2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
5 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
6 * Copyright 2009-2013 Konstantin Belousov <kib@FreeBSD.ORG>.
7 * Copyright 2012 John Marino <draco@marino.st>.
8 * Copyright 2014-2017 The FreeBSD Foundation
11 * Portions of this software were developed by Konstantin Belousov
12 * under sponsorship from the FreeBSD Foundation.
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 * Dynamic linker for ELF.
38 * John Polstra <jdp@polstra.com>.
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
44 #include <sys/param.h>
45 #include <sys/mount.h>
48 #include <sys/sysctl.h>
50 #include <sys/utsname.h>
51 #include <sys/ktrace.h>
68 #include "rtld_printf.h"
69 #include "rtld_utrace.h"
73 typedef void (*func_ptr_type)();
74 typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
77 * Function declarations.
79 static const char *basename(const char *);
80 static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
81 const Elf_Dyn **, const Elf_Dyn **);
82 static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
84 static void digest_dynamic(Obj_Entry *, int);
85 static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
86 static Obj_Entry *dlcheck(void *);
87 static int dlclose_locked(void *, RtldLockState *);
88 static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
89 int lo_flags, int mode, RtldLockState *lockstate);
90 static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
91 static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
92 static bool donelist_check(DoneList *, const Obj_Entry *);
93 static void errmsg_restore(char *);
94 static char *errmsg_save(void);
95 static void *fill_search_info(const char *, size_t, void *);
96 static char *find_library(const char *, const Obj_Entry *, int *);
97 static const char *gethints(bool);
98 static void hold_object(Obj_Entry *);
99 static void unhold_object(Obj_Entry *);
100 static void init_dag(Obj_Entry *);
101 static void init_marker(Obj_Entry *);
102 static void init_pagesizes(Elf_Auxinfo **aux_info);
103 static void init_rtld(caddr_t, Elf_Auxinfo **);
104 static void initlist_add_neededs(Needed_Entry *, Objlist *);
105 static void initlist_add_objects(Obj_Entry *, Obj_Entry *, Objlist *);
106 static void linkmap_add(Obj_Entry *);
107 static void linkmap_delete(Obj_Entry *);
108 static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
109 static void unload_filtees(Obj_Entry *, RtldLockState *);
110 static int load_needed_objects(Obj_Entry *, int);
111 static int load_preload_objects(void);
112 static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int);
113 static void map_stacks_exec(RtldLockState *);
114 static int obj_enforce_relro(Obj_Entry *);
115 static Obj_Entry *obj_from_addr(const void *);
116 static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
117 static void objlist_call_init(Objlist *, RtldLockState *);
118 static void objlist_clear(Objlist *);
119 static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
120 static void objlist_init(Objlist *);
121 static void objlist_push_head(Objlist *, Obj_Entry *);
122 static void objlist_push_tail(Objlist *, Obj_Entry *);
123 static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
124 static void objlist_remove(Objlist *, Obj_Entry *);
125 static int open_binary_fd(const char *argv0, bool search_in_path);
126 static int parse_args(char* argv[], int argc, bool *use_pathp, int *fdp);
127 static int parse_integer(const char *);
128 static void *path_enumerate(const char *, path_enum_proc, const char *, void *);
129 static void print_usage(const char *argv0);
130 static void release_object(Obj_Entry *);
131 static int relocate_object_dag(Obj_Entry *root, bool bind_now,
132 Obj_Entry *rtldobj, int flags, RtldLockState *lockstate);
133 static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
134 int flags, RtldLockState *lockstate);
135 static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
137 static int resolve_object_ifunc(Obj_Entry *, bool, int, RtldLockState *);
138 static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
139 int flags, RtldLockState *lockstate);
140 static int rtld_dirname(const char *, char *);
141 static int rtld_dirname_abs(const char *, char *);
142 static void *rtld_dlopen(const char *name, int fd, int mode);
143 static void rtld_exit(void);
144 static char *search_library_path(const char *, const char *, const char *,
146 static char *search_library_pathfds(const char *, const char *, int *);
147 static const void **get_program_var_addr(const char *, RtldLockState *);
148 static void set_program_var(const char *, const void *);
149 static int symlook_default(SymLook *, const Obj_Entry *refobj);
150 static int symlook_global(SymLook *, DoneList *);
151 static void symlook_init_from_req(SymLook *, const SymLook *);
152 static int symlook_list(SymLook *, const Objlist *, DoneList *);
153 static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
154 static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
155 static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
156 static void trace_loaded_objects(Obj_Entry *);
157 static void unlink_object(Obj_Entry *);
158 static void unload_object(Obj_Entry *, RtldLockState *lockstate);
159 static void unref_dag(Obj_Entry *);
160 static void ref_dag(Obj_Entry *);
161 static char *origin_subst_one(Obj_Entry *, char *, const char *,
163 static char *origin_subst(Obj_Entry *, char *);
164 static bool obj_resolve_origin(Obj_Entry *obj);
165 static void preinit_main(void);
166 static int rtld_verify_versions(const Objlist *);
167 static int rtld_verify_object_versions(Obj_Entry *);
168 static void object_add_name(Obj_Entry *, const char *);
169 static int object_match_name(const Obj_Entry *, const char *);
170 static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
171 static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
172 struct dl_phdr_info *phdr_info);
173 static uint32_t gnu_hash(const char *);
174 static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
175 const unsigned long);
177 void r_debug_state(struct r_debug *, struct link_map *) __noinline __exported;
178 void _r_debug_postinit(struct link_map *) __noinline __exported;
180 int __sys_openat(int, const char *, int, ...);
185 static char *error_message; /* Message for dlerror(), or NULL */
186 struct r_debug r_debug __exported; /* for GDB; */
187 static bool libmap_disable; /* Disable libmap */
188 static bool ld_loadfltr; /* Immediate filters processing */
189 static char *libmap_override; /* Maps to use in addition to libmap.conf */
190 static bool trust; /* False for setuid and setgid programs */
191 static bool dangerous_ld_env; /* True if environment variables have been
192 used to affect the libraries loaded */
193 bool ld_bind_not; /* Disable PLT update */
194 static char *ld_bind_now; /* Environment variable for immediate binding */
195 static char *ld_debug; /* Environment variable for debugging */
196 static char *ld_library_path; /* Environment variable for search path */
197 static char *ld_library_dirs; /* Environment variable for library descriptors */
198 static char *ld_preload; /* Environment variable for libraries to
200 static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
201 static char *ld_tracing; /* Called from ldd to print libs */
202 static char *ld_utrace; /* Use utrace() to log events. */
203 static struct obj_entry_q obj_list; /* Queue of all loaded objects */
204 static Obj_Entry *obj_main; /* The main program shared object */
205 static Obj_Entry obj_rtld; /* The dynamic linker shared object */
206 static unsigned int obj_count; /* Number of objects in obj_list */
207 static unsigned int obj_loads; /* Number of loads of objects (gen count) */
209 static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
210 STAILQ_HEAD_INITIALIZER(list_global);
211 static Objlist list_main = /* Objects loaded at program startup */
212 STAILQ_HEAD_INITIALIZER(list_main);
213 static Objlist list_fini = /* Objects needing fini() calls */
214 STAILQ_HEAD_INITIALIZER(list_fini);
216 Elf_Sym sym_zero; /* For resolving undefined weak refs. */
218 #define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
220 extern Elf_Dyn _DYNAMIC;
221 #pragma weak _DYNAMIC
223 int dlclose(void *) __exported;
224 char *dlerror(void) __exported;
225 void *dlopen(const char *, int) __exported;
226 void *fdlopen(int, int) __exported;
227 void *dlsym(void *, const char *) __exported;
228 dlfunc_t dlfunc(void *, const char *) __exported;
229 void *dlvsym(void *, const char *, const char *) __exported;
230 int dladdr(const void *, Dl_info *) __exported;
231 void dllockinit(void *, void *(*)(void *), void (*)(void *), void (*)(void *),
232 void (*)(void *), void (*)(void *), void (*)(void *)) __exported;
233 int dlinfo(void *, int , void *) __exported;
234 int dl_iterate_phdr(__dl_iterate_hdr_callback, void *) __exported;
235 int _rtld_addr_phdr(const void *, struct dl_phdr_info *) __exported;
236 int _rtld_get_stack_prot(void) __exported;
237 int _rtld_is_dlopened(void *) __exported;
238 void _rtld_error(const char *, ...) __exported;
240 int npagesizes, osreldate;
243 static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
244 static int max_stack_flags;
247 * Global declarations normally provided by crt1. The dynamic linker is
248 * not built with crt1, so we have to provide them ourselves.
254 * Used to pass argc, argv to init functions.
260 * Globals to control TLS allocation.
262 size_t tls_last_offset; /* Static TLS offset of last module */
263 size_t tls_last_size; /* Static TLS size of last module */
264 size_t tls_static_space; /* Static TLS space allocated */
265 size_t tls_static_max_align;
266 int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
267 int tls_max_index = 1; /* Largest module index allocated */
269 bool ld_library_path_rpath = false;
272 * Globals for path names, and such
274 char *ld_elf_hints_default = _PATH_ELF_HINTS;
275 char *ld_path_libmap_conf = _PATH_LIBMAP_CONF;
276 char *ld_path_rtld = _PATH_RTLD;
277 char *ld_standard_library_path = STANDARD_LIBRARY_PATH;
278 char *ld_env_prefix = LD_;
281 * Fill in a DoneList with an allocation large enough to hold all of
282 * the currently-loaded objects. Keep this as a macro since it calls
283 * alloca and we want that to occur within the scope of the caller.
285 #define donelist_init(dlp) \
286 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
287 assert((dlp)->objs != NULL), \
288 (dlp)->num_alloc = obj_count, \
291 #define LD_UTRACE(e, h, mb, ms, r, n) do { \
292 if (ld_utrace != NULL) \
293 ld_utrace_log(e, h, mb, ms, r, n); \
297 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
298 int refcnt, const char *name)
300 struct utrace_rtld ut;
301 static const char rtld_utrace_sig[RTLD_UTRACE_SIG_SZ] = RTLD_UTRACE_SIG;
303 memcpy(ut.sig, rtld_utrace_sig, sizeof(ut.sig));
306 ut.mapbase = mapbase;
307 ut.mapsize = mapsize;
309 bzero(ut.name, sizeof(ut.name));
311 strlcpy(ut.name, name, sizeof(ut.name));
312 utrace(&ut, sizeof(ut));
315 #ifdef RTLD_VARIANT_ENV_NAMES
317 * construct the env variable based on the type of binary that's
320 static inline const char *
323 static char buffer[128];
325 strlcpy(buffer, ld_env_prefix, sizeof(buffer));
326 strlcat(buffer, var, sizeof(buffer));
334 * Main entry point for dynamic linking. The first argument is the
335 * stack pointer. The stack is expected to be laid out as described
336 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
337 * Specifically, the stack pointer points to a word containing
338 * ARGC. Following that in the stack is a null-terminated sequence
339 * of pointers to argument strings. Then comes a null-terminated
340 * sequence of pointers to environment strings. Finally, there is a
341 * sequence of "auxiliary vector" entries.
343 * The second argument points to a place to store the dynamic linker's
344 * exit procedure pointer and the third to a place to store the main
347 * The return value is the main program's entry point.
350 _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
352 Elf_Auxinfo *aux, *auxp, *auxpf, *aux_info[AT_COUNT];
353 Objlist_Entry *entry;
354 Obj_Entry *last_interposer, *obj, *preload_tail;
355 const Elf_Phdr *phdr;
357 RtldLockState lockstate;
360 char **argv, *argv0, **env, **envp, *kexecpath, *library_path_rpath;
362 char buf[MAXPATHLEN];
363 int argc, fd, i, phnum, rtld_argc;
364 bool dir_enable, explicit_fd, search_in_path;
367 * On entry, the dynamic linker itself has not been relocated yet.
368 * Be very careful not to reference any global data until after
369 * init_rtld has returned. It is OK to reference file-scope statics
370 * and string constants, and to call static and global functions.
373 /* Find the auxiliary vector on the stack. */
377 sp += argc + 1; /* Skip over arguments and NULL terminator */
379 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
381 aux = (Elf_Auxinfo *) sp;
383 /* Digest the auxiliary vector. */
384 for (i = 0; i < AT_COUNT; i++)
386 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
387 if (auxp->a_type < AT_COUNT)
388 aux_info[auxp->a_type] = auxp;
391 /* Initialize and relocate ourselves. */
392 assert(aux_info[AT_BASE] != NULL);
393 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
395 __progname = obj_rtld.path;
396 argv0 = argv[0] != NULL ? argv[0] : "(null)";
401 trust = !issetugid();
403 md_abi_variant_hook(aux_info);
406 if (aux_info[AT_EXECFD] != NULL) {
407 fd = aux_info[AT_EXECFD]->a_un.a_val;
409 assert(aux_info[AT_PHDR] != NULL);
410 phdr = (const Elf_Phdr *)aux_info[AT_PHDR]->a_un.a_ptr;
411 if (phdr == obj_rtld.phdr) {
413 _rtld_error("Tainted process refusing to run binary %s",
417 dbg("opening main program in direct exec mode");
419 rtld_argc = parse_args(argv, argc, &search_in_path, &fd);
420 argv0 = argv[rtld_argc];
421 explicit_fd = (fd != -1);
423 fd = open_binary_fd(argv0, search_in_path);
424 if (fstat(fd, &st) == -1) {
425 _rtld_error("Failed to fstat FD %d (%s): %s", fd,
426 explicit_fd ? "user-provided descriptor" : argv0,
427 rtld_strerror(errno));
432 * Rough emulation of the permission checks done by
433 * execve(2), only Unix DACs are checked, ACLs are
434 * ignored. Preserve the semantic of disabling owner
435 * to execute if owner x bit is cleared, even if
436 * others x bit is enabled.
437 * mmap(2) does not allow to mmap with PROT_EXEC if
438 * binary' file comes from noexec mount. We cannot
439 * set VV_TEXT on the binary.
442 if (st.st_uid == geteuid()) {
443 if ((st.st_mode & S_IXUSR) != 0)
445 } else if (st.st_gid == getegid()) {
446 if ((st.st_mode & S_IXGRP) != 0)
448 } else if ((st.st_mode & S_IXOTH) != 0) {
452 _rtld_error("No execute permission for binary %s",
458 * For direct exec mode, argv[0] is the interpreter
459 * name, we must remove it and shift arguments left
460 * before invoking binary main. Since stack layout
461 * places environment pointers and aux vectors right
462 * after the terminating NULL, we must shift
463 * environment and aux as well.
465 main_argc = argc - rtld_argc;
466 for (i = 0; i <= main_argc; i++)
467 argv[i] = argv[i + rtld_argc];
469 environ = env = envp = argv + main_argc + 1;
471 *envp = *(envp + rtld_argc);
473 } while (*envp != NULL);
474 aux = auxp = (Elf_Auxinfo *)envp;
475 auxpf = (Elf_Auxinfo *)(envp + rtld_argc);
476 for (;; auxp++, auxpf++) {
478 if (auxp->a_type == AT_NULL)
482 _rtld_error("No binary");
488 ld_bind_now = getenv(_LD("BIND_NOW"));
491 * If the process is tainted, then we un-set the dangerous environment
492 * variables. The process will be marked as tainted until setuid(2)
493 * is called. If any child process calls setuid(2) we do not want any
494 * future processes to honor the potentially un-safe variables.
