2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * Copyright 2009-2012 Konstantin Belousov <kib@FreeBSD.ORG>.
5 * Copyright 2012 John Marino <draco@marino.st>.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 * Dynamic linker for ELF.
34 * John Polstra <jdp@polstra.com>.
38 #error "GCC is needed to compile this file"
41 #include <sys/param.h>
42 #include <sys/mount.h>
45 #include <sys/sysctl.h>
47 #include <sys/utsname.h>
48 #include <sys/ktrace.h>
64 #include "rtld_printf.h"
68 #define PATH_RTLD "/libexec/ld-elf.so.1"
70 #define PATH_RTLD "/libexec/ld-elf32.so.1"
74 typedef void (*func_ptr_type)();
75 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
78 * Function declarations.
80 static const char *basename(const char *);
81 static void 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_pagesizes(Elf_Auxinfo **aux_info);
101 static void init_rtld(caddr_t, Elf_Auxinfo **);
102 static void initlist_add_neededs(Needed_Entry *, Objlist *);
103 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
104 static void linkmap_add(Obj_Entry *);
105 static void linkmap_delete(Obj_Entry *);
106 static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
107 static void unload_filtees(Obj_Entry *);
108 static int load_needed_objects(Obj_Entry *, int);
109 static int load_preload_objects(void);
110 static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int);
111 static void map_stacks_exec(RtldLockState *);
112 static Obj_Entry *obj_from_addr(const void *);
113 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
114 static void objlist_call_init(Objlist *, RtldLockState *);
115 static void objlist_clear(Objlist *);
116 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
117 static void objlist_init(Objlist *);
118 static void objlist_push_head(Objlist *, Obj_Entry *);
119 static void objlist_push_tail(Objlist *, Obj_Entry *);
120 static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
121 static void objlist_remove(Objlist *, Obj_Entry *);
122 static int parse_libdir(const char *);
123 static void *path_enumerate(const char *, path_enum_proc, void *);
124 static int relocate_object_dag(Obj_Entry *root, bool bind_now,
125 Obj_Entry *rtldobj, int flags, RtldLockState *lockstate);
126 static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
127 int flags, RtldLockState *lockstate);
128 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
130 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
131 int flags, RtldLockState *lockstate);
132 static int rtld_dirname(const char *, char *);
133 static int rtld_dirname_abs(const char *, char *);
134 static void *rtld_dlopen(const char *name, int fd, int mode);
135 static void rtld_exit(void);
136 static char *search_library_path(const char *, const char *);
137 static char *search_library_pathfds(const char *, const char *, int *);
138 static const void **get_program_var_addr(const char *, RtldLockState *);
139 static void set_program_var(const char *, const void *);
140 static int symlook_default(SymLook *, const Obj_Entry *refobj);
141 static int symlook_global(SymLook *, DoneList *);
142 static void symlook_init_from_req(SymLook *, const SymLook *);
143 static int symlook_list(SymLook *, const Objlist *, DoneList *);
144 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
145 static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
146 static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
147 static void trace_loaded_objects(Obj_Entry *);
148 static void unlink_object(Obj_Entry *);
149 static void unload_object(Obj_Entry *);
150 static void unref_dag(Obj_Entry *);
151 static void ref_dag(Obj_Entry *);
152 static char *origin_subst_one(char *, const char *, const char *, bool);
153 static char *origin_subst(char *, const char *);
154 static void preinit_main(void);
155 static int rtld_verify_versions(const Objlist *);
156 static int rtld_verify_object_versions(Obj_Entry *);
157 static void object_add_name(Obj_Entry *, const char *);
158 static int object_match_name(const Obj_Entry *, const char *);
159 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
160 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
161 struct dl_phdr_info *phdr_info);
162 static uint32_t gnu_hash(const char *);
163 static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
164 const unsigned long);
166 void r_debug_state(struct r_debug *, struct link_map *) __noinline __exported;
167 void _r_debug_postinit(struct link_map *) __noinline __exported;
169 int __sys_openat(int, const char *, int, ...);
174 static char *error_message; /* Message for dlerror(), or NULL */
175 struct r_debug r_debug __exported; /* for GDB; */
176 static bool libmap_disable; /* Disable libmap */
177 static bool ld_loadfltr; /* Immediate filters processing */
178 static char *libmap_override; /* Maps to use in addition to libmap.conf */
179 static bool trust; /* False for setuid and setgid programs */
180 static bool dangerous_ld_env; /* True if environment variables have been
181 used to affect the libraries loaded */
182 static char *ld_bind_now; /* Environment variable for immediate binding */
183 static char *ld_debug; /* Environment variable for debugging */
184 static char *ld_library_path; /* Environment variable for search path */
185 static char *ld_library_dirs; /* Environment variable for library descriptors */
186 static char *ld_preload; /* Environment variable for libraries to
188 static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
189 static char *ld_tracing; /* Called from ldd to print libs */
190 static char *ld_utrace; /* Use utrace() to log events. */
191 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
192 static Obj_Entry **obj_tail; /* Link field of last object in list */
193 static Obj_Entry *obj_main; /* The main program shared object */
194 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
195 static unsigned int obj_count; /* Number of objects in obj_list */
196 static unsigned int obj_loads; /* Number of objects in obj_list */
198 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
199 STAILQ_HEAD_INITIALIZER(list_global);
200 static Objlist list_main = /* Objects loaded at program startup */
201 STAILQ_HEAD_INITIALIZER(list_main);
202 static Objlist list_fini = /* Objects needing fini() calls */
203 STAILQ_HEAD_INITIALIZER(list_fini);
205 Elf_Sym sym_zero; /* For resolving undefined weak refs. */
207 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
209 extern Elf_Dyn _DYNAMIC;
210 #pragma weak _DYNAMIC
211 #ifndef RTLD_IS_DYNAMIC
212 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
215 int dlclose(void *) __exported;
216 char *dlerror(void) __exported;
217 void *dlopen(const char *, int) __exported;
218 void *fdlopen(int, int) __exported;
219 void *dlsym(void *, const char *) __exported;
220 dlfunc_t dlfunc(void *, const char *) __exported;
221 void *dlvsym(void *, const char *, const char *) __exported;
222 int dladdr(const void *, Dl_info *) __exported;
223 void dllockinit(void *, void *(*)(void *), void (*)(void *), void (*)(void *),
224 void (*)(void *), void (*)(void *), void (*)(void *)) __exported;
225 int dlinfo(void *, int , void *) __exported;
226 int dl_iterate_phdr(__dl_iterate_hdr_callback, void *) __exported;
227 int _rtld_addr_phdr(const void *, struct dl_phdr_info *) __exported;
228 int _rtld_get_stack_prot(void) __exported;
229 int _rtld_is_dlopened(void *) __exported;
230 void _rtld_error(const char *, ...) __exported;
232 int npagesizes, osreldate;
235 long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
237 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
238 static int max_stack_flags;
241 * Global declarations normally provided by crt1. The dynamic linker is
242 * not built with crt1, so we have to provide them ourselves.
248 * Used to pass argc, argv to init functions.
254 * Globals to control TLS allocation.
256 size_t tls_last_offset; /* Static TLS offset of last module */
257 size_t tls_last_size; /* Static TLS size of last module */
258 size_t tls_static_space; /* Static TLS space allocated */
259 size_t tls_static_max_align;
260 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
261 int tls_max_index = 1; /* Largest module index allocated */
263 bool ld_library_path_rpath = false;
266 * Fill in a DoneList with an allocation large enough to hold all of
267 * the currently-loaded objects. Keep this as a macro since it calls
268 * alloca and we want that to occur within the scope of the caller.
270 #define donelist_init(dlp) \
271 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
272 assert((dlp)->objs != NULL), \
273 (dlp)->num_alloc = obj_count, \
276 #define UTRACE_DLOPEN_START 1
277 #define UTRACE_DLOPEN_STOP 2
278 #define UTRACE_DLCLOSE_START 3
279 #define UTRACE_DLCLOSE_STOP 4
280 #define UTRACE_LOAD_OBJECT 5
281 #define UTRACE_UNLOAD_OBJECT 6
282 #define UTRACE_ADD_RUNDEP 7
283 #define UTRACE_PRELOAD_FINISHED 8
284 #define UTRACE_INIT_CALL 9
285 #define UTRACE_FINI_CALL 10
286 #define UTRACE_DLSYM_START 11
287 #define UTRACE_DLSYM_STOP 12
290 char sig[4]; /* 'RTLD' */
293 void *mapbase; /* Used for 'parent' and 'init/fini' */
295 int refcnt; /* Used for 'mode' */
296 char name[MAXPATHLEN];
299 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
300 if (ld_utrace != NULL) \
301 ld_utrace_log(e, h, mb, ms, r, n); \
305 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
306 int refcnt, const char *name)
308 struct utrace_rtld ut;
316 ut.mapbase = mapbase;
317 ut.mapsize = mapsize;
319 bzero(ut.name, sizeof(ut.name));
321 strlcpy(ut.name, name, sizeof(ut.name));
322 utrace(&ut, sizeof(ut));
326 * Main entry point for dynamic linking. The first argument is the
327 * stack pointer. The stack is expected to be laid out as described
328 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
329 * Specifically, the stack pointer points to a word containing
330 * ARGC. Following that in the stack is a null-terminated sequence
331 * of pointers to argument strings. Then comes a null-terminated
332 * sequence of pointers to environment strings. Finally, there is a
333 * sequence of "auxiliary vector" entries.
335 * The second argument points to a place to store the dynamic linker's
336 * exit procedure pointer and the third to a place to store the main
339 * The return value is the main program's entry point.
342 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
344 Elf_Auxinfo *aux_info[AT_COUNT];
352 Objlist_Entry *entry;
354 Obj_Entry **preload_tail;
355 Obj_Entry *last_interposer;
357 RtldLockState lockstate;
358 char *library_path_rpath;
363 * On entry, the dynamic linker itself has not been relocated yet.
364 * Be very careful not to reference any global data until after
365 * init_rtld has returned. It is OK to reference file-scope statics
366 * and string constants, and to call static and global functions.
369 /* Find the auxiliary vector on the stack. */
372 sp += argc + 1; /* Skip over arguments and NULL terminator */
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);
390 __progname = obj_rtld.path;
391 argv0 = argv[0] != NULL ? argv[0] : "(null)";
396 if (aux_info[AT_CANARY] != NULL &&
397 aux_info[AT_CANARY]->a_un.a_ptr != NULL) {
398 i = aux_info[AT_CANARYLEN]->a_un.a_val;
399 if (i > sizeof(__stack_chk_guard))
400 i = sizeof(__stack_chk_guard);
401 memcpy(__stack_chk_guard, aux_info[AT_CANARY]->a_un.a_ptr, i);
406 len = sizeof(__stack_chk_guard);
407 if (sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 ||
408 len != sizeof(__stack_chk_guard)) {
409 /* If sysctl was unsuccessful, use the "terminator canary". */
410 ((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
411 ((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
412 ((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
413 ((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
417 trust = !issetugid();
419 ld_bind_now = getenv(LD_ "BIND_NOW");
421 * If the process is tainted, then we un-set the dangerous environment
422 * variables. The process will be marked as tainted until setuid(2)
423 * is called. If any child process calls setuid(2) we do not want any
424 * future processes to honor the potentially un-safe variables.
