2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * Copyright 2009, 2010, 2011 Konstantin Belousov <kib@FreeBSD.ORG>.
5 * Copyright 2012 John Marino <draco@marino.st>.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 * Dynamic linker for ELF.
34 * John Polstra <jdp@polstra.com>.
38 #error "GCC is needed to compile this file"
41 #include <sys/param.h>
42 #include <sys/mount.h>
45 #include <sys/sysctl.h>
47 #include <sys/utsname.h>
48 #include <sys/ktrace.h>
49 #include <sys/resident.h>
52 #include <machine/tls.h>
67 #include "rtld_printf.h"
70 #define PATH_RTLD "/usr/libexec/ld-elf.so.2"
71 #define LD_ARY_CACHE 16
74 typedef void (*func_ptr_type)();
75 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
78 * Function declarations.
80 static const char *_getenv_ld(const char *id);
81 static void die(void) __dead2;
82 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
83 const Elf_Dyn **, const Elf_Dyn **);
84 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
86 static void digest_dynamic(Obj_Entry *, int);
87 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
88 static Obj_Entry *dlcheck(void *);
89 static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
90 int lo_flags, int mode, RtldLockState *lockstate);
91 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
92 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
93 static bool donelist_check(DoneList *, const Obj_Entry *);
94 static void errmsg_restore(char *);
95 static char *errmsg_save(void);
96 static void *fill_search_info(const char *, size_t, void *);
97 static char *find_library(const char *, const Obj_Entry *);
98 static const char *gethints(const Obj_Entry *);
99 static void init_dag(Obj_Entry *);
100 static void init_rtld(caddr_t, Elf_Auxinfo **);
101 static void initlist_add_neededs(Needed_Entry *, Objlist *);
102 static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
103 static bool is_exported(const Elf_Sym *);
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 preinitialize_main_object (void);
116 static void objlist_clear(Objlist *);
117 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
118 static void objlist_init(Objlist *);
119 static void objlist_push_head(Objlist *, Obj_Entry *);
120 static void objlist_push_tail(Objlist *, Obj_Entry *);
121 static void objlist_remove(Objlist *, Obj_Entry *);
122 static void *path_enumerate(const char *, path_enum_proc, void *);
123 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
125 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
126 int flags, RtldLockState *lockstate);
127 static int rtld_dirname(const char *, char *);
128 static int rtld_dirname_abs(const char *, char *);
129 static void *rtld_dlopen(const char *name, int fd, int mode);
130 static void rtld_exit(void);
131 static char *search_library_path(const char *, const char *);
132 static const void **get_program_var_addr(const char *, RtldLockState *);
133 static void set_program_var(const char *, const void *);
134 static int symlook_default(SymLook *, const Obj_Entry *refobj);
135 static int symlook_global(SymLook *, DoneList *);
136 static void symlook_init_from_req(SymLook *, const SymLook *);
137 static int symlook_list(SymLook *, const Objlist *, DoneList *);
138 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
139 static int symlook_obj1(SymLook *, const Obj_Entry *);
140 static int symlook_obj2(SymLook *, const Obj_Entry *);
141 static void trace_loaded_objects(Obj_Entry *);
142 static void unlink_object(Obj_Entry *);
143 static void unload_object(Obj_Entry *);
144 static void unref_dag(Obj_Entry *);
145 static void ref_dag(Obj_Entry *);
146 static int origin_subst_one(char **, const char *, const char *,
147 const char *, char *);
148 static char *origin_subst(const char *, const char *);
149 static int rtld_verify_versions(const Objlist *);
150 static int rtld_verify_object_versions(Obj_Entry *);
151 static void object_add_name(Obj_Entry *, const char *);
152 static int object_match_name(const Obj_Entry *, const char *);
153 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
154 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
155 struct dl_phdr_info *phdr_info);
156 static uint_fast32_t gnu_hash (const char *);
157 static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
158 const unsigned long);
160 void r_debug_state(struct r_debug *, struct link_map *) __noinline;
165 static char *error_message; /* Message for dlerror(), or NULL */
166 struct r_debug r_debug; /* for GDB; */
167 static bool libmap_disable; /* Disable libmap */
168 static bool ld_loadfltr; /* Immediate filters processing */
169 static char *libmap_override; /* Maps to use in addition to libmap.conf */
170 static bool trust; /* False for setuid and setgid programs */
171 static bool dangerous_ld_env; /* True if environment variables have been
172 used to affect the libraries loaded */
173 static const char *ld_bind_now; /* Environment variable for immediate binding */
174 static const char *ld_debug; /* Environment variable for debugging */
175 static const char *ld_library_path; /* Environment variable for search path */
176 static char *ld_preload; /* Environment variable for libraries to
178 static const char *ld_elf_hints_path; /* Environment variable for alternative hints path */
179 static const char *ld_tracing; /* Called from ldd to print libs */
180 static const char *ld_utrace; /* Use utrace() to log events. */
181 static int (*rtld_functrace)( /* Optional function call tracing hook */
182 const char *caller_obj,
183 const char *callee_obj,
184 const char *callee_func,
186 static const Obj_Entry *rtld_functrace_obj; /* Object thereof */
187 static Obj_Entry *obj_list; /* Head of linked list of shared objects */
188 static Obj_Entry **obj_tail; /* Link field of last object in list */
189 static Obj_Entry **preload_tail;
190 static Obj_Entry *obj_main; /* The main program shared object */
191 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
192 static unsigned int obj_count; /* Number of objects in obj_list */
193 static unsigned int obj_loads; /* Number of objects in obj_list */
195 static int ld_resident; /* Non-zero if resident */
196 static const char *ld_ary[LD_ARY_CACHE];
198 static Objlist initlist;
200 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
201 STAILQ_HEAD_INITIALIZER(list_global);
202 static Objlist list_main = /* Objects loaded at program startup */
203 STAILQ_HEAD_INITIALIZER(list_main);
204 static Objlist list_fini = /* Objects needing fini() calls */
205 STAILQ_HEAD_INITIALIZER(list_fini);
207 static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
209 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
211 extern Elf_Dyn _DYNAMIC;
212 #pragma weak _DYNAMIC
213 #ifndef RTLD_IS_DYNAMIC
214 #define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
217 #ifdef ENABLE_OSRELDATE
221 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
222 static int max_stack_flags;
225 * These are the functions the dynamic linker exports to application
226 * programs. They are the only symbols the dynamic linker is willing
227 * to export from itself.
229 static func_ptr_type exports[] = {
230 (func_ptr_type) &_rtld_error,
231 (func_ptr_type) &dlclose,
232 (func_ptr_type) &dlerror,
233 (func_ptr_type) &dlopen,
234 (func_ptr_type) &fdlopen,
235 (func_ptr_type) &dlfunc,
236 (func_ptr_type) &dlsym,
237 (func_ptr_type) &dlvsym,
238 (func_ptr_type) &dladdr,
239 (func_ptr_type) &dlinfo,
240 (func_ptr_type) &dl_iterate_phdr,
242 (func_ptr_type) &___tls_get_addr,
244 (func_ptr_type) &__tls_get_addr,
245 (func_ptr_type) &__tls_get_addr_tcb,
246 (func_ptr_type) &_rtld_allocate_tls,
247 (func_ptr_type) &_rtld_free_tls,
248 (func_ptr_type) &_rtld_call_init,
249 (func_ptr_type) &_rtld_thread_init,
250 (func_ptr_type) &_rtld_addr_phdr,
251 (func_ptr_type) &_rtld_get_stack_prot,
256 * Global declarations normally provided by crt1. The dynamic linker is
257 * not built with crt1, so we have to provide them ourselves.
263 * Used to pass argc, argv to init functions.
269 * Globals to control TLS allocation.
271 size_t tls_last_offset; /* Static TLS offset of last module */
272 size_t tls_last_size; /* Static TLS size of last module */
273 size_t tls_static_space; /* Static TLS space allocated */
274 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
275 int tls_max_index = 1; /* Largest module index allocated */
278 * Fill in a DoneList with an allocation large enough to hold all of
279 * the currently-loaded objects. Keep this as a macro since it calls
280 * alloca and we want that to occur within the scope of the caller.
282 #define donelist_init(dlp) \
283 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
284 assert((dlp)->objs != NULL), \
285 (dlp)->num_alloc = obj_count, \
288 #define UTRACE_DLOPEN_START 1
289 #define UTRACE_DLOPEN_STOP 2
290 #define UTRACE_DLCLOSE_START 3
291 #define UTRACE_DLCLOSE_STOP 4
292 #define UTRACE_LOAD_OBJECT 5
293 #define UTRACE_UNLOAD_OBJECT 6
294 #define UTRACE_ADD_RUNDEP 7
295 #define UTRACE_PRELOAD_FINISHED 8
296 #define UTRACE_INIT_CALL 9
297 #define UTRACE_FINI_CALL 10
300 char sig[4]; /* 'RTLD' */
303 void *mapbase; /* Used for 'parent' and 'init/fini' */
305 int refcnt; /* Used for 'mode' */
306 char name[MAXPATHLEN];
309 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
310 if (ld_utrace != NULL) \
311 ld_utrace_log(e, h, mb, ms, r, n); \
315 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
316 int refcnt, const char *name)
318 struct utrace_rtld ut;
326 ut.mapbase = mapbase;
327 ut.mapsize = mapsize;
329 bzero(ut.name, sizeof(ut.name));
331 strlcpy(ut.name, name, sizeof(ut.name));
332 utrace(&ut, sizeof(ut));
336 * Main entry point for dynamic linking. The first argument is the
337 * stack pointer. The stack is expected to be laid out as described
338 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
339 * Specifically, the stack pointer points to a word containing
340 * ARGC. Following that in the stack is a null-terminated sequence
341 * of pointers to argument strings. Then comes a null-terminated
342 * sequence of pointers to environment strings. Finally, there is a
343 * sequence of "auxiliary vector" entries.
345 * The second argument points to a place to store the dynamic linker's
346 * exit procedure pointer and the third to a place to store the main
349 * The return value is the main program's entry point.
352 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
354 Elf_Auxinfo *aux_info[AT_COUNT];
362 Objlist_Entry *entry;
365 /* marino: DO NOT MOVE THESE VARIABLES TO _rtld
366 Obj_Entry **preload_tail;
368 from global to here. It will break the DWARF2 unwind scheme.
369 The system compilers were unaffected, but not gcc 4.6
373 * On entry, the dynamic linker itself has not been relocated yet.
374 * Be very careful not to reference any global data until after
375 * init_rtld has returned. It is OK to reference file-scope statics
376 * and string constants, and to call static and global functions.
379 /* Find the auxiliary vector on the stack. */
382 sp += argc + 1; /* Skip over arguments and NULL terminator */
386 * If we aren't already resident we have to dig out some more info.
387 * Note that auxinfo does not exist when we are resident.
389 * I'm not sure about the ld_resident check. It seems to read zero
390 * prior to relocation, which is what we want. When running from a
391 * resident copy everything will be relocated so we are definitely
394 if (ld_resident == 0) {
395 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
397 aux = (Elf_Auxinfo *) sp;
399 /* Digest the auxiliary vector. */
400 for (i = 0; i < AT_COUNT; i++)
402 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
403 if (auxp->a_type < AT_COUNT)
404 aux_info[auxp->a_type] = auxp;
407 /* Initialize and relocate ourselves. */
408 assert(aux_info[AT_BASE] != NULL);
409 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
412 ld_index = 0; /* don't use old env cache in case we are resident */
413 __progname = obj_rtld.path;
414 argv0 = argv[0] != NULL ? argv[0] : "(null)";
419 trust = !issetugid();
421 ld_bind_now = _getenv_ld("LD_BIND_NOW");
423 * If the process is tainted, then we un-set the dangerous environment
424 * variables. The process will be marked as tainted until setuid(2)
425 * is called. If any child process calls setuid(2) we do not want any
426 * future processes to honor the potentially un-safe variables.
429 if ( unsetenv("LD_DEBUG")
430 || unsetenv("LD_PRELOAD")
431 || unsetenv("LD_LIBRARY_PATH")
432 || unsetenv("LD_ELF_HINTS_PATH")
433 || unsetenv("LD_LIBMAP")
434 || unsetenv("LD_LIBMAP_DISABLE")
435 || unsetenv("LD_LOADFLTR")
437 _rtld_error("environment corrupt; aborting");
441 ld_debug = _getenv_ld("LD_DEBUG");
442 libmap_disable = _getenv_ld("LD_LIBMAP_DISABLE") != NULL;
443 libmap_override = (char *)_getenv_ld("LD_LIBMAP");
444 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
445 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
446 ld_elf_hints_path = _getenv_ld("LD_ELF_HINTS_PATH");
447 ld_loadfltr = _getenv_ld("LD_LOADFLTR") != NULL;
448 dangerous_ld_env = (ld_library_path != NULL)
449 || (ld_preload != NULL)
450 || (ld_elf_hints_path != NULL)
452 || (libmap_override != NULL)
455 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
456 ld_utrace = _getenv_ld("LD_UTRACE");
458 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
459 ld_elf_hints_path = _PATH_ELF_HINTS;
461 if (ld_debug != NULL && *ld_debug != '\0')
463 dbg("%s is initialized, base address = %p", __progname,
464 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
465 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
466 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
468 dbg("initializing thread locks");
472 * If we are resident we can skip work that we have already done.