497 if (unsetenv(_LD("PRELOAD")) || unsetenv(_LD("LIBMAP")) ||
498 unsetenv(_LD("LIBRARY_PATH")) || unsetenv(_LD("LIBRARY_PATH_FDS")) ||
499 unsetenv(_LD("LIBMAP_DISABLE")) || unsetenv(_LD("BIND_NOT")) ||
500 unsetenv(_LD("DEBUG")) || unsetenv(_LD("ELF_HINTS_PATH")) ||
501 unsetenv(_LD("LOADFLTR")) || unsetenv(_LD("LIBRARY_PATH_RPATH"))) {
502 _rtld_error("environment corrupt; aborting");
506 ld_debug = getenv(_LD("DEBUG"));
507 if (ld_bind_now == NULL)
508 ld_bind_not = getenv(_LD("BIND_NOT")) != NULL;
509 libmap_disable = getenv(_LD("LIBMAP_DISABLE")) != NULL;
510 libmap_override = getenv(_LD("LIBMAP"));
511 ld_library_path = getenv(_LD("LIBRARY_PATH"));
512 ld_library_dirs = getenv(_LD("LIBRARY_PATH_FDS"));
513 ld_preload = getenv(_LD("PRELOAD"));
514 ld_elf_hints_path = getenv(_LD("ELF_HINTS_PATH"));
515 ld_loadfltr = getenv(_LD("LOADFLTR")) != NULL;
516 library_path_rpath = getenv(_LD("LIBRARY_PATH_RPATH"));
517 if (library_path_rpath != NULL) {
518 if (library_path_rpath[0] == 'y' ||
519 library_path_rpath[0] == 'Y' ||
520 library_path_rpath[0] == '1')
521 ld_library_path_rpath = true;
523 ld_library_path_rpath = false;
525 dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
526 (ld_library_path != NULL) || (ld_preload != NULL) ||
527 (ld_elf_hints_path != NULL) || ld_loadfltr;
528 ld_tracing = getenv(_LD("TRACE_LOADED_OBJECTS"));
529 ld_utrace = getenv(_LD("UTRACE"));
531 if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
532 ld_elf_hints_path = ld_elf_hints_default;
534 if (ld_debug != NULL && *ld_debug != '\0')
536 dbg("%s is initialized, base address = %p", __progname,
537 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
538 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
539 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
541 dbg("initializing thread locks");
545 * Load the main program, or process its program header if it is
548 if (fd != -1) { /* Load the main program. */
549 dbg("loading main program");
550 obj_main = map_object(fd, argv0, NULL);
552 if (obj_main == NULL)
554 max_stack_flags = obj_main->stack_flags;
555 } else { /* Main program already loaded. */
556 dbg("processing main program's program header");
557 assert(aux_info[AT_PHDR] != NULL);
558 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
559 assert(aux_info[AT_PHNUM] != NULL);
560 phnum = aux_info[AT_PHNUM]->a_un.a_val;
561 assert(aux_info[AT_PHENT] != NULL);
562 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
563 assert(aux_info[AT_ENTRY] != NULL);
564 imgentry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
565 if ((obj_main = digest_phdr(phdr, phnum, imgentry, argv0)) == NULL)
569 if (aux_info[AT_EXECPATH] != NULL && fd == -1) {
570 kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
571 dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
572 if (kexecpath[0] == '/')
573 obj_main->path = kexecpath;
574 else if (getcwd(buf, sizeof(buf)) == NULL ||
575 strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
576 strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
577 obj_main->path = xstrdup(argv0);
579 obj_main->path = xstrdup(buf);
581 dbg("No AT_EXECPATH or direct exec");
582 obj_main->path = xstrdup(argv0);
584 dbg("obj_main path %s", obj_main->path);
585 obj_main->mainprog = true;
587 if (aux_info[AT_STACKPROT] != NULL &&
588 aux_info[AT_STACKPROT]->a_un.a_val != 0)
589 stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
593 * Get the actual dynamic linker pathname from the executable if
594 * possible. (It should always be possible.) That ensures that
595 * gdb will find the right dynamic linker even if a non-standard
598 if (obj_main->interp != NULL &&
599 strcmp(obj_main->interp, obj_rtld.path) != 0) {
601 obj_rtld.path = xstrdup(obj_main->interp);
602 __progname = obj_rtld.path;
606 digest_dynamic(obj_main, 0);
607 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
608 obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
609 obj_main->dynsymcount);
611 linkmap_add(obj_main);
612 linkmap_add(&obj_rtld);
614 /* Link the main program into the list of objects. */
615 TAILQ_INSERT_HEAD(&obj_list, obj_main, next);
619 /* Initialize a fake symbol for resolving undefined weak references. */
620 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
621 sym_zero.st_shndx = SHN_UNDEF;
622 sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
625 libmap_disable = (bool)lm_init(libmap_override);
627 dbg("loading LD_PRELOAD libraries");
628 if (load_preload_objects() == -1)
630 preload_tail = globallist_curr(TAILQ_LAST(&obj_list, obj_entry_q));
632 dbg("loading needed objects");
633 if (load_needed_objects(obj_main, 0) == -1)
636 /* Make a list of all objects loaded at startup. */
637 last_interposer = obj_main;
638 TAILQ_FOREACH(obj, &obj_list, next) {
641 if (obj->z_interpose && obj != obj_main) {
642 objlist_put_after(&list_main, last_interposer, obj);
643 last_interposer = obj;
645 objlist_push_tail(&list_main, obj);
650 dbg("checking for required versions");
651 if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
654 if (ld_tracing) { /* We're done */
655 trace_loaded_objects(obj_main);
659 if (getenv(_LD("DUMP_REL_PRE")) != NULL) {
660 dump_relocations(obj_main);
665 * Processing tls relocations requires having the tls offsets
666 * initialized. Prepare offsets before starting initial
667 * relocation processing.
669 dbg("initializing initial thread local storage offsets");
670 STAILQ_FOREACH(entry, &list_main, link) {
672 * Allocate all the initial objects out of the static TLS
673 * block even if they didn't ask for it.
675 allocate_tls_offset(entry->obj);
678 if (relocate_objects(obj_main,
679 ld_bind_now != NULL && *ld_bind_now != '\0',
680 &obj_rtld, SYMLOOK_EARLY, NULL) == -1)
683 dbg("doing copy relocations");
684 if (do_copy_relocations(obj_main) == -1)
687 if (getenv(_LD("DUMP_REL_POST")) != NULL) {
688 dump_relocations(obj_main);
695 * Setup TLS for main thread. This must be done after the
696 * relocations are processed, since tls initialization section
697 * might be the subject for relocations.
699 dbg("initializing initial thread local storage");
700 allocate_initial_tls(globallist_curr(TAILQ_FIRST(&obj_list)));
702 dbg("initializing key program variables");
703 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
704 set_program_var("environ", env);
705 set_program_var("__elf_aux_vector", aux);
707 /* Make a list of init functions to call. */
708 objlist_init(&initlist);
709 initlist_add_objects(globallist_curr(TAILQ_FIRST(&obj_list)),
710 preload_tail, &initlist);
712 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
714 map_stacks_exec(NULL);
716 dbg("resolving ifuncs");
717 if (resolve_objects_ifunc(obj_main,
718 ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
722 dbg("enforcing main obj relro");
723 if (obj_enforce_relro(obj_main) == -1)
726 if (!obj_main->crt_no_init) {
728 * Make sure we don't call the main program's init and fini
729 * functions for binaries linked with old crt1 which calls
732 obj_main->init = obj_main->fini = (Elf_Addr)NULL;
733 obj_main->preinit_array = obj_main->init_array =
734 obj_main->fini_array = (Elf_Addr)NULL;
738 * Execute MD initializers required before we call the objects'
743 wlock_acquire(rtld_bind_lock, &lockstate);
744 if (obj_main->crt_no_init)
746 objlist_call_init(&initlist, &lockstate);
747 _r_debug_postinit(&obj_main->linkmap);
748 objlist_clear(&initlist);
749 dbg("loading filtees");
750 TAILQ_FOREACH(obj, &obj_list, next) {
753 if (ld_loadfltr || obj->z_loadfltr)
754 load_filtees(obj, 0, &lockstate);
756 lock_release(rtld_bind_lock, &lockstate);
758 dbg("transferring control to program entry point = %p", obj_main->entry);
760 /* Return the exit procedure and the program entry point. */
761 *exit_proc = rtld_exit;
763 return (func_ptr_type) obj_main->entry;
767 rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
772 ptr = (void *)make_function_pointer(def, obj);
773 target = call_ifunc_resolver(ptr);
774 return ((void *)target);
778 * NB: MIPS uses a private version of this function (_mips_rtld_bind).
779 * Changes to this function should be applied there as well.
782 _rtld_bind(Obj_Entry *obj, Elf_Size reloff)
786 const Obj_Entry *defobj;
789 RtldLockState lockstate;
791 rlock_acquire(rtld_bind_lock, &lockstate);
792 if (sigsetjmp(lockstate.env, 0) != 0)
793 lock_upgrade(rtld_bind_lock, &lockstate);
795 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
797 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
799 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
800 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, SYMLOOK_IN_PLT,
804 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
805 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
807 target = (Elf_Addr)(defobj->relocbase + def->st_value);
809 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
810 defobj->strtab + def->st_name, basename(obj->path),
811 (void *)target, basename(defobj->path));
814 * Write the new contents for the jmpslot. Note that depending on
815 * architecture, the value which we need to return back to the
816 * lazy binding trampoline may or may not be the target
817 * address. The value returned from reloc_jmpslot() is the value
818 * that the trampoline needs.
820 target = reloc_jmpslot(where, target, defobj, obj, rel);
821 lock_release(rtld_bind_lock, &lockstate);
826 * Error reporting function. Use it like printf. If formats the message
827 * into a buffer, and sets things up so that the next call to dlerror()
828 * will return the message.
831 _rtld_error(const char *fmt, ...)
833 static char buf[512];
837 rtld_vsnprintf(buf, sizeof buf, fmt, ap);
840 LD_UTRACE(UTRACE_RTLD_ERROR, NULL, NULL, 0, 0, error_message);
844 * Return a dynamically-allocated copy of the current error message, if any.
849 return error_message == NULL ? NULL : xstrdup(error_message);
853 * Restore the current error message from a copy which was previously saved
854 * by errmsg_save(). The copy is freed.
857 errmsg_restore(char *saved_msg)
859 if (saved_msg == NULL)
860 error_message = NULL;
862 _rtld_error("%s", saved_msg);
868 basename(const char *name)
870 const char *p = strrchr(name, '/');
871 return p != NULL ? p + 1 : name;
874 static struct utsname uts;
877 origin_subst_one(Obj_Entry *obj, char *real, const char *kw,
878 const char *subst, bool may_free)
880 char *p, *p1, *res, *resp;
881 int subst_len, kw_len, subst_count, old_len, new_len;
886 * First, count the number of the keyword occurrences, to
887 * preallocate the final string.
889 for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
896 * If the keyword is not found, just return.
898 * Return non-substituted string if resolution failed. We
899 * cannot do anything more reasonable, the failure mode of the
900 * caller is unresolved library anyway.
902 if (subst_count == 0 || (obj != NULL && !obj_resolve_origin(obj)))
903 return (may_free ? real : xstrdup(real));
905 subst = obj->origin_path;
908 * There is indeed something to substitute. Calculate the
909 * length of the resulting string, and allocate it.
911 subst_len = strlen(subst);
912 old_len = strlen(real);
913 new_len = old_len + (subst_len - kw_len) * subst_count;
914 res = xmalloc(new_len + 1);
917 * Now, execute the substitution loop.
919 for (p = real, resp = res, *resp = '\0';;) {
922 /* Copy the prefix before keyword. */
923 memcpy(resp, p, p1 - p);
925 /* Keyword replacement. */
926 memcpy(resp, subst, subst_len);
934 /* Copy to the end of string and finish. */
942 origin_subst(Obj_Entry *obj, char *real)
944 char *res1, *res2, *res3, *res4;
946 if (obj == NULL || !trust)
947 return (xstrdup(real));
948 if (uts.sysname[0] == '\0') {
949 if (uname(&uts) != 0) {
950 _rtld_error("utsname failed: %d", errno);
954 res1 = origin_subst_one(obj, real, "$ORIGIN", NULL, false);
955 res2 = origin_subst_one(NULL, res1, "$OSNAME", uts.sysname, true);
956 res3 = origin_subst_one(NULL, res2, "$OSREL", uts.release, true);
957 res4 = origin_subst_one(NULL, res3, "$PLATFORM", uts.machine, true);
964 const char *msg = dlerror();
968 rtld_fdputstr(STDERR_FILENO, _BASENAME_RTLD ": ");
969 rtld_fdputstr(STDERR_FILENO, msg);
970 rtld_fdputchar(STDERR_FILENO, '\n');
975 * Process a shared object's DYNAMIC section, and save the important
976 * information in its Obj_Entry structure.
979 digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
980 const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
983 Needed_Entry **needed_tail = &obj->needed;
984 Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
985 Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
986 const Elf_Hashelt *hashtab;
987 const Elf32_Word *hashval;
988 Elf32_Word bkt, nmaskwords;
990 int plttype = DT_REL;
996 obj->bind_now = false;
997 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
998 switch (dynp->d_tag) {
1001 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
1005 obj->relsize = dynp->d_un.d_val;
1009 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
1013 obj->pltrel = (const Elf_Rel *)
1014 (obj->relocbase + dynp->d_un.d_ptr);
1018 obj->pltrelsize = dynp->d_un.d_val;
1022 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
1026 obj->relasize = dynp->d_un.d_val;
1030 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
1034 plttype = dynp->d_un.d_val;
1035 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
1039 obj->symtab = (const Elf_Sym *)
1040 (obj->relocbase + dynp->d_un.d_ptr);
1044 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
1048 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
1052 obj->strsize = dynp->d_un.d_val;
1056 obj->verneed = (const Elf_Verneed *) (obj->relocbase +
1061 obj->verneednum = dynp->d_un.d_val;
1065 obj->verdef = (const Elf_Verdef *) (obj->relocbase +
1070 obj->verdefnum = dynp->d_un.d_val;
1074 obj->versyms = (const Elf_Versym *)(obj->relocbase +
1080 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1082 obj->nbuckets = hashtab[0];
1083 obj->nchains = hashtab[1];
1084 obj->buckets = hashtab + 2;
1085 obj->chains = obj->buckets + obj->nbuckets;
1086 obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
1087 obj->buckets != NULL;
1093 hashtab = (const Elf_Hashelt *)(obj->relocbase +
1095 obj->nbuckets_gnu = hashtab[0];
1096 obj->symndx_gnu = hashtab[1];
1097 nmaskwords = hashtab[2];
1098 bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
1099 obj->maskwords_bm_gnu = nmaskwords - 1;
1100 obj->shift2_gnu = hashtab[3];
1101 obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
1102 obj->buckets_gnu = hashtab + 4 + bloom_size32;
1103 obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
1105 /* Number of bitmask words is required to be power of 2 */
1106 obj->valid_hash_gnu = powerof2(nmaskwords) &&
1107 obj->nbuckets_gnu > 0 && obj->buckets_gnu != NULL;
1113 Needed_Entry *nep = NEW(Needed_Entry);
1114 nep->name = dynp->d_un.d_val;
1119 needed_tail = &nep->next;
1125 Needed_Entry *nep = NEW(Needed_Entry);
1126 nep->name = dynp->d_un.d_val;
1130 *needed_filtees_tail = nep;
1131 needed_filtees_tail = &nep->next;
1137 Needed_Entry *nep = NEW(Needed_Entry);
1138 nep->name = dynp->d_un.d_val;
1142 *needed_aux_filtees_tail = nep;
1143 needed_aux_filtees_tail = &nep->next;
1148 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
1152 obj->textrel = true;
1156 obj->symbolic = true;
1161 * We have to wait until later to process this, because we
1162 * might not have gotten the address of the string table yet.
1172 *dyn_runpath = dynp;
1176 obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1179 case DT_PREINIT_ARRAY:
1180 obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1183 case DT_PREINIT_ARRAYSZ:
1184 obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1188 obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1191 case DT_INIT_ARRAYSZ:
1192 obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1196 obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1200 obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
1203 case DT_FINI_ARRAYSZ:
1204 obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
1208 * Don't process DT_DEBUG on MIPS as the dynamic section
1209 * is mapped read-only. DT_MIPS_RLD_MAP is used instead.
1215 dbg("Filling in DT_DEBUG entry");
1216 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
1221 if (dynp->d_un.d_val & DF_ORIGIN)
1222 obj->z_origin = true;
1223 if (dynp->d_un.d_val & DF_SYMBOLIC)
1224 obj->symbolic = true;
1225 if (dynp->d_un.d_val & DF_TEXTREL)
1226 obj->textrel = true;
1227 if (dynp->d_un.d_val & DF_BIND_NOW)
1228 obj->bind_now = true;
1229 /*if (dynp->d_un.d_val & DF_STATIC_TLS)
1233 case DT_MIPS_LOCAL_GOTNO:
1234 obj->local_gotno = dynp->d_un.d_val;
1237 case DT_MIPS_SYMTABNO:
1238 obj->symtabno = dynp->d_un.d_val;
1241 case DT_MIPS_GOTSYM:
1242 obj->gotsym = dynp->d_un.d_val;
1245 case DT_MIPS_RLD_MAP:
1246 *((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &r_debug;
1249 case DT_MIPS_PLTGOT:
1250 obj->mips_pltgot = (Elf_Addr *) (obj->relocbase +
1256 #ifdef __powerpc64__
1257 case DT_PPC64_GLINK:
1258 obj->glink = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
1263 if (dynp->d_un.d_val & DF_1_NOOPEN)
1264 obj->z_noopen = true;
1265 if (dynp->d_un.d_val & DF_1_ORIGIN)
1266 obj->z_origin = true;
1267 if (dynp->d_un.d_val & DF_1_GLOBAL)
1268 obj->z_global = true;
1269 if (dynp->d_un.d_val & DF_1_BIND_NOW)
1270 obj->bind_now = true;
1271 if (dynp->d_un.d_val & DF_1_NODELETE)
1272 obj->z_nodelete = true;
1273 if (dynp->d_un.d_val & DF_1_LOADFLTR)
1274 obj->z_loadfltr = true;
1275 if (dynp->d_un.d_val & DF_1_INTERPOSE)
1276 obj->z_interpose = true;
1277 if (dynp->d_un.d_val & DF_1_NODEFLIB)
1278 obj->z_nodeflib = true;
1283 dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
1290 obj->traced = false;
1292 if (plttype == DT_RELA) {
1293 obj->pltrela = (const Elf_Rela *) obj->pltrel;
1295 obj->pltrelasize = obj->pltrelsize;
1296 obj->pltrelsize = 0;
1299 /* Determine size of dynsym table (equal to nchains of sysv hash) */
1300 if (obj->valid_hash_sysv)
1301 obj->dynsymcount = obj->nchains;
1302 else if (obj->valid_hash_gnu) {
1303 obj->dynsymcount = 0;
1304 for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
1305 if (obj->buckets_gnu[bkt] == 0)
1307 hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
1310 while ((*hashval++ & 1u) == 0);
1312 obj->dynsymcount += obj->symndx_gnu;
1317 obj_resolve_origin(Obj_Entry *obj)
1320 if (obj->origin_path != NULL)
1322 obj->origin_path = xmalloc(PATH_MAX);
1323 return (rtld_dirname_abs(obj->path, obj->origin_path) != -1);
1327 digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
1328 const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
1331 if (obj->z_origin && !obj_resolve_origin(obj))
1334 if (dyn_runpath != NULL) {
1335 obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
1336 obj->runpath = origin_subst(obj, obj->runpath);
1337 } else if (dyn_rpath != NULL) {
1338 obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
1339 obj->rpath = origin_subst(obj, obj->rpath);
1341 if (dyn_soname != NULL)
1342 object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
1346 digest_dynamic(Obj_Entry *obj, int early)
1348 const Elf_Dyn *dyn_rpath;
1349 const Elf_Dyn *dyn_soname;
1350 const Elf_Dyn *dyn_runpath;
1352 digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
1353 digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
1357 * Process a shared object's program header. This is used only for the
1358 * main program, when the kernel has already loaded the main program
1359 * into memory before calling the dynamic linker. It creates and
1360 * returns an Obj_Entry structure.
