Resident executable support stage 1/4: Add kernel bits and syscall support
[dragonfly.git] / libexec / rtld-elf / rtld.c
CommitLineData
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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 $
4e390e27 27 * $DragonFly: src/libexec/rtld-elf/rtld.c,v 1.4 2003/12/01 23:50:20 drhodus Exp $
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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>
43
44#include <dlfcn.h>
45#include <err.h>
46#include <errno.h>
47#include <fcntl.h>
48#include <stdarg.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52#include <unistd.h>
53
54#include "debug.h"
55#include "rtld.h"
56
57#define END_SYM "_end"
58#define PATH_RTLD "/usr/libexec/ld-elf.so.1"
59
60/* Types. */
61typedef void (*func_ptr_type)();
62typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
63
64/*
65 * This structure provides a reentrant way to keep a list of objects and
66 * check which ones have already been processed in some way.
67 */
68typedef struct Struct_DoneList {
69 const Obj_Entry **objs; /* Array of object pointers */
70 unsigned int num_alloc; /* Allocated size of the array */
71 unsigned int num_used; /* Number of array slots used */
72} DoneList;
73
74/*
75 * Function declarations.
76 */
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77static void die(void);
78static void digest_dynamic(Obj_Entry *);
79static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
80static Obj_Entry *dlcheck(void *);
81static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
82static bool donelist_check(DoneList *, const Obj_Entry *);
1c76efe5 83static u_int32_t elf_uniqid(u_int32_t, const void *, size_t);
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84static void errmsg_restore(char *);
85static char *errmsg_save(void);
86static void *fill_search_info(const char *, size_t, void *);
87static char *find_library(const char *, const Obj_Entry *);
88static const char *gethints(void);
89static void init_dag(Obj_Entry *);
90static void init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *);
91static void init_rtld(caddr_t);
92static void initlist_add_neededs(Needed_Entry *needed, Objlist *list);
93static void initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail,
94 Objlist *list);
95static bool is_exported(const Elf_Sym *);
96static void linkmap_add(Obj_Entry *);
97static void linkmap_delete(Obj_Entry *);
98static int load_needed_objects(Obj_Entry *);
99static int load_preload_objects(void);
100static Obj_Entry *load_object(char *);
101static void lock_check(void);
102static Obj_Entry *obj_from_addr(const void *);
103static void objlist_call_fini(Objlist *);
104static void objlist_call_init(Objlist *);
105static void objlist_clear(Objlist *);
106static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
107static void objlist_init(Objlist *);
108static void objlist_push_head(Objlist *, Obj_Entry *);
109static void objlist_push_tail(Objlist *, Obj_Entry *);
110static void objlist_remove(Objlist *, Obj_Entry *);
111static void objlist_remove_unref(Objlist *);
112static void *path_enumerate(const char *, path_enum_proc, void *);
113static int relocate_objects(Obj_Entry *, bool);
114static int rtld_dirname(const char *, char *);
115static void rtld_exit(void);
116static char *search_library_path(const char *, const char *);
117static const void **get_program_var_addr(const char *name);
118static void set_program_var(const char *, const void *);
119static const Elf_Sym *symlook_default(const char *, unsigned long hash,
120 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt);
121static const Elf_Sym *symlook_list(const char *, unsigned long,
122 Objlist *, const Obj_Entry **, bool in_plt, DoneList *);
123static void trace_loaded_objects(Obj_Entry *obj);
124static void unlink_object(Obj_Entry *);
125static void unload_object(Obj_Entry *);
126static void unref_dag(Obj_Entry *);
127
128void r_debug_state(struct r_debug*, struct link_map*);
129
130/*
131 * Data declarations.
132 */
133static char *error_message; /* Message for dlerror(), or NULL */
134struct r_debug r_debug; /* for GDB; */
135static bool trust; /* False for setuid and setgid programs */
136static char *ld_bind_now; /* Environment variable for immediate binding */
137static char *ld_debug; /* Environment variable for debugging */
138static char *ld_library_path; /* Environment variable for search path */
139static char *ld_preload; /* Environment variable for libraries to
140 load first */
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141static char *ld_tracing; /* Called from ldd(1) to print libs */
142static char *ld_prebind; /* Called from prebind(1) to prebind libs */
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143static Obj_Entry *obj_list; /* Head of linked list of shared objects */
144static Obj_Entry **obj_tail; /* Link field of last object in list */
145static Obj_Entry *obj_main; /* The main program shared object */
146static Obj_Entry obj_rtld; /* The dynamic linker shared object */
147static unsigned int obj_count; /* Number of objects in obj_list */
148
149static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
150 STAILQ_HEAD_INITIALIZER(list_global);
151static Objlist list_main = /* Objects loaded at program startup */
152 STAILQ_HEAD_INITIALIZER(list_main);
153static Objlist list_fini = /* Objects needing fini() calls */
154 STAILQ_HEAD_INITIALIZER(list_fini);
155
156static LockInfo lockinfo;
157
158static Elf_Sym sym_zero; /* For resolving undefined weak refs. */
159
160#define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
161
162extern Elf_Dyn _DYNAMIC;
163#pragma weak _DYNAMIC
164
165/*
166 * These are the functions the dynamic linker exports to application
167 * programs. They are the only symbols the dynamic linker is willing
168 * to export from itself.
169 */
170static func_ptr_type exports[] = {
171 (func_ptr_type) &_rtld_error,
172 (func_ptr_type) &dlclose,
173 (func_ptr_type) &dlerror,
174 (func_ptr_type) &dlopen,
175 (func_ptr_type) &dlsym,
176 (func_ptr_type) &dladdr,
177 (func_ptr_type) &dllockinit,
178 (func_ptr_type) &dlinfo,
179 NULL
180};
181
182/*
183 * Global declarations normally provided by crt1. The dynamic linker is
184 * not built with crt1, so we have to provide them ourselves.
185 */
186char *__progname;
187char **environ;
188
189/*
190 * Fill in a DoneList with an allocation large enough to hold all of
191 * the currently-loaded objects. Keep this as a macro since it calls
192 * alloca and we want that to occur within the scope of the caller.
193 */
194#define donelist_init(dlp) \
195 ((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
196 assert((dlp)->objs != NULL), \
197 (dlp)->num_alloc = obj_count, \
198 (dlp)->num_used = 0)
199
200static __inline void
201rlock_acquire(void)
202{
203 lockinfo.rlock_acquire(lockinfo.thelock);
204 atomic_incr_int(&lockinfo.rcount);
205 lock_check();
206}
207
208static __inline void
209wlock_acquire(void)
210{
211 lockinfo.wlock_acquire(lockinfo.thelock);
212 atomic_incr_int(&lockinfo.wcount);
213 lock_check();
214}
215
216static __inline void
217rlock_release(void)
218{
219 atomic_decr_int(&lockinfo.rcount);
220 lockinfo.rlock_release(lockinfo.thelock);
221}
222
223static __inline void
224wlock_release(void)
225{
226 atomic_decr_int(&lockinfo.wcount);
227 lockinfo.wlock_release(lockinfo.thelock);
228}
229
230/*
231 * Main entry point for dynamic linking. The first argument is the
232 * stack pointer. The stack is expected to be laid out as described
233 * in the SVR4 ABI specification, Intel 386 Processor Supplement.
234 * Specifically, the stack pointer points to a word containing
235 * ARGC. Following that in the stack is a null-terminated sequence
236 * of pointers to argument strings. Then comes a null-terminated
237 * sequence of pointers to environment strings. Finally, there is a
238 * sequence of "auxiliary vector" entries.
239 *
240 * The second argument points to a place to store the dynamic linker's
241 * exit procedure pointer and the third to a place to store the main
242 * program's object.
243 *
244 * The return value is the main program's entry point.
245 */
246func_ptr_type
247_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
248{
249 Elf_Auxinfo *aux_info[AT_COUNT];
250 int i;
251 int argc;
252 char **argv;
253 char **env;
254 Elf_Auxinfo *aux;
255 Elf_Auxinfo *auxp;
256 const char *argv0;
257 Obj_Entry *obj;
258 Obj_Entry **preload_tail;
259 Objlist initlist;
1c76efe5 260 int prebind_disable = 0;
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261
262 /*
263 * On entry, the dynamic linker itself has not been relocated yet.
264 * Be very careful not to reference any global data until after
265 * init_rtld has returned. It is OK to reference file-scope statics
266 * and string constants, and to call static and global functions.