473 * Note that the stack is reset and there is no Elf_Auxinfo
474 * when running from a resident image, and the static globals setup
475 * between here and resident_skip will have already been setup.
481 * Load the main program, or process its program header if it is
484 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
485 int fd = aux_info[AT_EXECFD]->a_un.a_val;
486 dbg("loading main program");
487 obj_main = map_object(fd, argv0, NULL);
489 if (obj_main == NULL)
491 max_stack_flags = obj->stack_flags;
492 } else { /* Main program already loaded. */
493 const Elf_Phdr *phdr;
497 dbg("processing main program's program header");
498 assert(aux_info[AT_PHDR] != NULL);
499 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
500 assert(aux_info[AT_PHNUM] != NULL);
501 phnum = aux_info[AT_PHNUM]->a_un.a_val;
502 assert(aux_info[AT_PHENT] != NULL);
503 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
504 assert(aux_info[AT_ENTRY] != NULL);
505 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
506 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
510 char buf[MAXPATHLEN];
511 if (aux_info[AT_EXECPATH] != NULL) {
514 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
515 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
516 if (kexecpath[0] == '/')
517 obj_main->path = kexecpath;
518 else if (getcwd(buf, sizeof(buf)) == NULL ||
519 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
520 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
521 obj_main->path = xstrdup(argv0);
523 obj_main->path = xstrdup(buf);
525 char resolved[MAXPATHLEN];
526 dbg("No AT_EXECPATH");
527 if (argv0[0] == '/') {
528 if (realpath(argv0, resolved) != NULL)
529 obj_main->path = xstrdup(resolved);
531 obj_main->path = xstrdup(argv0);
533 if (getcwd(buf, sizeof(buf)) != NULL
534 && strlcat(buf, "/", sizeof(buf)) < sizeof(buf)
535 && strlcat(buf, argv0, sizeof (buf)) < sizeof(buf)
536 && access(buf, R_OK) == 0
537 && realpath(buf, resolved) != NULL)
538 obj_main->path = xstrdup(resolved);
540 obj_main->path = xstrdup(argv0);
543 dbg("obj_main path %s", obj_main->path);
544 obj_main->mainprog = true;
546 if (aux_info[AT_STACKPROT] != NULL &&
547 aux_info[AT_STACKPROT]->a_un.a_val != 0)
548 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
551 * Get the actual dynamic linker pathname from the executable if
552 * possible. (It should always be possible.) That ensures that
553 * gdb will find the right dynamic linker even if a non-standard
556 if (obj_main->interp != NULL &&
557 strcmp(obj_main->interp, obj_rtld.path) != 0) {
559 obj_rtld.path = xstrdup(obj_main->interp);
560 __progname = obj_rtld.path;
563 digest_dynamic(obj_main, 0);
565 linkmap_add(obj_main);
566 linkmap_add(&obj_rtld);
568 /* Link the main program into the list of objects. */
569 *obj_tail = obj_main;
570 obj_tail = &obj_main->next;
574 /* Initialize a fake symbol for resolving undefined weak references. */
575 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
576 sym_zero.st_shndx = SHN_UNDEF;
577 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
580 libmap_disable = (bool)lm_init(libmap_override);
582 dbg("loading LD_PRELOAD libraries");
583 if (load_preload_objects() == -1)
585 preload_tail = obj_tail;
587 dbg("loading needed objects");
588 if (load_needed_objects(obj_main, 0) == -1)
591 /* Make a list of all objects loaded at startup. */
592 for (obj = obj_list; obj != NULL; obj = obj->next) {
593 objlist_push_tail(&list_main, obj);
597 dbg("checking for required versions");
598 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
603 if (ld_tracing) { /* We're done */
604 trace_loaded_objects(obj_main);
608 if (ld_resident) /* XXX clean this up! */
611 if (_getenv_ld("LD_DUMP_REL_PRE") != NULL) {
612 dump_relocations(obj_main);
616 /* setup TLS for main thread */
617 dbg("initializing initial thread local storage");
618 STAILQ_FOREACH(entry, &list_main, link) {
620 * Allocate all the initial objects out of the static TLS
621 * block even if they didn't ask for it.
623 allocate_tls_offset(entry->obj);
626 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
629 * Do not try to allocate the TLS here, let libc do it itself.
630 * (crt1 for the program will call _init_tls())
633 if (relocate_objects(obj_main,
634 ld_bind_now != NULL && *ld_bind_now != '\0',
635 &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
638 dbg("doing copy relocations");
639 if (do_copy_relocations(obj_main) == -1)
644 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
645 if (exec_sys_unregister(-1) < 0) {
646 dbg("exec_sys_unregister failed %d\n", errno);
649 dbg("exec_sys_unregister success\n");
653 if (_getenv_ld("LD_DUMP_REL_POST") != NULL) {
654 dump_relocations(obj_main);
658 dbg("initializing key program variables");
659 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
660 set_program_var("environ", env);
661 set_program_var("__elf_aux_vector", aux);
663 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
664 extern void resident_start(void);
666 if (exec_sys_register(resident_start) < 0) {
667 dbg("exec_sys_register failed %d\n", errno);
670 dbg("exec_sys_register success\n");
674 /* Make a list of init functions to call. */
675 objlist_init(&initlist);
676 initlist_add_objects(obj_list, preload_tail, &initlist);
678 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
680 map_stacks_exec(NULL);
682 dbg("resolving ifuncs");
683 if (resolve_objects_ifunc(obj_main,
684 ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
689 * Do NOT call the initlist here, give libc a chance to set up
690 * the initial TLS segment. crt1 will then call _rtld_call_init().
693 dbg("transferring control to program entry point = %p", obj_main->entry);
695 /* Return the exit procedure and the program entry point. */
696 *exit_proc = rtld_exit;
698 return (func_ptr_type) obj_main->entry;
702 * Call the initialization list for dynamically loaded libraries.
703 * (called from crt1.c).
706 _rtld_call_init(void)
708 RtldLockState lockstate;
711 if (!obj_main->note_present && obj_main->valid_hash_gnu) {
713 * The use of a linker script with a PHDRS directive that does not include
714 * PT_NOTE will block the crt_no_init note. In this case we'll look for the
715 * recently added GNU hash dynamic tag which gets built by default. It is
716 * extremely unlikely to find a pre-3.1 binary without a PT_NOTE header and
717 * a gnu hash tag. If gnu hash found, consider binary to use new crt code.
719 obj_main->crt_no_init = true;
720 dbg("Setting crt_no_init without presence of PT_NOTE header");
723 wlock_acquire(rtld_bind_lock, &lockstate);
724 if (obj_main->crt_no_init) {
725 preinitialize_main_object();
729 * Make sure we don't call the main program's init and fini functions
730 * for binaries linked with old crt1 which calls _init itself.
732 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
733 obj_main->init_array = obj_main->fini_array = (Elf_Addr)NULL;
735 objlist_call_init(&initlist, &lockstate);
736 objlist_clear(&initlist);
737 dbg("loading filtees");
738 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
739 if (ld_loadfltr || obj->z_loadfltr)
740 load_filtees(obj, 0, &lockstate);
742 lock_release(rtld_bind_lock, &lockstate);
746 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
751 ptr = (void *)make_function_pointer(def, obj);
752 target = ((Elf_Addr (*)(void))ptr)();
753 return ((void *)target);
757 _rtld_bind(Obj_Entry *obj, Elf_Size reloff, void *stack)
761 const Obj_Entry *defobj;
764 RtldLockState lockstate;
766 rlock_acquire(rtld_bind_lock, &lockstate);
767 if (sigsetjmp(lockstate.env, 0) != 0)
768 lock_upgrade(rtld_bind_lock, &lockstate);
770 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
772 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
774 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
775 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
779 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
780 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
782 target = (Elf_Addr)(defobj->relocbase + def->st_value);
784 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
785 defobj->strtab + def->st_name, basename(obj->path),
786 (void *)target, basename(defobj->path));
789 * If we have a function call tracing hook, and the
790 * hook would like to keep tracing this one function,
791 * prevent the relocation so we will wind up here
792 * the next time again.
794 * We don't want to functrace calls from the functracer
795 * to avoid recursive loops.
797 if (rtld_functrace != NULL && obj != rtld_functrace_obj) {
798 if (rtld_functrace(obj->path,
800 defobj->strtab + def->st_name,
802 lock_release(rtld_bind_lock, &lockstate);
808 * Write the new contents for the jmpslot. Note that depending on
809 * architecture, the value which we need to return back to the
810 * lazy binding trampoline may or may not be the target
811 * address. The value returned from reloc_jmpslot() is the value
812 * that the trampoline needs.
814 target = reloc_jmpslot(where, target, defobj, obj, rel);
815 lock_release(rtld_bind_lock, &lockstate);
820 * Error reporting function. Use it like printf. If formats the message
821 * into a buffer, and sets things up so that the next call to dlerror()
822 * will return the message.
825 _rtld_error(const char *fmt, ...)
827 static char buf[512];
831 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
837 * Return a dynamically-allocated copy of the current error message, if any.
842 return error_message == NULL ? NULL : xstrdup(error_message);
846 * Restore the current error message from a copy which was previously saved
847 * by errmsg_save(). The copy is freed.
850 errmsg_restore(char *saved_msg)
852 if (saved_msg == NULL)
853 error_message = NULL;
855 _rtld_error("%s", saved_msg);
861 basename(const char *name)
863 const char *p = strrchr(name, '/');
864 return p != NULL ? p + 1 : name;
867 static struct utsname uts;
870 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
880 subst_len = kw_len = 0;
884 if (subst_len == 0) {
885 subst_len = strlen(subst);
889 *res = xmalloc(PATH_MAX);
892 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
893 _rtld_error("Substitution of %s in %s cannot be performed",
895 if (may_free != NULL)
900 memcpy(res1, p, p1 - p);
902 memcpy(res1, subst, subst_len);
907 if (may_free != NULL)
910 *res = xstrdup(real);
914 if (may_free != NULL)
916 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
926 origin_subst(const char *real, const char *origin_path)
928 char *res1, *res2, *res3, *res4;
930 if (uts.sysname[0] == '\0') {
931 if (uname(&uts) != 0) {
932 _rtld_error("utsname failed: %d", errno);
936 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
937 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
938 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
939 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
947 const char *msg = dlerror();
951 rtld_fdputstr(STDERR_FILENO, msg);
952 rtld_fdputchar(STDERR_FILENO, '\n');
957 * Process a shared object's DYNAMIC section, and save the important
958 * information in its Obj_Entry structure.
961 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
962 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
965 Needed_Entry **needed_tail = &obj->needed;
966 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
967 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
968 int plttype = DT_REL;
974 obj->bind_now = false;
975 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
976 switch (dynp->d_tag) {
979 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
983 obj->relsize = dynp->d_un.d_val;
987 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
991 obj->pltrel = (const Elf_Rel *)
992 (obj->relocbase + dynp->d_un.d_ptr);
996 obj->pltrelsize = dynp->d_un.d_val;
1000 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
1004 obj->relasize = dynp->d_un.d_val;
1008 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
1012 plttype = dynp->d_un.d_val;
1013 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
1017 obj->symtab = (const Elf_Sym *)
1018 (obj->relocbase + dynp->d_un.d_ptr);
1022 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
1026 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
1030 obj->strsize = dynp->d_un.d_val;
1034 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1039 obj->verneednum = dynp->d_un.d_val;
1043 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1048 obj->verdefnum = dynp->d_un.d_val;
1052 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1058 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1059 (obj->relocbase + dynp->d_un.d_ptr);
1060 obj->nbuckets = hashtab[0];
1061 obj->nchains = hashtab[1];
1062 obj->buckets = hashtab + 2;
1063 obj->chains = obj->buckets + obj->nbuckets;
1064 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
1065 obj->buckets != NULL;
1071 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1072 (obj->relocbase + dynp->d_un.d_ptr);
1073 obj->nbuckets_gnu = hashtab[0];
1074 obj->symndx_gnu = hashtab[1];
1075 const Elf32_Word nmaskwords = hashtab[2];
1076 const int bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1077 /* Number of bitmask words is required to be power of 2 */
1078 const bool nmw_power2 = ((nmaskwords & (nmaskwords - 1)) == 0);
1079 obj->maskwords_bm_gnu = nmaskwords - 1;
1080 obj->shift2_gnu = hashtab[3];
1081 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1082 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1083 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1085 obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 &&
1086 obj->buckets_gnu != NULL;
1092 Needed_Entry *nep = NEW(Needed_Entry);
1093 nep->name = dynp->d_un.d_val;
1098 needed_tail = &nep->next;
1104 Needed_Entry *nep = NEW(Needed_Entry);
1105 nep->name = dynp->d_un.d_val;
1109 *needed_filtees_tail = nep;
1110 needed_filtees_tail = &nep->next;
1116 Needed_Entry *nep = NEW(Needed_Entry);
1117 nep->name = dynp->d_un.d_val;
1121 *needed_aux_filtees_tail = nep;
1122 needed_aux_filtees_tail = &nep->next;
1127 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1131 obj->textrel = true;
1135 obj->symbolic = true;
1140 * We have to wait until later to process this, because we
1141 * might not have gotten the address of the string table yet.
