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 unsetenv(LD_ "PRELOAD");
370 unsetenv(LD_ "LIBMAP");
371 unsetenv(LD_ "LIBRARY_PATH");
372 unsetenv(LD_ "LIBMAP_DISABLE");
373 unsetenv(LD_ "DEBUG");
374 unsetenv(LD_ "ELF_HINTS_PATH");
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;
479 libmap_disable = (bool)lm_init(libmap_override);
481 dbg("loading LD_PRELOAD libraries");
482 if (load_preload_objects() == -1)
484 preload_tail = obj_tail;
486 dbg("loading needed objects");
487 if (load_needed_objects(obj_main) == -1)
490 /* Make a list of all objects loaded at startup. */
491 for (obj = obj_list; obj != NULL; obj = obj->next) {
492 objlist_push_tail(&list_main, obj);
496 dbg("checking for required versions");
497 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
500 if (ld_tracing) { /* We're done */
501 trace_loaded_objects(obj_main);
505 if (getenv(LD_ "DUMP_REL_PRE") != NULL) {
506 dump_relocations(obj_main);
510 /* setup TLS for main thread */
511 dbg("initializing initial thread local storage");
512 STAILQ_FOREACH(entry, &list_main, link) {
514 * Allocate all the initial objects out of the static TLS
515 * block even if they didn't ask for it.
517 allocate_tls_offset(entry->obj);
519 allocate_initial_tls(obj_list);
521 if (relocate_objects(obj_main,
522 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld) == -1)
525 dbg("doing copy relocations");
526 if (do_copy_relocations(obj_main) == -1)
529 if (getenv(LD_ "DUMP_REL_POST") != NULL) {
530 dump_relocations(obj_main);
534 dbg("initializing key program variables");
535 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
536 set_program_var("environ", env);
538 dbg("initializing thread locks");
541 /* Make a list of init functions to call. */
542 objlist_init(&initlist);
543 initlist_add_objects(obj_list, preload_tail, &initlist);
545 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
547 lockstate = wlock_acquire(rtld_bind_lock);
548 objlist_call_init(&initlist, &lockstate);
549 objlist_clear(&initlist);
550 wlock_release(rtld_bind_lock, lockstate);
552 dbg("transferring control to program entry point = %p", obj_main->entry);
554 /* Return the exit procedure and the program entry point. */
555 *exit_proc = rtld_exit;
557 return (func_ptr_type) obj_main->entry;
561 _rtld_bind(Obj_Entry *obj, Elf_Size reloff)
565 const Obj_Entry *defobj;
570 lockstate = rlock_acquire(rtld_bind_lock);
572 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
574 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
576 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
577 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
581 target = (Elf_Addr)(defobj->relocbase + def->st_value);
583 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
584 defobj->strtab + def->st_name, basename(obj->path),
585 (void *)target, basename(defobj->path));
588 * Write the new contents for the jmpslot. Note that depending on
589 * architecture, the value which we need to return back to the
590 * lazy binding trampoline may or may not be the target
591 * address. The value returned from reloc_jmpslot() is the value
592 * that the trampoline needs.
594 target = reloc_jmpslot(where, target, defobj, obj, rel);
595 rlock_release(rtld_bind_lock, lockstate);
600 * Error reporting function. Use it like printf. If formats the message
601 * into a buffer, and sets things up so that the next call to dlerror()
602 * will return the message.
605 _rtld_error(const char *fmt, ...)
607 static char buf[512];
611 vsnprintf(buf, sizeof buf, fmt, ap);
617 * Return a dynamically-allocated copy of the current error message, if any.
622 return error_message == NULL ? NULL : xstrdup(error_message);
626 * Restore the current error message from a copy which was previously saved
627 * by errmsg_save(). The copy is freed.
630 errmsg_restore(char *saved_msg)
632 if (saved_msg == NULL)
633 error_message = NULL;
635 _rtld_error("%s", saved_msg);
641 basename(const char *name)
643 const char *p = strrchr(name, '/');
644 return p != NULL ? p + 1 : name;
647 static struct utsname uts;
650 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
660 subst_len = kw_len = 0;
664 if (subst_len == 0) {
665 subst_len = strlen(subst);
669 *res = xmalloc(PATH_MAX);
672 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
673 _rtld_error("Substitution of %s in %s cannot be performed",
675 if (may_free != NULL)
680 memcpy(res1, p, p1 - p);
682 memcpy(res1, subst, subst_len);
687 if (may_free != NULL)
690 *res = xstrdup(real);
694 if (may_free != NULL)
696 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
706 origin_subst(const char *real, const char *origin_path)
708 char *res1, *res2, *res3, *res4;
710 if (uts.sysname[0] == '\0') {
711 if (uname(&uts) != 0) {
712 _rtld_error("utsname failed: %d", errno);
716 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
717 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
718 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
719 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
727 const char *msg = dlerror();
735 * Process a shared object's DYNAMIC section, and save the important
736 * information in its Obj_Entry structure.
739 digest_dynamic(Obj_Entry *obj, int early)
742 Needed_Entry **needed_tail = &obj->needed;
743 const Elf_Dyn *dyn_rpath = NULL;
744 const Elf_Dyn *dyn_soname = NULL;
745 int plttype = DT_REL;
747 obj->bind_now = false;
748 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
749 switch (dynp->d_tag) {
752 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
756 obj->relsize = dynp->d_un.d_val;
760 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
764 obj->pltrel = (const Elf_Rel *)
765 (obj->relocbase + dynp->d_un.d_ptr);
769 obj->pltrelsize = dynp->d_un.d_val;
773 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
777 obj->relasize = dynp->d_un.d_val;
781 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
785 plttype = dynp->d_un.d_val;
786 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
790 obj->symtab = (const Elf_Sym *)
791 (obj->relocbase + dynp->d_un.d_ptr);
795 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
799 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
803 obj->strsize = dynp->d_un.d_val;
807 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
812 obj->verneednum = dynp->d_un.d_val;
816 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
821 obj->verdefnum = dynp->d_un.d_val;
825 obj->versyms = (const Elf_Versym *)(obj->relocbase +
831 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
832 (obj->relocbase + dynp->d_un.d_ptr);
833 obj->nbuckets = hashtab[0];
834 obj->nchains = hashtab[1];
835 obj->buckets = hashtab + 2;
836 obj->chains = obj->buckets + obj->nbuckets;
842 Needed_Entry *nep = NEW(Needed_Entry);
843 nep->name = dynp->d_un.d_val;
848 needed_tail = &nep->next;
853 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
861 obj->symbolic = true;
865 case DT_RUNPATH: /* XXX: process separately */
867 * We have to wait until later to process this, because we
868 * might not have gotten the address of the string table yet.
878 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
882 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
886 * Don't process DT_DEBUG on MIPS as the dynamic section
887 * is mapped read-only. DT_MIPS_RLD_MAP is used instead.
892 /* XXX - not implemented yet */
894 dbg("Filling in DT_DEBUG entry");
895 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
900 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
901 obj->z_origin = true;
902 if (dynp->d_un.d_val & DF_SYMBOLIC)
903 obj->symbolic = true;
904 if (dynp->d_un.d_val & DF_TEXTREL)
906 if (dynp->d_un.d_val & DF_BIND_NOW)
907 obj->bind_now = true;
908 if (dynp->d_un.d_val & DF_STATIC_TLS)
912 case DT_MIPS_LOCAL_GOTNO:
913 obj->local_gotno = dynp->d_un.d_val;
916 case DT_MIPS_SYMTABNO:
917 obj->symtabno = dynp->d_un.d_val;
921 obj->gotsym = dynp->d_un.d_val;
924 case DT_MIPS_RLD_MAP:
927 dbg("Filling in DT_DEBUG entry");
928 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
934 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
935 obj->z_origin = true;
936 if (dynp->d_un.d_val & DF_1_GLOBAL)
938 if (dynp->d_un.d_val & DF_1_BIND_NOW)
939 obj->bind_now = true;
940 if (dynp->d_un.d_val & DF_1_NODELETE)
941 obj->z_nodelete = true;
946 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
955 if (plttype == DT_RELA) {
956 obj->pltrela = (const Elf_Rela *) obj->pltrel;
958 obj->pltrelasize = obj->pltrelsize;
962 if (obj->z_origin && obj->origin_path == NULL) {
963 obj->origin_path = xmalloc(PATH_MAX);
964 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
968 if (dyn_rpath != NULL) {
969 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
971 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
974 if (dyn_soname != NULL)
975 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
979 * Process a shared object's program header. This is used only for the
980 * main program, when the kernel has already loaded the main program
981 * into memory before calling the dynamic linker. It creates and
982 * returns an Obj_Entry structure.