1363 digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
1366 const Elf_Phdr *phlimit = phdr + phnum;
1368 Elf_Addr note_start, note_end;
1372 for (ph = phdr; ph < phlimit; ph++) {
1373 if (ph->p_type != PT_PHDR)
1377 obj->phsize = ph->p_memsz;
1378 obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
1382 obj->stack_flags = PF_X | PF_R | PF_W;
1384 for (ph = phdr; ph < phlimit; ph++) {
1385 switch (ph->p_type) {
1388 obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
1392 if (nsegs == 0) { /* First load segment */
1393 obj->vaddrbase = trunc_page(ph->p_vaddr);
1394 obj->mapbase = obj->vaddrbase + obj->relocbase;
1395 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
1397 } else { /* Last load segment */
1398 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
1405 obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
1410 obj->tlssize = ph->p_memsz;
1411 obj->tlsalign = ph->p_align;
1412 obj->tlsinitsize = ph->p_filesz;
1413 obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
1417 obj->stack_flags = ph->p_flags;
1421 obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
1422 obj->relro_size = round_page(ph->p_memsz);
1426 note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
1427 note_end = note_start + ph->p_filesz;
1428 digest_notes(obj, note_start, note_end);
1433 _rtld_error("%s: too few PT_LOAD segments", path);
1442 digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
1444 const Elf_Note *note;
1445 const char *note_name;
1448 for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
1449 note = (const Elf_Note *)((const char *)(note + 1) +
1450 roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
1451 roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
1452 if (note->n_namesz != sizeof(NOTE_FREEBSD_VENDOR) ||
1453 note->n_descsz != sizeof(int32_t))
1455 if (note->n_type != NT_FREEBSD_ABI_TAG &&
1456 note->n_type != NT_FREEBSD_NOINIT_TAG)
1458 note_name = (const char *)(note + 1);
1459 if (strncmp(NOTE_FREEBSD_VENDOR, note_name,
1460 sizeof(NOTE_FREEBSD_VENDOR)) != 0)
1462 switch (note->n_type) {
1463 case NT_FREEBSD_ABI_TAG:
1464 /* FreeBSD osrel note */
1465 p = (uintptr_t)(note + 1);
1466 p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
1467 obj->osrel = *(const int32_t *)(p);
1468 dbg("note osrel %d", obj->osrel);
1470 case NT_FREEBSD_NOINIT_TAG:
1471 /* FreeBSD 'crt does not call init' note */
1472 obj->crt_no_init = true;
1473 dbg("note crt_no_init");
1480 dlcheck(void *handle)
1484 TAILQ_FOREACH(obj, &obj_list, next) {
1485 if (obj == (Obj_Entry *) handle)
1489 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
1490 _rtld_error("Invalid shared object handle %p", handle);
1497 * If the given object is already in the donelist, return true. Otherwise
1498 * add the object to the list and return false.
1501 donelist_check(DoneList *dlp, const Obj_Entry *obj)
1505 for (i = 0; i < dlp->num_used; i++)
1506 if (dlp->objs[i] == obj)
1509 * Our donelist allocation should always be sufficient. But if
1510 * our threads locking isn't working properly, more shared objects
1511 * could have been loaded since we allocated the list. That should
1512 * never happen, but we'll handle it properly just in case it does.
1514 if (dlp->num_used < dlp->num_alloc)
1515 dlp->objs[dlp->num_used++] = obj;
1520 * Hash function for symbol table lookup. Don't even think about changing
1521 * this. It is specified by the System V ABI.
1524 elf_hash(const char *name)
1526 const unsigned char *p = (const unsigned char *) name;
1527 unsigned long h = 0;
1530 while (*p != '\0') {
1531 h = (h << 4) + *p++;
1532 if ((g = h & 0xf0000000) != 0)
1540 * The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
1541 * unsigned in case it's implemented with a wider type.
1544 gnu_hash(const char *s)
1550 for (c = *s; c != '\0'; c = *++s)
1552 return (h & 0xffffffff);
1557 * Find the library with the given name, and return its full pathname.
1558 * The returned string is dynamically allocated. Generates an error
1559 * message and returns NULL if the library cannot be found.
1561 * If the second argument is non-NULL, then it refers to an already-
1562 * loaded shared object, whose library search path will be searched.
1564 * If a library is successfully located via LD_LIBRARY_PATH_FDS, its
1565 * descriptor (which is close-on-exec) will be passed out via the third
1568 * The search order is:
1569 * DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
1570 * DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
1572 * DT_RUNPATH in the referencing file
1573 * ldconfig hints (if -z nodefaultlib, filter out default library directories
1575 * /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
1577 * (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
1580 find_library(const char *xname, const Obj_Entry *refobj, int *fdp)
1582 char *name, *pathname, *refobj_path;
1583 bool nodeflib, objgiven;
1585 objgiven = refobj != NULL;
1587 if (libmap_disable || !objgiven ||
1588 (name = lm_find(refobj->path, xname)) == NULL)
1589 name = (char *)xname;
1591 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
1592 if (name[0] != '/' && !trust) {
1593 _rtld_error("Absolute pathname required "
1594 "for shared object \"%s\"", name);
1597 return (origin_subst(__DECONST(Obj_Entry *, refobj),
1598 __DECONST(char *, name)));
1601 dbg(" Searching for \"%s\"", name);
1602 refobj_path = objgiven ? refobj->path : NULL;
1605 * If refobj->rpath != NULL, then refobj->runpath is NULL. Fall
1606 * back to pre-conforming behaviour if user requested so with
1607 * LD_LIBRARY_PATH_RPATH environment variable and ignore -z
1610 if (objgiven && refobj->rpath != NULL && ld_library_path_rpath) {
1611 pathname = search_library_path(name, ld_library_path,
1613 if (pathname != NULL)
1615 if (refobj != NULL) {
1616 pathname = search_library_path(name, refobj->rpath,
1618 if (pathname != NULL)
1621 pathname = search_library_pathfds(name, ld_library_dirs, fdp);
1622 if (pathname != NULL)
1624 pathname = search_library_path(name, gethints(false),
1626 if (pathname != NULL)
1628 pathname = search_library_path(name, ld_standard_library_path,
1630 if (pathname != NULL)
1633 nodeflib = objgiven ? refobj->z_nodeflib : false;
1635 pathname = search_library_path(name, refobj->rpath,
1637 if (pathname != NULL)
1640 if (objgiven && refobj->runpath == NULL && refobj != obj_main) {
1641 pathname = search_library_path(name, obj_main->rpath,
1643 if (pathname != NULL)
1646 pathname = search_library_path(name, ld_library_path,
1648 if (pathname != NULL)
1651 pathname = search_library_path(name, refobj->runpath,
1653 if (pathname != NULL)
1656 pathname = search_library_pathfds(name, ld_library_dirs, fdp);
1657 if (pathname != NULL)
1659 pathname = search_library_path(name, gethints(nodeflib),
1661 if (pathname != NULL)
1663 if (objgiven && !nodeflib) {
1664 pathname = search_library_path(name,
1665 ld_standard_library_path, refobj_path, fdp);
1666 if (pathname != NULL)
1671 if (objgiven && refobj->path != NULL) {
1672 _rtld_error("Shared object \"%s\" not found, "
1673 "required by \"%s\"", name, basename(refobj->path));
1675 _rtld_error("Shared object \"%s\" not found", name);
1681 * Given a symbol number in a referencing object, find the corresponding
1682 * definition of the symbol. Returns a pointer to the symbol, or NULL if
1683 * no definition was found. Returns a pointer to the Obj_Entry of the
1684 * defining object via the reference parameter DEFOBJ_OUT.
1687 find_symdef(unsigned long symnum, const Obj_Entry *refobj,
1688 const Obj_Entry **defobj_out, int flags, SymCache *cache,
1689 RtldLockState *lockstate)
1693 const Obj_Entry *defobj;
1694 const Ver_Entry *ve;
1700 * If we have already found this symbol, get the information from
1703 if (symnum >= refobj->dynsymcount)
1704 return NULL; /* Bad object */
1705 if (cache != NULL && cache[symnum].sym != NULL) {
1706 *defobj_out = cache[symnum].obj;
1707 return cache[symnum].sym;
1710 ref = refobj->symtab + symnum;
1711 name = refobj->strtab + ref->st_name;
1717 * We don't have to do a full scale lookup if the symbol is local.
1718 * We know it will bind to the instance in this load module; to
1719 * which we already have a pointer (ie ref). By not doing a lookup,
1720 * we not only improve performance, but it also avoids unresolvable
1721 * symbols when local symbols are not in the hash table. This has
1722 * been seen with the ia64 toolchain.
1724 if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
1725 if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
1726 _rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
1729 symlook_init(&req, name);
1731 ve = req.ventry = fetch_ventry(refobj, symnum);
1732 req.lockstate = lockstate;
1733 res = symlook_default(&req, refobj);
1736 defobj = req.defobj_out;
1744 * If we found no definition and the reference is weak, treat the
1745 * symbol as having the value zero.
1747 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
1753 *defobj_out = defobj;
1754 /* Record the information in the cache to avoid subsequent lookups. */
1755 if (cache != NULL) {
1756 cache[symnum].sym = def;
1757 cache[symnum].obj = defobj;
1760 if (refobj != &obj_rtld)
1761 _rtld_error("%s: Undefined symbol \"%s%s%s\"", refobj->path, name,
1762 ve != NULL ? "@" : "", ve != NULL ? ve->name : "");
1768 * Return the search path from the ldconfig hints file, reading it if
1769 * necessary. If nostdlib is true, then the default search paths are
1770 * not added to result.
1772 * Returns NULL if there are problems with the hints file,
1773 * or if the search path there is empty.
1776 gethints(bool nostdlib)
1778 static char *hints, *filtered_path;
1779 static struct elfhints_hdr hdr;
1780 struct fill_search_info_args sargs, hargs;
1781 struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
1782 struct dl_serpath *SLPpath, *hintpath;
1784 struct stat hint_stat;
1785 unsigned int SLPndx, hintndx, fndx, fcount;
1791 /* First call, read the hints file */
1792 if (hints == NULL) {
1793 /* Keep from trying again in case the hints file is bad. */
1796 if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
1800 * Check of hdr.dirlistlen value against type limit
1801 * intends to pacify static analyzers. Further
1802 * paranoia leads to checks that dirlist is fully
1803 * contained in the file range.
1805 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
1806 hdr.magic != ELFHINTS_MAGIC ||
1807 hdr.version != 1 || hdr.dirlistlen > UINT_MAX / 2 ||
1808 fstat(fd, &hint_stat) == -1) {
1815 if (dl + hdr.dirlist < dl)
1818 if (dl + hdr.dirlistlen < dl)
1820 dl += hdr.dirlistlen;
1821 if (dl > hint_stat.st_size)
1823 p = xmalloc(hdr.dirlistlen + 1);
1824 if (pread(fd, p, hdr.dirlistlen + 1,
1825 hdr.strtab + hdr.dirlist) != (ssize_t)hdr.dirlistlen + 1 ||
1826 p[hdr.dirlistlen] != '\0') {
1835 * If caller agreed to receive list which includes the default
1836 * paths, we are done. Otherwise, if we still did not
1837 * calculated filtered result, do it now.
1840 return (hints[0] != '\0' ? hints : NULL);
1841 if (filtered_path != NULL)
1845 * Obtain the list of all configured search paths, and the
1846 * list of the default paths.
1848 * First estimate the size of the results.
1850 smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1852 hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1855 sargs.request = RTLD_DI_SERINFOSIZE;
1856 sargs.serinfo = &smeta;
1857 hargs.request = RTLD_DI_SERINFOSIZE;
1858 hargs.serinfo = &hmeta;
1860 path_enumerate(ld_standard_library_path, fill_search_info, NULL,
1862 path_enumerate(hints, fill_search_info, NULL, &hargs);
1864 SLPinfo = xmalloc(smeta.dls_size);
1865 hintinfo = xmalloc(hmeta.dls_size);
1868 * Next fetch both sets of paths.
1870 sargs.request = RTLD_DI_SERINFO;
1871 sargs.serinfo = SLPinfo;
1872 sargs.serpath = &SLPinfo->dls_serpath[0];
1873 sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
1875 hargs.request = RTLD_DI_SERINFO;
1876 hargs.serinfo = hintinfo;
1877 hargs.serpath = &hintinfo->dls_serpath[0];
1878 hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
1880 path_enumerate(ld_standard_library_path, fill_search_info, NULL,
1882 path_enumerate(hints, fill_search_info, NULL, &hargs);
1885 * Now calculate the difference between two sets, by excluding
1886 * standard paths from the full set.
1890 filtered_path = xmalloc(hdr.dirlistlen + 1);
1891 hintpath = &hintinfo->dls_serpath[0];
1892 for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
1894 SLPpath = &SLPinfo->dls_serpath[0];
1896 * Check each standard path against current.
1898 for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
1899 /* matched, skip the path */
1900 if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
1908 * Not matched against any standard path, add the path
1909 * to result. Separate consequtive paths with ':'.
1912 filtered_path[fndx] = ':';
1916 flen = strlen(hintpath->dls_name);
1917 strncpy((filtered_path + fndx), hintpath->dls_name, flen);
1920 filtered_path[fndx] = '\0';
1926 return (filtered_path[0] != '\0' ? filtered_path : NULL);
1930 init_dag(Obj_Entry *root)
1932 const Needed_Entry *needed;
1933 const Objlist_Entry *elm;
1936 if (root->dag_inited)
1938 donelist_init(&donelist);
1940 /* Root object belongs to own DAG. */
1941 objlist_push_tail(&root->dldags, root);
1942 objlist_push_tail(&root->dagmembers, root);
1943 donelist_check(&donelist, root);
1946 * Add dependencies of root object to DAG in breadth order
1947 * by exploiting the fact that each new object get added
1948 * to the tail of the dagmembers list.
1950 STAILQ_FOREACH(elm, &root->dagmembers, link) {
1951 for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
1952 if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
1954 objlist_push_tail(&needed->obj->dldags, root);
1955 objlist_push_tail(&root->dagmembers, needed->obj);
1958 root->dag_inited = true;
1962 init_marker(Obj_Entry *marker)
1965 bzero(marker, sizeof(*marker));
1966 marker->marker = true;
1970 globallist_curr(const Obj_Entry *obj)
1977 return (__DECONST(Obj_Entry *, obj));
1978 obj = TAILQ_PREV(obj, obj_entry_q, next);
1983 globallist_next(const Obj_Entry *obj)
1987 obj = TAILQ_NEXT(obj, next);
1991 return (__DECONST(Obj_Entry *, obj));
1995 /* Prevent the object from being unmapped while the bind lock is dropped. */
1997 hold_object(Obj_Entry *obj)
2004 unhold_object(Obj_Entry *obj)
2007 assert(obj->holdcount > 0);
2008 if (--obj->holdcount == 0 && obj->unholdfree)
2009 release_object(obj);
2013 process_z(Obj_Entry *root)
2015 const Objlist_Entry *elm;
2019 * Walk over object DAG and process every dependent object
2020 * that is marked as DF_1_NODELETE or DF_1_GLOBAL. They need
2021 * to grow their own DAG.
2023 * For DF_1_GLOBAL, DAG is required for symbol lookups in
2024 * symlook_global() to work.
2026 * For DF_1_NODELETE, the DAG should have its reference upped.
2028 STAILQ_FOREACH(elm, &root->dagmembers, link) {
2032 if (obj->z_nodelete && !obj->ref_nodel) {
2033 dbg("obj %s -z nodelete", obj->path);
2036 obj->ref_nodel = true;
2038 if (obj->z_global && objlist_find(&list_global, obj) == NULL) {
2039 dbg("obj %s -z global", obj->path);
2040 objlist_push_tail(&list_global, obj);
2046 * Initialize the dynamic linker. The argument is the address at which
2047 * the dynamic linker has been mapped into memory. The primary task of
2048 * this function is to relocate the dynamic linker.
