2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * Copyright 2009, 2010, 2011 Konstantin Belousov <kib@FreeBSD.ORG>.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 * Dynamic linker for ELF.
33 * John Polstra <jdp@polstra.com>.
37 #error "GCC is needed to compile this file"
40 #include <sys/param.h>
41 #include <sys/mount.h>
44 #include <sys/sysctl.h>
46 #include <sys/utsname.h>
47 #include <sys/ktrace.h>
48 #include <sys/resident.h>
51 #include <machine/tls.h>
66 #include "rtld_printf.h"
68 #define PATH_RTLD "/usr/libexec/ld-elf.so.2"
69 #define LD_ARY_CACHE 16
72 typedef void (*func_ptr_type)();
73 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
76 * Function declarations.
78 static const char *_getenv_ld(const char *id);
79 static void die(void) __dead2;
80 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
82 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *);
83 static void digest_dynamic(Obj_Entry *, int);
84 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
85 static Obj_Entry *dlcheck(void *);
86 static Obj_Entry *dlopen_object(const char *name, Obj_Entry *refobj,
87 int lo_flags, int mode);
88 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
89 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
90 static bool donelist_check(DoneList *, const Obj_Entry *);
91 static void errmsg_restore(char *);
92 static char *errmsg_save(void);
93 static void *fill_search_info(const char *, size_t, void *);
94 static char *find_library(const char *, const Obj_Entry *);
95 static const char *gethints(void);
96 static void init_dag(Obj_Entry *);
97 static void init_rtld(caddr_t, Elf_Auxinfo **);
98 static void initlist_add_neededs(Needed_Entry *, Objlist *);
99 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
100 static bool is_exported(const Elf_Sym *);
101 static void linkmap_add(Obj_Entry *);
102 static void linkmap_delete(Obj_Entry *);
103 static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
104 static void unload_filtees(Obj_Entry *);
105 static int load_needed_objects(Obj_Entry *, int);
106 static int load_preload_objects(void);
107 static Obj_Entry *load_object(const char *, const Obj_Entry *, int);
108 static void map_stacks_exec(RtldLockState *);
109 static Obj_Entry *obj_from_addr(const void *);
110 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
111 static void objlist_call_init(Objlist *, RtldLockState *);
112 static void preinitialize_main_object (void);
113 static void objlist_clear(Objlist *);
114 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
115 static void objlist_init(Objlist *);
116 static void objlist_push_head(Objlist *, Obj_Entry *);
117 static void objlist_push_tail(Objlist *, Obj_Entry *);
118 static void objlist_remove(Objlist *, Obj_Entry *);
119 static void *path_enumerate(const char *, path_enum_proc, void *);
120 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, RtldLockState *);
121 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
122 RtldLockState *lockstate);
123 static int rtld_dirname(const char *, char *);
124 static int rtld_dirname_abs(const char *, char *);
125 static void rtld_exit(void);
126 static char *search_library_path(const char *, const char *);
127 static const void **get_program_var_addr(const char *, RtldLockState *);
128 static void set_program_var(const char *, const void *);
129 static int symlook_default(SymLook *, const Obj_Entry *refobj);
130 static int symlook_global(SymLook *, DoneList *);
131 static void symlook_init_from_req(SymLook *, const SymLook *);
132 static int symlook_list(SymLook *, const Objlist *, DoneList *);
133 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
134 static int symlook_obj1(SymLook *, const Obj_Entry *);
135 static void trace_loaded_objects(Obj_Entry *);
136 static void unlink_object(Obj_Entry *);
137 static void unload_object(Obj_Entry *);
138 static void unref_dag(Obj_Entry *);
139 static void ref_dag(Obj_Entry *);
140 static int origin_subst_one(char **, const char *, const char *,
141 const char *, char *);
142 static char *origin_subst(const char *, const char *);
143 static int rtld_verify_versions(const Objlist *);
144 static int rtld_verify_object_versions(Obj_Entry *);
145 static void object_add_name(Obj_Entry *, const char *);
146 static int object_match_name(const Obj_Entry *, const char *);
147 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
148 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
149 struct dl_phdr_info *phdr_info);
151 void r_debug_state(struct r_debug *, struct link_map *) __noinline;
156 static char *error_message; /* Message for dlerror(), or NULL */
157 struct r_debug r_debug; /* for GDB; */
158 static bool libmap_disable; /* Disable libmap */
159 static bool ld_loadfltr; /* Immediate filters processing */
160 static char *libmap_override; /* Maps to use in addition to libmap.conf */
161 static bool trust; /* False for setuid and setgid programs */
162 static bool dangerous_ld_env; /* True if environment variables have been
163 used to affect the libraries loaded */
164 static const char *ld_bind_now; /* Environment variable for immediate binding */
165 static const char *ld_debug; /* Environment variable for debugging */
166 static const char *ld_library_path; /* Environment variable for search path */
167 static char *ld_preload; /* Environment variable for libraries to
169 static const char *ld_elf_hints_path; /* Environment variable for alternative hints path */
170 static const char *ld_tracing; /* Called from ldd to print libs */
171 static const char *ld_utrace; /* Use utrace() to log events. */
172 static int (*rtld_functrace)( /* Optional function call tracing hook */
173 const char *caller_obj,
174 const char *callee_obj,
175 const char *callee_func,
177 static const Obj_Entry *rtld_functrace_obj; /* Object thereof */
178 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
179 static Obj_Entry **obj_tail; /* Link field of last object in list */
180 static Obj_Entry **preload_tail;
181 static Obj_Entry *obj_main; /* The main program shared object */
182 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
183 static unsigned int obj_count; /* Number of objects in obj_list */
184 static unsigned int obj_loads; /* Number of objects in obj_list */
186 static int ld_resident; /* Non-zero if resident */
187 static const char *ld_ary[LD_ARY_CACHE];
189 static Objlist initlist;
191 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
192 STAILQ_HEAD_INITIALIZER(list_global);
193 static Objlist list_main = /* Objects loaded at program startup */
194 STAILQ_HEAD_INITIALIZER(list_main);
195 static Objlist list_fini = /* Objects needing fini() calls */
196 STAILQ_HEAD_INITIALIZER(list_fini);
198 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
200 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
202 extern Elf_Dyn _DYNAMIC;
203 #pragma weak _DYNAMIC
204 #ifndef RTLD_IS_DYNAMIC
205 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
208 #ifdef ENABLE_OSRELDATE
212 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
213 static int max_stack_flags;
216 * These are the functions the dynamic linker exports to application
217 * programs. They are the only symbols the dynamic linker is willing
218 * to export from itself.
220 static func_ptr_type exports[] = {
221 (func_ptr_type) &_rtld_error,
222 (func_ptr_type) &dlclose,
223 (func_ptr_type) &dlerror,
224 (func_ptr_type) &dlopen,
225 (func_ptr_type) &dlfunc,
226 (func_ptr_type) &dlsym,
227 (func_ptr_type) &dlvsym,
228 (func_ptr_type) &dladdr,
229 (func_ptr_type) &dlinfo,
230 (func_ptr_type) &dl_iterate_phdr,
232 (func_ptr_type) &___tls_get_addr,
234 (func_ptr_type) &__tls_get_addr,
235 (func_ptr_type) &__tls_get_addr_tcb,
236 (func_ptr_type) &_rtld_allocate_tls,
237 (func_ptr_type) &_rtld_free_tls,
238 (func_ptr_type) &_rtld_call_init,
239 (func_ptr_type) &_rtld_thread_init,
240 (func_ptr_type) &_rtld_addr_phdr,
241 (func_ptr_type) &_rtld_get_stack_prot,
246 * Global declarations normally provided by crt1. The dynamic linker is
247 * not built with crt1, so we have to provide them ourselves.
253 * Globals passed as arguments to .init_array and .preinit_array functions
260 * Globals to control TLS allocation.
262 size_t tls_last_offset; /* Static TLS offset of last module */
263 size_t tls_last_size; /* Static TLS size of last module */
264 size_t tls_static_space; /* Static TLS space allocated */
265 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
266 int tls_max_index = 1; /* Largest module index allocated */
269 * Fill in a DoneList with an allocation large enough to hold all of
270 * the currently-loaded objects. Keep this as a macro since it calls
271 * alloca and we want that to occur within the scope of the caller.
273 #define donelist_init(dlp) \
274 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
275 assert((dlp)->objs != NULL), \
276 (dlp)->num_alloc = obj_count, \
279 #define UTRACE_DLOPEN_START 1
280 #define UTRACE_DLOPEN_STOP 2
281 #define UTRACE_DLCLOSE_START 3
282 #define UTRACE_DLCLOSE_STOP 4
283 #define UTRACE_LOAD_OBJECT 5
284 #define UTRACE_UNLOAD_OBJECT 6
285 #define UTRACE_ADD_RUNDEP 7
286 #define UTRACE_PRELOAD_FINISHED 8
287 #define UTRACE_INIT_CALL 9
288 #define UTRACE_FINI_CALL 10
291 char sig[4]; /* 'RTLD' */
294 void *mapbase; /* Used for 'parent' and 'init/fini' */
296 int refcnt; /* Used for 'mode' */
297 char name[MAXPATHLEN];
300 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
301 if (ld_utrace != NULL) \
302 ld_utrace_log(e, h, mb, ms, r, n); \
306 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
307 int refcnt, const char *name)
309 struct utrace_rtld ut;
317 ut.mapbase = mapbase;
318 ut.mapsize = mapsize;
320 bzero(ut.name, sizeof(ut.name));
322 strlcpy(ut.name, name, sizeof(ut.name));
323 utrace(&ut, sizeof(ut));
327 * Main entry point for dynamic linking. The first argument is the
328 * stack pointer. The stack is expected to be laid out as described
329 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
330 * Specifically, the stack pointer points to a word containing
331 * ARGC. Following that in the stack is a null-terminated sequence
332 * of pointers to argument strings. Then comes a null-terminated
333 * sequence of pointers to environment strings. Finally, there is a
334 * sequence of "auxiliary vector" entries.
336 * The second argument points to a place to store the dynamic linker's
337 * exit procedure pointer and the third to a place to store the main
340 * The return value is the main program's entry point.
343 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
345 Elf_Auxinfo *aux_info[AT_COUNT];
353 Objlist_Entry *entry;
356 /* marino: DO NOT MOVE THESE VARIABLES TO _rtld
357 Obj_Entry **preload_tail;
359 from global to here. It will break the DWARF2 unwind scheme.
360 The system compilers were unaffected, but not gcc 4.6
364 * On entry, the dynamic linker itself has not been relocated yet.
365 * Be very careful not to reference any global data until after
366 * init_rtld has returned. It is OK to reference file-scope statics
367 * and string constants, and to call static and global functions.
370 /* Find the auxiliary vector on the stack. */
373 sp += argc + 1; /* Skip over arguments and NULL terminator */
377 * If we aren't already resident we have to dig out some more info.
378 * Note that auxinfo does not exist when we are resident.
380 * I'm not sure about the ld_resident check. It seems to read zero
381 * prior to relocation, which is what we want. When running from a
382 * resident copy everything will be relocated so we are definitely
385 if (ld_resident == 0) {
386 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
388 aux = (Elf_Auxinfo *) sp;
390 /* Digest the auxiliary vector. */
391 for (i = 0; i < AT_COUNT; i++)
393 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
394 if (auxp->a_type < AT_COUNT)
395 aux_info[auxp->a_type] = auxp;
398 /* Initialize and relocate ourselves. */
399 assert(aux_info[AT_BASE] != NULL);
400 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
403 ld_index = 0; /* don't use old env cache in case we are resident */
404 __progname = obj_rtld.path;
405 argv0 = argv[0] != NULL ? argv[0] : "(null)";
410 trust = !issetugid();
412 ld_bind_now = _getenv_ld("LD_BIND_NOW");
414 * If the process is tainted, then we un-set the dangerous environment
415 * variables. The process will be marked as tainted until setuid(2)
416 * is called. If any child process calls setuid(2) we do not want any
417 * future processes to honor the potentially un-safe variables.