985 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
988 const Elf_Phdr *phlimit = phdr + phnum;
993 for (ph = phdr; ph < phlimit; ph++) {
994 switch (ph->p_type) {
997 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
998 _rtld_error("%s: invalid PT_PHDR", path);
1001 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
1002 obj->phsize = ph->p_memsz;
1006 obj->interp = (const char *) ph->p_vaddr;
1010 if (nsegs == 0) { /* First load segment */
1011 obj->vaddrbase = trunc_page(ph->p_vaddr);
1012 obj->mapbase = (caddr_t) obj->vaddrbase;
1013 obj->relocbase = obj->mapbase - obj->vaddrbase;
1014 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1016 } else { /* Last load segment */
1017 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1024 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
1029 obj->tlssize = ph->p_memsz;
1030 obj->tlsalign = ph->p_align;
1031 obj->tlsinitsize = ph->p_filesz;
1032 obj->tlsinit = (void*) ph->p_vaddr;
1037 _rtld_error("%s: too few PT_LOAD segments", path);
1046 dlcheck(void *handle)
1050 for (obj = obj_list; obj != NULL; obj = obj->next)
1051 if (obj == (Obj_Entry *) handle)
1054 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1055 _rtld_error("Invalid shared object handle %p", handle);
1062 * If the given object is already in the donelist, return true. Otherwise
1063 * add the object to the list and return false.
1066 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1070 for (i = 0; i < dlp->num_used; i++)
1071 if (dlp->objs[i] == obj)
1074 * Our donelist allocation should always be sufficient. But if
1075 * our threads locking isn't working properly, more shared objects
1076 * could have been loaded since we allocated the list. That should
1077 * never happen, but we'll handle it properly just in case it does.
1079 if (dlp->num_used < dlp->num_alloc)
1080 dlp->objs[dlp->num_used++] = obj;
1085 * Hash function for symbol table lookup. Don't even think about changing
1086 * this. It is specified by the System V ABI.
1089 elf_hash(const char *name)
1091 const unsigned char *p = (const unsigned char *) name;
1092 unsigned long h = 0;
1095 while (*p != '\0') {
1096 h = (h << 4) + *p++;
1097 if ((g = h & 0xf0000000) != 0)
1105 * Find the library with the given name, and return its full pathname.
1106 * The returned string is dynamically allocated. Generates an error
1107 * message and returns NULL if the library cannot be found.
1109 * If the second argument is non-NULL, then it refers to an already-
1110 * loaded shared object, whose library search path will be searched.
1112 * The search order is:
1114 * rpath in the referencing file
1119 find_library(const char *xname, const Obj_Entry *refobj)
1124 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1125 if (xname[0] != '/' && !trust) {
1126 _rtld_error("Absolute pathname required for shared object \"%s\"",
1130 if (refobj != NULL && refobj->z_origin)
1131 return origin_subst(xname, refobj->origin_path);
1133 return xstrdup(xname);
1136 if (libmap_disable || (refobj == NULL) ||
1137 (name = lm_find(refobj->path, xname)) == NULL)
1138 name = (char *)xname;
1140 dbg(" Searching for \"%s\"", name);
1142 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1144 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1145 (pathname = search_library_path(name, gethints())) != NULL ||
1146 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1149 if(refobj != NULL && refobj->path != NULL) {
1150 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1151 name, basename(refobj->path));
1153 _rtld_error("Shared object \"%s\" not found", name);
1159 * Given a symbol number in a referencing object, find the corresponding
1160 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1161 * no definition was found. Returns a pointer to the Obj_Entry of the
1162 * defining object via the reference parameter DEFOBJ_OUT.
1165 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1166 const Obj_Entry **defobj_out, int flags, SymCache *cache)
1170 const Obj_Entry *defobj;
1171 const Ver_Entry *ventry;
1176 * If we have already found this symbol, get the information from
1179 if (symnum >= refobj->nchains)
1180 return NULL; /* Bad object */
1181 if (cache != NULL && cache[symnum].sym != NULL) {
1182 *defobj_out = cache[symnum].obj;
1183 return cache[symnum].sym;
1186 ref = refobj->symtab + symnum;
1187 name = refobj->strtab + ref->st_name;
1191 * We don't have to do a full scale lookup if the symbol is local.
1192 * We know it will bind to the instance in this load module; to
1193 * which we already have a pointer (ie ref). By not doing a lookup,
1194 * we not only improve performance, but it also avoids unresolvable
1195 * symbols when local symbols are not in the hash table. This has
1196 * been seen with the ia64 toolchain.
1198 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1199 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1200 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1203 ventry = fetch_ventry(refobj, symnum);
1204 hash = elf_hash(name);
1205 def = symlook_default(name, hash, refobj, &defobj, ventry, flags);
1212 * If we found no definition and the reference is weak, treat the
1213 * symbol as having the value zero.
1215 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1221 *defobj_out = defobj;
1222 /* Record the information in the cache to avoid subsequent lookups. */
1223 if (cache != NULL) {
1224 cache[symnum].sym = def;
1225 cache[symnum].obj = defobj;
1228 if (refobj != &obj_rtld)
1229 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1235 * Return the search path from the ldconfig hints file, reading it if
1236 * necessary. Returns NULL if there are problems with the hints file,
1237 * or if the search path there is empty.
1244 if (hints == NULL) {
1246 struct elfhints_hdr hdr;
1249 /* Keep from trying again in case the hints file is bad. */
1252 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1254 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1255 hdr.magic != ELFHINTS_MAGIC ||
1260 p = xmalloc(hdr.dirlistlen + 1);
1261 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1262 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1270 return hints[0] != '\0' ? hints : NULL;
1274 init_dag(Obj_Entry *root)
1278 donelist_init(&donelist);
1279 init_dag1(root, root, &donelist);
1283 init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
1285 const Needed_Entry *needed;
1287 if (donelist_check(dlp, obj))
1291 objlist_push_tail(&obj->dldags, root);
1292 objlist_push_tail(&root->dagmembers, obj);
1293 for (needed = obj->needed; needed != NULL; needed = needed->next)
1294 if (needed->obj != NULL)
1295 init_dag1(root, needed->obj, dlp);
1299 * Initialize the dynamic linker. The argument is the address at which
1300 * the dynamic linker has been mapped into memory. The primary task of
1301 * this function is to relocate the dynamic linker.
1304 init_rtld(caddr_t mapbase)
1306 Obj_Entry objtmp; /* Temporary rtld object */
1309 * Conjure up an Obj_Entry structure for the dynamic linker.
1311 * The "path" member can't be initialized yet because string constants
1312 * cannot yet be accessed. Below we will set it correctly.
1314 memset(&objtmp, 0, sizeof(objtmp));
1317 objtmp.mapbase = mapbase;
1319 objtmp.relocbase = mapbase;
1321 if (RTLD_IS_DYNAMIC()) {
1322 objtmp.dynamic = rtld_dynamic(&objtmp);
1323 digest_dynamic(&objtmp, 1);
1324 assert(objtmp.needed == NULL);
1325 #if !defined(__mips__)
1326 /* MIPS and SH{3,5} have a bogus DT_TEXTREL. */
1327 assert(!objtmp.textrel);
1331 * Temporarily put the dynamic linker entry into the object list, so
1332 * that symbols can be found.
