2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * Copyright 2009-2012 Konstantin Belousov <kib@FreeBSD.ORG>.
5 * Copyright 2012 John Marino <draco@marino.st>.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 * Dynamic linker for ELF.
34 * John Polstra <jdp@polstra.com>.
38 #error "GCC is needed to compile this file"
41 #include <sys/param.h>
42 #include <sys/mount.h>
45 #include <sys/sysctl.h>
47 #include <sys/utsname.h>
48 #include <sys/ktrace.h>
64 #include "rtld_printf.h"
68 #define PATH_RTLD "/libexec/ld-elf.so.1"
70 #define PATH_RTLD "/libexec/ld-elf32.so.1"
74 typedef void (*func_ptr_type)();
75 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
78 * Function declarations.
80 static const char *basename(const char *);
81 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
82 const Elf_Dyn **, const Elf_Dyn **);
83 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
85 static void digest_dynamic(Obj_Entry *, int);
86 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
87 static Obj_Entry *dlcheck(void *);
88 static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
89 int lo_flags, int mode, RtldLockState *lockstate);
90 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
91 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
92 static bool donelist_check(DoneList *, const Obj_Entry *);
93 static void errmsg_restore(char *);
94 static char *errmsg_save(void);
95 static void *fill_search_info(const char *, size_t, void *);
96 static char *find_library(const char *, const Obj_Entry *, int *);
97 static const char *gethints(bool);
98 static void init_dag(Obj_Entry *);
99 static void init_pagesizes(Elf_Auxinfo **aux_info);
100 static void init_rtld(caddr_t, Elf_Auxinfo **);
101 static void initlist_add_neededs(Needed_Entry *, Objlist *);
102 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
103 static void linkmap_add(Obj_Entry *);
104 static void linkmap_delete(Obj_Entry *);
105 static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
106 static void unload_filtees(Obj_Entry *);
107 static int load_needed_objects(Obj_Entry *, int);
108 static int load_preload_objects(void);
109 static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int);
110 static void map_stacks_exec(RtldLockState *);
111 static Obj_Entry *obj_from_addr(const void *);
112 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
113 static void objlist_call_init(Objlist *, RtldLockState *);
114 static void objlist_clear(Objlist *);
115 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
116 static void objlist_init(Objlist *);
117 static void objlist_push_head(Objlist *, Obj_Entry *);
118 static void objlist_push_tail(Objlist *, Obj_Entry *);
119 static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
120 static void objlist_remove(Objlist *, Obj_Entry *);
121 static int parse_libdir(const char *);
122 static void *path_enumerate(const char *, path_enum_proc, void *);
123 static int relocate_object_dag(Obj_Entry *root, bool bind_now,
124 Obj_Entry *rtldobj, int flags, RtldLockState *lockstate);
125 static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
126 int flags, RtldLockState *lockstate);
127 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
129 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
130 int flags, RtldLockState *lockstate);
131 static int rtld_dirname(const char *, char *);
132 static int rtld_dirname_abs(const char *, char *);
133 static void *rtld_dlopen(const char *name, int fd, int mode);
134 static void rtld_exit(void);
135 static char *search_library_path(const char *, const char *);
136 static char *search_library_pathfds(const char *, const char *, int *);
137 static const void **get_program_var_addr(const char *, RtldLockState *);
138 static void set_program_var(const char *, const void *);
139 static int symlook_default(SymLook *, const Obj_Entry *refobj);
140 static int symlook_global(SymLook *, DoneList *);
141 static void symlook_init_from_req(SymLook *, const SymLook *);
142 static int symlook_list(SymLook *, const Objlist *, DoneList *);
143 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
144 static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
145 static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
146 static void trace_loaded_objects(Obj_Entry *);
147 static void unlink_object(Obj_Entry *);
148 static void unload_object(Obj_Entry *);
149 static void unref_dag(Obj_Entry *);
150 static void ref_dag(Obj_Entry *);
151 static char *origin_subst_one(char *, const char *, const char *, bool);
152 static char *origin_subst(char *, const char *);
153 static void preinit_main(void);
154 static int rtld_verify_versions(const Objlist *);
155 static int rtld_verify_object_versions(Obj_Entry *);
156 static void object_add_name(Obj_Entry *, const char *);
157 static int object_match_name(const Obj_Entry *, const char *);
158 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
159 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
160 struct dl_phdr_info *phdr_info);
161 static uint32_t gnu_hash(const char *);
162 static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
163 const unsigned long);
165 void r_debug_state(struct r_debug *, struct link_map *) __noinline __exported;
166 void _r_debug_postinit(struct link_map *) __noinline __exported;
168 int __sys_openat(int, const char *, int, ...);
173 static char *error_message; /* Message for dlerror(), or NULL */
174 struct r_debug r_debug __exported; /* for GDB; */
175 static bool libmap_disable; /* Disable libmap */
176 static bool ld_loadfltr; /* Immediate filters processing */
177 static char *libmap_override; /* Maps to use in addition to libmap.conf */
178 static bool trust; /* False for setuid and setgid programs */
179 static bool dangerous_ld_env; /* True if environment variables have been
180 used to affect the libraries loaded */
181 static char *ld_bind_now; /* Environment variable for immediate binding */
182 static char *ld_debug; /* Environment variable for debugging */
183 static char *ld_library_path; /* Environment variable for search path */
184 static char *ld_library_dirs; /* Environment variable for library descriptors */
185 static char *ld_preload; /* Environment variable for libraries to
187 static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
188 static char *ld_tracing; /* Called from ldd to print libs */
189 static char *ld_utrace; /* Use utrace() to log events. */
190 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
191 static Obj_Entry **obj_tail; /* Link field of last object in list */
192 static Obj_Entry *obj_main; /* The main program shared object */
193 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
194 static unsigned int obj_count; /* Number of objects in obj_list */
195 static unsigned int obj_loads; /* Number of objects in obj_list */
197 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
198 STAILQ_HEAD_INITIALIZER(list_global);
199 static Objlist list_main = /* Objects loaded at program startup */
200 STAILQ_HEAD_INITIALIZER(list_main);
201 static Objlist list_fini = /* Objects needing fini() calls */
202 STAILQ_HEAD_INITIALIZER(list_fini);
204 Elf_Sym sym_zero; /* For resolving undefined weak refs. */
206 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
208 extern Elf_Dyn _DYNAMIC;
209 #pragma weak _DYNAMIC
210 #ifndef RTLD_IS_DYNAMIC
211 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
214 int dlclose(void *) __exported;
215 char *dlerror(void) __exported;
216 void *dlopen(const char *, int) __exported;
217 void *fdlopen(int, int) __exported;
218 void *dlsym(void *, const char *) __exported;
219 dlfunc_t dlfunc(void *, const char *) __exported;
220 void *dlvsym(void *, const char *, const char *) __exported;
221 int dladdr(const void *, Dl_info *) __exported;
222 void dllockinit(void *, void *(*)(void *), void (*)(void *), void (*)(void *),
223 void (*)(void *), void (*)(void *), void (*)(void *)) __exported;
224 int dlinfo(void *, int , void *) __exported;
225 int dl_iterate_phdr(__dl_iterate_hdr_callback, void *) __exported;
226 int _rtld_addr_phdr(const void *, struct dl_phdr_info *) __exported;
227 int _rtld_get_stack_prot(void) __exported;
228 int _rtld_is_dlopened(void *) __exported;
229 void _rtld_error(const char *, ...) __exported;
231 int npagesizes, osreldate;
234 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
236 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
237 static int max_stack_flags;
240 * Global declarations normally provided by crt1. The dynamic linker is
241 * not built with crt1, so we have to provide them ourselves.
247 * Used to pass argc, argv to init functions.
253 * Globals to control TLS allocation.
255 size_t tls_last_offset; /* Static TLS offset of last module */
256 size_t tls_last_size; /* Static TLS size of last module */
257 size_t tls_static_space; /* Static TLS space allocated */
258 size_t tls_static_max_align;
259 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
260 int tls_max_index = 1; /* Largest module index allocated */
262 bool ld_library_path_rpath = false;
265 * Fill in a DoneList with an allocation large enough to hold all of
266 * the currently-loaded objects. Keep this as a macro since it calls
267 * alloca and we want that to occur within the scope of the caller.
269 #define donelist_init(dlp) \
270 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
271 assert((dlp)->objs != NULL), \
272 (dlp)->num_alloc = obj_count, \
275 #define UTRACE_DLOPEN_START 1
276 #define UTRACE_DLOPEN_STOP 2
277 #define UTRACE_DLCLOSE_START 3
278 #define UTRACE_DLCLOSE_STOP 4
279 #define UTRACE_LOAD_OBJECT 5
280 #define UTRACE_UNLOAD_OBJECT 6
281 #define UTRACE_ADD_RUNDEP 7
282 #define UTRACE_PRELOAD_FINISHED 8
283 #define UTRACE_INIT_CALL 9
284 #define UTRACE_FINI_CALL 10
285 #define UTRACE_DLSYM_START 11
286 #define UTRACE_DLSYM_STOP 12
289 char sig[4]; /* 'RTLD' */
292 void *mapbase; /* Used for 'parent' and 'init/fini' */
294 int refcnt; /* Used for 'mode' */
295 char name[MAXPATHLEN];
298 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
299 if (ld_utrace != NULL) \
300 ld_utrace_log(e, h, mb, ms, r, n); \
304 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
305 int refcnt, const char *name)
307 struct utrace_rtld ut;
315 ut.mapbase = mapbase;
316 ut.mapsize = mapsize;
318 bzero(ut.name, sizeof(ut.name));
320 strlcpy(ut.name, name, sizeof(ut.name));
321 utrace(&ut, sizeof(ut));
325 * Main entry point for dynamic linking. The first argument is the
326 * stack pointer. The stack is expected to be laid out as described
327 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
328 * Specifically, the stack pointer points to a word containing
329 * ARGC. Following that in the stack is a null-terminated sequence
330 * of pointers to argument strings. Then comes a null-terminated
331 * sequence of pointers to environment strings. Finally, there is a
332 * sequence of "auxiliary vector" entries.
334 * The second argument points to a place to store the dynamic linker's
335 * exit procedure pointer and the third to a place to store the main
338 * The return value is the main program's entry point.
341 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
343 Elf_Auxinfo *aux_info[AT_COUNT];
351 Objlist_Entry *entry;
353 Obj_Entry **preload_tail;
354 Obj_Entry *last_interposer;
356 RtldLockState lockstate;
357 char *library_path_rpath;
362 * On entry, the dynamic linker itself has not been relocated yet.
363 * Be very careful not to reference any global data until after
364 * init_rtld has returned. It is OK to reference file-scope statics
365 * and string constants, and to call static and global functions.
368 /* Find the auxiliary vector on the stack. */
371 sp += argc + 1; /* Skip over arguments and NULL terminator */
373 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
375 aux = (Elf_Auxinfo *) sp;
377 /* Digest the auxiliary vector. */
378 for (i = 0; i < AT_COUNT; i++)
380 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
381 if (auxp->a_type < AT_COUNT)
382 aux_info[auxp->a_type] = auxp;
385 /* Initialize and relocate ourselves. */
386 assert(aux_info[AT_BASE] != NULL);
387 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
389 __progname = obj_rtld.path;
390 argv0 = argv[0] != NULL ? argv[0] : "(null)";
395 if (aux_info[AT_CANARY] != NULL &&
396 aux_info[AT_CANARY]->a_un.a_ptr != NULL) {
397 i = aux_info[AT_CANARYLEN]->a_un.a_val;
398 if (i > sizeof(__stack_chk_guard))
399 i = sizeof(__stack_chk_guard);
400 memcpy(__stack_chk_guard, aux_info[AT_CANARY]->a_un.a_ptr, i);
405 len = sizeof(__stack_chk_guard);
406 if (sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 ||
407 len != sizeof(__stack_chk_guard)) {
408 /* If sysctl was unsuccessful, use the "terminator canary". */
409 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
410 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
411 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
412 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
416 trust = !issetugid();
418 ld_bind_now = getenv(LD_ "BIND_NOW");
420 * If the process is tainted, then we un-set the dangerous environment
421 * variables. The process will be marked as tainted until setuid(2)
422 * is called. If any child process calls setuid(2) we do not want any
423 * future processes to honor the potentially un-safe variables.