427 if (unsetenv(LD_ "PRELOAD") || unsetenv(LD_ "LIBMAP") ||
428 unsetenv(LD_ "LIBRARY_PATH") || unsetenv(LD_ "LIBRARY_PATH_FDS") ||
429 unsetenv(LD_ "LIBMAP_DISABLE") ||
430 unsetenv(LD_ "DEBUG") || unsetenv(LD_ "ELF_HINTS_PATH") ||
431 unsetenv(LD_ "LOADFLTR") || unsetenv(LD_ "LIBRARY_PATH_RPATH")) {
432 _rtld_error("environment corrupt; aborting");
436 ld_debug = getenv(LD_ "DEBUG");
437 libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL;
438 libmap_override = getenv(LD_ "LIBMAP");
439 ld_library_path = getenv(LD_ "LIBRARY_PATH");
440 ld_library_dirs = getenv(LD_ "LIBRARY_PATH_FDS");
441 ld_preload = getenv(LD_ "PRELOAD");
442 ld_elf_hints_path = getenv(LD_ "ELF_HINTS_PATH");
443 ld_loadfltr = getenv(LD_ "LOADFLTR") != NULL;
444 library_path_rpath = getenv(LD_ "LIBRARY_PATH_RPATH");
445 if (library_path_rpath != NULL) {
446 if (library_path_rpath[0] == 'y' ||
447 library_path_rpath[0] == 'Y' ||
448 library_path_rpath[0] == '1')
449 ld_library_path_rpath = true;
451 ld_library_path_rpath = false;
453 dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
454 (ld_library_path != NULL) || (ld_preload != NULL) ||
455 (ld_elf_hints_path != NULL) || ld_loadfltr;
456 ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS");
457 ld_utrace = getenv(LD_ "UTRACE");
459 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
460 ld_elf_hints_path = _PATH_ELF_HINTS;
462 if (ld_debug != NULL && *ld_debug != '\0')
464 dbg("%s is initialized, base address = %p", __progname,
465 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
466 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
467 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
469 dbg("initializing thread locks");
473 * Load the main program, or process its program header if it is
476 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
477 int fd = aux_info[AT_EXECFD]->a_un.a_val;
478 dbg("loading main program");
479 obj_main = map_object(fd, argv0, NULL);
481 if (obj_main == NULL)
483 max_stack_flags = obj->stack_flags;
484 } else { /* Main program already loaded. */
485 const Elf_Phdr *phdr;
489 dbg("processing main program's program header");
490 assert(aux_info[AT_PHDR] != NULL);
491 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
492 assert(aux_info[AT_PHNUM] != NULL);
493 phnum = aux_info[AT_PHNUM]->a_un.a_val;
494 assert(aux_info[AT_PHENT] != NULL);
495 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
496 assert(aux_info[AT_ENTRY] != NULL);
497 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
498 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
502 if (aux_info[AT_EXECPATH] != 0) {
504 char buf[MAXPATHLEN];
506 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
507 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
508 if (kexecpath[0] == '/')
509 obj_main->path = kexecpath;
510 else if (getcwd(buf, sizeof(buf)) == NULL ||
511 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
512 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
513 obj_main->path = xstrdup(argv0);
515 obj_main->path = xstrdup(buf);
517 dbg("No AT_EXECPATH");
518 obj_main->path = xstrdup(argv0);
520 dbg("obj_main path %s", obj_main->path);
521 obj_main->mainprog = true;
523 if (aux_info[AT_STACKPROT] != NULL &&
524 aux_info[AT_STACKPROT]->a_un.a_val != 0)
525 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
529 * Get the actual dynamic linker pathname from the executable if
530 * possible. (It should always be possible.) That ensures that
531 * gdb will find the right dynamic linker even if a non-standard
534 if (obj_main->interp != NULL &&
535 strcmp(obj_main->interp, obj_rtld.path) != 0) {
537 obj_rtld.path = xstrdup(obj_main->interp);
538 __progname = obj_rtld.path;
542 digest_dynamic(obj_main, 0);
543 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
544 obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
545 obj_main->dynsymcount);
547 linkmap_add(obj_main);
548 linkmap_add(&obj_rtld);
550 /* Link the main program into the list of objects. */
551 *obj_tail = obj_main;
552 obj_tail = &obj_main->next;
556 /* Initialize a fake symbol for resolving undefined weak references. */
557 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
558 sym_zero.st_shndx = SHN_UNDEF;
559 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
562 libmap_disable = (bool)lm_init(libmap_override);
564 dbg("loading LD_PRELOAD libraries");
565 if (load_preload_objects() == -1)
567 preload_tail = obj_tail;
569 dbg("loading needed objects");
570 if (load_needed_objects(obj_main, 0) == -1)
573 /* Make a list of all objects loaded at startup. */
574 last_interposer = obj_main;
575 for (obj = obj_list; obj != NULL; obj = obj->next) {
576 if (obj->z_interpose && obj != obj_main) {
577 objlist_put_after(&list_main, last_interposer, obj);
578 last_interposer = obj;
580 objlist_push_tail(&list_main, obj);
585 dbg("checking for required versions");
586 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
589 if (ld_tracing) { /* We're done */
590 trace_loaded_objects(obj_main);
594 if (getenv(LD_ "DUMP_REL_PRE") != NULL) {
595 dump_relocations(obj_main);
600 * Processing tls relocations requires having the tls offsets
601 * initialized. Prepare offsets before starting initial
602 * relocation processing.
604 dbg("initializing initial thread local storage offsets");
605 STAILQ_FOREACH(entry, &list_main, link) {
607 * Allocate all the initial objects out of the static TLS
608 * block even if they didn't ask for it.
610 allocate_tls_offset(entry->obj);
613 if (relocate_objects(obj_main,
614 ld_bind_now != NULL && *ld_bind_now != '\0',
615 &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
618 dbg("doing copy relocations");
619 if (do_copy_relocations(obj_main) == -1)
622 if (getenv(LD_ "DUMP_REL_POST") != NULL) {
623 dump_relocations(obj_main);
628 * Setup TLS for main thread. This must be done after the
629 * relocations are processed, since tls initialization section
630 * might be the subject for relocations.
632 dbg("initializing initial thread local storage");
633 allocate_initial_tls(obj_list);
635 dbg("initializing key program variables");
636 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
637 set_program_var("environ", env);
638 set_program_var("__elf_aux_vector", aux);
640 /* Make a list of init functions to call. */
641 objlist_init(&initlist);
642 initlist_add_objects(obj_list, preload_tail, &initlist);
644 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
646 map_stacks_exec(NULL);
648 dbg("resolving ifuncs");
649 if (resolve_objects_ifunc(obj_main,
650 ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
654 if (!obj_main->crt_no_init) {
656 * Make sure we don't call the main program's init and fini
657 * functions for binaries linked with old crt1 which calls
660 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
661 obj_main->preinit_array = obj_main->init_array =
662 obj_main->fini_array = (Elf_Addr)NULL;
665 wlock_acquire(rtld_bind_lock, &lockstate);
666 if (obj_main->crt_no_init)
668 objlist_call_init(&initlist, &lockstate);
669 _r_debug_postinit(&obj_main->linkmap);
670 objlist_clear(&initlist);
671 dbg("loading filtees");
672 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
673 if (ld_loadfltr || obj->z_loadfltr)
674 load_filtees(obj, 0, &lockstate);
676 lock_release(rtld_bind_lock, &lockstate);
678 dbg("transferring control to program entry point = %p", obj_main->entry);
680 /* Return the exit procedure and the program entry point. */
681 *exit_proc = rtld_exit;
683 return (func_ptr_type) obj_main->entry;
687 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
692 ptr = (void *)make_function_pointer(def, obj);
693 target = ((Elf_Addr (*)(void))ptr)();
694 return ((void *)target);
698 _rtld_bind(Obj_Entry *obj, Elf_Size reloff)
702 const Obj_Entry *defobj;
705 RtldLockState lockstate;
707 rlock_acquire(rtld_bind_lock, &lockstate);
708 if (sigsetjmp(lockstate.env, 0) != 0)
709 lock_upgrade(rtld_bind_lock, &lockstate);
711 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
713 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
715 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
716 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
720 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
721 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
723 target = (Elf_Addr)(defobj->relocbase + def->st_value);
725 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
726 defobj->strtab + def->st_name, basename(obj->path),
727 (void *)target, basename(defobj->path));
730 * Write the new contents for the jmpslot. Note that depending on
731 * architecture, the value which we need to return back to the
732 * lazy binding trampoline may or may not be the target
733 * address. The value returned from reloc_jmpslot() is the value
734 * that the trampoline needs.
736 target = reloc_jmpslot(where, target, defobj, obj, rel);
737 lock_release(rtld_bind_lock, &lockstate);
742 * Error reporting function. Use it like printf. If formats the message
743 * into a buffer, and sets things up so that the next call to dlerror()
744 * will return the message.
747 _rtld_error(const char *fmt, ...)
749 static char buf[512];
753 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
759 * Return a dynamically-allocated copy of the current error message, if any.
764 return error_message == NULL ? NULL : xstrdup(error_message);
768 * Restore the current error message from a copy which was previously saved
769 * by errmsg_save(). The copy is freed.
772 errmsg_restore(char *saved_msg)
774 if (saved_msg == NULL)
775 error_message = NULL;
777 _rtld_error("%s", saved_msg);
783 basename(const char *name)
785 const char *p = strrchr(name, '/');
786 return p != NULL ? p + 1 : name;
789 static struct utsname uts;
792 origin_subst_one(char *real, const char *kw, const char *subst,
795 char *p, *p1, *res, *resp;
796 int subst_len, kw_len, subst_count, old_len, new_len;
801 * First, count the number of the keyword occurences, to
802 * preallocate the final string.
804 for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
811 * If the keyword is not found, just return.
813 if (subst_count == 0)
814 return (may_free ? real : xstrdup(real));
817 * There is indeed something to substitute. Calculate the
818 * length of the resulting string, and allocate it.
820 subst_len = strlen(subst);
821 old_len = strlen(real);
822 new_len = old_len + (subst_len - kw_len) * subst_count;
823 res = xmalloc(new_len + 1);
826 * Now, execute the substitution loop.
828 for (p = real, resp = res, *resp = '\0';;) {
831 /* Copy the prefix before keyword. */
832 memcpy(resp, p, p1 - p);
834 /* Keyword replacement. */
835 memcpy(resp, subst, subst_len);
843 /* Copy to the end of string and finish. */
851 origin_subst(char *real, const char *origin_path)
853 char *res1, *res2, *res3, *res4;
855 if (uts.sysname[0] == '\0') {
856 if (uname(&uts) != 0) {
857 _rtld_error("utsname failed: %d", errno);
861 res1 = origin_subst_one(real, "$ORIGIN", origin_path, false);
862 res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true);
863 res3 = origin_subst_one(res2, "$OSREL", uts.release, true);
864 res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true);
871 const char *msg = dlerror();
875 rtld_fdputstr(STDERR_FILENO, msg);
876 rtld_fdputchar(STDERR_FILENO, '\n');
881 * Process a shared object's DYNAMIC section, and save the important
882 * information in its Obj_Entry structure.
885 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
886 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
889 Needed_Entry **needed_tail = &obj->needed;
890 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
891 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
892 const Elf_Hashelt *hashtab;
893 const Elf32_Word *hashval;
894 Elf32_Word bkt, nmaskwords;
896 int plttype = DT_REL;
902 obj->bind_now = false;
903 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
904 switch (dynp->d_tag) {
907 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
911 obj->relsize = dynp->d_un.d_val;
915 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
919 obj->pltrel = (const Elf_Rel *)
920 (obj->relocbase + dynp->d_un.d_ptr);
924 obj->pltrelsize = dynp->d_un.d_val;
928 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
932 obj->relasize = dynp->d_un.d_val;
936 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
940 plttype = dynp->d_un.d_val;
941 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
945 obj->symtab = (const Elf_Sym *)
946 (obj->relocbase + dynp->d_un.d_ptr);
950 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
954 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
958 obj->strsize = dynp->d_un.d_val;
962 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
967 obj->verneednum = dynp->d_un.d_val;
971 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
976 obj->verdefnum = dynp->d_un.d_val;
980 obj->versyms = (const Elf_Versym *)(obj->relocbase +
986 hashtab = (const Elf_Hashelt *)(obj->relocbase +
988 obj->nbuckets = hashtab[0];
989 obj->nchains = hashtab[1];
990 obj->buckets = hashtab + 2;
991 obj->chains = obj->buckets + obj->nbuckets;
992 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
993 obj->buckets != NULL;
999 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1001 obj->nbuckets_gnu = hashtab[0];
1002 obj->symndx_gnu = hashtab[1];
1003 nmaskwords = hashtab[2];
1004 bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1005 obj->maskwords_bm_gnu = nmaskwords - 1;
1006 obj->shift2_gnu = hashtab[3];
1007 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1008 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1009 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1011 /* Number of bitmask words is required to be power of 2 */
1012 obj->valid_hash_gnu = powerof2(nmaskwords) &&
1013 obj->nbuckets_gnu > 0 && obj->buckets_gnu != NULL;
1019 Needed_Entry *nep = NEW(Needed_Entry);
1020 nep->name = dynp->d_un.d_val;
1025 needed_tail = &nep->next;
1031 Needed_Entry *nep = NEW(Needed_Entry);
1032 nep->name = dynp->d_un.d_val;
1036 *needed_filtees_tail = nep;
1037 needed_filtees_tail = &nep->next;
1043 Needed_Entry *nep = NEW(Needed_Entry);
1044 nep->name = dynp->d_un.d_val;
1048 *needed_aux_filtees_tail = nep;
1049 needed_aux_filtees_tail = &nep->next;
1054 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1058 obj->textrel = true;
1062 obj->symbolic = true;
1067 * We have to wait until later to process this, because we
1068 * might not have gotten the address of the string table yet.
1078 *dyn_runpath = dynp;
1082 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1085 case DT_PREINIT_ARRAY:
1086 obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1089 case DT_PREINIT_ARRAYSZ:
1090 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1094 obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1097 case DT_INIT_ARRAYSZ:
1098 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1102 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1106 obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1109 case DT_FINI_ARRAYSZ:
1110 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1114 * Don't process DT_DEBUG on MIPS as the dynamic section
1115 * is mapped read-only. DT_MIPS_RLD_MAP is used instead.
1120 /* XXX - not implemented yet */
1122 dbg("Filling in DT_DEBUG entry");
1123 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1128 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1129 obj->z_origin = true;
1130 if (dynp->d_un.d_val & DF_SYMBOLIC)
1131 obj->symbolic = true;
1132 if (dynp->d_un.d_val & DF_TEXTREL)
1133 obj->textrel = true;
1134 if (dynp->d_un.d_val & DF_BIND_NOW)
1135 obj->bind_now = true;
1136 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1140 case DT_MIPS_LOCAL_GOTNO:
1141 obj->local_gotno = dynp->d_un.d_val;
1144 case DT_MIPS_SYMTABNO:
1145 obj->symtabno = dynp->d_un.d_val;
1148 case DT_MIPS_GOTSYM:
1149 obj->gotsym = dynp->d_un.d_val;
1152 case DT_MIPS_RLD_MAP:
1153 *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &r_debug;
1158 if (dynp->d_un.d_val & DF_1_NOOPEN)
1159 obj->z_noopen = true;
1160 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1161 obj->z_origin = true;
1162 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1164 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1165 obj->bind_now = true;
1166 if (dynp->d_un.d_val & DF_1_NODELETE)
1167 obj->z_nodelete = true;
1168 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1169 obj->z_loadfltr = true;
1170 if (dynp->d_un.d_val & DF_1_INTERPOSE)
1171 obj->z_interpose = true;
1172 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1173 obj->z_nodeflib = true;
1178 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1185 obj->traced = false;
1187 if (plttype == DT_RELA) {
1188 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1190 obj->pltrelasize = obj->pltrelsize;
1191 obj->pltrelsize = 0;
1194 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1195 if (obj->valid_hash_sysv)
1196 obj->dynsymcount = obj->nchains;
1197 else if (obj->valid_hash_gnu) {
1198 obj->dynsymcount = 0;
1199 for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1200 if (obj->buckets_gnu[bkt] == 0)
1202 hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1205 while ((*hashval++ & 1u) == 0);
1207 obj->dynsymcount += obj->symndx_gnu;
1212 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1213 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1216 if (obj->z_origin && obj->origin_path == NULL) {
1217 obj->origin_path = xmalloc(PATH_MAX);
1218 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1222 if (dyn_runpath != NULL) {
1223 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1225 obj->runpath = origin_subst(obj->runpath, obj->origin_path);
1227 else if (dyn_rpath != NULL) {
1228 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1230 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1233 if (dyn_soname != NULL)
1234 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1238 digest_dynamic(Obj_Entry *obj, int early)
1240 const Elf_Dyn *dyn_rpath;
1241 const Elf_Dyn *dyn_soname;
1242 const Elf_Dyn *dyn_runpath;
1244 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1245 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1249 * Process a shared object's program header. This is used only for the
1250 * main program, when the kernel has already loaded the main program
1251 * into memory before calling the dynamic linker. It creates and
1252 * returns an Obj_Entry structure.
