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);
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);
807 * Write the new contents for the jmpslot. Note that depending on
808 * architecture, the value which we need to return back to the
809 * lazy binding trampoline may or may not be the target
810 * address. The value returned from reloc_jmpslot() is the value
811 * that the trampoline needs.
813 target = reloc_jmpslot(where, target, defobj, obj, rel);
814 lock_release(rtld_bind_lock, &lockstate);
819 * Error reporting function. Use it like printf. If formats the message
820 * into a buffer, and sets things up so that the next call to dlerror()
821 * will return the message.
824 _rtld_error(const char *fmt, ...)
826 static char buf[512];
830 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
836 * Return a dynamically-allocated copy of the current error message, if any.
841 return error_message == NULL ? NULL : xstrdup(error_message);
845 * Restore the current error message from a copy which was previously saved
846 * by errmsg_save(). The copy is freed.
849 errmsg_restore(char *saved_msg)
851 if (saved_msg == NULL)
852 error_message = NULL;
854 _rtld_error("%s", saved_msg);
860 basename(const char *name)
862 const char *p = strrchr(name, '/');
863 return p != NULL ? p + 1 : name;
866 static struct utsname uts;
869 origin_subst_one(char **res, const char *real, const char *kw, const char *subst,
879 subst_len = kw_len = 0;
883 if (subst_len == 0) {
884 subst_len = strlen(subst);
888 *res = xmalloc(PATH_MAX);
891 if ((res1 - *res) + subst_len + (p1 - p) >= PATH_MAX) {
892 _rtld_error("Substitution of %s in %s cannot be performed",
894 if (may_free != NULL)
899 memcpy(res1, p, p1 - p);
901 memcpy(res1, subst, subst_len);
906 if (may_free != NULL)
909 *res = xstrdup(real);
913 if (may_free != NULL)
915 if (strlcat(res1, p, PATH_MAX - (res1 - *res)) >= PATH_MAX) {
925 origin_subst(const char *real, const char *origin_path)
927 char *res1, *res2, *res3, *res4;
929 if (uts.sysname[0] == '\0') {
930 if (uname(&uts) != 0) {
931 _rtld_error("utsname failed: %d", errno);
935 if (!origin_subst_one(&res1, real, "$ORIGIN", origin_path, NULL) ||
936 !origin_subst_one(&res2, res1, "$OSNAME", uts.sysname, res1) ||
937 !origin_subst_one(&res3, res2, "$OSREL", uts.release, res2) ||
938 !origin_subst_one(&res4, res3, "$PLATFORM", uts.machine, res3))
946 const char *msg = dlerror();
950 rtld_fdputstr(STDERR_FILENO, msg);
951 rtld_fdputchar(STDERR_FILENO, '\n');
956 * Process a shared object's DYNAMIC section, and save the important
957 * information in its Obj_Entry structure.
960 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
961 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
964 Needed_Entry **needed_tail = &obj->needed;
965 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
966 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
967 int plttype = DT_REL;
973 obj->bind_now = false;
974 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
975 switch (dynp->d_tag) {
978 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
982 obj->relsize = dynp->d_un.d_val;
986 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
990 obj->pltrel = (const Elf_Rel *)
991 (obj->relocbase + dynp->d_un.d_ptr);
995 obj->pltrelsize = dynp->d_un.d_val;
999 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
1003 obj->relasize = dynp->d_un.d_val;
1007 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
1011 plttype = dynp->d_un.d_val;
1012 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
1016 obj->symtab = (const Elf_Sym *)
1017 (obj->relocbase + dynp->d_un.d_ptr);
1021 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
1025 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
1029 obj->strsize = dynp->d_un.d_val;
1033 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1038 obj->verneednum = dynp->d_un.d_val;
1042 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1047 obj->verdefnum = dynp->d_un.d_val;
1051 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1057 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1058 (obj->relocbase + dynp->d_un.d_ptr);
1059 obj->nbuckets = hashtab[0];
1060 obj->nchains = hashtab[1];
1061 obj->buckets = hashtab + 2;
1062 obj->chains = obj->buckets + obj->nbuckets;
1063 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
1064 obj->buckets != NULL;
1070 const Elf_Hashelt *hashtab = (const Elf_Hashelt *)
1071 (obj->relocbase + dynp->d_un.d_ptr);
1072 obj->nbuckets_gnu = hashtab[0];
1073 obj->symndx_gnu = hashtab[1];
1074 const Elf32_Word nmaskwords = hashtab[2];
1075 const int bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1076 /* Number of bitmask words is required to be power of 2 */
1077 const bool nmw_power2 = ((nmaskwords & (nmaskwords - 1)) == 0);
1078 obj->maskwords_bm_gnu = nmaskwords - 1;
1079 obj->shift2_gnu = hashtab[3];
1080 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1081 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1082 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1084 obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 &&
1085 obj->buckets_gnu != NULL;
1091 Needed_Entry *nep = NEW(Needed_Entry);
1092 nep->name = dynp->d_un.d_val;
1097 needed_tail = &nep->next;
1103 Needed_Entry *nep = NEW(Needed_Entry);
1104 nep->name = dynp->d_un.d_val;
1108 *needed_filtees_tail = nep;
1109 needed_filtees_tail = &nep->next;
1115 Needed_Entry *nep = NEW(Needed_Entry);
1116 nep->name = dynp->d_un.d_val;
1120 *needed_aux_filtees_tail = nep;
1121 needed_aux_filtees_tail = &nep->next;
1126 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1130 obj->textrel = true;
1134 obj->symbolic = true;
1139 * We have to wait until later to process this, because we
1140 * might not have gotten the address of the string table yet.
1150 *dyn_runpath = dynp;
1154 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1158 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1161 case DT_PREINIT_ARRAY:
1162 obj->preinit_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1166 obj->init_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1170 obj->fini_array = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1173 case DT_PREINIT_ARRAYSZ:
1174 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1177 case DT_INIT_ARRAYSZ:
1178 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1181 case DT_FINI_ARRAYSZ:
1182 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1186 /* XXX - not implemented yet */
1188 dbg("Filling in DT_DEBUG entry");
1189 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1193 if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
1194 obj->z_origin = true;
1195 if (dynp->d_un.d_val & DF_SYMBOLIC)
1196 obj->symbolic = true;
1197 if (dynp->d_un.d_val & DF_TEXTREL)
1198 obj->textrel = true;
1199 if (dynp->d_un.d_val & DF_BIND_NOW)
1200 obj->bind_now = true;
1201 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1206 if (dynp->d_un.d_val & DF_1_NOOPEN)
1207 obj->z_noopen = true;
1208 if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
1209 obj->z_origin = true;
1210 /*if (dynp->d_un.d_val & DF_1_GLOBAL)
1212 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1213 obj->bind_now = true;
1214 if (dynp->d_un.d_val & DF_1_NODELETE)
1215 obj->z_nodelete = true;
1216 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1217 obj->z_loadfltr = true;
1218 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1219 obj->z_nodeflib = true;
1224 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1231 obj->traced = false;
1233 if (plttype == DT_RELA) {
1234 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1236 obj->pltrelasize = obj->pltrelsize;
1237 obj->pltrelsize = 0;
1240 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1241 if (obj->valid_hash_sysv)
1242 obj->dynsymcount = obj->nchains;
1243 else if (obj->valid_hash_gnu) {
1244 obj->dynsymcount = 0;
1245 for (Elf32_Word bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1246 if (obj->buckets_gnu[bkt] == 0)
1248 const Elf32_Word *hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1251 while ((*hashval++ & 1u) == 0);
1253 obj->dynsymcount += obj->symndx_gnu;
1258 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1259 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1262 if (obj->z_origin && obj->origin_path == NULL) {
1263 obj->origin_path = xmalloc(PATH_MAX);
1264 if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
1268 if (dyn_runpath != NULL) {
1269 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1271 obj->runpath = origin_subst(obj->runpath, obj->origin_path);
1273 else if (dyn_rpath != NULL) {
1274 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1276 obj->rpath = origin_subst(obj->rpath, obj->origin_path);
1279 if (dyn_soname != NULL)
1280 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1284 digest_dynamic(Obj_Entry *obj, int early)
1286 const Elf_Dyn *dyn_rpath;
1287 const Elf_Dyn *dyn_soname;
1288 const Elf_Dyn *dyn_runpath;
1290 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1291 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1295 * Process a shared object's program header. This is used only for the
1296 * main program, when the kernel has already loaded the main program
1297 * into memory before calling the dynamic linker. It creates and
1298 * returns an Obj_Entry structure.
1301 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1304 const Elf_Phdr *phlimit = phdr + phnum;
1306 Elf_Addr note_start, note_end;
1310 for (ph = phdr; ph < phlimit; ph++) {
1311 if (ph->p_type != PT_PHDR)
1315 obj->phsize = ph->p_memsz;
1316 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1320 obj->stack_flags = PF_X | PF_R | PF_W;
1322 for (ph = phdr; ph < phlimit; ph++) {
1323 switch (ph->p_type) {
1326 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1330 if (nsegs == 0) { /* First load segment */
1331 obj->vaddrbase = trunc_page(ph->p_vaddr);
1332 obj->mapbase = obj->vaddrbase + obj->relocbase;
1333 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1335 } else { /* Last load segment */
1336 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1343 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1348 obj->tlssize = ph->p_memsz;
1349 obj->tlsalign = ph->p_align;
1350 obj->tlsinitsize = ph->p_filesz;
1351 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1355 obj->stack_flags = ph->p_flags;
1359 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1360 obj->relro_size = round_page(ph->p_memsz);
1364 obj->note_present = true;
1365 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1366 note_end = note_start + ph->p_filesz;
1367 digest_notes(obj, note_start, note_end);
1372 _rtld_error("%s: too few PT_LOAD segments", path);
1381 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1383 const Elf_Note *note;
1384 const char *note_name;
1387 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1388 note = (const Elf_Note *)((const char *)(note + 1) +
1389 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1390 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1391 if (note->n_namesz != sizeof(NOTE_VENDOR) ||
1392 note->n_descsz != sizeof(int32_t))
1394 if (note->n_type != ABI_NOTETYPE && note->n_type != CRT_NOINIT_NOTETYPE)
1396 note_name = (const char *)(note + 1);
1397 if (strncmp(NOTE_VENDOR, note_name, sizeof(NOTE_VENDOR)) != 0)
1399 switch (note->n_type) {
1401 /* DragonFly osrel note */
1402 p = (uintptr_t)(note + 1);
1403 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1404 obj->osrel = *(const int32_t *)(p);
1405 dbg("note osrel %d", obj->osrel);
1407 case CRT_NOINIT_NOTETYPE:
1408 /* DragonFly 'crt does not call init' note */
1409 obj->crt_no_init = true;
1410 dbg("note crt_no_init");
1417 dlcheck(void *handle)
1421 for (obj = obj_list; obj != NULL; obj = obj->next)
1422 if (obj == (Obj_Entry *) handle)
1425 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1426 _rtld_error("Invalid shared object handle %p", handle);
1433 * If the given object is already in the donelist, return true. Otherwise
1434 * add the object to the list and return false.