426 if (unsetenv(LD_ "PRELOAD") || unsetenv(LD_ "LIBMAP") ||
427 unsetenv(LD_ "LIBRARY_PATH") || unsetenv(LD_ "LIBRARY_PATH_FDS") ||
428 unsetenv(LD_ "LIBMAP_DISABLE") ||
429 unsetenv(LD_ "DEBUG") || unsetenv(LD_ "ELF_HINTS_PATH") ||
430 unsetenv(LD_ "LOADFLTR") || unsetenv(LD_ "LIBRARY_PATH_RPATH")) {
431 _rtld_error("environment corrupt; aborting");
435 ld_debug = getenv(LD_ "DEBUG");
436 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL;
437 libmap_override = getenv(LD_ "LIBMAP");
438 ld_library_path = getenv(LD_ "LIBRARY_PATH");
439 ld_library_dirs = getenv(LD_ "LIBRARY_PATH_FDS");
440 ld_preload = getenv(LD_ "PRELOAD");
441 ld_elf_hints_path = getenv(LD_ "ELF_HINTS_PATH");
442 ld_loadfltr = getenv(LD_ "LOADFLTR") != NULL;
443 library_path_rpath = getenv(LD_ "LIBRARY_PATH_RPATH");
444 if (library_path_rpath != NULL) {
445 if (library_path_rpath[0] == 'y' ||
446 library_path_rpath[0] == 'Y' ||
447 library_path_rpath[0] == '1')
448 ld_library_path_rpath = true;
450 ld_library_path_rpath = false;
452 dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
453 (ld_library_path != NULL) || (ld_preload != NULL) ||
454 (ld_elf_hints_path != NULL) || ld_loadfltr;
455 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS");
456 ld_utrace = getenv(LD_ "UTRACE");
458 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
459 ld_elf_hints_path = _PATH_ELF_HINTS;
461 if (ld_debug != NULL && *ld_debug != '\0')
463 dbg("%s is initialized, base address = %p", __progname,
464 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
465 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
466 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
468 dbg("initializing thread locks");
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 if (aux_info[AT_EXECPATH] != 0) {
503 char buf[MAXPATHLEN];
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 dbg("No AT_EXECPATH");
517 obj_main->path = xstrdup(argv0);
519 dbg("obj_main path %s", obj_main->path);
520 obj_main->mainprog = true;
522 if (aux_info[AT_STACKPROT] != NULL &&
523 aux_info[AT_STACKPROT]->a_un.a_val != 0)
524 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
528 * Get the actual dynamic linker pathname from the executable if
529 * possible. (It should always be possible.) That ensures that
530 * gdb will find the right dynamic linker even if a non-standard
533 if (obj_main->interp != NULL &&
534 strcmp(obj_main->interp, obj_rtld.path) != 0) {
536 obj_rtld.path = xstrdup(obj_main->interp);
537 __progname = obj_rtld.path;
541 digest_dynamic(obj_main, 0);
542 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
543 obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
544 obj_main->dynsymcount);
546 linkmap_add(obj_main);
547 linkmap_add(&obj_rtld);
549 /* Link the main program into the list of objects. */
550 *obj_tail = obj_main;
551 obj_tail = &obj_main->next;
555 /* Initialize a fake symbol for resolving undefined weak references. */
556 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
557 sym_zero.st_shndx = SHN_UNDEF;
558 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
561 libmap_disable = (bool)lm_init(libmap_override);
563 dbg("loading LD_PRELOAD libraries");
564 if (load_preload_objects() == -1)
566 preload_tail = obj_tail;
568 dbg("loading needed objects");
569 if (load_needed_objects(obj_main, 0) == -1)
572 /* Make a list of all objects loaded at startup. */
573 last_interposer = obj_main;
574 for (obj = obj_list; obj != NULL; obj = obj->next) {
575 if (obj->z_interpose && obj != obj_main) {
576 objlist_put_after(&list_main, last_interposer, obj);
577 last_interposer = obj;
579 objlist_push_tail(&list_main, obj);
584 dbg("checking for required versions");
585 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
588 if (ld_tracing) { /* We're done */
589 trace_loaded_objects(obj_main);
593 if (getenv(LD_ "DUMP_REL_PRE") != NULL) {
594 dump_relocations(obj_main);
599 * Processing tls relocations requires having the tls offsets
600 * initialized. Prepare offsets before starting initial
601 * relocation processing.
603 dbg("initializing initial thread local storage offsets");
604 STAILQ_FOREACH(entry, &list_main, link) {
606 * Allocate all the initial objects out of the static TLS
607 * block even if they didn't ask for it.
609 allocate_tls_offset(entry->obj);
612 if (relocate_objects(obj_main,
613 ld_bind_now != NULL && *ld_bind_now != '\0',
614 &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
617 dbg("doing copy relocations");
618 if (do_copy_relocations(obj_main) == -1)
621 if (getenv(LD_ "DUMP_REL_POST") != NULL) {
622 dump_relocations(obj_main);
627 * Setup TLS for main thread. This must be done after the
628 * relocations are processed, since tls initialization section
629 * might be the subject for relocations.
631 dbg("initializing initial thread local storage");
632 allocate_initial_tls(obj_list);
634 dbg("initializing key program variables");
635 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
636 set_program_var("environ", env);
637 set_program_var("__elf_aux_vector", aux);
639 /* Make a list of init functions to call. */
640 objlist_init(&initlist);
641 initlist_add_objects(obj_list, preload_tail, &initlist);
643 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
645 map_stacks_exec(NULL);
647 dbg("resolving ifuncs");
648 if (resolve_objects_ifunc(obj_main,
649 ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
653 if (!obj_main->crt_no_init) {
655 * Make sure we don't call the main program's init and fini
656 * functions for binaries linked with old crt1 which calls
659 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
660 obj_main->preinit_array = obj_main->init_array =
661 obj_main->fini_array = (Elf_Addr)NULL;
664 wlock_acquire(rtld_bind_lock, &lockstate);
665 if (obj_main->crt_no_init)
667 objlist_call_init(&initlist, &lockstate);
668 _r_debug_postinit(&obj_main->linkmap);
669 objlist_clear(&initlist);
670 dbg("loading filtees");
671 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
672 if (ld_loadfltr || obj->z_loadfltr)
673 load_filtees(obj, 0, &lockstate);
675 lock_release(rtld_bind_lock, &lockstate);
677 dbg("transferring control to program entry point = %p", obj_main->entry);
679 /* Return the exit procedure and the program entry point. */
680 *exit_proc = rtld_exit;
682 return (func_ptr_type) obj_main->entry;
686 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
691 ptr = (void *)make_function_pointer(def, obj);
692 target = ((Elf_Addr (*)(void))ptr)();
693 return ((void *)target);
697 _rtld_bind(Obj_Entry *obj, Elf_Size reloff)
701 const Obj_Entry *defobj;
704 RtldLockState lockstate;
706 rlock_acquire(rtld_bind_lock, &lockstate);
707 if (sigsetjmp(lockstate.env, 0) != 0)
708 lock_upgrade(rtld_bind_lock, &lockstate);
710 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
712 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
714 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
715 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
719 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
720 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
722 target = (Elf_Addr)(defobj->relocbase + def->st_value);
724 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
725 defobj->strtab + def->st_name, basename(obj->path),
726 (void *)target, basename(defobj->path));
729 * Write the new contents for the jmpslot. Note that depending on
730 * architecture, the value which we need to return back to the
731 * lazy binding trampoline may or may not be the target
732 * address. The value returned from reloc_jmpslot() is the value
733 * that the trampoline needs.
735 target = reloc_jmpslot(where, target, defobj, obj, rel);
736 lock_release(rtld_bind_lock, &lockstate);
741 * Error reporting function. Use it like printf. If formats the message
742 * into a buffer, and sets things up so that the next call to dlerror()
743 * will return the message.
746 _rtld_error(const char *fmt, ...)
748 static char buf[512];
752 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
758 * Return a dynamically-allocated copy of the current error message, if any.
763 return error_message == NULL ? NULL : xstrdup(error_message);
767 * Restore the current error message from a copy which was previously saved
768 * by errmsg_save(). The copy is freed.
771 errmsg_restore(char *saved_msg)
773 if (saved_msg == NULL)
774 error_message = NULL;
776 _rtld_error("%s", saved_msg);
782 basename(const char *name)
784 const char *p = strrchr(name, '/');
785 return p != NULL ? p + 1 : name;
788 static struct utsname uts;
791 origin_subst_one(char *real, const char *kw, const char *subst,
794 char *p, *p1, *res, *resp;
795 int subst_len, kw_len, subst_count, old_len, new_len;
800 * First, count the number of the keyword occurences, to
801 * preallocate the final string.
803 for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
810 * If the keyword is not found, just return.
812 if (subst_count == 0)
813 return (may_free ? real : xstrdup(real));
816 * There is indeed something to substitute. Calculate the
817 * length of the resulting string, and allocate it.
819 subst_len = strlen(subst);
820 old_len = strlen(real);
821 new_len = old_len + (subst_len - kw_len) * subst_count;
822 res = xmalloc(new_len + 1);
825 * Now, execute the substitution loop.
827 for (p = real, resp = res, *resp = '\0';;) {
830 /* Copy the prefix before keyword. */
831 memcpy(resp, p, p1 - p);
833 /* Keyword replacement. */
834 memcpy(resp, subst, subst_len);
842 /* Copy to the end of string and finish. */
850 origin_subst(char *real, const char *origin_path)
852 char *res1, *res2, *res3, *res4;
854 if (uts.sysname[0] == '\0') {
855 if (uname(&uts) != 0) {
856 _rtld_error("utsname failed: %d", errno);
860 res1 = origin_subst_one(real, "$ORIGIN", origin_path, false);
861 res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true);
862 res3 = origin_subst_one(res2, "$OSREL", uts.release, true);
863 res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true);
870 const char *msg = dlerror();
874 rtld_fdputstr(STDERR_FILENO, msg);
875 rtld_fdputchar(STDERR_FILENO, '\n');
880 * Process a shared object's DYNAMIC section, and save the important
881 * information in its Obj_Entry structure.
884 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
885 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
888 Needed_Entry **needed_tail = &obj->needed;
889 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
890 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
891 const Elf_Hashelt *hashtab;
892 const Elf32_Word *hashval;
893 Elf32_Word bkt, nmaskwords;
895 int plttype = DT_REL;
901 obj->bind_now = false;
902 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
903 switch (dynp->d_tag) {
906 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
910 obj->relsize = dynp->d_un.d_val;
914 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
918 obj->pltrel = (const Elf_Rel *)
919 (obj->relocbase + dynp->d_un.d_ptr);
923 obj->pltrelsize = dynp->d_un.d_val;
927 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
931 obj->relasize = dynp->d_un.d_val;
935 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
939 plttype = dynp->d_un.d_val;
940 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
944 obj->symtab = (const Elf_Sym *)
945 (obj->relocbase + dynp->d_un.d_ptr);
949 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
953 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
957 obj->strsize = dynp->d_un.d_val;
961 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
966 obj->verneednum = dynp->d_un.d_val;
970 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
975 obj->verdefnum = dynp->d_un.d_val;
979 obj->versyms = (const Elf_Versym *)(obj->relocbase +
985 hashtab = (const Elf_Hashelt *)(obj->relocbase +
987 obj->nbuckets = hashtab[0];
988 obj->nchains = hashtab[1];
989 obj->buckets = hashtab + 2;
990 obj->chains = obj->buckets + obj->nbuckets;
991 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
992 obj->buckets != NULL;
998 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1000 obj->nbuckets_gnu = hashtab[0];
1001 obj->symndx_gnu = hashtab[1];
1002 nmaskwords = hashtab[2];
1003 bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1004 obj->maskwords_bm_gnu = nmaskwords - 1;
1005 obj->shift2_gnu = hashtab[3];
1006 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1007 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1008 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1010 /* Number of bitmask words is required to be power of 2 */
1011 obj->valid_hash_gnu = powerof2(nmaskwords) &&
1012 obj->nbuckets_gnu > 0 && obj->buckets_gnu != NULL;
1018 Needed_Entry *nep = NEW(Needed_Entry);
1019 nep->name = dynp->d_un.d_val;
1024 needed_tail = &nep->next;
1030 Needed_Entry *nep = NEW(Needed_Entry);
1031 nep->name = dynp->d_un.d_val;
1035 *needed_filtees_tail = nep;
1036 needed_filtees_tail = &nep->next;
1042 Needed_Entry *nep = NEW(Needed_Entry);
1043 nep->name = dynp->d_un.d_val;
1047 *needed_aux_filtees_tail = nep;
1048 needed_aux_filtees_tail = &nep->next;
1053 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1057 obj->textrel = true;
1061 obj->symbolic = true;
1066 * We have to wait until later to process this, because we
1067 * might not have gotten the address of the string table yet.
1077 *dyn_runpath = dynp;
1081 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1084 case DT_PREINIT_ARRAY:
1085 obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1088 case DT_PREINIT_ARRAYSZ:
1089 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1093 obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1096 case DT_INIT_ARRAYSZ:
1097 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1101 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1105 obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1108 case DT_FINI_ARRAYSZ:
1109 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1113 * Don't process DT_DEBUG on MIPS as the dynamic section
1114 * is mapped read-only. DT_MIPS_RLD_MAP is used instead.
1119 /* XXX - not implemented yet */
1121 dbg("Filling in DT_DEBUG entry");
1122 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1127 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1128 obj->z_origin = true;
1129 if (dynp->d_un.d_val & DF_SYMBOLIC)
1130 obj->symbolic = true;
1131 if (dynp->d_un.d_val & DF_TEXTREL)
1132 obj->textrel = true;
1133 if (dynp->d_un.d_val & DF_BIND_NOW)
1134 obj->bind_now = true;
1135 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1139 case DT_MIPS_LOCAL_GOTNO:
1140 obj->local_gotno = dynp->d_un.d_val;
1143 case DT_MIPS_SYMTABNO:
1144 obj->symtabno = dynp->d_un.d_val;
1147 case DT_MIPS_GOTSYM:
1148 obj->gotsym = dynp->d_un.d_val;
1151 case DT_MIPS_RLD_MAP:
1152 *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &r_debug;
1157 if (dynp->d_un.d_val & DF_1_NOOPEN)
1158 obj->z_noopen = true;
1159 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1160 obj->z_origin = true;
1161 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1163 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1164 obj->bind_now = true;
1165 if (dynp->d_un.d_val & DF_1_NODELETE)
1166 obj->z_nodelete = true;
1167 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1168 obj->z_loadfltr = true;
1169 if (dynp->d_un.d_val & DF_1_INTERPOSE)
1170 obj->z_interpose = true;
1171 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1172 obj->z_nodeflib = true;
1177 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1184 obj->traced = false;
1186 if (plttype == DT_RELA) {
1187 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1189 obj->pltrelasize = obj->pltrelsize;
1190 obj->pltrelsize = 0;
1193 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1194 if (obj->valid_hash_sysv)
1195 obj->dynsymcount = obj->nchains;
1196 else if (obj->valid_hash_gnu) {
1197 obj->dynsymcount = 0;
1198 for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1199 if (obj->buckets_gnu[bkt] == 0)
1201 hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1204 while ((*hashval++ & 1u) == 0);
1206 obj->dynsymcount += obj->symndx_gnu;
1211 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1212 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1215 if (obj->z_origin && obj->origin_path == NULL) {
1216 obj->origin_path = xmalloc(PATH_MAX);
1217 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1221 if (dyn_runpath != NULL) {
1222 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1224 obj->runpath = origin_subst(obj->runpath, obj->origin_path);
1226 else if (dyn_rpath != NULL) {
1227 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1229 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1232 if (dyn_soname != NULL)
1233 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1237 digest_dynamic(Obj_Entry *obj, int early)
1239 const Elf_Dyn *dyn_rpath;
1240 const Elf_Dyn *dyn_soname;
1241 const Elf_Dyn *dyn_runpath;
1243 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1244 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1248 * Process a shared object's program header. This is used only for the
1249 * main program, when the kernel has already loaded the main program
1250 * into memory before calling the dynamic linker. It creates and
1251 * returns an Obj_Entry structure.