2051 init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
2053 Obj_Entry objtmp; /* Temporary rtld object */
2054 const Elf_Ehdr *ehdr;
2055 const Elf_Dyn *dyn_rpath;
2056 const Elf_Dyn *dyn_soname;
2057 const Elf_Dyn *dyn_runpath;
2059 #ifdef RTLD_INIT_PAGESIZES_EARLY
2060 /* The page size is required by the dynamic memory allocator. */
2061 init_pagesizes(aux_info);
2065 * Conjure up an Obj_Entry structure for the dynamic linker.
2067 * The "path" member can't be initialized yet because string constants
2068 * cannot yet be accessed. Below we will set it correctly.
2070 memset(&objtmp, 0, sizeof(objtmp));
2073 objtmp.mapbase = mapbase;
2075 objtmp.relocbase = mapbase;
2078 objtmp.dynamic = rtld_dynamic(&objtmp);
2079 digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
2080 assert(objtmp.needed == NULL);
2081 #if !defined(__mips__)
2082 /* MIPS has a bogus DT_TEXTREL. */
2083 assert(!objtmp.textrel);
2086 * Temporarily put the dynamic linker entry into the object list, so
2087 * that symbols can be found.
2089 relocate_objects(&objtmp, true, &objtmp, 0, NULL);
2091 ehdr = (Elf_Ehdr *)mapbase;
2092 objtmp.phdr = (Elf_Phdr *)((char *)mapbase + ehdr->e_phoff);
2093 objtmp.phsize = ehdr->e_phnum * sizeof(objtmp.phdr[0]);
2095 /* Initialize the object list. */
2096 TAILQ_INIT(&obj_list);
2098 /* Now that non-local variables can be accesses, copy out obj_rtld. */
2099 memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
2101 #ifndef RTLD_INIT_PAGESIZES_EARLY
2102 /* The page size is required by the dynamic memory allocator. */
2103 init_pagesizes(aux_info);
2106 if (aux_info[AT_OSRELDATE] != NULL)
2107 osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
2109 digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
2111 /* Replace the path with a dynamically allocated copy. */
2112 obj_rtld.path = xstrdup(ld_path_rtld);
2114 r_debug.r_brk = r_debug_state;
2115 r_debug.r_state = RT_CONSISTENT;
2119 * Retrieve the array of supported page sizes. The kernel provides the page
2120 * sizes in increasing order.
2123 init_pagesizes(Elf_Auxinfo **aux_info)
2125 static size_t psa[MAXPAGESIZES];
2129 if (aux_info[AT_PAGESIZES] != NULL && aux_info[AT_PAGESIZESLEN] !=
2131 size = aux_info[AT_PAGESIZESLEN]->a_un.a_val;
2132 pagesizes = aux_info[AT_PAGESIZES]->a_un.a_ptr;
2135 if (sysctlnametomib("hw.pagesizes", mib, &len) == 0)
2138 /* As a fallback, retrieve the base page size. */
2139 size = sizeof(psa[0]);
2140 if (aux_info[AT_PAGESZ] != NULL) {
2141 psa[0] = aux_info[AT_PAGESZ]->a_un.a_val;
2145 mib[1] = HW_PAGESIZE;
2149 if (sysctl(mib, len, psa, &size, NULL, 0) == -1) {
2150 _rtld_error("sysctl for hw.pagesize(s) failed");
2156 npagesizes = size / sizeof(pagesizes[0]);
2157 /* Discard any invalid entries at the end of the array. */
2158 while (npagesizes > 0 && pagesizes[npagesizes - 1] == 0)
2163 * Add the init functions from a needed object list (and its recursive
2164 * needed objects) to "list". This is not used directly; it is a helper
2165 * function for initlist_add_objects(). The write lock must be held
2166 * when this function is called.
2169 initlist_add_neededs(Needed_Entry *needed, Objlist *list)
2171 /* Recursively process the successor needed objects. */
2172 if (needed->next != NULL)
2173 initlist_add_neededs(needed->next, list);
2175 /* Process the current needed object. */
2176 if (needed->obj != NULL)
2177 initlist_add_objects(needed->obj, needed->obj, list);
2181 * Scan all of the DAGs rooted in the range of objects from "obj" to
2182 * "tail" and add their init functions to "list". This recurses over
2183 * the DAGs and ensure the proper init ordering such that each object's
2184 * needed libraries are initialized before the object itself. At the
2185 * same time, this function adds the objects to the global finalization
2186 * list "list_fini" in the opposite order. The write lock must be
2187 * held when this function is called.
2190 initlist_add_objects(Obj_Entry *obj, Obj_Entry *tail, Objlist *list)
2194 if (obj->init_scanned || obj->init_done)
2196 obj->init_scanned = true;
2198 /* Recursively process the successor objects. */
2199 nobj = globallist_next(obj);
2200 if (nobj != NULL && obj != tail)
2201 initlist_add_objects(nobj, tail, list);
2203 /* Recursively process the needed objects. */
2204 if (obj->needed != NULL)
2205 initlist_add_neededs(obj->needed, list);
2206 if (obj->needed_filtees != NULL)
2207 initlist_add_neededs(obj->needed_filtees, list);
2208 if (obj->needed_aux_filtees != NULL)
2209 initlist_add_neededs(obj->needed_aux_filtees, list);
2211 /* Add the object to the init list. */
2212 if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
2213 obj->init_array != (Elf_Addr)NULL)
2214 objlist_push_tail(list, obj);
2216 /* Add the object to the global fini list in the reverse order. */
2217 if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
2218 && !obj->on_fini_list) {
2219 objlist_push_head(&list_fini, obj);
2220 obj->on_fini_list = true;
2225 #define FPTR_TARGET(f) ((Elf_Addr) (f))
2229 free_needed_filtees(Needed_Entry *n, RtldLockState *lockstate)
2231 Needed_Entry *needed, *needed1;
2233 for (needed = n; needed != NULL; needed = needed->next) {
2234 if (needed->obj != NULL) {
2235 dlclose_locked(needed->obj, lockstate);
2239 for (needed = n; needed != NULL; needed = needed1) {
2240 needed1 = needed->next;
2246 unload_filtees(Obj_Entry *obj, RtldLockState *lockstate)
2249 free_needed_filtees(obj->needed_filtees, lockstate);
2250 obj->needed_filtees = NULL;
2251 free_needed_filtees(obj->needed_aux_filtees, lockstate);
2252 obj->needed_aux_filtees = NULL;
2253 obj->filtees_loaded = false;
2257 load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
2258 RtldLockState *lockstate)
2261 for (; needed != NULL; needed = needed->next) {
2262 needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
2263 flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
2264 RTLD_LOCAL, lockstate);
2269 load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
2272 lock_restart_for_upgrade(lockstate);
2273 if (!obj->filtees_loaded) {
2274 load_filtee1(obj, obj->needed_filtees, flags, lockstate);
2275 load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
2276 obj->filtees_loaded = true;
2281 process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
2285 for (; needed != NULL; needed = needed->next) {
2286 obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
2287 flags & ~RTLD_LO_NOLOAD);
2288 if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
2295 * Given a shared object, traverse its list of needed objects, and load
2296 * each of them. Returns 0 on success. Generates an error message and
2297 * returns -1 on failure.
2300 load_needed_objects(Obj_Entry *first, int flags)
2304 for (obj = first; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
2307 if (process_needed(obj, obj->needed, flags) == -1)
2314 load_preload_objects(void)
2316 char *p = ld_preload;
2318 static const char delim[] = " \t:;";
2323 p += strspn(p, delim);
2324 while (*p != '\0') {
2325 size_t len = strcspn(p, delim);
2330 obj = load_object(p, -1, NULL, 0);
2332 return -1; /* XXX - cleanup */
2333 obj->z_interpose = true;
2336 p += strspn(p, delim);
2338 LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
2343 printable_path(const char *path)
2346 return (path == NULL ? "<unknown>" : path);
2350 * Load a shared object into memory, if it is not already loaded. The
2351 * object may be specified by name or by user-supplied file descriptor
2352 * fd_u. In the later case, the fd_u descriptor is not closed, but its
2355 * Returns a pointer to the Obj_Entry for the object. Returns NULL
2359 load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
2368 TAILQ_FOREACH(obj, &obj_list, next) {
2369 if (obj->marker || obj->doomed)
2371 if (object_match_name(obj, name))
2375 path = find_library(name, refobj, &fd);
2383 * search_library_pathfds() opens a fresh file descriptor for the
2384 * library, so there is no need to dup().
2386 } else if (fd_u == -1) {
2388 * If we didn't find a match by pathname, or the name is not
2389 * supplied, open the file and check again by device and inode.
2390 * This avoids false mismatches caused by multiple links or ".."
2393 * To avoid a race, we open the file and use fstat() rather than
2396 if ((fd = open(path, O_RDONLY | O_CLOEXEC | O_VERIFY)) == -1) {
2397 _rtld_error("Cannot open \"%s\"", path);
2402 fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
2404 _rtld_error("Cannot dup fd");
2409 if (fstat(fd, &sb) == -1) {
2410 _rtld_error("Cannot fstat \"%s\"", printable_path(path));
2415 TAILQ_FOREACH(obj, &obj_list, next) {
2416 if (obj->marker || obj->doomed)
2418 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
2421 if (obj != NULL && name != NULL) {
2422 object_add_name(obj, name);
2427 if (flags & RTLD_LO_NOLOAD) {
2433 /* First use of this object, so we must map it in */
2434 obj = do_load_object(fd, name, path, &sb, flags);
2443 do_load_object(int fd, const char *name, char *path, struct stat *sbp,
2450 * but first, make sure that environment variables haven't been
2451 * used to circumvent the noexec flag on a filesystem.
2453 if (dangerous_ld_env) {
2454 if (fstatfs(fd, &fs) != 0) {
2455 _rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
2458 if (fs.f_flags & MNT_NOEXEC) {
2459 _rtld_error("Cannot execute objects on %s", fs.f_mntonname);
2463 dbg("loading \"%s\"", printable_path(path));
2464 obj = map_object(fd, printable_path(path), sbp);
2469 * If DT_SONAME is present in the object, digest_dynamic2 already
2470 * added it to the object names.
2473 object_add_name(obj, name);
2475 digest_dynamic(obj, 0);
2476 dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
2477 obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
2478 if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
2480 dbg("refusing to load non-loadable \"%s\"", obj->path);
2481 _rtld_error("Cannot dlopen non-loadable %s", obj->path);
2482 munmap(obj->mapbase, obj->mapsize);
2487 obj->dlopened = (flags & RTLD_LO_DLOPEN) != 0;
2488 TAILQ_INSERT_TAIL(&obj_list, obj, next);
2491 linkmap_add(obj); /* for GDB & dlinfo() */
2492 max_stack_flags |= obj->stack_flags;
2494 dbg(" %p .. %p: %s", obj->mapbase,
2495 obj->mapbase + obj->mapsize - 1, obj->path);
2497 dbg(" WARNING: %s has impure text", obj->path);
2498 LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
2505 obj_from_addr(const void *addr)
2509 TAILQ_FOREACH(obj, &obj_list, next) {
2512 if (addr < (void *) obj->mapbase)
2514 if (addr < (void *) (obj->mapbase + obj->mapsize))
2523 Elf_Addr *preinit_addr;
2526 preinit_addr = (Elf_Addr *)obj_main->preinit_array;
2527 if (preinit_addr == NULL)
2530 for (index = 0; index < obj_main->preinit_array_num; index++) {
2531 if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
2532 dbg("calling preinit function for %s at %p", obj_main->path,
2533 (void *)preinit_addr[index]);
2534 LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
2535 0, 0, obj_main->path);
2536 call_init_pointer(obj_main, preinit_addr[index]);
2542 * Call the finalization functions for each of the objects in "list"
2543 * belonging to the DAG of "root" and referenced once. If NULL "root"
2544 * is specified, every finalization function will be called regardless
2545 * of the reference count and the list elements won't be freed. All of
2546 * the objects are expected to have non-NULL fini functions.
2549 objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
2553 Elf_Addr *fini_addr;
2556 assert(root == NULL || root->refcount == 1);
2559 root->doomed = true;
2562 * Preserve the current error message since a fini function might
2563 * call into the dynamic linker and overwrite it.
2565 saved_msg = errmsg_save();
2567 STAILQ_FOREACH(elm, list, link) {
2568 if (root != NULL && (elm->obj->refcount != 1 ||
2569 objlist_find(&root->dagmembers, elm->obj) == NULL))
2571 /* Remove object from fini list to prevent recursive invocation. */
2572 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2573 /* Ensure that new references cannot be acquired. */
2574 elm->obj->doomed = true;
2576 hold_object(elm->obj);
2577 lock_release(rtld_bind_lock, lockstate);
2579 * It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
2580 * When this happens, DT_FINI_ARRAY is processed first.
2582 fini_addr = (Elf_Addr *)elm->obj->fini_array;
2583 if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
2584 for (index = elm->obj->fini_array_num - 1; index >= 0;
2586 if (fini_addr[index] != 0 && fini_addr[index] != 1) {
2587 dbg("calling fini function for %s at %p",
2588 elm->obj->path, (void *)fini_addr[index]);
2589 LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
2590 (void *)fini_addr[index], 0, 0, elm->obj->path);
2591 call_initfini_pointer(elm->obj, fini_addr[index]);
2595 if (elm->obj->fini != (Elf_Addr)NULL) {
2596 dbg("calling fini function for %s at %p", elm->obj->path,
2597 (void *)elm->obj->fini);
2598 LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
2599 0, 0, elm->obj->path);
2600 call_initfini_pointer(elm->obj, elm->obj->fini);
2602 wlock_acquire(rtld_bind_lock, lockstate);
2603 unhold_object(elm->obj);
2604 /* No need to free anything if process is going down. */
2608 * We must restart the list traversal after every fini call
2609 * because a dlclose() call from the fini function or from
2610 * another thread might have modified the reference counts.
2614 } while (elm != NULL);
2615 errmsg_restore(saved_msg);
2619 * Call the initialization functions for each of the objects in
2620 * "list". All of the objects are expected to have non-NULL init
2624 objlist_call_init(Objlist *list, RtldLockState *lockstate)
2629 Elf_Addr *init_addr;
2633 * Clean init_scanned flag so that objects can be rechecked and
2634 * possibly initialized earlier if any of vectors called below
2635 * cause the change by using dlopen.
2637 TAILQ_FOREACH(obj, &obj_list, next) {
2640 obj->init_scanned = false;
2644 * Preserve the current error message since an init function might
2645 * call into the dynamic linker and overwrite it.
2647 saved_msg = errmsg_save();
2648 STAILQ_FOREACH(elm, list, link) {
2649 if (elm->obj->init_done) /* Initialized early. */
2652 * Race: other thread might try to use this object before current
2653 * one completes the initialization. Not much can be done here
2654 * without better locking.
2656 elm->obj->init_done = true;
2657 hold_object(elm->obj);
2658 lock_release(rtld_bind_lock, lockstate);
2661 * It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
2662 * When this happens, DT_INIT is processed first.
2664 if (elm->obj->init != (Elf_Addr)NULL) {
2665 dbg("calling init function for %s at %p", elm->obj->path,
2666 (void *)elm->obj->init);
2667 LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
2668 0, 0, elm->obj->path);
2669 call_initfini_pointer(elm->obj, elm->obj->init);
2671 init_addr = (Elf_Addr *)elm->obj->init_array;
2672 if (init_addr != NULL) {
2673 for (index = 0; index < elm->obj->init_array_num; index++) {
2674 if (init_addr[index] != 0 && init_addr[index] != 1) {
2675 dbg("calling init function for %s at %p", elm->obj->path,
2676 (void *)init_addr[index]);
2677 LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
2678 (void *)init_addr[index], 0, 0, elm->obj->path);
2679 call_init_pointer(elm->obj, init_addr[index]);
2683 wlock_acquire(rtld_bind_lock, lockstate);
2684 unhold_object(elm->obj);
2686 errmsg_restore(saved_msg);
2690 objlist_clear(Objlist *list)
2694 while (!STAILQ_EMPTY(list)) {
2695 elm = STAILQ_FIRST(list);
2696 STAILQ_REMOVE_HEAD(list, link);
2701 static Objlist_Entry *
2702 objlist_find(Objlist *list, const Obj_Entry *obj)
2706 STAILQ_FOREACH(elm, list, link)
2707 if (elm->obj == obj)
2713 objlist_init(Objlist *list)
2719 objlist_push_head(Objlist *list, Obj_Entry *obj)
2723 elm = NEW(Objlist_Entry);
2725 STAILQ_INSERT_HEAD(list, elm, link);
2729 objlist_push_tail(Objlist *list, Obj_Entry *obj)
2733 elm = NEW(Objlist_Entry);
2735 STAILQ_INSERT_TAIL(list, elm, link);
2739 objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
2741 Objlist_Entry *elm, *listelm;
2743 STAILQ_FOREACH(listelm, list, link) {
2744 if (listelm->obj == listobj)
2747 elm = NEW(Objlist_Entry);
2749 if (listelm != NULL)
2750 STAILQ_INSERT_AFTER(list, listelm, elm, link);
2752 STAILQ_INSERT_TAIL(list, elm, link);
2756 objlist_remove(Objlist *list, Obj_Entry *obj)
2760 if ((elm = objlist_find(list, obj)) != NULL) {
2761 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
2767 * Relocate dag rooted in the specified object.