420 if ( unsetenv("LD_DEBUG")
421 || unsetenv("LD_PRELOAD")
422 || unsetenv("LD_LIBRARY_PATH")
423 || unsetenv("LD_ELF_HINTS_PATH")
424 || unsetenv("LD_LIBMAP")
425 || unsetenv("LD_LIBMAP_DISABLE")
426 || unsetenv("LD_LOADFLTR")
428 _rtld_error("environment corrupt; aborting");
432 ld_debug = _getenv_ld("LD_DEBUG");
433 libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL;
434 libmap_override = (char *)_getenv_ld("LD_LIBMAP");
435 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
436 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
437 ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH");
438 ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL;
439 dangerous_ld_env = (ld_library_path != NULL)
440 || (ld_preload != NULL)
441 || (ld_elf_hints_path != NULL)
443 || (libmap_override != NULL)
446 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
447 ld_utrace = _getenv_ld("LD_UTRACE");
449 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
450 ld_elf_hints_path = _PATH_ELF_HINTS;
452 if (ld_debug != NULL && *ld_debug != '\0')
454 dbg("%s is initialized, base address = %p", __progname,
455 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
456 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
457 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
459 dbg("initializing thread locks");
463 * If we are resident we can skip work that we have already done.
464 * Note that the stack is reset and there is no Elf_Auxinfo
465 * when running from a resident image, and the static globals setup
466 * between here and resident_skip will have already been setup.
472 * Load the main program, or process its program header if it is
475 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
476 int fd = aux_info[AT_EXECFD]->a_un.a_val;
477 dbg("loading main program");
478 obj_main = map_object(fd, argv0, NULL);
480 if (obj_main == NULL)
482 max_stack_flags = obj->stack_flags;
483 } else { /* Main program already loaded. */
484 const Elf_Phdr *phdr;
488 dbg("processing main program's program header");
489 assert(aux_info[AT_PHDR] != NULL);
490 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
491 assert(aux_info[AT_PHNUM] != NULL);
492 phnum = aux_info[AT_PHNUM]->a_un.a_val;
493 assert(aux_info[AT_PHENT] != NULL);
494 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
495 assert(aux_info[AT_ENTRY] != NULL);
496 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
497 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
501 char buf[MAXPATHLEN];
502 if (aux_info[AT_EXECPATH] != 0) {
505 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
506 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
507 if (kexecpath[0] == '/')
508 obj_main->path = kexecpath;
509 else if (getcwd(buf, sizeof(buf)) == NULL ||
510 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
511 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
512 obj_main->path = xstrdup(argv0);
514 obj_main->path = xstrdup(buf);
516 char resolved[MAXPATHLEN];
517 dbg("No AT_EXECPATH");
518 if (argv0[0] == '/') {
519 if (realpath(argv0, resolved) != NULL)
520 obj_main->path = xstrdup(resolved);
522 obj_main->path = xstrdup(argv0);
524 if (getcwd(buf, sizeof(buf)) != NULL
525 && strlcat(buf, "/", sizeof(buf)) < sizeof(buf)
526 && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf)
527 && access(buf, R_OK) == 0
528 && realpath(buf, resolved) != NULL)
529 obj_main->path = xstrdup(resolved);
531 obj_main->path = xstrdup(argv0);
534 dbg("obj_main path %s", obj_main->path);
535 obj_main->mainprog = true;
537 if (aux_info[AT_STACKPROT] != NULL &&
538 aux_info[AT_STACKPROT]->a_un.a_val != 0)
539 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
542 * Get the actual dynamic linker pathname from the executable if
543 * possible. (It should always be possible.) That ensures that
544 * gdb will find the right dynamic linker even if a non-standard
547 if (obj_main->interp != NULL &&
548 strcmp(obj_main->interp, obj_rtld.path) != 0) {
550 obj_rtld.path = xstrdup(obj_main->interp);
551 __progname = obj_rtld.path;
554 digest_dynamic(obj_main, 0);
556 linkmap_add(obj_main);
557 linkmap_add(&obj_rtld);
559 /* Link the main program into the list of objects. */
560 *obj_tail = obj_main;
561 obj_tail = &obj_main->next;
564 /* Make sure we don't call the main program's init and fini functions. */
565 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
566 obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL;
568 /* Initialize a fake symbol for resolving undefined weak references. */
569 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
570 sym_zero.st_shndx = SHN_UNDEF;
571 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
574 libmap_disable = (bool)lm_init(libmap_override);
576 dbg("loading LD_PRELOAD libraries");
577 if (load_preload_objects() == -1)
579 preload_tail = obj_tail;
581 dbg("loading needed objects");
582 if (load_needed_objects(obj_main, 0) == -1)
585 /* Make a list of all objects loaded at startup. */
586 for (obj = obj_list; obj != NULL; obj = obj->next) {
587 objlist_push_tail(&list_main, obj);
591 dbg("checking for required versions");
592 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
597 if (ld_tracing) { /* We're done */
598 trace_loaded_objects(obj_main);
602 if (ld_resident) /* XXX clean this up! */
605 if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) {
606 dump_relocations(obj_main);
610 /* setup TLS for main thread */
611 dbg("initializing initial thread local storage");
612 STAILQ_FOREACH(entry, &list_main, link) {
614 * Allocate all the initial objects out of the static TLS
615 * block even if they didn't ask for it.
617 allocate_tls_offset(entry->obj);
620 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
623 * Do not try to allocate the TLS here, let libc do it itself.
624 * (crt1 for the program will call _init_tls())
627 if (relocate_objects(obj_main,
628 ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, NULL) == -1)
631 dbg("doing copy relocations");
632 if (do_copy_relocations(obj_main) == -1)
637 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
638 if (exec_sys_unregister(-1) < 0) {
639 dbg("exec_sys_unregister failed %d\n", errno);
642 dbg("exec_sys_unregister success\n");
646 if (_getenv_ld("LD_DUMP_REL_POST") != NULL) {
647 dump_relocations(obj_main);
651 dbg("initializing key program variables");
652 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
653 set_program_var("environ", env);
654 set_program_var("__elf_aux_vector", aux);
656 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
657 extern void resident_start(void);
659 if (exec_sys_register(resident_start) < 0) {
660 dbg("exec_sys_register failed %d\n", errno);
663 dbg("exec_sys_register success\n");
667 /* Make a list of init functions to call. */
668 objlist_init(&initlist);
669 initlist_add_objects(obj_list, preload_tail, &initlist);
671 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
673 map_stacks_exec(NULL);
675 dbg("resolving ifuncs");
676 if (resolve_objects_ifunc(obj_main,
677 ld_bind_now != NULL && *ld_bind_now != '\0', NULL) == -1)
681 * Do NOT call the initlist here, give libc a chance to set up
682 * the initial TLS segment. crt1 will then call _rtld_call_init().
685 dbg("transferring control to program entry point = %p", obj_main->entry);
687 /* Return the exit procedure and the program entry point. */
688 *exit_proc = rtld_exit;
690 return (func_ptr_type) obj_main->entry;
694 * Call the initialization list for dynamically loaded libraries.
695 * (called from crt1.c).
698 _rtld_call_init(void)
700 RtldLockState lockstate;
703 preinitialize_main_object();
704 wlock_acquire(rtld_bind_lock, &lockstate);
705 objlist_call_init(&initlist, &lockstate);
706 objlist_clear(&initlist);
707 dbg("loading filtees");
708 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
709 if (ld_loadfltr || obj->z_loadfltr)
710 load_filtees(obj, 0, &lockstate);
712 lock_release(rtld_bind_lock, &lockstate);
716 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
721 ptr = (void *)make_function_pointer(def, obj);
722 target = ((Elf_Addr (*)(void))ptr)();
723 return ((void *)target);
727 _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack)
731 const Obj_Entry *defobj;
734 RtldLockState lockstate;
736 rlock_acquire(rtld_bind_lock, &lockstate);
737 if (sigsetjmp(lockstate.env, 0) != 0)
738 lock_upgrade(rtld_bind_lock, &lockstate);
740 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
742 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
744 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
745 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
749 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
750 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
752 target = (Elf_Addr)(defobj->relocbase + def->st_value);
754 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
755 defobj->strtab + def->st_name, basename(obj->path),
756 (void *)target, basename(defobj->path));
759 * If we have a function call tracing hook, and the
760 * hook would like to keep tracing this one function,
761 * prevent the relocation so we will wind up here
762 * the next time again.
764 * We don't want to functrace calls from the functracer
765 * to avoid recursive loops.
767 if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
768 if (rtld_functrace(obj->path,
770 defobj->strtab + def->st_name,
772 lock_release(rtld_bind_lock, &lockstate);
777 * Write the new contents for the jmpslot. Note that depending on
778 * architecture, the value which we need to return back to the
779 * lazy binding trampoline may or may not be the target
780 * address. The value returned from reloc_jmpslot() is the value
781 * that the trampoline needs.
783 target = reloc_jmpslot(where, target, defobj, obj, rel);
784 lock_release(rtld_bind_lock, &lockstate);
789 * Error reporting function. Use it like printf. If formats the message
790 * into a buffer, and sets things up so that the next call to dlerror()
791 * will return the message.
794 _rtld_error(const char *fmt, ...)
796 static char buf[512];
800 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
806 * Return a dynamically-allocated copy of the current error message, if any.
811 return error_message == NULL ? NULL : xstrdup(error_message);
815 * Restore the current error message from a copy which was previously saved
816 * by errmsg_save(). The copy is freed.
819 errmsg_restore(char *saved_msg)
821 if (saved_msg == NULL)
822 error_message = NULL;
824 _rtld_error("%s", saved_msg);
830 basename(const char *name)
832 const char *p = strrchr(name, '/');
833 return p != NULL ? p + 1 : name;
836 static struct utsname uts;
839 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
849 subst_len = kw_len = 0;
853 if (subst_len == 0) {
854 subst_len = strlen(subst);
858 *res = xmalloc(PATH_MAX);
861 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
862 _rtld_error("Substitution of %s in %s cannot be performed",
864 if (may_free != NULL)
869 memcpy(res1, p, p1 - p);
871 memcpy(res1, subst, subst_len);
876 if (may_free != NULL)
879 *res = xstrdup(real);
883 if (may_free != NULL)
885 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
895 origin_subst(const char *real, const char *origin_path)
897 char *res1, *res2, *res3, *res4;
899 if (uts.sysname[0] == '\0') {
900 if (uname(&uts) != 0) {
901 _rtld_error("utsname failed: %d", errno);
905 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
906 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
907 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
908 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
916 const char *msg = dlerror();
920 rtld_fdputstr(STDERR_FILENO, msg);
921 rtld_fdputchar(STDERR_FILENO, '\n');
926 * Process a shared object's DYNAMIC section, and save the important
927 * information in its Obj_Entry structure.