1254 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1257 const Elf_Phdr *phlimit = phdr + phnum;
1259 Elf_Addr note_start, note_end;
1263 for (ph = phdr; ph < phlimit; ph++) {
1264 if (ph->p_type != PT_PHDR)
1268 obj->phsize = ph->p_memsz;
1269 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1273 obj->stack_flags = PF_X | PF_R | PF_W;
1275 for (ph = phdr; ph < phlimit; ph++) {
1276 switch (ph->p_type) {
1279 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1283 if (nsegs == 0) { /* First load segment */
1284 obj->vaddrbase = trunc_page(ph->p_vaddr);
1285 obj->mapbase = obj->vaddrbase + obj->relocbase;
1286 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1288 } else { /* Last load segment */
1289 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1296 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1301 obj->tlssize = ph->p_memsz;
1302 obj->tlsalign = ph->p_align;
1303 obj->tlsinitsize = ph->p_filesz;
1304 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1308 obj->stack_flags = ph->p_flags;
1312 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1313 obj->relro_size = round_page(ph->p_memsz);
1317 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1318 note_end = note_start + ph->p_filesz;
1319 digest_notes(obj, note_start, note_end);
1324 _rtld_error("%s: too few PT_LOAD segments", path);
1333 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1335 const Elf_Note *note;
1336 const char *note_name;
1339 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1340 note = (const Elf_Note *)((const char *)(note + 1) +
1341 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1342 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1343 if (note->n_namesz != sizeof(NOTE_FREEBSD_VENDOR) ||
1344 note->n_descsz != sizeof(int32_t))
1346 if (note->n_type != ABI_NOTETYPE &&
1347 note->n_type != CRT_NOINIT_NOTETYPE)
1349 note_name = (const char *)(note + 1);
1350 if (strncmp(NOTE_FREEBSD_VENDOR, note_name,
1351 sizeof(NOTE_FREEBSD_VENDOR)) != 0)
1353 switch (note->n_type) {
1355 /* FreeBSD osrel note */
1356 p = (uintptr_t)(note + 1);
1357 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1358 obj->osrel = *(const int32_t *)(p);
1359 dbg("note osrel %d", obj->osrel);
1361 case CRT_NOINIT_NOTETYPE:
1362 /* FreeBSD 'crt does not call init' note */
1363 obj->crt_no_init = true;
1364 dbg("note crt_no_init");
1371 dlcheck(void *handle)
1375 for (obj = obj_list; obj != NULL; obj = obj->next)
1376 if (obj == (Obj_Entry *) handle)
1379 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1380 _rtld_error("Invalid shared object handle %p", handle);
1387 * If the given object is already in the donelist, return true. Otherwise
1388 * add the object to the list and return false.
1391 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1395 for (i = 0; i < dlp->num_used; i++)
1396 if (dlp->objs[i] == obj)
1399 * Our donelist allocation should always be sufficient. But if
1400 * our threads locking isn't working properly, more shared objects
1401 * could have been loaded since we allocated the list. That should
1402 * never happen, but we'll handle it properly just in case it does.
1404 if (dlp->num_used < dlp->num_alloc)
1405 dlp->objs[dlp->num_used++] = obj;
1410 * Hash function for symbol table lookup. Don't even think about changing
1411 * this. It is specified by the System V ABI.
1414 elf_hash(const char *name)
1416 const unsigned char *p = (const unsigned char *) name;
1417 unsigned long h = 0;
1420 while (*p != '\0') {
1421 h = (h << 4) + *p++;
1422 if ((g = h & 0xf0000000) != 0)
1430 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1431 * unsigned in case it's implemented with a wider type.
1434 gnu_hash(const char *s)
1440 for (c = *s; c != '\0'; c = *++s)
1442 return (h & 0xffffffff);
1447 * Find the library with the given name, and return its full pathname.
1448 * The returned string is dynamically allocated. Generates an error
1449 * message and returns NULL if the library cannot be found.
1451 * If the second argument is non-NULL, then it refers to an already-
1452 * loaded shared object, whose library search path will be searched.
1454 * If a library is successfully located via LD_LIBRARY_PATH_FDS, its
1455 * descriptor (which is close-on-exec) will be passed out via the third
1458 * The search order is:
1459 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1460 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1462 * DT_RUNPATH in the referencing file
1463 * ldconfig hints (if -z nodefaultlib, filter out default library directories
1465 * /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1467 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1470 find_library(const char *xname, const Obj_Entry *refobj, int *fdp)
1474 bool nodeflib, objgiven;
1476 objgiven = refobj != NULL;
1477 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1478 if (xname[0] != '/' && !trust) {
1479 _rtld_error("Absolute pathname required for shared object \"%s\"",
1483 if (objgiven && refobj->z_origin) {
1484 return (origin_subst(__DECONST(char *, xname),
1485 refobj->origin_path));
1487 return (xstrdup(xname));
1491 if (libmap_disable || !objgiven ||
1492 (name = lm_find(refobj->path, xname)) == NULL)
1493 name = (char *)xname;
1495 dbg(" Searching for \"%s\"", name);
1498 * If refobj->rpath != NULL, then refobj->runpath is NULL. Fall
1499 * back to pre-conforming behaviour if user requested so with
1500 * LD_LIBRARY_PATH_RPATH environment variable and ignore -z
1503 if (objgiven && refobj->rpath != NULL && ld_library_path_rpath) {
1504 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1506 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1507 (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
1508 (pathname = search_library_path(name, gethints(false))) != NULL ||
1509 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1512 nodeflib = objgiven ? refobj->z_nodeflib : false;
1514 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1515 (objgiven && refobj->runpath == NULL && refobj != obj_main &&
1516 (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
1517 (pathname = search_library_path(name, ld_library_path)) != NULL ||
1519 (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
1520 (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
1521 (pathname = search_library_path(name, gethints(nodeflib))) != NULL ||
1522 (objgiven && !nodeflib &&
1523 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
1527 if (objgiven && refobj->path != NULL) {
1528 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1529 name, basename(refobj->path));
1531 _rtld_error("Shared object \"%s\" not found", name);
1537 * Given a symbol number in a referencing object, find the corresponding
1538 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1539 * no definition was found. Returns a pointer to the Obj_Entry of the
1540 * defining object via the reference parameter DEFOBJ_OUT.
1543 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1544 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1545 RtldLockState *lockstate)
1549 const Obj_Entry *defobj;
1555 * If we have already found this symbol, get the information from
1558 if (symnum >= refobj->dynsymcount)
1559 return NULL; /* Bad object */
1560 if (cache != NULL && cache[symnum].sym != NULL) {
1561 *defobj_out = cache[symnum].obj;
1562 return cache[symnum].sym;
1565 ref = refobj->symtab + symnum;
1566 name = refobj->strtab + ref->st_name;
1571 * We don't have to do a full scale lookup if the symbol is local.
1572 * We know it will bind to the instance in this load module; to
1573 * which we already have a pointer (ie ref). By not doing a lookup,
1574 * we not only improve performance, but it also avoids unresolvable
1575 * symbols when local symbols are not in the hash table. This has
1576 * been seen with the ia64 toolchain.
1578 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1579 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1580 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1583 symlook_init(&req, name);
1585 req.ventry = fetch_ventry(refobj, symnum);
1586 req.lockstate = lockstate;
1587 res = symlook_default(&req, refobj);
1590 defobj = req.defobj_out;
1598 * If we found no definition and the reference is weak, treat the
1599 * symbol as having the value zero.
1601 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1607 *defobj_out = defobj;
1608 /* Record the information in the cache to avoid subsequent lookups. */
1609 if (cache != NULL) {
1610 cache[symnum].sym = def;
1611 cache[symnum].obj = defobj;
1614 if (refobj != &obj_rtld)
1615 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1621 * Return the search path from the ldconfig hints file, reading it if
1622 * necessary. If nostdlib is true, then the default search paths are
1623 * not added to result.
1625 * Returns NULL if there are problems with the hints file,
1626 * or if the search path there is empty.
1629 gethints(bool nostdlib)
1631 static char *hints, *filtered_path;
1632 struct elfhints_hdr hdr;
1633 struct fill_search_info_args sargs, hargs;
1634 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1635 struct dl_serpath *SLPpath, *hintpath;
1637 unsigned int SLPndx, hintndx, fndx, fcount;
1642 /* First call, read the hints file */
1643 if (hints == NULL) {
1644 /* Keep from trying again in case the hints file is bad. */
1647 if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
1649 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1650 hdr.magic != ELFHINTS_MAGIC ||
1655 p = xmalloc(hdr.dirlistlen + 1);
1656 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1657 read(fd, p, hdr.dirlistlen + 1) !=
1658 (ssize_t)hdr.dirlistlen + 1) {
1668 * If caller agreed to receive list which includes the default
1669 * paths, we are done. Otherwise, if we still did not
1670 * calculated filtered result, do it now.
1673 return (hints[0] != '\0' ? hints : NULL);
1674 if (filtered_path != NULL)
1678 * Obtain the list of all configured search paths, and the
1679 * list of the default paths.
1681 * First estimate the size of the results.
1683 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1685 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1688 sargs.request = RTLD_DI_SERINFOSIZE;
1689 sargs.serinfo = &smeta;
1690 hargs.request = RTLD_DI_SERINFOSIZE;
1691 hargs.serinfo = &hmeta;
1693 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1694 path_enumerate(p, fill_search_info, &hargs);
1696 SLPinfo = xmalloc(smeta.dls_size);
1697 hintinfo = xmalloc(hmeta.dls_size);
1700 * Next fetch both sets of paths.
1702 sargs.request = RTLD_DI_SERINFO;
1703 sargs.serinfo = SLPinfo;
1704 sargs.serpath = &SLPinfo->dls_serpath[0];
1705 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1707 hargs.request = RTLD_DI_SERINFO;
1708 hargs.serinfo = hintinfo;
1709 hargs.serpath = &hintinfo->dls_serpath[0];
1710 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1712 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1713 path_enumerate(p, fill_search_info, &hargs);
1716 * Now calculate the difference between two sets, by excluding
1717 * standard paths from the full set.
1721 filtered_path = xmalloc(hdr.dirlistlen + 1);
1722 hintpath = &hintinfo->dls_serpath[0];
1723 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
1725 SLPpath = &SLPinfo->dls_serpath[0];
1727 * Check each standard path against current.
1729 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
1730 /* matched, skip the path */
1731 if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
1739 * Not matched against any standard path, add the path
1740 * to result. Separate consequtive paths with ':'.
1743 filtered_path[fndx] = ':';
1747 flen = strlen(hintpath->dls_name);
1748 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1751 filtered_path[fndx] = '\0';
1757 return (filtered_path[0] != '\0' ? filtered_path : NULL);
1761 init_dag(Obj_Entry *root)
1763 const Needed_Entry *needed;
1764 const Objlist_Entry *elm;
1767 if (root->dag_inited)
1769 donelist_init(&donelist);
1771 /* Root object belongs to own DAG. */
1772 objlist_push_tail(&root->dldags, root);
1773 objlist_push_tail(&root->dagmembers, root);
1774 donelist_check(&donelist, root);
1777 * Add dependencies of root object to DAG in breadth order
1778 * by exploiting the fact that each new object get added
1779 * to the tail of the dagmembers list.
1781 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1782 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1783 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1785 objlist_push_tail(&needed->obj->dldags, root);
1786 objlist_push_tail(&root->dagmembers, needed->obj);
1789 root->dag_inited = true;
1793 process_nodelete(Obj_Entry *root)
1795 const Objlist_Entry *elm;
1798 * Walk over object DAG and process every dependent object that
1799 * is marked as DF_1_NODELETE. They need to grow their own DAG,
1800 * which then should have its reference upped separately.
1802 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1803 if (elm->obj != NULL && elm->obj->z_nodelete &&
1804 !elm->obj->ref_nodel) {
1805 dbg("obj %s nodelete", elm->obj->path);
1808 elm->obj->ref_nodel = true;
1813 * Initialize the dynamic linker. The argument is the address at which
1814 * the dynamic linker has been mapped into memory. The primary task of
1815 * this function is to relocate the dynamic linker.
1818 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1820 Obj_Entry objtmp; /* Temporary rtld object */
1821 const Elf_Dyn *dyn_rpath;
1822 const Elf_Dyn *dyn_soname;
1823 const Elf_Dyn *dyn_runpath;
1825 #ifdef RTLD_INIT_PAGESIZES_EARLY
1826 /* The page size is required by the dynamic memory allocator. */
1827 init_pagesizes(aux_info);
1831 * Conjure up an Obj_Entry structure for the dynamic linker.
