the DAG removing unreferenced objects from
3663 * appropriate lists.
3665 unlink_object(root);
3667 /* Unmap all objects that are no longer referenced. */
3668 linkp = &obj_list->next;
3669 while ((obj = *linkp) != NULL) {
3670 if (obj->refcount == 0) {
3671 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
3673 dbg("unloading \"%s\"", obj->path);
3674 unload_filtees(root);
3675 munmap(obj->mapbase, obj->mapsize);
3676 linkmap_delete(obj);
3687 unlink_object(Obj_Entry *root)
3691 if (root->refcount == 0) {
3692 /* Remove the object from the RTLD_GLOBAL list. */
3693 objlist_remove(&list_global, root);
3695 /* Remove the object from all objects' DAG lists. */
3696 STAILQ_FOREACH(elm, &root->dagmembers, link) {
3697 objlist_remove(&elm->obj->dldags, root);
3698 if (elm->obj != root)
3699 unlink_object(elm->obj);
3705 ref_dag(Obj_Entry *root)
3709 assert(root->dag_inited);
3710 STAILQ_FOREACH(elm, &root->dagmembers, link)
3711 elm->obj->refcount++;
3715 unref_dag(Obj_Entry *root)
3719 assert(root->dag_inited);
3720 STAILQ_FOREACH(elm, &root->dagmembers, link)
3721 elm->obj->refcount--;
3725 * Common code for MD __tls_get_addr().
3728 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
3730 Elf_Addr* dtv = *dtvp;
3731 RtldLockState lockstate;
3733 /* Check dtv generation in case new modules have arrived */
3734 if (dtv[0] != tls_dtv_generation) {
3738 wlock_acquire(rtld_bind_lock, &lockstate);
3739 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3741 if (to_copy > tls_max_index)
3742 to_copy = tls_max_index;
3743 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
3744 newdtv[0] = tls_dtv_generation;
3745 newdtv[1] = tls_max_index;
3747 lock_release(rtld_bind_lock, &lockstate);
3748 dtv = *dtvp = newdtv;
3751 /* Dynamically allocate module TLS if necessary */
3752 if (!dtv[index + 1]) {
3753 /* Signal safe, wlock will block out signals. */
3754 wlock_acquire(rtld_bind_lock, &lockstate);
3755 if (!dtv[index + 1])
3756 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
3757 lock_release(rtld_bind_lock, &lockstate);
3759 return (void*) (dtv[index + 1] + offset);
3762 #if defined(RTLD_STATIC_TLS_VARIANT_II)
3765 * Allocate the static TLS area. Return a pointer to the TCB. The
3766 * static area is based on negative offsets relative to the tcb.
3768 * The TCB contains an errno pointer for the system call layer, but because
3769 * we are the RTLD we really have no idea how the caller was compiled so
3770 * the information has to be passed in. errno can either be:
3772 * type 0 errno is a simple non-TLS global pointer.
3773 * (special case for e.g. libc_rtld)
3774 * type 1 errno accessed by GOT entry (dynamically linked programs)
3775 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
3778 allocate_tls(Obj_Entry *objs)
3783 struct tls_tcb *tcb;
3788 * Allocate the new TCB. static TLS storage is placed just before the
3789 * TCB to support the %gs:OFFSET (negative offset) model.
3791 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
3792 ~RTLD_STATIC_TLS_ALIGN_MASK;
3793 tcb = malloc(data_size + sizeof(*tcb));
3794 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
3796 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
3797 dtv = malloc(dtv_size);
3798 bzero(dtv, dtv_size);
3800 #ifdef RTLD_TCB_HAS_SELF_POINTER
3801 tcb->tcb_self = tcb;
3804 tcb->tcb_pthread = NULL;
3806 dtv[0] = tls_dtv_generation;
3807 dtv[1] = tls_max_index;
3809 for (obj = objs; obj; obj = obj->next) {
3810 if (obj->tlsoffset) {
3811 addr = (Elf_Addr)tcb - obj->tlsoffset;
3812 memset((void *)(addr + obj->tlsinitsize),
3813 0, obj->tlssize - obj->tlsinitsize);
3815 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
3816 dtv[obj->tlsindex + 1] = addr;
3823 free_tls(struct tls_tcb *tcb)
3827 Elf_Addr tls_start, tls_end;
3830 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
3831 ~RTLD_STATIC_TLS_ALIGN_MASK;
3835 tls_end = (Elf_Addr)tcb;
3836 tls_start = (Elf_Addr)tcb - data_size;
3837 for (i = 0; i < dtv_size; i++) {
3838 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
3839 free((void *)dtv[i+2]);
3843 free((void*) tls_start);
3847 #error "Unsupported TLS layout"
3851 * Allocate TLS block for module with given index.