1255 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1258 const Elf_Phdr *phlimit = phdr + phnum;
1260 Elf_Addr note_start, note_end;
1264 for (ph = phdr; ph < phlimit; ph++) {
1265 if (ph->p_type != PT_PHDR)
1269 obj->phsize = ph->p_memsz;
1270 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1274 obj->stack_flags = PF_X | PF_R | PF_W;
1276 for (ph = phdr; ph < phlimit; ph++) {
1277 switch (ph->p_type) {
1280 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1284 if (nsegs == 0) { /* First load segment */
1285 obj->vaddrbase = trunc_page(ph->p_vaddr);
1286 obj->mapbase = obj->vaddrbase + obj->relocbase;
1287 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1289 } else { /* Last load segment */
1290 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1297 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1302 obj->tlssize = ph->p_memsz;
1303 obj->tlsalign = ph->p_align;
1304 obj->tlsinitsize = ph->p_filesz;
1305 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1309 obj->stack_flags = ph->p_flags;
1313 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1314 obj->relro_size = round_page(ph->p_memsz);
1318 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1319 note_end = note_start + ph->p_filesz;
1320 digest_notes(obj, note_start, note_end);
1325 _rtld_error("%s: too few PT_LOAD segments", path);
1334 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1336 const Elf_Note *note;
1337 const char *note_name;
1340 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1341 note = (const Elf_Note *)((const char *)(note + 1) +
1342 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1343 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1344 if (note->n_namesz != sizeof(NOTE_FREEBSD_VENDOR) ||
1345 note->n_descsz != sizeof(int32_t))
1347 if (note->n_type != ABI_NOTETYPE &&
1348 note->n_type != CRT_NOINIT_NOTETYPE)
1350 note_name = (const char *)(note + 1);
1351 if (strncmp(NOTE_FREEBSD_VENDOR, note_name,
1352 sizeof(NOTE_FREEBSD_VENDOR)) != 0)
1354 switch (note->n_type) {
1356 /* FreeBSD osrel note */
1357 p = (uintptr_t)(note + 1);
1358 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1359 obj->osrel = *(const int32_t *)(p);
1360 dbg("note osrel %d", obj->osrel);
1362 case CRT_NOINIT_NOTETYPE:
1363 /* FreeBSD 'crt does not call init' note */
1364 obj->crt_no_init = true;
1365 dbg("note crt_no_init");
1372 dlcheck(void *handle)
1376 for (obj = obj_list; obj != NULL; obj = obj->next)
1377 if (obj == (Obj_Entry *) handle)
1380 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1381 _rtld_error("Invalid shared object handle %p", handle);
1388 * If the given object is already in the donelist, return true. Otherwise
1389 * add the object to the list and return false.
1392 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1396 for (i = 0; i < dlp->num_used; i++)
1397 if (dlp->objs[i] == obj)
1400 * Our donelist allocation should always be sufficient. But if
1401 * our threads locking isn't working properly, more shared objects
1402 * could have been loaded since we allocated the list. That should
1403 * never happen, but we'll handle it properly just in case it does.
1405 if (dlp->num_used < dlp->num_alloc)
1406 dlp->objs[dlp->num_used++] = obj;
1411 * Hash function for symbol table lookup. Don't even think about changing
1412 * this. It is specified by the System V ABI.
1415 elf_hash(const char *name)
1417 const unsigned char *p = (const unsigned char *) name;
1418 unsigned long h = 0;
1421 while (*p != '\0') {
1422 h = (h << 4) + *p++;
1423 if ((g = h & 0xf0000000) != 0)
1431 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1432 * unsigned in case it's implemented with a wider type.
1435 gnu_hash(const char *s)
1441 for (c = *s; c != '\0'; c = *++s)
1443 return (h & 0xffffffff);
1448 * Find the library with the given name, and return its full pathname.
1449 * The returned string is dynamically allocated. Generates an error
1450 * message and returns NULL if the library cannot be found.
1452 * If the second argument is non-NULL, then it refers to an already-
1453 * loaded shared object, whose library search path will be searched.
1455 * If a library is successfully located via LD_LIBRARY_PATH_FDS, its
1456 * descriptor (which is close-on-exec) will be passed out via the third
1459 * The search order is:
1460 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1461 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1463 * DT_RUNPATH in the referencing file
1464 * ldconfig hints (if -z nodefaultlib, filter out default library directories
1466 * /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1468 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1471 find_library(const char *xname, const Obj_Entry *refobj, int *fdp)
1475 bool nodeflib, objgiven;
1477 objgiven = refobj != NULL;
1478 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1479 if (xname[0] != '/' && !trust) {
1480 _rtld_error("Absolute pathname required for shared object \"%s\"",
1484 if (objgiven && refobj->z_origin) {
1485 return (origin_subst(__DECONST(char *, xname),
1486 refobj->origin_path));
1488 return (xstrdup(xname));
1492 if (libmap_disable || !objgiven ||
1493 (name = lm_find(refobj->path, xname)) == NULL)
1494 name = (char *)xname;
1496 dbg(" Searching for \"%s\"", name);
1499 * If refobj->rpath != NULL, then refobj->runpath is NULL. Fall
1500 * back to pre-conforming behaviour if user requested so with
1501 * LD_LIBRARY_PATH_RPATH environment variable and ignore -z
1504 if (objgiven && refobj->rpath != NULL && ld_library_path_rpath) {
1505 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
1507 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1508 (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
1509 (pathname = search_library_path(name, gethints(false))) != NULL ||
1510 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
1513 nodeflib = objgiven ? refobj->z_nodeflib : false;
1515 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1516 (objgiven && refobj->runpath == NULL && refobj != obj_main &&
1517 (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
1518 (pathname = search_library_path(name, ld_library_path)) != NULL ||
1520 (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
1521 (pathname = search_library_pathfds(name, ld_library_dirs, fdp)) != NULL ||
1522 (pathname = search_library_path(name, gethints(nodeflib))) != NULL ||
1523 (objgiven && !nodeflib &&
1524 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
1528 if (objgiven && refobj->path != NULL) {
1529 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1530 name, basename(refobj->path));
1532 _rtld_error("Shared object \"%s\" not found", name);
1538 * Given a symbol number in a referencing object, find the corresponding
1539 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1540 * no definition was found. Returns a pointer to the Obj_Entry of the
1541 * defining object via the reference parameter DEFOBJ_OUT.
1544 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1545 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1546 RtldLockState *lockstate)
1550 const Obj_Entry *defobj;
1556 * If we have already found this symbol, get the information from
1559 if (symnum >= refobj->dynsymcount)
1560 return NULL; /* Bad object */
1561 if (cache != NULL && cache[symnum].sym != NULL) {
1562 *defobj_out = cache[symnum].obj;
1563 return cache[symnum].sym;
1566 ref = refobj->symtab + symnum;
1567 name = refobj->strtab + ref->st_name;
1572 * We don't have to do a full scale lookup if the symbol is local.
1573 * We know it will bind to the instance in this load module; to
1574 * which we already have a pointer (ie ref). By not doing a lookup,
1575 * we not only improve performance, but it also avoids unresolvable
1576 * symbols when local symbols are not in the hash table. This has
1577 * been seen with the ia64 toolchain.
1579 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1580 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1581 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1584 symlook_init(&req, name);
1586 req.ventry = fetch_ventry(refobj, symnum);
1587 req.lockstate = lockstate;
1588 res = symlook_default(&req, refobj);
1591 defobj = req.defobj_out;
1599 * If we found no definition and the reference is weak, treat the
1600 * symbol as having the value zero.
1602 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1608 *defobj_out = defobj;
1609 /* Record the information in the cache to avoid subsequent lookups. */
1610 if (cache != NULL) {
1611 cache[symnum].sym = def;
1612 cache[symnum].obj = defobj;
1615 if (refobj != &obj_rtld)
1616 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1622 * Return the search path from the ldconfig hints file, reading it if
1623 * necessary. If nostdlib is true, then the default search paths are
1624 * not added to result.
1626 * Returns NULL if there are problems with the hints file,
1627 * or if the search path there is empty.
1630 gethints(bool nostdlib)
1632 static char *hints, *filtered_path;
1633 struct elfhints_hdr hdr;
1634 struct fill_search_info_args sargs, hargs;
1635 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1636 struct dl_serpath *SLPpath, *hintpath;
1638 unsigned int SLPndx, hintndx, fndx, fcount;
1643 /* First call, read the hints file */
1644 if (hints == NULL) {
1645 /* Keep from trying again in case the hints file is bad. */
1648 if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
1650 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1651 hdr.magic != ELFHINTS_MAGIC ||
1656 p = xmalloc(hdr.dirlistlen + 1);
1657 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1658 read(fd, p, hdr.dirlistlen + 1) !=
1659 (ssize_t)hdr.dirlistlen + 1) {
1669 * If caller agreed to receive list which includes the default
1670 * paths, we are done. Otherwise, if we still did not
1671 * calculated filtered result, do it now.
1674 return (hints[0] != '\0' ? hints : NULL);
1675 if (filtered_path != NULL)
1679 * Obtain the list of all configured search paths, and the
1680 * list of the default paths.
1682 * First estimate the size of the results.
1684 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1686 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1689 sargs.request = RTLD_DI_SERINFOSIZE;
1690 sargs.serinfo = &smeta;
1691 hargs.request = RTLD_DI_SERINFOSIZE;
1692 hargs.serinfo = &hmeta;
1694 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1695 path_enumerate(p, fill_search_info, &hargs);
1697 SLPinfo = xmalloc(smeta.dls_size);
1698 hintinfo = xmalloc(hmeta.dls_size);
1701 * Next fetch both sets of paths.
1703 sargs.request = RTLD_DI_SERINFO;
1704 sargs.serinfo = SLPinfo;
1705 sargs.serpath = &SLPinfo->dls_serpath[0];
1706 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1708 hargs.request = RTLD_DI_SERINFO;
1709 hargs.serinfo = hintinfo;
1710 hargs.serpath = &hintinfo->dls_serpath[0];
1711 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1713 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1714 path_enumerate(p, fill_search_info, &hargs);
1717 * Now calculate the difference between two sets, by excluding
1718 * standard paths from the full set.
1722 filtered_path = xmalloc(hdr.dirlistlen + 1);
1723 hintpath = &hintinfo->dls_serpath[0];
1724 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
1726 SLPpath = &SLPinfo->dls_serpath[0];
1728 * Check each standard path against current.
1730 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
1731 /* matched, skip the path */
1732 if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
1740 * Not matched against any standard path, add the path
1741 * to result. Separate consequtive paths with ':'.
1744 filtered_path[fndx] = ':';
1748 flen = strlen(hintpath->dls_name);
1749 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1752 filtered_path[fndx] = '\0';
1758 return (filtered_path[0] != '\0' ? filtered_path : NULL);
1762 init_dag(Obj_Entry *root)
1764 const Needed_Entry *needed;
1765 const Objlist_Entry *elm;
1768 if (root->dag_inited)
1770 donelist_init(&donelist);
1772 /* Root object belongs to own DAG. */
1773 objlist_push_tail(&root->dldags, root);
1774 objlist_push_tail(&root->dagmembers, root);
1775 donelist_check(&donelist, root);
1778 * Add dependencies of root object to DAG in breadth order
1779 * by exploiting the fact that each new object get added
1780 * to the tail of the dagmembers list.
1782 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1783 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1784 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1786 objlist_push_tail(&needed->obj->dldags, root);
1787 objlist_push_tail(&root->dagmembers, needed->obj);
1790 root->dag_inited = true;
1794 process_nodelete(Obj_Entry *root)
1796 const Objlist_Entry *elm;
1799 * Walk over object DAG and process every dependent object that
1800 * is marked as DF_1_NODELETE. They need to grow their own DAG,
1801 * which then should have its reference upped separately.
1803 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1804 if (elm->obj != NULL && elm->obj->z_nodelete &&
1805 !elm->obj->ref_nodel) {
1806 dbg("obj %s nodelete", elm->obj->path);
1809 elm->obj->ref_nodel = true;
1814 * Initialize the dynamic linker. The argument is the address at which
1815 * the dynamic linker has been mapped into memory. The primary task of
1816 * this function is to relocate the dynamic linker.
1819 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1821 Obj_Entry objtmp; /* Temporary rtld object */
1822 const Elf_Dyn *dyn_rpath;
1823 const Elf_Dyn *dyn_soname;
1824 const Elf_Dyn *dyn_runpath;
1826 #ifdef RTLD_INIT_PAGESIZES_EARLY
1827 /* The page size is required by the dynamic memory allocator. */
1828 init_pagesizes(aux_info);
1832 * Conjure up an Obj_Entry structure for the dynamic linker.
