Clear the NOCORE flag on any text mappings that the RTLD modifies due to
[dragonfly.git] / libexec / rtld-elf / rtld.c
CommitLineData
984263bc
MD
1/*-
2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3 * Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 *
26 * $FreeBSD: src/libexec/rtld-elf/rtld.c,v 1.43.2.15 2003/02/20 20:42:46 kan Exp $
4b89341e 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.8 2004/11/18 10:01:47 dillon Exp $
984263bc
MD
28 */
29
30/*
31 * Dynamic linker for ELF.
32 *
33 * John Polstra <jdp@polstra.com>.
34 */
35
36#ifndef __GNUC__
37#error "GCC is needed to compile this file"
38#endif
39
40#include <sys/param.h>
41#include <sys/mman.h>
42#include <sys/stat.h>
8ca15ec8 43#include <sys/resident.h>
984263bc
MD
44
45#include <dlfcn.h>
46#include <err.h>
47#include <errno.h>
48#include <fcntl.h>
49#include <stdarg.h>
50#include <stdio.h>
51#include <stdlib.h>
52#include <string.h>
53#include <unistd.h>
54
55#include "debug.h"
56#include "rtld.h"
57
58#define END_SYM "_end"
59#define PATH_RTLD "/usr/libexec/ld-elf.so.1"
8ca15ec8 60#define LD_ARY_CACHE 16
984263bc
MD
61
62/* Types. */
63typedef void (*func_ptr_type)();
64typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
65
66/*
67 * This structure provides a reentrant way to keep a list of objects and
68 * check which ones have already been processed in some way.
69 */
70typedef struct Struct_DoneList {
71 const Obj_Entry **objs; /* Array of object pointers */
72 unsigned int num_alloc; /* Allocated size of the array */
73 unsigned int num_used; /* Number of array slots used */
74} DoneList;
75
76/*
77 * Function declarations.
78 */
984263bc
MD
79static void die(void);
80static void digest_dynamic(Obj_Entry *);
8ca15ec8 81static const char *_getenv_ld(const char *id);
984263bc
MD
82static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
83static Obj_Entry *dlcheck(void *);
84static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
85static bool donelist_check(DoneList *, const Obj_Entry *);
86static void errmsg_restore(char *);
87static char *errmsg_save(void);
88static void *fill_search_info(const char *, size_t, void *);
89static char *find_library(const char *, const Obj_Entry *);
90static const char *gethints(void);
91static void init_dag(Obj_Entry *);
92static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *);
93static void init_rtld(caddr_t);
94static void initlist_add_neededs(Needed_Entry *needed, Objlist *list);
95static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail,
96 Objlist *list);
97static bool is_exported(const Elf_Sym *);
98static void linkmap_add(Obj_Entry *);
99static void linkmap_delete(Obj_Entry *);
100static int load_needed_objects(Obj_Entry *);
101static int load_preload_objects(void);
102static Obj_Entry *load_object(char *);
103static void lock_check(void);
104static Obj_Entry *obj_from_addr(const void *);
105static void objlist_call_fini(Objlist *);
106static void objlist_call_init(Objlist *);
107static void objlist_clear(Objlist *);
108static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
109static void objlist_init(Objlist *);
110static void objlist_push_head(Objlist *, Obj_Entry *);
111static void objlist_push_tail(Objlist *, Obj_Entry *);
112static void objlist_remove(Objlist *, Obj_Entry *);
113static void objlist_remove_unref(Objlist *);
114static void *path_enumerate(const char *, path_enum_proc, void *);
115static int relocate_objects(Obj_Entry *, bool);
116static int rtld_dirname(const char *, char *);
117static void rtld_exit(void);
118static char *search_library_path(const char *, const char *);
119static const void **get_program_var_addr(const char *name);
120static void set_program_var(const char *, const void *);
121static const Elf_Sym *symlook_default(const char *, unsigned long hash,
122 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
123static const Elf_Sym *symlook_list(const char *, unsigned long,
124 Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
125static void trace_loaded_objects(Obj_Entry *obj);
126static void unlink_object(Obj_Entry *);
127static void unload_object(Obj_Entry *);
128static void unref_dag(Obj_Entry *);
129
130void r_debug_state(struct r_debug*, struct link_map*);
131
132/*
133 * Data declarations.
134 */
135static char *error_message; /* Message for dlerror(), or NULL */
136struct r_debug r_debug; /* for GDB; */
137static bool trust; /* False for setuid and setgid programs */
8ca15ec8
MD
138static const char *ld_bind_now; /* Environment variable for immediate binding */
139static const char *ld_debug; /* Environment variable for debugging */
140static const char *ld_library_path; /* Environment variable for search path */
984263bc
MD
141static char *ld_preload; /* Environment variable for libraries to
142 load first */
8ca15ec8 143static const char *ld_tracing; /* Called from ldd(1) to print libs */
984263bc
MD
144static Obj_Entry *obj_list; /* Head of linked list of shared objects */
145static Obj_Entry **obj_tail; /* Link field of last object in list */
8ca15ec8 146static Obj_Entry **preload_tail;
984263bc
MD
147static Obj_Entry *obj_main; /* The main program shared object */
148static Obj_Entry obj_rtld; /* The dynamic linker shared object */
149static unsigned int obj_count; /* Number of objects in obj_list */
33a8b578 150static int ld_resident; /* Non-zero if resident */
8ca15ec8
MD
151static const char *ld_ary[LD_ARY_CACHE];
152static int ld_index;
984263bc
MD
153
154static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
155 STAILQ_HEAD_INITIALIZER(list_global);
156static Objlist list_main = /* Objects loaded at program startup */
157 STAILQ_HEAD_INITIALIZER(list_main);
158static Objlist list_fini = /* Objects needing fini() calls */
159 STAILQ_HEAD_INITIALIZER(list_fini);
160
161static LockInfo lockinfo;
162
163static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
164
165#define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
166
167extern Elf_Dyn _DYNAMIC;
168#pragma weak _DYNAMIC
169
170/*
171 * These are the functions the dynamic linker exports to application
172 * programs. They are the only symbols the dynamic linker is willing
173 * to export from itself.
174 */
175static func_ptr_type exports[] = {
176 (func_ptr_type) &_rtld_error,
177 (func_ptr_type) &dlclose,
178 (func_ptr_type) &dlerror,
179 (func_ptr_type) &dlopen,
180 (func_ptr_type) &dlsym,
181 (func_ptr_type) &dladdr,
182 (func_ptr_type) &dllockinit,
183 (func_ptr_type) &dlinfo,
184 NULL
185};
186
187/*
188 * Global declarations normally provided by crt1. The dynamic linker is
189 * not built with crt1, so we have to provide them ourselves.
190 */
191char *__progname;
192char **environ;
193
194/*
195 * Fill in a DoneList with an allocation large enough to hold all of
196 * the currently-loaded objects. Keep this as a macro since it calls
197 * alloca and we want that to occur within the scope of the caller.
198 */
199#define donelist_init(dlp) \
200 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
201 assert((dlp)->objs != NULL), \
202 (dlp)->num_alloc = obj_count, \
203 (dlp)->num_used = 0)
204
205static __inline void
206rlock_acquire(void)
207{
208 lockinfo.rlock_acquire(lockinfo.thelock);
209 atomic_incr_int(&lockinfo.rcount);
210 lock_check();
211}
212
213static __inline void
214wlock_acquire(void)
215{
216 lockinfo.wlock_acquire(lockinfo.thelock);
217 atomic_incr_int(&lockinfo.wcount);
218 lock_check();
219}
220
221static __inline void
222rlock_release(void)
223{
224 atomic_decr_int(&lockinfo.rcount);
225 lockinfo.rlock_release(lockinfo.thelock);
226}
227
228static __inline void
229wlock_release(void)
230{
231 atomic_decr_int(&lockinfo.wcount);
232 lockinfo.wlock_release(lockinfo.thelock);
233}
234
235/*
236 * Main entry point for dynamic linking. The first argument is the
237 * stack pointer. The stack is expected to be laid out as described
238 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
239 * Specifically, the stack pointer points to a word containing
240 * ARGC. Following that in the stack is a null-terminated sequence
241 * of pointers to argument strings. Then comes a null-terminated
242 * sequence of pointers to environment strings. Finally, there is a
243 * sequence of "auxiliary vector" entries.
244 *
245 * The second argument points to a place to store the dynamic linker's
246 * exit procedure pointer and the third to a place to store the main
247 * program's object.
248 *
249 * The return value is the main program's entry point.
250 */
251func_ptr_type
252_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
253{
254 Elf_Auxinfo *aux_info[AT_COUNT];
255 int i;
256 int argc;
257 char **argv;
258 char **env;
259 Elf_Auxinfo *aux;
260 Elf_Auxinfo *auxp;
261 const char *argv0;
262 Obj_Entry *obj;
984263bc
MD
263 Objlist initlist;
264
8ca15ec8
MD
265 ld_index = 0; /* don't use old env cache in case we are resident */
266
984263bc
MD
267 /*
268 * On entry, the dynamic linker itself has not been relocated yet.