1335 relocate_objects(&objtmp, true, &objtmp);
1338 /* Initialize the object list. */
1339 obj_tail = &obj_list;
1341 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1342 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1344 /* Replace the path with a dynamically allocated copy. */
1345 obj_rtld.path = xstrdup(PATH_RTLD);
1347 r_debug.r_brk = r_debug_state;
1348 r_debug.r_state = RT_CONSISTENT;
1352 * Add the init functions from a needed object list (and its recursive
1353 * needed objects) to "list". This is not used directly; it is a helper
1354 * function for initlist_add_objects(). The write lock must be held
1355 * when this function is called.
1358 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1360 /* Recursively process the successor needed objects. */
1361 if (needed->next != NULL)
1362 initlist_add_neededs(needed->next, list);
1364 /* Process the current needed object. */
1365 if (needed->obj != NULL)
1366 initlist_add_objects(needed->obj, &needed->obj->next, list);
1370 * Scan all of the DAGs rooted in the range of objects from "obj" to
1371 * "tail" and add their init functions to "list". This recurses over
1372 * the DAGs and ensure the proper init ordering such that each object's
1373 * needed libraries are initialized before the object itself. At the
1374 * same time, this function adds the objects to the global finalization
1375 * list "list_fini" in the opposite order. The write lock must be
1376 * held when this function is called.
1379 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1381 if (obj->init_scanned || obj->init_done)
1383 obj->init_scanned = true;
1385 /* Recursively process the successor objects. */
1386 if (&obj->next != tail)
1387 initlist_add_objects(obj->next, tail, list);
1389 /* Recursively process the needed objects. */
1390 if (obj->needed != NULL)
1391 initlist_add_neededs(obj->needed, list);
1393 /* Add the object to the init list. */
1394 if (obj->init != (Elf_Addr)NULL)
1395 objlist_push_tail(list, obj);
1397 /* Add the object to the global fini list in the reverse order. */
1398 if (obj->fini != (Elf_Addr)NULL && !obj->on_fini_list) {
1399 objlist_push_head(&list_fini, obj);
1400 obj->on_fini_list = true;
1405 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1409 is_exported(const Elf_Sym *def)
1412 const func_ptr_type *p;
1414 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1415 for (p = exports; *p != NULL; p++)
1416 if (FPTR_TARGET(*p) == value)
1422 * Given a shared object, traverse its list of needed objects, and load
1423 * each of them. Returns 0 on success. Generates an error message and
1424 * returns -1 on failure.
1427 load_needed_objects(Obj_Entry *first)
1429 Obj_Entry *obj, *obj1;
1431 for (obj = first; obj != NULL; obj = obj->next) {
1432 Needed_Entry *needed;
1434 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1435 obj1 = needed->obj = load_object(obj->strtab + needed->name, obj,
1437 if (obj1 == NULL && !ld_tracing)
1439 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1440 dbg("obj %s nodelete", obj1->path);
1443 obj1->ref_nodel = true;
1452 load_preload_objects(void)
1454 char *p = ld_preload;
1455 static const char delim[] = " \t:;";
1460 p += strspn(p, delim);
1461 while (*p != '\0') {
1462 size_t len = strcspn(p, delim);
1467 if (load_object(p, NULL, false) == NULL)
1468 return -1; /* XXX - cleanup */
1471 p += strspn(p, delim);
1473 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
1478 * Load a shared object into memory, if it is not already loaded.
1480 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1484 load_object(const char *name, const Obj_Entry *refobj, int noload)
1491 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1492 if (object_match_name(obj, name))
1495 path = find_library(name, refobj);
1500 * If we didn't find a match by pathname, open the file and check
1501 * again by device and inode. This avoids false mismatches caused
1502 * by multiple links or ".." in pathnames.
1504 * To avoid a race, we open the file and use fstat() rather than
1507 if ((fd = open(path, O_RDONLY)) == -1) {
1508 _rtld_error("Cannot open \"%s\"", path);
1512 if (fstat(fd, &sb) == -1) {
1513 _rtld_error("Cannot fstat \"%s\"", path);
1518 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1519 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
1525 object_add_name(obj, name);
1533 /* First use of this object, so we must map it in */
1534 obj = do_load_object(fd, name, path, &sb);
1543 do_load_object(int fd, const char *name, char *path, struct stat *sbp)
1549 * but first, make sure that environment variables haven't been
1550 * used to circumvent the noexec flag on a filesystem.
1552 if (dangerous_ld_env) {
1553 if (fstatfs(fd, &fs) != 0) {
1554 _rtld_error("Cannot fstatfs \"%s\"", path);
1557 if (fs.f_flags & MNT_NOEXEC) {
1558 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
1562 dbg("loading \"%s\"", path);
1563 obj = map_object(fd, path, sbp);
1567 object_add_name(obj, name);
1569 digest_dynamic(obj, 0);
1572 obj_tail = &obj->next;
1575 linkmap_add(obj); /* for GDB & dlinfo() */
1577 dbg(" %p .. %p: %s", obj->mapbase,
1578 obj->mapbase + obj->mapsize - 1, obj->path);
1580 dbg(" WARNING: %s has impure text", obj->path);
1581 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
1588 obj_from_addr(const void *addr)
1592 for (obj = obj_list; obj != NULL; obj = obj->next) {
1593 if (addr < (void *) obj->mapbase)
1595 if (addr < (void *) (obj->mapbase + obj->mapsize))
1602 * Call the finalization functions for each of the objects in "list"
1603 * which are unreferenced. All of the objects are expected to have
1604 * non-NULL fini functions.
1607 objlist_call_fini(Objlist *list, bool force, int *lockstate)
1609 Objlist_Entry *elm, *elm_tmp;
1613 * Preserve the current error message since a fini function might
1614 * call into the dynamic linker and overwrite it.
1616 saved_msg = errmsg_save();
1617 STAILQ_FOREACH_SAFE(elm, list, link, elm_tmp) {
1618 if (elm->obj->refcount == 0 || force) {
1619 dbg("calling fini function for %s at %p", elm->obj->path,
1620 (void *)elm->obj->fini);
1621 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini, 0, 0,
1623 /* Remove object from fini list to prevent recursive invocation. */
1624 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1625 wlock_release(rtld_bind_lock, *lockstate);
1626 call_initfini_pointer(elm->obj, elm->obj->fini);
1627 *lockstate = wlock_acquire(rtld_bind_lock);
1628 /* No need to free anything if process is going down. */
1633 errmsg_restore(saved_msg);
1637 * Call the initialization functions for each of the objects in
1638 * "list". All of the objects are expected to have non-NULL init
1642 objlist_call_init(Objlist *list, int *lockstate)
1649 * Clean init_scanned flag so that objects can be rechecked and
1650 * possibly initialized earlier if any of vectors called below
1651 * cause the change by using dlopen.
1653 for (obj = obj_list; obj != NULL; obj = obj->next)
1654 obj->init_scanned = false;
1657 * Preserve the current error message since an init function might
1658 * call into the dynamic linker and overwrite it.
1660 saved_msg = errmsg_save();
1661 STAILQ_FOREACH(elm, list, link) {
1662 if (elm->obj->init_done) /* Initialized early. */
1664 dbg("calling init function for %s at %p", elm->obj->path,
1665 (void *)elm->obj->init);
1666 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init, 0, 0,
1669 * Race: other thread might try to use this object before current
1670 * one completes the initilization. Not much can be done here
1671 * without better locking.