1833 * The "path" member can't be initialized yet because string constants
1834 * cannot yet be accessed. Below we will set it correctly.
1836 memset(&objtmp, 0, sizeof(objtmp));
1839 objtmp.mapbase = mapbase;
1841 objtmp.relocbase = mapbase;
1843 if (RTLD_IS_DYNAMIC()) {
1844 objtmp.dynamic = rtld_dynamic(&objtmp);
1845 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
1846 assert(objtmp.needed == NULL);
1847 #if !defined(__mips__)
1848 /* MIPS has a bogus DT_TEXTREL. */
1849 assert(!objtmp.textrel);
1853 * Temporarily put the dynamic linker entry into the object list, so
1854 * that symbols can be found.
1857 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
1860 /* Initialize the object list. */
1861 obj_tail = &obj_list;
1863 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1864 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1866 #ifndef RTLD_INIT_PAGESIZES_EARLY
1867 /* The page size is required by the dynamic memory allocator. */
1868 init_pagesizes(aux_info);
1871 if (aux_info[AT_OSRELDATE] != NULL)
1872 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1874 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
1876 /* Replace the path with a dynamically allocated copy. */
1877 obj_rtld.path = xstrdup(PATH_RTLD);
1879 r_debug.r_brk = r_debug_state;
1880 r_debug.r_state = RT_CONSISTENT;
1884 * Retrieve the array of supported page sizes. The kernel provides the page
1885 * sizes in increasing order.
1888 init_pagesizes(Elf_Auxinfo **aux_info)
1890 static size_t psa[MAXPAGESIZES];
1894 if (aux_info[AT_PAGESIZES] != NULL && aux_info[AT_PAGESIZESLEN] !=
1896 size = aux_info[AT_PAGESIZESLEN]->a_un.a_val;
1897 pagesizes = aux_info[AT_PAGESIZES]->a_un.a_ptr;
1900 if (sysctlnametomib("hw.pagesizes", mib, &len) == 0)
1903 /* As a fallback, retrieve the base page size. */
1904 size = sizeof(psa[0]);
1905 if (aux_info[AT_PAGESZ] != NULL) {
1906 psa[0] = aux_info[AT_PAGESZ]->a_un.a_val;
1910 mib[1] = HW_PAGESIZE;
1914 if (sysctl(mib, len, psa, &size, NULL, 0) == -1) {
1915 _rtld_error("sysctl for hw.pagesize(s) failed");
1921 npagesizes = size / sizeof(pagesizes[0]);
1922 /* Discard any invalid entries at the end of the array. */
1923 while (npagesizes > 0 && pagesizes[npagesizes - 1] == 0)
1928 * Add the init functions from a needed object list (and its recursive
1929 * needed objects) to "list". This is not used directly; it is a helper
1930 * function for initlist_add_objects(). The write lock must be held
1931 * when this function is called.
1934 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1936 /* Recursively process the successor needed objects. */
1937 if (needed->next != NULL)
1938 initlist_add_neededs(needed->next, list);
1940 /* Process the current needed object. */
1941 if (needed->obj != NULL)
1942 initlist_add_objects(needed->obj, &needed->obj->next, list);
1946 * Scan all of the DAGs rooted in the range of objects from "obj" to
1947 * "tail" and add their init functions to "list". This recurses over
1948 * the DAGs and ensure the proper init ordering such that each object's
1949 * needed libraries are initialized before the object itself. At the
1950 * same time, this function adds the objects to the global finalization
1951 * list "list_fini" in the opposite order. The write lock must be
1952 * held when this function is called.
1955 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1958 if (obj->init_scanned || obj->init_done)
1960 obj->init_scanned = true;
1962 /* Recursively process the successor objects. */
1963 if (&obj->next != tail)
1964 initlist_add_objects(obj->next, tail, list);
1966 /* Recursively process the needed objects. */
1967 if (obj->needed != NULL)
1968 initlist_add_neededs(obj->needed, list);
1969 if (obj->needed_filtees != NULL)
1970 initlist_add_neededs(obj->needed_filtees, list);
1971 if (obj->needed_aux_filtees != NULL)
1972 initlist_add_neededs(obj->needed_aux_filtees, list);
1974 /* Add the object to the init list. */
1975 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
1976 obj->init_array != (Elf_Addr)NULL)
1977 objlist_push_tail(list, obj);
1979 /* Add the object to the global fini list in the reverse order. */
1980 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1981 && !obj->on_fini_list) {
1982 objlist_push_head(&list_fini, obj);
1983 obj->on_fini_list = true;
1988 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1992 free_needed_filtees(Needed_Entry *n)
1994 Needed_Entry *needed, *needed1;
1996 for (needed = n; needed != NULL; needed = needed->next) {
1997 if (needed->obj != NULL) {
1998 dlclose(needed->obj);
2002 for (needed = n; needed != NULL; needed = needed1) {
2003 needed1 = needed->next;
2009 unload_filtees(Obj_Entry *obj)
2012 free_needed_filtees(obj->needed_filtees);
2013 obj->needed_filtees = NULL;
2014 free_needed_filtees(obj->needed_aux_filtees);
2015 obj->needed_aux_filtees = NULL;
2016 obj->filtees_loaded = false;
2020 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
2021 RtldLockState *lockstate)
2024 for (; needed != NULL; needed = needed->next) {
2025 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
2026 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
2027 RTLD_LOCAL, lockstate);
2032 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
2035 lock_restart_for_upgrade(lockstate);
2036 if (!obj->filtees_loaded) {
2037 load_filtee1(obj, obj->needed_filtees, flags, lockstate);
2038 load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
2039 obj->filtees_loaded = true;
2044 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
2048 for (; needed != NULL; needed = needed->next) {
2049 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
2050 flags & ~RTLD_LO_NOLOAD);
2051 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
2058 * Given a shared object, traverse its list of needed objects, and load
2059 * each of them. Returns 0 on success. Generates an error message and
2060 * returns -1 on failure.
2063 load_needed_objects(Obj_Entry *first, int flags)
2067 for (obj = first; obj != NULL; obj = obj->next) {
2068 if (process_needed(obj, obj->needed, flags) == -1)
2075 load_preload_objects(void)
2077 char *p = ld_preload;
2079 static const char delim[] = " \t:;";
2084 p += strspn(p, delim);
2085 while (*p != '\0') {
2086 size_t len = strcspn(p, delim);
2091 obj = load_object(p, -1, NULL, 0);
2093 return -1; /* XXX - cleanup */
2094 obj->z_interpose = true;
2097 p += strspn(p, delim);
2099 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2104 printable_path(const char *path)
2107 return (path == NULL ? "<unknown>" : path);
2111 * Load a shared object into memory, if it is not already loaded. The
2112 * object may be specified by name or by user-supplied file descriptor
2113 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2116 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2120 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2129 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
2130 if (object_match_name(obj, name))
2134 path = find_library(name, refobj, &fd);
2142 * search_library_pathfds() opens a fresh file descriptor for the
2143 * library, so there is no need to dup().
2145 } else if (fd_u == -1) {
2147 * If we didn't find a match by pathname, or the name is not
2148 * supplied, open the file and check again by device and inode.
2149 * This avoids false mismatches caused by multiple links or ".."
2152 * To avoid a race, we open the file and use fstat() rather than
2155 if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
2156 _rtld_error("Cannot open \"%s\"", path);
2161 fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
2163 _rtld_error("Cannot dup fd");
2168 if (fstat(fd, &sb) == -1) {
2169 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2174 for (obj = obj_list->next; obj != NULL; obj = obj->next)
2175 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2177 if (obj != NULL && name != NULL) {
2178 object_add_name(obj, name);
2183 if (flags & RTLD_LO_NOLOAD) {
2189 /* First use of this object, so we must map it in */
2190 obj = do_load_object(fd, name, path, &sb, flags);
2199 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2206 * but first, make sure that environment variables haven't been
2207 * used to circumvent the noexec flag on a filesystem.
2209 if (dangerous_ld_env) {
2210 if (fstatfs(fd, &fs) != 0) {
2211 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2214 if (fs.f_flags & MNT_NOEXEC) {
2215 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
2219 dbg("loading \"%s\"", printable_path(path));
2220 obj = map_object(fd, printable_path(path), sbp);
2225 * If DT_SONAME is present in the object, digest_dynamic2 already
2226 * added it to the object names.
2229 object_add_name(obj, name);
2231 digest_dynamic(obj, 0);
2232 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
2233 obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
2234 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2236 dbg("refusing to load non-loadable \"%s\"", obj->path);
2237 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2238 munmap(obj->mapbase, obj->mapsize);
2243 obj->dlopened = (flags & RTLD_LO_DLOPEN) != 0;
2245 obj_tail = &obj->next;
2248 linkmap_add(obj); /* for GDB & dlinfo() */
2249 max_stack_flags |= obj->stack_flags;
2251 dbg(" %p .. %p: %s", obj->mapbase,
2252 obj->mapbase + obj->mapsize - 1, obj->path);
2254 dbg(" WARNING: %s has impure text", obj->path);
2255 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2262 obj_from_addr(const void *addr)
2266 for (obj = obj_list; obj != NULL; obj = obj->next) {
2267 if (addr < (void *) obj->mapbase)
2269 if (addr < (void *) (obj->mapbase + obj->mapsize))
2278 Elf_Addr *preinit_addr;
2281 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2282 if (preinit_addr == NULL)
2285 for (index = 0; index < obj_main->preinit_array_num; index++) {
2286 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2287 dbg("calling preinit function for %s at %p", obj_main->path,
2288 (void *)preinit_addr[index]);
2289 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2290 0, 0, obj_main->path);
2291 call_init_pointer(obj_main, preinit_addr[index]);
2297 * Call the finalization functions for each of the objects in "list"
2298 * belonging to the DAG of "root" and referenced once. If NULL "root"
2299 * is specified, every finalization function will be called regardless
2300 * of the reference count and the list elements won't be freed. All of
2301 * the objects are expected to have non-NULL fini functions.
2304 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2308 Elf_Addr *fini_addr;
2311 assert(root == NULL || root->refcount == 1);
2314 * Preserve the current error message since a fini function might
2315 * call into the dynamic linker and overwrite it.
2317 saved_msg = errmsg_save();
2319 STAILQ_FOREACH(elm, list, link) {
2320 if (root != NULL && (elm->obj->refcount != 1 ||
2321 objlist_find(&root->dagmembers, elm->obj) == NULL))
2323 /* Remove object from fini list to prevent recursive invocation. */
2324 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2326 * XXX: If a dlopen() call references an object while the
2327 * fini function is in progress, we might end up trying to
2328 * unload the referenced object in dlclose() or the object
2329 * won't be unloaded although its fini function has been
2332 lock_release(rtld_bind_lock, lockstate);
2335 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
2336 * When this happens, DT_FINI_ARRAY is processed first.
2338 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2339 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2340 for (index = elm->obj->fini_array_num - 1; index >= 0;
2342 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2343 dbg("calling fini function for %s at %p",
2344 elm->obj->path, (void *)fini_addr[index]);
2345 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2346 (void *)fini_addr[index], 0, 0, elm->obj->path);
2347 call_initfini_pointer(elm->obj, fini_addr[index]);
2351 if (elm->obj->fini != (Elf_Addr)NULL) {
2352 dbg("calling fini function for %s at %p", elm->obj->path,
2353 (void *)elm->obj->fini);
2354 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2355 0, 0, elm->obj->path);
2356 call_initfini_pointer(elm->obj, elm->obj->fini);
2358 wlock_acquire(rtld_bind_lock, lockstate);
2359 /* No need to free anything if process is going down. */
2363 * We must restart the list traversal after every fini call
2364 * because a dlclose() call from the fini function or from
2365 * another thread might have modified the reference counts.
2369 } while (elm != NULL);
2370 errmsg_restore(saved_msg);
2374 * Call the initialization functions for each of the objects in
2375 * "list". All of the objects are expected to have non-NULL init
2379 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2384 Elf_Addr *init_addr;
2388 * Clean init_scanned flag so that objects can be rechecked and
2389 * possibly initialized earlier if any of vectors called below
2390 * cause the change by using dlopen.
2392 for (obj = obj_list; obj != NULL; obj = obj->next)
2393 obj->init_scanned = false;
2396 * Preserve the current error message since an init function might
2397 * call into the dynamic linker and overwrite it.
2399 saved_msg = errmsg_save();
2400 STAILQ_FOREACH(elm, list, link) {
2401 if (elm->obj->init_done) /* Initialized early. */
2404 * Race: other thread might try to use this object before current
2405 * one completes the initilization. Not much can be done here
2406 * without better locking.
2408 elm->obj->init_done = true;
2409 lock_release(rtld_bind_lock, lockstate);
2412 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
2413 * When this happens, DT_INIT is processed first.