1437 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1441 for (i = 0; i < dlp->num_used; i++)
1442 if (dlp->objs[i] == obj)
1445 * Our donelist allocation should always be sufficient. But if
1446 * our threads locking isn't working properly, more shared objects
1447 * could have been loaded since we allocated the list. That should
1448 * never happen, but we'll handle it properly just in case it does.
1450 if (dlp->num_used < dlp->num_alloc)
1451 dlp->objs[dlp->num_used++] = obj;
1456 * Hash function for symbol table lookup. Don't even think about changing
1457 * this. It is specified by the System V ABI.
1460 elf_hash(const char *name)
1462 const unsigned char *p = (const unsigned char *) name;
1463 unsigned long h = 0;
1466 while (*p != '\0') {
1467 h = (h << 4) + *p++;
1468 if ((g = h & 0xf0000000) != 0)
1476 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1477 * unsigned in case it's implemented with a wider type.
1479 static uint_fast32_t
1480 gnu_hash (const char *s)
1482 uint_fast32_t h = 5381;
1483 for (unsigned char c = *s; c != '\0'; c = *++s)
1485 return h & 0xffffffff;
1489 * Find the library with the given name, and return its full pathname.
1490 * The returned string is dynamically allocated. Generates an error
1491 * message and returns NULL if the library cannot be found.
1493 * If the second argument is non-NULL, then it refers to an already-
1494 * loaded shared object, whose library search path will be searched.
1496 * The search order is:
1497 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1498 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1500 * DT_RUNPATH in the referencing file
1501 * ldconfig hints (if -z nodefaultlib, filter out /usr/lib from list)
1502 * /usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1504 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1507 find_library(const char *xname, const Obj_Entry *refobj)
1511 bool objgiven = (refobj != NULL);
1513 if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
1514 if (xname[0] != '/' && !trust) {
1515 _rtld_error("Absolute pathname required for shared object \"%s\"",
1519 if (objgiven && refobj->z_origin)
1520 return origin_subst(xname, refobj->origin_path);
1522 return xstrdup(xname);
1525 if (libmap_disable || !objgiven ||
1526 (name = lm_find(refobj->path, xname)) == NULL)
1527 name = (char *)xname;
1529 dbg(" Searching for \"%s\"", name);
1532 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
1533 (objgiven && (refobj->runpath == NULL) && (refobj != obj_main) &&
1534 (pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
1535 (pathname = search_library_path(name, ld_library_path)) != NULL ||
1537 (pathname = search_library_path(name, refobj->runpath)) != NULL) ||
1538 (pathname = search_library_path(name, gethints(refobj))) != NULL ||
1539 (objgiven && !refobj->z_nodeflib &&
1540 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
1543 if(objgiven && refobj->path != NULL) {
1544 _rtld_error("Shared object \"%s\" not found, required by \"%s\"",
1545 name, basename(refobj->path));
1547 _rtld_error("Shared object \"%s\" not found", name);
1553 * Given a symbol number in a referencing object, find the corresponding
1554 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1555 * no definition was found. Returns a pointer to the Obj_Entry of the
1556 * defining object via the reference parameter DEFOBJ_OUT.
1559 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1560 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1561 RtldLockState *lockstate)
1565 const Obj_Entry *defobj;
1571 * If we have already found this symbol, get the information from
1574 if (symnum >= refobj->dynsymcount)
1575 return NULL; /* Bad object */
1576 if (cache != NULL && cache[symnum].sym != NULL) {
1577 *defobj_out = cache[symnum].obj;
1578 return cache[symnum].sym;
1581 ref = refobj->symtab + symnum;
1582 name = refobj->strtab + ref->st_name;
1587 * We don't have to do a full scale lookup if the symbol is local.
1588 * We know it will bind to the instance in this load module; to
1589 * which we already have a pointer (ie ref). By not doing a lookup,
1590 * we not only improve performance, but it also avoids unresolvable
1591 * symbols when local symbols are not in the hash table.
1593 * This might occur for TLS module relocations, which simply use
1596 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1597 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1598 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1601 symlook_init(&req, name);
1603 req.ventry = fetch_ventry(refobj, symnum);
1604 req.lockstate = lockstate;
1605 res = symlook_default(&req, refobj);
1608 defobj = req.defobj_out;
1616 * If we found no definition and the reference is weak, treat the
1617 * symbol as having the value zero.
1619 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1625 *defobj_out = defobj;
1626 /* Record the information in the cache to avoid subsequent lookups. */
1627 if (cache != NULL) {
1628 cache[symnum].sym = def;
1629 cache[symnum].obj = defobj;
1632 if (refobj != &obj_rtld)
1633 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
1639 * Return the search path from the ldconfig hints file, reading it if
1640 * necessary. Returns NULL if there are problems with the hints file,
1641 * or if the search path there is empty.
1642 * If DF_1_NODEFLIB flag set, omit STANDARD_LIBRARY_PATH directories
1645 gethints(const Obj_Entry *obj)
1649 if (hints == NULL) {
1651 struct elfhints_hdr hdr;
1654 /* Keep from trying again in case the hints file is bad. */
1657 if ((fd = open(ld_elf_hints_path, O_RDONLY)) == -1)
1659 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1660 hdr.magic != ELFHINTS_MAGIC ||
1665 p = xmalloc(hdr.dirlistlen + 1);
1666 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
1667 read(fd, p, hdr.dirlistlen + 1) != (ssize_t)hdr.dirlistlen + 1) {
1672 /* skip stdlib if compiled with -z nodeflib */
1673 if ((obj != NULL) && obj->z_nodeflib) {
1674 struct fill_search_info_args sargs, hargs;
1675 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1676 struct dl_serpath *SLPpath, *hintpath;
1677 unsigned int SLPndx, hintndx, fndx, fcount;
1678 char *filtered_path;
1682 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1684 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1687 sargs.request = RTLD_DI_SERINFOSIZE;
1688 sargs.serinfo = &smeta;
1689 hargs.request = RTLD_DI_SERINFOSIZE;
1690 hargs.serinfo = &hmeta;
1692 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1693 path_enumerate(p, fill_search_info, &hargs);
1695 SLPinfo = malloc(smeta.dls_size);
1696 hintinfo = malloc(hmeta.dls_size);
1698 sargs.request = RTLD_DI_SERINFO;
1699 sargs.serinfo = SLPinfo;
1700 sargs.serpath = &SLPinfo->dls_serpath[0];
1701 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1703 hargs.request = RTLD_DI_SERINFO;
1704 hargs.serinfo = hintinfo;
1705 hargs.serpath = &hintinfo->dls_serpath[0];
1706 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1708 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
1709 path_enumerate(p, fill_search_info, &hargs);
1713 filtered_path = xmalloc(hdr.dirlistlen + 1);
1714 hintpath = &hintinfo->dls_serpath[0];
1715 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++) {
1717 SLPpath = &SLPinfo->dls_serpath[0];
1718 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++) {
1719 if (strcmp(hintpath->dls_name, SLPpath->dls_name) == 0)
1725 filtered_path[fndx] = ':';
1729 flen = strlen(hintpath->dls_name);
1730 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1735 filtered_path[fndx] = '\0';
1740 hints = filtered_path;
1746 return hints[0] != '\0' ? hints : NULL;
1750 init_dag(Obj_Entry *root)
1752 const Needed_Entry *needed;
1753 const Objlist_Entry *elm;
1756 if (root->dag_inited)
1758 donelist_init(&donelist);
1760 /* Root object belongs to own DAG. */
1761 objlist_push_tail(&root->dldags, root);
1762 objlist_push_tail(&root->dagmembers, root);
1763 donelist_check(&donelist, root);
1766 * Add dependencies of root object to DAG in breadth order
1767 * by exploiting the fact that each new object get added
1768 * to the tail of the dagmembers list.
1770 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1771 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1772 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1774 objlist_push_tail(&needed->obj->dldags, root);
1775 objlist_push_tail(&root->dagmembers, needed->obj);
1778 root->dag_inited = true;
1782 * Initialize the dynamic linker. The argument is the address at which
1783 * the dynamic linker has been mapped into memory. The primary task of
1784 * this function is to relocate the dynamic linker.
1787 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
1789 Obj_Entry objtmp; /* Temporary rtld object */
1790 const Elf_Dyn *dyn_rpath;
1791 const Elf_Dyn *dyn_soname;
1792 const Elf_Dyn *dyn_runpath;
1795 * Conjure up an Obj_Entry structure for the dynamic linker.
1797 * The "path" member can't be initialized yet because string constants
1798 * cannot yet be accessed. Below we will set it correctly.
1800 memset(&objtmp, 0, sizeof(objtmp));
1803 objtmp.mapbase = mapbase;
1805 objtmp.relocbase = mapbase;
1807 if (RTLD_IS_DYNAMIC()) {
1808 objtmp.dynamic = rtld_dynamic(&objtmp);
1809 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
1810 assert(objtmp.needed == NULL);
1811 assert(!objtmp.textrel);
1814 * Temporarily put the dynamic linker entry into the object list, so
1815 * that symbols can be found.
1818 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
1821 /* Initialize the object list. */
1822 obj_tail = &obj_list;
1824 /* Now that non-local variables can be accesses, copy out obj_rtld. */
1825 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
1827 #ifdef ENABLE_OSRELDATE
1828 if (aux_info[AT_OSRELDATE] != NULL)
1829 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
1832 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
1834 /* Replace the path with a dynamically allocated copy. */
1835 obj_rtld.path = xstrdup(PATH_RTLD);
1837 r_debug.r_brk = r_debug_state;
1838 r_debug.r_state = RT_CONSISTENT;
1842 * Add the init functions from a needed object list (and its recursive
1843 * needed objects) to "list". This is not used directly; it is a helper
1844 * function for initlist_add_objects(). The write lock must be held
1845 * when this function is called.