269 * Be very careful not to reference any global data until after
270 * init_rtld has returned. It is OK to reference file-scope statics
271 * and string constants, and to call static and global functions.
272 */
273
274 /* Find the auxiliary vector on the stack. */
275 argc = *sp++;
276 argv = (char **) sp;
277 sp += argc + 1; /* Skip over arguments and NULL terminator */
278 env = (char **) sp;
984263bc 279
33a8b578
MD
280 /*
281 * If we aren't already resident we have to dig out some more info.
282 * Note that auxinfo does not exist when we are resident.
283 */
284 if (ld_resident == 0) {
285 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
286 ;
287 aux = (Elf_Auxinfo *) sp;
288
289 /* Digest the auxiliary vector. */
290 for (i = 0; i < AT_COUNT; i++)
291 aux_info[i] = NULL;
292 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
293 if (auxp->a_type < AT_COUNT)
294 aux_info[auxp->a_type] = auxp;
295 }
296
297 /* Initialize and relocate ourselves. */
298 assert(aux_info[AT_BASE] != NULL);
299 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
300 }
984263bc
MD
301
302 __progname = obj_rtld.path;
303 argv0 = argv[0] != NULL ? argv[0] : "(null)";
304 environ = env;
305
8ca15ec8 306 trust = (geteuid() == getuid()) && (getegid() == getgid());
984263bc 307
8ca15ec8 308 ld_bind_now = _getenv_ld("LD_BIND_NOW");
984263bc 309 if (trust) {
8ca15ec8
MD
310 ld_debug = _getenv_ld("LD_DEBUG");
311 ld_library_path = _getenv_ld("LD_LIBRARY_PATH");
312 ld_preload = (char *)_getenv_ld("LD_PRELOAD");
984263bc 313 }
8ca15ec8 314 ld_tracing = _getenv_ld("LD_TRACE_LOADED_OBJECTS");
984263bc
MD
315
316 if (ld_debug != NULL && *ld_debug != '\0')
317 debug = 1;
318 dbg("%s is initialized, base address = %p", __progname,
319 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
320 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
321 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
322
33a8b578
MD
323 /*
324 * If we are resident we can skip work that we have already done.
325 * Note that the stack is reset and there is no Elf_Auxinfo
326 * when running from a resident image, and the static globals setup
327 * between here and resident_skip will have already been setup.
328 */
8ca15ec8 329 if (ld_resident)
33a8b578 330 goto resident_skip1;
33a8b578 331
984263bc
MD
332 /*
333 * Load the main program, or process its program header if it is
334 * already loaded.
335 */
336 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
337 int fd = aux_info[AT_EXECFD]->a_un.a_val;
338 dbg("loading main program");
339 obj_main = map_object(fd, argv0, NULL);
340 close(fd);
341 if (obj_main == NULL)
342 die();
343 } else { /* Main program already loaded. */
344 const Elf_Phdr *phdr;
345 int phnum;
346 caddr_t entry;
347
348 dbg("processing main program's program header");
349 assert(aux_info[AT_PHDR] != NULL);
350 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
351 assert(aux_info[AT_PHNUM] != NULL);
352 phnum = aux_info[AT_PHNUM]->a_un.a_val;
353 assert(aux_info[AT_PHENT] != NULL);
354 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
355 assert(aux_info[AT_ENTRY] != NULL);
356 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
357 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
358 die();
359 }
360
361 obj_main->path = xstrdup(argv0);
362 obj_main->mainprog = true;
363
364 /*
365 * Get the actual dynamic linker pathname from the executable if
366 * possible. (It should always be possible.) That ensures that
367 * gdb will find the right dynamic linker even if a non-standard
368 * one is being used.
369 */
370 if (obj_main->interp != NULL &&
371 strcmp(obj_main->interp, obj_rtld.path) != 0) {
372 free(obj_rtld.path);
373 obj_rtld.path = xstrdup(obj_main->interp);
374 }
375
376 digest_dynamic(obj_main);
377
378 linkmap_add(obj_main);
379 linkmap_add(&obj_rtld);
380
381 /* Link the main program into the list of objects. */
382 *obj_tail = obj_main;
383 obj_tail = &obj_main->next;
384 obj_count++;
385 obj_main->refcount++;
386 /* Make sure we don't call the main program's init and fini functions. */
387 obj_main->init = obj_main->fini = NULL;
388
389 /* Initialize a fake symbol for resolving undefined weak references. */
390 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
391 sym_zero.st_shndx = SHN_ABS;
392
393 dbg("loading LD_PRELOAD libraries");
394 if (load_preload_objects() == -1)
395 die();
396 preload_tail = obj_tail;
397
398 dbg("loading needed objects");
399 if (load_needed_objects(obj_main) == -1)
400 die();
401
402 /* Make a list of all objects loaded at startup. */
403 for (obj = obj_list; obj != NULL; obj = obj->next)
404 objlist_push_tail(&list_main, obj);
405
33a8b578
MD
406resident_skip1:
407
984263bc
MD
408 if (ld_tracing) { /* We're done */
409 trace_loaded_objects(obj_main);
410 exit(0);
411 }
412
33a8b578
MD
413 if (ld_resident) /* XXX clean this up! */
414 goto resident_skip2;
415
6192271e
MD
416 if (relocate_objects(obj_main,
417 ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
418 die();
984263bc 419
6192271e
MD
420 dbg("doing copy relocations");
421 if (do_copy_relocations(obj_main) == -1)
422 die();
1c76efe5 423
33a8b578
MD
424resident_skip2:
425
8ca15ec8 426 if (_getenv_ld("LD_RESIDENT_UNREGISTER_NOW")) {
33a8b578
MD
427 if (exec_sys_unregister(-1) < 0) {
428 dbg("exec_sys_unregister failed %d\n", errno);
429 exit(errno);
430 }
431 dbg("exec_sys_unregister success\n");
432 exit(0);
433 }
984263bc
MD
434
435 dbg("initializing key program variables");
436 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
437 set_program_var("environ", env);
438
8ca15ec8
MD
439 if (_getenv_ld("LD_RESIDENT_REGISTER_NOW")) {
440 extern void resident_start(void);
441 ld_resident = 1;
442 if (exec_sys_register(resident_start) < 0) {
443 dbg("exec_sys_register failed %d\n", errno);
444 exit(errno);
445 }
446 dbg("exec_sys_register success\n");
447 exit(0);
448 }
449
984263bc
MD
450 dbg("initializing thread locks");
451 lockdflt_init(&lockinfo);
452 lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
453
454 /* Make a list of init functions to call. */
455 objlist_init(&initlist);
456 initlist_add_objects(obj_list, preload_tail, &initlist);
457
458 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
459
460 objlist_call_init(&initlist);
461 wlock_acquire();
462 objlist_clear(&initlist);
463 wlock_release();
464
8ca15ec8
MD
465
466
984263bc
MD
467 dbg("transferring control to program entry point = %p", obj_main->entry);
468
469 /* Return the exit procedure and the program entry point. */
470 *exit_proc = rtld_exit;
471 *objp = obj_main;
472 return (func_ptr_type) obj_main->entry;
473}
474
475Elf_Addr
476_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
477{
478 const Elf_Rel *rel;
479 const Elf_Sym *def;
480 const Obj_Entry *defobj;
481 Elf_Addr *where;
482 Elf_Addr target;
483
484 rlock_acquire();
485 if (obj->pltrel)
486 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
487 else
488 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
489
490 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
491 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
492 if (def == NULL)
493 die();
494
495 target = (Elf_Addr)(defobj->relocbase + def->st_value);
496
497 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
498 defobj->strtab + def->st_name, basename(obj->path),
499 (void *)target, basename(defobj->path));
500
501 reloc_jmpslot(where, target);
502 rlock_release();
503 return target;
504}
505
506/*
507 * Error reporting function. Use it like printf. If formats the message
508 * into a buffer, and sets things up so that the next call to dlerror()
509 * will return the message.
510 */
511void
512_rtld_error(const char *fmt, ...)
513{
514 static char buf[512];
515 va_list ap;
516
517 va_start(ap, fmt);
518 vsnprintf(buf, sizeof buf, fmt, ap);
519 error_message = buf;
520 va_end(ap);
521}
522
523/*
524 * Return a dynamically-allocated copy of the current error message, if any.
525 */
526static char *
527errmsg_save(void)
528{
529 return error_message == NULL ? NULL : xstrdup(error_message);
530}
531
532/*
533 * Restore the current error message from a copy which was previously saved
534 * by errmsg_save(). The copy is freed.
535 */
536static void
537errmsg_restore(char *saved_msg)
538{
539 if (saved_msg == NULL)
540 error_message = NULL;
541 else {
542 _rtld_error("%s", saved_msg);
543 free(saved_msg);
544 }
545}
546
1c76efe5 547const char *
984263bc
MD
548basename(const char *name)
549{
550 const char *p = strrchr(name, '/');
551 return p != NULL ? p + 1 : name;
552}
553
554static void
555die(void)
556{
557 const char *msg = dlerror();
558
559 if (msg == NULL)
560 msg = "Fatal error";
561 errx(1, "%s", msg);
562}
563
564/*
565 * Process a shared object's DYNAMIC section, and save the important
566 * information in its Obj_Entry structure.