2768 * Returns 0 on success, or -1 on failure.
2772 relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
2773 int flags, RtldLockState *lockstate)
2779 STAILQ_FOREACH(elm, &root->dagmembers, link) {
2780 error = relocate_object(elm->obj, bind_now, rtldobj, flags,
2789 * Prepare for, or clean after, relocating an object marked with
2790 * DT_TEXTREL or DF_TEXTREL. Before relocating, all read-only
2791 * segments are remapped read-write. After relocations are done, the
2792 * segment's permissions are returned back to the modes specified in
2793 * the phdrs. If any relocation happened, or always for wired
2794 * program, COW is triggered.
2797 reloc_textrel_prot(Obj_Entry *obj, bool before)
2804 for (l = obj->phsize / sizeof(*ph), ph = obj->phdr; l > 0;
2806 if (ph->p_type != PT_LOAD || (ph->p_flags & PF_W) != 0)
2808 base = obj->relocbase + trunc_page(ph->p_vaddr);
2809 sz = round_page(ph->p_vaddr + ph->p_filesz) -
2810 trunc_page(ph->p_vaddr);
2811 prot = convert_prot(ph->p_flags) | (before ? PROT_WRITE : 0);
2812 if (mprotect(base, sz, prot) == -1) {
2813 _rtld_error("%s: Cannot write-%sable text segment: %s",
2814 obj->path, before ? "en" : "dis",
2815 rtld_strerror(errno));
2823 * Relocate single object.
2824 * Returns 0 on success, or -1 on failure.
2827 relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
2828 int flags, RtldLockState *lockstate)
2833 obj->relocated = true;
2835 dbg("relocating \"%s\"", obj->path);
2837 if (obj->symtab == NULL || obj->strtab == NULL ||
2838 !(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
2839 _rtld_error("%s: Shared object has no run-time symbol table",
2844 /* There are relocations to the write-protected text segment. */
2845 if (obj->textrel && reloc_textrel_prot(obj, true) != 0)
2848 /* Process the non-PLT non-IFUNC relocations. */
2849 if (reloc_non_plt(obj, rtldobj, flags, lockstate))
2852 /* Re-protected the text segment. */
2853 if (obj->textrel && reloc_textrel_prot(obj, false) != 0)
2856 /* Set the special PLT or GOT entries. */
2859 /* Process the PLT relocations. */
2860 if (reloc_plt(obj) == -1)
2862 /* Relocate the jump slots if we are doing immediate binding. */
2863 if (obj->bind_now || bind_now) {
2864 if (reloc_jmpslots(obj, flags, lockstate) == -1 ||
2865 resolve_object_ifunc(obj, true, flags, lockstate) == -1)
2870 * Process the non-PLT IFUNC relocations. The relocations are
2871 * processed in two phases, because IFUNC resolvers may
2872 * reference other symbols, which must be readily processed
2873 * before resolvers are called.
2875 if (obj->non_plt_gnu_ifunc &&
2876 reloc_non_plt(obj, rtldobj, flags | SYMLOOK_IFUNC, lockstate))
2879 if (!obj->mainprog && obj_enforce_relro(obj) == -1)
2883 * Set up the magic number and version in the Obj_Entry. These
2884 * were checked in the crt1.o from the original ElfKit, so we
2885 * set them for backward compatibility.
2887 obj->magic = RTLD_MAGIC;
2888 obj->version = RTLD_VERSION;
2894 * Relocate newly-loaded shared objects. The argument is a pointer to
2895 * the Obj_Entry for the first such object. All objects from the first
2896 * to the end of the list of objects are relocated. Returns 0 on success,
2900 relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
2901 int flags, RtldLockState *lockstate)
2906 for (error = 0, obj = first; obj != NULL;
2907 obj = TAILQ_NEXT(obj, next)) {
2910 error = relocate_object(obj, bind_now, rtldobj, flags,
2919 * The handling of R_MACHINE_IRELATIVE relocations and jumpslots
2920 * referencing STT_GNU_IFUNC symbols is postponed till the other
2921 * relocations are done. The indirect functions specified as
2922 * ifunc are allowed to call other symbols, so we need to have
2923 * objects relocated before asking for resolution from indirects.
2925 * The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
2926 * instead of the usual lazy handling of PLT slots. It is
2927 * consistent with how GNU does it.
2930 resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
2931 RtldLockState *lockstate)
2933 if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
2935 if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
2936 reloc_gnu_ifunc(obj, flags, lockstate) == -1)
2942 resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
2943 RtldLockState *lockstate)
2947 for (obj = first; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
2950 if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
2957 initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
2958 RtldLockState *lockstate)
2962 STAILQ_FOREACH(elm, list, link) {
2963 if (resolve_object_ifunc(elm->obj, bind_now, flags,
2971 * Cleanup procedure. It will be called (by the atexit mechanism) just
2972 * before the process exits.
2977 RtldLockState lockstate;
2979 wlock_acquire(rtld_bind_lock, &lockstate);
2981 objlist_call_fini(&list_fini, NULL, &lockstate);
2982 /* No need to remove the items from the list, since we are exiting. */
2983 if (!libmap_disable)
2985 lock_release(rtld_bind_lock, &lockstate);
2989 * Iterate over a search path, translate each element, and invoke the
2990 * callback on the result.
2993 path_enumerate(const char *path, path_enum_proc callback,
2994 const char *refobj_path, void *arg)
3000 path += strspn(path, ":;");
3001 while (*path != '\0') {
3005 len = strcspn(path, ":;");
3006 trans = lm_findn(refobj_path, path, len);
3008 res = callback(trans, strlen(trans), arg);
3010 res = callback(path, len, arg);
3016 path += strspn(path, ":;");
3022 struct try_library_args {
3031 try_library_path(const char *dir, size_t dirlen, void *param)
3033 struct try_library_args *arg;
3037 if (*dir == '/' || trust) {
3040 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
3043 pathname = arg->buffer;
3044 strncpy(pathname, dir, dirlen);
3045 pathname[dirlen] = '/';
3046 strcpy(pathname + dirlen + 1, arg->name);
3048 dbg(" Trying \"%s\"", pathname);
3049 fd = open(pathname, O_RDONLY | O_CLOEXEC | O_VERIFY);
3051 dbg(" Opened \"%s\", fd %d", pathname, fd);
3052 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
3053 strcpy(pathname, arg->buffer);
3057 dbg(" Failed to open \"%s\": %s",
3058 pathname, rtld_strerror(errno));
3065 search_library_path(const char *name, const char *path,
3066 const char *refobj_path, int *fdp)
3069 struct try_library_args arg;
3075 arg.namelen = strlen(name);
3076 arg.buffer = xmalloc(PATH_MAX);
3077 arg.buflen = PATH_MAX;
3080 p = path_enumerate(path, try_library_path, refobj_path, &arg);
3090 * Finds the library with the given name using the directory descriptors
3091 * listed in the LD_LIBRARY_PATH_FDS environment variable.
3093 * Returns a freshly-opened close-on-exec file descriptor for the library,
3094 * or -1 if the library cannot be found.
3097 search_library_pathfds(const char *name, const char *path, int *fdp)
3099 char *envcopy, *fdstr, *found, *last_token;
3103 dbg("%s('%s', '%s', fdp)", __func__, name, path);
3105 /* Don't load from user-specified libdirs into setuid binaries. */
3109 /* We can't do anything if LD_LIBRARY_PATH_FDS isn't set. */
3113 /* LD_LIBRARY_PATH_FDS only works with relative paths. */
3114 if (name[0] == '/') {
3115 dbg("Absolute path (%s) passed to %s", name, __func__);
3120 * Use strtok_r() to walk the FD:FD:FD list. This requires a local
3121 * copy of the path, as strtok_r rewrites separator tokens
3125 envcopy = xstrdup(path);
3126 for (fdstr = strtok_r(envcopy, ":", &last_token); fdstr != NULL;
3127 fdstr = strtok_r(NULL, ":", &last_token)) {
3128 dirfd = parse_integer(fdstr);
3130 _rtld_error("failed to parse directory FD: '%s'",
3134 fd = __sys_openat(dirfd, name, O_RDONLY | O_CLOEXEC | O_VERIFY);
3137 len = strlen(fdstr) + strlen(name) + 3;
3138 found = xmalloc(len);
3139 if (rtld_snprintf(found, len, "#%d/%s", dirfd, name) < 0) {
3140 _rtld_error("error generating '%d/%s'",
3144 dbg("open('%s') => %d", found, fd);
3155 dlclose(void *handle)
3157 RtldLockState lockstate;
3160 wlock_acquire(rtld_bind_lock, &lockstate);
3161 error = dlclose_locked(handle, &lockstate);
3162 lock_release(rtld_bind_lock, &lockstate);
3167 dlclose_locked(void *handle, RtldLockState *lockstate)
3171 root = dlcheck(handle);
3174 LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
3177 /* Unreference the object and its dependencies. */
3178 root->dl_refcount--;
3180 if (root->refcount == 1) {
3182 * The object will be no longer referenced, so we must unload it.
3183 * First, call the fini functions.
3185 objlist_call_fini(&list_fini, root, lockstate);
3189 /* Finish cleaning up the newly-unreferenced objects. */
3190 GDB_STATE(RT_DELETE,&root->linkmap);
3191 unload_object(root, lockstate);
3192 GDB_STATE(RT_CONSISTENT,NULL);
3196 LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
3203 char *msg = error_message;
3204 error_message = NULL;
3209 * This function is deprecated and has no effect.
3212 dllockinit(void *context,
3213 void *(*lock_create)(void *context),
3214 void (*rlock_acquire)(void *lock),
3215 void (*wlock_acquire)(void *lock),
3216 void (*lock_release)(void *lock),
3217 void (*lock_destroy)(void *lock),
3218 void (*context_destroy)(void *context))
3220 static void *cur_context;
3221 static void (*cur_context_destroy)(void *);
3223 /* Just destroy the context from the previous call, if necessary. */
3224 if (cur_context_destroy != NULL)
3225 cur_context_destroy(cur_context);
3226 cur_context = context;
3227 cur_context_destroy = context_destroy;
3231 dlopen(const char *name, int mode)
3234 return (rtld_dlopen(name, -1, mode));
3238 fdlopen(int fd, int mode)
3241 return (rtld_dlopen(NULL, fd, mode));
3245 rtld_dlopen(const char *name, int fd, int mode)
3247 RtldLockState lockstate;
3250 LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
3251 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
3252 if (ld_tracing != NULL) {
3253 rlock_acquire(rtld_bind_lock, &lockstate);
3254 if (sigsetjmp(lockstate.env, 0) != 0)
3255 lock_upgrade(rtld_bind_lock, &lockstate);
3256 environ = (char **)*get_program_var_addr("environ", &lockstate);
3257 lock_release(rtld_bind_lock, &lockstate);
3259 lo_flags = RTLD_LO_DLOPEN;
3260 if (mode & RTLD_NODELETE)
3261 lo_flags |= RTLD_LO_NODELETE;
3262 if (mode & RTLD_NOLOAD)
3263 lo_flags |= RTLD_LO_NOLOAD;
3264 if (ld_tracing != NULL)
3265 lo_flags |= RTLD_LO_TRACE;
3267 return (dlopen_object(name, fd, obj_main, lo_flags,
3268 mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
3272 dlopen_cleanup(Obj_Entry *obj, RtldLockState *lockstate)
3277 if (obj->refcount == 0)
3278 unload_object(obj, lockstate);
3282 dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
3283 int mode, RtldLockState *lockstate)
3285 Obj_Entry *old_obj_tail;
3288 RtldLockState mlockstate;
3291 objlist_init(&initlist);
3293 if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
3294 wlock_acquire(rtld_bind_lock, &mlockstate);
3295 lockstate = &mlockstate;
3297 GDB_STATE(RT_ADD,NULL);
3299 old_obj_tail = globallist_curr(TAILQ_LAST(&obj_list, obj_entry_q));
3301 if (name == NULL && fd == -1) {
3305 obj = load_object(name, fd, refobj, lo_flags);
3310 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
3311 objlist_push_tail(&list_global, obj);
3312 if (globallist_next(old_obj_tail) != NULL) {
3313 /* We loaded something new. */
3314 assert(globallist_next(old_obj_tail) == obj);
3315 result = load_needed_objects(obj,
3316 lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
3320 result = rtld_verify_versions(&obj->dagmembers);
3321 if (result != -1 && ld_tracing)
3323 if (result == -1 || relocate_object_dag(obj,
3324 (mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
3325 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3327 dlopen_cleanup(obj, lockstate);
3329 } else if (lo_flags & RTLD_LO_EARLY) {
3331 * Do not call the init functions for early loaded
3332 * filtees. The image is still not initialized enough
3335 * Our object is found by the global object list and
3336 * will be ordered among all init calls done right
3337 * before transferring control to main.
3340 /* Make list of init functions to call. */
3341 initlist_add_objects(obj, obj, &initlist);
3344 * Process all no_delete or global objects here, given
3345 * them own DAGs to prevent their dependencies from being
3346 * unloaded. This has to be done after we have loaded all
3347 * of the dependencies, so that we do not miss any.
3353 * Bump the reference counts for objects on this DAG. If
3354 * this is the first dlopen() call for the object that was
3355 * already loaded as a dependency, initialize the dag
3361 if ((lo_flags & RTLD_LO_TRACE) != 0)
3364 if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
3365 obj->z_nodelete) && !obj->ref_nodel) {
3366 dbg("obj %s nodelete", obj->path);
3368 obj->z_nodelete = obj->ref_nodel = true;
3372 LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
3374 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
3376 if (!(lo_flags & RTLD_LO_EARLY)) {
3377 map_stacks_exec(lockstate);
3380 if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
3381 (lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
3383 objlist_clear(&initlist);
3384 dlopen_cleanup(obj, lockstate);
3385 if (lockstate == &mlockstate)
3386 lock_release(rtld_bind_lock, lockstate);
3390 if (!(lo_flags & RTLD_LO_EARLY)) {
3391 /* Call the init functions. */
3392 objlist_call_init(&initlist, lockstate);
3394 objlist_clear(&initlist);
3395 if (lockstate == &mlockstate)
3396 lock_release(rtld_bind_lock, lockstate);
3399 trace_loaded_objects(obj);
3400 if (lockstate == &mlockstate)
3401 lock_release(rtld_bind_lock, lockstate);
3406 do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
3410 const Obj_Entry *obj, *defobj;
3413 RtldLockState lockstate;
3420 symlook_init(&req, name);
3422 req.flags = flags | SYMLOOK_IN_PLT;
3423 req.lockstate = &lockstate;
3425 LD_UTRACE(UTRACE_DLSYM_START, handle, NULL, 0, 0, name);
3426 rlock_acquire(rtld_bind_lock, &lockstate);
3427 if (sigsetjmp(lockstate.env, 0) != 0)
3428 lock_upgrade(rtld_bind_lock, &lockstate);
3429 if (handle == NULL || handle == RTLD_NEXT ||
3430 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
3432 if ((obj = obj_from_addr(retaddr)) == NULL) {
3433 _rtld_error("Cannot determine caller's shared object");
3434 lock_release(rtld_bind_lock, &lockstate);
3435 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3438 if (handle == NULL) { /* Just the caller's shared object. */
3439 res = symlook_obj(&req, obj);
3442 defobj = req.defobj_out;
3444 } else if (handle == RTLD_NEXT || /* Objects after caller's */
3445 handle == RTLD_SELF) { /* ... caller included */
3446 if (handle == RTLD_NEXT)
3447 obj = globallist_next(obj);
3448 for (; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
3451 res = symlook_obj(&req, obj);
3454 ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
3456 defobj = req.defobj_out;
3457 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
3463 * Search the dynamic linker itself, and possibly resolve the
3464 * symbol from there. This is how the application links to
3465 * dynamic linker services such as dlopen.
3467 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3468 res = symlook_obj(&req, &obj_rtld);
3471 defobj = req.defobj_out;
3475 assert(handle == RTLD_DEFAULT);
3476 res = symlook_default(&req, obj);
3478 defobj = req.defobj_out;
3483 if ((obj = dlcheck(handle)) == NULL) {
3484 lock_release(rtld_bind_lock, &lockstate);
3485 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3489 donelist_init(&donelist);
3490 if (obj->mainprog) {
3491 /* Handle obtained by dlopen(NULL, ...) implies global scope. */
3492 res = symlook_global(&req, &donelist);
3495 defobj = req.defobj_out;
3498 * Search the dynamic linker itself, and possibly resolve the
3499 * symbol from there. This is how the application links to
3500 * dynamic linker services such as dlopen.