1151 *dyn_runpath = dynp;
1155 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1159 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1162 case DT_PREINIT_ARRAY:
1163 obj->preinit_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1167 obj->init_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1171 obj->fini_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1174 case DT_PREINIT_ARRAYSZ:
1175 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1178 case DT_INIT_ARRAYSZ:
1179 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1182 case DT_FINI_ARRAYSZ:
1183 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1187 /* XXX - not implemented yet */
1189 dbg("Filling in DT_DEBUG entry");
1190 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1194 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1195 obj->z_origin = true;
1196 if (dynp->d_un.d_val & DF_SYMBOLIC)
1197 obj->symbolic = true;
1198 if (dynp->d_un.d_val & DF_TEXTREL)
1199 obj->textrel = true;
1200 if (dynp->d_un.d_val & DF_BIND_NOW)
1201 obj->bind_now = true;
1202 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1207 if (dynp->d_un.d_val & DF_1_NOOPEN)
1208 obj->z_noopen = true;
1209 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1210 obj->z_origin = true;
1211 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1213 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1214 obj->bind_now = true;
1215 if (dynp->d_un.d_val & DF_1_NODELETE)
1216 obj->z_nodelete = true;
1217 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1218 obj->z_loadfltr = true;
1219 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1220 obj->z_nodeflib = true;
1225 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1232 obj->traced = false;
1234 if (plttype == DT_RELA) {
1235 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1237 obj->pltrelasize = obj->pltrelsize;
1238 obj->pltrelsize = 0;
1241 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1242 if (obj->valid_hash_sysv)
1243 obj->dynsymcount = obj->nchains;
1244 else if (obj->valid_hash_gnu) {
1245 obj->dynsymcount = 0;
1246 for (Elf32_Word bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1247 if (obj->buckets_gnu[bkt] == 0)
1249 const Elf32_Word *hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1252 while ((*hashval++ & 1u) == 0);
1254 obj->dynsymcount += obj->symndx_gnu;
1259 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1260 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1263 if (obj->z_origin && obj->origin_path == NULL) {
1264 obj->origin_path = xmalloc(PATH_MAX);
1265 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1269 if (dyn_runpath != NULL) {
1270 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1272 obj->runpath = origin_subst(obj->runpath, obj->origin_path);
1274 else if (dyn_rpath != NULL) {
1275 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1277 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1280 if (dyn_soname != NULL)
1281 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1285 digest_dynamic(Obj_Entry *obj, int early)
1287 const Elf_Dyn *dyn_rpath;
1288 const Elf_Dyn *dyn_soname;
1289 const Elf_Dyn *dyn_runpath;
1291 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1292 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1296 * Process a shared object's program header. This is used only for the
1297 * main program, when the kernel has already loaded the main program
1298 * into memory before calling the dynamic linker. It creates and
1299 * returns an Obj_Entry structure.
1302 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1305 const Elf_Phdr *phlimit = phdr + phnum;
1307 Elf_Addr note_start, note_end;
1311 for (ph = phdr; ph < phlimit; ph++) {
1312 if (ph->p_type != PT_PHDR)
1316 obj->phsize = ph->p_memsz;
1317 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1321 obj->stack_flags = PF_X | PF_R | PF_W;
1323 for (ph = phdr; ph < phlimit; ph++) {
1324 switch (ph->p_type) {
1327 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1331 if (nsegs == 0) { /* First load segment */
1332 obj->vaddrbase = trunc_page(ph->p_vaddr);
1333 obj->mapbase = obj->vaddrbase + obj->relocbase;
1334 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1336 } else { /* Last load segment */
1337 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1344 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1349 obj->tlssize = ph->p_memsz;
1350 obj->tlsalign = ph->p_align;
1351 obj->tlsinitsize = ph->p_filesz;
1352 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1356 obj->stack_flags = ph->p_flags;
1360 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1361 obj->relro_size = round_page(ph->p_memsz);
1365 obj->note_present = true;
1366 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1367 note_end = note_start + ph->p_filesz;
1368 digest_notes(obj, note_start, note_end);
1373 _rtld_error("%s: too few PT_LOAD segments", path);
1382 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1384 const Elf_Note *note;
1385 const char *note_name;
1388 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1389 note = (const Elf_Note *)((const char *)(note + 1) +
1390 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1391 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1392 if (note->n_namesz != sizeof(NOTE_VENDOR) ||
1393 note->n_descsz != sizeof(int32_t))
1395 if (note->n_type != ABI_NOTETYPE && note->n_type != CRT_NOINIT_NOTETYPE)
1397 note_name = (const char *)(note + 1);
1398 if (strncmp(NOTE_VENDOR, note_name, sizeof(NOTE_VENDOR)) != 0)
1400 switch (note->n_type) {
1402 /* DragonFly osrel note */
1403 p = (uintptr_t)(note + 1);
1404 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1405 obj->osrel = *(const int32_t *)(p);
1406 dbg("note osrel %d", obj->osrel);
1408 case CRT_NOINIT_NOTETYPE:
1409 /* DragonFly 'crt does not call init' note */
1410 obj->crt_no_init = true;
1411 dbg("note crt_no_init");
1418 dlcheck(void *handle)
1422 for (obj = obj_list; obj != NULL; obj = obj->next)
1423 if (obj == (Obj_Entry *) handle)
1426 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1427 _rtld_error("Invalid shared object handle %p", handle);
1434 * If the given object is already in the donelist, return true. Otherwise
1435 * add the object to the list and return false.
1438 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1442 for (i = 0; i < dlp->num_used; i++)
1443 if (dlp->objs[i] == obj)
1446 * Our donelist allocation should always be sufficient. But if
1447 * our threads locking isn't working properly, more shared objects
1448 * could have been loaded since we allocated the list. That should
1449 * never happen, but we'll handle it properly just in case it does.
1451 if (dlp->num_used < dlp->num_alloc)
1452 dlp->objs[dlp->num_used++] = obj;
1457 * Hash function for symbol table lookup. Don't even think about changing
1458 * this. It is specified by the System V ABI.
1461 elf_hash(const char *name)
1463 const unsigned char *p = (const unsigned char *) name;
1464 unsigned long h = 0;
1467 while (*p != '\0') {
1468 h = (h << 4) + *p++;
1469 if ((g = h & 0xf0000000) != 0)
1477 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1478 * unsigned in case it's implemented with a wider type.
1480 static uint_fast32_t
1481 gnu_hash (const char *s)
1483 uint_fast32_t h = 5381;
1484 for (unsigned char c = *s; c != '\0'; c = *++s)
1486 return h & 0xffffffff;
1490 * Find the library with the given name, and return its full pathname.
1491 * The returned string is dynamically allocated. Generates an error
1492 * message and returns NULL if the library cannot be found.
1494 * If the second argument is non-NULL, then it refers to an already-
1495 * loaded shared object, whose library search path will be searched.
1497 * The search order is:
1498 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1499 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1501 * DT_RUNPATH in the referencing file
1502 * ldconfig hints (if -z nodefaultlib, filter out /usr/lib from list)
1503 * /usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1505 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1508 find_library(const char *xname, const Obj_Entry *refobj)
1512 bool objgiven = (refobj != NULL);
1514 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1515 if (xname[0] != '/' && !trust) {
1516 _rtld_error("Absolute pathname required for shared object \"%s\"",
1520 if (objgiven && refobj->z_origin)
1521 return origin_subst(xname, refobj->origin_path);
1523 return xstrdup(xname);
1526 if (libmap_disable || !objgiven ||
1527 (name = lm_find(refobj->path, xname)) == NULL)
1528 name = (char *)xname;
1530 dbg(" Searching for \"%s\"", name);
1533 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1534 (objgiven && (refobj->runpath == NULL) && (refobj != obj_main) &&
1535 (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
1536 (pathname = search_library_path(name, ld_library_path)) != NULL ||
1538 (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
1539 (pathname = search_library_path(name, gethints(refobj))) != NULL ||
1540 (objgiven && !refobj->z_nodeflib &&
1541 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
1544 if(objgiven && refobj->path != NULL) {
1545 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1546 name, basename(refobj->path));
1548 _rtld_error("Shared object \"%s\" not found", name);
1554 * Given a symbol number in a referencing object, find the corresponding
1555 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1556 * no definition was found. Returns a pointer to the Obj_Entry of the
1557 * defining object via the reference parameter DEFOBJ_OUT.
1560 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1561 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1562 RtldLockState *lockstate)
1566 const Obj_Entry *defobj;
1572 * If we have already found this symbol, get the information from
1575 if (symnum >= refobj->dynsymcount)
1576 return NULL; /* Bad object */
1577 if (cache != NULL && cache[symnum].sym != NULL) {
1578 *defobj_out = cache[symnum].obj;
1579 return cache[symnum].sym;
1582 ref = refobj->symtab + symnum;
1583 name = refobj->strtab + ref->st_name;
1588 * We don't have to do a full scale lookup if the symbol is local.
1589 * We know it will bind to the instance in this load module; to
1590 * which we already have a pointer (ie ref). By not doing a lookup,
1591 * we not only improve performance, but it also avoids unresolvable
1592 * symbols when local symbols are not in the hash table.
1594 * This might occur for TLS module relocations, which simply use
1597 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1598 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1599 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1602 symlook_init(&req, name);
1604 req.ventry = fetch_ventry(refobj, symnum);
1605 req.lockstate = lockstate;
1606 res = symlook_default(&req, refobj);
1609 defobj = req.defobj_out;
1617 * If we found no definition and the reference is weak, treat the
1618 * symbol as having the value zero.
1620 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1626 *defobj_out = defobj;
1627 /* Record the information in the cache to avoid subsequent lookups. */
1628 if (cache != NULL) {
1629 cache[symnum].sym = def;
1630 cache[symnum].obj = defobj;
1633 if (refobj != &obj_rtld)
1634 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1640 * Return the search path from the ldconfig hints file, reading it if
1641 * necessary. Returns NULL if there are problems with the hints file,
1642 * or if the search path there is empty.
1643 * If DF_1_NODEFLIB flag set, omit STANDARD_LIBRARY_PATH directories
1646 gethints(const Obj_Entry *obj)
1650 if (hints == NULL) {
1652 struct elfhints_hdr hdr;
1655 /* Keep from trying again in case the hints file is bad. */
1658 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1660 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1661 hdr.magic != ELFHINTS_MAGIC ||
1666 p = xmalloc(hdr.dirlistlen + 1);
1667 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1668 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1673 /* skip stdlib if compiled with -z nodeflib */
1674 if ((obj != NULL) && obj->z_nodeflib) {
1675 struct fill_search_info_args sargs, hargs;
1676 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1677 struct dl_serpath *SLPpath, *hintpath;
1678 unsigned int SLPndx, hintndx, fndx, fcount;
1679 char *filtered_path;
1683 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1685 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1688 sargs.request = RTLD_DI_SERINFOSIZE;
1689 sargs.serinfo = &smeta;
1690 hargs.request = RTLD_DI_SERINFOSIZE;
1691 hargs.serinfo = &hmeta;
1693 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1694 path_enumerate(p, fill_search_info, &hargs);
1696 SLPinfo = malloc(smeta.dls_size);
1697 hintinfo = malloc(hmeta.dls_size);
1699 sargs.request = RTLD_DI_SERINFO;
1700 sargs.serinfo = SLPinfo;
1701 sargs.serpath = &SLPinfo->dls_serpath[0];
1702 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1704 hargs.request = RTLD_DI_SERINFO;
1705 hargs.serinfo = hintinfo;
1706 hargs.serpath = &hintinfo->dls_serpath[0];
1707 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1709 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1710 path_enumerate(p, fill_search_info, &hargs);
1714 filtered_path = xmalloc(hdr.dirlistlen + 1);
1715 hintpath = &hintinfo->dls_serpath[0];
1716 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++) {
1718 SLPpath = &SLPinfo->dls_serpath[0];
1719 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++) {
1720 if (strcmp(hintpath->dls_name, SLPpath->dls_name) == 0)
1726 filtered_path[fndx] = ':';
1730 flen = strlen(hintpath->dls_name);
1731 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1736 filtered_path[fndx] = '\0';
1741 hints = filtered_path;
1747 return hints[0] != '\0' ? hints : NULL;
1751 init_dag(Obj_Entry *root)
1753 const Needed_Entry *needed;
1754 const Objlist_Entry *elm;
1757 if (root->dag_inited)
1759 donelist_init(&donelist);
1761 /* Root object belongs to own DAG. */
1762 objlist_push_tail(&root->dldags, root);
1763 objlist_push_tail(&root->dagmembers, root);
1764 donelist_check(&donelist, root);
1767 * Add dependencies of root object to DAG in breadth order
1768 * by exploiting the fact that each new object get added
1769 * to the tail of the dagmembers list.