1834 * The "path" member can't be initialized yet because string constants
1835 * cannot yet be accessed. Below we will set it correctly.
1837 memset(&objtmp, 0, sizeof(objtmp));
1840 objtmp.mapbase = mapbase;
1842 objtmp.relocbase = mapbase;
1844 if (RTLD_IS_DYNAMIC()) {
1845 objtmp.dynamic = rtld_dynamic(&objtmp);
1846 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
1847 assert(objtmp.needed == NULL);
1848 #if !defined(__mips__)
1849 /* MIPS has a bogus DT_TEXTREL. */
1850 assert(!objtmp.textrel);
1854 * Temporarily put the dynamic linker entry into the object list, so
1855 * that symbols can be found.
1858 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
1861 /* Initialize the object list. */
1862 obj_tail = &obj_list;
1864 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1865 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1867 #ifndef RTLD_INIT_PAGESIZES_EARLY
1868 /* The page size is required by the dynamic memory allocator. */
1869 init_pagesizes(aux_info);
1872 if (aux_info[AT_OSRELDATE] != NULL)
1873 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1875 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
1877 /* Replace the path with a dynamically allocated copy. */
1878 obj_rtld.path = xstrdup(PATH_RTLD);
1880 r_debug.r_brk = r_debug_state;
1881 r_debug.r_state = RT_CONSISTENT;
1885 * Retrieve the array of supported page sizes. The kernel provides the page
1886 * sizes in increasing order.
1889 init_pagesizes(Elf_Auxinfo **aux_info)
1891 static size_t psa[MAXPAGESIZES];
1895 if (aux_info[AT_PAGESIZES] != NULL && aux_info[AT_PAGESIZESLEN] !=
1897 size = aux_info[AT_PAGESIZESLEN]->a_un.a_val;
1898 pagesizes = aux_info[AT_PAGESIZES]->a_un.a_ptr;
1901 if (sysctlnametomib("hw.pagesizes", mib, &len) == 0)
1904 /* As a fallback, retrieve the base page size. */
1905 size = sizeof(psa[0]);
1906 if (aux_info[AT_PAGESZ] != NULL) {
1907 psa[0] = aux_info[AT_PAGESZ]->a_un.a_val;
1911 mib[1] = HW_PAGESIZE;
1915 if (sysctl(mib, len, psa, &size, NULL, 0) == -1) {
1916 _rtld_error("sysctl for hw.pagesize(s) failed");
1922 npagesizes = size / sizeof(pagesizes[0]);
1923 /* Discard any invalid entries at the end of the array. */
1924 while (npagesizes > 0 && pagesizes[npagesizes - 1] == 0)
1929 * Add the init functions from a needed object list (and its recursive
1930 * needed objects) to "list". This is not used directly; it is a helper
1931 * function for initlist_add_objects(). The write lock must be held
1932 * when this function is called.
1935 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1937 /* Recursively process the successor needed objects. */
1938 if (needed->next != NULL)
1939 initlist_add_neededs(needed->next, list);
1941 /* Process the current needed object. */
1942 if (needed->obj != NULL)
1943 initlist_add_objects(needed->obj, &needed->obj->next, list);
1947 * Scan all of the DAGs rooted in the range of objects from "obj" to
1948 * "tail" and add their init functions to "list". This recurses over
1949 * the DAGs and ensure the proper init ordering such that each object's
1950 * needed libraries are initialized before the object itself. At the
1951 * same time, this function adds the objects to the global finalization
1952 * list "list_fini" in the opposite order. The write lock must be
1953 * held when this function is called.
1956 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1959 if (obj->init_scanned || obj->init_done)
1961 obj->init_scanned = true;
1963 /* Recursively process the successor objects. */
1964 if (&obj->next != tail)
1965 initlist_add_objects(obj->next, tail, list);
1967 /* Recursively process the needed objects. */
1968 if (obj->needed != NULL)
1969 initlist_add_neededs(obj->needed, list);
1970 if (obj->needed_filtees != NULL)
1971 initlist_add_neededs(obj->needed_filtees, list);
1972 if (obj->needed_aux_filtees != NULL)
1973 initlist_add_neededs(obj->needed_aux_filtees, list);
1975 /* Add the object to the init list. */
1976 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
1977 obj->init_array != (Elf_Addr)NULL)
1978 objlist_push_tail(list, obj);
1980 /* Add the object to the global fini list in the reverse order. */
1981 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1982 && !obj->on_fini_list) {
1983 objlist_push_head(&list_fini, obj);
1984 obj->on_fini_list = true;
1989 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1993 free_needed_filtees(Needed_Entry *n)
1995 Needed_Entry *needed, *needed1;
1997 for (needed = n; needed != NULL; needed = needed->next) {
1998 if (needed->obj != NULL) {
1999 dlclose(needed->obj);
2003 for (needed = n; needed != NULL; needed = needed1) {
2004 needed1 = needed->next;
2010 unload_filtees(Obj_Entry *obj)
2013 free_needed_filtees(obj->needed_filtees);
2014 obj->needed_filtees = NULL;
2015 free_needed_filtees(obj->needed_aux_filtees);
2016 obj->needed_aux_filtees = NULL;
2017 obj->filtees_loaded = false;
2021 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
2022 RtldLockState *lockstate)
2025 for (; needed != NULL; needed = needed->next) {
2026 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
2027 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
2028 RTLD_LOCAL, lockstate);
2033 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
2036 lock_restart_for_upgrade(lockstate);
2037 if (!obj->filtees_loaded) {
2038 load_filtee1(obj, obj->needed_filtees, flags, lockstate);
2039 load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
2040 obj->filtees_loaded = true;
2045 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
2049 for (; needed != NULL; needed = needed->next) {
2050 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
2051 flags & ~RTLD_LO_NOLOAD);
2052 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
2059 * Given a shared object, traverse its list of needed objects, and load
2060 * each of them. Returns 0 on success. Generates an error message and
2061 * returns -1 on failure.
2064 load_needed_objects(Obj_Entry *first, int flags)
2068 for (obj = first; obj != NULL; obj = obj->next) {
2069 if (process_needed(obj, obj->needed, flags) == -1)
2076 load_preload_objects(void)
2078 char *p = ld_preload;
2080 static const char delim[] = " \t:;";
2085 p += strspn(p, delim);
2086 while (*p != '\0') {
2087 size_t len = strcspn(p, delim);
2092 obj = load_object(p, -1, NULL, 0);
2094 return -1; /* XXX - cleanup */
2095 obj->z_interpose = true;
2098 p += strspn(p, delim);
2100 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2105 printable_path(const char *path)
2108 return (path == NULL ? "<unknown>" : path);
2112 * Load a shared object into memory, if it is not already loaded. The
2113 * object may be specified by name or by user-supplied file descriptor
2114 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2117 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2121 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2130 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
2131 if (object_match_name(obj, name))
2135 path = find_library(name, refobj, &fd);
2143 * search_library_pathfds() opens a fresh file descriptor for the
2144 * library, so there is no need to dup().
2146 } else if (fd_u == -1) {
2148 * If we didn't find a match by pathname, or the name is not
2149 * supplied, open the file and check again by device and inode.
2150 * This avoids false mismatches caused by multiple links or ".."
2153 * To avoid a race, we open the file and use fstat() rather than
2156 if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
2157 _rtld_error("Cannot open \"%s\"", path);
2162 fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
2164 _rtld_error("Cannot dup fd");
2169 if (fstat(fd, &sb) == -1) {
2170 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2175 for (obj = obj_list->next; obj != NULL; obj = obj->next)
2176 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2178 if (obj != NULL && name != NULL) {
2179 object_add_name(obj, name);
2184 if (flags & RTLD_LO_NOLOAD) {
2190 /* First use of this object, so we must map it in */
2191 obj = do_load_object(fd, name, path, &sb, flags);
2200 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2207 * but first, make sure that environment variables haven't been
2208 * used to circumvent the noexec flag on a filesystem.
2210 if (dangerous_ld_env) {
2211 if (fstatfs(fd, &fs) != 0) {
2212 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2215 if (fs.f_flags & MNT_NOEXEC) {
2216 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
2220 dbg("loading \"%s\"", printable_path(path));
2221 obj = map_object(fd, printable_path(path), sbp);
2226 * If DT_SONAME is present in the object, digest_dynamic2 already
2227 * added it to the object names.
2230 object_add_name(obj, name);
2232 digest_dynamic(obj, 0);
2233 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
2234 obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
2235 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2237 dbg("refusing to load non-loadable \"%s\"", obj->path);
2238 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2239 munmap(obj->mapbase, obj->mapsize);
2244 obj->dlopened = (flags & RTLD_LO_DLOPEN) != 0;
2246 obj_tail = &obj->next;
2249 linkmap_add(obj); /* for GDB & dlinfo() */
2250 max_stack_flags |= obj->stack_flags;
2252 dbg(" %p .. %p: %s", obj->mapbase,
2253 obj->mapbase + obj->mapsize - 1, obj->path);
2255 dbg(" WARNING: %s has impure text", obj->path);
2256 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2263 obj_from_addr(const void *addr)
2267 for (obj = obj_list; obj != NULL; obj = obj->next) {
2268 if (addr < (void *) obj->mapbase)
2270 if (addr < (void *) (obj->mapbase + obj->mapsize))
2279 Elf_Addr *preinit_addr;
2282 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2283 if (preinit_addr == NULL)
2286 for (index = 0; index < obj_main->preinit_array_num; index++) {
2287 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2288 dbg("calling preinit function for %s at %p", obj_main->path,
2289 (void *)preinit_addr[index]);
2290 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2291 0, 0, obj_main->path);
2292 call_init_pointer(obj_main, preinit_addr[index]);
2298 * Call the finalization functions for each of the objects in "list"
2299 * belonging to the DAG of "root" and referenced once. If NULL "root"
2300 * is specified, every finalization function will be called regardless
2301 * of the reference count and the list elements won't be freed. All of
2302 * the objects are expected to have non-NULL fini functions.
2305 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2309 Elf_Addr *fini_addr;
2312 assert(root == NULL || root->refcount == 1);
2315 * Preserve the current error message since a fini function might
2316 * call into the dynamic linker and overwrite it.
2318 saved_msg = errmsg_save();
2320 STAILQ_FOREACH(elm, list, link) {
2321 if (root != NULL && (elm->obj->refcount != 1 ||
2322 objlist_find(&root->dagmembers, elm->obj) == NULL))
2324 /* Remove object from fini list to prevent recursive invocation. */
2325 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2327 * XXX: If a dlopen() call references an object while the
2328 * fini function is in progress, we might end up trying to
2329 * unload the referenced object in dlclose() or the object
2330 * won't be unloaded although its fini function has been
2333 lock_release(rtld_bind_lock, lockstate);
2336 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
2337 * When this happens, DT_FINI_ARRAY is processed first.
2339 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2340 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2341 for (index = elm->obj->fini_array_num - 1; index >= 0;
2343 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2344 dbg("calling fini function for %s at %p",
2345 elm->obj->path, (void *)fini_addr[index]);
2346 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2347 (void *)fini_addr[index], 0, 0, elm->obj->path);
2348 call_initfini_pointer(elm->obj, fini_addr[index]);
2352 if (elm->obj->fini != (Elf_Addr)NULL) {
2353 dbg("calling fini function for %s at %p", elm->obj->path,
2354 (void *)elm->obj->fini);
2355 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2356 0, 0, elm->obj->path);
2357 call_initfini_pointer(elm->obj, elm->obj->fini);
2359 wlock_acquire(rtld_bind_lock, lockstate);
2360 /* No need to free anything if process is going down. */
2364 * We must restart the list traversal after every fini call
2365 * because a dlclose() call from the fini function or from
2366 * another thread might have modified the reference counts.
2370 } while (elm != NULL);
2371 errmsg_restore(saved_msg);
2375 * Call the initialization functions for each of the objects in
2376 * "list". All of the objects are expected to have non-NULL init
2380 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2385 Elf_Addr *init_addr;
2389 * Clean init_scanned flag so that objects can be rechecked and
2390 * possibly initialized earlier if any of vectors called below
2391 * cause the change by using dlopen.
2393 for (obj = obj_list; obj != NULL; obj = obj->next)
2394 obj->init_scanned = false;
2397 * Preserve the current error message since an init function might
2398 * call into the dynamic linker and overwrite it.
2400 saved_msg = errmsg_save();
2401 STAILQ_FOREACH(elm, list, link) {
2402 if (elm->obj->init_done) /* Initialized early. */
2405 * Race: other thread might try to use this object before current
2406 * one completes the initilization. Not much can be done here
2407 * without better locking.
2409 elm->obj->init_done = true;
2410 lock_release(rtld_bind_lock, lockstate);
2413 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
2414 * When this happens, DT_INIT is processed first.