930 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
931 const Elf_Dyn **dyn_soname)
934 Needed_Entry **needed_tail = &obj->needed;
935 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
936 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
937 int plttype = DT_REL;
942 obj->bind_now = false;
943 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
944 switch (dynp->d_tag) {
947 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
951 obj->relsize = dynp->d_un.d_val;
955 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
959 obj->pltrel = (const Elf_Rel *)
960 (obj->relocbase + dynp->d_un.d_ptr);
964 obj->pltrelsize = dynp->d_un.d_val;
968 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
972 obj->relasize = dynp->d_un.d_val;
976 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
980 plttype = dynp->d_un.d_val;
981 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
985 obj->symtab = (const Elf_Sym *)
986 (obj->relocbase + dynp->d_un.d_ptr);
990 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
994 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
998 obj->strsize = dynp->d_un.d_val;
1002 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1007 obj->verneednum = dynp->d_un.d_val;
1011 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1016 obj->verdefnum = dynp->d_un.d_val;
1020 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1026 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1027 (obj->relocbase + dynp->d_un.d_ptr);
1028 obj->nbuckets = hashtab[0];
1029 obj->nchains = hashtab[1];
1030 obj->buckets = hashtab + 2;
1031 obj->chains = obj->buckets + obj->nbuckets;
1037 Needed_Entry *nep = NEW(Needed_Entry);
1038 nep->name = dynp->d_un.d_val;
1043 needed_tail = &nep->next;
1049 Needed_Entry *nep = NEW(Needed_Entry);
1050 nep->name = dynp->d_un.d_val;
1054 *needed_filtees_tail = nep;
1055 needed_filtees_tail = &nep->next;
1061 Needed_Entry *nep = NEW(Needed_Entry);
1062 nep->name = dynp->d_un.d_val;
1066 *needed_aux_filtees_tail = nep;
1067 needed_aux_filtees_tail = &nep->next;
1072 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1076 obj->textrel = true;
1080 obj->symbolic = true;
1084 case DT_RUNPATH: /* XXX: process separately */
1086 * We have to wait until later to process this, because we
1087 * might not have gotten the address of the string table yet.
1097 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1101 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1104 case DT_PREINIT_ARRAY:
1105 obj->preinit_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1109 obj->init_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1113 obj->fini_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1116 case DT_PREINIT_ARRAYSZ:
1117 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1120 case DT_INIT_ARRAYSZ:
1121 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1124 case DT_FINI_ARRAYSZ:
1125 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1129 /* XXX - not implemented yet */
1131 dbg("Filling in DT_DEBUG entry");
1132 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1136 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1137 obj->z_origin = true;
1138 if (dynp->d_un.d_val & DF_SYMBOLIC)
1139 obj->symbolic = true;
1140 if (dynp->d_un.d_val & DF_TEXTREL)
1141 obj->textrel = true;
1142 if (dynp->d_un.d_val & DF_BIND_NOW)
1143 obj->bind_now = true;
1144 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1149 if (dynp->d_un.d_val & DF_1_NOOPEN)
1150 obj->z_noopen = true;
1151 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1152 obj->z_origin = true;
1153 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1155 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1156 obj->bind_now = true;
1157 if (dynp->d_un.d_val & DF_1_NODELETE)
1158 obj->z_nodelete = true;
1159 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1160 obj->z_loadfltr = true;
1165 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1172 obj->traced = false;
1174 if (plttype == DT_RELA) {
1175 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1177 obj->pltrelasize = obj->pltrelsize;
1178 obj->pltrelsize = 0;
1183 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1184 const Elf_Dyn *dyn_soname)
1187 if (obj->z_origin && obj->origin_path == NULL) {
1188 obj->origin_path = xmalloc(PATH_MAX);
1189 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1193 if (dyn_rpath != NULL) {
1194 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1196 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1199 if (dyn_soname != NULL)
1200 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1204 digest_dynamic(Obj_Entry *obj, int early)
1206 const Elf_Dyn *dyn_rpath;
1207 const Elf_Dyn *dyn_soname;
1209 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname);
1210 digest_dynamic2(obj, dyn_rpath, dyn_soname);
1214 * Process a shared object's program header. This is used only for the
1215 * main program, when the kernel has already loaded the main program
1216 * into memory before calling the dynamic linker. It creates and
1217 * returns an Obj_Entry structure.
1220 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1223 const Elf_Phdr *phlimit = phdr + phnum;
1228 for (ph = phdr; ph < phlimit; ph++) {
1229 if (ph->p_type != PT_PHDR)
1233 obj->phsize = ph->p_memsz;
1234 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1238 obj->stack_flags = PF_X | PF_R | PF_W;
1240 for (ph = phdr; ph < phlimit; ph++) {
1241 switch (ph->p_type) {
1244 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1248 if (nsegs == 0) { /* First load segment */
1249 obj->vaddrbase = trunc_page(ph->p_vaddr);
1250 obj->mapbase = obj->vaddrbase + obj->relocbase;
1251 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1253 } else { /* Last load segment */
1254 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1261 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1266 obj->tlssize = ph->p_memsz;
1267 obj->tlsalign = ph->p_align;
1268 obj->tlsinitsize = ph->p_filesz;
1269 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1273 obj->stack_flags = ph->p_flags;
1277 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1278 obj->relro_size = round_page(ph->p_memsz);
1283 _rtld_error("%s: too few PT_LOAD segments", path);
1292 dlcheck(void *handle)
1296 for (obj = obj_list; obj != NULL; obj = obj->next)
1297 if (obj == (Obj_Entry *) handle)
1300 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1301 _rtld_error("Invalid shared object handle %p", handle);
1308 * If the given object is already in the donelist, return true. Otherwise
1309 * add the object to the list and return false.
1312 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1316 for (i = 0; i < dlp->num_used; i++)
1317 if (dlp->objs[i] == obj)
1320 * Our donelist allocation should always be sufficient. But if
1321 * our threads locking isn't working properly, more shared objects
1322 * could have been loaded since we allocated the list. That should
1323 * never happen, but we'll handle it properly just in case it does.
1325 if (dlp->num_used < dlp->num_alloc)
1326 dlp->objs[dlp->num_used++] = obj;
1331 * Hash function for symbol table lookup. Don't even think about changing
1332 * this. It is specified by the System V ABI.
1335 elf_hash(const char *name)
1337 const unsigned char *p = (const unsigned char *) name;
1338 unsigned long h = 0;
1341 while (*p != '\0') {
1342 h = (h << 4) + *p++;
1343 if ((g = h & 0xf0000000) != 0)
1351 * Find the library with the given name, and return its full pathname.
1352 * The returned string is dynamically allocated. Generates an error
1353 * message and returns NULL if the library cannot be found.
1355 * If the second argument is non-NULL, then it refers to an already-
1356 * loaded shared object, whose library search path will be searched.
1358 * The search order is:
1360 * rpath in the referencing file
1365 find_library(const char *xname, const Obj_Entry *refobj)
1370 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1371 if (xname[0] != '/' && !trust) {
1372 _rtld_error("Absolute pathname required for shared object \"%s\"",
1376 if (refobj != NULL && refobj->z_origin)
1377 return origin_subst(xname, refobj->origin_path);
1379 return xstrdup(xname);
1382 if (libmap_disable || (refobj == NULL) ||
1383 (name = lm_find(refobj->path, xname)) == NULL)
1384 name = (char *)xname;
1386 dbg(" Searching for \"%s\"", name);
1388 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1390 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1391 (pathname = search_library_path(name, gethints())) != NULL ||
1392 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1395 if(refobj != NULL && refobj->path != NULL) {
1396 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1397 name, basename(refobj->path));
1399 _rtld_error("Shared object \"%s\" not found", name);
1405 * Given a symbol number in a referencing object, find the corresponding
1406 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1407 * no definition was found. Returns a pointer to the Obj_Entry of the
1408 * defining object via the reference parameter DEFOBJ_OUT.
1411 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1412 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1413 RtldLockState *lockstate)
1417 const Obj_Entry *defobj;
1423 * If we have already found this symbol, get the information from
1426 if (symnum >= refobj->nchains)
1427 return NULL; /* Bad object */
1428 if (cache != NULL && cache[symnum].sym != NULL) {
1429 *defobj_out = cache[symnum].obj;
1430 return cache[symnum].sym;
1433 ref = refobj->symtab + symnum;
1434 name = refobj->strtab + ref->st_name;
1439 * We don't have to do a full scale lookup if the symbol is local.
1440 * We know it will bind to the instance in this load module; to
1441 * which we already have a pointer (ie ref). By not doing a lookup,
1442 * we not only improve performance, but it also avoids unresolvable
1443 * symbols when local symbols are not in the hash table.
1445 * This might occur for TLS module relocations, which simply use
1448 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1449 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1450 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1453 symlook_init(&req, name);
1455 req.ventry = fetch_ventry(refobj, symnum);
1456 req.lockstate = lockstate;
1457 res = symlook_default(&req, refobj);
1460 defobj = req.defobj_out;
1468 * If we found no definition and the reference is weak, treat the
1469 * symbol as having the value zero.
1471 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1477 *defobj_out = defobj;
1478 /* Record the information in the cache to avoid subsequent lookups. */
1479 if (cache != NULL) {
1480 cache[symnum].sym = def;
1481 cache[symnum].obj = defobj;
1484 if (refobj != &obj_rtld)
1485 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1491 * Return the search path from the ldconfig hints file, reading it if
1492 * necessary. Returns NULL if there are problems with the hints file,
1493 * or if the search path there is empty.
1500 if (hints == NULL) {
1502 struct elfhints_hdr hdr;
1505 /* Keep from trying again in case the hints file is bad. */
1508 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1510 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1511 hdr.magic != ELFHINTS_MAGIC ||
1516 p = xmalloc(hdr.dirlistlen + 1);
1517 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1518 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1526 return hints[0] != '\0' ? hints : NULL;
1530 init_dag(Obj_Entry *root)
1532 const Needed_Entry *needed;
1533 const Objlist_Entry *elm;
1536 if (root->dag_inited)
1538 donelist_init(&donelist);
1540 /* Root object belongs to own DAG. */
1541 objlist_push_tail(&root->dldags, root);
1542 objlist_push_tail(&root->dagmembers, root);
1543 donelist_check(&donelist, root);
1546 * Add dependencies of root object to DAG in breadth order
1547 * by exploiting the fact that each new object get added
1548 * to the tail of the dagmembers list.
1550 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1551 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1552 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1554 objlist_push_tail(&needed->obj->dldags, root);
1555 objlist_push_tail(&root->dagmembers, needed->obj);
1558 root->dag_inited = true;
1562 * Initialize the dynamic linker. The argument is the address at which
1563 * the dynamic linker has been mapped into memory. The primary task of
1564 * this function is to relocate the dynamic linker.
1567 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1569 Obj_Entry objtmp; /* Temporary rtld object */
1570 const Elf_Dyn *dyn_rpath;
1571 const Elf_Dyn *dyn_soname;
1574 * Conjure up an Obj_Entry structure for the dynamic linker.
1576 * The "path" member can't be initialized yet because string constants
1577 * cannot yet be accessed. Below we will set it correctly.
1579 memset(&objtmp, 0, sizeof(objtmp));
1582 objtmp.mapbase = mapbase;
1584 objtmp.relocbase = mapbase;
1586 if (RTLD_IS_DYNAMIC()) {
1587 objtmp.dynamic = rtld_dynamic(&objtmp);
1588 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname);
1589 assert(objtmp.needed == NULL);
1590 assert(!objtmp.textrel);
1593 * Temporarily put the dynamic linker entry into the object list, so
1594 * that symbols can be found.