567 */
568static void
569digest_dynamic(Obj_Entry *obj)
570{
571 const Elf_Dyn *dynp;
572 Needed_Entry **needed_tail = &obj->needed;
573 const Elf_Dyn *dyn_rpath = NULL;
574 int plttype = DT_REL;
575
576 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
577 switch (dynp->d_tag) {
578
579 case DT_REL:
580 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
581 break;
582
583 case DT_RELSZ:
584 obj->relsize = dynp->d_un.d_val;
585 break;
586
587 case DT_RELENT:
588 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
589 break;
590
591 case DT_JMPREL:
592 obj->pltrel = (const Elf_Rel *)
593 (obj->relocbase + dynp->d_un.d_ptr);
594 break;
595
596 case DT_PLTRELSZ:
597 obj->pltrelsize = dynp->d_un.d_val;
598 break;
599
600 case DT_RELA:
601 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
602 break;
603
604 case DT_RELASZ:
605 obj->relasize = dynp->d_un.d_val;
606 break;
607
608 case DT_RELAENT:
609 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
610 break;
611
612 case DT_PLTREL:
613 plttype = dynp->d_un.d_val;
614 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
615 break;
616
617 case DT_SYMTAB:
618 obj->symtab = (const Elf_Sym *)
619 (obj->relocbase + dynp->d_un.d_ptr);
620 break;
621
622 case DT_SYMENT:
623 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
624 break;
625
626 case DT_STRTAB:
627 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
628 break;
629
630 case DT_STRSZ:
631 obj->strsize = dynp->d_un.d_val;
632 break;
633
634 case DT_HASH:
635 {
636 const Elf_Addr *hashtab = (const Elf_Addr *)
637 (obj->relocbase + dynp->d_un.d_ptr);
638 obj->nbuckets = hashtab[0];
639 obj->nchains = hashtab[1];
640 obj->buckets = hashtab + 2;
641 obj->chains = obj->buckets + obj->nbuckets;
642 }
643 break;
644
645 case DT_NEEDED:
646 if (!obj->rtld) {
647 Needed_Entry *nep = NEW(Needed_Entry);
648 nep->name = dynp->d_un.d_val;
649 nep->obj = NULL;
650 nep->next = NULL;
651
652 *needed_tail = nep;
653 needed_tail = &nep->next;
654 }
655 break;
656
657 case DT_PLTGOT:
658 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
659 break;
660
661 case DT_TEXTREL:
662 obj->textrel = true;
663 break;
664
665 case DT_SYMBOLIC:
666 obj->symbolic = true;
667 break;
668
669 case DT_RPATH:
670 /*
671 * We have to wait until later to process this, because we
672 * might not have gotten the address of the string table yet.
673 */
674 dyn_rpath = dynp;
675 break;
676
677 case DT_SONAME:
678 /* Not used by the dynamic linker. */
679 break;
680
681 case DT_INIT:
682 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
683 break;
684
685 case DT_FINI:
686 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
687 break;
688
689 case DT_DEBUG:
690 /* XXX - not implemented yet */
691 dbg("Filling in DT_DEBUG entry");
692 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
693 break;
694
695 default:
696 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
697 break;
698 }
699 }
700
701 obj->traced = false;
702
703 if (plttype == DT_RELA) {
704 obj->pltrela = (const Elf_Rela *) obj->pltrel;
705 obj->pltrel = NULL;
706 obj->pltrelasize = obj->pltrelsize;
707 obj->pltrelsize = 0;
708 }
709
710 if (dyn_rpath != NULL)
711 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
712}
713
714/*
715 * Process a shared object's program header. This is used only for the
716 * main program, when the kernel has already loaded the main program
717 * into memory before calling the dynamic linker. It creates and
718 * returns an Obj_Entry structure.
719 */
720static Obj_Entry *
721digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
722{
723 Obj_Entry *obj;
724 const Elf_Phdr *phlimit = phdr + phnum;
725 const Elf_Phdr *ph;
726 int nsegs = 0;
727
728 obj = obj_new();
729 for (ph = phdr; ph < phlimit; ph++) {
730 switch (ph->p_type) {
731
732 case PT_PHDR:
733 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
734 _rtld_error("%s: invalid PT_PHDR", path);
735 return NULL;
736 }
737 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
738 obj->phsize = ph->p_memsz;
739 break;
740
741 case PT_INTERP:
742 obj->interp = (const char *) ph->p_vaddr;
743 break;
744
745 case PT_LOAD:
746 if (nsegs == 0) { /* First load segment */
747 obj->vaddrbase = trunc_page(ph->p_vaddr);
748 obj->mapbase = (caddr_t) obj->vaddrbase;
749 obj->relocbase = obj->mapbase - obj->vaddrbase;
750 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
751 obj->vaddrbase;
752 } else { /* Last load segment */
753 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
754 obj->vaddrbase;
755 }
756 nsegs++;
757 break;
758
759 case PT_DYNAMIC:
760 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
761 break;
762 }
763 }
764 if (nsegs < 1) {
765 _rtld_error("%s: too few PT_LOAD segments", path);
766 return NULL;
767 }
768
769 obj->entry = entry;
770 return obj;
771}
772
773static Obj_Entry *
774dlcheck(void *handle)
775{
776 Obj_Entry *obj;
777
778 for (obj = obj_list; obj != NULL; obj = obj->next)
779 if (obj == (Obj_Entry *) handle)
780 break;
781
782 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
783 _rtld_error("Invalid shared object handle %p", handle);
784 return NULL;
785 }
786 return obj;
787}
788
789/*
790 * If the given object is already in the donelist, return true. Otherwise
791 * add the object to the list and return false.
792 */
793static bool
794donelist_check(DoneList *dlp, const Obj_Entry *obj)
795{
796 unsigned int i;
797
798 for (i = 0; i < dlp->num_used; i++)
799 if (dlp->objs[i] == obj)
800 return true;
801 /*
802 * Our donelist allocation should always be sufficient. But if
803 * our threads locking isn't working properly, more shared objects
804 * could have been loaded since we allocated the list. That should
805 * never happen, but we'll handle it properly just in case it does.
806 */
807 if (dlp->num_used < dlp->num_alloc)
808 dlp->objs[dlp->num_used++] = obj;
809 return false;
810}
811
812/*
813 * Hash function for symbol table lookup. Don't even think about changing
814 * this. It is specified by the System V ABI.
815 */
816unsigned long
817elf_hash(const char *name)
818{
819 const unsigned char *p = (const unsigned char *) name;
820 unsigned long h = 0;
821 unsigned long g;
822
823 while (*p != '\0') {
824 h = (h << 4) + *p++;
825 if ((g = h & 0xf0000000) != 0)
826 h ^= g >> 24;
827 h &= ~g;
828 }
829 return h;
830}
831
832/*
833 * Find the library with the given name, and return its full pathname.
834 * The returned string is dynamically allocated. Generates an error
835 * message and returns NULL if the library cannot be found.
836 *
837 * If the second argument is non-NULL, then it refers to an already-
838 * loaded shared object, whose library search path will be searched.
839 *
840 * The search order is:
984263bc 841 * LD_LIBRARY_PATH
4e390e27 842 * rpath in the referencing file
984263bc
MD
843 * ldconfig hints
844 * /usr/lib
845 */
846static char *
847find_library(const char *name, const Obj_Entry *refobj)
848{
849 char *pathname;
850
851 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
852 if (name[0] != '/' && !trust) {
853 _rtld_error("Absolute pathname required for shared object \"%s\"",
854 name);
855 return NULL;
856 }
857 return xstrdup(name);
858 }
859
860 dbg(" Searching for \"%s\"", name);
861
862 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
863 (refobj != NULL &&
864 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
865 (pathname = search_library_path(name, gethints())) != NULL ||
866 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
867 return pathname;
868
869 _rtld_error("Shared object \"%s\" not found", name);
870 return NULL;
871}
872
873/*
874 * Given a symbol number in a referencing object, find the corresponding
875 * definition of the symbol. Returns a pointer to the symbol, or NULL if
876 * no definition was found. Returns a pointer to the Obj_Entry of the
877 * defining object via the reference parameter DEFOBJ_OUT.
878 */
879const Elf_Sym *
880find_symdef(unsigned long symnum, const Obj_Entry *refobj,
881 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
882{
883 const Elf_Sym *ref;
884 const Elf_Sym *def;
885 const Obj_Entry *defobj;
886 const char *name;
887 unsigned long hash;
888
889 /*
890 * If we have already found this symbol, get the information from
891 * the cache.
892 */
893 if (symnum >= refobj->nchains)
894 return NULL; /* Bad object */
895 if (cache != NULL && cache[symnum].sym != NULL) {
896 *defobj_out = cache[symnum].obj;
897 return cache[symnum].sym;
898 }
899
900 ref = refobj->symtab + symnum;
901 name = refobj->strtab + ref->st_name;
902 hash = elf_hash(name);
903 defobj = NULL;
904
905 def = symlook_default(name, hash, refobj, &defobj, in_plt);
906
907 /*
908 * If we found no definition and the reference is weak, treat the
909 * symbol as having the value zero.