2416 if (elm->obj->init != (Elf_Addr)NULL) {
2417 dbg("calling init function for %s at %p", elm->obj->path,
2418 (void *)elm->obj->init);
2419 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2420 0, 0, elm->obj->path);
2421 call_initfini_pointer(elm->obj, elm->obj->init);
2423 init_addr = (Elf_Addr *)elm->obj->init_array;
2424 if (init_addr != NULL) {
2425 for (index = 0; index < elm->obj->init_array_num; index++) {
2426 if (init_addr[index] != 0 && init_addr[index] != 1) {
2427 dbg("calling init function for %s at %p", elm->obj->path,
2428 (void *)init_addr[index]);
2429 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2430 (void *)init_addr[index], 0, 0, elm->obj->path);
2431 call_init_pointer(elm->obj, init_addr[index]);
2435 wlock_acquire(rtld_bind_lock, lockstate);
2437 errmsg_restore(saved_msg);
2441 objlist_clear(Objlist *list)
2445 while (!STAILQ_EMPTY(list)) {
2446 elm = STAILQ_FIRST(list);
2447 STAILQ_REMOVE_HEAD(list, link);
2452 static Objlist_Entry *
2453 objlist_find(Objlist *list, const Obj_Entry *obj)
2457 STAILQ_FOREACH(elm, list, link)
2458 if (elm->obj == obj)
2464 objlist_init(Objlist *list)
2470 objlist_push_head(Objlist *list, Obj_Entry *obj)
2474 elm = NEW(Objlist_Entry);
2476 STAILQ_INSERT_HEAD(list, elm, link);
2480 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2484 elm = NEW(Objlist_Entry);
2486 STAILQ_INSERT_TAIL(list, elm, link);
2490 objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
2492 Objlist_Entry *elm, *listelm;
2494 STAILQ_FOREACH(listelm, list, link) {
2495 if (listelm->obj == listobj)
2498 elm = NEW(Objlist_Entry);
2500 if (listelm != NULL)
2501 STAILQ_INSERT_AFTER(list, listelm, elm, link);
2503 STAILQ_INSERT_TAIL(list, elm, link);
2507 objlist_remove(Objlist *list, Obj_Entry *obj)
2511 if ((elm = objlist_find(list, obj)) != NULL) {
2512 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2518 * Relocate dag rooted in the specified object.
2519 * Returns 0 on success, or -1 on failure.
2523 relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
2524 int flags, RtldLockState *lockstate)
2530 STAILQ_FOREACH(elm, &root->dagmembers, link) {
2531 error = relocate_object(elm->obj, bind_now, rtldobj, flags,
2540 * Relocate single object.
2541 * Returns 0 on success, or -1 on failure.
2544 relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
2545 int flags, RtldLockState *lockstate)
2550 obj->relocated = true;
2552 dbg("relocating \"%s\"", obj->path);
2554 if (obj->symtab == NULL || obj->strtab == NULL ||
2555 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2556 _rtld_error("%s: Shared object has no run-time symbol table",
2562 /* There are relocations to the write-protected text segment. */
2563 if (mprotect(obj->mapbase, obj->textsize,
2564 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2565 _rtld_error("%s: Cannot write-enable text segment: %s",
2566 obj->path, rtld_strerror(errno));
2571 /* Process the non-PLT non-IFUNC relocations. */
2572 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2575 if (obj->textrel) { /* Re-protected the text segment. */
2576 if (mprotect(obj->mapbase, obj->textsize,
2577 PROT_READ|PROT_EXEC) == -1) {
2578 _rtld_error("%s: Cannot write-protect text segment: %s",
2579 obj->path, rtld_strerror(errno));
2584 /* Set the special PLT or GOT entries. */
2587 /* Process the PLT relocations. */
2588 if (reloc_plt(obj) == -1)
2590 /* Relocate the jump slots if we are doing immediate binding. */
2591 if (obj->bind_now || bind_now)
2592 if (reloc_jmpslots(obj, flags, lockstate) == -1)
2596 * Process the non-PLT IFUNC relocations. The relocations are
2597 * processed in two phases, because IFUNC resolvers may
2598 * reference other symbols, which must be readily processed
2599 * before resolvers are called.
2601 if (obj->non_plt_gnu_ifunc &&
2602 reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate))
2605 if (obj->relro_size > 0) {
2606 if (mprotect(obj->relro_page, obj->relro_size,
2608 _rtld_error("%s: Cannot enforce relro protection: %s",
2609 obj->path, rtld_strerror(errno));
2615 * Set up the magic number and version in the Obj_Entry. These
2616 * were checked in the crt1.o from the original ElfKit, so we
2617 * set them for backward compatibility.
2619 obj->magic = RTLD_MAGIC;
2620 obj->version = RTLD_VERSION;
2626 * Relocate newly-loaded shared objects. The argument is a pointer to
2627 * the Obj_Entry for the first such object. All objects from the first
2628 * to the end of the list of objects are relocated. Returns 0 on success,
2632 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2633 int flags, RtldLockState *lockstate)
2638 for (error = 0, obj = first; obj != NULL; obj = obj->next) {
2639 error = relocate_object(obj, bind_now, rtldobj, flags,
2648 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2649 * referencing STT_GNU_IFUNC symbols is postponed till the other
2650 * relocations are done. The indirect functions specified as
2651 * ifunc are allowed to call other symbols, so we need to have
2652 * objects relocated before asking for resolution from indirects.
2654 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2655 * instead of the usual lazy handling of PLT slots. It is
2656 * consistent with how GNU does it.
2659 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2660 RtldLockState *lockstate)
2662 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2664 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2665 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2671 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2672 RtldLockState *lockstate)
2676 for (obj = first; obj != NULL; obj = obj->next) {
2677 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2684 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2685 RtldLockState *lockstate)
2689 STAILQ_FOREACH(elm, list, link) {
2690 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2698 * Cleanup procedure. It will be called (by the atexit mechanism) just
2699 * before the process exits.
2704 RtldLockState lockstate;
2706 wlock_acquire(rtld_bind_lock, &lockstate);
2708 objlist_call_fini(&list_fini, NULL, &lockstate);
2709 /* No need to remove the items from the list, since we are exiting. */
2710 if (!libmap_disable)
2712 lock_release(rtld_bind_lock, &lockstate);
2716 * Iterate over a search path, translate each element, and invoke the
2717 * callback on the result.
2720 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2726 path += strspn(path, ":;");
2727 while (*path != '\0') {
2731 len = strcspn(path, ":;");
2732 trans = lm_findn(NULL, path, len);
2734 res = callback(trans, strlen(trans), arg);
2736 res = callback(path, len, arg);
2742 path += strspn(path, ":;");
2748 struct try_library_args {
2756 try_library_path(const char *dir, size_t dirlen, void *param)
2758 struct try_library_args *arg;
2761 if (*dir == '/' || trust) {
2764 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2767 pathname = arg->buffer;
2768 strncpy(pathname, dir, dirlen);
2769 pathname[dirlen] = '/';
2770 strcpy(pathname + dirlen + 1, arg->name);
2772 dbg(" Trying \"%s\"", pathname);
2773 if (access(pathname, F_OK) == 0) { /* We found it */
2774 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2775 strcpy(pathname, arg->buffer);
2783 search_library_path(const char *name, const char *path)
2786 struct try_library_args arg;
2792 arg.namelen = strlen(name);
2793 arg.buffer = xmalloc(PATH_MAX);
2794 arg.buflen = PATH_MAX;
2796 p = path_enumerate(path, try_library_path, &arg);
2805 * Finds the library with the given name using the directory descriptors
2806 * listed in the LD_LIBRARY_PATH_FDS environment variable.
2808 * Returns a freshly-opened close-on-exec file descriptor for the library,
2809 * or -1 if the library cannot be found.
2812 search_library_pathfds(const char *name, const char *path, int *fdp)
2814 char *envcopy, *fdstr, *found, *last_token;
2818 dbg("%s('%s', '%s', fdp)", __func__, name, path);
2820 /* Don't load from user-specified libdirs into setuid binaries. */
2824 /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */
2828 /* LD_LIBRARY_PATH_FDS only works with relative paths. */
2829 if (name[0] == '/') {
2830 dbg("Absolute path (%s) passed to %s", name, __func__);
2835 * Use strtok_r() to walk the FD:FD:FD list. This requires a local
2836 * copy of the path, as strtok_r rewrites separator tokens
2840 envcopy = xstrdup(path);
2841 for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL;
2842 fdstr = strtok_r(NULL, ":", &last_token)) {
2843 dirfd = parse_libdir(fdstr);
2846 fd = __sys_openat(dirfd, name, O_RDONLY | O_CLOEXEC);
2849 len = strlen(fdstr) + strlen(name) + 3;
2850 found = xmalloc(len);
2851 if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) {
2852 _rtld_error("error generating '%d/%s'",
2856 dbg("open('%s') => %d", found, fd);
2867 dlclose(void *handle)
2870 RtldLockState lockstate;
2872 wlock_acquire(rtld_bind_lock, &lockstate);
2873 root = dlcheck(handle);
2875 lock_release(rtld_bind_lock, &lockstate);
2878 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2881 /* Unreference the object and its dependencies. */
2882 root->dl_refcount--;
2884 if (root->refcount == 1) {
2886 * The object will be no longer referenced, so we must unload it.
2887 * First, call the fini functions.
2889 objlist_call_fini(&list_fini, root, &lockstate);
2893 /* Finish cleaning up the newly-unreferenced objects. */
2894 GDB_STATE(RT_DELETE,&root->linkmap);
2895 unload_object(root);
2896 GDB_STATE(RT_CONSISTENT,NULL);
2900 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2901 lock_release(rtld_bind_lock, &lockstate);
2908 char *msg = error_message;
2909 error_message = NULL;
2914 * This function is deprecated and has no effect.
2917 dllockinit(void *context,
2918 void *(*lock_create)(void *context),
2919 void (*rlock_acquire)(void *lock),
2920 void (*wlock_acquire)(void *lock),
2921 void (*lock_release)(void *lock),
2922 void (*lock_destroy)(void *lock),
2923 void (*context_destroy)(void *context))
2925 static void *cur_context;
2926 static void (*cur_context_destroy)(void *);
2928 /* Just destroy the context from the previous call, if necessary. */
2929 if (cur_context_destroy != NULL)
2930 cur_context_destroy(cur_context);
2931 cur_context = context;
2932 cur_context_destroy = context_destroy;
2936 dlopen(const char *name, int mode)
2939 return (rtld_dlopen(name, -1, mode));
2943 fdlopen(int fd, int mode)
2946 return (rtld_dlopen(NULL, fd, mode));
2950 rtld_dlopen(const char *name, int fd, int mode)
2952 RtldLockState lockstate;
2955 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2956 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2957 if (ld_tracing != NULL) {
2958 rlock_acquire(rtld_bind_lock, &lockstate);
2959 if (sigsetjmp(lockstate.env, 0) != 0)
2960 lock_upgrade(rtld_bind_lock, &lockstate);
2961 environ = (char **)*get_program_var_addr("environ", &lockstate);
2962 lock_release(rtld_bind_lock, &lockstate);
2964 lo_flags = RTLD_LO_DLOPEN;
2965 if (mode & RTLD_NODELETE)
2966 lo_flags |= RTLD_LO_NODELETE;
2967 if (mode & RTLD_NOLOAD)
2968 lo_flags |= RTLD_LO_NOLOAD;
2969 if (ld_tracing != NULL)
2970 lo_flags |= RTLD_LO_TRACE;
2972 return (dlopen_object(name, fd, obj_main, lo_flags,
2973 mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
2977 dlopen_cleanup(Obj_Entry *obj)
2982 if (obj->refcount == 0)
2987 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
2988 int mode, RtldLockState *lockstate)
2990 Obj_Entry **old_obj_tail;
2993 RtldLockState mlockstate;
2996 objlist_init(&initlist);
2998 if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
2999 wlock_acquire(rtld_bind_lock, &mlockstate);
3000 lockstate = &mlockstate;
3002 GDB_STATE(RT_ADD,NULL);
3004 old_obj_tail = obj_tail;
3006 if (name == NULL && fd == -1) {
3010 obj = load_object(name, fd, refobj, lo_flags);
3015 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
3016 objlist_push_tail(&list_global, obj);
3017 if (*old_obj_tail != NULL) { /* We loaded something new. */
3018 assert(*old_obj_tail == obj);
3019 result = load_needed_objects(obj,
3020 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
3024 result = rtld_verify_versions(&obj->dagmembers);
3025 if (result != -1 && ld_tracing)
3027 if (result == -1 || relocate_object_dag(obj,
3028 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
3029 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3031 dlopen_cleanup(obj);
3033 } else if (lo_flags & RTLD_LO_EARLY) {
3035 * Do not call the init functions for early loaded
3036 * filtees. The image is still not initialized enough
3039 * Our object is found by the global object list and
3040 * will be ordered among all init calls done right
3041 * before transferring control to main.
3044 /* Make list of init functions to call. */
3045 initlist_add_objects(obj, &obj->next, &initlist);
3048 * Process all no_delete objects here, given them own
3049 * DAGs to prevent their dependencies from being unloaded.
3050 * This has to be done after we have loaded all of the
3051 * dependencies, so that we do not miss any.