1771 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1772 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1773 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1775 objlist_push_tail(&needed->obj->dldags, root);
1776 objlist_push_tail(&root->dagmembers, needed->obj);
1779 root->dag_inited = true;
1783 * Initialize the dynamic linker. The argument is the address at which
1784 * the dynamic linker has been mapped into memory. The primary task of
1785 * this function is to relocate the dynamic linker.
1788 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1790 Obj_Entry objtmp; /* Temporary rtld object */
1791 const Elf_Dyn *dyn_rpath;
1792 const Elf_Dyn *dyn_soname;
1793 const Elf_Dyn *dyn_runpath;
1796 * Conjure up an Obj_Entry structure for the dynamic linker.
1798 * The "path" member can't be initialized yet because string constants
1799 * cannot yet be accessed. Below we will set it correctly.
1801 memset(&objtmp, 0, sizeof(objtmp));
1804 objtmp.mapbase = mapbase;
1806 objtmp.relocbase = mapbase;
1808 if (RTLD_IS_DYNAMIC()) {
1809 objtmp.dynamic = rtld_dynamic(&objtmp);
1810 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
1811 assert(objtmp.needed == NULL);
1812 assert(!objtmp.textrel);
1815 * Temporarily put the dynamic linker entry into the object list, so
1816 * that symbols can be found.
1819 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
1822 /* Initialize the object list. */
1823 obj_tail = &obj_list;
1825 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1826 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1828 #ifdef ENABLE_OSRELDATE
1829 if (aux_info[AT_OSRELDATE] != NULL)
1830 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1833 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
1835 /* Replace the path with a dynamically allocated copy. */
1836 obj_rtld.path = xstrdup(PATH_RTLD);
1838 r_debug.r_brk = r_debug_state;
1839 r_debug.r_state = RT_CONSISTENT;
1843 * Add the init functions from a needed object list (and its recursive
1844 * needed objects) to "list". This is not used directly; it is a helper
1845 * function for initlist_add_objects(). The write lock must be held
1846 * when this function is called.
1849 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1851 /* Recursively process the successor needed objects. */
1852 if (needed->next != NULL)
1853 initlist_add_neededs(needed->next, list);
1855 /* Process the current needed object. */
1856 if (needed->obj != NULL)
1857 initlist_add_objects(needed->obj, &needed->obj->next, list);
1861 * Scan all of the DAGs rooted in the range of objects from "obj" to
1862 * "tail" and add their init functions to "list". This recurses over
1863 * the DAGs and ensure the proper init ordering such that each object's
1864 * needed libraries are initialized before the object itself. At the
1865 * same time, this function adds the objects to the global finalization
1866 * list "list_fini" in the opposite order. The write lock must be
1867 * held when this function is called.
1870 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1873 if (obj->init_scanned || obj->init_done)
1875 obj->init_scanned = true;
1877 /* Recursively process the successor objects. */
1878 if (&obj->next != tail)
1879 initlist_add_objects(obj->next, tail, list);
1881 /* Recursively process the needed objects. */
1882 if (obj->needed != NULL)
1883 initlist_add_neededs(obj->needed, list);
1884 if (obj->needed_filtees != NULL)
1885 initlist_add_neededs(obj->needed_filtees, list);
1886 if (obj->needed_aux_filtees != NULL)
1887 initlist_add_neededs(obj->needed_aux_filtees, list);
1889 /* Add the object to the init list. */
1890 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
1891 obj->init_array != (Elf_Addr)NULL)
1892 objlist_push_tail(list, obj);
1894 /* Add the object to the global fini list in the reverse order. */
1895 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1896 && !obj->on_fini_list) {
1897 objlist_push_head(&list_fini, obj);
1898 obj->on_fini_list = true;
1903 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1907 is_exported(const Elf_Sym *def)
1910 const func_ptr_type *p;
1912 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1913 for (p = exports; *p != NULL; p++)
1914 if (FPTR_TARGET(*p) == value)
1920 free_needed_filtees(Needed_Entry *n)
1922 Needed_Entry *needed, *needed1;
1924 for (needed = n; needed != NULL; needed = needed->next) {
1925 if (needed->obj != NULL) {
1926 dlclose(needed->obj);
1930 for (needed = n; needed != NULL; needed = needed1) {
1931 needed1 = needed->next;
1937 unload_filtees(Obj_Entry *obj)
1940 free_needed_filtees(obj->needed_filtees);
1941 obj->needed_filtees = NULL;
1942 free_needed_filtees(obj->needed_aux_filtees);
1943 obj->needed_aux_filtees = NULL;
1944 obj->filtees_loaded = false;
1948 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
1949 RtldLockState *lockstate)
1952 for (; needed != NULL; needed = needed->next) {
1953 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
1954 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
1955 RTLD_LOCAL, lockstate);
1960 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
1963 lock_restart_for_upgrade(lockstate);
1964 if (!obj->filtees_loaded) {
1965 load_filtee1(obj, obj->needed_filtees, flags, lockstate);
1966 load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
1967 obj->filtees_loaded = true;
1972 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
1976 for (; needed != NULL; needed = needed->next) {
1977 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
1978 flags & ~RTLD_LO_NOLOAD);
1979 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
1981 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1982 dbg("obj %s nodelete", obj1->path);
1985 obj1->ref_nodel = true;
1992 * Given a shared object, traverse its list of needed objects, and load
1993 * each of them. Returns 0 on success. Generates an error message and
1994 * returns -1 on failure.
1997 load_needed_objects(Obj_Entry *first, int flags)
2001 for (obj = first; obj != NULL; obj = obj->next) {
2002 if (process_needed(obj, obj->needed, flags) == -1)
2009 load_preload_objects(void)
2011 char *p = ld_preload;
2012 static const char delim[] = " \t:;";
2017 p += strspn(p, delim);
2018 while (*p != '\0') {
2019 size_t len = strcspn(p, delim);
2027 obj = load_object(p, -1, NULL, 0);
2029 return -1; /* XXX - cleanup */
2032 p += strspn(p, delim);
2034 /* Check for the magic tracing function */
2035 symlook_init(&req, RTLD_FUNCTRACE);
2036 res = symlook_obj(&req, obj);
2038 rtld_functrace = (void *)(req.defobj_out->relocbase +
2039 req.sym_out->st_value);
2040 rtld_functrace_obj = req.defobj_out;
2043 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2048 printable_path(const char *path)
2051 return (path == NULL ? "<unknown>" : path);
2055 * Load a shared object into memory, if it is not already loaded. The
2056 * object may be specified by name or by user-supplied file descriptor
2057 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2060 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2064 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2072 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
2073 if (object_match_name(obj, name))
2077 path = find_library(name, refobj);
2084 * If we didn't find a match by pathname, or the name is not
2085 * supplied, open the file and check again by device and inode.
2086 * This avoids false mismatches caused by multiple links or ".."
2089 * To avoid a race, we open the file and use fstat() rather than
2094 if ((fd = open(path, O_RDONLY)) == -1) {
2095 _rtld_error("Cannot open \"%s\"", path);
2102 _rtld_error("Cannot dup fd");
2107 if (fstat(fd, &sb) == -1) {
2108 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2113 for (obj = obj_list->next; obj != NULL; obj = obj->next)
2114 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2116 if (obj != NULL && name != NULL) {
2117 object_add_name(obj, name);
2122 if (flags & RTLD_LO_NOLOAD) {
2128 /* First use of this object, so we must map it in */
2129 obj = do_load_object(fd, name, path, &sb, flags);
2138 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2145 * but first, make sure that environment variables haven't been
2146 * used to circumvent the noexec flag on a filesystem.
2148 if (dangerous_ld_env) {
2149 if (fstatfs(fd, &fs) != 0) {
2150 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2153 if (fs.f_flags & MNT_NOEXEC) {
2154 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
2158 dbg("loading \"%s\"", printable_path(path));
2159 obj = map_object(fd, printable_path(path), sbp);
2164 * If DT_SONAME is present in the object, digest_dynamic2 already
2165 * added it to the object names.
2168 object_add_name(obj, name);
2170 digest_dynamic(obj, 0);
2171 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2173 dbg("refusing to load non-loadable \"%s\"", obj->path);
2174 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2175 munmap(obj->mapbase, obj->mapsize);
2181 obj_tail = &obj->next;
2184 linkmap_add(obj); /* for GDB & dlinfo() */
2185 max_stack_flags |= obj->stack_flags;
2187 dbg(" %p .. %p: %s", obj->mapbase,
2188 obj->mapbase + obj->mapsize - 1, obj->path);
2190 dbg(" WARNING: %s has impure text", obj->path);
2191 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2198 obj_from_addr(const void *addr)
2202 for (obj = obj_list; obj != NULL; obj = obj->next) {
2203 if (addr < (void *) obj->mapbase)
2205 if (addr < (void *) (obj->mapbase + obj->mapsize))
2212 * Call the finalization functions for each of the objects in "list"
2213 * belonging to the DAG of "root" and referenced once. If NULL "root"
2214 * is specified, every finalization function will be called regardless
2215 * of the reference count and the list elements won't be freed. All of
2216 * the objects are expected to have non-NULL fini functions.
2219 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2223 Elf_Addr *fini_addr;
2226 assert(root == NULL || root->refcount == 1);
2229 * Preserve the current error message since a fini function might
2230 * call into the dynamic linker and overwrite it.
2232 saved_msg = errmsg_save();
2234 STAILQ_FOREACH(elm, list, link) {
2235 if (root != NULL && (elm->obj->refcount != 1 ||
2236 objlist_find(&root->dagmembers, elm->obj) == NULL))
2239 /* Remove object from fini list to prevent recursive invocation. */
2240 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2242 * XXX: If a dlopen() call references an object while the
2243 * fini function is in progress, we might end up trying to
2244 * unload the referenced object in dlclose() or the object
2245 * won't be unloaded although its fini function has been
2248 lock_release(rtld_bind_lock, lockstate);
2251 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. When this
2252 * happens, DT_FINI_ARRAY is processed first, and it is also processed
2253 * backwards. It is possible to encounter DT_FINI_ARRAY elements with
2254 * values of 0 or 1, but they need to be ignored.
2256 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2257 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2258 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
2259 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2260 dbg("calling fini array function for %s at %p",
2261 elm->obj->path, (void *)fini_addr[index]);
2262 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2263 (void *)fini_addr[index], 0, 0, elm->obj->path);
2264 call_initfini_pointer(elm->obj, fini_addr[index]);
2268 if (elm->obj->fini != (Elf_Addr)NULL) {
2269 dbg("calling fini function for %s at %p", elm->obj->path,
2270 (void *)elm->obj->fini);
2271 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2272 0, 0, elm->obj->path);
2273 call_initfini_pointer(elm->obj, elm->obj->fini);
2275 wlock_acquire(rtld_bind_lock, lockstate);
2276 /* No need to free anything if process is going down. */
2280 * We must restart the list traversal after every fini call
2281 * because a dlclose() call from the fini function or from
2282 * another thread might have modified the reference counts.
2286 } while (elm != NULL);
2287 errmsg_restore(saved_msg);
2291 * If the main program is defined with a .preinit_array section, call
2292 * each function in order. This must occur before the initialization
2293 * of any shared object or the main program.