1597 relocate_objects(&objtmp, true, &objtmp, NULL);
1600 /* Initialize the object list. */
1601 obj_tail = &obj_list;
1603 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1604 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1606 #ifdef ENABLE_OSRELDATE
1607 if (aux_info[AT_OSRELDATE] != NULL)
1608 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1611 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname);
1613 /* Replace the path with a dynamically allocated copy. */
1614 obj_rtld.path = xstrdup(PATH_RTLD);
1616 r_debug.r_brk = r_debug_state;
1617 r_debug.r_state = RT_CONSISTENT;
1621 * Add the init functions from a needed object list (and its recursive
1622 * needed objects) to "list". This is not used directly; it is a helper
1623 * function for initlist_add_objects(). The write lock must be held
1624 * when this function is called.
1627 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1629 /* Recursively process the successor needed objects. */
1630 if (needed->next != NULL)
1631 initlist_add_neededs(needed->next, list);
1633 /* Process the current needed object. */
1634 if (needed->obj != NULL)
1635 initlist_add_objects(needed->obj, &needed->obj->next, list);
1639 * Scan all of the DAGs rooted in the range of objects from "obj" to
1640 * "tail" and add their init functions to "list". This recurses over
1641 * the DAGs and ensure the proper init ordering such that each object's
1642 * needed libraries are initialized before the object itself. At the
1643 * same time, this function adds the objects to the global finalization
1644 * list "list_fini" in the opposite order. The write lock must be
1645 * held when this function is called.
1648 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1650 if (obj->init_scanned || obj->init_done)
1652 obj->init_scanned = true;
1654 /* Recursively process the successor objects. */
1655 if (&obj->next != tail)
1656 initlist_add_objects(obj->next, tail, list);
1658 /* Recursively process the needed objects. */
1659 if (obj->needed != NULL)
1660 initlist_add_neededs(obj->needed, list);
1662 /* Add the object to the init list. */
1663 if (obj->init != (Elf_Addr)NULL || obj->init_array != (Elf_Addr)NULL)
1664 objlist_push_tail(list, obj);
1666 /* Add the object to the global fini list in the reverse order. */
1667 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1668 && !obj->on_fini_list) {
1669 objlist_push_head(&list_fini, obj);
1670 obj->on_fini_list = true;
1675 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1679 is_exported(const Elf_Sym *def)
1682 const func_ptr_type *p;
1684 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1685 for (p = exports; *p != NULL; p++)
1686 if (FPTR_TARGET(*p) == value)
1692 free_needed_filtees(Needed_Entry *n)
1694 Needed_Entry *needed, *needed1;
1696 for (needed = n; needed != NULL; needed = needed->next) {
1697 if (needed->obj != NULL) {
1698 dlclose(needed->obj);
1702 for (needed = n; needed != NULL; needed = needed1) {
1703 needed1 = needed->next;
1709 unload_filtees(Obj_Entry *obj)
1712 free_needed_filtees(obj->needed_filtees);
1713 obj->needed_filtees = NULL;
1714 free_needed_filtees(obj->needed_aux_filtees);
1715 obj->needed_aux_filtees = NULL;
1716 obj->filtees_loaded = false;
1720 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags)
1723 for (; needed != NULL; needed = needed->next) {
1724 needed->obj = dlopen_object(obj->strtab + needed->name, obj,
1725 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
1731 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
1734 lock_restart_for_upgrade(lockstate);
1735 if (!obj->filtees_loaded) {
1736 load_filtee1(obj, obj->needed_filtees, flags);
1737 load_filtee1(obj, obj->needed_aux_filtees, flags);
1738 obj->filtees_loaded = true;
1743 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
1747 for (; needed != NULL; needed = needed->next) {
1748 obj1 = needed->obj = load_object(obj->strtab + needed->name, obj,
1749 flags & ~RTLD_LO_NOLOAD);
1750 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
1752 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1753 dbg("obj %s nodelete", obj1->path);
1756 obj1->ref_nodel = true;
1763 * Given a shared object, traverse its list of needed objects, and load
1764 * each of them. Returns 0 on success. Generates an error message and
1765 * returns -1 on failure.
1768 load_needed_objects(Obj_Entry *first, int flags)
1772 for (obj = first; obj != NULL; obj = obj->next) {
1773 if (process_needed(obj, obj->needed, flags) == -1)
1780 load_preload_objects(void)
1782 char *p = ld_preload;
1783 static const char delim[] = " \t:;";
1788 p += strspn(p, delim);
1789 while (*p != '\0') {
1790 size_t len = strcspn(p, delim);
1798 obj = load_object(p, NULL, 0);
1800 return -1; /* XXX - cleanup */
1803 p += strspn(p, delim);
1805 /* Check for the magic tracing function */
1806 symlook_init(&req, RTLD_FUNCTRACE);
1807 res = symlook_obj(&req, obj);
1809 rtld_functrace = (void *)(req.defobj_out->relocbase +
1810 req.sym_out->st_value);
1811 rtld_functrace_obj = req.defobj_out;
1814 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
1819 * Load a shared object into memory, if it is not already loaded.
1821 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1825 load_object(const char *name, const Obj_Entry *refobj, int flags)
1832 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1833 if (object_match_name(obj, name))
1836 path = find_library(name, refobj);
1841 * If we didn't find a match by pathname, open the file and check
1842 * again by device and inode. This avoids false mismatches caused
1843 * by multiple links or ".." in pathnames.
1845 * To avoid a race, we open the file and use fstat() rather than
1848 if ((fd = open(path, O_RDONLY)) == -1) {
1849 _rtld_error("Cannot open \"%s\"", path);
1853 if (fstat(fd, &sb) == -1) {
1854 _rtld_error("Cannot fstat \"%s\"", path);
1859 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1860 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
1863 object_add_name(obj, name);
1868 if (flags & RTLD_LO_NOLOAD) {
1874 /* First use of this object, so we must map it in */
1875 obj = do_load_object(fd, name, path, &sb, flags);
1884 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
1891 * but first, make sure that environment variables haven't been
1892 * used to circumvent the noexec flag on a filesystem.
1894 if (dangerous_ld_env) {
1895 if (fstatfs(fd, &fs) != 0) {
1896 _rtld_error("Cannot fstatfs \"%s\"", path);
1899 if (fs.f_flags & MNT_NOEXEC) {
1900 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
1904 dbg("loading \"%s\"", path);
1905 obj = map_object(fd, path, sbp);
1909 object_add_name(obj, name);
1911 digest_dynamic(obj, 0);
1912 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
1914 dbg("refusing to load non-loadable \"%s\"", obj->path);
1915 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
1916 munmap(obj->mapbase, obj->mapsize);
1922 obj_tail = &obj->next;
1925 linkmap_add(obj); /* for GDB & dlinfo() */
1926 max_stack_flags |= obj->stack_flags;
1928 dbg(" %p .. %p: %s", obj->mapbase,
1929 obj->mapbase + obj->mapsize - 1, obj->path);
1931 dbg(" WARNING: %s has impure text", obj->path);
1932 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
1939 obj_from_addr(const void *addr)
1943 for (obj = obj_list; obj != NULL; obj = obj->next) {
1944 if (addr < (void *) obj->mapbase)
1946 if (addr < (void *) (obj->mapbase + obj->mapsize))
1953 * Call the finalization functions for each of the objects in "list"
1954 * belonging to the DAG of "root" and referenced once. If NULL "root"
1955 * is specified, every finalization function will be called regardless
1956 * of the reference count and the list elements won't be freed. All of
1957 * the objects are expected to have non-NULL fini functions.
1960 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
1964 Elf_Addr *fini_addr;
1967 assert(root == NULL || root->refcount == 1);
1970 * Preserve the current error message since a fini function might
1971 * call into the dynamic linker and overwrite it.
1973 saved_msg = errmsg_save();
1975 STAILQ_FOREACH(elm, list, link) {
1976 if (root != NULL && (elm->obj->refcount != 1 ||
1977 objlist_find(&root->dagmembers, elm->obj) == NULL))
1980 /* Remove object from fini list to prevent recursive invocation. */
1981 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1983 * XXX: If a dlopen() call references an object while the
1984 * fini function is in progress, we might end up trying to
1985 * unload the referenced object in dlclose() or the object
1986 * won't be unloaded although its fini function has been
1989 lock_release(rtld_bind_lock, lockstate);
1992 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. When this
1993 * happens, DT_FINI_ARRAY is processed first, and it is also processed
1994 * backwards. It is possible to encounter DT_FINI_ARRAY elements with
1995 * values of 0 or 1, but they need to be ignored.
1997 fini_addr = (Elf_Addr *)elm->obj->fini_array;
1998 if (fini_addr != (Elf_Addr)NULL) {
1999 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
2000 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2001 dbg("DSO Array: calling fini function for %s at %p",
2002 elm->obj->path, (void *)fini_addr[index]);
2003 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2004 (void *)fini_addr[index], 0, 0, elm->obj->path);
2005 call_initfini_pointer(elm->obj, fini_addr[index]);
2009 if (elm->obj->fini != (Elf_Addr)NULL) {
2010 dbg("DSO: calling fini function for %s at %p", elm->obj->path,
2011 (void *)elm->obj->fini);
2012 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2013 0, 0, elm->obj->path);
2014 call_initfini_pointer(elm->obj, elm->obj->fini);
2016 wlock_acquire(rtld_bind_lock, lockstate);
2017 /* No need to free anything if process is going down. */
2021 * We must restart the list traversal after every fini call
2022 * because a dlclose() call from the fini function or from
2023 * another thread might have modified the reference counts.
2027 } while (elm != NULL);
2028 errmsg_restore(saved_msg);
2032 * If the main program is defined with a .preinit_array section, call
2033 * each function in order. This must occur before the initialization
2034 * of any shared object or the main program.
2037 preinitialize_main_object (void)
2039 Elf_Addr *init_addr;
2042 init_addr = (Elf_Addr *)obj_main->preinit_array;
2043 if (init_addr == (Elf_Addr)NULL)
2046 for (index = 0; index < obj_main->preinit_array_num; index++)
2047 if (init_addr[index] != 0 && init_addr[index] != 1) {
2048 dbg("Calling preinit array function for %s at %p",
2049 (void *) obj_main->path, (void *)init_addr[index]);
2050 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)init_addr[index],
2051 0, 0, obj_main->path);
2052 call_array_pointer(init_addr[index], glac, glav, environ);
2057 * Call the initialization functions for each of the objects in
2058 * "list". All of the objects are expected to have non-NULL init
2062 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2067 Elf_Addr *init_addr;
2071 * Clean init_scanned flag so that objects can be rechecked and
2072 * possibly initialized earlier if any of vectors called below
2073 * cause the change by using dlopen.
2075 for (obj = obj_list; obj != NULL; obj = obj->next)
2076 obj->init_scanned = false;
2079 * Preserve the current error message since an init function might
2080 * call into the dynamic linker and overwrite it.
2082 saved_msg = errmsg_save();
2083 STAILQ_FOREACH(elm, list, link) {
2084 if (elm->obj->init_done) /* Initialized early. */
2088 * Race: other thread might try to use this object before current
2089 * one completes the initilization. Not much can be done here
2090 * without better locking.
2092 elm->obj->init_done = true;
2093 lock_release(rtld_bind_lock, lockstate);
2096 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. When
2097 * this happens, DT_INIT is processed first. It is possible to
2098 * encounter DT_INIT_ARRAY elements with values of 0 or 1, but they
2099 * need to be ignored.