1848 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1850 /* Recursively process the successor needed objects. */
1851 if (needed->next != NULL)
1852 initlist_add_neededs(needed->next, list);
1854 /* Process the current needed object. */
1855 if (needed->obj != NULL)
1856 initlist_add_objects(needed->obj, &needed->obj->next, list);
1860 * Scan all of the DAGs rooted in the range of objects from "obj" to
1861 * "tail" and add their init functions to "list". This recurses over
1862 * the DAGs and ensure the proper init ordering such that each object's
1863 * needed libraries are initialized before the object itself. At the
1864 * same time, this function adds the objects to the global finalization
1865 * list "list_fini" in the opposite order. The write lock must be
1866 * held when this function is called.
1869 initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1872 if (obj->init_scanned || obj->init_done)
1874 obj->init_scanned = true;
1876 /* Recursively process the successor objects. */
1877 if (&obj->next != tail)
1878 initlist_add_objects(obj->next, tail, list);
1880 /* Recursively process the needed objects. */
1881 if (obj->needed != NULL)
1882 initlist_add_neededs(obj->needed, list);
1883 if (obj->needed_filtees != NULL)
1884 initlist_add_neededs(obj->needed_filtees, list);
1885 if (obj->needed_aux_filtees != NULL)
1886 initlist_add_neededs(obj->needed_aux_filtees, list);
1888 /* Add the object to the init list. */
1889 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
1890 obj->init_array != (Elf_Addr)NULL)
1891 objlist_push_tail(list, obj);
1893 /* Add the object to the global fini list in the reverse order. */
1894 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
1895 && !obj->on_fini_list) {
1896 objlist_push_head(&list_fini, obj);
1897 obj->on_fini_list = true;
1902 #define FPTR_TARGET(f) ((Elf_Addr) (f))
1906 is_exported(const Elf_Sym *def)
1909 const func_ptr_type *p;
1911 value = (Elf_Addr)(obj_rtld.relocbase + def->st_value);
1912 for (p = exports; *p != NULL; p++)
1913 if (FPTR_TARGET(*p) == value)
1919 free_needed_filtees(Needed_Entry *n)
1921 Needed_Entry *needed, *needed1;
1923 for (needed = n; needed != NULL; needed = needed->next) {
1924 if (needed->obj != NULL) {
1925 dlclose(needed->obj);
1929 for (needed = n; needed != NULL; needed = needed1) {
1930 needed1 = needed->next;
1936 unload_filtees(Obj_Entry *obj)
1939 free_needed_filtees(obj->needed_filtees);
1940 obj->needed_filtees = NULL;
1941 free_needed_filtees(obj->needed_aux_filtees);
1942 obj->needed_aux_filtees = NULL;
1943 obj->filtees_loaded = false;
1947 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags)
1950 for (; needed != NULL; needed = needed->next) {
1951 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
1952 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
1958 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
1961 lock_restart_for_upgrade(lockstate);
1962 if (!obj->filtees_loaded) {
1963 load_filtee1(obj, obj->needed_filtees, flags);
1964 load_filtee1(obj, obj->needed_aux_filtees, flags);
1965 obj->filtees_loaded = true;
1970 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
1974 for (; needed != NULL; needed = needed->next) {
1975 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
1976 flags & ~RTLD_LO_NOLOAD);
1977 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
1979 if (obj1 != NULL && obj1->z_nodelete && !obj1->ref_nodel) {
1980 dbg("obj %s nodelete", obj1->path);
1983 obj1->ref_nodel = true;
1990 * Given a shared object, traverse its list of needed objects, and load
1991 * each of them. Returns 0 on success. Generates an error message and
1992 * returns -1 on failure.
1995 load_needed_objects(Obj_Entry *first, int flags)
1999 for (obj = first; obj != NULL; obj = obj->next) {
2000 if (process_needed(obj, obj->needed, flags) == -1)
2007 load_preload_objects(void)
2009 char *p = ld_preload;
2010 static const char delim[] = " \t:;";
2015 p += strspn(p, delim);
2016 while (*p != '\0') {
2017 size_t len = strcspn(p, delim);
2025 obj = load_object(p, -1, NULL, 0);
2027 return -1; /* XXX - cleanup */
2030 p += strspn(p, delim);
2032 /* Check for the magic tracing function */
2033 symlook_init(&req, RTLD_FUNCTRACE);
2034 res = symlook_obj(&req, obj);
2036 rtld_functrace = (void *)(req.defobj_out->relocbase +
2037 req.sym_out->st_value);
2038 rtld_functrace_obj = req.defobj_out;
2041 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2046 printable_path(const char *path)
2049 return (path == NULL ? "<unknown>" : path);
2053 * Load a shared object into memory, if it is not already loaded. The
2054 * object may be specified by name or by user-supplied file descriptor
2055 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2058 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2062 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2070 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
2071 if (object_match_name(obj, name))
2075 path = find_library(name, refobj);
2082 * If we didn't find a match by pathname, or the name is not
2083 * supplied, open the file and check again by device and inode.
2084 * This avoids false mismatches caused by multiple links or ".."
2087 * To avoid a race, we open the file and use fstat() rather than
2092 if ((fd = open(path, O_RDONLY)) == -1) {
2093 _rtld_error("Cannot open \"%s\"", path);
2100 _rtld_error("Cannot dup fd");
2105 if (fstat(fd, &sb) == -1) {
2106 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2111 for (obj = obj_list->next; obj != NULL; obj = obj->next)
2112 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2114 if (obj != NULL && name != NULL) {
2115 object_add_name(obj, name);
2120 if (flags & RTLD_LO_NOLOAD) {
2126 /* First use of this object, so we must map it in */
2127 obj = do_load_object(fd, name, path, &sb, flags);
2136 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2143 * but first, make sure that environment variables haven't been
2144 * used to circumvent the noexec flag on a filesystem.
2146 if (dangerous_ld_env) {
2147 if (fstatfs(fd, &fs) != 0) {
2148 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2151 if (fs.f_flags & MNT_NOEXEC) {
2152 _rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
2156 dbg("loading \"%s\"", printable_path(path));
2157 obj = map_object(fd, printable_path(path), sbp);
2162 * If DT_SONAME is present in the object, digest_dynamic2 already
2163 * added it to the object names.
2166 object_add_name(obj, name);
2168 digest_dynamic(obj, 0);
2169 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2171 dbg("refusing to load non-loadable \"%s\"", obj->path);
2172 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2173 munmap(obj->mapbase, obj->mapsize);
2179 obj_tail = &obj->next;
2182 linkmap_add(obj); /* for GDB & dlinfo() */
2183 max_stack_flags |= obj->stack_flags;
2185 dbg(" %p .. %p: %s", obj->mapbase,
2186 obj->mapbase + obj->mapsize - 1, obj->path);
2188 dbg(" WARNING: %s has impure text", obj->path);
2189 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2196 obj_from_addr(const void *addr)
2200 for (obj = obj_list; obj != NULL; obj = obj->next) {
2201 if (addr < (void *) obj->mapbase)
2203 if (addr < (void *) (obj->mapbase + obj->mapsize))
2210 * Call the finalization functions for each of the objects in "list"
2211 * belonging to the DAG of "root" and referenced once. If NULL "root"
2212 * is specified, every finalization function will be called regardless
2213 * of the reference count and the list elements won't be freed. All of
2214 * the objects are expected to have non-NULL fini functions.
2217 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2221 Elf_Addr *fini_addr;
2224 assert(root == NULL || root->refcount == 1);
2227 * Preserve the current error message since a fini function might
2228 * call into the dynamic linker and overwrite it.
2230 saved_msg = errmsg_save();
2232 STAILQ_FOREACH(elm, list, link) {
2233 if (root != NULL && (elm->obj->refcount != 1 ||
2234 objlist_find(&root->dagmembers, elm->obj) == NULL))
2237 /* Remove object from fini list to prevent recursive invocation. */
2238 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2240 * XXX: If a dlopen() call references an object while the
2241 * fini function is in progress, we might end up trying to
2242 * unload the referenced object in dlclose() or the object
2243 * won't be unloaded although its fini function has been
2246 lock_release(rtld_bind_lock, lockstate);
2249 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined. When this
2250 * happens, DT_FINI_ARRAY is processed first, and it is also processed
2251 * backwards. It is possible to encounter DT_FINI_ARRAY elements with
2252 * values of 0 or 1, but they need to be ignored.
2254 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2255 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2256 for (index = elm->obj->fini_array_num - 1; index >= 0; index--) {
2257 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2258 dbg("calling fini array function for %s at %p",
2259 elm->obj->path, (void *)fini_addr[index]);
2260 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2261 (void *)fini_addr[index], 0, 0, elm->obj->path);
2262 call_initfini_pointer(elm->obj, fini_addr[index]);
2266 if (elm->obj->fini != (Elf_Addr)NULL) {
2267 dbg("calling fini function for %s at %p", elm->obj->path,
2268 (void *)elm->obj->fini);
2269 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2270 0, 0, elm->obj->path);
2271 call_initfini_pointer(elm->obj, elm->obj->fini);
2273 wlock_acquire(rtld_bind_lock, lockstate);
2274 /* No need to free anything if process is going down. */
2278 * We must restart the list traversal after every fini call
2279 * because a dlclose() call from the fini function or from
2280 * another thread might have modified the reference counts.
2284 } while (elm != NULL);
2285 errmsg_restore(saved_msg);
2289 * If the main program is defined with a .preinit_array section, call
2290 * each function in order. This must occur before the initialization
2291 * of any shared object or the main program.
2294 preinitialize_main_object (void)
2296 Elf_Addr *preinit_addr;
2299 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2300 if (preinit_addr == NULL)
2303 for (index = 0; index < obj_main->preinit_array_num; index++) {
2304 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2305 dbg("calling preinit function for %s at %p", obj_main->path,
2306 (void *)preinit_addr[index]);
2307 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2308 0, 0, obj_main->path);
2309 call_init_pointer(obj_main, preinit_addr[index]);
2315 * Call the initialization functions for each of the objects in
2316 * "list". All of the objects are expected to have non-NULL init
2320 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2325 Elf_Addr *init_addr;
2329 * Clean init_scanned flag so that objects can be rechecked and
2330 * possibly initialized earlier if any of vectors called below
2331 * cause the change by using dlopen.