3854 allocate_module_tls(int index)
3859 for (obj = obj_list; obj; obj = obj->next) {
3860 if (obj->tlsindex == index)
3864 _rtld_error("Can't find module with TLS index %d", index);
3868 p = malloc(obj->tlssize);
3870 _rtld_error("Cannot allocate TLS block for index %d", index);
3873 memcpy(p, obj->tlsinit, obj->tlsinitsize);
3874 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
3880 allocate_tls_offset(Obj_Entry *obj)
3887 if (obj->tlssize == 0) {
3888 obj->tls_done = true;
3892 if (obj->tlsindex == 1)
3893 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
3895 off = calculate_tls_offset(tls_last_offset, tls_last_size,
3896 obj->tlssize, obj->tlsalign);
3899 * If we have already fixed the size of the static TLS block, we
3900 * must stay within that size. When allocating the static TLS, we
3901 * leave a small amount of space spare to be used for dynamically
3902 * loading modules which use static TLS.
3904 if (tls_static_space) {
3905 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
3909 tls_last_offset = obj->tlsoffset = off;
3910 tls_last_size = obj->tlssize;
3911 obj->tls_done = true;
3917 free_tls_offset(Obj_Entry *obj)
3919 #ifdef RTLD_STATIC_TLS_VARIANT_II
3921 * If we were the last thing to allocate out of the static TLS
3922 * block, we give our space back to the 'allocator'. This is a
3923 * simplistic workaround to allow libGL.so.1 to be loaded and
3924 * unloaded multiple times. We only handle the Variant II
3925 * mechanism for now - this really needs a proper allocator.
3927 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
3928 == calculate_tls_end(tls_last_offset, tls_last_size)) {
3929 tls_last_offset -= obj->tlssize;
3936 _rtld_allocate_tls(void)
3938 struct tls_tcb *new_tcb;
3939 RtldLockState lockstate;
3941 wlock_acquire(rtld_bind_lock, &lockstate);
3942 new_tcb = allocate_tls(obj_list);
3943 lock_release(rtld_bind_lock, &lockstate);
3948 _rtld_free_tls(struct tls_tcb *tcb)
3950 RtldLockState lockstate;
3952 wlock_acquire(rtld_bind_lock, &lockstate);
3954 lock_release(rtld_bind_lock, &lockstate);
3958 object_add_name(Obj_Entry *obj, const char *name)
3964 entry = malloc(sizeof(Name_Entry) + len);
3966 if (entry != NULL) {
3967 strcpy(entry->name, name);
3968 STAILQ_INSERT_TAIL(&obj->names, entry, link);
3973 object_match_name(const Obj_Entry *obj, const char *name)
3977 STAILQ_FOREACH(entry, &obj->names, link) {
3978 if (strcmp(name, entry->name) == 0)
3985 locate_dependency(const Obj_Entry *obj, const char *name)
3987 const Objlist_Entry *entry;
3988 const Needed_Entry *needed;
3990 STAILQ_FOREACH(entry, &list_main, link) {
3991 if (object_match_name(entry->obj, name))
3995 for (needed = obj->needed; needed != NULL; needed = needed->next) {
3996 if (strcmp(obj->strtab + needed->name, name) == 0 ||
3997 (needed->obj != NULL && object_match_name(needed->obj, name))) {
3999 * If there is DT_NEEDED for the name we are looking for,
4000 * we are all set. Note that object might not be found if
4001 * dependency was not loaded yet, so the function can
4002 * return NULL here. This is expected and handled
4003 * properly by the caller.