2296 preinitialize_main_object (void)
2298 Elf_Addr *preinit_addr;
2301 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2302 if (preinit_addr == NULL)
2305 for (index = 0; index < obj_main->preinit_array_num; index++) {
2306 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2307 dbg("calling preinit function for %s at %p", obj_main->path,
2308 (void *)preinit_addr[index]);
2309 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2310 0, 0, obj_main->path);
2311 call_init_pointer(obj_main, preinit_addr[index]);
2317 * Call the initialization functions for each of the objects in
2318 * "list". All of the objects are expected to have non-NULL init
2322 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2327 Elf_Addr *init_addr;
2331 * Clean init_scanned flag so that objects can be rechecked and
2332 * possibly initialized earlier if any of vectors called below
2333 * cause the change by using dlopen.
2335 for (obj = obj_list; obj != NULL; obj = obj->next)
2336 obj->init_scanned = false;
2339 * Preserve the current error message since an init function might
2340 * call into the dynamic linker and overwrite it.
2342 saved_msg = errmsg_save();
2343 STAILQ_FOREACH(elm, list, link) {
2344 if (elm->obj->init_done) /* Initialized early. */
2348 * Race: other thread might try to use this object before current
2349 * one completes the initilization. Not much can be done here
2350 * without better locking.
2352 elm->obj->init_done = true;
2353 lock_release(rtld_bind_lock, lockstate);
2356 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. When
2357 * this happens, DT_INIT is processed first. It is possible to
2358 * encounter DT_INIT_ARRAY elements with values of 0 or 1, but they
2359 * need to be ignored.
2361 if (elm->obj->init != (Elf_Addr)NULL) {
2362 dbg("calling init function for %s at %p", elm->obj->path,
2363 (void *)elm->obj->init);
2364 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2365 0, 0, elm->obj->path);
2366 call_initfini_pointer(elm->obj, elm->obj->init);
2368 init_addr = (Elf_Addr *)elm->obj->init_array;
2369 if (init_addr != NULL) {
2370 for (index = 0; index < elm->obj->init_array_num; index++) {
2371 if (init_addr[index] != 0 && init_addr[index] != 1) {
2372 dbg("calling init array function for %s at %p", elm->obj->path,
2373 (void *)init_addr[index]);
2374 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2375 (void *)init_addr[index], 0, 0, elm->obj->path);
2376 call_init_pointer(elm->obj, init_addr[index]);
2380 wlock_acquire(rtld_bind_lock, lockstate);
2382 errmsg_restore(saved_msg);
2386 objlist_clear(Objlist *list)
2390 while (!STAILQ_EMPTY(list)) {
2391 elm = STAILQ_FIRST(list);
2392 STAILQ_REMOVE_HEAD(list, link);
2397 static Objlist_Entry *
2398 objlist_find(Objlist *list, const Obj_Entry *obj)
2402 STAILQ_FOREACH(elm, list, link)
2403 if (elm->obj == obj)
2409 objlist_init(Objlist *list)
2415 objlist_push_head(Objlist *list, Obj_Entry *obj)
2419 elm = NEW(Objlist_Entry);
2421 STAILQ_INSERT_HEAD(list, elm, link);
2425 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2429 elm = NEW(Objlist_Entry);
2431 STAILQ_INSERT_TAIL(list, elm, link);
2435 objlist_remove(Objlist *list, Obj_Entry *obj)
2439 if ((elm = objlist_find(list, obj)) != NULL) {
2440 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2446 * Relocate newly-loaded shared objects. The argument is a pointer to
2447 * the Obj_Entry for the first such object. All objects from the first
2448 * to the end of the list of objects are relocated. Returns 0 on success,
2452 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2453 int flags, RtldLockState *lockstate)
2457 for (obj = first; obj != NULL; obj = obj->next) {
2460 obj->relocated = true;
2462 dbg("relocating \"%s\"", obj->path);
2464 if (obj->symtab == NULL || obj->strtab == NULL ||
2465 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2466 _rtld_error("%s: Shared object has no run-time symbol table",
2472 /* There are relocations to the write-protected text segment. */
2473 if (mprotect(obj->mapbase, obj->textsize,
2474 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2475 _rtld_error("%s: Cannot write-enable text segment: %s",
2476 obj->path, rtld_strerror(errno));
2481 /* Process the non-PLT relocations. */
2482 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2486 * Reprotect the text segment. Make sure it is included in the
2487 * core dump since we modified it. This unfortunately causes the
2488 * entire text segment to core-out but we don't have much of a
2489 * choice. We could try to only reenable core dumps on pages
2490 * in which relocations occured but that is likely most of the text
2491 * pages anyway, and even that would not work because the rest of
2492 * the text pages would wind up as a read-only OBJT_DEFAULT object
2493 * (created due to our modifications) backed by the original OBJT_VNODE
2494 * object, and the ELF coredump code is currently only able to dump
2495 * vnode records for pure vnode-backed mappings, not vnode backings
2496 * to memory objects.
2499 madvise(obj->mapbase, obj->textsize, MADV_CORE);
2500 if (mprotect(obj->mapbase, obj->textsize,
2501 PROT_READ|PROT_EXEC) == -1) {
2502 _rtld_error("%s: Cannot write-protect text segment: %s",
2503 obj->path, rtld_strerror(errno));
2509 /* Set the special PLT or GOT entries. */
2512 /* Process the PLT relocations. */
2513 if (reloc_plt(obj) == -1)
2515 /* Relocate the jump slots if we are doing immediate binding. */
2516 if (obj->bind_now || bind_now)
2517 if (reloc_jmpslots(obj, flags, lockstate) == -1)
2521 * Set up the magic number and version in the Obj_Entry. These
2522 * were checked in the crt1.o from the original ElfKit, so we
2523 * set them for backward compatibility.
2525 obj->magic = RTLD_MAGIC;
2526 obj->version = RTLD_VERSION;
2529 * Set relocated data to read-only status if protection specified
2532 if (obj->relro_size) {
2533 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
2534 _rtld_error("%s: Cannot enforce relro relocation: %s",
2535 obj->path, rtld_strerror(errno));
2545 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2546 * referencing STT_GNU_IFUNC symbols is postponed till the other
2547 * relocations are done. The indirect functions specified as
2548 * ifunc are allowed to call other symbols, so we need to have
2549 * objects relocated before asking for resolution from indirects.
2551 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2552 * instead of the usual lazy handling of PLT slots. It is
2553 * consistent with how GNU does it.
2556 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2557 RtldLockState *lockstate)
2559 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2561 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2562 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2568 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2569 RtldLockState *lockstate)
2573 for (obj = first; obj != NULL; obj = obj->next) {
2574 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2581 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2582 RtldLockState *lockstate)
2586 STAILQ_FOREACH(elm, list, link) {
2587 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2595 * Cleanup procedure. It will be called (by the atexit mechanism) just
2596 * before the process exits.
2601 RtldLockState lockstate;
2603 wlock_acquire(rtld_bind_lock, &lockstate);
2605 objlist_call_fini(&list_fini, NULL, &lockstate);
2606 /* No need to remove the items from the list, since we are exiting. */
2607 if (!libmap_disable)
2609 lock_release(rtld_bind_lock, &lockstate);
2613 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2618 path += strspn(path, ":;");
2619 while (*path != '\0') {
2623 len = strcspn(path, ":;");
2624 res = callback(path, len, arg);
2630 path += strspn(path, ":;");
2636 struct try_library_args {
2644 try_library_path(const char *dir, size_t dirlen, void *param)
2646 struct try_library_args *arg;
2649 if (*dir == '/' || trust) {
2652 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2655 pathname = arg->buffer;
2656 strncpy(pathname, dir, dirlen);
2657 pathname[dirlen] = '/';
2658 strcpy(pathname + dirlen + 1, arg->name);
2660 dbg(" Trying \"%s\"", pathname);
2661 if (access(pathname, F_OK) == 0) { /* We found it */
2662 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2663 strcpy(pathname, arg->buffer);
2671 search_library_path(const char *name, const char *path)
2674 struct try_library_args arg;
2680 arg.namelen = strlen(name);
2681 arg.buffer = xmalloc(PATH_MAX);
2682 arg.buflen = PATH_MAX;
2684 p = path_enumerate(path, try_library_path, &arg);
2692 dlclose(void *handle)
2695 RtldLockState lockstate;
2697 wlock_acquire(rtld_bind_lock, &lockstate);
2698 root = dlcheck(handle);
2700 lock_release(rtld_bind_lock, &lockstate);
2703 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2706 /* Unreference the object and its dependencies. */
2707 root->dl_refcount--;
2709 if (root->refcount == 1) {
2711 * The object will be no longer referenced, so we must unload it.
2712 * First, call the fini functions.
2714 objlist_call_fini(&list_fini, root, &lockstate);
2718 /* Finish cleaning up the newly-unreferenced objects. */
2719 GDB_STATE(RT_DELETE,&root->linkmap);
2720 unload_object(root);
2721 GDB_STATE(RT_CONSISTENT,NULL);
2725 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2726 lock_release(rtld_bind_lock, &lockstate);
2733 char *msg = error_message;
2734 error_message = NULL;
2739 dlopen(const char *name, int mode)
2742 return (rtld_dlopen(name, -1, mode));
2746 fdlopen(int fd, int mode)
2749 return (rtld_dlopen(NULL, fd, mode));
2753 rtld_dlopen(const char *name, int fd, int mode)
2755 RtldLockState lockstate;
2758 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2759 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2760 if (ld_tracing != NULL) {
2761 rlock_acquire(rtld_bind_lock, &lockstate);
2762 if (sigsetjmp(lockstate.env, 0) != 0)
2763 lock_upgrade(rtld_bind_lock, &lockstate);
2764 environ = (char **)*get_program_var_addr("environ", &lockstate);
2765 lock_release(rtld_bind_lock, &lockstate);
2767 lo_flags = RTLD_LO_DLOPEN;
2768 if (mode & RTLD_NODELETE)
2769 lo_flags |= RTLD_LO_NODELETE;
2770 if (mode & RTLD_NOLOAD)
2771 lo_flags |= RTLD_LO_NOLOAD;
2772 if (ld_tracing != NULL)
2773 lo_flags |= RTLD_LO_TRACE;
2775 return (dlopen_object(name, fd, obj_main, lo_flags,
2776 mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
2780 dlopen_cleanup(Obj_Entry *obj)
2785 if (obj->refcount == 0)
2790 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
2791 int mode, RtldLockState *lockstate)
2793 Obj_Entry **old_obj_tail;
2796 RtldLockState mlockstate;
2799 objlist_init(&initlist);
2801 if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
2802 wlock_acquire(rtld_bind_lock, &mlockstate);
2803 lockstate = &mlockstate;
2805 GDB_STATE(RT_ADD,NULL);
2807 old_obj_tail = obj_tail;
2809 if (name == NULL && fd == -1) {
2813 obj = load_object(name, fd, refobj, lo_flags);
2818 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2819 objlist_push_tail(&list_global, obj);
2820 if (*old_obj_tail != NULL) { /* We loaded something new. */
2821 assert(*old_obj_tail == obj);
2822 result = load_needed_objects(obj,
2823 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
2827 result = rtld_verify_versions(&obj->dagmembers);
2828 if (result != -1 && ld_tracing)
2830 if (result == -1 || (relocate_objects(obj,
2831 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
2832 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
2833 lockstate)) == -1) {
2834 dlopen_cleanup(obj);
2836 } else if (lo_flags & RTLD_LO_EARLY) {
2838 * Do not call the init functions for early loaded
2839 * filtees. The image is still not initialized enough
2842 * Our object is found by the global object list and
2843 * will be ordered among all init calls done right
2844 * before transferring control to main.
