2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 * Dynamic linker for ELF.
32 * John Polstra <jdp@polstra.com>.
36 #error "GCC is needed to compile this file"
39 #include <sys/param.h>
40 #include <sys/mount.h>
44 #include <sys/utsname.h>
45 #include <sys/ktrace.h>
63 #define PATH_RTLD "/libexec/ld-elf.so.1"
65 #define PATH_RTLD "/libexec/ld-elf32.so.1"
69 typedef void (*func_ptr_type)();
70 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
73 * This structure provides a reentrant way to keep a list of objects and
74 * check which ones have already been processed in some way.
76 typedef struct Struct_DoneList {
77 const Obj_Entry **objs; /* Array of object pointers */
78 unsigned int num_alloc; /* Allocated size of the array */
79 unsigned int num_used; /* Number of array slots used */
83 * Function declarations.
85 static const char *basename(const char *);
86 static void die(void) __dead2;
87 static void digest_dynamic(Obj_Entry *, int);
88 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
89 static Obj_Entry *dlcheck(void *);
90 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *);
91 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
92 static bool donelist_check(DoneList *, const Obj_Entry *);
93 static void errmsg_restore(char *);
94 static char *errmsg_save(void);
95 static void *fill_search_info(const char *, size_t, void *);
96 static char *find_library(const char *, const Obj_Entry *);
97 static const char *gethints(void);
98 static void init_dag(Obj_Entry *);
99 static void init_dag1(Obj_Entry *, Obj_Entry *, DoneList *);
100 static void init_rtld(caddr_t);
101 static void initlist_add_neededs(Needed_Entry *, Objlist *);
102 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
103 static bool is_exported(const Elf_Sym *);
104 static void linkmap_add(Obj_Entry *);
105 static void linkmap_delete(Obj_Entry *);
106 static int load_needed_objects(Obj_Entry *);
107 static int load_preload_objects(void);
108 static Obj_Entry *load_object(const char *, const Obj_Entry *, int);
109 static Obj_Entry *obj_from_addr(const void *);
110 static void objlist_call_fini(Objlist *, bool, int *);
111 static void objlist_call_init(Objlist *, int *);
112 static void objlist_clear(Objlist *);
113 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
114 static void objlist_init(Objlist *);
115 static void objlist_push_head(Objlist *, Obj_Entry *);
116 static void objlist_push_tail(Objlist *, Obj_Entry *);
117 static void objlist_remove(Objlist *, Obj_Entry *);
118 static void *path_enumerate(const char *, path_enum_proc, void *);
119 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *);
120 static int rtld_dirname(const char *, char *);
121 static int rtld_dirname_abs(const char *, char *);
122 static void rtld_exit(void);
123 static char *search_library_path(const char *, const char *);
124 static const void **get_program_var_addr(const char *);
125 static void set_program_var(const char *, const void *);
126 static const Elf_Sym *symlook_default(const char *, unsigned long,
127 const Obj_Entry *, const Obj_Entry **, const Ver_Entry *, int);
128 static const Elf_Sym *symlook_list(const char *, unsigned long, const Objlist *,
129 const Obj_Entry **, const Ver_Entry *, int, DoneList *);
130 static const Elf_Sym *symlook_needed(const char *, unsigned long,
131 const Needed_Entry *, const Obj_Entry **, const Ver_Entry *,
133 static void trace_loaded_objects(Obj_Entry *);
134 static void unlink_object(Obj_Entry *);
135 static void unload_object(Obj_Entry *);
136 static void unref_dag(Obj_Entry *);
137 static void ref_dag(Obj_Entry *);
138 static int origin_subst_one(char **, const char *, const char *,
139 const char *, char *);
140 static char *origin_subst(const char *, const char *);
141 static int rtld_verify_versions(const Objlist *);
142 static int rtld_verify_object_versions(Obj_Entry *);
143 static void object_add_name(Obj_Entry *, const char *);
144 static int object_match_name(const Obj_Entry *, const char *);
145 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
147 void r_debug_state(struct r_debug *, struct link_map *);
152 static char *error_message; /* Message for dlerror(), or NULL */
153 struct r_debug r_debug; /* for GDB; */
154 static bool libmap_disable; /* Disable libmap */
155 static char *libmap_override; /* Maps to use in addition to libmap.conf */
156 static bool trust; /* False for setuid and setgid programs */
157 static bool dangerous_ld_env; /* True if environment variables have been
158 used to affect the libraries loaded */
159 static char *ld_bind_now; /* Environment variable for immediate binding */
160 static char *ld_debug; /* Environment variable for debugging */
161 static char *ld_library_path; /* Environment variable for search path */
162 static char *ld_preload; /* Environment variable for libraries to
164 static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
165 static char *ld_tracing; /* Called from ldd to print libs */
166 static char *ld_utrace; /* Use utrace() to log events. */
167 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
168 static Obj_Entry **obj_tail; /* Link field of last object in list */
169 static Obj_Entry *obj_main; /* The main program shared object */
170 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
171 static unsigned int obj_count; /* Number of objects in obj_list */
172 static unsigned int obj_loads; /* Number of objects in obj_list */
174 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
175 STAILQ_HEAD_INITIALIZER(list_global);
176 static Objlist list_main = /* Objects loaded at program startup */
177 STAILQ_HEAD_INITIALIZER(list_main);
178 static Objlist list_fini = /* Objects needing fini() calls */
179 STAILQ_HEAD_INITIALIZER(list_fini);
181 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
183 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
185 extern Elf_Dyn _DYNAMIC;
186 #pragma weak _DYNAMIC
187 #ifndef RTLD_IS_DYNAMIC
188 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
192 * These are the functions the dynamic linker exports to application
193 * programs. They are the only symbols the dynamic linker is willing
194 * to export from itself.
196 static func_ptr_type exports[] = {
197 (func_ptr_type) &_rtld_error,
198 (func_ptr_type) &dlclose,
199 (func_ptr_type) &dlerror,
200 (func_ptr_type) &dlopen,
201 (func_ptr_type) &dlsym,
202 (func_ptr_type) &dlfunc,
203 (func_ptr_type) &dlvsym,
204 (func_ptr_type) &dladdr,
205 (func_ptr_type) &dllockinit,
206 (func_ptr_type) &dlinfo,
207 (func_ptr_type) &_rtld_thread_init,
209 (func_ptr_type) &___tls_get_addr,
211 (func_ptr_type) &__tls_get_addr,
212 (func_ptr_type) &_rtld_allocate_tls,
213 (func_ptr_type) &_rtld_free_tls,
214 (func_ptr_type) &dl_iterate_phdr,
215 (func_ptr_type) &_rtld_atfork_pre,
216 (func_ptr_type) &_rtld_atfork_post,
221 * Global declarations normally provided by crt1. The dynamic linker is
222 * not built with crt1, so we have to provide them ourselves.
228 * Globals to control TLS allocation.
230 size_t tls_last_offset; /* Static TLS offset of last module */
231 size_t tls_last_size; /* Static TLS size of last module */
232 size_t tls_static_space; /* Static TLS space allocated */
233 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
234 int tls_max_index = 1; /* Largest module index allocated */
237 * Fill in a DoneList with an allocation large enough to hold all of
238 * the currently-loaded objects. Keep this as a macro since it calls
239 * alloca and we want that to occur within the scope of the caller.
241 #define donelist_init(dlp) \
242 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
243 assert((dlp)->objs != NULL), \
244 (dlp)->num_alloc = obj_count, \
247 #define UTRACE_DLOPEN_START 1
248 #define UTRACE_DLOPEN_STOP 2
249 #define UTRACE_DLCLOSE_START 3
250 #define UTRACE_DLCLOSE_STOP 4
251 #define UTRACE_LOAD_OBJECT 5
252 #define UTRACE_UNLOAD_OBJECT 6
253 #define UTRACE_ADD_RUNDEP 7
254 #define UTRACE_PRELOAD_FINISHED 8
255 #define UTRACE_INIT_CALL 9
256 #define UTRACE_FINI_CALL 10
259 char sig[4]; /* 'RTLD' */
262 void *mapbase; /* Used for 'parent' and 'init/fini' */
264 int refcnt; /* Used for 'mode' */
265 char name[MAXPATHLEN];
268 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
269 if (ld_utrace != NULL) \
270 ld_utrace_log(e, h, mb, ms, r, n); \
274 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
275 int refcnt, const char *name)
277 struct utrace_rtld ut;
285 ut.mapbase = mapbase;
286 ut.mapsize = mapsize;
288 bzero(ut.name, sizeof(ut.name));
290 strlcpy(ut.name, name, sizeof(ut.name));
291 utrace(&ut, sizeof(ut));
295 * Main entry point for dynamic linking. The first argument is the
296 * stack pointer. The stack is expected to be laid out as described
297 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
298 * Specifically, the stack pointer points to a word containing
299 * ARGC. Following that in the stack is a null-terminated sequence
300 * of pointers to argument strings. Then comes a null-terminated
301 * sequence of pointers to environment strings. Finally, there is a
302 * sequence of "auxiliary vector" entries.
304 * The second argument points to a place to store the dynamic linker's
305 * exit procedure pointer and the third to a place to store the main
308 * The return value is the main program's entry point.
311 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
313 Elf_Auxinfo *aux_info[AT_COUNT];
321 Objlist_Entry *entry;
323 Obj_Entry **preload_tail;
328 * On entry, the dynamic linker itself has not been relocated yet.
329 * Be very careful not to reference any global data until after
330 * init_rtld has returned. It is OK to reference file-scope statics
331 * and string constants, and to call static and global functions.