3502 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
3503 res = symlook_obj(&req, &obj_rtld);
3506 defobj = req.defobj_out;
3511 /* Search the whole DAG rooted at the given object. */
3512 res = symlook_list(&req, &obj->dagmembers, &donelist);
3515 defobj = req.defobj_out;
3521 lock_release(rtld_bind_lock, &lockstate);
3524 * The value required by the caller is derived from the value
3525 * of the symbol. this is simply the relocated value of the
3528 if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
3529 sym = make_function_pointer(def, defobj);
3530 else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
3531 sym = rtld_resolve_ifunc(defobj, def);
3532 else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
3533 ti.ti_module = defobj->tlsindex;
3534 ti.ti_offset = def->st_value;
3535 sym = __tls_get_addr(&ti);
3537 sym = defobj->relocbase + def->st_value;
3538 LD_UTRACE(UTRACE_DLSYM_STOP, handle, sym, 0, 0, name);
3542 _rtld_error("Undefined symbol \"%s%s%s\"", name, ve != NULL ? "@" : "",
3543 ve != NULL ? ve->name : "");
3544 lock_release(rtld_bind_lock, &lockstate);
3545 LD_UTRACE(UTRACE_DLSYM_STOP, handle, NULL, 0, 0, name);
3550 dlsym(void *handle, const char *name)
3552 return do_dlsym(handle, name, __builtin_return_address(0), NULL,
3557 dlfunc(void *handle, const char *name)
3564 rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
3570 dlvsym(void *handle, const char *name, const char *version)
3574 ventry.name = version;
3576 ventry.hash = elf_hash(version);
3578 return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
3583 _rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
3585 const Obj_Entry *obj;
3586 RtldLockState lockstate;
3588 rlock_acquire(rtld_bind_lock, &lockstate);
3589 obj = obj_from_addr(addr);
3591 _rtld_error("No shared object contains address");
3592 lock_release(rtld_bind_lock, &lockstate);
3595 rtld_fill_dl_phdr_info(obj, phdr_info);
3596 lock_release(rtld_bind_lock, &lockstate);
3601 dladdr(const void *addr, Dl_info *info)
3603 const Obj_Entry *obj;
3606 unsigned long symoffset;
3607 RtldLockState lockstate;
3609 rlock_acquire(rtld_bind_lock, &lockstate);
3610 obj = obj_from_addr(addr);
3612 _rtld_error("No shared object contains address");
3613 lock_release(rtld_bind_lock, &lockstate);
3616 info->dli_fname = obj->path;
3617 info->dli_fbase = obj->mapbase;
3618 info->dli_saddr = (void *)0;
3619 info->dli_sname = NULL;
3622 * Walk the symbol list looking for the symbol whose address is
3623 * closest to the address sent in.
3625 for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
3626 def = obj->symtab + symoffset;
3629 * For skip the symbol if st_shndx is either SHN_UNDEF or
3632 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
3636 * If the symbol is greater than the specified address, or if it
3637 * is further away from addr than the current nearest symbol,
3640 symbol_addr = obj->relocbase + def->st_value;
3641 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
3644 /* Update our idea of the nearest symbol. */
3645 info->dli_sname = obj->strtab + def->st_name;
3646 info->dli_saddr = symbol_addr;
3649 if (info->dli_saddr == addr)
3652 lock_release(rtld_bind_lock, &lockstate);
3657 dlinfo(void *handle, int request, void *p)
3659 const Obj_Entry *obj;
3660 RtldLockState lockstate;
3663 rlock_acquire(rtld_bind_lock, &lockstate);
3665 if (handle == NULL || handle == RTLD_SELF) {
3668 retaddr = __builtin_return_address(0); /* __GNUC__ only */
3669 if ((obj = obj_from_addr(retaddr)) == NULL)
3670 _rtld_error("Cannot determine caller's shared object");
3672 obj = dlcheck(handle);
3675 lock_release(rtld_bind_lock, &lockstate);
3681 case RTLD_DI_LINKMAP:
3682 *((struct link_map const **)p) = &obj->linkmap;
3684 case RTLD_DI_ORIGIN:
3685 error = rtld_dirname(obj->path, p);
3688 case RTLD_DI_SERINFOSIZE:
3689 case RTLD_DI_SERINFO:
3690 error = do_search_info(obj, request, (struct dl_serinfo *)p);
3694 _rtld_error("Invalid request %d passed to dlinfo()", request);
3698 lock_release(rtld_bind_lock, &lockstate);
3704 rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
3707 phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
3708 phdr_info->dlpi_name = obj->path;
3709 phdr_info->dlpi_phdr = obj->phdr;
3710 phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
3711 phdr_info->dlpi_tls_modid = obj->tlsindex;
3712 phdr_info->dlpi_tls_data = obj->tlsinit;
3713 phdr_info->dlpi_adds = obj_loads;
3714 phdr_info->dlpi_subs = obj_loads - obj_count;
3718 dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
3720 struct dl_phdr_info phdr_info;
3721 Obj_Entry *obj, marker;
3722 RtldLockState bind_lockstate, phdr_lockstate;
3725 init_marker(&marker);
3728 wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
3729 wlock_acquire(rtld_bind_lock, &bind_lockstate);
3730 for (obj = globallist_curr(TAILQ_FIRST(&obj_list)); obj != NULL;) {
3731 TAILQ_INSERT_AFTER(&obj_list, obj, &marker, next);
3732 rtld_fill_dl_phdr_info(obj, &phdr_info);
3734 lock_release(rtld_bind_lock, &bind_lockstate);
3736 error = callback(&phdr_info, sizeof phdr_info, param);
3738 wlock_acquire(rtld_bind_lock, &bind_lockstate);
3740 obj = globallist_next(&marker);
3741 TAILQ_REMOVE(&obj_list, &marker, next);
3743 lock_release(rtld_bind_lock, &bind_lockstate);
3744 lock_release(rtld_phdr_lock, &phdr_lockstate);
3750 rtld_fill_dl_phdr_info(&obj_rtld, &phdr_info);
3751 lock_release(rtld_bind_lock, &bind_lockstate);
3752 error = callback(&phdr_info, sizeof(phdr_info), param);
3754 lock_release(rtld_phdr_lock, &phdr_lockstate);
3759 fill_search_info(const char *dir, size_t dirlen, void *param)
3761 struct fill_search_info_args *arg;
3765 if (arg->request == RTLD_DI_SERINFOSIZE) {
3766 arg->serinfo->dls_cnt ++;
3767 arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
3769 struct dl_serpath *s_entry;
3771 s_entry = arg->serpath;
3772 s_entry->dls_name = arg->strspace;
3773 s_entry->dls_flags = arg->flags;
3775 strncpy(arg->strspace, dir, dirlen);
3776 arg->strspace[dirlen] = '\0';
3778 arg->strspace += dirlen + 1;
3786 do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
3788 struct dl_serinfo _info;
3789 struct fill_search_info_args args;
3791 args.request = RTLD_DI_SERINFOSIZE;
3792 args.serinfo = &_info;
3794 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
3797 path_enumerate(obj->rpath, fill_search_info, NULL, &args);
3798 path_enumerate(ld_library_path, fill_search_info, NULL, &args);
3799 path_enumerate(obj->runpath, fill_search_info, NULL, &args);
3800 path_enumerate(gethints(obj->z_nodeflib), fill_search_info, NULL, &args);
3801 if (!obj->z_nodeflib)
3802 path_enumerate(ld_standard_library_path, fill_search_info, NULL, &args);
3805 if (request == RTLD_DI_SERINFOSIZE) {
3806 info->dls_size = _info.dls_size;
3807 info->dls_cnt = _info.dls_cnt;
3811 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
3812 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
3816 args.request = RTLD_DI_SERINFO;
3817 args.serinfo = info;
3818 args.serpath = &info->dls_serpath[0];
3819 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
3821 args.flags = LA_SER_RUNPATH;
3822 if (path_enumerate(obj->rpath, fill_search_info, NULL, &args) != NULL)
3825 args.flags = LA_SER_LIBPATH;
3826 if (path_enumerate(ld_library_path, fill_search_info, NULL, &args) != NULL)
3829 args.flags = LA_SER_RUNPATH;
3830 if (path_enumerate(obj->runpath, fill_search_info, NULL, &args) != NULL)
3833 args.flags = LA_SER_CONFIG;
3834 if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, NULL, &args)
3838 args.flags = LA_SER_DEFAULT;
3839 if (!obj->z_nodeflib && path_enumerate(ld_standard_library_path,
3840 fill_search_info, NULL, &args) != NULL)
3846 rtld_dirname(const char *path, char *bname)
3850 /* Empty or NULL string gets treated as "." */
3851 if (path == NULL || *path == '\0') {
3857 /* Strip trailing slashes */
3858 endp = path + strlen(path) - 1;
3859 while (endp > path && *endp == '/')
3862 /* Find the start of the dir */
3863 while (endp > path && *endp != '/')
3866 /* Either the dir is "/" or there are no slashes */
3868 bname[0] = *endp == '/' ? '/' : '.';
3874 } while (endp > path && *endp == '/');
3877 if (endp - path + 2 > PATH_MAX)
3879 _rtld_error("Filename is too long: %s", path);
3883 strncpy(bname, path, endp - path + 1);
3884 bname[endp - path + 1] = '\0';
3889 rtld_dirname_abs(const char *path, char *base)
3893 if (realpath(path, base) == NULL)
3895 dbg("%s -> %s", path, base);
3896 last = strrchr(base, '/');
3905 linkmap_add(Obj_Entry *obj)
3907 struct link_map *l = &obj->linkmap;
3908 struct link_map *prev;
3910 obj->linkmap.l_name = obj->path;
3911 obj->linkmap.l_addr = obj->mapbase;
3912 obj->linkmap.l_ld = obj->dynamic;
3914 /* GDB needs load offset on MIPS to use the symbols */
3915 obj->linkmap.l_offs = obj->relocbase;
3918 if (r_debug.r_map == NULL) {
3924 * Scan to the end of the list, but not past the entry for the
3925 * dynamic linker, which we want to keep at the very end.
3927 for (prev = r_debug.r_map;
3928 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
3929 prev = prev->l_next)
3932 /* Link in the new entry. */
3934 l->l_next = prev->l_next;
3935 if (l->l_next != NULL)
3936 l->l_next->l_prev = l;
3941 linkmap_delete(Obj_Entry *obj)
3943 struct link_map *l = &obj->linkmap;
3945 if (l->l_prev == NULL) {
3946 if ((r_debug.r_map = l->l_next) != NULL)
3947 l->l_next->l_prev = NULL;
3951 if ((l->l_prev->l_next = l->l_next) != NULL)
3952 l->l_next->l_prev = l->l_prev;
3956 * Function for the debugger to set a breakpoint on to gain control.
3958 * The two parameters allow the debugger to easily find and determine
3959 * what the runtime loader is doing and to whom it is doing it.
3961 * When the loadhook trap is hit (r_debug_state, set at program
3962 * initialization), the arguments can be found on the stack:
3964 * +8 struct link_map *m
3965 * +4 struct r_debug *rd
3969 r_debug_state(struct r_debug* rd, struct link_map *m)
3972 * The following is a hack to force the compiler to emit calls to
3973 * this function, even when optimizing. If the function is empty,
3974 * the compiler is not obliged to emit any code for calls to it,
3975 * even when marked __noinline. However, gdb depends on those
3978 __compiler_membar();
3982 * A function called after init routines have completed. This can be used to
3983 * break before a program's entry routine is called, and can be used when
3984 * main is not available in the symbol table.
3987 _r_debug_postinit(struct link_map *m)
3990 /* See r_debug_state(). */
3991 __compiler_membar();
3995 release_object(Obj_Entry *obj)
3998 if (obj->holdcount > 0) {
3999 obj->unholdfree = true;
4002 munmap(obj->mapbase, obj->mapsize);
4003 linkmap_delete(obj);
4008 * Get address of the pointer variable in the main program.
4009 * Prefer non-weak symbol over the weak one.
4011 static const void **
4012 get_program_var_addr(const char *name, RtldLockState *lockstate)
4017 symlook_init(&req, name);
4018 req.lockstate = lockstate;
4019 donelist_init(&donelist);
4020 if (symlook_global(&req, &donelist) != 0)
4022 if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
4023 return ((const void **)make_function_pointer(req.sym_out,
4025 else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
4026 return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
4028 return ((const void **)(req.defobj_out->relocbase +
4029 req.sym_out->st_value));
4033 * Set a pointer variable in the main program to the given value. This
4034 * is used to set key variables such as "environ" before any of the
4035 * init functions are called.
4038 set_program_var(const char *name, const void *value)
4042 if ((addr = get_program_var_addr(name, NULL)) != NULL) {
4043 dbg("\"%s\": *%p <-- %p", name, addr, value);
4049 * Search the global objects, including dependencies and main object,
4050 * for the given symbol.
4053 symlook_global(SymLook *req, DoneList *donelist)
4056 const Objlist_Entry *elm;
4059 symlook_init_from_req(&req1, req);
4061 /* Search all objects loaded at program start up. */
4062 if (req->defobj_out == NULL ||
4063 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
4064 res = symlook_list(&req1, &list_main, donelist);
4065 if (res == 0 && (req->defobj_out == NULL ||
4066 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
4067 req->sym_out = req1.sym_out;
4068 req->defobj_out = req1.defobj_out;
4069 assert(req->defobj_out != NULL);
4073 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
4074 STAILQ_FOREACH(elm, &list_global, link) {
4075 if (req->defobj_out != NULL &&
4076 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
4078 res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
4079 if (res == 0 && (req->defobj_out == NULL ||
4080 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
4081 req->sym_out = req1.sym_out;
4082 req->defobj_out = req1.defobj_out;
4083 assert(req->defobj_out != NULL);
4087 return (req->sym_out != NULL ? 0 : ESRCH);
4091 * Given a symbol name in a referencing object, find the corresponding
4092 * definition of the symbol. Returns a pointer to the symbol, or NULL if
4093 * no definition was found. Returns a pointer to the Obj_Entry of the
4094 * defining object via the reference parameter DEFOBJ_OUT.
4097 symlook_default(SymLook *req, const Obj_Entry *refobj)
4100 const Objlist_Entry *elm;
4104 donelist_init(&donelist);
4105 symlook_init_from_req(&req1, req);
4108 * Look first in the referencing object if linked symbolically,
4109 * and similarly handle protected symbols.
4111 res = symlook_obj(&req1, refobj);
4112 if (res == 0 && (refobj->symbolic ||
4113 ELF_ST_VISIBILITY(req1.sym_out->st_other) == STV_PROTECTED)) {
4114 req->sym_out = req1.sym_out;
4115 req->defobj_out = req1.defobj_out;
4116 assert(req->defobj_out != NULL);
4118 if (refobj->symbolic || req->defobj_out != NULL)
4119 donelist_check(&donelist, refobj);
4121 symlook_global(req, &donelist);
4123 /* Search all dlopened DAGs containing the referencing object. */
4124 STAILQ_FOREACH(elm, &refobj->dldags, link) {
4125 if (req->sym_out != NULL &&
4126 ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
4128 res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
4129 if (res == 0 && (req->sym_out == NULL ||
4130 ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
4131 req->sym_out = req1.sym_out;
4132 req->defobj_out = req1.defobj_out;
4133 assert(req->defobj_out != NULL);
4138 * Search the dynamic linker itself, and possibly resolve the
4139 * symbol from there. This is how the application links to
4140 * dynamic linker services such as dlopen.
4142 if (req->sym_out == NULL ||
4143 ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
4144 res = symlook_obj(&req1, &obj_rtld);
4146 req->sym_out = req1.sym_out;
4147 req->defobj_out = req1.defobj_out;
4148 assert(req->defobj_out != NULL);
4152 return (req->sym_out != NULL ? 0 : ESRCH);
4156 symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
4159 const Obj_Entry *defobj;
4160 const Objlist_Entry *elm;
4166 STAILQ_FOREACH(elm, objlist, link) {
4167 if (donelist_check(dlp, elm->obj))
4169 symlook_init_from_req(&req1, req);
4170 if ((res = symlook_obj(&req1, elm->obj)) == 0) {
4171 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
4173 defobj = req1.defobj_out;
4174 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
4181 req->defobj_out = defobj;
4188 * Search the chain of DAGS cointed to by the given Needed_Entry
4189 * for a symbol of the given name. Each DAG is scanned completely
4190 * before advancing to the next one. Returns a pointer to the symbol,
4191 * or NULL if no definition was found.
4194 symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
4197 const Needed_Entry *n;
4198 const Obj_Entry *defobj;
4204 symlook_init_from_req(&req1, req);
4205 for (n = needed; n != NULL; n = n->next) {
4206 if (n->obj == NULL ||
4207 (res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
4209 if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
4211 defobj = req1.defobj_out;
4212 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
4218 req->defobj_out = defobj;
4225 * Search the symbol table of a single shared object for a symbol of
4226 * the given name and version, if requested. Returns a pointer to the
4227 * symbol, or NULL if no definition was found. If the object is
4228 * filter, return filtered symbol from filtee.
4230 * The symbol's hash value is passed in for efficiency reasons; that
4231 * eliminates many recomputations of the hash value.
4234 symlook_obj(SymLook *req, const Obj_Entry *obj)
4238 int flags, res, mres;
4241 * If there is at least one valid hash at this point, we prefer to
4242 * use the faster GNU version if available.
