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>
49 #include <sys/resident.h>
52 #include <machine/tls.h>
67 #include "rtld_printf.h"
70 #define PATH_RTLD "/usr/libexec/ld-elf.so.2"
71 #define LD_ARY_CACHE 16
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 *_getenv_ld(const char *id);
81 static void die(void) __dead2;
82 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
83 const Elf_Dyn **, const Elf_Dyn **);
84 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
86 static void digest_dynamic(Obj_Entry *, int);
87 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
88 static Obj_Entry *dlcheck(void *);
89 static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
90 int lo_flags, int mode, RtldLockState *lockstate);
91 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
92 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
93 static bool donelist_check(DoneList *, const Obj_Entry *);
94 static void errmsg_restore(char *);
95 static char *errmsg_save(void);
96 static void *fill_search_info(const char *, size_t, void *);
97 static char *find_library(const char *, const Obj_Entry *, int *);
98 static const char *gethints(bool);
99 static void init_dag(Obj_Entry *);
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 uint_fast32_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;
166 void _r_debug_postinit(struct link_map *) __noinline;
171 static char *error_message; /* Message for dlerror(), or NULL */
172 struct r_debug r_debug; /* for GDB; */
173 static bool libmap_disable; /* Disable libmap */
174 static bool ld_loadfltr; /* Immediate filters processing */
175 static char *libmap_override; /* Maps to use in addition to libmap.conf */
176 static bool trust; /* False for setuid and setgid programs */
177 static bool dangerous_ld_env; /* True if environment variables have been
178 used to affect the libraries loaded */
179 static const char *ld_bind_now; /* Environment variable for immediate binding */
180 static const char *ld_debug; /* Environment variable for debugging */
181 static const char *ld_library_path; /* Environment variable for search path */
182 static const char *ld_library_dirs; /* Env variable for library descriptors */
183 static char *ld_preload; /* Environment variable for libraries to
185 static const char *ld_elf_hints_path; /* Env var. for alternative hints path */
186 static const char *ld_tracing; /* Called from ldd to print libs */
187 static const char *ld_utrace; /* Use utrace() to log events. */
188 static int (*rtld_functrace)( /* Optional function call tracing hook */
189 const char *caller_obj,
190 const char *callee_obj,
191 const char *callee_func,
193 static const Obj_Entry *rtld_functrace_obj; /* Object thereof */
194 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
195 static Obj_Entry **obj_tail; /* Link field of last object in list */
196 static Obj_Entry **preload_tail;
197 static Obj_Entry *obj_main; /* The main program shared object */
198 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
199 static unsigned int obj_count; /* Number of objects in obj_list */
200 static unsigned int obj_loads; /* Number of objects in obj_list */
202 static int ld_resident; /* Non-zero if resident */
203 static const char *ld_ary[LD_ARY_CACHE];
205 static Objlist initlist;
207 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
208 STAILQ_HEAD_INITIALIZER(list_global);
209 static Objlist list_main = /* Objects loaded at program startup */
210 STAILQ_HEAD_INITIALIZER(list_main);
211 static Objlist list_fini = /* Objects needing fini() calls */
212 STAILQ_HEAD_INITIALIZER(list_fini);
214 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
215 const char *__ld_sharedlib_base;
217 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
219 extern Elf_Dyn _DYNAMIC;
220 #pragma weak _DYNAMIC
221 #ifndef RTLD_IS_DYNAMIC
222 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
225 #ifdef ENABLE_OSRELDATE
229 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
231 static int max_stack_flags;
235 * Global declarations normally provided by crt1. The dynamic linker is
236 * not built with crt1, so we have to provide them ourselves.
242 * Used to pass argc, argv to init functions.
248 * Globals to control TLS allocation.
250 size_t tls_last_offset; /* Static TLS offset of last module */
251 size_t tls_last_size; /* Static TLS size of last module */
252 size_t tls_static_space; /* Static TLS space allocated */
253 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
254 int tls_max_index = 1; /* Largest module index allocated */
257 * Fill in a DoneList with an allocation large enough to hold all of
258 * the currently-loaded objects. Keep this as a macro since it calls
259 * alloca and we want that to occur within the scope of the caller.
261 #define donelist_init(dlp) \
262 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
263 assert((dlp)->objs != NULL), \
264 (dlp)->num_alloc = obj_count, \
267 #define UTRACE_DLOPEN_START 1
268 #define UTRACE_DLOPEN_STOP 2
269 #define UTRACE_DLCLOSE_START 3
270 #define UTRACE_DLCLOSE_STOP 4
271 #define UTRACE_LOAD_OBJECT 5
272 #define UTRACE_UNLOAD_OBJECT 6
273 #define UTRACE_ADD_RUNDEP 7
274 #define UTRACE_PRELOAD_FINISHED 8
275 #define UTRACE_INIT_CALL 9
276 #define UTRACE_FINI_CALL 10
279 char sig[4]; /* 'RTLD' */
282 void *mapbase; /* Used for 'parent' and 'init/fini' */
284 int refcnt; /* Used for 'mode' */
285 char name[MAXPATHLEN];
288 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
289 if (ld_utrace != NULL) \
290 ld_utrace_log(e, h, mb, ms, r, n); \
294 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
295 int refcnt, const char *name)
297 struct utrace_rtld ut;
305 ut.mapbase = mapbase;
306 ut.mapsize = mapsize;
308 bzero(ut.name, sizeof(ut.name));
310 strlcpy(ut.name, name, sizeof(ut.name));
311 utrace(&ut, sizeof(ut));
315 * Main entry point for dynamic linking. The first argument is the
316 * stack pointer. The stack is expected to be laid out as described
317 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
318 * Specifically, the stack pointer points to a word containing
319 * ARGC. Following that in the stack is a null-terminated sequence
320 * of pointers to argument strings. Then comes a null-terminated
321 * sequence of pointers to environment strings. Finally, there is a
322 * sequence of "auxiliary vector" entries.
324 * The second argument points to a place to store the dynamic linker's
325 * exit procedure pointer and the third to a place to store the main
328 * The return value is the main program's entry point.
331 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
333 Elf_Auxinfo *aux_info[AT_COUNT];
341 Objlist_Entry *entry;
343 Obj_Entry *last_interposer;
345 /* marino: DO NOT MOVE THESE VARIABLES TO _rtld
346 Obj_Entry **preload_tail;
348 from global to here. It will break the DWARF2 unwind scheme.
352 * On entry, the dynamic linker itself has not been relocated yet.
353 * Be very careful not to reference any global data until after
354 * init_rtld has returned. It is OK to reference file-scope statics
355 * and string constants, and to call static and global functions.
358 /* Find the auxiliary vector on the stack. */
361 sp += argc + 1; /* Skip over arguments and NULL terminator */
365 * If we aren't already resident we have to dig out some more info.
366 * Note that auxinfo does not exist when we are resident.
368 * I'm not sure about the ld_resident check. It seems to read zero
369 * prior to relocation, which is what we want. When running from a
370 * resident copy everything will be relocated so we are definitely
373 if (ld_resident == 0) {
374 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
376 aux = (Elf_Auxinfo *) sp;
378 /* Digest the auxiliary vector. */
379 for (i = 0; i < AT_COUNT; i++)
381 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
382 if (auxp->a_type < AT_COUNT)
383 aux_info[auxp->a_type] = auxp;
386 /* Initialize and relocate ourselves. */
387 assert(aux_info[AT_BASE] != NULL);
388 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
391 ld_index = 0; /* don't use old env cache in case we are resident */
392 __progname = obj_rtld.path;
393 argv0 = argv[0] != NULL ? argv[0] : "(null)";
398 trust = !issetugid();
400 ld_bind_now = _getenv_ld("LD_BIND_NOW");
402 * If the process is tainted, then we un-set the dangerous environment
403 * variables. The process will be marked as tainted until setuid(2)
404 * is called. If any child process calls setuid(2) we do not want any
405 * future processes to honor the potentially un-safe variables.
408 if ( unsetenv("LD_DEBUG")
409 || unsetenv("LD_PRELOAD")
410 || unsetenv("LD_LIBRARY_PATH")
411 || unsetenv("LD_LIBRARY_PATH_FDS")
412 || unsetenv("LD_ELF_HINTS_PATH")
413 || unsetenv("LD_LIBMAP")
414 || unsetenv("LD_LIBMAP_DISABLE")
415 || unsetenv("LD_LOADFLTR")
416 || unsetenv("LD_SHAREDLIB_BASE")
418 _rtld_error("environment corrupt; aborting");
422 __ld_sharedlib_base = _getenv_ld("LD_SHAREDLIB_BASE");
423 ld_debug = _getenv_ld("LD_DEBUG");
424 libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL;
425 libmap_override = (char *)_getenv_ld("LD_LIBMAP");
426 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
427 ld_library_dirs = _getenv_ld("LD_LIBRARY_PATH_FDS");
428 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
429 ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH");
430 ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL;
431 dangerous_ld_env = (ld_library_path != NULL)
432 || (ld_preload != NULL)
433 || (ld_elf_hints_path != NULL)
435 || (libmap_override != NULL)
438 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
439 ld_utrace = _getenv_ld("LD_UTRACE");
441 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
442 ld_elf_hints_path = _PATH_ELF_HINTS;
444 if (ld_debug != NULL && *ld_debug != '\0')
446 dbg("%s is initialized, base address = %p", __progname,
447 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
448 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
449 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
451 dbg("initializing thread locks");
455 * If we are resident we can skip work that we have already done.
456 * Note that the stack is reset and there is no Elf_Auxinfo
457 * when running from a resident image, and the static globals setup
458 * between here and resident_skip will have already been setup.
464 * Load the main program, or process its program header if it is
467 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
468 int fd = aux_info[AT_EXECFD]->a_un.a_val;
469 dbg("loading main program");
470 obj_main = map_object(fd, argv0, NULL);
472 if (obj_main == NULL)
475 max_stack_flags = obj_main->stack_flags;
477 } else { /* Main program already loaded. */
478 const Elf_Phdr *phdr;
482 dbg("processing main program's program header");
483 assert(aux_info[AT_PHDR] != NULL);
484 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
485 assert(aux_info[AT_PHNUM] != NULL);
486 phnum = aux_info[AT_PHNUM]->a_un.a_val;
487 assert(aux_info[AT_PHENT] != NULL);
488 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
489 assert(aux_info[AT_ENTRY] != NULL);
490 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
491 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
495 char buf[MAXPATHLEN];
496 if (aux_info[AT_EXECPATH] != NULL) {
499 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
500 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
501 if (kexecpath[0] == '/')
502 obj_main->path = kexecpath;
503 else if (getcwd(buf, sizeof(buf)) == NULL ||
504 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
505 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
506 obj_main->path = xstrdup(argv0);
508 obj_main->path = xstrdup(buf);
510 char resolved[MAXPATHLEN];
511 dbg("No AT_EXECPATH");
512 if (argv0[0] == '/') {
513 if (realpath(argv0, resolved) != NULL)
514 obj_main->path = xstrdup(resolved);
516 obj_main->path = xstrdup(argv0);
518 if (getcwd(buf, sizeof(buf)) != NULL
519 && strlcat(buf, "/", sizeof(buf)) < sizeof(buf)
520 && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf)
521 && access(buf, R_OK) == 0
522 && realpath(buf, resolved) != NULL)
523 obj_main->path = xstrdup(resolved);
525 obj_main->path = xstrdup(argv0);
528 dbg("obj_main path %s", obj_main->path);
529 obj_main->mainprog = true;
531 if (aux_info[AT_STACKPROT] != NULL &&
532 aux_info[AT_STACKPROT]->a_un.a_val != 0)
533 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
536 * Get the actual dynamic linker pathname from the executable if
537 * possible. (It should always be possible.) That ensures that
538 * gdb will find the right dynamic linker even if a non-standard
541 if (obj_main->interp != NULL &&
542 strcmp(obj_main->interp, obj_rtld.path) != 0) {
544 obj_rtld.path = xstrdup(obj_main->interp);
545 __progname = obj_rtld.path;
548 digest_dynamic(obj_main, 0);
549 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
550 obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
551 obj_main->dynsymcount);
553 linkmap_add(obj_main);
554 linkmap_add(&obj_rtld);
556 /* Link the main program into the list of objects. */
557 *obj_tail = obj_main;
558 obj_tail = &obj_main->next;
562 /* Initialize a fake symbol for resolving undefined weak references. */
563 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
564 sym_zero.st_shndx = SHN_UNDEF;
565 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
568 libmap_disable = (bool)lm_init(libmap_override);
570 dbg("loading LD_PRELOAD libraries");
571 if (load_preload_objects() == -1)
573 preload_tail = obj_tail;
575 dbg("loading needed objects");
576 if (load_needed_objects(obj_main, 0) == -1)
579 /* Make a list of all objects loaded at startup. */
580 last_interposer = obj_main;
581 for (obj = obj_list; obj != NULL; obj = obj->next) {
582 if (obj->z_interpose && obj != obj_main) {
583 objlist_put_after(&list_main, last_interposer, obj);
584 last_interposer = obj;
586 objlist_push_tail(&list_main, obj);
591 dbg("checking for required versions");
592 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
597 if (ld_tracing) { /* We're done */
598 trace_loaded_objects(obj_main);
602 if (ld_resident) /* XXX clean this up! */
605 if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) {
606 dump_relocations(obj_main);
610 /* setup TLS for main thread */
611 dbg("initializing initial thread local storage");
612 STAILQ_FOREACH(entry, &list_main, link) {
614 * Allocate all the initial objects out of the static TLS
615 * block even if they didn't ask for it.