2847 /* Make list of init functions to call. */
2848 initlist_add_objects(obj, &obj->next, &initlist);
2853 * Bump the reference counts for objects on this DAG. If
2854 * this is the first dlopen() call for the object that was
2855 * already loaded as a dependency, initialize the dag
2861 if ((lo_flags & RTLD_LO_TRACE) != 0)
2864 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
2865 obj->z_nodelete) && !obj->ref_nodel) {
2866 dbg("obj %s nodelete", obj->path);
2868 obj->z_nodelete = obj->ref_nodel = true;
2872 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2874 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2876 if (!(lo_flags & RTLD_LO_EARLY)) {
2877 map_stacks_exec(lockstate);
2880 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
2881 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
2883 objlist_clear(&initlist);
2884 dlopen_cleanup(obj);
2885 if (lockstate == &mlockstate)
2886 lock_release(rtld_bind_lock, lockstate);
2890 if (!(lo_flags & RTLD_LO_EARLY)) {
2891 /* Call the init functions. */
2892 objlist_call_init(&initlist, lockstate);
2894 objlist_clear(&initlist);
2895 if (lockstate == &mlockstate)
2896 lock_release(rtld_bind_lock, lockstate);
2899 trace_loaded_objects(obj);
2900 if (lockstate == &mlockstate)
2901 lock_release(rtld_bind_lock, lockstate);
2906 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2910 const Obj_Entry *obj, *defobj;
2913 RtldLockState lockstate;
2918 symlook_init(&req, name);
2920 req.flags = flags | SYMLOOK_IN_PLT;
2921 req.lockstate = &lockstate;
2923 rlock_acquire(rtld_bind_lock, &lockstate);
2924 if (sigsetjmp(lockstate.env, 0) != 0)
2925 lock_upgrade(rtld_bind_lock, &lockstate);
2926 if (handle == NULL || handle == RTLD_NEXT ||
2927 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2929 if ((obj = obj_from_addr(retaddr)) == NULL) {
2930 _rtld_error("Cannot determine caller's shared object");
2931 lock_release(rtld_bind_lock, &lockstate);
2934 if (handle == NULL) { /* Just the caller's shared object. */
2935 res = symlook_obj(&req, obj);
2938 defobj = req.defobj_out;
2940 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2941 handle == RTLD_SELF) { /* ... caller included */
2942 if (handle == RTLD_NEXT)
2944 for (; obj != NULL; obj = obj->next) {
2945 res = symlook_obj(&req, obj);
2948 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
2950 defobj = req.defobj_out;
2951 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2957 * Search the dynamic linker itself, and possibly resolve the
2958 * symbol from there. This is how the application links to
2959 * dynamic linker services such as dlopen.
2961 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2962 res = symlook_obj(&req, &obj_rtld);
2963 if (res == 0 && is_exported(req.sym_out)) {
2965 defobj = req.defobj_out;
2969 assert(handle == RTLD_DEFAULT);
2970 res = symlook_default(&req, obj);
2972 defobj = req.defobj_out;
2977 if ((obj = dlcheck(handle)) == NULL) {
2978 lock_release(rtld_bind_lock, &lockstate);
2982 donelist_init(&donelist);
2983 if (obj->mainprog) {
2984 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
2985 res = symlook_global(&req, &donelist);
2988 defobj = req.defobj_out;
2991 * Search the dynamic linker itself, and possibly resolve the
2992 * symbol from there. This is how the application links to
2993 * dynamic linker services such as dlopen.
2995 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2996 res = symlook_obj(&req, &obj_rtld);
2999 defobj = req.defobj_out;
3004 /* Search the whole DAG rooted at the given object. */
3005 res = symlook_list(&req, &obj->dagmembers, &donelist);
3008 defobj = req.defobj_out;
3014 lock_release(rtld_bind_lock, &lockstate);
3017 * The value required by the caller is derived from the value
3018 * of the symbol. For the ia64 architecture, we need to
3019 * construct a function descriptor which the caller can use to
3020 * call the function with the right 'gp' value. For other
3021 * architectures and for non-functions, the value is simply
3022 * the relocated value of the symbol.
3024 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3025 return (make_function_pointer(def, defobj));
3026 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3027 return (rtld_resolve_ifunc(defobj, def));
3028 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3030 ti.ti_module = defobj->tlsindex;
3031 ti.ti_offset = def->st_value;
3032 return (__tls_get_addr(&ti));
3034 return (defobj->relocbase + def->st_value);
3037 _rtld_error("Undefined symbol \"%s\"", name);
3038 lock_release(rtld_bind_lock, &lockstate);
3043 dlsym(void *handle, const char *name)
3045 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3050 dlfunc(void *handle, const char *name)
3057 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3063 dlvsym(void *handle, const char *name, const char *version)
3067 ventry.name = version;
3069 ventry.hash = elf_hash(version);
3071 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3076 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3078 const Obj_Entry *obj;
3079 RtldLockState lockstate;
3081 rlock_acquire(rtld_bind_lock, &lockstate);
3082 obj = obj_from_addr(addr);
3084 _rtld_error("No shared object contains address");
3085 lock_release(rtld_bind_lock, &lockstate);
3088 rtld_fill_dl_phdr_info(obj, phdr_info);
3089 lock_release(rtld_bind_lock, &lockstate);
3094 dladdr(const void *addr, Dl_info *info)
3096 const Obj_Entry *obj;
3099 unsigned long symoffset;
3100 RtldLockState lockstate;
3102 rlock_acquire(rtld_bind_lock, &lockstate);
3103 obj = obj_from_addr(addr);
3105 _rtld_error("No shared object contains address");
3106 lock_release(rtld_bind_lock, &lockstate);
3109 info->dli_fname = obj->path;
3110 info->dli_fbase = obj->mapbase;
3111 info->dli_saddr = NULL;
3112 info->dli_sname = NULL;
3115 * Walk the symbol list looking for the symbol whose address is
3116 * closest to the address sent in.
3118 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3119 def = obj->symtab + symoffset;
3122 * For skip the symbol if st_shndx is either SHN_UNDEF or
3125 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3129 * If the symbol is greater than the specified address, or if it
3130 * is further away from addr than the current nearest symbol,
3133 symbol_addr = obj->relocbase + def->st_value;
3134 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3137 /* Update our idea of the nearest symbol. */
3138 info->dli_sname = obj->strtab + def->st_name;
3139 info->dli_saddr = symbol_addr;
3142 if (info->dli_saddr == addr)
3145 lock_release(rtld_bind_lock, &lockstate);
3150 dlinfo(void *handle, int request, void *p)
3152 const Obj_Entry *obj;
3153 RtldLockState lockstate;
3156 rlock_acquire(rtld_bind_lock, &lockstate);
3158 if (handle == NULL || handle == RTLD_SELF) {
3161 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3162 if ((obj = obj_from_addr(retaddr)) == NULL)
3163 _rtld_error("Cannot determine caller's shared object");
3165 obj = dlcheck(handle);
3168 lock_release(rtld_bind_lock, &lockstate);
3174 case RTLD_DI_LINKMAP:
3175 *((struct link_map const **)p) = &obj->linkmap;
3177 case RTLD_DI_ORIGIN:
3178 error = rtld_dirname(obj->path, p);
3181 case RTLD_DI_SERINFOSIZE:
3182 case RTLD_DI_SERINFO:
3183 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3187 _rtld_error("Invalid request %d passed to dlinfo()", request);
3191 lock_release(rtld_bind_lock, &lockstate);
3197 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3200 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3201 phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ?
3202 STAILQ_FIRST(&obj->names)->name : obj->path;
3203 phdr_info->dlpi_phdr = obj->phdr;
3204 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3205 phdr_info->dlpi_tls_modid = obj->tlsindex;
3206 phdr_info->dlpi_tls_data = obj->tlsinit;
3207 phdr_info->dlpi_adds = obj_loads;
3208 phdr_info->dlpi_subs = obj_loads - obj_count;
3212 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3214 struct dl_phdr_info phdr_info;
3215 const Obj_Entry *obj;
3216 RtldLockState bind_lockstate, phdr_lockstate;
3219 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3220 rlock_acquire(rtld_bind_lock, &bind_lockstate);
3224 for (obj = obj_list; obj != NULL; obj = obj->next) {
3225 rtld_fill_dl_phdr_info(obj, &phdr_info);
3226 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
3230 lock_release(rtld_bind_lock, &bind_lockstate);
3231 lock_release(rtld_phdr_lock, &phdr_lockstate);
3237 fill_search_info(const char *dir, size_t dirlen, void *param)
3239 struct fill_search_info_args *arg;
3243 if (arg->request == RTLD_DI_SERINFOSIZE) {
3244 arg->serinfo->dls_cnt ++;
3245 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3247 struct dl_serpath *s_entry;
3249 s_entry = arg->serpath;
3250 s_entry->dls_name = arg->strspace;
3251 s_entry->dls_flags = arg->flags;
3253 strncpy(arg->strspace, dir, dirlen);
3254 arg->strspace[dirlen] = '\0';
3256 arg->strspace += dirlen + 1;
3264 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3266 struct dl_serinfo _info;
3267 struct fill_search_info_args args;
3269 args.request = RTLD_DI_SERINFOSIZE;
3270 args.serinfo = &_info;
3272 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3275 path_enumerate(obj->rpath, fill_search_info, &args);
3276 path_enumerate(ld_library_path, fill_search_info, &args);
3277 path_enumerate(obj->runpath, fill_search_info, &args);
3278 path_enumerate(gethints(obj), fill_search_info, &args);
3279 if (!obj->z_nodeflib)
3280 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
3283 if (request == RTLD_DI_SERINFOSIZE) {
3284 info->dls_size = _info.dls_size;
3285 info->dls_cnt = _info.dls_cnt;
3289 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3290 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3294 args.request = RTLD_DI_SERINFO;
3295 args.serinfo = info;
3296 args.serpath = &info->dls_serpath[0];
3297 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3299 args.flags = LA_SER_RUNPATH;
3300 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3303 args.flags = LA_SER_LIBPATH;
3304 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3307 args.flags = LA_SER_RUNPATH;
3308 if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
3311 args.flags = LA_SER_CONFIG;
3312 if (path_enumerate(gethints(obj), fill_search_info, &args) != NULL)
3315 args.flags = LA_SER_DEFAULT;
3316 if (!obj->z_nodeflib &&
3317 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3323 rtld_dirname(const char *path, char *bname)
3327 /* Empty or NULL string gets treated as "." */
3328 if (path == NULL || *path == '\0') {
3334 /* Strip trailing slashes */
3335 endp = path + strlen(path) - 1;
3336 while (endp > path && *endp == '/')
3339 /* Find the start of the dir */
3340 while (endp > path && *endp != '/')
3343 /* Either the dir is "/" or there are no slashes */
3345 bname[0] = *endp == '/' ? '/' : '.';
3351 } while (endp > path && *endp == '/');
3354 if (endp - path + 2 > PATH_MAX)
3356 _rtld_error("Filename is too long: %s", path);
3360 strncpy(bname, path, endp - path + 1);
3361 bname[endp - path + 1] = '\0';
3366 rtld_dirname_abs(const char *path, char *base)
3368 char base_rel[PATH_MAX];
3370 if (rtld_dirname(path, base) == -1)
3374 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
3375 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
3376 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
3378 strcpy(base, base_rel);
3383 linkmap_add(Obj_Entry *obj)
3385 struct link_map *l = &obj->linkmap;
3386 struct link_map *prev;
3388 obj->linkmap.l_name = obj->path;
3389 obj->linkmap.l_addr = obj->mapbase;
3390 obj->linkmap.l_ld = obj->dynamic;
3392 /* GDB needs load offset on MIPS to use the symbols */
3393 obj->linkmap.l_offs = obj->relocbase;
3396 if (r_debug.r_map == NULL) {
3402 * Scan to the end of the list, but not past the entry for the
3403 * dynamic linker, which we want to keep at the very end.
3405 for (prev = r_debug.r_map;
3406 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3407 prev = prev->l_next)
3410 /* Link in the new entry. */
3412 l->l_next = prev->l_next;
3413 if (l->l_next != NULL)
3414 l->l_next->l_prev = l;
3419 linkmap_delete(Obj_Entry *obj)
3421 struct link_map *l = &obj->linkmap;
3423 if (l->l_prev == NULL) {
3424 if ((r_debug.r_map = l->l_next) != NULL)
3425 l->l_next->l_prev = NULL;
3429 if ((l->l_prev->l_next = l->l_next) != NULL)
3430 l->l_next->l_prev = l->l_prev;
3434 * Function for the debugger to set a breakpoint on to gain control.
3436 * The two parameters allow the debugger to easily find and determine
3437 * what the runtime loader is doing and to whom it is doing it.
3439 * When the loadhook trap is hit (r_debug_state, set at program
3440 * initialization), the arguments can be found on the stack:
3442 * +8 struct link_map *m
3443 * +4 struct r_debug *rd
3447 r_debug_state(struct r_debug* rd, struct link_map *m)
3450 * The following is a hack to force the compiler to emit calls to
3451 * this function, even when optimizing. If the function is empty,
3452 * the compiler is not obliged to emit any code for calls to it,
3453 * even when marked __noinline. However, gdb depends on those
3456 __asm __volatile("" : : : "memory");
3460 * Get address of the pointer variable in the main program.
3461 * Prefer non-weak symbol over the weak one.
3463 static const void **
3464 get_program_var_addr(const char *name, RtldLockState *lockstate)
3469 symlook_init(&req, name);
3470 req.lockstate = lockstate;
3471 donelist_init(&donelist);
3472 if (symlook_global(&req, &donelist) != 0)
3474 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3475 return ((const void **)make_function_pointer(req.sym_out,
3477 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3478 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3480 return ((const void **)(req.defobj_out->relocbase + req.sym_out->st_value));
3484 * Set a pointer variable in the main program to the given value. This
3485 * is used to set key variables such as "environ" before any of the
3486 * init functions are called.