4244 if (obj->valid_hash_gnu)
4245 mres = symlook_obj1_gnu(req, obj);
4246 else if (obj->valid_hash_sysv)
4247 mres = symlook_obj1_sysv(req, obj);
4252 if (obj->needed_filtees != NULL) {
4253 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
4254 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
4255 donelist_init(&donelist);
4256 symlook_init_from_req(&req1, req);
4257 res = symlook_needed(&req1, obj->needed_filtees, &donelist);
4259 req->sym_out = req1.sym_out;
4260 req->defobj_out = req1.defobj_out;
4264 if (obj->needed_aux_filtees != NULL) {
4265 flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
4266 load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
4267 donelist_init(&donelist);
4268 symlook_init_from_req(&req1, req);
4269 res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
4271 req->sym_out = req1.sym_out;
4272 req->defobj_out = req1.defobj_out;
4280 /* Symbol match routine common to both hash functions */
4282 matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
4283 const unsigned long symnum)
4286 const Elf_Sym *symp;
4289 symp = obj->symtab + symnum;
4290 strp = obj->strtab + symp->st_name;
4292 switch (ELF_ST_TYPE(symp->st_info)) {
4298 if (symp->st_value == 0)
4302 if (symp->st_shndx != SHN_UNDEF)
4305 else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
4306 (ELF_ST_TYPE(symp->st_info) == STT_FUNC))
4313 if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
4316 if (req->ventry == NULL) {
4317 if (obj->versyms != NULL) {
4318 verndx = VER_NDX(obj->versyms[symnum]);
4319 if (verndx > obj->vernum) {
4321 "%s: symbol %s references wrong version %d",
4322 obj->path, obj->strtab + symnum, verndx);
4326 * If we are not called from dlsym (i.e. this
4327 * is a normal relocation from unversioned
4328 * binary), accept the symbol immediately if
4329 * it happens to have first version after this
4330 * shared object became versioned. Otherwise,
4331 * if symbol is versioned and not hidden,
4332 * remember it. If it is the only symbol with
4333 * this name exported by the shared object, it
4334 * will be returned as a match by the calling
4335 * function. If symbol is global (verndx < 2)
4336 * accept it unconditionally.
4338 if ((req->flags & SYMLOOK_DLSYM) == 0 &&
4339 verndx == VER_NDX_GIVEN) {
4340 result->sym_out = symp;
4343 else if (verndx >= VER_NDX_GIVEN) {
4344 if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
4346 if (result->vsymp == NULL)
4347 result->vsymp = symp;
4353 result->sym_out = symp;
4356 if (obj->versyms == NULL) {
4357 if (object_match_name(obj, req->ventry->name)) {
4358 _rtld_error("%s: object %s should provide version %s "
4359 "for symbol %s", obj_rtld.path, obj->path,
4360 req->ventry->name, obj->strtab + symnum);
4364 verndx = VER_NDX(obj->versyms[symnum]);
4365 if (verndx > obj->vernum) {
4366 _rtld_error("%s: symbol %s references wrong version %d",
4367 obj->path, obj->strtab + symnum, verndx);
4370 if (obj->vertab[verndx].hash != req->ventry->hash ||
4371 strcmp(obj->vertab[verndx].name, req->ventry->name)) {
4373 * Version does not match. Look if this is a
4374 * global symbol and if it is not hidden. If
4375 * global symbol (verndx < 2) is available,
4376 * use it. Do not return symbol if we are
4377 * called by dlvsym, because dlvsym looks for
4378 * a specific version and default one is not
4379 * what dlvsym wants.
4381 if ((req->flags & SYMLOOK_DLSYM) ||
4382 (verndx >= VER_NDX_GIVEN) ||
4383 (obj->versyms[symnum] & VER_NDX_HIDDEN))
4387 result->sym_out = symp;
4392 * Search for symbol using SysV hash function.
4393 * obj->buckets is known not to be NULL at this point; the test for this was
4394 * performed with the obj->valid_hash_sysv assignment.
4397 symlook_obj1_sysv(SymLook *req, const Obj_Entry *obj)
4399 unsigned long symnum;
4400 Sym_Match_Result matchres;
4402 matchres.sym_out = NULL;
4403 matchres.vsymp = NULL;
4404 matchres.vcount = 0;
4406 for (symnum = obj->buckets[req->hash % obj->nbuckets];
4407 symnum != STN_UNDEF; symnum = obj->chains[symnum]) {
4408 if (symnum >= obj->nchains)
4409 return (ESRCH); /* Bad object */
4411 if (matched_symbol(req, obj, &matchres, symnum)) {
4412 req->sym_out = matchres.sym_out;
4413 req->defobj_out = obj;
4417 if (matchres.vcount == 1) {
4418 req->sym_out = matchres.vsymp;
4419 req->defobj_out = obj;
4425 /* Search for symbol using GNU hash function */
4427 symlook_obj1_gnu(SymLook *req, const Obj_Entry *obj)
4429 Elf_Addr bloom_word;
4430 const Elf32_Word *hashval;
4432 Sym_Match_Result matchres;
4433 unsigned int h1, h2;
4434 unsigned long symnum;
4436 matchres.sym_out = NULL;
4437 matchres.vsymp = NULL;
4438 matchres.vcount = 0;
4440 /* Pick right bitmask word from Bloom filter array */
4441 bloom_word = obj->bloom_gnu[(req->hash_gnu / __ELF_WORD_SIZE) &
4442 obj->maskwords_bm_gnu];
4444 /* Calculate modulus word size of gnu hash and its derivative */
4445 h1 = req->hash_gnu & (__ELF_WORD_SIZE - 1);
4446 h2 = ((req->hash_gnu >> obj->shift2_gnu) & (__ELF_WORD_SIZE - 1));
4448 /* Filter out the "definitely not in set" queries */
4449 if (((bloom_word >> h1) & (bloom_word >> h2) & 1) == 0)
4452 /* Locate hash chain and corresponding value element*/
4453 bucket = obj->buckets_gnu[req->hash_gnu % obj->nbuckets_gnu];
4456 hashval = &obj->chain_zero_gnu[bucket];
4458 if (((*hashval ^ req->hash_gnu) >> 1) == 0) {
4459 symnum = hashval - obj->chain_zero_gnu;
4460 if (matched_symbol(req, obj, &matchres, symnum)) {
4461 req->sym_out = matchres.sym_out;
4462 req->defobj_out = obj;
4466 } while ((*hashval++ & 1) == 0);
4467 if (matchres.vcount == 1) {
4468 req->sym_out = matchres.vsymp;
4469 req->defobj_out = obj;
4476 trace_loaded_objects(Obj_Entry *obj)
4478 char *fmt1, *fmt2, *fmt, *main_local, *list_containers;
4481 if ((main_local = getenv(_LD("TRACE_LOADED_OBJECTS_PROGNAME"))) == NULL)
4484 if ((fmt1 = getenv(_LD("TRACE_LOADED_OBJECTS_FMT1"))) == NULL)
4485 fmt1 = "\t%o => %p (%x)\n";
4487 if ((fmt2 = getenv(_LD("TRACE_LOADED_OBJECTS_FMT2"))) == NULL)
4488 fmt2 = "\t%o (%x)\n";
4490 list_containers = getenv(_LD("TRACE_LOADED_OBJECTS_ALL"));
4492 for (; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
4493 Needed_Entry *needed;
4499 if (list_containers && obj->needed != NULL)
4500 rtld_printf("%s:\n", obj->path);
4501 for (needed = obj->needed; needed; needed = needed->next) {
4502 if (needed->obj != NULL) {
4503 if (needed->obj->traced && !list_containers)
4505 needed->obj->traced = true;
4506 path = needed->obj->path;
4510 name = (char *)obj->strtab + needed->name;
4511 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
4513 fmt = is_lib ? fmt1 : fmt2;
4514 while ((c = *fmt++) != '\0') {
4540 rtld_putstr(main_local);
4543 rtld_putstr(obj_main->path);
4550 rtld_printf("%d", sodp->sod_major);
4553 rtld_printf("%d", sodp->sod_minor);
4560 rtld_printf("%p", needed->obj ? needed->obj->mapbase :
4573 * Unload a dlopened object and its dependencies from memory and from
4574 * our data structures. It is assumed that the DAG rooted in the
4575 * object has already been unreferenced, and that the object has a
4576 * reference count of 0.
4579 unload_object(Obj_Entry *root, RtldLockState *lockstate)
4581 Obj_Entry marker, *obj, *next;
4583 assert(root->refcount == 0);
4586 * Pass over the DAG removing unreferenced objects from
4587 * appropriate lists.
4589 unlink_object(root);
4591 /* Unmap all objects that are no longer referenced. */
4592 for (obj = TAILQ_FIRST(&obj_list); obj != NULL; obj = next) {
4593 next = TAILQ_NEXT(obj, next);
4594 if (obj->marker || obj->refcount != 0)
4596 LD_UTRACE(UTRACE_UNLOAD_OBJECT, obj, obj->mapbase,
4597 obj->mapsize, 0, obj->path);
4598 dbg("unloading \"%s\"", obj->path);
4600 * Unlink the object now to prevent new references from
4601 * being acquired while the bind lock is dropped in
4602 * recursive dlclose() invocations.
4604 TAILQ_REMOVE(&obj_list, obj, next);
4607 if (obj->filtees_loaded) {
4609 init_marker(&marker);
4610 TAILQ_INSERT_BEFORE(next, &marker, next);
4611 unload_filtees(obj, lockstate);
4612 next = TAILQ_NEXT(&marker, next);
4613 TAILQ_REMOVE(&obj_list, &marker, next);
4615 unload_filtees(obj, lockstate);
4617 release_object(obj);
4622 unlink_object(Obj_Entry *root)
4626 if (root->refcount == 0) {
4627 /* Remove the object from the RTLD_GLOBAL list. */
4628 objlist_remove(&list_global, root);
4630 /* Remove the object from all objects' DAG lists. */
4631 STAILQ_FOREACH(elm, &root->dagmembers, link) {
4632 objlist_remove(&elm->obj->dldags, root);
4633 if (elm->obj != root)
4634 unlink_object(elm->obj);
4640 ref_dag(Obj_Entry *root)
4644 assert(root->dag_inited);
4645 STAILQ_FOREACH(elm, &root->dagmembers, link)
4646 elm->obj->refcount++;
4650 unref_dag(Obj_Entry *root)
4654 assert(root->dag_inited);
4655 STAILQ_FOREACH(elm, &root->dagmembers, link)
4656 elm->obj->refcount--;
4660 * Common code for MD __tls_get_addr().
4662 static void *tls_get_addr_slow(Elf_Addr **, int, size_t) __noinline;
4664 tls_get_addr_slow(Elf_Addr **dtvp, int index, size_t offset)
4666 Elf_Addr *newdtv, *dtv;
4667 RtldLockState lockstate;
4671 /* Check dtv generation in case new modules have arrived */
4672 if (dtv[0] != tls_dtv_generation) {
4673 wlock_acquire(rtld_bind_lock, &lockstate);
4674 newdtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4676 if (to_copy > tls_max_index)
4677 to_copy = tls_max_index;
4678 memcpy(&newdtv[2], &dtv[2], to_copy * sizeof(Elf_Addr));
4679 newdtv[0] = tls_dtv_generation;
4680 newdtv[1] = tls_max_index;
4682 lock_release(rtld_bind_lock, &lockstate);
4683 dtv = *dtvp = newdtv;
4686 /* Dynamically allocate module TLS if necessary */
4687 if (dtv[index + 1] == 0) {
4688 /* Signal safe, wlock will block out signals. */
4689 wlock_acquire(rtld_bind_lock, &lockstate);
4690 if (!dtv[index + 1])
4691 dtv[index + 1] = (Elf_Addr)allocate_module_tls(index);
4692 lock_release(rtld_bind_lock, &lockstate);
4694 return ((void *)(dtv[index + 1] + offset));
4698 tls_get_addr_common(Elf_Addr **dtvp, int index, size_t offset)
4703 /* Check dtv generation in case new modules have arrived */
4704 if (__predict_true(dtv[0] == tls_dtv_generation &&
4705 dtv[index + 1] != 0))
4706 return ((void *)(dtv[index + 1] + offset));
4707 return (tls_get_addr_slow(dtvp, index, offset));
4710 #if defined(__aarch64__) || defined(__arm__) || defined(__mips__) || \
4711 defined(__powerpc__) || defined(__riscv)
4714 * Return pointer to allocated TLS block
4717 get_tls_block_ptr(void *tcb, size_t tcbsize)
4719 size_t extra_size, post_size, pre_size, tls_block_size;
4720 size_t tls_init_align;
4722 tls_init_align = MAX(obj_main->tlsalign, 1);
4724 /* Compute fragments sizes. */
4725 extra_size = tcbsize - TLS_TCB_SIZE;
4726 post_size = calculate_tls_post_size(tls_init_align);
4727 tls_block_size = tcbsize + post_size;
4728 pre_size = roundup2(tls_block_size, tls_init_align) - tls_block_size;
4730 return ((char *)tcb - pre_size - extra_size);
4734 * Allocate Static TLS using the Variant I method.
4736 * For details on the layout, see lib/libc/gen/tls.c.
4738 * NB: rtld's tls_static_space variable includes TLS_TCB_SIZE and post_size as
4739 * it is based on tls_last_offset, and TLS offsets here are really TCB
4740 * offsets, whereas libc's tls_static_space is just the executable's static
4744 allocate_tls(Obj_Entry *objs, void *oldtcb, size_t tcbsize, size_t tcbalign)
4748 Elf_Addr *dtv, **tcb;
4751 size_t extra_size, maxalign, post_size, pre_size, tls_block_size;
4752 size_t tls_init_align;
4754 if (oldtcb != NULL && tcbsize == TLS_TCB_SIZE)
4757 assert(tcbsize >= TLS_TCB_SIZE);
4758 maxalign = MAX(tcbalign, tls_static_max_align);
4759 tls_init_align = MAX(obj_main->tlsalign, 1);
4761 /* Compute fragmets sizes. */
4762 extra_size = tcbsize - TLS_TCB_SIZE;
4763 post_size = calculate_tls_post_size(tls_init_align);
4764 tls_block_size = tcbsize + post_size;
4765 pre_size = roundup2(tls_block_size, tls_init_align) - tls_block_size;
4766 tls_block_size += pre_size + tls_static_space - TLS_TCB_SIZE - post_size;
4768 /* Allocate whole TLS block */
4769 tls_block = malloc_aligned(tls_block_size, maxalign);
4770 tcb = (Elf_Addr **)(tls_block + pre_size + extra_size);
4772 if (oldtcb != NULL) {
4773 memcpy(tls_block, get_tls_block_ptr(oldtcb, tcbsize),
4775 free_aligned(get_tls_block_ptr(oldtcb, tcbsize));
4777 /* Adjust the DTV. */
4779 for (i = 0; i < dtv[1]; i++) {
4780 if (dtv[i+2] >= (Elf_Addr)oldtcb &&
4781 dtv[i+2] < (Elf_Addr)oldtcb + tls_static_space) {
4782 dtv[i+2] = dtv[i+2] - (Elf_Addr)oldtcb + (Elf_Addr)tcb;
4786 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4788 dtv[0] = tls_dtv_generation;
4789 dtv[1] = tls_max_index;
4791 for (obj = globallist_curr(objs); obj != NULL;
4792 obj = globallist_next(obj)) {
4793 if (obj->tlsoffset > 0) {
4794 addr = (Elf_Addr)tcb + obj->tlsoffset;
4795 if (obj->tlsinitsize > 0)
4796 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4797 if (obj->tlssize > obj->tlsinitsize)
4798 memset((void*) (addr + obj->tlsinitsize), 0,
4799 obj->tlssize - obj->tlsinitsize);
4800 dtv[obj->tlsindex + 1] = addr;
4809 free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
4812 Elf_Addr tlsstart, tlsend;
4814 size_t dtvsize, i, tls_init_align;
4816 assert(tcbsize >= TLS_TCB_SIZE);
4817 tls_init_align = MAX(obj_main->tlsalign, 1);
4819 /* Compute fragments sizes. */
4820 post_size = calculate_tls_post_size(tls_init_align);
4822 tlsstart = (Elf_Addr)tcb + TLS_TCB_SIZE + post_size;
4823 tlsend = (Elf_Addr)tcb + tls_static_space;
4825 dtv = *(Elf_Addr **)tcb;
4827 for (i = 0; i < dtvsize; i++) {
4828 if (dtv[i+2] && (dtv[i+2] < tlsstart || dtv[i+2] >= tlsend)) {
4829 free((void*)dtv[i+2]);
4833 free_aligned(get_tls_block_ptr(tcb, tcbsize));
4838 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__)
4841 * Allocate Static TLS using the Variant II method.
4844 allocate_tls(Obj_Entry *objs, void *oldtls, size_t tcbsize, size_t tcbalign)
4847 size_t size, ralign;
4849 Elf_Addr *dtv, *olddtv;
4850 Elf_Addr segbase, oldsegbase, addr;
4854 if (tls_static_max_align > ralign)
4855 ralign = tls_static_max_align;
4856 size = round(tls_static_space, ralign) + round(tcbsize, ralign);
4858 assert(tcbsize >= 2*sizeof(Elf_Addr));
4859 tls = malloc_aligned(size, ralign);
4860 dtv = xcalloc(tls_max_index + 2, sizeof(Elf_Addr));
4862 segbase = (Elf_Addr)(tls + round(tls_static_space, ralign));
4863 ((Elf_Addr*)segbase)[0] = segbase;
4864 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
4866 dtv[0] = tls_dtv_generation;
4867 dtv[1] = tls_max_index;
4871 * Copy the static TLS block over whole.