2415 if (elm->obj->init != (Elf_Addr)NULL) {
2416 dbg("calling init function for %s at %p", elm->obj->path,
2417 (void *)elm->obj->init);
2418 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2419 0, 0, elm->obj->path);
2420 call_initfini_pointer(elm->obj, elm->obj->init);
2422 init_addr = (Elf_Addr *)elm->obj->init_array;
2423 if (init_addr != NULL) {
2424 for (index = 0; index < elm->obj->init_array_num; index++) {
2425 if (init_addr[index] != 0 && init_addr[index] != 1) {
2426 dbg("calling init function for %s at %p", elm->obj->path,
2427 (void *)init_addr[index]);
2428 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2429 (void *)init_addr[index], 0, 0, elm->obj->path);
2430 call_init_pointer(elm->obj, init_addr[index]);
2434 wlock_acquire(rtld_bind_lock, lockstate);
2436 errmsg_restore(saved_msg);
2440 objlist_clear(Objlist *list)
2444 while (!STAILQ_EMPTY(list)) {
2445 elm = STAILQ_FIRST(list);
2446 STAILQ_REMOVE_HEAD(list, link);
2451 static Objlist_Entry *
2452 objlist_find(Objlist *list, const Obj_Entry *obj)
2456 STAILQ_FOREACH(elm, list, link)
2457 if (elm->obj == obj)
2463 objlist_init(Objlist *list)
2469 objlist_push_head(Objlist *list, Obj_Entry *obj)
2473 elm = NEW(Objlist_Entry);
2475 STAILQ_INSERT_HEAD(list, elm, link);
2479 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2483 elm = NEW(Objlist_Entry);
2485 STAILQ_INSERT_TAIL(list, elm, link);
2489 objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
2491 Objlist_Entry *elm, *listelm;
2493 STAILQ_FOREACH(listelm, list, link) {
2494 if (listelm->obj == listobj)
2497 elm = NEW(Objlist_Entry);
2499 if (listelm != NULL)
2500 STAILQ_INSERT_AFTER(list, listelm, elm, link);
2502 STAILQ_INSERT_TAIL(list, elm, link);
2506 objlist_remove(Objlist *list, Obj_Entry *obj)
2510 if ((elm = objlist_find(list, obj)) != NULL) {
2511 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2517 * Relocate dag rooted in the specified object.
2518 * Returns 0 on success, or -1 on failure.
2522 relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
2523 int flags, RtldLockState *lockstate)
2529 STAILQ_FOREACH(elm, &root->dagmembers, link) {
2530 error = relocate_object(elm->obj, bind_now, rtldobj, flags,
2539 * Relocate single object.
2540 * Returns 0 on success, or -1 on failure.
2543 relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
2544 int flags, RtldLockState *lockstate)
2549 obj->relocated = true;
2551 dbg("relocating \"%s\"", obj->path);
2553 if (obj->symtab == NULL || obj->strtab == NULL ||
2554 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2555 _rtld_error("%s: Shared object has no run-time symbol table",
2561 /* There are relocations to the write-protected text segment. */
2562 if (mprotect(obj->mapbase, obj->textsize,
2563 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2564 _rtld_error("%s: Cannot write-enable text segment: %s",
2565 obj->path, rtld_strerror(errno));
2570 /* Process the non-PLT non-IFUNC relocations. */
2571 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2574 if (obj->textrel) { /* Re-protected the text segment. */
2575 if (mprotect(obj->mapbase, obj->textsize,
2576 PROT_READ|PROT_EXEC) == -1) {
2577 _rtld_error("%s: Cannot write-protect text segment: %s",
2578 obj->path, rtld_strerror(errno));
2583 /* Set the special PLT or GOT entries. */
2586 /* Process the PLT relocations. */
2587 if (reloc_plt(obj) == -1)
2589 /* Relocate the jump slots if we are doing immediate binding. */
2590 if (obj->bind_now || bind_now)
2591 if (reloc_jmpslots(obj, flags, lockstate) == -1)
2595 * Process the non-PLT IFUNC relocations. The relocations are
2596 * processed in two phases, because IFUNC resolvers may
2597 * reference other symbols, which must be readily processed
2598 * before resolvers are called.
2600 if (obj->non_plt_gnu_ifunc &&
2601 reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate))
2604 if (obj->relro_size > 0) {
2605 if (mprotect(obj->relro_page, obj->relro_size,
2607 _rtld_error("%s: Cannot enforce relro protection: %s",
2608 obj->path, rtld_strerror(errno));
2614 * Set up the magic number and version in the Obj_Entry. These
2615 * were checked in the crt1.o from the original ElfKit, so we
2616 * set them for backward compatibility.
2618 obj->magic = RTLD_MAGIC;
2619 obj->version = RTLD_VERSION;
2625 * Relocate newly-loaded shared objects. The argument is a pointer to
2626 * the Obj_Entry for the first such object. All objects from the first
2627 * to the end of the list of objects are relocated. Returns 0 on success,
2631 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2632 int flags, RtldLockState *lockstate)
2637 for (error = 0, obj = first; obj != NULL; obj = obj->next) {
2638 error = relocate_object(obj, bind_now, rtldobj, flags,
2647 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2648 * referencing STT_GNU_IFUNC symbols is postponed till the other
2649 * relocations are done. The indirect functions specified as
2650 * ifunc are allowed to call other symbols, so we need to have
2651 * objects relocated before asking for resolution from indirects.
2653 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2654 * instead of the usual lazy handling of PLT slots. It is
2655 * consistent with how GNU does it.
2658 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2659 RtldLockState *lockstate)
2661 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2663 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2664 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2670 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2671 RtldLockState *lockstate)
2675 for (obj = first; obj != NULL; obj = obj->next) {
2676 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2683 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2684 RtldLockState *lockstate)
2688 STAILQ_FOREACH(elm, list, link) {
2689 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2697 * Cleanup procedure. It will be called (by the atexit mechanism) just
2698 * before the process exits.
2703 RtldLockState lockstate;
2705 wlock_acquire(rtld_bind_lock, &lockstate);
2707 objlist_call_fini(&list_fini, NULL, &lockstate);
2708 /* No need to remove the items from the list, since we are exiting. */
2709 if (!libmap_disable)
2711 lock_release(rtld_bind_lock, &lockstate);
2715 * Iterate over a search path, translate each element, and invoke the
2716 * callback on the result.
2719 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2725 path += strspn(path, ":;");
2726 while (*path != '\0') {
2730 len = strcspn(path, ":;");
2731 trans = lm_findn(NULL, path, len);
2733 res = callback(trans, strlen(trans), arg);
2735 res = callback(path, len, arg);
2741 path += strspn(path, ":;");
2747 struct try_library_args {
2755 try_library_path(const char *dir, size_t dirlen, void *param)
2757 struct try_library_args *arg;
2760 if (*dir == '/' || trust) {
2763 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2766 pathname = arg->buffer;
2767 strncpy(pathname, dir, dirlen);
2768 pathname[dirlen] = '/';
2769 strcpy(pathname + dirlen + 1, arg->name);
2771 dbg(" Trying \"%s\"", pathname);
2772 if (access(pathname, F_OK) == 0) { /* We found it */
2773 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2774 strcpy(pathname, arg->buffer);
2782 search_library_path(const char *name, const char *path)
2785 struct try_library_args arg;
2791 arg.namelen = strlen(name);
2792 arg.buffer = xmalloc(PATH_MAX);
2793 arg.buflen = PATH_MAX;
2795 p = path_enumerate(path, try_library_path, &arg);
2804 * Finds the library with the given name using the directory descriptors
2805 * listed in the LD_LIBRARY_PATH_FDS environment variable.
2807 * Returns a freshly-opened close-on-exec file descriptor for the library,
2808 * or -1 if the library cannot be found.
2811 search_library_pathfds(const char *name, const char *path, int *fdp)
2813 char *envcopy, *fdstr, *found, *last_token;
2817 dbg("%s('%s', '%s', fdp)", __func__, name, path);
2819 /* Don't load from user-specified libdirs into setuid binaries. */
2823 /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */
2827 /* LD_LIBRARY_PATH_FDS only works with relative paths. */
2828 if (name[0] == '/') {
2829 dbg("Absolute path (%s) passed to %s", name, __func__);
2834 * Use strtok_r() to walk the FD:FD:FD list. This requires a local
2835 * copy of the path, as strtok_r rewrites separator tokens
2839 envcopy = xstrdup(path);
2840 for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL;
2841 fdstr = strtok_r(NULL, ":", &last_token)) {
2842 dirfd = parse_libdir(fdstr);
2845 fd = __sys_openat(dirfd, name, O_RDONLY | O_CLOEXEC);
2848 len = strlen(fdstr) + strlen(name) + 3;
2849 found = xmalloc(len);
2850 if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) {
2851 _rtld_error("error generating '%d/%s'",
2855 dbg("open('%s') => %d", found, fd);
2866 dlclose(void *handle)
2869 RtldLockState lockstate;
2871 wlock_acquire(rtld_bind_lock, &lockstate);
2872 root = dlcheck(handle);
2874 lock_release(rtld_bind_lock, &lockstate);
2877 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2880 /* Unreference the object and its dependencies. */
2881 root->dl_refcount--;
2883 if (root->refcount == 1) {
2885 * The object will be no longer referenced, so we must unload it.
2886 * First, call the fini functions.
2888 objlist_call_fini(&list_fini, root, &lockstate);
2892 /* Finish cleaning up the newly-unreferenced objects. */
2893 GDB_STATE(RT_DELETE,&root->linkmap);
2894 unload_object(root);
2895 GDB_STATE(RT_CONSISTENT,NULL);
2899 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2900 lock_release(rtld_bind_lock, &lockstate);
2907 char *msg = error_message;
2908 error_message = NULL;
2913 * This function is deprecated and has no effect.
2916 dllockinit(void *context,
2917 void *(*lock_create)(void *context),
2918 void (*rlock_acquire)(void *lock),
2919 void (*wlock_acquire)(void *lock),
2920 void (*lock_release)(void *lock),
2921 void (*lock_destroy)(void *lock),
2922 void (*context_destroy)(void *context))
2924 static void *cur_context;
2925 static void (*cur_context_destroy)(void *);
2927 /* Just destroy the context from the previous call, if necessary. */
2928 if (cur_context_destroy != NULL)
2929 cur_context_destroy(cur_context);
2930 cur_context = context;
2931 cur_context_destroy = context_destroy;
2935 dlopen(const char *name, int mode)
2938 return (rtld_dlopen(name, -1, mode));
2942 fdlopen(int fd, int mode)
2945 return (rtld_dlopen(NULL, fd, mode));
2949 rtld_dlopen(const char *name, int fd, int mode)
2951 RtldLockState lockstate;
2954 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2955 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2956 if (ld_tracing != NULL) {
2957 rlock_acquire(rtld_bind_lock, &lockstate);
2958 if (sigsetjmp(lockstate.env, 0) != 0)
2959 lock_upgrade(rtld_bind_lock, &lockstate);
2960 environ = (char **)*get_program_var_addr("environ", &lockstate);
2961 lock_release(rtld_bind_lock, &lockstate);
2963 lo_flags = RTLD_LO_DLOPEN;
2964 if (mode & RTLD_NODELETE)
2965 lo_flags |= RTLD_LO_NODELETE;
2966 if (mode & RTLD_NOLOAD)
2967 lo_flags |= RTLD_LO_NOLOAD;
2968 if (ld_tracing != NULL)
2969 lo_flags |= RTLD_LO_TRACE;
2971 return (dlopen_object(name, fd, obj_main, lo_flags,
2972 mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
2976 dlopen_cleanup(Obj_Entry *obj)
2981 if (obj->refcount == 0)
2986 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
2987 int mode, RtldLockState *lockstate)
2989 Obj_Entry **old_obj_tail;
2992 RtldLockState mlockstate;
2995 objlist_init(&initlist);
2997 if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
2998 wlock_acquire(rtld_bind_lock, &mlockstate);
2999 lockstate = &mlockstate;
3001 GDB_STATE(RT_ADD,NULL);
3003 old_obj_tail = obj_tail;
3005 if (name == NULL && fd == -1) {
3009 obj = load_object(name, fd, refobj, lo_flags);
3014 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
3015 objlist_push_tail(&list_global, obj);
3016 if (*old_obj_tail != NULL) { /* We loaded something new. */
3017 assert(*old_obj_tail == obj);
3018 result = load_needed_objects(obj,
3019 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
3023 result = rtld_verify_versions(&obj->dagmembers);
3024 if (result != -1 && ld_tracing)
3026 if (result == -1 || relocate_object_dag(obj,
3027 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
3028 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3030 dlopen_cleanup(obj);
3032 } else if (lo_flags & RTLD_LO_EARLY) {
3034 * Do not call the init functions for early loaded
3035 * filtees. The image is still not initialized enough
3038 * Our object is found by the global object list and
3039 * will be ordered among all init calls done right
3040 * before transferring control to main.
3043 /* Make list of init functions to call. */
3044 initlist_add_objects(obj, &obj->next, &initlist);
3047 * Process all no_delete objects here, given them own
3048 * DAGs to prevent their dependencies from being unloaded.
3049 * This has to be done after we have loaded all of the
3050 * dependencies, so that we do not miss any.