334 /* Find the auxiliary vector on the stack. */
337 sp += argc + 1; /* Skip over arguments and NULL terminator */
339 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
341 aux = (Elf_Auxinfo *) sp;
343 /* Digest the auxiliary vector. */
344 for (i = 0; i < AT_COUNT; i++)
346 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
347 if (auxp->a_type < AT_COUNT)
348 aux_info[auxp->a_type] = auxp;
351 /* Initialize and relocate ourselves. */
352 assert(aux_info[AT_BASE] != NULL);
353 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
355 __progname = obj_rtld.path;
356 argv0 = argv[0] != NULL ? argv[0] : "(null)";
359 trust = !issetugid();
361 ld_bind_now = getenv(LD_ "BIND_NOW");
363 * If the process is tainted, then we un-set the dangerous environment
364 * variables. The process will be marked as tainted until setuid(2)
365 * is called. If any child process calls setuid(2) we do not want any
366 * future processes to honor the potentially un-safe variables.
369 if (unsetenv(LD_ "PRELOAD") || unsetenv(LD_ "LIBMAP") ||
370 unsetenv(LD_ "LIBRARY_PATH") || unsetenv(LD_ "LIBMAP_DISABLE") ||
371 unsetenv(LD_ "DEBUG") || unsetenv(LD_ "ELF_HINTS_PATH")) {
372 _rtld_error("environment corrupt; aborting");
376 ld_debug = getenv(LD_ "DEBUG");
377 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL;
378 libmap_override = getenv(LD_ "LIBMAP");
379 ld_library_path = getenv(LD_ "LIBRARY_PATH");
380 ld_preload = getenv(LD_ "PRELOAD");
381 ld_elf_hints_path = getenv(LD_ "ELF_HINTS_PATH");
382 dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
383 (ld_library_path != NULL) || (ld_preload != NULL) ||
384 (ld_elf_hints_path != NULL);
385 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS");
386 ld_utrace = getenv(LD_ "UTRACE");
388 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
389 ld_elf_hints_path = _PATH_ELF_HINTS;
391 if (ld_debug != NULL && *ld_debug != '\0')
393 dbg("%s is initialized, base address = %p", __progname,
394 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
395 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
396 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
399 * Load the main program, or process its program header if it is
402 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
403 int fd = aux_info[AT_EXECFD]->a_un.a_val;
404 dbg("loading main program");
405 obj_main = map_object(fd, argv0, NULL);
407 if (obj_main == NULL)
409 } else { /* Main program already loaded. */
410 const Elf_Phdr *phdr;
414 dbg("processing main program's program header");
415 assert(aux_info[AT_PHDR] != NULL);
416 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
417 assert(aux_info[AT_PHNUM] != NULL);
418 phnum = aux_info[AT_PHNUM]->a_un.a_val;
419 assert(aux_info[AT_PHENT] != NULL);
420 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
421 assert(aux_info[AT_ENTRY] != NULL);
422 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
423 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
427 if (aux_info[AT_EXECPATH] != 0) {
429 char buf[MAXPATHLEN];
431 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
432 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
433 if (kexecpath[0] == '/')
434 obj_main->path = kexecpath;
435 else if (getcwd(buf, sizeof(buf)) == NULL ||
436 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
437 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
438 obj_main->path = xstrdup(argv0);
440 obj_main->path = xstrdup(buf);
442 dbg("No AT_EXECPATH");
443 obj_main->path = xstrdup(argv0);
445 dbg("obj_main path %s", obj_main->path);
446 obj_main->mainprog = true;
449 * Get the actual dynamic linker pathname from the executable if
450 * possible. (It should always be possible.) That ensures that
451 * gdb will find the right dynamic linker even if a non-standard
454 if (obj_main->interp != NULL &&
455 strcmp(obj_main->interp, obj_rtld.path) != 0) {
457 obj_rtld.path = xstrdup(obj_main->interp);
458 __progname = obj_rtld.path;
461 digest_dynamic(obj_main, 0);
463 linkmap_add(obj_main);
464 linkmap_add(&obj_rtld);
466 /* Link the main program into the list of objects. */
467 *obj_tail = obj_main;
468 obj_tail = &obj_main->next;
471 /* Make sure we don't call the main program's init and fini functions. */
472 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
474 /* Initialize a fake symbol for resolving undefined weak references. */
475 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
476 sym_zero.st_shndx = SHN_UNDEF;
477 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
480 libmap_disable = (bool)lm_init(libmap_override);
482 dbg("loading LD_PRELOAD libraries");
483 if (load_preload_objects() == -1)
485 preload_tail = obj_tail;
487 dbg("loading needed objects");
488 if (load_needed_objects(obj_main) == -1)
491 /* Make a list of all objects loaded at startup. */
492 for (obj = obj_list; obj != NULL; obj = obj->next) {
493 objlist_push_tail(&list_main, obj);
497 dbg("checking for required versions");
498 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
501 if (ld_tracing) { /* We're done */
502 trace_loaded_objects(obj_main);
506 if (getenv(LD_ "DUMP_REL_PRE") != NULL) {
507 dump_relocations(obj_main);
511 /* setup TLS for main thread */
512 dbg("initializing initial thread local storage");
513 STAILQ_FOREACH(entry, &list_main, link) {
515 * Allocate all the initial objects out of the static TLS
516 * block even if they didn't ask for it.
518 allocate_tls_offset(entry->obj);
520 allocate_initial_tls(obj_list);
522 if (relocate_objects(obj_main,
523 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1)
526 dbg("doing copy relocations");
527 if (do_copy_relocations(obj_main) == -1)
530 if (getenv(LD_ "DUMP_REL_POST") != NULL) {
531 dump_relocations(obj_main);
535 dbg("initializing key program variables");
536 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
537 set_program_var("environ", env);
539 dbg("initializing thread locks");
542 /* Make a list of init functions to call. */
543 objlist_init(&initlist);
544 initlist_add_objects(obj_list, preload_tail, &initlist);
546 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
548 lockstate = wlock_acquire(rtld_bind_lock);
549 objlist_call_init(&initlist, &lockstate);
550 objlist_clear(&initlist);
551 wlock_release(rtld_bind_lock, lockstate);
553 dbg("transferring control to program entry point = %p", obj_main->entry);
555 /* Return the exit procedure and the program entry point. */
556 *exit_proc = rtld_exit;
558 return (func_ptr_type) obj_main->entry;
562 _rtld_bind(Obj_Entry *obj, Elf_Size reloff)
566 const Obj_Entry *defobj;
571 lockstate = rlock_acquire(rtld_bind_lock);
573 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
575 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
577 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
578 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
582 target = (Elf_Addr)(defobj->relocbase + def->st_value);
584 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
585 defobj->strtab + def->st_name, basename(obj->path),
586 (void *)target, basename(defobj->path));
589 * Write the new contents for the jmpslot. Note that depending on
590 * architecture, the value which we need to return back to the
591 * lazy binding trampoline may or may not be the target
592 * address. The value returned from reloc_jmpslot() is the value
593 * that the trampoline needs.
595 target = reloc_jmpslot(where, target, defobj, obj, rel);
596 rlock_release(rtld_bind_lock, lockstate);
601 * Error reporting function. Use it like printf. If formats the message
602 * into a buffer, and sets things up so that the next call to dlerror()
603 * will return the message.
606 _rtld_error(const char *fmt, ...)
608 static char buf[512];
612 vsnprintf(buf, sizeof buf, fmt, ap);
618 * Return a dynamically-allocated copy of the current error message, if any.
623 return error_message == NULL ? NULL : xstrdup(error_message);
627 * Restore the current error message from a copy which was previously saved
628 * by errmsg_save(). The copy is freed.
631 errmsg_restore(char *saved_msg)
633 if (saved_msg == NULL)
634 error_message = NULL;
636 _rtld_error("%s", saved_msg);
642 basename(const char *name)
644 const char *p = strrchr(name, '/');
645 return p != NULL ? p + 1 : name;
648 static struct utsname uts;
651 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
661 subst_len = kw_len = 0;
665 if (subst_len == 0) {
666 subst_len = strlen(subst);
670 *res = xmalloc(PATH_MAX);
673 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
674 _rtld_error("Substitution of %s in %s cannot be performed",
676 if (may_free != NULL)
681 memcpy(res1, p, p1 - p);
683 memcpy(res1, subst, subst_len);
688 if (may_free != NULL)
691 *res = xstrdup(real);
695 if (may_free != NULL)
697 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
707 origin_subst(const char *real, const char *origin_path)
709 char *res1, *res2, *res3, *res4;
711 if (uts.sysname[0] == '\0') {
712 if (uname(&uts) != 0) {
713 _rtld_error("utsname failed: %d", errno);
717 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
718 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
719 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
720 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
728 const char *msg = dlerror();
736 * Process a shared object's DYNAMIC section, and save the important
737 * information in its Obj_Entry structure.
740 digest_dynamic(Obj_Entry *obj, int early)
743 Needed_Entry **needed_tail = &obj->needed;
744 const Elf_Dyn *dyn_rpath = NULL;
745 const Elf_Dyn *dyn_soname = NULL;
746 int plttype = DT_REL;
748 obj->bind_now = false;
749 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
750 switch (dynp->d_tag) {
753 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
757 obj->relsize = dynp->d_un.d_val;
761 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
765 obj->pltrel = (const Elf_Rel *)
766 (obj->relocbase + dynp->d_un.d_ptr);
770 obj->pltrelsize = dynp->d_un.d_val;
774 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
778 obj->relasize = dynp->d_un.d_val;
782 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
786 plttype = dynp->d_un.d_val;
787 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
791 obj->symtab = (const Elf_Sym *)
792 (obj->relocbase + dynp->d_un.d_ptr);
796 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
800 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
804 obj->strsize = dynp->d_un.d_val;
808 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
813 obj->verneednum = dynp->d_un.d_val;
817 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
822 obj->verdefnum = dynp->d_un.d_val;
826 obj->versyms = (const Elf_Versym *)(obj->relocbase +
832 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
833 (obj->relocbase + dynp->d_un.d_ptr);
834 obj->nbuckets = hashtab[0];
835 obj->nchains = hashtab[1];
836 obj->buckets = hashtab + 2;
837 obj->chains = obj->buckets + obj->nbuckets;
843 Needed_Entry *nep = NEW(Needed_Entry);
844 nep->name = dynp->d_un.d_val;
849 needed_tail = &nep->next;
854 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
862 obj->symbolic = true;
866 case DT_RUNPATH: /* XXX: process separately */
868 * We have to wait until later to process this, because we
869 * might not have gotten the address of the string table yet.