1673 elm->obj->init_done = true;
1674 wlock_release(rtld_bind_lock, *lockstate);
1675 call_initfini_pointer(elm->obj, elm->obj->init);
1676 *lockstate = wlock_acquire(rtld_bind_lock);
1678 errmsg_restore(saved_msg);
1682 objlist_clear(Objlist *list)
1686 while (!STAILQ_EMPTY(list)) {
1687 elm = STAILQ_FIRST(list);
1688 STAILQ_REMOVE_HEAD(list, link);
1693 static Objlist_Entry *
1694 objlist_find(Objlist *list, const Obj_Entry *obj)
1698 STAILQ_FOREACH(elm, list, link)
1699 if (elm->obj == obj)
1705 objlist_init(Objlist *list)
1711 objlist_push_head(Objlist *list, Obj_Entry *obj)
1715 elm = NEW(Objlist_Entry);
1717 STAILQ_INSERT_HEAD(list, elm, link);
1721 objlist_push_tail(Objlist *list, Obj_Entry *obj)
1725 elm = NEW(Objlist_Entry);
1727 STAILQ_INSERT_TAIL(list, elm, link);
1731 objlist_remove(Objlist *list, Obj_Entry *obj)
1735 if ((elm = objlist_find(list, obj)) != NULL) {
1736 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1742 * Relocate newly-loaded shared objects. The argument is a pointer to
1743 * the Obj_Entry for the first such object. All objects from the first
1744 * to the end of the list of objects are relocated. Returns 0 on success,
1748 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj)
1752 for (obj = first; obj != NULL; obj = obj->next) {
1754 dbg("relocating \"%s\"", obj->path);
1755 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1756 obj->symtab == NULL || obj->strtab == NULL) {
1757 _rtld_error("%s: Shared object has no run-time symbol table",
1763 /* There are relocations to the write-protected text segment. */
1764 if (mprotect(obj->mapbase, obj->textsize,
1765 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1766 _rtld_error("%s: Cannot write-enable text segment: %s",
1767 obj->path, strerror(errno));
1772 /* Process the non-PLT relocations. */
1773 if (reloc_non_plt(obj, rtldobj))
1776 if (obj->textrel) { /* Re-protected the text segment. */
1777 if (mprotect(obj->mapbase, obj->textsize,
1778 PROT_READ|PROT_EXEC) == -1) {
1779 _rtld_error("%s: Cannot write-protect text segment: %s",
1780 obj->path, strerror(errno));
1785 /* Process the PLT relocations. */
1786 if (reloc_plt(obj) == -1)
1788 /* Relocate the jump slots if we are doing immediate binding. */
1789 if (obj->bind_now || bind_now)
1790 if (reloc_jmpslots(obj) == -1)
1795 * Set up the magic number and version in the Obj_Entry. These
1796 * were checked in the crt1.o from the original ElfKit, so we
1797 * set them for backward compatibility.
1799 obj->magic = RTLD_MAGIC;
1800 obj->version = RTLD_VERSION;
1802 /* Set the special PLT or GOT entries. */
1810 * Cleanup procedure. It will be called (by the atexit mechanism) just
1811 * before the process exits.
1818 lockstate = wlock_acquire(rtld_bind_lock);
1820 objlist_call_fini(&list_fini, true, &lockstate);
1821 /* No need to remove the items from the list, since we are exiting. */
1822 if (!libmap_disable)
1824 wlock_release(rtld_bind_lock, lockstate);
1828 path_enumerate(const char *path, path_enum_proc callback, void *arg)
1836 path += strspn(path, ":;");
1837 while (*path != '\0') {
1841 len = strcspn(path, ":;");
1843 trans = lm_findn(NULL, path, len);
1845 res = callback(trans, strlen(trans), arg);
1848 res = callback(path, len, arg);
1854 path += strspn(path, ":;");
1860 struct try_library_args {
1868 try_library_path(const char *dir, size_t dirlen, void *param)
1870 struct try_library_args *arg;
1873 if (*dir == '/' || trust) {
1876 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1879 pathname = arg->buffer;
1880 strncpy(pathname, dir, dirlen);
1881 pathname[dirlen] = '/';
1882 strcpy(pathname + dirlen + 1, arg->name);
1884 dbg(" Trying \"%s\"", pathname);
1885 if (access(pathname, F_OK) == 0) { /* We found it */
1886 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1887 strcpy(pathname, arg->buffer);
1895 search_library_path(const char *name, const char *path)
1898 struct try_library_args arg;
1904 arg.namelen = strlen(name);
1905 arg.buffer = xmalloc(PATH_MAX);
1906 arg.buflen = PATH_MAX;
1908 p = path_enumerate(path, try_library_path, &arg);
1916 dlclose(void *handle)
1921 lockstate = wlock_acquire(rtld_bind_lock);
1922 root = dlcheck(handle);
1924 wlock_release(rtld_bind_lock, lockstate);
1927 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
1930 /* Unreference the object and its dependencies. */
1931 root->dl_refcount--;
1935 if (root->refcount == 0) {
1937 * The object is no longer referenced, so we must unload it.
1938 * First, call the fini functions.
1940 objlist_call_fini(&list_fini, false, &lockstate);
1942 /* Finish cleaning up the newly-unreferenced objects. */
1943 GDB_STATE(RT_DELETE,&root->linkmap);
1944 unload_object(root);
1945 GDB_STATE(RT_CONSISTENT,NULL);
1947 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
1948 wlock_release(rtld_bind_lock, lockstate);
1955 char *msg = error_message;
1956 error_message = NULL;
1961 * This function is deprecated and has no effect.
1964 dllockinit(void *context,
1965 void *(*lock_create)(void *context),
1966 void (*rlock_acquire)(void *lock),
1967 void (*wlock_acquire)(void *lock),
1968 void (*lock_release)(void *lock),
1969 void (*lock_destroy)(void *lock),
1970 void (*context_destroy)(void *context))
1972 static void *cur_context;
1973 static void (*cur_context_destroy)(void *);
1975 /* Just destroy the context from the previous call, if necessary. */
1976 if (cur_context_destroy != NULL)
1977 cur_context_destroy(cur_context);
1978 cur_context = context;
1979 cur_context_destroy = context_destroy;
1983 dlopen(const char *name, int mode)
1985 Obj_Entry **old_obj_tail;
1988 int result, lockstate, nodelete, noload;
1990 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
1991 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1992 if (ld_tracing != NULL)
1993 environ = (char **)*get_program_var_addr("environ");
1994 nodelete = mode & RTLD_NODELETE;
1995 noload = mode & RTLD_NOLOAD;
1997 objlist_init(&initlist);
1999 lockstate = wlock_acquire(rtld_bind_lock);
2000 GDB_STATE(RT_ADD,NULL);
2002 old_obj_tail = obj_tail;
2008 obj = load_object(name, obj_main, noload);
2013 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2014 objlist_push_tail(&list_global, obj);
2015 mode &= RTLD_MODEMASK;
2016 if (*old_obj_tail != NULL) { /* We loaded something new. */
2017 assert(*old_obj_tail == obj);
2018 result = load_needed_objects(obj);
2021 result = rtld_verify_versions(&obj->dagmembers);
2022 if (result != -1 && ld_tracing)
2025 (relocate_objects(obj, mode == RTLD_NOW, &obj_rtld)) == -1) {
2028 if (obj->refcount == 0)
2032 /* Make list of init functions to call. */
2033 initlist_add_objects(obj, &obj->next, &initlist);
2037 /* Bump the reference counts for objects on this DAG. */
2043 if (obj != NULL && (nodelete || obj->z_nodelete) && !obj->ref_nodel) {
2044 dbg("obj %s nodelete", obj->path);
2046 obj->z_nodelete = obj->ref_nodel = true;
2050 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2052 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2054 /* Call the init functions. */
2055 objlist_call_init(&initlist, &lockstate);
2056 objlist_clear(&initlist);
2057 wlock_release(rtld_bind_lock, lockstate);
2060 trace_loaded_objects(obj);
2061 wlock_release(rtld_bind_lock, lockstate);
2066 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2070 const Obj_Entry *obj, *defobj;
2071 const Elf_Sym *def, *symp;
2075 hash = elf_hash(name);
2078 flags |= SYMLOOK_IN_PLT;
2080 lockstate = rlock_acquire(rtld_bind_lock);
2081 if (handle == NULL || handle == RTLD_NEXT ||
2082 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2084 if ((obj = obj_from_addr(retaddr)) == NULL) {
2085 _rtld_error("Cannot determine caller's shared object");
2086 rlock_release(rtld_bind_lock, lockstate);
2089 if (handle == NULL) { /* Just the caller's shared object. */
2090 def = symlook_obj(name, hash, obj, ve, flags);
2092 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2093 handle == RTLD_SELF) { /* ... caller included */
2094 if (handle == RTLD_NEXT)
2096 for (; obj != NULL; obj = obj->next) {
2097 if ((symp = symlook_obj(name, hash, obj, ve, flags)) != NULL) {
2098 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2101 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2107 * Search the dynamic linker itself, and possibly resolve the
2108 * symbol from there. This is how the application links to
2109 * dynamic linker services such as dlopen. Only the values listed
2110 * in the "exports" array can be resolved from the dynamic linker.