617 allocate_tls_offset(entry->obj);
620 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
623 * Do not try to allocate the TLS here, let libc do it itself.
624 * (crt1 for the program will call _init_tls())
627 if (relocate_objects(obj_main,
628 ld_bind_now != NULL && *ld_bind_now != '\0',
629 &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
632 dbg("doing copy relocations");
633 if (do_copy_relocations(obj_main) == -1)
638 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
639 if (exec_sys_unregister(-1) < 0) {
640 dbg("exec_sys_unregister failed %d\n", errno);
643 dbg("exec_sys_unregister success\n");
647 if (_getenv_ld("LD_DUMP_REL_POST") != NULL) {
648 dump_relocations(obj_main);
652 dbg("initializing key program variables");
653 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
654 set_program_var("environ", env);
655 set_program_var("__elf_aux_vector", aux);
657 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
658 extern void resident_start(void);
660 if (exec_sys_register(resident_start) < 0) {
661 dbg("exec_sys_register failed %d\n", errno);
664 dbg("exec_sys_register success\n");
668 /* Make a list of init functions to call. */
669 objlist_init(&initlist);
670 initlist_add_objects(obj_list, preload_tail, &initlist);
672 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
674 map_stacks_exec(NULL);
676 dbg("resolving ifuncs");
677 if (resolve_objects_ifunc(obj_main,
678 ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
683 * Do NOT call the initlist here, give libc a chance to set up
684 * the initial TLS segment. crt1 will then call _rtld_call_init().
687 dbg("transferring control to program entry point = %p", obj_main->entry);
689 /* Return the exit procedure and the program entry point. */
690 *exit_proc = rtld_exit;
692 return (func_ptr_type) obj_main->entry;
696 * Call the initialization list for dynamically loaded libraries.
697 * (called from crt1.c).
700 _rtld_call_init(void)
702 RtldLockState lockstate;
705 if (!obj_main->note_present && obj_main->valid_hash_gnu) {
707 * The use of a linker script with a PHDRS directive that does not include
708 * PT_NOTE will block the crt_no_init note. In this case we'll look for the
709 * recently added GNU hash dynamic tag which gets built by default. It is
710 * extremely unlikely to find a pre-3.1 binary without a PT_NOTE header and
711 * a gnu hash tag. If gnu hash found, consider binary to use new crt code.
713 obj_main->crt_no_init = true;
714 dbg("Setting crt_no_init without presence of PT_NOTE header");
717 wlock_acquire(rtld_bind_lock, &lockstate);
718 if (obj_main->crt_no_init)
722 * Make sure we don't call the main program's init and fini functions
723 * for binaries linked with old crt1 which calls _init itself.
725 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
726 obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL;
728 objlist_call_init(&initlist, &lockstate);
729 _r_debug_postinit(&obj_main->linkmap);
730 objlist_clear(&initlist);
731 dbg("loading filtees");
732 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
733 if (ld_loadfltr || obj->z_loadfltr)
734 load_filtees(obj, 0, &lockstate);
736 lock_release(rtld_bind_lock, &lockstate);
740 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
745 ptr = (void *)make_function_pointer(def, obj);
746 target = ((Elf_Addr (*)(void))ptr)();
747 return ((void *)target);
751 _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack)
755 const Obj_Entry *defobj;
758 RtldLockState lockstate;
760 rlock_acquire(rtld_bind_lock, &lockstate);
761 if (sigsetjmp(lockstate.env, 0) != 0)
762 lock_upgrade(rtld_bind_lock, &lockstate);
764 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
766 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
768 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
769 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
773 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
774 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
776 target = (Elf_Addr)(defobj->relocbase + def->st_value);
778 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
779 defobj->strtab + def->st_name, basename(obj->path),
780 (void *)target, basename(defobj->path));
783 * If we have a function call tracing hook, and the
784 * hook would like to keep tracing this one function,
785 * prevent the relocation so we will wind up here
786 * the next time again.
788 * We don't want to functrace calls from the functracer
789 * to avoid recursive loops.
791 if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
792 if (rtld_functrace(obj->path,
794 defobj->strtab + def->st_name,
796 lock_release(rtld_bind_lock, &lockstate);
802 * Write the new contents for the jmpslot. Note that depending on
803 * architecture, the value which we need to return back to the
804 * lazy binding trampoline may or may not be the target
805 * address. The value returned from reloc_jmpslot() is the value
806 * that the trampoline needs.
808 target = reloc_jmpslot(where, target, defobj, obj, rel);
809 lock_release(rtld_bind_lock, &lockstate);
814 * Error reporting function. Use it like printf. If formats the message
815 * into a buffer, and sets things up so that the next call to dlerror()
816 * will return the message.
819 _rtld_error(const char *fmt, ...)
821 static char buf[512];
825 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
831 * Return a dynamically-allocated copy of the current error message, if any.
836 return error_message == NULL ? NULL : xstrdup(error_message);
840 * Restore the current error message from a copy which was previously saved
841 * by errmsg_save(). The copy is freed.
844 errmsg_restore(char *saved_msg)
846 if (saved_msg == NULL)
847 error_message = NULL;
849 _rtld_error("%s", saved_msg);
855 basename(const char *name)
857 const char *p = strrchr(name, '/');
858 return p != NULL ? p + 1 : name;
861 static struct utsname uts;
864 origin_subst_one(char *real, const char *kw, const char *subst,
867 char *p, *p1, *res, *resp;
868 int subst_len, kw_len, subst_count, old_len, new_len;
873 * First, count the number of the keyword occurrences, to
874 * preallocate the final string.
876 for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
883 * If the keyword is not found, just return.
885 if (subst_count == 0)
886 return (may_free ? real : xstrdup(real));
889 * There is indeed something to substitute. Calculate the
890 * length of the resulting string, and allocate it.
892 subst_len = strlen(subst);
893 old_len = strlen(real);
894 new_len = old_len + (subst_len - kw_len) * subst_count;
895 res = xmalloc(new_len + 1);
898 * Now, execute the substitution loop.
900 for (p = real, resp = res, *resp = '\0';;) {
903 /* Copy the prefix before keyword. */
904 memcpy(resp, p, p1 - p);
906 /* Keyword replacement. */
907 memcpy(resp, subst, subst_len);
915 /* Copy to the end of string and finish. */
923 origin_subst(char *real, const char *origin_path)
925 char *res1, *res2, *res3, *res4;
927 if (uts.sysname[0] == '\0') {
928 if (uname(&uts) != 0) {
929 _rtld_error("utsname failed: %d", errno);
933 res1 = origin_subst_one(real, "$ORIGIN", origin_path, false);
934 res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true);
935 res3 = origin_subst_one(res2, "$OSREL", uts.release, true);
936 res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true);
943 const char *msg = dlerror();
947 rtld_fdputstr(STDERR_FILENO, msg);
948 rtld_fdputchar(STDERR_FILENO, '\n');
953 * Process a shared object's DYNAMIC section, and save the important
954 * information in its Obj_Entry structure.
957 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
958 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
961 Needed_Entry **needed_tail = &obj->needed;
962 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
963 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
964 const Elf_Hashelt *hashtab;
965 const Elf32_Word *hashval;
966 Elf32_Word bkt, nmaskwords;
969 int plttype = DT_REL;
975 obj->bind_now = false;
976 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
977 switch (dynp->d_tag) {
980 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
984 obj->relsize = dynp->d_un.d_val;
988 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
992 obj->pltrel = (const Elf_Rel *)
993 (obj->relocbase + dynp->d_un.d_ptr);
997 obj->pltrelsize = dynp->d_un.d_val;
1001 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
1005 obj->relasize = dynp->d_un.d_val;
1009 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
1013 plttype = dynp->d_un.d_val;
1014 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
1018 obj->symtab = (const Elf_Sym *)
1019 (obj->relocbase + dynp->d_un.d_ptr);
1023 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
1027 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
1031 obj->strsize = dynp->d_un.d_val;
1035 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1040 obj->verneednum = dynp->d_un.d_val;
1044 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1049 obj->verdefnum = dynp->d_un.d_val;
1053 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1059 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1061 obj->nbuckets = hashtab[0];
1062 obj->nchains = hashtab[1];
1063 obj->buckets = hashtab + 2;
1064 obj->chains = obj->buckets + obj->nbuckets;
1065 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
1066 obj->buckets != NULL;
1072 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1074 obj->nbuckets_gnu = hashtab[0];
1075 obj->symndx_gnu = hashtab[1];
1076 nmaskwords = hashtab[2];
1077 bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1078 /* Number of bitmask words is required to be power of 2 */
1079 nmw_power2 = ((nmaskwords & (nmaskwords - 1)) == 0);
1080 obj->maskwords_bm_gnu = nmaskwords - 1;
1081 obj->shift2_gnu = hashtab[3];
1082 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1083 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1084 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1086 obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 &&
1087 obj->buckets_gnu != NULL;
1093 Needed_Entry *nep = NEW(Needed_Entry);
1094 nep->name = dynp->d_un.d_val;
1099 needed_tail = &nep->next;
1105 Needed_Entry *nep = NEW(Needed_Entry);
1106 nep->name = dynp->d_un.d_val;
1110 *needed_filtees_tail = nep;
1111 needed_filtees_tail = &nep->next;
1117 Needed_Entry *nep = NEW(Needed_Entry);
1118 nep->name = dynp->d_un.d_val;
1122 *needed_aux_filtees_tail = nep;
1123 needed_aux_filtees_tail = &nep->next;
1128 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1132 obj->textrel = true;
1136 obj->symbolic = true;
1141 * We have to wait until later to process this, because we
1142 * might not have gotten the address of the string table yet.
1152 *dyn_runpath = dynp;
1156 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1159 case DT_PREINIT_ARRAY:
1160 obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1163 case DT_PREINIT_ARRAYSZ:
1164 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1168 obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1171 case DT_INIT_ARRAYSZ:
1172 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1176 obj->fini = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1180 obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1183 case DT_FINI_ARRAYSZ:
1184 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1188 /* XXX - not implemented yet */
1190 dbg("Filling in DT_DEBUG entry");
1191 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1195 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1196 obj->z_origin = true;
1197 if (dynp->d_un.d_val & DF_SYMBOLIC)
1198 obj->symbolic = true;
1199 if (dynp->d_un.d_val & DF_TEXTREL)
1200 obj->textrel = true;
1201 if (dynp->d_un.d_val & DF_BIND_NOW)
1202 obj->bind_now = true;
1203 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1208 if (dynp->d_un.d_val & DF_1_NOOPEN)
1209 obj->z_noopen = true;
1210 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1211 obj->z_origin = true;
1212 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1214 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1215 obj->bind_now = true;
1216 if (dynp->d_un.d_val & DF_1_NODELETE)
1217 obj->z_nodelete = true;
1218 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1219 obj->z_loadfltr = true;
1220 if (dynp->d_un.d_val & DF_1_INTERPOSE)
1221 obj->z_interpose = true;
1222 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1223 obj->z_nodeflib = true;
1228 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1235 obj->traced = false;
1237 if (plttype == DT_RELA) {
1238 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1240 obj->pltrelasize = obj->pltrelsize;
1241 obj->pltrelsize = 0;
1244 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1245 if (obj->valid_hash_sysv)
1246 obj->dynsymcount = obj->nchains;
1247 else if (obj->valid_hash_gnu) {
1248 obj->dynsymcount = 0;
1249 for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1250 if (obj->buckets_gnu[bkt] == 0)
1252 hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1255 while ((*hashval++ & 1u) == 0);
1257 obj->dynsymcount += obj->symndx_gnu;
1262 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1263 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1266 if (obj->z_origin && obj->origin_path == NULL) {
1267 obj->origin_path = xmalloc(PATH_MAX);
1268 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1272 if (dyn_runpath != NULL) {
1273 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1275 obj->runpath = origin_subst(obj->runpath, obj->origin_path);
1277 else if (dyn_rpath != NULL) {
1278 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1280 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1283 if (dyn_soname != NULL)
1284 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1288 digest_dynamic(Obj_Entry *obj, int early)
1290 const Elf_Dyn *dyn_rpath;
1291 const Elf_Dyn *dyn_soname;
1292 const Elf_Dyn *dyn_runpath;
1294 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1295 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1299 * Process a shared object's program header. This is used only for the
1300 * main program, when the kernel has already loaded the main program
1301 * into memory before calling the dynamic linker. It creates and
1302 * returns an Obj_Entry structure.