879 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
883 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
887 * Don't process DT_DEBUG on MIPS as the dynamic section
888 * is mapped read-only. DT_MIPS_RLD_MAP is used instead.
893 /* XXX - not implemented yet */
895 dbg("Filling in DT_DEBUG entry");
896 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
901 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
902 obj->z_origin = true;
903 if (dynp->d_un.d_val & DF_SYMBOLIC)
904 obj->symbolic = true;
905 if (dynp->d_un.d_val & DF_TEXTREL)
907 if (dynp->d_un.d_val & DF_BIND_NOW)
908 obj->bind_now = true;
909 if (dynp->d_un.d_val & DF_STATIC_TLS)
913 case DT_MIPS_LOCAL_GOTNO:
914 obj->local_gotno = dynp->d_un.d_val;
917 case DT_MIPS_SYMTABNO:
918 obj->symtabno = dynp->d_un.d_val;
922 obj->gotsym = dynp->d_un.d_val;
925 case DT_MIPS_RLD_MAP:
928 dbg("Filling in DT_DEBUG entry");
929 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
935 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
936 obj->z_origin = true;
937 if (dynp->d_un.d_val & DF_1_GLOBAL)
939 if (dynp->d_un.d_val & DF_1_BIND_NOW)
940 obj->bind_now = true;
941 if (dynp->d_un.d_val & DF_1_NODELETE)
942 obj->z_nodelete = true;
947 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
956 if (plttype == DT_RELA) {
957 obj->pltrela = (const Elf_Rela *) obj->pltrel;
959 obj->pltrelasize = obj->pltrelsize;
963 if (obj->z_origin && obj->origin_path == NULL) {
964 obj->origin_path = xmalloc(PATH_MAX);
965 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
969 if (dyn_rpath != NULL) {
970 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
972 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
975 if (dyn_soname != NULL)
976 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
980 * Process a shared object's program header. This is used only for the
981 * main program, when the kernel has already loaded the main program
982 * into memory before calling the dynamic linker. It creates and
983 * returns an Obj_Entry structure.
986 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
989 const Elf_Phdr *phlimit = phdr + phnum;
994 for (ph = phdr; ph < phlimit; ph++) {
995 if (ph->p_type != PT_PHDR)
999 obj->phsize = ph->p_memsz;
1000 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1004 for (ph = phdr; ph < phlimit; ph++) {
1005 switch (ph->p_type) {
1008 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1012 if (nsegs == 0) { /* First load segment */
1013 obj->vaddrbase = trunc_page(ph->p_vaddr);
1014 obj->mapbase = obj->vaddrbase + obj->relocbase;
1015 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1017 } else { /* Last load segment */
1018 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1025 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1030 obj->tlssize = ph->p_memsz;
1031 obj->tlsalign = ph->p_align;
1032 obj->tlsinitsize = ph->p_filesz;
1033 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1038 _rtld_error("%s: too few PT_LOAD segments", path);
1047 dlcheck(void *handle)
1051 for (obj = obj_list; obj != NULL; obj = obj->next)
1052 if (obj == (Obj_Entry *) handle)
1055 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1056 _rtld_error("Invalid shared object handle %p", handle);
1063 * If the given object is already in the donelist, return true. Otherwise
1064 * add the object to the list and return false.
1067 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1071 for (i = 0; i < dlp->num_used; i++)
1072 if (dlp->objs[i] == obj)
1075 * Our donelist allocation should always be sufficient. But if
1076 * our threads locking isn't working properly, more shared objects
1077 * could have been loaded since we allocated the list. That should
1078 * never happen, but we'll handle it properly just in case it does.
1080 if (dlp->num_used < dlp->num_alloc)
1081 dlp->objs[dlp->num_used++] = obj;
1086 * Hash function for symbol table lookup. Don't even think about changing
1087 * this. It is specified by the System V ABI.
1090 elf_hash(const char *name)
1092 const unsigned char *p = (const unsigned char *) name;
1093 unsigned long h = 0;
1096 while (*p != '\0') {
1097 h = (h << 4) + *p++;
1098 if ((g = h & 0xf0000000) != 0)
1106 * Find the library with the given name, and return its full pathname.
1107 * The returned string is dynamically allocated. Generates an error
1108 * message and returns NULL if the library cannot be found.
1110 * If the second argument is non-NULL, then it refers to an already-
1111 * loaded shared object, whose library search path will be searched.
1113 * The search order is:
1115 * rpath in the referencing file
1120 find_library(const char *xname, const Obj_Entry *refobj)
1125 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1126 if (xname[0] != '/' && !trust) {
1127 _rtld_error("Absolute pathname required for shared object \"%s\"",
1131 if (refobj != NULL && refobj->z_origin)
1132 return origin_subst(xname, refobj->origin_path);
1134 return xstrdup(xname);
1137 if (libmap_disable || (refobj == NULL) ||
1138 (name = lm_find(refobj->path, xname)) == NULL)
1139 name = (char *)xname;
1141 dbg(" Searching for \"%s\"", name);
1143 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1145 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1146 (pathname = search_library_path(name, gethints())) != NULL ||
1147 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1150 if(refobj != NULL && refobj->path != NULL) {
1151 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1152 name, basename(refobj->path));
1154 _rtld_error("Shared object \"%s\" not found", name);
1160 * Given a symbol number in a referencing object, find the corresponding
1161 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1162 * no definition was found. Returns a pointer to the Obj_Entry of the
1163 * defining object via the reference parameter DEFOBJ_OUT.
1166 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1167 const Obj_Entry **defobj_out, int flags, SymCache *cache)
1171 const Obj_Entry *defobj;
1172 const Ver_Entry *ventry;
1177 * If we have already found this symbol, get the information from
1180 if (symnum >= refobj->nchains)
1181 return NULL; /* Bad object */
1182 if (cache != NULL && cache[symnum].sym != NULL) {
1183 *defobj_out = cache[symnum].obj;
1184 return cache[symnum].sym;
1187 ref = refobj->symtab + symnum;
1188 name = refobj->strtab + ref->st_name;
1192 * We don't have to do a full scale lookup if the symbol is local.
1193 * We know it will bind to the instance in this load module; to
1194 * which we already have a pointer (ie ref). By not doing a lookup,
1195 * we not only improve performance, but it also avoids unresolvable
1196 * symbols when local symbols are not in the hash table. This has
1197 * been seen with the ia64 toolchain.
1199 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1200 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1201 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1204 ventry = fetch_ventry(refobj, symnum);
1205 hash = elf_hash(name);
1206 def = symlook_default(name, hash, refobj, &defobj, ventry, flags);
1213 * If we found no definition and the reference is weak, treat the
1214 * symbol as having the value zero.
1216 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1222 *defobj_out = defobj;
1223 /* Record the information in the cache to avoid subsequent lookups. */
1224 if (cache != NULL) {
1225 cache[symnum].sym = def;
1226 cache[symnum].obj = defobj;
1229 if (refobj != &obj_rtld)
1230 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1236 * Return the search path from the ldconfig hints file, reading it if
1237 * necessary. Returns NULL if there are problems with the hints file,
1238 * or if the search path there is empty.
1245 if (hints == NULL) {
1247 struct elfhints_hdr hdr;
1250 /* Keep from trying again in case the hints file is bad. */
1253 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1255 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1256 hdr.magic != ELFHINTS_MAGIC ||
1261 p = xmalloc(hdr.dirlistlen + 1);
1262 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1263 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1271 return hints[0] != '\0' ? hints : NULL;
1275 init_dag(Obj_Entry *root)
1279 donelist_init(&donelist);
1280 init_dag1(root, root, &donelist);
1284 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1286 const Needed_Entry *needed;
1288 if (donelist_check(dlp, obj))
1292 objlist_push_tail(&obj->dldags, root);
1293 objlist_push_tail(&root->dagmembers, obj);
1294 for (needed = obj->needed; needed != NULL; needed = needed->next)
1295 if (needed->obj != NULL)
1296 init_dag1(root, needed->obj, dlp);
1300 * Initialize the dynamic linker. The argument is the address at which
1301 * the dynamic linker has been mapped into memory. The primary task of
1302 * this function is to relocate the dynamic linker.
1305 init_rtld(caddr_t mapbase)
1307 Obj_Entry objtmp; /* Temporary rtld object */
1310 * Conjure up an Obj_Entry structure for the dynamic linker.
1312 * The "path" member can't be initialized yet because string constants
1313 * cannot yet be accessed. Below we will set it correctly.
1315 memset(&objtmp, 0, sizeof(objtmp));
1318 objtmp.mapbase = mapbase;
1320 objtmp.relocbase = mapbase;
1322 if (RTLD_IS_DYNAMIC()) {
1323 objtmp.dynamic = rtld_dynamic(&objtmp);
1324 digest_dynamic(&objtmp, 1);
1325 assert(objtmp.needed == NULL);
1326 #if !defined(__mips__)
1327 /* MIPS and SH{3,5} have a bogus DT_TEXTREL. */
1328 assert(!objtmp.textrel);
1332 * Temporarily put the dynamic linker entry into the object list, so
1333 * that symbols can be found.