2112 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2113 symp = symlook_obj(name, hash, &obj_rtld, ve, flags);
2114 if (symp != NULL && is_exported(symp)) {
2120 assert(handle == RTLD_DEFAULT);
2121 def = symlook_default(name, hash, obj, &defobj, ve, flags);
2124 if ((obj = dlcheck(handle)) == NULL) {
2125 rlock_release(rtld_bind_lock, lockstate);
2129 donelist_init(&donelist);
2130 if (obj->mainprog) {
2131 /* Search main program and all libraries loaded by it. */
2132 def = symlook_list(name, hash, &list_main, &defobj, ve, flags,
2136 * We do not distinguish between 'main' object and global scope.
2137 * If symbol is not defined by objects loaded at startup, continue
2138 * search among dynamically loaded objects with RTLD_GLOBAL
2142 def = symlook_list(name, hash, &list_global, &defobj, ve,
2147 /* Search the whole DAG rooted at the given object. */
2149 fake.obj = (Obj_Entry *)obj;
2151 def = symlook_needed(name, hash, &fake, &defobj, ve, flags,
2157 rlock_release(rtld_bind_lock, lockstate);
2160 * The value required by the caller is derived from the value
2161 * of the symbol. For the ia64 architecture, we need to
2162 * construct a function descriptor which the caller can use to
2163 * call the function with the right 'gp' value. For other
2164 * architectures and for non-functions, the value is simply
2165 * the relocated value of the symbol.
2167 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
2168 return make_function_pointer(def, defobj);
2170 return defobj->relocbase + def->st_value;
2173 _rtld_error("Undefined symbol \"%s\"", name);
2174 rlock_release(rtld_bind_lock, lockstate);
2179 dlsym(void *handle, const char *name)
2181 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
2186 dlfunc(void *handle, const char *name)
2193 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
2199 dlvsym(void *handle, const char *name, const char *version)
2203 ventry.name = version;
2205 ventry.hash = elf_hash(version);
2207 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
2212 dladdr(const void *addr, Dl_info *info)
2214 const Obj_Entry *obj;
2217 unsigned long symoffset;
2220 lockstate = rlock_acquire(rtld_bind_lock);
2221 obj = obj_from_addr(addr);
2223 _rtld_error("No shared object contains address");
2224 rlock_release(rtld_bind_lock, lockstate);
2227 info->dli_fname = obj->path;
2228 info->dli_fbase = obj->mapbase;
2229 info->dli_saddr = (void *)0;
2230 info->dli_sname = NULL;
2233 * Walk the symbol list looking for the symbol whose address is
2234 * closest to the address sent in.
2236 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
2237 def = obj->symtab + symoffset;
2240 * For skip the symbol if st_shndx is either SHN_UNDEF or
2243 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
2247 * If the symbol is greater than the specified address, or if it
2248 * is further away from addr than the current nearest symbol,
2251 symbol_addr = obj->relocbase + def->st_value;
2252 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
2255 /* Update our idea of the nearest symbol. */
2256 info->dli_sname = obj->strtab + def->st_name;
2257 info->dli_saddr = symbol_addr;
2260 if (info->dli_saddr == addr)
2263 rlock_release(rtld_bind_lock, lockstate);
2268 dlinfo(void *handle, int request, void *p)
2270 const Obj_Entry *obj;
2271 int error, lockstate;
2273 lockstate = rlock_acquire(rtld_bind_lock);
2275 if (handle == NULL || handle == RTLD_SELF) {
2278 retaddr = __builtin_return_address(0); /* __GNUC__ only */
2279 if ((obj = obj_from_addr(retaddr)) == NULL)
2280 _rtld_error("Cannot determine caller's shared object");
2282 obj = dlcheck(handle);
2285 rlock_release(rtld_bind_lock, lockstate);
2291 case RTLD_DI_LINKMAP:
2292 *((struct link_map const **)p) = &obj->linkmap;
2294 case RTLD_DI_ORIGIN:
2295 error = rtld_dirname(obj->path, p);
2298 case RTLD_DI_SERINFOSIZE:
2299 case RTLD_DI_SERINFO:
2300 error = do_search_info(obj, request, (struct dl_serinfo *)p);
2304 _rtld_error("Invalid request %d passed to dlinfo()", request);
2308 rlock_release(rtld_bind_lock, lockstate);
2314 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
2316 struct dl_phdr_info phdr_info;
2317 const Obj_Entry *obj;
2318 int error, bind_lockstate, phdr_lockstate;
2320 phdr_lockstate = wlock_acquire(rtld_phdr_lock);
2321 bind_lockstate = rlock_acquire(rtld_bind_lock);
2325 for (obj = obj_list; obj != NULL; obj = obj->next) {
2326 phdr_info.dlpi_addr = (Elf_Addr)obj->relocbase;
2327 phdr_info.dlpi_name = STAILQ_FIRST(&obj->names) ?
2328 STAILQ_FIRST(&obj->names)->name : obj->path;
2329 phdr_info.dlpi_phdr = obj->phdr;
2330 phdr_info.dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
2331 phdr_info.dlpi_tls_modid = obj->tlsindex;
2332 phdr_info.dlpi_tls_data = obj->tlsinit;
2333 phdr_info.dlpi_adds = obj_loads;
2334 phdr_info.dlpi_subs = obj_loads - obj_count;
2336 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
2340 rlock_release(rtld_bind_lock, bind_lockstate);
2341 wlock_release(rtld_phdr_lock, phdr_lockstate);
2346 struct fill_search_info_args {
2349 Dl_serinfo *serinfo;
2350 Dl_serpath *serpath;
2355 fill_search_info(const char *dir, size_t dirlen, void *param)
2357 struct fill_search_info_args *arg;
2361 if (arg->request == RTLD_DI_SERINFOSIZE) {
2362 arg->serinfo->dls_cnt ++;
2363 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1;
2365 struct dl_serpath *s_entry;
2367 s_entry = arg->serpath;
2368 s_entry->dls_name = arg->strspace;
2369 s_entry->dls_flags = arg->flags;
2371 strncpy(arg->strspace, dir, dirlen);
2372 arg->strspace[dirlen] = '\0';
2374 arg->strspace += dirlen + 1;
2382 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2384 struct dl_serinfo _info;
2385 struct fill_search_info_args args;
2387 args.request = RTLD_DI_SERINFOSIZE;
2388 args.serinfo = &_info;
2390 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2393 path_enumerate(ld_library_path, fill_search_info, &args);
2394 path_enumerate(obj->rpath, fill_search_info, &args);
2395 path_enumerate(gethints(), fill_search_info, &args);
2396 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2399 if (request == RTLD_DI_SERINFOSIZE) {
2400 info->dls_size = _info.dls_size;
2401 info->dls_cnt = _info.dls_cnt;
2405 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2406 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2410 args.request = RTLD_DI_SERINFO;
2411 args.serinfo = info;
2412 args.serpath = &info->dls_serpath[0];
2413 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2415 args.flags = LA_SER_LIBPATH;
2416 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
2419 args.flags = LA_SER_RUNPATH;
2420 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
2423 args.flags = LA_SER_CONFIG;
2424 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
2427 args.flags = LA_SER_DEFAULT;
2428 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
2434 rtld_dirname(const char *path, char *bname)
2438 /* Empty or NULL string gets treated as "." */
2439 if (path == NULL || *path == '\0') {
2445 /* Strip trailing slashes */
2446 endp = path + strlen(path) - 1;
2447 while (endp > path && *endp == '/')
2450 /* Find the start of the dir */
2451 while (endp > path && *endp != '/')
2454 /* Either the dir is "/" or there are no slashes */
2456 bname[0] = *endp == '/' ? '/' : '.';
2462 } while (endp > path && *endp == '/');
2465 if (endp - path + 2 > PATH_MAX)
2467 _rtld_error("Filename is too long: %s", path);
2471 strncpy(bname, path, endp - path + 1);
2472 bname[endp - path + 1] = '\0';
2477 rtld_dirname_abs(const char *path, char *base)
2479 char base_rel[PATH_MAX];
2481 if (rtld_dirname(path, base) == -1)
2485 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
2486 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
2487 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
2489 strcpy(base, base_rel);
2494 linkmap_add(Obj_Entry *obj)
2496 struct link_map *l = &obj->linkmap;
2497 struct link_map *prev;
2499 obj->linkmap.l_name = obj->path;
2500 obj->linkmap.l_addr = obj->mapbase;
2501 obj->linkmap.l_ld = obj->dynamic;
2503 /* GDB needs load offset on MIPS to use the symbols */
2504 obj->linkmap.l_offs = obj->relocbase;
2507 if (r_debug.r_map == NULL) {
2513 * Scan to the end of the list, but not past the entry for the
2514 * dynamic linker, which we want to keep at the very end.