2101 if (elm->obj->init != (Elf_Addr)NULL) {
2102 dbg("DSO: calling init function for %s at %p", elm->obj->path,
2103 (void *)elm->obj->init);
2104 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2105 0, 0, elm->obj->path);
2106 call_initfini_pointer(elm->obj, elm->obj->init);
2108 init_addr = (Elf_Addr *)elm->obj->init_array;
2109 if (init_addr != (Elf_Addr)NULL) {
2110 for (index = 0; index < elm->obj->init_array_num; index++)
2111 if (init_addr[index] != 0 && init_addr[index] != 1) {
2112 dbg("DSO Array: calling init function for %s at %p",
2113 elm->obj->path, (void *)init_addr[index]);
2114 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2115 (void *)init_addr[index], 0, 0, elm->obj->path);
2116 call_array_pointer(init_addr[index], glac, glav, environ);
2119 wlock_acquire(rtld_bind_lock, lockstate);
2121 errmsg_restore(saved_msg);
2125 objlist_clear(Objlist *list)
2129 while (!STAILQ_EMPTY(list)) {
2130 elm = STAILQ_FIRST(list);
2131 STAILQ_REMOVE_HEAD(list, link);
2136 static Objlist_Entry *
2137 objlist_find(Objlist *list, const Obj_Entry *obj)
2141 STAILQ_FOREACH(elm, list, link)
2142 if (elm->obj == obj)
2148 objlist_init(Objlist *list)
2154 objlist_push_head(Objlist *list, Obj_Entry *obj)
2158 elm = NEW(Objlist_Entry);
2160 STAILQ_INSERT_HEAD(list, elm, link);
2164 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2168 elm = NEW(Objlist_Entry);
2170 STAILQ_INSERT_TAIL(list, elm, link);
2174 objlist_remove(Objlist *list, Obj_Entry *obj)
2178 if ((elm = objlist_find(list, obj)) != NULL) {
2179 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2185 * Relocate newly-loaded shared objects. The argument is a pointer to
2186 * the Obj_Entry for the first such object. All objects from the first
2187 * to the end of the list of objects are relocated. Returns 0 on success,
2191 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2192 RtldLockState *lockstate)
2196 for (obj = first; obj != NULL; obj = obj->next) {
2198 dbg("relocating \"%s\"", obj->path);
2199 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
2200 obj->symtab == NULL || obj->strtab == NULL) {
2201 _rtld_error("%s: Shared object has no run-time symbol table",
2207 /* There are relocations to the write-protected text segment. */
2208 if (mprotect(obj->mapbase, obj->textsize,
2209 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2210 _rtld_error("%s: Cannot write-enable text segment: %s",
2211 obj->path, strerror(errno));
2216 /* Process the non-PLT relocations. */
2217 if (reloc_non_plt(obj, rtldobj, lockstate))
2221 * Reprotect the text segment. Make sure it is included in the
2222 * core dump since we modified it. This unfortunately causes the
2223 * entire text segment to core-out but we don't have much of a
2224 * choice. We could try to only reenable core dumps on pages
2225 * in which relocations occured but that is likely most of the text
2226 * pages anyway, and even that would not work because the rest of
2227 * the text pages would wind up as a read-only OBJT_DEFAULT object
2228 * (created due to our modifications) backed by the original OBJT_VNODE
2229 * object, and the ELF coredump code is currently only able to dump
2230 * vnode records for pure vnode-backed mappings, not vnode backings
2231 * to memory objects.
2234 madvise(obj->mapbase, obj->textsize, MADV_CORE);
2235 if (mprotect(obj->mapbase, obj->textsize,
2236 PROT_READ|PROT_EXEC) == -1) {
2237 _rtld_error("%s: Cannot write-protect text segment: %s",
2238 obj->path, strerror(errno));
2244 /* Set the special PLT or GOT entries. */
2247 /* Process the PLT relocations. */
2248 if (reloc_plt(obj) == -1)
2250 /* Relocate the jump slots if we are doing immediate binding. */
2251 if (obj->bind_now || bind_now)
2252 if (reloc_jmpslots(obj, lockstate) == -1)
2256 * Set up the magic number and version in the Obj_Entry. These
2257 * were checked in the crt1.o from the original ElfKit, so we
2258 * set them for backward compatibility.
2260 obj->magic = RTLD_MAGIC;
2261 obj->version = RTLD_VERSION;
2264 * Set relocated data to read-only status if protection specified
2267 if (obj->relro_size) {
2268 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
2269 _rtld_error("%s: Cannot enforce relro relocation: %s",
2270 obj->path, strerror(errno));
2280 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2281 * referencing STT_GNU_IFUNC symbols is postponed till the other
2282 * relocations are done. The indirect functions specified as
2283 * ifunc are allowed to call other symbols, so we need to have
2284 * objects relocated before asking for resolution from indirects.
2286 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2287 * instead of the usual lazy handling of PLT slots. It is
2288 * consistent with how GNU does it.
2291 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, RtldLockState *lockstate)
2293 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2295 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2296 reloc_gnu_ifunc(obj, lockstate) == -1)
2302 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, RtldLockState *lockstate)
2306 for (obj = first; obj != NULL; obj = obj->next) {
2307 if (resolve_object_ifunc(obj, bind_now, lockstate) == -1)
2314 initlist_objects_ifunc(Objlist *list, bool bind_now, RtldLockState *lockstate)
2318 STAILQ_FOREACH(elm, list, link) {
2319 if (resolve_object_ifunc(elm->obj, bind_now, lockstate) == -1)
2326 * Cleanup procedure. It will be called (by the atexit mechanism) just
2327 * before the process exits.
2332 RtldLockState lockstate;
2334 wlock_acquire(rtld_bind_lock, &lockstate);
2336 objlist_call_fini(&list_fini, NULL, &lockstate);
2337 /* No need to remove the items from the list, since we are exiting. */
2338 if (!libmap_disable)
2340 lock_release(rtld_bind_lock, &lockstate);
2344 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2349 path += strspn(path, ":;");
2350 while (*path != '\0') {
2354 len = strcspn(path, ":;");
2355 res = callback(path, len, arg);
2361 path += strspn(path, ":;");
2367 struct try_library_args {
2375 try_library_path(const char *dir, size_t dirlen, void *param)
2377 struct try_library_args *arg;
2380 if (*dir == '/' || trust) {
2383 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2386 pathname = arg->buffer;
2387 strncpy(pathname, dir, dirlen);
2388 pathname[dirlen] = '/';
2389 strcpy(pathname + dirlen + 1, arg->name);
2391 dbg(" Trying \"%s\"", pathname);
2392 if (access(pathname, F_OK) == 0) { /* We found it */
2393 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2394 strcpy(pathname, arg->buffer);
2402 search_library_path(const char *name, const char *path)
2405 struct try_library_args arg;
2411 arg.namelen = strlen(name);
2412 arg.buffer = xmalloc(PATH_MAX);
2413 arg.buflen = PATH_MAX;
2415 p = path_enumerate(path, try_library_path, &arg);
2423 dlclose(void *handle)
2426 RtldLockState lockstate;
2428 wlock_acquire(rtld_bind_lock, &lockstate);
2429 root = dlcheck(handle);
2431 lock_release(rtld_bind_lock, &lockstate);
2434 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2437 /* Unreference the object and its dependencies. */
2438 root->dl_refcount--;
2440 if (root->refcount == 1) {
2442 * The object will be no longer referenced, so we must unload it.
2443 * First, call the fini functions.
2445 objlist_call_fini(&list_fini, root, &lockstate);
2449 /* Finish cleaning up the newly-unreferenced objects. */
2450 GDB_STATE(RT_DELETE,&root->linkmap);
2451 unload_object(root);
2452 GDB_STATE(RT_CONSISTENT,NULL);
2456 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2457 lock_release(rtld_bind_lock, &lockstate);
2464 char *msg = error_message;
2465 error_message = NULL;
2470 dlopen(const char *name, int mode)
2472 RtldLockState lockstate;
2475 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2476 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2477 if (ld_tracing != NULL) {
2478 rlock_acquire(rtld_bind_lock, &lockstate);
2479 if (sigsetjmp(lockstate.env, 0) != 0)
2480 lock_upgrade(rtld_bind_lock, &lockstate);
2481 environ = (char **)*get_program_var_addr("environ", &lockstate);
2482 lock_release(rtld_bind_lock, &lockstate);
2484 lo_flags = RTLD_LO_DLOPEN;
2485 if (mode & RTLD_NODELETE)
2486 lo_flags |= RTLD_LO_NODELETE;
2487 if (mode & RTLD_NOLOAD)
2488 lo_flags |= RTLD_LO_NOLOAD;
2489 if (ld_tracing != NULL)
2490 lo_flags |= RTLD_LO_TRACE;
2492 return (dlopen_object(name, obj_main, lo_flags,
2493 mode & (RTLD_MODEMASK | RTLD_GLOBAL)));
2497 dlopen_cleanup(Obj_Entry *obj)
2502 if (obj->refcount == 0)
2507 dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode)
2509 Obj_Entry **old_obj_tail;
2512 RtldLockState lockstate;
2515 objlist_init(&initlist);
2517 wlock_acquire(rtld_bind_lock, &lockstate);
2518 GDB_STATE(RT_ADD,NULL);
2520 old_obj_tail = obj_tail;
2526 obj = load_object(name, refobj, lo_flags);
2531 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2532 objlist_push_tail(&list_global, obj);
2533 if (*old_obj_tail != NULL) { /* We loaded something new. */
2534 assert(*old_obj_tail == obj);
2535 result = load_needed_objects(obj, lo_flags & RTLD_LO_DLOPEN);
2539 result = rtld_verify_versions(&obj->dagmembers);
2540 if (result != -1 && ld_tracing)
2542 if (result == -1 || (relocate_objects(obj, (mode & RTLD_MODEMASK)
2543 == RTLD_NOW, &obj_rtld, &lockstate)) == -1) {
2544 dlopen_cleanup(obj);
2547 /* Make list of init functions to call. */
2548 initlist_add_objects(obj, &obj->next, &initlist);
2553 * Bump the reference counts for objects on this DAG. If
2554 * this is the first dlopen() call for the object that was
2555 * already loaded as a dependency, initialize the dag
2561 if ((lo_flags & RTLD_LO_TRACE) != 0)
2564 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
2565 obj->z_nodelete) && !obj->ref_nodel) {
2566 dbg("obj %s nodelete", obj->path);
2568 obj->z_nodelete = obj->ref_nodel = true;
2572 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2574 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2576 map_stacks_exec(&lockstate);
2578 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
2579 &lockstate) == -1) {
2580 objlist_clear(&initlist);
2581 dlopen_cleanup(obj);
2582 lock_release(rtld_bind_lock, &lockstate);
2586 /* Call the init functions. */
2587 objlist_call_init(&initlist, &lockstate);
2588 objlist_clear(&initlist);
2589 lock_release(rtld_bind_lock, &lockstate);
2592 trace_loaded_objects(obj);
2593 lock_release(rtld_bind_lock, &lockstate);
2598 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2602 const Obj_Entry *obj, *defobj;
2605 RtldLockState lockstate;
2610 symlook_init(&req, name);
2612 req.flags = flags | SYMLOOK_IN_PLT;
2613 req.lockstate = &lockstate;
2615 rlock_acquire(rtld_bind_lock, &lockstate);
2616 if (sigsetjmp(lockstate.env, 0) != 0)
2617 lock_upgrade(rtld_bind_lock, &lockstate);
2618 if (handle == NULL || handle == RTLD_NEXT ||
2619 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2621 if ((obj = obj_from_addr(retaddr)) == NULL) {
2622 _rtld_error("Cannot determine caller's shared object");
2623 lock_release(rtld_bind_lock, &lockstate);
2626 if (handle == NULL) { /* Just the caller's shared object. */
2627 res = symlook_obj(&req, obj);
2630 defobj = req.defobj_out;
2632 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2633 handle == RTLD_SELF) { /* ... caller included */
2634 if (handle == RTLD_NEXT)
2636 for (; obj != NULL; obj = obj->next) {
2637 res = symlook_obj(&req, obj);
2640 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
2642 defobj = req.defobj_out;
2643 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2649 * Search the dynamic linker itself, and possibly resolve the
2650 * symbol from there. This is how the application links to
2651 * dynamic linker services such as dlopen.