910 */
911 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
912 def = &sym_zero;
913 defobj = obj_main;
914 }
915
916 if (def != NULL) {
917 *defobj_out = defobj;
918 /* Record the information in the cache to avoid subsequent lookups. */
919 if (cache != NULL) {
920 cache[symnum].sym = def;
921 cache[symnum].obj = defobj;
922 }
923 } else
924 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
925 return def;
926}
927
928/*
929 * Return the search path from the ldconfig hints file, reading it if
930 * necessary. Returns NULL if there are problems with the hints file,
931 * or if the search path there is empty.
932 */
933static const char *
934gethints(void)
935{
936 static char *hints;
937
938 if (hints == NULL) {
939 int fd;
940 struct elfhints_hdr hdr;
941 char *p;
942
943 /* Keep from trying again in case the hints file is bad. */
944 hints = "";
945
946 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
947 return NULL;
948 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
949 hdr.magic != ELFHINTS_MAGIC ||
950 hdr.version != 1) {
951 close(fd);
952 return NULL;
953 }
954 p = xmalloc(hdr.dirlistlen + 1);
955 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
956 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
957 free(p);
958 close(fd);
959 return NULL;
960 }
961 hints = p;
962 close(fd);
963 }
964 return hints[0] != '\0' ? hints : NULL;
965}
966
967static void
968init_dag(Obj_Entry *root)
969{
970 DoneList donelist;
971
972 donelist_init(&donelist);
973 init_dag1(root, root, &donelist);
974}
975
976static void
977init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
978{
979 const Needed_Entry *needed;
980
981 if (donelist_check(dlp, obj))
982 return;
983 objlist_push_tail(&obj->dldags, root);
984 objlist_push_tail(&root->dagmembers, obj);
985 for (needed = obj->needed; needed != NULL; needed = needed->next)
986 if (needed->obj != NULL)
987 init_dag1(root, needed->obj, dlp);
988}
989
990/*
991 * Initialize the dynamic linker. The argument is the address at which
992 * the dynamic linker has been mapped into memory. The primary task of
993 * this function is to relocate the dynamic linker.
994 */
995static void
996init_rtld(caddr_t mapbase)
997{
998 /*
999 * Conjure up an Obj_Entry structure for the dynamic linker.
1000 *
1001 * The "path" member is supposed to be dynamically-allocated, but we
1002 * aren't yet initialized sufficiently to do that. Below we will
1003 * replace the static version with a dynamically-allocated copy.
1004 */
1005 obj_rtld.path = PATH_RTLD;
1006 obj_rtld.rtld = true;
1007 obj_rtld.mapbase = mapbase;
1008#ifdef PIC
1009 obj_rtld.relocbase = mapbase;
1010#endif
1011 if (&_DYNAMIC != 0) {
1012 obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1013 digest_dynamic(&obj_rtld);
1014 assert(obj_rtld.needed == NULL);
1015 assert(!obj_rtld.textrel);
1016
1017 /*
1018 * Temporarily put the dynamic linker entry into the object list, so
1019 * that symbols can be found.
1020 */
1021 obj_list = &obj_rtld;
1022 obj_tail = &obj_rtld.next;
1023 obj_count = 1;
1024
1025 relocate_objects(&obj_rtld, true);
1026 }
1027
1028 /* Make the object list empty again. */
1029 obj_list = NULL;
1030 obj_tail = &obj_list;
1031 obj_count = 0;
1032
1033 /* Replace the path with a dynamically allocated copy. */
1034 obj_rtld.path = xstrdup(obj_rtld.path);
1035
1036 r_debug.r_brk = r_debug_state;
1037 r_debug.r_state = RT_CONSISTENT;
1038}
1039
1040/*
1041 * Add the init functions from a needed object list (and its recursive
1042 * needed objects) to "list". This is not used directly; it is a helper
1043 * function for initlist_add_objects(). The write lock must be held
1044 * when this function is called.
1045 */
1046static void
1047initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1048{
1049 /* Recursively process the successor needed objects. */
1050 if (needed->next != NULL)
1051 initlist_add_neededs(needed->next, list);
1052
1053 /* Process the current needed object. */
1054 if (needed->obj != NULL)
1055 initlist_add_objects(needed->obj, &needed->obj->next, list);
1056}
1057
1058/*
1059 * Scan all of the DAGs rooted in the range of objects from "obj" to
1060 * "tail" and add their init functions to "list". This recurses over
1061 * the DAGs and ensure the proper init ordering such that each object's
1062 * needed libraries are initialized before the object itself. At the
1063 * same time, this function adds the objects to the global finalization
1064 * list "list_fini" in the opposite order. The write lock must be
1065 * held when this function is called.
1066 */
1067static void
1068initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1069{
1070 if (obj->init_done)
1071 return;
1072 obj->init_done = true;
1073
1074 /* Recursively process the successor objects. */
1075 if (&obj->next != tail)
1076 initlist_add_objects(obj->next, tail, list);
1077
1078 /* Recursively process the needed objects. */
1079 if (obj->needed != NULL)
1080 initlist_add_neededs(obj->needed, list);
1081
1082 /* Add the object to the init list. */
1083 if (obj->init != NULL)
1084 objlist_push_tail(list, obj);
1085
1086 /* Add the object to the global fini list in the reverse order. */
1087 if (obj->fini != NULL)
1088 objlist_push_head(&list_fini, obj);
1089}
1090
1091static bool
1092is_exported(const Elf_Sym *def)
1093{
1094 func_ptr_type value;
1095 const func_ptr_type *p;
1096
1097 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1098 for (p = exports; *p != NULL; p++)
1099 if (*p == value)
1100 return true;
1101 return false;
1102}
1103
1104/*
1105 * Given a shared object, traverse its list of needed objects, and load
1106 * each of them. Returns 0 on success. Generates an error message and
1107 * returns -1 on failure.
1108 */
1109static int
1110load_needed_objects(Obj_Entry *first)
1111{
1112 Obj_Entry *obj;
1113
1114 for (obj = first; obj != NULL; obj = obj->next) {
1115 Needed_Entry *needed;
1116
1117 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1118 const char *name = obj->strtab + needed->name;
1119 char *path = find_library(name, obj);
1120
1121 needed->obj = NULL;
1122 if (path == NULL && !ld_tracing)
1123 return -1;
1124
1125 if (path) {
1126 needed->obj = load_object(path);
1127 if (needed->obj == NULL && !ld_tracing)
1128 return -1; /* XXX - cleanup */
1129 }
1130 }
1131 }
1132
1133 return 0;
1134}
1135
1136static int
1137load_preload_objects(void)
1138{
1139 char *p = ld_preload;
1140 static const char delim[] = " \t:;";
1141
1142 if (p == NULL)
1143 return NULL;
1144
1145 p += strspn(p, delim);
1146 while (*p != '\0') {
1147 size_t len = strcspn(p, delim);
1148 char *path;
1149 char savech;
1150
1151 savech = p[len];
1152 p[len] = '\0';
1153 if ((path = find_library(p, NULL)) == NULL)
1154 return -1;
1155 if (load_object(path) == NULL)
1156 return -1; /* XXX - cleanup */
1157 p[len] = savech;
1158 p += len;
1159 p += strspn(p, delim);
1160 }
1161 return 0;
1162}
1163
1164/*
1165 * Load a shared object into memory, if it is not already loaded. The
1166 * argument must be a string allocated on the heap. This function assumes
1167 * responsibility for freeing it when necessary.
1168 *
1169 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1170 * on failure.
1171 */
1172static Obj_Entry *
1173load_object(char *path)
1174{
1175 Obj_Entry *obj;
1176 int fd = -1;
1177 struct stat sb;
1178
1179 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1180 if (strcmp(obj->path, path) == 0)
1181 break;
1182
1183 /*
1184 * If we didn't find a match by pathname, open the file and check
1185 * again by device and inode. This avoids false mismatches caused
1186 * by multiple links or ".." in pathnames.
1187 *
1188 * To avoid a race, we open the file and use fstat() rather than
1189 * using stat().
1190 */
1191 if (obj == NULL) {
1192 if ((fd = open(path, O_RDONLY)) == -1) {
1193 _rtld_error("Cannot open \"%s\"", path);
1194 return NULL;
1195 }
1196 if (fstat(fd, &sb) == -1) {
1197 _rtld_error("Cannot fstat \"%s\"", path);
1198 close(fd);
1199 return NULL;
1200 }
1201 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1202 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
1203 close(fd);
1204 break;
1205 }
1206 }
1207 }
1208
1209 if (obj == NULL) { /* First use of this object, so we must map it in */
1210 dbg("loading \"%s\"", path);
1211 obj = map_object(fd, path, &sb);
1212 close(fd);
1213 if (obj == NULL) {
1214 free(path);
1215 return NULL;
1216 }
1217
1218 obj->path = path;
1219 digest_dynamic(obj);
1220
1221 *obj_tail = obj;
1222 obj_tail = &obj->next;
1223 obj_count++;
1224 linkmap_add(obj); /* for GDB & dlinfo() */
1225
1226 dbg(" %p .. %p: %s", obj->mapbase,
1227 obj->mapbase + obj->mapsize - 1, obj->path);
1228 if (obj->textrel)
1229 dbg(" WARNING: %s has impure text", obj->path);
1230 } else
1231 free(path);
1232
1233 obj->refcount++;
1234 return obj;
1235}
1236
1237/*
1238 * Check for locking violations and die if one is found.