3054 process_nodelete(obj);
3057 * Bump the reference counts for objects on this DAG. If
3058 * this is the first dlopen() call for the object that was
3059 * already loaded as a dependency, initialize the dag
3065 if ((lo_flags & RTLD_LO_TRACE) != 0)
3068 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
3069 obj->z_nodelete) && !obj->ref_nodel) {
3070 dbg("obj %s nodelete", obj->path);
3072 obj->z_nodelete = obj->ref_nodel = true;
3076 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
3078 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
3080 if (!(lo_flags & RTLD_LO_EARLY)) {
3081 map_stacks_exec(lockstate);
3084 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
3085 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3087 objlist_clear(&initlist);
3088 dlopen_cleanup(obj);
3089 if (lockstate == &mlockstate)
3090 lock_release(rtld_bind_lock, lockstate);
3094 if (!(lo_flags & RTLD_LO_EARLY)) {
3095 /* Call the init functions. */
3096 objlist_call_init(&initlist, lockstate);
3098 objlist_clear(&initlist);
3099 if (lockstate == &mlockstate)
3100 lock_release(rtld_bind_lock, lockstate);
3103 trace_loaded_objects(obj);
3104 if (lockstate == &mlockstate)
3105 lock_release(rtld_bind_lock, lockstate);
3110 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
3114 const Obj_Entry *obj, *defobj;
3117 RtldLockState lockstate;
3124 symlook_init(&req, name);
3126 req.flags = flags | SYMLOOK_IN_PLT;
3127 req.lockstate = &lockstate;
3129 LD_UTRACE(UTRACE_DLSYM_START, handle, NULL, 0, 0, name);
3130 rlock_acquire(rtld_bind_lock, &lockstate);
3131 if (sigsetjmp(lockstate.env, 0) != 0)
3132 lock_upgrade(rtld_bind_lock, &lockstate);
3133 if (handle == NULL || handle == RTLD_NEXT ||
3134 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
3136 if ((obj = obj_from_addr(retaddr)) == NULL) {
3137 _rtld_error("Cannot determine caller's shared object");
3138 lock_release(rtld_bind_lock, &lockstate);
3139 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3142 if (handle == NULL) { /* Just the caller's shared object. */
3143 res = symlook_obj(&req, obj);
3146 defobj = req.defobj_out;
3148 } else if (handle == RTLD_NEXT || /* Objects after caller's */
3149 handle == RTLD_SELF) { /* ... caller included */
3150 if (handle == RTLD_NEXT)
3152 for (; obj != NULL; obj = obj->next) {
3153 res = symlook_obj(&req, obj);
3156 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
3158 defobj = req.defobj_out;
3159 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3165 * Search the dynamic linker itself, and possibly resolve the
3166 * symbol from there. This is how the application links to
3167 * dynamic linker services such as dlopen.
3169 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3170 res = symlook_obj(&req, &obj_rtld);
3173 defobj = req.defobj_out;
3177 assert(handle == RTLD_DEFAULT);
3178 res = symlook_default(&req, obj);
3180 defobj = req.defobj_out;
3185 if ((obj = dlcheck(handle)) == NULL) {
3186 lock_release(rtld_bind_lock, &lockstate);
3187 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3191 donelist_init(&donelist);
3192 if (obj->mainprog) {
3193 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
3194 res = symlook_global(&req, &donelist);
3197 defobj = req.defobj_out;
3200 * Search the dynamic linker itself, and possibly resolve the
3201 * symbol from there. This is how the application links to
3202 * dynamic linker services such as dlopen.
3204 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3205 res = symlook_obj(&req, &obj_rtld);
3208 defobj = req.defobj_out;
3213 /* Search the whole DAG rooted at the given object. */
3214 res = symlook_list(&req, &obj->dagmembers, &donelist);
3217 defobj = req.defobj_out;
3223 lock_release(rtld_bind_lock, &lockstate);
3226 * The value required by the caller is derived from the value
3227 * of the symbol. this is simply the relocated value of the
3230 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3231 sym = make_function_pointer(def, defobj);
3232 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3233 sym = rtld_resolve_ifunc(defobj, def);
3234 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3235 ti.ti_module = defobj->tlsindex;
3236 ti.ti_offset = def->st_value;
3237 sym = __tls_get_addr(&ti);
3239 sym = defobj->relocbase + def->st_value;
3240 LD_UTRACE(UTRACE_DLSYM_STOP, handle, sym, 0, 0, name);
3244 _rtld_error("Undefined symbol \"%s\"", name);
3245 lock_release(rtld_bind_lock, &lockstate);
3246 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3251 dlsym(void *handle, const char *name)
3253 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3258 dlfunc(void *handle, const char *name)
3265 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3271 dlvsym(void *handle, const char *name, const char *version)
3275 ventry.name = version;
3277 ventry.hash = elf_hash(version);
3279 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3284 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3286 const Obj_Entry *obj;
3287 RtldLockState lockstate;
3289 rlock_acquire(rtld_bind_lock, &lockstate);
3290 obj = obj_from_addr(addr);
3292 _rtld_error("No shared object contains address");
3293 lock_release(rtld_bind_lock, &lockstate);
3296 rtld_fill_dl_phdr_info(obj, phdr_info);
3297 lock_release(rtld_bind_lock, &lockstate);
3302 dladdr(const void *addr, Dl_info *info)
3304 const Obj_Entry *obj;
3307 unsigned long symoffset;
3308 RtldLockState lockstate;
3310 rlock_acquire(rtld_bind_lock, &lockstate);
3311 obj = obj_from_addr(addr);
3313 _rtld_error("No shared object contains address");
3314 lock_release(rtld_bind_lock, &lockstate);
3317 info->dli_fname = obj->path;
3318 info->dli_fbase = obj->mapbase;
3319 info->dli_saddr = (void *)0;
3320 info->dli_sname = NULL;
3323 * Walk the symbol list looking for the symbol whose address is
3324 * closest to the address sent in.
3326 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3327 def = obj->symtab + symoffset;
3330 * For skip the symbol if st_shndx is either SHN_UNDEF or
3333 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3337 * If the symbol is greater than the specified address, or if it
3338 * is further away from addr than the current nearest symbol,
3341 symbol_addr = obj->relocbase + def->st_value;
3342 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3345 /* Update our idea of the nearest symbol. */
3346 info->dli_sname = obj->strtab + def->st_name;
3347 info->dli_saddr = symbol_addr;
3350 if (info->dli_saddr == addr)
3353 lock_release(rtld_bind_lock, &lockstate);
3358 dlinfo(void *handle, int request, void *p)
3360 const Obj_Entry *obj;
3361 RtldLockState lockstate;
3364 rlock_acquire(rtld_bind_lock, &lockstate);
3366 if (handle == NULL || handle == RTLD_SELF) {
3369 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3370 if ((obj = obj_from_addr(retaddr)) == NULL)
3371 _rtld_error("Cannot determine caller's shared object");
3373 obj = dlcheck(handle);
3376 lock_release(rtld_bind_lock, &lockstate);
3382 case RTLD_DI_LINKMAP:
3383 *((struct link_map const **)p) = &obj->linkmap;
3385 case RTLD_DI_ORIGIN:
3386 error = rtld_dirname(obj->path, p);
3389 case RTLD_DI_SERINFOSIZE:
3390 case RTLD_DI_SERINFO:
3391 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3395 _rtld_error("Invalid request %d passed to dlinfo()", request);
3399 lock_release(rtld_bind_lock, &lockstate);
3405 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3408 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3409 phdr_info->dlpi_name = obj->path;
3410 phdr_info->dlpi_phdr = obj->phdr;
3411 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3412 phdr_info->dlpi_tls_modid = obj->tlsindex;
3413 phdr_info->dlpi_tls_data = obj->tlsinit;
3414 phdr_info->dlpi_adds = obj_loads;
3415 phdr_info->dlpi_subs = obj_loads - obj_count;
3419 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3421 struct dl_phdr_info phdr_info;
3422 const Obj_Entry *obj;
3423 RtldLockState bind_lockstate, phdr_lockstate;
3426 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3427 rlock_acquire(rtld_bind_lock, &bind_lockstate);
3431 for (obj = obj_list; obj != NULL; obj = obj->next) {
3432 rtld_fill_dl_phdr_info(obj, &phdr_info);
3433 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
3438 rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info);
3439 error = callback(&phdr_info, sizeof(phdr_info), param);
3442 lock_release(rtld_bind_lock, &bind_lockstate);
3443 lock_release(rtld_phdr_lock, &phdr_lockstate);
3449 fill_search_info(const char *dir, size_t dirlen, void *param)
3451 struct fill_search_info_args *arg;
3455 if (arg->request == RTLD_DI_SERINFOSIZE) {
3456 arg->serinfo->dls_cnt ++;
3457 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3459 struct dl_serpath *s_entry;
3461 s_entry = arg->serpath;
3462 s_entry->dls_name = arg->strspace;
3463 s_entry->dls_flags = arg->flags;
3465 strncpy(arg->strspace, dir, dirlen);
3466 arg->strspace[dirlen] = '\0';
3468 arg->strspace += dirlen + 1;
3476 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3478 struct dl_serinfo _info;
3479 struct fill_search_info_args args;
3481 args.request = RTLD_DI_SERINFOSIZE;
3482 args.serinfo = &_info;
3484 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3487 path_enumerate(obj->rpath, fill_search_info, &args);
3488 path_enumerate(ld_library_path, fill_search_info, &args);
3489 path_enumerate(obj->runpath, fill_search_info, &args);
3490 path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args);
3491 if (!obj->z_nodeflib)
3492 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
3495 if (request == RTLD_DI_SERINFOSIZE) {
3496 info->dls_size = _info.dls_size;
3497 info->dls_cnt = _info.dls_cnt;
3501 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3502 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3506 args.request = RTLD_DI_SERINFO;
3507 args.serinfo = info;
3508 args.serpath = &info->dls_serpath[0];
3509 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3511 args.flags = LA_SER_RUNPATH;
3512 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3515 args.flags = LA_SER_LIBPATH;
3516 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3519 args.flags = LA_SER_RUNPATH;
3520 if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
3523 args.flags = LA_SER_CONFIG;
3524 if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args)
3528 args.flags = LA_SER_DEFAULT;
3529 if (!obj->z_nodeflib &&
3530 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3536 rtld_dirname(const char *path, char *bname)
3540 /* Empty or NULL string gets treated as "." */
3541 if (path == NULL || *path == '\0') {
3547 /* Strip trailing slashes */
3548 endp = path + strlen(path) - 1;
3549 while (endp > path && *endp == '/')
3552 /* Find the start of the dir */
3553 while (endp > path && *endp != '/')
3556 /* Either the dir is "/" or there are no slashes */
3558 bname[0] = *endp == '/' ? '/' : '.';
3564 } while (endp > path && *endp == '/');
3567 if (endp - path + 2 > PATH_MAX)
3569 _rtld_error("Filename is too long: %s", path);
3573 strncpy(bname, path, endp - path + 1);
3574 bname[endp - path + 1] = '\0';
3579 rtld_dirname_abs(const char *path, char *base)
3583 if (realpath(path, base) == NULL)
3585 dbg("%s -> %s", path, base);
3586 last = strrchr(base, '/');
3595 linkmap_add(Obj_Entry *obj)
3597 struct link_map *l = &obj->linkmap;
3598 struct link_map *prev;
3600 obj->linkmap.l_name = obj->path;
3601 obj->linkmap.l_addr = obj->mapbase;
3602 obj->linkmap.l_ld = obj->dynamic;
3604 /* GDB needs load offset on MIPS to use the symbols */
3605 obj->linkmap.l_offs = obj->relocbase;
3608 if (r_debug.r_map == NULL) {
3614 * Scan to the end of the list, but not past the entry for the
3615 * dynamic linker, which we want to keep at the very end.
3617 for (prev = r_debug.r_map;
3618 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3619 prev = prev->l_next)
3622 /* Link in the new entry. */
3624 l->l_next = prev->l_next;
3625 if (l->l_next != NULL)
3626 l->l_next->l_prev = l;
3631 linkmap_delete(Obj_Entry *obj)
3633 struct link_map *l = &obj->linkmap;
3635 if (l->l_prev == NULL) {
3636 if ((r_debug.r_map = l->l_next) != NULL)
3637 l->l_next->l_prev = NULL;
3641 if ((l->l_prev->l_next = l->l_next) != NULL)
3642 l->l_next->l_prev = l->l_prev;
3646 * Function for the debugger to set a breakpoint on to gain control.
3648 * The two parameters allow the debugger to easily find and determine
3649 * what the runtime loader is doing and to whom it is doing it.
3651 * When the loadhook trap is hit (r_debug_state, set at program
3652 * initialization), the arguments can be found on the stack:
3654 * +8 struct link_map *m
3655 * +4 struct r_debug *rd
3659 r_debug_state(struct r_debug* rd, struct link_map *m)
3662 * The following is a hack to force the compiler to emit calls to
3663 * this function, even when optimizing. If the function is empty,
3664 * the compiler is not obliged to emit any code for calls to it,
3665 * even when marked __noinline. However, gdb depends on those
3668 __compiler_membar();
3672 * A function called after init routines have completed. This can be used to
3673 * break before a program's entry routine is called, and can be used when
3674 * main is not available in the symbol table.
3677 _r_debug_postinit(struct link_map *m)
3680 /* See r_debug_state(). */
3681 __compiler_membar();
3685 * Get address of the pointer variable in the main program.
3686 * Prefer non-weak symbol over the weak one.
3688 static const void **
3689 get_program_var_addr(const char *name, RtldLockState *lockstate)
3694 symlook_init(&req, name);
3695 req.lockstate = lockstate;
3696 donelist_init(&donelist);
3697 if (symlook_global(&req, &donelist) != 0)
3699 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3700 return ((const void **)make_function_pointer(req.sym_out,
3702 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3703 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3705 return ((const void **)(req.defobj_out->relocbase +
3706 req.sym_out->st_value));
3710 * Set a pointer variable in the main program to the given value. This
3711 * is used to set key variables such as "environ" before any of the
3712 * init functions are called.
3715 set_program_var(const char *name, const void *value)
3719 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3720 dbg("\"%s\": *%p <-- %p", name, addr, value);
3726 * Search the global objects, including dependencies and main object,
3727 * for the given symbol.
3730 symlook_global(SymLook *req, DoneList *donelist)
3733 const Objlist_Entry *elm;
3736 symlook_init_from_req(&req1, req);
3738 /* Search all objects loaded at program start up. */
3739 if (req->defobj_out == NULL ||
3740 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3741 res = symlook_list(&req1, &list_main, donelist);
3742 if (res == 0 && (req->defobj_out == NULL ||
3743 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3744 req->sym_out = req1.sym_out;
3745 req->defobj_out = req1.defobj_out;
3746 assert(req->defobj_out != NULL);
3750 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3751 STAILQ_FOREACH(elm, &list_global, link) {
3752 if (req->defobj_out != NULL &&
3753 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3755 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3756 if (res == 0 && (req->defobj_out == NULL ||
3757 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3758 req->sym_out = req1.sym_out;
3759 req->defobj_out = req1.defobj_out;
3760 assert(req->defobj_out != NULL);
3764 return (req->sym_out != NULL ? 0 : ESRCH);
3768 * Given a symbol name in a referencing object, find the corresponding
3769 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3770 * no definition was found. Returns a pointer to the Obj_Entry of the
3771 * defining object via the reference parameter DEFOBJ_OUT.