2333 for (obj = obj_list; obj != NULL; obj = obj->next)
2334 obj->init_scanned = false;
2337 * Preserve the current error message since an init function might
2338 * call into the dynamic linker and overwrite it.
2340 saved_msg = errmsg_save();
2341 STAILQ_FOREACH(elm, list, link) {
2342 if (elm->obj->init_done) /* Initialized early. */
2346 * Race: other thread might try to use this object before current
2347 * one completes the initilization. Not much can be done here
2348 * without better locking.
2350 elm->obj->init_done = true;
2351 lock_release(rtld_bind_lock, lockstate);
2354 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined. When
2355 * this happens, DT_INIT is processed first. It is possible to
2356 * encounter DT_INIT_ARRAY elements with values of 0 or 1, but they
2357 * need to be ignored.
2359 if (elm->obj->init != (Elf_Addr)NULL) {
2360 dbg("calling init function for %s at %p", elm->obj->path,
2361 (void *)elm->obj->init);
2362 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2363 0, 0, elm->obj->path);
2364 call_initfini_pointer(elm->obj, elm->obj->init);
2366 init_addr = (Elf_Addr *)elm->obj->init_array;
2367 if (init_addr != NULL) {
2368 for (index = 0; index < elm->obj->init_array_num; index++) {
2369 if (init_addr[index] != 0 && init_addr[index] != 1) {
2370 dbg("calling init array function for %s at %p", elm->obj->path,
2371 (void *)init_addr[index]);
2372 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2373 (void *)init_addr[index], 0, 0, elm->obj->path);
2374 call_init_pointer(elm->obj, init_addr[index]);
2378 wlock_acquire(rtld_bind_lock, lockstate);
2380 errmsg_restore(saved_msg);
2384 objlist_clear(Objlist *list)
2388 while (!STAILQ_EMPTY(list)) {
2389 elm = STAILQ_FIRST(list);
2390 STAILQ_REMOVE_HEAD(list, link);
2395 static Objlist_Entry *
2396 objlist_find(Objlist *list, const Obj_Entry *obj)
2400 STAILQ_FOREACH(elm, list, link)
2401 if (elm->obj == obj)
2407 objlist_init(Objlist *list)
2413 objlist_push_head(Objlist *list, Obj_Entry *obj)
2417 elm = NEW(Objlist_Entry);
2419 STAILQ_INSERT_HEAD(list, elm, link);
2423 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2427 elm = NEW(Objlist_Entry);
2429 STAILQ_INSERT_TAIL(list, elm, link);
2433 objlist_remove(Objlist *list, Obj_Entry *obj)
2437 if ((elm = objlist_find(list, obj)) != NULL) {
2438 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2444 * Relocate newly-loaded shared objects. The argument is a pointer to
2445 * the Obj_Entry for the first such object. All objects from the first
2446 * to the end of the list of objects are relocated. Returns 0 on success,
2450 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2451 int flags, RtldLockState *lockstate)
2455 for (obj = first; obj != NULL; obj = obj->next) {
2458 obj->relocated = true;
2460 dbg("relocating \"%s\"", obj->path);
2462 if (obj->symtab == NULL || obj->strtab == NULL ||
2463 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2464 _rtld_error("%s: Shared object has no run-time symbol table",
2470 /* There are relocations to the write-protected text segment. */
2471 if (mprotect(obj->mapbase, obj->textsize,
2472 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
2473 _rtld_error("%s: Cannot write-enable text segment: %s",
2474 obj->path, rtld_strerror(errno));
2479 /* Process the non-PLT relocations. */
2480 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2484 * Reprotect the text segment. Make sure it is included in the
2485 * core dump since we modified it. This unfortunately causes the
2486 * entire text segment to core-out but we don't have much of a
2487 * choice. We could try to only reenable core dumps on pages
2488 * in which relocations occured but that is likely most of the text
2489 * pages anyway, and even that would not work because the rest of
2490 * the text pages would wind up as a read-only OBJT_DEFAULT object
2491 * (created due to our modifications) backed by the original OBJT_VNODE
2492 * object, and the ELF coredump code is currently only able to dump
2493 * vnode records for pure vnode-backed mappings, not vnode backings
2494 * to memory objects.
2497 madvise(obj->mapbase, obj->textsize, MADV_CORE);
2498 if (mprotect(obj->mapbase, obj->textsize,
2499 PROT_READ|PROT_EXEC) == -1) {
2500 _rtld_error("%s: Cannot write-protect text segment: %s",
2501 obj->path, rtld_strerror(errno));
2507 /* Set the special PLT or GOT entries. */
2510 /* Process the PLT relocations. */
2511 if (reloc_plt(obj) == -1)
2513 /* Relocate the jump slots if we are doing immediate binding. */
2514 if (obj->bind_now || bind_now)
2515 if (reloc_jmpslots(obj, flags, lockstate) == -1)
2519 * Set up the magic number and version in the Obj_Entry. These
2520 * were checked in the crt1.o from the original ElfKit, so we
2521 * set them for backward compatibility.
2523 obj->magic = RTLD_MAGIC;
2524 obj->version = RTLD_VERSION;
2527 * Set relocated data to read-only status if protection specified
2530 if (obj->relro_size) {
2531 if (mprotect(obj->relro_page, obj->relro_size, PROT_READ) == -1) {
2532 _rtld_error("%s: Cannot enforce relro relocation: %s",
2533 obj->path, rtld_strerror(errno));
2543 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2544 * referencing STT_GNU_IFUNC symbols is postponed till the other
2545 * relocations are done. The indirect functions specified as
2546 * ifunc are allowed to call other symbols, so we need to have
2547 * objects relocated before asking for resolution from indirects.
2549 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2550 * instead of the usual lazy handling of PLT slots. It is
2551 * consistent with how GNU does it.
2554 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2555 RtldLockState *lockstate)
2557 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2559 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2560 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2566 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2567 RtldLockState *lockstate)
2571 for (obj = first; obj != NULL; obj = obj->next) {
2572 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2579 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2580 RtldLockState *lockstate)
2584 STAILQ_FOREACH(elm, list, link) {
2585 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2593 * Cleanup procedure. It will be called (by the atexit mechanism) just
2594 * before the process exits.
2599 RtldLockState lockstate;
2601 wlock_acquire(rtld_bind_lock, &lockstate);
2603 objlist_call_fini(&list_fini, NULL, &lockstate);
2604 /* No need to remove the items from the list, since we are exiting. */
2605 if (!libmap_disable)
2607 lock_release(rtld_bind_lock, &lockstate);
2611 path_enumerate(const char *path, path_enum_proc callback, void *arg)
2616 path += strspn(path, ":;");
2617 while (*path != '\0') {
2621 len = strcspn(path, ":;");
2622 res = callback(path, len, arg);
2628 path += strspn(path, ":;");
2634 struct try_library_args {
2642 try_library_path(const char *dir, size_t dirlen, void *param)
2644 struct try_library_args *arg;
2647 if (*dir == '/' || trust) {
2650 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
2653 pathname = arg->buffer;
2654 strncpy(pathname, dir, dirlen);
2655 pathname[dirlen] = '/';
2656 strcpy(pathname + dirlen + 1, arg->name);
2658 dbg(" Trying \"%s\"", pathname);
2659 if (access(pathname, F_OK) == 0) { /* We found it */
2660 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
2661 strcpy(pathname, arg->buffer);
2669 search_library_path(const char *name, const char *path)
2672 struct try_library_args arg;
2678 arg.namelen = strlen(name);
2679 arg.buffer = xmalloc(PATH_MAX);
2680 arg.buflen = PATH_MAX;
2682 p = path_enumerate(path, try_library_path, &arg);
2690 dlclose(void *handle)
2693 RtldLockState lockstate;
2695 wlock_acquire(rtld_bind_lock, &lockstate);
2696 root = dlcheck(handle);
2698 lock_release(rtld_bind_lock, &lockstate);
2701 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
2704 /* Unreference the object and its dependencies. */
2705 root->dl_refcount--;
2707 if (root->refcount == 1) {
2709 * The object will be no longer referenced, so we must unload it.
2710 * First, call the fini functions.
2712 objlist_call_fini(&list_fini, root, &lockstate);
2716 /* Finish cleaning up the newly-unreferenced objects. */
2717 GDB_STATE(RT_DELETE,&root->linkmap);
2718 unload_object(root);
2719 GDB_STATE(RT_CONSISTENT,NULL);
2723 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
2724 lock_release(rtld_bind_lock, &lockstate);
2731 char *msg = error_message;
2732 error_message = NULL;
2737 dlopen(const char *name, int mode)
2740 return (rtld_dlopen(name, -1, mode));
2744 fdlopen(int fd, int mode)
2747 return (rtld_dlopen(NULL, fd, mode));
2751 rtld_dlopen(const char *name, int fd, int mode)
2753 RtldLockState lockstate;
2756 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
2757 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
2758 if (ld_tracing != NULL) {
2759 rlock_acquire(rtld_bind_lock, &lockstate);
2760 if (sigsetjmp(lockstate.env, 0) != 0)
2761 lock_upgrade(rtld_bind_lock, &lockstate);
2762 environ = (char **)*get_program_var_addr("environ", &lockstate);
2763 lock_release(rtld_bind_lock, &lockstate);
2765 lo_flags = RTLD_LO_DLOPEN;
2766 if (mode & RTLD_NODELETE)
2767 lo_flags |= RTLD_LO_NODELETE;
2768 if (mode & RTLD_NOLOAD)
2769 lo_flags |= RTLD_LO_NOLOAD;
2770 if (ld_tracing != NULL)
2771 lo_flags |= RTLD_LO_TRACE;
2773 return (dlopen_object(name, fd, obj_main, lo_flags,
2774 mode & (RTLD_MODEMASK | RTLD_GLOBAL)));
2778 dlopen_cleanup(Obj_Entry *obj)
2783 if (obj->refcount == 0)
2788 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
2791 Obj_Entry **old_obj_tail;
2794 RtldLockState lockstate;
2797 objlist_init(&initlist);
2799 wlock_acquire(rtld_bind_lock, &lockstate);
2800 GDB_STATE(RT_ADD,NULL);
2802 old_obj_tail = obj_tail;
2804 if (name == NULL && fd == -1) {
2808 obj = load_object(name, fd, refobj, lo_flags);
2813 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
2814 objlist_push_tail(&list_global, obj);
2815 if (*old_obj_tail != NULL) { /* We loaded something new. */
2816 assert(*old_obj_tail == obj);
2817 result = load_needed_objects(obj,
2818 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
2822 result = rtld_verify_versions(&obj->dagmembers);
2823 if (result != -1 && ld_tracing)
2825 if (result == -1 || (relocate_objects(obj,
2826 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
2827 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
2828 &lockstate)) == -1) {
2829 dlopen_cleanup(obj);
2831 } else if (lo_flags & RTLD_LO_EARLY) {
2833 * Do not call the init functions for early loaded
2834 * filtees. The image is still not initialized enough
2837 * Our object is found by the global object list and
2838 * will be ordered among all init calls done right
2839 * before transferring control to main.