1305 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1308 const Elf_Phdr *phlimit = phdr + phnum;
1310 Elf_Addr note_start, note_end;
1314 for (ph = phdr; ph < phlimit; ph++) {
1315 if (ph->p_type != PT_PHDR)
1319 obj->phsize = ph->p_memsz;
1320 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1324 obj->stack_flags = PF_X | PF_R | PF_W;
1326 for (ph = phdr; ph < phlimit; ph++) {
1327 switch (ph->p_type) {
1330 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1334 if (nsegs == 0) { /* First load segment */
1335 obj->vaddrbase = trunc_page(ph->p_vaddr);
1336 obj->mapbase = obj->vaddrbase + obj->relocbase;
1337 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1339 } else { /* Last load segment */
1340 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1347 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1352 obj->tlssize = ph->p_memsz;
1353 obj->tlsalign = ph->p_align;
1354 obj->tlsinitsize = ph->p_filesz;
1355 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1359 obj->stack_flags = ph->p_flags;
1363 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1364 obj->relro_size = round_page(ph->p_memsz);
1368 obj->note_present = true;
1369 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1370 note_end = note_start + ph->p_filesz;
1371 digest_notes(obj, note_start, note_end);
1376 _rtld_error("%s: too few PT_LOAD segments", path);
1385 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1387 const Elf_Note *note;
1388 const char *note_name;
1391 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1392 note = (const Elf_Note *)((const char *)(note + 1) +
1393 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1394 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1395 if (note->n_namesz != sizeof(NOTE_VENDOR) ||
1396 note->n_descsz != sizeof(int32_t))
1398 if (note->n_type != ABI_NOTETYPE &&
1399 note->n_type != CRT_NOINIT_NOTETYPE)
1401 note_name = (const char *)(note + 1);
1402 if (strncmp(NOTE_VENDOR, note_name, sizeof(NOTE_VENDOR)) != 0)
1404 switch (note->n_type) {
1406 /* DragonFly osrel note */
1407 p = (uintptr_t)(note + 1);
1408 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1409 obj->osrel = *(const int32_t *)(p);
1410 dbg("note osrel %d", obj->osrel);
1412 case CRT_NOINIT_NOTETYPE:
1413 /* DragonFly 'crt does not call init' note */
1414 obj->crt_no_init = true;
1415 dbg("note crt_no_init");
1422 dlcheck(void *handle)
1426 for (obj = obj_list; obj != NULL; obj = obj->next)
1427 if (obj == (Obj_Entry *) handle)
1430 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1431 _rtld_error("Invalid shared object handle %p", handle);
1438 * If the given object is already in the donelist, return true. Otherwise
1439 * add the object to the list and return false.
1442 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1446 for (i = 0; i < dlp->num_used; i++)
1447 if (dlp->objs[i] == obj)
1450 * Our donelist allocation should always be sufficient. But if
1451 * our threads locking isn't working properly, more shared objects
1452 * could have been loaded since we allocated the list. That should
1453 * never happen, but we'll handle it properly just in case it does.
1455 if (dlp->num_used < dlp->num_alloc)
1456 dlp->objs[dlp->num_used++] = obj;
1461 * Hash function for symbol table lookup. Don't even think about changing
1462 * this. It is specified by the System V ABI.
1465 elf_hash(const char *name)
1467 const unsigned char *p = (const unsigned char *) name;
1468 unsigned long h = 0;
1471 while (*p != '\0') {
1472 h = (h << 4) + *p++;
1473 if ((g = h & 0xf0000000) != 0)
1481 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1482 * unsigned in case it's implemented with a wider type.
1484 static uint_fast32_t
1485 gnu_hash(const char *s)
1491 for (c = *s; c != '\0'; c = *++s)
1493 return (h & 0xffffffff);
1498 * Find the library with the given name, and return its full pathname.
1499 * The returned string is dynamically allocated. Generates an error
1500 * message and returns NULL if the library cannot be found.
1502 * If the second argument is non-NULL, then it refers to an already-
1503 * loaded shared object, whose library search path will be searched.
1505 * If a library is successfully located via LD_LIBRARY_PATH_FDS, its
1506 * descriptor (which is close-on-exec) will be passed out via the third
1509 * The search order is:
1510 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1511 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1513 * DT_RUNPATH in the referencing file
1514 * ldconfig hints (if -z nodefaultlib, filter out default library directories
1516 * /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1518 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1521 find_library(const char *xname, const Obj_Entry *refobj, int *fdp)
1525 bool nodeflib, objgiven;
1527 objgiven = refobj != NULL;
1528 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1529 if (xname[0] != '/' && !trust) {
1530 _rtld_error("Absolute pathname required for shared object \"%s\"",
1534 if (objgiven && refobj->z_origin) {
1535 return (origin_subst(__DECONST(char *, xname),
1536 refobj->origin_path));
1538 return (xstrdup(xname));
1542 if (libmap_disable || !objgiven ||
1543 (name = lm_find(refobj->path, xname)) == NULL)
1544 name = (char *)xname;
1546 dbg(" Searching for \"%s\"", name);
1548 nodeflib = objgiven ? refobj->z_nodeflib : false;
1550 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1551 (objgiven && refobj->runpath == NULL && refobj != obj_main &&
1552 (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
1553 (pathname = search_library_path(name, ld_library_path)) != NULL ||
1555 (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
1556 (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
1557 (pathname = search_library_path(name, gethints(nodeflib))) != NULL ||
1558 (objgiven && !nodeflib &&
1559 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
1562 if (objgiven && refobj->path != NULL) {
1563 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1564 name, basename(refobj->path));
1566 _rtld_error("Shared object \"%s\" not found", name);
1572 * Given a symbol number in a referencing object, find the corresponding
1573 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1574 * no definition was found. Returns a pointer to the Obj_Entry of the
1575 * defining object via the reference parameter DEFOBJ_OUT.
1578 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1579 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1580 RtldLockState *lockstate)
1584 const Obj_Entry *defobj;
1590 * If we have already found this symbol, get the information from
1593 if (symnum >= refobj->dynsymcount)
1594 return NULL; /* Bad object */
1595 if (cache != NULL && cache[symnum].sym != NULL) {
1596 *defobj_out = cache[symnum].obj;
1597 return cache[symnum].sym;
1600 ref = refobj->symtab + symnum;
1601 name = refobj->strtab + ref->st_name;
1606 * We don't have to do a full scale lookup if the symbol is local.
1607 * We know it will bind to the instance in this load module; to
1608 * which we already have a pointer (ie ref). By not doing a lookup,
1609 * we not only improve performance, but it also avoids unresolvable
1610 * symbols when local symbols are not in the hash table.
1612 * This might occur for TLS module relocations, which simply use
1615 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1616 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1617 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1620 symlook_init(&req, name);
1622 req.ventry = fetch_ventry(refobj, symnum);
1623 req.lockstate = lockstate;
1624 res = symlook_default(&req, refobj);
1627 defobj = req.defobj_out;
1635 * If we found no definition and the reference is weak, treat the
1636 * symbol as having the value zero.
1638 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1644 *defobj_out = defobj;
1645 /* Record the information in the cache to avoid subsequent lookups. */
1646 if (cache != NULL) {
1647 cache[symnum].sym = def;
1648 cache[symnum].obj = defobj;
1651 if (refobj != &obj_rtld)
1652 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1658 * Return the search path from the ldconfig hints file, reading it if
1659 * necessary. If nostdlib is true, then the default search paths are
1660 * not added to result.
1662 * Returns NULL if there are problems with the hints file,
1663 * or if the search path there is empty.
1666 gethints(bool nostdlib)
1668 static char *hints, *filtered_path;
1669 struct elfhints_hdr hdr;
1670 struct fill_search_info_args sargs, hargs;
1671 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1672 struct dl_serpath *SLPpath, *hintpath;
1674 unsigned int SLPndx, hintndx, fndx, fcount;
1679 /* First call, read the hints file */
1680 if (hints == NULL) {
1681 /* Keep from trying again in case the hints file is bad. */
1684 if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
1686 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1687 hdr.magic != ELFHINTS_MAGIC ||
1692 p = xmalloc(hdr.dirlistlen + 1);
1693 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1694 read(fd, p, hdr.dirlistlen + 1) !=
1695 (ssize_t)hdr.dirlistlen + 1) {
1705 * If caller agreed to receive list which includes the default
1706 * paths, we are done. Otherwise, if we still have not
1707 * calculated filtered result, do it now.
1710 return (hints[0] != '\0' ? hints : NULL);
1711 if (filtered_path != NULL)
1715 * Obtain the list of all configured search paths, and the
1716 * list of the default paths.
1718 * First estimate the size of the results.
1720 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1722 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1725 sargs.request = RTLD_DI_SERINFOSIZE;
1726 sargs.serinfo = &smeta;
1727 hargs.request = RTLD_DI_SERINFOSIZE;
1728 hargs.serinfo = &hmeta;
1730 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1731 path_enumerate(p, fill_search_info, &hargs);
1733 SLPinfo = xmalloc(smeta.dls_size);
1734 hintinfo = xmalloc(hmeta.dls_size);
1737 * Next fetch both sets of paths.
1739 sargs.request = RTLD_DI_SERINFO;
1740 sargs.serinfo = SLPinfo;
1741 sargs.serpath = &SLPinfo->dls_serpath[0];
1742 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1744 hargs.request = RTLD_DI_SERINFO;
1745 hargs.serinfo = hintinfo;
1746 hargs.serpath = &hintinfo->dls_serpath[0];
1747 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1749 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1750 path_enumerate(p, fill_search_info, &hargs);
1753 * Now calculate the difference between two sets, by excluding
1754 * standard paths from the full set.
1758 filtered_path = xmalloc(hdr.dirlistlen + 1);
1759 hintpath = &hintinfo->dls_serpath[0];
1760 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
1762 SLPpath = &SLPinfo->dls_serpath[0];
1764 * Check each standard path against current.
1766 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
1767 /* matched, skip the path */
1768 if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
1776 * Not matched against any standard path, add the path
1777 * to result. Separate consecutive paths with ':'.
1780 filtered_path[fndx] = ':';
1784 flen = strlen(hintpath->dls_name);
1785 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1788 filtered_path[fndx] = '\0';
1794 return (filtered_path[0] != '\0' ? filtered_path : NULL);
1798 init_dag(Obj_Entry *root)
1800 const Needed_Entry *needed;
1801 const Objlist_Entry *elm;
1804 if (root->dag_inited)
1806 donelist_init(&donelist);
1808 /* Root object belongs to own DAG. */
1809 objlist_push_tail(&root->dldags, root);
1810 objlist_push_tail(&root->dagmembers, root);
1811 donelist_check(&donelist, root);
1814 * Add dependencies of root object to DAG in breadth order
1815 * by exploiting the fact that each new object get added
1816 * to the tail of the dagmembers list.
1818 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1819 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1820 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1822 objlist_push_tail(&needed->obj->dldags, root);
1823 objlist_push_tail(&root->dagmembers, needed->obj);
1826 root->dag_inited = true;
1830 process_nodelete(Obj_Entry *root)
1832 const Objlist_Entry *elm;
1835 * Walk over object DAG and process every dependent object that
1836 * is marked as DF_1_NODELETE. They need to grow their own DAG,
1837 * which then should have its reference upped separately.
1839 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1840 if (elm->obj != NULL && elm->obj->z_nodelete &&
1841 !elm->obj->ref_nodel) {
1842 dbg("obj %s nodelete", elm->obj->path);
1845 elm->obj->ref_nodel = true;
1851 * Initialize the dynamic linker. The argument is the address at which
1852 * the dynamic linker has been mapped into memory. The primary task of
1853 * this function is to relocate the dynamic linker.
1856 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1858 Obj_Entry objtmp; /* Temporary rtld object */
1859 const Elf_Ehdr *ehdr;
1860 const Elf_Dyn *dyn_rpath;
1861 const Elf_Dyn *dyn_soname;
1862 const Elf_Dyn *dyn_runpath;
1865 * Conjure up an Obj_Entry structure for the dynamic linker.
1867 * The "path" member can't be initialized yet because string constants
1868 * cannot yet be accessed. Below we will set it correctly.
1870 memset(&objtmp, 0, sizeof(objtmp));
1873 objtmp.mapbase = mapbase;
1875 objtmp.relocbase = mapbase;
1877 if (RTLD_IS_DYNAMIC()) {
1878 objtmp.dynamic = rtld_dynamic(&objtmp);
1879 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
1880 assert(objtmp.needed == NULL);
1881 assert(!objtmp.textrel);
1884 * Temporarily put the dynamic linker entry into the object list, so
1885 * that symbols can be found.