3053 process_nodelete(obj);
3056 * Bump the reference counts for objects on this DAG. If
3057 * this is the first dlopen() call for the object that was
3058 * already loaded as a dependency, initialize the dag
3064 if ((lo_flags & RTLD_LO_TRACE) != 0)
3067 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
3068 obj->z_nodelete) && !obj->ref_nodel) {
3069 dbg("obj %s nodelete", obj->path);
3071 obj->z_nodelete = obj->ref_nodel = true;
3075 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
3077 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
3079 if (!(lo_flags & RTLD_LO_EARLY)) {
3080 map_stacks_exec(lockstate);
3083 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
3084 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3086 objlist_clear(&initlist);
3087 dlopen_cleanup(obj);
3088 if (lockstate == &mlockstate)
3089 lock_release(rtld_bind_lock, lockstate);
3093 if (!(lo_flags & RTLD_LO_EARLY)) {
3094 /* Call the init functions. */
3095 objlist_call_init(&initlist, lockstate);
3097 objlist_clear(&initlist);
3098 if (lockstate == &mlockstate)
3099 lock_release(rtld_bind_lock, lockstate);
3102 trace_loaded_objects(obj);
3103 if (lockstate == &mlockstate)
3104 lock_release(rtld_bind_lock, lockstate);
3109 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
3113 const Obj_Entry *obj, *defobj;
3116 RtldLockState lockstate;
3123 symlook_init(&req, name);
3125 req.flags = flags | SYMLOOK_IN_PLT;
3126 req.lockstate = &lockstate;
3128 LD_UTRACE(UTRACE_DLSYM_START, handle, NULL, 0, 0, name);
3129 rlock_acquire(rtld_bind_lock, &lockstate);
3130 if (sigsetjmp(lockstate.env, 0) != 0)
3131 lock_upgrade(rtld_bind_lock, &lockstate);
3132 if (handle == NULL || handle == RTLD_NEXT ||
3133 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
3135 if ((obj = obj_from_addr(retaddr)) == NULL) {
3136 _rtld_error("Cannot determine caller's shared object");
3137 lock_release(rtld_bind_lock, &lockstate);
3138 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3141 if (handle == NULL) { /* Just the caller's shared object. */
3142 res = symlook_obj(&req, obj);
3145 defobj = req.defobj_out;
3147 } else if (handle == RTLD_NEXT || /* Objects after caller's */
3148 handle == RTLD_SELF) { /* ... caller included */
3149 if (handle == RTLD_NEXT)
3151 for (; obj != NULL; obj = obj->next) {
3152 res = symlook_obj(&req, obj);
3155 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
3157 defobj = req.defobj_out;
3158 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3164 * Search the dynamic linker itself, and possibly resolve the
3165 * symbol from there. This is how the application links to
3166 * dynamic linker services such as dlopen.
3168 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3169 res = symlook_obj(&req, &obj_rtld);
3172 defobj = req.defobj_out;
3176 assert(handle == RTLD_DEFAULT);
3177 res = symlook_default(&req, obj);
3179 defobj = req.defobj_out;
3184 if ((obj = dlcheck(handle)) == NULL) {
3185 lock_release(rtld_bind_lock, &lockstate);
3186 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3190 donelist_init(&donelist);
3191 if (obj->mainprog) {
3192 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
3193 res = symlook_global(&req, &donelist);
3196 defobj = req.defobj_out;
3199 * Search the dynamic linker itself, and possibly resolve the
3200 * symbol from there. This is how the application links to
3201 * dynamic linker services such as dlopen.
3203 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3204 res = symlook_obj(&req, &obj_rtld);
3207 defobj = req.defobj_out;
3212 /* Search the whole DAG rooted at the given object. */
3213 res = symlook_list(&req, &obj->dagmembers, &donelist);
3216 defobj = req.defobj_out;
3222 lock_release(rtld_bind_lock, &lockstate);
3225 * The value required by the caller is derived from the value
3226 * of the symbol. this is simply the relocated value of the
3229 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3230 sym = make_function_pointer(def, defobj);
3231 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3232 sym = rtld_resolve_ifunc(defobj, def);
3233 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3234 ti.ti_module = defobj->tlsindex;
3235 ti.ti_offset = def->st_value;
3236 sym = __tls_get_addr(&ti);
3238 sym = defobj->relocbase + def->st_value;
3239 LD_UTRACE(UTRACE_DLSYM_STOP, handle, sym, 0, 0, name);
3243 _rtld_error("Undefined symbol \"%s\"", name);
3244 lock_release(rtld_bind_lock, &lockstate);
3245 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3250 dlsym(void *handle, const char *name)
3252 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3257 dlfunc(void *handle, const char *name)
3264 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3270 dlvsym(void *handle, const char *name, const char *version)
3274 ventry.name = version;
3276 ventry.hash = elf_hash(version);
3278 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3283 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3285 const Obj_Entry *obj;
3286 RtldLockState lockstate;
3288 rlock_acquire(rtld_bind_lock, &lockstate);
3289 obj = obj_from_addr(addr);
3291 _rtld_error("No shared object contains address");
3292 lock_release(rtld_bind_lock, &lockstate);
3295 rtld_fill_dl_phdr_info(obj, phdr_info);
3296 lock_release(rtld_bind_lock, &lockstate);
3301 dladdr(const void *addr, Dl_info *info)
3303 const Obj_Entry *obj;
3306 unsigned long symoffset;
3307 RtldLockState lockstate;
3309 rlock_acquire(rtld_bind_lock, &lockstate);
3310 obj = obj_from_addr(addr);
3312 _rtld_error("No shared object contains address");
3313 lock_release(rtld_bind_lock, &lockstate);
3316 info->dli_fname = obj->path;
3317 info->dli_fbase = obj->mapbase;
3318 info->dli_saddr = (void *)0;
3319 info->dli_sname = NULL;
3322 * Walk the symbol list looking for the symbol whose address is
3323 * closest to the address sent in.
3325 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3326 def = obj->symtab + symoffset;
3329 * For skip the symbol if st_shndx is either SHN_UNDEF or
3332 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3336 * If the symbol is greater than the specified address, or if it
3337 * is further away from addr than the current nearest symbol,
3340 symbol_addr = obj->relocbase + def->st_value;
3341 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3344 /* Update our idea of the nearest symbol. */
3345 info->dli_sname = obj->strtab + def->st_name;
3346 info->dli_saddr = symbol_addr;
3349 if (info->dli_saddr == addr)
3352 lock_release(rtld_bind_lock, &lockstate);
3357 dlinfo(void *handle, int request, void *p)
3359 const Obj_Entry *obj;
3360 RtldLockState lockstate;
3363 rlock_acquire(rtld_bind_lock, &lockstate);
3365 if (handle == NULL || handle == RTLD_SELF) {
3368 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3369 if ((obj = obj_from_addr(retaddr)) == NULL)
3370 _rtld_error("Cannot determine caller's shared object");
3372 obj = dlcheck(handle);
3375 lock_release(rtld_bind_lock, &lockstate);
3381 case RTLD_DI_LINKMAP:
3382 *((struct link_map const **)p) = &obj->linkmap;
3384 case RTLD_DI_ORIGIN:
3385 error = rtld_dirname(obj->path, p);
3388 case RTLD_DI_SERINFOSIZE:
3389 case RTLD_DI_SERINFO:
3390 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3394 _rtld_error("Invalid request %d passed to dlinfo()", request);
3398 lock_release(rtld_bind_lock, &lockstate);
3404 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3407 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3408 phdr_info->dlpi_name = obj->path;
3409 phdr_info->dlpi_phdr = obj->phdr;
3410 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3411 phdr_info->dlpi_tls_modid = obj->tlsindex;
3412 phdr_info->dlpi_tls_data = obj->tlsinit;
3413 phdr_info->dlpi_adds = obj_loads;
3414 phdr_info->dlpi_subs = obj_loads - obj_count;
3418 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3420 struct dl_phdr_info phdr_info;
3421 const Obj_Entry *obj;
3422 RtldLockState bind_lockstate, phdr_lockstate;
3425 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3426 rlock_acquire(rtld_bind_lock, &bind_lockstate);
3430 for (obj = obj_list; obj != NULL; obj = obj->next) {
3431 rtld_fill_dl_phdr_info(obj, &phdr_info);
3432 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
3437 rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info);
3438 error = callback(&phdr_info, sizeof(phdr_info), param);
3441 lock_release(rtld_bind_lock, &bind_lockstate);
3442 lock_release(rtld_phdr_lock, &phdr_lockstate);
3448 fill_search_info(const char *dir, size_t dirlen, void *param)
3450 struct fill_search_info_args *arg;
3454 if (arg->request == RTLD_DI_SERINFOSIZE) {
3455 arg->serinfo->dls_cnt ++;
3456 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3458 struct dl_serpath *s_entry;
3460 s_entry = arg->serpath;
3461 s_entry->dls_name = arg->strspace;
3462 s_entry->dls_flags = arg->flags;
3464 strncpy(arg->strspace, dir, dirlen);
3465 arg->strspace[dirlen] = '\0';
3467 arg->strspace += dirlen + 1;
3475 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3477 struct dl_serinfo _info;
3478 struct fill_search_info_args args;
3480 args.request = RTLD_DI_SERINFOSIZE;
3481 args.serinfo = &_info;
3483 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3486 path_enumerate(obj->rpath, fill_search_info, &args);
3487 path_enumerate(ld_library_path, fill_search_info, &args);
3488 path_enumerate(obj->runpath, fill_search_info, &args);
3489 path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args);
3490 if (!obj->z_nodeflib)
3491 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
3494 if (request == RTLD_DI_SERINFOSIZE) {
3495 info->dls_size = _info.dls_size;
3496 info->dls_cnt = _info.dls_cnt;
3500 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3501 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3505 args.request = RTLD_DI_SERINFO;
3506 args.serinfo = info;
3507 args.serpath = &info->dls_serpath[0];
3508 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3510 args.flags = LA_SER_RUNPATH;
3511 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3514 args.flags = LA_SER_LIBPATH;
3515 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3518 args.flags = LA_SER_RUNPATH;
3519 if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
3522 args.flags = LA_SER_CONFIG;
3523 if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args)
3527 args.flags = LA_SER_DEFAULT;
3528 if (!obj->z_nodeflib &&
3529 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3535 rtld_dirname(const char *path, char *bname)
3539 /* Empty or NULL string gets treated as "." */
3540 if (path == NULL || *path == '\0') {
3546 /* Strip trailing slashes */
3547 endp = path + strlen(path) - 1;
3548 while (endp > path && *endp == '/')
3551 /* Find the start of the dir */
3552 while (endp > path && *endp != '/')
3555 /* Either the dir is "/" or there are no slashes */
3557 bname[0] = *endp == '/' ? '/' : '.';
3563 } while (endp > path && *endp == '/');
3566 if (endp - path + 2 > PATH_MAX)
3568 _rtld_error("Filename is too long: %s", path);
3572 strncpy(bname, path, endp - path + 1);
3573 bname[endp - path + 1] = '\0';
3578 rtld_dirname_abs(const char *path, char *base)
3582 if (realpath(path, base) == NULL)
3584 dbg("%s -> %s", path, base);
3585 last = strrchr(base, '/');
3594 linkmap_add(Obj_Entry *obj)
3596 struct link_map *l = &obj->linkmap;
3597 struct link_map *prev;
3599 obj->linkmap.l_name = obj->path;
3600 obj->linkmap.l_addr = obj->mapbase;
3601 obj->linkmap.l_ld = obj->dynamic;
3603 /* GDB needs load offset on MIPS to use the symbols */
3604 obj->linkmap.l_offs = obj->relocbase;
3607 if (r_debug.r_map == NULL) {
3613 * Scan to the end of the list, but not past the entry for the
3614 * dynamic linker, which we want to keep at the very end.
3616 for (prev = r_debug.r_map;
3617 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3618 prev = prev->l_next)
3621 /* Link in the new entry. */
3623 l->l_next = prev->l_next;
3624 if (l->l_next != NULL)
3625 l->l_next->l_prev = l;
3630 linkmap_delete(Obj_Entry *obj)
3632 struct link_map *l = &obj->linkmap;
3634 if (l->l_prev == NULL) {
3635 if ((r_debug.r_map = l->l_next) != NULL)
3636 l->l_next->l_prev = NULL;
3640 if ((l->l_prev->l_next = l->l_next) != NULL)
3641 l->l_next->l_prev = l->l_prev;
3645 * Function for the debugger to set a breakpoint on to gain control.
3647 * The two parameters allow the debugger to easily find and determine
3648 * what the runtime loader is doing and to whom it is doing it.
3650 * When the loadhook trap is hit (r_debug_state, set at program
3651 * initialization), the arguments can be found on the stack:
3653 * +8 struct link_map *m
3654 * +4 struct r_debug *rd
3658 r_debug_state(struct r_debug* rd, struct link_map *m)
3661 * The following is a hack to force the compiler to emit calls to
3662 * this function, even when optimizing. If the function is empty,
3663 * the compiler is not obliged to emit any code for calls to it,
3664 * even when marked __noinline. However, gdb depends on those
3667 __compiler_membar();
3671 * A function called after init routines have completed. This can be used to
3672 * break before a program's entry routine is called, and can be used when
3673 * main is not available in the symbol table.
3676 _r_debug_postinit(struct link_map *m)
3679 /* See r_debug_state(). */
3680 __compiler_membar();
3684 * Get address of the pointer variable in the main program.
3685 * Prefer non-weak symbol over the weak one.
3687 static const void **
3688 get_program_var_addr(const char *name, RtldLockState *lockstate)
3693 symlook_init(&req, name);
3694 req.lockstate = lockstate;
3695 donelist_init(&donelist);
3696 if (symlook_global(&req, &donelist) != 0)
3698 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3699 return ((const void **)make_function_pointer(req.sym_out,
3701 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3702 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3704 return ((const void **)(req.defobj_out->relocbase +
3705 req.sym_out->st_value));
3709 * Set a pointer variable in the main program to the given value. This
3710 * is used to set key variables such as "environ" before any of the
3711 * init functions are called.
3714 set_program_var(const char *name, const void *value)
3718 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3719 dbg("\"%s\": *%p <-- %p", name, addr, value);
3725 * Search the global objects, including dependencies and main object,
3726 * for the given symbol.