2516 for (prev = r_debug.r_map;
2517 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2518 prev = prev->l_next)
2521 /* Link in the new entry. */
2523 l->l_next = prev->l_next;
2524 if (l->l_next != NULL)
2525 l->l_next->l_prev = l;
2530 linkmap_delete(Obj_Entry *obj)
2532 struct link_map *l = &obj->linkmap;
2534 if (l->l_prev == NULL) {
2535 if ((r_debug.r_map = l->l_next) != NULL)
2536 l->l_next->l_prev = NULL;
2540 if ((l->l_prev->l_next = l->l_next) != NULL)
2541 l->l_next->l_prev = l->l_prev;
2545 * Function for the debugger to set a breakpoint on to gain control.
2547 * The two parameters allow the debugger to easily find and determine
2548 * what the runtime loader is doing and to whom it is doing it.
2550 * When the loadhook trap is hit (r_debug_state, set at program
2551 * initialization), the arguments can be found on the stack:
2553 * +8 struct link_map *m
2554 * +4 struct r_debug *rd
2558 r_debug_state(struct r_debug* rd, struct link_map *m)
2563 * Get address of the pointer variable in the main program.
2565 static const void **
2566 get_program_var_addr(const char *name)
2568 const Obj_Entry *obj;
2571 hash = elf_hash(name);
2572 for (obj = obj_main; obj != NULL; obj = obj->next) {
2575 if ((def = symlook_obj(name, hash, obj, NULL, 0)) != NULL) {
2578 addr = (const void **)(obj->relocbase + def->st_value);
2586 * Set a pointer variable in the main program to the given value. This
2587 * is used to set key variables such as "environ" before any of the
2588 * init functions are called.
2591 set_program_var(const char *name, const void *value)
2595 if ((addr = get_program_var_addr(name)) != NULL) {
2596 dbg("\"%s\": *%p <-- %p", name, addr, value);
2602 * Given a symbol name in a referencing object, find the corresponding
2603 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2604 * no definition was found. Returns a pointer to the Obj_Entry of the
2605 * defining object via the reference parameter DEFOBJ_OUT.
2607 static const Elf_Sym *
2608 symlook_default(const char *name, unsigned long hash, const Obj_Entry *refobj,
2609 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags)
2613 const Elf_Sym *symp;
2614 const Obj_Entry *obj;
2615 const Obj_Entry *defobj;
2616 const Objlist_Entry *elm;
2619 donelist_init(&donelist);
2621 /* Look first in the referencing object if linked symbolically. */
2622 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2623 symp = symlook_obj(name, hash, refobj, ventry, flags);
2630 /* Search all objects loaded at program start up. */
2631 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2632 symp = symlook_list(name, hash, &list_main, &obj, ventry, flags,
2635 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2641 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2642 STAILQ_FOREACH(elm, &list_global, link) {
2643 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2645 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry,
2648 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2654 /* Search all dlopened DAGs containing the referencing object. */
2655 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2656 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2658 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, ventry,
2661 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2668 * Search the dynamic linker itself, and possibly resolve the
2669 * symbol from there. This is how the application links to
2670 * dynamic linker services such as dlopen. Only the values listed
2671 * in the "exports" array can be resolved from the dynamic linker.
2673 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2674 symp = symlook_obj(name, hash, &obj_rtld, ventry, flags);
2675 if (symp != NULL && is_exported(symp)) {
2682 *defobj_out = defobj;
2686 static const Elf_Sym *
2687 symlook_list(const char *name, unsigned long hash, const Objlist *objlist,
2688 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags,
2691 const Elf_Sym *symp;
2693 const Obj_Entry *defobj;
2694 const Objlist_Entry *elm;
2698 STAILQ_FOREACH(elm, objlist, link) {
2699 if (donelist_check(dlp, elm->obj))
2701 if ((symp = symlook_obj(name, hash, elm->obj, ventry, flags)) != NULL) {
2702 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2705 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2711 *defobj_out = defobj;
2716 * Search the symbol table of a shared object and all objects needed
2717 * by it for a symbol of the given name. Search order is
2718 * breadth-first. Returns a pointer to the symbol, or NULL if no
2719 * definition was found.
2721 static const Elf_Sym *
2722 symlook_needed(const char *name, unsigned long hash, const Needed_Entry *needed,
2723 const Obj_Entry **defobj_out, const Ver_Entry *ventry, int flags,
2726 const Elf_Sym *def, *def_w;
2727 const Needed_Entry *n;
2728 const Obj_Entry *obj, *defobj, *defobj1;
2732 for (n = needed; n != NULL; n = n->next) {
2733 if ((obj = n->obj) == NULL ||
2734 donelist_check(dlp, obj) ||
2735 (def = symlook_obj(name, hash, obj, ventry, flags)) == NULL)
2738 if (ELF_ST_BIND(def->st_info) != STB_WEAK) {
2739 *defobj_out = defobj;
2744 * There we come when either symbol definition is not found in
2745 * directly needed objects, or found symbol is weak.
2747 for (n = needed; n != NULL; n = n->next) {
2748 if ((obj = n->obj) == NULL)
2750 def_w = symlook_needed(name, hash, obj->needed, &defobj1,
2751 ventry, flags, dlp);
2754 if (def == NULL || ELF_ST_BIND(def_w->st_info) != STB_WEAK) {
2758 if (ELF_ST_BIND(def_w->st_info) != STB_WEAK)
2762 *defobj_out = defobj;
2767 * Search the symbol table of a single shared object for a symbol of
2768 * the given name and version, if requested. Returns a pointer to the
2769 * symbol, or NULL if no definition was found.
2771 * The symbol's hash value is passed in for efficiency reasons; that
2772 * eliminates many recomputations of the hash value.
2775 symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2776 const Ver_Entry *ventry, int flags)
2778 unsigned long symnum;
2779 const Elf_Sym *vsymp;
2783 if (obj->buckets == NULL)
2788 symnum = obj->buckets[hash % obj->nbuckets];
2790 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
2791 const Elf_Sym *symp;
2794 if (symnum >= obj->nchains)
2795 return NULL; /* Bad object */
2797 symp = obj->symtab + symnum;
2798 strp = obj->strtab + symp->st_name;
2800 switch (ELF_ST_TYPE(symp->st_info)) {
2804 if (symp->st_value == 0)
2808 if (symp->st_shndx != SHN_UNDEF)
2811 else if (((flags & SYMLOOK_IN_PLT) == 0) &&
2812 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
2819 if (name[0] != strp[0] || strcmp(name, strp) != 0)
2822 if (ventry == NULL) {
2823 if (obj->versyms != NULL) {
2824 verndx = VER_NDX(obj->versyms[symnum]);
2825 if (verndx > obj->vernum) {
2826 _rtld_error("%s: symbol %s references wrong version %d",
2827 obj->path, obj->strtab + symnum, verndx);
2831 * If we are not called from dlsym (i.e. this is a normal
2832 * relocation from unversioned binary, accept the symbol
2833 * immediately if it happens to have first version after
2834 * this shared object became versioned. Otherwise, if
2835 * symbol is versioned and not hidden, remember it. If it
2836 * is the only symbol with this name exported by the
2837 * shared object, it will be returned as a match at the
2838 * end of the function. If symbol is global (verndx < 2)
2839 * accept it unconditionally.