267 */
268
269 /* Find the auxiliary vector on the stack. */
270 argc = *sp++;
271 argv = (char **) sp;
272 sp += argc + 1; /* Skip over arguments and NULL terminator */
273 env = (char **) sp;
274 while (*sp++ != 0) /* Skip over environment, and NULL terminator */
275 ;
276 aux = (Elf_Auxinfo *) sp;
277
278 /* Digest the auxiliary vector. */
279 for (i = 0; i < AT_COUNT; i++)
280 aux_info[i] = NULL;
281 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
282 if (auxp->a_type < AT_COUNT)
283 aux_info[auxp->a_type] = auxp;
284 }
285
286 /* Initialize and relocate ourselves. */
287 assert(aux_info[AT_BASE] != NULL);
288 init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
289
290 __progname = obj_rtld.path;
291 argv0 = argv[0] != NULL ? argv[0] : "(null)";
292 environ = env;
293
294 trust = geteuid() == getuid() && getegid() == getgid();
295
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296 prebind_disable = getenv("LD_PREBIND_DISABLE") != NULL;
297
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298 ld_bind_now = getenv("LD_BIND_NOW");
299 if (trust) {
300 ld_debug = getenv("LD_DEBUG");
301 ld_library_path = getenv("LD_LIBRARY_PATH");
302 ld_preload = getenv("LD_PRELOAD");
303 }
304 ld_tracing = getenv("LD_TRACE_LOADED_OBJECTS");
305
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306 if (trust) {
307 ld_prebind = getenv("LD_PREBIND");
308 if (ld_prebind != NULL && *ld_prebind != '\0') {
309 ld_bind_now = ld_prebind;
310 prebind_disable = 1;
311 }
312 }
313
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314 if (ld_debug != NULL && *ld_debug != '\0')
315 debug = 1;
316 dbg("%s is initialized, base address = %p", __progname,
317 (caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
318 dbg("RTLD dynamic = %p", obj_rtld.dynamic);
319 dbg("RTLD pltgot = %p", obj_rtld.pltgot);
320
321 /*
322 * Load the main program, or process its program header if it is
323 * already loaded.
324 */
325 if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
326 int fd = aux_info[AT_EXECFD]->a_un.a_val;
327 dbg("loading main program");
328 obj_main = map_object(fd, argv0, NULL);
329 close(fd);
330 if (obj_main == NULL)
331 die();
332 } else { /* Main program already loaded. */
333 const Elf_Phdr *phdr;
334 int phnum;
335 caddr_t entry;
336
337 dbg("processing main program's program header");
338 assert(aux_info[AT_PHDR] != NULL);
339 phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
340 assert(aux_info[AT_PHNUM] != NULL);
341 phnum = aux_info[AT_PHNUM]->a_un.a_val;
342 assert(aux_info[AT_PHENT] != NULL);
343 assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
344 assert(aux_info[AT_ENTRY] != NULL);
345 entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
346 if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
347 die();
348 }
349
350 obj_main->path = xstrdup(argv0);
351 obj_main->mainprog = true;
352
353 /*
354 * Get the actual dynamic linker pathname from the executable if
355 * possible. (It should always be possible.) That ensures that
356 * gdb will find the right dynamic linker even if a non-standard
357 * one is being used.
358 */
359 if (obj_main->interp != NULL &&
360 strcmp(obj_main->interp, obj_rtld.path) != 0) {
361 free(obj_rtld.path);
362 obj_rtld.path = xstrdup(obj_main->interp);
363 }
364
365 digest_dynamic(obj_main);
366
367 linkmap_add(obj_main);
368 linkmap_add(&obj_rtld);
369
370 /* Link the main program into the list of objects. */
371 *obj_tail = obj_main;
372 obj_tail = &obj_main->next;
373 obj_count++;
374 obj_main->refcount++;
375 /* Make sure we don't call the main program's init and fini functions. */
376 obj_main->init = obj_main->fini = NULL;
377
378 /* Initialize a fake symbol for resolving undefined weak references. */
379 sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
380 sym_zero.st_shndx = SHN_ABS;
381
382 dbg("loading LD_PRELOAD libraries");
383 if (load_preload_objects() == -1)
384 die();
385 preload_tail = obj_tail;
386
387 dbg("loading needed objects");
388 if (load_needed_objects(obj_main) == -1)
389 die();
390
391 /* Make a list of all objects loaded at startup. */
392 for (obj = obj_list; obj != NULL; obj = obj->next)
393 objlist_push_tail(&list_main, obj);
394
395 if (ld_tracing) { /* We're done */
396 trace_loaded_objects(obj_main);
397 exit(0);
398 }
399
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400 if (prebind_disable || prebind_load(&obj_rtld, obj_main)) {
401 if (relocate_objects(obj_main,
402 ld_bind_now != NULL && *ld_bind_now != '\0') == -1)
403 die();
984263bc 404
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405 dbg("doing copy relocations");
406 if (do_copy_relocations(obj_main) == -1)
407 die();
408 }
409
410 if (ld_prebind != NULL && *ld_prebind != '\0')
411 exit (prebind_save(&obj_rtld, obj_main));
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412
413 dbg("initializing key program variables");
414 set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
415 set_program_var("environ", env);
416
417 dbg("initializing thread locks");
418 lockdflt_init(&lockinfo);
419 lockinfo.thelock = lockinfo.lock_create(lockinfo.context);
420
421 /* Make a list of init functions to call. */
422 objlist_init(&initlist);
423 initlist_add_objects(obj_list, preload_tail, &initlist);
424
425 r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
426
427 objlist_call_init(&initlist);
428 wlock_acquire();
429 objlist_clear(&initlist);
430 wlock_release();
431
432 dbg("transferring control to program entry point = %p", obj_main->entry);
433
434 /* Return the exit procedure and the program entry point. */
435 *exit_proc = rtld_exit;
436 *objp = obj_main;
437 return (func_ptr_type) obj_main->entry;
438}
439
440Elf_Addr
441_rtld_bind(Obj_Entry *obj, Elf_Word reloff)
442{
443 const Elf_Rel *rel;
444 const Elf_Sym *def;
445 const Obj_Entry *defobj;
446 Elf_Addr *where;
447 Elf_Addr target;
448
449 rlock_acquire();
450 if (obj->pltrel)
451 rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
452 else
453 rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
454
455 where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
456 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL);
457 if (def == NULL)
458 die();
459
460 target = (Elf_Addr)(defobj->relocbase + def->st_value);
461
462 dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
463 defobj->strtab + def->st_name, basename(obj->path),
464 (void *)target, basename(defobj->path));
465
466 reloc_jmpslot(where, target);
467 rlock_release();
468 return target;
469}
470
471/*
472 * Error reporting function. Use it like printf. If formats the message
473 * into a buffer, and sets things up so that the next call to dlerror()
474 * will return the message.
475 */
476void
477_rtld_error(const char *fmt, ...)
478{
479 static char buf[512];
480 va_list ap;
481
482 va_start(ap, fmt);
483 vsnprintf(buf, sizeof buf, fmt, ap);
484 error_message = buf;
485 va_end(ap);
486}
487
488/*
489 * Return a dynamically-allocated copy of the current error message, if any.
490 */
491static char *
492errmsg_save(void)
493{
494 return error_message == NULL ? NULL : xstrdup(error_message);
495}
496
497/*
498 * Restore the current error message from a copy which was previously saved
499 * by errmsg_save(). The copy is freed.
500 */
501static void
502errmsg_restore(char *saved_msg)
503{
504 if (saved_msg == NULL)
505 error_message = NULL;
506 else {
507 _rtld_error("%s", saved_msg);
508 free(saved_msg);
509 }
510}
511
1c76efe5 512const char *
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513basename(const char *name)
514{
515 const char *p = strrchr(name, '/');
516 return p != NULL ? p + 1 : name;
517}
518
519static void
520die(void)
521{
522 const char *msg = dlerror();
523
524 if (msg == NULL)
525 msg = "Fatal error";
526 errx(1, "%s", msg);
527}
528
529/*
530 * Process a shared object's DYNAMIC section, and save the important
531 * information in its Obj_Entry structure.
532 */
533static void
534digest_dynamic(Obj_Entry *obj)
535{
536 const Elf_Dyn *dynp;
537 Needed_Entry **needed_tail = &obj->needed;
538 const Elf_Dyn *dyn_rpath = NULL;
539 int plttype = DT_REL;
540
541 for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
542 switch (dynp->d_tag) {
543
544 case DT_REL:
545 obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
546 break;
547
548 case DT_RELSZ:
549 obj->relsize = dynp->d_un.d_val;
550 break;
551
552 case DT_RELENT:
553 assert(dynp->d_un.d_val == sizeof(Elf_Rel));
554 break;
555
556 case DT_JMPREL:
557 obj->pltrel = (const Elf_Rel *)
558 (obj->relocbase + dynp->d_un.d_ptr);
559 break;
560
561 case DT_PLTRELSZ:
562 obj->pltrelsize = dynp->d_un.d_val;
563 break;
564
565 case DT_RELA:
566 obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
567 break;
568
569 case DT_RELASZ:
570 obj->relasize = dynp->d_un.d_val;
571 break;
572
573 case DT_RELAENT:
574 assert(dynp->d_un.d_val == sizeof(Elf_Rela));
575 break;
576
577 case DT_PLTREL:
578 plttype = dynp->d_un.d_val;
579 assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
580 break;
581
582 case DT_SYMTAB:
583 obj->symtab = (const Elf_Sym *)
584 (obj->relocbase + dynp->d_un.d_ptr);
585 break;
586
587 case DT_SYMENT:
588 assert(dynp->d_un.d_val == sizeof(Elf_Sym));
589 break;
590
591 case DT_STRTAB:
592 obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
593 break;
594
595 case DT_STRSZ:
596 obj->strsize = dynp->d_un.d_val;
597 break;
598
599 case DT_HASH:
600 {
601 const Elf_Addr *hashtab = (const Elf_Addr *)
602 (obj->relocbase + dynp->d_un.d_ptr);
603 obj->nbuckets = hashtab[0];
604 obj->nchains = hashtab[1];
605 obj->buckets = hashtab + 2;
606 obj->chains = obj->buckets + obj->nbuckets;
607 }
608 break;
609
610 case DT_NEEDED:
611 if (!obj->rtld) {
612 Needed_Entry *nep = NEW(Needed_Entry);
613 nep->name = dynp->d_un.d_val;
614 nep->obj = NULL;
615 nep->next = NULL;
616
617 *needed_tail = nep;
618 needed_tail = &nep->next;
619 }
620 break;
621
622 case DT_PLTGOT:
623 obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
624 break;
625
626 case DT_TEXTREL:
627 obj->textrel = true;
628 break;
629
630 case DT_SYMBOLIC:
631 obj->symbolic = true;
632 break;
633
634 case DT_RPATH:
635 /*
636 * We have to wait until later to process this, because we
637 * might not have gotten the address of the string table yet.