1336 relocate_objects(&objtmp, true, &objtmp);
1339 /* Initialize the object list. */
1340 obj_tail = &obj_list;
1342 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1343 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1345 /* Replace the path with a dynamically allocated copy. */
1346 obj_rtld.path = xstrdup(PATH_RTLD);
1348 r_debug.r_brk = r_debug_state;
1349 r_debug.r_state = RT_CONSISTENT;
1353 * Add the init functions from a needed object list (and its recursive
1354 * needed objects) to "list". This is not used directly; it is a helper
1355 * function for initlist_add_objects(). The write lock must be held
1356 * when this function is called.
1359 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1361 /* Recursively process the successor needed objects. */
1362 if (needed->next != NULL)
1363 initlist_add_neededs(needed->next, list);
1365 /* Process the current needed object. */
1366 if (needed->obj != NULL)
1367 initlist_add_objects(needed->obj, &needed->obj->next, list);
1371 * Scan all of the DAGs rooted in the range of objects from "obj" to
1372 * "tail" and add their init functions to "list". This recurses over
1373 * the DAGs and ensure the proper init ordering such that each object's
1374 * needed libraries are initialized before the object itself. At the
1375 * same time, this function adds the objects to the global finalization
1376 * list "list_fini" in the opposite order. The write lock must be
1377 * held when this function is called.
1380 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1382 if (obj->init_scanned || obj->init_done)
1384 obj->init_scanned = true;
1386 /* Recursively process the successor objects. */
1387 if (&obj->next != tail)
1388 initlist_add_objects(obj->next, tail, list);
1390 /* Recursively process the needed objects. */
1391 if (obj->needed != NULL)
1392 initlist_add_neededs(obj->needed, list);
1394 /* Add the object to the init list. */
1395 if (obj->init != (Elf_Addr)NULL)
1396 objlist_push_tail(list, obj);
1398 /* Add the object to the global fini list in the reverse order. */
1399 if (obj->fini != (Elf_Addr)NULL && !obj->on_fini_list) {
1400 objlist_push_head(&list_fini, obj);
1401 obj->on_fini_list = true;
1406 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1410 is_exported(const Elf_Sym *def)
1413 const func_ptr_type *p;
1415 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1416 for (p = exports; *p != NULL; p++)
1417 if (FPTR_TARGET(*p) == value)
1423 * Given a shared object, traverse its list of needed objects, and load
1424 * each of them. Returns 0 on success. Generates an error message and
1425 * returns -1 on failure.
1428 load_needed_objects(Obj_Entry *first)
1430 Obj_Entry *obj, *obj1;
1432 for (obj = first; obj != NULL; obj = obj->next) {
1433 Needed_Entry *needed;
1435 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1436 obj1 = needed->obj = load_object(obj->strtab + needed->name, obj,
1438 if (obj1 == NULL && !ld_tracing)
1440 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1441 dbg("obj %s nodelete", obj1->path);
1444 obj1->ref_nodel = true;
1453 load_preload_objects(void)
1455 char *p = ld_preload;
1456 static const char delim[] = " \t:;";
1461 p += strspn(p, delim);
1462 while (*p != '\0') {
1463 size_t len = strcspn(p, delim);
1468 if (load_object(p, NULL, false) == NULL)
1469 return -1; /* XXX - cleanup */
1472 p += strspn(p, delim);
1474 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
1479 * Load a shared object into memory, if it is not already loaded.
1481 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1485 load_object(const char *name, const Obj_Entry *refobj, int noload)
1492 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1493 if (object_match_name(obj, name))
1496 path = find_library(name, refobj);
1501 * If we didn't find a match by pathname, open the file and check
1502 * again by device and inode. This avoids false mismatches caused
1503 * by multiple links or ".." in pathnames.
1505 * To avoid a race, we open the file and use fstat() rather than
1508 if ((fd = open(path, O_RDONLY)) == -1) {
1509 _rtld_error("Cannot open \"%s\"", path);
1513 if (fstat(fd, &sb) == -1) {
1514 _rtld_error("Cannot fstat \"%s\"", path);
1519 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1520 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
1526 object_add_name(obj, name);
1534 /* First use of this object, so we must map it in */
1535 obj = do_load_object(fd, name, path, &sb);
1544 do_load_object(int fd, const char *name, char *path, struct stat *sbp)
1550 * but first, make sure that environment variables haven't been
1551 * used to circumvent the noexec flag on a filesystem.
1553 if (dangerous_ld_env) {
1554 if (fstatfs(fd, &fs) != 0) {
1555 _rtld_error("Cannot fstatfs \"%s\"", path);
1558 if (fs.f_flags & MNT_NOEXEC) {
1559 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
1563 dbg("loading \"%s\"", path);
1564 obj = map_object(fd, path, sbp);
1568 object_add_name(obj, name);
1570 digest_dynamic(obj, 0);
1573 obj_tail = &obj->next;
1576 linkmap_add(obj); /* for GDB & dlinfo() */
1578 dbg(" %p .. %p: %s", obj->mapbase,
1579 obj->mapbase + obj->mapsize - 1, obj->path);
1581 dbg(" WARNING: %s has impure text", obj->path);
1582 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
1589 obj_from_addr(const void *addr)
1593 for (obj = obj_list; obj != NULL; obj = obj->next) {
1594 if (addr < (void *) obj->mapbase)
1596 if (addr < (void *) (obj->mapbase + obj->mapsize))
1603 * Call the finalization functions for each of the objects in "list"
1604 * which are unreferenced. All of the objects are expected to have
1605 * non-NULL fini functions.
1608 objlist_call_fini(Objlist *list, bool force, int *lockstate)
1610 Objlist_Entry *elm, *elm_tmp;
1614 * Preserve the current error message since a fini function might
1615 * call into the dynamic linker and overwrite it.
1617 saved_msg = errmsg_save();
1618 STAILQ_FOREACH_SAFE(elm, list, link, elm_tmp) {
1619 if (elm->obj->refcount == 0 || force) {
1620 dbg("calling fini function for %s at %p", elm->obj->path,
1621 (void *)elm->obj->fini);
1622 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini, 0, 0,
1624 /* Remove object from fini list to prevent recursive invocation. */
1625 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1626 wlock_release(rtld_bind_lock, *lockstate);
1627 call_initfini_pointer(elm->obj, elm->obj->fini);
1628 *lockstate = wlock_acquire(rtld_bind_lock);
1629 /* No need to free anything if process is going down. */
1634 errmsg_restore(saved_msg);
1638 * Call the initialization functions for each of the objects in
1639 * "list". All of the objects are expected to have non-NULL init
1643 objlist_call_init(Objlist *list, int *lockstate)
1650 * Clean init_scanned flag so that objects can be rechecked and
1651 * possibly initialized earlier if any of vectors called below
1652 * cause the change by using dlopen.
1654 for (obj = obj_list; obj != NULL; obj = obj->next)
1655 obj->init_scanned = false;
1658 * Preserve the current error message since an init function might
1659 * call into the dynamic linker and overwrite it.
1661 saved_msg = errmsg_save();
1662 STAILQ_FOREACH(elm, list, link) {
1663 if (elm->obj->init_done) /* Initialized early. */
1665 dbg("calling init function for %s at %p", elm->obj->path,
1666 (void *)elm->obj->init);
1667 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init, 0, 0,
1670 * Race: other thread might try to use this object before current
1671 * one completes the initilization. Not much can be done here
1672 * without better locking.
1674 elm->obj->init_done = true;
1675 wlock_release(rtld_bind_lock, *lockstate);
1676 call_initfini_pointer(elm->obj, elm->obj->init);
1677 *lockstate = wlock_acquire(rtld_bind_lock);
1679 errmsg_restore(saved_msg);
1683 objlist_clear(Objlist *list)
1687 while (!STAILQ_EMPTY(list)) {
1688 elm = STAILQ_FIRST(list);
1689 STAILQ_REMOVE_HEAD(list, link);
1694 static Objlist_Entry *
1695 objlist_find(Objlist *list, const Obj_Entry *obj)
1699 STAILQ_FOREACH(elm, list, link)
1700 if (elm->obj == obj)
1706 objlist_init(Objlist *list)
1712 objlist_push_head(Objlist *list, Obj_Entry *obj)
1716 elm = NEW(Objlist_Entry);
1718 STAILQ_INSERT_HEAD(list, elm, link);
1722 objlist_push_tail(Objlist *list, Obj_Entry *obj)
1726 elm = NEW(Objlist_Entry);
1728 STAILQ_INSERT_TAIL(list, elm, link);
1732 objlist_remove(Objlist *list, Obj_Entry *obj)
1736 if ((elm = objlist_find(list, obj)) != NULL) {
1737 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1743 * Relocate newly-loaded shared objects. The argument is a pointer to
1744 * the Obj_Entry for the first such object. All objects from the first
1745 * to the end of the list of objects are relocated. Returns 0 on success,
1749 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj)
1753 for (obj = first; obj != NULL; obj = obj->next) {
1755 dbg("relocating \"%s\"", obj->path);
1756 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1757 obj->symtab == NULL || obj->strtab == NULL) {
1758 _rtld_error("%s: Shared object has no run-time symbol table",
1764 /* There are relocations to the write-protected text segment. */
1765 if (mprotect(obj->mapbase, obj->textsize,
1766 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1767 _rtld_error("%s: Cannot write-enable text segment: %s",
1768 obj->path, strerror(errno));
1773 /* Process the non-PLT relocations. */
1774 if (reloc_non_plt(obj, rtldobj))
1777 if (obj->textrel) { /* Re-protected the text segment. */
1778 if (mprotect(obj->mapbase, obj->textsize,
1779 PROT_READ|PROT_EXEC) == -1) {
1780 _rtld_error("%s: Cannot write-protect text segment: %s",
1781 obj->path, strerror(errno));
1786 /* Process the PLT relocations. */
1787 if (reloc_plt(obj) == -1)
1789 /* Relocate the jump slots if we are doing immediate binding. */
1790 if (obj->bind_now || bind_now)
1791 if (reloc_jmpslots(obj) == -1)
1796 * Set up the magic number and version in the Obj_Entry. These
1797 * were checked in the crt1.o from the original ElfKit, so we
1798 * set them for backward compatibility.