2653 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2654 res = symlook_obj(&req, &obj_rtld);
2655 if (res == 0 && is_exported(req.sym_out)) {
2657 defobj = req.defobj_out;
2661 assert(handle == RTLD_DEFAULT);
2662 res = symlook_default(&req, obj);
2664 defobj = req.defobj_out;
2669 if ((obj = dlcheck(handle)) == NULL) {
2670 lock_release(rtld_bind_lock, &lockstate);
2674 donelist_init(&donelist);
2675 if (obj->mainprog) {
2676 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
2677 res = symlook_global(&req, &donelist);
2680 defobj = req.defobj_out;
2683 * Search the dynamic linker itself, and possibly resolve the
2684 * symbol from there. This is how the application links to
2685 * dynamic linker services such as dlopen.
2687 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2688 res = symlook_obj(&req, &obj_rtld);
2691 defobj = req.defobj_out;
2696 /* Search the whole DAG rooted at the given object. */
2697 res = symlook_list(&req, &obj->dagmembers, &donelist);
2700 defobj = req.defobj_out;
2706 lock_release(rtld_bind_lock, &lockstate);
2709 * The value required by the caller is derived from the value
2710 * of the symbol. For the ia64 architecture, we need to
2711 * construct a function descriptor which the caller can use to
2712 * call the function with the right 'gp' value. For other
2713 * architectures and for non-functions, the value is simply
2714 * the relocated value of the symbol.
2716 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
2717 return (make_function_pointer(def, defobj));
2718 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
2719 return (rtld_resolve_ifunc(defobj, def));
2720 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
2722 ti.ti_module = defobj->tlsindex;
2723 ti.ti_offset = def->st_value;
2724 return (__tls_get_addr(&ti));
2726 return (defobj->relocbase + def->st_value);
2729 _rtld_error("Undefined symbol \"%s\"", name);
2730 lock_release(rtld_bind_lock, &lockstate);
2735 dlsym(void *handle, const char *name)
2737 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
2742 dlfunc(void *handle, const char *name)
2749 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
2755 dlvsym(void *handle, const char *name, const char *version)
2759 ventry.name = version;
2761 ventry.hash = elf_hash(version);
2763 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
2768 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
2770 const Obj_Entry *obj;
2771 RtldLockState lockstate;
2773 rlock_acquire(rtld_bind_lock, &lockstate);
2774 obj = obj_from_addr(addr);
2776 _rtld_error("No shared object contains address");
2777 lock_release(rtld_bind_lock, &lockstate);
2780 rtld_fill_dl_phdr_info(obj, phdr_info);
2781 lock_release(rtld_bind_lock, &lockstate);
2786 dladdr(const void *addr, Dl_info *info)
2788 const Obj_Entry *obj;
2791 unsigned long symoffset;
2792 RtldLockState lockstate;
2794 rlock_acquire(rtld_bind_lock, &lockstate);
2795 obj = obj_from_addr(addr);
2797 _rtld_error("No shared object contains address");
2798 lock_release(rtld_bind_lock, &lockstate);
2801 info->dli_fname = obj->path;
2802 info->dli_fbase = obj->mapbase;
2803 info->dli_saddr = NULL;
2804 info->dli_sname = NULL;
2807 * Walk the symbol list looking for the symbol whose address is
2808 * closest to the address sent in.
2810 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
2811 def = obj->symtab + symoffset;
2814 * For skip the symbol if st_shndx is either SHN_UNDEF or
2817 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
2821 * If the symbol is greater than the specified address, or if it
2822 * is further away from addr than the current nearest symbol,
2825 symbol_addr = obj->relocbase + def->st_value;
2826 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
2829 /* Update our idea of the nearest symbol. */
2830 info->dli_sname = obj->strtab + def->st_name;
2831 info->dli_saddr = symbol_addr;
2834 if (info->dli_saddr == addr)
2837 lock_release(rtld_bind_lock, &lockstate);
2842 dlinfo(void *handle, int request, void *p)
2844 const Obj_Entry *obj;
2845 RtldLockState lockstate;
2848 rlock_acquire(rtld_bind_lock, &lockstate);
2850 if (handle == NULL || handle == RTLD_SELF) {
2853 retaddr = __builtin_return_address(0); /* __GNUC__ only */
2854 if ((obj = obj_from_addr(retaddr)) == NULL)
2855 _rtld_error("Cannot determine caller's shared object");
2857 obj = dlcheck(handle);
2860 lock_release(rtld_bind_lock, &lockstate);
2866 case RTLD_DI_LINKMAP:
2867 *((struct link_map const **)p) = &obj->linkmap;
2869 case RTLD_DI_ORIGIN:
2870 error = rtld_dirname(obj->path, p);
2873 case RTLD_DI_SERINFOSIZE:
2874 case RTLD_DI_SERINFO:
2875 error = do_search_info(obj, request, (struct dl_serinfo *)p);
2879 _rtld_error("Invalid request %d passed to dlinfo()", request);
2883 lock_release(rtld_bind_lock, &lockstate);
2889 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
2892 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
2893 phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ?
2894 STAILQ_FIRST(&obj->names)->name : obj->path;
2895 phdr_info->dlpi_phdr = obj->phdr;
2896 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
2897 phdr_info->dlpi_tls_modid = obj->tlsindex;
2898 phdr_info->dlpi_tls_data = obj->tlsinit;
2899 phdr_info->dlpi_adds = obj_loads;
2900 phdr_info->dlpi_subs = obj_loads - obj_count;
2904 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
2906 struct dl_phdr_info phdr_info;
2907 const Obj_Entry *obj;
2908 RtldLockState bind_lockstate, phdr_lockstate;
2911 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
2912 rlock_acquire(rtld_bind_lock, &bind_lockstate);
2916 for (obj = obj_list; obj != NULL; obj = obj->next) {
2917 rtld_fill_dl_phdr_info(obj, &phdr_info);
2918 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
2922 lock_release(rtld_bind_lock, &bind_lockstate);
2923 lock_release(rtld_phdr_lock, &phdr_lockstate);
2928 struct fill_search_info_args {
2931 Dl_serinfo *serinfo;
2932 Dl_serpath *serpath;
2937 fill_search_info(const char *dir, size_t dirlen, void *param)
2939 struct fill_search_info_args *arg;
2943 if (arg->request == RTLD_DI_SERINFOSIZE) {
2944 arg->serinfo->dls_cnt ++;
2945 arg->serinfo->dls_size += sizeof(Dl_serpath) + dirlen + 1;
2947 struct dl_serpath *s_entry;
2949 s_entry = arg->serpath;
2950 s_entry->dls_name = arg->strspace;
2951 s_entry->dls_flags = arg->flags;
2953 strncpy(arg->strspace, dir, dirlen);
2954 arg->strspace[dirlen] = '\0';
2956 arg->strspace += dirlen + 1;
2964 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
2966 struct dl_serinfo _info;
2967 struct fill_search_info_args args;
2969 args.request = RTLD_DI_SERINFOSIZE;
2970 args.serinfo = &_info;
2972 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
2975 path_enumerate(ld_library_path, fill_search_info, &args);
2976 path_enumerate(obj->rpath, fill_search_info, &args);
2977 path_enumerate(gethints(), fill_search_info, &args);
2978 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
2981 if (request == RTLD_DI_SERINFOSIZE) {
2982 info->dls_size = _info.dls_size;
2983 info->dls_cnt = _info.dls_cnt;
2987 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
2988 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
2992 args.request = RTLD_DI_SERINFO;
2993 args.serinfo = info;
2994 args.serpath = &info->dls_serpath[0];
2995 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
2997 args.flags = LA_SER_LIBPATH;
2998 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3001 args.flags = LA_SER_RUNPATH;
3002 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3005 args.flags = LA_SER_CONFIG;
3006 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
3009 args.flags = LA_SER_DEFAULT;
3010 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3016 rtld_dirname(const char *path, char *bname)
3020 /* Empty or NULL string gets treated as "." */
3021 if (path == NULL || *path == '\0') {
3027 /* Strip trailing slashes */
3028 endp = path + strlen(path) - 1;
3029 while (endp > path && *endp == '/')
3032 /* Find the start of the dir */
3033 while (endp > path && *endp != '/')
3036 /* Either the dir is "/" or there are no slashes */
3038 bname[0] = *endp == '/' ? '/' : '.';
3044 } while (endp > path && *endp == '/');
3047 if (endp - path + 2 > PATH_MAX)
3049 _rtld_error("Filename is too long: %s", path);
3053 strncpy(bname, path, endp - path + 1);
3054 bname[endp - path + 1] = '\0';
3059 rtld_dirname_abs(const char *path, char *base)
3061 char base_rel[PATH_MAX];
3063 if (rtld_dirname(path, base) == -1)
3067 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
3068 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
3069 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
3071 strcpy(base, base_rel);
3076 linkmap_add(Obj_Entry *obj)
3078 struct link_map *l = &obj->linkmap;
3079 struct link_map *prev;
3081 obj->linkmap.l_name = obj->path;
3082 obj->linkmap.l_addr = obj->mapbase;
3083 obj->linkmap.l_ld = obj->dynamic;
3085 /* GDB needs load offset on MIPS to use the symbols */
3086 obj->linkmap.l_offs = obj->relocbase;
3089 if (r_debug.r_map == NULL) {
3095 * Scan to the end of the list, but not past the entry for the
3096 * dynamic linker, which we want to keep at the very end.
3098 for (prev = r_debug.r_map;
3099 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3100 prev = prev->l_next)
3103 /* Link in the new entry. */
3105 l->l_next = prev->l_next;
3106 if (l->l_next != NULL)
3107 l->l_next->l_prev = l;
3112 linkmap_delete(Obj_Entry *obj)
3114 struct link_map *l = &obj->linkmap;
3116 if (l->l_prev == NULL) {
3117 if ((r_debug.r_map = l->l_next) != NULL)
3118 l->l_next->l_prev = NULL;
3122 if ((l->l_prev->l_next = l->l_next) != NULL)
3123 l->l_next->l_prev = l->l_prev;
3127 * Function for the debugger to set a breakpoint on to gain control.
3129 * The two parameters allow the debugger to easily find and determine
3130 * what the runtime loader is doing and to whom it is doing it.
3132 * When the loadhook trap is hit (r_debug_state, set at program
3133 * initialization), the arguments can be found on the stack:
3135 * +8 struct link_map *m
3136 * +4 struct r_debug *rd
3140 r_debug_state(struct r_debug* rd, struct link_map *m)
3143 * The following is a hack to force the compiler to emit calls to
3144 * this function, even when optimizing. If the function is empty,
3145 * the compiler is not obliged to emit any code for calls to it,
3146 * even when marked __noinline. However, gdb depends on those
3149 __asm __volatile("" : : : "memory");
3153 * Get address of the pointer variable in the main program.
3154 * Prefer non-weak symbol over the weak one.
3156 static const void **
3157 get_program_var_addr(const char *name, RtldLockState *lockstate)
3162 symlook_init(&req, name);
3163 req.lockstate = lockstate;
3164 donelist_init(&donelist);
3165 if (symlook_global(&req, &donelist) != 0)
3167 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3168 return ((const void **)make_function_pointer(req.sym_out,
3170 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3171 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3173 return ((const void **)(req.defobj_out->relocbase +
3174 req.sym_out->st_value));
3178 * Set a pointer variable in the main program to the given value. This
3179 * is used to set key variables such as "environ" before any of the
3180 * init functions are called.