638 */
639 dyn_rpath = dynp;
640 break;
641
642 case DT_SONAME:
643 /* Not used by the dynamic linker. */
644 break;
645
646 case DT_INIT:
647 obj->init = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
648 break;
649
650 case DT_FINI:
651 obj->fini = (InitFunc) (obj->relocbase + dynp->d_un.d_ptr);
652 break;
653
654 case DT_DEBUG:
655 /* XXX - not implemented yet */
656 dbg("Filling in DT_DEBUG entry");
657 ((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
658 break;
659
660 default:
661 dbg("Ignoring d_tag %d = %#x", dynp->d_tag, dynp->d_tag);
662 break;
663 }
664 }
665
666 obj->traced = false;
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667 obj->uniqid = 1;
668
669 if (obj->pltrelsize)
670 obj->uniqid = elf_uniqid(obj->uniqid, obj->pltrel, obj->pltrelsize);
671 if (obj->symtab)
672 obj->uniqid = elf_uniqid(obj->uniqid, obj->symtab, obj->nchains * sizeof(*obj->symtab));
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673
674 if (plttype == DT_RELA) {
675 obj->pltrela = (const Elf_Rela *) obj->pltrel;
676 obj->pltrel = NULL;
677 obj->pltrelasize = obj->pltrelsize;
678 obj->pltrelsize = 0;
679 }
680
681 if (dyn_rpath != NULL)
682 obj->rpath = obj->strtab + dyn_rpath->d_un.d_val;
683}
684
685/*
686 * Process a shared object's program header. This is used only for the
687 * main program, when the kernel has already loaded the main program
688 * into memory before calling the dynamic linker. It creates and
689 * returns an Obj_Entry structure.
690 */
691static Obj_Entry *
692digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
693{
694 Obj_Entry *obj;
695 const Elf_Phdr *phlimit = phdr + phnum;
696 const Elf_Phdr *ph;
697 int nsegs = 0;
698
699 obj = obj_new();
700 for (ph = phdr; ph < phlimit; ph++) {
701 switch (ph->p_type) {
702
703 case PT_PHDR:
704 if ((const Elf_Phdr *)ph->p_vaddr != phdr) {
705 _rtld_error("%s: invalid PT_PHDR", path);
706 return NULL;
707 }
708 obj->phdr = (const Elf_Phdr *) ph->p_vaddr;
709 obj->phsize = ph->p_memsz;
710 break;
711
712 case PT_INTERP:
713 obj->interp = (const char *) ph->p_vaddr;
714 break;
715
716 case PT_LOAD:
717 if (nsegs == 0) { /* First load segment */
718 obj->vaddrbase = trunc_page(ph->p_vaddr);
719 obj->mapbase = (caddr_t) obj->vaddrbase;
720 obj->relocbase = obj->mapbase - obj->vaddrbase;
721 obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
722 obj->vaddrbase;
723 } else { /* Last load segment */
724 obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
725 obj->vaddrbase;
726 }
727 nsegs++;
728 break;
729
730 case PT_DYNAMIC:
731 obj->dynamic = (const Elf_Dyn *) ph->p_vaddr;
732 break;
733 }
734 }
735 if (nsegs < 1) {
736 _rtld_error("%s: too few PT_LOAD segments", path);
737 return NULL;
738 }
739
740 obj->entry = entry;
741 return obj;
742}
743
744static Obj_Entry *
745dlcheck(void *handle)
746{
747 Obj_Entry *obj;
748
749 for (obj = obj_list; obj != NULL; obj = obj->next)
750 if (obj == (Obj_Entry *) handle)
751 break;
752
753 if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
754 _rtld_error("Invalid shared object handle %p", handle);
755 return NULL;
756 }
757 return obj;
758}
759
760/*
761 * If the given object is already in the donelist, return true. Otherwise
762 * add the object to the list and return false.
763 */
764static bool
765donelist_check(DoneList *dlp, const Obj_Entry *obj)
766{
767 unsigned int i;
768
769 for (i = 0; i < dlp->num_used; i++)
770 if (dlp->objs[i] == obj)
771 return true;
772 /*
773 * Our donelist allocation should always be sufficient. But if
774 * our threads locking isn't working properly, more shared objects
775 * could have been loaded since we allocated the list. That should
776 * never happen, but we'll handle it properly just in case it does.
777 */
778 if (dlp->num_used < dlp->num_alloc)
779 dlp->objs[dlp->num_used++] = obj;
780 return false;
781}
782
783/*
784 * Hash function for symbol table lookup. Don't even think about changing
785 * this. It is specified by the System V ABI.
786 */
787unsigned long
788elf_hash(const char *name)
789{
790 const unsigned char *p = (const unsigned char *) name;
791 unsigned long h = 0;
792 unsigned long g;
793
794 while (*p != '\0') {
795 h = (h << 4) + *p++;
796 if ((g = h & 0xf0000000) != 0)
797 h ^= g >> 24;
798 h &= ~g;
799 }
800 return h;
801}
802
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803/*
804 * Hash function to get an unique ID from an ELF object file
805 * needs to be fast and small
806 *
807 * This one is after Krovetz, Rogaway: The PolyR construction,
808 * http://www.cs.ucdavis.edu/~rogaway/papers/poly.htm
809 *
810 * If called for the first time on a block, pass hash = 1
811 */
812static u_int32_t
813elf_uniqid(u_int32_t hash, const void *data, size_t len)
814{
815 const u_int32_t p = 0xfffffffb; /* The largest prime smaller than 2^32 */
816 const u_int32_t offset = 5; /* Constant for translating out-of-range words */
817 const u_int32_t marker = 0xfffffffa; /* Constant for indicating out-of-range words */
818 const u_int32_t key = RTLD_TS; /* Hash key XXX */
819 u_int32_t n = len / 4; /* 32 bit blocks */
820 u_int32_t remainder = 0;
821 const u_int32_t *block;
822
823 for (block = data; n; --n, ++block)
824uniqid_hash:
825 if (*block >= p - 1) { /* If word is not in range, then */
826 hash = uniqid_hash_block(hash, key, marker); /* Maker indicates out-of-range */
827 hash = uniqid_hash_block(hash, key, *block - offset); /* Offset m back into range */
828 } else
829 hash = uniqid_hash_block(hash, key, *block);
830
831 if (len % 4) { /* we got some remainder */
832 memcpy(&remainder, block, len % 4); /* copy remaining bytes into 0-padded block */
833 block = &remainder; /* set up pointer */
834 n = 1; /* one block to process */
835 len = 0; /* we've done the remainder */
836 goto uniqid_hash; /* run once again */
837 }
838
839 return hash;
840}
841
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842/*
843 * Find the library with the given name, and return its full pathname.
844 * The returned string is dynamically allocated. Generates an error
845 * message and returns NULL if the library cannot be found.
846 *
847 * If the second argument is non-NULL, then it refers to an already-
848 * loaded shared object, whose library search path will be searched.
849 *
850 * The search order is:
984263bc 851 * LD_LIBRARY_PATH
4e390e27 852 * rpath in the referencing file
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853 * ldconfig hints
854 * /usr/lib
855 */
856static char *
857find_library(const char *name, const Obj_Entry *refobj)
858{
859 char *pathname;
860
861 if (strchr(name, '/') != NULL) { /* Hard coded pathname */
862 if (name[0] != '/' && !trust) {
863 _rtld_error("Absolute pathname required for shared object \"%s\"",
864 name);
865 return NULL;
866 }
867 return xstrdup(name);
868 }
869
870 dbg(" Searching for \"%s\"", name);
871
872 if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
873 (refobj != NULL &&
874 (pathname = search_library_path(name, refobj->rpath)) != NULL) ||
875 (pathname = search_library_path(name, gethints())) != NULL ||
876 (pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
877 return pathname;
878
879 _rtld_error("Shared object \"%s\" not found", name);
880 return NULL;
881}
882
883/*
884 * Given a symbol number in a referencing object, find the corresponding
885 * definition of the symbol. Returns a pointer to the symbol, or NULL if
886 * no definition was found. Returns a pointer to the Obj_Entry of the
887 * defining object via the reference parameter DEFOBJ_OUT.
888 */
889const Elf_Sym *
890find_symdef(unsigned long symnum, const Obj_Entry *refobj,
891 const Obj_Entry **defobj_out, bool in_plt, SymCache *cache)
892{
893 const Elf_Sym *ref;
894 const Elf_Sym *def;
895 const Obj_Entry *defobj;
896 const char *name;
897 unsigned long hash;
898
899 /*
900 * If we have already found this symbol, get the information from
901 * the cache.
902 */
903 if (symnum >= refobj->nchains)
904 return NULL; /* Bad object */
905 if (cache != NULL && cache[symnum].sym != NULL) {
906 *defobj_out = cache[symnum].obj;
907 return cache[symnum].sym;
908 }
909
910 ref = refobj->symtab + symnum;
911 name = refobj->strtab + ref->st_name;
912 hash = elf_hash(name);
913 defobj = NULL;
914
915 def = symlook_default(name, hash, refobj, &defobj, in_plt);
916
917 /*
918 * If we found no definition and the reference is weak, treat the
919 * symbol as having the value zero.