1800 obj->magic = RTLD_MAGIC;
1801 obj->version = RTLD_VERSION;
1803 /* Set the special PLT or GOT entries. */
1811 * Cleanup procedure. It will be called (by the atexit mechanism) just
1812 * before the process exits.
1819 lockstate = wlock_acquire(rtld_bind_lock);
1821 objlist_call_fini(&list_fini, true, &lockstate);
1822 /* No need to remove the items from the list, since we are exiting. */
1823 if (!libmap_disable)
1825 wlock_release(rtld_bind_lock, lockstate);
1829 path_enumerate(const char *path, path_enum_proc callback, void *arg)
1837 path += strspn(path, ":;");
1838 while (*path != '\0') {
1842 len = strcspn(path, ":;");
1844 trans = lm_findn(NULL, path, len);
1846 res = callback(trans, strlen(trans), arg);
1849 res = callback(path, len, arg);
1855 path += strspn(path, ":;");
1861 struct try_library_args {
1869 try_library_path(const char *dir, size_t dirlen, void *param)
1871 struct try_library_args *arg;
1874 if (*dir == '/' || trust) {
1877 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1880 pathname = arg->buffer;
1881 strncpy(pathname, dir, dirlen);
1882 pathname[dirlen] = '/';
1883 strcpy(pathname + dirlen + 1, arg->name);
1885 dbg(" Trying \"%s\"", pathname);
1886 if (access(pathname, F_OK) == 0) { /* We found it */
1887 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1888 strcpy(pathname, arg->buffer);
1896 search_library_path(const char *name, const char *path)
1899 struct try_library_args arg;
1905 arg.namelen = strlen(name);
1906 arg.buffer = xmalloc(PATH_MAX);
1907 arg.buflen = PATH_MAX;
1909 p = path_enumerate(path, try_library_path, &arg);
1917 dlclose(void *handle)
1922 lockstate = wlock_acquire(rtld_bind_lock);
1923 root = dlcheck(handle);
1925 wlock_release(rtld_bind_lock, lockstate);
1928 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
1931 /* Unreference the object and its dependencies. */
1932 root->dl_refcount--;
1936 if (root->refcount == 0) {
1938 * The object is no longer referenced, so we must unload it.
1939 * First, call the fini functions.
1941 objlist_call_fini(&list_fini, false, &lockstate);
1943 /* Finish cleaning up the newly-unreferenced objects. */
1944 GDB_STATE(RT_DELETE,&root->linkmap);
1945 unload_object(root);
1946 GDB_STATE(RT_CONSISTENT,NULL);
1948 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
1949 wlock_release(rtld_bind_lock, lockstate);
1956 char *msg = error_message;
1957 error_message = NULL;
1962 * This function is deprecated and has no effect.
1965 dllockinit(void *context,
1966 void *(*lock_create)(void *context),
1967 void (*rlock_acquire)(void *lock),
1968 void (*wlock_acquire)(void *lock),
1969 void (*lock_release)(void *lock),
1970 void (*lock_destroy)(void *lock),
1971 void (*context_destroy)(void *context))
1973 static void *cur_context;
1974 static void (*cur_context_destroy)(void *);
1976 /* Just destroy the context from the previous call, if necessary. */
1977 if (cur_context_destroy != NULL)
1978 cur_context_destroy(cur_context);
1979 cur_context = context;
1980 cur_context_destroy = context_destroy;
1984 dlopen(const char *name, int mode)
1986 Obj_Entry **old_obj_tail;
1989 int result, lockstate, nodelete, noload;
1991 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
1992 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1993 if (ld_tracing != NULL)
1994 environ = (char **)*get_program_var_addr("environ");
1995 nodelete = mode & RTLD_NODELETE;
1996 noload = mode & RTLD_NOLOAD;
1998 objlist_init(&initlist);
2000 lockstate = wlock_acquire(rtld_bind_lock);
2001 GDB_STATE(RT_ADD,NULL);
2003 old_obj_tail = obj_tail;
2009 obj = load_object(name, obj_main, noload);
2014 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2015 objlist_push_tail(&list_global, obj);
2016 mode &= RTLD_MODEMASK;
2017 if (*old_obj_tail != NULL) { /* We loaded something new. */
2018 assert(*old_obj_tail == obj);
2019 result = load_needed_objects(obj);
2022 result = rtld_verify_versions(&obj->dagmembers);
2023 if (result != -1 && ld_tracing)
2026 (relocate_objects(obj, mode == RTLD_NOW, &obj_rtld)) == -1) {
2029 if (obj->refcount == 0)
2033 /* Make list of init functions to call. */
2034 initlist_add_objects(obj, &obj->next, &initlist);
2038 /* Bump the reference counts for objects on this DAG. */
2044 if (obj != NULL && (nodelete || obj->z_nodelete) && !obj->ref_nodel) {
2045 dbg("obj %s nodelete", obj->path);
2047 obj->z_nodelete = obj->ref_nodel = true;
2051 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2053 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2055 /* Call the init functions. */
2056 objlist_call_init(&initlist, &lockstate);
2057 objlist_clear(&initlist);
2058 wlock_release(rtld_bind_lock, lockstate);
2061 trace_loaded_objects(obj);
2062 wlock_release(rtld_bind_lock, lockstate);
2067 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2071 const Obj_Entry *obj, *defobj;
2072 const Elf_Sym *def, *symp;
2076 hash = elf_hash(name);
2079 flags |= SYMLOOK_IN_PLT;
2081 lockstate = rlock_acquire(rtld_bind_lock);
2082 if (handle == NULL || handle == RTLD_NEXT ||
2083 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2085 if ((obj = obj_from_addr(retaddr)) == NULL) {
2086 _rtld_error("Cannot determine caller's shared object");
2087 rlock_release(rtld_bind_lock, lockstate);
2090 if (handle == NULL) { /* Just the caller's shared object. */
2091 def = symlook_obj(name, hash, obj, ve, flags);
2093 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2094 handle == RTLD_SELF) { /* ... caller included */
2095 if (handle == RTLD_NEXT)
2097 for (; obj != NULL; obj = obj->next) {
2098 if ((symp = symlook_obj(name, hash, obj, ve, flags)) != NULL) {
2099 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2102 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2108 * Search the dynamic linker itself, and possibly resolve the
2109 * symbol from there. This is how the application links to
2110 * dynamic linker services such as dlopen. Only the values listed
2111 * in the "exports" array can be resolved from the dynamic linker.
2113 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2114 symp = symlook_obj(name, hash, &obj_rtld, ve, flags);
2115 if (symp != NULL && is_exported(symp)) {
2121 assert(handle == RTLD_DEFAULT);
2122 def = symlook_default(name, hash, obj, &defobj, ve, flags);
2125 if ((obj = dlcheck(handle)) == NULL) {
2126 rlock_release(rtld_bind_lock, lockstate);
2130 donelist_init(&donelist);
2131 if (obj->mainprog) {
2132 /* Search main program and all libraries loaded by it. */
2133 def = symlook_list(name, hash, &list_main, &defobj, ve, flags,
2137 * We do not distinguish between 'main' object and global scope.
2138 * If symbol is not defined by objects loaded at startup, continue
2139 * search among dynamically loaded objects with RTLD_GLOBAL
2143 def = symlook_list(name, hash, &list_global, &defobj, ve,
2148 /* Search the whole DAG rooted at the given object. */
2150 fake.obj = (Obj_Entry *)obj;
2152 def = symlook_needed(name, hash, &fake, &defobj, ve, flags,
2158 rlock_release(rtld_bind_lock, lockstate);
2161 * The value required by the caller is derived from the value
2162 * of the symbol. For the ia64 architecture, we need to
2163 * construct a function descriptor which the caller can use to
2164 * call the function with the right 'gp' value. For other
2165 * architectures and for non-functions, the value is simply
2166 * the relocated value of the symbol.
2168 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
2169 return make_function_pointer(def, defobj);
2171 return defobj->relocbase + def->st_value;
2174 _rtld_error("Undefined symbol \"%s\"", name);
2175 rlock_release(rtld_bind_lock, lockstate);
2180 dlsym(void *handle, const char *name)
2182 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
2187 dlfunc(void *handle, const char *name)
2194 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
2200 dlvsym(void *handle, const char *name, const char *version)
2204 ventry.name = version;
2206 ventry.hash = elf_hash(version);
2208 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
2213 dladdr(const void *addr, Dl_info *info)
2215 const Obj_Entry *obj;
2218 unsigned long symoffset;
2221 lockstate = rlock_acquire(rtld_bind_lock);
2222 obj = obj_from_addr(addr);
2224 _rtld_error("No shared object contains address");
2225 rlock_release(rtld_bind_lock, lockstate);
2228 info->dli_fname = obj->path;
2229 info->dli_fbase = obj->mapbase;
2230 info->dli_saddr = (void *)0;
2231 info->dli_sname = NULL;
2234 * Walk the symbol list looking for the symbol whose address is
2235 * closest to the address sent in.