3183 set_program_var(const char *name, const void *value)
3187 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3188 dbg("\"%s\": *%p <-- %p", name, addr, value);
3194 * Search the global objects, including dependencies and main object,
3195 * for the given symbol.
3198 symlook_global(SymLook *req, DoneList *donelist)
3201 const Objlist_Entry *elm;
3204 symlook_init_from_req(&req1, req);
3206 /* Search all objects loaded at program start up. */
3207 if (req->defobj_out == NULL ||
3208 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3209 res = symlook_list(&req1, &list_main, donelist);
3210 if (res == 0 && (req->defobj_out == NULL ||
3211 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3212 req->sym_out = req1.sym_out;
3213 req->defobj_out = req1.defobj_out;
3214 assert(req->defobj_out != NULL);
3218 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3219 STAILQ_FOREACH(elm, &list_global, link) {
3220 if (req->defobj_out != NULL &&
3221 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3223 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3224 if (res == 0 && (req->defobj_out == NULL ||
3225 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3226 req->sym_out = req1.sym_out;
3227 req->defobj_out = req1.defobj_out;
3228 assert(req->defobj_out != NULL);
3232 return (req->sym_out != NULL ? 0 : ESRCH);
3236 * This is a special version of getenv which is far more efficient
3237 * at finding LD_ environment vars.
3241 _getenv_ld(const char *id)
3245 int idlen = strlen(id);
3247 if (ld_index == LD_ARY_CACHE)
3249 if (ld_index == 0) {
3250 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
3251 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
3258 for (i = ld_index - 1; i >= 0; --i) {
3259 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
3260 return(ld_ary[i] + idlen + 1);
3266 * Given a symbol name in a referencing object, find the corresponding
3267 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3268 * no definition was found. Returns a pointer to the Obj_Entry of the
3269 * defining object via the reference parameter DEFOBJ_OUT.
3272 symlook_default(SymLook *req, const Obj_Entry *refobj)
3275 const Objlist_Entry *elm;
3279 donelist_init(&donelist);
3280 symlook_init_from_req(&req1, req);
3282 /* Look first in the referencing object if linked symbolically. */
3283 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3284 res = symlook_obj(&req1, refobj);
3286 req->sym_out = req1.sym_out;
3287 req->defobj_out = req1.defobj_out;
3288 assert(req->defobj_out != NULL);
3292 symlook_global(req, &donelist);
3294 /* Search all dlopened DAGs containing the referencing object. */
3295 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3296 if (req->sym_out != NULL &&
3297 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3299 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3300 if (res == 0 && (req->sym_out == NULL ||
3301 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3302 req->sym_out = req1.sym_out;
3303 req->defobj_out = req1.defobj_out;
3304 assert(req->defobj_out != NULL);
3309 * Search the dynamic linker itself, and possibly resolve the
3310 * symbol from there. This is how the application links to
3311 * dynamic linker services such as dlopen. Only the values listed
3312 * in the "exports" array can be resolved from the dynamic linker.
3314 if (req->sym_out == NULL ||
3315 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3316 res = symlook_obj(&req1, &obj_rtld);
3317 if (res == 0 && is_exported(req1.sym_out)) {
3318 req->sym_out = req1.sym_out;
3319 req->defobj_out = req1.defobj_out;
3320 assert(req->defobj_out != NULL);
3324 return (req->sym_out != NULL ? 0 : ESRCH);
3328 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3331 const Obj_Entry *defobj;
3332 const Objlist_Entry *elm;
3338 STAILQ_FOREACH(elm, objlist, link) {
3339 if (donelist_check(dlp, elm->obj))
3341 symlook_init_from_req(&req1, req);
3342 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3343 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3345 defobj = req1.defobj_out;
3346 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3353 req->defobj_out = defobj;
3360 * Search the chain of DAGS cointed to by the given Needed_Entry
3361 * for a symbol of the given name. Each DAG is scanned completely
3362 * before advancing to the next one. Returns a pointer to the symbol,
3363 * or NULL if no definition was found.
3366 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3369 const Needed_Entry *n;
3370 const Obj_Entry *defobj;
3376 symlook_init_from_req(&req1, req);
3377 for (n = needed; n != NULL; n = n->next) {
3378 if (n->obj == NULL ||
3379 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3381 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3383 defobj = req1.defobj_out;
3384 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3390 req->defobj_out = defobj;
3397 * Search the symbol table of a single shared object for a symbol of
3398 * the given name and version, if requested. Returns a pointer to the
3399 * symbol, or NULL if no definition was found. If the object is
3400 * filter, return filtered symbol from filtee.
3402 * The symbol's hash value is passed in for efficiency reasons; that
3403 * eliminates many recomputations of the hash value.
3406 symlook_obj(SymLook *req, const Obj_Entry *obj)
3412 mres = symlook_obj1(req, obj);
3414 if (obj->needed_filtees != NULL) {
3415 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate);
3416 donelist_init(&donelist);
3417 symlook_init_from_req(&req1, req);
3418 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3420 req->sym_out = req1.sym_out;
3421 req->defobj_out = req1.defobj_out;
3425 if (obj->needed_aux_filtees != NULL) {
3426 load_filtees(__DECONST(Obj_Entry *, obj), 0, req->lockstate);
3427 donelist_init(&donelist);
3428 symlook_init_from_req(&req1, req);
3429 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3431 req->sym_out = req1.sym_out;
3432 req->defobj_out = req1.defobj_out;
3441 symlook_obj1(SymLook *req, const Obj_Entry *obj)
3443 unsigned long symnum;
3444 const Elf_Sym *vsymp;
3448 if (obj->buckets == NULL)
3453 symnum = obj->buckets[req->hash % obj->nbuckets];
3455 for (; symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
3456 const Elf_Sym *symp;
3459 if (symnum >= obj->nchains)
3460 return (ESRCH); /* Bad object */
3462 symp = obj->symtab + symnum;
3463 strp = obj->strtab + symp->st_name;
3465 switch (ELF_ST_TYPE(symp->st_info)) {
3470 if (symp->st_value == 0)
3474 if (symp->st_shndx != SHN_UNDEF)
3476 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3477 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3483 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
3486 if (req->ventry == NULL) {
3487 if (obj->versyms != NULL) {
3488 verndx = VER_NDX(obj->versyms[symnum]);
3489 if (verndx > obj->vernum) {
3490 _rtld_error("%s: symbol %s references wrong version %d",
3491 obj->path, obj->strtab + symnum, verndx);
3495 * If we are not called from dlsym (i.e. this is a normal
3496 * relocation from unversioned binary), accept the symbol
3497 * immediately if it happens to have first version after
3498 * this shared object became versioned. Otherwise, if
3499 * symbol is versioned and not hidden, remember it. If it
3500 * is the only symbol with this name exported by the
3501 * shared object, it will be returned as a match at the
3502 * end of the function. If symbol is global (verndx < 2)
3503 * accept it unconditionally.
3505 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
3506 verndx == VER_NDX_GIVEN) {
3507 req->sym_out = symp;
3508 req->defobj_out = obj;
3511 else if (verndx >= VER_NDX_GIVEN) {
3512 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
3520 req->sym_out = symp;
3521 req->defobj_out = obj;
3524 if (obj->versyms == NULL) {
3525 if (object_match_name(obj, req->ventry->name)) {
3526 _rtld_error("%s: object %s should provide version %s for "
3527 "symbol %s", obj_rtld.path, obj->path,
3528 req->ventry->name, obj->strtab + symnum);
3532 verndx = VER_NDX(obj->versyms[symnum]);
3533 if (verndx > obj->vernum) {
3534 _rtld_error("%s: symbol %s references wrong version %d",
3535 obj->path, obj->strtab + symnum, verndx);
3538 if (obj->vertab[verndx].hash != req->ventry->hash ||
3539 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
3541 * Version does not match. Look if this is a global symbol
3542 * and if it is not hidden. If global symbol (verndx < 2)
3543 * is available, use it. Do not return symbol if we are
3544 * called by dlvsym, because dlvsym looks for a specific
3545 * version and default one is not what dlvsym wants.
3547 if ((req->flags & SYMLOOK_DLSYM) ||
3548 (obj->versyms[symnum] & VER_NDX_HIDDEN) ||
3549 (verndx >= VER_NDX_GIVEN))
3553 req->sym_out = symp;
3554 req->defobj_out = obj;
3559 req->sym_out = vsymp;
3560 req->defobj_out = obj;
3567 trace_loaded_objects(Obj_Entry *obj)
3569 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
3572 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
3575 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
3576 fmt1 = "\t%o => %p (%x)\n";
3578 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
3579 fmt2 = "\t%o (%x)\n";
3581 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");
3583 for (; obj; obj = obj->next) {
3584 Needed_Entry *needed;
3588 if (list_containers && obj->needed != NULL)
3589 rtld_printf("%s:\n", obj->path);
3590 for (needed = obj->needed; needed; needed = needed->next) {
3591 if (needed->obj != NULL) {
3592 if (needed->obj->traced && !list_containers)
3594 needed->obj->traced = true;
3595 path = needed->obj->path;
3599 name = (char *)obj->strtab + needed->name;
3600 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
3602 fmt = is_lib ? fmt1 : fmt2;
3603 while ((c = *fmt++) != '\0') {
3629 rtld_putstr(main_local);
3632 rtld_putstr(obj_main->path);
3641 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
3654 * Unload a dlopened object and its dependencies from memory and from
3655 * our data structures. It is assumed that the DAG rooted in the
3656 * object has already been unreferenced, and that the object has a
3657 * reference count of 0.
3660 unload_object(Obj_Entry *root)
3665 assert(root->refcount == 0);
3668 * Pass over the DAG removing unreferenced objects from
3669 * appropriate lists.
3671 unlink_object(root);
3673 /* Unmap all objects that are no longer referenced. */
3674 linkp = &obj_list->next;
3675 while ((obj = *linkp) != NULL) {
3676 if (obj->refcount == 0) {
3677 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
3679 dbg("unloading \"%s\"", obj->path);
3680 unload_filtees(root);
3681 munmap(obj->mapbase, obj->mapsize);
3682 linkmap_delete(obj);
3693 unlink_object(Obj_Entry *root)
3697 if (root->refcount == 0) {
3698 /* Remove the object from the RTLD_GLOBAL list. */
3699 objlist_remove(&list_global, root);
3701 /* Remove the object from all objects' DAG lists. */
3702 STAILQ_FOREACH(elm, &root->dagmembers, link) {
3703 objlist_remove(&elm->obj->dldags, root);
3704 if (elm->obj != root)
3705 unlink_object(elm->obj);
3711 ref_dag(Obj_Entry *root)
3715 assert(root->dag_inited);
3716 STAILQ_FOREACH(elm, &root->dagmembers, link)
3717 elm->obj->refcount++;
3721 unref_dag(Obj_Entry *root)
3725 assert(root->dag_inited);
3726 STAILQ_FOREACH(elm, &root->dagmembers, link)
3727 elm->obj->refcount--;
3731 * Common code for MD __tls_get_addr().