2842 /* Make list of init functions to call. */
2843 initlist_add_objects(obj, &obj->next, &initlist);
2848 * Bump the reference counts for objects on this DAG. If
2849 * this is the first dlopen() call for the object that was
2850 * already loaded as a dependency, initialize the dag
2856 if ((lo_flags & RTLD_LO_TRACE) != 0)
2859 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
2860 obj->z_nodelete) && !obj->ref_nodel) {
2861 dbg("obj %s nodelete", obj->path);
2863 obj->z_nodelete = obj->ref_nodel = true;
2867 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
2869 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
2871 map_stacks_exec(&lockstate);
2873 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
2874 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
2875 &lockstate) == -1) {
2876 objlist_clear(&initlist);
2877 dlopen_cleanup(obj);
2878 lock_release(rtld_bind_lock, &lockstate);
2882 if (!(lo_flags & RTLD_LO_EARLY)) {
2883 /* Call the init functions. */
2884 objlist_call_init(&initlist, &lockstate);
2886 objlist_clear(&initlist);
2887 lock_release(rtld_bind_lock, &lockstate);
2890 trace_loaded_objects(obj);
2891 lock_release(rtld_bind_lock, &lockstate);
2896 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
2900 const Obj_Entry *obj, *defobj;
2903 RtldLockState lockstate;
2908 symlook_init(&req, name);
2910 req.flags = flags | SYMLOOK_IN_PLT;
2911 req.lockstate = &lockstate;
2913 rlock_acquire(rtld_bind_lock, &lockstate);
2914 if (sigsetjmp(lockstate.env, 0) != 0)
2915 lock_upgrade(rtld_bind_lock, &lockstate);
2916 if (handle == NULL || handle == RTLD_NEXT ||
2917 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
2919 if ((obj = obj_from_addr(retaddr)) == NULL) {
2920 _rtld_error("Cannot determine caller's shared object");
2921 lock_release(rtld_bind_lock, &lockstate);
2924 if (handle == NULL) { /* Just the caller's shared object. */
2925 res = symlook_obj(&req, obj);
2928 defobj = req.defobj_out;
2930 } else if (handle == RTLD_NEXT || /* Objects after caller's */
2931 handle == RTLD_SELF) { /* ... caller included */
2932 if (handle == RTLD_NEXT)
2934 for (; obj != NULL; obj = obj->next) {
2935 res = symlook_obj(&req, obj);
2938 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
2940 defobj = req.defobj_out;
2941 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2947 * Search the dynamic linker itself, and possibly resolve the
2948 * symbol from there. This is how the application links to
2949 * dynamic linker services such as dlopen.
2951 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2952 res = symlook_obj(&req, &obj_rtld);
2953 if (res == 0 && is_exported(req.sym_out)) {
2955 defobj = req.defobj_out;
2959 assert(handle == RTLD_DEFAULT);
2960 res = symlook_default(&req, obj);
2962 defobj = req.defobj_out;
2967 if ((obj = dlcheck(handle)) == NULL) {
2968 lock_release(rtld_bind_lock, &lockstate);
2972 donelist_init(&donelist);
2973 if (obj->mainprog) {
2974 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
2975 res = symlook_global(&req, &donelist);
2978 defobj = req.defobj_out;
2981 * Search the dynamic linker itself, and possibly resolve the
2982 * symbol from there. This is how the application links to
2983 * dynamic linker services such as dlopen.
2985 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2986 res = symlook_obj(&req, &obj_rtld);
2989 defobj = req.defobj_out;
2994 /* Search the whole DAG rooted at the given object. */
2995 res = symlook_list(&req, &obj->dagmembers, &donelist);
2998 defobj = req.defobj_out;
3004 lock_release(rtld_bind_lock, &lockstate);
3007 * The value required by the caller is derived from the value
3008 * of the symbol. For the ia64 architecture, we need to
3009 * construct a function descriptor which the caller can use to
3010 * call the function with the right 'gp' value. For other
3011 * architectures and for non-functions, the value is simply
3012 * the relocated value of the symbol.
3014 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3015 return (make_function_pointer(def, defobj));
3016 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3017 return (rtld_resolve_ifunc(defobj, def));
3018 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3020 ti.ti_module = defobj->tlsindex;
3021 ti.ti_offset = def->st_value;
3022 return (__tls_get_addr(&ti));
3024 return (defobj->relocbase + def->st_value);
3027 _rtld_error("Undefined symbol \"%s\"", name);
3028 lock_release(rtld_bind_lock, &lockstate);
3033 dlsym(void *handle, const char *name)
3035 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3040 dlfunc(void *handle, const char *name)
3047 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3053 dlvsym(void *handle, const char *name, const char *version)
3057 ventry.name = version;
3059 ventry.hash = elf_hash(version);
3061 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3066 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3068 const Obj_Entry *obj;
3069 RtldLockState lockstate;
3071 rlock_acquire(rtld_bind_lock, &lockstate);
3072 obj = obj_from_addr(addr);
3074 _rtld_error("No shared object contains address");
3075 lock_release(rtld_bind_lock, &lockstate);
3078 rtld_fill_dl_phdr_info(obj, phdr_info);
3079 lock_release(rtld_bind_lock, &lockstate);
3084 dladdr(const void *addr, Dl_info *info)
3086 const Obj_Entry *obj;
3089 unsigned long symoffset;
3090 RtldLockState lockstate;
3092 rlock_acquire(rtld_bind_lock, &lockstate);
3093 obj = obj_from_addr(addr);
3095 _rtld_error("No shared object contains address");
3096 lock_release(rtld_bind_lock, &lockstate);
3099 info->dli_fname = obj->path;
3100 info->dli_fbase = obj->mapbase;
3101 info->dli_saddr = NULL;
3102 info->dli_sname = NULL;
3105 * Walk the symbol list looking for the symbol whose address is
3106 * closest to the address sent in.
3108 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3109 def = obj->symtab + symoffset;
3112 * For skip the symbol if st_shndx is either SHN_UNDEF or
3115 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3119 * If the symbol is greater than the specified address, or if it
3120 * is further away from addr than the current nearest symbol,
3123 symbol_addr = obj->relocbase + def->st_value;
3124 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3127 /* Update our idea of the nearest symbol. */
3128 info->dli_sname = obj->strtab + def->st_name;
3129 info->dli_saddr = symbol_addr;
3132 if (info->dli_saddr == addr)
3135 lock_release(rtld_bind_lock, &lockstate);
3140 dlinfo(void *handle, int request, void *p)
3142 const Obj_Entry *obj;
3143 RtldLockState lockstate;
3146 rlock_acquire(rtld_bind_lock, &lockstate);
3148 if (handle == NULL || handle == RTLD_SELF) {
3151 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3152 if ((obj = obj_from_addr(retaddr)) == NULL)
3153 _rtld_error("Cannot determine caller's shared object");
3155 obj = dlcheck(handle);
3158 lock_release(rtld_bind_lock, &lockstate);
3164 case RTLD_DI_LINKMAP:
3165 *((struct link_map const **)p) = &obj->linkmap;
3167 case RTLD_DI_ORIGIN:
3168 error = rtld_dirname(obj->path, p);
3171 case RTLD_DI_SERINFOSIZE:
3172 case RTLD_DI_SERINFO:
3173 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3177 _rtld_error("Invalid request %d passed to dlinfo()", request);
3181 lock_release(rtld_bind_lock, &lockstate);
3187 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3190 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3191 phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ?