3489 set_program_var(const char *name, const void *value)
3493 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3494 dbg("\"%s\": *%p <-- %p", name, addr, value);
3500 * Search the global objects, including dependencies and main object,
3501 * for the given symbol.
3504 symlook_global(SymLook *req, DoneList *donelist)
3507 const Objlist_Entry *elm;
3510 symlook_init_from_req(&req1, req);
3512 /* Search all objects loaded at program start up. */
3513 if (req->defobj_out == NULL ||
3514 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3515 res = symlook_list(&req1, &list_main, donelist);
3516 if (res == 0 && (req->defobj_out == NULL ||
3517 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3518 req->sym_out = req1.sym_out;
3519 req->defobj_out = req1.defobj_out;
3520 assert(req->defobj_out != NULL);
3524 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3525 STAILQ_FOREACH(elm, &list_global, link) {
3526 if (req->defobj_out != NULL &&
3527 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3529 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3530 if (res == 0 && (req->defobj_out == NULL ||
3531 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3532 req->sym_out = req1.sym_out;
3533 req->defobj_out = req1.defobj_out;
3534 assert(req->defobj_out != NULL);
3538 return (req->sym_out != NULL ? 0 : ESRCH);
3542 * This is a special version of getenv which is far more efficient
3543 * at finding LD_ environment vars.
3547 _getenv_ld(const char *id)
3551 int idlen = strlen(id);
3553 if (ld_index == LD_ARY_CACHE)
3555 if (ld_index == 0) {
3556 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
3557 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
3564 for (i = ld_index - 1; i >= 0; --i) {
3565 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
3566 return(ld_ary[i] + idlen + 1);
3572 * Given a symbol name in a referencing object, find the corresponding
3573 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3574 * no definition was found. Returns a pointer to the Obj_Entry of the
3575 * defining object via the reference parameter DEFOBJ_OUT.
3578 symlook_default(SymLook *req, const Obj_Entry *refobj)
3581 const Objlist_Entry *elm;
3585 donelist_init(&donelist);
3586 symlook_init_from_req(&req1, req);
3588 /* Look first in the referencing object if linked symbolically. */
3589 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3590 res = symlook_obj(&req1, refobj);
3592 req->sym_out = req1.sym_out;
3593 req->defobj_out = req1.defobj_out;
3594 assert(req->defobj_out != NULL);
3598 symlook_global(req, &donelist);
3600 /* Search all dlopened DAGs containing the referencing object. */
3601 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3602 if (req->sym_out != NULL &&
3603 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3605 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3606 if (res == 0 && (req->sym_out == NULL ||
3607 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3608 req->sym_out = req1.sym_out;
3609 req->defobj_out = req1.defobj_out;
3610 assert(req->defobj_out != NULL);
3615 * Search the dynamic linker itself, and possibly resolve the
3616 * symbol from there. This is how the application links to
3617 * dynamic linker services such as dlopen. Only the values listed
3618 * in the "exports" array can be resolved from the dynamic linker.
3620 if (req->sym_out == NULL ||
3621 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3622 res = symlook_obj(&req1, &obj_rtld);
3623 if (res == 0 && is_exported(req1.sym_out)) {
3624 req->sym_out = req1.sym_out;
3625 req->defobj_out = req1.defobj_out;
3626 assert(req->defobj_out != NULL);
3630 return (req->sym_out != NULL ? 0 : ESRCH);
3634 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3637 const Obj_Entry *defobj;
3638 const Objlist_Entry *elm;
3644 STAILQ_FOREACH(elm, objlist, link) {
3645 if (donelist_check(dlp, elm->obj))
3647 symlook_init_from_req(&req1, req);
3648 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3649 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3651 defobj = req1.defobj_out;
3652 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3659 req->defobj_out = defobj;
3666 * Search the chain of DAGS cointed to by the given Needed_Entry
3667 * for a symbol of the given name. Each DAG is scanned completely
3668 * before advancing to the next one. Returns a pointer to the symbol,
3669 * or NULL if no definition was found.
3672 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3675 const Needed_Entry *n;
3676 const Obj_Entry *defobj;
3682 symlook_init_from_req(&req1, req);
3683 for (n = needed; n != NULL; n = n->next) {
3684 if (n->obj == NULL ||
3685 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3687 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3689 defobj = req1.defobj_out;
3690 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3696 req->defobj_out = defobj;
3703 * Search the symbol table of a single shared object for a symbol of
3704 * the given name and version, if requested. Returns a pointer to the
3705 * symbol, or NULL if no definition was found. If the object is
3706 * filter, return filtered symbol from filtee.
3708 * The symbol's hash value is passed in for efficiency reasons; that
3709 * eliminates many recomputations of the hash value.
3712 symlook_obj(SymLook *req, const Obj_Entry *obj)
3716 int flags, res, mres;
3719 * There is at least one valid hash at this point, and we prefer to use
3720 * the faster GNU version if available.
3722 if (obj->valid_hash_gnu)
3723 mres = symlook_obj2(req, obj);
3725 mres = symlook_obj1(req, obj);
3728 if (obj->needed_filtees != NULL) {
3729 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3730 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3731 donelist_init(&donelist);
3732 symlook_init_from_req(&req1, req);
3733 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3735 req->sym_out = req1.sym_out;
3736 req->defobj_out = req1.defobj_out;
3740 if (obj->needed_aux_filtees != NULL) {
3741 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3742 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3743 donelist_init(&donelist);
3744 symlook_init_from_req(&req1, req);
3745 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3747 req->sym_out = req1.sym_out;
3748 req->defobj_out = req1.defobj_out;
3756 /* Symbol match routine common to both hash functions */
3758 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
3759 const unsigned long symnum)
3762 const Elf_Sym *symp = obj->symtab + symnum;
3763 const char *strp = obj->strtab + symp->st_name;
3765 switch (ELF_ST_TYPE(symp->st_info)) {
3771 if (symp->st_value == 0)
3775 if (symp->st_shndx != SHN_UNDEF)
3777 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3778 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3784 if (strcmp(req->name, strp) != 0)
3787 if (req->ventry == NULL) {
3788 if (obj->versyms != NULL) {
3789 verndx = VER_NDX(obj->versyms[symnum]);
3790 if (verndx > obj->vernum) {
3791 _rtld_error("%s: symbol %s references wrong version %d",
3792 obj->path, obj->strtab + symnum, verndx);
3796 * If we are not called from dlsym (i.e. this is a normal relocation
3797 * from unversioned binary), accept the symbol immediately if it happens
3798 * to have first version after this shared object became versioned.
3799 * Otherwise, if symbol is versioned and not hidden, remember it. If it
3800 * is the only symbol with this name exported by the shared object, it
3801 * will be returned as a match by the calling function. If symbol is
3802 * global (verndx < 2) accept it unconditionally.
3804 if ((req->flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN) {
3805 result->sym_out = symp;
3808 else if (verndx >= VER_NDX_GIVEN) {
3809 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
3810 if (result->vsymp == NULL)
3811 result->vsymp = symp;
3817 result->sym_out = symp;
3820 if (obj->versyms == NULL) {
3821 if (object_match_name(obj, req->ventry->name)) {
3822 _rtld_error("%s: object %s should provide version %s for "
3823 "symbol %s", obj_rtld.path, obj->path,
3824 req->ventry->name, obj->strtab + symnum);
3828 verndx = VER_NDX(obj->versyms[symnum]);
3829 if (verndx > obj->vernum) {
3830 _rtld_error("%s: symbol %s references wrong version %d",
3831 obj->path, obj->strtab + symnum, verndx);
3834 if (obj->vertab[verndx].hash != req->ventry->hash ||
3835 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
3837 * Version does not match. Look if this is a global symbol and if it is
3838 * not hidden. If global symbol (verndx < 2) is available, use it. Do not
3839 * return symbol if we are called by dlvsym, because dlvsym looks for a
3840 * specific version and default one is not what dlvsym wants.
3842 if ((req->flags & SYMLOOK_DLSYM) || (verndx >= VER_NDX_GIVEN) ||
3843 (obj->versyms[symnum] & VER_NDX_HIDDEN))
3847 result->sym_out = symp;
3852 * Search for symbol using SysV hash function.
3853 * obj->buckets is known not to be NULL at this point; the test for this was
3854 * performed with the obj->valid_hash_sysv assignment.
3857 symlook_obj1(SymLook *req, const Obj_Entry *obj)
3859 unsigned long symnum;
3860 Sym_Match_Result matchres;
3862 matchres.sym_out = NULL;
3863 matchres.vsymp = NULL;
3864 matchres.vcount = 0;
3866 for (symnum = obj->buckets[req->hash % obj->nbuckets];
3867 symnum != STN_UNDEF;
3868 symnum = obj->chains[symnum]) {
3870 if (symnum >= obj->nchains)
3871 return (ESRCH); /* Bad object */
3873 if (matched_symbol(req, obj, &matchres, symnum)) {
3874 req->sym_out = matchres.sym_out;
3875 req->defobj_out = obj;
3879 if (matchres.vcount == 1) {
3880 req->sym_out = matchres.vsymp;
3881 req->defobj_out = obj;
3887 /* Search for symbol using GNU hash function */
3889 symlook_obj2(SymLook *req, const Obj_Entry *obj)
3891 Elf_Addr bloom_word;
3893 unsigned int h1, h2;
3894 unsigned long symnum;
3895 const int c = __ELF_WORD_SIZE;
3896 Sym_Match_Result matchres;
3898 matchres.sym_out = NULL;
3899 matchres.vsymp = NULL;
3900 matchres.vcount = 0;
3902 /* pick right bitmask word from Bloom filter array*/
3903 bloom_word = obj->bloom_gnu[(req->hash_gnu / c) & obj->maskwords_bm_gnu];
3905 /* calculate modulus 32 (64 for x86_64) of gnu hash and its derivative */
3906 h1 = req->hash_gnu & (c - 1);
3907 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (c - 1));
3909 /* Filter out the "definitely not in set" queries */
3910 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
3913 /* Locate hash chain and corresponding value element*/
3914 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
3917 const Elf32_Word *hashval = &obj->chain_zero_gnu[bucket];
3919 if (((*hashval ^ req->hash_gnu) >> 1) == 0)
3921 symnum = hashval - obj->chain_zero_gnu;
3922 if (matched_symbol(req, obj, &matchres, symnum)) {
3923 req->sym_out = matchres.sym_out;
3924 req->defobj_out = obj;
3928 while ((*hashval++ & 1u) == 0);
3929 if (matchres.vcount == 1) {
3930 req->sym_out = matchres.vsymp;
3931 req->defobj_out = obj;
3938 trace_loaded_objects(Obj_Entry *obj)
3940 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
3943 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
3946 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
3947 fmt1 = "\t%o => %p (%x)\n";
3949 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
3950 fmt2 = "\t%o (%x)\n";
3952 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");
3954 for (; obj; obj = obj->next) {
3955 Needed_Entry *needed;
3959 if (list_containers && obj->needed != NULL)
3960 rtld_printf("%s:\n", obj->path);
3961 for (needed = obj->needed; needed; needed = needed->next) {
3962 if (needed->obj != NULL) {
3963 if (needed->obj->traced && !list_containers)
3965 needed->obj->traced = true;
3966 path = needed->obj->path;
3970 name = (char *)obj->strtab + needed->name;
3971 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
3973 fmt = is_lib ? fmt1 : fmt2;
3974 while ((c = *fmt++) != '\0') {
4000 rtld_putstr(main_local);
4003 rtld_putstr(obj_main->path);
4012 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4025 * Unload a dlopened object and its dependencies from memory and from
4026 * our data structures. It is assumed that the DAG rooted in the
4027 * object has already been unreferenced, and that the object has a
4028 * reference count of 0.
4031 unload_object(Obj_Entry *root)
4036 assert(root->refcount == 0);
4039 * Pass over the DAG removing unreferenced objects from
4040 * appropriate lists.