4873 oldsegbase = (Elf_Addr) oldtls;
4874 memcpy((void *)(segbase - tls_static_space),
4875 (const void *)(oldsegbase - tls_static_space),
4879 * If any dynamic TLS blocks have been created tls_get_addr(),
4882 olddtv = ((Elf_Addr**)oldsegbase)[1];
4883 for (i = 0; i < olddtv[1]; i++) {
4884 if (olddtv[i+2] < oldsegbase - size || olddtv[i+2] > oldsegbase) {
4885 dtv[i+2] = olddtv[i+2];
4891 * We assume that this block was the one we created with
4892 * allocate_initial_tls().
4894 free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
4896 for (obj = objs; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
4897 if (obj->marker || obj->tlsoffset == 0)
4899 addr = segbase - obj->tlsoffset;
4900 memset((void*) (addr + obj->tlsinitsize),
4901 0, obj->tlssize - obj->tlsinitsize);
4903 memcpy((void*) addr, obj->tlsinit, obj->tlsinitsize);
4904 dtv[obj->tlsindex + 1] = addr;
4908 return (void*) segbase;
4912 free_tls(void *tls, size_t tcbsize, size_t tcbalign)
4915 size_t size, ralign;
4917 Elf_Addr tlsstart, tlsend;
4920 * Figure out the size of the initial TLS block so that we can
4921 * find stuff which ___tls_get_addr() allocated dynamically.
4924 if (tls_static_max_align > ralign)
4925 ralign = tls_static_max_align;
4926 size = round(tls_static_space, ralign);
4928 dtv = ((Elf_Addr**)tls)[1];
4930 tlsend = (Elf_Addr) tls;
4931 tlsstart = tlsend - size;
4932 for (i = 0; i < dtvsize; i++) {
4933 if (dtv[i + 2] != 0 && (dtv[i + 2] < tlsstart || dtv[i + 2] > tlsend)) {
4934 free_aligned((void *)dtv[i + 2]);
4938 free_aligned((void *)tlsstart);
4945 * Allocate TLS block for module with given index.
4948 allocate_module_tls(int index)
4953 TAILQ_FOREACH(obj, &obj_list, next) {
4956 if (obj->tlsindex == index)
4960 _rtld_error("Can't find module with TLS index %d", index);
4964 p = malloc_aligned(obj->tlssize, obj->tlsalign);
4965 memcpy(p, obj->tlsinit, obj->tlsinitsize);
4966 memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
4972 allocate_tls_offset(Obj_Entry *obj)
4979 if (obj->tlssize == 0) {
4980 obj->tls_done = true;
4984 if (tls_last_offset == 0)
4985 off = calculate_first_tls_offset(obj->tlssize, obj->tlsalign);
4987 off = calculate_tls_offset(tls_last_offset, tls_last_size,
4988 obj->tlssize, obj->tlsalign);
4991 * If we have already fixed the size of the static TLS block, we
4992 * must stay within that size. When allocating the static TLS, we
4993 * leave a small amount of space spare to be used for dynamically
4994 * loading modules which use static TLS.
4996 if (tls_static_space != 0) {
4997 if (calculate_tls_end(off, obj->tlssize) > tls_static_space)
4999 } else if (obj->tlsalign > tls_static_max_align) {
5000 tls_static_max_align = obj->tlsalign;
5003 tls_last_offset = obj->tlsoffset = off;
5004 tls_last_size = obj->tlssize;
5005 obj->tls_done = true;
5011 free_tls_offset(Obj_Entry *obj)
5015 * If we were the last thing to allocate out of the static TLS
5016 * block, we give our space back to the 'allocator'. This is a
5017 * simplistic workaround to allow libGL.so.1 to be loaded and
5018 * unloaded multiple times.
5020 if (calculate_tls_end(obj->tlsoffset, obj->tlssize)
5021 == calculate_tls_end(tls_last_offset, tls_last_size)) {
5022 tls_last_offset -= obj->tlssize;
5028 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
5031 RtldLockState lockstate;
5033 wlock_acquire(rtld_bind_lock, &lockstate);
5034 ret = allocate_tls(globallist_curr(TAILQ_FIRST(&obj_list)), oldtls,
5036 lock_release(rtld_bind_lock, &lockstate);
5041 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
5043 RtldLockState lockstate;
5045 wlock_acquire(rtld_bind_lock, &lockstate);
5046 free_tls(tcb, tcbsize, tcbalign);
5047 lock_release(rtld_bind_lock, &lockstate);
5051 object_add_name(Obj_Entry *obj, const char *name)
5057 entry = malloc(sizeof(Name_Entry) + len);
5059 if (entry != NULL) {
5060 strcpy(entry->name, name);
5061 STAILQ_INSERT_TAIL(&obj->names, entry, link);
5066 object_match_name(const Obj_Entry *obj, const char *name)
5070 STAILQ_FOREACH(entry, &obj->names, link) {
5071 if (strcmp(name, entry->name) == 0)
5078 locate_dependency(const Obj_Entry *obj, const char *name)
5080 const Objlist_Entry *entry;
5081 const Needed_Entry *needed;
5083 STAILQ_FOREACH(entry, &list_main, link) {
5084 if (object_match_name(entry->obj, name))
5088 for (needed = obj->needed; needed != NULL; needed = needed->next) {
5089 if (strcmp(obj->strtab + needed->name, name) == 0 ||
5090 (needed->obj != NULL && object_match_name(needed->obj, name))) {
5092 * If there is DT_NEEDED for the name we are looking for,
5093 * we are all set. Note that object might not be found if
5094 * dependency was not loaded yet, so the function can
5095 * return NULL here. This is expected and handled
5096 * properly by the caller.
5098 return (needed->obj);
5101 _rtld_error("%s: Unexpected inconsistency: dependency %s not found",
5107 check_object_provided_version(Obj_Entry *refobj, const Obj_Entry *depobj,
5108 const Elf_Vernaux *vna)
5110 const Elf_Verdef *vd;
5111 const char *vername;
5113 vername = refobj->strtab + vna->vna_name;
5114 vd = depobj->verdef;
5116 _rtld_error("%s: version %s required by %s not defined",
5117 depobj->path, vername, refobj->path);
5121 if (vd->vd_version != VER_DEF_CURRENT) {
5122 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
5123 depobj->path, vd->vd_version);
5126 if (vna->vna_hash == vd->vd_hash) {
5127 const Elf_Verdaux *aux = (const Elf_Verdaux *)
5128 ((char *)vd + vd->vd_aux);
5129 if (strcmp(vername, depobj->strtab + aux->vda_name) == 0)
5132 if (vd->vd_next == 0)
5134 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
5136 if (vna->vna_flags & VER_FLG_WEAK)
5138 _rtld_error("%s: version %s required by %s not found",
5139 depobj->path, vername, refobj->path);
5144 rtld_verify_object_versions(Obj_Entry *obj)
5146 const Elf_Verneed *vn;
5147 const Elf_Verdef *vd;
5148 const Elf_Verdaux *vda;
5149 const Elf_Vernaux *vna;
5150 const Obj_Entry *depobj;
5151 int maxvernum, vernum;
5153 if (obj->ver_checked)
5155 obj->ver_checked = true;
5159 * Walk over defined and required version records and figure out
5160 * max index used by any of them. Do very basic sanity checking
5164 while (vn != NULL) {
5165 if (vn->vn_version != VER_NEED_CURRENT) {
5166 _rtld_error("%s: Unsupported version %d of Elf_Verneed entry",
5167 obj->path, vn->vn_version);
5170 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
5172 vernum = VER_NEED_IDX(vna->vna_other);
5173 if (vernum > maxvernum)
5175 if (vna->vna_next == 0)
5177 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
5179 if (vn->vn_next == 0)
5181 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
5185 while (vd != NULL) {
5186 if (vd->vd_version != VER_DEF_CURRENT) {
5187 _rtld_error("%s: Unsupported version %d of Elf_Verdef entry",
5188 obj->path, vd->vd_version);
5191 vernum = VER_DEF_IDX(vd->vd_ndx);
5192 if (vernum > maxvernum)
5194 if (vd->vd_next == 0)
5196 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
5203 * Store version information in array indexable by version index.
5204 * Verify that object version requirements are satisfied along the
5207 obj->vernum = maxvernum + 1;
5208 obj->vertab = xcalloc(obj->vernum, sizeof(Ver_Entry));
5211 while (vd != NULL) {
5212 if ((vd->vd_flags & VER_FLG_BASE) == 0) {
5213 vernum = VER_DEF_IDX(vd->vd_ndx);
5214 assert(vernum <= maxvernum);
5215 vda = (const Elf_Verdaux *)((char *)vd + vd->vd_aux);
5216 obj->vertab[vernum].hash = vd->vd_hash;
5217 obj->vertab[vernum].name = obj->strtab + vda->vda_name;
5218 obj->vertab[vernum].file = NULL;
5219 obj->vertab[vernum].flags = 0;
5221 if (vd->vd_next == 0)
5223 vd = (const Elf_Verdef *) ((char *)vd + vd->vd_next);
5227 while (vn != NULL) {
5228 depobj = locate_dependency(obj, obj->strtab + vn->vn_file);
5231 vna = (const Elf_Vernaux *) ((char *)vn + vn->vn_aux);
5233 if (check_object_provided_version(obj, depobj, vna))
5235 vernum = VER_NEED_IDX(vna->vna_other);
5236 assert(vernum <= maxvernum);
5237 obj->vertab[vernum].hash = vna->vna_hash;
5238 obj->vertab[vernum].name = obj->strtab + vna->vna_name;
5239 obj->vertab[vernum].file = obj->strtab + vn->vn_file;
5240 obj->vertab[vernum].flags = (vna->vna_other & VER_NEED_HIDDEN) ?
5241 VER_INFO_HIDDEN : 0;
5242 if (vna->vna_next == 0)
5244 vna = (const Elf_Vernaux *) ((char *)vna + vna->vna_next);
5246 if (vn->vn_next == 0)
5248 vn = (const Elf_Verneed *) ((char *)vn + vn->vn_next);
5254 rtld_verify_versions(const Objlist *objlist)
5256 Objlist_Entry *entry;
5260 STAILQ_FOREACH(entry, objlist, link) {
5262 * Skip dummy objects or objects that have their version requirements
5265 if (entry->obj->strtab == NULL || entry->obj->vertab != NULL)
5267 if (rtld_verify_object_versions(entry->obj) == -1) {
5269 if (ld_tracing == NULL)
5273 if (rc == 0 || ld_tracing != NULL)
5274 rc = rtld_verify_object_versions(&obj_rtld);
5279 fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
5284 vernum = VER_NDX(obj->versyms[symnum]);
5285 if (vernum >= obj->vernum) {
5286 _rtld_error("%s: symbol %s has wrong verneed value %d",
5287 obj->path, obj->strtab + symnum, vernum);
5288 } else if (obj->vertab[vernum].hash != 0) {
5289 return &obj->vertab[vernum];
5296 _rtld_get_stack_prot(void)
5299 return (stack_prot);
5303 _rtld_is_dlopened(void *arg)
5306 RtldLockState lockstate;
5309 rlock_acquire(rtld_bind_lock, &lockstate);
5312 obj = obj_from_addr(arg);
5314 _rtld_error("No shared object contains address");
5315 lock_release(rtld_bind_lock, &lockstate);
5318 res = obj->dlopened ? 1 : 0;
5319 lock_release(rtld_bind_lock, &lockstate);
5324 obj_enforce_relro(Obj_Entry *obj)
5327 if (obj->relro_size > 0 && mprotect(obj->relro_page, obj->relro_size,
5329 _rtld_error("%s: Cannot enforce relro protection: %s",
5330 obj->path, rtld_strerror(errno));
5337 map_stacks_exec(RtldLockState *lockstate)
5339 void (*thr_map_stacks_exec)(void);
5341 if ((max_stack_flags & PF_X) == 0 || (stack_prot & PROT_EXEC) != 0)
5343 thr_map_stacks_exec = (void (*)(void))(uintptr_t)
5344 get_program_var_addr("__pthread_map_stacks_exec", lockstate);
5345 if (thr_map_stacks_exec != NULL) {
5346 stack_prot |= PROT_EXEC;
5347 thr_map_stacks_exec();
5352 symlook_init(SymLook *dst, const char *name)
5355 bzero(dst, sizeof(*dst));
5357 dst->hash = elf_hash(name);
5358 dst->hash_gnu = gnu_hash(name);
5362 symlook_init_from_req(SymLook *dst, const SymLook *src)
5365 dst->name = src->name;
5366 dst->hash = src->hash;
5367 dst->hash_gnu = src->hash_gnu;
5368 dst->ventry = src->ventry;
5369 dst->flags = src->flags;
5370 dst->defobj_out = NULL;
5371 dst->sym_out = NULL;
5372 dst->lockstate = src->lockstate;
5376 open_binary_fd(const char *argv0, bool search_in_path)
5378 char *pathenv, *pe, binpath[PATH_MAX];
5381 if (search_in_path && strchr(argv0, '/') == NULL) {
5382 pathenv = getenv("PATH");
5383 if (pathenv == NULL) {
5384 _rtld_error("-p and no PATH environment variable");
5387 pathenv = strdup(pathenv);
5388 if (pathenv == NULL) {
5389 _rtld_error("Cannot allocate memory");
5394 while ((pe = strsep(&pathenv, ":")) != NULL) {
5395 if (strlcpy(binpath, pe, sizeof(binpath)) >=
5398 if (binpath[0] != '\0' &&
5399 strlcat(binpath, "/", sizeof(binpath)) >=
5402 if (strlcat(binpath, argv0, sizeof(binpath)) >=
5405 fd = open(binpath, O_RDONLY | O_CLOEXEC | O_VERIFY);
5406 if (fd != -1 || errno != ENOENT)
5411 fd = open(argv0, O_RDONLY | O_CLOEXEC | O_VERIFY);
5415 _rtld_error("Cannot open %s: %s", argv0, rtld_strerror(errno));
5422 * Parse a set of command-line arguments.
5425 parse_args(char* argv[], int argc, bool *use_pathp, int *fdp)
5428 int fd, i, j, arglen;
5431 dbg("Parsing command-line arguments");
5435 for (i = 1; i < argc; i++ ) {
5437 dbg("argv[%d]: '%s'", i, arg);
5440 * rtld arguments end with an explicit "--" or with the first
5441 * non-prefixed argument.
5443 if (strcmp(arg, "--") == 0) {
5451 * All other arguments are single-character options that can
5452 * be combined, so we need to search through `arg` for them.
5454 arglen = strlen(arg);
5455 for (j = 1; j < arglen; j++) {
5458 print_usage(argv[0]);
5460 } else if (opt == 'f') {
5462 * -f XX can be used to specify a descriptor for the
5463 * binary named at the command line (i.e., the later
5464 * argument will specify the process name but the
5465 * descriptor is what will actually be executed)
5467 if (j != arglen - 1) {
5468 /* -f must be the last option in, e.g., -abcf */
5469 _rtld_error("Invalid options: %s", arg);
5473 fd = parse_integer(argv[i]);
5475 _rtld_error("Invalid file descriptor: '%s'",
5481 } else if (opt == 'p') {
5484 _rtld_error("Invalid argument: '%s'", arg);
5485 print_usage(argv[0]);
5495 * Parse a file descriptor number without pulling in more of libc (e.g. atoi).
5498 parse_integer(const char *str)
5500 static const int RADIX = 10; /* XXXJA: possibly support hex? */
5507 for (c = *str; c != '\0'; c = *++str) {
5508 if (c < '0' || c > '9')
5515 /* Make sure we actually parsed something. */
5522 print_usage(const char *argv0)
5525 rtld_printf("Usage: %s [-h] [-f <FD>] [--] <binary> [<args>]\n"
5528 " -h Display this help message\n"
5529 " -p Search in PATH for named binary\n"
5530 " -f <FD> Execute <FD> instead of searching for <binary>\n"
5531 " -- End of RTLD options\n"
5532 " <binary> Name of process to execute\n"
5533 " <args> Arguments to the executed process\n", argv0);
5537 * Overrides for libc_pic-provided functions.
5541 __getosreldate(void)
5551 oid[1] = KERN_OSRELDATE;
5553 len = sizeof(osrel);
5554 error = sysctl(oid, 2, &osrel, &len, NULL, 0);
5555 if (error == 0 && osrel > 0 && len == sizeof(osrel))
5567 void (*__cleanup)(void);
5568 int __isthreaded = 0;
5569 int _thread_autoinit_dummy_decl = 1;
5572 * No unresolved symbols for rtld.
5575 __pthread_cxa_finalize(struct dl_phdr_info *a)
5580 rtld_strerror(int errnum)
5583 if (errnum < 0 || errnum >= sys_nerr)
5584 return ("Unknown error");
5585 return (sys_errlist[errnum]);