1888 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
1890 ehdr = (Elf_Ehdr *)mapbase;
1891 objtmp.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff);
1892 objtmp.phsize = ehdr->e_phnum * sizeof(objtmp.phdr[0]);
1894 /* Initialize the object list. */
1895 obj_tail = &obj_list;
1897 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1898 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1900 #ifdef ENABLE_OSRELDATE
1901 if (aux_info[AT_OSRELDATE] != NULL)
1902 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1905 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
1907 /* Replace the path with a dynamically allocated copy. */
1908 obj_rtld.path = xstrdup(PATH_RTLD);
1910 r_debug.r_brk = r_debug_state;
1911 r_debug.r_state = RT_CONSISTENT;
1915 * Add the init functions from a needed object list (and its recursive
1916 * needed objects) to "list". This is not used directly; it is a helper
1917 * function for initlist_add_objects(). The write lock must be held
1918 * when this function is called.
1921 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1923 /* Recursively process the successor needed objects. */
1924 if (needed->next != NULL)
1925 initlist_add_neededs(needed->next, list);
1927 /* Process the current needed object. */
1928 if (needed->obj != NULL)
1929 initlist_add_objects(needed->obj, &needed->obj->next, list);
1933 * Scan all of the DAGs rooted in the range of objects from "obj" to
1934 * "tail" and add their init functions to "list". This recurses over
1935 * the DAGs and ensure the proper init ordering such that each object's
1936 * needed libraries are initialized before the object itself. At the
1937 * same time, this function adds the objects to the global finalization
1938 * list "list_fini" in the opposite order. The write lock must be
1939 * held when this function is called.
1942 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1945 if (obj->init_scanned || obj->init_done)
1947 obj->init_scanned = true;
1949 /* Recursively process the successor objects. */
1950 if (&obj->next != tail)
1951 initlist_add_objects(obj->next, tail, list);
1953 /* Recursively process the needed objects. */
1954 if (obj->needed != NULL)
1955 initlist_add_neededs(obj->needed, list);
1956 if (obj->needed_filtees != NULL)
1957 initlist_add_neededs(obj->needed_filtees, list);
1958 if (obj->needed_aux_filtees != NULL)
1959 initlist_add_neededs(obj->needed_aux_filtees, list);
1961 /* Add the object to the init list. */
1962 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
1963 obj->init_array != (Elf_Addr)NULL)
1964 objlist_push_tail(list, obj);
1966 /* Add the object to the global fini list in the reverse order. */
1967 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1968 && !obj->on_fini_list) {
1969 objlist_push_head(&list_fini, obj);
1970 obj->on_fini_list = true;
1975 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1979 free_needed_filtees(Needed_Entry *n)
1981 Needed_Entry *needed, *needed1;
1983 for (needed = n; needed != NULL; needed = needed->next) {
1984 if (needed->obj != NULL) {
1985 dlclose(needed->obj);
1989 for (needed = n; needed != NULL; needed = needed1) {
1990 needed1 = needed->next;
1996 unload_filtees(Obj_Entry *obj)
1999 free_needed_filtees(obj->needed_filtees);
2000 obj->needed_filtees = NULL;
2001 free_needed_filtees(obj->needed_aux_filtees);
2002 obj->needed_aux_filtees = NULL;
2003 obj->filtees_loaded = false;
2007 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
2008 RtldLockState *lockstate)
2011 for (; needed != NULL; needed = needed->next) {
2012 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
2013 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
2014 RTLD_LOCAL, lockstate);
2019 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
2022 lock_restart_for_upgrade(lockstate);
2023 if (!obj->filtees_loaded) {
2024 load_filtee1(obj, obj->needed_filtees, flags, lockstate);
2025 load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
2026 obj->filtees_loaded = true;
2031 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
2035 for (; needed != NULL; needed = needed->next) {
2036 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
2037 flags & ~RTLD_LO_NOLOAD);
2038 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
2045 * Given a shared object, traverse its list of needed objects, and load
2046 * each of them. Returns 0 on success. Generates an error message and
2047 * returns -1 on failure.
2050 load_needed_objects(Obj_Entry *first, int flags)
2054 for (obj = first; obj != NULL; obj = obj->next) {
2055 if (process_needed(obj, obj->needed, flags) == -1)
2062 load_preload_objects(void)
2064 char *p = ld_preload;
2066 static const char delim[] = " \t:;";
2071 p += strspn(p, delim);
2072 while (*p != '\0') {
2073 size_t len = strcspn(p, delim);
2080 obj = load_object(p, -1, NULL, 0);
2082 return -1; /* XXX - cleanup */
2083 obj->z_interpose = true;
2086 p += strspn(p, delim);
2088 /* Check for the magic tracing function */
2089 symlook_init(&req, RTLD_FUNCTRACE);
2090 res = symlook_obj(&req, obj);
2092 rtld_functrace = (void *)(req.defobj_out->relocbase +
2093 req.sym_out->st_value);
2094 rtld_functrace_obj = req.defobj_out;
2097 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2102 printable_path(const char *path)
2105 return (path == NULL ? "<unknown>" : path);
2109 * Load a shared object into memory, if it is not already loaded. The
2110 * object may be specified by name or by user-supplied file descriptor
2111 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2114 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2118 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2127 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
2128 if (object_match_name(obj, name))
2132 path = find_library(name, refobj, &fd);
2140 * search_library_pathfds() opens a fresh file descriptor for the
2141 * library, so there is no need to dup().
2143 } else if (fd_u == -1) {
2145 * If we didn't find a match by pathname, or the name is not
2146 * supplied, open the file and check again by device and inode.
2147 * This avoids false mismatches caused by multiple links or ".."
2150 * To avoid a race, we open the file and use fstat() rather than
2153 if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
2154 _rtld_error("Cannot open \"%s\"", path);
2159 fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
2161 _rtld_error("Cannot dup fd");
2166 if (fstat(fd, &sb) == -1) {
2167 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2172 for (obj = obj_list->next; obj != NULL; obj = obj->next)
2173 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2175 if (obj != NULL && name != NULL) {
2176 object_add_name(obj, name);
2181 if (flags & RTLD_LO_NOLOAD) {
2187 /* First use of this object, so we must map it in */
2188 obj = do_load_object(fd, name, path, &sb, flags);
2197 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2204 * but first, make sure that environment variables haven't been
2205 * used to circumvent the noexec flag on a filesystem.
2207 if (dangerous_ld_env) {
2208 if (fstatfs(fd, &fs) != 0) {
2209 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2212 if (fs.f_flags & MNT_NOEXEC) {
2213 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
2217 dbg("loading \"%s\"", printable_path(path));
2218 obj = map_object(fd, printable_path(path), sbp);
2223 * If DT_SONAME is present in the object, digest_dynamic2 already
2224 * added it to the object names.
2227 object_add_name(obj, name);
2229 digest_dynamic(obj, 0);
2230 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
2231 obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
2232 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2234 dbg("refusing to load non-loadable \"%s\"", obj->path);
2235 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2236 munmap(obj->mapbase, obj->mapsize);
2242 obj_tail = &obj->next;
2245 linkmap_add(obj); /* for GDB & dlinfo() */
2247 max_stack_flags |= obj->stack_flags;
2250 dbg(" %p .. %p: %s", obj->mapbase,
2251 obj->mapbase + obj->mapsize - 1, obj->path);
2253 dbg(" WARNING: %s has impure text", obj->path);
2254 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2261 obj_from_addr(const void *addr)
2265 for (obj = obj_list; obj != NULL; obj = obj->next) {
2266 if (addr < (void *) obj->mapbase)
2268 if (addr < (void *) (obj->mapbase + obj->mapsize))
2275 * If the main program is defined with a .preinit_array section, call
2276 * each function in order. This must occur before the initialization
2277 * of any shared object or the main program.
2282 Elf_Addr *preinit_addr;
2285 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2286 if (preinit_addr == NULL)
2289 for (index = 0; index < obj_main->preinit_array_num; index++) {
2290 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2291 dbg("calling preinit function for %s at %p", obj_main->path,
2292 (void *)preinit_addr[index]);
2293 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2294 0, 0, obj_main->path);
2295 call_init_pointer(obj_main, preinit_addr[index]);
2301 * Call the finalization functions for each of the objects in "list"
2302 * belonging to the DAG of "root" and referenced once. If NULL "root"
2303 * is specified, every finalization function will be called regardless
2304 * of the reference count and the list elements won't be freed. All of
2305 * the objects are expected to have non-NULL fini functions.
2308 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2312 Elf_Addr *fini_addr;
2315 assert(root == NULL || root->refcount == 1);
2318 * Preserve the current error message since a fini function might
2319 * call into the dynamic linker and overwrite it.
2321 saved_msg = errmsg_save();
2323 STAILQ_FOREACH(elm, list, link) {
2324 if (root != NULL && (elm->obj->refcount != 1 ||
2325 objlist_find(&root->dagmembers, elm->obj) == NULL))
2328 /* Remove object from fini list to prevent recursive invocation. */
2329 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2331 * XXX: If a dlopen() call references an object while the
2332 * fini function is in progress, we might end up trying to
2333 * unload the referenced object in dlclose() or the object
2334 * won't be unloaded although its fini function has been
2337 lock_release(rtld_bind_lock, lockstate);
2340 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
2341 * When this happens, DT_FINI_ARRAY is processed first.
2342 * It is also processed backwards. It is possible to encounter
2343 * DT_FINI_ARRAY elements with values of 0 or 1, but they need
2346 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2347 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2348 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
2349 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2350 dbg("calling fini array function for %s at %p",
2351 elm->obj->path, (void *)fini_addr[index]);
2352 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2353 (void *)fini_addr[index], 0, 0, elm->obj->path);
2354 call_initfini_pointer(elm->obj, fini_addr[index]);
2358 if (elm->obj->fini != (Elf_Addr)NULL) {
2359 dbg("calling fini function for %s at %p", elm->obj->path,
2360 (void *)elm->obj->fini);
2361 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2362 0, 0, elm->obj->path);
2363 call_initfini_pointer(elm->obj, elm->obj->fini);
2365 wlock_acquire(rtld_bind_lock, lockstate);
2366 /* No need to free anything if process is going down. */
2370 * We must restart the list traversal after every fini call
2371 * because a dlclose() call from the fini function or from
2372 * another thread might have modified the reference counts.
2376 } while (elm != NULL);
2377 errmsg_restore(saved_msg);
2381 * Call the initialization functions for each of the objects in
2382 * "list". All of the objects are expected to have non-NULL init
2386 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2391 Elf_Addr *init_addr;
2395 * Clean init_scanned flag so that objects can be rechecked and
2396 * possibly initialized earlier if any of vectors called below
2397 * cause the change by using dlopen.
2399 for (obj = obj_list; obj != NULL; obj = obj->next)
2400 obj->init_scanned = false;
2403 * Preserve the current error message since an init function might
2404 * call into the dynamic linker and overwrite it.
2406 saved_msg = errmsg_save();
2407 STAILQ_FOREACH(elm, list, link) {
2408 if (elm->obj->init_done) /* Initialized early. */
2412 * Race: other thread might try to use this object before current
2413 * one completes the initilization. Not much can be done here
2414 * without better locking.
2416 elm->obj->init_done = true;
2417 lock_release(rtld_bind_lock, lockstate);
2420 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
2421 * When this happens, DT_INIT is processed first.
2422 * It is possible to encounter DT_INIT_ARRAY elements with values
2423 * of 0 or 1, but they need to be ignored.
2425 if (elm->obj->init != (Elf_Addr)NULL) {
2426 dbg("calling init function for %s at %p", elm->obj->path,
2427 (void *)elm->obj->init);
2428 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2429 0, 0, elm->obj->path);
2430 call_initfini_pointer(elm->obj, elm->obj->init);
2432 init_addr = (Elf_Addr *)elm->obj->init_array;
2433 if (init_addr != NULL) {
2434 for (index = 0; index < elm->obj->init_array_num; index++) {
2435 if (init_addr[index] != 0 && init_addr[index] != 1) {
2436 dbg("calling init array function for %s at %p", elm->obj->path,
2437 (void *)init_addr[index]);
2438 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2439 (void *)init_addr[index], 0, 0, elm->obj->path);
2440 call_init_pointer(elm->obj, init_addr[index]);
2444 wlock_acquire(rtld_bind_lock, lockstate);
2446 errmsg_restore(saved_msg);
2450 objlist_clear(Objlist *list)
2454 while (!STAILQ_EMPTY(list)) {
2455 elm = STAILQ_FIRST(list);
2456 STAILQ_REMOVE_HEAD(list, link);
2461 static Objlist_Entry *
2462 objlist_find(Objlist *list, const Obj_Entry *obj)
2466 STAILQ_FOREACH(elm, list, link)
2467 if (elm->obj == obj)
2473 objlist_init(Objlist *list)
2479 objlist_push_head(Objlist *list, Obj_Entry *obj)
2483 elm = NEW(Objlist_Entry);
2485 STAILQ_INSERT_HEAD(list, elm, link);
2489 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2493 elm = NEW(Objlist_Entry);
2495 STAILQ_INSERT_TAIL(list, elm, link);
2499 objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
2501 Objlist_Entry *elm, *listelm;
2503 STAILQ_FOREACH(listelm, list, link) {
2504 if (listelm->obj == listobj)
2507 elm = NEW(Objlist_Entry);
2509 if (listelm != NULL)
2510 STAILQ_INSERT_AFTER(list, listelm, elm, link);
2512 STAILQ_INSERT_TAIL(list, elm, link);
2516 objlist_remove(Objlist *list, Obj_Entry *obj)
2520 if ((elm = objlist_find(list, obj)) != NULL) {
2521 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2527 * Relocate dag rooted in the specified object.