2841 if ((flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN)
2843 else if (verndx >= VER_NDX_GIVEN) {
2844 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
2854 if (obj->versyms == NULL) {
2855 if (object_match_name(obj, ventry->name)) {
2856 _rtld_error("%s: object %s should provide version %s for "
2857 "symbol %s", obj_rtld.path, obj->path, ventry->name,
2858 obj->strtab + symnum);
2862 verndx = VER_NDX(obj->versyms[symnum]);
2863 if (verndx > obj->vernum) {
2864 _rtld_error("%s: symbol %s references wrong version %d",
2865 obj->path, obj->strtab + symnum, verndx);
2868 if (obj->vertab[verndx].hash != ventry->hash ||
2869 strcmp(obj->vertab[verndx].name, ventry->name)) {
2871 * Version does not match. Look if this is a global symbol
2872 * and if it is not hidden. If global symbol (verndx < 2)
2873 * is available, use it. Do not return symbol if we are
2874 * called by dlvsym, because dlvsym looks for a specific
2875 * version and default one is not what dlvsym wants.
2877 if ((flags & SYMLOOK_DLSYM) ||
2878 (obj->versyms[symnum] & VER_NDX_HIDDEN) ||
2879 (verndx >= VER_NDX_GIVEN))
2886 return (vcount == 1) ? vsymp : NULL;
2890 trace_loaded_objects(Obj_Entry *obj)
2892 char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
2895 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
2898 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL)
2899 fmt1 = "\t%o => %p (%x)\n";
2901 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL)
2902 fmt2 = "\t%o (%x)\n";
2904 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL");
2906 for (; obj; obj = obj->next) {
2907 Needed_Entry *needed;
2911 if (list_containers && obj->needed != NULL)
2912 printf("%s:\n", obj->path);
2913 for (needed = obj->needed; needed; needed = needed->next) {
2914 if (needed->obj != NULL) {
2915 if (needed->obj->traced && !list_containers)
2917 needed->obj->traced = true;
2918 path = needed->obj->path;
2922 name = (char *)obj->strtab + needed->name;
2923 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2925 fmt = is_lib ? fmt1 : fmt2;
2926 while ((c = *fmt++) != '\0') {
2952 printf("%s", main_local);
2955 printf("%s", obj_main->path);
2962 printf("%d", sodp->sod_major);
2965 printf("%d", sodp->sod_minor);
2972 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2984 * Unload a dlopened object and its dependencies from memory and from
2985 * our data structures. It is assumed that the DAG rooted in the
2986 * object has already been unreferenced, and that the object has a
2987 * reference count of 0.
2990 unload_object(Obj_Entry *root)
2995 assert(root->refcount == 0);
2998 * Pass over the DAG removing unreferenced objects from
2999 * appropriate lists.
3001 unlink_object(root);
3003 /* Unmap all objects that are no longer referenced. */
3004 linkp = &obj_list->next;
3005 while ((obj = *linkp) != NULL) {
3006 if (obj->refcount == 0) {
3007 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
3009 dbg("unloading \"%s\"", obj->path);
3010 munmap(obj->mapbase, obj->mapsize);
3011 linkmap_delete(obj);
3022 unlink_object(Obj_Entry *root)
3026 if (root->refcount == 0) {
3027 /* Remove the object from the RTLD_GLOBAL list. */
3028 objlist_remove(&list_global, root);
3030 /* Remove the object from all objects' DAG lists. */
3031 STAILQ_FOREACH(elm, &root->dagmembers, link) {
3032 objlist_remove(&elm->obj->dldags, root);
3033 if (elm->obj != root)
3034 unlink_object(elm->obj);
3040 ref_dag(Obj_Entry *root)
3044 STAILQ_FOREACH(elm, &root->dagmembers, link)
3045 elm->obj->refcount++;
3049 unref_dag(Obj_Entry *root)
3053 STAILQ_FOREACH(elm, &root->dagmembers, link)
3054 elm->obj->refcount--;
3058 * Common code for MD __tls_get_addr().
3061 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
3063 Elf_Addr* dtv = *dtvp;
3066 /* Check dtv generation in case new modules have arrived */
3067 if (dtv[0] != tls_dtv_generation) {
3071 lockstate = wlock_acquire(rtld_bind_lock);
3072 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3074 if (to_copy > tls_max_index)
3075 to_copy = tls_max_index;
3076 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
3077 newdtv[0] = tls_dtv_generation;
3078 newdtv[1] = tls_max_index;
3080 wlock_release(rtld_bind_lock, lockstate);
3084 /* Dynamically allocate module TLS if necessary */
3085 if (!dtv[index + 1]) {
3086 /* Signal safe, wlock will block out signals. */
3087 lockstate = wlock_acquire(rtld_bind_lock);
3088 if (!dtv[index + 1])
3089 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
3090 wlock_release(rtld_bind_lock, lockstate);
3092 return (void*) (dtv[index + 1] + offset);
3095 /* XXX not sure what variants to use for arm. */
3097 #if defined(__ia64__) || defined(__powerpc__)
3100 * Allocate Static TLS using the Variant I method.
3103 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
3112 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
3115 assert(tcbsize >= TLS_TCB_SIZE);
3116 tcb = calloc(1, tls_static_space - TLS_TCB_SIZE + tcbsize);
3117 tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE);
3119 if (oldtcb != NULL) {
3120 memcpy(tls, oldtcb, tls_static_space);
3123 /* Adjust the DTV. */
3125 for (i = 0; i < dtv[1]; i++) {
3126 if (dtv[i+2] >= (Elf_Addr)oldtcb &&
3127 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) {
3128 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tls;
3132 dtv = calloc(tls_max_index + 2, sizeof(Elf_Addr));
3134 dtv[0] = tls_dtv_generation;
3135 dtv[1] = tls_max_index;
3137 for (obj = objs; obj; obj = obj->next) {
3138 if (obj->tlsoffset) {
3139 addr = (Elf_Addr)tls + obj->tlsoffset;
3140 memset((void*) (addr + obj->tlsinitsize),
3141 0, obj->tlssize - obj->tlsinitsize);
3143 memcpy((void*) addr, obj->tlsinit,
3145 dtv[obj->tlsindex + 1] = addr;
3154 free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
3157 Elf_Addr tlsstart, tlsend;
3160 assert(tcbsize >= TLS_TCB_SIZE);
3162 tlsstart = (Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE;
3163 tlsend = tlsstart + tls_static_space;
3165 dtv = *(Elf_Addr **)tlsstart;
3167 for (i = 0; i < dtvsize; i++) {
3168 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) {
3169 free((void*)dtv[i+2]);
3178 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \
3179 defined(__arm__) || defined(__mips__)
3182 * Allocate Static TLS using the Variant II method.
3185 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
3190 Elf_Addr *dtv, *olddtv;
3191 Elf_Addr segbase, oldsegbase, addr;
3194 size = round(tls_static_space, tcbalign);
3196 assert(tcbsize >= 2*sizeof(Elf_Addr));
3197 tls = calloc(1, size + tcbsize);
3198 dtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3200 segbase = (Elf_Addr)(tls + size);
3201 ((Elf_Addr*)segbase)[0] = segbase;
3202 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
3204 dtv[0] = tls_dtv_generation;
3205 dtv[1] = tls_max_index;
3209 * Copy the static TLS block over whole.
3211 oldsegbase = (Elf_Addr) oldtls;
3212 memcpy((void *)(segbase - tls_static_space),
3213 (const void *)(oldsegbase - tls_static_space),
3217 * If any dynamic TLS blocks have been created tls_get_addr(),
3220 olddtv = ((Elf_Addr**)oldsegbase)[1];
3221 for (i = 0; i < olddtv[1]; i++) {
3222 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) {
3223 dtv[i+2] = olddtv[i+2];
3229 * We assume that this block was the one we created with
3230 * allocate_initial_tls().