920 */
921 if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
922 def = &sym_zero;
923 defobj = obj_main;
924 }
925
926 if (def != NULL) {
927 *defobj_out = defobj;
928 /* Record the information in the cache to avoid subsequent lookups. */
929 if (cache != NULL) {
930 cache[symnum].sym = def;
931 cache[symnum].obj = defobj;
932 }
933 } else
934 _rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
935 return def;
936}
937
938/*
939 * Return the search path from the ldconfig hints file, reading it if
940 * necessary. Returns NULL if there are problems with the hints file,
941 * or if the search path there is empty.
942 */
943static const char *
944gethints(void)
945{
946 static char *hints;
947
948 if (hints == NULL) {
949 int fd;
950 struct elfhints_hdr hdr;
951 char *p;
952
953 /* Keep from trying again in case the hints file is bad. */
954 hints = "";
955
956 if ((fd = open(_PATH_ELF_HINTS, O_RDONLY)) == -1)
957 return NULL;
958 if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
959 hdr.magic != ELFHINTS_MAGIC ||
960 hdr.version != 1) {
961 close(fd);
962 return NULL;
963 }
964 p = xmalloc(hdr.dirlistlen + 1);
965 if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
966 read(fd, p, hdr.dirlistlen + 1) != hdr.dirlistlen + 1) {
967 free(p);
968 close(fd);
969 return NULL;
970 }
971 hints = p;
972 close(fd);
973 }
974 return hints[0] != '\0' ? hints : NULL;
975}
976
977static void
978init_dag(Obj_Entry *root)
979{
980 DoneList donelist;
981
982 donelist_init(&donelist);
983 init_dag1(root, root, &donelist);
984}
985
986static void
987init_dag1(Obj_Entry *root, Obj_Entry *obj, DoneList *dlp)
988{
989 const Needed_Entry *needed;
990
991 if (donelist_check(dlp, obj))
992 return;
993 objlist_push_tail(&obj->dldags, root);
994 objlist_push_tail(&root->dagmembers, obj);
995 for (needed = obj->needed; needed != NULL; needed = needed->next)
996 if (needed->obj != NULL)
997 init_dag1(root, needed->obj, dlp);
998}
999
1000/*
1001 * Initialize the dynamic linker. The argument is the address at which
1002 * the dynamic linker has been mapped into memory. The primary task of
1003 * this function is to relocate the dynamic linker.
1004 */
1005static void
1006init_rtld(caddr_t mapbase)
1007{
1008 /*
1009 * Conjure up an Obj_Entry structure for the dynamic linker.
1010 *
1011 * The "path" member is supposed to be dynamically-allocated, but we
1012 * aren't yet initialized sufficiently to do that. Below we will
1013 * replace the static version with a dynamically-allocated copy.
1014 */
1015 obj_rtld.path = PATH_RTLD;
1016 obj_rtld.rtld = true;
1017 obj_rtld.mapbase = mapbase;
1018#ifdef PIC
1019 obj_rtld.relocbase = mapbase;
1020#endif
1021 if (&_DYNAMIC != 0) {
1022 obj_rtld.dynamic = rtld_dynamic(&obj_rtld);
1023 digest_dynamic(&obj_rtld);
1024 assert(obj_rtld.needed == NULL);
1025 assert(!obj_rtld.textrel);
1026
1027 /*
1028 * Temporarily put the dynamic linker entry into the object list, so
1029 * that symbols can be found.
1030 */
1031 obj_list = &obj_rtld;
1032 obj_tail = &obj_rtld.next;
1033 obj_count = 1;
1034
1035 relocate_objects(&obj_rtld, true);
1036 }
1037
1038 /* Make the object list empty again. */
1039 obj_list = NULL;
1040 obj_tail = &obj_list;
1041 obj_count = 0;
1042
1043 /* Replace the path with a dynamically allocated copy. */
1044 obj_rtld.path = xstrdup(obj_rtld.path);
1045
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1046 obj_rtld.uniqid = RTLD_TS;
1047
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1048 r_debug.r_brk = r_debug_state;
1049 r_debug.r_state = RT_CONSISTENT;
1050}
1051
1052/*
1053 * Add the init functions from a needed object list (and its recursive
1054 * needed objects) to "list". This is not used directly; it is a helper
1055 * function for initlist_add_objects(). The write lock must be held
1056 * when this function is called.
1057 */
1058static void
1059initlist_add_neededs(Needed_Entry *needed, Objlist *list)
1060{
1061 /* Recursively process the successor needed objects. */
1062 if (needed->next != NULL)
1063 initlist_add_neededs(needed->next, list);
1064
1065 /* Process the current needed object. */
1066 if (needed->obj != NULL)
1067 initlist_add_objects(needed->obj, &needed->obj->next, list);
1068}
1069
1070/*
1071 * Scan all of the DAGs rooted in the range of objects from "obj" to
1072 * "tail" and add their init functions to "list". This recurses over
1073 * the DAGs and ensure the proper init ordering such that each object's
1074 * needed libraries are initialized before the object itself. At the
1075 * same time, this function adds the objects to the global finalization
1076 * list "list_fini" in the opposite order. The write lock must be
1077 * held when this function is called.
1078 */
1079static void
1080initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
1081{
1082 if (obj->init_done)
1083 return;
1084 obj->init_done = true;
1085
1086 /* Recursively process the successor objects. */
1087 if (&obj->next != tail)
1088 initlist_add_objects(obj->next, tail, list);
1089
1090 /* Recursively process the needed objects. */
1091 if (obj->needed != NULL)
1092 initlist_add_neededs(obj->needed, list);
1093
1094 /* Add the object to the init list. */
1095 if (obj->init != NULL)
1096 objlist_push_tail(list, obj);
1097
1098 /* Add the object to the global fini list in the reverse order. */
1099 if (obj->fini != NULL)
1100 objlist_push_head(&list_fini, obj);
1101}
1102
1103static bool
1104is_exported(const Elf_Sym *def)
1105{
1106 func_ptr_type value;
1107 const func_ptr_type *p;
1108
1109 value = (func_ptr_type)(obj_rtld.relocbase + def->st_value);
1110 for (p = exports; *p != NULL; p++)
1111 if (*p == value)
1112 return true;
1113 return false;
1114}
1115
1116/*
1117 * Given a shared object, traverse its list of needed objects, and load
1118 * each of them. Returns 0 on success. Generates an error message and
1119 * returns -1 on failure.
1120 */
1121static int
1122load_needed_objects(Obj_Entry *first)
1123{
1124 Obj_Entry *obj;
1125
1126 for (obj = first; obj != NULL; obj = obj->next) {
1127 Needed_Entry *needed;
1128
1129 for (needed = obj->needed; needed != NULL; needed = needed->next) {
1130 const char *name = obj->strtab + needed->name;
1131 char *path = find_library(name, obj);
1132
1133 needed->obj = NULL;
1134 if (path == NULL && !ld_tracing)
1135 return -1;
1136
1137 if (path) {
1138 needed->obj = load_object(path);
1139 if (needed->obj == NULL && !ld_tracing)
1140 return -1; /* XXX - cleanup */
1141 }
1142 }
1143 }
1144
1145 return 0;
1146}
1147
1148static int
1149load_preload_objects(void)
1150{
1151 char *p = ld_preload;
1152 static const char delim[] = " \t:;";
1153
1154 if (p == NULL)
1155 return NULL;
1156
1157 p += strspn(p, delim);
1158 while (*p != '\0') {
1159 size_t len = strcspn(p, delim);
1160 char *path;
1161 char savech;
1162
1163 savech = p[len];
1164 p[len] = '\0';
1165 if ((path = find_library(p, NULL)) == NULL)
1166 return -1;
1167 if (load_object(path) == NULL)
1168 return -1; /* XXX - cleanup */
1169 p[len] = savech;
1170 p += len;
1171 p += strspn(p, delim);
1172 }
1173 return 0;
1174}
1175
1176/*
1177 * Load a shared object into memory, if it is not already loaded. The
1178 * argument must be a string allocated on the heap. This function assumes
1179 * responsibility for freeing it when necessary.
1180 *
1181 * Returns a pointer to the Obj_Entry for the object. Returns NULL
1182 * on failure.
1183 */
1184static Obj_Entry *
1185load_object(char *path)
1186{
1187 Obj_Entry *obj;
1188 int fd = -1;
1189 struct stat sb;
1190
1191 for (obj = obj_list->next; obj != NULL; obj = obj->next)
1192 if (strcmp(obj->path, path) == 0)
1193 break;
1194
1195 /*
1196 * If we didn't find a match by pathname, open the file and check
1197 * again by device and inode. This avoids false mismatches caused
1198 * by multiple links or ".." in pathnames.
1199 *
1200 * To avoid a race, we open the file and use fstat() rather than
1201 * using stat().