4042 unlink_object(root);
4044 /* Unmap all objects that are no longer referenced. */
4045 linkp = &obj_list->next;
4046 while ((obj = *linkp) != NULL) {
4047 if (obj->refcount == 0) {
4048 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
4050 dbg("unloading \"%s\"", obj->path);
4051 unload_filtees(root);
4052 munmap(obj->mapbase, obj->mapsize);
4053 linkmap_delete(obj);
4064 unlink_object(Obj_Entry *root)
4068 if (root->refcount == 0) {
4069 /* Remove the object from the RTLD_GLOBAL list. */
4070 objlist_remove(&list_global, root);
4072 /* Remove the object from all objects' DAG lists. */
4073 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4074 objlist_remove(&elm->obj->dldags, root);
4075 if (elm->obj != root)
4076 unlink_object(elm->obj);
4082 ref_dag(Obj_Entry *root)
4086 assert(root->dag_inited);
4087 STAILQ_FOREACH(elm, &root->dagmembers, link)
4088 elm->obj->refcount++;
4092 unref_dag(Obj_Entry *root)
4096 assert(root->dag_inited);
4097 STAILQ_FOREACH(elm, &root->dagmembers, link)
4098 elm->obj->refcount--;
4102 * Common code for MD __tls_get_addr().
4105 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
4107 Elf_Addr* dtv = *dtvp;
4108 RtldLockState lockstate;
4110 /* Check dtv generation in case new modules have arrived */
4111 if (dtv[0] != tls_dtv_generation) {
4115 wlock_acquire(rtld_bind_lock, &lockstate);
4116 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4118 if (to_copy > tls_max_index)
4119 to_copy = tls_max_index;
4120 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4121 newdtv[0] = tls_dtv_generation;
4122 newdtv[1] = tls_max_index;
4124 lock_release(rtld_bind_lock, &lockstate);
4125 dtv = *dtvp = newdtv;
4128 /* Dynamically allocate module TLS if necessary */
4129 if (!dtv[index + 1]) {
4130 /* Signal safe, wlock will block out signals. */
4131 wlock_acquire(rtld_bind_lock, &lockstate);
4132 if (!dtv[index + 1])
4133 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4134 lock_release(rtld_bind_lock, &lockstate);
4136 return (void*) (dtv[index + 1] + offset);
4139 #if defined(RTLD_STATIC_TLS_VARIANT_II)
4142 * Allocate the static TLS area. Return a pointer to the TCB. The
4143 * static area is based on negative offsets relative to the tcb.
4145 * The TCB contains an errno pointer for the system call layer, but because
4146 * we are the RTLD we really have no idea how the caller was compiled so
4147 * the information has to be passed in. errno can either be:
4149 * type 0 errno is a simple non-TLS global pointer.
4150 * (special case for e.g. libc_rtld)
4151 * type 1 errno accessed by GOT entry (dynamically linked programs)
4152 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
4155 allocate_tls(Obj_Entry *objs)
4160 struct tls_tcb *tcb;
4165 * Allocate the new TCB. static TLS storage is placed just before the
4166 * TCB to support the %gs:OFFSET (negative offset) model.
4168 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4169 ~RTLD_STATIC_TLS_ALIGN_MASK;
4170 tcb = malloc(data_size + sizeof(*tcb));
4171 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
4173 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
4174 dtv = malloc(dtv_size);
4175 bzero(dtv, dtv_size);
4177 #ifdef RTLD_TCB_HAS_SELF_POINTER
4178 tcb->tcb_self = tcb;
4181 tcb->tcb_pthread = NULL;
4183 dtv[0] = tls_dtv_generation;
4184 dtv[1] = tls_max_index;
4186 for (obj = objs; obj; obj = obj->next) {
4187 if (obj->tlsoffset) {
4188 addr = (Elf_Addr)tcb - obj->tlsoffset;
4189 memset((void *)(addr + obj->tlsinitsize),
4190 0, obj->tlssize - obj->tlsinitsize);
4192 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4193 dtv[obj->tlsindex + 1] = addr;
4200 free_tls(struct tls_tcb *tcb)
4204 Elf_Addr tls_start, tls_end;
4207 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4208 ~RTLD_STATIC_TLS_ALIGN_MASK;
4212 tls_end = (Elf_Addr)tcb;
4213 tls_start = (Elf_Addr)tcb - data_size;
4214 for (i = 0; i < dtv_size; i++) {
4215 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
4216 free((void *)dtv[i+2]);
4220 free((void*) tls_start);
4224 #error "Unsupported TLS layout"
4228 * Allocate TLS block for module with given index.
4231 allocate_module_tls(int index)
4236 for (obj = obj_list; obj; obj = obj->next) {
4237 if (obj->tlsindex == index)
4241 _rtld_error("Can't find module with TLS index %d", index);
4245 p = malloc(obj->tlssize);
4247 _rtld_error("Cannot allocate TLS block for index %d", index);
4250 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4251 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4257 allocate_tls_offset(Obj_Entry *obj)
4264 if (obj->tlssize == 0) {
4265 obj->tls_done = true;
4269 if (obj->tlsindex == 1)
4270 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4272 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4273 obj->tlssize, obj->tlsalign);
4276 * If we have already fixed the size of the static TLS block, we
4277 * must stay within that size. When allocating the static TLS, we
4278 * leave a small amount of space spare to be used for dynamically
4279 * loading modules which use static TLS.
4281 if (tls_static_space) {
4282 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4286 tls_last_offset = obj->tlsoffset = off;
4287 tls_last_size = obj->tlssize;
4288 obj->tls_done = true;
4294 free_tls_offset(Obj_Entry *obj)
4296 #ifdef RTLD_STATIC_TLS_VARIANT_II
4298 * If we were the last thing to allocate out of the static TLS
4299 * block, we give our space back to the 'allocator'. This is a
4300 * simplistic workaround to allow libGL.so.1 to be loaded and
4301 * unloaded multiple times. We only handle the Variant II
4302 * mechanism for now - this really needs a proper allocator.
4304 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
4305 == calculate_tls_end(tls_last_offset, tls_last_size)) {
4306 tls_last_offset -= obj->tlssize;
4313 _rtld_allocate_tls(void)
4315 struct tls_tcb *new_tcb;
4316 RtldLockState lockstate;
4318 wlock_acquire(rtld_bind_lock, &lockstate);
4319 new_tcb = allocate_tls(obj_list);
4320 lock_release(rtld_bind_lock, &lockstate);
4325 _rtld_free_tls(struct tls_tcb *tcb)
4327 RtldLockState lockstate;
4329 wlock_acquire(rtld_bind_lock, &lockstate);
4331 lock_release(rtld_bind_lock, &lockstate);
4335 object_add_name(Obj_Entry *obj, const char *name)
4341 entry = malloc(sizeof(Name_Entry) + len);
4343 if (entry != NULL) {
4344 strcpy(entry->name, name);
4345 STAILQ_INSERT_TAIL(&obj->names, entry, link);
4350 object_match_name(const Obj_Entry *obj, const char *name)
4354 STAILQ_FOREACH(entry, &obj->names, link) {
4355 if (strcmp(name, entry->name) == 0)
4362 locate_dependency(const Obj_Entry *obj, const char *name)
4364 const Objlist_Entry *entry;
4365 const Needed_Entry *needed;
4367 STAILQ_FOREACH(entry, &list_main, link) {
4368 if (object_match_name(entry->obj, name))
4372 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4373 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4374 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4376 * If there is DT_NEEDED for the name we are looking for,
4377 * we are all set. Note that object might not be found if
4378 * dependency was not loaded yet, so the function can
4379 * return NULL here. This is expected and handled
4380 * properly by the caller.
4382 return (needed->obj);
4385 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4391 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4392 const Elf_Vernaux *vna)
4394 const Elf_Verdef *vd;
4395 const char *vername;
4397 vername = refobj->strtab + vna->vna_name;
4398 vd = depobj->verdef;
4400 _rtld_error("%s: version %s required by %s not defined",
4401 depobj->path, vername, refobj->path);
4405 if (vd->vd_version != VER_DEF_CURRENT) {
4406 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4407 depobj->path, vd->vd_version);
4410 if (vna->vna_hash == vd->vd_hash) {
4411 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4412 ((char *)vd + vd->vd_aux);
4413 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4416 if (vd->vd_next == 0)
4418 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4420 if (vna->vna_flags & VER_FLG_WEAK)
4422 _rtld_error("%s: version %s required by %s not found",
4423 depobj->path, vername, refobj->path);
4428 rtld_verify_object_versions(Obj_Entry *obj)
4430 const Elf_Verneed *vn;
4431 const Elf_Verdef *vd;
4432 const Elf_Verdaux *vda;
4433 const Elf_Vernaux *vna;
4434 const Obj_Entry *depobj;
4435 int maxvernum, vernum;
4437 if (obj->ver_checked)
4439 obj->ver_checked = true;
4443 * Walk over defined and required version records and figure out
4444 * max index used by any of them. Do very basic sanity checking
4448 while (vn != NULL) {
4449 if (vn->vn_version != VER_NEED_CURRENT) {
4450 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4451 obj->path, vn->vn_version);
4454 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4456 vernum = VER_NEED_IDX(vna->vna_other);
4457 if (vernum > maxvernum)
4459 if (vna->vna_next == 0)
4461 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4463 if (vn->vn_next == 0)
4465 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4469 while (vd != NULL) {
4470 if (vd->vd_version != VER_DEF_CURRENT) {
4471 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4472 obj->path, vd->vd_version);
4475 vernum = VER_DEF_IDX(vd->vd_ndx);
4476 if (vernum > maxvernum)
4478 if (vd->vd_next == 0)
4480 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4487 * Store version information in array indexable by version index.
4488 * Verify that object version requirements are satisfied along the
4491 obj->vernum = maxvernum + 1;
4492 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
4495 while (vd != NULL) {
4496 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4497 vernum = VER_DEF_IDX(vd->vd_ndx);
4498 assert(vernum <= maxvernum);
4499 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4500 obj->vertab[vernum].hash = vd->vd_hash;
4501 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4502 obj->vertab[vernum].file = NULL;
4503 obj->vertab[vernum].flags = 0;
4505 if (vd->vd_next == 0)
4507 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4511 while (vn != NULL) {
4512 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4515 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4517 if (check_object_provided_version(obj, depobj, vna))
4519 vernum = VER_NEED_IDX(vna->vna_other);
4520 assert(vernum <= maxvernum);
4521 obj->vertab[vernum].hash = vna->vna_hash;
4522 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4523 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4524 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4525 VER_INFO_HIDDEN : 0;
4526 if (vna->vna_next == 0)
4528 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4530 if (vn->vn_next == 0)
4532 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4538 rtld_verify_versions(const Objlist *objlist)
4540 Objlist_Entry *entry;
4544 STAILQ_FOREACH(entry, objlist, link) {
4546 * Skip dummy objects or objects that have their version requirements
4549 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4551 if (rtld_verify_object_versions(entry->obj) == -1) {
4553 if (ld_tracing == NULL)
4557 if (rc == 0 || ld_tracing != NULL)
4558 rc = rtld_verify_object_versions(&obj_rtld);
4563 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4568 vernum = VER_NDX(obj->versyms[symnum]);
4569 if (vernum >= obj->vernum) {
4570 _rtld_error("%s: symbol %s has wrong verneed value %d",
4571 obj->path, obj->strtab + symnum, vernum);
4572 } else if (obj->vertab[vernum].hash != 0) {
4573 return &obj->vertab[vernum];
4580 _rtld_get_stack_prot(void)
4583 return (stack_prot);
4587 map_stacks_exec(RtldLockState *lockstate)
4591 * Stack protection must be implemented in the kernel before the dynamic
4592 * linker can handle PT_GNU_STACK sections.
4593 * The following is the FreeBSD implementation of map_stacks_exec()
4594 * void (*thr_map_stacks_exec)(void);
4596 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4598 * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4599 * get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4600 * if (thr_map_stacks_exec != NULL) {
4601 * stack_prot |= PROT_EXEC;
4602 * thr_map_stacks_exec();
4608 symlook_init(SymLook *dst, const char *name)
4611 bzero(dst, sizeof(*dst));
4613 dst->hash = elf_hash(name);
4614 dst->hash_gnu = gnu_hash(name);
4618 symlook_init_from_req(SymLook *dst, const SymLook *src)
4621 dst->name = src->name;
4622 dst->hash = src->hash;
4623 dst->hash_gnu = src->hash_gnu;
4624 dst->ventry = src->ventry;
4625 dst->flags = src->flags;
4626 dst->defobj_out = NULL;
4627 dst->sym_out = NULL;
4628 dst->lockstate = src->lockstate;
4631 #ifdef ENABLE_OSRELDATE
4633 * Overrides for libc_pic-provided functions.
4637 __getosreldate(void)
4647 oid[1] = KERN_OSRELDATE;
4649 len = sizeof(osrel);
4650 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
4651 if (error == 0 && osrel > 0 && len == sizeof(osrel))
4658 * No unresolved symbols for rtld.
4661 __pthread_cxa_finalize(struct dl_phdr_info *a)
4666 rtld_strerror(int errnum)
4669 if (errnum < 0 || errnum >= sys_nerr)
4670 return ("Unknown error");
4671 return (sys_errlist[errnum]);