3774 symlook_default(SymLook *req, const Obj_Entry *refobj)
3777 const Objlist_Entry *elm;
3781 donelist_init(&donelist);
3782 symlook_init_from_req(&req1, req);
3784 /* Look first in the referencing object if linked symbolically. */
3785 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3786 res = symlook_obj(&req1, refobj);
3788 req->sym_out = req1.sym_out;
3789 req->defobj_out = req1.defobj_out;
3790 assert(req->defobj_out != NULL);
3794 symlook_global(req, &donelist);
3796 /* Search all dlopened DAGs containing the referencing object. */
3797 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3798 if (req->sym_out != NULL &&
3799 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3801 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3802 if (res == 0 && (req->sym_out == NULL ||
3803 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3804 req->sym_out = req1.sym_out;
3805 req->defobj_out = req1.defobj_out;
3806 assert(req->defobj_out != NULL);
3811 * Search the dynamic linker itself, and possibly resolve the
3812 * symbol from there. This is how the application links to
3813 * dynamic linker services such as dlopen.
3815 if (req->sym_out == NULL ||
3816 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3817 res = symlook_obj(&req1, &obj_rtld);
3819 req->sym_out = req1.sym_out;
3820 req->defobj_out = req1.defobj_out;
3821 assert(req->defobj_out != NULL);
3825 return (req->sym_out != NULL ? 0 : ESRCH);
3829 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3832 const Obj_Entry *defobj;
3833 const Objlist_Entry *elm;
3839 STAILQ_FOREACH(elm, objlist, link) {
3840 if (donelist_check(dlp, elm->obj))
3842 symlook_init_from_req(&req1, req);
3843 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3844 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3846 defobj = req1.defobj_out;
3847 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3854 req->defobj_out = defobj;
3861 * Search the chain of DAGS cointed to by the given Needed_Entry
3862 * for a symbol of the given name. Each DAG is scanned completely
3863 * before advancing to the next one. Returns a pointer to the symbol,
3864 * or NULL if no definition was found.
3867 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3870 const Needed_Entry *n;
3871 const Obj_Entry *defobj;
3877 symlook_init_from_req(&req1, req);
3878 for (n = needed; n != NULL; n = n->next) {
3879 if (n->obj == NULL ||
3880 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3882 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3884 defobj = req1.defobj_out;
3885 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3891 req->defobj_out = defobj;
3898 * Search the symbol table of a single shared object for a symbol of
3899 * the given name and version, if requested. Returns a pointer to the
3900 * symbol, or NULL if no definition was found. If the object is
3901 * filter, return filtered symbol from filtee.
3903 * The symbol's hash value is passed in for efficiency reasons; that
3904 * eliminates many recomputations of the hash value.
3907 symlook_obj(SymLook *req, const Obj_Entry *obj)
3911 int flags, res, mres;
3914 * If there is at least one valid hash at this point, we prefer to
3915 * use the faster GNU version if available.
3917 if (obj->valid_hash_gnu)
3918 mres = symlook_obj1_gnu(req, obj);
3919 else if (obj->valid_hash_sysv)
3920 mres = symlook_obj1_sysv(req, obj);
3925 if (obj->needed_filtees != NULL) {
3926 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3927 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3928 donelist_init(&donelist);
3929 symlook_init_from_req(&req1, req);
3930 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3932 req->sym_out = req1.sym_out;
3933 req->defobj_out = req1.defobj_out;
3937 if (obj->needed_aux_filtees != NULL) {
3938 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3939 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3940 donelist_init(&donelist);
3941 symlook_init_from_req(&req1, req);
3942 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3944 req->sym_out = req1.sym_out;
3945 req->defobj_out = req1.defobj_out;
3953 /* Symbol match routine common to both hash functions */
3955 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
3956 const unsigned long symnum)
3959 const Elf_Sym *symp;
3962 symp = obj->symtab + symnum;
3963 strp = obj->strtab + symp->st_name;
3965 switch (ELF_ST_TYPE(symp->st_info)) {
3971 if (symp->st_value == 0)
3975 if (symp->st_shndx != SHN_UNDEF)
3978 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3979 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3986 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
3989 if (req->ventry == NULL) {
3990 if (obj->versyms != NULL) {
3991 verndx = VER_NDX(obj->versyms[symnum]);
3992 if (verndx > obj->vernum) {
3994 "%s: symbol %s references wrong version %d",
3995 obj->path, obj->strtab + symnum, verndx);
3999 * If we are not called from dlsym (i.e. this
4000 * is a normal relocation from unversioned
4001 * binary), accept the symbol immediately if
4002 * it happens to have first version after this
4003 * shared object became versioned. Otherwise,
4004 * if symbol is versioned and not hidden,
4005 * remember it. If it is the only symbol with
4006 * this name exported by the shared object, it
4007 * will be returned as a match by the calling
4008 * function. If symbol is global (verndx < 2)
4009 * accept it unconditionally.
4011 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
4012 verndx == VER_NDX_GIVEN) {
4013 result->sym_out = symp;
4016 else if (verndx >= VER_NDX_GIVEN) {
4017 if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
4019 if (result->vsymp == NULL)
4020 result->vsymp = symp;
4026 result->sym_out = symp;
4029 if (obj->versyms == NULL) {
4030 if (object_match_name(obj, req->ventry->name)) {
4031 _rtld_error("%s: object %s should provide version %s "
4032 "for symbol %s", obj_rtld.path, obj->path,
4033 req->ventry->name, obj->strtab + symnum);
4037 verndx = VER_NDX(obj->versyms[symnum]);
4038 if (verndx > obj->vernum) {
4039 _rtld_error("%s: symbol %s references wrong version %d",
4040 obj->path, obj->strtab + symnum, verndx);
4043 if (obj->vertab[verndx].hash != req->ventry->hash ||
4044 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
4046 * Version does not match. Look if this is a
4047 * global symbol and if it is not hidden. If
4048 * global symbol (verndx < 2) is available,
4049 * use it. Do not return symbol if we are
4050 * called by dlvsym, because dlvsym looks for
4051 * a specific version and default one is not
4052 * what dlvsym wants.
4054 if ((req->flags & SYMLOOK_DLSYM) ||
4055 (verndx >= VER_NDX_GIVEN) ||
4056 (obj->versyms[symnum] & VER_NDX_HIDDEN))
4060 result->sym_out = symp;
4065 * Search for symbol using SysV hash function.
4066 * obj->buckets is known not to be NULL at this point; the test for this was
4067 * performed with the obj->valid_hash_sysv assignment.
4070 symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj)
4072 unsigned long symnum;
4073 Sym_Match_Result matchres;
4075 matchres.sym_out = NULL;
4076 matchres.vsymp = NULL;
4077 matchres.vcount = 0;
4079 for (symnum = obj->buckets[req->hash % obj->nbuckets];
4080 symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
4081 if (symnum >= obj->nchains)
4082 return (ESRCH); /* Bad object */
4084 if (matched_symbol(req, obj, &matchres, symnum)) {
4085 req->sym_out = matchres.sym_out;
4086 req->defobj_out = obj;
4090 if (matchres.vcount == 1) {
4091 req->sym_out = matchres.vsymp;
4092 req->defobj_out = obj;
4098 /* Search for symbol using GNU hash function */
4100 symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj)
4102 Elf_Addr bloom_word;
4103 const Elf32_Word *hashval;
4105 Sym_Match_Result matchres;
4106 unsigned int h1, h2;
4107 unsigned long symnum;
4109 matchres.sym_out = NULL;
4110 matchres.vsymp = NULL;
4111 matchres.vcount = 0;
4113 /* Pick right bitmask word from Bloom filter array */
4114 bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) &
4115 obj->maskwords_bm_gnu];
4117 /* Calculate modulus word size of gnu hash and its derivative */
4118 h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1);
4119 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1));
4121 /* Filter out the "definitely not in set" queries */
4122 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
4125 /* Locate hash chain and corresponding value element*/
4126 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
4129 hashval = &obj->chain_zero_gnu[bucket];
4131 if (((*hashval ^ req->hash_gnu) >> 1) == 0) {
4132 symnum = hashval - obj->chain_zero_gnu;
4133 if (matched_symbol(req, obj, &matchres, symnum)) {
4134 req->sym_out = matchres.sym_out;
4135 req->defobj_out = obj;
4139 } while ((*hashval++ & 1) == 0);
4140 if (matchres.vcount == 1) {
4141 req->sym_out = matchres.vsymp;
4142 req->defobj_out = obj;
4149 trace_loaded_objects(Obj_Entry *obj)
4151 char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
4154 if ((main_local = getenv(LD_ "TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
4157 if ((fmt1 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT1")) == NULL)
4158 fmt1 = "\t%o => %p (%x)\n";
4160 if ((fmt2 = getenv(LD_ "TRACE_LOADED_OBJECTS_FMT2")) == NULL)
4161 fmt2 = "\t%o (%x)\n";
4163 list_containers = getenv(LD_ "TRACE_LOADED_OBJECTS_ALL");
4165 for (; obj; obj = obj->next) {
4166 Needed_Entry *needed;
4170 if (list_containers && obj->needed != NULL)
4171 rtld_printf("%s:\n", obj->path);
4172 for (needed = obj->needed; needed; needed = needed->next) {
4173 if (needed->obj != NULL) {
4174 if (needed->obj->traced && !list_containers)
4176 needed->obj->traced = true;
4177 path = needed->obj->path;
4181 name = (char *)obj->strtab + needed->name;
4182 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
4184 fmt = is_lib ? fmt1 : fmt2;
4185 while ((c = *fmt++) != '\0') {
4211 rtld_putstr(main_local);
4214 rtld_putstr(obj_main->path);
4221 rtld_printf("%d", sodp->sod_major);
4224 rtld_printf("%d", sodp->sod_minor);
4231 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4244 * Unload a dlopened object and its dependencies from memory and from
4245 * our data structures. It is assumed that the DAG rooted in the
4246 * object has already been unreferenced, and that the object has a
4247 * reference count of 0.
4250 unload_object(Obj_Entry *root)
4255 assert(root->refcount == 0);
4258 * Pass over the DAG removing unreferenced objects from
4259 * appropriate lists.
4261 unlink_object(root);
4263 /* Unmap all objects that are no longer referenced. */
4264 linkp = &obj_list->next;
4265 while ((obj = *linkp) != NULL) {
4266 if (obj->refcount == 0) {
4267 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
4269 dbg("unloading \"%s\"", obj->path);
4270 unload_filtees(root);
4271 munmap(obj->mapbase, obj->mapsize);
4272 linkmap_delete(obj);
4283 unlink_object(Obj_Entry *root)
4287 if (root->refcount == 0) {
4288 /* Remove the object from the RTLD_GLOBAL list. */
4289 objlist_remove(&list_global, root);
4291 /* Remove the object from all objects' DAG lists. */
4292 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4293 objlist_remove(&elm->obj->dldags, root);
4294 if (elm->obj != root)
4295 unlink_object(elm->obj);
4301 ref_dag(Obj_Entry *root)
4305 assert(root->dag_inited);
4306 STAILQ_FOREACH(elm, &root->dagmembers, link)
4307 elm->obj->refcount++;
4311 unref_dag(Obj_Entry *root)
4315 assert(root->dag_inited);
4316 STAILQ_FOREACH(elm, &root->dagmembers, link)
4317 elm->obj->refcount--;
4321 * Common code for MD __tls_get_addr().
4323 static void *tls_get_addr_slow(Elf_Addr **, int, size_t) __noinline;
4325 tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
4327 Elf_Addr *newdtv, *dtv;
4328 RtldLockState lockstate;
4332 /* Check dtv generation in case new modules have arrived */
4333 if (dtv[0] != tls_dtv_generation) {
4334 wlock_acquire(rtld_bind_lock, &lockstate);
4335 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4337 if (to_copy > tls_max_index)
4338 to_copy = tls_max_index;
4339 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4340 newdtv[0] = tls_dtv_generation;
4341 newdtv[1] = tls_max_index;
4343 lock_release(rtld_bind_lock, &lockstate);
4344 dtv = *dtvp = newdtv;
4347 /* Dynamically allocate module TLS if necessary */
4348 if (dtv[index + 1] == 0) {
4349 /* Signal safe, wlock will block out signals. */
4350 wlock_acquire(rtld_bind_lock, &lockstate);
4351 if (!dtv[index + 1])
4352 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4353 lock_release(rtld_bind_lock, &lockstate);
4355 return ((void *)(dtv[index + 1] + offset));
4359 tls_get_addr_common(Elf_Addr **dtvp, int index, size_t offset)
4364 /* Check dtv generation in case new modules have arrived */
4365 if (__predict_true(dtv[0] == tls_dtv_generation &&
4366 dtv[index + 1] != 0))
4367 return ((void *)(dtv[index + 1] + offset));
4368 return (tls_get_addr_slow(dtvp, index, offset));
4371 #if defined(__aarch64__) || defined(__arm__) || defined(__mips__) || \
4372 defined(__powerpc__)
4375 * Allocate Static TLS using the Variant I method.