1202 */
1203 if (obj == NULL) {
1204 if ((fd = open(path, O_RDONLY)) == -1) {
1205 _rtld_error("Cannot open \"%s\"", path);
1206 return NULL;
1207 }
1208 if (fstat(fd, &sb) == -1) {
1209 _rtld_error("Cannot fstat \"%s\"", path);
1210 close(fd);
1211 return NULL;
1212 }
1213 for (obj = obj_list->next; obj != NULL; obj = obj->next) {
1214 if (obj->ino == sb.st_ino && obj->dev == sb.st_dev) {
1215 close(fd);
1216 break;
1217 }
1218 }
1219 }
1220
1221 if (obj == NULL) { /* First use of this object, so we must map it in */
1222 dbg("loading \"%s\"", path);
1223 obj = map_object(fd, path, &sb);
1224 close(fd);
1225 if (obj == NULL) {
1226 free(path);
1227 return NULL;
1228 }
1229
1230 obj->path = path;
1231 digest_dynamic(obj);
1232
1233 *obj_tail = obj;
1234 obj_tail = &obj->next;
1235 obj_count++;
1236 linkmap_add(obj); /* for GDB & dlinfo() */
1237
1238 dbg(" %p .. %p: %s", obj->mapbase,
1239 obj->mapbase + obj->mapsize - 1, obj->path);
1240 if (obj->textrel)
1241 dbg(" WARNING: %s has impure text", obj->path);
1242 } else
1243 free(path);
1244
1245 obj->refcount++;
1246 return obj;
1247}
1248
1249/*
1250 * Check for locking violations and die if one is found.
1251 */
1252static void
1253lock_check(void)
1254{
1255 int rcount, wcount;
1256
1257 rcount = lockinfo.rcount;
1258 wcount = lockinfo.wcount;
1259 assert(rcount >= 0);
1260 assert(wcount >= 0);
1261 if (wcount > 1 || (wcount != 0 && rcount != 0)) {
1262 _rtld_error("Application locking error: %d readers and %d writers"
1263 " in dynamic linker. See DLLOCKINIT(3) in manual pages.",
1264 rcount, wcount);
1265 die();
1266 }
1267}
1268
1269static Obj_Entry *
1270obj_from_addr(const void *addr)
1271{
1272 unsigned long endhash;
1273 Obj_Entry *obj;
1274
1275 endhash = elf_hash(END_SYM);
1276 for (obj = obj_list; obj != NULL; obj = obj->next) {
1277 const Elf_Sym *endsym;
1278
1279 if (addr < (void *) obj->mapbase)
1280 continue;
1281 if ((endsym = symlook_obj(END_SYM, endhash, obj, true)) == NULL)
1282 continue; /* No "end" symbol?! */
1283 if (addr < (void *) (obj->relocbase + endsym->st_value))
1284 return obj;
1285 }
1286 return NULL;
1287}
1288
1289/*
1290 * Call the finalization functions for each of the objects in "list"
1291 * which are unreferenced. All of the objects are expected to have
1292 * non-NULL fini functions.
1293 */
1294static void
1295objlist_call_fini(Objlist *list)
1296{
1297 Objlist_Entry *elm;
1298 char *saved_msg;
1299
1300 /*
1301 * Preserve the current error message since a fini function might
1302 * call into the dynamic linker and overwrite it.
1303 */
1304 saved_msg = errmsg_save();
1305 STAILQ_FOREACH(elm, list, link) {
1306 if (elm->obj->refcount == 0) {
1307 dbg("calling fini function for %s", elm->obj->path);
1308 (*elm->obj->fini)();
1309 }
1310 }
1311 errmsg_restore(saved_msg);
1312}
1313
1314/*
1315 * Call the initialization functions for each of the objects in
1316 * "list". All of the objects are expected to have non-NULL init
1317 * functions.
1318 */
1319static void
1320objlist_call_init(Objlist *list)
1321{
1322 Objlist_Entry *elm;
1323 char *saved_msg;
1324
1325 /*
1326 * Preserve the current error message since an init function might
1327 * call into the dynamic linker and overwrite it.
1328 */
1329 saved_msg = errmsg_save();
1330 STAILQ_FOREACH(elm, list, link) {
1331 dbg("calling init function for %s", elm->obj->path);
1332 (*elm->obj->init)();
1333 }
1334 errmsg_restore(saved_msg);
1335}
1336
1337static void
1338objlist_clear(Objlist *list)
1339{
1340 Objlist_Entry *elm;
1341
1342 while (!STAILQ_EMPTY(list)) {
1343 elm = STAILQ_FIRST(list);
1344 STAILQ_REMOVE_HEAD(list, link);
1345 free(elm);
1346 }
1347}
1348
1349static Objlist_Entry *
1350objlist_find(Objlist *list, const Obj_Entry *obj)
1351{
1352 Objlist_Entry *elm;
1353
1354 STAILQ_FOREACH(elm, list, link)
1355 if (elm->obj == obj)
1356 return elm;
1357 return NULL;
1358}
1359
1360static void
1361objlist_init(Objlist *list)
1362{
1363 STAILQ_INIT(list);
1364}
1365
1366static void
1367objlist_push_head(Objlist *list, Obj_Entry *obj)
1368{
1369 Objlist_Entry *elm;
1370
1371 elm = NEW(Objlist_Entry);
1372 elm->obj = obj;
1373 STAILQ_INSERT_HEAD(list, elm, link);
1374}
1375
1376static void
1377objlist_push_tail(Objlist *list, Obj_Entry *obj)
1378{
1379 Objlist_Entry *elm;
1380
1381 elm = NEW(Objlist_Entry);
1382 elm->obj = obj;
1383 STAILQ_INSERT_TAIL(list, elm, link);
1384}
1385
1386static void
1387objlist_remove(Objlist *list, Obj_Entry *obj)
1388{
1389 Objlist_Entry *elm;
1390
1391 if ((elm = objlist_find(list, obj)) != NULL) {
1392 STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
1393 free(elm);
1394 }
1395}
1396
1397/*
1398 * Remove all of the unreferenced objects from "list".
1399 */
1400static void
1401objlist_remove_unref(Objlist *list)
1402{
1403 Objlist newlist;
1404 Objlist_Entry *elm;
1405
1406 STAILQ_INIT(&newlist);
1407 while (!STAILQ_EMPTY(list)) {
1408 elm = STAILQ_FIRST(list);
1409 STAILQ_REMOVE_HEAD(list, link);
1410 if (elm->obj->refcount == 0)
1411 free(elm);
1412 else
1413 STAILQ_INSERT_TAIL(&newlist, elm, link);
1414 }
1415 *list = newlist;
1416}
1417
1418/*
1419 * Relocate newly-loaded shared objects. The argument is a pointer to
1420 * the Obj_Entry for the first such object. All objects from the first
1421 * to the end of the list of objects are relocated. Returns 0 on success,
1422 * or -1 on failure.
1423 */
1424static int
1425relocate_objects(Obj_Entry *first, bool bind_now)
1426{
1427 Obj_Entry *obj;
1428
1429 for (obj = first; obj != NULL; obj = obj->next) {
1430 if (obj != &obj_rtld)
1431 dbg("relocating \"%s\"", obj->path);
1432 if (obj->nbuckets == 0 || obj->nchains == 0 || obj->buckets == NULL ||
1433 obj->symtab == NULL || obj->strtab == NULL) {
1434 _rtld_error("%s: Shared object has no run-time symbol table",
1435 obj->path);
1436 return -1;
1437 }
1438
1439 if (obj->textrel) {
1440 /* There are relocations to the write-protected text segment. */
1441 if (mprotect(obj->mapbase, obj->textsize,
1442 PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
1443 _rtld_error("%s: Cannot write-enable text segment: %s",
1444 obj->path, strerror(errno));
1445 return -1;
1446 }
1447 }
1448
1449 /* Process the non-PLT relocations. */
1450 if (reloc_non_plt(obj, &obj_rtld))
1451 return -1;
1452
1453 if (obj->textrel) { /* Re-protected the text segment. */
1454 if (mprotect(obj->mapbase, obj->textsize,
1455 PROT_READ|PROT_EXEC) == -1) {
1456 _rtld_error("%s: Cannot write-protect text segment: %s",
1457 obj->path, strerror(errno));
1458 return -1;
1459 }
1460 }
1461
1462 /* Process the PLT relocations. */
1463 if (reloc_plt(obj) == -1)
1464 return -1;
1465 /* Relocate the jump slots if we are doing immediate binding. */
1466 if (bind_now)
1467 if (reloc_jmpslots(obj) == -1)
1468 return -1;
1469
1470
1471 /*
1472 * Set up the magic number and version in the Obj_Entry. These
1473 * were checked in the crt1.o from the original ElfKit, so we
1474 * set them for backward compatibility.
1475 */
1476 obj->magic = RTLD_MAGIC;
1477 obj->version = RTLD_VERSION;
1478
1479 /* Set the special PLT or GOT entries. */
1480 init_pltgot(obj);
1481 }
1482
1483 return 0;
1484}
1485
1486/*
1487 * Cleanup procedure. It will be called (by the atexit mechanism) just
1488 * before the process exits.