2237 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
2238 def = obj->symtab + symoffset;
2241 * For skip the symbol if st_shndx is either SHN_UNDEF or
2244 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
2248 * If the symbol is greater than the specified address, or if it
2249 * is further away from addr than the current nearest symbol,
2252 symbol_addr = obj->relocbase + def->st_value;
2253 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
2256 /* Update our idea of the nearest symbol. */
2257 info->dli_sname = obj->strtab + def->st_name;
2258 info->dli_saddr = symbol_addr;
2261 if (info->dli_saddr == addr)
2264 rlock_release(rtld_bind_lock, lockstate);
2269 dlinfo(void *handle, int request, void *p)
2271 const Obj_Entry *obj;
2272 int error, lockstate;
2274 lockstate = rlock_acquire(rtld_bind_lock);
2276 if (handle == NULL || handle == RTLD_SELF) {
2279 retaddr = __builtin_return_address(0); /* __GNUC__ only */
2280 if ((obj = obj_from_addr(retaddr)) == NULL)
2281 _rtld_error("Cannot determine caller's shared object");
2283 obj = dlcheck(handle);
2286 rlock_release(rtld_bind_lock, lockstate);
2292 case RTLD_DI_LINKMAP:
2293 *((struct link_map const **)p) = &obj->linkmap;
2295 case RTLD_DI_ORIGIN:
2296 error = rtld_dirname(obj->path, p);
2299 case RTLD_DI_SERINFOSIZE:
2300 case RTLD_DI_SERINFO:
2301 error = do_search_info(obj, request, (struct dl_serinfo *)p);
2305 _rtld_error("Invalid request %d passed to dlinfo()", request);
2309 rlock_release(rtld_bind_lock, lockstate);
2315 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
2317 struct dl_phdr_info phdr_info;
2318 const Obj_Entry *obj;
2319 int error, bind_lockstate, phdr_lockstate;
2321 phdr_lockstate = wlock_acquire(rtld_phdr_lock);
2322 bind_lockstate = rlock_acquire(rtld_bind_lock);
2326 for (obj = obj_list; obj != NULL; obj = obj->next) {
2327 phdr_info.dlpi_addr = (Elf_Addr)obj->relocbase;
2328 phdr_info.dlpi_name = STAILQ_FIRST(&obj->names) ?
2329 STAILQ_FIRST(&obj->names)->name : obj->path;
2330 phdr_info.dlpi_phdr = obj->phdr;
2331 phdr_info.dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
2332 phdr_info.dlpi_tls_modid = obj->tlsindex;
2333 phdr_info.dlpi_tls_data = obj->tlsinit;
2334 phdr_info.dlpi_adds = obj_loads;
2335 phdr_info.dlpi_subs = obj_loads - obj_count;
2337 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
2341 rlock_release(rtld_bind_lock, bind_lockstate);
2342 wlock_release(rtld_phdr_lock, phdr_lockstate);
2347 struct fill_search_info_args {
2350 Dl_serinfo *serinfo;
2351 Dl_serpath *serpath;
2356 fill_search_info(const char *dir, size_t dirlen, void *param)
2358 struct fill_search_info_args *arg;
2362 if (arg->request == RTLD_DI_SERINFOSIZE) {
2363 arg->serinfo->dls_cnt ++;
2364 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1;
2366 struct dl_serpath *s_entry;
2368 s_entry = arg->serpath;
2369 s_entry->dls_name = arg->strspace;
2370 s_entry->dls_flags = arg->flags;
2372 strncpy(arg->strspace, dir, dirlen);
2373 arg->strspace[dirlen] = '\0';
2375 arg->strspace += dirlen + 1;
2383 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2385 struct dl_serinfo _info;
2386 struct fill_search_info_args args;
2388 args.request = RTLD_DI_SERINFOSIZE;
2389 args.serinfo = &_info;
2391 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2394 path_enumerate(ld_library_path, fill_search_info, &args);
2395 path_enumerate(obj->rpath, fill_search_info, &args);
2396 path_enumerate(gethints(), fill_search_info, &args);
2397 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2400 if (request == RTLD_DI_SERINFOSIZE) {
2401 info->dls_size = _info.dls_size;
2402 info->dls_cnt = _info.dls_cnt;
2406 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2407 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2411 args.request = RTLD_DI_SERINFO;
2412 args.serinfo = info;
2413 args.serpath = &info->dls_serpath[0];
2414 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2416 args.flags = LA_SER_LIBPATH;
2417 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2420 args.flags = LA_SER_RUNPATH;
2421 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2424 args.flags = LA_SER_CONFIG;
2425 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2428 args.flags = LA_SER_DEFAULT;
2429 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2435 rtld_dirname(const char *path, char *bname)
2439 /* Empty or NULL string gets treated as "." */
2440 if (path == NULL || *path == '\0') {
2446 /* Strip trailing slashes */
2447 endp = path + strlen(path) - 1;
2448 while (endp > path && *endp == '/')
2451 /* Find the start of the dir */
2452 while (endp > path && *endp != '/')
2455 /* Either the dir is "/" or there are no slashes */
2457 bname[0] = *endp == '/' ? '/' : '.';
2463 } while (endp > path && *endp == '/');
2466 if (endp - path + 2 > PATH_MAX)
2468 _rtld_error("Filename is too long: %s", path);
2472 strncpy(bname, path, endp - path + 1);
2473 bname[endp - path + 1] = '\0';
2478 rtld_dirname_abs(const char *path, char *base)
2480 char base_rel[PATH_MAX];
2482 if (rtld_dirname(path, base) == -1)
2486 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
2487 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
2488 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
2490 strcpy(base, base_rel);
2495 linkmap_add(Obj_Entry *obj)
2497 struct link_map *l = &obj->linkmap;
2498 struct link_map *prev;
2500 obj->linkmap.l_name = obj->path;
2501 obj->linkmap.l_addr = obj->mapbase;
2502 obj->linkmap.l_ld = obj->dynamic;
2504 /* GDB needs load offset on MIPS to use the symbols */
2505 obj->linkmap.l_offs = obj->relocbase;
2508 if (r_debug.r_map == NULL) {
2514 * Scan to the end of the list, but not past the entry for the
2515 * dynamic linker, which we want to keep at the very end.
2517 for (prev = r_debug.r_map;
2518 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2519 prev = prev->l_next)
2522 /* Link in the new entry. */
2524 l->l_next = prev->l_next;
2525 if (l->l_next != NULL)
2526 l->l_next->l_prev = l;
2531 linkmap_delete(Obj_Entry *obj)
2533 struct link_map *l = &obj->linkmap;
2535 if (l->l_prev == NULL) {
2536 if ((r_debug.r_map = l->l_next) != NULL)
2537 l->l_next->l_prev = NULL;
2541 if ((l->l_prev->l_next = l->l_next) != NULL)
2542 l->l_next->l_prev = l->l_prev;
2546 * Function for the debugger to set a breakpoint on to gain control.
2548 * The two parameters allow the debugger to easily find and determine
2549 * what the runtime loader is doing and to whom it is doing it.
2551 * When the loadhook trap is hit (r_debug_state, set at program
2552 * initialization), the arguments can be found on the stack:
2554 * +8 struct link_map *m
2555 * +4 struct r_debug *rd
2559 r_debug_state(struct r_debug* rd, struct link_map *m)
2564 * Get address of the pointer variable in the main program.
2566 static const void **
2567 get_program_var_addr(const char *name)
2569 const Obj_Entry *obj;
2572 hash = elf_hash(name);
2573 for (obj = obj_main; obj != NULL; obj = obj->next) {
2576 if ((def = symlook_obj(name, hash, obj, NULL, 0)) != NULL) {
2579 addr = (const void **)(obj->relocbase + def->st_value);
2587 * Set a pointer variable in the main program to the given value. This
2588 * is used to set key variables such as "environ" before any of the
2589 * init functions are called.
2592 set_program_var(const char *name, const void *value)
2596 if ((addr = get_program_var_addr(name)) != NULL) {
2597 dbg("\"%s\": *%p <-- %p", name, addr, value);
2603 * Given a symbol name in a referencing object, find the corresponding
2604 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2605 * no definition was found. Returns a pointer to the Obj_Entry of the
2606 * defining object via the reference parameter DEFOBJ_OUT.
2608 static const Elf_Sym *
2609 symlook_default(const char *name, unsigned long hash, const Obj_Entry *refobj,
2610 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags)
2614 const Elf_Sym *symp;
2615 const Obj_Entry *obj;
2616 const Obj_Entry *defobj;
2617 const Objlist_Entry *elm;
2620 donelist_init(&donelist);
2622 /* Look first in the referencing object if linked symbolically. */
2623 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2624 symp = symlook_obj(name, hash, refobj, ventry, flags);
2631 /* Search all objects loaded at program start up. */
2632 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2633 symp = symlook_list(name, hash, &list_main, &obj, ventry, flags,
2636 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2642 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2643 STAILQ_FOREACH(elm, &list_global, link) {
2644 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2646 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry,
2649 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2655 /* Search all dlopened DAGs containing the referencing object. */
2656 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2657 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2659 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry,
2662 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2669 * Search the dynamic linker itself, and possibly resolve the
2670 * symbol from there. This is how the application links to
2671 * dynamic linker services such as dlopen. Only the values listed
2672 * in the "exports" array can be resolved from the dynamic linker.