3232 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
3234 for (obj = objs; obj; obj = obj->next) {
3235 if (obj->tlsoffset) {
3236 addr = segbase - obj->tlsoffset;
3237 memset((void*) (addr + obj->tlsinitsize),
3238 0, obj->tlssize - obj->tlsinitsize);
3240 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
3241 dtv[obj->tlsindex + 1] = addr;
3246 return (void*) segbase;
3250 free_tls(void *tls, size_t tcbsize, size_t tcbalign)
3255 Elf_Addr tlsstart, tlsend;
3258 * Figure out the size of the initial TLS block so that we can
3259 * find stuff which ___tls_get_addr() allocated dynamically.
3261 size = round(tls_static_space, tcbalign);
3263 dtv = ((Elf_Addr**)tls)[1];
3265 tlsend = (Elf_Addr) tls;
3266 tlsstart = tlsend - size;
3267 for (i = 0; i < dtvsize; i++) {
3268 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] > tlsend)) {
3269 free((void*) dtv[i+2]);
3273 free((void*) tlsstart);
3280 * Allocate TLS block for module with given index.
3283 allocate_module_tls(int index)
3288 for (obj = obj_list; obj; obj = obj->next) {
3289 if (obj->tlsindex == index)
3293 _rtld_error("Can't find module with TLS index %d", index);
3297 p = malloc(obj->tlssize);
3298 memcpy(p, obj->tlsinit, obj->tlsinitsize);
3299 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
3305 allocate_tls_offset(Obj_Entry *obj)
3312 if (obj->tlssize == 0) {
3313 obj->tls_done = true;
3317 if (obj->tlsindex == 1)
3318 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
3320 off = calculate_tls_offset(tls_last_offset, tls_last_size,
3321 obj->tlssize, obj->tlsalign);
3324 * If we have already fixed the size of the static TLS block, we
3325 * must stay within that size. When allocating the static TLS, we
3326 * leave a small amount of space spare to be used for dynamically
3327 * loading modules which use static TLS.
3329 if (tls_static_space) {
3330 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
3334 tls_last_offset = obj->tlsoffset = off;
3335 tls_last_size = obj->tlssize;
3336 obj->tls_done = true;
3342 free_tls_offset(Obj_Entry *obj)
3344 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \
3345 defined(__arm__) || defined(__mips__)
3347 * If we were the last thing to allocate out of the static TLS
3348 * block, we give our space back to the 'allocator'. This is a
3349 * simplistic workaround to allow libGL.so.1 to be loaded and
3350 * unloaded multiple times. We only handle the Variant II
3351 * mechanism for now - this really needs a proper allocator.
3353 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
3354 == calculate_tls_end(tls_last_offset, tls_last_size)) {
3355 tls_last_offset -= obj->tlssize;
3362 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
3367 lockstate = wlock_acquire(rtld_bind_lock);
3368 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign);
3369 wlock_release(rtld_bind_lock, lockstate);
3374 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
3378 lockstate = wlock_acquire(rtld_bind_lock);
3379 free_tls(tcb, tcbsize, tcbalign);
3380 wlock_release(rtld_bind_lock, lockstate);
3384 object_add_name(Obj_Entry *obj, const char *name)
3390 entry = malloc(sizeof(Name_Entry) + len);
3392 if (entry != NULL) {
3393 strcpy(entry->name, name);
3394 STAILQ_INSERT_TAIL(&obj->names, entry, link);
3399 object_match_name(const Obj_Entry *obj, const char *name)
3403 STAILQ_FOREACH(entry, &obj->names, link) {
3404 if (strcmp(name, entry->name) == 0)
3411 locate_dependency(const Obj_Entry *obj, const char *name)
3413 const Objlist_Entry *entry;
3414 const Needed_Entry *needed;
3416 STAILQ_FOREACH(entry, &list_main, link) {
3417 if (object_match_name(entry->obj, name))
3421 for (needed = obj->needed; needed != NULL; needed = needed->next) {
3422 if (needed->obj == NULL)
3424 if (object_match_name(needed->obj, name))
3427 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
3433 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
3434 const Elf_Vernaux *vna)
3436 const Elf_Verdef *vd;
3437 const char *vername;
3439 vername = refobj->strtab + vna->vna_name;
3440 vd = depobj->verdef;
3442 _rtld_error("%s: version %s required by %s not defined",
3443 depobj->path, vername, refobj->path);
3447 if (vd->vd_version != VER_DEF_CURRENT) {
3448 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
3449 depobj->path, vd->vd_version);
3452 if (vna->vna_hash == vd->vd_hash) {
3453 const Elf_Verdaux *aux = (const Elf_Verdaux *)
3454 ((char *)vd + vd->vd_aux);
3455 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
3458 if (vd->vd_next == 0)
3460 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3462 if (vna->vna_flags & VER_FLG_WEAK)
3464 _rtld_error("%s: version %s required by %s not found",
3465 depobj->path, vername, refobj->path);
3470 rtld_verify_object_versions(Obj_Entry *obj)
3472 const Elf_Verneed *vn;
3473 const Elf_Verdef *vd;
3474 const Elf_Verdaux *vda;
3475 const Elf_Vernaux *vna;
3476 const Obj_Entry *depobj;
3477 int maxvernum, vernum;
3481 * Walk over defined and required version records and figure out
3482 * max index used by any of them. Do very basic sanity checking
3486 while (vn != NULL) {
3487 if (vn->vn_version != VER_NEED_CURRENT) {
3488 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
3489 obj->path, vn->vn_version);
3492 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
3494 vernum = VER_NEED_IDX(vna->vna_other);
3495 if (vernum > maxvernum)
3497 if (vna->vna_next == 0)
3499 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
3501 if (vn->vn_next == 0)
3503 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
3507 while (vd != NULL) {
3508 if (vd->vd_version != VER_DEF_CURRENT) {
3509 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
3510 obj->path, vd->vd_version);
3513 vernum = VER_DEF_IDX(vd->vd_ndx);
3514 if (vernum > maxvernum)
3516 if (vd->vd_next == 0)
3518 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3525 * Store version information in array indexable by version index.
3526 * Verify that object version requirements are satisfied along the
3529 obj->vernum = maxvernum + 1;
3530 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry));
3533 while (vd != NULL) {
3534 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
3535 vernum = VER_DEF_IDX(vd->vd_ndx);
3536 assert(vernum <= maxvernum);
3537 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
3538 obj->vertab[vernum].hash = vd->vd_hash;
3539 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
3540 obj->vertab[vernum].file = NULL;
3541 obj->vertab[vernum].flags = 0;
3543 if (vd->vd_next == 0)
3545 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
3549 while (vn != NULL) {
3550 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
3551 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
3553 if (check_object_provided_version(obj, depobj, vna))
3555 vernum = VER_NEED_IDX(vna->vna_other);
3556 assert(vernum <= maxvernum);
3557 obj->vertab[vernum].hash = vna->vna_hash;
3558 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
3559 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
3560 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
3561 VER_INFO_HIDDEN : 0;
3562 if (vna->vna_next == 0)
3564 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
3566 if (vn->vn_next == 0)
3568 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
3574 rtld_verify_versions(const Objlist *objlist)
3576 Objlist_Entry *entry;
3580 STAILQ_FOREACH(entry, objlist, link) {
3582 * Skip dummy objects or objects that have their version requirements
3585 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
3587 if (rtld_verify_object_versions(entry->obj) == -1) {
3589 if (ld_tracing == NULL)
3593 if (rc == 0 || ld_tracing != NULL)
3594 rc = rtld_verify_object_versions(&obj_rtld);
3599 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
3604 vernum = VER_NDX(obj->versyms[symnum]);
3605 if (vernum >= obj->vernum) {
3606 _rtld_error("%s: symbol %s has wrong verneed value %d",
3607 obj->path, obj->strtab + symnum, vernum);
3608 } else if (obj->vertab[vernum].hash != 0) {
3609 return &obj->vertab[vernum];