3192 STAILQ_FIRST(&obj->names)->name : obj->path;
3193 phdr_info->dlpi_phdr = obj->phdr;
3194 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3195 phdr_info->dlpi_tls_modid = obj->tlsindex;
3196 phdr_info->dlpi_tls_data = obj->tlsinit;
3197 phdr_info->dlpi_adds = obj_loads;
3198 phdr_info->dlpi_subs = obj_loads - obj_count;
3202 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3204 struct dl_phdr_info phdr_info;
3205 const Obj_Entry *obj;
3206 RtldLockState bind_lockstate, phdr_lockstate;
3209 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3210 rlock_acquire(rtld_bind_lock, &bind_lockstate);
3214 for (obj = obj_list; obj != NULL; obj = obj->next) {
3215 rtld_fill_dl_phdr_info(obj, &phdr_info);
3216 if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
3220 lock_release(rtld_bind_lock, &bind_lockstate);
3221 lock_release(rtld_phdr_lock, &phdr_lockstate);
3227 fill_search_info(const char *dir, size_t dirlen, void *param)
3229 struct fill_search_info_args *arg;
3233 if (arg->request == RTLD_DI_SERINFOSIZE) {
3234 arg->serinfo->dls_cnt ++;
3235 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3237 struct dl_serpath *s_entry;
3239 s_entry = arg->serpath;
3240 s_entry->dls_name = arg->strspace;
3241 s_entry->dls_flags = arg->flags;
3243 strncpy(arg->strspace, dir, dirlen);
3244 arg->strspace[dirlen] = '\0';
3246 arg->strspace += dirlen + 1;
3254 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3256 struct dl_serinfo _info;
3257 struct fill_search_info_args args;
3259 args.request = RTLD_DI_SERINFOSIZE;
3260 args.serinfo = &_info;
3262 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3265 path_enumerate(obj->rpath, fill_search_info, &args);
3266 path_enumerate(ld_library_path, fill_search_info, &args);
3267 path_enumerate(obj->runpath, fill_search_info, &args);
3268 path_enumerate(gethints(obj), fill_search_info, &args);
3269 if (!obj->z_nodeflib)
3270 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
3273 if (request == RTLD_DI_SERINFOSIZE) {
3274 info->dls_size = _info.dls_size;
3275 info->dls_cnt = _info.dls_cnt;
3279 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3280 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3284 args.request = RTLD_DI_SERINFO;
3285 args.serinfo = info;
3286 args.serpath = &info->dls_serpath[0];
3287 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3289 args.flags = LA_SER_RUNPATH;
3290 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
3293 args.flags = LA_SER_LIBPATH;
3294 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
3297 args.flags = LA_SER_RUNPATH;
3298 if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
3301 args.flags = LA_SER_CONFIG;
3302 if (path_enumerate(gethints(obj), fill_search_info, &args) != NULL)
3305 args.flags = LA_SER_DEFAULT;
3306 if (!obj->z_nodeflib &&
3307 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
3313 rtld_dirname(const char *path, char *bname)
3317 /* Empty or NULL string gets treated as "." */
3318 if (path == NULL || *path == '\0') {
3324 /* Strip trailing slashes */
3325 endp = path + strlen(path) - 1;
3326 while (endp > path && *endp == '/')
3329 /* Find the start of the dir */
3330 while (endp > path && *endp != '/')
3333 /* Either the dir is "/" or there are no slashes */
3335 bname[0] = *endp == '/' ? '/' : '.';
3341 } while (endp > path && *endp == '/');
3344 if (endp - path + 2 > PATH_MAX)
3346 _rtld_error("Filename is too long: %s", path);
3350 strncpy(bname, path, endp - path + 1);
3351 bname[endp - path + 1] = '\0';
3356 rtld_dirname_abs(const char *path, char *base)
3358 char base_rel[PATH_MAX];
3360 if (rtld_dirname(path, base) == -1)
3364 if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
3365 strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
3366 strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
3368 strcpy(base, base_rel);
3373 linkmap_add(Obj_Entry *obj)
3375 struct link_map *l = &obj->linkmap;
3376 struct link_map *prev;
3378 obj->linkmap.l_name = obj->path;
3379 obj->linkmap.l_addr = obj->mapbase;
3380 obj->linkmap.l_ld = obj->dynamic;
3382 /* GDB needs load offset on MIPS to use the symbols */
3383 obj->linkmap.l_offs = obj->relocbase;
3386 if (r_debug.r_map == NULL) {
3392 * Scan to the end of the list, but not past the entry for the
3393 * dynamic linker, which we want to keep at the very end.
3395 for (prev = r_debug.r_map;
3396 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3397 prev = prev->l_next)
3400 /* Link in the new entry. */
3402 l->l_next = prev->l_next;
3403 if (l->l_next != NULL)
3404 l->l_next->l_prev = l;
3409 linkmap_delete(Obj_Entry *obj)
3411 struct link_map *l = &obj->linkmap;
3413 if (l->l_prev == NULL) {
3414 if ((r_debug.r_map = l->l_next) != NULL)
3415 l->l_next->l_prev = NULL;
3419 if ((l->l_prev->l_next = l->l_next) != NULL)
3420 l->l_next->l_prev = l->l_prev;
3424 * Function for the debugger to set a breakpoint on to gain control.
3426 * The two parameters allow the debugger to easily find and determine
3427 * what the runtime loader is doing and to whom it is doing it.
3429 * When the loadhook trap is hit (r_debug_state, set at program
3430 * initialization), the arguments can be found on the stack:
3432 * +8 struct link_map *m
3433 * +4 struct r_debug *rd
3437 r_debug_state(struct r_debug* rd, struct link_map *m)
3440 * The following is a hack to force the compiler to emit calls to
3441 * this function, even when optimizing. If the function is empty,
3442 * the compiler is not obliged to emit any code for calls to it,
3443 * even when marked __noinline. However, gdb depends on those
3446 __asm __volatile("" : : : "memory");
3450 * Get address of the pointer variable in the main program.
3451 * Prefer non-weak symbol over the weak one.
3453 static const void **
3454 get_program_var_addr(const char *name, RtldLockState *lockstate)
3459 symlook_init(&req, name);
3460 req.lockstate = lockstate;
3461 donelist_init(&donelist);
3462 if (symlook_global(&req, &donelist) != 0)
3464 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
3465 return ((const void **)make_function_pointer(req.sym_out,
3467 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
3468 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
3470 return ((const void **)(req.defobj_out->relocbase + req.sym_out->st_value));
3474 * Set a pointer variable in the main program to the given value. This
3475 * is used to set key variables such as "environ" before any of the
3476 * init functions are called.
3479 set_program_var(const char *name, const void *value)
3483 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
3484 dbg("\"%s\": *%p <-- %p", name, addr, value);
3490 * Search the global objects, including dependencies and main object,
3491 * for the given symbol.
3494 symlook_global(SymLook *req, DoneList *donelist)
3497 const Objlist_Entry *elm;
3500 symlook_init_from_req(&req1, req);
3502 /* Search all objects loaded at program start up. */
3503 if (req->defobj_out == NULL ||
3504 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3505 res = symlook_list(&req1, &list_main, donelist);
3506 if (res == 0 && (req->defobj_out == NULL ||
3507 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3508 req->sym_out = req1.sym_out;
3509 req->defobj_out = req1.defobj_out;
3510 assert(req->defobj_out != NULL);
3514 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
3515 STAILQ_FOREACH(elm, &list_global, link) {
3516 if (req->defobj_out != NULL &&
3517 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3519 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
3520 if (res == 0 && (req->defobj_out == NULL ||
3521 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3522 req->sym_out = req1.sym_out;
3523 req->defobj_out = req1.defobj_out;
3524 assert(req->defobj_out != NULL);
3528 return (req->sym_out != NULL ? 0 : ESRCH);
3532 * This is a special version of getenv which is far more efficient
3533 * at finding LD_ environment vars.
3537 _getenv_ld(const char *id)
3541 int idlen = strlen(id);
3543 if (ld_index == LD_ARY_CACHE)
3545 if (ld_index == 0) {
3546 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
3547 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
3554 for (i = ld_index - 1; i >= 0; --i) {
3555 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
3556 return(ld_ary[i] + idlen + 1);
3562 * Given a symbol name in a referencing object, find the corresponding
3563 * definition of the symbol. Returns a pointer to the symbol, or NULL if
3564 * no definition was found. Returns a pointer to the Obj_Entry of the
3565 * defining object via the reference parameter DEFOBJ_OUT.
3568 symlook_default(SymLook *req, const Obj_Entry *refobj)
3571 const Objlist_Entry *elm;
3575 donelist_init(&donelist);
3576 symlook_init_from_req(&req1, req);
3578 /* Look first in the referencing object if linked symbolically. */
3579 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
3580 res = symlook_obj(&req1, refobj);
3582 req->sym_out = req1.sym_out;
3583 req->defobj_out = req1.defobj_out;
3584 assert(req->defobj_out != NULL);
3588 symlook_global(req, &donelist);
3590 /* Search all dlopened DAGs containing the referencing object. */
3591 STAILQ_FOREACH(elm, &refobj->dldags, link) {
3592 if (req->sym_out != NULL &&
3593 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
3595 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
3596 if (res == 0 && (req->sym_out == NULL ||
3597 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
3598 req->sym_out = req1.sym_out;
3599 req->defobj_out = req1.defobj_out;
3600 assert(req->defobj_out != NULL);
3605 * Search the dynamic linker itself, and possibly resolve the
3606 * symbol from there. This is how the application links to
3607 * dynamic linker services such as dlopen. Only the values listed
3608 * in the "exports" array can be resolved from the dynamic linker.
3610 if (req->sym_out == NULL ||
3611 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
3612 res = symlook_obj(&req1, &obj_rtld);
3613 if (res == 0 && is_exported(req1.sym_out)) {
3614 req->sym_out = req1.sym_out;
3615 req->defobj_out = req1.defobj_out;
3616 assert(req->defobj_out != NULL);
3620 return (req->sym_out != NULL ? 0 : ESRCH);
3624 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
3627 const Obj_Entry *defobj;
3628 const Objlist_Entry *elm;
3634 STAILQ_FOREACH(elm, objlist, link) {
3635 if (donelist_check(dlp, elm->obj))
3637 symlook_init_from_req(&req1, req);
3638 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
3639 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3641 defobj = req1.defobj_out;
3642 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3649 req->defobj_out = defobj;
3656 * Search the chain of DAGS cointed to by the given Needed_Entry
3657 * for a symbol of the given name. Each DAG is scanned completely
3658 * before advancing to the next one. Returns a pointer to the symbol,
3659 * or NULL if no definition was found.
3662 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
3665 const Needed_Entry *n;
3666 const Obj_Entry *defobj;
3672 symlook_init_from_req(&req1, req);
3673 for (n = needed; n != NULL; n = n->next) {
3674 if (n->obj == NULL ||
3675 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
3677 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
3679 defobj = req1.defobj_out;
3680 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3686 req->defobj_out = defobj;
3693 * Search the symbol table of a single shared object for a symbol of
3694 * the given name and version, if requested. Returns a pointer to the
3695 * symbol, or NULL if no definition was found. If the object is
3696 * filter, return filtered symbol from filtee.
3698 * The symbol's hash value is passed in for efficiency reasons; that
3699 * eliminates many recomputations of the hash value.
3702 symlook_obj(SymLook *req, const Obj_Entry *obj)
3706 int flags, res, mres;
3709 * There is at least one valid hash at this point, and we prefer to use
3710 * the faster GNU version if available.