4005 return (needed->obj);
4008 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4014 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4015 const Elf_Vernaux *vna)
4017 const Elf_Verdef *vd;
4018 const char *vername;
4020 vername = refobj->strtab + vna->vna_name;
4021 vd = depobj->verdef;
4023 _rtld_error("%s: version %s required by %s not defined",
4024 depobj->path, vername, refobj->path);
4028 if (vd->vd_version != VER_DEF_CURRENT) {
4029 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4030 depobj->path, vd->vd_version);
4033 if (vna->vna_hash == vd->vd_hash) {
4034 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4035 ((char *)vd + vd->vd_aux);
4036 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4039 if (vd->vd_next == 0)
4041 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4043 if (vna->vna_flags & VER_FLG_WEAK)
4045 _rtld_error("%s: version %s required by %s not found",
4046 depobj->path, vername, refobj->path);
4051 rtld_verify_object_versions(Obj_Entry *obj)
4053 const Elf_Verneed *vn;
4054 const Elf_Verdef *vd;
4055 const Elf_Verdaux *vda;
4056 const Elf_Vernaux *vna;
4057 const Obj_Entry *depobj;
4058 int maxvernum, vernum;
4062 * Walk over defined and required version records and figure out
4063 * max index used by any of them. Do very basic sanity checking
4067 while (vn != NULL) {
4068 if (vn->vn_version != VER_NEED_CURRENT) {
4069 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4070 obj->path, vn->vn_version);
4073 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4075 vernum = VER_NEED_IDX(vna->vna_other);
4076 if (vernum > maxvernum)
4078 if (vna->vna_next == 0)
4080 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4082 if (vn->vn_next == 0)
4084 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4088 while (vd != NULL) {
4089 if (vd->vd_version != VER_DEF_CURRENT) {
4090 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4091 obj->path, vd->vd_version);
4094 vernum = VER_DEF_IDX(vd->vd_ndx);
4095 if (vernum > maxvernum)
4097 if (vd->vd_next == 0)
4099 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4106 * Store version information in array indexable by version index.
4107 * Verify that object version requirements are satisfied along the
4110 obj->vernum = maxvernum + 1;
4111 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry));
4114 while (vd != NULL) {
4115 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4116 vernum = VER_DEF_IDX(vd->vd_ndx);
4117 assert(vernum <= maxvernum);
4118 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4119 obj->vertab[vernum].hash = vd->vd_hash;
4120 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4121 obj->vertab[vernum].file = NULL;
4122 obj->vertab[vernum].flags = 0;
4124 if (vd->vd_next == 0)
4126 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4130 while (vn != NULL) {
4131 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4134 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4136 if (check_object_provided_version(obj, depobj, vna))
4138 vernum = VER_NEED_IDX(vna->vna_other);
4139 assert(vernum <= maxvernum);
4140 obj->vertab[vernum].hash = vna->vna_hash;
4141 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4142 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4143 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4144 VER_INFO_HIDDEN : 0;
4145 if (vna->vna_next == 0)
4147 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4149 if (vn->vn_next == 0)
4151 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4157 rtld_verify_versions(const Objlist *objlist)
4159 Objlist_Entry *entry;
4163 STAILQ_FOREACH(entry, objlist, link) {
4165 * Skip dummy objects or objects that have their version requirements
4168 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4170 if (rtld_verify_object_versions(entry->obj) == -1) {
4172 if (ld_tracing == NULL)
4176 if (rc == 0 || ld_tracing != NULL)
4177 rc = rtld_verify_object_versions(&obj_rtld);
4182 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4187 vernum = VER_NDX(obj->versyms[symnum]);
4188 if (vernum >= obj->vernum) {
4189 _rtld_error("%s: symbol %s has wrong verneed value %d",
4190 obj->path, obj->strtab + symnum, vernum);
4191 } else if (obj->vertab[vernum].hash != 0) {
4192 return &obj->vertab[vernum];
4199 _rtld_get_stack_prot(void)
4202 return (stack_prot);
4206 map_stacks_exec(RtldLockState *lockstate)
4210 * Stack protection must be implemented in the kernel before the dynamic
4211 * linker can handle PT_GNU_STACK sections.
4212 * The following is the FreeBSD implementation of map_stacks_exec()
4213 * void (*thr_map_stacks_exec)(void);
4215 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4217 * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4218 * get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4219 * if (thr_map_stacks_exec != NULL) {
4220 * stack_prot |= PROT_EXEC;
4221 * thr_map_stacks_exec();
4227 symlook_init(SymLook *dst, const char *name)
4230 bzero(dst, sizeof(*dst));
4232 dst->hash = elf_hash(name);
4236 symlook_init_from_req(SymLook *dst, const SymLook *src)
4239 dst->name = src->name;
4240 dst->hash = src->hash;
4241 dst->ventry = src->ventry;
4242 dst->flags = src->flags;
4243 dst->defobj_out = NULL;
4244 dst->sym_out = NULL;
4245 dst->lockstate = src->lockstate;
4248 #ifdef ENABLE_OSRELDATE
4250 * Overrides for libc_pic-provided functions.
4254 __getosreldate(void)
4264 oid[1] = KERN_OSRELDATE;
4266 len = sizeof(osrel);
4267 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
4268 if (error == 0 && osrel > 0 && len == sizeof(osrel))
4275 * No unresolved symbols for rtld.
4278 __pthread_cxa_finalize(struct dl_phdr_info *a)