3729 symlook_global(SymLook *req, DoneList *donelist)
3732 const Objlist_Entry *elm;
3735 symlook_init_from_req(&req1, req);
3737 /* Search all objects loaded at program start up. */
3738 if (req->defobj_out == NULL ||
3739 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3740 res = symlook_list(&req1, &list_main, donelist);
3741 if (res == 0 && (req->defobj_out == NULL ||
3742 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3743 req->sym_out = req1.sym_out;
3744 req->defobj_out = req1.defobj_out;
3745 assert(req->defobj_out != NULL);
3749 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3750 STAILQ_FOREACH(elm, &list_global, link) {
3751 if (req->defobj_out != NULL &&
3752 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3754 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3755 if (res == 0 && (req->defobj_out == NULL ||
3756 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3757 req->sym_out = req1.sym_out;
3758 req->defobj_out = req1.defobj_out;
3759 assert(req->defobj_out != NULL);
3763 return (req->sym_out != NULL ? 0 : ESRCH);
3767 * Given a symbol name in a referencing object, find the corresponding
3768 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3769 * no definition was found. Returns a pointer to the Obj_Entry of the
3770 * defining object via the reference parameter DEFOBJ_OUT.
3773 symlook_default(SymLook *req, const Obj_Entry *refobj)
3776 const Objlist_Entry *elm;
3780 donelist_init(&donelist);
3781 symlook_init_from_req(&req1, req);
3783 /* Look first in the referencing object if linked symbolically. */
3784 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3785 res = symlook_obj(&req1, refobj);
3787 req->sym_out = req1.sym_out;
3788 req->defobj_out = req1.defobj_out;
3789 assert(req->defobj_out != NULL);
3793 symlook_global(req, &donelist);
3795 /* Search all dlopened DAGs containing the referencing object. */
3796 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3797 if (req->sym_out != NULL &&
3798 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3800 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3801 if (res == 0 && (req->sym_out == NULL ||
3802 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3803 req->sym_out = req1.sym_out;
3804 req->defobj_out = req1.defobj_out;
3805 assert(req->defobj_out != NULL);
3810 * Search the dynamic linker itself, and possibly resolve the
3811 * symbol from there. This is how the application links to
3812 * dynamic linker services such as dlopen.
3814 if (req->sym_out == NULL ||
3815 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3816 res = symlook_obj(&req1, &obj_rtld);
3818 req->sym_out = req1.sym_out;
3819 req->defobj_out = req1.defobj_out;
3820 assert(req->defobj_out != NULL);
3824 return (req->sym_out != NULL ? 0 : ESRCH);
3828 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3831 const Obj_Entry *defobj;
3832 const Objlist_Entry *elm;
3838 STAILQ_FOREACH(elm, objlist, link) {
3839 if (donelist_check(dlp, elm->obj))
3841 symlook_init_from_req(&req1, req);
3842 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3843 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3845 defobj = req1.defobj_out;
3846 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3853 req->defobj_out = defobj;
3860 * Search the chain of DAGS cointed to by the given Needed_Entry
3861 * for a symbol of the given name. Each DAG is scanned completely
3862 * before advancing to the next one. Returns a pointer to the symbol,
3863 * or NULL if no definition was found.
3866 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3869 const Needed_Entry *n;
3870 const Obj_Entry *defobj;
3876 symlook_init_from_req(&req1, req);
3877 for (n = needed; n != NULL; n = n->next) {
3878 if (n->obj == NULL ||
3879 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3881 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3883 defobj = req1.defobj_out;
3884 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3890 req->defobj_out = defobj;
3897 * Search the symbol table of a single shared object for a symbol of
3898 * the given name and version, if requested. Returns a pointer to the
3899 * symbol, or NULL if no definition was found. If the object is
3900 * filter, return filtered symbol from filtee.
3902 * The symbol's hash value is passed in for efficiency reasons; that
3903 * eliminates many recomputations of the hash value.
3906 symlook_obj(SymLook *req, const Obj_Entry *obj)
3910 int flags, res, mres;
3913 * If there is at least one valid hash at this point, we prefer to
3914 * use the faster GNU version if available.
3916 if (obj->valid_hash_gnu)
3917 mres = symlook_obj1_gnu(req, obj);
3918 else if (obj->valid_hash_sysv)
3919 mres = symlook_obj1_sysv(req, obj);
3924 if (obj->needed_filtees != NULL) {
3925 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3926 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3927 donelist_init(&donelist);
3928 symlook_init_from_req(&req1, req);
3929 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3931 req->sym_out = req1.sym_out;
3932 req->defobj_out = req1.defobj_out;
3936 if (obj->needed_aux_filtees != NULL) {
3937 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3938 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3939 donelist_init(&donelist);
3940 symlook_init_from_req(&req1, req);
3941 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3943 req->sym_out = req1.sym_out;
3944 req->defobj_out = req1.defobj_out;
3952 /* Symbol match routine common to both hash functions */
3954 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
3955 const unsigned long symnum)
3958 const Elf_Sym *symp;
3961 symp = obj->symtab + symnum;
3962 strp = obj->strtab + symp->st_name;
3964 switch (ELF_ST_TYPE(symp->st_info)) {
3970 if (symp->st_value == 0)
3974 if (symp->st_shndx != SHN_UNDEF)
3977 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3978 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3985 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
3988 if (req->ventry == NULL) {
3989 if (obj->versyms != NULL) {
3990 verndx = VER_NDX(obj->versyms[symnum]);
3991 if (verndx > obj->vernum) {
3993 "%s: symbol %s references wrong version %d",
3994 obj->path, obj->strtab + symnum, verndx);
3998 * If we are not called from dlsym (i.e. this
3999 * is a normal relocation from unversioned
4000 * binary), accept the symbol immediately if
4001 * it happens to have first version after this
4002 * shared object became versioned. Otherwise,
4003 * if symbol is versioned and not hidden,
4004 * remember it. If it is the only symbol with
4005 * this name exported by the shared object, it
4006 * will be returned as a match by the calling
4007 * function. If symbol is global (verndx < 2)
4008 * accept it unconditionally.
4010 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
4011 verndx == VER_NDX_GIVEN) {
4012 result->sym_out = symp;
4015 else if (verndx >= VER_NDX_GIVEN) {
4016 if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
4018 if (result->vsymp == NULL)
4019 result->vsymp = symp;
4025 result->sym_out = symp;
4028 if (obj->versyms == NULL) {
4029 if (object_match_name(obj, req->ventry->name)) {
4030 _rtld_error("%s: object %s should provide version %s "
4031 "for symbol %s", obj_rtld.path, obj->path,
4032 req->ventry->name, obj->strtab + symnum);
4036 verndx = VER_NDX(obj->versyms[symnum]);
4037 if (verndx > obj->vernum) {
4038 _rtld_error("%s: symbol %s references wrong version %d",
4039 obj->path, obj->strtab + symnum, verndx);
4042 if (obj->vertab[verndx].hash != req->ventry->hash ||
4043 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
4045 * Version does not match. Look if this is a
4046 * global symbol and if it is not hidden. If
4047 * global symbol (verndx < 2) is available,
4048 * use it. Do not return symbol if we are
4049 * called by dlvsym, because dlvsym looks for
4050 * a specific version and default one is not
4051 * what dlvsym wants.
4053 if ((req->flags & SYMLOOK_DLSYM) ||
4054 (verndx >= VER_NDX_GIVEN) ||
4055 (obj->versyms[symnum] & VER_NDX_HIDDEN))
4059 result->sym_out = symp;
4064 * Search for symbol using SysV hash function.
4065 * obj->buckets is known not to be NULL at this point; the test for this was
4066 * performed with the obj->valid_hash_sysv assignment.
4069 symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj)
4071 unsigned long symnum;
4072 Sym_Match_Result matchres;
4074 matchres.sym_out = NULL;
4075 matchres.vsymp = NULL;
4076 matchres.vcount = 0;
4078 for (symnum = obj->buckets[req->hash % obj->nbuckets];
4079 symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
4080 if (symnum >= obj->nchains)
4081 return (ESRCH); /* Bad object */
4083 if (matched_symbol(req, obj, &matchres, symnum)) {
4084 req->sym_out = matchres.sym_out;
4085 req->defobj_out = obj;
4089 if (matchres.vcount == 1) {
4090 req->sym_out = matchres.vsymp;
4091 req->defobj_out = obj;
4097 /* Search for symbol using GNU hash function */
4099 symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj)
4101 Elf_Addr bloom_word;
4102 const Elf32_Word *hashval;
4104 Sym_Match_Result matchres;
4105 unsigned int h1, h2;
4106 unsigned long symnum;
4108 matchres.sym_out = NULL;
4109 matchres.vsymp = NULL;
4110 matchres.vcount = 0;
4112 /* Pick right bitmask word from Bloom filter array */
4113 bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) &
4114 obj->maskwords_bm_gnu];
4116 /* Calculate modulus word size of gnu hash and its derivative */
4117 h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1);
4118 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1));
4120 /* Filter out the "definitely not in set" queries */
4121 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
4124 /* Locate hash chain and corresponding value element*/
4125 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
4128 hashval = &obj->chain_zero_gnu[bucket];
4130 if (((*hashval ^ req->hash_gnu) >> 1) == 0) {
4131 symnum = hashval - obj->chain_zero_gnu;
4132 if (matched_symbol(req, obj, &matchres, symnum)) {
4133 req->sym_out = matchres.sym_out;
4134 req->defobj_out = obj;
4138 } while ((*hashval++ & 1) == 0);
4139 if (matchres.vcount == 1) {
4140 req->sym_out = matchres.vsymp;
4141 req->defobj_out = obj;
4148 trace_loaded_objects(Obj_Entry *obj)
4150 char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
4153 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
4156 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL)
4157 fmt1 = "\t%o => %p (%x)\n";
4159 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL)
4160 fmt2 = "\t%o (%x)\n";
4162 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL");
4164 for (; obj; obj = obj->next) {
4165 Needed_Entry *needed;
4169 if (list_containers && obj->needed != NULL)
4170 rtld_printf("%s:\n", obj->path);
4171 for (needed = obj->needed; needed; needed = needed->next) {
4172 if (needed->obj != NULL) {
4173 if (needed->obj->traced && !list_containers)
4175 needed->obj->traced = true;
4176 path = needed->obj->path;
4180 name = (char *)obj->strtab + needed->name;
4181 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
4183 fmt = is_lib ? fmt1 : fmt2;
4184 while ((c = *fmt++) != '\0') {
4210 rtld_putstr(main_local);
4213 rtld_putstr(obj_main->path);
4220 rtld_printf("%d", sodp->sod_major);
4223 rtld_printf("%d", sodp->sod_minor);
4230 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4243 * Unload a dlopened object and its dependencies from memory and from
4244 * our data structures. It is assumed that the DAG rooted in the
4245 * object has already been unreferenced, and that the object has a
4246 * reference count of 0.
4249 unload_object(Obj_Entry *root)
4254 assert(root->refcount == 0);
4257 * Pass over the DAG removing unreferenced objects from
4258 * appropriate lists.
4260 unlink_object(root);
4262 /* Unmap all objects that are no longer referenced. */
4263 linkp = &obj_list->next;
4264 while ((obj = *linkp) != NULL) {
4265 if (obj->refcount == 0) {
4266 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
4268 dbg("unloading \"%s\"", obj->path);
4269 unload_filtees(root);
4270 munmap(obj->mapbase, obj->mapsize);
4271 linkmap_delete(obj);
4282 unlink_object(Obj_Entry *root)
4286 if (root->refcount == 0) {
4287 /* Remove the object from the RTLD_GLOBAL list. */
4288 objlist_remove(&list_global, root);
4290 /* Remove the object from all objects' DAG lists. */
4291 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4292 objlist_remove(&elm->obj->dldags, root);
4293 if (elm->obj != root)
4294 unlink_object(elm->obj);
4300 ref_dag(Obj_Entry *root)
4304 assert(root->dag_inited);
4305 STAILQ_FOREACH(elm, &root->dagmembers, link)
4306 elm->obj->refcount++;
4310 unref_dag(Obj_Entry *root)
4314 assert(root->dag_inited);
4315 STAILQ_FOREACH(elm, &root->dagmembers, link)
4316 elm->obj->refcount--;
4320 * Common code for MD __tls_get_addr().
4322 static void *tls_get_addr_slow(Elf_Addr **, int, size_t) __noinline;
4324 tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
4326 Elf_Addr *newdtv, *dtv;
4327 RtldLockState lockstate;
4331 /* Check dtv generation in case new modules have arrived */
4332 if (dtv[0] != tls_dtv_generation) {
4333 wlock_acquire(rtld_bind_lock, &lockstate);
4334 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4336 if (to_copy > tls_max_index)
4337 to_copy = tls_max_index;
4338 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4339 newdtv[0] = tls_dtv_generation;
4340 newdtv[1] = tls_max_index;
4342 lock_release(rtld_bind_lock, &lockstate);
4343 dtv = *dtvp = newdtv;
4346 /* Dynamically allocate module TLS if necessary */
4347 if (dtv[index + 1] == 0) {
4348 /* Signal safe, wlock will block out signals. */
4349 wlock_acquire(rtld_bind_lock, &lockstate);
4350 if (!dtv[index + 1])
4351 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4352 lock_release(rtld_bind_lock, &lockstate);
4354 return ((void *)(dtv[index + 1] + offset));
4358 tls_get_addr_common(Elf_Addr **dtvp, int index, size_t offset)
4363 /* Check dtv generation in case new modules have arrived */
4364 if (__predict_true(dtv[0] == tls_dtv_generation &&
4365 dtv[index + 1] != 0))
4366 return ((void *)(dtv[index + 1] + offset));
4367 return (tls_get_addr_slow(dtvp, index, offset));
4370 #if defined(__aarch64__) || defined(__arm__) || defined(__mips__) || \
4371 defined(__powerpc__)
4374 * Allocate Static TLS using the Variant I method.