1489 */
1490static void
1491rtld_exit(void)
1492{
1493 Obj_Entry *obj;
1494
1495 dbg("rtld_exit()");
1496 /* Clear all the reference counts so the fini functions will be called. */
1497 for (obj = obj_list; obj != NULL; obj = obj->next)
1498 obj->refcount = 0;
1499 objlist_call_fini(&list_fini);
1500 /* No need to remove the items from the list, since we are exiting. */
1501}
1502
1503static void *
1504path_enumerate(const char *path, path_enum_proc callback, void *arg)
1505{
1506 if (path == NULL)
1507 return (NULL);
1508
1509 path += strspn(path, ":;");
1510 while (*path != '\0') {
1511 size_t len;
1512 char *res;
1513
1514 len = strcspn(path, ":;");
1515 res = callback(path, len, arg);
1516
1517 if (res != NULL)
1518 return (res);
1519
1520 path += len;
1521 path += strspn(path, ":;");
1522 }
1523
1524 return (NULL);
1525}
1526
1527struct try_library_args {
1528 const char *name;
1529 size_t namelen;
1530 char *buffer;
1531 size_t buflen;
1532};
1533
1534static void *
1535try_library_path(const char *dir, size_t dirlen, void *param)
1536{
1537 struct try_library_args *arg;
1538
1539 arg = param;
1540 if (*dir == '/' || trust) {
1541 char *pathname;
1542
1543 if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
1544 return (NULL);
1545
1546 pathname = arg->buffer;
1547 strncpy(pathname, dir, dirlen);
1548 pathname[dirlen] = '/';
1549 strcpy(pathname + dirlen + 1, arg->name);
1550
1551 dbg(" Trying \"%s\"", pathname);
1552 if (access(pathname, F_OK) == 0) { /* We found it */
1553 pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
1554 strcpy(pathname, arg->buffer);
1555 return (pathname);
1556 }
1557 }
1558 return (NULL);
1559}
1560
1561static char *
1562search_library_path(const char *name, const char *path)
1563{
1564 char *p;
1565 struct try_library_args arg;
1566
1567 if (path == NULL)
1568 return NULL;
1569
1570 arg.name = name;
1571 arg.namelen = strlen(name);
1572 arg.buffer = xmalloc(PATH_MAX);
1573 arg.buflen = PATH_MAX;
1574
1575 p = path_enumerate(path, try_library_path, &arg);
1576
1577 free(arg.buffer);
1578
1579 return (p);
1580}
1581
1582int
1583dlclose(void *handle)
1584{
1585 Obj_Entry *root;
1586
1587 wlock_acquire();
1588 root = dlcheck(handle);
1589 if (root == NULL) {
1590 wlock_release();
1591 return -1;
1592 }
1593
1594 /* Unreference the object and its dependencies. */
1595 root->dl_refcount--;
1596 unref_dag(root);
1597
1598 if (root->refcount == 0) {
1599 /*
1600 * The object is no longer referenced, so we must unload it.
1601 * First, call the fini functions with no locks held.
1602 */
1603 wlock_release();
1604 objlist_call_fini(&list_fini);
1605 wlock_acquire();
1606 objlist_remove_unref(&list_fini);
1607
1608 /* Finish cleaning up the newly-unreferenced objects. */
1609 GDB_STATE(RT_DELETE,&root->linkmap);
1610 unload_object(root);
1611 GDB_STATE(RT_CONSISTENT,NULL);
1612 }
1613 wlock_release();
1614 return 0;
1615}
1616
1617const char *
1618dlerror(void)
1619{
1620 char *msg = error_message;
1621 error_message = NULL;
1622 return msg;
1623}
1624
1625/*
1626 * This function is deprecated and has no effect.
1627 */
1628void
1629dllockinit(void *context,
1630 void *(*lock_create)(void *context),
1631 void (*rlock_acquire)(void *lock),
1632 void (*wlock_acquire)(void *lock),
1633 void (*lock_release)(void *lock),
1634 void (*lock_destroy)(void *lock),
1635 void (*context_destroy)(void *context))
1636{
1637 static void *cur_context;
1638 static void (*cur_context_destroy)(void *);
1639
1640 /* Just destroy the context from the previous call, if necessary. */
1641 if (cur_context_destroy != NULL)
1642 cur_context_destroy(cur_context);
1643 cur_context = context;
1644 cur_context_destroy = context_destroy;
1645}
1646
1647void *
1648dlopen(const char *name, int mode)
1649{
1650 Obj_Entry **old_obj_tail;
1651 Obj_Entry *obj;
1652 Objlist initlist;
1653 int result;
1654
1655 ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
1656 if (ld_tracing != NULL)
1657 environ = (char **)*get_program_var_addr("environ");
1658
1659 objlist_init(&initlist);
1660
1661 wlock_acquire();
1662 GDB_STATE(RT_ADD,NULL);
1663
1664 old_obj_tail = obj_tail;
1665 obj = NULL;
1666 if (name == NULL) {
1667 obj = obj_main;
1668 obj->refcount++;
1669 } else {
1670 char *path = find_library(name, obj_main);
1671 if (path != NULL)
1672 obj = load_object(path);
1673 }
1674
1675 if (obj) {
1676 obj->dl_refcount++;
1677 if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
1678 objlist_push_tail(&list_global, obj);
1679 mode &= RTLD_MODEMASK;
1680 if (*old_obj_tail != NULL) { /* We loaded something new. */
1681 assert(*old_obj_tail == obj);
1682
1683 result = load_needed_objects(obj);
1684 if (result != -1 && ld_tracing)
1685 goto trace;
1686
1687 if (result == -1 ||
1688 (init_dag(obj), relocate_objects(obj, mode == RTLD_NOW)) == -1) {
1689 obj->dl_refcount--;
1690 unref_dag(obj);
1691 if (obj->refcount == 0)
1692 unload_object(obj);
1693 obj = NULL;
1694 } else {
1695 /* Make list of init functions to call. */
1696 initlist_add_objects(obj, &obj->next, &initlist);
1697 }
1698 } else if (ld_tracing)
1699 goto trace;
1700 }
1701
1702 GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
1703
1704 /* Call the init functions with no locks held. */
1705 wlock_release();
1706 objlist_call_init(&initlist);
1707 wlock_acquire();
1708 objlist_clear(&initlist);
1709 wlock_release();
1710 return obj;
1711trace:
1712 trace_loaded_objects(obj);
1713 wlock_release();
1714 exit(0);
1715}
1716
1717void *
1718dlsym(void *handle, const char *name)
1719{
1720 const Obj_Entry *obj;
1721 unsigned long hash;
1722 const Elf_Sym *def;
1723 const Obj_Entry *defobj;
1724
1725 hash = elf_hash(name);
1726 def = NULL;
1727 defobj = NULL;
1728
1729 rlock_acquire();
1730 if (handle == NULL || handle == RTLD_NEXT ||
1731 handle == RTLD_DEFAULT || handle == RTLD_SELF) {
1732 void *retaddr;
1733
1734 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1735 if ((obj = obj_from_addr(retaddr)) == NULL) {
1736 _rtld_error("Cannot determine caller's shared object");
1737 rlock_release();
1738 return NULL;
1739 }
1740 if (handle == NULL) { /* Just the caller's shared object. */
1741 def = symlook_obj(name, hash, obj, true);
1742 defobj = obj;
1743 } else if (handle == RTLD_NEXT || /* Objects after caller's */
1744 handle == RTLD_SELF) { /* ... caller included */
1745 if (handle == RTLD_NEXT)
1746 obj = obj->next;
1747 for (; obj != NULL; obj = obj->next) {
1748 if ((def = symlook_obj(name, hash, obj, true)) != NULL) {
1749 defobj = obj;
1750 break;
1751 }
1752 }
1753 } else {
1754 assert(handle == RTLD_DEFAULT);
1755 def = symlook_default(name, hash, obj, &defobj, true);
1756 }
1757 } else {
1758 if ((obj = dlcheck(handle)) == NULL) {
1759 rlock_release();
1760 return NULL;
1761 }
1762
1763 if (obj->mainprog) {
1764 DoneList donelist;
1765
1766 /* Search main program and all libraries loaded by it. */
1767 donelist_init(&donelist);
1768 def = symlook_list(name, hash, &list_main, &defobj, true,
1769 &donelist);
1770 } else {
1771 /*
1772 * XXX - This isn't correct. The search should include the whole
1773 * DAG rooted at the given object.
1774 */
1775 def = symlook_obj(name, hash, obj, true);
1776 defobj = obj;
1777 }
1778 }
1779
1780 if (def != NULL) {
1781 rlock_release();
1782 return defobj->relocbase + def->st_value;
1783 }
1784
1785 _rtld_error("Undefined symbol \"%s\"", name);
1786 rlock_release();
1787 return NULL;
1788}
1789
1790int
1791dladdr(const void *addr, Dl_info *info)
1792{
1793 const Obj_Entry *obj;
1794 const Elf_Sym *def;
1795 void *symbol_addr;
1796 unsigned long symoffset;
1797
1798 rlock_acquire();
1799 obj = obj_from_addr(addr);
1800 if (obj == NULL) {
1801 _rtld_error("No shared object contains address");
1802 rlock_release();
1803 return 0;
1804 }
1805 info->dli_fname = obj->path;
1806 info->dli_fbase = obj->mapbase;
1807 info->dli_saddr = (void *)0;
1808 info->dli_sname = NULL;
1809
1810 /*
1811 * Walk the symbol list looking for the symbol whose address is
1812 * closest to the address sent in.
1813 */
1814 for (symoffset = 0; symoffset < obj->nchains; symoffset++) {
1815 def = obj->symtab + symoffset;
1816
1817 /*
1818 * For skip the symbol if st_shndx is either SHN_UNDEF or
1819 * SHN_COMMON.
1820 */
1821 if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
1822 continue;
1823
1824 /*
1825 * If the symbol is greater than the specified address, or if it
1826 * is further away from addr than the current nearest symbol,
1827 * then reject it.