2674 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2675 symp = symlook_obj(name, hash, &obj_rtld, ventry, flags);
2676 if (symp != NULL && is_exported(symp)) {
2683 *defobj_out = defobj;
2687 static const Elf_Sym *
2688 symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
2689 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags,
2692 const Elf_Sym *symp;
2694 const Obj_Entry *defobj;
2695 const Objlist_Entry *elm;
2699 STAILQ_FOREACH(elm, objlist, link) {
2700 if (donelist_check(dlp, elm->obj))
2702 if ((symp = symlook_obj(name, hash, elm->obj, ventry, flags)) != NULL) {
2703 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2706 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2712 *defobj_out = defobj;
2717 * Search the symbol table of a shared object and all objects needed
2718 * by it for a symbol of the given name. Search order is
2719 * breadth-first. Returns a pointer to the symbol, or NULL if no
2720 * definition was found.
2722 static const Elf_Sym *
2723 symlook_needed(const char *name, unsigned long hash, const Needed_Entry *needed,
2724 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags,
2727 const Elf_Sym *def, *def_w;
2728 const Needed_Entry *n;
2729 const Obj_Entry *obj, *defobj, *defobj1;
2733 for (n = needed; n != NULL; n = n->next) {
2734 if ((obj = n->obj) == NULL ||
2735 donelist_check(dlp, obj) ||
2736 (def = symlook_obj(name, hash, obj, ventry, flags)) == NULL)
2739 if (ELF_ST_BIND(def->st_info) != STB_WEAK) {
2740 *defobj_out = defobj;
2745 * There we come when either symbol definition is not found in
2746 * directly needed objects, or found symbol is weak.
2748 for (n = needed; n != NULL; n = n->next) {
2749 if ((obj = n->obj) == NULL)
2751 def_w = symlook_needed(name, hash, obj->needed, &defobj1,
2752 ventry, flags, dlp);
2755 if (def == NULL || ELF_ST_BIND(def_w->st_info) != STB_WEAK) {
2759 if (ELF_ST_BIND(def_w->st_info) != STB_WEAK)
2763 *defobj_out = defobj;
2768 * Search the symbol table of a single shared object for a symbol of
2769 * the given name and version, if requested. Returns a pointer to the
2770 * symbol, or NULL if no definition was found.
2772 * The symbol's hash value is passed in for efficiency reasons; that
2773 * eliminates many recomputations of the hash value.
2776 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2777 const Ver_Entry *ventry, int flags)
2779 unsigned long symnum;
2780 const Elf_Sym *vsymp;
2784 if (obj->buckets == NULL)
2789 symnum = obj->buckets[hash % obj->nbuckets];
2791 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
2792 const Elf_Sym *symp;
2795 if (symnum >= obj->nchains)
2796 return NULL; /* Bad object */
2798 symp = obj->symtab + symnum;
2799 strp = obj->strtab + symp->st_name;
2801 switch (ELF_ST_TYPE(symp->st_info)) {
2805 if (symp->st_value == 0)
2809 if (symp->st_shndx != SHN_UNDEF)
2812 else if (((flags & SYMLOOK_IN_PLT) == 0) &&
2813 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
2820 if (name[0] != strp[0] || strcmp(name, strp) != 0)
2823 if (ventry == NULL) {
2824 if (obj->versyms != NULL) {
2825 verndx = VER_NDX(obj->versyms[symnum]);
2826 if (verndx > obj->vernum) {
2827 _rtld_error("%s: symbol %s references wrong version %d",
2828 obj->path, obj->strtab + symnum, verndx);
2832 * If we are not called from dlsym (i.e. this is a normal
2833 * relocation from unversioned binary, accept the symbol
2834 * immediately if it happens to have first version after
2835 * this shared object became versioned. Otherwise, if
2836 * symbol is versioned and not hidden, remember it. If it
2837 * is the only symbol with this name exported by the
2838 * shared object, it will be returned as a match at the
2839 * end of the function. If symbol is global (verndx < 2)
2840 * accept it unconditionally.
2842 if ((flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN)
2844 else if (verndx >= VER_NDX_GIVEN) {
2845 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
2855 if (obj->versyms == NULL) {
2856 if (object_match_name(obj, ventry->name)) {
2857 _rtld_error("%s: object %s should provide version %s for "
2858 "symbol %s", obj_rtld.path, obj->path, ventry->name,
2859 obj->strtab + symnum);
2863 verndx = VER_NDX(obj->versyms[symnum]);
2864 if (verndx > obj->vernum) {
2865 _rtld_error("%s: symbol %s references wrong version %d",
2866 obj->path, obj->strtab + symnum, verndx);
2869 if (obj->vertab[verndx].hash != ventry->hash ||
2870 strcmp(obj->vertab[verndx].name, ventry->name)) {
2872 * Version does not match. Look if this is a global symbol
2873 * and if it is not hidden. If global symbol (verndx < 2)
2874 * is available, use it. Do not return symbol if we are
2875 * called by dlvsym, because dlvsym looks for a specific
2876 * version and default one is not what dlvsym wants.
2878 if ((flags & SYMLOOK_DLSYM) ||
2879 (obj->versyms[symnum] & VER_NDX_HIDDEN) ||
2880 (verndx >= VER_NDX_GIVEN))
2887 return (vcount == 1) ? vsymp : NULL;
2891 trace_loaded_objects(Obj_Entry *obj)
2893 char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
2896 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
2899 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL)
2900 fmt1 = "\t%o => %p (%x)\n";
2902 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL)
2903 fmt2 = "\t%o (%x)\n";
2905 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL");
2907 for (; obj; obj = obj->next) {
2908 Needed_Entry *needed;
2912 if (list_containers && obj->needed != NULL)
2913 printf("%s:\n", obj->path);
2914 for (needed = obj->needed; needed; needed = needed->next) {
2915 if (needed->obj != NULL) {
2916 if (needed->obj->traced && !list_containers)
2918 needed->obj->traced = true;
2919 path = needed->obj->path;
2923 name = (char *)obj->strtab + needed->name;
2924 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2926 fmt = is_lib ? fmt1 : fmt2;
2927 while ((c = *fmt++) != '\0') {
2953 printf("%s", main_local);
2956 printf("%s", obj_main->path);
2963 printf("%d", sodp->sod_major);
2966 printf("%d", sodp->sod_minor);
2973 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2985 * Unload a dlopened object and its dependencies from memory and from
2986 * our data structures. It is assumed that the DAG rooted in the
2987 * object has already been unreferenced, and that the object has a
2988 * reference count of 0.
2991 unload_object(Obj_Entry *root)
2996 assert(root->refcount == 0);
2999 * Pass over the DAG removing unreferenced objects from
3000 * appropriate lists.
3002 unlink_object(root);
3004 /* Unmap all objects that are no longer referenced. */
3005 linkp = &obj_list->next;
3006 while ((obj = *linkp) != NULL) {
3007 if (obj->refcount == 0) {
3008 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
3010 dbg("unloading \"%s\"", obj->path);
3011 munmap(obj->mapbase, obj->mapsize);
3012 linkmap_delete(obj);
3023 unlink_object(Obj_Entry *root)
3027 if (root->refcount == 0) {
3028 /* Remove the object from the RTLD_GLOBAL list. */
3029 objlist_remove(&list_global, root);
3031 /* Remove the object from all objects' DAG lists. */
3032 STAILQ_FOREACH(elm, &root->dagmembers, link) {
3033 objlist_remove(&elm->obj->dldags, root);
3034 if (elm->obj != root)
3035 unlink_object(elm->obj);
3041 ref_dag(Obj_Entry *root)
3045 STAILQ_FOREACH(elm, &root->dagmembers, link)
3046 elm->obj->refcount++;
3050 unref_dag(Obj_Entry *root)
3054 STAILQ_FOREACH(elm, &root->dagmembers, link)
3055 elm->obj->refcount--;
3059 * Common code for MD __tls_get_addr().
3062 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
3064 Elf_Addr* dtv = *dtvp;
3067 /* Check dtv generation in case new modules have arrived */
3068 if (dtv[0] != tls_dtv_generation) {
3072 lockstate = wlock_acquire(rtld_bind_lock);
3073 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3075 if (to_copy > tls_max_index)
3076 to_copy = tls_max_index;
3077 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
3078 newdtv[0] = tls_dtv_generation;
3079 newdtv[1] = tls_max_index;
3081 wlock_release(rtld_bind_lock, lockstate);
3085 /* Dynamically allocate module TLS if necessary */
3086 if (!dtv[index + 1]) {
3087 /* Signal safe, wlock will block out signals. */
3088 lockstate = wlock_acquire(rtld_bind_lock);
3089 if (!dtv[index + 1])
3090 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
3091 wlock_release(rtld_bind_lock, lockstate);
3093 return (void*) (dtv[index + 1] + offset);
3096 /* XXX not sure what variants to use for arm. */
3098 #if defined(__ia64__) || defined(__powerpc__)
3101 * Allocate Static TLS using the Variant I method.
3104 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
3113 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
3116 assert(tcbsize >= TLS_TCB_SIZE);
3117 tcb = calloc(1, tls_static_space - TLS_TCB_SIZE + tcbsize);
3118 tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE);
3120 if (oldtcb != NULL) {
3121 memcpy(tls, oldtcb, tls_static_space);
3124 /* Adjust the DTV. */
3126 for (i = 0; i < dtv[1]; i++) {
3127 if (dtv[i+2] >= (Elf_Addr)oldtcb &&
3128 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) {
3129 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tls;
3133 dtv = calloc(tls_max_index + 2, sizeof(Elf_Addr));
3135 dtv[0] = tls_dtv_generation;
3136 dtv[1] = tls_max_index;
3138 for (obj = objs; obj; obj = obj->next) {
3139 if (obj->tlsoffset) {
3140 addr = (Elf_Addr)tls + obj->tlsoffset;
3141 memset((void*) (addr + obj->tlsinitsize),
3142 0, obj->tlssize - obj->tlsinitsize);
3144 memcpy((void*) addr, obj->tlsinit,
3146 dtv[obj->tlsindex + 1] = addr;
3155 free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
3158 Elf_Addr tlsstart, tlsend;
3161 assert(tcbsize >= TLS_TCB_SIZE);
3163 tlsstart = (Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE;
3164 tlsend = tlsstart + tls_static_space;
3166 dtv = *(Elf_Addr **)tlsstart;
3168 for (i = 0; i < dtvsize; i++) {
3169 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) {
3170 free((void*)dtv[i+2]);
3179 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \
3180 defined(__arm__) || defined(__mips__)
3183 * Allocate Static TLS using the Variant II method.