2528 * Returns 0 on success, or -1 on failure.
2532 relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
2533 int flags, RtldLockState *lockstate)
2539 STAILQ_FOREACH(elm, &root->dagmembers, link) {
2540 error = relocate_object(elm->obj, bind_now, rtldobj, flags,
2549 * Prepare for, or clean after, relocating an object marked with
2550 * DT_TEXTREL or DF_TEXTREL. Before relocating, all read-only
2551 * segments are remapped read-write. After relocations are done, the
2552 * segment's permissions are returned back to the modes specified in
2553 * the phdrs. If any relocation happened, or always for wired
2554 * program, COW is triggered.
2557 reloc_textrel_prot(Obj_Entry *obj, bool before)
2564 for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0;
2566 if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0)
2568 base = obj->relocbase + trunc_page(ph->p_vaddr);
2569 sz = round_page(ph->p_vaddr + ph->p_filesz) -
2570 trunc_page(ph->p_vaddr);
2571 prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0);
2573 * Make sure modified text segments are included in the
2574 * core dump since we modified it. This unfortunately causes the
2575 * entire text segment to core-out but we don't have much of a
2576 * choice. We could try to only reenable core dumps on pages
2577 * in which relocations occured but that is likely most of the text
2578 * pages anyway, and even that would not work because the rest of
2579 * the text pages would wind up as a read-only OBJT_DEFAULT object
2580 * (created due to our modifications) backed by the original OBJT_VNODE
2581 * object, and the ELF coredump code is currently only able to dump
2582 * vnode records for pure vnode-backed mappings, not vnode backings
2583 * to memory objects.
2585 if (before == false)
2586 madvise(base, sz, MADV_CORE);
2587 if (mprotect(base, sz, prot) == -1) {
2588 _rtld_error("%s: Cannot write-%sable text segment: %s",
2589 obj->path, before ? "en" : "dis",
2590 rtld_strerror(errno));
2598 * Relocate single object.
2599 * Returns 0 on success, or -1 on failure.
2602 relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
2603 int flags, RtldLockState *lockstate)
2608 obj->relocated = true;
2610 dbg("relocating \"%s\"", obj->path);
2612 if (obj->symtab == NULL || obj->strtab == NULL ||
2613 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2614 _rtld_error("%s: Shared object has no run-time symbol table",
2619 /* There are relocations to the write-protected text segment. */
2620 if (obj->textrel && reloc_textrel_prot(obj, true) != 0)
2623 /* Process the non-PLT non-IFUNC relocations. */
2624 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2627 /* Re-protected the text segment. */
2628 if (obj->textrel && reloc_textrel_prot(obj, false) != 0)
2631 /* Set the special PLT or GOT entries. */
2634 /* Process the PLT relocations. */
2635 if (reloc_plt(obj) == -1)
2637 /* Relocate the jump slots if we are doing immediate binding. */
2638 if (obj->bind_now || bind_now)
2639 if (reloc_jmpslots(obj, flags, lockstate) == -1)
2643 * Process the non-PLT IFUNC relocations. The relocations are
2644 * processed in two phases, because IFUNC resolvers may
2645 * reference other symbols, which must be readily processed
2646 * before resolvers are called.
2648 if (obj->non_plt_gnu_ifunc &&
2649 reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate))
2653 * Set up the magic number and version in the Obj_Entry. These
2654 * were checked in the crt1.o from the original ElfKit, so we
2655 * set them for backward compatibility.
2657 obj->magic = RTLD_MAGIC;
2658 obj->version = RTLD_VERSION;
2661 * Set relocated data to read-only status if protection specified
2664 if (obj->relro_size) {
2665 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
2666 _rtld_error("%s: Cannot enforce relro relocation: %s",
2667 obj->path, rtld_strerror(errno));
2675 * Relocate newly-loaded shared objects. The argument is a pointer to
2676 * the Obj_Entry for the first such object. All objects from the first
2677 * to the end of the list of objects are relocated. Returns 0 on success,
2681 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2682 int flags, RtldLockState *lockstate)
2687 for (error = 0, obj = first; obj != NULL; obj = obj->next) {
2688 error = relocate_object(obj, bind_now, rtldobj, flags,
2697 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2698 * referencing STT_GNU_IFUNC symbols is postponed till the other
2699 * relocations are done. The indirect functions specified as
2700 * ifunc are allowed to call other symbols, so we need to have
2701 * objects relocated before asking for resolution from indirects.
2703 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2704 * instead of the usual lazy handling of PLT slots. It is
2705 * consistent with how GNU does it.
2708 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2709 RtldLockState *lockstate)
2711 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2713 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2714 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2720 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2721 RtldLockState *lockstate)
2725 for (obj = first; obj != NULL; obj = obj->next) {
2726 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2733 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2734 RtldLockState *lockstate)
2738 STAILQ_FOREACH(elm, list, link) {
2739 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2747 * Cleanup procedure. It will be called (by the atexit mechanism) just
2748 * before the process exits.
2753 RtldLockState lockstate;
2755 wlock_acquire(rtld_bind_lock, &lockstate);
2757 objlist_call_fini(&list_fini, NULL, &lockstate);
2758 /* No need to remove the items from the list, since we are exiting. */
2759 if (!libmap_disable)
2761 lock_release(rtld_bind_lock, &lockstate);
2765 * Iterate over a search path, translate each element, and invoke the
2766 * callback on the result.
2769 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2775 path += strspn(path, ":;");
2776 while (*path != '\0') {
2780 len = strcspn(path, ":;");
2781 trans = lm_findn(NULL, path, len);
2783 res = callback(trans, strlen(trans), arg);
2785 res = callback(path, len, arg);
2791 path += strspn(path, ":;");
2797 struct try_library_args {
2805 try_library_path(const char *dir, size_t dirlen, void *param)
2807 struct try_library_args *arg;
2810 if (*dir == '/' || trust) {
2813 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2816 pathname = arg->buffer;
2817 strncpy(pathname, dir, dirlen);
2818 pathname[dirlen] = '/';
2819 strcpy(pathname + dirlen + 1, arg->name);
2821 dbg(" Trying \"%s\"", pathname);
2822 if (access(pathname, F_OK) == 0) { /* We found it */
2823 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2824 strcpy(pathname, arg->buffer);
2832 search_library_path(const char *name, const char *path)
2835 struct try_library_args arg;
2841 arg.namelen = strlen(name);
2842 arg.buffer = xmalloc(PATH_MAX);
2843 arg.buflen = PATH_MAX;
2845 p = path_enumerate(path, try_library_path, &arg);
2854 * Finds the library with the given name using the directory descriptors
2855 * listed in the LD_LIBRARY_PATH_FDS environment variable.
2857 * Returns a freshly-opened close-on-exec file descriptor for the library,
2858 * or -1 if the library cannot be found.
2861 search_library_pathfds(const char *name, const char *path, int *fdp)
2863 char *envcopy, *fdstr, *found, *last_token;
2867 dbg("%s('%s', '%s', fdp)", __func__, name, path);
2869 /* Don't load from user-specified libdirs into setuid binaries. */
2873 /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */
2877 /* LD_LIBRARY_PATH_FDS only works with relative paths. */
2878 if (name[0] == '/') {
2879 dbg("Absolute path (%s) passed to %s", name, __func__);
2884 * Use strtok_r() to walk the FD:FD:FD list. This requires a local
2885 * copy of the path, as strtok_r rewrites separator tokens
2889 envcopy = xstrdup(path);
2890 for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL;
2891 fdstr = strtok_r(NULL, ":", &last_token)) {
2892 dirfd = parse_libdir(fdstr);
2895 fd = openat(dirfd, name, O_RDONLY | O_CLOEXEC);
2898 len = strlen(fdstr) + strlen(name) + 3;
2899 found = xmalloc(len);
2900 if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) {
2901 _rtld_error("error generating '%d/%s'",
2905 dbg("open('%s') => %d", found, fd);
2916 dlclose(void *handle)
2919 RtldLockState lockstate;
2921 wlock_acquire(rtld_bind_lock, &lockstate);
2922 root = dlcheck(handle);
2924 lock_release(rtld_bind_lock, &lockstate);
2927 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2930 /* Unreference the object and its dependencies. */
2931 root->dl_refcount--;
2933 if (root->refcount == 1) {
2935 * The object will be no longer referenced, so we must unload it.
2936 * First, call the fini functions.
2938 objlist_call_fini(&list_fini, root, &lockstate);
2942 /* Finish cleaning up the newly-unreferenced objects. */
2943 GDB_STATE(RT_DELETE,&root->linkmap);
2944 unload_object(root);
2945 GDB_STATE(RT_CONSISTENT,NULL);
2949 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2950 lock_release(rtld_bind_lock, &lockstate);
2957 char *msg = error_message;
2958 error_message = NULL;
2963 dlopen(const char *name, int mode)
2966 return (rtld_dlopen(name, -1, mode));
2970 fdlopen(int fd, int mode)
2973 return (rtld_dlopen(NULL, fd, mode));
2977 rtld_dlopen(const char *name, int fd, int mode)
2979 RtldLockState lockstate;
2982 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2983 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2984 if (ld_tracing != NULL) {
2985 rlock_acquire(rtld_bind_lock, &lockstate);
2986 if (sigsetjmp(lockstate.env, 0) != 0)
2987 lock_upgrade(rtld_bind_lock, &lockstate);
2988 environ = (char **)*get_program_var_addr("environ", &lockstate);
2989 lock_release(rtld_bind_lock, &lockstate);
2991 lo_flags = RTLD_LO_DLOPEN;
2992 if (mode & RTLD_NODELETE)
2993 lo_flags |= RTLD_LO_NODELETE;
2994 if (mode & RTLD_NOLOAD)
2995 lo_flags |= RTLD_LO_NOLOAD;
2996 if (ld_tracing != NULL)
2997 lo_flags |= RTLD_LO_TRACE;
2999 return (dlopen_object(name, fd, obj_main, lo_flags,
3000 mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
3004 dlopen_cleanup(Obj_Entry *obj)
3009 if (obj->refcount == 0)
3014 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
3015 int mode, RtldLockState *lockstate)
3017 Obj_Entry **old_obj_tail;
3020 RtldLockState mlockstate;
3023 objlist_init(&initlist);
3025 if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
3026 wlock_acquire(rtld_bind_lock, &mlockstate);
3027 lockstate = &mlockstate;
3029 GDB_STATE(RT_ADD,NULL);
3031 old_obj_tail = obj_tail;
3033 if (name == NULL && fd == -1) {
3037 obj = load_object(name, fd, refobj, lo_flags);
3042 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
3043 objlist_push_tail(&list_global, obj);
3044 if (*old_obj_tail != NULL) { /* We loaded something new. */
3045 assert(*old_obj_tail == obj);
3046 result = load_needed_objects(obj,
3047 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
3051 result = rtld_verify_versions(&obj->dagmembers);
3052 if (result != -1 && ld_tracing)
3054 if (result == -1 || relocate_object_dag(obj,
3055 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
3056 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3058 dlopen_cleanup(obj);
3060 } else if (lo_flags & RTLD_LO_EARLY) {
3062 * Do not call the init functions for early loaded
3063 * filtees. The image is still not initialized enough
3066 * Our object is found by the global object list and
3067 * will be ordered among all init calls done right
3068 * before transferring control to main.
3071 /* Make list of init functions to call. */
3072 initlist_add_objects(obj, &obj->next, &initlist);
3075 * Process all no_delete objects here, given them own
3076 * DAGs to prevent their dependencies from being unloaded.
3077 * This has to be done after we have loaded all of the
3078 * dependencies, so that we do not miss any.