1828 */
1829 symbol_addr = obj->relocbase + def->st_value;
1830 if (symbol_addr > addr || symbol_addr < info->dli_saddr)
1831 continue;
1832
1833 /* Update our idea of the nearest symbol. */
1834 info->dli_sname = obj->strtab + def->st_name;
1835 info->dli_saddr = symbol_addr;
1836
1837 /* Exact match? */
1838 if (info->dli_saddr == addr)
1839 break;
1840 }
1841 rlock_release();
1842 return 1;
1843}
1844
1845int
1846dlinfo(void *handle, int request, void *p)
1847{
1848 const Obj_Entry *obj;
1849 int error;
1850
1851 rlock_acquire();
1852
1853 if (handle == NULL || handle == RTLD_SELF) {
1854 void *retaddr;
1855
1856 retaddr = __builtin_return_address(0); /* __GNUC__ only */
1857 if ((obj = obj_from_addr(retaddr)) == NULL)
1858 _rtld_error("Cannot determine caller's shared object");
1859 } else
1860 obj = dlcheck(handle);
1861
1862 if (obj == NULL) {
1863 rlock_release();
1864 return (-1);
1865 }
1866
1867 error = 0;
1868 switch (request) {
1869 case RTLD_DI_LINKMAP:
1870 *((struct link_map const **)p) = &obj->linkmap;
1871 break;
1872 case RTLD_DI_ORIGIN:
1873 error = rtld_dirname(obj->path, p);
1874 break;
1875
1876 case RTLD_DI_SERINFOSIZE:
1877 case RTLD_DI_SERINFO:
1878 error = do_search_info(obj, request, (struct dl_serinfo *)p);
1879 break;
1880
1881 default:
1882 _rtld_error("Invalid request %d passed to dlinfo()", request);
1883 error = -1;
1884 }
1885
1886 rlock_release();
1887
1888 return (error);
1889}
1890
1891struct fill_search_info_args {
1892 int request;
1893 unsigned int flags;
1894 Dl_serinfo *serinfo;
1895 Dl_serpath *serpath;
1896 char *strspace;
1897};
1898
1899static void *
1900fill_search_info(const char *dir, size_t dirlen, void *param)
1901{
1902 struct fill_search_info_args *arg;
1903
1904 arg = param;
1905
1906 if (arg->request == RTLD_DI_SERINFOSIZE) {
1907 arg->serinfo->dls_cnt ++;
1908 arg->serinfo->dls_size += dirlen + 1;
1909 } else {
1910 struct dl_serpath *s_entry;
1911
1912 s_entry = arg->serpath;
1913 s_entry->dls_name = arg->strspace;
1914 s_entry->dls_flags = arg->flags;
1915
1916 strncpy(arg->strspace, dir, dirlen);
1917 arg->strspace[dirlen] = '\0';
1918
1919 arg->strspace += dirlen + 1;
1920 arg->serpath++;
1921 }
1922
1923 return (NULL);
1924}
1925
1926static int
1927do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
1928{
1929 struct dl_serinfo _info;
1930 struct fill_search_info_args args;
1931
1932 args.request = RTLD_DI_SERINFOSIZE;
1933 args.serinfo = &_info;
1934
1935 _info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
1936 _info.dls_cnt = 0;
1937
1938 path_enumerate(ld_library_path, fill_search_info, &args);
1939 path_enumerate(obj->rpath, fill_search_info, &args);
1940 path_enumerate(gethints(), fill_search_info, &args);
1941 path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
1942
1943
1944 if (request == RTLD_DI_SERINFOSIZE) {
1945 info->dls_size = _info.dls_size;
1946 info->dls_cnt = _info.dls_cnt;
1947 return (0);
1948 }
1949
1950 if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
1951 _rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
1952 return (-1);
1953 }
1954
1955 args.request = RTLD_DI_SERINFO;
1956 args.serinfo = info;
1957 args.serpath = &info->dls_serpath[0];
1958 args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
1959
1960 args.flags = LA_SER_LIBPATH;
1961 if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
1962 return (-1);
1963
1964 args.flags = LA_SER_RUNPATH;
1965 if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
1966 return (-1);
1967
1968 args.flags = LA_SER_CONFIG;
1969 if (path_enumerate(gethints(), fill_search_info, &args) != NULL)
1970 return (-1);
1971
1972 args.flags = LA_SER_DEFAULT;
1973 if (path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
1974 return (-1);
1975 return (0);
1976}
1977
1978static int
1979rtld_dirname(const char *path, char *bname)
1980{
1981 const char *endp;
1982
1983 /* Empty or NULL string gets treated as "." */
1984 if (path == NULL || *path == '\0') {
1985 bname[0] = '.';
1986 bname[1] = '\0';
1987 return (0);
1988 }
1989
1990 /* Strip trailing slashes */
1991 endp = path + strlen(path) - 1;
1992 while (endp > path && *endp == '/')
1993 endp--;
1994
1995 /* Find the start of the dir */
1996 while (endp > path && *endp != '/')
1997 endp--;
1998
1999 /* Either the dir is "/" or there are no slashes */
2000 if (endp == path) {
2001 bname[0] = *endp == '/' ? '/' : '.';
2002 bname[1] = '\0';
2003 return (0);
2004 } else {
2005 do {
2006 endp--;
2007 } while (endp > path && *endp == '/');
2008 }
2009
2010 if (endp - path + 2 > PATH_MAX)
2011 {
2012 _rtld_error("Filename is too long: %s", path);
2013 return(-1);
2014 }
2015
2016 strncpy(bname, path, endp - path + 1);
2017 bname[endp - path + 1] = '\0';
2018 return (0);
2019}
2020
2021static void
2022linkmap_add(Obj_Entry *obj)
2023{
2024 struct link_map *l = &obj->linkmap;
2025 struct link_map *prev;
2026
2027 obj->linkmap.l_name = obj->path;
2028 obj->linkmap.l_addr = obj->mapbase;
2029 obj->linkmap.l_ld = obj->dynamic;
2030#ifdef __mips__
2031 /* GDB needs load offset on MIPS to use the symbols */
2032 obj->linkmap.l_offs = obj->relocbase;
2033#endif
2034
2035 if (r_debug.r_map == NULL) {
2036 r_debug.r_map = l;
2037 return;
2038 }
2039
2040 /*
2041 * Scan to the end of the list, but not past the entry for the
2042 * dynamic linker, which we want to keep at the very end.
2043 */
2044 for (prev = r_debug.r_map;
2045 prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
2046 prev = prev->l_next)
2047 ;
2048
2049 /* Link in the new entry. */
2050 l->l_prev = prev;
2051 l->l_next = prev->l_next;
2052 if (l->l_next != NULL)
2053 l->l_next->l_prev = l;
2054 prev->l_next = l;
2055}
2056
2057static void
2058linkmap_delete(Obj_Entry *obj)
2059{
2060 struct link_map *l = &obj->linkmap;
2061
2062 if (l->l_prev == NULL) {
2063 if ((r_debug.r_map = l->l_next) != NULL)
2064 l->l_next->l_prev = NULL;
2065 return;
2066 }
2067
2068 if ((l->l_prev->l_next = l->l_next) != NULL)
2069 l->l_next->l_prev = l->l_prev;
2070}
2071
2072/*
2073 * Function for the debugger to set a breakpoint on to gain control.
2074 *
2075 * The two parameters allow the debugger to easily find and determine
2076 * what the runtime loader is doing and to whom it is doing it.
2077 *
2078 * When the loadhook trap is hit (r_debug_state, set at program
2079 * initialization), the arguments can be found on the stack:
2080 *
2081 * +8 struct link_map *m
2082 * +4 struct r_debug *rd
2083 * +0 RetAddr
2084 */
2085void
2086r_debug_state(struct r_debug* rd, struct link_map *m)
2087{
2088}
2089
2090/*
2091 * Get address of the pointer variable in the main program.
2092 */
2093static const void **
2094get_program_var_addr(const char *name)
2095{
2096 const Obj_Entry *obj;
2097 unsigned long hash;
2098
2099 hash = elf_hash(name);
2100 for (obj = obj_main; obj != NULL; obj = obj->next) {
2101 const Elf_Sym *def;
2102
2103 if ((def = symlook_obj(name, hash, obj, false)) != NULL) {
2104 const void **addr;
2105
2106 addr = (const void **)(obj->relocbase + def->st_value);
2107 return addr;
2108 }
2109 }
2110 return NULL;
2111}
2112
2113/*
2114 * Set a pointer variable in the main program to the given value. This
2115 * is used to set key variables such as "environ" before any of the
2116 * init functions are called.
2117 */
2118static void
2119set_program_var(const char *name, const void *value)
2120{
2121 const void **addr;
2122
2123 if ((addr = get_program_var_addr(name)) != NULL) {
2124 dbg("\"%s\": *%p <-- %p", name, addr, value);
2125 *addr = value;
2126 }
2127}
2128
2129/*
2130 * Given a symbol name in a referencing object, find the corresponding
2131 * definition of the symbol. Returns a pointer to the symbol, or NULL if
2132 * no definition was found. Returns a pointer to the Obj_Entry of the
2133 * defining object via the reference parameter DEFOBJ_OUT.