4378 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
4387 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
4390 assert(tcbsize >= TLS_TCB_SIZE);
4391 tcb = xcalloc(1, tls_static_space - TLS_TCB_SIZE + tcbsize);
4392 tls = (Elf_Addr **)(tcb + tcbsize - TLS_TCB_SIZE);
4394 if (oldtcb != NULL) {
4395 memcpy(tls, oldtcb, tls_static_space);
4398 /* Adjust the DTV. */
4400 for (i = 0; i < dtv[1]; i++) {
4401 if (dtv[i+2] >= (Elf_Addr)oldtcb &&
4402 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) {
4403 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tls;
4407 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4409 dtv[0] = tls_dtv_generation;
4410 dtv[1] = tls_max_index;
4412 for (obj = objs; obj; obj = obj->next) {
4413 if (obj->tlsoffset > 0) {
4414 addr = (Elf_Addr)tls + obj->tlsoffset;
4415 if (obj->tlsinitsize > 0)
4416 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4417 if (obj->tlssize > obj->tlsinitsize)
4418 memset((void*) (addr + obj->tlsinitsize), 0,
4419 obj->tlssize - obj->tlsinitsize);
4420 dtv[obj->tlsindex + 1] = addr;
4429 free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
4432 Elf_Addr tlsstart, tlsend;
4435 assert(tcbsize >= TLS_TCB_SIZE);
4437 tlsstart = (Elf_Addr)tcb + tcbsize - TLS_TCB_SIZE;
4438 tlsend = tlsstart + tls_static_space;
4440 dtv = *(Elf_Addr **)tlsstart;
4442 for (i = 0; i < dtvsize; i++) {
4443 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) {
4444 free((void*)dtv[i+2]);
4453 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__)
4456 * Allocate Static TLS using the Variant II method.
4459 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
4462 size_t size, ralign;
4464 Elf_Addr *dtv, *olddtv;
4465 Elf_Addr segbase, oldsegbase, addr;
4469 if (tls_static_max_align > ralign)
4470 ralign = tls_static_max_align;
4471 size = round(tls_static_space, ralign) + round(tcbsize, ralign);
4473 assert(tcbsize >= 2*sizeof(Elf_Addr));
4474 tls = malloc_aligned(size, ralign);
4475 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4477 segbase = (Elf_Addr)(tls + round(tls_static_space, ralign));
4478 ((Elf_Addr*)segbase)[0] = segbase;
4479 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
4481 dtv[0] = tls_dtv_generation;
4482 dtv[1] = tls_max_index;
4486 * Copy the static TLS block over whole.
4488 oldsegbase = (Elf_Addr) oldtls;
4489 memcpy((void *)(segbase - tls_static_space),
4490 (const void *)(oldsegbase - tls_static_space),
4494 * If any dynamic TLS blocks have been created tls_get_addr(),
4497 olddtv = ((Elf_Addr**)oldsegbase)[1];
4498 for (i = 0; i < olddtv[1]; i++) {
4499 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) {
4500 dtv[i+2] = olddtv[i+2];
4506 * We assume that this block was the one we created with
4507 * allocate_initial_tls().
4509 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
4511 for (obj = objs; obj; obj = obj->next) {
4512 if (obj->tlsoffset) {
4513 addr = segbase - obj->tlsoffset;
4514 memset((void*) (addr + obj->tlsinitsize),
4515 0, obj->tlssize - obj->tlsinitsize);
4517 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4518 dtv[obj->tlsindex + 1] = addr;
4523 return (void*) segbase;
4527 free_tls(void *tls, size_t tcbsize, size_t tcbalign)
4530 size_t size, ralign;
4532 Elf_Addr tlsstart, tlsend;
4535 * Figure out the size of the initial TLS block so that we can
4536 * find stuff which ___tls_get_addr() allocated dynamically.
4539 if (tls_static_max_align > ralign)
4540 ralign = tls_static_max_align;
4541 size = round(tls_static_space, ralign);
4543 dtv = ((Elf_Addr**)tls)[1];
4545 tlsend = (Elf_Addr) tls;
4546 tlsstart = tlsend - size;
4547 for (i = 0; i < dtvsize; i++) {
4548 if (dtv[i + 2] != 0 && (dtv[i + 2] < tlsstart || dtv[i + 2] > tlsend)) {
4549 free_aligned((void *)dtv[i + 2]);
4553 free_aligned((void *)tlsstart);
4560 * Allocate TLS block for module with given index.
4563 allocate_module_tls(int index)
4568 for (obj = obj_list; obj; obj = obj->next) {
4569 if (obj->tlsindex == index)
4573 _rtld_error("Can't find module with TLS index %d", index);
4577 p = malloc_aligned(obj->tlssize, obj->tlsalign);
4578 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4579 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4585 allocate_tls_offset(Obj_Entry *obj)
4592 if (obj->tlssize == 0) {
4593 obj->tls_done = true;
4597 if (obj->tlsindex == 1)
4598 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4600 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4601 obj->tlssize, obj->tlsalign);
4604 * If we have already fixed the size of the static TLS block, we
4605 * must stay within that size. When allocating the static TLS, we
4606 * leave a small amount of space spare to be used for dynamically
4607 * loading modules which use static TLS.
4609 if (tls_static_space != 0) {
4610 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4612 } else if (obj->tlsalign > tls_static_max_align) {
4613 tls_static_max_align = obj->tlsalign;
4616 tls_last_offset = obj->tlsoffset = off;
4617 tls_last_size = obj->tlssize;
4618 obj->tls_done = true;
4624 free_tls_offset(Obj_Entry *obj)
4628 * If we were the last thing to allocate out of the static TLS
4629 * block, we give our space back to the 'allocator'. This is a
4630 * simplistic workaround to allow libGL.so.1 to be loaded and
4631 * unloaded multiple times.
4633 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
4634 == calculate_tls_end(tls_last_offset, tls_last_size)) {
4635 tls_last_offset -= obj->tlssize;
4641 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
4644 RtldLockState lockstate;
4646 wlock_acquire(rtld_bind_lock, &lockstate);
4647 ret = allocate_tls(obj_list, oldtls, tcbsize, tcbalign);
4648 lock_release(rtld_bind_lock, &lockstate);
4653 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
4655 RtldLockState lockstate;
4657 wlock_acquire(rtld_bind_lock, &lockstate);
4658 free_tls(tcb, tcbsize, tcbalign);
4659 lock_release(rtld_bind_lock, &lockstate);
4663 object_add_name(Obj_Entry *obj, const char *name)
4669 entry = malloc(sizeof(Name_Entry) + len);
4671 if (entry != NULL) {
4672 strcpy(entry->name, name);
4673 STAILQ_INSERT_TAIL(&obj->names, entry, link);
4678 object_match_name(const Obj_Entry *obj, const char *name)
4682 STAILQ_FOREACH(entry, &obj->names, link) {
4683 if (strcmp(name, entry->name) == 0)
4690 locate_dependency(const Obj_Entry *obj, const char *name)
4692 const Objlist_Entry *entry;
4693 const Needed_Entry *needed;
4695 STAILQ_FOREACH(entry, &list_main, link) {
4696 if (object_match_name(entry->obj, name))
4700 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4701 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4702 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4704 * If there is DT_NEEDED for the name we are looking for,
4705 * we are all set. Note that object might not be found if
4706 * dependency was not loaded yet, so the function can
4707 * return NULL here. This is expected and handled
4708 * properly by the caller.
4710 return (needed->obj);
4713 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4719 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4720 const Elf_Vernaux *vna)
4722 const Elf_Verdef *vd;
4723 const char *vername;
4725 vername = refobj->strtab + vna->vna_name;
4726 vd = depobj->verdef;
4728 _rtld_error("%s: version %s required by %s not defined",
4729 depobj->path, vername, refobj->path);
4733 if (vd->vd_version != VER_DEF_CURRENT) {
4734 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4735 depobj->path, vd->vd_version);
4738 if (vna->vna_hash == vd->vd_hash) {
4739 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4740 ((char *)vd + vd->vd_aux);
4741 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4744 if (vd->vd_next == 0)
4746 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4748 if (vna->vna_flags & VER_FLG_WEAK)
4750 _rtld_error("%s: version %s required by %s not found",
4751 depobj->path, vername, refobj->path);
4756 rtld_verify_object_versions(Obj_Entry *obj)
4758 const Elf_Verneed *vn;
4759 const Elf_Verdef *vd;
4760 const Elf_Verdaux *vda;
4761 const Elf_Vernaux *vna;
4762 const Obj_Entry *depobj;
4763 int maxvernum, vernum;
4765 if (obj->ver_checked)
4767 obj->ver_checked = true;
4771 * Walk over defined and required version records and figure out
4772 * max index used by any of them. Do very basic sanity checking
4776 while (vn != NULL) {
4777 if (vn->vn_version != VER_NEED_CURRENT) {
4778 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4779 obj->path, vn->vn_version);
4782 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4784 vernum = VER_NEED_IDX(vna->vna_other);
4785 if (vernum > maxvernum)
4787 if (vna->vna_next == 0)
4789 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4791 if (vn->vn_next == 0)
4793 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4797 while (vd != NULL) {
4798 if (vd->vd_version != VER_DEF_CURRENT) {
4799 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4800 obj->path, vd->vd_version);
4803 vernum = VER_DEF_IDX(vd->vd_ndx);
4804 if (vernum > maxvernum)
4806 if (vd->vd_next == 0)
4808 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4815 * Store version information in array indexable by version index.
4816 * Verify that object version requirements are satisfied along the
4819 obj->vernum = maxvernum + 1;
4820 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
4823 while (vd != NULL) {
4824 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4825 vernum = VER_DEF_IDX(vd->vd_ndx);
4826 assert(vernum <= maxvernum);
4827 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4828 obj->vertab[vernum].hash = vd->vd_hash;
4829 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4830 obj->vertab[vernum].file = NULL;
4831 obj->vertab[vernum].flags = 0;
4833 if (vd->vd_next == 0)
4835 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4839 while (vn != NULL) {
4840 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4843 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4845 if (check_object_provided_version(obj, depobj, vna))
4847 vernum = VER_NEED_IDX(vna->vna_other);
4848 assert(vernum <= maxvernum);
4849 obj->vertab[vernum].hash = vna->vna_hash;
4850 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4851 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4852 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4853 VER_INFO_HIDDEN : 0;
4854 if (vna->vna_next == 0)
4856 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4858 if (vn->vn_next == 0)
4860 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4866 rtld_verify_versions(const Objlist *objlist)
4868 Objlist_Entry *entry;
4872 STAILQ_FOREACH(entry, objlist, link) {
4874 * Skip dummy objects or objects that have their version requirements
4877 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4879 if (rtld_verify_object_versions(entry->obj) == -1) {
4881 if (ld_tracing == NULL)
4885 if (rc == 0 || ld_tracing != NULL)
4886 rc = rtld_verify_object_versions(&obj_rtld);
4891 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4896 vernum = VER_NDX(obj->versyms[symnum]);
4897 if (vernum >= obj->vernum) {
4898 _rtld_error("%s: symbol %s has wrong verneed value %d",
4899 obj->path, obj->strtab + symnum, vernum);
4900 } else if (obj->vertab[vernum].hash != 0) {
4901 return &obj->vertab[vernum];
4908 _rtld_get_stack_prot(void)
4911 return (stack_prot);
4915 _rtld_is_dlopened(void *arg)
4918 RtldLockState lockstate;
4921 rlock_acquire(rtld_bind_lock, &lockstate);
4924 obj = obj_from_addr(arg);
4926 _rtld_error("No shared object contains address");
4927 lock_release(rtld_bind_lock, &lockstate);
4930 res = obj->dlopened ? 1 : 0;
4931 lock_release(rtld_bind_lock, &lockstate);
4936 map_stacks_exec(RtldLockState *lockstate)
4938 void (*thr_map_stacks_exec)(void);
4940 if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4942 thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4943 get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4944 if (thr_map_stacks_exec != NULL) {
4945 stack_prot |= PROT_EXEC;
4946 thr_map_stacks_exec();
4951 symlook_init(SymLook *dst, const char *name)
4954 bzero(dst, sizeof(*dst));
4956 dst->hash = elf_hash(name);
4957 dst->hash_gnu = gnu_hash(name);
4961 symlook_init_from_req(SymLook *dst, const SymLook *src)
4964 dst->name = src->name;
4965 dst->hash = src->hash;
4966 dst->hash_gnu = src->hash_gnu;
4967 dst->ventry = src->ventry;
4968 dst->flags = src->flags;
4969 dst->defobj_out = NULL;
4970 dst->sym_out = NULL;
4971 dst->lockstate = src->lockstate;
4976 * Parse a file descriptor number without pulling in more of libc (e.g. atoi).
4979 parse_libdir(const char *str)
4981 static const int RADIX = 10; /* XXXJA: possibly support hex? */
4988 for (c = *str; c != '\0'; c = *++str) {
4989 if (c < '0' || c > '9')
4996 /* Make sure we actually parsed something. */
4998 _rtld_error("failed to parse directory FD from '%s'", str);
5005 * Overrides for libc_pic-provided functions.
5009 __getosreldate(void)
5019 oid[1] = KERN_OSRELDATE;
5021 len = sizeof(osrel);
5022 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
5023 if (error == 0 && osrel > 0 && len == sizeof(osrel))
5035 void (*__cleanup)(void);
5036 int __isthreaded = 0;
5037 int _thread_autoinit_dummy_decl = 1;
5040 * No unresolved symbols for rtld.
5043 __pthread_cxa_finalize(struct dl_phdr_info *a)
5048 __stack_chk_fail(void)
5051 _rtld_error("stack overflow detected; terminated");
5054 __weak_reference(__stack_chk_fail, __stack_chk_fail_local);
5060 _rtld_error("buffer overflow detected; terminated");
5065 rtld_strerror(int errnum)
5068 if (errnum < 0 || errnum >= sys_nerr)
5069 return ("Unknown error");
5070 return (sys_errlist[errnum]);