3712 if (obj->valid_hash_gnu)
3713 mres = symlook_obj2(req, obj);
3715 mres = symlook_obj1(req, obj);
3718 if (obj->needed_filtees != NULL) {
3719 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3720 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3721 donelist_init(&donelist);
3722 symlook_init_from_req(&req1, req);
3723 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
3725 req->sym_out = req1.sym_out;
3726 req->defobj_out = req1.defobj_out;
3730 if (obj->needed_aux_filtees != NULL) {
3731 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
3732 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
3733 donelist_init(&donelist);
3734 symlook_init_from_req(&req1, req);
3735 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
3737 req->sym_out = req1.sym_out;
3738 req->defobj_out = req1.defobj_out;
3746 /* Symbol match routine common to both hash functions */
3748 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
3749 const unsigned long symnum)
3752 const Elf_Sym *symp = obj->symtab + symnum;
3753 const char *strp = obj->strtab + symp->st_name;
3755 switch (ELF_ST_TYPE(symp->st_info)) {
3761 if (symp->st_value == 0)
3765 if (symp->st_shndx != SHN_UNDEF)
3767 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
3768 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
3774 if (strcmp(req->name, strp) != 0)
3777 if (req->ventry == NULL) {
3778 if (obj->versyms != NULL) {
3779 verndx = VER_NDX(obj->versyms[symnum]);
3780 if (verndx > obj->vernum) {
3781 _rtld_error("%s: symbol %s references wrong version %d",
3782 obj->path, obj->strtab + symnum, verndx);
3786 * If we are not called from dlsym (i.e. this is a normal relocation
3787 * from unversioned binary), accept the symbol immediately if it happens
3788 * to have first version after this shared object became versioned.
3789 * Otherwise, if symbol is versioned and not hidden, remember it. If it
3790 * is the only symbol with this name exported by the shared object, it
3791 * will be returned as a match by the calling function. If symbol is
3792 * global (verndx < 2) accept it unconditionally.
3794 if ((req->flags & SYMLOOK_DLSYM) == 0 && verndx == VER_NDX_GIVEN) {
3795 result->sym_out = symp;
3798 else if (verndx >= VER_NDX_GIVEN) {
3799 if ((obj->versyms[symnum] & VER_NDX_HIDDEN) == 0) {
3800 if (result->vsymp == NULL)
3801 result->vsymp = symp;
3807 result->sym_out = symp;
3810 if (obj->versyms == NULL) {
3811 if (object_match_name(obj, req->ventry->name)) {
3812 _rtld_error("%s: object %s should provide version %s for "
3813 "symbol %s", obj_rtld.path, obj->path,
3814 req->ventry->name, obj->strtab + symnum);
3818 verndx = VER_NDX(obj->versyms[symnum]);
3819 if (verndx > obj->vernum) {
3820 _rtld_error("%s: symbol %s references wrong version %d",
3821 obj->path, obj->strtab + symnum, verndx);
3824 if (obj->vertab[verndx].hash != req->ventry->hash ||
3825 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
3827 * Version does not match. Look if this is a global symbol and if it is
3828 * not hidden. If global symbol (verndx < 2) is available, use it. Do not
3829 * return symbol if we are called by dlvsym, because dlvsym looks for a
3830 * specific version and default one is not what dlvsym wants.
3832 if ((req->flags & SYMLOOK_DLSYM) || (verndx >= VER_NDX_GIVEN) ||
3833 (obj->versyms[symnum] & VER_NDX_HIDDEN))
3837 result->sym_out = symp;
3842 * Search for symbol using SysV hash function.
3843 * obj->buckets is known not to be NULL at this point; the test for this was
3844 * performed with the obj->valid_hash_sysv assignment.
3847 symlook_obj1(SymLook *req, const Obj_Entry *obj)
3849 unsigned long symnum;
3850 Sym_Match_Result matchres;
3852 matchres.sym_out = NULL;
3853 matchres.vsymp = NULL;
3854 matchres.vcount = 0;
3856 for (symnum = obj->buckets[req->hash % obj->nbuckets];
3857 symnum != STN_UNDEF;
3858 symnum = obj->chains[symnum]) {
3860 if (symnum >= obj->nchains)
3861 return (ESRCH); /* Bad object */
3863 if (matched_symbol(req, obj, &matchres, symnum)) {
3864 req->sym_out = matchres.sym_out;
3865 req->defobj_out = obj;
3869 if (matchres.vcount == 1) {
3870 req->sym_out = matchres.vsymp;
3871 req->defobj_out = obj;
3877 /* Search for symbol using GNU hash function */
3879 symlook_obj2(SymLook *req, const Obj_Entry *obj)
3881 Elf_Addr bloom_word;
3883 unsigned int h1, h2;
3884 unsigned long symnum;
3885 const int c = __ELF_WORD_SIZE;
3886 Sym_Match_Result matchres;
3888 matchres.sym_out = NULL;
3889 matchres.vsymp = NULL;
3890 matchres.vcount = 0;
3892 /* pick right bitmask word from Bloom filter array*/
3893 bloom_word = obj->bloom_gnu[(req->hash_gnu / c) & obj->maskwords_bm_gnu];
3895 /* calculate modulus 32 (64 for x86_64) of gnu hash and its derivative */
3896 h1 = req->hash_gnu & (c - 1);
3897 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (c - 1));
3899 /* Filter out the "definitely not in set" queries */
3900 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
3903 /* Locate hash chain and corresponding value element*/
3904 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
3907 const Elf32_Word *hashval = &obj->chain_zero_gnu[bucket];
3909 if (((*hashval ^ req->hash_gnu) >> 1) == 0)
3911 symnum = hashval - obj->chain_zero_gnu;
3912 if (matched_symbol(req, obj, &matchres, symnum)) {
3913 req->sym_out = matchres.sym_out;
3914 req->defobj_out = obj;
3918 while ((*hashval++ & 1u) == 0);
3919 if (matchres.vcount == 1) {
3920 req->sym_out = matchres.vsymp;
3921 req->defobj_out = obj;
3928 trace_loaded_objects(Obj_Entry *obj)
3930 const char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
3933 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
3936 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
3937 fmt1 = "\t%o => %p (%x)\n";
3939 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
3940 fmt2 = "\t%o (%x)\n";
3942 list_containers = _getenv_ld("LD_TRACE_LOADED_OBJECTS_ALL");
3944 for (; obj; obj = obj->next) {
3945 Needed_Entry *needed;
3949 if (list_containers && obj->needed != NULL)
3950 rtld_printf("%s:\n", obj->path);
3951 for (needed = obj->needed; needed; needed = needed->next) {
3952 if (needed->obj != NULL) {
3953 if (needed->obj->traced && !list_containers)
3955 needed->obj->traced = true;
3956 path = needed->obj->path;
3960 name = (char *)obj->strtab + needed->name;
3961 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
3963 fmt = is_lib ? fmt1 : fmt2;
3964 while ((c = *fmt++) != '\0') {
3990 rtld_putstr(main_local);
3993 rtld_putstr(obj_main->path);
4002 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4015 * Unload a dlopened object and its dependencies from memory and from
4016 * our data structures. It is assumed that the DAG rooted in the
4017 * object has already been unreferenced, and that the object has a
4018 * reference count of 0.
4021 unload_object(Obj_Entry *root)
4026 assert(root->refcount == 0);
4029 * Pass over the DAG removing unreferenced objects from
4030 * appropriate lists.
4032 unlink_object(root);
4034 /* Unmap all objects that are no longer referenced. */
4035 linkp = &obj_list->next;
4036 while ((obj = *linkp) != NULL) {
4037 if (obj->refcount == 0) {
4038 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
4040 dbg("unloading \"%s\"", obj->path);
4041 unload_filtees(root);
4042 munmap(obj->mapbase, obj->mapsize);
4043 linkmap_delete(obj);
4054 unlink_object(Obj_Entry *root)
4058 if (root->refcount == 0) {
4059 /* Remove the object from the RTLD_GLOBAL list. */
4060 objlist_remove(&list_global, root);
4062 /* Remove the object from all objects' DAG lists. */
4063 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4064 objlist_remove(&elm->obj->dldags, root);
4065 if (elm->obj != root)
4066 unlink_object(elm->obj);
4072 ref_dag(Obj_Entry *root)
4076 assert(root->dag_inited);
4077 STAILQ_FOREACH(elm, &root->dagmembers, link)
4078 elm->obj->refcount++;
4082 unref_dag(Obj_Entry *root)
4086 assert(root->dag_inited);
4087 STAILQ_FOREACH(elm, &root->dagmembers, link)
4088 elm->obj->refcount--;
4092 * Common code for MD __tls_get_addr().
4095 tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset)
4097 Elf_Addr* dtv = *dtvp;
4098 RtldLockState lockstate;
4100 /* Check dtv generation in case new modules have arrived */
4101 if (dtv[0] != tls_dtv_generation) {
4105 wlock_acquire(rtld_bind_lock, &lockstate);
4106 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4108 if (to_copy > tls_max_index)
4109 to_copy = tls_max_index;
4110 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4111 newdtv[0] = tls_dtv_generation;
4112 newdtv[1] = tls_max_index;
4114 lock_release(rtld_bind_lock, &lockstate);
4115 dtv = *dtvp = newdtv;
4118 /* Dynamically allocate module TLS if necessary */
4119 if (!dtv[index + 1]) {
4120 /* Signal safe, wlock will block out signals. */
4121 wlock_acquire(rtld_bind_lock, &lockstate);
4122 if (!dtv[index + 1])
4123 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4124 lock_release(rtld_bind_lock, &lockstate);
4126 return (void*) (dtv[index + 1] + offset);
4129 #if defined(RTLD_STATIC_TLS_VARIANT_II)
4132 * Allocate the static TLS area. Return a pointer to the TCB. The
4133 * static area is based on negative offsets relative to the tcb.
4135 * The TCB contains an errno pointer for the system call layer, but because
4136 * we are the RTLD we really have no idea how the caller was compiled so
4137 * the information has to be passed in. errno can either be:
4139 * type 0 errno is a simple non-TLS global pointer.
4140 * (special case for e.g. libc_rtld)
4141 * type 1 errno accessed by GOT entry (dynamically linked programs)
4142 * type 2 errno accessed by %gs:OFFSET (statically linked programs)
4145 allocate_tls(Obj_Entry *objs)
4150 struct tls_tcb *tcb;
4155 * Allocate the new TCB. static TLS storage is placed just before the
4156 * TCB to support the %gs:OFFSET (negative offset) model.