3081 process_nodelete(obj);
3084 * Bump the reference counts for objects on this DAG. If
3085 * this is the first dlopen() call for the object that was
3086 * already loaded as a dependency, initialize the dag
3092 if ((lo_flags & RTLD_LO_TRACE) != 0)
3095 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
3096 obj->z_nodelete) && !obj->ref_nodel) {
3097 dbg("obj %s nodelete", obj->path);
3099 obj->z_nodelete = obj->ref_nodel = true;
3103 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
3105 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
3107 if (!(lo_flags & RTLD_LO_EARLY)) {
3108 map_stacks_exec(lockstate);
3111 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
3112 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3114 objlist_clear(&initlist);
3115 dlopen_cleanup(obj);
3116 if (lockstate == &mlockstate)
3117 lock_release(rtld_bind_lock, lockstate);
3121 if (!(lo_flags & RTLD_LO_EARLY)) {
3122 /* Call the init functions. */
3123 objlist_call_init(&initlist, lockstate);
3125 objlist_clear(&initlist);
3126 if (lockstate == &mlockstate)
3127 lock_release(rtld_bind_lock, lockstate);
3130 trace_loaded_objects(obj);
3131 if (lockstate == &mlockstate)
3132 lock_release(rtld_bind_lock, lockstate);
3137 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
3141 const Obj_Entry *obj, *defobj;
3144 RtldLockState lockstate;
3150 symlook_init(&req, name);
3152 req.flags = flags | SYMLOOK_IN_PLT;
3153 req.lockstate = &lockstate;
3155 rlock_acquire(rtld_bind_lock, &lockstate);
3156 if (sigsetjmp(lockstate.env, 0) != 0)
3157 lock_upgrade(rtld_bind_lock, &lockstate);
3158 if (handle == NULL || handle == RTLD_NEXT ||
3159 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
3161 if ((obj = obj_from_addr(retaddr)) == NULL) {
3162 _rtld_error("Cannot determine caller's shared object");
3163 lock_release(rtld_bind_lock, &lockstate);
3166 if (handle == NULL) { /* Just the caller's shared object. */
3167 res = symlook_obj(&req, obj);
3170 defobj = req.defobj_out;
3172 } else if (handle == RTLD_NEXT || /* Objects after caller's */
3173 handle == RTLD_SELF) { /* ... caller included */
3174 if (handle == RTLD_NEXT)
3176 for (; obj != NULL; obj = obj->next) {
3177 res = symlook_obj(&req, obj);
3180 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
3182 defobj = req.defobj_out;
3183 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3189 * Search the dynamic linker itself, and possibly resolve the
3190 * symbol from there. This is how the application links to
3191 * dynamic linker services such as dlopen.
3193 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3194 res = symlook_obj(&req, &obj_rtld);
3197 defobj = req.defobj_out;
3201 assert(handle == RTLD_DEFAULT);
3202 res = symlook_default(&req, obj);
3204 defobj = req.defobj_out;
3209 if ((obj = dlcheck(handle)) == NULL) {
3210 lock_release(rtld_bind_lock, &lockstate);
3214 donelist_init(&donelist);
3215 if (obj->mainprog) {
3216 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
3217 res = symlook_global(&req, &donelist);
3220 defobj = req.defobj_out;
3223 * Search the dynamic linker itself, and possibly resolve the
3224 * symbol from there. This is how the application links to
3225 * dynamic linker services such as dlopen.
3227 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3228 res = symlook_obj(&req, &obj_rtld);
3231 defobj = req.defobj_out;
3236 /* Search the whole DAG rooted at the given object. */
3237 res = symlook_list(&req, &obj->dagmembers, &donelist);
3240 defobj = req.defobj_out;
3246 lock_release(rtld_bind_lock, &lockstate);
3249 * The value required by the caller is derived from the value
3250 * of the symbol. this is simply the relocated value of the
3253 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3254 return (make_function_pointer(def, defobj));
3255 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3256 return (rtld_resolve_ifunc(defobj, def));
3257 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3258 ti.ti_module = defobj->tlsindex;
3259 ti.ti_offset = def->st_value;
3260 return (__tls_get_addr(&ti));
3262 return (defobj->relocbase + def->st_value);
3265 _rtld_error("Undefined symbol \"%s\"", name);
3266 lock_release(rtld_bind_lock, &lockstate);
3271 dlsym(void *handle, const char *name)
3273 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3278 dlfunc(void *handle, const char *name)
3285 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3291 dlvsym(void *handle, const char *name, const char *version)
3295 ventry.name = version;
3297 ventry.hash = elf_hash(version);
3299 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3304 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3306 const Obj_Entry *obj;
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 rtld_fill_dl_phdr_info(obj, phdr_info);
3317 lock_release(rtld_bind_lock, &lockstate);
3322 dladdr(const void *addr, Dl_info *info)
3324 const Obj_Entry *obj;
3327 unsigned long symoffset;
3328 RtldLockState lockstate;
3330 rlock_acquire(rtld_bind_lock, &lockstate);
3331 obj = obj_from_addr(addr);
3333 _rtld_error("No shared object contains address");
3334 lock_release(rtld_bind_lock, &lockstate);
3337 info->dli_fname = obj->path;
3338 info->dli_fbase = obj->mapbase;
3339 info->dli_saddr = NULL;
3340 info->dli_sname = NULL;
3343 * Walk the symbol list looking for the symbol whose address is
3344 * closest to the address sent in.
3346 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3347 def = obj->symtab + symoffset;
3350 * For skip the symbol if st_shndx is either SHN_UNDEF or
3353 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3357 * If the symbol is greater than the specified address, or if it
3358 * is further away from addr than the current nearest symbol,
3361 symbol_addr = obj->relocbase + def->st_value;
3362 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3365 /* Update our idea of the nearest symbol. */
3366 info->dli_sname = obj->strtab + def->st_name;
3367 info->dli_saddr = symbol_addr;
3370 if (info->dli_saddr == addr)
3373 lock_release(rtld_bind_lock, &lockstate);
3378 dlinfo(void *handle, int request, void *p)
3380 const Obj_Entry *obj;
3381 RtldLockState lockstate;
3384 rlock_acquire(rtld_bind_lock, &lockstate);
3386 if (handle == NULL || handle == RTLD_SELF) {
3389 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3390 if ((obj = obj_from_addr(retaddr)) == NULL)
3391 _rtld_error("Cannot determine caller's shared object");
3393 obj = dlcheck(handle);
3396 lock_release(rtld_bind_lock, &lockstate);
3402 case RTLD_DI_LINKMAP:
3403 *((struct link_map const **)p) = &obj->linkmap;
3405 case RTLD_DI_ORIGIN:
3406 error = rtld_dirname(obj->path, p);
3409 case RTLD_DI_SERINFOSIZE:
3410 case RTLD_DI_SERINFO:
3411 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3415 _rtld_error("Invalid request %d passed to dlinfo()", request);
3419 lock_release(rtld_bind_lock, &lockstate);
3425 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3428 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3429 phdr_info->dlpi_name = obj->path;
3430 phdr_info->dlpi_phdr = obj->phdr;
3431 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3432 phdr_info->dlpi_tls_modid = obj->tlsindex;
3433 phdr_info->dlpi_tls_data = obj->tlsinit;
3434 phdr_info->dlpi_adds = obj_loads;
3435 phdr_info->dlpi_subs = obj_loads - obj_count;
3439 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3441 struct dl_phdr_info phdr_info;
3442 const Obj_Entry *obj;
3443 RtldLockState bind_lockstate, phdr_lockstate;
3446 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3447 rlock_acquire(rtld_bind_lock, &bind_lockstate);
3451 for (obj = obj_list; obj != NULL; obj = obj->next) {
3452 rtld_fill_dl_phdr_info(obj, &phdr_info);
3453 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
3458 rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info);
3459 error = callback(&phdr_info, sizeof(phdr_info), param);
3462 lock_release(rtld_bind_lock, &bind_lockstate);
3463 lock_release(rtld_phdr_lock, &phdr_lockstate);
3469 fill_search_info(const char *dir, size_t dirlen, void *param)
3471 struct fill_search_info_args *arg;
3475 if (arg->request == RTLD_DI_SERINFOSIZE) {
3476 arg->serinfo->dls_cnt ++;
3477 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3479 struct dl_serpath *s_entry;
3481 s_entry = arg->serpath;
3482 s_entry->dls_name = arg->strspace;
3483 s_entry->dls_flags = arg->flags;
3485 strncpy(arg->strspace, dir, dirlen);
3486 arg->strspace[dirlen] = '\0';
3488 arg->strspace += dirlen + 1;
3496 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3498 struct dl_serinfo _info;
3499 struct fill_search_info_args args;
3501 args.request = RTLD_DI_SERINFOSIZE;
3502 args.serinfo = &_info;
3504 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3507 path_enumerate(obj->rpath, fill_search_info, &args);
3508 path_enumerate(ld_library_path, fill_search_info, &args);
3509 path_enumerate(obj->runpath, fill_search_info, &args);
3510 path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args);
3511 if (!obj->z_nodeflib)
3512 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
3515 if (request == RTLD_DI_SERINFOSIZE) {
3516 info->dls_size = _info.dls_size;
3517 info->dls_cnt = _info.dls_cnt;
3521 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3522 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3526 args.request = RTLD_DI_SERINFO;
3527 args.serinfo = info;
3528 args.serpath = &info->dls_serpath[0];
3529 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3531 args.flags = LA_SER_RUNPATH;
3532 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3535 args.flags = LA_SER_LIBPATH;
3536 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3539 args.flags = LA_SER_RUNPATH;
3540 if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
3543 args.flags = LA_SER_CONFIG;
3544 if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args)
3548 args.flags = LA_SER_DEFAULT;
3549 if (!obj->z_nodeflib &&
3550 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3556 rtld_dirname(const char *path, char *bname)
3560 /* Empty or NULL string gets treated as "." */
3561 if (path == NULL || *path == '\0') {
3567 /* Strip trailing slashes */
3568 endp = path + strlen(path) - 1;
3569 while (endp > path && *endp == '/')
3572 /* Find the start of the dir */
3573 while (endp > path && *endp != '/')
3576 /* Either the dir is "/" or there are no slashes */
3578 bname[0] = *endp == '/' ? '/' : '.';
3584 } while (endp > path && *endp == '/');
3587 if (endp - path + 2 > PATH_MAX)
3589 _rtld_error("Filename is too long: %s", path);
3593 strncpy(bname, path, endp - path + 1);
3594 bname[endp - path + 1] = '\0';
3599 rtld_dirname_abs(const char *path, char *base)
3601 char base_rel[PATH_MAX];
3603 if (rtld_dirname(path, base) == -1)
3607 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
3608 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
3609 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
3611 strcpy(base, base_rel);
3616 linkmap_add(Obj_Entry *obj)
3618 struct link_map *l = &obj->linkmap;
3619 struct link_map *prev;
3621 obj->linkmap.l_name = obj->path;
3622 obj->linkmap.l_addr = obj->mapbase;
3623 obj->linkmap.l_ld = obj->dynamic;
3625 if (r_debug.r_map == NULL) {
3631 * Scan to the end of the list, but not past the entry for the
3632 * dynamic linker, which we want to keep at the very end.
3634 for (prev = r_debug.r_map;
3635 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3636 prev = prev->l_next)
3639 /* Link in the new entry. */
3641 l->l_next = prev->l_next;
3642 if (l->l_next != NULL)
3643 l->l_next->l_prev = l;
3648 linkmap_delete(Obj_Entry *obj)
3650 struct link_map *l = &obj->linkmap;
3652 if (l->l_prev == NULL) {
3653 if ((r_debug.r_map = l->l_next) != NULL)
3654 l->l_next->l_prev = NULL;
3658 if ((l->l_prev->l_next = l->l_next) != NULL)
3659 l->l_next->l_prev = l->l_prev;
3663 * Function for the debugger to set a breakpoint on to gain control.
3665 * The two parameters allow the debugger to easily find and determine
3666 * what the runtime loader is doing and to whom it is doing it.
3668 * When the loadhook trap is hit (r_debug_state, set at program
3669 * initialization), the arguments can be found on the stack:
3671 * +8 struct link_map *m
3672 * +4 struct r_debug *rd
3676 r_debug_state(struct r_debug* rd, struct link_map *m)
3679 * The following is a hack to force the compiler to emit calls to
3680 * this function, even when optimizing. If the function is empty,
3681 * the compiler is not obliged to emit any code for calls to it,
3682 * even when marked __noinline. However, gdb depends on those
3685 __asm __volatile("" : : : "memory");
3689 * A function called after init routines have completed. This can be used to
3690 * break before a program's entry routine is called, and can be used when
3691 * main is not available in the symbol table.
3694 _r_debug_postinit(struct link_map *m)
3697 /* See r_debug_state(). */
3698 __asm __volatile("" : : : "memory");
3702 * Get address of the pointer variable in the main program.
3703 * Prefer non-weak symbol over the weak one.