1239 */
1240static void
1241lock_check(void)
1242{
1243 int rcount, wcount;
1244
1245 rcount = lockinfo.rcount;
1246 wcount = lockinfo.wcount;
1247 assert(rcount >= 0);
1248 assert(wcount >= 0);
1249 if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1250 _rtld_error("Application locking error: %d readers and %d writers"
1251 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1252 rcount, wcount);
1253 die();
1254 }
1255}
1256
1257static Obj_Entry *
1258obj_from_addr(const void *addr)
1259{
1260 unsigned long endhash;
1261 Obj_Entry *obj;
1262
1263 endhash = elf_hash(END_SYM);
1264 for (obj = obj_list; obj != NULL; obj = obj->next) {
1265 const Elf_Sym *endsym;
1266
1267 if (addr < (void *) obj->mapbase)
1268 continue;
1269 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL)
1270 continue; /* No "end" symbol?! */
1271 if (addr < (void *) (obj->relocbase + endsym->st_value))
1272 return obj;
1273 }
1274 return NULL;
1275}
1276
1277/*
1278 * Call the finalization functions for each of the objects in "list"
1279 * which are unreferenced. All of the objects are expected to have
1280 * non-NULL fini functions.
1281 */
1282static void
1283objlist_call_fini(Objlist *list)
1284{
1285 Objlist_Entry *elm;
1286 char *saved_msg;
1287
1288 /*
1289 * Preserve the current error message since a fini function might
1290 * call into the dynamic linker and overwrite it.
1291 */
1292 saved_msg = errmsg_save();
1293 STAILQ_FOREACH(elm, list, link) {
1294 if (elm->obj->refcount == 0) {
1295 dbg("calling fini function for %s", elm->obj->path);
1296 (*elm->obj->fini)();
1297 }
1298 }
1299 errmsg_restore(saved_msg);
1300}
1301
1302/*
1303 * Call the initialization functions for each of the objects in
1304 * "list". All of the objects are expected to have non-NULL init
1305 * functions.
1306 */
1307static void
1308objlist_call_init(Objlist *list)
1309{
1310 Objlist_Entry *elm;
1311 char *saved_msg;
1312
1313 /*
1314 * Preserve the current error message since an init function might
1315 * call into the dynamic linker and overwrite it.
1316 */
1317 saved_msg = errmsg_save();
1318 STAILQ_FOREACH(elm, list, link) {
1319 dbg("calling init function for %s", elm->obj->path);
1320 (*elm->obj->init)();
1321 }
1322 errmsg_restore(saved_msg);
1323}
1324
1325static void
1326objlist_clear(Objlist *list)
1327{
1328 Objlist_Entry *elm;
1329
1330 while (!STAILQ_EMPTY(list)) {
1331 elm = STAILQ_FIRST(list);
1332 STAILQ_REMOVE_HEAD(list, link);
1333 free(elm);
1334 }
1335}
1336
1337static Objlist_Entry *
1338objlist_find(Objlist *list, const Obj_Entry *obj)
1339{
1340 Objlist_Entry *elm;
1341
1342 STAILQ_FOREACH(elm, list, link)
1343 if (elm->obj == obj)
1344 return elm;
1345 return NULL;
1346}
1347
1348static void
1349objlist_init(Objlist *list)
1350{
1351 STAILQ_INIT(list);
1352}
1353
1354static void
1355objlist_push_head(Objlist *list, Obj_Entry *obj)
1356{
1357 Objlist_Entry *elm;
1358
1359 elm = NEW(Objlist_Entry);
1360 elm->obj = obj;
1361 STAILQ_INSERT_HEAD(list, elm, link);
1362}
1363
1364static void
1365objlist_push_tail(Objlist *list, Obj_Entry *obj)
1366{
1367 Objlist_Entry *elm;
1368
1369 elm = NEW(Objlist_Entry);
1370 elm->obj = obj;
1371 STAILQ_INSERT_TAIL(list, elm, link);
1372}
1373
1374static void
1375objlist_remove(Objlist *list, Obj_Entry *obj)
1376{
1377 Objlist_Entry *elm;
1378
1379 if ((elm = objlist_find(list, obj)) != NULL) {
1380 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1381 free(elm);
1382 }
1383}
1384
1385/*
1386 * Remove all of the unreferenced objects from "list".
1387 */
1388static void
1389objlist_remove_unref(Objlist *list)
1390{
1391 Objlist newlist;
1392 Objlist_Entry *elm;
1393
1394 STAILQ_INIT(&newlist);
1395 while (!STAILQ_EMPTY(list)) {
1396 elm = STAILQ_FIRST(list);
1397 STAILQ_REMOVE_HEAD(list, link);
1398 if (elm->obj->refcount == 0)
1399 free(elm);
1400 else
1401 STAILQ_INSERT_TAIL(&newlist, elm, link);
1402 }
1403 *list = newlist;
1404}
1405
1406/*
1407 * Relocate newly-loaded shared objects. The argument is a pointer to
1408 * the Obj_Entry for the first such object. All objects from the first
1409 * to the end of the list of objects are relocated. Returns 0 on success,
1410 * or -1 on failure.
1411 */
1412static int
1413relocate_objects(Obj_Entry *first, bool bind_now)
1414{
1415 Obj_Entry *obj;
1416
1417 for (obj = first; obj != NULL; obj = obj->next) {
1418 if (obj != &obj_rtld)
1419 dbg("relocating \"%s\"", obj->path);
1420 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1421 obj->symtab == NULL || obj->strtab == NULL) {
1422 _rtld_error("%s: Shared object has no run-time symbol table",
1423 obj->path);
1424 return -1;
1425 }
1426
1427 if (obj->textrel) {
1428 /* There are relocations to the write-protected text segment. */
1429 if (mprotect(obj->mapbase, obj->textsize,
1430 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1431 _rtld_error("%s: Cannot write-enable text segment: %s",
1432 obj->path, strerror(errno));
1433 return -1;
1434 }
1435 }
1436
1437 /* Process the non-PLT relocations. */
1438 if (reloc_non_plt(obj, &obj_rtld))
1439 return -1;
1440
4b89341e
MD
1441 /*
1442 * Reprotect the text segment. Make sure it is included in the
1443 * core dump since we modified it. This unfortunately causes the
1444 * entire text segment to core-out but we don't have much of a
1445 * choice. We could try to only reenable core dumps on pages
1446 * in which relocations occured but that is likely most of the text
1447 * pages anyway, and even that would not work because the rest of
1448 * the text pages would wind up as a read-only OBJT_DEFAULT object
1449 * (created due to our modifications) backed by the original OBJT_VNODE
1450 * object, and the ELF coredump code is currently only able to dump
1451 * vnode records for pure vnode-backed mappings, not vnode backings
1452 * to memory objects.
1453 */
1454 if (obj->textrel) {
1455 madvise(obj->mapbase, obj->textsize, MADV_CORE);
984263bc
MD
1456 if (mprotect(obj->mapbase, obj->textsize,
1457 PROT_READ|PROT_EXEC) == -1) {
1458 _rtld_error("%s: Cannot write-protect text segment: %s",
1459 obj->path, strerror(errno));
1460 return -1;
1461 }
1462 }
1463
1464 /* Process the PLT relocations. */
1465 if (reloc_plt(obj) == -1)
1466 return -1;
1467 /* Relocate the jump slots if we are doing immediate binding. */
1468 if (bind_now)
1469 if (reloc_jmpslots(obj) == -1)
1470 return -1;
1471
1472
1473 /*
1474 * Set up the magic number and version in the Obj_Entry. These
1475 * were checked in the crt1.o from the original ElfKit, so we
1476 * set them for backward compatibility.
1477 */
1478 obj->magic = RTLD_MAGIC;
1479 obj->version = RTLD_VERSION;
1480
1481 /* Set the special PLT or GOT entries. */
1482 init_pltgot(obj);
1483 }
1484
1485 return 0;
1486}
1487
1488/*
1489 * Cleanup procedure. It will be called (by the atexit mechanism) just
1490 * before the process exits.