3734 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
3736 Elf_Addr* dtv = *dtvp;
3737 RtldLockState lockstate;
3739 /* Check dtv generation in case new modules have arrived */
3740 if (dtv[0] != tls_dtv_generation) {
3744 wlock_acquire(rtld_bind_lock, &lockstate);
3745 newdtv = calloc(1, (tls_max_index + 2) * sizeof(Elf_Addr));
3747 if (to_copy > tls_max_index)
3748 to_copy = tls_max_index;
3749 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
3750 newdtv[0] = tls_dtv_generation;
3751 newdtv[1] = tls_max_index;
3753 lock_release(rtld_bind_lock, &lockstate);
3754 dtv = *dtvp = newdtv;
3757 /* Dynamically allocate module TLS if necessary */
3758 if (!dtv[index + 1]) {
3759 /* Signal safe, wlock will block out signals. */
3760 wlock_acquire(rtld_bind_lock, &lockstate);
3761 if (!dtv[index + 1])
3762 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
3763 lock_release(rtld_bind_lock, &lockstate);
3765 return (void*) (dtv[index + 1] + offset);
3768 #if defined(RTLD_STATIC_TLS_VARIANT_II)
3771 * Allocate the static TLS area. Return a pointer to the TCB. The
3772 * static area is based on negative offsets relative to the tcb.
3774 * The TCB contains an errno pointer for the system call layer, but because
3775 * we are the RTLD we really have no idea how the caller was compiled so
3776 * the information has to be passed in. errno can either be:
3778 * type 0 errno is a simple non-TLS global pointer.
3779 * (special case for e.g. libc_rtld)
3780 * type 1 errno accessed by GOT entry (dynamically linked programs)
3781 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
3784 allocate_tls(Obj_Entry *objs)
3789 struct tls_tcb *tcb;
3794 * Allocate the new TCB. static TLS storage is placed just before the
3795 * TCB to support the %gs:OFFSET (negative offset) model.
3797 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
3798 ~RTLD_STATIC_TLS_ALIGN_MASK;
3799 tcb = malloc(data_size + sizeof(*tcb));
3800 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
3802 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
3803 dtv = malloc(dtv_size);
3804 bzero(dtv, dtv_size);
3806 #ifdef RTLD_TCB_HAS_SELF_POINTER
3807 tcb->tcb_self = tcb;
3810 tcb->tcb_pthread = NULL;
3812 dtv[0] = tls_dtv_generation;
3813 dtv[1] = tls_max_index;
3815 for (obj = objs; obj; obj = obj->next) {
3816 if (obj->tlsoffset) {
3817 addr = (Elf_Addr)tcb - obj->tlsoffset;
3818 memset((void *)(addr + obj->tlsinitsize),
3819 0, obj->tlssize - obj->tlsinitsize);
3821 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
3822 dtv[obj->tlsindex + 1] = addr;
3829 free_tls(struct tls_tcb *tcb)
3833 Elf_Addr tls_start, tls_end;
3836 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
3837 ~RTLD_STATIC_TLS_ALIGN_MASK;
3841 tls_end = (Elf_Addr)tcb;
3842 tls_start = (Elf_Addr)tcb - data_size;
3843 for (i = 0; i < dtv_size; i++) {
3844 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
3845 free((void *)dtv[i+2]);
3849 free((void*) tls_start);
3853 #error "Unsupported TLS layout"
3857 * Allocate TLS block for module with given index.
3860 allocate_module_tls(int index)
3865 for (obj = obj_list; obj; obj = obj->next) {
3866 if (obj->tlsindex == index)
3870 _rtld_error("Can't find module with TLS index %d", index);
3874 p = malloc(obj->tlssize);
3876 _rtld_error("Cannot allocate TLS block for index %d", index);
3879 memcpy(p, obj->tlsinit, obj->tlsinitsize);
3880 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
3886 allocate_tls_offset(Obj_Entry *obj)
3893 if (obj->tlssize == 0) {
3894 obj->tls_done = true;
3898 if (obj->tlsindex == 1)
3899 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
3901 off = calculate_tls_offset(tls_last_offset, tls_last_size,
3902 obj->tlssize, obj->tlsalign);
3905 * If we have already fixed the size of the static TLS block, we
3906 * must stay within that size. When allocating the static TLS, we
3907 * leave a small amount of space spare to be used for dynamically
3908 * loading modules which use static TLS.
3910 if (tls_static_space) {
3911 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
3915 tls_last_offset = obj->tlsoffset = off;
3916 tls_last_size = obj->tlssize;
3917 obj->tls_done = true;
3923 free_tls_offset(Obj_Entry *obj)
3925 #ifdef RTLD_STATIC_TLS_VARIANT_II
3927 * If we were the last thing to allocate out of the static TLS
3928 * block, we give our space back to the 'allocator'. This is a
3929 * simplistic workaround to allow libGL.so.1 to be loaded and
3930 * unloaded multiple times. We only handle the Variant II
3931 * mechanism for now - this really needs a proper allocator.
3933 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
3934 == calculate_tls_end(tls_last_offset, tls_last_size)) {
3935 tls_last_offset -= obj->tlssize;
3942 _rtld_allocate_tls(void)
3944 struct tls_tcb *new_tcb;
3945 RtldLockState lockstate;
3947 wlock_acquire(rtld_bind_lock, &lockstate);
3948 new_tcb = allocate_tls(obj_list);
3949 lock_release(rtld_bind_lock, &lockstate);
3954 _rtld_free_tls(struct tls_tcb *tcb)
3956 RtldLockState lockstate;
3958 wlock_acquire(rtld_bind_lock, &lockstate);
3960 lock_release(rtld_bind_lock, &lockstate);
3964 object_add_name(Obj_Entry *obj, const char *name)
3970 entry = malloc(sizeof(Name_Entry) + len);
3972 if (entry != NULL) {
3973 strcpy(entry->name, name);
3974 STAILQ_INSERT_TAIL(&obj->names, entry, link);
3979 object_match_name(const Obj_Entry *obj, const char *name)
3983 STAILQ_FOREACH(entry, &obj->names, link) {
3984 if (strcmp(name, entry->name) == 0)
3991 locate_dependency(const Obj_Entry *obj, const char *name)
3993 const Objlist_Entry *entry;
3994 const Needed_Entry *needed;
3996 STAILQ_FOREACH(entry, &list_main, link) {
3997 if (object_match_name(entry->obj, name))
4001 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4002 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4003 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4005 * If there is DT_NEEDED for the name we are looking for,
4006 * we are all set. Note that object might not be found if
4007 * dependency was not loaded yet, so the function can
4008 * return NULL here. This is expected and handled
4009 * properly by the caller.
4011 return (needed->obj);
4014 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4020 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4021 const Elf_Vernaux *vna)
4023 const Elf_Verdef *vd;
4024 const char *vername;
4026 vername = refobj->strtab + vna->vna_name;
4027 vd = depobj->verdef;
4029 _rtld_error("%s: version %s required by %s not defined",
4030 depobj->path, vername, refobj->path);
4034 if (vd->vd_version != VER_DEF_CURRENT) {
4035 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4036 depobj->path, vd->vd_version);
4039 if (vna->vna_hash == vd->vd_hash) {
4040 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4041 ((char *)vd + vd->vd_aux);
4042 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4045 if (vd->vd_next == 0)
4047 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4049 if (vna->vna_flags & VER_FLG_WEAK)
4051 _rtld_error("%s: version %s required by %s not found",
4052 depobj->path, vername, refobj->path);
4057 rtld_verify_object_versions(Obj_Entry *obj)
4059 const Elf_Verneed *vn;
4060 const Elf_Verdef *vd;
4061 const Elf_Verdaux *vda;
4062 const Elf_Vernaux *vna;
4063 const Obj_Entry *depobj;
4064 int maxvernum, vernum;
4068 * Walk over defined and required version records and figure out
4069 * max index used by any of them. Do very basic sanity checking
4073 while (vn != NULL) {
4074 if (vn->vn_version != VER_NEED_CURRENT) {
4075 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4076 obj->path, vn->vn_version);
4079 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4081 vernum = VER_NEED_IDX(vna->vna_other);
4082 if (vernum > maxvernum)
4084 if (vna->vna_next == 0)
4086 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4088 if (vn->vn_next == 0)
4090 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4094 while (vd != NULL) {
4095 if (vd->vd_version != VER_DEF_CURRENT) {
4096 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4097 obj->path, vd->vd_version);
4100 vernum = VER_DEF_IDX(vd->vd_ndx);
4101 if (vernum > maxvernum)
4103 if (vd->vd_next == 0)
4105 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4112 * Store version information in array indexable by version index.
4113 * Verify that object version requirements are satisfied along the
4116 obj->vernum = maxvernum + 1;
4117 obj->vertab = calloc(obj->vernum, sizeof(Ver_Entry));
4120 while (vd != NULL) {
4121 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4122 vernum = VER_DEF_IDX(vd->vd_ndx);
4123 assert(vernum <= maxvernum);
4124 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4125 obj->vertab[vernum].hash = vd->vd_hash;
4126 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4127 obj->vertab[vernum].file = NULL;
4128 obj->vertab[vernum].flags = 0;
4130 if (vd->vd_next == 0)
4132 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4136 while (vn != NULL) {
4137 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4140 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4142 if (check_object_provided_version(obj, depobj, vna))
4144 vernum = VER_NEED_IDX(vna->vna_other);
4145 assert(vernum <= maxvernum);
4146 obj->vertab[vernum].hash = vna->vna_hash;
4147 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4148 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4149 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4150 VER_INFO_HIDDEN : 0;
4151 if (vna->vna_next == 0)
4153 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4155 if (vn->vn_next == 0)
4157 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4163 rtld_verify_versions(const Objlist *objlist)
4165 Objlist_Entry *entry;
4169 STAILQ_FOREACH(entry, objlist, link) {
4171 * Skip dummy objects or objects that have their version requirements
4174 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4176 if (rtld_verify_object_versions(entry->obj) == -1) {
4178 if (ld_tracing == NULL)
4182 if (rc == 0 || ld_tracing != NULL)
4183 rc = rtld_verify_object_versions(&obj_rtld);
4188 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4193 vernum = VER_NDX(obj->versyms[symnum]);
4194 if (vernum >= obj->vernum) {
4195 _rtld_error("%s: symbol %s has wrong verneed value %d",
4196 obj->path, obj->strtab + symnum, vernum);
4197 } else if (obj->vertab[vernum].hash != 0) {
4198 return &obj->vertab[vernum];
4205 _rtld_get_stack_prot(void)
4208 return (stack_prot);
4212 map_stacks_exec(RtldLockState *lockstate)
4216 * Stack protection must be implemented in the kernel before the dynamic
4217 * linker can handle PT_GNU_STACK sections.
4218 * The following is the FreeBSD implementation of map_stacks_exec()
4219 * void (*thr_map_stacks_exec)(void);
4221 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4223 * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4224 * get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4225 * if (thr_map_stacks_exec != NULL) {
4226 * stack_prot |= PROT_EXEC;
4227 * thr_map_stacks_exec();
4233 symlook_init(SymLook *dst, const char *name)
4236 bzero(dst, sizeof(*dst));
4238 dst->hash = elf_hash(name);
4242 symlook_init_from_req(SymLook *dst, const SymLook *src)
4245 dst->name = src->name;
4246 dst->hash = src->hash;
4247 dst->ventry = src->ventry;
4248 dst->flags = src->flags;
4249 dst->defobj_out = NULL;
4250 dst->sym_out = NULL;
4251 dst->lockstate = src->lockstate;
4254 #ifdef ENABLE_OSRELDATE
4256 * Overrides for libc_pic-provided functions.
4260 __getosreldate(void)
4270 oid[1] = KERN_OSRELDATE;
4272 len = sizeof(osrel);
4273 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
4274 if (error == 0 && osrel > 0 && len == sizeof(osrel))
4281 * No unresolved symbols for rtld.
4284 __pthread_cxa_finalize(struct dl_phdr_info *a)