3705 static const void **
3706 get_program_var_addr(const char *name, RtldLockState *lockstate)
3711 symlook_init(&req, name);
3712 req.lockstate = lockstate;
3713 donelist_init(&donelist);
3714 if (symlook_global(&req, &donelist) != 0)
3716 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3717 return ((const void **)make_function_pointer(req.sym_out,
3719 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3720 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3722 return ((const void **)(req.defobj_out->relocbase +
3723 req.sym_out->st_value));
3727 * Set a pointer variable in the main program to the given value. This
3728 * is used to set key variables such as "environ" before any of the
3729 * init functions are called.
3732 set_program_var(const char *name, const void *value)
3736 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3737 dbg("\"%s\": *%p <-- %p", name, addr, value);
3743 * Search the global objects, including dependencies and main object,
3744 * for the given symbol.
3747 symlook_global(SymLook *req, DoneList *donelist)
3750 const Objlist_Entry *elm;
3753 symlook_init_from_req(&req1, req);
3755 /* Search all objects loaded at program start up. */
3756 if (req->defobj_out == NULL ||
3757 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3758 res = symlook_list(&req1, &list_main, donelist);
3759 if (res == 0 && (req->defobj_out == NULL ||
3760 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3761 req->sym_out = req1.sym_out;
3762 req->defobj_out = req1.defobj_out;
3763 assert(req->defobj_out != NULL);
3767 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3768 STAILQ_FOREACH(elm, &list_global, link) {
3769 if (req->defobj_out != NULL &&
3770 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3772 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3773 if (res == 0 && (req->defobj_out == NULL ||
3774 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3775 req->sym_out = req1.sym_out;
3776 req->defobj_out = req1.defobj_out;
3777 assert(req->defobj_out != NULL);
3781 return (req->sym_out != NULL ? 0 : ESRCH);
3785 * This is a special version of getenv which is far more efficient
3786 * at finding LD_ environment vars.
3790 _getenv_ld(const char *id)
3794 int idlen = strlen(id);
3796 if (ld_index == LD_ARY_CACHE)
3798 if (ld_index == 0) {
3799 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
3800 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
3807 for (i = ld_index - 1; i >= 0; --i) {
3808 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
3809 return(ld_ary[i] + idlen + 1);
3815 * Given a symbol name in a referencing object, find the corresponding
3816 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3817 * no definition was found. Returns a pointer to the Obj_Entry of the
3818 * defining object via the reference parameter DEFOBJ_OUT.
3821 symlook_default(SymLook *req, const Obj_Entry *refobj)
3824 const Objlist_Entry *elm;
3828 donelist_init(&donelist);
3829 symlook_init_from_req(&req1, req);
3831 /* Look first in the referencing object if linked symbolically. */
3832 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3833 res = symlook_obj(&req1, refobj);
3835 req->sym_out = req1.sym_out;
3836 req->defobj_out = req1.defobj_out;
3837 assert(req->defobj_out != NULL);
3841 symlook_global(req, &donelist);
3843 /* Search all dlopened DAGs containing the referencing object. */
3844 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3845 if (req->sym_out != NULL &&
3846 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3848 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3849 if (res == 0 && (req->sym_out == NULL ||
3850 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3851 req->sym_out = req1.sym_out;
3852 req->defobj_out = req1.defobj_out;
3853 assert(req->defobj_out != NULL);
3858 * Search the dynamic linker itself, and possibly resolve the
3859 * symbol from there. This is how the application links to
3860 * dynamic linker services such as dlopen.
3862 if (req->sym_out == NULL ||
3863 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3864 res = symlook_obj(&req1, &obj_rtld);
3866 req->sym_out = req1.sym_out;
3867 req->defobj_out = req1.defobj_out;
3868 assert(req->defobj_out != NULL);
3872 return (req->sym_out != NULL ? 0 : ESRCH);
3876 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3879 const Obj_Entry *defobj;
3880 const Objlist_Entry *elm;
3886 STAILQ_FOREACH(elm, objlist, link) {
3887 if (donelist_check(dlp, elm->obj))
3889 symlook_init_from_req(&req1, req);
3890 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3891 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3893 defobj = req1.defobj_out;
3894 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3901 req->defobj_out = defobj;
3908 * Search the chain of DAGS cointed to by the given Needed_Entry
3909 * for a symbol of the given name. Each DAG is scanned completely
3910 * before advancing to the next one. Returns a pointer to the symbol,
3911 * or NULL if no definition was found.
3914 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3917 const Needed_Entry *n;
3918 const Obj_Entry *defobj;
3924 symlook_init_from_req(&req1, req);
3925 for (n = needed; n != NULL; n = n->next) {
3926 if (n->obj == NULL ||
3927 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3929 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3931 defobj = req1.defobj_out;
3932 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3938 req->defobj_out = defobj;
3945 * Search the symbol table of a single shared object for a symbol of
3946 * the given name and version, if requested. Returns a pointer to the
3947 * symbol, or NULL if no definition was found. If the object is
3948 * filter, return filtered symbol from filtee.
3950 * The symbol's hash value is passed in for efficiency reasons; that
3951 * eliminates many recomputations of the hash value.
3954 symlook_obj(SymLook *req, const Obj_Entry *obj)
3958 int flags, res, mres;
3961 * If there is at least one valid hash at this point, we prefer to
3962 * use the faster GNU version if available.
3964 if (obj->valid_hash_gnu)
3965 mres = symlook_obj1_gnu(req, obj);
3966 else if (obj->valid_hash_sysv)
3967 mres = symlook_obj1_sysv(req, obj);
3972 if (obj->needed_filtees != NULL) {
3973 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3974 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3975 donelist_init(&donelist);
3976 symlook_init_from_req(&req1, req);
3977 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3979 req->sym_out = req1.sym_out;
3980 req->defobj_out = req1.defobj_out;
3984 if (obj->needed_aux_filtees != NULL) {
3985 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3986 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3987 donelist_init(&donelist);
3988 symlook_init_from_req(&req1, req);
3989 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3991 req->sym_out = req1.sym_out;
3992 req->defobj_out = req1.defobj_out;
4000 /* Symbol match routine common to both hash functions */
4002 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
4003 const unsigned long symnum)
4006 const Elf_Sym *symp;
4009 symp = obj->symtab + symnum;
4010 strp = obj->strtab + symp->st_name;
4012 switch (ELF_ST_TYPE(symp->st_info)) {
4018 if (symp->st_value == 0)
4022 if (symp->st_shndx != SHN_UNDEF)
4024 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
4025 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
4031 if (strcmp(req->name, strp) != 0)
4034 if (req->ventry == NULL) {
4035 if (obj->versyms != NULL) {
4036 verndx = VER_NDX(obj->versyms[symnum]);
4037 if (verndx > obj->vernum) {
4039 "%s: symbol %s references wrong version %d",
4040 obj->path, obj->strtab + symnum, verndx);
4044 * If we are not called from dlsym (i.e. this
4045 * is a normal relocation from unversioned
4046 * binary), accept the symbol immediately if
4047 * it happens to have first version after this
4048 * shared object became versioned. Otherwise,
4049 * if symbol is versioned and not hidden,
4050 * remember it. If it is the only symbol with
4051 * this name exported by the shared object, it
4052 * will be returned as a match by the calling
4053 * function. If symbol is global (verndx < 2)
4054 * accept it unconditionally.
4056 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
4057 verndx == VER_NDX_GIVEN) {
4058 result->sym_out = symp;
4061 else if (verndx >= VER_NDX_GIVEN) {
4062 if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
4064 if (result->vsymp == NULL)
4065 result->vsymp = symp;
4071 result->sym_out = symp;
4074 if (obj->versyms == NULL) {
4075 if (object_match_name(obj, req->ventry->name)) {
4076 _rtld_error("%s: object %s should provide version %s "
4077 "for symbol %s", obj_rtld.path, obj->path,
4078 req->ventry->name, obj->strtab + symnum);
4082 verndx = VER_NDX(obj->versyms[symnum]);
4083 if (verndx > obj->vernum) {
4084 _rtld_error("%s: symbol %s references wrong version %d",
4085 obj->path, obj->strtab + symnum, verndx);
4088 if (obj->vertab[verndx].hash != req->ventry->hash ||
4089 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
4091 * Version does not match. Look if this is a
4092 * global symbol and if it is not hidden. If
4093 * global symbol (verndx < 2) is available,
4094 * use it. Do not return symbol if we are
4095 * called by dlvsym, because dlvsym looks for
4096 * a specific version and default one is not
4097 * what dlvsym wants.
4099 if ((req->flags & SYMLOOK_DLSYM) ||
4100 (verndx >= VER_NDX_GIVEN) ||
4101 (obj->versyms[symnum] & VER_NDX_HIDDEN))
4105 result->sym_out = symp;
4110 * Search for symbol using SysV hash function.
4111 * obj->buckets is known not to be NULL at this point; the test for this was
4112 * performed with the obj->valid_hash_sysv assignment.
4115 symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj)
4117 unsigned long symnum;
4118 Sym_Match_Result matchres;
4120 matchres.sym_out = NULL;
4121 matchres.vsymp = NULL;
4122 matchres.vcount = 0;
4124 for (symnum = obj->buckets[req->hash % obj->nbuckets];
4125 symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
4126 if (symnum >= obj->nchains)
4127 return (ESRCH); /* Bad object */
4129 if (matched_symbol(req, obj, &matchres, symnum)) {
4130 req->sym_out = matchres.sym_out;
4131 req->defobj_out = obj;
4135 if (matchres.vcount == 1) {
4136 req->sym_out = matchres.vsymp;
4137 req->defobj_out = obj;
4143 /* Search for symbol using GNU hash function */
4145 symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj)
4147 Elf_Addr bloom_word;
4148 const Elf32_Word *hashval;
4150 Sym_Match_Result matchres;
4151 unsigned int h1, h2;
4152 unsigned long symnum;
4154 matchres.sym_out = NULL;
4155 matchres.vsymp = NULL;
4156 matchres.vcount = 0;
4158 /* Pick right bitmask word from Bloom filter array */
4159 bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) &
4160 obj->maskwords_bm_gnu];
4162 /* Calculate modulus word size of gnu hash and its derivative */
4163 h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1);
4164 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1));
4166 /* Filter out the "definitely not in set" queries */
4167 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
4170 /* Locate hash chain and corresponding value element*/
4171 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
4174 hashval = &obj->chain_zero_gnu[bucket];
4176 if (((*hashval ^ req->hash_gnu) >> 1) == 0) {
4177 symnum = hashval - obj->chain_zero_gnu;
4178 if (matched_symbol(req, obj, &matchres, symnum)) {
4179 req->sym_out = matchres.sym_out;
4180 req->defobj_out = obj;
4184 } while ((*hashval++ & 1) == 0);
4185 if (matchres.vcount == 1) {
4186 req->sym_out = matchres.vsymp;
4187 req->defobj_out = obj;
4194 trace_loaded_objects(Obj_Entry *obj)
4196 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
4199 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
4202 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
4203 fmt1 = "\t%o => %p (%x)\n";
4205 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
4206 fmt2 = "\t%o (%x)\n";
4208 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");
4210 for (; obj; obj = obj->next) {
4211 Needed_Entry *needed;
4215 if (list_containers && obj->needed != NULL)
4216 rtld_printf("%s:\n", obj->path);
4217 for (needed = obj->needed; needed; needed = needed->next) {
4218 if (needed->obj != NULL) {
4219 if (needed->obj->traced && !list_containers)
4221 needed->obj->traced = true;
4222 path = needed->obj->path;
4226 name = (char *)obj->strtab + needed->name;
4227 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
4229 fmt = is_lib ? fmt1 : fmt2;
4230 while ((c = *fmt++) != '\0') {
4256 rtld_putstr(main_local);
4259 rtld_putstr(obj_main->path);
4268 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4281 * Unload a dlopened object and its dependencies from memory and from
4282 * our data structures. It is assumed that the DAG rooted in the
4283 * object has already been unreferenced, and that the object has a
4284 * reference count of 0.
4287 unload_object(Obj_Entry *root)
4292 assert(root->refcount == 0);
4295 * Pass over the DAG removing unreferenced objects from
4296 * appropriate lists.
4298 unlink_object(root);
4300 /* Unmap all objects that are no longer referenced. */
4301 linkp = &obj_list->next;
4302 while ((obj = *linkp) != NULL) {
4303 if (obj->refcount == 0) {
4304 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
4306 dbg("unloading \"%s\"", obj->path);
4307 unload_filtees(root);
4308 munmap(obj->mapbase, obj->mapsize);
4309 linkmap_delete(obj);
4320 unlink_object(Obj_Entry *root)
4324 if (root->refcount == 0) {
4325 /* Remove the object from the RTLD_GLOBAL list. */
4326 objlist_remove(&list_global, root);
4328 /* Remove the object from all objects' DAG lists. */
4329 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4330 objlist_remove(&elm->obj->dldags, root);
4331 if (elm->obj != root)
4332 unlink_object(elm->obj);
4338 ref_dag(Obj_Entry *root)
4342 assert(root->dag_inited);
4343 STAILQ_FOREACH(elm, &root->dagmembers, link)
4344 elm->obj->refcount++;
4348 unref_dag(Obj_Entry *root)
4352 assert(root->dag_inited);
4353 STAILQ_FOREACH(elm, &root->dagmembers, link)
4354 elm->obj->refcount--;
4358 * Common code for MD __tls_get_addr().