2134 */
2135static const Elf_Sym *
2136symlook_default(const char *name, unsigned long hash,
2137 const Obj_Entry *refobj, const Obj_Entry **defobj_out, bool in_plt)
2138{
2139 DoneList donelist;
2140 const Elf_Sym *def;
2141 const Elf_Sym *symp;
2142 const Obj_Entry *obj;
2143 const Obj_Entry *defobj;
2144 const Objlist_Entry *elm;
2145 def = NULL;
2146 defobj = NULL;
2147 donelist_init(&donelist);
2148
2149 /* Look first in the referencing object if linked symbolically. */
2150 if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
2151 symp = symlook_obj(name, hash, refobj, in_plt);
2152 if (symp != NULL) {
2153 def = symp;
2154 defobj = refobj;
2155 }
2156 }
2157
2158 /* Search all objects loaded at program start up. */
2159 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2160 symp = symlook_list(name, hash, &list_main, &obj, in_plt, &donelist);
2161 if (symp != NULL &&
2162 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2163 def = symp;
2164 defobj = obj;
2165 }
2166 }
2167
2168 /* Search all DAGs whose roots are RTLD_GLOBAL objects. */
2169 STAILQ_FOREACH(elm, &list_global, link) {
2170 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2171 break;
2172 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2173 &donelist);
2174 if (symp != NULL &&
2175 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2176 def = symp;
2177 defobj = obj;
2178 }
2179 }
2180
2181 /* Search all dlopened DAGs containing the referencing object. */
2182 STAILQ_FOREACH(elm, &refobj->dldags, link) {
2183 if (def != NULL && ELF_ST_BIND(def->st_info) != STB_WEAK)
2184 break;
2185 symp = symlook_list(name, hash, &elm->obj->dagmembers, &obj, in_plt,
2186 &donelist);
2187 if (symp != NULL &&
2188 (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK)) {
2189 def = symp;
2190 defobj = obj;
2191 }
2192 }
2193
2194 /*
2195 * Search the dynamic linker itself, and possibly resolve the
2196 * symbol from there. This is how the application links to
2197 * dynamic linker services such as dlopen. Only the values listed
2198 * in the "exports" array can be resolved from the dynamic linker.
2199 */
2200 if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
2201 symp = symlook_obj(name, hash, &obj_rtld, in_plt);
2202 if (symp != NULL && is_exported(symp)) {
2203 def = symp;
2204 defobj = &obj_rtld;
2205 }
2206 }
2207
2208 if (def != NULL)
2209 *defobj_out = defobj;
2210 return def;
2211}
2212
2213static const Elf_Sym *
2214symlook_list(const char *name, unsigned long hash, Objlist *objlist,
2215 const Obj_Entry **defobj_out, bool in_plt, DoneList *dlp)
2216{
2217 const Elf_Sym *symp;
2218 const Elf_Sym *def;
2219 const Obj_Entry *defobj;
2220 const Objlist_Entry *elm;
2221
2222 def = NULL;
2223 defobj = NULL;
2224 STAILQ_FOREACH(elm, objlist, link) {
2225 if (donelist_check(dlp, elm->obj))
2226 continue;
2227 if ((symp = symlook_obj(name, hash, elm->obj, in_plt)) != NULL) {
2228 if (def == NULL || ELF_ST_BIND(symp->st_info) != STB_WEAK) {
2229 def = symp;
2230 defobj = elm->obj;
2231 if (ELF_ST_BIND(def->st_info) != STB_WEAK)
2232 break;
2233 }
2234 }
2235 }
2236 if (def != NULL)
2237 *defobj_out = defobj;
2238 return def;
2239}
2240
2241/*
2242 * Search the symbol table of a single shared object for a symbol of
2243 * the given name. Returns a pointer to the symbol, or NULL if no
2244 * definition was found.
2245 *
2246 * The symbol's hash value is passed in for efficiency reasons; that
2247 * eliminates many recomputations of the hash value.
2248 */
2249const Elf_Sym *
2250symlook_obj(const char *name, unsigned long hash, const Obj_Entry *obj,
2251 bool in_plt)
2252{
2253 if (obj->buckets != NULL) {
2254 unsigned long symnum = obj->buckets[hash % obj->nbuckets];
2255
2256 while (symnum != STN_UNDEF) {
2257 const Elf_Sym *symp;
2258 const char *strp;
2259
2260 if (symnum >= obj->nchains)
2261 return NULL; /* Bad object */
2262 symp = obj->symtab + symnum;
2263 strp = obj->strtab + symp->st_name;
2264
2265 if (name[0] == strp[0] && strcmp(name, strp) == 0)
2266 return symp->st_shndx != SHN_UNDEF ||
2267 (!in_plt && symp->st_value != 0 &&
2268 ELF_ST_TYPE(symp->st_info) == STT_FUNC) ? symp : NULL;
2269
2270 symnum = obj->chains[symnum];
2271 }
2272 }
2273 return NULL;
2274}
2275
2276static void
2277trace_loaded_objects(Obj_Entry *obj)
2278{
2279 char *fmt1, *fmt2, *fmt, *main_local;
2280 int c;
2281
2282 if ((main_local = getenv("LD_TRACE_LOADED_OBJECTS_PROGNAME")) == NULL)
2283 main_local = "";
2284
2285 if ((fmt1 = getenv("LD_TRACE_LOADED_OBJECTS_FMT1")) == NULL)
2286 fmt1 = "\t%o => %p (%x)\n";
2287
2288 if ((fmt2 = getenv("LD_TRACE_LOADED_OBJECTS_FMT2")) == NULL)
2289 fmt2 = "\t%o (%x)\n";
2290
2291 for (; obj; obj = obj->next) {
2292 Needed_Entry *needed;
2293 char *name, *path;
2294 bool is_lib;
2295
2296 for (needed = obj->needed; needed; needed = needed->next) {
2297 if (needed->obj != NULL) {
2298 if (needed->obj->traced)
2299 continue;
2300 needed->obj->traced = true;
2301 path = needed->obj->path;
2302 } else
2303 path = "not found";
2304
2305 name = (char *)obj->strtab + needed->name;
2306 is_lib = strncmp(name, "lib", 3) == 0; /* XXX - bogus */
2307
2308 fmt = is_lib ? fmt1 : fmt2;
2309 while ((c = *fmt++) != '\0') {
2310 switch (c) {
2311 default:
2312 putchar(c);
2313 continue;
2314 case '\\':
2315 switch (c = *fmt) {
2316 case '\0':
2317 continue;
2318 case 'n':
2319 putchar('\n');
2320 break;
2321 case 't':
2322 putchar('\t');
2323 break;
2324 }
2325 break;
2326 case '%':
2327 switch (c = *fmt) {
2328 case '\0':
2329 continue;
2330 case '%':
2331 default:
2332 putchar(c);
2333 break;
2334 case 'A':
2335 printf("%s", main_local);
2336 break;
2337 case 'a':
2338 printf("%s", obj_main->path);
2339 break;
2340 case 'o':
2341 printf("%s", name);
2342 break;
2343#if 0
2344 case 'm':
2345 printf("%d", sodp->sod_major);
2346 break;
2347 case 'n':
2348 printf("%d", sodp->sod_minor);
2349 break;
2350#endif
2351 case 'p':
2352 printf("%s", path);
2353 break;
2354 case 'x':
2355 printf("%p", needed->obj ? needed->obj->mapbase : 0);
2356 break;
2357 }
2358 break;
2359 }
2360 ++fmt;
2361 }
2362 }
2363 }
2364}
2365
2366/*
2367 * Unload a dlopened object and its dependencies from memory and from
2368 * our data structures. It is assumed that the DAG rooted in the
2369 * object has already been unreferenced, and that the object has a
2370 * reference count of 0.
2371 */
2372static void
2373unload_object(Obj_Entry *root)
2374{
2375 Obj_Entry *obj;
2376 Obj_Entry **linkp;
2377
2378 assert(root->refcount == 0);
2379
2380 /*
2381 * Pass over the DAG removing unreferenced objects from
2382 * appropriate lists.
2383 */
2384 unlink_object(root);
2385
2386 /* Unmap all objects that are no longer referenced. */
2387 linkp = &obj_list->next;
2388 while ((obj = *linkp) != NULL) {
2389 if (obj->refcount == 0) {
2390 dbg("unloading \"%s\"", obj->path);
2391 munmap(obj->mapbase, obj->mapsize);
2392 linkmap_delete(obj);
2393 *linkp = obj->next;
2394 obj_count--;
2395 obj_free(obj);
2396 } else
2397 linkp = &obj->next;
2398 }
2399 obj_tail = linkp;
2400}
2401
2402static void
2403unlink_object(Obj_Entry *root)
2404{
2405 const Needed_Entry *needed;
2406 Objlist_Entry *elm;
2407
2408 if (root->refcount == 0) {
2409 /* Remove the object from the RTLD_GLOBAL list. */
2410 objlist_remove(&list_global, root);
2411
2412 /* Remove the object from all objects' DAG lists. */
2413 STAILQ_FOREACH(elm, &root->dagmembers , link)
2414 objlist_remove(&elm->obj->dldags, root);
2415 }
2416
2417 for (needed = root->needed; needed != NULL; needed = needed->next)
2418 if (needed->obj != NULL)
2419 unlink_object(needed->obj);
2420}
2421
2422static void
2423unref_dag(Obj_Entry *root)
2424{
2425 const Needed_Entry *needed;
2426
2427 if (root->refcount == 0)
2428 return;
2429 root->refcount--;
2430 if (root->refcount == 0)
2431 for (needed = root->needed; needed != NULL; needed = needed->next)
2432 if (needed->obj != NULL)
2433 unref_dag(needed->obj);
2434}