4158 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4159 ~RTLD_STATIC_TLS_ALIGN_MASK;
4160 tcb = malloc(data_size + sizeof(*tcb));
4161 tcb = (void *)((char *)tcb + data_size); /* actual tcb location */
4163 dtv_size = (tls_max_index + 2) * sizeof(Elf_Addr);
4164 dtv = malloc(dtv_size);
4165 bzero(dtv, dtv_size);
4167 #ifdef RTLD_TCB_HAS_SELF_POINTER
4168 tcb->tcb_self = tcb;
4171 tcb->tcb_pthread = NULL;
4173 dtv[0] = tls_dtv_generation;
4174 dtv[1] = tls_max_index;
4176 for (obj = objs; obj; obj = obj->next) {
4177 if (obj->tlsoffset) {
4178 addr = (Elf_Addr)tcb - obj->tlsoffset;
4179 memset((void *)(addr + obj->tlsinitsize),
4180 0, obj->tlssize - obj->tlsinitsize);
4182 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4183 dtv[obj->tlsindex + 1] = addr;
4190 free_tls(struct tls_tcb *tcb)
4194 Elf_Addr tls_start, tls_end;
4197 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
4198 ~RTLD_STATIC_TLS_ALIGN_MASK;
4202 tls_end = (Elf_Addr)tcb;
4203 tls_start = (Elf_Addr)tcb - data_size;
4204 for (i = 0; i < dtv_size; i++) {
4205 if (dtv[i+2] != 0 && (dtv[i+2] < tls_start || dtv[i+2] > tls_end)) {
4206 free((void *)dtv[i+2]);
4210 free((void*) tls_start);
4214 #error "Unsupported TLS layout"
4218 * Allocate TLS block for module with given index.
4221 allocate_module_tls(int index)
4226 for (obj = obj_list; obj; obj = obj->next) {
4227 if (obj->tlsindex == index)
4231 _rtld_error("Can't find module with TLS index %d", index);
4235 p = malloc(obj->tlssize);
4237 _rtld_error("Cannot allocate TLS block for index %d", index);
4240 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4241 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4247 allocate_tls_offset(Obj_Entry *obj)
4254 if (obj->tlssize == 0) {
4255 obj->tls_done = true;
4259 if (obj->tlsindex == 1)
4260 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4262 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4263 obj->tlssize, obj->tlsalign);
4266 * If we have already fixed the size of the static TLS block, we
4267 * must stay within that size. When allocating the static TLS, we
4268 * leave a small amount of space spare to be used for dynamically
4269 * loading modules which use static TLS.
4271 if (tls_static_space) {
4272 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4276 tls_last_offset = obj->tlsoffset = off;
4277 tls_last_size = obj->tlssize;
4278 obj->tls_done = true;
4284 free_tls_offset(Obj_Entry *obj)
4286 #ifdef RTLD_STATIC_TLS_VARIANT_II
4288 * If we were the last thing to allocate out of the static TLS
4289 * block, we give our space back to the 'allocator'. This is a
4290 * simplistic workaround to allow libGL.so.1 to be loaded and
4291 * unloaded multiple times. We only handle the Variant II
4292 * mechanism for now - this really needs a proper allocator.
4294 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
4295 == calculate_tls_end(tls_last_offset, tls_last_size)) {
4296 tls_last_offset -= obj->tlssize;
4303 _rtld_allocate_tls(void)
4305 struct tls_tcb *new_tcb;
4306 RtldLockState lockstate;
4308 wlock_acquire(rtld_bind_lock, &lockstate);
4309 new_tcb = allocate_tls(obj_list);
4310 lock_release(rtld_bind_lock, &lockstate);
4315 _rtld_free_tls(struct tls_tcb *tcb)
4317 RtldLockState lockstate;
4319 wlock_acquire(rtld_bind_lock, &lockstate);
4321 lock_release(rtld_bind_lock, &lockstate);
4325 object_add_name(Obj_Entry *obj, const char *name)
4331 entry = malloc(sizeof(Name_Entry) + len);
4333 if (entry != NULL) {
4334 strcpy(entry->name, name);
4335 STAILQ_INSERT_TAIL(&obj->names, entry, link);
4340 object_match_name(const Obj_Entry *obj, const char *name)
4344 STAILQ_FOREACH(entry, &obj->names, link) {
4345 if (strcmp(name, entry->name) == 0)
4352 locate_dependency(const Obj_Entry *obj, const char *name)
4354 const Objlist_Entry *entry;
4355 const Needed_Entry *needed;
4357 STAILQ_FOREACH(entry, &list_main, link) {
4358 if (object_match_name(entry->obj, name))
4362 for (needed = obj->needed; needed != NULL; needed = needed->next) {
4363 if (strcmp(obj->strtab + needed->name, name) == 0 ||
4364 (needed->obj != NULL && object_match_name(needed->obj, name))) {
4366 * If there is DT_NEEDED for the name we are looking for,
4367 * we are all set. Note that object might not be found if
4368 * dependency was not loaded yet, so the function can
4369 * return NULL here. This is expected and handled
4370 * properly by the caller.
4372 return (needed->obj);
4375 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
4381 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
4382 const Elf_Vernaux *vna)
4384 const Elf_Verdef *vd;
4385 const char *vername;
4387 vername = refobj->strtab + vna->vna_name;
4388 vd = depobj->verdef;
4390 _rtld_error("%s: version %s required by %s not defined",
4391 depobj->path, vername, refobj->path);
4395 if (vd->vd_version != VER_DEF_CURRENT) {
4396 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4397 depobj->path, vd->vd_version);
4400 if (vna->vna_hash == vd->vd_hash) {
4401 const Elf_Verdaux *aux = (const Elf_Verdaux *)
4402 ((char *)vd + vd->vd_aux);
4403 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
4406 if (vd->vd_next == 0)
4408 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4410 if (vna->vna_flags & VER_FLG_WEAK)
4412 _rtld_error("%s: version %s required by %s not found",
4413 depobj->path, vername, refobj->path);
4418 rtld_verify_object_versions(Obj_Entry *obj)
4420 const Elf_Verneed *vn;
4421 const Elf_Verdef *vd;
4422 const Elf_Verdaux *vda;
4423 const Elf_Vernaux *vna;
4424 const Obj_Entry *depobj;
4425 int maxvernum, vernum;
4427 if (obj->ver_checked)
4429 obj->ver_checked = true;
4433 * Walk over defined and required version records and figure out
4434 * max index used by any of them. Do very basic sanity checking
4438 while (vn != NULL) {
4439 if (vn->vn_version != VER_NEED_CURRENT) {
4440 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
4441 obj->path, vn->vn_version);
4444 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4446 vernum = VER_NEED_IDX(vna->vna_other);
4447 if (vernum > maxvernum)
4449 if (vna->vna_next == 0)
4451 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4453 if (vn->vn_next == 0)
4455 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4459 while (vd != NULL) {
4460 if (vd->vd_version != VER_DEF_CURRENT) {
4461 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
4462 obj->path, vd->vd_version);
4465 vernum = VER_DEF_IDX(vd->vd_ndx);
4466 if (vernum > maxvernum)
4468 if (vd->vd_next == 0)
4470 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4477 * Store version information in array indexable by version index.
4478 * Verify that object version requirements are satisfied along the
4481 obj->vernum = maxvernum + 1;
4482 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
4485 while (vd != NULL) {
4486 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
4487 vernum = VER_DEF_IDX(vd->vd_ndx);
4488 assert(vernum <= maxvernum);
4489 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
4490 obj->vertab[vernum].hash = vd->vd_hash;
4491 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
4492 obj->vertab[vernum].file = NULL;
4493 obj->vertab[vernum].flags = 0;
4495 if (vd->vd_next == 0)
4497 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
4501 while (vn != NULL) {
4502 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
4505 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
4507 if (check_object_provided_version(obj, depobj, vna))
4509 vernum = VER_NEED_IDX(vna->vna_other);
4510 assert(vernum <= maxvernum);
4511 obj->vertab[vernum].hash = vna->vna_hash;
4512 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
4513 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
4514 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
4515 VER_INFO_HIDDEN : 0;
4516 if (vna->vna_next == 0)
4518 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
4520 if (vn->vn_next == 0)
4522 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
4528 rtld_verify_versions(const Objlist *objlist)
4530 Objlist_Entry *entry;
4534 STAILQ_FOREACH(entry, objlist, link) {
4536 * Skip dummy objects or objects that have their version requirements
4539 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
4541 if (rtld_verify_object_versions(entry->obj) == -1) {
4543 if (ld_tracing == NULL)
4547 if (rc == 0 || ld_tracing != NULL)
4548 rc = rtld_verify_object_versions(&obj_rtld);
4553 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
4558 vernum = VER_NDX(obj->versyms[symnum]);
4559 if (vernum >= obj->vernum) {
4560 _rtld_error("%s: symbol %s has wrong verneed value %d",
4561 obj->path, obj->strtab + symnum, vernum);
4562 } else if (obj->vertab[vernum].hash != 0) {
4563 return &obj->vertab[vernum];
4570 _rtld_get_stack_prot(void)
4573 return (stack_prot);
4577 map_stacks_exec(RtldLockState *lockstate)
4581 * Stack protection must be implemented in the kernel before the dynamic
4582 * linker can handle PT_GNU_STACK sections.
4583 * The following is the FreeBSD implementation of map_stacks_exec()
4584 * void (*thr_map_stacks_exec)(void);
4586 * if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
4588 * thr_map_stacks_exec = (void (*)(void))(uintptr_t)
4589 * get_program_var_addr("__pthread_map_stacks_exec", lockstate);
4590 * if (thr_map_stacks_exec != NULL) {
4591 * stack_prot |= PROT_EXEC;
4592 * thr_map_stacks_exec();
4598 symlook_init(SymLook *dst, const char *name)
4601 bzero(dst, sizeof(*dst));
4603 dst->hash = elf_hash(name);
4604 dst->hash_gnu = gnu_hash(name);
4608 symlook_init_from_req(SymLook *dst, const SymLook *src)
4611 dst->name = src->name;
4612 dst->hash = src->hash;
4613 dst->hash_gnu = src->hash_gnu;
4614 dst->ventry = src->ventry;
4615 dst->flags = src->flags;
4616 dst->defobj_out = NULL;
4617 dst->sym_out = NULL;
4618 dst->lockstate = src->lockstate;
4621 #ifdef ENABLE_OSRELDATE
4623 * Overrides for libc_pic-provided functions.
4627 __getosreldate(void)
4637 oid[1] = KERN_OSRELDATE;
4639 len = sizeof(osrel);
4640 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
4641 if (error == 0 && osrel > 0 && len == sizeof(osrel))
4648 * No unresolved symbols for rtld.
4651 __pthread_cxa_finalize(struct dl_phdr_info *a)
4656 rtld_strerror(int errnum)
4659 if (errnum < 0 || errnum >= sys_nerr)
4660 return ("Unknown error");
4661 return (sys_errlist[errnum]);