3186 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
3191 Elf_Addr *dtv, *olddtv;
3192 Elf_Addr segbase, oldsegbase, addr;
3195 size = round(tls_static_space, tcbalign);
3197 assert(tcbsize >= 2*sizeof(Elf_Addr));
3198 tls = calloc(1, size + tcbsize);
3199 dtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3201 segbase = (Elf_Addr)(tls + size);
3202 ((Elf_Addr*)segbase)[0] = segbase;
3203 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
3205 dtv[0] = tls_dtv_generation;
3206 dtv[1] = tls_max_index;
3210 * Copy the static TLS block over whole.
3212 oldsegbase = (Elf_Addr) oldtls;
3213 memcpy((void *)(segbase - tls_static_space),
3214 (const void *)(oldsegbase - tls_static_space),
3218 * If any dynamic TLS blocks have been created tls_get_addr(),
3221 olddtv = ((Elf_Addr**)oldsegbase)[1];
3222 for (i = 0; i < olddtv[1]; i++) {
3223 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) {
3224 dtv[i+2] = olddtv[i+2];
3230 * We assume that this block was the one we created with
3231 * allocate_initial_tls().
3233 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
3235 for (obj = objs; obj; obj = obj->next) {
3236 if (obj->tlsoffset) {
3237 addr = segbase - obj->tlsoffset;
3238 memset((void*) (addr + obj->tlsinitsize),
3239 0, obj->tlssize - obj->tlsinitsize);
3241 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
3242 dtv[obj->tlsindex + 1] = addr;
3247 return (void*) segbase;
3251 free_tls(void *tls, size_t tcbsize, size_t tcbalign)
3256 Elf_Addr tlsstart, tlsend;
3259 * Figure out the size of the initial TLS block so that we can
3260 * find stuff which ___tls_get_addr() allocated dynamically.
3262 size = round(tls_static_space, tcbalign);
3264 dtv = ((Elf_Addr**)tls)[1];
3266 tlsend = (Elf_Addr) tls;
3267 tlsstart = tlsend - size;
3268 for (i = 0; i < dtvsize; i++) {
3269 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] > tlsend)) {
3270 free((void*) dtv[i+2]);
3274 free((void*) tlsstart);
3281 * Allocate TLS block for module with given index.
3284 allocate_module_tls(int index)
3289 for (obj = obj_list; obj; obj = obj->next) {
3290 if (obj->tlsindex == index)
3294 _rtld_error("Can't find module with TLS index %d", index);
3298 p = malloc(obj->tlssize);
3299 memcpy(p, obj->tlsinit, obj->tlsinitsize);
3300 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
3306 allocate_tls_offset(Obj_Entry *obj)
3313 if (obj->tlssize == 0) {
3314 obj->tls_done = true;
3318 if (obj->tlsindex == 1)
3319 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
3321 off = calculate_tls_offset(tls_last_offset, tls_last_size,
3322 obj->tlssize, obj->tlsalign);
3325 * If we have already fixed the size of the static TLS block, we
3326 * must stay within that size. When allocating the static TLS, we
3327 * leave a small amount of space spare to be used for dynamically
3328 * loading modules which use static TLS.
3330 if (tls_static_space) {
3331 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
3335 tls_last_offset = obj->tlsoffset = off;
3336 tls_last_size = obj->tlssize;
3337 obj->tls_done = true;
3343 free_tls_offset(Obj_Entry *obj)
3345 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \
3346 defined(__arm__) || defined(__mips__)
3348 * If we were the last thing to allocate out of the static TLS
3349 * block, we give our space back to the 'allocator'. This is a
3350 * simplistic workaround to allow libGL.so.1 to be loaded and
3351 * unloaded multiple times. We only handle the Variant II
3352 * mechanism for now - this really needs a proper allocator.
3354 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
3355 == calculate_tls_end(tls_last_offset, tls_last_size)) {
3356 tls_last_offset -= obj->tlssize;
3363 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
3368 lockstate = wlock_acquire(rtld_bind_lock);
3369 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign);
3370 wlock_release(rtld_bind_lock, lockstate);
3375 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
3379 lockstate = wlock_acquire(rtld_bind_lock);
3380 free_tls(tcb, tcbsize, tcbalign);
3381 wlock_release(rtld_bind_lock, lockstate);
3385 object_add_name(Obj_Entry *obj, const char *name)
3391 entry = malloc(sizeof(Name_Entry) + len);
3393 if (entry != NULL) {
3394 strcpy(entry->name, name);
3395 STAILQ_INSERT_TAIL(&obj->names, entry, link);
3400 object_match_name(const Obj_Entry *obj, const char *name)
3404 STAILQ_FOREACH(entry, &obj->names, link) {
3405 if (strcmp(name, entry->name) == 0)
3412 locate_dependency(const Obj_Entry *obj, const char *name)
3414 const Objlist_Entry *entry;
3415 const Needed_Entry *needed;
3417 STAILQ_FOREACH(entry, &list_main, link) {
3418 if (object_match_name(entry->obj, name))
3422 for (needed = obj->needed; needed != NULL; needed = needed->next) {
3423 if (needed->obj == NULL)
3425 if (object_match_name(needed->obj, name))
3428 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
3434 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
3435 const Elf_Vernaux *vna)
3437 const Elf_Verdef *vd;
3438 const char *vername;
3440 vername = refobj->strtab + vna->vna_name;
3441 vd = depobj->verdef;
3443 _rtld_error("%s: version %s required by %s not defined",
3444 depobj->path, vername, refobj->path);
3448 if (vd->vd_version != VER_DEF_CURRENT) {
3449 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
3450 depobj->path, vd->vd_version);
3453 if (vna->vna_hash == vd->vd_hash) {
3454 const Elf_Verdaux *aux = (const Elf_Verdaux *)
3455 ((char *)vd + vd->vd_aux);
3456 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
3459 if (vd->vd_next == 0)
3461 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3463 if (vna->vna_flags & VER_FLG_WEAK)
3465 _rtld_error("%s: version %s required by %s not found",
3466 depobj->path, vername, refobj->path);
3471 rtld_verify_object_versions(Obj_Entry *obj)
3473 const Elf_Verneed *vn;
3474 const Elf_Verdef *vd;
3475 const Elf_Verdaux *vda;
3476 const Elf_Vernaux *vna;
3477 const Obj_Entry *depobj;
3478 int maxvernum, vernum;
3482 * Walk over defined and required version records and figure out
3483 * max index used by any of them. Do very basic sanity checking
3487 while (vn != NULL) {
3488 if (vn->vn_version != VER_NEED_CURRENT) {
3489 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
3490 obj->path, vn->vn_version);
3493 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
3495 vernum = VER_NEED_IDX(vna->vna_other);
3496 if (vernum > maxvernum)
3498 if (vna->vna_next == 0)
3500 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
3502 if (vn->vn_next == 0)
3504 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
3508 while (vd != NULL) {
3509 if (vd->vd_version != VER_DEF_CURRENT) {
3510 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
3511 obj->path, vd->vd_version);
3514 vernum = VER_DEF_IDX(vd->vd_ndx);
3515 if (vernum > maxvernum)
3517 if (vd->vd_next == 0)
3519 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3526 * Store version information in array indexable by version index.
3527 * Verify that object version requirements are satisfied along the
3530 obj->vernum = maxvernum + 1;
3531 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry));
3534 while (vd != NULL) {
3535 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
3536 vernum = VER_DEF_IDX(vd->vd_ndx);
3537 assert(vernum <= maxvernum);
3538 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
3539 obj->vertab[vernum].hash = vd->vd_hash;
3540 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
3541 obj->vertab[vernum].file = NULL;
3542 obj->vertab[vernum].flags = 0;
3544 if (vd->vd_next == 0)
3546 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3550 while (vn != NULL) {
3551 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
3552 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
3554 if (check_object_provided_version(obj, depobj, vna))
3556 vernum = VER_NEED_IDX(vna->vna_other);
3557 assert(vernum <= maxvernum);
3558 obj->vertab[vernum].hash = vna->vna_hash;
3559 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
3560 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
3561 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
3562 VER_INFO_HIDDEN : 0;
3563 if (vna->vna_next == 0)
3565 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
3567 if (vn->vn_next == 0)
3569 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
3575 rtld_verify_versions(const Objlist *objlist)
3577 Objlist_Entry *entry;
3581 STAILQ_FOREACH(entry, objlist, link) {
3583 * Skip dummy objects or objects that have their version requirements
3586 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
3588 if (rtld_verify_object_versions(entry->obj) == -1) {
3590 if (ld_tracing == NULL)
3594 if (rc == 0 || ld_tracing != NULL)
3595 rc = rtld_verify_object_versions(&obj_rtld);
3600 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
3605 vernum = VER_NDX(obj->versyms[symnum]);
3606 if (vernum >= obj->vernum) {
3607 _rtld_error("%s: symbol %s has wrong verneed value %d",
3608 obj->path, obj->strtab + symnum, vernum);
3609 } else if (obj->vertab[vernum].hash != 0) {
3610 return &obj->vertab[vernum];