4361 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
4363 Elf_Addr* dtv = *dtvp;
4364 RtldLockState lockstate;
4366 /* Check dtv generation in case new modules have arrived */
4367 if (dtv[0] != tls_dtv_generation) {
4371 wlock_acquire(rtld_bind_lock, &lockstate);
4372 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4374 if (to_copy > tls_max_index)
4375 to_copy = tls_max_index;
4376 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4377 newdtv[0] = tls_dtv_generation;
4378 newdtv[1] = tls_max_index;
4380 lock_release(rtld_bind_lock, &lockstate);
4381 dtv = *dtvp = newdtv;
4384 /* Dynamically allocate module TLS if necessary */
4385 if (!dtv[index + 1]) {
4386 /* Signal safe, wlock will block out signals. */
4387 wlock_acquire(rtld_bind_lock, &lockstate);
4388 if (!dtv[index + 1])
4389 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4390 lock_release(rtld_bind_lock, &lockstate);
4392 return ((void *)(dtv[index + 1] + offset));
4395 #if defined(RTLD_STATIC_TLS_VARIANT_II)
4398 * Allocate the static TLS area. Return a pointer to the TCB. The
4399 * static area is based on negative offsets relative to the tcb.
4401 * The TCB contains an errno pointer for the system call layer, but because
4402 * we are the RTLD we really have no idea how the caller was compiled so
4403 * the information has to be passed in. errno can either be:
4405 * type 0 errno is a simple non-TLS global pointer.
4406 * (special case for e.g. libc_rtld)
4407 * type 1 errno accessed by GOT entry (dynamically linked programs)
4408 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
4411 allocate_tls(Obj_Entry *objs)
4416 struct tls_tcb *tcb;
4421 * Allocate the new TCB. static TLS storage is placed just before the
4422 * TCB to support the %gs:OFFSET (negative offset) model.
4424 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4425 ~RTLD_STATIC_TLS_ALIGN_MASK;
4426 tcb = malloc(data_size + sizeof(*tcb));
4427 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
4429 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
4430 dtv = malloc(dtv_size);
4431 bzero(dtv, dtv_size);
4433 #ifdef RTLD_TCB_HAS_SELF_POINTER
4434 tcb->tcb_self = tcb;
4437 tcb->tcb_pthread = NULL;
4439 dtv[0] = tls_dtv_generation;
4440 dtv[1] = tls_max_index;
4442 for (obj = objs; obj; obj = obj->next) {
4443 if (obj->tlsoffset) {
4444 addr = (Elf_Addr)tcb - obj->tlsoffset;
4445 memset((void *)(addr + obj->tlsinitsize),
4446 0, obj->tlssize - obj->tlsinitsize);
4448 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4449 dtv[obj->tlsindex + 1] = addr;
4456 free_tls(struct tls_tcb *tcb)
4460 Elf_Addr tls_start, tls_end;
4463 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4464 ~RTLD_STATIC_TLS_ALIGN_MASK;
4468 tls_end = (Elf_Addr)tcb;
4469 tls_start = (Elf_Addr)tcb - data_size;
4470 for (i = 0; i < dtv_size; i++) {
4471 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
4472 free((void *)dtv[i+2]);
4477 free((void*) tls_start);
4481 #error "Unsupported TLS layout"
4485 * Allocate TLS block for module with given index.
4488 allocate_module_tls(int index)
4493 for (obj = obj_list; obj; obj = obj->next) {
4494 if (obj->tlsindex == index)
4498 _rtld_error("Can't find module with TLS index %d", index);
4502 p = malloc(obj->tlssize);
4504 _rtld_error("Cannot allocate TLS block for index %d", index);
4507 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4508 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4514 allocate_tls_offset(Obj_Entry *obj)
4521 if (obj->tlssize == 0) {
4522 obj->tls_done = true;
4526 if (obj->tlsindex == 1)
4527 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4529 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4530 obj->tlssize, obj->tlsalign);
4533 * If we have already fixed the size of the static TLS block, we
4534 * must stay within that size. When allocating the static TLS, we
4535 * leave a small amount of space spare to be used for dynamically
4536 * loading modules which use static TLS.
4538 if (tls_static_space) {
4539 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4543 tls_last_offset = obj->tlsoffset = off;
4544 tls_last_size = obj->tlssize;
4545 obj->tls_done = true;
4551 free_tls_offset(Obj_Entry *obj)
4553 #ifdef RTLD_STATIC_TLS_VARIANT_II
4555 * If we were the last thing to allocate out of the static TLS
4556 * block, we give our space back to the 'allocator'. This is a
4557 * simplistic workaround to allow libGL.so.1 to be loaded and
4558 * unloaded multiple times. We only handle the Variant II
4559 * mechanism for now - this really needs a proper allocator.
4561 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
4562 == calculate_tls_end(tls_last_offset, tls_last_size)) {
4563 tls_last_offset -= obj->tlssize;
4570 _rtld_allocate_tls(void)
4572 struct tls_tcb *new_tcb;
4573 RtldLockState lockstate;
4575 wlock_acquire(rtld_bind_lock, &lockstate);
4576 new_tcb = allocate_tls(obj_list);
4577 lock_release(rtld_bind_lock, &lockstate);
4582 _rtld_free_tls(struct tls_tcb *tcb)
4584 RtldLockState lockstate;
4586 wlock_acquire(rtld_bind_lock, &lockstate);
4588 lock_release(rtld_bind_lock, &lockstate);
4592 object_add_name(Obj_Entry *obj, const char *name)
4598 entry = malloc(sizeof(Name_Entry) + len);
4600 if (entry != NULL) {
4601 strcpy(entry->name, name);
4602 STAILQ_INSERT_TAIL(&obj->names, entry, link);
4607 object_match_name(const Obj_Entry *obj, const char *name)
4611 STAILQ_FOREACH(entry, &obj->names, link) {
4612 if (strcmp(name, entry->name) == 0)
4619 locate_dependency(const Obj_Entry *obj, const char *name)
4621 const Objlist_Entry *entry;
4622 const Needed_Entry *needed;
4624 STAILQ_FOREACH(entry, &list_main, link) {
4625 if (object_match_name(entry->obj, name))
4629 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4630 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4631 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4633 * If there is DT_NEEDED for the name we are looking for,
4634 * we are all set. Note that object might not be found if
4635 * dependency was not loaded yet, so the function can
4636 * return NULL here. This is expected and handled
4637 * properly by the caller.
4639 return (needed->obj);
4642 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4648 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4649 const Elf_Vernaux *vna)
4651 const Elf_Verdef *vd;
4652 const char *vername;
4654 vername = refobj->strtab + vna->vna_name;
4655 vd = depobj->verdef;
4657 _rtld_error("%s: version %s required by %s not defined",
4658 depobj->path, vername, refobj->path);
4662 if (vd->vd_version != VER_DEF_CURRENT) {
4663 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4664 depobj->path, vd->vd_version);
4667 if (vna->vna_hash == vd->vd_hash) {
4668 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4669 ((char *)vd + vd->vd_aux);
4670 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4673 if (vd->vd_next == 0)
4675 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4677 if (vna->vna_flags & VER_FLG_WEAK)
4679 _rtld_error("%s: version %s required by %s not found",
4680 depobj->path, vername, refobj->path);
4685 rtld_verify_object_versions(Obj_Entry *obj)
4687 const Elf_Verneed *vn;
4688 const Elf_Verdef *vd;
4689 const Elf_Verdaux *vda;
4690 const Elf_Vernaux *vna;
4691 const Obj_Entry *depobj;
4692 int maxvernum, vernum;
4694 if (obj->ver_checked)
4696 obj->ver_checked = true;
4700 * Walk over defined and required version records and figure out
4701 * max index used by any of them. Do very basic sanity checking
4705 while (vn != NULL) {
4706 if (vn->vn_version != VER_NEED_CURRENT) {
4707 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4708 obj->path, vn->vn_version);
4711 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4713 vernum = VER_NEED_IDX(vna->vna_other);
4714 if (vernum > maxvernum)
4716 if (vna->vna_next == 0)
4718 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4720 if (vn->vn_next == 0)
4722 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4726 while (vd != NULL) {
4727 if (vd->vd_version != VER_DEF_CURRENT) {
4728 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4729 obj->path, vd->vd_version);
4732 vernum = VER_DEF_IDX(vd->vd_ndx);
4733 if (vernum > maxvernum)
4735 if (vd->vd_next == 0)
4737 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4744 * Store version information in array indexable by version index.
4745 * Verify that object version requirements are satisfied along the
4748 obj->vernum = maxvernum + 1;
4749 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
4752 while (vd != NULL) {
4753 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4754 vernum = VER_DEF_IDX(vd->vd_ndx);
4755 assert(vernum <= maxvernum);
4756 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4757 obj->vertab[vernum].hash = vd->vd_hash;
4758 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4759 obj->vertab[vernum].file = NULL;
4760 obj->vertab[vernum].flags = 0;
4762 if (vd->vd_next == 0)
4764 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4768 while (vn != NULL) {
4769 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4772 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4774 if (check_object_provided_version(obj, depobj, vna))
4776 vernum = VER_NEED_IDX(vna->vna_other);
4777 assert(vernum <= maxvernum);
4778 obj->vertab[vernum].hash = vna->vna_hash;
4779 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4780 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4781 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4782 VER_INFO_HIDDEN : 0;
4783 if (vna->vna_next == 0)
4785 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4787 if (vn->vn_next == 0)
4789 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4795 rtld_verify_versions(const Objlist *objlist)
4797 Objlist_Entry *entry;
4801 STAILQ_FOREACH(entry, objlist, link) {
4803 * Skip dummy objects or objects that have their version requirements
4806 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4808 if (rtld_verify_object_versions(entry->obj) == -1) {
4810 if (ld_tracing == NULL)
4814 if (rc == 0 || ld_tracing != NULL)
4815 rc = rtld_verify_object_versions(&obj_rtld);
4820 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4825 vernum = VER_NDX(obj->versyms[symnum]);
4826 if (vernum >= obj->vernum) {
4827 _rtld_error("%s: symbol %s has wrong verneed value %d",
4828 obj->path, obj->strtab + symnum, vernum);
4829 } else if (obj->vertab[vernum].hash != 0) {
4830 return &obj->vertab[vernum];
4837 _rtld_get_stack_prot(void)
4840 return (stack_prot);
4844 map_stacks_exec(RtldLockState *lockstate)
4848 * Stack protection must be implemented in the kernel before the dynamic
4849 * linker can handle PT_GNU_STACK sections.
4850 * The following is the FreeBSD implementation of map_stacks_exec()
4851 * void (*thr_map_stacks_exec)(void);
4853 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4855 * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4856 * get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4857 * if (thr_map_stacks_exec != NULL) {
4858 * stack_prot |= PROT_EXEC;
4859 * thr_map_stacks_exec();
4865 symlook_init(SymLook *dst, const char *name)
4868 bzero(dst, sizeof(*dst));
4870 dst->hash = elf_hash(name);
4871 dst->hash_gnu = gnu_hash(name);
4875 symlook_init_from_req(SymLook *dst, const SymLook *src)
4878 dst->name = src->name;
4879 dst->hash = src->hash;
4880 dst->hash_gnu = src->hash_gnu;
4881 dst->ventry = src->ventry;
4882 dst->flags = src->flags;
4883 dst->defobj_out = NULL;
4884 dst->sym_out = NULL;
4885 dst->lockstate = src->lockstate;
4890 * Parse a file descriptor number without pulling in more of libc (e.g. atoi).
4893 parse_libdir(const char *str)
4895 static const int RADIX = 10; /* XXXJA: possibly support hex? */
4902 for (c = *str; c != '\0'; c = *++str) {
4903 if (c < '0' || c > '9')
4910 /* Make sure we actually parsed something. */
4912 _rtld_error("failed to parse directory FD from '%s'", str);
4918 #ifdef ENABLE_OSRELDATE
4920 * Overrides for libc_pic-provided functions.
4924 __getosreldate(void)
4934 oid[1] = KERN_OSRELDATE;
4936 len = sizeof(osrel);
4937 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
4938 if (error == 0 && osrel > 0 && len == sizeof(osrel))
4945 * No unresolved symbols for rtld.
4948 __pthread_cxa_finalize(struct dl_phdr_info *a)
4953 rtld_strerror(int errnum)
4956 if (errnum < 0 || errnum >= sys_nerr)
4957 return ("Unknown error");
4958 return (sys_errlist[errnum]);