4377 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
4386 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
4389 assert(tcbsize >= TLS_TCB_SIZE);
4390 tcb = xcalloc(1, tls_static_space - TLS_TCB_SIZE + tcbsize);
4391 tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE);
4393 if (oldtcb != NULL) {
4394 memcpy(tls, oldtcb, tls_static_space);
4397 /* Adjust the DTV. */
4399 for (i = 0; i < dtv[1]; i++) {
4400 if (dtv[i+2] >= (Elf_Addr)oldtcb &&
4401 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) {
4402 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tls;
4406 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4408 dtv[0] = tls_dtv_generation;
4409 dtv[1] = tls_max_index;
4411 for (obj = objs; obj; obj = obj->next) {
4412 if (obj->tlsoffset > 0) {
4413 addr = (Elf_Addr)tls + obj->tlsoffset;
4414 if (obj->tlsinitsize > 0)
4415 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4416 if (obj->tlssize > obj->tlsinitsize)
4417 memset((void*) (addr + obj->tlsinitsize), 0,
4418 obj->tlssize - obj->tlsinitsize);
4419 dtv[obj->tlsindex + 1] = addr;
4428 free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
4431 Elf_Addr tlsstart, tlsend;
4434 assert(tcbsize >= TLS_TCB_SIZE);
4436 tlsstart = (Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE;
4437 tlsend = tlsstart + tls_static_space;
4439 dtv = *(Elf_Addr **)tlsstart;
4441 for (i = 0; i < dtvsize; i++) {
4442 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) {
4443 free((void*)dtv[i+2]);
4452 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__)
4455 * Allocate Static TLS using the Variant II method.
4458 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
4461 size_t size, ralign;
4463 Elf_Addr *dtv, *olddtv;
4464 Elf_Addr segbase, oldsegbase, addr;
4468 if (tls_static_max_align > ralign)
4469 ralign = tls_static_max_align;
4470 size = round(tls_static_space, ralign) + round(tcbsize, ralign);
4472 assert(tcbsize >= 2*sizeof(Elf_Addr));
4473 tls = malloc_aligned(size, ralign);
4474 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4476 segbase = (Elf_Addr)(tls + round(tls_static_space, ralign));
4477 ((Elf_Addr*)segbase)[0] = segbase;
4478 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
4480 dtv[0] = tls_dtv_generation;
4481 dtv[1] = tls_max_index;
4485 * Copy the static TLS block over whole.
4487 oldsegbase = (Elf_Addr) oldtls;
4488 memcpy((void *)(segbase - tls_static_space),
4489 (const void *)(oldsegbase - tls_static_space),
4493 * If any dynamic TLS blocks have been created tls_get_addr(),
4496 olddtv = ((Elf_Addr**)oldsegbase)[1];
4497 for (i = 0; i < olddtv[1]; i++) {
4498 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) {
4499 dtv[i+2] = olddtv[i+2];
4505 * We assume that this block was the one we created with
4506 * allocate_initial_tls().
4508 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
4510 for (obj = objs; obj; obj = obj->next) {
4511 if (obj->tlsoffset) {
4512 addr = segbase - obj->tlsoffset;
4513 memset((void*) (addr + obj->tlsinitsize),
4514 0, obj->tlssize - obj->tlsinitsize);
4516 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4517 dtv[obj->tlsindex + 1] = addr;
4522 return (void*) segbase;
4526 free_tls(void *tls, size_t tcbsize, size_t tcbalign)
4529 size_t size, ralign;
4531 Elf_Addr tlsstart, tlsend;
4534 * Figure out the size of the initial TLS block so that we can
4535 * find stuff which ___tls_get_addr() allocated dynamically.
4538 if (tls_static_max_align > ralign)
4539 ralign = tls_static_max_align;
4540 size = round(tls_static_space, ralign);
4542 dtv = ((Elf_Addr**)tls)[1];
4544 tlsend = (Elf_Addr) tls;
4545 tlsstart = tlsend - size;
4546 for (i = 0; i < dtvsize; i++) {
4547 if (dtv[i + 2] != 0 && (dtv[i + 2] < tlsstart || dtv[i + 2] > tlsend)) {
4548 free_aligned((void *)dtv[i + 2]);
4552 free_aligned((void *)tlsstart);
4559 * Allocate TLS block for module with given index.
4562 allocate_module_tls(int index)
4567 for (obj = obj_list; obj; obj = obj->next) {
4568 if (obj->tlsindex == index)
4572 _rtld_error("Can't find module with TLS index %d", index);
4576 p = malloc_aligned(obj->tlssize, obj->tlsalign);
4577 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4578 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4584 allocate_tls_offset(Obj_Entry *obj)
4591 if (obj->tlssize == 0) {
4592 obj->tls_done = true;
4596 if (obj->tlsindex == 1)
4597 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4599 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4600 obj->tlssize, obj->tlsalign);
4603 * If we have already fixed the size of the static TLS block, we
4604 * must stay within that size. When allocating the static TLS, we
4605 * leave a small amount of space spare to be used for dynamically
4606 * loading modules which use static TLS.
4608 if (tls_static_space != 0) {
4609 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4611 } else if (obj->tlsalign > tls_static_max_align) {
4612 tls_static_max_align = obj->tlsalign;
4615 tls_last_offset = obj->tlsoffset = off;
4616 tls_last_size = obj->tlssize;
4617 obj->tls_done = true;
4623 free_tls_offset(Obj_Entry *obj)
4627 * If we were the last thing to allocate out of the static TLS
4628 * block, we give our space back to the 'allocator'. This is a
4629 * simplistic workaround to allow libGL.so.1 to be loaded and
4630 * unloaded multiple times.
4632 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
4633 == calculate_tls_end(tls_last_offset, tls_last_size)) {
4634 tls_last_offset -= obj->tlssize;
4640 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
4643 RtldLockState lockstate;
4645 wlock_acquire(rtld_bind_lock, &lockstate);
4646 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign);
4647 lock_release(rtld_bind_lock, &lockstate);
4652 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
4654 RtldLockState lockstate;
4656 wlock_acquire(rtld_bind_lock, &lockstate);
4657 free_tls(tcb, tcbsize, tcbalign);
4658 lock_release(rtld_bind_lock, &lockstate);
4662 object_add_name(Obj_Entry *obj, const char *name)
4668 entry = malloc(sizeof(Name_Entry) + len);
4670 if (entry != NULL) {
4671 strcpy(entry->name, name);
4672 STAILQ_INSERT_TAIL(&obj->names, entry, link);
4677 object_match_name(const Obj_Entry *obj, const char *name)
4681 STAILQ_FOREACH(entry, &obj->names, link) {
4682 if (strcmp(name, entry->name) == 0)
4689 locate_dependency(const Obj_Entry *obj, const char *name)
4691 const Objlist_Entry *entry;
4692 const Needed_Entry *needed;
4694 STAILQ_FOREACH(entry, &list_main, link) {
4695 if (object_match_name(entry->obj, name))
4699 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4700 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4701 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4703 * If there is DT_NEEDED for the name we are looking for,
4704 * we are all set. Note that object might not be found if
4705 * dependency was not loaded yet, so the function can
4706 * return NULL here. This is expected and handled
4707 * properly by the caller.
4709 return (needed->obj);
4712 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4718 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4719 const Elf_Vernaux *vna)
4721 const Elf_Verdef *vd;
4722 const char *vername;
4724 vername = refobj->strtab + vna->vna_name;
4725 vd = depobj->verdef;
4727 _rtld_error("%s: version %s required by %s not defined",
4728 depobj->path, vername, refobj->path);
4732 if (vd->vd_version != VER_DEF_CURRENT) {
4733 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4734 depobj->path, vd->vd_version);
4737 if (vna->vna_hash == vd->vd_hash) {
4738 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4739 ((char *)vd + vd->vd_aux);
4740 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4743 if (vd->vd_next == 0)
4745 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4747 if (vna->vna_flags & VER_FLG_WEAK)
4749 _rtld_error("%s: version %s required by %s not found",
4750 depobj->path, vername, refobj->path);
4755 rtld_verify_object_versions(Obj_Entry *obj)
4757 const Elf_Verneed *vn;
4758 const Elf_Verdef *vd;
4759 const Elf_Verdaux *vda;
4760 const Elf_Vernaux *vna;
4761 const Obj_Entry *depobj;
4762 int maxvernum, vernum;
4764 if (obj->ver_checked)
4766 obj->ver_checked = true;
4770 * Walk over defined and required version records and figure out
4771 * max index used by any of them. Do very basic sanity checking
4775 while (vn != NULL) {
4776 if (vn->vn_version != VER_NEED_CURRENT) {
4777 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4778 obj->path, vn->vn_version);
4781 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4783 vernum = VER_NEED_IDX(vna->vna_other);
4784 if (vernum > maxvernum)
4786 if (vna->vna_next == 0)
4788 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4790 if (vn->vn_next == 0)
4792 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4796 while (vd != NULL) {
4797 if (vd->vd_version != VER_DEF_CURRENT) {
4798 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4799 obj->path, vd->vd_version);
4802 vernum = VER_DEF_IDX(vd->vd_ndx);
4803 if (vernum > maxvernum)
4805 if (vd->vd_next == 0)
4807 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4814 * Store version information in array indexable by version index.
4815 * Verify that object version requirements are satisfied along the
4818 obj->vernum = maxvernum + 1;
4819 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
4822 while (vd != NULL) {
4823 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4824 vernum = VER_DEF_IDX(vd->vd_ndx);
4825 assert(vernum <= maxvernum);
4826 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4827 obj->vertab[vernum].hash = vd->vd_hash;
4828 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4829 obj->vertab[vernum].file = NULL;
4830 obj->vertab[vernum].flags = 0;
4832 if (vd->vd_next == 0)
4834 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4838 while (vn != NULL) {
4839 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4842 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4844 if (check_object_provided_version(obj, depobj, vna))
4846 vernum = VER_NEED_IDX(vna->vna_other);
4847 assert(vernum <= maxvernum);
4848 obj->vertab[vernum].hash = vna->vna_hash;
4849 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4850 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4851 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4852 VER_INFO_HIDDEN : 0;
4853 if (vna->vna_next == 0)
4855 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4857 if (vn->vn_next == 0)
4859 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4865 rtld_verify_versions(const Objlist *objlist)
4867 Objlist_Entry *entry;
4871 STAILQ_FOREACH(entry, objlist, link) {
4873 * Skip dummy objects or objects that have their version requirements
4876 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4878 if (rtld_verify_object_versions(entry->obj) == -1) {
4880 if (ld_tracing == NULL)
4884 if (rc == 0 || ld_tracing != NULL)
4885 rc = rtld_verify_object_versions(&obj_rtld);
4890 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4895 vernum = VER_NDX(obj->versyms[symnum]);
4896 if (vernum >= obj->vernum) {
4897 _rtld_error("%s: symbol %s has wrong verneed value %d",
4898 obj->path, obj->strtab + symnum, vernum);
4899 } else if (obj->vertab[vernum].hash != 0) {
4900 return &obj->vertab[vernum];
4907 _rtld_get_stack_prot(void)
4910 return (stack_prot);
4914 _rtld_is_dlopened(void *arg)
4917 RtldLockState lockstate;
4920 rlock_acquire(rtld_bind_lock, &lockstate);
4923 obj = obj_from_addr(arg);
4925 _rtld_error("No shared object contains address");
4926 lock_release(rtld_bind_lock, &lockstate);
4929 res = obj->dlopened ? 1 : 0;
4930 lock_release(rtld_bind_lock, &lockstate);
4935 map_stacks_exec(RtldLockState *lockstate)
4937 void (*thr_map_stacks_exec)(void);
4939 if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4941 thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4942 get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4943 if (thr_map_stacks_exec != NULL) {
4944 stack_prot |= PROT_EXEC;
4945 thr_map_stacks_exec();
4950 symlook_init(SymLook *dst, const char *name)
4953 bzero(dst, sizeof(*dst));
4955 dst->hash = elf_hash(name);
4956 dst->hash_gnu = gnu_hash(name);
4960 symlook_init_from_req(SymLook *dst, const SymLook *src)
4963 dst->name = src->name;
4964 dst->hash = src->hash;
4965 dst->hash_gnu = src->hash_gnu;
4966 dst->ventry = src->ventry;
4967 dst->flags = src->flags;
4968 dst->defobj_out = NULL;
4969 dst->sym_out = NULL;
4970 dst->lockstate = src->lockstate;
4975 * Parse a file descriptor number without pulling in more of libc (e.g. atoi).
4978 parse_libdir(const char *str)
4980 static const int RADIX = 10; /* XXXJA: possibly support hex? */
4987 for (c = *str; c != '\0'; c = *++str) {
4988 if (c < '0' || c > '9')
4995 /* Make sure we actually parsed something. */
4997 _rtld_error("failed to parse directory FD from '%s'", str);
5004 * Overrides for libc_pic-provided functions.
5008 __getosreldate(void)
5018 oid[1] = KERN_OSRELDATE;
5020 len = sizeof(osrel);
5021 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
5022 if (error == 0 && osrel > 0 && len == sizeof(osrel))
5034 void (*__cleanup)(void);
5035 int __isthreaded = 0;
5036 int _thread_autoinit_dummy_decl = 1;
5039 * No unresolved symbols for rtld.
5042 __pthread_cxa_finalize(struct dl_phdr_info *a)
5047 __stack_chk_fail(void)
5050 _rtld_error("stack overflow detected; terminated");
5053 __weak_reference(__stack_chk_fail, __stack_chk_fail_local);
5059 _rtld_error("buffer overflow detected; terminated");
5064 rtld_strerror(int errnum)
5067 if (errnum < 0 || errnum >= sys_nerr)
5068 return ("Unknown error");
5069 return (sys_errlist[errnum]);