1491 */
1492static void
1493rtld_exit(void)
1494{
1495 Obj_Entry *obj;
1496
1497 dbg("rtld_exit()");
1498 /* Clear all the reference counts so the fini functions will be called. */
1499 for (obj = obj_list; obj != NULL; obj = obj->next)
1500 obj->refcount = 0;
1501 objlist_call_fini(&list_fini);
1502 /* No need to remove the items from the list, since we are exiting. */
1503}
1504
1505static void *
1506path_enumerate(const char *path, path_enum_proc callback, void *arg)
1507{
1508 if (path == NULL)
1509 return (NULL);
1510
1511 path += strspn(path, ":;");
1512 while (*path != '\0') {
1513 size_t len;
1514 char *res;
1515
1516 len = strcspn(path, ":;");
1517 res = callback(path, len, arg);
1518
1519 if (res != NULL)
1520 return (res);
1521
1522 path += len;
1523 path += strspn(path, ":;");
1524 }
1525
1526 return (NULL);
1527}
1528
1529struct try_library_args {
1530 const char *name;
1531 size_t namelen;
1532 char *buffer;
1533 size_t buflen;
1534};
1535
1536static void *
1537try_library_path(const char *dir, size_t dirlen, void *param)
1538{
1539 struct try_library_args *arg;
1540
1541 arg = param;
1542 if (*dir == '/' || trust) {
1543 char *pathname;
1544
1545 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1546 return (NULL);
1547
1548 pathname = arg->buffer;
1549 strncpy(pathname, dir, dirlen);
1550 pathname[dirlen] = '/';
1551 strcpy(pathname + dirlen + 1, arg->name);
1552
1553 dbg(" Trying \"%s\"", pathname);
1554 if (access(pathname, F_OK) == 0) { /* We found it */
1555 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1556 strcpy(pathname, arg->buffer);
1557 return (pathname);
1558 }
1559 }
1560 return (NULL);
1561}
1562
1563static char *
1564search_library_path(const char *name, const char *path)
1565{
1566 char *p;
1567 struct try_library_args arg;
1568
1569 if (path == NULL)
1570 return NULL;
1571
1572 arg.name = name;
1573 arg.namelen = strlen(name);
1574 arg.buffer = xmalloc(PATH_MAX);
1575 arg.buflen = PATH_MAX;
1576
1577 p = path_enumerate(path, try_library_path, &arg);
1578
1579 free(arg.buffer);
1580
1581 return (p);
1582}
1583
1584int
1585dlclose(void *handle)
1586{
1587 Obj_Entry *root;
1588
1589 wlock_acquire();
1590 root = dlcheck(handle);
1591 if (root == NULL) {
1592 wlock_release();
1593 return -1;
1594 }
1595
1596 /* Unreference the object and its dependencies. */
1597 root->dl_refcount--;
1598 unref_dag(root);
1599
1600 if (root->refcount == 0) {
1601 /*
1602 * The object is no longer referenced, so we must unload it.
1603 * First, call the fini functions with no locks held.
1604 */
1605 wlock_release();
1606 objlist_call_fini(&list_fini);
1607 wlock_acquire();
1608 objlist_remove_unref(&list_fini);
1609
1610 /* Finish cleaning up the newly-unreferenced objects. */
1611 GDB_STATE(RT_DELETE,&root->linkmap);
1612 unload_object(root);
1613 GDB_STATE(RT_CONSISTENT,NULL);
1614 }
1615 wlock_release();
1616 return 0;
1617}
1618
1619const char *
1620dlerror(void)
1621{
1622 char *msg = error_message;
1623 error_message = NULL;
1624 return msg;
1625}
1626
1627/*
1628 * This function is deprecated and has no effect.
1629 */
1630void
1631dllockinit(void *context,
1632 void *(*lock_create)(void *context),
1633 void (*rlock_acquire)(void *lock),
1634 void (*wlock_acquire)(void *lock),
1635 void (*lock_release)(void *lock),
1636 void (*lock_destroy)(void *lock),
1637 void (*context_destroy)(void *context))
1638{
1639 static void *cur_context;
1640 static void (*cur_context_destroy)(void *);
1641
1642 /* Just destroy the context from the previous call, if necessary. */
1643 if (cur_context_destroy != NULL)
1644 cur_context_destroy(cur_context);
1645 cur_context = context;
1646 cur_context_destroy = context_destroy;
1647}
1648
1649void *
1650dlopen(const char *name, int mode)
1651{
1652 Obj_Entry **old_obj_tail;
1653 Obj_Entry *obj;
1654 Objlist initlist;
1655 int result;
1656
1657 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1658 if (ld_tracing != NULL)
1659 environ = (char **)*get_program_var_addr("environ");
1660
1661 objlist_init(&initlist);
1662
1663 wlock_acquire();
1664 GDB_STATE(RT_ADD,NULL);
1665
1666 old_obj_tail = obj_tail;
1667 obj = NULL;
1668 if (name == NULL) {
1669 obj = obj_main;
1670 obj->refcount++;
1671 } else {
1672 char *path = find_library(name, obj_main);
1673 if (path != NULL)
1674 obj = load_object(path);
1675 }
1676
1677 if (obj) {
1678 obj->dl_refcount++;
8ca15ec8 1679 if ((mode & RTLD_GLOBAL) && objlist_find(&list_global, obj) == NULL)
984263bc
MD
1680 objlist_push_tail(&list_global, obj);
1681 mode &= RTLD_MODEMASK;
1682 if (*old_obj_tail != NULL) { /* We loaded something new. */
1683 assert(*old_obj_tail == obj);
1684
1685 result = load_needed_objects(obj);
1686 if (result != -1 && ld_tracing)
1687 goto trace;
1688
1689 if (result == -1 ||
1690 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1691 obj->dl_refcount--;
1692 unref_dag(obj);
1693 if (obj->refcount == 0)
1694 unload_object(obj);
1695 obj = NULL;
1696 } else {
1697 /* Make list of init functions to call. */
1698 initlist_add_objects(obj, &obj->next, &initlist);
1699 }
1700 } else if (ld_tracing)
1701 goto trace;
1702 }
1703
1704 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1705
1706 /* Call the init functions with no locks held. */
1707 wlock_release();
1708 objlist_call_init(&initlist);
1709 wlock_acquire();
1710 objlist_clear(&initlist);
1711 wlock_release();
1712 return obj;
1713trace:
1714 trace_loaded_objects(obj);
1715 wlock_release();
1716 exit(0);
1717}
1718
1719void *
1720dlsym(void *handle, const char *name)
1721{
1722 const Obj_Entry *obj;
1723 unsigned long hash;
1724 const Elf_Sym *def;
1725 const Obj_Entry *defobj;
1726
1727 hash = elf_hash(name);
1728 def = NULL;
1729 defobj = NULL;
1730
1731 rlock_acquire();
1732 if (handle == NULL || handle == RTLD_NEXT ||
1733 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1734 void *retaddr;
1735
1736 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1737 if ((obj = obj_from_addr(retaddr)) == NULL) {
1738 _rtld_error("Cannot determine caller's shared object");
1739 rlock_release();
1740 return NULL;
1741 }
1742 if (handle == NULL) { /* Just the caller's shared object. */
1743 def = symlook_obj(name, hash, obj, true);
1744 defobj = obj;
1745 } else if (handle == RTLD_NEXT || /* Objects after caller's */
1746 handle == RTLD_SELF) { /* ... caller included */
1747 if (handle == RTLD_NEXT)
1748 obj = obj->next;
1749 for (; obj != NULL; obj = obj->next) {
1750 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1751 defobj = obj;
1752 break;
1753 }
1754 }
1755 } else {
1756 assert(handle == RTLD_DEFAULT);
1757 def = symlook_default(name, hash, obj, &defobj, true);
1758 }
1759 } else {
1760 if ((obj = dlcheck(handle)) == NULL) {
1761 rlock_release();
1762 return NULL;
1763 }
1764
1765 if (obj->mainprog) {
1766 DoneList donelist;
1767
1768 /* Search main program and all libraries loaded by it. */
1769 donelist_init(&donelist);
1770 def = symlook_list(name, hash, &list_main, &defobj, true,
1771 &donelist);
1772 } else {
1773 /*
1774 * XXX - This isn't correct. The search should include the whole
1775 * DAG rooted at the given object.
1776 */
1777 def = symlook_obj(name, hash, obj, true);
1778 defobj = obj;
1779 }
1780 }
1781
1782 if (def != NULL) {
1783 rlock_release();
1784 return defobj->relocbase + def->st_value;
1785 }
1786
1787 _rtld_error("Undefined symbol \"%s\"", name);
1788 rlock_release();
1789 return NULL;
1790}
1791
1792int
1793dladdr(const void *addr, Dl_info *info)
1794{
1795 const Obj_Entry *obj;
1796 const Elf_Sym *def;
1797 void *symbol_addr;
1798 unsigned long symoffset;
1799
1800 rlock_acquire();
1801 obj = obj_from_addr(addr);
1802 if (obj == NULL) {
1803 _rtld_error("No shared object contains address");
1804 rlock_release();
1805 return 0;
1806 }
1807 info->dli_fname = obj->path;
1808 info->dli_fbase = obj->mapbase;
1809 info->dli_saddr = (void *)0;
1810 info->dli_sname = NULL;
1811
1812 /*
1813 * Walk the symbol list looking for the symbol whose address is
1814 * closest to the address sent in.
1815 */
1816 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1817 def = obj->symtab + symoffset;
1818
1819 /*
1820 * For skip the symbol if st_shndx is either SHN_UNDEF or
1821 * SHN_COMMON.
1822 */
1823 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1824 continue;
1825
1826 /*
1827 * If the symbol is greater than the specified address, or if it
1828 * is further away from addr than the current nearest symbol,
1829 * then reject it.
1830 */
1831 symbol_addr = obj->relocbase + def->st_value;
1832 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1833 continue;
1834
1835 /* Update our idea of the nearest symbol. */
1836 info->dli_sname = obj->strtab + def->st_name;
1837 info->dli_saddr = symbol_addr;
1838
1839 /* Exact match? */
1840 if (info->dli_saddr == addr)
1841 break;
1842 }
1843 rlock_release();
1844 return 1;
1845}
1846
1847int
1848dlinfo(void *handle, int request, void *p)
1849{
1850 const Obj_Entry *obj;
1851 int error;
1852
1853 rlock_acquire();
1854
1855 if (handle == NULL || handle == RTLD_SELF) {
1856 void *retaddr;
1857
1858 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1859 if ((obj = obj_from_addr(retaddr)) == NULL)
1860 _rtld_error("Cannot determine caller's shared object");
1861 } else
1862 obj = dlcheck(handle);
1863
1864 if (obj == NULL) {
1865 rlock_release();
1866 return (-1);
1867 }
1868
1869 error = 0;
1870 switch (request) {
1871 case RTLD_DI_LINKMAP:
1872 *((struct link_map const **)p) = &obj->linkmap;
1873 break;
1874 case RTLD_DI_ORIGIN:
1875 error = rtld_dirname(obj->path, p);
1876 break;
1877
1878 case RTLD_DI_SERINFOSIZE:
1879 case RTLD_DI_SERINFO:
1880 error = do_search_info(obj, request, (struct dl_serinfo *)p);
1881 break;
1882
1883 default:
1884 _rtld_error("Invalid request %d passed to dlinfo()", request);
1885 error = -1;
1886 }
1887
1888 rlock_release();
1889
1890 return (error);
1891}
1892
1893struct fill_search_info_args {
1894 int request;
1895 unsigned int flags;
1896 Dl_serinfo *serinfo;
1897 Dl_serpath *serpath;
1898 char *strspace;
1899};
1900
1901static void *
1902fill_search_info(const char *dir, size_t dirlen, void *param)
1903{
1904 struct fill_search_info_args *arg;
1905
1906 arg = param;
1907
1908 if (arg->request == RTLD_DI_SERINFOSIZE) {
1909 arg->serinfo->dls_cnt ++;
1910 arg->serinfo->dls_size += dirlen + 1;
1911 } else {
1912 struct dl_serpath *s_entry;
1913
1914 s_entry = arg->serpath;
1915 s_entry->dls_name = arg->strspace;
1916 s_entry->dls_flags = arg->flags;
1917
1918 strncpy(arg->strspace, dir, dirlen);
1919 arg->strspace[dirlen] = '\0';
1920
1921 arg->strspace += dirlen + 1;
1922 arg->serpath++;
1923 }
1924
1925 return (NULL);
1926}
1927
1928static int
1929do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
1930{
1931 struct dl_serinfo _info;
1932 struct fill_search_info_args args;
1933
1934 args.request = RTLD_DI_SERINFOSIZE;
1935 args.serinfo = &_info;
1936
1937 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1938 _info.dls_cnt = 0;
1939
1940 path_enumerate(ld_library_path, fill_search_info, &args);
1941 path_enumerate(obj->rpath, fill_search_info, &args);
1942 path_enumerate(gethints(), fill_search_info, &args);
1943 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
1944
1945
1946 if (request == RTLD_DI_SERINFOSIZE) {
1947 info->dls_size = _info.dls_size;
1948 info->dls_cnt = _info.dls_cnt;
1949 return (0);
1950 }
1951
1952 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
1953 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
1954 return (-1);
1955 }
1956
1957 args.request = RTLD_DI_SERINFO;
1958 args.serinfo = info;
1959 args.serpath = &info->dls_serpath[0];
1960 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
1961
1962 args.flags = LA_SER_LIBPATH;
1963 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
1964 return (-1);
1965
1966 args.flags = LA_SER_RUNPATH;
1967 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
1968 return (-1);
1969
1970 args.flags = LA_SER_CONFIG;
1971 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
1972 return (-1);
1973
1974 args.flags = LA_SER_DEFAULT;
1975 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
1976 return (-1);
1977 return (0);
1978}
1979
1980static int
1981rtld_dirname(const char *path, char *bname)
1982{
1983 const char *endp;
1984
1985 /* Empty or NULL string gets treated as "." */
1986 if (path == NULL || *path == '\0') {
1987 bname[0] = '.';
1988 bname[1] = '\0';
1989 return (0);
1990 }
1991
1992 /* Strip trailing slashes */
1993 endp = path + strlen(path) - 1;
1994 while (endp > path && *endp == '/')
1995 endp--;
1996
1997 /* Find the start of the dir */
1998 while (endp > path && *endp != '/')
1999 endp--;
2000
2001 /* Either the dir is "/" or there are no slashes */
2002 if (endp == path) {
2003 bname[0] = *endp == '/' ? '/' : '.';
2004 bname[1] = '\0';
2005 return (0);
2006 } else {
2007 do {
2008 endp--;
2009 } while (endp > path && *endp == '/');
2010 }
2011
2012 if (endp - path + 2 > PATH_MAX)
2013 {
2014 _rtld_error("Filename is too long: %s", path);
2015 return(-1);
2016 }
2017
2018 strncpy(bname, path, endp - path + 1);
2019 bname[endp - path + 1] = '\0';
2020 return (0);
2021}
2022
2023static void
2024linkmap_add(Obj_Entry *obj)
2025{
2026 struct link_map *l = &obj->linkmap;
2027 struct link_map *prev;
2028
2029 obj->linkmap.l_name = obj->path;
2030 obj->linkmap.l_addr = obj->mapbase;
2031 obj->linkmap.l_ld = obj->dynamic;
2032#ifdef __mips__
2033 /* GDB needs load offset on MIPS to use the symbols */
2034 obj->linkmap.l_offs = obj->relocbase;
2035#endif
2036
2037 if (r_debug.r_map == NULL) {
2038 r_debug.r_map = l;
2039 return;
2040 }
2041
2042 /*
2043 * Scan to the end of the list, but not past the entry for the
2044 * dynamic linker, which we want to keep at the very end.
2045 */
2046 for (prev = r_debug.r_map;
2047 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2048 prev = prev->l_next)
2049 ;
2050
2051 /* Link in the new entry. */
2052 l->l_prev = prev;
2053 l->l_next = prev->l_next;
2054 if (l->l_next != NULL)
2055 l->l_next->l_prev = l;
2056 prev->l_next = l;
2057}
2058
2059static void
2060linkmap_delete(Obj_Entry *obj)
2061{
2062 struct link_map *l = &obj->linkmap;
2063
2064 if (l->l_prev == NULL) {
2065 if ((r_debug.r_map = l->l_next) != NULL)
2066 l->l_next->l_prev = NULL;
2067 return;
2068 }
2069
2070 if ((l->l_prev->l_next = l->l_next) != NULL)
2071 l->l_next->l_prev = l->l_prev;
2072}
2073
2074/*
2075 * Function for the debugger to set a breakpoint on to gain control.
2076 *
2077 * The two parameters allow the debugger to easily find and determine
2078 * what the runtime loader is doing and to whom it is doing it.
2079 *
2080 * When the loadhook trap is hit (r_debug_state, set at program
2081 * initialization), the arguments can be found on the stack:
2082 *
2083 * +8 struct link_map *m
2084 * +4 struct r_debug *rd
2085 * +0 RetAddr
2086 */
2087void
2088r_debug_state(struct r_debug* rd, struct link_map *m)
2089{
2090}
2091
2092/*
2093 * Get address of the pointer variable in the main program.
2094 */
2095static const void **
2096get_program_var_addr(const char *name)
2097{
2098 const Obj_Entry *obj;
2099 unsigned long hash;
2100
2101 hash = elf_hash(name);
2102 for (obj = obj_main; obj != NULL; obj = obj->next) {
2103 const Elf_Sym *def;
2104
2105 if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2106 const void **addr;
2107
2108 addr = (const void **)(obj->relocbase + def->st_value);
2109 return addr;
2110 }
2111 }
2112 return NULL;
2113}
2114
2115/*
2116 * Set a pointer variable in the main program to the given value. This
2117 * is used to set key variables such as "environ" before any of the
2118 * init functions are called.
2119 */
2120static void
2121set_program_var(const char *name, const void *value)
2122{
2123 const void **addr;
2124
2125 if ((addr = get_program_var_addr(name)) != NULL) {
2126 dbg("\"%s\": *%p <-- %p", name, addr, value);
2127 *addr = value;
2128 }
2129}
2130
8ca15ec8
MD
2131/*
2132 * This is a special version of getenv which is far more efficient
2133 * at finding LD_ environment vars.
2134 */
2135static
2136const char *
2137_getenv_ld(const char *id)
2138{
2139 const char *envp;
2140 int i, j;
2141 int idlen = strlen(id);
2142
2143 if (ld_index == LD_ARY_CACHE)
2144 return(getenv(id));
2145 if (ld_index == 0) {
2146 for (i = j = 0; (envp = environ[i]) != NULL && j < LD_ARY_CACHE; ++i) {
2147 if (envp[0] == 'L' && envp[1] == 'D' && envp[2] == '_')
2148 ld_ary[j++] = envp;
2149 }
2150 if (j == 0)
2151 ld_ary[j++] = "";
2152 ld_index = j;
2153 }
2154 for (i = ld_index - 1; i >= 0; --i) {
2155 if (strncmp(ld_ary[i], id, idlen) == 0 && ld_ary[i][idlen] == '=')
2156 return(ld_ary[i] + idlen + 1);
2157 }
2158 return(NULL);
2159}
2160
984263bc
MD
2161/*
2162 * Given a symbol name in a referencing object, find the corresponding
2163 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2164 * no definition was found. Returns a pointer to the Obj_Entry of the
2165 * defining object via the reference parameter DEFOBJ_OUT.
2166 */
2167static const Elf_Sym *
2168symlook_default(const char *name, unsigned long hash,
2169 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2170{
2171 DoneList donelist;
2172 const Elf_Sym *def;
2173 const Elf_Sym *symp;
2174 const Obj_Entry *obj;
2175 const Obj_Entry *defobj;
2176 const Objlist_Entry *elm;
2177 def = NULL;
2178 defobj = NULL;
2179 donelist_init(&donelist);
2180
2181 /* Look first in the referencing object if linked symbolically. */
2182 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2183 symp = symlook_obj(name, hash, refobj, in_plt);
2184 if (symp != NULL) {
2185 def = symp;
2186 defobj = refobj;
2187 }
2188 }
2189
2190 /* Search all objects loaded at program start up. */
2191 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2192 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2193 if (symp != NULL &&
2194 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2195 def = symp;
2196 defobj = obj;
2197 }
2198 }
2199
2200 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2201 STAILQ_FOREACH(elm, &list_global, link) {
2202 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2203 break;
2204 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2205 &donelist);
2206 if (symp != NULL &&
2207 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2208 def = symp;
2209 defobj = obj;
2210 }
2211 }
2212
2213 /* Search all dlopened DAGs containing the referencing object. */
2214 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2215 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2216 break;
2217 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2218 &donelist);
2219 if (symp != NULL &&
2220 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2221 def = symp;
2222 defobj = obj;
2223 }
2224 }
2225
2226 /*
2227 * Search the dynamic linker itself, and possibly resolve the
2228 * symbol from there. This is how the application links to
2229 * dynamic linker services such as dlopen. Only the values listed
2230 * in the "exports" array can be resolved from the dynamic linker.
2231 */
2232 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2233 symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2234 if (symp != NULL && is_exported(symp)) {
2235 def = symp;
2236 defobj = &obj_rtld;
2237 }
2238 }
2239
2240 if (def != NULL)
2241 *defobj_out = defobj;
2242 return def;
2243}
2244
2245static const Elf_Sym *
2246symlook_list(const char *name, unsigned long hash, Objlist *objlist,
2247 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2248{
2249 const Elf_Sym *symp;
2250 const Elf_Sym *def;
2251 const Obj_Entry *defobj;
2252 const Objlist_Entry *elm;
2253
2254 def = NULL;
2255 defobj = NULL;
2256 STAILQ_FOREACH(elm, objlist, link) {
2257 if (donelist_check(dlp, elm->obj))
2258 continue;
2259 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2260 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2261 def = symp;
2262 defobj = elm->obj;
2263 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2264 break;
2265 }
2266 }
2267 }
2268 if (def != NULL)
2269 *defobj_out = defobj;
2270 return def;
2271}
2272
2273/*
2274 * Search the symbol table of a single shared object for a symbol of
2275 * the given name. Returns a pointer to the symbol, or NULL if no
2276 * definition was found.
2277 *
2278 * The symbol's hash value is passed in for efficiency reasons; that
2279 * eliminates many recomputations of the hash value.
2280 */
2281const Elf_Sym *
2282symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2283 bool in_plt)
2284{
2285 if (obj->buckets != NULL) {
2286 unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2287
2288 while (symnum != STN_UNDEF) {
2289 const Elf_Sym *symp;
2290 const char *strp;
2291
2292 if (symnum >= obj->nchains)
2293 return NULL; /* Bad object */
2294 symp = obj->symtab + symnum;
2295 strp = obj->strtab + symp->st_name;
2296
2297 if (name[0] == strp[0] && strcmp(name, strp) == 0)
2298 return symp->st_shndx != SHN_UNDEF ||
2299 (!in_plt && symp->st_value != 0 &&
2300 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2301
2302 symnum = obj->chains[symnum];
2303 }
2304 }
2305 return NULL;
2306}
2307
2308static void
2309trace_loaded_objects(Obj_Entry *obj)
2310{
8ca15ec8 2311 const char *fmt1, *fmt2, *fmt, *main_local;
984263bc
MD
2312 int c;
2313
8ca15ec8 2314 if ((main_local = _getenv_ld("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
984263bc
MD
2315 main_local = "";
2316
8ca15ec8 2317 if ((fmt1 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
984263bc
MD
2318 fmt1 = "\t%o => %p (%x)\n";
2319
8ca15ec8 2320 if ((fmt2 = _getenv_ld("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
984263bc
MD
2321 fmt2 = "\t%o (%x)\n";
2322
2323 for (; obj; obj = obj->next) {
2324 Needed_Entry *needed;
2325 char *name, *path;
2326 bool is_lib;
2327
2328 for (needed = obj->needed; needed; needed = needed->next) {
2329 if (needed->obj != NULL) {
2330 if (needed->obj->traced)
2331 continue;
2332 needed->obj->traced = true;
2333 path = needed->obj->path;
2334 } else
2335 path = "not found";
2336
2337 name = (char *)obj->strtab + needed->name;
2338 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2339
2340 fmt = is_lib ? fmt1 : fmt2;
2341 while ((c = *fmt++) != '\0') {
2342 switch (c) {
2343 default:
2344 putchar(c);
2345 continue;
2346 case '\\':
2347 switch (c = *fmt) {
2348 case '\0':
2349 continue;
2350 case 'n':
2351 putchar('\n');
2352 break;
2353 case 't':
2354 putchar('\t');
2355 break;
2356 }
2357 break;
2358 case '%':
2359 switch (c = *fmt) {
2360 case '\0':
2361 continue;
2362 case '%':
2363 default:
2364 putchar(c);
2365 break;
2366 case 'A':
2367 printf("%s", main_local);
2368 break;
2369 case 'a':
2370 printf("%s", obj_main->path);
2371 break;
2372 case 'o':
2373 printf("%s", name);
2374 break;
2375#if 0
2376 case 'm':
2377 printf("%d", sodp->sod_major);
2378 break;
2379 case 'n':
2380 printf("%d", sodp->sod_minor);
2381 break;
2382#endif
2383 case 'p':
2384 printf("%s", path);
2385 break;
2386 case 'x':
2387 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2388 break;
2389 }
2390 break;
2391 }
2392 ++fmt;
2393 }
2394 }
2395 }
2396}
2397
2398/*
2399 * Unload a dlopened object and its dependencies from memory and from
2400 * our data structures. It is assumed that the DAG rooted in the
2401 * object has already been unreferenced, and that the object has a
2402 * reference count of 0.
2403 */
2404static void
2405unload_object(Obj_Entry *root)
2406{
2407 Obj_Entry *obj;
2408 Obj_Entry **linkp;
2409
2410 assert(root->refcount == 0);
2411
2412 /*
2413 * Pass over the DAG removing unreferenced objects from
2414 * appropriate lists.
2415 */
2416 unlink_object(root);
2417
2418 /* Unmap all objects that are no longer referenced. */
2419 linkp = &obj_list->next;
2420 while ((obj = *linkp) != NULL) {
2421 if (obj->refcount == 0) {
2422 dbg("unloading \"%s\"", obj->path);
2423 munmap(obj->mapbase, obj->mapsize);
2424 linkmap_delete(obj);
2425 *linkp = obj->next;
2426 obj_count--;
2427 obj_free(obj);
2428 } else
2429 linkp = &obj->next;
2430 }
2431 obj_tail = linkp;
2432}
2433
2434static void
2435unlink_object(Obj_Entry *root)
2436{
2437 const Needed_Entry *needed;
2438 Objlist_Entry *elm;
2439
2440 if (root->refcount == 0) {
2441 /* Remove the object from the RTLD_GLOBAL list. */
2442 objlist_remove(&list_global, root);
2443
2444 /* Remove the object from all objects' DAG lists. */
2445 STAILQ_FOREACH(elm, &root->dagmembers , link)
2446 objlist_remove(&elm->obj->dldags, root);
2447 }
2448
2449 for (needed = root->needed; needed != NULL; needed = needed->next)
2450 if (needed->obj != NULL)
2451 unlink_object(needed->obj);
2452}
2453
2454static void
2455unref_dag(Obj_Entry *root)
2456{
2457 const Needed_Entry *needed;
2458
2459 if (root->refcount == 0)
2460 return;
2461 root->refcount--;
2462 if (root->refcount == 0)
2463 for (needed = root->needed; needed != NULL; needed = needed->next)
2464 if (needed->obj != NULL)
2465 unref_dag(needed->obj);
2466}